System for performing atomic force microscopy including a grid plate qualification tool

Abstract

A system for performing atomic force microscopy, the system comprising: an atomic force microscope tool configured to receive a plate including a coordinate reference pattern thereon for providing positional references to system elements of the atomic force microscope tool; and a device for qualifying the coordinate reference pattern in the atomic force microscope (AFM) tool, the device comprising a fixed reference frame, a pattern encoder for reading the coordinate reference pattern, a motion stage for moving the plate and the pattern encoder parallel to and relative to the plate, a displacement measurement system for measuring the displacement of the plate or the pattern encoder relative to the fixed reference frame, and a controller for controlling the motion stage, the pattern encoder, and the displacement measurement system. While controlling the motion stage, the controller is configured to control the pattern encoder to identify defects in the coordinate reference pattern. For each defect, the controller controls the displacement measurement system to identify a position of the defect and enable the displacement of the plate or the pattern encoder to be measured relative to the fixed reference frame. The controller is configured to store each defect in association with the determined position.

Description

[Technical field]

[0001] The present invention relates to a system for performing atomic force microscopy, the system comprising an atomic force microscopy tool configured to receive a plate including a coordinate reference pattern on the plate for providing positional references to system elements of the atomic force microscopy tool, the system further comprising a device for qualifying the coordinate reference pattern on the plate, the device being configured to receive the plate for performing a qualification inspection. [Background technology]

[0002] Various production and quality inspection systems require highly accurate positioning of production or inspection system elements relative to the products to be processed, examples of which are systems for manufacturing electronic, optical or optoelectronic products on the nanoscale.

[0003] Positioning systems operating at this scale, such as scanning probe microscopy (SPM), typically use encoders in combination with a flat 2D encoder plate, also known as a grid plate, to determine positional references for system elements during product processing. The resolution and quality of the grid plate therefore contributes significantly to the resolution and accuracy of the positioning system.

[0004] Depending on the patterning method, the grid plate pattern will have manufacturing imperfections that result in signal imperfections and limit the accuracy of the position signal obtained from the encoder. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, a means is needed that allows for improved accuracy. [Means for solving the problem]

[0006] In summary, an embodiment of the present invention relates to a system for performing atomic force microscopy, the system comprising an atomic force microscopy tool configured to receive a plate including a coordinate reference pattern on the plate for providing positional references to atomic force microscopy system elements, the system further comprising a device for qualifying the coordinate reference pattern on the plate, where the device is configured to receive the plate to perform a qualification test.

[0007] A device for qualifying the coordinate reference pattern on the plate for use in an atomic force microscope (AFM) tool includes a fixed reference frame, a pattern encoder, a motion stage, a displacement measurement system, and a controller. The pattern encoder is configured to read the coordinate reference pattern on the plate. The motion stage is configured to move the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate. The displacement measurement system is configured to measure displacement of the plate or the pattern encoder relative to the fixed reference frame, and the controller is configured to control the motion stage, the pattern encoder, and the displacement measurement system.

[0008] While controlling the motion stages, the controller is configured to control the pattern encoder to identify defects in the coordinate reference pattern. For each defect, the controller is configured to identify a location of the defect by controlling the displacement measurement system to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame. The controller is configured to store each defect in association with a location of the each defect.

[0009] An advantage of the device is that the position of each defect identified by the pattern encoder is measured by an independent measurement system, for example with a higher measurement resolution than the pattern encoder, preferably on a sub-micron scale, to qualify the coordinate reference pattern.

[0010] The invention also relates to a device for use in the system described above.

[0011] Another aspect of the invention relates to a data file for use in an atomic force microscope (AFM) tool generated by the device described above, the data file comprising an array of identified defects in at least a subset of a coordinate reference pattern on a plate, each identified defect being associated with a position of the identified defect relative to at least one reference position on the coordinate reference pattern.

[0012] As a result, the data file may include a correction map of the coordinate reference pattern that can be used to improve the accuracy of the coordinate reference pattern when implemented in an AFM tool.

[0013] Yet another aspect of the invention relates to a method for qualifying a coordinate reference pattern on a plate for use in an atomic force microscope (AFM) tool by a device. In a first step, the method includes moving the plate and a pattern encoder relative to each other in a direction parallel to a plane of the plate by a motion stage. In a further step, a pattern encoder configured to read the coordinate reference pattern on the plate identifies defects in the coordinate reference pattern. Then, a displacement measurement system configured to measure the displacement of the plate relative to a fixed reference frame locates a position of each defect. Finally, the method includes storing each defect in association with the position of each defect to create a pattern correction map.

[0014] The invention will be explained in more detail in the accompanying drawings. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 illustrates a first embodiment of a device 10 for qualifying a coordinate fiducial pattern on a plate for use in an atomic force microscope (AFM) tool. [Diagram 2] FIG. 2 provides a top view of an alternative or further embodiment of device 10. [Diagram 3] FIG. 3 illustrates a device 10 according to yet another or further embodiment. [Figure 4] FIG. 4 illustrates an exemplary embodiment of the device 10 . [Diagram 5] FIG. 5 illustrates a data file 20 generated by the device 10 for use in an atomic force microscope (AFM) tool. [Figure 6] FIG. 6 illustrates a schematic of a method 30 for device-qualifying coordinate fiducial patterns on a plate for use in an atomic force microscope (AFM) tool. [Figure 7] FIG. 7 illustrates a system for performing scanning probe microscopy according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Aspects of the invention relate to a device and method for qualifying a coordinate reference pattern on a plate for use in an Atomic Force Microscope (AFM) tool, and a data file generated by the device for use in an Atomic Force Microscope (AFM) tool, the device and method comprising a fixed reference frame and a pattern encoder configured to read the coordinate reference pattern on the plate, a motion stage configured to move the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate, a displacement measurement system configured to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame, and a controller configured to control the motion stage, the pattern encoder and the displacement measurement system.

[0017] While controlling the actuation stage, the controller is configured to control the pattern encoder to identify defects in the coordinate reference pattern. The controller is configured to identify for each defect a position of the defect by controlling the displacement measurement system to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame. The controller is configured to store each defect in association with the position of the defect. An advantage of the device is that the position of each defect identified by the pattern encoder is measured by an independent measurement system, e.g. with a higher measurement resolution than the pattern encoder, to qualify the coordinate reference pattern.

[0018] In a preferred embodiment of the device, the controller is configured to identify defects in at least a subset of the coordinate reference pattern to create a pattern correction map, which can be used, for example, to improve positioning accuracy of an AFM.

[0019] In another or further embodiment of the device, before controlling the pattern encoder to identify defects, the controller is configured to control the pattern encoder to identify at least one reference position in the coordinate reference pattern, and for each reference position, to identify the position of the reference position by controlling the displacement measurement system to measure the displacement of the plate relative to the fixed reference frame, and to store each reference position in association with the position of the each reference position to provide a map of identified reference positions on the coordinate reference pattern associated with the identified defects, which can be used, for example, by an AFM tool to quickly scan which coordinate reference pattern or plate is being used.

[0020] Additionally, for each defect, the controller may be configured to calculate a relative position of each defect relative to at least one reference position and store each defect in association with the relative position of each defect to improve accuracy of the correction map.

[0021] In some embodiments, for each defect, the controller is configured to control the pattern encoder to identify a type of each defect and / or to quantify an impact of each defect, and to store each defect in association with the location of each defect and the type and / or quantified impact of each defect, thereby generating a pattern correction map in which information regarding the type and impact of each identified defect is also provided, thereby improving the robustness of the coordinate reference pattern.

[0022] In another or further preferred embodiment, the controller is configured to control the displacement measurement system to measure the displacement of the plate along an X-axis defined by the fixed reference frame and along a Y-axis perpendicular to the X-axis. The controller may additionally be configured to control the displacement measurement system to measure a rotation of the plate about a Z-axis perpendicular to the X-axis and the Y-axis, thus allowing coordinates provided by the correction map to be aligned with coordinates measured by an AFM tool to improve ease of implementation.

[0023] In some embodiments, the motion stage is configured to adjust the position of the plate along the Z axis and to adjust the orientation of the plate about the X axis and about the Y axis, and wherein the displacement measurement system is additionally configured to measure the displacement of the plate along the Z axis. Additionally, while controlling the motion stage to relatively move the plate and the pattern encoder in a direction parallel to the plane of the plate, the controller can be configured to control the motion stage to maintain the position and orientation of the plate along the Z axis and about the X and Y axes, respectively, to minimize measurement errors during movement of the plate.

[0024] In a preferred embodiment of the device, the displacement measurement system comprises a laser interferometer system to measure the displacement of the motion stage with sub-micron resolution.

[0025] In another preferred or even more preferred embodiment, the actuation stage includes a planar air bearing for moving the plate to minimize friction while moving the plate.

[0026] Preferably, the motion stage and the fixed reference frame are mechanically and thermally isolated from each other to avoid force and / or thermal influences affecting the measurements.

[0027] In some embodiments, the device comprises a housing for providing a regulated environment for at least the fixed reference frame and the motion stage.

[0028] The present invention will be described in more detail hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, absolute and relative sizes of systems, components, layers and regions may be exaggerated for clarity. The embodiments may be described with reference to schematic and / or cross-sectional illustrations of possible idealized embodiments and intermediate structures of the invention. In this specification and the drawings, like numbers refer to like elements throughout. Relative terms and their derivatives should be construed to refer to the orientation shown in the drawings currently being described or discussed. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation, unless specifically stated otherwise.

[0029] Turning now to FIG. 7, a system 1 for performing scanning probe microscopy (e.g. atomic force microscopy) according to the present invention is illustrated. The system 1 comprises a scanning probe microscopy tool 2 (e.g. atomic force microscopy tool, hereinafter also designated with reference numeral 2). The system also includes a grid qualification tool 3, or otherwise referred to as a device, for qualifying a coordinate reference pattern. The grid qualification tool 3 may for example be formed by or comprise a device 10, further described below. Moreover, an automatic or semi-automatic transfer arrangement 4 may optionally be provided in the system 1 to enable the transfer of a plate 5 including a coordinate reference pattern 210 between the atomic force microscope tool 2 and the device 10 forming the grid qualification tool 3. This arrangement 4 is optional, since the plate 5 may also be transferred manually between the tool 2 and the tool 3. For example, system 1 may be configured with tools 2 and 3 in close proximity to one another to allow plate 5 to be easily transported between multiple tools (with or without configuration 4), or in some cases grid qualification tool 3 may be configured remotely from atomic force microscope tool 2, or even not in the same building. In this latter embodiment, it is preferred that plate 5 is manually transported between tools 2 and 3. Grid qualification tool 3 may be a separate tool without the presence of atomic force microscope tool 2, for example in the form of any of devices 10 described herein, and thus does not form a system 1.

[0030] In FIG. 1, a device 10 for qualifying a coordinate reference pattern 210 on a plate 5, e.g. a grid plate, for use in an atomic force microscope (AFM) tool is shown. The device 10 comprises a fixed reference frame 110, e.g. a metrology frame. A pattern encoder 200 is configured to read the coordinate reference pattern 210 on the plate. The device 10 further comprises a movement stage 300 configured to move the plate 5 and the pattern encoder 200 relative to each other in a direction parallel to the plane of the plate 5. The device 10 is configured to receive the plate 5 to perform a qualification test, e.g. by enabling the plate 5 to be mounted (manually, automatically or semi-automatically) on the movement stage 300 or on the fixed reference frame 110, as further described below. The pattern encoder 200 is, for example, mounted or suspended on the fixed reference frame 110 at a position remote from the plate 5, or alternatively, mounted or suspended on the movement stage 300 when the plate is mounted on the fixed reference frame 110 in some embodiments.

[0031] For example, the motion stage 300 can be a one- or two-dimensional translation stage in a Cartesian coordinate frame, e.g., an xy stage, or in a polar coordinate frame, e.g., an r-θ stage. The motion stage 300 can be configured, for example, to move the plate 5 while the pattern encoder 200 is mounted to a fixed reference frame 110. Alternatively, the motion stage 300 can be configured to move the pattern encoder 200 while the plate 5 is mounted to a fixed reference frame 110.

[0032] In the device 10, a displacement measuring system 400 is configured to measure the displacement of the plate 5 or the pattern encoder 200 relative to the fixed reference frame 110, and measures the displacement of the actuation stage with sub-micron resolution. For example, the resolution of the displacement measuring system 400 is less than 500 nm, or 10-300 nm, or 50-200 nm. In FIG. 1, the displacement measuring system 400 is shown configured to measure the displacement of the plate 5 relative to the fixed reference frame 110. The displacement measuring system 400 can be based, for example, on optical, magnetic, inductive or capacitive measurement principles, or any combination thereof. For example, the displacement measuring system 400 can be a laser interferometer system, for example comprising one or more laser heads, interferometers and reflectors, or the displacement measuring system 400 can be a linear encoder system, comprising an optical or magnetic scanning head moving along a scale.

[0033] The device 10 further comprises a controller 800 configured to control the actuation stage 300, the pattern encoder 200 and the displacement measurement system 400. The controller 800 may be an integral part of the device 10 or may be part of a computer system operatively connected to the device 10.

[0034] While controlling the actuation stage 300, the controller 800 is configured to control the pattern encoder 200 to identify defects in the coordinate reference pattern 210. For each defect, the controller 800 is configured to identify the position of the defect and measure the displacement of the plate 5 or the pattern encoder 200 relative to the fixed reference frame 110 by controlling the displacement measurement system 400. The controller 800 is configured to store each defect in association with the position of the each defect, for example in a computer readable memory, which may be an integral part of the device 10 or may be part of a computer system operatively connected to the device 10.

[0035] In some embodiments, the controller 800 is configured to identify defects in at least a subset of the coordinate reference pattern 210, such as the entire coordinate reference pattern 210, or a specific area in the coordinate reference pattern 210, or multiple dispersed areas in the coordinate reference pattern 210, to create a pattern correction map.

[0036] Alternatively or additionally, information about the defects may be stored in a data file or memory without creating a map. At least the location of the defects may be saved to allow for correction of the location relative to the defects. Any additional information improves accuracy, but is optional to include in the data file or memory.

[0037] In other or further embodiments, the controller 800 is configured to control the pattern encoder 200 to identify, for each defect, a type of defect, such as a geometric deviation relative to the expected pattern of the measured coordinate reference pattern 210, or a missing piece, or a scratch or other type of damage in the coordinate reference pattern 210.

[0038] Additionally or alternatively in these embodiments, the controller 800 is configured to control the pattern encoder 200 to quantify, for each defect, the effect of each defect, e.g., provide a quantified size, length or depth of the defect, or include a quantification of the defect as a whole, e.g., the defect including its shape, or provide an indication of the usefulness of that region of the coordinate reference pattern 210.

[0039] Additionally in these or other embodiments, the controller 800 is configured to store each defect in association with its location and its type and / or quantified impact. In this manner, a pattern correction map can be created that provides, in addition to the location, also information regarding the type and impact of each defect identified on the map, thereby improving the robustness of the coordinate reference pattern so that, for example, an AFM tool can respond to each defect in the most appropriate way.

[0040] 2, the controller 800 may be configured to control the pattern encoder 200 to identify at least one reference position 250 in the coordinate reference pattern 210, e.g., a predefined position or a dedicated homing mark or fiducial in the coordinate reference pattern 210, before controlling the pattern encoder 200 to identify defects. For each reference position 250, the controller 800 is configured to identify the position of the reference position by controlling the displacement measurement system 400 to measure the displacement of the plate 5 relative to the fixed reference frame 110, and to store each reference position 250 in association with the position of the respective reference position 250. This combination of identified reference positions 250 and defects can be used by, for example, an AFM tool to quickly scan which coordinate reference pattern 210 or plate 5 is being used in the AFM tool.

[0041] In some further embodiments of the device 10, the controller 800 is configured to calculate, for each defect, a relative position of said each defect relative to at least one reference position 250, and to store each defect in association with said relative position of said each defect. For example, the controller 800 is configured to calculate the relative position of defect A with respect to three reference positions 250, and to store defect A in association with its relative position relative to the three reference positions 250. A single reference position 250 is sufficient, provided that its position on the plate 5 and its orientation are known. Multiple reference positions 250 improve accuracy.

[0042] Preferably, the relative positions are calculated relative to at least two reference positions 250, e.g., relative to two to four reference positions 250. In some embodiments, the controller 800 is configured to derive the relative positions of each defect from the calculated relative positions relative to the at least two reference positions 250. For example, the controller 800 is configured to derive the relative position of defect A from the calculated relative positions relative to four reference positions 250, e.g., by averaging the four relative positions. In this manner, a more accurate pattern correction map can be obtained by the controller 800.

[0043] Preferably, as shown in Fig. 2, the controller 800 is configured to control the displacement measuring system 400 to measure the displacement of the plate 5 along an X-axis defined by the fixed reference frame 110 and along a Y-axis perpendicular to the X-axis. In this way, the measured and stored positions of each identified defect, and such coordinates provided by the correction map, can be aligned with the coordinates measured by the AFM tool, facilitating the implementation of the correction map in the AFM tool, for example by minimizing the need for geometric transformations that may result in servo delays and / or positioning errors. Preferably, the displacement measuring system 400 comprises adjustment means for adjusting the orientation of the X-axis relative to the Y-axis so that they are perpendicular and intersect, in order to minimize measurement errors, such as Abbe errors.

[0044] In some further embodiments, the controller 800 is additionally configured to control the displacement measurement system 400 to measure the rotation of the plate 5 about a Z-axis perpendicular to the X-axis and the Y-axis. Preferably, the displacement measurement system 400 comprises adjustment means for adjusting the relative orientation between the X-axis, the Y-axis and the Z-axis so that they are all perpendicular and intersect at one point (which point is preferably on the plane of the coordinate reference pattern 210) in order to minimize measurement errors, such as the Abbe error.

[0045] In another or further embodiment, as shown in Fig. 3, the actuation stage 300 is configured to adjust the position of the plate along the Z axis and to adjust the orientation of the plate about the X axis and about the Y axis, where the displacement measurement system is additionally configured to measure the displacement of the plate along the Z axis. For example, the actuation stage 300 may comprise an adjustment means 310, e.g., an adjustment mechanism comprising an adjustment screw or an actuator. By having an actuation stage configured to adjust the position and orientation of the plate 5 along the Z axis and about the X and Y axes, installation errors, e.g., encoder misalignment, cosine error and Abbe error, can be minimized.

[0046] Additionally, in some embodiments, while controlling the actuation stage 300 to relatively move the plate 5 and the pattern encoder 200 in a direction parallel to the plane of the plate 5, the controller 800 is configured to control the actuation stage 300 to maintain the position and orientation of the plate 5 along the Z axis and about the X and Y axes, respectively, during the movement of the plate 5, in order to minimize measurement errors, such as cosine errors and Abbe errors, despite geometric variations in the plate 5 and / or the actuation stage 300, or variations caused by dynamic or thermal effects.

[0047] 4 illustrates an exemplary embodiment of the device 10, where the displacement measurement system 400 comprises a laser interferometer system, e.g., one or more mirrors, interferometers and / or laser heads, preferably configured in an adjustable manner to minimize measurement errors, e.g., measurement errors related to dead paths in the laser path or cosine or Abbe errors. Preferably, one or more mirrors of the system are mounted on the actuator stage 300 to minimize moving mass. One or more interferometers can be mounted, e.g., on a fixed reference frame 110. Preferably, one or more laser heads are mounted at a distance from the fixed reference frame, e.g., by using a mirror or prism system, to avoid the heat of the laser heads affecting the measurements.

[0048] To create an accurate correction map, good results can be achieved with a laser interferometer system with good wavelength stability, e.g. better than 0.02 ppm, small mirror flatness, e.g. smaller than λ / 10, and good mirror surface roughness, e.g. better than 2 nanometers RMS. Besides the quality of these aspects, the accuracy of the correction map may also depend on other aspects, e.g. the resolution of the displacement measurement system, the quality of the alignment of the system components relative to each other, temperature stability, dynamic errors, etc. Repeatable measurement errors, e.g. caused by defects in the mirror shape or misalignment of components, can be corrected, e.g. by taking into account the results of static or dynamic calibration routines of the displacement measurement system used to define the correction map, to further improve the accuracy of the correction map, e.g. better than 1 nanometer.

[0049] The laser interferometer system may be configured to measure two-dimensional displacements of the motion stage 300, such as x- and y-displacements, or r- and θ-displacements, to measure the movement by the motion stage 300 of the plate 5 and the pattern encoder 200 relative to each other in a direction parallel to the plane of the plate 5. Alternatively, the laser interferometer system may be configured to measure one- or three-dimensional displacements of the motion stage 300 to respectively simplify or verify measurements relative to a fixed reference frame.

[0050] In some embodiments, the actuation stage 300 includes a planar air bearing 330 for moving the plate 5, which minimizes friction between the actuation stage 300 and the plate 5 during movement, thereby reducing the amount of hysteresis or virtual play. By minimizing (quasi-)static friction, stick-slip behavior can be reduced, thereby improving the overall positioning accuracy of the actuation stage 300. Alternatively, the actuation stage 300 can include other types of bearings, such as ball bearings, roller bearings, or magnetic bearings, for moving the plate with low friction. Alternatively or additionally, the actuation stage 300 can include an elastic hinge mechanism for moving the plate 5 at least partially without friction and hysteresis. For example, the actuation stage 300 can provide movement of the plate 5 by a two-stroke actuation mechanism with a large stroke equipped with roller bearings and a small stroke equipped with an elastic hinge mechanism.

[0051] In another or further embodiment, the actuation stage 300 and the fixed reference frame 110 are mechanically and thermally isolated from each other to prevent any force or temperature changes originating from the actuation stage 300 from affecting the fixed reference frame 110 and affecting the measurements. Preferably, the fixed reference frame 110 is designed as a metrology frame, isolated from other device components and from environmental influences. For example, the fixed reference frame 110 can have a heavy mass support structure 600, e.g., a granite base, to attenuate external forces. The support structure 600 can be isolated from the ground by vibration isolators 660. As shown in FIG. 4, the actuation stage 300 can be attached to a force frame 390 that is independently attached to the support structure 600 and thus mechanically and thermally isolated from the fixed reference frame 110. Optionally, vibration isolation devices 660 can be added where the force frame 390 and fixed reference frame 110 are attached to the support structure 600. Additionally, the fixed reference frame 110 is preferably made of a low thermal expansion material, such as Zerodur, to limit thermal expansion, and preferably has parts with matched thermal expansion coefficients to avoid warping.

[0052] In some preferred embodiments, the device 10 comprises an enclosure 900 for providing a regulated environment for at least the fixed reference frame 110 and the actuation stage 300. For example, the enclosure 900 may provide a constant temperature inside the enclosure 900, for example to reduce thermal expansion of the fixed reference frame 110 and / or the plate 5. The enclosure 900 may further provide a constant pressure inside the enclosure 900, for example to avoid fluctuations in the performance of the planar air bearing 330 used by the actuation stage 300. The enclosure 900 may also provide constant lighting and humidity conditions for the pattern encoder 200 and / or the displacement measurement system 400, for example to avoid measurement errors due to optical aberrations or fluctuations. Preferably, the enclosure 900 is also configured to prevent dust or other particles from entering the enclosure 900 and contaminating, for example, the coordinate reference pattern 210 and / or the pattern encoder 200 and / or the displacement measurement system 400.

[0053] 5 illustrates a data file 20 for use in an atomic force microscope (AFM) tool generated by device 10 according to any of the embodiments of the present invention, for example as part of a real-time positioning strategy for an AFM or mini-AFM. Figure 5 shows that the MAFM first receives desired settings in step 91, and then in step 92 calculates actual settings based on the desired settings by using data file 20.

[0054] The data file 20 comprises an array of identified defects in at least a subset of a coordinate reference pattern 210 on a plate, e.g., a grid plate. The array of identified defects may, for example, be representative of the entire coordinate reference pattern 210, or may be representative of a particular area within the coordinate reference pattern 210, or may be representative of multiple distributed areas or nodes within the coordinate reference pattern 210. In the data file 20, each identified defect is associated with a position of the identified defect relative to at least one reference position on the coordinate reference pattern, e.g., a homing mark or fiducial, thereby creating a correction map of the coordinate reference pattern 210.

[0055] For example, the data file may comprise an array of defects identified by the pattern encoder 200 covering a particular area in the coordinate reference pattern 210, where each defect is associated with an x- and y-position measured by the displacement measurement system 400 relative to an origin mark on the coordinate reference pattern 210. Alternatively, the data file 20 may comprise an array of defects identified by the pattern encoder covering the entire coordinate reference pattern, where each defect is associated with an r- and θ-coordinate measured by the displacement reference system relative to two reference positions on the coordinate reference pattern.

[0056] 5, the MAFM tool can use the set points corrected by the data file 20 in combination with input from a pattern encoder 200 reading a coordinate reference pattern 210, where the signal of the pattern encoder 200 is converted to a measured position in step 94 and moved to an actual set point under a control loop in step 93, resulting in a servo position error in step 95. The advantage of using the data file 20 to calculate the actual set point is that it reduces the servo position error relative to a system that does not have such a data file 20. This can be explained by the data file 20 providing a correction map of the coordinate reference pattern 210, thereby acting as a calibrated feedforward signal for the control loop.

[0057] In Fig. 6, a method 30 for qualifying a coordinate reference pattern 210 on a plate 5, for example a grid plate or grated disc, for use in an atomic force microscope (AFM) tool by a device is shown. The method comprises in a first step 31 moving the plate 5 and the pattern encoder 200 relative to each other in a direction parallel to the plane of the plate 5 by a movement stage 300. In a second step 32, defects in the coordinate reference pattern 210 are identified by the pattern encoder 200 configured to read the coordinate reference pattern 210 on the plate 5. In a third step 33, the position of said defects is identified for each defect by a displacement measurement system 400 configured to measure the displacement of the plate 5 relative to a fixed reference frame 110. In a fourth step 34, each defect is stored in association with its position to create a pattern correction map.

[0058] Hereinafter, various features of various embodiments of the present invention will be highlighted in a series of numbered statements or paragraphs. These features are not to be construed as limiting the invention or inventive concept, but are merely provided to highlight some of the features of the invention described herein, and do not imply any particular order of importance or relevance of such features. The present invention is limited only by the scope of the appended claims, which are set forth in the correspondingly titled section. The numbered statements include the following:

[0059] Statement 1: A device for qualifying coordinate reference patterns on a plate for use in an atomic force microscope (AFM) tool, comprising: fixed frame of reference; a pattern encoder configured to read the coordinate reference pattern on the plate; an actuation stage configured to move the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate; a displacement measurement system configured to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame; and a controller configured to control the motion stage, the pattern encoder, and the displacement measurement system; It is equipped with wherein while controlling the actuation stage, the controller is configured to control the pattern encoder to identify defects in the coordinate reference pattern; wherein for each defect, the controller is configured to identify a location of each defect by controlling the displacement measurement system to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame; and wherein the controller is configured to store each defect in association with the location of each defect. The device.

[0060] Statement 2: A device according to statement 1, configured to identify defects in at least a subset of the coordinate reference patterns to create a pattern correction map.

[0061] Statement 3: A device described in statement 1 or 2, wherein prior to controlling the pattern encoder to identify defects, the controller is configured to control the pattern encoder to identify at least one reference position in the coordinate reference pattern, and for each reference position, to identify the position of the reference position by controlling the displacement measurement system to measure the displacement of the plate relative to the fixed reference frame, and to store each reference position in association with the position of the respective reference position.

[0062] Statement 4: The device described in Statement 3, wherein for each defect, the controller is configured to calculate a relative position of each defect relative to at least one reference position, and to store each defect in association with the relative position of each defect.

[0063] Statement 5: A device described in any one of statements 1 to 4, wherein, for each defect, the controller is configured to control the pattern encoder to identify a type of each defect and / or to quantify an impact of each defect, and to store each defect in association with the location of each defect and the type and / or quantified impact of each defect.

[0064] Statement 6: A device described in any one of statements 1 to 5, wherein the controller is configured to control the displacement measurement system to measure the displacement of the plate along an X axis defined by the fixed reference frame and along a Y axis perpendicular to the X axis.

[0065] Statement 7: The device described in Statement 6, wherein the controller is configured to control the displacement measurement system to measure rotation of the plate about a Z-axis perpendicular to the X-axis and the Y-axis.

[0066] Statement 8: A device described in any one of statements 1 to 7, wherein the actuation stage is configured to adjust the position of the plate along the Z axis and to adjust the orientation of the plate about the X axis and about the Y axis, and wherein the displacement measurement system is additionally configured to measure the displacement of the plate along the Z axis.

[0067] Statement 9: The device described in Statement 8, wherein the controller is configured to control the actuation stage to maintain the position and orientation of the plate along the Z axis and about the X axis and the Y axis, respectively, while controlling the actuation stage to relatively move the plate and the pattern encoder in a direction parallel to the plane of the plate.

[0068] Statement 10: A device described in any one of statements 1 to 9, wherein the displacement measuring system comprises a laser interferometer system.

[0069] Statement 11: A device described in any one of statements 1 to 10, wherein the actuation stage comprises a planar air bearing for moving the plate.

[0070] Statement 12: A device described in any one of statements 1 to 11, wherein the actuating stage and the fixed reference frame are mechanically and thermally isolated from one another.

[0071] Statement 13: A device described in any one of statements 1 to 12, comprising a housing for providing a regulated environment for at least the fixed reference frame and the actuation stage.

[0072] Statement 14: A data file for use in an atomic force microscope (AFM) tool generated by a device described in any one of statements 1 to 13, the data file comprising an array of identified defects in at least one subset of a coordinate reference pattern on a plate, wherein each identified defect is associated with a position of the identified defect relative to at least one reference position on the coordinate reference pattern.

[0073] Statement 15: A method for qualifying a coordinate reference pattern on a plate for use in an atomic force microscope (AFM) tool by a device, comprising: moving the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate with an actuation stage; identifying defects in a coordinate reference pattern by a pattern encoder configured to read the coordinate reference pattern on the plate; identifying, for each defect, a location of the defect by a displacement measurement system configured to measure a displacement of the plate relative to a fixed reference frame; and storing each defect in association with its location to generate a pattern correction map; The method comprising:

Claims

1. 1. A system for performing atomic force microscopy, the system comprising: an atomic force microscope tool configured to receive a plate including a coordinate reference pattern thereon for providing positional references to system elements of the atomic force microscope tool; and A device for qualifying said coordinate reference pattern on said plate. Equipped with wherein the device is configured to receive the plate to perform a qualification test; and A fixed frame of reference; a pattern encoder configured to read the coordinate reference pattern on the plate; a motion stage configured to move the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate; a displacement measurement system configured to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame; and a controller configured to control the motion stage, the pattern encoder, and the displacement measurement system; Equipped with wherein while controlling the actuation stage, the controller is configured to control the pattern encoder to identify defects in the coordinate reference pattern; wherein for each defect, the controller is configured to identify a location of each defect by controlling the displacement measurement system to measure the displacement of the plate or the pattern encoder relative to the fixed reference frame; and wherein the controller is configured to store each defect in association with the location of each defect. The system.

2. The system of claim 1 , wherein the controller is configured to identify defects in at least a subset of the coordinate reference patterns to create a pattern correction map.

3. 2. The system of claim 1, wherein prior to controlling the pattern encoder to identify defects, the controller is configured to control the pattern encoder to identify at least one reference position in the coordinate reference pattern, and for each reference position, to identify the position of the reference position by controlling the displacement measurement system to measure the displacement of the plate relative to the fixed reference frame, and to store each reference position in association with the position of the each reference position.

4. 4. The system of claim 3, wherein for each defect, the controller is configured to calculate a relative position of each defect relative to at least one reference position and store each defect in association with the relative position of each defect.

5. 5. The system of claim 1, wherein for each defect, the controller is configured to control the pattern encoder to identify a type of each defect and / or to quantify an effect of each defect, and to store each defect in association with the location of each defect and the type and / or quantified effect of each defect.

6. 5. The system of claim 1, wherein the controller is configured to control the displacement measurement system to measure the displacement of the plate along an X-axis defined by the fixed reference frame and along a Y-axis perpendicular to the X-axis.

7. The system of claim 6 , wherein the controller is configured to control the displacement measurement system to measure rotation of the plate about a Z-axis perpendicular to the X-axis and the Y-axis.

8. 5. The system of claim 1, wherein the actuation stage is configured to adjust a position of the plate along the Z axis and to adjust an orientation of the plate about the X axis and about the Y axis, and wherein the displacement measurement system is additionally configured to measure a displacement of the plate along the Z axis.

9. 9. The system of claim 8, wherein the controller is configured to control the motion stage to maintain the position and orientation of the plate along the Z axis and about the X and Y axes, respectively, while controlling the motion stage to relatively move the plate and the pattern encoder in a direction parallel to a plane of the plate.

10. The system of any one of claims 1 to 4, wherein the displacement measurement system comprises a laser interferometer system.

11. The system of any one of claims 1 to 4, wherein the actuation stage comprises a planar air bearing for moving the plate.

12. The system of any one of claims 1 to 4, wherein the motion stage and the fixed reference frame are mechanically and thermally isolated from each other.

13. A system according to any preceding claim, comprising an enclosure for providing a regulated environment for at least said fixed reference frame and said motion stage.

14. A device for use in a system according to any one of claims 1 to 4 for qualifying a coordinate reference pattern on a plate for use in an Atomic Force Microscopy (AFM) tool.

15. 15. A data file for use in an atomic force microscope (AFM) tool generated by the device described in claim 14, the data file comprising an array of identified defects in at least a subset of a coordinate reference pattern on a plate, wherein each identified defect is associated with a position of the identified defect relative to at least one reference position on the coordinate reference pattern.

16. 1. A method for device-qualifying a coordinate reference pattern on a plate for use in an atomic force microscope (AFM) tool, comprising: moving the plate and the pattern encoder relative to one another in a direction parallel to a plane of the plate with an actuation stage; identifying defects in a coordinate reference pattern by a pattern encoder configured to read the coordinate reference pattern on the plate; identifying, for each defect, a location of the defect by a displacement measurement system configured to measure a displacement of the plate relative to a fixed reference frame; and storing each defect in association with its location to generate a pattern correction map; The method comprising:

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