Solver PRO-M Scanning Probe Microscope. SPM Controller

Transcription

1 Solver PRO-M Scanning Probe Microscope SPM Controller (models BL022MTM, BL022MRM) Reference Manual June, 2006 Copyright NT-MDT, 2006 Web Page: General Information: Technical Support: NT-MDT Co., building 167, Zelenograd, , Moscow, Russia Tel.: +7(495) Fax: +7(495)

2 Part 1. SPM Controller (models BL022MTM, BL022MRM) PART 1. SPM Controller (models BL022MTM, BL022MRM) Table of Contents 1. GENERAL INFORMATION ABOUT THE SPM CONTROLLER CONNECTING THE SPM CONTROLLER SCHEMATICS OF INTERCONNECTIONS OF THE CONTROLLER ORDER OF SWITCHING THE SPM CONTROLLER ON/OFF DESCRIPTION OF THE TERMINAL PANEL OF THE SPM CONTROLLER FUNCTIONAL MODULES OF THE SPM CONTROLLER CONVERTERS X, Y, Z AMPLIFIERS FEEDBACK SYSTEM MULTIPLEXERS DIGITAL SIGNAL PROCESSOR, DSP ENTRANCE PREAMPLIFIERS GENERATOR MODULE DRIVING MODULE OF THE APPROACH SYSTEM CONFIGURING OF THE SPM CONTROLLER CONFIGURATION MODES Configuring in the Manual Mode Configuring in the Automatic Mode CONFIGURATION OF THE SPM CONTROLLER FOR TUNING OF THE PROBE DEFLECTION DETECTION OPTICAL SYSTEM CONFIGURATION OF THE SPM CONTROLLER FOR CONTACT TECHNIQUES Constant Force Method Contact Error Method Lateral Force Imaging Method Constant Height Method Spreading Resistance Imaging Method Force Modulation Method Piezoresponse Force Microscopy Method CONFIGURATION OF THE SPM CONTROLLER FOR SEMICONTACT TECHNIQUES Semicontact Method of Topography Measurements Semicontact Error Mode Phase Imaging Method Electric Force Microscopy Method Scanning Capacitance Microscopy Method Magnetic Force Microscopy Method SPECTROSCOPY SPM CONTROLLER CONFIGURATION FOR SCANNING TUNNELING MICROSCOPY STM Constant Current Method STM Constant Height Method BASIC SAFETY MEASURES OPERATING CONDITIONS STORAGE AND TRANSPORT INSTRUCTIONS

3 Part 1. SPM Controller (models BL022MTM, BL022MRM). Table of Contents APPENDIXES OVERALL BLOCK-DIAGRAM OF THE SPM CONTROLLER REFERENCE TABLE OF MAIN SIGNALS CONNECTOR DIAGRAMS OF THE CONTROLLER BREAKOUT CONNECTIONS CONNECTOR DIAGRAM OF THE HEAD BREAKOUT CONNECTION (50-PIN D-TYPE PLUG) CONNECTOR DIAGRAM OF THE SCANNER BREAKOUT CONNECTION (37-PIN D-TYPE PLUG) CONNECTOR DIAGRAM OF THE CONTROLLER2 BREAKOUT CONNECTION (62-PIN D-TYPE PLUG) CONNECTOR DIAGRAM OF THE EXTENSION ADDITIONAL BREAKOUT CONNECTION (50-PIN D-TYPE PLUG) CONNECTING EEXTERNAL DEVICES (CONNECTOR EXTENSION) TESTING THE SPM CONTROLLER

4 Part 1. SPM Controller (models BL022MTM, BL022MRM) 1. General Information about the SPM Controller The purpose of the SPM Controller is to drive by scanning probe microscopes: Processing of signals acquired by measurement heads; Conversion of driving signals sent from the «Nova» computer program; Generation of driving signals for the scanners and the piezo-driver of the probe; Operations with auxiliary devices. Depending of the model, controllers are available in two types of cases: Tower (model BL022MTM) and Ratiopac Pro (model BL022MRM). Fig. 1-1 demonstrates the Tower type of SPM Controller cases: Fig The Tower type of SPM Controller cases Fig. 1-2 demonstrates the Ratiopac Pro type of SPM Controller cases: Fig The Ratiopac Pro type of SPM Controller cases 1-4

5 Chapter 1. General Information about the SPM Controller Controllers of the Ratiopac Pro type are contained within a special electronics cabinet. Fig. 1-3 gives an overall view of an electronics cabinet: Fig Electronics cabinet Dimensions and weights of the available models of the SPM Controller are given in Table 1-1. Model SPM Controller dimensions (W L H), mm Weight, kg BL022MTM BL022MRM Table

6 Part 1. SPM Controller (models BL022MTM, BL022MRM) 2. Connecting the SPM Controller 2.1. Schematics of Interconnections of the Controller A number of devices can be connected to the controller by means of cables. These devices are connected according to the following schematics of interconnections (Fig. 2-1, Fig. 2-2, Fig. 2-3). Fig Measuring head with sensors + exchangeable scanner without sensors configuration Fig Measuring head without sensors + exchangeable scanner without sensors configuration 1-6

7 Chapter 2. Connecting the SPM Controller Fig Measuring head without sensors + exchangeable scanner with sensors configuration 2.2. Order of Switching the SPM Controller on/off The SPM Controller has the following input power requirements: VAC at Hz. Power consumption is 80 W. The order of switching the SPM Controller and computer is as follows: 1. Turn the computer on. Start the driving software up. 2. Turn the SPM Controller on using the switch located on the front panel. If the startup procedure has been completed successfully, a green tick will appear in the bottom left corner of the driving software s main graphics window. 1-7

8 Part 1. SPM Controller (models BL022MTM, BL022MRM) 2.3. Description of the Terminal Panel of the SPM Controller An overall view of the terminal panel of the SPM Controller is given below (Fig. 2-4). Fig Overall view of the terminal panel of the SPM Controller POWER power supply input; COMPUTER serial port for a PCI (or PCMCIA) interface board (4 Mb/s); SCANNER - 2 equivalent 37-pin connectors for scanners; HEAD - 50-pin connector for the measuring head; EXTENSION - 50-pin connector for external devices; OSC BNC connector for an external oscilloscope; GROUND grounding terminal; FUSE fuse; CONTROLLER2-62-pin connector for the main module. A voltage switch to select between 120/240 VAC is located in the top left corner of the panel. 1-8

9 Chapter 3. Functional Modules of the SPM Controller 3. Functional Modules of the SPM Controller Main functional modules are presented in Appendixes (see i. 2 page 1-60), in the SPM Controller block-diagram Converters Converters are used for the acquisition of signals proportional to the logarithm of input current, oscillation amplitude of the probe in modulation methods (synchronous registration is required), RMS value, phase difference between the input and the actuating signals. All signals go through low-pass filters of the 2 nd order with a tunable range 100 Hz 50 khz. In modulation methods, the operational frequency lies within khz for STM and within 1 khz 1.8 MHz for AFM. Synchronous registration of signals is only performed at frequencies which are multiple with respect to the frequency of the actuating signal. Using a conductive probe, it is possible to maintained one of the parameters of oscillation (phase, amplitude etc.) constant. These parameters of oscillation are kept constant by variations of voltage applied to the probe X, Y, Z Amplifiers X, Y, Z amplifiers are used to amplify signals which drive the scanner. X, Y, Z scanners have the same design. Each of them consists of a 22-bit composite DAC (Digital-to-Analog Converter) and a tandem high voltage output amplifier. Bipolar voltage V is supplied to drive the scanner. The resultant voltage applied to the scanner varies from V to +300 V Feedback System The feedback system consists of an integrator, high voltage amplifier (with tunable gain coefficient and the possibility to reset and store data), amplifier of the error signal and a precision 16-bit composite DAC Multiplexers Three groups of multiplexers are used for signal commutation. The first one operates with input signals. The second is responsible for independent synchronous measurements of three ADCs (Analog-to-Digital Converter). The third group is responsible for the selection of output signals applied to the feedback loop, control of the input electrical current magnitude, amplitude modulation etc. A list of all signals is provided in the Appendixes (see Item 2 on page 1-60). 1-9

10 Part 1. SPM Controller (models BL022MTM, BL022MRM) 3.5. Digital Signal Processor, DSP Digital processor ADSP-2185 is used to control the entire device. These functions, as well as communication with and identification of the nodes of the instrument, are performed through I2C bus Entrance Preamplifiers Entrance preamplifiers are integral parts of all scanning heads. Two types of entrance preamplifiers are used for STM measurements. They operate within different electrical current ranges: 30 pa and 10 pa and they perform current-to-voltage conversion. Their impedance is, respectively, 20 MOhms and 200 MOhms, maximum input current is 50 na and 5 na and bandpass is 10 khz and 3 khz. A 1MHz bandpass entrance preamplifier is used for AFM measurements with four-section photodiode. Its circuit, consisting of integral / differential amplifiers, converts current of the four input signals into voltage that is proportional either the displacement of the laser spot in the lateral and normal directions or the full signal from the photodiode Generator Module The generator module consists of four independent 32-bit signal generators. Two of them, sin(wt) and cos(wt), are used for synchronous amplification, while the other two generators are used to form signals with defined amplitude, frequency and phase. The frequency, amplitude and the phase are set independently from each other. The minimum step resolution is 0.01 Hz for frequency and 0.1 for phase. The AC voltage amplitude can vary from 1 mv to 10 V with 1 mv step resolution. A quartz generator operating at 40 MHz is used as a source of oscillations Driving Module of the Approach System Driving module of the approach system consists of two 12-bit DACs (20 V from maximum to maximum voltage, 130 ma maximum current). With their use, the program generates two sinusoidal signals with a 90 phase shift. These signals are applied to two power amplifiers and, then, to the stepper motor. 1-10

11 Chapter 4. Configuring of the SPM Controller 4. Configuring of the SPM Controller 4.1. Configuration Modes Configuring of the SPM Controller is performed through software. It can be done using two modes: manual and automatic Configuring in the Manual Mode Configuring in the manual mode is performed by means of the interactive block-diagram of the instrument (see Fig. 4-1) and by settings values in the Panel of main parameters (see Fig. 4-2). Fig Block-diagram of the instrument Fig Panel of main parameters 1-11

12 Part 1. SPM Controller (models BL022MTM, BL022MRM) Configuring in the Automatic Mode Configuring in the automatic mode is perform by selecting a corresponding option from the list of electronic configuration options: Fig List of configuration options for the instrument Automatic switching in performed in the instrument during this procedure Configuration of the SPM Controller for Tuning of the Probe Deflection Detection Optical System The optical system of the probe deflection detection and signals acquired by the SPM Controller from the probe are schematically depicted in Fig Fig Operational schematics of the registration system The SPM Controller acquires three signals: A-C the difference between the corresponding diagonal sections of the four section photodiode; B-D the difference between the corresponding diagonal sections of the four section photodiode; LASER. 1-12

13 Chapter 4. Configuring of the SPM Controller The following signals contain information: DFL signal proportional to the magnitude of deflection of the probe with respect to the normal (see Fig. 4-5). The DFL signal is the difference between signals from top and the bottom halves of the photodiode (see Fig. 4-4). DFL=(A+B) - (C+D) Fig. 4-5 LF signal proportional to the torsion deflection of the probe caused by lateral forces (see Fig. 4-5). The torsion deflection of the probe causes the laser beam reflected from the probe to shift in the lateral direction. The corresponding signal LF is the difference between signals from the right and left sides of the photodiode (see Fig. 4-4). LF = (A+C) - (B+D). LASER integrated signal from all the four sections of the photodiode. This signal is proportional to intensity of the laser beam reflected from the probe. LASER=A+B+C+D. Signals DFL, LF and LASER are displayed in the Aiming graphics window. Also, this window Aiming shows the position of the laser beam with respect to the center of the foursection photodiode (see Fig 4-6). 1-13

14 Part 1. SPM Controller (models BL022MTM, BL022MRM) Fig 4-6. Graphics window Aiming Signals DFL and LF are used during alignment of the registration system to control the pointing of the laser beam at the tip of the probe. These signals are regulated with the photodiode positioning screws located on the measuring head. Once the laser beam is precisely at the probe tip, the values of DFL and LF are equal to 0. The value of signal intensity, LASER, should be set maximum. Tuning of this signal is performed by means of the alignment screws of the photodiode Configuration of the SPM Controller for Contact Techniques Contact methods of atomic force microscopy are based on surface topography measurements during contact scanning of the sample surface. In the Constant Force Method, which is the main technique, a constant value of contact force between the sample and the probe is maintained during scanning. The contact force constancy is performed by keeping the DFL signal constant and is maintained by means of a feedback system which controls vertical displacement of the probe. In this technique, the vertical driving signal, which is applied to the Z section of the piezo scanner, is used to build an image of the surface topography. 1-14

15 Chapter 4. Configuring of the SPM Controller Surface scanning with constant contact force between the probe and sample lies in the basis of several other scanning techniques: Contact Error Method. In this method, the signal error of the feedback system is registered; Constant Height Method. In this method the feedback system is set maximum coarse and it traces smooth variations of the surface topography; Lateral Force Imaging. In this method, torsion deflections of the probe are registered; Force Modulation Method. In this method, the constant contact force is modulated with some sinusoidal vertical force. The local force response from the surface is derived from the modulation amplitude of the probe deflection; Spreading Resistance Imaging. In this method, while scanning the surface, electrical current is applied though the probe to the sample and is measured as a function of the probe position on the surface Constant Force Method In the Constant Force Mode of measurements, the signal DFL, which is proportional to the magnitude of deflection of the probe, is the main characteristic of the state of the probe. The DFL signal is the input signal for the feedback system, which maintains the value of this parameter equal to the value of Set Point. An operation block-diagram of the instrument in the Constant Force Mode is shown in (Fig. 4-7). 1-15

16 Fig Operation block-diagram of the instrument in the Constant Force Mode

17 Chapter 4. Configuring of the SPM Controller The DFL signal, acquired from the registration system, is compared with a pre-set value of Set Point, and the offset signal, which is (DFL-Set Point), is applied to the input of the integrator (Fig. 4-7). This offset signal is then amplified, integrated and is fed to a high voltage amplifier and to an AD converter with a programmable gain coefficient. The value of this ADC gain coefficient can be set in the field of the Scan Setup window (Fig. 4-8). Fig. 4-8 After the high voltage amplifier, the signal is applied to the piezo scanner which drives the probe so as to compensate the offset. Therefore the feedback system maintains the value of the DFL signal close to the value of Set Point. Operational accuracy of the integral feedback loop depends on the FB Gain coefficient, which can be set in the field of the FB Gain window (see Fig. 4-9). Fig. 4-9 NOTE. Fast response from the feedback loop is necessary to achieve maximum speed of scanning. Therefore the FB Cain value should be set as high as possible. However, a too big value can exceed the generation threshold. Operations at this threshold are characterized with induced auto-oscillations and lower accuracy of measurements. On the other hand, with too low FB Gain, the feedback loop does not recognize rapid variations of the sample profile. This, in turn, results in low accuracy of measurements. Therefore each given probe-sample system has an optimal FB Gain value, which provides maximum accuracy and reliability in operation. 1-17

18 Part 1. SPM Controller (models BL022MTM, BL022MRM) Contact Error Method In this method, the surface topography, obtained by the Constant Force technique, is simultaneously accompanied by measurements of the DFL signal error of the feedback system. During scanning, the current value of the DFL signal is treated as a signal error of the feedback system and it contains additional information, with respect to the position of the Z scanner, on the profile of the surface. This signal is used for a more detailed reconstruction of the surface topography. An operation block diagram of the instrument in the Contact Error Mode is shown in (Fig. 4-10). 1-18

19 Fig Operation block-diagram of the instrument in the Contact Error Mode

20 Part 1. SPM Controller (models BL022MTM, BL022MRM) During operation in this mode, measurements of the DFL signal are performed through the second measurement channel. The window Scan Setup of the panel of the measurement channels (Fig. 4-11) is used to select the DFL option. Fig Once the scanning procedure is performed, images of the surface topography, Height, and the signal error, DFL, are visualized in the graphics image windows Lateral Force Imaging Method Physical principles of the Lateral Force Imaging method are as follows. While scanning in this mode in the direction perpendicular to the longitudinal axis of the probe, a torsion deflection of the probe, which is additional to the normal deflection, occurs. Lateral force acting on the probe causes it. The information characterizing this effect is contained in the LF signal. The angle of twist of the probe is proportional to lateral forces. While moving the probe along a flat surface, which has segments with different friction coefficients, the twist angle of the probe will change from one segment to another. This contains information on distribution of local friction properties. An operation block diagram of the instrument in the Lateral Force Imaging mode is shown in (Fig. 4-12). 1-20

21 Fig Operation block-diagram of the instrument in the Lateral Force Method

22 Part 1. SPM Controller (models BL022MTM, BL022MRM) To configure the SPM Controller to operate in this mode, set Lateral Force in the Mode menu as shown in Fig. 4-13: Fig During operation in this mode, measurements of the LF signal are performed through the second measurement channel (see Fig. 4-14). Fig Once the scanning procedure is performed, images of the surface topography, Height, and the LF signal are visualized in the graphics image windows. 1-22

23 Chapter 4. Configuring of the SPM Controller Constant Height Method In this method, the probe is in permanent contact with the surface. The probe s tip is maintained at a constant height, while the value of deflection of the probe contains information on the sample surface topography. The speed of surface topography measurements is limited in this method by resonance properties of the probe. This is unlike the Constant Force Method, which is limited by properties of the feedback system. Resonance frequencies of probes are much greater than the characteristic frequency of the feedback system, which is equal to several units of khz. This gives an opportunity to scan samples at higher speed. Assume that the relationship between the value of the probe deflection versus the distance from the tip of the probe and the surface is known for a given probe (i.e. the relationship between the DFL signal and the distance Z from the tip of the probe an the surface). Then an image of the DFL signal distribution can be converted into a topography image. An operation block-diagram of the instrument in the Constant Height Mode is shown in (Fig. 4-15). 1-23

24 Fig Operation black diagram of the instrument in the Constant Height Mode

25 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Contact Constant Height in the Mode menu as shown in Fig and Fig Fig Fig After setting Contact Constant Height, the value of FB Gain (feedback system gain coefficient) is automatically set close to 0. This is equal to disabling the feedback loop and setting the probe with respect to the surface at a fixed height Spreading Resistance Imaging Method This method is based on the use of a conductive probe which is in contact with the surface of the sample under study. Bias voltage, Bias V, is applied to the probe and measurements of the resultant electrical current Ipr_low leaking locally through the sample are performed. These electrical current measurements are performed simultaneously with surface topography measurements in the Constant Force mode. An operation block-diagram of the instrument in the Spreading Resistance Imaging Mode is shown in (Fig. 4-18). 1-25

26 Fig Operation block-diagram of the instrument in the Spreading Resistance Imaging Mode

27 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Spreading Resistance in the Mode menu as shown in Fig Parameters Height and Ipr_low, required for measurements, are set automatically. Fig The value of the bias voltage, Bias V, which is the difference between electrical potentials of the probe and the sample, is set the in the corresponding window as shown in Fig Fig Once the scanning procedure is performed, images of the surface topography, Height, and the measured distribution of electrical current, Ipr low, are visualized in the graphics image windows Force Modulation Method In this method, scanning of the sample is done as in the Constant Force Method with, in addition, the scanner (or the sample) performing vertical periodic oscillations simultaneously. During this procedure, the pressure of the probe on the sample is not constant and it contains a periodic component (typically sinusoidal). Depending on local stiffness, the value of the measured corresponding surface deformation will change during scanning. Those segments with more solid surface will have smaller deformations, while softer segments will have bigger. Tracing of the surface topography is performed with the use of the averaged value of the probe deflection in the feedback loop. An operation block-diagram of the instrument in the Force Modulation Mode is shown in (Fig. 4-21). 1-27

28 Fig Operation block-diagram of the instrument in the Force Modulation Mode

29 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Force Modulation in the Mode menu as shown in Fig Fig The window of parameters (Fig. 4-23) is used to set the amplitude, frequency and phase of AC voltage applied to the Z electrode of the scanner, and also to set parameters of the lockin amplifier (Lock-In). Fig Once the scanning procedure is performed, images of the surface topography, Height, and the measured distribution of local stiffness, Mag, are visualized in the graphics image windows Piezoresponse Force Microscopy Method The principles of Piezoresponse Force Microscopy are based on the application of a local electrical field to the surface of a piezo-electric sample and subsequent analysis of the resulting displacement of the surface. This method is realized in the process of AFM scanning of a ferroelectric sample using a Constant Force Method. An electrical potential is applied to the conductive probe tip, which induces a local (underneath the tip) electrical field. Since ferroelectrics typically have the domain structure, the application of an identical local electrical field to different segments of the surface will bring different results. An operation block-diagram of the instrument in the Piezoresponse Force Microscopy Mode is shown in (Fig. 4-21). 1-29

30 Fig Operation block-diagram of the instrument in the Piezoresponse Force Microscopy Mode

31 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Piezoresponse Force Microscopy in the Mode menu as shown in Fig Fig The following settings and procedures required to operate in this mode are performed automatically: Electrical voltage from the generator is applied to the probe sensor (position 1 in Fig. 4-26); Maximum gain coefficient is set for the lock-in amplifier (position 2 in Fig. 4-26); The DFL signal is applied to the input of synchronous detector (position 3 in Fig. 4-26). Fig The following parameters are selected for measurement during scanning (Fig. 4-27): In the forward direction: Height and Mag; In the reverse direction: Phase. 1-31

32 Part 1. SPM Controller (models BL022MTM, BL022MRM) Fig Once the scanning procedure is performed, images of the surface topography, Height, and the measured Mag and Phase signals are visualized in the graphics image windows (see i. 4.4 on page 1-32) Configuration of the SPM Controller for Semicontact Techniques During operation in this mode, scanning is performed with a probe oscillating at the surface of the sample. The probe oscillates in the vertical direction at its resonant frequency (or close to it). The probe is a resonant system with high Q-factor and a fairly high resonance frequency, typically greater than 100 khz. The probe oscillation amplitude typically lies in between 1 nm and 100 nm. Generation of mechanical oscillations of the probe is done by means of a piezo drive, which is in direct contact with the chip of the probe. Specifics of this technique are linked with the fact that the oscillating probe is so close to the sample surface that, while scanning, it slightly touches the surface. Note that most of the oscillation time the probe is not in contact with the surface and its interaction with the sample is relatively weak. Only on approach to the surface, up to the region where the interaction potential becomes repulsive, the interaction effect becomes significant. During this impact the probe loses the energy accumulated during the rest of the period. Depending on the character of interactions, such parameters as the main harmonic phase shift and, also, amplitudes and phases of higher harmonics can alter with respect to the excitation signal. The laser beam of the registration system is reflected from the oscillating in the vertical direction probe. These oscillations of the probe result in oscillations of the laser beam spot with respect to the top and bottom halves of the photodiode. This induces a variable electrical signal, at the probe oscillation frequency, at the output of the registration system. The amplitude of this signal is proportional to the oscillation amplitude of the probe. In the 1-32

33 Chapter 4. Configuring of the SPM Controller case under consideration this signal is the variable component of the DFL signal detected at the probe oscillation frequency. Therefore the registration system measures the probe oscillation amplitude and converts it into an electrical signal in the form of a variable component of the DFL signal. Then, processing of the variable component of the DFL signal takes place: filtering, amplification and detection. The SPM Controller provides several options for processing of the variable component of the DFL signal; either of them can be selected. The variable component of the DFL signal can be applied to the input of: Lock-In amplifier; RMS detector; Phase detector. The Lock-In amplifier generates three output electrical signals: MAG, corresponds to the amplitude of the variable component of the DFL signal at the modulation frequency; MAG*sin, is proportional to the product of the MAG value and the value of sine of the probe oscillation phase shift with respect to the reference signal applied to the Lock-In amplifier; MAG*cos, is proportional to the product of the MAG value and the value of cosine of the probe oscillation phase shift with respect to the reference signal applied to the Lock-In amplifier. The value of the probe oscillation phase shift with respect to the reference signal is the sum of the probe oscillation phase shift with respect to the excitation signal and the phase shift between the excitation and reference signals (with accuracy to a constant). The RMS detector generates a RMS signal, which is proportional to the Root Mean Square of the variable component of the DFL signal within the whole frequency band of the detector. The Phase detector generates a signal, PHASE1, whose value variations are proportional to variations of the probe oscillation phase shift with respect to the excitation signal. Signal PHASE1 is the sum of the probe oscillation phase shift with respect to the excitation signal and the phase shift between the excitation and reference signals (with accuracy to a constant). Either of the enumerated signals can be included into the feedback system by making a selection from the list of options in the popup window available from the block-diagram of the instrument (Fig. 4-1) as shown in Fig

34 Part 1. SPM Controller (models BL022MTM, BL022MRM) The set of signals available from the list of options depends on the configuration set in the panel of main parameters. Fig List of options popup window. During operations in the semicontact mode, the probe oscillation amplitude is used as a parameter to characterize the interaction between the probe and the sample surface. Operation with the scanning probe microscope in the mode when the probe oscillation amplitude is kept constant is the basis mode for topography measurements. The task of maintaining the probe oscillation amplitude constant is achieved by keeping the signals, proportional to the oscillation amplitude, at the same level. Signals MAG and RMS are such signals and either of them can be used as input signals for the feedback system for topography measurements. However the use of signal MAG is most preferable since in that case it is possible to achieve a lower noise level. As a result, since synchronous detection is used, it is possible to gain higher resolution. This signal is engaged into the feedback loop by means of the interactive block-diagram of computer control of the instrument (Fig. 4-1). 1-34

35 Chapter 4. Configuring of the SPM Controller Semicontact Method of Topography Measurements In the Semicontact Method, topography measurements are performed in the mode of maintaining of the probe oscillation amplitude constant. This is achieved be keeping the MAG signal at a constant level. Note that MAG has been selected as the input signal for the feedback system. The overall operation principles are in many aspects similar to those of contact techniques. Alignment of the probe deflection optical registration system is performed before operations. Then, the values of amplitude, frequency and phase of probe oscillations are set in the window of the generator parameters. The initial value of MAG is set by means of setting the value of the parameter Set Point. Therefore some value of the probe oscillation amplitude and, respectively, some level of interaction between the probe tip and the sample surface are set. As MAG is the input signal for the feedback system, this parameter is maintained to be equal to the pre-set value of parameter Set Point. Unlike contact techniques, in this case the value of probe oscillation amplitude, which is the measure of interaction between the probe and sample, is kept constant during scanning. This is achieved by the feedback system by means of maintaining the pre-set level of MAG. An operation block-diagram of the instrument in the Semicontact Mode of topography measurements is shown in (Fig. 4-29). 1-35

36 Fig Operation block-diagram of the instrument in the Semicontact Mode of topography measurements

37 Chapter 4. Configuring of the SPM Controller During the scanning procedure, the value of the probe oscillation amplitude varies from point to point depending on the surface topography. Consequently, the current value of MAG varies with respect to the level Set Point at each point of the surface. Therefore the feedback system attempts to restore the probe oscillation amplitude to its initial value by moving the probe, using the scanner, in the normal to the surface direction so as to compensate the offset between MAG and Set Point. The error signal, (MAG-Set Point), is also applied to the amplifier with a regulated gain coefficient. The following parameters are set in the panel of the Lock-In amplifier (Fig. 4-30). Fig Low-pass filter cutoff frequency. This filter serves to minimize high frequency noise. Signals whose modulation frequency exceeds the indicated in Low Pass upper bound value will be cut off by the filter; Gain coefficient of the Lock-In amplifier. Varies from 1 to 100; The harmonic to be amplified. The Lock-In amplifier of the instrument allows operations with the first nine harmonics of the input signal. Amplification of the first harmonic is used in most methods. The second, or the third, harmonics are used in capacitance methods; Frequency range of the signal to be amplified; Gain coefficient of preliminary amplification of the signal applied to the input of the Lock-In amplifier. Once the scanning procedure is performed, an image of the surface topography, Height, is visualized in the graphics image windows. 1-37

38 Part 1. SPM Controller (models BL022MTM, BL022MRM) Semicontact Error Mode In this mode measurements of surface topography are performed simultaneously with measurement of the error signal MAG. During scanning, the current value of the MAG signal contains additional information on features of the surface. This signal is used for a more detailed reconstruction of the surface topography. An operation block-diagram of the instrument in the Semicontact Error Mode is shown in (Fig. 4-31). 1-38

39 Fig Operation block-diagram of the instrument in the Semicontact Error Mode

40 Part 1. SPM Controller (models BL022MTM, BL022MRM) During operation in this mode, measurements of the MAG signal are performed through the second measurement channel (Fig. 4-32). Fig Once the scanning procedure is performed, images of the surface topography, Height, and the signal MAG are visualized in the graphics image windows Phase Imaging Method Measurements of the probe oscillation phase shift (signal Phase) are performed in this mode. When the oscillating probe comes in contact with the sample surface, it experiences both repulsive and also adhesive, capillary and some other forces. As a result of such interactions, a shift of both frequency and phase occurs. If the sample surface is inhomogeneous by its properties, the phase shift distribution will also be inhomogeneous. A distribution of the phase shift over the sample surface reflects distributions of properties of the material under study. An operation block-diagram of the instrument in the Phase Imaging Mode is shown in (Fig. 4-31). 1-40

41 Fig Operation block-diagram of the instrument in the Phase Imaging Mode

42 Part 1. SPM Controller (models BL022MTM, BL022MRM) To configure the SPM Controller to operate in this mode, set Phase Contrast in the Mode menu as shown in Fig Fig Signal Phase can vary from 0 to 180 degrees depending on the initial phase of the generator, which in turn can vary from 0 to 360 degrees. Once the scanning procedure is performed, images of the surface topography, Height, and the signal Phase are visualized in the graphics image windows Electric Force Microscopy Method This method is a two-pass technique. The first pass is performed using the Semicontact method (see Item on page 1-35). An operation block-diagram of the instrument in the Electric Force Microscopy Mode is shown in (Fig. 4-35). 1-42

43 Fig Operation block-diagram of the instrument in the Electric Force Microscopy Mode

44 Part 1. SPM Controller (models BL022MTM, BL022MRM) To configure the SPM Controller to operate in this mode, set Electrostatic Force in the Mode menu as shown in Fig Fig Once the scanning procedure is performed, images of the surface topography, Height, and the signal Phase are visualized in the graphics image windows Scanning Capacitance Microscopy Method This method is a variation of the method of Electric Force Microscopy. In the general case, a bias voltage V tip =V dc + V ac *sin(wt), where V ac actuates oscillations, is applied to the probe. Scanning is conducted at some height, h, above the sample surface following its topography determined during the first pass using a Semicontact method. Measurements are performed on the second harmonic. An operation block-diagram of the instrument in the Scanning Capacitance Microscopy Mode is shown in (Fig. 4-37). 1-44

45 Fig Operation block-diagram of the instrument in the Scanning Capacitance Microscopy Mode

46 Part 1. SPM Controller (models BL022MTM, BL022MRM) To configure the SPM Controller to operate in this mode, set Capacitance Contrast in the Mode menu as shown in Fig Fig The variable component of bias voltage, Bias V, is set in the panel of settings of the generator (Fig. 4-39). The probe oscillation amplitude, Mag, is set as the signal for measurement. The second harmonic is selected in the Lock-in amplifier settings (Harm = 2). Fig Once the scanning procedure is performed, images of the surface topography, Height, and the signal Mag are visualized in the graphics image windows. 1-46

47 Chapter 4. Configuring of the SPM Controller Magnetic Force Microscopy Method This method is a two-pass technique. Surface topography is measured using a contact or a semicontact method during the first pass. On the second pass, the probe is lifted and kept above the surface; so magnetic scanning is performed using the surface profile acquired immediately before. Therefore the distance between the surface and the probe tip is maintained constant during the second pass. This makes it possible to acquire surface topography and magnetic images simultaneously. An operation block-diagram of the instrument in the Magnetic Force Microscopy Mode is shown in (Fig. 4-40). 1-47

48 Fig Operation block-diagram of the instrument in the Magnetic Force Microscopy Mode

49 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set AC Magnetic Force in the Mode menu as shown in Fig Fig Once the scanning procedure is performed, images of the surface topography, Height, and the signal Phase are visualized in the graphics image windows Spectroscopy The dependence of one signal on another is called spectroscopy. Spectroscopy measurements cam be taken both at one point and at several point of a line (or nodes of a grid). The following types of spectroscopy can be specified: Force spectroscopy; Adhesion force spectroscopy; Amplitude spectroscopy; Phase spectroscopy; Frequency spectroscopy; Resonance spectroscopy. A digital feedback loop is used for Z to perform all spectroscopy measurements. An operation block-diagram of the instrument for measurement of the functional dependence of DFL on Height is shown in Fig

50 Fig Operation block-diagram of the instrument for measurement of the functional dependence of DFL on Height

51 Chapter 4. Configuring of the SPM Controller 4.6. SPM Controller Configuration for Scanning Tunneling Microscopy The operation principles of Scanning Tunneling Microscopy are based on the phenomenon of electron tunneling through the potential energy barrier separating the metal probe and a conductive sample in the presence of an external electric field. The application of a potential difference V to a tunneling contact induces a tunneling current. The feedback system maintains the value of the tunneling current flow between the probe and sample at a pre-set level. Control of this value and, consequently, the distance between the probe and surface is performed by means of moving the probe along the Z axis using a piezo-element. The image of the surface in STM is formed by two methods: STM constant current method and constant height method STM Constant Current Method In this mode, the probe moves along the surface performing raster scanning. Feedback loop voltage variations of the Z piezo-element electrode, which imitate surface topography with high accuracy, are reproduced using the software tools. Tunneling voltage and current flow operation parameters are set at the start and, then, the probe-surface approach system is enabled. The driving voltage is applied to the stepper motor. The scanner is fully extended towards the sample in the initial state. An operation block-diagram of the instrument in the STM Constant Current Mode is shown in (Fig. 4-43). 1-51

52 Fig Operation block-diagram of the instrument in the STM Constant Current Mode

53 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Constant Current in the Mode menu as shown in Fig Fig Once a tunneling current flow is detected, the feedback system moves the probe backwards starting therefore the procedure of precise alignment of the sample. During this procedure, mutual movements of the probe and sample are taking place until the scanner takes up the middle of its dynamic range. Note that the feedback system is maintaining the pre-selected value of tunneling current. Either signal Ipr low, which is the current flow through the probe and sample (through an STM pin or conductive probe), or Ipr log, which is a signal derived from Ipr low using a logarithm converter, can be used as the feedback system input signal. The Ipr low signal is preferred for the approach procedure and for scanning of low-conductive samples, when the tunneling current is about na. For STM measurements of high-conductive samples, when the tunneling current is about 1 5 na, it is recommended to use Ipr log after the approach procedure is completed as the feedback system input signal. While scanning, the feedback system is maintaining the tunneling current flow at a constant level. This is done in the following way. The true instant value of current Ipr_low is compared, by means of a differential amplifier, with the pre-set value of parameter Set Point. The obtained value of the error signal is amplified and then applied to the internal Z electrode of the scanner. Therefore, the voltage applied to the Z electrode of the scanner is proportional to the profile of the surface measured STM Constant Height Method In this mode, the probe moves above the surface at a height of several angstroms. All variations of the tunneling current are registered in the STM image of the surface. Scanning is performed either with the feedback system disabled or at speeds greater then the response speed of the feedback loop. So, the feedback system only responds to smooth variation of the surface level. An operation block-diagram of the instrument in the STM Constant Height Mode is shown in (Fig. 4-45). 1-53

54 Fig Operation block-diagram of the instrument in the STM Constant Height Mode

55 Chapter 4. Configuring of the SPM Controller To configure the SPM Controller to operate in this mode, set Constant Height in the Mode menu as shown in Fig Fig Once the scanning procedure is performed, an image of the surface topography, Height, is visualized in the graphics image windows. 1-55

56 Part 1. SPM Controller (models BL022MTM, BL022MRM) 5. Basic Safety Measures Do not disassemble the controller. Disassembling of the controller is permitted only to persons certified by NT-MDT. Do not connect additional devices to the controller without prior advice from an authorized person from NT-MDT. This instrument contains precision electro-mechanical parts. Therefore protect it from mechanical shocks. Protect the controller against the influence of extreme temperature and moisture. For transport, provide proper packaging for the controller so as to avoid its damage. Before operation, set the power switch of the SPM controller to the position corresponding to value of the local electrical power line (this is only done with the controller being off!). Switch the SPM controller off before connecting/disconnecting its cable connectors. Disconnecting or connecting the cable connectors during operations may cause damage to the electronic circuit and disable the instrument. A warning label is attached to the SPM controller of the instrument (Fig. 5-1). Fig

57 Chapter 6. Operating Conditions 6. Operating Conditions environment temperature: temperature drift less than 20 ±5 C; 1 C per hour; relative humidity less than 80%; atmospheric pressure 760 ±30 mm Hg; electric mains with 110/220 V (+10%/-15%), 50/60 Hz and grounding; the room should be protected from mechanical vibrations and acoustic noises, either internal or external; the controller should be protected from the direct sun radiation impact. 1-57

58 Part 1. SPM Controller (models BL022MTM, BL022MRM) 7. Storage and Transport Instructions Storage Instructions The instruments should be stored packaged in clean and dry premises with low ambient temperature variations: Acceptable temperature inside the premises is plus (20 ± 10) C; Acceptable humidity inside the premises is < 80 %. Transport Instructions The instrument should be carefully packaged to avoid damage during transport. 1-58

59 Fig Overall block-diagram of the controller Appendixes 1. Overall Block-diagram of the SPM Controller

60 Part 1. SPM Controller (models BL022MTM, BL022MRM) 2. Reference Table of Main Signals Signal name Description of the signal Reference to the text pages SM_A SM_B SM_C Driving signal of the approach system stepper motor. Driving signal of the approach system stepper motor. Driving signal of the approach system stepper motor. SM_D Driving signal of the approach system stepper motor. Sample Bias voltage. Page 1-25 Sensors in I2C input ExtM Input signals of the X, Y, Z sensors. I2C bus input. Output of the programmable generator. Set by the user. X+ X- electrode of the scanner (opposite phase to X-). X- X-electrode of the scanner. Y+ Y- electrode of the scanner (opposite phase to Y-). Y- Y-electrode of the scanner. Z+ Z- electrode of the scanner (opposite phase to Z-). Page 1-35 Z- Z-electrode of the scanner. Page 1-18 Probe Voltage applied to the piezo drive of the probe sensor holder. Is used in modulation techniques to actuate oscillations of the probe. Digital input Cer- Cer+ MAG MAG*SIN MAG*COS FPGA digital input. Output of a programmable generator. Is used to actuate oscillations of the probe in modulation techniques. Inversion of signal Cer-. Electrical current signal from the Lock-in amplifier proportional to the probe oscillation amplitude. Signal of a projection of the probe oscillation amplitude. Signal of a projection of the probe oscillation amplitude. Page 1-33 Page 1-33 Page

61 Chapter 2. Reference Table of Main Signals RMS The value of the Root Mean Square deviation of the signal applied to the RMS detector. This signal is similar to MAG but, unlike MAG, it does not depend on frequency. Page 1-33 Z(Height) Signal whose value is derived analytically from the value of voltage applied to the Z tube of the piezo scanner. PHASE Calibrated signal of the phase shift between the reference signal fed to the piezo drive of the probe sensor holder and the Lock-in amplifier output signal. Page 1-42 LASER Electrical current signal of the four-section photodiode proportional to the integrated intensity of the laser beam acquired by the photodiode. Page 1-13 LF Electrical current signal proportional to the torsion deflection of the probe. Page 1-13 DFL Electrical current signal proportional to the probe deflection in the vertical direction. Page 1-13 Ipr_low Electrical current between the probe and sample. Page 1-53 Ipr_loq T0 Signal derived from Ipr low using a logarithm converter. Calibrated signal containing information on temperature of thermostages. This signal is used with the thermostage that can warm samples up to C. Page 1-53 T1 Calibrated signal containing information on temperature of thermostages. This signal is used with the thermostage that can warm samples up to C. A-C Difference between the corresponding diagonal sections of the four-section photodiode. Page 1-12 B-D Difference between the corresponding diagonal sections of the four-section photodiode. Page 1-12 Ext1 Ext2 Ext3 Signal from an external output. Signal from an external output. Signal from an external output. 1-61

62 Part 1. SPM Controller (models BL022MTM, BL022MRM) CTM T1 T2 Sum Sensors out I2C output Digital output Sw_Rtn Output from the current-to-voltage converter of the STM head. First external temperature sensor cathode of a silicon diode. Second external temperature sensor cathode of a silicon diode. Input of the amplifier of the signal LASER. Full exposure of the photodiode is required. Output signals of the X, Y, Z sensors. I2C bus output. FPGA digital output. Reverse ground of switches of the approach system stepper motor. 1-62

63 Chapter 3. Connector Diagrams of the Controller Breakout Connections 3. Connector Diagrams of the Controller Breakout Connections 3.1. Connector Diagram of the HEAD Breakout Connection (50-pin D-Type Plug) Pin number Signal Description 1 Las_-5 Isolated minus of the laser power supply. It is -5 V relative to ground of the laser (see pin 18 "Las_Com"). 2 Agnd Analog ground, connected to the case. 3 Agnd Analog ground, connected to the case Minus of the main power source. 5 AFM_Ref Return ground for signals A-C, B-D, Sum, STM (pin 35). 6 Agnd Analog ground, connected to the case. 7 STM Input for the current-to-voltage converter of the STM head. Non-inverted input of the differential amplifier. 8 STM_Ref Differential amplifier input. The resulting STM signal is the difference (STM - STM_Ref). Usually connected to Agnd of the STM-head. Can be used as a differential input in the range V. 9 +Amp Switched output for CMOS Switch tip voltage/ground. Usually connected to the current-to-voltage converter in the STM head. 10 AFM_Id AD Converter input. Linked with -15 V through a 10- kohm resistor inside the module. It is used to identify AFM heads. The resistor is engaged between "AFM_Id" and ground of the head. 1-63

64 Part 1. SPM Controller (models BL022MTM, BL022MRM) 11 Agnd Analog ground, connected to the case. 12 Ext1 Non-inverting input-1. Selected by the user. Has similar functionality as the Normal Force input. See pin Ext3 Inverting input of the differential amplifier. Linked with non-inverting input-3. This signal is the difference (Ext3 - Ext3_Ref). Can be employed as a differential input in the range V. See pin N.C. Not in use. Should be left open. 15 Res_Gnd Signal ground of the additional DAC. See pin Cer_Rtn Return ground for Cer- and Cer+. Connected with the output amplifiers power sources through two bypass 1 uf capacitors, and with the analog ground through a 16-Ohm resistor. 17 Cer_Rtn See pin Las_Com «Ground» of the laser power supply. Connected to the case through a 10-kOhm resistor. 19 Agnd Analog ground, connected to the case Plus of the main power supply. Is applied to internal circuits of AFM/STM heads. 21 B-D Input of the Normal Force and Lateral Force amplifiers. The difference between the corresponding diagonal sections of the AFM head four-section photodiode. 22 Agnd Analog ground, connected to the case Minus of the main power supply. Is applied to internal circuits of AFM/STM heads. 24 Agnd Analog ground, connected to the case. 25 Bias Bias voltage. See pin Agnd Analog ground, connected to the case. 27 Agnd Analog ground, connected to the case. 28 Ext1_Ref Inverting input of the differential amplifier. Linked with non-inverting input-1. This signal is the difference (Ext1 Ext1_Ref). Can be employed as a differential input in the range V. See pin Ext2_Ref Inverting input of the differential amplifier. Linked with non-inverting input-2. This signal is the difference (Ext2 Ext2_Ref). Can be employed as a differential input in the range V. See pin

65 Chapter 3. Connector Diagrams of the Controller Breakout Connections 30 Ext3 Non-inverting input 2. Selected by the user. See pin N.C. Not in use. Should be left open. 32 Res Output of the additional DAC. Range: 5 +5 V. See pin Cer_Rtn See pins 16, Las_Com See pin Sum Input of the signal LASER amplifier. See pin A-C Difference between the corresponding diagonal sections of the AFM head four-section photodiode. 37 Agnd Analog ground, connected to the case. 38 Agnd Analog ground, connected to the case Plus of the main power supply. Is applied to internal circuits of AFM/STM heads. 40 Agnd Analog ground, connected to the case. 41 Agnd Analog ground, connected to the case. 42 Agnd Analog ground, connected to the case. 43 STM_Id AD Converter input. Linked with -15 V through a 10- kohm resistor inside the module. Usually this resistor links STM_Id with the analog ground of the measuring head case. 44 Sample Bias voltage. Outside input Lit (see pin 23 in Connector diagram of the EXTENSION additional breakout connection ) / Ground / - switching output to the sample. Usually has direct access to the sample. See pin 12 in Connector diagram of the SCANNER breakout connection. 45 Agnd Analog ground, connected to the case. 46 Ext2 Non-inverting input 2. Selected by the user. See pin N.C. Not in use. Should be left open. 48 N.C. Not in use. Should be left open. 49 Cer- Output of a programmable generator. Is used to actuate oscillations of the probe in modulation techniques. 50 Cer+ Inversion of «Cer-». 1-65

66 Part 1. SPM Controller (models BL022MTM, BL022MRM) 3.2. Connector Diagram of the SCANNER Breakout Connection (37-pin D-Type Plug) Pin number Signal Description 1 Y- Y- electrode of the scanner, ±150 V. 2 Y+ Y- electrode of the scanner, ±150 V (opposite phase to 1). 3 X- X- electrode of the scanner, ±150 V. 4 X+ X- electrode of the scanner, ±150 V (opposite phase to 3). 5 Z- Z - electrode of the scanner, ±150 V. 6 Z+ Z - electrode of the scanner, ±150 V (opposite phase to 5). 7 Sw_Rtn Return ground of the switches of the stepper motor. AD Converter input. Connection with the analog ground through a 1-kOhm resistor. 8 Sw_Bot Power source of the bottom of switch of the stepper motor. Connected with +15 V through a 20-kOhm resistor. 9 SM_B Stepper motor coil. 10 SM_D Stepper motor coil. 11 Piezo_Id AD Converter input. Linked with -15 V through a 10-kOhm resistor inside the module. It is used to identify scanners. Can be employed as an additional power source of V. See pin 10 and pin 43 in section Connector diagram of the HEAD breakout connection. 12 Sample Switching output to the sample: Bias voltage / Outside input Lit / Ground. Directly connected to the sample. See item 44 in Connector diagram of the HEAD breakout connection. Item 23 in Connector diagram of the EXTENSION additional breakout connection. 13 N.C. Not in use. Should be left open. 14 N.C. Not in use. Should be left open. 15 N.C. Not in use. Should be left open. 1-66

67 Chapter 3. Connector Diagrams of the Controller Breakout Connections 16 N.C.t Not in use. Should be left open. 17 N.C. Not in use. Should be left open. 18 N.C. Not in use. Should be left open. 19 N.C. Not in use. Should be left open. 20 Agnd Analog ground, connected to the case. 21 Agnd Analog ground, connected to the case. 22 Agnd Analog ground, connected to the case. 23 Agnd Analog ground, connected to the case. 24 Agnd Analog ground, connected to the case. 25 Agnd Analog ground, connected to the case. 26 Sw_Top Power source of the top of switch of the stepper motor. Connected with -15 V through a 10-kOhm resistor. 27 SM_A Stepper motor coil. 28 SM_C Stepper motor coil. 29 Id_Rtn Return ground for scanner identification (pin 11). 30 Agnd Analog ground, connected to the case. 31 Agnd Analog ground, connected to the case. 32 N.C. Not in use. Should be left open. 33 N.C. Not in use. Should be left open. 34 N.C. Not in use. Should be left open. 35 N.C. Not in use. Should be left open. 36 N.C. Not in use. Should be left open. 37 N.C. Not in use. Should be left open. 1-67

68 Part 1. SPM Controller (models BL022MTM, BL022MRM) 3.3. Connector Diagram of the CONTROLLER2 Breakout Connection (62-pin D-Type Plug) Pin number Signal Description 1 Y+ Y- electrode of the scanner, ±150 V. 2 X+ X- electrode of the scanner, ±150 V. 3 Z+ Z- electrode of the scanner, ±150 V. 4 N.C. Not in use. Should be left open. 5 Sw_Rtn Return ground of the switches of the stepper motor. AD Converter input. Connection with the analog ground through a 1-kOhm resistor. 6-5C Minus of the capacitance sensors power supply. 7 SM_C Stepper motor coil. 8 SM_D Stepper motor coil. 9 ExtM Output of the programmable generator. Set by the user. 10 N.C. Not in use. Should be left open. 11 N.C. Not in use. Should be left open. 12 GND Analog ground, connected to the case. 13 N.C. Not in use. Should be left open. 14 N.C. Not in use. Should be left open V Plus of the main power supply. Is applied to internal circuits of AFM/STM heads. 1-68

69 Chapter 3. Connector Diagrams of the Controller Breakout Connections 16 GND Analog ground. 17 SCOX Actuation for the X sensor. 18 GND Analog ground. 19 RCOX Actuation for the X sensor reference capacitor. 20 GND Analog ground. 21 PAOX X-sensor preamplifier input. 22 GND Analog ground. 23 GND Analog ground. 24 GND Analog ground. 25 GND Analog ground. 26 GND Analog ground C Minus of the capacitance sensors power supply. 28 SM_A Stepper motor coil. 29 SM_B Stepper motor coil. 30 GND Analog ground. 31 GND Analog ground. 32 N.C. Not in use. Should be left open. 33 N.C. Not in use. Should be left open V Power source, +5 B 35 GND Analog ground. 36 GND Analog ground. 37 GND Analog ground. 38 SCOY Actuation for the Y sensor. 39 GND Analog ground. 40 RCOY Actuation for the Y sensor reference capacitor. 41 GND Analog ground. 42 PAOY Y-sensor preamplifier input. 43 Y- Y- electrode of the scanner, ±150 V. 44 X- X- electrode of the scanner, ±150 V. 45 Z- Z- electrode of the scanner, ±150 V 46 N.C. Not in use. Should be left open. 47 D0 Digital bus (input-output). 1-69

70 Part 1. SPM Controller (models BL022MTM, BL022MRM) 48 D1 Digital bus (input-output). 49 D2 Digital bus (input-output). 50 D3 Digital bus (input-output). 51 D4 Digital bus (input-output). 52 D5 Digital bus (input-output). 53 PROG Coding signal of I2C devices. 54 DATA I2C bus data signal. 55 CLK I2C bus clock signal V Minus of the main power supply. Usually, is applied to internal circuits of AFM/STM heads. 57 GND Analog ground. 58 SCOZ Actuation for the Z sensor. 59 GND Analog ground. 60 RCOZ Actuation for the Z sensor reference capacitor. 61 GND Analog ground. 62 PAOZ Z-sensor preamplifier input. 1-70

71 Chapter 3. Connector Diagrams of the Controller Breakout Connections 3.4. Connector Diagram of the EXTENSION Additional Breakout Connection (50-pin D-Type Plug) Pin number Signal Description 1 LDO+ Digital output of the serial port. Values of output voltage, load impedance, time ratios of the front and rear edges are in accordance with EIA RS-485 standard. Follows the data flows DO+, DO- (pins 3 and 20) timed by ClkO+ and ClkO- (pins 2 and 19). High pulse level enables data updating. 2 ClkO+ Non-inverting digital output of the serial port. Serial data are stored in an external shift register on every rising edge of ClkO. Electrical parameters, see pin 1. 3 DO+ Serial port non-inverting output. Electrical parameters, see pin 1. 4 SinO- Inverting output of the lock-in amplifier generator. 5 ExtM Output of the programmable generator. Set by the user. See pin22. 6 LitS Software controlled Clock pulse for the Lithography mode. TTL compatible. Set by the user. 7 Agnd Analog ground, connected to the case. 8 Agnd Analog ground, connected to the case. 9 Osc Buffered output. Allocated for direct access to a set of internal test points by means of a software-controlled C-MOS multiplexer. Duplicates the BNC connector on the rear panel. 10 Res -5 V +5 V unbuffered output of the reserve DAC. See pin 32 in Connector diagram of the HEAD breakout connection. 1-71

72 Part 1. SPM Controller (models BL022MTM, BL022MRM) 11 Ext1 Non-inverting input 1. Selected by the user. See pin Ext2 Non-inverting input 2. Selected by the user. See pin Agnd Analog ground, connected to the case. 14 Agnd Analog ground, connected to the case. 15 N.C. Not in use. Should be left open. 16 N.C. Not in use. Should be left open. 17 N.C. Not in use. Should be left open. 18 LDO- Digital inverting output of the serial port. Follows the data streams DO+, DO- (pins 3, 20) operated by clocks ClkO+, ClkO- (pins 2, 19). Clear information by high voltage level. Electrical parameters, see pin1. 19 ClkO- Inverting digital output of the serial port. Serial data are stored in an external shift register on every rising edge of ClkO. Electrical parameters, see pin DO- Serial port inverting output. Electrical parameters, see pin SinO+ Non-inverting output of the lock-in amplifier generator. 22 ExtM_Ref Return ground of the programmable generator. It is linked with the output generators power supplies through two 1 uf bypass capacitors. See pin Lit Connected to Sample by programming means Minus of the main power supply, -15 V. 25 Agnd Analog ground, connected to the case. 26 Res_Gnd Direct connection to the return ground of the reserve DAC. Can serve as a base point for "Res" (pin 10). See item 15 in Connector diagram of the HEAD breakout connection. 27 N.C. Not in use. Should be left open. 28 Ext2_Ref Inverting input of the differential amplifier. Linked with non-inverting input-2. This signal is the difference (Ext2 Ext2_Ref). Can be employed as a differential input in the range V. See pin Ext3_Ref Inverting input of the differential amplifier. Linked with non-inverting input-3. This signal is the difference (Ext3 Ext3_Ref). Can be employed as a differential input in the range V. See pin 45.I 30 Agnd Analog ground, connected to the case. 31 N.C. Not in use. Should be left open. 32 N.C. Not in use. Should be left open. 33 N.C. Not in use. Should be left open. 1-72

73 Chapter 3. Connector Diagrams of the Controller Breakout Connections 34 Agnd Analog ground, connected to the case. 35 Agnd Analog ground, connected to the case. 36 Agnd Analog ground, connected to the case. 37 Agnd Analog ground, connected to the case. 38 Agnd Analog ground, connected to the case. 39 Agnd Analog ground, connected to the case Power source, +5 V Main power source, +15V. 42 Osc_Ret Return ground for "Osc" (pin 9). Connected to the case. 43 N.C. Not in use. Should be left open. 44 Ext1_Ref Inverting input of the differential amplifier. Linked with non-inverting input-1. This signal is the difference (Ext1 Ext1_Ref). Can be employed as a differential input in the range V. See pin 11.I 45 Ext3 Non-inverting input 3. Selected by the user. See pin N.C. Not in use. Should be left open. 47 N.C. Not in use. Should be left open. 48 N.C. Not in use. Should be left open. 49 N.C. Not in use. Should be left open. 50 N.C. Not in use. Should be left open. 1-73

74 Part 1. SPM Controller (models BL022MTM, BL022MRM) 4. Connecting Eexternal Devices (Connector EXTENSION) Ex1 outside input: can be used for measurements by means of the internal oscilloscope and for reading signals during scanning. It can also be used as input for a lock-in amplifier and RMS detector. Ex2 outside input: can be used for measurements by means of the internal oscilloscope and for reading signals during scanning. Ex3 outside input: can be used for measurements by means of the internal oscilloscope and for reading signals during scanning. Ex4 Ex5 outside input for additional voltage from 10 V to +10 V applied to the sample. outside input for voltage from 100 V to +100 V applied to the sample. Ex6 outside output of the generator. Load: R > 2 kohm, C < 100 pf, gain 0 2 V. Ex7 output: DC voltage from the internal DA Converter, from 5 V to +5 V. Ex8 output: synchronization pulses for operation in the Lithography mode with Ex5. ATTENTION! It is strongly advised not to connect external devices that have not been supplied or authorized to use by NT-MDT. 1-74

75 Chapter 5. Testing the SPM Controller 5. Testing the SPM Controller A special SPM Controller tester is supplied with the instruments. This device serves to check the operation functions of the SPM Controller and detect possible malfunctions. The tester has (i) two connectors, 50- and 37-pin, linked with a cable (Fig. 5-1) and (ii) a 62-pin connector (Fig. 5-2). Fig. 5-1 Fig. 5-2 The tester is plugged into the external terminals of the SPM Controller instead of the instrument and emulates its operations. Special software functions drive the tester and read main signals. If the SPM Controller is malfunctioning, follow the procedure described below. SPM Controller test procedure To test the SPM Controller perform the following steps: 1. Turn the SPM Controller off. 2. Disconnect all cables of the instrument from the SPM Controller. 3. Plug in the tester to the SPM Controller connectors as described below: 50-pin connector to HEAD, 37-pin connector to either of SCANNER connectors, 62-pin connector to CONTROLLER2. 4. Launch the program Nova. 5. Turn the SPM Controller on. The indicator Device ON comes on and then off on the computer monitor after its initialization. 6. Start the test procedure. Perform the following program menu sequence:nova PowerScriptScriptsP8_tst (Fig. 5-3). 1-75

76 Part 1. SPM Controller (models BL022MTM, BL022MRM) Fig. 5-3 After the procedure is finished, its results are saved and stored in a disk file tst.tst (by default) in the Nova folder. This file can be read with any text editor. A typical example of this file is given below. Forward this file to the NT-MDT Service Department for further analysis. An example of the file with SPM Controller test results Modification 8 SerialNumber 817 EX1=laser supply EX2 and EX3 and LASER and BV NF and BV LF and BV Iprobe and resdac * X HV X HV Y HV Y HV Z HV Z HV X HV * Y HV Z HV X SENSOR Y SENSOR X SENSOR Digital inout ok PROBE~1V MAG*1 GAIN= PROBE~1V RMS* PH * PH PROBE~0.1V MAG*10 GAIN= BV~1V MAG*1 GAIN= Scale = 1, Offset =