Park Systems NX20 User Manual

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Park Systems | The Most Accurate Atomic Force Microscope

Park NX20

User's Manual

Version 2.3

2017-01-18

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Page 3 Park Systems Corp. Park Systems is not responsible for any mistakes or damages that may occur either accidentally or willfully, as a result of using this manual.
Page 4 Preface The Scanning Probe Microscope (SPM) is not only at the top of the list of equipment pioneering the nano scale world, it is also the most fundamental technology. Succeeding the first generation optical microscope, and the second generation electron microscope, the SPM has every right to be known as a “third generation” microscope since it enables us to look into the nano scale world.
Page 7 NX20 for your safety. CAUTION! If the user operates the NX20 in a manner not specified in this User’s Manual, serious damage to the instrument may result. Each component such as MOD (Optional), Temperature Control Unit (Optional), PC, Monitor, Vacuum Pump(Optional) separately provides the manual accordingly.
Page 9 Safety Precautions of NX20 system 1. Hazard Labels On the NX20 system, there are hazard labels on the position for hazard possibilities. Caution must be taken for the each hazard label warning. Symbol Description “ON” (power) To indicate connection to the mains, at least for main switches or their positions, and all those cases where safety is involved.
Page 10 NX20 User’s Manual 1-1. Electrical Hazard Label The Electrical Hazard label notifies the area that might cause electrical damage to the system of to the personnel. Care must be taken. The Electrical Hazard label is attached to the areas listed below.
Page 11 The NX20 design is compatible within the related SEMI standards. 2-1. Center of Gravity Figure 3 below shows the center of gravity for NX20. The load of each leg at the acoustic enclosure of the NX20 is 160kg(352.7lb). Figure 1. CG for NX20...
Page 12 NX20 User’s Manual 2-2. Dimension of NX20 Components The table below shows the dimensions for each components of NX20. Width Depth Height Items (mm) (mm) (mm) AFM Controller Cabinet Temperature Control Controller MOD Controller Table 1400 Vacuum Pump Vacuum Regulator Table 1.
Page 13 Safety Precautions of NX20 system 3-2. Door Interlock Switch 3-2-1. Acoustic Enclosure The acoustic enclosure (A/E) side door interlock sensor disables the X, Y, Z Stage and Focus stage motors controlled by the AFM controller. When the door is opened, the corresponding safety relay is activated to give the “motor power off”...
Page 14 NX20 User’s Manual WARNING! Operating the AFM with the door open can result in finger and hand injuries. NOTE! The “The door is opened” message is generated on the monitor screen, and the AFM is not operated because the door interlock with the door open works. Please...
Page 15 Before the power is turned on, the power selections for the individual components need to be inspected. The voltage selector switch is located on the rear panel of the NX20 Control Electronics, and it can be set to the following voltages: 100 V, 120 V, 220 V, or 240 V.
Page 16 NX20 User’s Manual CAUTION! All parts in the NX20 system should be handled with extreme care. If not handled properly, these parts can be easily damaged as they are made of fragile electromagnetic equipment. CAUTION! An EMI filter must be installed to maintain operating safety and meet EMC (Electromagnetic Compatibility Compliance).
Page 17 Figure 4. General Information of NX20 Main Body Equipped with AE 5-2. NX20 AFM Controller The general specification of the NX20 control electronics is informed on the name plate, located on the cabinet surrounding the AFM controller, as shown in figure...
Page 18 NX20 User’s Manual Figure 5. General Information of NX20 AFM Controller 5-3. Temperature Controller(Optional) The general specification of the Temperature Controller for temperature is informed on the nameplate, located on the TC-AE, as shown in figure below. Figure 6. General Information of Temperature Controller...
Page 19: Table Of Contents
Contents Contents CHAPTER 1. INTRODUCTION TO NX20 ................1 1-1. Scanning Probe Microscope ..................1 1-2. Atomic Force Microscope ................... 1 1-3. Park Systems AFM ...................... 6 CHAPTER 2. COMPONENTS OF NX20 ................12 2-1. NX20 Main System ....................13 2-2.
Page 20 NX20 User’s Manual 6-1. Principle of Contact Mode AFM ................121 6-2. Contact mode setup ....................123 6-3. Cantilever Selection ....................123 6-4. Measurement Procedure ..................125 CHAPTER 7. LATERAL FORCE MICROSCOPY (LFM) ..........127 7-1. Principle of Lateral Force Microscopy (LFM) ............127 7-2.
Page 21 Contents 11-1. Principle of Q Control Mode ................. 216 11-2. Q Control User Interface ..................220 11-3. Q Control Procedure ..................... 222 CHAPTER 12. MAGNETIC FORCE MICROSCOPY (MFM)..........223 12-1. Principle of Magnetic Force Microscopy ............223 12-2. Components ......................226 12-3.
Page 23 Figure 2-10. (a) 150mm XY Stage, (b) 200mm XY Stage ..........20 Figure 2-11. X-Y scanner ....................21 Figure 2-12. Sample Chuck of NX20 (Up: For 150mm XY Stage and Bottom: For 200mm XY Stage) ......................23 Figure 2-13. Optical Microscope of NX20 ................ 26...
Page 24 (d) maximum adjust limit ............. 37 Figure 3-1. Vibration Criteria Graph .................. 40 Figure 3-2. Top View of Dimension NX20 with Clearance ..........42 Figure 3-3. Acoustic Enclosure Bottom ................46 Figure 3-4. Electronics, Monitor, Computer Desk Setup ..........47 Figure 3-5.
Page 25 Figure Contents attached.......................... 71 Figure 4-20. SLD beam on the Detector Chip Carrier ............ 72 Figure 5-1. SMARTSCAN User Interface of NX20 ............75 Figure 5-2. Removing NX20 Head ..................77 Figure 5-3. Load Cantilever onto Probehand ..............78 Figure 5-4.
Page 26 NX20 User’s Manual Figure 9-2. (a) Resonant frequency shift (b) Amplitude vs. Z-feedback ....142 Figure 9-3. Conversion to DFM ..................143 Figure 9-4. Resonant frequency setup in DFM ............. 144 Figure 10-1. Spectroscopy Control workspace ............. 146 Figure 10-2. Vision View and expanded Vision View ........... 147 Figure 10-3.
Page 27 Figure Contents Figure 10-32. Thermal analysis spectroscopy control window ........178 Figure 10-33. SThM Reference Calibration ..............180 Figure 10-34. Z Servo Config ..................180 Figure 10-35. Line Scan button with yellow light ON ........... 181 Figure 10-36. Selecting Cantilever type ................. 182 Figure 10-37.
Page 28 NX20 User’s Manual Figure 10-68. Start button for acquiring spectroscopy data ........200 Figure 10-69. Line Scan button with yellow light ON ............ 201 Figure 10-70. Selecting Cantilever Type ................ 202 Figure 10-71. Head Mode button in NC-Mode .............. 202 Figure 10-72.
Page 29 Figure Contents Calibration, Right: After Initial Calibration) ............... 222 Figure 11-10 Deactivate Q Control ................. 222 Figure 12-1. Process of the SPM imaging ..............224 Figure 12-2. Scanning process in MFM mode .............. 225 Figure 12-3 Obtained signals in MFM mode ..............225 Figure 12-4.
Page 30 NX20 User’s Manual Figure 14-2. Diagram of 1) EFM, 2) EFM-DC ..............252 Figure 14-3. (a) Surface height, (b) Surface charge image of TGS single crystal by DC-EFM, (c) Surface height, (d) Surface charge image by conventional EFM .. 253 Figure 14-4.
Page 31 Figure Contents Figure 14-34. After parameter adjustments to synchronize Z height signals ... 281 Figure 14-35-a Figure 14-35-b Figure 14-35-c ............................282 Figure 14-36. Line profiles of SKPM Potential Images ..........282 Figure 14-37-a. Tip bias servo gain=0.1 ................ 283 Figure 14-37-b.
Page 33: Chapter 1. Introduction To Nx20
Chapter 1. Introduction to NX20 Chapter 1. Introduction to NX20 1-1. Scanning Probe Microscope The Scanning Probe Microscope (SPM) proved a prevailing concept wrong, that an atom is too small to be observed with even the best microscope. Now, it has every right to be identified as the third generation microscope, with optical and electron microscopes being the first and second generations respectively.
Page 34 NX20 User’s Manual the Atomic Force Microscope (AFM) which may be used to measure almost any sample, regardless of its electrical properties. As a result, the AFM has greatly extended the SPM’s applicability to all branches of scientific research. Figure 1-1. Diagram of Conventional AFM’s Scanning Instead of a conducting needle, the AFM uses a micro-machined cantilever with a sharp tip to measure a sample’s surface.
Page 35 Chapter 1. Introduction to NX20 horizontal direction (X-Y) and in the vertical direction (Z). It repetitively scans the sample line by line, while the PSPD signal is used to establish a feedback loop which controls the vertical movement of the scanner as the cantilever moves across the sample surface.
Page 36 NX20 User’s Manual The most inconvenient aspect of using the AFM is its slow speed. As mentioned above, since the image is obtained by the tip’s mechanically following a sample’s surface, it is much slower than other microscopes that use electrons or light. The main factors slowing the speed of the AFM are the Z scanner’s response rate and the...
Page 37 Chapter 1. Introduction to NX20 Applied Bias (V) Extension of X axis Figure 1-2. Nonlinearity and Hysteresis (a), and Cross Coupling (b) Observed in Piezoelectric Tube Scanners...
Page 38: Park Systems Afm
The breakthrough that eliminated these cumbersome problems came when the Park Systems SPMs introduced a new concept of separating the Z scanner from the X-Y scanner. The NX system is designed so that the X-Y scanner scans a sample in two-dimensional space, while the Z scanner moves the tip only in the z direction.
Page 39 Chapter 1. Introduction to NX20 rates (10~50Hz) than would be possible with a standard AFM. Because the stacked piezoelectric actuator used for the Z scanner has a very fast response speed, at least 5 kHz, it is able to respond to topographic changes on the sample surface more than 10 times faster than is possible with a conventional tube type scanner.
Page 40 NX20 User’s Manual Figure 1-5 shows a diagram that explains the cantilever movement detection mechanism used in the NX system. This SLD Beam/ & PSPD configuration, which permits the accurate acquisition of stable images at high measurement speeds, satisfies the following two important imaging conditions: First, the PSPD should be able to measure only the deflection of the cantilever without interference from the Z scanner.
Page 41 Chapter 1. Introduction to NX20 the cantilever will be detected, independent of the Z scanner movement. Since there is nothing obstructing the view above the cantilever in the structure, the optical microscope is located on the same axis as the SLD beam that is reflected at the fixed mirror.
Page 42 NX20 User’s Manual NX Head Figure 1-7. Lock Head The NX system not only achieved a structural design change that yielded exemplary SPM efficiency, but also brought many improvements to the electronic controller and to the supporting software. The AFM control unit has a fast, powerful Digital Signal Processor (DSP), high speed ADC/DACs and offers built-in support for Digital lock-in and digital Q control functions without the need for additional instruments .
Page 43 Chapter 1. Introduction to NX20 Figure 1-8. SmartScan™ - Data Acquisition Program Figure 1-9. XEI - Image Processing Program...
Page 44: Chapter 2. Components Of Nx20
NX20 control electronics, a computer and twin monitors. Figure 2-1. NX20 System The NX20 main system is where actual measurements are made, and the NX20 control electronics control the movement of the NX20 main system according to the commands from the computer.
Page 45: Nx20 Main System
Chapter 2. Components of NX20 2-1. NX20 Main System The NX20 main system is divided into three components as shown in Figure 2-2. The following sections explain each component in more detail. Figure 2-2. NX20 Scanning Probe Microcope 2-1-1. Z Stage The Z stage head assembly controls the coarse vertical positioning of the Z scanner with a stepper motor and is used to approach the cantilever near the sample.
Page 46 UL10x, EL20x > 15 ㎛ > 38 ㎛ Z Scanner Stroke Table 2-1. Specifications of NX20 Head The NX20 head is a core component of the Park SYSTEMS AFM and perfors the following functions:  Cantilever Mount  Cantilever Modulation ...
Page 47 PSPD Alignment Knobs Probehand Figure 2-4. Structure of NX20 Head WARNING! Do not disassemble the NX20 head on your own. Park Systems will not be responsible for any personal, physical damage or degraded performance that may result from unauthorized disassembly. Probe hand The probe hand is the part of the AFM head which holds the cantilever.
Page 48 15 m and the long travel head’s Z scanner can move up to 38m. WARNING! Never disassemble the Z scanner on your own. Park Systems will not be responsible for any personal, physical damage or degraded performance that may result from unauthorized disassembly.
Page 49 (SMARTSCAN and the vision program), making location and movement of the beam easy and accurate. 4. Whenever it is necessary to remove the NX20 head from the main frame, it iseasy to do so. This procedure can be accomplished by unlocking the dovetail thumb locks and sliding the NX20 head off the dovetail rail.
Page 50 AFM Beam Detection Array AFMs collect a beam signal after it is reflected from the back side of a cantilever in order to detect the probe’s movement. The NX20 uses an SLD beam with a wavelength of 830nm. ,, Mirror...
Page 51 The motorized X-Y stage can move the sample to a defined location accurately and swiftly. Also, it is very simple to recreate its motion to the same locations. The NX20 can provide two kind of XY stage as mentioned in the following table., The 150mm XY stage is provided by default.
Page 52 Table 2-1. Specifications of NX20 XY Stage  NX20 X-Y scanner The NX20 X-Y scanner that moves the sample in the X-Y plane is a Body Guided Flexure scanner. The X-Y scanner is fabricated from a solid aluminum block. The desired area is cut out from inside the aluminum block, and the lines indicated in Figure 2-11 are fabricated with a special technique called ‘Wire Electric Discharge...
Page 53 X-Y scanner, retain higher scan linearity even for a wide scan range, compared to when a single sensor is used for positioning correction. An X-Y scanner used with the NX20 has ~100 m  ~ 100 m scan range.
Page 54  Sample Chuck The Sample Chuck is where the samples are loaded. Sample chucks for the NX20 are mainly designed for large size wafer samples. However, other samples can be mounted as well. To prevent samples from tilting or moving during the measurement, a vacuum is supplied.
Page 55 Bolt Pin 150mm Guide Bolt Pin Stopper for flat wafer Vacuum Point for Small Sample Magnetic Sample Holder for general Stopper for flat wafer Figure 2-12. Sample Chuck of NX20 (Up: For 150mm XY Stage and Bottom: For 200mm XY Stage)
Page 56 NX20 User’s Manual *Vacuum Valves Each vacuum line is controlled by its valve accordingly. Turning a valve to the 9 o’clock position will turn the vacuum on. Turning a valve to the 12 o’clock position will turn the vacuum off.
Page 57 The optical microscope is attached to the motorized Focus stage, which is controlled via sofware. The Focus stage is used to vertically position the optical microscope so as to observe the cantilever or sample. The NX20 Focus stage has a maximum range of 15mm.
Page 58: Nx20 Control Electronics
Figure 2-13. Optical Microscope of NX20 2-2. NX20 Control Electronics The NX20 main system is divided into three components, the NX20 main system, the Control Electronis, and the computer. The Control Electronics serves as a mediator between the main system and the computer.
Page 59 Chapter 2. Components of NX20 In order to maintain fast, effective communication between the computer and the NX20 main system, an Ethernet connection is used. Analog: AFM Control Signal NX20 Control HV: Scanner Control Signal Ethernet: Main Electronics Communication System...
Page 60 NX20 User’s Manual Connector Purpose Specification Label AUX 5 IN Inputs connector for user- supplied signals. External signals are introduced through these AUX 4 IN connectors can be viewed alongside SPM parameters, each BW 20 kHz, +/- 10V being assigned to a channel AUX 3 IN selectable from the “Input Config”...
Page 61 Chapter 2. Components of NX20  Image Sync. NX20 provides Image Sync outputs (Frame, Line, Pixel) for your experiment Example Pixel, Line, and Frame signals for a 4x4 pixels image are shown in figure 2- 15. The forward (left-to-right) scan order is denoted by numbers, and the backwards (right-to-left) scan order is denoted by letters.
Page 62 NX20 User’s Manual 2-2-1. Power/Fuse Change  Power The power to the NX20 Control Electronics is not free voltage. The procedure for changing the input power voltage follows below: Figure 2-16. Change Power 1. Remove power cord. 2. Pry door open at socket.
Page 63 Chapter 2. Components of NX20 2. Gently lift UP until the entire door lifts up at least 1/4". 3. Once lifted, the door will pivot on its hinges and expose the fuse holder. 4. When the fuse holder is installed in the single fuse position, apply the screwdriver as shown and gently pry up.
Page 64: Computer & Monitor
The Vision program is to observe the cantilever/sample/beam/etc for system operation. See the software manual for further description of the software. The computer is connected to the NX20 Control Electronics via Ethernet cable. The two 23 inch LCD monitors provides 1920×1080 pixels with 32 bit color. These monitors are digitally connected to the computer via SVGA DVI (Digital Video Interface) port.
Page 65: Acoustic And Vibration Isolation System
Chapter 2. Components of NX20 Table 2-9. Speccifications of NX20 Part Name Specification Decoupled XY and Z-scanner Single module flexure XY-scanner with closed-loop control Scanner Scan range of XY-scanner: 50 μm (Optional 100 μm), 10 μm Scan range of Z-scanner: 15 μm (Optional 38μm) XY stage trave rangel: 20 mm ×...
Page 66 NX20 User’s Manual measurements. It is recommended that the NX20 system is placed in an Acoustic Enclosure to block acoustic noise from the surrounding environment, and supported by an Active Vibration Isolation System to block floor vibrations. 2-4-1. Acoustic Enclosure .
Page 67 The AVIS available with the NX20 consumes, in general, under 5W, and in extreme cases a maximum of 50W (70VA). Any AC power point between 115V and 230V (-±...
Page 68 NX20 User’s Manual Figure 2-19. AVIS Controller To expose the adjustment nuts, remove the end covers by undoing the screws shown in Fig 2-20 (a) (2mm hex key). When loaded the upper gap and the lower gap (Fig 2-20 (b)) should be approximately equal.
Page 69 Chapter 2. Components of NX20 Figure 2-20. Isolation Unit adjustment; (a) removing covers, (b) gap checking, (c) spring adjustment, (d) maximum adjust limit...
Page 70: Chapter 3. Installation
Chapter 3. Installation The installation procedure and environmental specifications for the NX20 play a significant role in the safe operation of the system. Since the durability, safety and overall performance of the NX20 depend on the environment and proper installation, please close...
Page 71 Isolation System can be used to mitigate any remaining sources of noise. The Vibration Criteria for NX20 should be below the line labeled “VC-E” on the criteria plot in Figure 3-1. The vibration level will be improved with the Acoustic Enclosure and Active Isolation System.
Page 72 Figure 3-1. Vibration Criteria Graph  Electrical Requirements -The NX20 requires an AC power supply. -Power Supply: 100/120 V or 220/240V, Single Phase, 50/60Hz -Consumption: 1kW (max) -Ground Resistance: Recommended below 100ohms (Here is the electrical specification for each controller used in NX20)
Page 73 10KA Rating(SCCR) Since the NX20 SPM a is highly sensitive equipment, it is ideal to use it with an Uninterruptible Power Supply (UPS) installed to provide a stable power supply. It is also recommended to connect all the ground pins in the power lines to a ground source to reduce noise.
Page 74: Component List
NX20 User’s Manual Figure 3-2. Top View of Dimension NX20 with Clearance 3-2. Component List  NX20 System  NX Standard Head  NX20 XY Scanner  MOD Unit(Option)  Cables  Motor Cable, 50 pin (3 m)  Analog Cable, 68pin(3 m) ...
Page 75 Chapter 3. Installation  MOD Controller (Option)  MOD Controller  Power Cable  Manual  Acoustic Enclosure (Optionally, the Temperature Control Acoustic Enclosure will be provided. In this case, its manual will be provided, separately.)  Computer  Computer Main Unit ...
Page 76 NX20 User’s Manual Cantilevers for NC Mode 10ea  Tweezers  Sample plate 10ea  Exchanger  Clip type chip carrier  Controller Spare Fuse 4A, 100V/120V or 2A, 220/240V  SLD Paper  Glue for Mounting Accessory Ⅱ ...
Page 77: Uncrate
Chapter 3. Installation 3-3. Uncrate  Use a Phillips screwdriver to peel off the back of a blue vinyl top box and remove the screws that hold the panels in each side. CAUTION: Two people are required to remove all panels of the crate. Improper lifting can cause muscle strain or back injury.
Page 78: System Setup
NX20 User’s Manual 3-4. System Setup 3-4-1. Installation of Acoustic Enclosure Place the AE at the installation location. Note that there is a metal foot(1), nut(2), and wheel(3) assembly on each of the lower corners of the AE. Use a wrench to turn the nut(2) clockwise to lower each foot(2) until the wheels(3) are slightly raised off of the floor (approximately 5mm).
Page 79 Chapter 3. Installation 3-4-2. Load Control Electronics & Computer/Monitor ① Load NX20 control electronics and monitors/keyboard/mouse/PC on the desk. Monitors Control Electronics MOD Controller Figure 3-4. Electronics, Monitor, Computer Desk Setup 3-4-3. Cabling ① Required Cables: (a) Camera Cable (b) TCP/IP Cable...
Page 80 AE and the LAN port of the computer. ② Connect the Motor cable between the 50 pin connector coming out of the AE and the motor connector ((d) in figure 3-6) on the rear panel of the NX20 control electronics.
Page 81 Please refer to the manual supplied by the computer manufacturer. Grounding The NX20 system needs to be grounded in order to prevent any damage from the ESD. A ground cable should be connected from the AE-Ground point (Figure 3-7) to the Common Point Ground at the installation site.
Page 82 NX20 User’s Manual 3-4-5. Unlock XY Stage ① Remove the jig to lock the XY Stage from the XY Stage body by unscrewing three screws (circled in red in Figure 3-9). XY Stage XY Stage Jig Figure 3-9. XY Stage Jig 3-3-6.
Page 83 3-3-8. Power On ① Connect to Power Supply Connect the NX20 control electronics, the computer and the monitor to a grounded power supply. Make sure that all the switches are turned off to prevent any damage to the equipment.
Page 84 NX20 User’s Manual Figure 3-12. Diagram of Cables Connections for the NX20 Check Calibration of Scanners ① Load the standard sample on the magnetic sample holder of the XY scanner. ② Take image and check if the dimensions of the standard sample measured from the obtained image correspond to the specification of the standard sample.
Page 85: System Relocation
[2nd Order line by line in both X and Y direction] ⑦ Check the RMS roughness of the processed image. The RMS roughness should be less than 0.5Å for a properly installed NX20 system equipped with a MOD and AE.
Page 86 ⑦ Relocate the acoustic enclosure to new installation site by pushing it using the wheel on the bottom. WARNING! Do not move the acoustic enclosure with the NX20 main system inside it. The system may be damaged if the enclosure encounters uneven flooring. Move the NX20 main system separately from the acoustic enclosure.
Page 87 Chapter 3. Installation <Blank Page>...
Page 88: Chapter 4. Cantilever Selection
NX20 User’s Manual Chapter 4. Cantilever Selection 4-1. Cantilever Characteristics Generally speaking, the term ‘cantilever’ includes the silicon chip, a cantilever hanging from the chip, and a tip hanging from the end of the cantilever. Figure 4-1 shows the overall view and the names of the parts of the cantilever used in the SPM (Scanning Probe Microscope).
Page 89 Q-factor, a cantilever with a high force constant, is used more than the V shape. The cantilever provided with the NX20 by default is a silicon, rectangular shaped cantilever for use in both contact and non- contact mode.
Page 90: Cantilever Selection
NX20 User’s Manual reflectivity. However, for EFM (Electrostatic Force Microscopy) or MFM (Magnetic Force Microscopy), when the whole cantilever and tip is coated to measure the electric or magnetic properties, there is no extra coating on the cantilever. 4-2. Cantilever Selection There are several types of cantilevers varying in material, shape, softness (represented by the spring constant), intrinsic frequency, and Q-factor.
Page 91: Cantilever Mounting
4-3. Cantilever Mounting Cantilever chips must be mounted on chip carriers before use. Park Systems provides various types of chip carriers for different measurements. Both pre-mounted and unmounted cantilever chips are provided. If your cantilever chip is not mounted onto a chip carrier, you must do so with adhesive using glue type chip carriers or with clip type chip carriers.
Page 92 NX20 User’s Manual Standard Chip Carrier Ceramic Chip Carrier for SThM Ceramic Chip Carrier for SCM Teflon Coated Chip Carrier for CP-AFM Teflon Coated Chip Carrier for EC-Cell  Required Components The following items are required to load un-mounted cantilever chips in general.
Page 93 Chapter 4. Cantilever Selection NOTE! You should allow several hours for the adhesive to completely dry; otherwise, Non-Contact mode images may be affected. NOTE! Make sure that the cantilever chip is attached the right way up. If necessary, reattach the cantilever chip. Improper Alignment Correct Figure 4-7.
Page 94 NX20 User’s Manual Clip Mount Clip Lift Hole Hole Figure 4-8. Structure of Clip Type Chip Carrier The chip type chip carrier is coated with chromium, is designed for various environments such as air, liquid, wiring, and does not need electrically conductive glue to be connected between the cantilever and chip carrier electrically.
Page 95 Chapter 4. Cantilever Selection Adjustment Screw Chip Loading Place Upper Base Chip Carrier Mount Figure 4-9. Cantilever Exchanger There is an adjustment screw on the upper base of the cantilever exchanger to move the upper base up or down. Turning the screw clockwise moves the upper base down and keeps the clip opened.
Page 96 NX20 User’s Manual NOTE! The cantilever may not be mounted correctly if the cantilever chip isn’t sufficiently aligned on the Cantilever Exchanger. ③ Close the upper base of cantilever exchanger and turn the adjustment screw clockwise to open the chip carrier’s clip.
Page 97 Chapter 4. Cantilever Selection NOTE! Make sure that the cantilever chip is placed the right way up. If necessary, reinsert the cantilever chip. Bad!! Good!! Figure 4-13. Correct Mounting of Cantilever Chip ⑥ Turn the adjustment screw of the cantilever exchanger counter-clockwise to lift up the upper base.
Page 98: Cantilever Db
NX20 User’s Manual you overlay the two ruby nodules located on the end of the probe arm with these holes, the cantilever chip will be attached into place by a magnet, and the position of the cantilever will be firmly fixed in one position.
Page 99 Chapter 4. Cantilever Selection Figure 4-15. Create Cantilever DB NOTE! Before you create the cantilever DB, it is recommended to select the cantilever type with a similar force constant since the cantilever DB is created by copying the previous selected one. 4-4-2.
Page 100 NX20 User’s Manual Figure 4-16. Input Cantilever Specification 4-4-3. Calibrate VERTICAL Sensitivity VERTICAL sensitivity is the calibration factor between the deflection of the cantilever and the movement of the reflected beam on the PSPD. In contact mode, this PSPD position is converted to a distance deflected by the cantilever using the VERTICAL sensitivity calibration.
Page 101 Chapter 4. Cantilever Selection a) Approach your cantilever to the sample. b) Go to FD spectroscopy by selecting [Mode>Scan Mode>FD Spectroscopy] or the icon. c) Add a point on the scan image. d) Set the parameters on FD spectroscopy control window. e) Perform FD spectroscopy by clicking the [Acquire] button.
Page 102: Cantilever Storage
NX20 User’s Manual Figure 4-17. VERTICAL Sensitivity Calibration 4-5. Cantilever Storage When cantilevers are kept in ambient conditions with variable temperature and humidity for long periods, their reflected beam intensity can decrease due to oxidation of the cantilever coating material. It is also possible that the end of the tip can become damaged.
Page 103 Chapter 4. Cantilever Selection Infrared Ray(IR) Detector SLD Beam Position Cantilever Position on standard chip carrier Figure 4-18. (Left) Beam position when using SLD detector Chip Carrier, (Right) Beam position when using Standard Chip Carrier. Attachment There are two holes in the chip carrier, a round hole and an elongated slot. Overlay the two ruby nodules located on the probehand with these holes.
Page 104 NX20 User’s Manual Figure 4-20. SLD beam on the Detector Chip Carrier 3. Re-attach the chip carrier and cantilever after removing the detector chip carrier. 4. Move the SLD beam upward or downward while turning the Y beam alignment knob (large knob on the left side of head), since the SLD beam has been located on the cantilever position in X axis but with an offset in Y axis, depending on the cantilever type (Figure 4-18).
Page 105 Chapter 4. Cantilever Selection <Black Page>...
Page 106: Chapter 5. Operation Procedure 5-1. Basic Procedure
SMARTSCAN. The NX20 is operated by the SmartScan™ software. When you click the SmartScan™ icon in the desktop or in C:\Park Systems\SmartScan\bin of your computer, you can...
Page 107 NX20 is fabricated so that even large size sample can be investigated with enhanced images. To satisfy this, NX20’s X-Y scanner is different from NX10’s, which is usually used for smaller samples. Thus, the sample loading procedure for the NX20 is divided into two cases, when using the vacuum lines and when using the magnetic sample holder.
Page 108 NX20 User’s Manual *XY Stage Control Window For the NX20, you can see both XY and Z/F stage pads on the screen. If there is no “X-Y stage control window” on your computer screen, you can open this window by clicking the X-Y stage icon .
Page 109 If the Focus stage is too close to the head, raise the Focus stage. Turn off the AFM beam switch and unlock the dovetail locks on the sides of the head. Disconnect the head from the connector of the NX20 main system. Then, slide the head out to the right.
Page 110 Section 6-5 much easier. Attach Head to the NX20 Main System ① Attach the head to the NX20 main system in inverse order of Figure 5-2. 5-1-4. Select Head Mode/Cantilever ① Attach the head to the NX20 main system in inverse order of Figure 5-2...
Page 111 Chapter 5. Operation Procedure Figure 5-4. Part Selection Dialog 5-1-5. Find Cantilever ① Move the focus stage down nearby the head using the focus motor control in the software. As you click upper or lower position from the center bar on the stage pad, the stage will move up or down.
Page 112 NX20 User’s Manual Find the cantilever chip shadow by the illuminator, using the X and Y optical alignment knobs. Left: Sample Surface, Right: Cantilever Shadow on Sample Surface c) Lift the Focus stage up, and you can see the cantilever chip substrate. Then, move the optical alignment knobs to position the cantilever on the center of the vision program.
Page 113 Chapter 5. Operation Procedure edge of the cantilever or cantilever chip substrate. ① Focus on the Cantilever Chip Substrate: It is easier to find the beam by placing it on the edge of the cantilever chip substrate with the Y beam alignment knob since its area is large.
Page 114 NX20 User’s Manual smaller than an atomic radius to be measured by the AFM. Align the reflected laser beam from the cantilever to the PSPD by controlling the PSPD alignment knobs. , ① Turn Y PSPD alignment knob to maximize INTENSITY.
Page 115 Chapter 5. Operation Procedure NOTE! Turning the X or Y PSPD alignment knob can make INTENSITY (beam intensity) suddenly smaller. In this case, stop turning the X or Y PSPD alignment knob and turn it the opposite direction. * When INTENSITY value on PSPD is too small: Even if the VERTICAL value is within the acceptable range, if the INTENSITY value is too small, it may be difficult for the beam to approach the center of the PSPD and for the tip to approach the sample properly.
Page 116 NX20 User’s Manual 5-1-8. Approach Tip to Sample ① Set Point Setting: Contact Mode Set Point in Contact Mode: Reference force for Z feedback As the cantilever and sample’s surface get closer, the repulsive force between tip and sample grows bigger, the cantilever bends more and PSPD’s VERTICAL value changes.
Page 117 Chapter 5. Operation Procedure Check Desired Position on Sample: Bring tip a few millimeters from the sample. Move head towards the sample using the Z-stage motor control in the software. Visually inspect the tip-sample separation. Stop when the tip is a few millimeters from sample.
Page 118 NX20 User’s Manual complete. The upper half of Z scanner bar in the PSPD window will be green if “Approach” is successful. Before approaching, it is recommended to set the scan size to 0 and Z servo gain to 1 in the scan control window.
Page 119 Chapter 5. Operation Procedure Figure 5-8. Input Config  Z Drive: Calculated Value from the driving voltage to the Z scanner in the feedback system. Considered as the height information of the sample surface since the Z scanner is in feedback to respond to the sample height. ...
Page 120 NX20 User’s Manual  VERTICAL: (VERTICAL) value in PSPD containing cantilever deflection information Parameter Setting Input a value in the Scan Size field found in the Scan Area tab. This will be the size of your image. The XY Scanner will begin moving back and forth using this value.
Page 121 Chapter 5. Operation Procedure  Repeat: If selected, the system wil activate the text display to the right. Enter a number between 2 and 1000 to repeat the scan the specified number of times.  Retract Z after Done: Checking the Retract Z after Done check box will lift the cantilever away from the sample 100μm using the Z stage control once the image has been acquired.
Page 122: Sample Loading
NX10’s, which is usually used for smaller samples. Thus, the sample loading procedure for NX20 is divided into two cases, for large and for small samples, as follows. ① Raise the Head and the Focus stage high enough so that you have no difficulties in loading the sample on the X-Y scanner.
Page 123 Chapter 5. Operation Procedure the vacuum pump. When the 150mm sample chuck is equipped on the XY stage, 4-, 6-inch flat type wafers and 6-inch notch type wafer can be positioned and when the 200mm sample chuck is equipped, 6-inch flat/notch type and 8-inch notch type wafer can be positioned using the bearings and the guide line pin.
Page 124 NX20 User’s Manual using glue. Hard-setting adhesives such as cyanoacrylate glues are recommended, otherwise, the sample may move significantly during the imaging procedure. Then, place the sample disk on the magnetic sample holder after fixing the magnetic sample holder to the X-Y scanner. (see figure 5-2) The magnet will keep the sample disk in place.
Page 125 Chapter 5. Operation Procedure Tape You can fix the small samples using adhesive tape. Using tape to fix the sample is convenient but may result in sample drift during imaging. Using a single strip of double- sided tape will reduce drift, but the adhesive layer on any tape will move significantly on a nano scale over time..
Page 126: Operating Concept
5-3. Operating Concept 5-3-1. Basic Operating Concept The NX20 scanner is separated into an X-Y scanner and a Z scanner instead of the single piezoelectric tube scanner used in most other SPMs. The X-Y scanner moves the sample in the horizontal direction for the range you want to image. The Z scanner moves the cantilever in the vertical direction to trace the morphology of the sample.
Page 127 Hence, you can manage the scanner’s motion more precisely by dividing the applied voltage into smaller units in the DAC (digital-to-analog converter). The NX20 system uses a 20-bit DAC for controlling scan movement in X and in Y. A 16-...
Page 128 NX20 User’s Manual bit DAC is used for determining scale so that the scanner’s motion and position can be elaborately controlled. When an applied voltage that can make the scanner move 50㎛ is controlled using a simple 20-bit DAC, the lateral resolution is 50 ㎛ / 2 = 1Å.
Page 129 Y axis, thus creating an AFM image. The brightness of the AFM image indicates sample height information:. Park SYSTEMS AFMs have strain gauge sensors on the Z scanner in order to accurately measure sample heights regardless of the non-linear characteristics inherent to all piezoelectric devices.
Page 130 NX20 User’s Manual file format. Thus, to see these acquired images in an Image viewer and the traditional Windows Explorer display, it is necessary to change the file format saved by individual SPM instruments into the image file format by using image processing software.
Page 131 Chapter 5. Operation Procedure Figure 5-18. Data Export...
Page 132: Maintenance
NX20 User’s Manual 5-4. Maintenance Maintenance procedures are required to maintain accuracy and safety of the SPM. There are two kinds of maintenance procedure. The daily check and the periodic test respectively. It is recommended to be perform periodic test after operating the SPM for a certain period of time.
Page 133 Chapter 5. Operation Procedure 5-4-1. XY Stage Maintenance procedures are required to maintain accuracy and safety of the XY stage. There are two kind of maintenance procedure of the XY stage. One is a daily check and the other is a periodic test which must be done after operating the XY stage for a certain period of time.
Page 134 NX20 User’s Manual Table 5-3. Checklist for frequency checkup of XY Stage Frequency Item Action - Interference with other parts of SPM during the Positioning operation - Position change when the stage is stationary 1 Day Noise and - Any abnormal noise generated or vibration at...
Page 135 Chapter 5. Operation Procedure 5-4-2. Acoustic Enclosures / Doors Parts of the acoustic enclosure are just structures and do not require any routine checkups except for the routine check of bolt fixations. Table 5-4. Checklist for freqency checkup of acoustic enclosure & door Frequency Item Action...
Page 136 NX20 User’s Manual ① X-Y scanner calibration in ‘Open Loop’ scan The XY scanner uses a wide moving range so the calibration data differs depending on the moving (scan) range without XY Servo by pzts’ non-linearity characteristics. Therefore, for XY scanner calibration in an ‘Open Loop’ scan, operators should sort by the scan range and calibrate the XY scanner respectively.
Page 137 Chapter 5. Operation Procedure 1.2 Select the XY Scanner Range (20% / 50% / 100%). -Turn off the laser by unchecking the beam check box in the vision view. -Go to Part Config window by clicking ‘Set up’ button. Make sure to turn off the Line Scan button before selecting Part Config.
Page 138 NX20 User’s Manual * XY Scanner Range: 50% -> Scan Size: 10 ㎛ * XY Scanner Range: 100% -> Scan Size: Full Range 1.5 Measure the XY scanner movement. -Go to the Channel Config window and select X detector and Y detector.
Page 139 Chapter 5. Operation Procedure 1.6 Go to Maintenance mode and select Calibration tab, then click XY button.
Page 140 NX20 User’s Manual ② X-Y scanner calibration in ‘Closed Loop’ scan The previous Park Systems’ version of XY Scanner used Single Servo Method (using Detector1 with two PSPDs as shown on the upper left figure) to correct the XY scanner non-linearized movement. For a better calibration error, the NX20 was equipped with an XY Scanner with four PSPDs which can also use the Dual Servo Method (using Detector 1 and 2).
Page 141 Chapter 5. Operation Procedure ② Select the head mode and the cantilever. -Turn off the laser by unchecking the beam check box in the vision view. -Set Head mode to C-AFM and select the appropriate type of cantilever in the Part Config.
Page 142 NX20 User’s Manual -Using the XEI program, measure the spacing between the largest number of maxima for the x direction of the calibration grid image. Refer to the XEI manual for details. -The measured spacing in the example above is 21.094㎛ between two maxima.
Page 143 Chapter 5. Operation Procedure -Click the ‘Apply’ button to calibrate. -Input the measured x spacing, 27.836㎛ to the ‘Measured value’ box of the ‘X Scanner’ and input the actual spacing, 27㎛ into the ‘Desired value’ box. -Click the ‘Calibrate’ button. ⑤...
Page 144 NX20 User’s Manual ③ Repeat the same procedures (③~⑤ of Step 2 above) for the X detector 2 calibration. ④ Calibrate the Y Detector2. -Place the calibration sample to the Y detector 2 position. -Set the fast scan direction to Y.
Page 145 Chapter 5. Operation Procedure ① Set XY Servo to On and XY Servo Type to Dual / Averaged in the XY ServoScan Config window ② Sweep the XY scanner. -Go to Sweep tab. -Set the parameters to the following: Driving Source: X Scan Pixels: 512 From ~To~: -80% ~ 80% Rate: 1 Hz...
Page 146 NX20 User’s Manual -Change the Driving source to Y Scan and click the Sweep button. -Check if the edge of the Y detector is well aligned like in the figure below (Forward and backward signals should match over an 80㎛ range) -Check for abnormal movement in the other direction (Y/X) by coupling during the movement in X/Y direction.
Page 147 Chapter 5. Operation Procedure Note: For more accurate and detailed measurement, calibration in Open loop must be performed.  Z Scanner Calibration 1. Setup XY scanner and NX head. 2. Place the calibration sample on the XY scanner. If a special calibration sample for much smaller/larger heights is not required, the standard grating sample included with the system can be used.
Page 148 NX20 User’s Manual 8. Set the scan size and scan rate appropriate for the calibration sample. Adjust the set point, gain, and slope parameters until the signal on the Trace window will stabilized and represents the sample topography. 10. Once an image is obtained, send the data to the XEI program by right clicking the mouse on the image and selecting Send to XEI in the Browse tab.
Page 149 Chapter 5. Operation Procedure 12. The height of the gratings in the above example is 171 nm when measured from the Height image. And, specifications of this standard sample shows that the height should be 170 nm. Hence, enter the calibration mode and select Z Scanner button.
Page 150 NX20 User’s Manual Open Perform X Scanner Sweep by clicking Sweep X button and check the value of offset. Input the value of Offset in the X1 Detector Offset field.
Page 151: Reliability Test
Adjust Apply the same procedure with X2 detector.  Y direction For the Y direction, follow the same procedure used in the X direction. Reliability test To confirm the reliability of the NX20 system, the operator can carry out following monthly tests. D-1. Height Noise Level Test ①...
Page 152 ⑥ Open the obtained Height image on XEI and flatten with the following conditions. [2nd Order line by line in both X and Y direction] ⑦ Check the RMS roughness of the processed image. (RMS roughness should be less than 0.5Å when the NX20 system is installed with MOD and AE.)
Page 153: Chapter 6. Afm In Contact Mode
Chapter 6. AFM in Contact Mode Chapter 6. AFM in Contact Mode 6-1. Principle of Contact Mode AFM The AFM (Atomic Force Microscope) is an instrument that is used to study the surface structure of a sample by measuring the force between atoms. At the lower end of the Z scanner, there is a cantilever of very tiny dimensions: 100 ㎛...
Page 154 NX20 User’s Manual Figure 6-1. Relation between the force and the distance between atoms In contact mode AFM the probe makes “soft contact” with the sample surface, and the study of the sample’s topography is then conducted by utilizing the repulsive force that is exerted vertically between the sample and the probe tip.
Page 155: Contact Mode Setup
Chapter 6. AFM in Contact Mode 6-2. Contact mode setup To use contact mode AFM, select the appropriate Head mode as follows: ① Turn off the beam by unclicking the beam control check box at the bottom left portion of the Vision View ②...
Page 156 NX20 User’s Manual Figure 6-2. SEM image of the shorter cantilevers (A, B, C) from a chip of the NSC36 series Figure 6-3 shows the detailed standardized gauge of the NSC36 series chip. Altogether, this chip contains three cantilevers, all with different spring constants.. If the unmounted cantilevers are purchased separately, you may choose from the set of cantilevers A,B,C.
Page 157: Measurement Procedure
Chapter 6. AFM in Contact Mode Table 6-1. Specifications of NSC36 Series Cantilevers 6-4. Measurement Procedure The measurement procedure hereafter is the same as in Chapter 6. Please review Chapter 6.
Page 158 NX20 User’s Manual <Blank Page>...
Page 159: Chapter 7. Lateral Force Microscopy (Lfm)
Chapter 7. Lateral Force Microscopy Chapter 7. Lateral Force Microscopy (LFM) 7-1. Principle of Lateral Force Microscopy (LFM) The principle of Lateral Force Microscopy (LFM) is very similar to that of Contact mode AFM. Whereas in contact mode we measure the deflection of the cantilever in the vertical direction to gather sample surface information, we measure the deflection of the cantilever in the horizontal direction in LFM.
Page 160 NX20 User’s Manual the lower cells (b+d) of the PSPD. Topographic information = VERTICAL = (a+c)-(b+d) The LFM(“LATERAL”) signal, which is related to the change in the surface friction on a sample surface, measures the deflection of the cantilever in the horizontal direction and can be represented as the difference in the signals recorded in the right cells (a+b) and the left cells (c+d).
Page 161: Conversion To Lfm
Chapter 7. Lateral Force Microscopy high frictional coefficient. Profile b indicates the cantilever’s deflection as it encounters topographic features as well as different frictional coefficients as it scans from left to right. Profile c is an AFM image of the surface topography and structure; it is represented by the change in the vertical deflection of the cantilever which does not include the horizontal deflection.
Page 162: Cantilever Selection
NX20 User’s Manual ① Turn off the beam by unclicking the beam control check box at the bottom left portion of the Vision View. ② Once the beam is off, click the Head Mode tab at the top of parameters view and select Contact.
Page 163 Chapter 7. Lateral Force Microscopy <Blank Page>...
Page 164: Chapter 8. Afm In Non-Contact Mode
NX20 User’s Manual Chapter 8. AFM in Non-Contact Mode 8-1. Principle of Non-contact Mode AFM There are two major forces, the static electric repulsive force and attractive force, existing between atoms a short distance apart: The static electric repulsive forces (F...
Page 165 Chapter 8. AFM in Non-Contact Mode Figure 8-1. Concept diagram of contact mode and non-contact mode Figure 8-1 compares the movement of the probe tip relative to the sample surface for images being acquired between in contact AFM and non-contact AFM. Contact AFM uses the “physical contact”...
Page 166 NX20 User’s Manual its resonant frequency near the sample surface experiences a shift in the spring constant from its intrinsic spring constant ( ). This is called the effective spring constant (k ), and the following equation holds:  ...
Page 167 Chapter 8. AFM in Non-Contact Mode frequency (f ) is as in Equation (2).  As in Equation (1), since k becomes smaller than k due to the attractive force, f too becomes smaller than f as shown in Figure 8-3 (a). If you vibrate the cantilever at the frequency f (a little larger than f ), where a steep slope is observed in the graph...
Page 168: Non-Contact Mode Setup
NX20 User’s Manual Figure 8-3. (a) Resonant frequency shift (b) Amplitude vs Z-feedback 8-2. Non-contact mode setup The non-contact mode setup can be done easily by selecting NC-AFM as the Head mode, similar to the setup for contact mode explained in Section 2 of Chapter 8.
Page 169 Chapter 8. AFM in Non-Contact Mode Figure 8-4. Resonant Frequency setup in Non-Contact Mode When the “NCM Frequency Setup” window opens, you can manually select the resonant frequency as follows. ① If the ‘Refresh’ button or ‘Zoom Out’ button is clicked, one unit on the X-axis represents 5 kHz as shown above.
Page 170: Cantilever Selection
NX20 User’s Manual of the peak height, and press the “OK” button once to enter the selection. The value of the drive amplitude(%) and set point can also be changed in the “Scan Control” window. 8-4. Cantilever selection The non-contact mode cantilever has a relatively large frequency since the non-...
Page 171: Measurement Procedure
Chapter 8. AFM in Non-Contact Mode Figure 8-6. Silicon chip of the NCHR series has 1 rectangular cantilever Table 8-1. NCHR series Cantilever Specifications Cantilever Cantilever Cantilever Cantilever Resonant Force Constant, Type Length, Width, Thickness, ㎛ Frequency, kHz l ± 5, ㎛ w ±...
Page 172: Chapter 9. Dynamic Force Microscopy (Dfm)
NX20 User’s Manual Chapter 9. Dynamic Force Microscopy (DFM) 9-1. Principle of Dynamic Force Microscopy Dynamic Force Microscopy (DFM) is very similar to Non-contact mode AFM in many ways such as the applied force and the measurement principle. Before you read this chapter, please read carefully “Chapter 8 Non-contact Mode measurement”.
Page 173 Chapter 9. Dynamic Force Microscopy vibrating frequency (f1) a little bit lower than the resonant frequency while oscillating in free-space. Then, as the tip is lowered, the real spring constant reduces due to the attractive van der Waals force which increase as the tip approaches the sample surface, as shown in Figure 9-2 (a).
Page 174 NX20 User’s Manual Figure 9-2. (a) Resonant frequency shift (b) Amplitude vs. Z-feedback For certain samples, DFM yields better measurements than contact mode or non-contact mode AFM. Dynamic force microscopy (DFM) has an advantage over contact mode in the sense that it will damage the sample less since there is no frictional force as the cantilever “skips”...
Page 175: Conversion To Dfm
Chapter 9. Dynamic Force Microscopy 9-2. Conversion to DFM In dynamic force microscopy, the Head mode will be set to NCM just as in non-contact mode. However, the “Intermittent” checkbox in NCM Frequency Sweep Window must be selected. Figure 9-3. Conversion to DFM 9-3.
Page 176: Cantilever Selection
NX20 User’s Manual Figure 9-4. Resonant frequency setup in DFM 9-4. Cantilever Selection Since DFM uses the same method as non-contact AFM, which is to vibrate the cantilever when measuring the sample surface, the same type of cantilevers are used in DFM as in non-contact mode unless the user prefers a different type of cantilever for a specific purpose.
Page 177 Chapter 9. Dynamic Force Microscopy...
Page 178: Chapter 10. Approach Spectroscopy
NX20 User’s Manual Chapter 10. Approach Spectroscopy Activating spectroscopy control mode changes the workspace as shown below. To get to the Spectroscopy Control View, click the Manual tab, then choose the Spectroscopy button in the Spectroscopy Parameters View. The workspace will change to the Spectroscopy Control workspace, as shown in Figure 10-1.
Page 179 Chapter 10. Approach Spectroscopy (CP-AFM)  Ind.: Nano-indentation  AD: Amplitude spectroscopy (generally referred to as amplitude- distance spectroscopy)  TA: Temperature analysis spectroscopy (used with scanning thermal microscopy) The Manual tab of the Spectroscopy Control workspace includes. Vision View The Vision View displays the optical view from the digital camera.
Page 180 NX20 User’s Manual The Vision View can also be used to control a) light strength, b) turning the beam on/off, c) the XY stage, and d) the Z/focus stage. Clicking Expand ) will expand the Vision View to allow the user to easily see the optical image.
Page 181 Chapter 10. Approach Spectroscopy Panel Function Quad Cell-PSPD Shows the position of the reflected laser beam on the PSPD so that you can monitor the deflection of the cantilever. Vertical Monitors the vertical PSPD signal, such as cantilever deflection, amplitude of cantilever vibration, or tunneling current, depending on your experimental setup.
Page 182 NX20 User’s Manual Figure 10-4. Quad-cell PSPD In order to perform an approach and take an image, in general you should set the value of the A-B signal smaller than ±0.3V (the red point should be positioned at the center (crosshair) of the quad-cell PSPD display) and the value of the A+B signal (in other words, the laser total intensity) greater than 2V.
Page 183 Chapter 10. Approach Spectroscopy  Z Scanner Bar The Z scanner bar monitors the extension or retraction of the Z scanner in response to feedback voltage. The orange portion of the Z scanner bar represents the extension of the piezoelectric Z scanner within its total allowable range of motion.
Page 184 NX20 User’s Manual  Channels Tab In the Channels tab, you can select several input signals (up to six) and monitor them through digital panels in real time. Figure 10-6. Channels tab  Edit Edit opens the Channel List dialog to select signals to be monitored through the digital panel.
Page 185: Spectroscopy Parameters View
Chapter 10. Approach Spectroscopy 10-1. Spectroscopy Parameters View The Spectroscopy Parameters View sets the parameters used to take the point measurement. The parameter interface changes depend on the type of spectroscopy measurement being taken. The various spectroscopy parameter setup interfaces are shown in Figure 10-8. Figure 10-8.
Page 186 NX20 User’s Manual The general procedure for spectroscopy measurement is as follows: 1. Obtain an SPM image of the sample to identify regions of interest for spectroscopy curves using Scan Control or Auto mode (Chapter 6). 2. Change to Spectroscopy Control.
Page 187 Chapter 10. Approach Spectroscopy users to acquire NCM amplitude and NCM phase information as a function of distance from the surface. This technique can be used to study tip-sample interaction.  TA: Temperature analysis spectroscopy Temperature analysis spectroscopy is used only with SThM for SThM probe temperature calibration.
Page 188 NX20 User’s Manual sample relative to the tip. When in Z Servo On mode, a high XY speed may be too fast for the Z servo to prevent the tip from being damaged.  Z Control while XY in Motion...
Page 189 Chapter 10. Approach Spectroscopy time, but may be insufficient to prevent collision.  Settling Time After the tip is relocated, the Z servo must be turned on. Settling Time allows the user to define how much time is given for the Z servo to activate.
Page 190 NX20 User’s Manual results, the green line should follow the linear portion of the FD curve. 4. The Sensitvity to be applied display box will update the calulated sensitivity. 5. Click Apply to update the sensitivity of the cantilever file.
Page 191 Chapter 10. Approach Spectroscopy Figure 10-12. Cantilever Spring Constant Calibration window  Force Slope Correction This option opens the Force Slope Correction window. The Force Slope Correction window is shown in Figure 10-13. The Force Slope Correction feature corrects the baseline of the FD curve. When the FD baseline is sloped, the curve can be corrected using the slope correction.
Page 192 NX20 User’s Manual Figure 10-13. Force Slope Calibration window  NCM Amplitude This option opens the NCM Amplitude Calibration window. To activate the NCM Amplitude menu selection, SmartScan must be set to a non-contact-based scanning mode and AD Spectroscopy must be selected. The NCM Amplitude Calibration window is shown in Figure 10-14.
Page 193: Spectroscopy Positions View
Chapter 10. Approach Spectroscopy Z Servo Clicking this button opens the Z Servo Configuration dialog. XY Servo Clicking this button opens XY Servo Configuration dialog. 10-2. Spectroscopy Positions View You can select the points from the Spectroscopy Positions View to indicate where you want to obtain spectroscopy data within the scan area.
Page 194 NX20 User’s Manual  Moving a point Measurement points can be moved by clicking and dragging the numbered point on the reference or by changing the coordinate values in the Point List. Figure 10-16. Moving a spectroscopy point. Left: original position and movement direction;...
Page 195 Chapter 10. Approach Spectroscopy 10-2-2. Point Grid After selecting Point Grid Spectroscopy Positions View, a white grid with pink dots will appear in Reference area. The white box indicates the grid size. Depending on the selected grid pixels, the box is divided. The measurement points will be automatically selected on all the center points of each divided small box.
Page 196: Data View
NX20 User’s Manual 10-2-5. Start Spectroscopy measurements will be acquired in numerical order using the parameters in the parameters control panel. This procedure produces a) a single spectroscopy curve (Single shot), b) a collection of curves (Point List), or c) a 2-D grid of curves (Point Grid).
Page 197: Spectroscopy Data List View
Chapter 10. Approach Spectroscopy 10-3-2. Cursor Figure 10-21. Cursor pop-up box Figure 10-22. Single cursor example 10-3-3. Copy Menu Figure 10-23. Copy menu pop-up box 10-3-4. Compare Tab Choose the Compare tab to compare data from different point curves taken within the same Point List or Point Grid run.
Page 198 NX20 User’s Manual screen. 10-4-1. Rescale This control rescales all plots simultaneously so that curve data fits on the oscilloscope screen. Double-clicking on each plot automatically rescales the display. The scale can also be controlled manually using the mouse wheel.
Page 199: Fd Spectroscopy
Chapter 10. Approach Spectroscopy 10-5. FD Spectroscopy Force spectroscopy measures the force (deflection of the the cantilever) as the tip is brought toward and away from the surface. The FD parameters in the Spectoscopy Parameter View can be found in Table 10-25. Figure 10-25.
Page 200 NX20 User’s Manual Table 10-1. Controls in FD spectroscopy mode Controls Function Z/Highest Z scanner retracts (away from the sample) to the max value distance from the offset position. Input range is [(-1/2~1/2) x Z scanner’s maximum movement range] when Z Offset turns on and [(-1~+1) x Z scanner maximum movement range] when Z Offset turns off.
Page 201 Chapter 10. Approach Spectroscopy When setting the FD input range, the Min value must be smaller than Max value. If not, the system will ask you to swap the values.  Auto Offset 1) Auto Offset On : Z scanner moves from the highest to the lowest position using the current Z scanner position (by the Z servo) as the reference position.
Page 202: Spectroscopy
NX20 User’s Manual 10-6. IV Spectroscopy Table 10-2, shown below, lists each control in the Spectroscopy control window with a brief description of its function. Figure 10-26. IV Spectroscopy parameters...
Page 203 Chapter 10. Approach Spectroscopy Table 10-2. Controls in IV spectroscopy mode Controls Function Bias/Highest Highest sample bias value in acquiring an IV curve Bias/Lowest Lowest sample bias value in acquiring an IV curve Reverse When Reverse is selected, the sample bias is applied in this order: Start->Lowest->Highest- >End.
Page 204: Indenter
NX20 User’s Manual 10-7. Indenter Nano-Indentation has two sub-modes: Z scanner mode and force mode. Each sub-mode uses different parameters to control the indentation cycle. In force mode, the force (load) between the tip and sample is varied as a linear function of time while the corresponding position of the Z scanner is measured.
Page 205 Chapter 10. Approach Spectroscopy Table 10-3. Controls in nano-indentation mode Controls Function Z or Force When the Z radio button is checked, nano-indentation is performed in Z scanner mode. When the Force radio button is checked, nano-indentation is performed in set point mode. Z Scanner Mode Z Depth The Z scanner extends (toward the sample) until it reaches...
Page 206 NX20 User’s Manual 10-7-1. Moving the Y Scanner During Indentation Normally, the cantilever will not be able to approach the sample top-down with zero degree cantilever tilt because an AFM cantilever has certain degree of tilt. Furthermore, it is possible for the tip to slip laterally as the indenter tip pushes down the sample.
Page 207 Chapter 10. Approach Spectroscopy In Figure 10-27, the values displayed in the Load Ratio and Unload Ratio specify the ratio between the movement of the Z scanner and the Y scanner. Inserting positive values will cause the Y scanner and Z scanner to adjust in the same direction.
Page 208: Ad Spectroscopy
NX20 User’s Manual 10-8. AD Spectroscopy In AD spectroscopy, the cantilever is oscillated at a constant frequency and amplitude. As the scanner is extended and the cantilever approaches the surface, the amplitude begins to decrease. This change in amplitude can be measured as a function of distance to the surface using AD spectroscopy.
Page 209 Chapter 10. Approach Spectroscopy Table 10-4. Controls in AD spectroscopy mode Controls Function Z/Highest The Z scanner retracts (away from the sample); the highest value that the Z scanner will be lifted away from the surface Z/Lowest Z The Z scanner extends (toward the sample); the lowest value that the scan will extend toward the surface Auto Offset Uses the relative Z position...
Page 210: Ta Spectroscopy
NX20 User’s Manual 10-9. TA Spectroscopy Thermal analysis (TA) spectroscopy mode is used to control current through the nanothermal probe in SmartScan. When current is transmitted to the nano thermal probe, melting can occur (heating the probe tip), and change the probe’s deflection.
Page 211 Chapter 10. Approach Spectroscopy Table 10-5. Controls in TA spectroscopy mode Controls Function Probe Current Start Starting current of the temperature ramp (Min 0.01mA – Max 2.5mA) Ending current of the temperature ramp (Min 0.01mA – Max 2.5mA) Base Base probe current before and after acquiring data Controls Function Speed of probe’s current sweep...
Page 212 NX20 User’s Manual Figure 10-33. SThM Reference Calibration Figure 10-34. Z Servo Config...
Page 213: General Procedure For Spectroscopy Measurement
Select Cantilever Window. . The Select Cantilever Window shows the list of common cantilevers offered by Park Systems. If the cantilever type is not on the list, create a new cantilever list by clicking the Create New Cantilever button (Refer to Section 4-1-1.
Page 214 NX20 User’s Manual Choose the type of cantilever to be used, then click Select button on the Select Cantilever Window to activate the selected cantilever type. Figure 10-36. Selecting Cantilever type  General Procedure for FD Spectroscopy measurement 1) Replace current cantilever in the system with low force constant cantilever and mount the sample.
Page 215 Chapter 10. Approach Spectroscopy 6) Switch to Spectroscopy Control by clicking Spectroscopy button in control panel. Figure 10-38. Spectroscopy button 7) Select FD spectroscopy by clicking the FD button in the spectroscopy view. 8) Open Spectroscopy Options window by clicking the Options button in the Setup menu.
Page 216 NX20 User’s Manual 9) Select points at which to take FD measurements on the reference image. There are three ways to do this. First is by clicking the Start button, the tip will approach the sample and perform FD measurement at the current location.
Page 217 Chapter 10. Approach Spectroscopy View in the attached SmartScan manual for more information) Figure 10-42. Sample of points in matrix 10) Set the parameters in the FD spectroscopy window to obtain optimum data measurement. (Refer to Section 9-6 in the attached SmartScan manual Figure 10-43.
Page 218 NX20 User’s Manual Figure 10-44. Start button for acquiring spectroscopy data 12) Once all of the measurement are complete, perform a curve analysis in the XEI software by right-clicking on the file in the buffer window and select “Select to XEI”.
Page 219 Chapter 10. Approach Spectroscopy Figure 10-45. Calibration button and features Perform Cantilever Sensitivity Calibration. (Refer to Section 9-1-4 Calibration in the attached SmartScan manual) Figure 10-46. Cantilever Sensitivity Calibration Perform Cantilever Spring Constant Calibration. (Refer to Section 9-1-4 Calibration in the attached SmartScan manual) Figure 10-47.
Page 220 NX20 User’s Manual 10-10-2. IV spectroscopy  Cantilever Selection The type of cantilever in IV spectroscopy must be coated by conductive material. This is to measure the current between the tip and the sample. It is also important to consider the type of sample and its application, since the cantilever tip is in contact with the sample during measurement.
Page 221 Cantilever type button is located in this window, and clicking this button will open the Select Cantilever window. The Select Cantilever Window shows the list of common cantilevers offered by Park Systems. If the cantilever type is not on the list, create a new cantilever list by clicking the Create New Cantilever button (Refer to Section 4-1-1.
Page 222 NX20 User’s Manual 4) Switch to CP-AFM Mode by clicking the Head Mode button in control panel. Figure 10-50. Head Mode button in CP-AFM 5) Select the type of amplifier and adjust the parameters in the Current Amplifier window. (Refer to Section 5-7 Current Amplifier in the attached SmartScan manual) Figure 10-51.
Page 223 Chapter 10. Approach Spectroscopy Figure 10-52. a) Variable Current Amplifier Hardware and b) Spectroscopy button 9) Switch to IV spectroscopy mode by clicking the IV button in the spectroscopy view. 10) Open Spectroscopy Options window by clicking the Options button in the Setup menu.
Page 224 NX20 User’s Manual Figure 10-53. Parameters in IV Spectroscopy Options 11) Select points at which to take IV measurements on the reference image. There are three ways to do this. a. First is by Clicking the Start button, the tip will approach the sample and perform FD measurement at the current location.
Page 225 Chapter 10. Approach Spectroscopy Figure 10-55. Sample of points added in a list Lastly, is to use Map, which designates evenly spaced points on matrix that i s overlaid on the sample surface. (Refer to Section 9- 2 Spectroscopy Positions View in the attached SmartScan manual fo r more information) Figure 10-56.
Page 226 NX20 User’s Manual 12) Set the parameters in the IV spectroscopy window to obtain optimum data measurement. (Refer to Section 9-6 in the attached SmartScan manual) Figure 10-57. Parameters in IV spectroscopy 13) Acquire IV Spectroscopy data by clicking the Start button. If the points of interest are designated using the Point list or Map, click the Start button found in the Spectroscopy Control Workspace.
Page 227 Chapter 10. Approach Spectroscopy 10-10-3. Indentation spectroscopy  Cantilever Selection The cantilever used for Indentation spectroscopy is a Diamond Tip cantilever. In this type of spectroscopy, the cantilever is pressed down to the sample with excessive force to indent and measure its mechanical property.
Page 228 Cantilever type button is located in this window, and clicking this button will open the Select Cantilever window. The Select Cantilever Window shows the list of common cantilevers offered by Park Systems. If the cantilever type is not on the list, create a new cantilever list by clicking the Create New Cantilever button (Refer to Section 4-1-1.
Page 229 Chapter 10. Approach Spectroscopy 4) Acquire image of the sample to identify regions of interest for Indentation spectroscopy. This process can be skipped and instead, a random point on the sample can be selected instead. 5) Switch to Spectroscopy Control by clicking Spectroscopy button in control panel. Figure 10-62.
Page 230 NX20 User’s Manual Figure 10-63. Parameters in IndentationSpectroscopy Options 8) Select points for Indentation measurements on the reference image. There are three ways to do this. a. First is by clicking the Start button, the tip will approach the sample and perform FD measurement at the current location.
Page 231 Chapter 10. Approach Spectroscopy b. Next, is to add points to a list. By clicking the location on the reference image, a point will be added to the list. Points can also be added directly by entering values into the Points List, which is accessible by selecting the Edit Points item in the context menu Figure 10-65.
Page 232 NX20 User’s Manual Figure 10-67. Parameters in Indentation spectroscopy 10) Acquire Indentation Spectroscopy data by clicking the Start button. If the points of interest are selected using the Point list or Map, click the Start button found in the Spectroscopy Control Workspace.
Page 233 Chapter 10. Approach Spectroscopy 10-10-4. AD spectroscopy  Cantilever Selection In selecting the appropriate cantilever for AD spectroscopy, force constant must be closely considered. It is recommended to use cantilever with high force constant (E.g. NCHR) to measure accurate amplitude during operation. AD spectroscopy allows users to acquire NCM amplitude and NCM phase information as a function of distance from surface to study tip-sample interaction.
Page 234 Select Cantilever window. The Select Cantilever Window shows the list of common cantilevers offered by Park Systems. If the cantilever type is not on the list, create a new cantilever list by clicking the Create New Cantilever button. (Refer to Section 4-1-1.
Page 235 Chapter 10. Approach Spectroscopy Approach the tip towards the sample Acquire image of the sample to identify regions of interest for AD curve acquisition. This process can be skipped and instead, a random point on the sample can be selected. Switch to Spectroscopy Control by clicking Spectroscopy button in control panel.
Page 236 NX20 User’s Manual Figure 10-73. Parameters in AD Spectroscopy Options Select points at which to take AD measurements on the reference image. There are three ways to do this. a. First is by clicking the Start button, the tip will approach the sample and perform AD measurement at the current location.
Page 237 Chapter 10. Approach Spectroscopy Figure 10-75. Sample of points in a list c. Lastly, is to use Map, which designates evenly spaced points on matrix that is overlaid on the sample surface. (Refer to Section 9-2 Spectroscopy Positions View in the attached SmartScan manual for more information) Figure 10-76.
Page 238 NX20 User’s Manual Figure 10-77. Parameters in AD spectroscopy Acquire AD Spectroscopy data by clicking the Start button. If the points of interest are designated using the Point list or Map, click the Start button found in the Spectroscopy Control Workspace.
Page 239 Chapter 10. Approach Spectroscopy 10-10-5. TA spectroscopy  Cantilever Selection The type of cantilever used in TA spectroscopy measurement is Thermal Probe with a resistive element. Thermal probe serves as a resistance thermometer (or a heater in CCM mode) and at the same time as Contact AFM probe. As a resistance thermometer in TCM, its temperature changes as the tip scans the surface according to the surface temperature.
Page 240 NX20 User’s Manual 2) Open Part Config window by clicking the Setup tab on control panel. The Cantilever type button is located in this window, and clicking this button will open the Select Cantilever window. The Select Cantilever Window shows the list of common cantilevers offered by Park Systems.
Page 241 Chapter 10. Approach Spectroscopy Load SThM standard sample with known melting point temperature. 4) Sweep the Probe Current signal and adjust the variable resistor located in the HEM with a flat head screw driver to establish same STHM Error value between 0mA and 0.1mA position.
Page 242 NX20 User’s Manual 8) Switch to TA spectroscopy mode by clicking the TA button in the spectroscopy view. 9) Open Spectroscopy Options window by clicking the Options button in the Setup menu. Set the parameters to prevent the tip from crashing into the sample surface as it is being moved to a new measurement location.
Page 243 Chapter 10. Approach Spectroscopy Figure 10-85. TA Start button b. Second is to add points to a list. Clicking on a location in the reference image, will add a point to the list. Points can also be added directly by entering values into the Points List, which is accessible by selecting the Edit Points item in the context menu Figure 10-86.
Page 244 NX20 User’s Manual Figure 10-87. Sample of points in a matrix (Refer to Section 9-2 Spectroscopy Positions View in the attached SmartScan manual for more information) 10) Set the parameters in the TA tab to obtain optimum data measurement. (Refer to Section 9-9 in the attached SmartScan manual) Figure 10-88.
Page 245 Chapter 10. Approach Spectroscopy Figure 10-89. Start button for acquiringspectroscopy data Once all of the measurement are complete, perform analysis by right-clicking on the file in the buffer window and select “Select to XEI”. (Refer to XEI manual for more information) Place a cursor pairs where A-B value changes dramatically on A-B vs Probe Current curve.
Page 246 NX20 User’s Manual Figure 10-91. SThM Error vs Probe Current 12) Open SThM reference calibration window as shown below and input the calibration value. Click the Apply button to start calibration. Figure 10-92. SThM reference calibration 13) Check the melting point with A-B vs SThM Temperature curve in XEI, after the temperature of nano thermal probe decreases.
Page 247 Chapter 10. Approach Spectroscopy curve after thermal calibration using standard sample with melting temperature at 55°C. Figure 10-93. A-B vs SThM Temperature...
Page 248: Chapter 11. Q Control Mode
NX20 User’s Manual Chapter 11. Q Control Mode The Q Control Mode enables the control of the quality factor of the cantilever while operating in Non Contact Mode and Dynamic Force Mode. The quality factor of the cantilever is inversely proportional to the viscous drag (damping) acting on the cantilever.
Page 249 Chapter 11. Q Control Mode Figure 11-1 Schematic diagram of Non Contact Mode When the cantilever is vibrated at the resonance frequency, a +90 degree phase difference between the driving signal (green) and output signal (yellow, VERTICAL (AC) signal occurs. Please see Figure 11-2. Frequency Figure 11-2 Phase shift between driving signal and ouput signal At this point, the phase changed is as shown in Figure 11-3.
Page 250 NX20 User’s Manual signal through VERTICAL signal is a Cosine function. Therefore, if the output signal is shifted to -90 degree and added to the input signal, the cantilever modulation is amplified about 10 in air. Figure 11-4 shows the cantilever modulation signal according to the phase shift.
Page 251 Chapter 11. Q Control Mode When the external driving force is applied in Non-Contact mode, the simple harmonic oscillation is expressed by the following equation. γ , k, and are the cantilever mass, damping constant, spring constant of the cantilever, and driving signal from NX-electronics respectively. When the Q control mode is enabled, the equation is as follows: G is the Q Control Gain and X(t) is the cantilever’s motion when time changes.
Page 252: Q Control User Interface
NX20 User’s Manual Figure 11-6 Modulation Amplitude Change according to gain (Left: Before Initial Calibration, Right: After Initial Calibration) 11-2. Q Control User Interface Clicking the ‘To Q Control” button on the Frequency Sweep Window will change the button to the ‘To Control’ button and change the UI of the Frequency Sweep Window.
Page 253 Chapter 11. Q Control Mode The negative input changes the Q value in the direction of decreasing Q. The positive input changes the Q value in the direction to increase Q. When you input ‘0’ on the text field on Q Amplify, Q control mode is deactivated. Figure 11-8 shows that Q value changes when Q amplify is set to -0.05(Left) and 0.05(Right) after the initial phase calibration is done.
Page 254: Q Control Procedure
NX20 User’s Manual Figure 11-9 Modulation Amplitude Change according to gain (Left: Before Initial Calibration, Right: After Initial Calibration)  Deactivate Q control mode is deactivated when the ‘Deactivate’ button is clicked. It means that the Q amplify value becomes 0. Figure 11-10 is shown when the ‘Deactivate’ button is clicked.
Page 255: Chapter 12. Magnetic Force Microscopy (Mfm)
This document is an operating manual for Magnetic Force Microscopy, one of the many application modes for the NX series SPM from Park Systems. MFM is a technique used to map magnetic properties of a sample surface by measuring the magnetic force between the magnetized tip and magnetic surface.
Page 256 NX20 User’s Manual Figure 12-1. Process of the SPM imaging...
Page 257 Chapter 12. Magnetic Force Microscopy (MFM) In the MFM mode of the NX SPM, sample is scanned twice to separate the signal. In first scan the tip scans the surface as in NC-AFM and the surface height of the sample is obtained.
Page 258: Components
NX20 User’s Manual 12-2. Components Required components for the MFM imaging are shown in the Figure 12-4 Figure 12-4. Required Components 1. Magnetizer 2. Magnetizer Clip 3. Standard Sample (a piece of hard disk) 4. Non magnetic sample holder 5. MFM Cantilevers (coated with magnetic materials such as Co-Cr, FeCoNi).
Page 259 Chapter 12. Magnetic Force Microscopy (MFM) Figure 12-5. Magnetizing the MFM tip 3. Insert the magnetizer clip in the magnetizer for 5 ~ 10 seconds as shown in Figure 4 (d). 4. Take magnetizer clip out and remove the cover. 5.
Page 260: Operation
NX20 User’s Manual Figure 12-6. Exchanging the Sample Holder 2. Mount the sample on the non magnetic sample holder by using the holder clips. Loose the screws holding clips. Place the clips on the sample. III. Tighten the screws to fix the sample well.
Page 261 Chapter 12. Magnetic Force Microscopy (MFM) Figure 12-8. Selecting the Head Mode and cantilever type 5. After selecting the MFM mode, turn on the laser beam by clicking 1) the ‘Line Scan on’ On/Off button in the toolbar. 2) ‘NCM Sweep’ window, which is similar to the ones encountered in NC-AFM will appear.
Page 262 NX20 User’s Manual Figure 12-9. Select the NCM Sweep 6. Figure 12-9 shows the Scan control window. There are many scan control parameters, however this manual will introduce only those required for MFM mode. Please refer to the SmartScan™ manual for a description of all other scan parameters in the Scan Control window.
Page 263 Chapter 12. Magnetic Force Microscopy (MFM)  MFM tip bias The MFM tip bias is a voltage applied to the tip when the system performs the second scan of the MFM mode to generate the MFM image. For some samples, according to the materials which it is made of, applying the MFM bias has effect of improving image quality.
Page 264 NX20 User’s Manual Figure 12-12. Selecting the monitoring signal in trace control window 9. Approach the tip to the sample as it is done in NC-AFM. For detailed procedure, refer to the NX user’s manual. After the approach is made, change the scan control parameters (Scan size, Slope, Scan rate, Z servo gain, Set point) to obtain an optimal surface height trace.
Page 265: Practice
Chapter 12. Magnetic Force Microscopy (MFM) 12-5. Practice Park Systems offers a standard MFM sample with MFM mode. Users can test their MFM and practice imaging skill by obtaining the MFM image of the standard sample and comparing it with the expected image. This section presents a typical image of a standard sample and expected result.
Page 266: Advanced Application
NX20 User’s Manual 12-6. Advanced Application Notes on MFM Imaging  Adjust scan parameters to obtain good Height image A bad Height image indicates that the distance between the sample and the tip is not constant, and MFM signals obtained when this is the case cannot be considered reasonable data.
Page 267 Chapter 12. Magnetic Force Microscopy (MFM)  MFM Signal Interference with Height signal Example [Height image] [MFM Phase image] Figure 12-15. Example of MFM signal interference in Height image [Height image] [MFM Phase image] Figure 12-16. Sample from Figure2, improved scan result As illustrated in Figure 12-15, the MFM signal can interfere with the Height signal when a sample has a strong magnetic force.
Page 268 NX20 User’s Manual  Height signal interference with MFM signal Example [Height image] [MFM Phase image] Figure 12-17. Example of Height signal interference in MFM image [Height image] [MFM Phase image] Figure 12-18. Sample from Figure4, improved scan result When obtaining MFM signals, the tip-sample distance is widened in...
Page 269 Chapter 12. Magnetic Force Microscopy (MFM) [Height image] [MFM Phase image] Figure 12-19. Sample with weak magnetic force The tip-sample distance must be increased in order to prevent Height signal interference with MFM imaging (as illustrated in Figure 12-17), but there are instances when a sample's magnetic force is too weak to detect at that range (as illustrated in Figure 12-19).
Page 270: Magnetic Field Generator (Optional)
NX20 User’s Manual 12-7. Magnetic Field Generator (Optional) The Magnetic Field Generator is an additional device for MFM used to apply an external magnetic field to the sample. When powered, a magnetic field is generated between the ends of the probe arm.
Page 271 Chapter 12. Magnetic Force Microscopy (MFM) 4. Magnetic Field Generator Main body B. Equipping The Magnetic Field Generator is attached to the NX Head. Figure 12-21 shows the Hem jig is attached to the NX Head (a) and screws are screwed to the Hem jig (b) and the Magnetic Field Generator Main body is attached to the Hem jig (c) and Hem jig is screwed to the Magnetic Field Generator.
Page 272 NX20 User’s Manual turn on the Power supply (c). Figure 12-22. Set up the Magnetic Field Generator Power C. Adjusting the field You can position the bracket and probe arms of the magnetic field generator to adjust the direction of the applied field. The bracket position can be adjusted back and forth as shown in the Figure 12-23(a) by loosening the two M1.5 fastening screws.
Page 273 Chapter 12. Magnetic Force Microscopy (MFM) D. Applying the field Supply DC voltage (-10V to 10V) to the generator. This produces a field of approximately 300~500G in the magnetic field generator. Check the MFG datasheet included in each MFG for detail information. Blow graph (Figure 12-24) shows the change in magnetic field supplying DC voltage twice from 0V ...
Page 274: Chapter 13. Force Modulation Microscopy (Fmm)
Chapter 13. Force Modulation Microscopy (FMM) This document is an operating manual for FMM (Force Modulation Microscopy) mode for Park Systems’ NX series SPM. FMM is used for investigating samples’ mechanical properties. During FMM measurements, the system scans the sample in contact mode while oscillating the tip.
Page 275 Chapter 13. Force Modulation Microscopy (FMM) Figure 13-1. Oscillating deflection of the cantilever The DC deflection signal represents average deflection of the tip, which depends on the force exerted on the sample. The Z feedback loop maintains the DC deflection signal and generates a topographic image.
Page 276: Operation
NX20 User’s Manual Figure 13-2. FMM Amplitude and FMM Phase Signal 13-2. Operation No additional NX hardware components are required for FMM imaging. Only the additional SmartScan™ software module for FMM needs to be installed to support the FMM mode. Setting up your NX SPM for FMM is same as that of the standard Contact AFM.
Page 277 Chapter 13. Force Modulation Microscopy (FMM) Figure 13-3. Changing the Head mode and select the cantilever 3. Open Input Config by selecting ‘Channel Config’ from the Setup menu. Select Z Drive, Z Height, FMM Amplitude, and FMM Phase input signals. Figure 13-4.
Page 278 NX20 User’s Manual  Set point The Set Point value for FMM is a force value. This represents the force that the cantilever is pressing down on the sample surface with. This value is maintained during the imaging. A higher value indicates a stronger force with which the cantilever presses on the sample.
Page 279 Chapter 13. Force Modulation Microscopy (FMM) 6. Approach the tip to the sample as with C-AFM. 7. Click the “Frequency sweep and set up” icon. The Frequency Sweep dialog will appear. 8. Input a Drive % value, and click the Refresh button. A resonance curve will automatically be selected.
Page 280 NX20 User’s Manual Figure 13-8. The trace control windows 11. Input a scan size suitable for an image scan. Change the scan control parameters (scan size, scan rate, Z servo gain, setpoint, and drive) to obtain an optimal signal trace. Click the ‘image’ button to get the FMM image.
Page 281: Chapter 14. Electrostatic Force Microscopy (Efm)
This document is an operating manual for Electrostatic Force Microscopy, one of the many application modes for the NX series SPM from Park Systems. EFM is a technique used to map electric properties on a sample surface by measuring the electrostatic force between the surface and a biased AFM cantilever.
Page 282: Principle Of Electrostatic Force Microscopy
NX20 User’s Manual 14-1. Principle of Electrostatic Force Microscopy Surface electrical property measured by EFM is acquired by the following process. Figure 14-1. Process of the EFM imaging For EFM, the sample surface properties would be electrical properties and the interaction force will be the electrostatic force between the biased tip and sample.
Page 283 Chapter 14. Electrostatic Force Microscopy (EFM) signal. To separate the EFM signal, Park Systems EFM uses the Lock-in Amplifier imbedded internally in NX electronics. In EFM, a Lock-in Amplifier is used for two purposes. One purpose is to apply AC bias of frequency ω, in addition to the DC bias applied by the NX controller, to the tip.
Page 284 NX20 User’s Manual signal with a frequency of ω is only read through internal Lock-in Amplifier. Figure 14-2. Diagram of 1) EFM, 2) EFM-DC Images can be generated from any of the above-mentioned signals. Analysis of an image involves understanding the contributions to the signal used to generate the image.
Page 285 Chapter 14. Electrostatic Force Microscopy (EFM) Amplifier, signal resulting from the tip’s motion by the force can be decomposed and analyzed into DC part and frequency ω part. ω part of the signal contains information of surface charge, . The frequency ω is chosen to be smaller(14~17kHz recommended) enough than the cantilever oscillation frequency(70~330kHz), so that the two signals do not interfere each other.
Page 286 NX20 User’s Manual 3. PFM (Piezoelectric Force Microscopy) PFM is to obtain characteristics of material in piezoelectric property. Materials which contain ferro-electricity can be determined the distribution of intrinsic remnant polarization by scanning 2D image. Also, size and direction of polarization can be estimated at one point by spectroscopy.
Page 287: Setup
Chapter 14. Electrostatic Force Microscopy (EFM) Figure 14-4. (Left)Surface Height, (Right)Surface Potential Surface Height Potential 14-2. Setup 1. Devices Set up your NX system as you would for the ordinary Contact/Non Contact AFM. For detailed instructions, refer to your NX user’s manual. Caution! You must set 0V for AC Amplitude before tip approaches to sample.
Page 288 NX20 User’s Manual Figure 14-5. Sample Preparation Silver Paste Tips! Sample bias will be applied through the sample holder and can be controlled by changing the ‘Sample bias’ value in the SMARTSCAN software. Setting the sample bias value to zero will have same effect as grounding the sample. But if needed, connect the ground wire or the proper external voltage line to the sample.
Page 289: Software Ui
Chapter 14. Electrostatic Force Microscopy (EFM) 14-3. Software UI The EFM modes can be classified by the method to acquire the sample height and result some difference in software UI. Please note that to improve the product, software UI can be changed without notice. 1.
Page 290 NX20 User’s Manual  Tip Bias Servo Gain The Tip Bias Servo Gain controls the sensitivity of SKPM feedback control. As this value is higher, the SKPM feedback will be better and the trace/retrace signal of Potential will be matched better. However, if this value is too high, the noise can be shown at Potential signal on the trace window such as Z servo gain parameter in NCM.
Page 291 Chapter 14. Electrostatic Force Microscopy (EFM) 3. Lock-in Setup Window UI Figure 14-9 shows the Lock-in Setup Window, displayed when [View->Lock-in Setup Window] on the Menus is selected. Figure 14-10. Lock-in Window 3-1. Lockin Config There is an independent lock-in channel for each lock-in(1/2/3/4) ...
Page 292 NX20 User’s Manual  Time Constant Set time constant on internal Lockin post filter which is a kind of ‘low pass filter’. Therefore, the filter order is set to ‘None’, and the time constant value will not contribute the signal since the low pass filter is not applied.
Page 293 Chapter 14. Electrostatic Force Microscopy (EFM)  Modulator Control Choose the desired channel for modulation. The selectable channels depend on the lock-in channel and the measurement head mode may select the modulation channel automatically.  Modulator Control Source for Lock-in 1: Selectable between ‘NCM Modulator’ or ‘Off’.
Page 294: Operation
NX20 User’s Manual  Drive Modulation Drive is selectable. In case of electrical properties measurement, if the Modulation Drive value increases too much, an electric field may form between tip and sample and may affect the sample surface potential. Thus, it is recommended to select lower than 2-3V.
Page 295 Chapter 14. Electrostatic Force Microscopy (EFM) *Note that to improve the product, software UI can be changed without notice. ① Head Mode: Select as ‘EFM’. Figure 14-12. Head Mode Setup ② Input Configuration(channels): Choose signals to be imaged. Recommend to set ‘Z Height’, ‘EFM Amplitude’, ‘EFM Phase’.
Page 296 NX20 User’s Manual Input Channel: A-B(Automatically selected) Phase: 0 Degree Time Constant: 1ms Sensitivity: 1V Filter: 2 Modulator Control: Tip Bias(Automatically selected) Frequency: 17 kHz Drive: 0V Caution! Before approach, please make sure that the modulator amplitude is set to zero so as to avoid any damage to the tip.
Page 297 Chapter 14. Electrostatic Force Microscopy (EFM) *Note that to improve the product, software UI can be changed without notice. ① Part Configuration: Head Mode-DC-EFM, Cantilever-loaded cantilever Figure 14-14. Head Mode Setup Note that when installed cantilever is not there, choose a similar spec cantilever and create a cantilever DB.
Page 298 NX20 User’s Manual ⑩ Monitor Window & Stage Control Window: Click ‘Approach’ button to approach the tip to the sample surface. If the approach is successful, the upper half of the Z scanner bar will turn green and the green light at the Stage Control Window will stop blinking.
Page 299 Chapter 14. Electrostatic Force Microscopy (EFM) ⑨ Trace Window/Lock-in Setup Window: In order to acquire optimized EFM Amplitude/Phase to appear, control the parameters such as Time Constant, Sensitivity and so on.  Start the PE Curve measurements ① Obtain EFM amplitude and Phase signal ②...
Page 300 NX20 User’s Manual ④ Set the lock-in parameter and start the PE curve measurements. ⑤ Set proper ‘Time constant’ in Lock-in amplifier. Figure 14-17. Time constant in Lock-in amplifier .
Page 301 Chapter 14. Electrostatic Force Microscopy (EFM) 3. SKPM(Scanning Kelvin Probe Microscope) Measurement SKPM measurement procedure is same as for the EFM or DC-EFM. The tip DC voltage is controlled by feedback to keep the potential difference between the tip and the sample at zero.
Page 302 NX20 User’s Manual Trace Mode&Lock-in Setup Window:Click the “Sweep” button. iii. Then, DC bias to the sample will be applied from -10V to 10V. The EFM phase curve versus potential is plotted. Adjust the “Phase” of the output signal on the Lock-In Amplifier control panel to center the curve in the window.
Page 303 Chapter 14. Electrostatic Force Microscopy (EFM) *Use Phase Only in Tip Bias Servo Both EFM Amplitude and EFM Phase [R sinө sinө : Modulator2 amplitude from Lock-in Amplifier setting, ө Modulator2 phase from Lock- :Current EFM amplitude, ө1:Current EFM Phase) in Amplifier setting, A will be used for SKPM tip bias feedback.
Page 304: Practice
NX20 User’s Manual 14-5. Practice Park Systems offers the EFM test sample with EFM mode. You can test your EFM and imaging skills by obtaining an EFM image of the test sample and comparing it with the expected image. This section describes the test sample and expected results.
Page 305 Chapter 14. Electrostatic Force Microscopy (EFM) B. Obtaining an EFM Image of the Test sample 1. Test Sample Installation: a. Mount the test sample on the sample holder. b. Connect the ground wire between ground slot and the grounding. 2. Head Mode: EFM, SKPM 3.
Page 306 NX20 User’s Manual Figure 14-24. Actual Height and EFM image of the test sample [Height Image] [Height line profile] Sample bias = -1V Sample bias = 1V [EFM Amplitude Image] [EFM Amplitude line profile] Sample bias = -1V Sample bias = 1V...
Page 307 Chapter 14. Electrostatic Force Microscopy (EFM) 2. DC-EFM A. Test Sample DC-EFM provides ferroelectric piezo material for the test sample. The thickness of piezo material(Zr/Ti composition) is approximately 150nm and the substrate is Ti/Pt on /Si wafer. The test sample Figure below shows the test sample electrically connected to the metal plate.
Page 308 NX20 User’s Manual C. Obtaining an EFM Image of the Test sample after Domain Switching This electric polarization of this piezo matrial can be reversed by external electric field. We can confirm it through DC-EFM after applying the +/- voltage to the tip.
Page 309 Chapter 14. Electrostatic Force Microscopy (EFM) atomic layers of carbon. is provided as the SKPM test sample. It is used a lot of applications by its atomic flatness, cleanness and conductivity. The parallelism of atomic layer is characterized by “mosaic spread angle” and the HOPG provided in SKPM has 0.7 degree high quality in it and 10 x 10 mm in size, 1.2 mm(±0.2) in thickness.
Page 310: Advanced Application
NX20 User’s Manual Figure 14-29. Expected results of the test sample Line Profile 14-6. Advanced Application Notes on EFM Imaging  Adjust scan parameters to obtain good Height image A bad Height image indicates that the distance between the sample and the tip is not constant –...
Page 311 Chapter 14. Electrostatic Force Microscopy (EFM) Figure 14-31. Line profiles of EFM Amplitude Image line profiles of each Image in Figure 14-30. 1): Figure 14-30-b, 2): Figure 14-30-a, 3): Figure 14-30-c When taking EFM scans, the EFM Amplitude image obtained may be blurry as shown in Figure 14-30-a, or noisy as shown in Figure 14-30-c.
Page 312 NX20 User’s Manual Time Constant setting  EFM Amplitude line profiles by Time constant setting. Figure 14-32-a. Time constant=1ms Figure 14-32-b. Time constant=3ms Figure 14-32-c. Time constant=5ms Figure.14-32: a) Time constant=1ms, b) Time constant=3ms, c) Time constant=5ms As in Figure 14-32-b and Figure 14-32-c, a long Time constant can result in lower signal detail and blurry images.
Page 313 Chapter 14. Electrostatic Force Microscopy (EFM)  When Surface potential affects Height signal There are instances when there is no large sample bias or applied sample bias but the EFM Amplitude signal and Z height signal's forward/backward don't match up or omits details as in Figure 14-33.
Page 314 NX20 User’s Manual Notes on SKPM Imaging  Adjust scan parameters to obtain good Topography results. Bad Topography results indicate that the distance between the sample and the tip is not constant - SKPM signals obtained when this is the case cannot be considered reasonable data.
Page 315 Chapter 14. Electrostatic Force Microscopy (EFM) while Figure 14-35-c shows an image which is noisy due to a large Tip bias servo gain value. Adjusting the Tip bias servo gain value can yield results such as Figure 14-35-b. In Figure 14-36, the line profiles of each SKPM Potential image in Figure 14-36 show noisier results with larger Tip bias servo gains and blurrier results with smaller Tip bias servo gains.
Page 316: Index
NX20 User’s Manual Index Detector Offset Calibration, 174 XY Scanner Calibration, 157 VERTICAL, 112 Z Scanner Calibration, 169 VERTICAL Sensitivity, 71, 73 Cantilever, 2, 61, 77, 86, 87, 88, 89, 91, 107, 123 Acoustic Enclosure, 36, 42, 45, 48, 59...
Page 317 Index Ethernet, 30 Error Signal, 95 External Sample Bias, 31 Force, 96 External Tip Bias, 31 Height, 95 Lateral Force, 96 NCM Amplitude, 95 FD Mode, 131, 133 NCM Phase, 96 Facility Requirement, 41 Z Drive, 95 Flexure Hinge, 22 Installation, 41 Focus Stage, 27, 85 Interatomic Force, 105, 107...
Page 318 NX20 User’s Manual Non-linearity, 3, 99 NX20 Main System Cables, 50 Sample Chuck, 24 NX20 Skin, 52 Sample Loading, 77 Set Point, 92, 123, 129 SLD, iv, 8, 20 Objective Lens, 28 SLD Detector Chip Carrier, 181 Open Loop, 99, 157...
Page 319 Index Tip Bias, 98 Open Loop, 158 Two way, 97 XY Servoscan, 99 X,Y, 97 XY Stage, 21 Z Servo, 98 XY Stage Jig, 54 Z Servo Gain, 98 XY stage Maintenance, 155 XY Detector, 157 XY Detector Calibration, 174 XY Scanner, 22, 99, 101, 157 Z Scanner, 6, 15, 17, 102, 169 XY Scanner Calibration...
Page 320 Please check that you think this comment is critical ( ) or moderate ( ) or minor ( ). Comments: Customer Information Name: Date: Company/Institution: System model: Address: E-mail: Fax: Country: Phone: You may fax this form or e-mail to Park Systems: Homepage: www.parkAFM.com info@parkafm.com E-mail: Address: KANC 4F, Iui-Dong 906-10, Suwon, Korea 443-766 Fax: +82-31-546-6805 Phone: +82-31-546-6800...
Page 321 Customer’s Document Feedback Form <Blank Page>...

Park Systems NX20 User Manual

Chapter 1. Introduction to Nx20

Chapter 2. Components of Nx20

Chapter 3. Installation

Chapter 4. Cantilever Selection

Chapter 5. Operation Procedure 5-1. Basic Procedure

Chapter 6. Afm in Contact Mode

Chapter 7. Lateral Force Microscopy (Lfm)

Chapter 8. Afm in Non-Contact Mode

Chapter 9. Dynamic Force Microscopy (Dfm)

Chapter 10. Approach Spectroscopy

Chapter 11. Q Control Mode

Chapter 12. Magnetic Force Microscopy (Mfm)

Chapter 13. Force Modulation Microscopy (Fmm)

Chapter 14. Electrostatic Force Microscopy (Efm)

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Summary of Contents for Park Systems NX20

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