Analysis device, analysis method, interferometric measurement system, and storage medium

Abstract

The present invention relates to an analysis device, an analysis method, an interference measurement system, and a storage medium. The analysis device (200) includes: an acquisition unit (210) that acquires a plurality of interference images based on a plurality of optical path lengths between a reference surface (132) and a surface of a measurement target object (10) from an interference measurement device; a calculation unit (230) that respectively calculates the sine wave component and cosine wave component of the interference signal of each pixel in the plurality of interference images; an error detection unit (240) that detects the error between a first Lissajous figure formed by the sine wave component and cosine wave component of each pixel and an ideal second Lissajous figure; a correction unit (250) that corrects the sine wave component and cosine wave component of each pixel based on the error; and a geometric shape calculation unit (260) that calculates the surface geometric shape of the measurement target object (10) based on the corrected sine wave component and cosine wave component.

Description

Technical Field

[0001] The present invention relates to an analysis device, an analysis method, an interference measurement system and a storage medium. Background Art

[0002] Inspection of the surface geometry of semiconductor wafers and high-precision mirrors may require high precision, and such inspection is performed using a Fizeau laser interferometer or a Twyman-Green interferometer. This interferometer measures the surface geometry of the object being measured by analyzing a plurality of interference images obtained by changing the phase difference between the measurement light and the reference light reflected at the surface of the object being measured. As a technique for changing the phase difference between the reference light and the measurement light, a mechanical method of mechanically moving an optical element and a polarization method using polarized light are known (see Patent Document 1: U.S. Patent 7,796,273, Patent Document 2: U.S. Patent 7,796,275, Patent Document 3: U.S. Patent 7,948,639, Patent Document 4: Japanese Patent Application Publication No. 2017-20962, and Non-Patent Document 1: D. Malacara, “Optical Shop Testing 3rd ed.”, Wiley-Interscience, 2007). Summary of the Invention

[0003] Problems to be solved by the invention

[0004] Conventionally, when analyzing multiple interference patterns generated by a laser interferometer, the change in the phase difference between reference light and measurement light has sometimes been treated as a known parameter. However, the phase shift of a phase shifter used to change the phase difference can contain errors due to, for example, operating errors of piezoelectric elements and defects in optical components. Furthermore, since the phase shift is affected by external factors such as vibration and air turbulence, achieving an ideal phase shift using a phase shifter is difficult. Because errors from the ideal phase shift affect the analysis of interference patterns generated by a laser interferometer, there has been a desire to easily reduce the impact of such phase shift errors.

[0005] The present invention focuses on these points, and an object of the present invention is to conveniently reduce the influence of a phase shift error in the case of analyzing an interference image of a laser interferometer.

[0006] Solutions for solving problems

[0007] A first aspect of the present invention provides an analysis device for analyzing an interference image of an interference measurement device, wherein the interference measurement device is used to generate the interference image of reference light and measurement light reflected by utilizing laser irradiation on a reference surface and the surface of a measurement object, the analysis device comprising: an acquisition unit for acquiring a plurality of the interference images based on a plurality of optical path lengths between the reference surface and the surface of the measurement object from the interference measurement device; a calculation unit for respectively calculating the sine wave component and cosine wave component of the interference signal of each pixel in the plurality of the interference images; an error detection unit for detecting an error between a first Lissajous figure formed based on the sine wave component and the cosine wave component of each pixel and an ideal second Lissajous figure; a correction unit for correcting the sine wave component and the cosine wave component of each pixel based on the error; and a geometric shape calculation unit for calculating the surface geometric shape of the measurement object based on the corrected sine wave component and the cosine wave component.

[0008] The error detection unit can use a circle with a predetermined radius as the second Lissajous figure, and the correction unit can correct the first Lissajous figure to be close to the second Lissajous figure by correcting the center coordinates and ellipticity of the first Lissajous figure based on the sine wave component and the cosine wave component of each pixel.

[0009] The error detection unit may extract information of the first Lissajous figure having an elliptical shape from the sine wave component and the cosine wave component of the interference signal of each pixel in the plurality of interference images.

[0010] The calculation unit calculates the sine wave component as I according to the following equation: sin (x n ,y m ), and the cosine wave component is calculated as I cos (x n ,y m ):

[0011] [Equation 1]

[0012]

[0013]

[0014]

[0015] Where: I i (x n ,y m) shows image data of N×M pixels of K interference images, where i=1, 2, 3, ..., K, n=1, 2, 3, ..., N, and m=1, 2, 3, ..., M, and δ i is a phase shift amount corresponding to the optical path length between the reference surface and the surface of the object to be measured when the i-th interference image is generated.

[0016] The error detection unit plots u=I with the horizontal axis being the u axis and the vertical axis being the v axis. cos (x n ,y m ) and v=I sin (x n ,y m ), extracting information of the first Lissajous figure having an elliptical shape, the information including the center coordinates (u0, v0) of the ellipse, the major axis a x 、Short axis a y , and the angle θ of the axis, and the correction unit corrects the sine wave component and the cosine wave component using the following equation so that the first Lissajous figure approaches the second Lissajous figure whose central coordinate is the origin:

[0017] [Equation 2]

[0018] I′ sin (x n ,y m )=I sin (x n ,y m )-v0

[0019] I′ cos (x n ,y m )=I cos (x n ,y m )-u0.

[0020] The correction unit rotates the Lissajous figure including the sine wave component and the cosine wave component after the center coordinates are corrected by -θ according to the following equation, and then further corrects the Lissajous figure so that the length of the major axis is consistent with the length of the minor axis, so that the first Lissajous figure approaches the second Lissajous figure:

[0021] [Equation 3]

[0022]

[0023] The geometric shape calculation unit calculates the pixel (x ) with respect to the interference image by using the sine wave component and the cosine wave component corrected by the correction unit according to the following equation:n ,y m ) corresponds to the position (x n ,y m ) at the reference height

[0024] [Equation 4]

[0025] as well as

[0026] According to the following equation, by using the phase difference To calculate the position (x n ,y m ) at a height h nm :

[0027] [Equation 5]

[0028]

[0029] Here, λ is the wavelength of the laser.

[0030] A second aspect of the present invention provides an analysis method for analyzing an interference image of an interference measurement device, wherein the interference measurement device is used to generate the interference image of the reference light and the measurement light reflected by utilizing laser irradiation on the reference surface and the surface of the measurement object, the analysis method comprising the following steps: obtaining a plurality of the interference images based on a plurality of optical path lengths between the reference surface and the surface of the measurement object from the interference measurement device; respectively calculating the sine wave component and cosine wave component of the interference signal of each pixel in the plurality of the interference images; detecting the error between a first Lissajous figure formed by the sine wave component and the cosine wave component of each pixel and an ideal second Lissajous figure; correcting the sine wave component and the cosine wave component of each pixel based on the error; and calculating the surface geometry of the measurement object based on the corrected sine wave component and the cosine wave component.

[0031] The third aspect of the present invention provides an interference measurement system, comprising: an interference measurement device; and an analysis device according to the first aspect, for analyzing a plurality of interference images captured by the interference measurement device, wherein the interference measurement device comprises: a light source unit for irradiating the surface of the measurement object with a laser; the reference surface, which is movably arranged on the optical axis of the laser; and an imaging unit for capturing the interference image of the reference light reflected at the reference surface and the measurement light reflected at the surface of the measurement object.

[0032] A fourth aspect of the present invention provides a storage medium storing a program which, when executed by a computer, causes the computer to function as the analysis apparatus according to the first aspect.

[0033] Effects of the Invention

[0034] According to the present invention, the influence of phase shift error can be conveniently reduced when analyzing the interference image of the laser interferometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A configuration example of an interferometry system 1000 and a measurement target object 10 according to the present embodiment are shown.

[0036] Figure 2 A structural example of the analysis apparatus 200 according to the present embodiment is shown.

[0037] Figure 3 An example of the operation flow of the analysis apparatus 200 according to the present embodiment is shown.

[0038] Figure 4 An example of a first Lissajous figure constructed by the error detection section 240 according to the present embodiment is shown.

[0039] Description of Reference Numerals

[0040] 10 Measurement object

[0041] 110 Light Source

[0042] 120 Optical System

[0043] 122 Magnifying Lens

[0044] 124 Collimating lens

[0045] 126 beam splitter

[0046] 128 Imaging Lens

[0047] 130 reference objects

[0048] 132 reference surface

[0049] 140 Phase Shifter

[0050] 150 Camera Department

[0051] 160 Control Department

[0052] 200 analytical equipment

[0053] 210 Acquisition Department

[0054] 220 Storage Department

[0055] 230 Computing Department

[0056] 240 Error Detection Unit

[0057] 250 Correction Department

[0058] 260 Geometry Calculation Department

[0059] 270 Output

[0060] 1000 Interferometry System DETAILED DESCRIPTION

[0061] <Configuration Example of Interference Measurement System 1000>

[0062] Figure 1 The following illustrates an example structure of an interferometry system 1000 according to this embodiment, and a measurement target object 10. Interferometry system 1000 forms a Fizeau interferometer and measures the surface geometry of measurement target object 10. Measurement target object 10 is, for example, a solid object such as a semiconductor wafer made of Si, GaAs, or GaN, a high-precision mirror, or metal. Interferometry system 1000 includes an interferometry device 100 and an analysis device 200. Interferometry device 100 includes a light source unit 110, an optical system 120, a reference object 130, a phase shifter 140, an imaging unit 150, and a control unit 160.

[0063] The light source section 110 includes a laser and irradiates the surface of the measurement target object 10 with laser light. The light source section 110 outputs laser light having a predetermined wavelength, for example. As an example, the light source section 110 is a He—Ne laser.

[0064] The optical system 120 irradiates the object 10 to be measured and the reference object 130 with laser light output from the light source section 110. The optical system 120 also forms an image of reflected light from the object 10 to be measured and the reference object 130 on the imaging section 150. The optical system 120 includes a magnifying lens 122, a collimating lens 124, a beam splitter 126, and an imaging lens 128.

[0065] The magnifying lens 122 magnifies the diameter of the laser light output from the light source unit 110. The collimating lens 124 collimates the light incident from the magnifying lens 122 and illuminates the surface of the object 10 to be measured with the collimated light. Furthermore, light reflected from the surface of the object 10 to be measured is incident on the collimating lens 124, which reduces the diameter of the reflected light and outputs it to the beam splitter 126. Here, the light reflected from the surface of the object 10 to be measured is referred to as measurement light.

[0066] Reference object 130 is disposed between collimating lens 124 and measurement target object 10, and a portion of the collimated light emitted from collimating lens 124 is reflected by reference surface 132 of reference object 130. Thus, collimating lens 124 emits the measurement light and the light reflected by reference surface 132 to beam splitter 126. Here, the light reflected by reference surface 132 is referred to as reference light.

[0067] Beam splitter 126 reflects a portion of the measurement light and reflected light emitted from collimating lens 124 toward imaging unit 150. Beam splitter 126 includes, for example, a half mirror. Imaging lens 128 forms an image of the light reflected by beam splitter 126 on imaging unit 150. Imaging lens 128 forms an interference image, resulting from the interference between the measurement light and the reference light, on imaging unit 150.

[0068] As described above, reference object 130 includes reference surface 132. Reference object 130 is, for example, a half mirror having reference surface 132 as a mirror surface. Reference surface 132 is disposed substantially perpendicular to the optical axis of the laser light output from light source unit 110. Furthermore, reference surface 132 is movably disposed on the optical axis of the laser light.

[0069] Phase shifter 140 moves reference object 130, causing reference surface 132 to move along the optical axis of the laser light. This movement of reference surface 132 along the optical axis of the laser light changes the distance between reference surface 132 and the surface of object 10 being measured, shifting the phase difference between the measurement light and the reference light. Phase shifter 140 moves reference object 130 until the phase difference between the measurement light and the reference light reaches, for example, approximately 2π or greater. Phase shifter 140, which includes, for example, a piezoelectric element, moves reference object 130 by a distance corresponding to the input control signal.

[0070] The imaging unit 150 captures an interference image of the reference light reflected by the reference surface 132 and the measurement light reflected by the surface of the object 10. The imaging unit 150 includes, for example, a camera, and captures the interference image formed by the optical system 120 in response to a control signal.

[0071] The control unit 160 controls the phase shifter 140 and the imaging unit 150 to capture multiple interference images based on multiple optical path lengths between the reference surface 132 and the surface of the object 10 being measured. For example, the control unit 160 sends a control signal to the phase shifter 140 to control the phase shifter 140, thereby moving the reference object 130 to a predetermined position. Furthermore, the control unit 160 sends a control signal to the imaging unit 150 to control the imaging unit 150, thereby capturing interference images. For example, the control unit 160 controls the phase shifter 140 and the imaging unit 150 to move the reference surface 132 by a distance corresponding to a predetermined phase shift amount, and captures an interference image each time the reference surface 132 moves. The control unit 160 includes, for example, a central processing unit (CPU).

[0072] In this manner, the interferometry apparatus 100 irradiates the reference surface 132 and the surface of the measurement target object 10 with laser light to generate an interference image of the reflected reference light and the measurement light. Figure 1 The interferometric measurement apparatus 100 of the illustrated optical system 120 is called a Fizeau interferometer, and is capable of measuring the geometric shape of the concavities and convexities on the surface of the measurement target object 10 with nanometer-level accuracy.

[0073] For such high-precision measurements, the phase difference between the measurement light and the reference light must be precisely controlled. However, the phase shift amount of phase shifter 140 may include errors due to operating errors of the piezoelectric element used to move reference object 130, as well as defects in optical system 120. In addition, environmental changes in interferometry apparatus 100 due to vibration, temperature, and air fluctuations may cause errors in the phase shift amount of phase shifter 140, making it difficult to ideally control the phase shift amount.

[0074] Conventionally, the impact of errors based on such phase shift amounts on measurement accuracy has been reduced through processes such as frequency filtering using a window function or correcting errors in the interference image by modeling the effects of the errors. However, since such processes use numerical processing using at least dozens of interference images or iterative processing using multiple parameters, they have high computational costs and may result in a local solution, making interferometry inconvenient.

[0075] Therefore, the analysis device 200 according to the present embodiment can easily perform high-precision interference measurement by analyzing ten or less interference images generated by the interference measurement device 100. The analysis device 200 will be described below.

[0076] <Structural Example of Analysis Device 200>

[0077] Figure 2The following illustrates an example structure of an analysis device 200 according to this embodiment. Analysis device 200 is, for example, a computer such as a server. It should be noted that analysis device 200 can perform at least a portion of the operations of control unit 160 of interferometry device 100. Analysis device 200 includes an acquisition unit 210, a storage unit 220, a calculation unit 230, an error detection unit 240, a correction unit 250, a geometric shape calculation unit 260, and an output unit 270.

[0078] The acquisition unit 210 acquires a plurality of interference images based on a plurality of optical path lengths between the reference surface 132 and the surface of the object 10 to be measured from the interferometry device 100. The acquisition unit 210 can acquire the interference images by connecting to the imaging unit 150 of the interferometry device 100, or alternatively, can acquire the interference images via a network or the like. Furthermore, the acquisition unit 210 can acquire the plurality of interference images from an external database or the like. In this case, the acquisition unit 210 acquires, for example, an interference image previously generated by the interferometry device 100.

[0079] The storage unit 220 stores the image data of the interference images acquired by the acquisition unit 210. The storage unit 220 preferably stores the image data of multiple interference images in association with the phase difference between the measurement light and the reference light, or the order of the interference measurement. Furthermore, the storage unit 220 may store intermediate data, calculation results, thresholds, parameters, and the like generated (or used) during the operation of the analysis device 200. Furthermore, the storage unit 220 may provide the stored data to the requesting party in response to a request from various components of the analysis device 200.

[0080] The storage unit 220 can store information about an operating system (OS) and programs used by a server or the like as the analysis device 200. Furthermore, the storage unit 220 can store various types of information, including databases referenced when executing the programs. For example, a computer such as a server can function as at least a portion of the acquisition unit 210, storage unit 220, calculation unit 230, error detection unit 240, correction unit 250, geometric shape calculation unit 260, and output unit 270 by executing the programs stored in the storage unit 220.

[0081] The storage unit 220 includes, for example, a read-only memory (ROM) for storing the basic input / output system (BIOS) of a computer, etc., and a random access memory (RAM) as a work area. Furthermore, the storage unit 220 may also include a large-capacity storage device such as a hard disk drive (HDD) and / or a solid-state drive (SSD). Furthermore, the computer may also include a graphics processing unit (GPU), etc.

[0082] The calculation unit 230 calculates the sine wave component and cosine wave component of the interference signal for each pixel in the multiple interference images. The calculation unit 230 generates an interference signal for each pixel from the multiple interference images. For example, if the interference image is image data consisting of N×M pixels, the calculation unit 230 generates N×M interference signals. The calculation unit 230 then calculates the sine wave component and cosine wave component corresponding to the frequency of the laser light for each interference signal.

[0083] The error detection unit 240 constructs a Lissajous figure based on the sine and cosine wave components calculated for each pixel and detects an error corresponding to an error in the phase shift amount. The correction unit 250 corrects the sine and cosine wave components for each pixel based on the detected error. The geometry calculation unit 260 calculates the surface geometry of the object 10 to be measured based on the corrected sine and cosine wave components. Error detection, error correction, and calculation of the surface geometry of the object 10 to be measured will be described later.

[0084] The output unit 270 outputs the calculation result of the surface geometry to a display device, etc. The output unit 270 can display numerical data and, alternatively or additionally, can schematically display the surface geometry of the object 10 to be measured. In addition, the output unit 270 can store the calculation result of the surface geometry of the object 10 to be measured in an external database, etc.

[0085] The analysis device 200 according to the present embodiment described above generates interference signals for each pixel from multiple interference images, thereby detecting and correcting errors in the phase shift amount corresponding to each pixel without requiring iterative calculations using multiple parameters. A more specific operation of the analysis device 200 will be described below.

[0086] <Operation Flow of Analysis Device 200>

[0087] Figure 3 An example of the operation flow of the analysis device 200 according to this embodiment is shown. The analysis device 200 performs Figure 3 The operations from step S310 to step S360 in FIG. 1 are used to calculate and output the surface geometry of the measurement target object 10 in which the phase shift error is corrected based on the plurality of interference images.

[0088] First, the acquisition unit 210 acquires a plurality of interference images from the interferometry device 100 (step S310). In this embodiment, an example will be described in which the acquisition unit 210 acquires K interference images from the interferometry device 100. Here, it is assumed that the interference image is image data of N×M pixels, and the image data of the interference image acquired by the acquisition unit 210 is referred to as I i (x n ,y m). Here, i=1, 2, 3, ..., K, n=1, 2, 3, ..., N, and m=1, 2, 3, ..., M.

[0089] Next, the calculation unit 230 generates an interference signal for each pixel from the plurality of interference images (step S320). For example, the calculation unit 230 generates N×M interference signals S(i) according to the following equation: n,m Each interference signal will contain K data.

[0090] [Equation 6]

[0091] S(i) n,m =I i (x n ,y m )

[0092] Next, the calculation unit 230 calculates the interference signal S(i) n,m The calculation unit 230 calculates the sine wave component I according to the following equation, for example: sin (x n ,y m ) and cosine wave component I cos (x n ,y m ).

[0093] [Equation 7]

[0094]

[0095]

[0096]

[0097] Here, δ i is the phase shift amount shifted by the phase shifter 140 when the interferometry apparatus 100 generates the i-th interference image. i is a value corresponding to the phase shift amount controlled by the control unit 160 and is treated as a known parameter in the calculation. However, as described above, δ i In addition, γ is a coefficient for normalizing the light intensity distribution of each pixel.

[0098] Then, the error detection unit 240 constructs a first Lissajous figure based on the sine wave component and cosine wave component of each pixel, and detects the error between the first Lissajous figure and the ideal second Lissajous figure (step S340). The first Lissajous figure is a figure where u=I is plotted on the uv plane. cos (x n ,y m ) and v=Isin (x n ,y m ) graph. i In the case of ideal interferometry, the Lissajous figure will be with radius r = (u 2 +v 2 ) 1 / 2 Here, the error detection section 240 uses an ideal Lissajous figure, which is a circle having a predetermined radius, as the second Lissajous figure.

[0099] Figure 4 An example of a first Lissajous figure constructed by the error detection section 240 according to the present embodiment is shown. Figure 4 An example of a first Lissajous figure is shown, in which u=I is plotted with the horizontal axis being the u axis and the vertical axis being the v axis. cos (x n ,y m ) and v=I sin (x n ,y m ). When the error is superimposed on δ i In the above case, Figure 4 As shown, the first Lissajous figure is an ellipse.

[0100] The error detection unit 240 extracts information about the first Lissajous figure having an elliptical shape constructed in this manner. The error detection unit 240 extracts parameters of the ellipse as information about the first Lissajous figure by fitting the first Lissajous figure to the ellipse using, for example, the least squares method. In this case, as an example, the information about the first Lissajous figure includes the center coordinates (u0, v0) of the ellipse, the major axis a, and the coordinates of the ellipse. x 、Short axis a y As described above, when the error detection unit 240 plots an elliptical shape as the first Lissajous figure, the difference between the elliptical shape and the circular shape as the second Lissajous figure is an error corresponding to the error in the phase shift amount.

[0101] Then, the correction unit 250 corrects the sine wave component and cosine wave component of each pixel based on the detected error (step S350). The correction unit 250 corrects the first Lissajous figure to be close to the second Lissajous figure by correcting the center coordinates and ellipticity of the first Lissajous figure based on the sine wave component and cosine wave component of each pixel. The correction unit 250 corrects the sine wave component and cosine wave component according to the following equation, for example, so that the center coordinates are offset toward the origin. Here, I sin '(x n ,y m ) and I cos '(x n ,y m) are the sine wave components and cosine wave components after correction of the center coordinates.

[0102] [Equation 8]

[0103] I′ sin (x n ,y m )=I sin (x n ,y m )-v0

[0104] I′ cos (x n ,y m )=I cos (x n ,y m )-u0

[0105] Furthermore, the correction unit 250 corrects the ellipticity by correcting the sine wave component and the cosine wave component. For example, the correction unit 250 rotates the ellipse by -θ so that the angle θ becomes 0, and then corrects the amplitude values of the sine wave component and the cosine wave component so that the length of the major axis and the length of the minor axis are consistent, and returns the angle to θ. As an example, the correction unit 250 corrects I according to the following equation: sin '(x n ,y m ) and I cos '(x n ,y m ). Here, I sin ”(x n ,y m ) and I cos ”(x n ,y m ) are the sine wave component and cosine wave component after the center coordinates are corrected. In addition, R(θ) is the rotation matrix.

[0106] [Equation 9]

[0107]

[0108] Next, the geometric shape calculation unit 260 calculates the corrected sine wave component I sin ”(x n ,y m ) and cosine wave component I cos ”(x n ,y m ) to calculate the surface geometry of the object 10 to be measured (step S360). The geometry calculation unit 260 calculates the pixel (x n ,y m) corresponds to the position (x n ,y m ) at the reference height

[0109] [Equation 10]

[0110]

[0111] The geometric shape calculation unit 260 calculates the phase difference according to the following equation: To calculate the position (x n ,y m ) at a height h nm Here, λ is the wavelength of the laser light from the light source unit 110 .

[0112] [Equation 11]

[0113]

[0114] As described above, the analysis device 200 according to this embodiment can calculate the surface geometry of the object 10 to be measured by correcting the phase shift error of the phase shifter 140. The analysis device 200 detects and corrects the phase shift error based on the sine wave component and cosine wave component contained in the interference signal of each pixel in the interference image generated by the interferometric measurement device 100. Here, even if there are approximately ten or fewer measurement points, the sine wave component and cosine wave component of the interference signal can be fully calculated. In other words, the analysis device 200 can detect and correct the phase shift error based on approximately ten or fewer interference images.

[0115] Furthermore, the analysis device 200 can detect and correct phase shift errors without using iterative processing using multiple parameters, etc. Therefore, the analysis device 200 can reduce computational costs and easily perform high-precision interferometry.

[0116] It should be noted that while the analysis device 200 according to this embodiment analyzes an interference image generated by an interferometer 100 including a Fizeau interferometer, the present invention is not limited thereto. The analysis device 200 can also analyze the interference image using an interferometer 100 including another type of interferometer, as long as the interferometer generates a phase shift error. For example, the interferometer 100 may include a Twyman-Green interferometer. Furthermore, the interferometer 100 is not limited to an interferometer that shifts the phase of the reference surface 132 and may also include an interferometer that shifts the polarization phase of the laser light.

[0117] The present invention has been described based on these exemplary embodiments. The technical scope of the present invention is not limited to the scope described in the above embodiments, and various changes and modifications can be made within the scope of the present invention. For example, all or part of the device can be configured to be functionally or physically distributed and integrated in arbitrary units. In addition, new exemplary embodiments generated by any combination of these exemplary embodiments are included in the exemplary embodiments of the present invention. The effects of the new embodiments resulting from this combination also have the effects of the original embodiments.

Claims

1. An analysis device for analyzing an interference image of an interferometer measurement device, the interferometer measurement device generating the interference image of reference light and measurement light reflected by irradiating a reference surface and a surface of an object to be measured with laser light, the analysis device comprising: an acquiring unit configured to acquire, from the interferometric measurement device, a plurality of the interference images based on a plurality of optical path lengths between the reference surface and the surface of the object to be measured; a calculation unit, configured to respectively calculate the sine wave component and the cosine wave component of the interference signal of each pixel in the plurality of interference images; an error detection unit configured to detect an error between a first Lissajous figure formed by the sine wave component and the cosine wave component of each pixel and an ideal second Lissajous figure; a correction unit configured to correct the sine wave component and the cosine wave component of each pixel based on the error; as well as A geometric shape calculation unit is configured to calculate a surface geometric shape of the object to be measured based on the corrected sine wave component and the cosine wave component.

2. The analysis device according to claim 1, wherein The error detecting section uses a circle having a predetermined radius as the second Lissajous figure, and The correction unit corrects the first Lissajous figure to be close to the second Lissajous figure by correcting the center coordinates and the ellipticity of the first Lissajous figure based on the sine wave component and the cosine wave component of each pixel.

3. The analysis device according to claim 1, wherein The error detection unit extracts information of the first Lissajous figure having an elliptical shape from the sine wave component and the cosine wave component of the interference signal of each pixel in the plurality of interference images.

4. The analysis device according to claim 1, wherein The calculation unit calculates the sine wave component as I according to the following equation: sin (x n ,y m ), and the cosine wave component is calculated as I cos (x n ,y m ): Where: I i (x n ,y m ) shows image data of N×M pixels of K interference images, where i=1, 2, 3, ..., K, n=1, 2, 3, ..., N, and m=1, 2, 3, ..., M, and δ i is a phase shift amount corresponding to the optical path length between the reference surface and the surface of the object to be measured when the i-th interference image is generated.

5. The analysis device according to claim 4, wherein The error detection unit plots u=I with the horizontal axis being the u axis and the vertical axis being the v axis. cos (x n ,y m ) and v=I sin (x n ,y m ), extracting information of the first Lissajous figure having an elliptical shape, the information including the center coordinates (u0, v0) of the ellipse, the major axis a x 、Short axis a y , and the angle θ of the axis, and The correction unit corrects the sine wave component and the cosine wave component using the following equation so that the first Lissajous figure approaches the second Lissajous figure whose central coordinate is the origin: I′ sin (x n ,y m )=I sin (x n ,y m )-v0 I′ cos (x n ,y m )=I cos (x n ,y m )-u0, The corrected sine wave component and cosine wave component are set to I′ sin (x n ,y m ) and I′ cos (x n ,y m ).

6. The analysis device according to claim 5, wherein The correction unit rotates the Lissajous figure including the sine wave component and the cosine wave component after the center coordinates are corrected by -θ according to the following equation, and then further corrects the Lissajous figure so that the length of the major axis is consistent with the length of the minor axis, so that the first Lissajous figure approaches the second Lissajous figure: Among them, I′ will be further corrected sin (x n ,y m ) and I′ cos (x n ,y m The sine wave component and the cosine wave component after ) are set to I″ sin (x n ,y m ) and I″ cos (x n ,y m ), and set the rotation matrix of rotation θ to R(θ).

7. The analysis device according to claim 6, wherein The geometric shape calculation unit: According to the following equation, the pixel (x n ,y m ) corresponds to the position (x n ,y m ) at the reference height as well as According to the following equation, by using the phase difference To calculate the position (x n ,y m ) at a height h n,m : Here, λ is the wavelength of the laser.

8. An analysis method for analyzing an interference image of an interferometer measuring device for generating the interference image of reference light and measurement light reflected by irradiating a reference surface and a surface of an object to be measured with laser light, the analysis method comprising the following steps: acquiring, from the interferometry device, a plurality of the interference images based on a plurality of optical path lengths between the reference surface and the surface of the measurement target object; respectively calculating the sine wave component and the cosine wave component of the interference signal of each pixel in the plurality of interference images; detecting an error between a first Lissajous figure formed by the sine wave component and the cosine wave component of each pixel and an ideal second Lissajous figure; correcting the sine wave component and the cosine wave component of each pixel based on the error; as well as The surface geometry of the measurement target object is calculated based on the corrected sine wave component and the cosine wave component.

9. An interferometry system comprising: interferometry equipment; as well as The analysis device according to any one of claims 1 to 7, configured to analyze a plurality of the interference images captured by the interference measurement device, Wherein, the interferometric measurement device comprises: a light source unit for irradiating the surface of the object to be measured with laser light; The reference surface is movably disposed on the optical axis of the laser; and The imaging unit is configured to capture the interference image of the reference light reflected by the reference surface and the measurement light reflected by the surface of the object to be measured. 10 . A storage medium storing a program which, when executed by a computer, causes the computer to function as the analysis apparatus according to claim 1 .

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