Scanning probe microscope system and method of operating same - Patents.com

Abstract

This document relates to a scanning probe microscope system comprising a sample support structure, a sensor head including a probe, a deflection sensor unit, and an actuator including a Z-motion actuator and a scanning actuator. The system further comprises a control unit capable of receiving the deflection sensor signals and controlling the actuator. The control unit comprises a number of signal processing units, each of which is capable of receiving the deflection signals, providing a processed signal, and cooperating with a trigger unit which compares the processed signals with predefined trigger conditions and generates a trigger when the conditions are met.

Description

[Technical Field]

[0001] The present invention provides 1. A scanning probe microscope system, comprising: a sample support structure for supporting a sample including a sample surface, a cantilever, and a probe disposed on the cantilever; probe tip a sensor head including a probe having the above-mentioned, and the probe during scanning. Tips a deflection sensor unit for acquiring a deflection sensor signal indicative of the deflection of the probe in a direction perpendicular to the sample surface; Tips and a Z-motion actuator for moving the probe laterally / parallel to the substrate surface. Tips and one or more actuators including a scanning actuator for moving the And, The system receives the deflection sensor signal from the deflection sensor unit. and a control unit configured to control the one or more actuators. attitude R The above The present invention further relates to a scanning probe microscope system. Operation Regarding the method. [Background technology]

[0002] Topographic imaging of 3D samples with specific structures, particularly those characterized by narrow-to-high aspect ratios common in the semiconductor or biomedical industries, using scanning probe microscope (SPM) systems (e.g., atomic force microscopes (AFMs)) requires the use of nonresonant vibrational imaging methods. Existing methods, while differing in implementation, typically share several common features. This involves moving the probe or sample in a repetitive motion profile perpendicular to the surface (Z direction), extracting the topography of each pixel in the image when the probe-sample interaction force reaches a predefined value. During the motion profile, these features include retracting the probe from the surface and translating the probe relative to the surface in a plane parallel to the surface (XY).

[0003] Therefore, conventional nonresonant vibration imaging modes typically suffer from a number of drawbacks. For example, topographic height data is extracted based on a predefined value of the probe-sample interaction force, but the shape and nature of surface features, as well as the height differences within and between surface features, can vary significantly. Even using a predefined probe-sample interaction force, not all features can be correctly imaged. This issue may be partially resolved by performing a second scan of the substrate surface with a different predefined probe-sample interaction force. However, this leads to reduced throughput and further wear on the probe. Furthermore, drift in the probe position relative to the sample surface (e.g., due to temperature differences or vibration) can adversely affect accuracy and even prevent or obscure imaging.

[0004] Another drawback is that in conventional non-resonant vibration imaging modes, retraction of the probe from the surface is typically performed using a fixed, user-defined retraction distance. In some cases, this predefined retraction distance may not be sufficient to completely remove the probe from the surface, which can lead to damage to the probe and / or the sample surface when moving the probe to the next pixel. In other cases, this predefined retraction distance may be too large, making the pixel-by-pixel procedure unnecessarily slow, again resulting in reduced throughput.

[0005] Furthermore, when the probe attempts to leave the surface, the surface forces slightly delay the departure, thereby biasing the probe. Tips When the probe is released, it vibrates at its natural frequency. This vibration, also known as ringing, must be minimized before measuring the next pixel, requiring a certain settling time before measuring the next pixel. This settling time is also usually preset in the system. Therefore, if the settling time is too short, the probe will still be ringing, and the vibration of the probe will affect the quality of the image. If the settling time is too long, this will also have a negative impact on measurement throughput.

[0006] In industrial applications, the throughput of an SPM system is crucial. This directly impacts the throughput of, for example, semiconductor manufacturing. However, this is not the only application where throughput plays an important role. For example, the use of SPMs to inspect large numbers of, for example, biological samples would also benefit from increased throughput. Similarly, the quality and precision of the imaging are crucial to achieving the required quality levels. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is an object of the present invention to provide an SPM system and method that overcomes the above-mentioned drawbacks and is capable of achieving high throughput with excellent quality and accuracy. [Means for solving the problem]

[0008] For this purpose, the above-mentioned system is provided, in which the control unit comprises a plurality of signal processing units. Tei Each of the plurality of signal processing units receives the deflection sensor signal provided by the deflection sensor unit. and the plurality of configured to provide a processed signal Tei Each of the signal processing units is configured to cooperate with an associated trigger unit. Tei , the trigger unit individual configured to compare the processed signal of the processing unit with predetermined trigger conditions and generate a trigger signal when the trigger conditions are met; attitude do.

[0009] In the system of the present invention, by employing multiple signal processing units, each associated with a trigger unit, it is possible to examine the deflection sensor signal in real time upon the occurrence of multiple different conditions. The occurrence of such conditions is signaled by the trigger unit generating a trigger signal, thus enabling more sophisticated control of one or more actuators of the system. This can be used in multiple different ways to improve throughput or accuracy or to prevent damage to the probe or sample. For example, if carefully selected force thresholds are monitored in this manner, it is not necessary to perform multiple passes to properly image different depths and shapes of surface features, resulting in fewer probe changes.

[0010] In some embodiments, each of the signal processing units is exclusively associated with a trigger unit, and the number of processing units associated with the number of trigger units is equal, thereby allowing each processed signal to be tested against its uniquely associated trigger condition. In other or further embodiments, one or more signal processing units are associated with multiple trigger units. For example, if a processed signal is indicative of a particular physical parameter of the deflection signal and that physical parameter is tested against multiple conditions, the processed signal from the corresponding signal processing unit may be provided directly to multiple trigger units to reduce the processing power required and increase processing speed.

[0011] The control unit of the present invention may be a single integrated circuit or a system of multiple integrated circuits, e.g., an electronic circuit including one or more integrated circuits. The control unit may also be embodied as multiple logic circuits, e.g., digital components combined with analog circuit elements. Each of the various described functions may be embodied as a dedicated element of one or more electronic circuits. Furthermore, it will be understood that many of the described functions, e.g., a processing function or a comparison function for performing a trigger, may be embodied in computer instructions that, when loaded into memory onboard a scanning probe microscope (SPM) system (or a data repository remotely accessible by the SPM system), enable a controller circuit, central processing unit (CPU), or other circuit to perform the desired function. Such instructions may, for example, include an algorithm or allow an operator to provide such an algorithm to the SPM system. Those skilled in the art will recognize possible ways to implement the above in light of the description provided herein.

[0012] In some embodiments, one or more of the plurality of signal processing units processes the deflection sensor signal. 、 The probe Tips Shows static deflection of like The term "static deflection," as applied herein, is intended to refer to the non-oscillating deflection behavior of the probe. For example, a probe having a frequency lower than the first resonant frequency of the cantilever. Tips In other or further embodiments, one or more of the plurality of signal processing units processes the deflection sensor signal to 、 The probe Tips Shows the dynamic deflection of like The term "dynamic deflection," as applied herein, is intended to refer to high frequency oscillatory behavior of the system, for example, starting at, near, or above the first resonant frequency of the cantilever. TipsBoth types of behavior may be examined to allow the generation of trigger signals that can be applied to control particular aspects of the probe and / or sample movement in the system. Each actuator or aspect of movement may in principle be controlled in this way, as will be explained further below.

[0013] The actuator(s) may be comprised of a single actuator unit or multiple actuator units, without limiting the claimed invention in any way. For example, a system of multiple actuator units may be applied, each actuator responsible for driving one or more degrees of freedom of movement of one or more elements of the SPM system. These actuators may additionally include vibration actuators or acoustic actuators, for example for applying vibrations to the probe and / or sample. Furthermore, the actuators may include translational or rotational actuators in or about the X, Y, or Z directions of the system.

[0014] In some embodiments, each trigger unit comprises: individual the processed signal of the processing unit ofThe trigger conditions of two or more trigger units may be configured to compare the signal with different trigger conditions. This means that each trigger unit among all trigger units in the system applies a trigger condition that is different from the trigger conditions of the other trigger units, thereby making it unique within the system. While this feature is not required, it allows for validating the deflection sensor signal against multiple different criteria simultaneously. For example, the criteria may include processing the signal to obtain a measurement of the probe-sample interaction force and comparing it to multiple force thresholds. The deflection sensor signal may also be processed to measure the amplitude of a high-frequency signal, for example, around the natural frequency of the probe, and compared to thresholds to determine whether the probe has stopped vibrating after leaving the surface. Alternatively or additionally, some of the trigger conditions of two or more trigger units may be the same, with the advantage that this may be used to perform different actions in response to one and the same trigger. For example, one and the same trigger condition may be used in a combination of a low-pass filter and a high-pass filter to perform a first action if the sensed frequency is below a certain threshold and a second action (different from the first action) if the sensed frequency is above the certain threshold. There are other possible situations where one and the same trigger condition may result in multiple different actions depending on the situation.

[0015] In some embodiments, at least two of the trigger units are configured to generate a trigger signal for comparison of the processed signals. To, configured to evaluate the same physical parameters TeiThe trigger conditions for the physical parameters of the at least two trigger units are different from each other. Thus, for example, the processed signal may indicate a specific physical parameter (e.g., the amplitude of a dynamic deflection signal), and these trigger conditions compare the amplitude of this dynamic signal with a first threshold and a second threshold. The first threshold may, for example, trigger the detection of probe ringing upon contact release, while the second threshold indicates that the ringing has settled sufficiently to allow re-access to the surface (to acquire a new measurement result). Alternatively or additionally, to improve the quality of the measurement, the probe-sample interaction force can also be compared with different thresholds or other conditions. In a non-resonant vibration imaging mode, the probe is pressed against the surface and may slightly depress the surface in response to this force. By generating triggers at different force thresholds, the probe deflection signal can be recorded at particularly predefined values ​​of the applied probe-sample interaction force.

[0016] In some embodiments, the physical parameter is a probe Tips deflection of the probe Tips the force acting on the probe Tips the torsion of the deflection sensor signal, the amplitude of the deflection sensor signal, the frequency of the deflection signal, the phase of the deflection sensor signal. The invention is not limited to these parameters and multiple simultaneous processing of the deflection sensor signals may be performed to gain insight into other physical parameters not explicitly mentioned herein.

[0017] In some embodiments, each of the at least two trigger units comprises: the The deflection sensor signal is compared with a threshold value according to an associated trigger condition, and the threshold values ​​of the at least two trigger units are different from each other. The advantages of these embodiments have already been mentioned herein. For example, in a non-resonant vibration imaging mode, this is advantageous in order to be able to acquire deflection signals when various conditions regarding the probe-sample interaction force occur. TipsThe force acting on the probe is Tips The bending may be determined by examining the bending of the probe, which may be done by analyzing the deflection sensor signal. Tips occurs while the surface is being pressed down, but the surface is Tips If both parameters are of interest, they can be analyzed in the method of the present invention using a combination of a dedicated signal processing unit and a trigger unit.

[0018] In some embodiments, the control unit comprises a motion profile generator configured to generate motion signals for controlling the one or more actuators. Department The motion profile generation Department receives the trigger signal from the trigger unit and controls the one or more actuators in response to the trigger signal. Operation This allows direct control of the probe's motion in response to the generation of a trigger. For example, in a non-resonant vibration imaging mode, the settling time can be made to depend on the amplitude of the probe's high-frequency ringing motion, as described above. As another example, the acquisition and registration of a topography signal when the probe-sample interaction force reaches a specific value can be implemented in this way. Furthermore, by detecting the occurrence of the high-frequency ringing signal (e.g., by its amplitude or frequency content in the deflection sensor signal), the moment the probe leaves the surface can be detected, and a trigger can be generated to stop the retraction motion. In this way, the probe is not retracted more than necessary (optimized) to prevent damage to the surface, after which a parallel motion of the probe relative to the surface can be performed and moved to the next pixel. This optimization allows this parallel motion to be performed faster, thereby increasing the throughput of the system.

[0019] In some embodiments, the system further comprises a Z-displacement sensor configured to generate a Z-displacement sensor signal indicative of a Z-position of the probe in a direction perpendicular to the sample surface, and the system is configured to store current Z-position data in a data repository such as a memory or a database when at least one of the trigger units generates a trigger signal. The advantages of these embodiments have already been mentioned, but the acquisition and registration of Z-displacement signals when a particular value of the probe-sample interaction force is achieved may be implemented in this way.

[0020] In some embodiments, more than one of the signal processing units is connected to the probe. Tips Shows static deflection of like a low pass filter for providing the processed signal, and wherein the trigger units associated with the plurality of signal processing units each pass the processed signal to the probe Tips takes Force Threshold When the control unit receives a predetermined trigger signal from the trigger unit, the control unit controls the Z-motion actuator. Operation Let the probe Tips This allows different Force Threshold and get many values ​​in the desired Force Threshold The probe can be automatically retracted with

[0021] In some embodiments, at least one of the signal processing units is Tips and a lock-in amplifier configured to provide data on the amplitude of the vibrational motion of the probe, and the trigger unit associated with the at least one signal processing unit is configured to generate a trigger signal when the amplitude falls below an amplitude threshold level. In this embodiment, a ringing behavior of the probe after release is monitored. Once the ringing has sufficiently settled, the probe may resume movement towards the surface using a Z-displacement actuator.

[0022] As mentioned above, in some embodiments, the control unit, upon receiving the trigger signal of the trigger unit associated with the at least one signal processing unit, Tips Parallel to the surface, fart Move The scanning actuator is operated to the probe Tips begins to recede from said surface Activating the Z-motion actuator or the probe Tips to stop the retraction of the and actuating the Z-motion actuator to configured to perform at least one of attitude do.

[0023] The present invention is not limited with respect to the type of deflection sensor applied. In some embodiments, the deflection sensor unit comprises at least one of an optical beam deflection unit, a piezoelectric sensor unit, a piezoresistive sensor unit, or a capacitive deflection sensor unit. attitude In principle, any type of deflection sensor that is sufficiently accurate depending on the requirements of the SPM system may be used in conjunction with the present invention.

[0024] In a second aspect of the present invention, there is provided a sample comprising a sample surface. against scanning probe microscope method (scanning probe microscopy) of a scanning probe microscope system for performing Operation 1. A method, comprising: a system including a control unit, a cantilever, and a probe disposed on the cantilever. Tips a sensor head including a probe having the probe and a scanning Tips a deflection sensor unit for acquiring a deflection sensor signal indicative of a deflection of the probe in a direction perpendicular to the sample surface; Tips Z-motion actuator for moving and the probe to the substrate surface Tips and one or more actuators including a scanning actuator for moving the TeiThe method includes receiving, by the control unit, the deflection sensor signal from the deflection sensor unit; and controlling, by the control unit, the one or more actuators in response to the received deflection sensor signal, thing The deflection sensor signals are simultaneously processed by a plurality of signal processing units of the control unit to perform the hand Each of the plurality of signal processing units provides a processed signal, and each of the signal processing units cooperates with an associated trigger unit, whereby each trigger unit compares the processed signal with a predetermined trigger condition. thing and generates a trigger signal when the trigger condition is met. The above operation It is a method.

[0025] The present invention will be further clarified by describing several specific embodiments with reference to the accompanying drawings. The following detailed description provides examples of possible implementations of the invention, but should not be considered as describing all of the embodiments falling within the scope of the invention. The scope of the invention is defined in the claims, and the following description should be considered illustrative rather than limiting. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of a scanning probe microscope system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing two graphs of the Z position signal of the Z actuator and the measured deflection signal from the probe tip in accordance with an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating four probe deflection situations associated with particular positions in FIG. [Figure 4A] FIG. 4A is a schematic diagram of a scanning probe microscope system according to one embodiment of the present invention and associated deflection and Z position signals during operation. [Figure 4B]FIG. 4B is a schematic diagram of a scanning probe microscope system according to an embodiment of the present invention and associated deflection and Z position signals during operation. [Figure 5A] FIG. 5A is a schematic diagram of a scanning probe microscope system and Z position signals and associated probe deflections in accordance with one embodiment of the present invention. [Figure 5B] FIG. 5B is a schematic diagram of a scanning probe microscope system and Z position signals and associated probe deflections in accordance with an embodiment of the present invention. [Figure 6A] FIG. 6A is a schematic diagram of a scanning probe microscope system and Z position signals and associated probe deflections in accordance with an embodiment of the present invention. [Figure 6B] FIG. 6B is a schematic diagram of a scanning probe microscope system according to an embodiment of the present invention, illustrating Z position signals and associated probe deflections. DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 is a schematic diagram of a scanning probe microscope system 1 according to one embodiment of the present invention. Only a portion of the SPM system is shown in FIG. 1 to avoid obscuring other parts of the system that are less important to the present invention. FIG. 1 shows a schematic of a sample carrier 2 carrying a sample 5 having a sample surface 6. The sample carrier 2 includes an XY actuator 12 that can move the sample 5 relative to a probe 7 of the system 1 in a direction parallel to the carrier 2. The system 1 further includes a cantilever 8 and a probe Tips In use, for example to perform measurements of the topography of the sample 5, for example to determine the local height of the surface 6, the probe Tips 9 must be at least temporarily in contact with the surface 6. Tips When 9 is in contact with surface 6, Tips The deflection of 9 is generally Tips 9 is not in contact with the surface 6. Tips Vibrate 9 or probe Tips By periodically contacting the probe 9 with the surface 6, the amplitude of this periodic or oscillatory movement varies depending on the local height of the surface 6. Tips Measurements can be made by monitoring the deflection of the probe. Tips Deflection of 9 can be caused by deformation of cantilever 8. Probe 7 is attached to a Z-position actuator 10 which, in use, allows probe 7 to contact and retract from sample surface 6. Actuators 10 and 12 are Operation Generate motion profiles to control Department During the measurement, the probe is operated by a control unit 20 equipped with a Tips 9 does not move or moves only slightly in the X and Y directions relative to the sample surface 6. Therefore, the probe Tips To move the 9, use the probe Tips 9 is retracted from the surface by Z-position actuator 10, and XY actuator 12 is actuated to move probe 7 and sample 5 relative to one another to the next pixel. Z-position actuator 10 is then actuated again to extend probe 7 towards surface 6, and probe Tips 9 is brought into contact with the surface 6 .

[0028] The measurement is performed using an optical beam deflection unit comprising a laser 15 and an optical sensor 17. The optical sensor 17 is for example a four-quadrant optical sensor which determines the shift of the spot formed by the laser beams 16 and 16' on the surface of the sensor 17. Beam 16 is provided by the laser unit 15 and is reflected by the back surface of the probe 9 into a reflected beam 16'. The optical beam deflector unit uses the optical sensor 17 to provide a deflection sensor signal at its output which is provided to a control unit 20.

[0029] According to the present invention, the control unit 20 includes multiple signal processing units 22-1, 22-2, 22-i to 22-N. The number of signal processing units may be freely determined in the design as needed. Each of the signal processing units 22 is associated with a corresponding trigger unit 24. Processing unit 22-1 is associated with trigger unit 24-1, processing unit 22-2 is associated with trigger unit 24-2, and so on. It is not necessary for each processing unit 22 to be exclusively associated with one trigger unit. For example, in some embodiments, one processing unit 22 may be associated with multiple different trigger units 24. In other or further embodiments, multiple processing units 22 may be connected to one and the same trigger unit 24, depending on the application and design requirements. Furthermore, each trigger unit compares the output of the associated processing unit 22 with a condition 25. The trigger conditions 25-1 to 22-N can be preset by the operator of the SPM system 1. For example, each of the trigger conditions 25-1 to 25-N may be different, such that a different trigger condition may be matched by each of the triggers 24-1 to 24-N. Furthermore, trigger signals are provided at the output of the trigger unit 24-N, all of which are provided to the registration unit 35, which will be described later. Furthermore, each of the output signals of the trigger units 24-1 to 24-N may be used for the motion profile generation. Department 30. For this purpose, a selector unit 28-1 to 28-N is associated with each of the trigger units 24-1 to 24-N. It should be noted that the selector unit is not essential in the system. In the absence of the selectors 28-1 to 28-N, the trigger signal is not provided to the motion profile generator 30. DepartmentThe registration unit 35 may perform registration of the actuator positions of the actuators 10 and 12 upon receiving a trigger signal from any of the trigger units 24-1 to 24-N. Furthermore, the control unit 20 may also be configured to register the output signal 17 upon receiving a trigger signal via connection 33. The registered measurement data and actuator positions are stored in a memory 38 of the SPM system.

[0030] 2 is a graph showing a schematic of a probe deflection signal 51 and a Z-position actuator signal 41 in an SPM system during a non-resonant vibration imaging mode according to one embodiment. The bottom graph shows the Z-position actuator signal 41 driving the probe 7 to and from the surface 6 of the substrate 5. The horizontal axis represents time and the level of the axis 43 represents the probe deflection signal 51. Tips 9 corresponds to the Z level where the probe 7 just touches the surface 6. If the probe 7 is further extended in the negative Z direction towards the surface 6, the probe Tips 9. Therefore, at the Z level below axis 43, the probe Tips The probe-sample interaction force acts on the probe 9. Chip 9 4 shows a schematic of the deflection signal 51 of the probe 7 (and the probe Tips 9) further towards the surface 6. The vertical lines 45, 46, 47, 48, and 49 are characteristic time While the probe 7 extends towards the surface 6 of the sample 5, as indicated by the Z position signal 41, time At point 45, the probe Tips 9 first contacts the surface 6 of the sample. This is the point where signal 41 intersects axis 43. In the deflection signal 51, time During the initial phase A of the deflection signal 51 while the probe 7 is approaching the surface 6 prior to point 45, the probe Tips9 deflection is not measured. In FIG. 3, stage A is shown diagrammatically at 60, where the probe Tips The position of the probe 9 and probe 7 is shown in a relaxed state above the surface 6 .

[0031] Immediately after contact, at time point 45, the probe Tips 9 is briefly attracted to the surface as indicated by the dip in deflection signal 51. Z position signal 41 indicates that probe 7 is being extended further towards surface 6, increasing the probe-sample interaction force. This is illustrated by portion 44 of Z position signal 41 indicating a negative Z position. Extension of probe 7 towards surface 6 continues until the probe-sample interaction force reaches a threshold value at time 46. Thereafter, time 46 and time During 47, the probe 7 is retracted again, indicating an increase in the Z position signal 41. The Z position signal 41 is negative. time 45 and time The period between 47 corresponds to phase B of the deflection signal. Phase B is actually time a first portion corresponding to the portion before point 46 and before the deflection signal 51 reaches a maximum; time 2. The situation in stage B is shown diagrammatically by situation 61 in FIG. 3. As can be seen, the positive probe-sample interaction force causes the probe 9 to bend backward, thereby time Point 45 and time Between 47, the deflection signal 51 becomes positive.

[0032] time At point 47, the probe 7 is at a Z position corresponding to the level of the axis 43 where the probe-sample interaction force is zero. Tips 9 is further retracted from the surface 6 until it is released. time Before that, time 47 and time Between 48, the adhesion strength is measured by the probe Tips Attracts 9 and thereby probes Tips A negative force is applied to 9, and during the retraction of the probe, Tips9 maintains contact with the sample surface 6. This portion of the deflection signal is shown as phase C. In FIG. 3, phase C is shown as situation 62, where the surface 6 and the probe Tips 9. The adhesion force between the probe Tips At time 48, the adhesive force and the Z actuator are applied to the probe. Tips The probe 7 has retracted so far that the combined balance of the forces exerted on the probe 7 and the force exerted on the probe 7 can no longer be maintained. Tips 9 is released from the surface 6 and begins to vibrate at its natural frequency. This phase D of the deflection signal 51 is called ringing and is shown diagrammatically in Figure 3 by situation 63. The ringing continues until it gradually disappears and the probe is again in a relaxed state corresponding to phase A from time 49, after which the next extension towards the surface may commence. time Point 48 and time During the next approach to the surface after 49, the probe may move laterally relative to the sample 5 towards the next pixel in the image. This process is repeated until all pixels have been imaged.

[0033] The following description outlines many different embodiments and possibilities that can be realized with the present invention. The present invention is not limited to these embodiments. In principle, each signal processing unit 22 of the control unit 20 may perform any desired signal processing method to provide processed signals from which any desired signal parameters can be obtained. Additionally, the trigger unit 24 may verify any desired trigger condition 25 to control the imaging process of the SPM system. Some examples are shown in FIGS. 4-6 and described below. References to the deflection signal 51 and the Z-position signal 41 are repeated in FIGS. 4B, 5B, and 6B below FIGS. 4A, 5A, and 6A, respectively.

[0034] 4A and 4B illustrate an embodiment in which the control unit 20 is configured to analyze the probe-sample interaction force against multiple different threshold levels. The deflection sensor signal 51 is provided to the control unit 20 by the deflection sensor 17 and is received by multiple signal processing units 22-1, 22-2, . . . 22-N in the control unit 20. While the units 22-1, . . . 22-N are shown as separate units in FIG. 4A, it is possible in principle to combine the signal processing into a single processing unit 22 and multiple trigger units 24-1, . . . 24-N. In the trigger units 24-1, . . . 24-N, each trigger unit verifies whether its associated trigger condition 25 is satisfied. In the embodiment of FIG. 4A, the probe-sample interaction force is compared against multiple different thresholds th1, th2, . . . thN, provided by trigger conditions 25-1, . . . 25-N. A trigger is generated by each of the trigger units 24-1, . . . 24-N for each satisfied condition 25-1, . . . 25-N. As triggers are generated by each trigger unit 24-1 to 24-N, they are sent to a registration unit 35 which registers the current deflection signal 51, the Z position signal 41 and the XY position signal indicative of the pixel being imaged. This data is stored in the memory 38 of the SPM system. Furthermore, the control unit 20 controls the motion profile generation. Department 4A, this is shown schematically by selectors 28-1 to 28-N. A selector showing "0" indicates that the trigger signal is to be discarded. A selector 28-1 to 28-N showing "1" indicates that the respective trigger signal has been selected by control unit 20. In the embodiment shown in FIG. 4A, trigger signal 28-2 is used to generate a motion profile. Department 30. This is done by the trigger unit 24-2 verifying whether a trigger condition 25-2 indicating a threshold value th2 is met, and if so, this is used to generate a motion profile. Department 30 to start retracting the probe 7 from the surface 6 again.

[0035] In FIG. 4B, each trigger condition 25-1 through 25-N verified by each trigger unit 24-1 through 24-N is represented schematically by a level 25-1 through 25-N in graph 50. These trigger conditions 25-1 through 25-N are arbitrarily selected to facilitate explanation of the operating principle. In practice, they may be selected differently. For example, the level of trigger condition 25-1 may be selected lower than the level of trigger condition 25-2. Also, additional trigger conditions may be added, or some of trigger conditions 25-1 through 25-N may not exist. In the example shown in FIGS. 4A and 4B, level 25-2 is the threshold level verified to retract the probe 7 from the surface 6 again. As can be seen from signal 51, upon reaching level 25-2, the probe-sample interaction force decreases again, corresponding to an increase in the Z position signal 41 in graph 40 of FIG. 4B. While this increase appears to occur immediately in FIG. 4B, in reality, it may occur with some delay due to system delays such as the inertia of the Z scanner. Other levels 25-1 to 25-N may be matched to perform specific actions, such as controlling specific parts of the system or registering the deflection sensor signal 51, Z position signal 41 and XY actuator signals of the SPM. In the case of trigger condition 25-N, this condition is time It is filled at time 45, which corresponds to point 65. Figure 4A: Motion Profile Generation Department 4B, the control unit 30 is programmed to start retracting the probe 7 from the sample surface 6 again and, after a certain settling time, control the XY actuator 12 to move to the next pixel. In the embodiment of FIG. 4A, only the probe-sample interaction force is analyzed for multiple triggers 25. Optionally, there may be no settling time, in the sense that the probe may be moved while still ringing.

[0036] In a further embodiment shown in Figures 5A and 5B, one of the signal processing units 22 is configured to analyze a portion of the frequency spectrum of the deflection sensor signal 51. Here, the signal processing unit 22-N is embodied by a lock-in amplifier that provides at least a portion of the deflection signal 51 corresponding to a frequency band that includes the natural frequency of the probe 7. As a result, a trigger unit 24-N associated with the signal processing unit 22-N can determine whether a signal component of sufficient strength is present in this frequency band. Here, a trigger condition 25-N is checked against a threshold thN that indicates a sufficiently strong signal indicative of ringing of the probe 7. This trigger unit 24-N therefore generates a trigger signal at time 48 in Figure 5B upon the occurrence of a ringing signal at stage D of the deflection signal 51. The signal processing unit 22-2 and the trigger unit 24-2 cooperate to determine the maximum desired probe-sample interaction force. Force Threshold 1, in the example of FIG. 5, the output signals of the trigger units 24-1 to 24-N are generated in response to the motion profile generation. Department 30, which can be indicated by using selector units 28-1 to 28-N. Each of these selectors 28-1 to 28-N is associated with one of the trigger units 24-1 to 24-N. The trigger signals 24-N and 24-2 are used to generate the motion profile. Department Selectors 28-N and 28-2 are each set to "1" to indicate that these corresponding trigger signals are to be used by motion profile generator 30. Department 30. Therefore, time In 46, the Z position signal 41 time Point 71 and deflection sensor signal 51 time Point 66 is the point where probe 7 retracts from surface 6 again. time The time point 48 (i.e., the time of the deflection sensor signal 51) may be marked as time From point 68 onwards, the occurrence of ringing of the probe 7 can be detected by the trigger unit 24-N. At this point, the Z position signal is timeAt point 73, when a trigger signal is received from trigger unit 24-N, a motion profile is generated. Department 30 probes Tips 9 is away from the surface 6, signaling that the probe 7 is ringing. Therefore, the XY actuator 12 may be controlled to move to the next pixel, and after a settling time set by the control unit 20, the Z-position actuator 10 may be controlled to extend the probe 7 toward the surface 6 again. In the embodiment of FIGS. 5A and 5B, no trigger is generated when the ringing of the probe 7 settles. In principle, it is possible to check whether the probe 7 has settled by checking one of the lowest threshold levels of the deflection signal 51. This may be advantageously used in other or further embodiments of the present invention. Furthermore, as in FIGS. 4A and 4B, in the embodiment shown in FIG. 5A, upon receipt of each trigger from the trigger units 24-1 to 24-N, data from the actuator signal and the deflection sensor signal 51 are registered in memory 38 by the registration unit 35.

[0037] 6A and 6B show a further embodiment of an SPM system according to the present invention. Here, a lock-in amplifier 22-N is present as one of the signal processing units 22 and checks for the occurrence of ringing after time 48. In addition, a further lock-in amplifier 22-1 is associated with trigger unit 24-1 and checks for the settling of the ringing signal from probe 7. The embodiment of FIGS. 6A and 6B is similar in many respects to the embodiment of FIGS. 5A and 5B, at least with the exception of the additional lock-in amplifier 22-1. As mentioned above, although different lock-in amplifiers are shown, all of these may be implemented by a single lock-in amplifier combined with multiple trigger units. Selectors 28-1, 28-2 to 28-N (the dots between units 22-2 and 22-N indicate that any number of processing units can be optionally added) each select these trigger signals to be used in the motion profile generation by setting them to a value of "1" (or "true" or another corresponding Boolean value). Department6A may also be provided in the deflection sensor signal 51 at time 46 in accordance with trigger condition 25-2. Additional trigger units not specifically shown in FIG. 6A may generate triggers under any circumstances, for example, at time 45 for registering data in memory 38. In the embodiment of FIG. 6A, trigger unit 24-2 triggers the deflection sensor signal 51 at time 46 in accordance with trigger condition 25-2. time A trigger is generated when the probe-sample interaction force reaches a maximum at point 66. time Then, generate the motion profile. Department 30 retracts the probe 7 from the surface 6. The next trigger is generated by the lock-in amplifier 22-N in combination with the trigger unit 24-N. Tips 9 is generated when the probe 7 starts to ring after it is released from the sample surface 6. Motion profile generation Department 30 probes Tips 9 is now away from the sample surface 6 and may therefore be moved to the next pixel by control of the XY actuator 12. Furthermore, a further trigger signal is generated at time 49 when the natural frequency of the deflection sensor 51 falls below the threshold level indicated by condition 25-1. The trigger unit 24-1 then generates the trigger signal and sends it to the motion profile generator 28-1 via the selector 28-1. Department 30. Motion profile generation Department For 30, this marks the point where the ringing of probe 7 has stopped, and probe 7 can safely be extended towards surface 6 in the next pixel. Thus, after time 49 on graph 40 of FIG. 6B, Z position signal 41 decreases again, indicating that probe 7 is being extended towards surface 6. This begins the process of imaging the next pixel.

[0038] The present invention has been described with reference to specific embodiments thereof. It will be understood that the embodiments shown in the drawings and described herein are intended for illustrative purposes only and are not intended to limit the present invention in any manner or by any means. The operation and construction of the present invention will be apparent from the foregoing description and accompanying drawings. It will be apparent to those skilled in the art that the present invention is not limited to the embodiments described herein, but that modifications are possible as contemplated within the scope of the appended claims. Additionally, kinematic reversal is inherently disclosed and is considered within the scope of the present invention. Furthermore, any of the components and elements of the various disclosed embodiments may be combined or incorporated into other embodiments as deemed necessary, desirable, or preferred without departing from the scope of the present invention as defined in the claims.

[0039] In the claims, any reference signs should not be construed as limiting the claims. When a decrease or increase in a particular parameter is described, this should not be construed as limiting, since the reversed parameter is equally applicable. When a decrease in Z level is mentioned, it means that the probe is extending toward the surface, while an increase means that the probe is retracting from the surface. Of course, this depends on the definition of the positive Z direction, and may be reversed if a different definition is used. The terms "comprises" and "includes," as used in this description or the appended claims, should not be construed in an exclusive or exhaustive sense, but rather in an inclusive sense. Thus, the term "comprising," as used herein, does not exclude the presence of other elements or steps in addition to those recited in any claim. Furthermore, the words "a" and "an" should not be construed as limited to "one and only one." Instead, they are used to mean "at least one," not to exclude a plurality. Features not specifically or explicitly recited herein or in the claims may additionally be included in the structures of the present invention within the scope of the present invention. Phrases such as "means for" should be read as "a component configured for" or "a member configured to" and should be construed to include equivalents of the disclosed structures. The use of phrases such as "important," "preferred," and "particularly preferred" is not intended to limit the invention. In general, additions, deletions, and modifications may be made within the knowledge of one skilled in the art without departing from the spirit and scope of the invention, which is determined by the claims. The invention may be embodied in forms other than those specifically described herein, and the invention is limited only by the appended claims.

Claims

1. A scanning probe microscope system, comprising: a sample support structure for supporting a sample including a sample surface; a sensor head including a probe having a cantilever and a probe tip disposed on the cantilever; a deflection sensor unit for acquiring a deflection sensor signal indicative of a deflection of the probe tip of the probe during scanning; one or more actuators including a Z-motion actuator for moving the probe tip in a direction perpendicular to the sample surface and a scan actuator for moving the probe tip relative to the substrate surface; It is equipped with the system further comprising a control unit configured to receive the deflection sensor signal associated with the probe from the deflection sensor unit and to control the one or more actuators; the control unit comprises a plurality of signal processing units for simultaneously providing a plurality of processed signals; each of the plurality of signal processing units is configured to receive the deflection sensor signal provided by the deflection sensor unit and to provide at least one processed signal among the plurality of processed signals, and each of the signal processing units is configured to cooperate with an associated trigger unit, the trigger unit being configured to compare the processed signal of the respective processing unit with a predetermined trigger condition and to generate a trigger signal when the trigger condition is satisfied; Scanning probe microscope system.

2. The plurality of signal processing units include: at least one first signal processing unit for providing a first processed signal; at least one second signal processing unit for providing a second processed signal; Including, the first signal processing unit is associated with a first trigger unit configured to compare the first processed signal with a first trigger condition; and the second signal processing unit is associated with a second trigger unit configured to compare the second processed signal with a second trigger condition; 2. A scanning probe microscope system according to claim 1.

3. 2. The scanning probe microscope system of claim 1, wherein each of the signal processing units is exclusively associated with a trigger unit, and the number of trigger units and the number of associated processing units are equal.

4. one or more of the plurality of signal processing units configured to process the deflection sensor signal to provide the processed signal indicative of static deflection of the probe tip; and / or one or more of the plurality of signal processing units configured to process the deflection sensor signal to provide the processed signal indicative of dynamic deflection of the probe tip.

2. A scanning probe microscope system according to claim 1.

5. The scanning probe microscope system of claim 1 , wherein each trigger unit is configured to compare the processed signal of each processing unit with a different trigger condition.

6. at least two of the trigger units are configured to evaluate the same physical parameter for comparison of the processed signals; the trigger conditions regarding the physical parameters of the at least two trigger units are different from each other; 6. A scanning probe microscope system according to claim 1.

7. 7. The scanning probe microscope system of claim 6, wherein the physical parameter is at least one of the group including: deflection of the probe tip, force on the probe tip, twist of the probe tip, amplitude of the deflection sensor signal, frequency of the deflection sensor signal, and phase of the deflection sensor signal.

8. Each of the at least two trigger units compares the deflection sensor signal with a threshold value according to its associated trigger condition for evaluating the physical parameter, and the threshold values ​​of the at least two trigger units are different from each other.

7. A scanning probe microscope system according to claim 6.

9. the control unit further comprises a motion profile generator configured to generate motion signals for controlling the one or more actuators; the motion profile generator is configured to receive the trigger signal from the trigger unit and control the operation of the one or more actuators in response to the trigger signal.

2. A scanning probe microscope system according to claim 1.

10. the scanning probe microscope system further comprising a Z-displacement sensor configured to generate a Z-displacement sensor signal indicative of a Z position of the probe in a direction perpendicular to the sample surface; the system is configured to store current Z position data in a data repository, such as a memory or a database, when at least one of the trigger units generates a trigger signal.

2. A scanning probe microscope system according to claim 1.

11. at least one of the signal processing units comprises a low pass filter for providing the processed signal as indicative of static deflection of the probe tip; each of the trigger units having the at least one of the signal processing units compares the processed signal with a threshold force applied to the probe tip, and the control unit is configured to actuate the Z-motion actuator to initiate retraction of the probe tip from the sample surface upon receiving a predetermined trigger signal of the trigger unit.

2. A scanning probe microscope system according to claim 1.

12. at least one of the signal processing units comprises a lock-in amplifier configured at least to provide amplitude data of the vibrational motion of the probe tip; the trigger unit associated with the at least one signal processing unit is configured to generate a trigger signal when the amplitude falls below an amplitude threshold level.

2. A scanning probe microscope system according to claim 1.

13. 13. The scanning probe microscope system of claim 12, wherein the control unit is configured to, upon receiving the trigger signal of the trigger unit associated with the at least one signal processing unit, at least one of: actuating the scanning actuator to move the probe tip parallel to the surface to a next position; actuating the Z-motion actuator to start retraction of the probe tip from the surface; or actuating the Z-motion actuator to stop retraction of the probe tip from the surface.

14. The scanning probe microscope system of claim 1 , wherein the deflection sensor unit comprises at least one of a light beam deflection unit, a piezoelectric sensor unit, a piezoresistive sensor unit, or a capacitive deflection sensor unit.

15. 1. A method of operating a scanning probe microscope system for performing scanning probe microscopy on a sample including a sample surface, comprising: the system comprises a control unit, a sensor head including a probe with a cantilever and a probe tip disposed on the cantilever, a deflection sensor unit for acquiring a deflection sensor signal indicative of a deflection of the probe tip during scanning, and one or more actuators including a Z-motion actuator for moving the probe tip in a direction perpendicular to the sample surface and a scan actuator for moving the probe tip relative to the substrate surface; The method comprises: receiving, by the control unit, the deflection sensor signal associated with the probe from the deflection sensor unit; controlling, by the control unit, the one or more actuators in response to the received deflection sensor signal; Including, To perform the controlling, the deflection sensor signals are simultaneously processed by a plurality of signal processing units of the control unit, each of the plurality of signal processing units providing at least one processed signal of a plurality of processed signals; each of said signal processing units cooperates with an associated trigger unit, whereby each trigger unit performs a comparison of said at least one processed signal with a predetermined trigger condition and generates a trigger signal when said trigger condition is satisfied; The method of operation.

16. The simultaneous processing is processing the deflection sensor signal by one or more of the plurality of signal processing units to provide the processed signal indicative of static deflection of the probe tip; or processing, by one or more of the plurality of signal processing units, the deflection sensor signal to provide the processed signal indicative of dynamic deflection of the probe tip.

17. for at least two of the trigger units, the comparing includes evaluating the same physical parameter; the trigger conditions relating to the physical parameters are different from one another; 17. The method of claim 16.

18. 18. The method of claim 17, wherein the physical parameter is at least one of the group including: deflection of a probe tip, force on the probe tip, twist of the probe tip, or, if the deflection sensor signal is a dynamic signal, amplitude of the deflection sensor signal, frequency of the deflection sensor signal, or phase of the deflection sensor signal.

19. each of the at least two trigger units compares the deflection sensor signal with a threshold value according to its associated trigger condition for evaluating the physical parameter; 19. The method of claim 17 or 18, wherein the threshold values ​​of the at least two trigger units are different from each other.

20. the method further comprising generating an operation signal for controlling the one or more actuators, and receiving the generated trigger signal from the trigger unit for controlling actuation of the one or more actuators in response to the trigger signal.

16. The method of claim 15.

21. said processing said deflection signal includes low pass filtering to provide said processed signal as indicative of static deflection of said probe tip; the comparing includes comparing the processed signal to a threshold force on the probe tip; 16. The method of claim 15, wherein said controlling comprises activating the Z-motion actuator to initiate retraction of the probe tip from the sample surface upon receiving a predetermined trigger signal.

22. processing the deflection sensor signal includes providing data on the amplitude of the vibrational motion of the probe tip; 16. The method of claim 15, wherein the comparing comprises generating a trigger signal when the amplitude falls below an amplitude threshold level.

23. 23. The method of claim 22, wherein in response to receiving the trigger signal, the method includes at least one of moving the probe tip parallel to the surface to a next position, retracting the probe tip from the surface, or stopping retraction of the probe tip from the surface.

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