Shape measurement method and shape measurement device

Abstract

To provide a shape measuring method and a shape measuring instrument that are capable of generating combined data with stitching processing errors corrected, when stitching shape measuring data together.SOLUTION: A shape measuring method has: a first combined data generation step of generating first combined data by stitching a plurality of shape measurement data together, a second combined data generation step of generating second combined data by patching the plurality of shape measuring data together, and a correction step of correcting the first combined data based on differential data between the first combined data and the second combined data.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a shape measuring method and a shape measuring instrument for measuring the shape of a surface to be measured in a non-contact manner. [Background technology]

[0002] Electrostatic chucks are known as chucks for holding wafers. They have an embossed wafer-holding surface (surface to be measured) and hold the wafer on this wafer-holding surface by electrical force (see Patent Document 1). Such electrostatic chucks are required to have the straightness of the top surfaces of the numerous embossments formed on the wafer-holding surface meet certain standards. Therefore, electrostatic chuck manufacturers or semiconductor manufacturing facilities measure the straightness of the top surface of each embossment. Specifically, the shape of the wafer-holding surface is measured using a measuring device capable of measuring the shapes of various surfaces to be measured, and the straightness is measured by extracting only the measurement results for the top surfaces of the embossments from the shape measurement results.

[0003] For example, if the measuring device is a contact type such as the surface roughness measuring device described in Patent Document 2, the stylus of the measuring device is moved along the wafer holding surface while in contact with the wafer holding surface of the electrostatic chuck. In this way, the stylus scans the wafer holding surface so as to cross the top surfaces of the multiple embossments, thereby obtaining a straightness measurement result for the top surface of each embossment.

[0004] Furthermore, when the measuring device is a non-contact type such as a white light interference microscope or a laser confocal microscope, the measuring device has a limited measurement range (observation field of view). Therefore, the measuring device continuously measures the shape of the wafer-holding surface while moving one of the measuring device and the wafer-holding surface relative to the other in a direction perpendicular to the measurement optical axis of the measuring device, thereby obtaining multiple pieces of shape measurement data. Then, each piece of shape measurement data is stitched together to generate composite data of a length that allows for evaluation of straightness (see Non-Patent Document 1). Based on this composite data, the straightness measurement results of the top surface of each embossment can be obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-14515 [Patent Document 2] Patent No. 6458335 [Non-patent literature]

[0006] [Non-Patent Document 1] Development of a stitching algorithm using approximate reference shapes: M. Negishi et al., Journal of the Japan Society for Precision Engineering, 81, 6(2015) 555. Summary of the Invention [Problem to be solved by the invention]

[0007] The embossments are minute protrusions with a diameter of 200 μm to 1 mm and a height of approximately 10 μm to 20 μm. For this reason, the contact-type measuring device described in Patent Document 2 may not be able to bring the stylus into sufficient contact with the top surface of the embossment, making it difficult to measure the straightness of the top surface of each embossment.

[0008] On the other hand, non-contact measuring devices can measure even minute shapes such as embossments without any problems. However, when stitching together each piece of shape measurement data using the stitching process described in Non-Patent Document 1, an error component (stitching process error) occurs in the stitched portion, and there is a risk that accurate straightness measurement results for the top surface of each embossment cannot be obtained from the combined data.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a shape measurement method and a shape measurement device that can generate composite data in which stitching processing errors have been corrected when shape measurement data is joined together using stitching processing. [Means for solving the problem]

[0010] A shape measurement method for achieving the object of the present invention includes a data acquisition step of acquiring a plurality of shape measurement data continuously measured by a measuring device that measures the shape of the surface to be measured non-contact, while moving the surface to be measured relative to the measuring device in a direction perpendicular to the measurement optical axis of the measuring device, the plurality of shape measurement data having partially overlapping measurement ranges; a first synthetic data generation step of stitching together the plurality of shape measurement data acquired in the data acquisition step using a stitching process to generate first synthetic data; a second synthetic data generation step of patching together the plurality of shape measurement data acquired in the data acquisition step using a patching process to generate second synthetic data; a differential data generation step of generating differential data between the first synthetic data and the second synthetic data; a first error calculation step of calculating a first error that occurs when the shape measurement data are stitched together using the differential data; and a correction data calculation step of subtracting the first error from the first synthetic data to calculate correction data for the first synthetic data.

[0011] According to this shape measurement method, the first error that occurs when connecting shape measurement data by stitching processing can be determined from the difference data between the first composite data generated by the stitching processing and the second composite data generated by the patching processing.

[0012] In a shape measurement method according to another aspect of the present invention, the first error calculation step includes a noise removal step of performing noise removal processing on the difference data, and a subtraction step of performing subtraction processing of a second error that occurs when connecting shape measurement data by patching processing and that is not removed by the noise removal processing from the difference data, thereby making it possible to determine the first error.

[0013] A shape measuring method according to another aspect of the present invention includes a second error acquisition step of acquiring a second error in advance, and a first error calculation step of performing subtraction processing based on the second error acquired in the second error acquisition step, thereby determining the first error.

[0014] In a shape measuring method according to another aspect of the present invention, the subtraction step performs subtraction on the difference data that has been subjected to noise removal processing.

[0015] In a shape measuring method according to another aspect of the present invention, the noise removal process is a filtering process that extracts wavelength components having lengths at least twice the length of the measurement range from the difference data.

[0016] In another aspect of the shape measurement method of the present invention, in the data acquisition step, a stage on which the surface to be measured is placed is moved in a vertical direction while acquiring multiple shape measurement data measured continuously by the measurement device, and stage deflection occurs during the stage movement, and the observation point on the surface to be measured included in the measurement range is displaced in the optical axis direction of the measurement optical axis according to the stage deflection angle, and the second error indicates the displacement of the observation point in the optical axis direction for each stage position according to the deflection angle for each stage position.

[0017] A shape measuring machine for achieving the object of the present invention includes a data acquisition unit that acquires a plurality of shape measurement data continuously measured by a measuring device that measures the shape of the surface to be measured non-contact while moving the surface to be measured relative to the measuring device in a direction perpendicular to the measurement optical axis of the measuring device, the plurality of shape measurement data having partially overlapping measurement ranges between successive shape measurement data; a first composite data generation unit that stitches together the plurality of shape measurement data acquired by the data acquisition unit using a stitching process to generate first composite data; a second composite data generation unit that stitches together the plurality of shape measurement data acquired by the data acquisition unit using a patching process to generate second composite data; a differential data generation unit that generates differential data between the first composite data and the second composite data; a first error calculation unit that calculates a first error that occurs when the shape measurement data is stitched together using the differential data; and a correction data calculation unit that subtracts the first error from the first composite data to calculate correction data for the first composite data.

[0018] In a shape measuring instrument according to another aspect of the present invention, the first error calculation unit includes a noise removal unit that performs noise removal processing on the difference data, and a subtraction processing unit that performs subtraction processing to subtract from the difference data a second error that occurs when connecting shape measurement data by patching processing and that is not removed by the noise removal processing. [Effects of the Invention]

[0019] When shape measurement data is stitched together by stitching, the present invention can generate composite data in which stitching process errors have been corrected. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram of a shape measuring machine for measuring the shape of a surface to be measured of various objects to be measured. [Figure 2] FIG. 2 is a top view of an electrostatic chuck that is a measurement target of the shape measuring instrument. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the wafer holding surface of the electrostatic chuck taken along the X direction. [Figure 4] FIG. 2 is a functional block diagram of a control device. [Figure 5] FIG. 10 is an explanatory diagram for explaining measurement control of shape measurement data by a measurement control unit. [Figure 6] 10 is a flowchart showing the flow of a straightness measurement process by the form measuring machine. [Figure 7] 7 is a graph showing an example of composite shape measurement data generated in the processing of step S3 in FIG. 6. [Figure 8] 7 is a graph showing an example of composite shape measurement data generated in the processing of step S4 in FIG. 6. [Figure 9] FIG. 10 is an explanatory diagram for explaining deflection of the moving stage for each position in the X direction. [Figure 10] 10 is an explanatory diagram for explaining displacement in the Z direction of the observation point on the wafer holding surface within the measurement range according to the bending angle of the moving stage. FIG. [Figure 11]10 is an explanatory diagram for explaining a Z-direction position error included in the composite shape measurement data. FIG. [Figure 12] FIG. 7 is an explanatory diagram for explaining the process of generating differential data in the process of step S5 in FIG. 6. [Figure 13] FIG. 7 is an explanatory diagram for explaining the noise removal process executed in the process of step S6 in FIG. 6. [Figure 14] FIG. 7 is an explanatory diagram for explaining the subtraction process executed in the process of step S8 in FIG. 6. [Figure 15] 7 is an explanatory diagram for explaining the correction process of the composite shape measurement data executed in the process of step S9 in FIG. 6, and the straightness calculation process executed in the process of step S10. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] [Configuration of shape measuring machine] Fig. 1 is a schematic diagram of a shape measuring instrument 10 that measures the shape of the measurement surface of various objects. Fig. 2 is a top view of an electrostatic chuck W, which is the measurement target of the shape measuring instrument 10. Fig. 3 is an enlarged cross-sectional view of the wafer holding surface Wa (corresponding to the measurement surface in the present invention) of the electrostatic chuck W, taken along the X direction. Note that, of the mutually orthogonal X, Y and Z directions in the figure, the X and Y directions are parallel to the horizontal direction, and the Z direction is the height direction (up and down).

[0022] 1 to 3, the wafer holding surface Wa of the electrostatic chuck W is embossed to form a large number of embossments 9. A shape measuring machine 10 measures the shape of the wafer holding surface Wa and measures the straightness of the upper surface of each embossment 9 based on the shape measurement results (hereinafter simply referred to as straightness measurement). Note that in FIG. 3 (and other figures as well), the shape, diameter, height, and spacing of the embossments 9 are partially exaggerated to clarify them.

[0023] The shape measuring machine 10 is used to carry out the shape measuring method of the present invention, and includes a base 12 , a linear guide mechanism 14 , a moving stage 16 , a measuring device 18 , and a control device 20 .

[0024] The base 12 has an upper surface parallel to the XY directions, in other words, an upper surface perpendicular to a measurement optical axis OA of a measurement device 18 described later.

[0025] The linear guide mechanism 14 moves the electrostatic chuck W (wafer holding surface Wa) in the X direction relative to a measuring device 18, which will be described later. The linear guide mechanism 14 includes a rail 14a, a block 14b, and an actuator 14c.

[0026] One or more rails 14a are provided on the upper surface of the base 12, and extend in the X direction. Note that multiple rails 14a may be provided. The block 14b is held by the rails 14a so as to be movable in the X direction. A moving stage 16 is attached to this block 14b.

[0027] The actuator 14c is, for example, a motor drive mechanism, etc. Under the control of a control device 20 (described later), the actuator 14c moves the block 14b along the X direction, thereby moving the moving stage 16 (electrostatic chuck W) in the X direction.

[0028] Although not shown, the linear guide mechanism 14 is provided with a detection sensor that detects the X-direction position of the block 14b, i.e., the X-direction position of the moving stage 16. This detection sensor sequentially outputs stage position information indicating the X-direction position of the moving stage 16 to the control device 20.

[0029] The moving stage 16 has an upper surface parallel to the X and Y directions (perpendicular to the optical axis direction of the measurement optical axis OA) and is attached to the block 14b. An electrostatic chuck W is placed on the upper surface of the moving stage 16. When the moving stage 16 is moved in the X direction by the linear guide mechanism 14, the electrostatic chuck W is moved in the X direction relative to a measuring device 18, which will be described later.

[0030] The measuring device 18 is disposed above the base 12 and the moving stage 16 in the Z direction, and has a measurement optical axis OA parallel to the Z direction. This measuring device 18 uses, for example, a vertical scanning white light interferometer microscope or a laser confocal microscope, and measures the shape of the wafer-holding surface Wa in a non-contact manner, and outputs shape measurement data D indicating the shape of the wafer-holding surface Wa to the control device 20. Note that the shape measurement data D also includes data used to calculate the shape of the wafer-holding surface Wa, such as an interference signal detected by the white light interferometer microscope.

[0031] The measurement range R (observation field, field of view range) in which the measuring device 18 can measure the shape of the wafer-holding surface Wa in one measurement is smaller than the wafer-holding surface Wa. For this reason, the measuring device 18 continuously measures the shape of the wafer-holding surface Wa within the measurement range R while the linear guide mechanism 14 moves the moving stage 16 (electrostatic chuck W) in the X direction. This allows for the acquisition of multiple shape measurement data D that indicate the shape of a straightness measurement region, which is a region within the wafer-holding surface Wa with a length required for straightness measurement.

[0032] Fig. 4 is a functional block diagram of the control device 20. As shown in Fig. 4 and the already-described Fig. 1, the control device 20 comprehensively controls the operations of the linear guide mechanism 14 and the measuring device 18, and, as will be described in detail later, calculates and corrects composite shape measurement data DS (see Fig. 7) of the straightness measurement region based on a plurality of shape measurement data D input from the measuring device 18, and calculates the straightness of the upper surface of each embossment 9. In addition to the linear guide mechanism 14 and the measuring device 18, a memory unit 22, an operation unit 24, and a display unit 26 are connected to this control device 20.

[0033] In addition to a control program (not shown), the memory unit 22 also stores in advance a Z-direction position error E2 (see Figure 9), which is a calculation error that occurs when each piece of shape measurement data D is stitched together by patching processing, as will be described in detail later.

[0034] The operation unit 24 is used for various operations of the profile measuring machine 10, such as starting various measurements such as straightness measurement, and setting each part of the profile measuring machine 10. The display unit 26 displays various setting screens and measurement results of various measurements such as straightness measurement.

[0035] [Controller function] The control device 20 is configured by an arithmetic device such as a personal computer, and includes an arithmetic circuit configured by various processors, memories, etc. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic device (SPLD), complex programmable logic device (CPLD), and field programmable gate array (FPGA)). The various functions of the control device 20 may be realized by a single processor, or by multiple processors of the same or different types.

[0036] The control device 20 executes the control program read from the storage unit 22, thereby functioning as a measurement control unit 30, a data acquisition unit 32, and an arithmetic processing unit 33.

[0037] 5 is an explanatory diagram for explaining measurement control of shape measurement data D by the measurement control unit 30. As shown in Fig. 5, the measurement control unit 30 drives the linear guide mechanism 14 in response to a measurement start operation on the operation unit 24 to move the moving stage 16 and the electrostatic chuck W in the X direction.

[0038] At the same time, the measurement control unit 30 causes the measuring device 18 to measure the shape of the wafer-holding surface Wa each time the moving stage 16 is moved a predetermined distance in the X direction. As a result, the measuring device 18 continuously measures the shape of the wafer-holding surface Wa within the measurement range R while relatively moving (scanning) the measurement range R in the X direction within the straightness measurement region of the wafer-holding surface Wa. At this time, the measurement control unit 30 adjusts the timing of the shape measurement by the measuring device 18 and the moving speed of the moving stage 16 so that the measurement range R of the measuring device 18 partially overlaps before and after consecutive measurements (see the shaded area in the figure). As a result, the measurement ranges R of consecutive consecutive shape measurement data D partially overlap, making it possible to splice together the consecutive shape measurement data D at their overlapping regions.

[0039] 4, the data acquisition unit 32 is connected to the measuring device 18 via a communication interface (not shown) in a wired or wireless manner. Every time the measuring device 18 measures the shape of the wafer holding surface Wa, the data acquisition unit 32 acquires shape measurement data D from the measuring device 18 and also acquires stage position information of the moving stage 16 from the linear guide mechanism 14. This makes it possible to obtain multiple pieces of shape measurement data D that indicate the shape within the straightness measurement region and stage position information at the time each piece of shape measurement data D was measured.

[0040] Based on each shape measurement data D and the position information for each shape measurement data D acquired by the data acquisition unit 32, the calculation processing unit 33 performs the following operations: (1) generates composite shape measurement data DS (see Figure 7) of the straightness measurement area by the stitching process; (2) calculates the stitching process error E1 (see Figure 14) generated in the stitching process; (3) corrects the composite shape measurement data DS using the stitching process error E1; and (4) calculates the straightness of the top surface of each embossing 9.

[0041] Furthermore, the calculation processing unit 33 calculates the stitching processing error E1 (see FIG. 14) in (2) above based on the difference data ΔD between the composite shape measurement data DS generated by the stitching processing and the composite shape measurement data DP of the straightness measurement area generated by the patching processing, as shown in FIG. 12, which will be described later. Therefore, the calculation in (2) above involves (2-1) generating the composite shape measurement data DP by the patching processing, (2-2) calculating the difference data ΔD between the composite shape measurement data DP, DS, and (2-3) calculating the stitching processing error E1 from the difference data ΔD.

[0042] To perform the above processes (1) to (4), the calculation processing unit 33 functions as a stitching processing unit 34, a patching processing unit 36, a difference data generation unit 38, a Z-direction position error acquisition unit 40, a stitching processing error calculation unit 42, a correction data calculation unit 44, and a straightness calculation unit 46. In addition, the stitching processing error calculation unit 42 functions as a noise removal unit 42a and a subtraction processing unit 42b.

[0043] The stitching processing unit 34 performs the process (1) above. The patching processing unit 36, the difference data generation unit 38, the Z-direction position error acquisition unit 40, and the stitching processing error calculation unit 42 perform the process (2) above. Specifically, the patching processing unit 36 ​​performs the process (2-1) above, the difference data generation unit 38 performs the process (2-2) above, and the Z-direction position error acquisition unit 40 and the stitching processing error calculation unit 42 (noise removal unit 42a, subtraction processing unit 42b) perform the process (2-3) above. Furthermore, the correction data calculation unit 44 performs the process (3) above, and the straightness calculation unit 46 performs the process (4) above.

[0044] [Operation of this embodiment] FIG. 6 is a flowchart showing the flow of straightness measurement processing by the form measuring machine 10 according to the form measuring method of the present invention.

[0045] 6, after the electrostatic chuck W is placed on the moving stage 16, the operator performs an operation to start straightness measurement using the operation unit 24, which activates the various components of the control device 20. First, the measurement control unit 30 controls the linear guide mechanism 14 and the measuring device 18 to perform continuous measurement of shape measurement data D within the straightness measurement region as shown in FIG. 5 (step S1), and the data acquisition unit 32 acquires each piece of shape measurement data D and stage position information at the time of measurement of each piece of shape measurement data D (step S2). Step S2 corresponds to the data acquisition step of the present invention.

[0046] Fig. 7 is a graph showing an example of composite shape measurement data DS generated in the processing of step S3 in Fig. 6 [processing (1) above]. As shown in step S3 in Fig. 6 and Fig. 7, stitching processing unit 34 uses stitching processing to connect the pieces of shape measurement data D acquired by data acquisition unit 32 to generate composite shape measurement data DS of the straightness measurement region. Note that stitching processing unit 34 corresponds to the first composite data generation unit of the present invention, the composite shape measurement data DS corresponds to the first composite data of the present invention, and step S3 corresponds to the first composite data generation step of the present invention.

[0047] Specifically, the stitching processing unit 34 determines overlapping areas between consecutive previous and next shape measurement data D in each piece of shape measurement data D, based on the stage position information at the time of measurement of each piece of shape measurement data D acquired by the data acquisition unit 32. Then, for each piece of previous and next shape measurement data D, the stitching processing unit 34 processes the data in the overlapping areas using a known best fit method, and then calculates the amount of rotation [pitching angle around the Y axis and rolling angle around the X axis] required to smoothly stitch together the overlapping areas of the previous and next shape measurement data D.

[0048] Next, the stitching processing unit 34 performs rotation correction on each of the front and rear shape measurement data D, rotating the front and rear shape measurement data D based on the previously calculated rotation amount, and then stitches together the overlapping areas of the front and rear shape measurement data D at the average height of the overlapping areas in the Z direction. At this time, the overlapping areas of the front and rear shape measurement data D use the data with the higher signal strength. This generates the composite shape measurement data DS.

[0049] In this type of stitching process, if there is a difference in the overlapping area between the previous and next shape measurement data D, for example if noise components are included in one of the overlapping areas between the previous and next shape measurement data D, a calculation error will be included in the calculation of the above-mentioned rotation amount. For this reason, when the previous and next shape measurement data D are stitched together, an error component such as a waviness component, called a stitching process error E1 (corresponding to the first error of the present invention, see FIG. 14), will be included in the stitched portion (overlapping area).

[0050] Therefore, in this embodiment, the stitching processing error E1 is calculated through the processing of steps S4 to S8 described below [processing (2) above], and then the composite shape measurement data DS is corrected based on the stitching processing error E1 in the processing of step S9 described below [processing (3) above].

[0051] Fig. 8 is a graph showing an example of composite shape measurement data DP generated in the processing of step S4 in Fig. 6 [processing (2-1) above]. As shown in step S4 in Fig. 6 and Fig. 8, patching processing unit 36 ​​generates composite shape measurement data DP of the straightness measurement region by patching together the pieces of shape measurement data D acquired by data acquisition unit 32. Note that patching processing unit 36 ​​corresponds to the second composite data generation unit of the present invention, the composite shape measurement data DP corresponds to the second composite data of the present invention, and step S4 corresponds to the second composite data generation step of the present invention.

[0052] Specifically, similar to the stitching process described above, the patching processor 36 determines overlapping areas between consecutive adjacent shape measurement data D within each piece of shape measurement data D based on stage position information at the time of measurement of each piece of shape measurement data D. Next, for each piece of shape measurement data D, the patching processor 36 joins the overlapping areas of the adjacent shape measurement data D in the X and Y directions at common X and Y coordinates within the overlapping areas, and also joins them in the Z direction at the average height of the two overlapping areas for each X and Y coordinate. Then, for each piece of shape measurement data D, the patching processor 36 embeds surface data created by the average value of both pieces of shape measurement data D in the overlapping areas of the adjacent shape measurement data D. This generates composite shape measurement data DP.

[0053] Such composite shape measurement data DP includes Z-direction position error E2 (see FIG. 11) caused by deflection of moving stage 16 during movement in the X direction.

[0054] FIG. 9 is an explanatory diagram for explaining the deflection of the moving stage 16 for each position in the X direction.

[0055] As shown in FIG. 9, when the movable stage 16 moves in the X direction during continuous measurement of shape measurement data D, the center of gravity G of the electrostatic chuck W on the movable stage 16 changes from the start to the end of the movement. As a result, the load moment acting on the movable stage 16 changes, causing deflection (pitching and rolling) of the movable stage 16. This causes the deflection angle (pitching angle and rolling angle) of the movable stage 16 to change for each position of the movable stage 16 in the X direction. As a result, the observation point P (see FIG. 10) on the wafer holding surface Wa within the measurement range R changes in the Z direction, i.e., in a direction parallel to the measurement optical axis OA, for each position of the movable stage 16 in the X direction.

[0056] 10 is an explanatory diagram for explaining displacement in the Z direction of an observation point P (also referred to as a measurement point) on the wafer holding surface Wa within the measurement range R in accordance with the deflection angle of the movable stage 16. Note that the symbol C in FIG. 10 indicates the center position of the block 14b (movable stage 16) in the X direction. Also, the actuator 14c (see FIG. 1) is not shown in FIG. 10.

[0057] 10, if the length of block 14b in the X direction is "B," the distance in the X direction from block 14b to measurement optical axis OA (observation point P) is "x," and the deflection angle (pitching angle, etc.) of moving stage 16 is "i," then observation point P is displaced in the Z direction by a displacement value ΔZ [ΔZ=(x+B / 2)×sin(i)] compared to observation point P0 when deflection angle i is 0 degrees. This ΔZ changes for each position of moving stage 16 in the X direction.

[0058] 11 is an explanatory diagram illustrating the Z-direction position error E2 included in the composite shape measurement data DP. As shown in FIG. 11, during continuous measurement of shape measurement data D, the Z-direction displacement value ΔZ of observation point P changes for each X-direction position of moving stage 16, but in the patching process, no correction is made when joining together each piece of shape measurement data D, as in the stitching process described above. Therefore, the composite shape measurement data DP includes a "Z-direction position error E2" equivalent to the displacement value ΔZ for each X-direction position of moving stage 16.

[0059] Here, the deflection angle i (pitching angle, etc.) for each X-direction position of the moving stage 16 can be found using a known calculation formula, or by experiment, simulation, etc. Therefore, by substituting the distance x and the deflection angle i into the calculation formula for the displacement value ΔZ for each X-direction position of the moving stage 16, it is possible to find the Z-direction position error E2 in advance. In this embodiment, the Z-direction position error E2 is stored in advance in the storage unit 22.

[0060] Furthermore, the composite shape measurement data DP also includes calculation errors other than the Z-direction position error E2. As mentioned above, the patching process does not perform the correction that is performed in the stitching process described above, so a step error, which is a short-wavelength (high-frequency) error component, occurs in the joint (overlapping area) of the previous and next shape measurement data D. For this reason, the composite shape measurement data DP includes the Z-direction position error E2 and a step error.

[0061] In this embodiment, the composite shape measurement data DS is generated by the stitching process in step S3, and then the composite shape measurement data DP is generated by the patching process in step S4, but the order may be reversed or the processes may be performed simultaneously.

[0062] Fig. 12 is an explanatory diagram for explaining the generation of differential data ΔD in the processing of step S5 in Fig. 6 [processing (2-2) above]. As shown in step S5 in Fig. 6 and reference numeral XIIA in Fig. 12, differential data generation unit 38 performs processing to subtract one of two types of composite shape measurement data DS, DP, which are created using different stitching methods, from the other. In this way, differential data generation unit 38 calculates differential data ΔD between the composite shape measurement data DS, DP, as shown by reference numeral XIIB in Fig. 12. Note that step S5 corresponds to the differential data generation step of the present invention.

[0063] By calculating the difference between the composite shape measurement data DS and DP in this way, the shape components of the wafer holding surface Wa (each embossment 9) are removed from the difference data ΔD. Therefore, the difference data ΔD includes a stitching process error E1 (see FIG. 14) that occurs in the stitching process, a Z-direction position error E2 and step error that occur in the patching process, and an X-direction position error. The X-direction position error is a short-wavelength (high-frequency) error component that occurs in the calculation of the difference data ΔD because the X-coordinate values ​​of the shape components such as the embossments 9 in the composite shape measurement data DS and DP are not identical, i.e., because there is an error in the X-coordinate value.

[0064] Next, the stitching processing error calculation unit 42 (noise removal unit 42a and subtraction processing unit 42b) starts the processing from step S6 to step S8 [the processing of (2-3) above] to calculate the stitching processing error E1 (see FIG. 14) from the difference data ΔD. Therefore, steps S6 to S8 correspond to the first error calculation step of the present invention, and the stitching processing error calculation unit 42 corresponds to the first error calculation unit of the present invention.

[0065] Fig. 13 is an explanatory diagram for explaining the noise removal process executed in the process of step S6 in Fig. 6. As indicated by reference symbol XIIIA in Fig. 13, the difference data ΔD mainly consists of stitching process error E1 (see Fig. 14) and Z direction position error E2, which are long wavelength (low frequency) signal components that occur in accordance with the stitching intervals of the shape measurement data D, and step error and X direction position error, which are short wavelength (high frequency) signal components, appear as noise components.

[0066] Therefore, as shown in step S6 of FIG. 6 and reference symbol XIIIB of FIG. 13, the noise removal unit 42a performs noise removal processing on the differential data ΔD to remove noise components (step error and X-direction position error) from the differential data ΔD (corresponding to the noise removal step of the present invention). As described above, the stitching processing error E1 (see FIG. 14) occurs depending on the stitching interval of the shape measurement data D. For this reason, the stitching processing error E1 can be considered to be a signal with a wavelength that is at least twice the length of a single measurement range R of the measuring device 18. Therefore, as the noise removal processing, the noise removal unit 42a performs a filter process to extract wavelength components that are at least twice (e.g., three times) the length of the measurement range R from the differential data ΔD. As a result, differential data ΔD1 including the stitching processing error E1 and the Z-direction position error E2 is generated.

[0067] 6, the Z-direction position error acquisition unit 40 acquires the Z-direction position error E2 from the storage unit 22 and outputs it to the subtraction processing unit 42b of the stitching processing error calculation unit 42 (corresponding to the second error acquisition step of the present invention). In this embodiment, the Z-direction position error acquisition unit 40 acquires the Z-direction position error E2 from the storage unit 22, but it may also acquire it from outside the shape measuring machine 10 (for example, a server on the Internet). The timing of step S7 is not particularly limited as long as it occurs before S8, which will be described later.

[0068] Fig. 14 is an explanatory diagram for explaining the subtraction processing executed in the processing of step S8 in Fig. 6. As shown in step S8 in Fig. 6 and Fig. 14, the subtraction processing unit 42b performs subtraction processing to subtract the Z-direction position error E2 (see symbol XIVB) from the difference data ΔD1 (see symbol XIVA) (corresponding to the subtraction processing step of the present invention). As a result, by removing the Z-direction position error E2 from the difference data ΔD1, the stitching processing error E1 (see symbol XIVC) is finally calculated.

[0069] In this embodiment, the noise removal process (step S6) is performed on the difference data ΔD before the subtraction process (step S8), but the noise removal process may be performed first after the subtraction process.

[0070] Fig. 15 is an explanatory diagram for explaining the correction process of the composite shape measurement data DS executed in the process of step S9 [the process (3) above] in Fig. 6, and the straightness calculation process executed in the process of step S10 [the process (4) above]. Note that the symbol ST in Fig. 15 represents the straightness measurement data of the top surface of each embossment 9 obtained from the composite shape measurement data DS and the correction data DS1, respectively.

[0071] As shown in step S9 of Fig. 6 and reference symbol XVA in Fig. 15, the correction data calculation unit 44 calculates correction data DS1 by correcting the composite shape measurement data DS by subtracting the stitching process error E1 calculated in step S8 from the composite shape measurement data DS generated in the above-mentioned step S3. This results in correction data DS1, which is the shape measurement result of the wafer holding surface Wa (straightness measurement area) excluding the stitching process error E1, as shown in reference symbol XVB in Fig. 15. Note that step S9 corresponds to the correction data calculation step of the present invention.

[0072] 6 and symbol XVB in Fig. 15, the straightness calculation unit 46 connects the upper surfaces of the embossments 9 included in the correction data DS1 to calculate straightness measurement data ST for the upper surfaces of the embossments 9. Note that instead of calculating the straightness measurement data ST from the correction data DS1, the straightness calculation unit 46 may execute a process of calculating straightness measurement data ST from the composite shape measurement data DS before correction and a process of subtracting a stitching processing error E1 from this straightness measurement data ST.

[0073] As described above, in this embodiment, by calculating the stitching process error E1 from the difference data ΔD between the composite shape measurement data DS generated by the stitching process and the composite shape measurement data DP generated by the patching process, the composite shape measurement data DS can be corrected based on this stitching process error E1. This allows for the acquisition of corrected data DS1 (corrected composite shape measurement data DS) from which the stitching process error E1 has been removed. As a result, the straightness of the top surface of each embossment 9 can be measured with higher accuracy. [others] In the above embodiment, the linear guide mechanism 14 moves the measuring device 18 and the wafer holding surface Wa (moving stage 16) relative to each other in the X direction, but various types of relative movement mechanisms may be used to move the measuring device 18 and the wafer holding surface Wa relative to each other in the X direction. In this case, in step S7, an error (the second error of the present invention) that occurs when stitching together the shape measurement data D by patching and that is not removed by the noise removal process in step S6 is acquired in advance. Then, in step S8, a subtraction process is performed on the difference data ΔD1 based on this acquired error.

[0074] In the above embodiment, the case where the shape of the wafer holding surface Wa of the embossed electrostatic chuck W and the straightness of the upper surface of each embossment 9 are measured has been described as an example. However, the present invention can be applied to cases where various shapes of various measurement surfaces of various measurement objects are measured.

[0075] The shape measuring instrument 10 of the above embodiment comprises a base 12, a linear guide mechanism 14, a moving stage 16, a measuring device 18, and a control device 20, but the shape measuring instrument of the present invention also includes an instrument that is composed only of the control device 20 (including software and programs), i.e., an analysis device (program, etc.) that acquires and analyzes each shape measurement data D measured by an external measuring device or measuring instrument. [Explanation of symbols]

[0076] 9 Embossing 10 Shape measuring machine 12 Foundation 14 Linear guide mechanism 14a Rail Block 14b 14c Actuator 16 Moving Stage 18 Measuring Equipment 20 Control device 22 Memory section 24 Control section 26 Display section 30 Measurement control section 32 Data Acquisition Section 33 Processing unit 34 Stitching processing section 36 Patching processing section 38 Differential Data Generation Unit 40 Z direction position error acquisition section 42 Stitching processing error calculation unit 42a Noise removal section 42b Subtraction processing unit 44 Correction data calculation section 46 Straightness calculation unit D Shape measurement data DP synthetic shape measurement data DS synthetic shape measurement data DS1 correction data E1 Stitching process error E2 Z direction position error G Center of gravity position OA measurement optical axis P,P0 observation point R Measurement Range ST straightness measurement data W electrostatic chuck Wa Wafer holding surface

Claims

1. a data acquisition step of acquiring a plurality of shape measurement data pieces successively measured by a measuring device that measures the shape of a surface to be measured in a non-contact manner while moving the surface to be measured relative to the measuring device in a direction perpendicular to a measurement optical axis of the measuring device, the plurality of shape measurement data pieces having measurement ranges that partially overlap each other between adjacent shape measurement data pieces; a first composite data generation step of stitching together the plurality of shape measurement data acquired in the data acquisition step to generate first composite data; a second composite data generation step of generating second composite data by patching the plurality of shape measurement data acquired in the data acquisition step; a correcting step of correcting the first combined data based on difference data between the first combined data and the second combined data; A shape measurement method having the following.

2. a data acquisition unit that acquires a plurality of shape measurement data pieces that are continuously measured by a measuring device that measures the shape of a surface to be measured in a non-contact manner while moving the surface to be measured relative to the measuring device in a direction perpendicular to a measurement optical axis of the measuring device, the shape measurement data pieces being such that measurement ranges of adjacent shape measurement data pieces partially overlap; a first composite data generation unit that stitches together the plurality of shape measurement data acquired by the data acquisition unit to generate first composite data; a second composite data generation unit that generates second composite data by patching the plurality of shape measurement data acquired by the data acquisition unit; a correction unit that corrects the first combined data based on difference data between the first combined data and the second combined data; A shape measuring machine equipped with:

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