Surface shape measuring device and surface shape measuring method

Abstract

The invention provides a surface shape measuring device and a surface shape measuring method capable of simply and efficiently measuring the surface shape of a measuring surface of an object on which a transparent material is arranged. The surface shape measuring device includes: a light source unit; an interference unit that generates interference light between the measurement light reflected by the measurement surface and the reference light reflected by the reference surface; a light detection unit that generates a detection signal of the interference light; a surface shape data calculation unit that calculates surface shape data indicating the height position of the surface of the measurement surface on the basis of a change in the intensity of the detection signal; a distribution calculation unit that calculates the distribution of the transparent material on the basis of sensitivity data indicating the detection sensitivity of the detection signal for each position of the measurement surface; an estimation unit that estimates, on the basis of the distribution of the transparent material, base material shape data indicating the height position of the surface of the base material in a transparent region in which the transparent material is disposed from surface shape data in a non-transparent region in which the transparent material is not disposed in the measurement surface; and a shape data correction unit that corrects the surface shape data of the transparent region on the basis of the substrate shape data.

Description

Technical Field

[0001] The present invention relates to a surface shape measuring device and a surface shape measuring method for measuring the surface shape of a measurement surface of a measurement object configured with a transparent material. Background Art

[0002] Conventionally, there has been known a surface shape measuring device that uses light to measure the surface shape of a measurement surface of a measurement object. For example, a surface shape measuring device that employs a white interference method measures the surface shape of a measurement surface of a measurement object by utilizing the interference phenomenon of white light.

[0003] In such a surface shape measuring device that uses light, when a transparent material is present on the measurement surface of the measurement object, it is sometimes difficult to accurately measure the surface shape of the measurement surface of the measurement object due to the influence of the refractive index of the transparent material.

[0004] For example, Patent Document 1 discloses a measuring device that uses the white interference method to measure the film thickness of a transparent material. In this measuring device, the refractive index of one of the transparent materials coated on the measurement object is measured and stored, and the film thickness of the remaining transparent material is measured using the stored refractive index.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-105781 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, in the measuring device of Patent Document 1, information indicating how the transparent material is distributed on the measurement surface of the measurement object is required. Therefore, in the absence of such information, it takes time to determine the transparent material in advance, which causes the measurement operation to become complicated.

[0010] The present invention has been made in view of such circumstances, and an object thereof is to provide a surface shape measuring device and a surface shape measuring method that can simply and efficiently measure the surface shape of a measurement surface of a measurement object configured with a transparent material without causing complication of the measurement operation.

[0011] Means for Solving the Problems

[0012] The surface shape measuring device of the first aspect measures the surface shape of a measurement surface of an object including a base material and a transparent material on the base material. The surface shape measuring device includes: a light source unit having a light source that emits light; an interference unit that splits the light emitted from the light source into measurement light and reference light, emits the measurement light toward the measurement surface and the reference light toward a reference surface, and generates interference light of the measurement light reflected from the measurement surface and the reference light reflected from the reference surface; a light detection unit that detects a detection signal representing the interference light; a surface shape data calculation unit that calculates surface shape data representing the height position of the surface of the measurement surface based on a change in the intensity of the detection signal when the optical path length difference between the measurement light and the reference light is changed; a distribution calculation unit that calculates the distribution of the transparent material in the measurement surface based on sensitivity data representing the detection sensitivity of the detection signal for each position of the measurement surface; an estimation unit that estimates base material shape data representing the height position of the surface of the base material in a transparent region where the transparent material is disposed in the measurement surface based on the distribution of the transparent material calculated by the distribution calculation unit and the surface shape data in a non-transparent region where the transparent material is not disposed in the measurement surface; and a shape data correction unit that corrects the surface shape data in the transparent region based on the base material shape data estimated by the estimation unit.

[0013] In the surface shape measuring device of the second aspect, the shape data correction unit calculates the thickness of the transparent material based on the difference between the height position of the surface of the base material in the transparent region obtained from the base material shape data and the height position of the surface of the measurement surface in the transparent region obtained from the surface shape data.

[0014] In the surface shape measuring device of the third aspect, when the difference is set as d, the refractive index of the transparent material is set as n, and the thickness of the transparent material is set as L, the shape data correction unit calculates the thickness of the transparent material using the following formula: L = d / (n - 1).

[0015] In the surface shape measuring device of the fourth aspect, the shape data correction unit calculates the corrected surface shape data in the transparent region by adding the thickness of the transparent material to the height position of the surface of the base material in the transparent region obtained from the base material shape data.

[0016] In the surface shape measuring device of the fifth aspect, the light source is a light source capable of emitting white light or wavelength-scanned light.

[0017] The surface shape measurement method of the sixth aspect measures the surface shape of the measurement surface of an object including a base material and a transparent material on the base material. The surface shape measurement method includes: an interference generation step of splitting the light emitted from a light source into measurement light and reference light, emitting the measurement light toward the measurement surface and emitting the reference light toward a reference surface, and generating interference light of the measurement light reflected from the measurement surface and the reference light reflected from the reference surface; a light detection step of detecting a detection signal representing the interference light; a surface shape data calculation step of calculating surface shape data representing the height position of the surface of the measurement surface based on the change in the intensity of the detection signal when the optical path length difference between the measurement light and the reference light is changed; a distribution calculation step of calculating the distribution of the transparent material in the measurement surface based on sensitivity data representing the detection sensitivity of the detection signal for each position of the measurement surface; a estimation step of estimating substrate shape data representing the height position of the surface of the substrate in the transparent region where the transparent material is disposed in the measurement surface based on the distribution of the transparent material calculated by the distribution calculation step and the surface shape data in the non-transparent region where the transparent material is not disposed in the measurement surface; and a shape data correction step of correcting the surface shape data in the transparent region based on the substrate shape data estimated by the estimation step.

[0018] In the surface shape measurement method of the seventh aspect, the shape data correction step calculates the thickness of the transparent material based on the difference between the height position of the surface of the substrate in the transparent region obtained from the substrate shape data and the height position of the surface of the measurement surface in the transparent region obtained from the surface shape data.

[0019] In the surface shape measurement method of the eighth aspect, when the difference is set to d, the refractive index of the transparent material is set to n, and the thickness of the transparent material is set to L, the shape data correction step calculates the thickness of the transparent material using the following formula: L = d / (n - 1).

[0020] In the surface shape measurement method of the ninth aspect, the shape data correction step calculates the corrected surface shape data in the transparent region by adding the thickness of the transparent material to the height position of the surface of the substrate in the transparent region obtained from the substrate shape data.

[0021] In the surface shape measurement method of the tenth aspect, the light source is a light source capable of emitting white light or wavelength-scanned light.

[0022] Advantages of the Invention

[0023] According to the present invention, it is possible to simply and efficiently measure the surface shape of the measurement surface of an object provided with a transparent material without causing complication of the measurement operation. Description of the Drawings

[0024] Figure 1It is a schematic diagram of a surface shape measuring device.

[0025] Figure 2 It is a block diagram of a surface shape measuring device.

[0026] Figure 3 It is a flowchart showing the process of measuring the shape of the measurement surface of a workpiece.

[0027] Figure 4 It is an enlarged view of the measurement surface of a workpiece.

[0028] Figure 5 It is a diagram showing an example of an interference fringe curve in an arbitrary pixel of a detection image.

[0029] Figure 6 It is a diagram for explaining the processing of the surface shape data calculation unit.

[0030] Figure 7 It is a diagram for explaining the processing of the distribution calculation unit.

[0031] Figure 8 It is a diagram for explaining the processing of the substrate shape data estimation unit.

[0032] Figure 9 It is a diagram for explaining the processing of the surface shape data correction unit.

[0033] Explanation of reference numerals

[0034] 10: Surface shape measuring device, 12: Optical head, 14: Camera, 16: Driving unit, 18: Scale, 20: Control device, 21: Operation unit, 22: Workbench, 23: Display unit, 24: Workbench driving unit, 26: Light source unit, 26a: Light source, 28: Beam splitter, 30: Interference objective lens, 30A: Objective lens, 30B: Beam splitter, 30C: Reference surface, 32: Imaging lens, 36: Detection image, 38: Position signal, 102: Measurement control unit, 104: Shape operation unit, 106: Surface shape data calculation unit, 108: Distribution calculation unit, 110: Substrate shape data estimation unit, 112: Surface shape data correction unit, AR1: Non-transparent area, AR2: Transparent area, L: Thickness, L1: Measurement light, L2: Reference light, L3: Combined light, S: Measurement surface, S1: Measurement surface, S2: Measurement surface, S3: Measurement surface, W: Workpiece, W1: Substrate, W2: Transparent material, WS: Surface shape data, WS1: Surface shape data, WS2: Surface shape data, WS3: Surface shape data, WS4: Substrate shape data, WS5: Surface shape data. Detailed implementation manners

[0035] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0036] Figure 1 This is a schematic diagram of the surface shape measuring device 10 of the embodiment. It should be noted that in the XYZ directions orthogonal to each other in the figure, the XY direction is the direction parallel to the horizontal direction, and the Z direction is the direction parallel to the up-and-down direction.

[0037] As Figure 1 shown, the surface shape measuring device 10 measures the surface shape (three-dimensional shape) of the measurement surface of the workpiece W as the object to be measured by the white light interference method. Generally speaking, the surface shape measuring device 10 includes an optical head 12, a drive unit 16, a scale 18, and a control device 20. Figure 1 The surface shape measuring device 10 shown in the figure includes a workbench 22 and a workbench drive unit 24. The workpiece W is placed on the workbench 22.

[0038] The optical head 12 is composed of a Michelson-type white light interference microscope as Figure 1 shown. The optical head 12 includes a camera 14, a light source unit 26, a beam splitter 28, an interference objective lens 30, and an imaging lens 32.

[0039] The interference objective lens 30, the beam splitter 28, the imaging lens 32, and the camera 14 are arranged in sequence from the workpiece W along the upper side in the Z direction. In addition, the light source unit 26 is arranged at a position opposed to the beam splitter 28 in the X direction (it can also be the Y direction).

[0040] Under the control of the control device 20, the light source unit 26 emits white light (low coherence light with low coherence) of parallel light beams toward the beam splitter 28 as the measurement light L1. The light source unit 26 can include a light source 26a such as a light emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp that can emit the measurement light L1, and a condenser lens that converts the measurement light L1 emitted from the light source 26a into parallel light beams. The light source unit 26 is an example of the light source unit of the present invention.

[0041] The beam splitter 28 uses a half mirror, for example. The beam splitter 28 reflects a part of the measurement light L1 incident from the light source unit 26 toward the interference objective lens 30 on the lower side in the Z direction. In addition, the beam splitter 28 transmits a part of the combined light L3 described later incident from the interference objective lens 30 to the upper side in the Z direction, and emits the combined light L3 toward the imaging lens 32.

[0042] The interference objective lens 30 is of the Michelson type and includes an objective lens 30A, a beam splitter 30B, and a reference surface 30C. The beam splitter 30B and the objective lens 30A are arranged in sequence from the workpiece W toward the upper side in the Z direction. In addition, the reference surface 30C is arranged at a position opposed to the beam splitter 30B in the X direction (it can also be the Y direction). The beam splitter 30B uses a half mirror, for example.

[0043] The beam splitter 30B splits the measurement light L1 incident from the objective lens 30A into a reference light L2 that passes through the reference optical path and a measurement light L1 that passes through the measurement optical path. The reference light L2 is irradiated onto the reference surface 30C. The measurement light L1 is irradiated onto the workpiece W. After the measurement light L1 that has passed through the beam splitter 30B is irradiated onto the workpiece W, it is reflected by the workpiece W and returns to the beam splitter 30B.

[0044] The reference surface 30C uses, for example, a mirror and reflects the reference light L2 incident from the beam splitter 30B back toward the beam splitter 30B. The reference surface 30C can be manually adjusted in the X direction using a position adjustment mechanism (not shown). Thereby, the optical path length of the reference light L2 between the beam splitter 30B and the reference surface 30C can be adjusted. This reference optical path length is adjusted to be the same (including approximately the same) as the optical path length of the measurement light L1 between the beam splitter 30B and the workpiece W.

[0045] The beam splitter 30B generates a combined light L3 of the measurement light L1 returned from the workpiece W and the reference light L2 returned from the reference surface 30C, and emits the combined light L3 toward the objective lens 30A on the upper side in the Z direction. The combined light L3 passes through the objective lens 30A and the beam splitter 28 and is incident on the imaging lens 32. The light source used in the white interference method is a light source that emits white light (low coherence light). Since white light lacks coherence, even if the light that has passed through the reference optical path and the measurement optical path is combined again by the beam splitter 30B, it does not interfere except under specific conditions. The optical path length of the reference light L2 is constant, but the optical path length of the measurement light L1 changes corresponding to the vertical scan of the optical head 12. It should be noted that, as is well known, when the optical path length difference between the measurement light L1 and the reference light L2 is zero (including approximately zero), the interference between the measurement light L1 and the reference light L2 in all wavelength regions of the visible light rays is enhanced, so the signal intensity of the combined light L3 becomes the maximum. The combined light L3 becomes interference light including interference fringes (for example, refer to Japanese Unexamined Patent Application Publication No. 2017 - 106860). The beam splitter 30B is an example of the interference unit of the present invention. The combined light L3 is an example of the interference light of the present invention.

[0046] The imaging lens 32 images the combined light L3 incident from the beam splitter 28 on the imaging surface (not shown) of the camera 14. Specifically, the imaging lens 32 images the point on the focal plane of the objective lens 30A as an image point on the imaging surface of the camera 14.

[0047] The camera 14 is equipped with an imaging element of the CCD (Charge Coupled Device) type or the CMOS (Complementary Metal Oxide Semiconductor) type. During the period when the optical head 12 is scanned in the scanning direction, the camera 14 detects the combined light L3 (interference light) imaged on the imaging surface by the imaging lens 32 within the field of view of the camera 14, and generates a detection image 36 (detection signal of the interference light) as the result of the detection. The camera 14 is an example of the light detection unit of the present invention.

[0048] The drive unit 16 is composed of a known linear motor or a motor drive mechanism. The drive unit 16 holds the optical head 12 so as to be relatively movable in the Z direction, which is the vertical scanning direction (the optical axis direction of the optical head 12), with respect to the workpiece W. Under the control of the control device 20, the drive unit 16 relatively moves the optical head 12 with respect to the workpiece W at a set scanning speed within the range of the scanning direction.

[0049] It should be noted that it is sufficient that the drive unit 16 can relatively scan the optical head 12 with respect to the workpiece W in the scanning direction. For example, the table 22 supporting the workpiece W may also be scanned in the scanning direction.

[0050] The table 22 has a table surface for supporting the workpiece W. The table surface is composed of a flat surface substantially parallel to the X direction and the Y direction. The table drive unit 24 is composed of a known linear motor or a motor drive mechanism, and relatively horizontally moves the table 22 with respect to the optical head 12 in a plane perpendicular to the scanning direction (the X direction and the Y direction) under the control of the control device 20.

[0051] It should be noted that it is sufficient that the table drive unit 24 can relatively move the table 22 with respect to the optical head 12 in the X direction and the Y direction. For example, the optical head 12 may also be moved with respect to the table 22 supporting the workpiece W in the X direction and the Y direction.

[0052] The scale 18 is a position detection sensor for detecting the position of the optical head 12 in the scanning direction with respect to the workpiece W. For example, an optical linear encoder (also called a scale) is used. The optical linear encoder is composed of, for example, a linear scale formed with slits at constant intervals, and a light receiving element and a light emitting element arranged opposite to each other across the linear scale. The scale 18 repeatedly detects the position of the optical head 12 in the scanning direction (Z direction position), and repeatedly outputs a position signal 38 including position information indicating the position in the scanning direction (Z direction position) to the control device 20.

[0053] The control device 20 comprehensively controls the surface shape measurement device 10 according to the input operation on the operation unit 21, such as switching between the adjustment before measuring the workpiece W (pre-adjustment mode) and the measurement of the workpiece W (measurement mode), setting the measurement conditions in each mode, and calculating the three-dimensional shape in the measurement mode. The display unit 23 displays various information under the control of the control device 20. The control device 20 can calculate the surface shape data of the workpiece W based on the detection image 36 generated by the camera 14 and the output from the scale 18.

[0054] The control device 20 includes an arithmetic circuit composed of various processors and memories. Among the various processors, there are a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and programmable logic devices [such as SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays)]. It should be noted that the various functions of the control device 20 can be implemented by one processor or by multiple processors of the same or different types.

[0055] Figure 2 is a functional block diagram of the control device 20. As Figure 2 shown, the camera 14 and the light source unit 26 of the optical head 12, the drive unit 16, the table drive unit 24, the scale 18, and the operation unit 21 are connected to the control device 20.

[0056] The control device 20 functions as a measurement control unit 102 and a shape calculation unit 104 by executing a control program read from a storage unit (not shown).

[0057] The measurement control unit 102 controls the camera 14, the light source unit 26, the drive unit 16, and the workbench drive unit 24 according to an instruction from the operation unit 21. After starting the emission of the measurement light L1 from the light source unit 26 (light source 26a), the measurement control unit 102 controls the drive unit 16 to scan the optical head 12 in the Z direction. In addition, during the period when the drive unit 16 scans the optical head 12 in the Z direction, based on the detection result of the Z-direction position of the optical head 12 detected by the scale 18, every time the optical head 12 moves a constant pitch in the Z direction, the shooting of the combined light L3 by the camera 14 and the output of the detection image 36 and the position signal 38 from the scale 18 to the control device 20 are repeatedly executed. It should be noted that the Z-direction position of the camera 14 when shooting the combined light L3 by the camera 14 can be detected by the scale 18. Therefore, the pitch when scanning the optical head 12 in the Z direction is not limited to a constant pitch and can also be an unequal pitch.

[0058] Based on a plurality of detection images 36 captured by the camera 14 during the scanning of the optical head 12 in the Z direction and the position information (position signal 38 from the scale 18) indicating the Z-direction position of the optical head 12 when each detection image 36 is captured, the shape calculation unit 104 calculates the surface shape of the measurement surface (including the surface where a transparent material is arranged in a part of the region) of the workpiece W.

[0059] The shape calculation unit 104 includes a surface shape data calculation unit 106, a distribution calculation unit 108, a base material shape data estimation unit 110, and a surface shape data correction unit 112.

[0060] Based on a plurality of detection images 36 (detection signals of interference light) captured by the camera 14 when the optical head 12 is scanned in the Z direction, the surface shape data calculation unit 106 calculates surface shape data indicating the height position of the surface of the measurement surface of the workpiece W. That is, the surface shape data calculation unit 106 calculates surface shape data indicating the height position of the surface of the measurement surface of the workpiece W based on the intensity change of the detection signal of the combined light L3 (interference light) detected by the camera 14 that functions as a light detection unit while changing the optical path length difference between the measurement light L1 and the reference light L2. Regarding the processing of the surface shape data calculation unit 106, see the following description. The surface shape data calculation unit 106 is an example of the surface shape data calculation unit of the present invention.

[0061] Based on the sensitivity data indicating the detection sensitivity of the detection signal of the combined light L3 (interference light) for each position of the measurement surface of the workpiece W, the distribution calculation unit 108 calculates the distribution of the transparent material in the measurement surface of the workpiece W. Regarding the processing of the distribution calculation unit 108, see the following description. The distribution calculation unit 108 is an example of the distribution calculation unit of the present invention.

[0062] Based on the distribution of the transparent material calculated by the distribution calculation unit 108, the substrate shape data estimation unit 110 estimates the substrate shape data representing the height position of the surface of the substrate of the workpiece W in the transparent region where the transparent material is disposed on the measurement surface of the workpiece W, according to the surface shape data in the non-transparent region where the transparent material is not disposed on the measurement surface of the workpiece W. Regarding the processing of the substrate shape data estimation unit 110, see the following description. The substrate shape data estimation unit 110 is an example of the estimation unit of the present invention.

[0063] Based on the substrate shape data estimated by the substrate shape data estimation unit 110, the surface shape data correction unit 112 corrects the surface shape data in the transparent region where the transparent material is disposed on the measurement surface of the workpiece W. Regarding the processing of the surface shape data correction unit 112, see the following description. The surface shape data correction unit 112 is an example of the shape data correction unit of the present invention.

[0064] Next, an example of a method (surface shape measurement method) for measuring the surface shape of the measurement surface of the workpiece W performed by the surface shape measurement device 10 of the embodiment will be described.

[0065] Figure 3 It is a flowchart showing the process of the shape measurement method. Figure 4 It is an enlarged view of the measurement surface S of the workpiece W. Figure 5 It is a diagram for explaining the calculation method of the measurement surface by the shape data calculation unit. Figure 6 It is a diagram for explaining the processing of the surface shape data calculation unit 106. Figure 7 It is a diagram for explaining the processing of the distribution calculation unit 108. Figure 8 It is a diagram for explaining the processing of the substrate shape data estimation unit 110. Figure 9 It is a diagram for explaining the processing of the surface shape data correction unit 112.

[0066] First, the workpiece W as the measurement object is placed on the workbench 22 (step S1). The workpiece W includes an opaque substrate W1 as shown, and includes a transparent material W2 on a part of the substrate W1. Here, as an example, a case where the shape of the substrate W1 constituting the workpiece W is convex (arc-shaped) and curved upward in the Z direction is shown, but it is not limited thereto, and other shapes may also be possible. For example, the shape of the substrate W1 may also be concave and curved downward in the Z direction, or a shape in which concavities and convexities coexist. In addition, it may also be a flat shape perpendicular or inclined obliquely to the Z direction. Figure 4 As shown, it includes an opaque substrate W1 and includes a transparent material W2 on a part of the substrate W1. Here, as an example, a case where the shape of the substrate W1 constituting the workpiece W is convex (arc-shaped) and curved upward in the Z direction is shown, but it is not limited thereto, and other shapes may also be possible. For example, the shape of the substrate W1 may also be concave and curved downward in the Z direction, or a shape in which concavities and convexities coexist. In addition, it may also be a flat shape perpendicular or inclined obliquely to the Z direction.

[0067] The surface shape measurement device 10 measures the surface shape (height position in the Z direction) of the measurement surface S of the workpiece W. It should be noted that in this specification, the measurement surface S of the workpiece W refers to the outermost surface of the workpiece W in the Z direction. For example,Figure 4 The measurement surfaces S of the workpiece W shown become the measurement surfaces S1 and S3 that are the outermost surfaces of the base material W1 and the measurement surface S2 that is the outermost surface of the transparent material W2 on the base material W1.

[0068] Next, the measurement of the measurement surface S of the workpiece W is started (step S2). Specifically, the measurement control unit 102 controls the stage drive unit 24 and the light source unit 26 to sequentially move the measurement position of the measurement surface S of the workpiece W facing the optical head 12 in the XY direction. And at each measurement position, while irradiating the measurement light L1 to the measurement surface S of the workpiece W, the Z-direction scanning of the optical head 12 is performed. During the Z-direction scanning of the optical head 12 at each measurement position, the measurement control unit 102, based on the detection result of the Z-direction position of the optical head 12 detected by the scale 18, each time the optical head 12 moves a constant pitch in the Z direction, repeatedly executes the shooting of the combined light L3 by the camera 14. A plurality of detection images 36 captured by the camera 14 at each constant pitch and the position information (position signal 38 from the scale 18) indicating the Z-direction position of the optical head 12 when each detection image 36 is captured are sequentially input to the shape calculation unit 104.

[0069] Next, surface shape data indicating the height position (Z-direction position) of the surface of the measurement surface S of the workpiece W is calculated (step S3). Specifically, the surface shape data calculation unit 106 calculates the surface shape data of the measurement surface S of the workpiece W through the following process.

[0070] The surface shape data calculation unit 106 detects and compares the luminance values of the pixels of the same coordinates for each of the detection images 36. Next, the surface shape data calculation unit 106 determines the Z-direction position where the luminance value is the maximum for the pixels of the same coordinates for each of the detection images 36, and thus calculates the surface shape data as the height information of the surface of the measurement surface S for each pixel of the same coordinates. That is, the surface shape data calculation unit 106 calculates the surface shape data indicating the height position of the surface of the measurement surface S based on the luminance change of the interference fringes (that is, the change in the intensity of the detection signal of the camera 14) that appear in each detection image 36 when the optical path length difference between the measurement light L1 and the reference light L2 is changed by the Z-direction scanning of the optical head 12.

[0071] Here, Figure 5This is a diagram showing an example of the interference fringe curve Q in an arbitrary pixel of the detection image 36. When the optical path length of the measurement light L1 is smaller than that of the reference light L2, the interference is small and the luminance value is approximately constant. Also, when the optical path length of the measurement light L1 is the same as that of the reference light L2, that is, when the optical path length difference becomes 0, the interference becomes large and the maximum luminance value is displayed. Furthermore, when the optical path length of the measurement light L1 is larger than that of the reference light L2, the interference becomes small again and the luminance value is approximately constant. Thus, Figure 5 The interference fringe curve Q as shown is obtained for each pixel of the same coordinates in each detection image 36. The surface shape data calculation unit 106 determines the Z-direction position where the luminance value becomes the maximum for each pixel of the same coordinates in each detection image 36, and thereby calculates the height information of the measurement surface S for each pixel of the same coordinates. Thus, the surface shape data indicating the height position (Z-direction position) of the surface of the measurement surface S is calculated.

[0072] However, in the case of a workpiece W as shown in Figure 4 which includes a transparent material W2 on a substrate W1, the problem shown in Figure 6 occurs. Figure 6 6-1 in shows the problem in the measurement of the surface shape, Figure 6 and 6-2 in shows the problem in the calculation of the surface shape data.

[0073] First, as shown in Figure 6 6-1, in the non-transparent region AR1 where the transparent material W2 does not exist, the measurement light L1 is reflected by the substrate W1 of the workpiece W, so the surface shape data indicating the height position of the substrate W1 as the measurement surface S can be calculated. On the other hand, the transparent material W2 has a low reflectivity for light. In the transparent region AR2 where the transparent material W2 exists, the measurement light L1 passes through the transparent material W2 and is reflected by the substrate W1 in the transparent region AR2. Therefore, instead of calculating the surface shape data indicating the height position of the surface of the transparent material W2 as the measurement surface S, the surface shape data indicating the height position of the surface of the substrate W1 on the back side of the transparent material W2 is calculated.

[0074] Second, when calculating the surface shape data, the distance that the light travels in the surface shape measurement device 10 is not the actual distance but the optical distance (optical path length). Therefore, when the refractive index of the transparent material W2 is set to n and the thickness of the transparent material W2 is set to L, the optical distance (optical path length) as the distance that the light travels when passing through the transparent material W2 becomes n×L. Thus, as shown in Figure 6As shown in FIG. 6-2, the calculated surface shape data WS appears to have a longer distance in the transparent region AR2 where the transparent material W2 exists, and is calculated as a concave shape. As a result, the measurement surface S of the workpiece W to be measured and the surface shape data WS measured by the surface shape measurement device 10 become different results.

[0075] Therefore, in the surface shape measurement device 10 of the embodiment, based on the above points, in order to measure the surface shape data of the measurement surface S of the workpiece W including the transparent material W2 on the substrate W1, the following-described various processes are implemented.

[0076] As Figure 3 shown, after calculating the surface shape data of the measurement surface S of the workpiece W (step S3), the distribution of the transparent material W2 in the measurement surface S is calculated (step S4). Specifically, the distribution calculation unit 108 acquires sensitivity data indicating the detection intensity of the detection signal for each position (each pixel of the detection image 36) of the measurement surface S. The sensitivity data is obtained based on the maximum luminance value of the interference fringe curve (refer to Figure 5 ) obtained for the pixels of the same coordinates for each detection image 36. In Figure 7 , as an example of the sensitivity data, a graph is shown with the signal intensity on the vertical axis and the horizontal position (position in the X direction or Y direction) on the horizontal axis.

[0077] As Figure 7 shown, the signal intensity of the detection signal varies depending on the presence or absence of the transparent material W2 in the measurement surface S. Specifically, in the non-transparent region AR1, the measurement light L1 reflected from the substrate W1 is detected by the camera 14. On the other hand, in the transparent region AR2, the measurement light L1 that has passed through the transparent material W2 and is reflected from the substrate W1 is detected by the camera 14. That is, in the transparent region AR2, the measurement light L1 is attenuated when passing through the transparent material W2, so the signal intensity of the detection signal is relatively weaker compared to the non-transparent region AR1. Therefore, by utilizing such a phenomenon, the distribution of the transparent material W2 in the measurement surface S can be obtained.

[0078] After the distribution calculation unit 108 acquires the sensitivity data indicating the detection sensitivity at each position of the measurement surface S, based on the acquired sensitivity data, the distribution of the transparent material W2 in the measurement surface S is calculated. In Figure 7In the example shown, a region with a relatively weak signal intensity of the detection signal is calculated as the transparent region AR2, and a region with a relatively strong signal intensity of the detection signal is calculated as the non-transparent region AR1. According to such a calculation method, even when the distribution of the transparent material W2 on the measurement surface S is unknown, information on the distribution of the transparent material W2 on the measurement surface S can be easily obtained based on the sensitivity data indicating the detection sensitivity at each position on the measurement surface S. Therefore, there is no need to determine the transparent material W2, and the complication of the measurement operation can be prevented.

[0079] After calculating the distribution of the transparent material W2 as described above (step S4), substrate shape data WS4 representing the height position of the surface of the substrate W1 in the transparent region AR2 is estimated (step S5). Specifically, based on the distribution of the transparent material W2 calculated by the distribution calculation unit 108, the substrate shape data estimation unit 110 estimates substrate shape data WS4 representing the height position of the surface of the substrate W1 in the transparent region AR2 where the transparent material W2 is disposed on the measurement surface S, according to the surface shape data in the non-transparent region AR1 where the transparent material W2 is not disposed on the measurement surface S.

[0080] Figure 8 FIG. 8-1 shows the surface shape data WS of the measurement surface S calculated by the surface shape data calculation unit 106 in step S2 when measuring the workpiece W shown. As shown in FIG. 8-1, the surface shape data of the portion corresponding to the transparent region where the transparent material W2 is disposed shows a concave shape with a lower height position than the adjacent other surface shape data WS1 and WS3, which is different from the actual shape (the shape of the measurement surface S of the workpiece W shown). Figure 4 shown workpiece W Figure 8 FIG. 8-1 Figure 4 shape of the measurement surface S of the workpiece W shown)

[0081] Figure 8 FIG. 8-2 shows the substrate shape data WS4 estimated by the substrate shape data estimation unit 110 for the surface shape data WS shown in FIG. 8-1. As shown in FIG. 8-2, based on the distribution of the transparent material W2 calculated by the distribution calculation unit 108, the substrate shape data estimation unit 110 estimates the substrate shape data WS4 in the transparent region AR2 by using the surface shape data WS1 and WS3 (calculated by the surface shape data calculation unit 106) in the non-transparent region AR1 adjacent to the transparent region AR2. Figure 8 FIG. 8-1 Figure 8 FIG. 8-2

[0082] As a method for estimating the substrate shape data WS4 representing the height position of the surface of the substrate W1 in the transparent region AR2, for example, known methods such as spline interpolation, Lagrange interpolation, or the least squares method can be applied. The surface shape data WS1 and WS are examples of the surface shape data in the non-transparent region in the measurement surface of the present invention. The substrate shape data WS4 is an example of the substrate shape data representing the height position of the surface of the substrate in the transparent region of the present invention.

[0083] After estimating the substrate shape data WS4 in the transparent region AR2 in this way (step S5), based on the estimated substrate shape data WS4, the surface shape data WS2 in the transparent region AR2 is corrected (step S6). Specifically, the surface shape data correction unit 112 calculates the height position of the surface of the transparent material W2 as the measurement surface S by using the difference between the surface shape data WS2 and the substrate shape data WS4 in the transparent region AR2, thereby correcting the surface shape data WS2 in the transparent region AR2.

[0084] Refer to Figure 9 A detailed description of the method for correcting the surface shape data WS2 in the transparent region AR2 will be given. First, as shown in FIG. 9-1, the surface shape data correction unit 112 obtains the difference d in the Z direction between the surface shape data WS2 and the substrate shape data WS4 at each position in the XY direction in the transparent region AR2. Figure 9

[0085] Here, the difference d is represented by the following formula (1) when the refractive index of the transparent material W2 is set to n and the thickness of the transparent material W2 is set to L (unknown).

[0086] d = n×L - L = L(n - 1) (1)

[0087] The surface shape data correction unit 112 calculates the thickness L of the transparent material W2 by using the following formula (2) based on the difference d obtained from the surface shape data WS2 and the substrate shape data WS4 and the known refractive index n of the transparent material W2. It should be noted that the refractive index n of the transparent material W2 is set to be pre-stored in the storage unit (not shown) of the control device 20.

[0088] L = d / (n - 1) (2)

[0089] Figure 9 After the surface shape data correction unit 112 calculates the thickness L of the transparent material W2 at each position in the XY direction as described above, as shown in FIG. 9-2, the surface shape data WS2 for the transparent region AR2 is corrected by adding the calculated thickness L to the substrate shape data WS4 of the transparent region AR2. Thus, the corrected surface shape data WS5 can be obtained.​​

[0090] The shape operation unit 104 finally determines the surface shape data WS obtained by combining the surface shape data WS1 and WS3 in the combined non-transparent region AR1 and the corrected surface shape data WS5 in the transparent region AR2 as the surface shape data WS of the measurement surface S of the workpiece W and outputs it. The surface shape data WS (surface shape data WS1, WS5, and WS3) thus obtained becomes the surface shape data corresponding to the actual shape of the surface of the measurement surface S (measurement surfaces S1, S2, and S3) of the workpiece W. Then, this flowchart ends.

[0091] As described above, according to the surface shape measurement device 10 of the embodiment, information on the distribution of the transparent material W2 in the measurement surface S can be easily obtained. Moreover, based on the distribution of the transparent material W2, the surface shape data WS2 for the transparent region AR2 can be corrected, and ultimately the surface shape data WS can be made to correspond to the shape of the actual measurement surface S of the workpiece W.

[0092] It should be noted that in the embodiment, the case where the optical head 12 is a Michelson type white interference microscope has been described, but it may also be a Mirau type white interference microscope or a Linnik type white interference microscope.

[0093] In addition, in the embodiment, the case where the present invention is applied to the white interference type surface shape measurement device 10 has been described as an example, but it is not limited thereto. For example, the present invention can also be applied to a wavelength scanning type surface shape measurement device. The structure of the wavelength scanning type surface shape measurement device is well-known, so a detailed description thereof is omitted. However, it mainly includes: a wavelength scanning light source that emits light while changing the wavelength as incident light; an interference unit (interferometer) that divides the incident light emitted from the wavelength scanning light source into reference light and measurement light, and combines the reflected light of the measurement light and the reference light into interference light; a light detection unit that detects the interference light after the reflected light and the reference light are combined by the interference unit; and a control device. The control device, like the control device 20 of the surface shape measurement device 10, has functions of calculating surface shape data, calculating the distribution of the transparent region, estimating the substrate shape data of the transparent region, and correcting the surface shape data of the transparent region.

Claims

1. A surface shape measuring device for measuring the surface shape of a measuring surface of an object including a substrate and a transparent material on the substrate, wherein: The surface shape measuring device comprises: a light source unit having a light source for emitting light; an interference unit that divides the light emitted from the light source into measurement light and reference light, emits the measurement light toward the measurement surface and emits the reference light toward the reference surface, and generates interference light of the measurement light reflected on the measurement surface and the reference light reflected on the reference surface; a light detection unit that detects the interference light and generates a detection signal of the interference light; a surface shape data calculation unit that calculates surface shape data indicating a height position of a surface of the measurement surface based on a change in the intensity of the detection signal when a difference in optical path length between the measurement light and the reference light is changed; a distribution calculation unit that calculates the distribution of the transparent material on the measurement surface based on sensitivity data indicating the detection sensitivity of the detection signal at each position on the measurement surface; an estimating unit that estimates, based on the distribution of the transparent material calculated by the distribution calculating unit, substrate shape data indicating a height position of the surface of the substrate in a transparent region in which the transparent material is arranged on the measurement surface, from the surface shape data in a non-transparent region in which the transparent material is not arranged on the measurement surface; as well as A shape data correction unit corrects the surface shape data in the transparent region based on the base shape data estimated by the estimating unit.

2. The surface shape measuring device according to claim 1, wherein: The shape data correction unit calculates the thickness of the transparent material based on a difference between a height position of a surface of the substrate in the transparent region obtained from the substrate shape data and a height position of a surface of the measurement surface in the transparent region obtained from the surface shape data.

3. The surface shape measuring device according to claim 2, wherein: When the difference is d, the refractive index of the transparent material is n, and the thickness of the transparent material is L, The shape data correction unit calculates the thickness of the transparent material using the following formula: L=d / (n-1).

4. The surface shape measuring device according to claim 2, wherein: The shape data correction unit calculates the corrected surface shape data in the transparent region by adding the thickness of the transparent material to the height position of the surface of the substrate in the transparent region obtained based on the substrate shape data.

5. The surface shape measuring device according to any one of claims 1 to 4, wherein: The light source is a light source capable of emitting white light or wavelength-swept light.

6. A surface shape measuring method, comprising measuring the surface shape of a measuring surface of an object including a substrate and a transparent material on the substrate, wherein: The surface shape measuring method comprises: an interference generating step of dividing light emitted from a light source into measurement light and reference light, emitting the measurement light toward the measurement surface and emitting the reference light toward the reference surface, and generating interference light of the measurement light reflected on the measurement surface and the reference light reflected on the reference surface; a light detection step of detecting a detection signal representing the interference light; a surface shape data calculation step of calculating surface shape data indicating a height position of a surface of the measurement surface based on a change in the intensity of the detection signal when a difference in optical path length between the measurement light and the reference light is changed; a distribution calculation step of calculating the distribution of the transparent material in the measurement surface based on sensitivity data indicating the detection sensitivity of the detection signal at each position of the measurement surface; an estimating step of estimating, based on the distribution of the transparent material calculated in the distribution calculating step, substrate shape data indicating a height position of the surface of the substrate in a transparent region in which the transparent material is arranged on the measuring surface, from the surface shape data in a non-transparent region in which the transparent material is not arranged on the measuring surface; and The shape data correction step corrects the surface shape data in the transparent area based on the base shape data estimated in the estimating step.

7. The surface shape measuring method according to claim 6, wherein: The shape data correction step calculates the thickness of the transparent material based on a difference between a height position of a surface of the substrate in the transparent region obtained from the substrate shape data and a height position of a surface of the measurement surface in the transparent region obtained from the surface shape data.

8. The surface shape measuring method according to claim 7, wherein: When the difference is d, the refractive index of the transparent material is n, and the thickness of the transparent material is L, The shape data correction step calculates the thickness of the transparent material using the following formula: L=d / (n-1).

9. The surface shape measuring method according to claim 7, wherein: The shape data correction step calculates the corrected surface shape data in the transparent area by adding the thickness of the transparent material to the height position of the surface of the substrate in the transparent area obtained based on the substrate shape data.

10. The surface shape measuring method according to any one of claims 6 to 9, wherein: The light source is a light source capable of emitting white light or wavelength-swept light.

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