Determination program, determination system, determination program recording medium, determination device, microstructure manufacturing system, method for determination, and method for manufacturing microstructure

Abstract

To provide a determination program, a determination system, a determination program recording medium, a determination device, a microstructure manufacturing system, a method for determination, and a method for manufacturing a microstructure for determining the shape of a microstructure having birefringence properties.SOLUTION: A determination program (2) for determining the shape of a microstructure (9) having birefringence properties causes a computer to function as input means (11) for inputting phase difference information concerning a phase difference between a fast axis and a slow axis of zero-order light obtained by transmitting or reflecting circularly polarized light, elliptically polarized light, or linearly polarized light through the microstructure (9), and as structure determination means (12) for determining the shape of the microstructure (9) on the basis of the phase difference information input by the input means (11).SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a judgment program, a judgment system, a judgment program recording medium, a judgment device for judging the shape of a microstructure having birefringence properties, and a microstructure manufacturing system, a judgment method, and a microstructure manufacturing method using the same. [Background technology]

[0002] Nanophotonics, which controls light by forming nano-sized structures on the surfaces of resins, glass, and metals, is a new optical technology whose range of applications, including displays, sensors, and biotechnology, has been expanding widely across industry in recent years. As of 2023, waveguides for AR glasses are an optical component expected to see significant growth within nanophotonics devices. The method of configuring the input and output couplers of waveguides for AR glasses using diffraction gratings formed by nanoimprinting is more suitable for mass production than other methods, and is considered essential for making AR glasses into affordable products for general consumers.

[0003] In the waveguide of AR glasses, as shown in Figure 1(a), light carrying a digital image output from a small display is diffracted by a diffraction grating on a glass substrate called the input coupler, absorbed into the glass substrate, propagates through the glass substrate by total reflection, reaches a diffraction grating called the output coupler, and is emitted from the glass substrate to the outside, where the transferred digital image is transmitted to the human retina. Alternatively, as shown in Figure 1(b), a diffraction grating called a pupil expander, which changes the propagation direction of light, can be used between the input and output couplers to magnify the image and then re-enlarge it at the output coupler. The diffraction gratings of the input coupler, pupil expander, and output coupler are extended in different directions, at 0°, 45°, and 90°, respectively. In addition, tilted shapes are sometimes used for these diffraction gratings, especially for the input coupler, to improve diffraction efficiency.

[0004] In the above-mentioned wave guides that transmit images, distortions or defects in the input / output diffraction grating patterns and irregularities in the flatness of the transfer section lead to image distortion and reduced resolution.Furthermore, variations in the thickness of the diffraction grating and variations in the inclination of the inclined type cause variations in diffraction efficiency, resulting in variations and unevenness in the brightness of the image.

[0005] Therefore, in order to produce optical waveguides with uniform and reproducible performance, it is essential to have a device that can detect and manage variations and fluctuations in the processing size, and it is most desirable to inspect all products using a device that can inspect products at high speed.

[0006] Many techniques have been published for measuring the phase difference of birefringent materials. For example, there is a method for observing the wavelength dispersion of the phase difference from the Mueller matrix obtained by spectroscopic ellipsometry measurement as shown in Figure 2 (Patent Document 1).

[0007] Another method, as shown in FIG. 3, involves circularly polarizing light from a light source 110 using a circular polarization filter 124, transmitting the light through a birefringent material to be measured, and measuring a two-dimensional distribution image of the phase difference and the direction of its principal axis of the transmitted light (Patent Documents 2 and 3). In this case, as shown in FIG. 3(a), the light reaching the image sensor 121 via a linear polarization filter 125 with a rotation drive mechanism placed in front of the image sensor 121 is measured for each rotation angle of the linear polarization filter. Alternatively, as shown in FIG. 3(b), a polarization image sensor 122 may be used in which polarization filters (nano-sized photonic crystals or wire-grid polarizers are used as polarization filters) with different principal axis directions by 45° are placed for each pixel of the image sensor. In this case, the linear polarization filter 125 with a rotation drive mechanism can be omitted.

[0008] Although there are methods for measuring the phase difference of birefringent materials, there is currently no standard inspection method for determining the shape of fine structures such as diffraction gratings in optical waveguides. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2005-308612 [Patent Document 2] Patent No. 4974543 [Patent Document 3] Patent No. 7227235 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0010] It is difficult to inspect processing precision with a pitch of 350nm to 500nm using optical measurements, while measuring the entire surface of elements within a wafer using a scanning electron microscope is not practical due to the measurement time required. One example of a device for inspecting diffraction gratings is TeraNova's Fourier Scatterometry, but it determines the intensity of the diffraction order at each incident angle for a specified polarization (TE or TM) by scanning the incident angle on the sample surface, and measures elements one by one, so there are limits to the high speed required for inspecting large quantities of products.

[0011] Therefore, the present invention aims to provide a new judgment program, judgment system, judgment program recording medium, judgment device, microstructure manufacturing system, judgment method, and microstructure manufacturing method for judging the shape of a microstructure having birefringence properties. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, the judgment program of the present invention is a judgment program for judging the shape of a microstructure having birefringence properties, and is characterized in that it causes a computer to function as an input means for inputting phase difference information regarding the phase difference between the fast axis and slow axis of zero-order light obtained by transmitting or reflecting circularly polarized light, elliptically polarized light, or linearly polarized light through the microstructure, and a structure judgment means for judging the shape of the microstructure based on the phase difference information input by the input means.

[0013] In this case, the structure determination means may determine the shape of the microstructure based on the phase difference information input by the input means and a lookup table showing the relationship between phase difference and shape that has been stored in advance.

[0014] The structure determination means may determine the shape of the microstructure based on AI that has previously learned the relationship between phase difference and shape.

[0015] The structure determination means may determine the shape of the fine structure by a statistical estimation method based on a relationship between a phase difference and a shape that is stored in advance.

[0016] The structure determination means may determine the shape of the fine structure based on a pre-stored threshold value of phase difference.

[0017] The structure determination means may determine the shape of the microstructure based on a change in phase difference between a plurality of microstructures input by an input means.

[0018] Furthermore, the computer may function as a phase difference information detection means that detects the phase difference information and inputs the phase difference information to the input means.

[0019] The phase difference information may be a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

[0020] The phase difference information may be image data detected by a polarization camera.

[0021] The phase difference information may include information on the phase difference between the fast axis and the slow axis of the zeroth-order light of a plurality of wavelengths in a wavelength range in which the diffraction efficiency of at least one of −1st-order diffraction and 1st-order diffraction is 10% or less.Moreover, it is preferable that the phase difference information includes information on the phase difference between the fast axis and the slow axis of the zeroth-order light of a wavelength in a wavelength range in which the diffraction efficiency of the zeroth-order diffraction is 50% or more and 90% or less.

[0022] The phase difference information may include a phase difference between the fast axis and the slow axis of the zero-order light transmitted through or reflected by the microstructure at a plurality of different angles of incidence.

[0023] The structure determination means may calculate the shape of the microstructure.

[0024] The structure determining means may determine whether the shape of the microstructure is good or bad.

[0025] The microstructure may be any one of a diffraction grating, a phase difference element, and a metalens.

[0026] The determination system of the present invention is characterized by comprising hardware in which the determination program is installed.

[0027] A determination program recording medium according to the present invention is characterized in that it is a recording medium on which the determination program is recorded.

[0028] In addition, the determination device of the present invention is a determination device for determining the shape of a microstructure having birefringence properties, and is characterized by comprising: an irradiation unit that irradiates the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light; a phase difference information detection means having a detection unit that detects phase difference information regarding the phase difference between the fast axis and slow axis of the zero-order light irradiated from the irradiation unit and transmitted through or reflected by the microstructure; and a structure determination means that determines the shape of the microstructure based on the phase difference information detected by the detection unit.

[0029] In this case, the structure determination means may determine the shape of the microstructure based on the phase difference information detected by the phase difference information detection means and a lookup table showing the relationship between phase difference and shape that has been stored in advance.

[0030] The structure determination means may determine the shape of the microstructure based on AI that has previously learned the relationship between phase difference and shape.

[0031] The structure determination means may determine the shape of the fine structure by a statistical estimation method based on a relationship between a phase difference and a shape that is stored in advance.

[0032] The structure determination means may determine the shape of the fine structure based on a pre-stored threshold value of phase difference.

[0033] The structure determination means may determine the shape of the microstructure based on a change in phase difference between a plurality of microstructures detected by a phase difference information detection means.

[0034] The phase difference information detecting means may detect, as the phase difference information, a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

[0035] The phase difference information detecting means may include a polarization camera that detects detected image data or the phase difference calculated from the image data as the phase difference information.

[0036] The irradiation unit may irradiate light of multiple wavelengths in a wavelength range in which the diffraction efficiency of at least one of −1st order diffraction and 1st order diffraction for the microstructure is 10% or less. Preferably, the irradiation unit can irradiate light of wavelengths in a wavelength range in which the diffraction efficiency of 0th order diffraction for the microstructure is 50% or more and 90% or less.

[0037] The irradiation unit may irradiate the microstructure with light at a plurality of different angles of incidence.

[0038] The structure determination means may calculate the shape of the microstructure.

[0039] The structure determining means may determine whether the shape of the microstructure is good or bad.

[0040] It is also preferable to provide a moving means for moving the fine structure to a position where the zero-order light can be detected by the phase difference information detecting means.

[0041] The microstructure may be any one of a diffraction grating, a phase difference element, and a metalens.

[0042] The present invention also provides a microstructure manufacturing system comprising a microstructure manufacturing device for manufacturing a microstructure having birefringence properties, and a determination device for determining the shape of the microstructure.

[0043] Here, the apparatus may further comprise a classification means for classifying the fine structures based on the result of the determination of the shape of the fine structures by the determination device.

[0044] In addition, the determination method of the present invention is a determination method for determining the shape of a microstructure having birefringence properties, and is characterized by having a phase difference information detection process of irradiating the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and detecting phase difference information regarding the phase difference between the fast axis and slow axis of zero-order light transmitted through or reflected by the microstructure, and a structure determination process of determining the shape of the microstructure based on the phase difference information detected in the phase difference information detection process.

[0045] Here, the structure determination step may determine the shape of the microstructure based on the phase difference information detected in the phase difference information detection step and a lookup table showing the relationship between phase difference and shape.

[0046] The structure determination step may determine the shape of the microstructure based on AI that has learned the relationship between phase difference and shape.

[0047] The structure determination step may determine the shape of the fine structure by a statistical estimation method based on the relationship between phase difference and shape.

[0048] The structure determination step may determine the shape of the fine structure based on a threshold value of a phase difference.

[0049] The structure determination step may determine the shape of the microstructure based on a change in phase difference between a plurality of microstructures detected in the phase difference information detection step.

[0050] The phase difference information detecting step may detect, as the phase difference information, a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

[0051] The phase difference information detecting step may detect, as the phase difference information, image data detected by a polarization camera or the phase difference calculated from the image data.

[0052] The phase difference information detecting step may be a step of irradiating light of a plurality of wavelengths in a wavelength range in which the diffraction efficiency of at least one of −1st order diffraction and 1st order diffraction for the microstructure is 10% or less.Furthermore, the phase difference information detecting step is preferably a step of irradiating light of a wavelength in a wavelength range in which the diffraction efficiency of 0th order diffraction for the microstructure is 50% or more and 90% or less.

[0053] The phase difference information detecting step may also include irradiating the microstructure with light at a plurality of different angles of incidence.

[0054] The structure determination step may also include calculating the shape of the microstructure.

[0055] The structure evaluation step may be a step of evaluating the quality of the shape of the microstructure.

[0056] The microstructure is any one of a diffraction grating, a phase difference element, and a metalens.

[0057] In addition, the microstructure manufacturing method of the present invention is characterized by having a microstructure manufacturing process for manufacturing a microstructure having birefringence properties, and a determination process using the determination method for determining the shape of the microstructure.

[0058] Here, the method may include a classification step of classifying the fine structures based on the result of the determination of the shape of the fine structures in the determination step. [Effects of the Invention]

[0059] The determination program, determination system, determination program recording medium, determination device, microstructure manufacturing system, determination method, and microstructure manufacturing method of the present invention can rapidly determine the shape of a microstructure having birefringence properties. [Brief explanation of the drawings]

[0060] [Figure 1] 10A and 10B are diagrams for explaining the pattern of a waveguide for AR glasses. [Figure 2] FIG. 1 is a diagram illustrating wavelength dispersion of the Mueller matrix and phase difference obtained by (a) spectroscopic ellipsometer and (b) spectroscopic ellipsometry measurement. [Figure 3] FIG. 2 is a diagram illustrating an example of a phase difference information detecting means of the present invention. [Figure 4] FIG. 1 is a configuration diagram of a determination system according to the present invention. [Figure 5] 3 is a flowchart showing steps of a determination program of the present invention. [Figure 6] FIG. 1 is a conceptual diagram showing the change in function of a tilted grating depending on the incident wavelength. [Figure 7] FIG. 10 is a diagram showing the relationship between incident wavelength and diffraction efficiency. [Figure 8] FIG. 1 is a diagram showing the shape of the microstructure of Example 1. [Figure 9] 1A is a graph showing the wavelength dependency of diffraction efficiency, the wavelength dependency of retardation, and the line width dependency of diffraction efficiency in Example 1. FIG. [Figure 10] 10A and 10B are diagrams illustrating the deformation of the replica mold and the change in shape of the molded product in Example 2. [Figure 11] FIG. 10 shows the measured dependence of retardation on the change in width of the microstructure of Example 2. [Figure 12] 10A is a diagram showing (a) the measurement method, (b) the wavelength dependency of the diffraction efficiency, and (c) the wavelength dependency of the retardation of zero-order light with respect to the deformation of the replica mold in Example 3. FIG. [Figure 13] 10A is a diagram showing the inclination of an inclined grating in Example 4, and FIG. 10B is a diagram showing the wavelength dependence of the diffraction efficiency with respect to the change in the inclination. [Figure 14] 10A shows the measurement method, and FIGS. 10B to 10D show the wavelength dependence of diffraction efficiency with respect to the angle of incidence in Example 4. FIG. [Figure 15] FIG. 10 is a diagram showing the wavelength dependency of retardation with respect to the change in incident angle for each tilt of the grating in Example 4. [Figure 16] FIG. 10 is a diagram showing the relationship between retardation and grating tilt α in Example 4. [Figure 17] 10A and 10B are diagrams showing (a) and (c) measurement methods, and (b) and (d) wavelength dependence of retardation in Example 5. [Figure 18] (a) Measurement method of Example 6, (b) -10°, (c) 0°, (d) 10° incident angle, and (c) wavelength dependence of diffraction efficiency. [Figure 19] FIG. 10 is a graph showing the wavelength dependence of retardation in the microstructure of Example 6 at incident angles of −10°, 0°, and 10°. [Figure 20] FIG. 13 is a diagram for explaining a measurement method according to a seventh embodiment. [Figure 21] FIG. 13 is a diagram for explaining another measurement method according to the seventh embodiment. [Figure 22] FIG. 13 is a diagram for explaining steps of the structure determination configuration of the eighth embodiment. [Figure 23] FIG. 13 is a diagram for explaining steps of the structure determination configuration of the ninth embodiment. [Figure 24] FIG. 1 is a diagram for explaining an outline of the measurement in the present invention while diagrammatically showing data obtained at each step of the structure determination. [Figure 25] FIG. 20 is a diagram illustrating a reflection-type measurement method in Example 12. [Figure 26] 12A and 12B are cross-sectional views showing the structure of a mold for (a) an SiO2 pattern and (b) an Si pattern on a Si substrate in Example 12. [Figure 27] 12A and 12B are diagrams showing the diffraction efficiency of reflected light from an SiO 2 pattern on an Si substrate and an Si pattern on an Si substrate, respectively, in Example 12. DETAILED DESCRIPTION OF THE INVENTION

[0061] The following describes a determination system 1 of the present invention and a determination program 2 that can be used in the determination system 1. Here, the determination program 2 refers to so-called software. The determination system 1 refers to hardware such as a computer in which the determination program 2 is installed and its peripheral devices. Figure 4 is a block diagram that schematically shows the electrical configuration of the determination system 1 in which the determination program 2 of the present invention is installed.

[0062] The determination system 1 is for determining the shape of a microstructure having birefringence properties based on phase difference information input by an input means. In this specification, a microstructure having birefringence properties refers to, for example, a structure consisting of multiple convex portions that are anisotropic in a planar view. Examples of such microstructures include diffraction gratings, phase difference elements, metasurfaces, and metalenses. In this specification, determining the shape refers to calculating the shape of the microstructure and determining whether the shape is good or bad.

[0063] Furthermore, in this specification, phase difference information refers to information regarding the phase difference between the fast axis and slow axis of zero-order light obtained by transmitting or reflecting circularly polarized light, elliptically polarized light, or linearly polarized light of a specific wavelength through a microstructure. The measurement range of the phase difference information may be a single point on the microstructure, a linear distribution, or a two-dimensional distribution within the plane. Furthermore, the phase difference information may not only be information regarding the phase difference of light of a specific wavelength itself, but also information that serves as the basis for calculating the phase difference. For example, the phase difference information may be a Mueller matrix obtained by spectroscopic ellipsometry measurement to calculate the phase difference. A spectroscopic ellipsometer or the like can be used for spectroscopic ellipsometry measurement. Furthermore, the phase difference information may be image data obtained by measuring the phase difference with a polarization camera.

[0064] Furthermore, the phase difference information preferably includes information about wavelengths in a wavelength range where at least one of −1st-order diffraction and 1st-order diffraction does not occur, more preferably information about the phase difference between the fast axis and the slow axis of 0th-order light of multiple wavelengths. Note that the wavelength range where at least one of −1st-order diffraction and 1st-order diffraction does not occur means a wavelength range where the diffraction efficiency of at least one of −1st-order diffraction and 1st-order diffraction is 10% or less, preferably 5% or less.

[0065] Furthermore, the microstructure has an intermediate wavelength region between the wavelength region where it functions as a diffraction grating and the wavelength region where it functions as a phase difference element, where the phase difference of the zero-order light changes rapidly. This wavelength region is sensitive to changes in the shape of the microstructure. Therefore, it is preferable that the phase difference information includes information about the phase difference of the zero-order light in the intermediate wavelength region between the wavelength region where the microstructure functions as a diffraction grating and the wavelength region where it functions as a phase difference element. The intermediate wavelength region corresponds to a wavelength region in which the diffraction efficiency of the zero-order diffracted light for the microstructure is at least 50%, preferably 60% or more, and 90% or less, preferably 80% or less.

[0066] The hardware of the computer and its peripheral devices used in the determination system 1 is mainly composed of a CPU 11, a ROM 12, a RAM 13, a storage device 14, an input device 16, a display device 17, an interface, etc., as shown in FIG.

[0067] The CPU 11 is a central processing unit that controls the overall determination system 1, and is used to execute various steps shown in the flowchart of Fig. 5 based on the determination program 2. Information (data) determined by the CPU 11 is stored in a RAM 13, a storage device 14, etc., which will be described later. The ROM 12 is a non-volatile memory that stores the BIOS executed by the CPU 11, etc. The RAM 13 is a volatile memory that temporarily stores information (data) required for the activated determination program 2 and various steps of the determination program 2 executed by the CPU 11, information determined in various steps, etc.

[0068] The interface is used to connect the CPU 11 to external devices such as the ROM 12, RAM 13, storage device 14, input device 16, display device 17, scanner, printer, tablet, etc., via wire or wireless.

[0069] The storage device 14 refers to a rewritable nonvolatile memory such as a hard disk drive (HDD) or a solid state drive (SSD), and stores the determination program 2, the database 21, etc. The storage device 14 may also store the determination program 2, information (data) required for various steps of the determination program 2 executed by the CPU 11, information determined in various steps, etc. Although not shown, the storage device 14 may also store an operating system (OS) such as Windows, or an interpreter such as Java or JRuby. The storage device 14 may be built into the computer or may be located on an external server. Using an external server allows multiple operators to use the determination program 2 on multiple PCs.

[0070] The determination system 1 executes each step shown in the flowchart of Fig. 5 in accordance with the determination program 2. Details of each step will be described later.

[0071] The database 21 stores various types of information used by the judgment system 1 and judgment program 2 of the present invention. For example, the database 21 stores a lookup table showing the relationship between phase difference and shape, information showing the relationship between phase difference and the shape of a microstructure used in statistical estimation methods such as principal component analysis and Wiener estimation, information obtained by learning the relationship between phase difference and the shape of a microstructure using AI, and information on the phase difference threshold value used to determine the quality of the shape of a microstructure. Here, the relationship between phase difference and the shape of a microstructure may be not only measured but also calculated using optical simulation or the like. Furthermore, an operator can register information not registered in the database 21 in the database 21 in advance. The database 21 may be dedicated to the judgment program 2 or may be shared with the database 21 of other software.

[0072] The input device 16 corresponds to, for example, a keyboard, a mouse, etc., and is used to input instructions from the worker to the determination system 1. The display device 17 has a screen, and in accordance with signals from the CPU 11, displays and outputs a work screen (hereinafter referred to as a work screen) in the determination system 1 and the work status on the work screen, etc., and corresponds to, for example, a liquid crystal display, etc.

[0073] Next, each step of functioning the determination system 1 of the present invention will be described with reference to the flowchart in FIG. 5. The determination system 1 executes each step in accordance with the determination program 2. The determination program 2 causes the computer of the determination system 1 to execute an input step, a structure determination step, a phase difference calculation step, etc. In this way, the determination program 2 causes the computer to function as an input means, a structure determination means, a phase information detection means, etc. When the determination program 2 is started, the CPU 11 starts executing each of these steps based on instructions from an operator or automatically. At each step, a work screen can also be displayed on a display device.

[0074] <Input step S1> The input step is a step of causing the computer to function as an input means for inputting phase difference information relating to the phase difference between the fast axis and the slow axis of zero-order light obtained by transmitting through or reflecting from a microstructure. In the input step, an operator acquires phase difference information in advance and inputs the phase difference information into hardware such as a computer via the input device 16 or the like. Then, based on an instruction from the operator, the CPU 11 determines that the input phase difference information is the phase difference information of the microstructure whose shape is to be determined.

[0075] Furthermore, the input step can also automatically input the phase difference information into hardware such as a computer without relying on an operator, using a phase difference information detection means that detects phase difference information and inputs the phase difference information into an input means. In this case, the input step inputs the phase difference information into hardware such as a computer via an interface or the like that is connected to the phase difference information detection means by wire or wirelessly. Then, the CPU 11 determines that the phase difference information input from the phase difference information detection means is phase difference information of the microstructure whose shape is to be determined.

[0076] The phase difference information input in the input step preferably includes a wavelength in a wavelength range where at least one of −1st-order diffraction and 1st-order diffraction does not occur, preferably a phase difference between the fast axis and the slow axis of zeroth-order light of multiple wavelengths. The wavelength range where at least one of −1st-order diffraction and 1st-order diffraction does not occur refers to a wavelength range where the diffraction efficiency of at least one of −1st-order diffraction and 1st-order diffraction is 10% or less, preferably 5% or less. The phase difference information preferably includes a phase difference between the fast axis and the slow axis of zeroth-order light transmitted through or reflected by the microstructure at multiple different incident angles.

[0077] <Phase difference information detection step S0> When the phase difference information is automatically input to hardware such as a computer using a phase difference information detection means, the determination program 2 causes the computer of the determination system 1 to execute a phase difference information detection step before the input step. That is, the phase difference information detection step is a step of detecting phase difference information and causing the computer to function as a phase difference information detection means that detects phase difference information and inputs the phase difference information to the input means. In the phase difference information detection step, for example, a spectroscopic ellipsometer, a polarization camera, or the like is used to detect phase difference information relating to the phase difference between the fast axis and the slow axis of zero-order light obtained by transmitting or reflecting on a microstructure. Then, the CPU 11 transmits the detected phase difference information to the input means via a wired or wireless connection.

[0078] The phase difference information detected by the phase difference information detecting means may be a Mueller matrix obtained by spectroscopic ellipsometry measurement or a phase difference calculated from the Mueller matrix. In this case, the phase difference information detecting means may be a spectroscopic ellipsometer or the like capable of spectroscopic ellipsometry measurement. Furthermore, the phase difference information detected by the phase difference information detecting means may be image data detected by a polarization camera.

[0079] <Structure determination step S2> The structure determination step is a step in which the computer functions as a structure determination means for determining the shape of a microstructure based on the phase difference information input by the input means. Here, we explain the principle behind determining the shape of a microstructure (structure determination). A periodic line-and-space pattern acts as a diffraction grating when the wavelength of incident light is approximately the same as the pattern pitch. On the other hand, if the wavelength of the incident light is sufficiently larger than the pattern pitch, diffraction does not occur and the incident light is transmitted as zero-order light. In this case, a difference in the propagation speed of light occurs between the direction parallel to the pattern axis (fast axis) and the direction perpendicular to the pattern axis (slow axis). This causes a birefringence phenomenon in which the delay of the slow axis relative to the fast axis occurs as a phase difference of light. The phase difference of birefringent materials can be measured using ellipsometry. It is also known that the two-dimensional distribution of phase difference can be measured using a commercially available polarization camera.

[0080] Figure 6 shows the microstructure of an AR optical waveguide that functions as a diffraction grating for visible light. The diffraction grating is a tilted line-and-space pattern with a refractive index of 1.9, a pattern pitch of 440 nm, a pattern width of 220 nm, and a tilt angle of 60°. When incident light of different wavelengths is applied to this diffraction grating, for visible light of 550 nm, the -1st-order diffracted light is strongly transmitted, as shown in Figure 6(a). On the other hand, when near-infrared light with a wavelength significantly longer than the pattern pitch is incident, no diffraction occurs and the 0th-order light is transmitted, as shown in Figure 6(b). Figure 7(a) shows the relationship between incident wavelength and diffraction efficiency calculated by electromagnetic field simulation using the RCWA method. For incident wavelengths shorter than 660 nm, the diffraction efficiency for the -1st-order diffracted light is significant, but for incident wavelengths above 660 nm, there is no diffraction and almost all light is transmitted as 0th-order light. Figure 7(b) shows the phase difference of birefringence versus incident wavelength calculated by electromagnetic field simulation using the RCWA method. The phase difference in the direction perpendicular to the line direction can be reliably measured using zero-order light transmitted at wavelengths above 660 nm. Between wavelength region A, where the structure functions as a diffraction grating, and wavelength region B, where the structure functions as a retardation plate, there is an intermediate wavelength region C, where the phase difference of the zero-order light changes rapidly. While wavelength region C is not suitable for use as a retardation plate, its sensitivity to structural changes can be utilized for the purpose of this invention, which is the evaluation of diffraction grating processing, as described below. Therefore, it is preferable for the phase difference information to include information on the phase difference of the zero-order light in the intermediate wavelength region between the wavelength region where the microstructure functions as a diffraction grating and the wavelength region where the microstructure functions as a retardation element. The intermediate wavelength region generally corresponds to the wavelength region where the diffraction efficiency of the zero-order diffracted light changes rapidly from 50% to 90% or from 60% to 80%.

[0081] Unlike measurements of birefringent materials or retardation plates, the purpose of structural evaluation is to detect slight variations in the shape of the diffraction grating. Therefore, rather than measuring wavelengths within the operating range of a normal retardation plate, the phase difference of the zeroth-order transmitted light is measured at a wavelength close to the diffraction conditions that are more sensitive to shape changes, or under conditions where diffraction conditions are occurring. In addition, measurements are taken by selecting multiple wavelengths and angles of incidence of the measurement light, and the results are referenced to a lookup table, etc., previously measured or calculated by electromagnetic field simulation, to detect variations in the processed shape from the phase difference.

[0082] Based on the above principle, in the structure determination step, the shape of the microstructure is determined based on the phase difference information input by the input means and pre-stored comparative phase difference information. Here, the comparative phase difference information refers to information indicating the relationship between the phase difference information and the shape of the microstructure in order to determine the shape of the microstructure. The phase difference information may be not only information on the phase difference between the fast and slow axes of zero-order light obtained by transmitting or reflecting circularly polarized light, elliptically polarized light, or linearly polarized light through or on the microstructure, but also information that serves as the basis for calculating the phase difference. For example, it may be a Mueller matrix obtained by spectroscopic ellipsometry measurement to calculate the phase difference. It may also be image data obtained by measuring the phase difference with a polarization camera. The comparative phase difference information may be any information that can be used to calculate the shape of the microstructure and determine whether the shape is good or bad. Examples of the comparative phase difference information include a lookup table showing the relationship between phase difference and the shape of the microstructure, information showing the relationship between phase difference and the shape of the microstructure used in statistical estimation methods such as principal component analysis and Wiener estimation, information previously learned by AI about the relationship between phase difference and the shape of the microstructure, and a phase difference threshold value for determining the quality of the shape of the microstructure. Furthermore, the comparative phase difference information may be information indicating the relationship between the shape and change in phase difference between a plurality of microstructures input by an input means, a threshold value of the amount of change, etc. The relationship between the phase difference and the shape of the microstructure may not only be measured, but also calculated by optical simulation or the like.

[0083] When the phase difference information of the fine structure whose shape is to be determined is determined in the input step, in the structure step, the CPU 11 determines the shape of the fine structure based on the phase difference information and pre-stored phase difference information for comparison.

[0084] For example, the CPU 11 may determine the shape of a microstructure based on phase difference information input by an input means and a lookup table indicating the relationship between phase difference and shape that has been stored in advance. Alternatively, the CPU 11 may determine the shape of a microstructure based on AI that has previously learned the relationship between phase difference and shape. Alternatively, the CPU 11 may determine the shape of a microstructure by a statistical estimation method based on the phase difference information input by an input means and pre-stored information indicating the relationship between phase difference and shape. Any statistical estimation method may be used as long as it can determine the shape of a microstructure based on information indicating the relationship between phase difference and shape, and examples of such methods include principal component analysis and Wiener estimation. Alternatively, the CPU 11 may determine the quality of the shape of a microstructure based on a pre-stored phase difference threshold value. Alternatively, the CPU 11 may determine the shape of a microstructure based on changes in the phase difference between multiple microstructures input by an input means. A specific example of a method for determining the shape of a microstructure based on phase difference information will be described later in the examples.

[0085] Next, a description will be given of a determination program recording medium of the present invention. The determination program recording medium is one on which the above-described determination program 2 of the present invention is recorded. Each step of the above-described determination program 2 is executed by hardware such as a computer or its peripheral devices. Therefore, the determination system 1 can be configured to read and execute a recording medium on which the determination program 2 that executes each of the above-described steps is recorded. The recording medium may be any medium on which the determination program 2 of the present invention is recorded in a computer-readable manner. For example, an optical disk, a magnetic disk, a magneto-optical disk, or other non-volatile memory can be used. Specific examples include CDs, DVDs, BDs, hard disk drives (HDDs), solid-state drives (SSDs), USB memories, and ROMs.

[0086] Next, the determination device of the present invention will be described. The determination device of the present invention is mainly composed of a phase difference information detection means and a structure determination means.

[0087] The phase difference information detecting means detects phase difference information relating to the phase difference between the fast axis and slow axis of the zero-order light transmitted through the microstructure, and is mainly composed of an irradiation unit and a detection unit.

[0088] The irradiation unit is for irradiating the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light. Any irradiation unit may be used as long as it can irradiate the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and for example, a combination of a monochromatic light source and a circularly polarized filter may be used. Furthermore, the light may be irradiated perpendicularly to the microstructure, or the irradiation angle may be freely adjusted. Furthermore, it is preferable that the light irradiated from the light source be capable of irradiating light of multiple wavelengths.

[0089] The detection unit is for detecting phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light that has been transmitted through or reflected from the microstructure. Any detection unit may be used as long as it can detect phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light that has been irradiated from the irradiation unit and transmitted through or reflected from the microstructure. For example, a combination of a rotatable linear polarization filter and an image sensor, or a polarization image sensor may be used. The detection unit may also have a lens or the like for forming an image of the light that has been transmitted through or reflected from the microstructure on the image sensor.

[0090] Furthermore, a spectroscopic ellipsometer equipped with an irradiation unit and a detection unit can be used as the phase difference information detection means. By using the spectroscopic ellipsometer, the Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix can be detected as phase difference information.

[0091] The structure determination means is for determining the shape of the microstructure based on the phase difference information detected by the phase difference information detection means. Any means may be used as long as it can determine the shape of the microstructure based on the phase difference information detected by the phase difference information detection means, and for example, the determination system 1 and determination program 2 of the present invention may be used. Note that a specific example of a method for determining the shape of the microstructure based on the phase difference information will be described later in the examples.

[0092] The determination device of the present invention may also include a moving means for moving the microstructure to a position where the zero-order light can be detected by the phase difference information detection means. This allows the shape of the microstructure to be determined while the microstructure is being transported. Furthermore, by moving the microstructure with the moving means, the irradiation angle of light from the irradiation means changes, so that the microstructure can be irradiated with light at a plurality of different incident angles without changing the irradiation angle on the irradiation means side. The moving means may be any means capable of moving the microstructure to a position where the zero-order light can be detected by the phase difference information detection means. For example, a belt conveyor or the like that moves the microstructure placed on a tray or the like can be used.

[0093] Next, the microstructure manufacturing system of the present invention will be described. The microstructure manufacturing system of the present invention is mainly composed of a microstructure manufacturing device for manufacturing a microstructure and an evaluation device.

[0094] The microstructure manufacturing device is for manufacturing a microstructure having birefringence characteristics. The microstructure manufacturing device may be any device capable of manufacturing a microstructure having birefringence characteristics, and examples thereof include devices used in conventional imprinting and photolithography.

[0095] The determination device is for determining the shape of a microstructure having birefringence characteristics. Any determination device may be used as long as it can determine the shape of the microstructure, and for example, the determination device of the present invention described above may be used.

[0096] The microstructure manufacturing system of the present invention may further include a sorting means for sorting the microstructures based on the result of the shape determination by the determination device. The sorting means may be any means capable of sorting the microstructures based on the result of the shape determination by the determination device, and may be, for example, a known sorting device capable of sorting out defective products based on the result of the determination.

[0097] Next, the determination method of the present invention will be described. The determination method of the present invention is a method for determining the shape of a microstructure having birefringence characteristics, and is mainly composed of a phase difference information detection step and a structure determination step.

[0098] The phase difference information detection process is intended to detect the phase difference information relating to the phase difference between the fast axis and slow axis of the zero-order light transmitted through or reflected from the microstructure by irradiating the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and is mainly composed of an irradiation process and a detection process.

[0099] The irradiation step is for irradiating the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light. The irradiation step may be any step that can irradiate the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and the above-mentioned irradiation unit may be used. Furthermore, the light may be irradiated perpendicularly to the microstructure, or may be irradiated by freely adjusting the irradiation angle. Furthermore, it is preferable that the irradiated light can be selected from multiple wavelengths.

[0100] The detection step is for detecting phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light that has been transmitted through or reflected by the microstructure. The detection step may be any step that can detect phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light that has been irradiated in the irradiation step and transmitted through or reflected by the microstructure. For example, detection using a combination of a rotatable linear polarization filter and an image sensor, or detection using a polarization image sensor may be used.

[0101] Furthermore, the phase difference information detection step can also be performed using a spectroscopic ellipsometer. By using the spectroscopic ellipsometer, a Mueller matrix obtained by spectroscopic ellipsometry measurement or a phase difference calculated from the Mueller matrix can be detected as phase difference information.

[0102] The structure determination process is for determining the shape of the microstructure based on the phase difference information detected in the phase difference information detection process. The structure determination process may be any process that can determine the shape of the microstructure based on the phase difference information detected in the phase difference information detection process. For example, the shape of the microstructure may be determined based on the phase difference information detected in the phase difference information detection process and a lookup table indicating the relationship between the phase difference and the shape. Alternatively, the shape of the microstructure may be determined based on the phase difference information detected in the phase difference information detection process and an AI that has learned the relationship between the phase difference and the shape. Alternatively, the shape of the microstructure may be determined by a statistical estimation method based on the phase difference information detected in the phase difference information detection process and information indicating the relationship between the phase difference and the shape. Any statistical estimation method may be used as long as it can determine the shape of the microstructure based on information indicating the relationship between the phase difference and the shape, and examples of the statistical estimation method include principal component analysis and Wiener estimation. Alternatively, the shape of the microstructure may be determined based on the phase difference information detected in the phase difference information detection process and a phase difference threshold. Alternatively, the shape of the microstructure may be determined based on changes in the phase difference between multiple microstructures detected in the phase difference information detection process. The structure determination step may use the determination system 1 or determination program 2 of the present invention described above. A specific example of a method for determining the shape of a microstructure based on phase difference information will be described later in the examples.

[0103] Next, the microstructure manufacturing method of the present invention will be described. The microstructure manufacturing method of the present invention mainly comprises a microstructure manufacturing step for manufacturing a microstructure and an evaluation step.

[0104] The microstructure manufacturing process is for manufacturing a microstructure having birefringence characteristics. The microstructure manufacturing process may be any process capable of manufacturing a microstructure having birefringence characteristics, and may be, for example, a conventional technique such as imprinting or photolithography.

[0105] The determining step is for determining the shape of the microstructure having birefringence characteristics. The determining step may be any step that can determine the shape of the microstructure, and for example, the determining method of the present invention described above may be used.

[0106] Furthermore, the microstructure manufacturing method of the present invention may further include a sorting step of sorting the microstructures based on the results of the shape determination in the determination step. The sorting step may be any step that can sort the microstructures based on the results of the shape determination in the determination step, and for example, a known sorting method that can sort out defective products based on the determination results can be used.

[0107] A method for determining the shape of a fine structure will be described below using an example. [Example 1] This example demonstrates the evaluation of the molding accuracy of a microstructure. The microstructure was a vertical line-and-space diffraction grating, as shown in Figure 8. The diffraction grating was made of a high-refractive-index resin with a refractive index of 1.9, formed on quartz glass (SiO2). It had a pitch P of 550 nm, a height H of 275 nm, and a width W of 275 nm. The light used for measurement was irradiated perpendicularly to the microstructure. Figure 9(a) shows the wavelength dependence of the diffraction efficiency. Figure 9(b) shows the relationship between the retardation (= phase difference × measured wavelength) and the measured wavelength for a line-and-space pattern with a width varying by ±5% and ±10% from the center width of 275 nm. As shown in Figure 9(a), diffraction almost completely disappears at incident wavelengths of 800 nm or longer, leaving only the zero-order light propagating in a straight line. Furthermore, as shown in Figure 9(b), the phase difference changes with the change in line width. By measuring the retardation with incident light of 800 nm or longer, the line width variation can be detected from this change. Furthermore, because the change in retardation decreases with increasing wavelength in the wavelength range above 800 nm, it is recommended to measure wavelengths above 800 nm, preferably multiple wavelengths, and detect line width variations from the measured characteristics. Therefore, the phase difference information should include information on the phase difference of wavelengths in a wavelength range where at least one of the −1st-order and 1st-order diffraction efficiencies is 10% or less, preferably 5% or less, and more preferably, information on the phase difference between the fast and slow axes of zeroth-order light at multiple wavelengths. To detect line width variations more accurately, measurements can be performed in advance or a lookup table of the structure and retardation obtained through electromagnetic field simulation can be created and compared with the lookup table. Figure 9(c) shows the line width dependence of the diffraction efficiency of this diffraction grating at 450 nm, 550 nm, and 650 nm. A 10% line width variation results in a variation of several percent in diffraction efficiency. When this diffraction grating is used in a waveguide for AR glasses, this variation is large enough to be detected as unevenness in the image. Therefore, it is necessary to monitor the line width fluctuations that cause the fluctuations in the above manner.

[0108] [Example 2] This example evaluates the variation in molded shape due to the deformation of a replica mold when a microstructure is repeatedly molded using a replica mold. The microstructure used was the same as the vertical line-and-space diffraction grating shown in Example 1. The light used for measurement was irradiated perpendicularly to the microstructure. Figure 10 shows the shape change of a molded product due to the deformation of a replica mold after continuous molding. When continuous molding is performed using a replica mold, the replica gradually decreases in width and increases in length due to the tension during demolding. If the replica mold is made of a rubber-based material such as a silicone mold, the volume after deformation remains unchanged. In a replica mold that molds a line-and-space microstructure with a design value of width W and height H, the replica mold pattern at the initial molding stage, i.e., the inverted pattern of the microstructure, has a width PW and a height H. If the pattern width decreases by x after multiple moldings using this replica mold, the width W' of the replica mold pattern is PWx and the height H' is (PW)H / (PWx). Therefore, due to the deformation of this replica mold, the shape of the microstructure of the molded product will have a width W' of W+x and a height H' of (PW)H / (PWx).

[0109] Figure 11(a) shows the results of a simulation of the wavelength dependence of retardation with respect to changes in the width of the microstructure. The simulation was performed using the RCWA method of electromagnetic field analysis. The width was simulated for a line and space pattern with a width of 275 nm and a height of 275 nm, with width changes of 5% and 10%. It can be seen that at incident wavelengths of 800 nm or more, the difference in retardation rapidly decreases as the wavelength increases in response to changes in width.

[0110] Figure 11(b) compares the changes in retardation at incident wavelengths of 820 nm, 850 nm, and 880 nm. The solid line in Figure 11(b) represents the results for the microstructure shown in Example 1 and Figure 9(b), where only the line width is varied. The dashed line in Figure 11(b) represents the results for the microstructure shown in Figure 11(a), where not only the line width but also the height variation corresponding to the replica deformation is considered. Here, at an incident wavelength of 880 nm, the change in retardation due to replica deformation cannot be observed. This is thought to be due to the fact that the decrease in retardation due to the increase in width and the increase in retardation due to the increase in height cancel each other out at the incident wavelength of 880 nm. On the other hand, the change in retardation due to replica deformation can be observed at incident wavelengths of 820 nm and 850 nm. In other words, by observing the change in retardation for multiple incident wavelengths near the minimum wavelength at which diffraction does not occur, it is possible to detect the deformation of the microstructure shape associated with the continuous use of the replica mold. For this reason, it is preferable that the phase difference information include information about the phase difference between the fast axis and the slow axis of zero-order light of multiple wavelengths in a wavelength range where diffraction efficiency of at least one of -1st-order diffraction and 1st-order diffraction is 10% or less, preferably 5% or less. To detect line width fluctuations more accurately, measurements can be performed in advance, or a lookup table of the structure and retardation obtained by electromagnetic field simulation can be created and compared with the lookup table. Using the above method, it is possible to detect deformation of the replica mold due to continuous molding and manage the replacement timing of the replica mold in the manufacturing process of microstructures.

[0111] [Example 3] This example evaluates the variation in the molded shape due to the deformation of a replica mold when a microstructure is repeatedly molded using the replica mold. The microstructure used had the same shape as the vertical line-and-space diffraction grating shown in Example 1. Specifically, the microstructure was a line-and-space structure made of a dielectric material with a refractive index of 1.9 formed on quartz glass, with a pattern pitch of 550 nm, a pattern width of 275 nm, and a height of 275 nm. The light used for measurement was irradiated at an angle relative to the microstructure. By tilting the incident light used for measurement in this way, it is possible to more sensitively detect the variation in the shape of the molded microstructure due to the deformation of the replica mold shown in Example 2. Figure 12(a) shows an example of a measurement system in which light is incident at an angle relative to the microstructure and the retardation of light transmitted through the microstructure is measured. The measurement system may be a spectroscopic ellipsometer as shown in Figure 2 or a polarization camera as shown in Figure 3. The diffraction efficiency is shown when light is incident at an angle of 10° on the line-and-space microstructure using this measurement system. As shown in Figure 12(b), the wavelength dependence of the 1st-order diffracted light and -1st-order diffracted light differs depending on the angle of the incident light, with the 1st-order diffracted light disappearing at wavelengths of 730 nm or more and the -1st-order diffracted light disappearing at wavelengths of 870 nm or more.

[0112] Figure 12(c) shows the wavelength dependence of the retardation of the zero-order light for a line and space having a width of 275 nm and a sample whose width has increased by 5% to 289 nm due to deformation of the replica mold and whose height has been extended to 289.5 nm according to H' = (PW)H / (PWx) as shown in Example 2. The incident angles of the light used in the measurements were 0° and 10°. Compared to the retardation observed when the light was incident perpendicularly (= 0° incident angle), the retardation observed when the light was incident at an angle of 10° was significantly different from that observed when the light was incident perpendicularly (= 0° incident angle). Differences in the retardation of zero-order light between the two structures were observed over a wider wavelength range than the 0° incident angle, in the wavelength range from 730 nm to 870 nm, where only the -1st order diffracted light was observed. Therefore, by observing the retardation of zero-order light at multiple wavelengths in this wavelength range and comparing it with a lookup table prepared in advance using optical simulation, pattern deformation can be detected. The above method can detect replica mold deformation during continuous molding and enable management of the replacement timing of the replica mold during the process.

[0113] [Example 4] This example shows a case where the microstructure is a tilted grating, as shown in Figure 6. When light enters a tilted structure like those shown in Figures 6(a) and (b), the diffraction efficiency is such that there is almost no first-order diffraction and a large negative first-order diffraction, resulting in most of the diffracted light being diffracted in only one direction (left or right). For this reason, tilted waveguides are widely used as waveguides for input couplers in AR glasses, where light must be transmitted in only one direction. The diffraction efficiency of such tilted gratings varies greatly depending on their tilt. On the other hand, when tilted gratings are continuously molded, the tilt becomes gentler due to deformation during the release of the replica mold, which can cause fluctuations in the characteristics of the molded waveguide. Figure 13 shows an example where the diffraction efficiency of a tilted grating is calculated using electromagnetic field simulations as the tilt is changed. The grating shape is assumed to be 440 nm pitch, 260 nm width, and 60° tilt, as shown in Figure 13(a). This tilt changes to 70°, 75°, 80°, and 90° as the replica mold deforms. It is said that the pattern height increases to a certain extent as the replica stretches. The diffraction efficiencies of the -1st and 1st orders are shown in Figure 13(b). At a tilt of 60°, the diffraction efficiency of the -1st order is nearly 80% at an incident wavelength of around 550 nm, while the diffraction efficiency of the 1st order is almost nonexistent, indicating that diffraction occurs in only one direction. On the other hand, when the tilt exceeds 75°, the difference between the diffraction efficiencies of the -1st and 1st orders suddenly disappears, and at tilts of 80° or more, the diffraction efficiencies of the -1st and 1st orders become almost the same. As such, differences in tilt can have a significant effect on the characteristics of the waveguide, so it is important to monitor changes in the shape.

[0114] As in Example 3, a method for detecting changes in shape by varying the incident angle will be described. As shown in Figure 14(a), the microstructure was a tilted grating with a pitch of 440 nm, a width of 260 nm, a height of 339 nm, and a tilt of 60°. Figures 14(b) and 14(c) show the wavelength dependence of the diffraction efficiency for incident angles of -10°, 0°, and 10°. At any incident angle, no diffraction occurred in either transmission or reflection at incident wavelengths of 750 nm or greater, and the transmission of zero-order light exhibited stable characteristics with respect to wavelength. Figure 15 shows the retardation for incident angles of -10°, 0°, and 10° for each grating tilt. At wavelengths of 750 nm or greater where diffraction ceases to occur, comparing incident angles of -10°, 0°, and 10°, the retardation at an incident angle of 10° exhibits the greatest change with respect to the incident wavelength and grating tilt. Furthermore, at grating tilts of 80° or greater, the retardation at incident angles of -10° and 10° is nearly equal. Figure 16 shows the relationship between retardation and grating tilt α at incident angles of -10°, 0°, and 10° at incident wavelengths of 750 nm and 850 nm. Within the wavelength range where diffraction does not occur, the change in retardation due to grating tilt is greater at the shorter wavelength of 750 nm. However, the sensitivity of retardation to incident angles of -10°, 0°, or 10° varies depending on the grating tilt angle. Therefore, to more accurately determine the shape of a microstructure, it is preferable to irradiate the microstructure with light at multiple different incident angles and measure the retardation. This makes it possible to identify shape changes by referencing a lookup table of the correlation between retardation and shape for each incident angle, which has been prepared in advance.

[0115] [Example 5] This example uses a tilted grating similar to that of Example 4, but the substrate is made of a high-refractive-index material with a refractive index of 1.9, similar to that of the grating, as shown in Figure 17(a). When manufacturing a waveguide for AR glasses, using a high-refractive-index substrate as the optical waveguide allows for a wider viewing angle, making this structure more practical than Example 4. Figure 17(b) shows the retardation at incident angles of -10°, 0°, and 10°. At wavelengths above 750 nm, where diffraction no longer occurs, there is almost no difference in retardation compared to when the substrate is made of SiO2. Furthermore, the retardation trends at incident angles of -10°, 0°, and 10° for incident wavelengths above 750 nm are almost the same as those for SiO2 substrates. Therefore, the evaluation method of Example 4 can be used in the same way. Furthermore, as shown in Figures 17(c) and (d), there was no difference in retardation between when the incident light was incident from the pattern side and when it was incident from the substrate side. This demonstrates that either arrangement of the illumination and detection units of the measurement device is possible.

[0116] [Example 6] This example uses a sawtooth (blazed) grating as its microstructure. As shown in Figure 18(a), a sawtooth grating with a refractive index of 1.9 is formed on a substrate made of a high-refractive-index material. The grating has a pitch and pattern width of 440 nm and a height of 246 nm. Although the microstructure of this example has lower diffraction efficiency than a tilted grating, it is robust and suitable for stable manufacturing. Furthermore, when manufacturing a waveguide for AR glasses, using a high-refractive-index substrate as the optical waveguide allows for a wide viewing angle, making this structure more practical than Example 4. Figures 18(b), 18(c), and 18(d) show the diffraction efficiency at incident angles of -10°, 0°, and 10°. In the incident wavelength range of 600 nm to 800 nm, diffraction is almost exclusively -1st-order transmitted diffraction, while at wavelengths above 800 nm, only 0th-order light is transmitted. Figure 19 shows the wavelength dependence of retardation for this microstructure at incident angles of -10°, 0°, and 10°. Although not as pronounced as with the tilted grating, there was a change in retardation depending on the angle of incidence. Furthermore, the magnitude relationship of retardation at angles of incidence of -10°, 0°, and 10° was reversed for incident wavelengths of 600nm to 800nm ​​and 900nm to 1000nm. This demonstrates that the shape of the sawtooth grating can also be evaluated by measuring retardation at multiple angles of incidence and wavelengths.

[0117] [Example 7] In Examples 1 to 4, we have basically disclosed a method for detecting shape changes by comparing wavelength-dependent spectra of retardation. Specifically, we used data obtained by spectroscopic ellipsometry, because this method is easy to understand and explains the essence of the technical concept of the present invention. Meanwhile, the evaluation of microstructures according to the present invention can be achieved not only by point evaluation using spectroscopic ellipsometry, but also by a method using a polarization camera, as shown in Figure 7, to obtain a two-dimensional retardation distribution using multiple wavelengths presumed to be the most appropriate. This method is also more practical for use in manufacturing measurements. Figures 20(a) to 20(c) show a method for obtaining two-dimensional distribution measurements using a polarization camera that achieves equivalent results to evaluations performed by varying the angle of incident light. For example, in a known phase difference measurement system using a polarization camera, circularly polarized light is applied from the bottom to a substrate having a patterned area, such as an input or output coupler of a waveguide, and the polarization camera is fixed in position while the sample stage is moved. Then, the retardation can be measured and compared by varying the angle at which the polarization camera receives light. This makes it possible to obtain a two-dimensional distribution that is equivalent to the observations using light with different incident angles in Examples 3 and 4. Also, Fig. 21 shows a method for deriving the tilt of a grating, as in Example 4, by comparing the difference in retardation between the center and adjacent patterns on the left and right sides on a substrate on which multiple identical patterns are periodically arranged.

[0118] [Example 8] The structural determination of the processed shape of a microstructure according to the present invention is performed, for example, by steps configured as shown in Fig. 22. Note that, although a waveguide diffraction grating is used as an example of the microstructure here, the present invention is not limited to this and can also be applied to other microstructures with birefringence properties, such as phase difference elements and metalenses.

[0119] (1) The structural factors of the microstructure whose shape is to be determined are input into a program or device. Structural factors include, for example, the type of diffraction grating (microstructure), structural parameters, and optical properties of the material. Types of diffraction gratings include, for example, vertical binary (line-and-space grating), slanted (inclined line-and-space grating), and blazed (serrated line-and-space grating) used in waveguide input and output couplers. Structural parameters include the pitch, width, height, and fill factor of the pattern. Optical properties of the material include the refractive index of the pattern or substrate and the wavelength dependence of the refractive index.

[0120] (2) Select the most appropriate light measurement wavelength and measurement angle for the shape to be evaluated. The operator can select these appropriately based on optical simulations or previous measurement data, or the optimal conditions can be determined using a pre-prepared lookup table or AI that has learned from simulations and measurement data.

[0121] (3) A look-up table of structural parameters and retardation is created or selected based on optical simulations of the structure and measurement conditions or past experimental data.

[0122] (4) Measure the phase difference and phase axis of the measurement sample at the wavelength and measurement angle selected in (2). The measurement can be performed using the phase difference information detection means described above. The measurement range can be a single point, a line distribution, or a two-dimensional distribution within a plane.

[0123] (5) The shape of the sample's microstructure (pattern width and tilt) is derived from the phase difference and phase axis data for each wavelength and measurement angle obtained in (3) by referencing a lookup table. Alternatively, the shape (pattern width and tilt) can be derived using AI that has learned from simulations and measurement data.

[0124] (6) The derived shape of the microstructure is output as numerical data, statistical data such as its average and standard deviation, graphs, and contours. It is also determined whether the predicted processed shape is within the target value.

[0125] [Example 9] Evaluation of the optical properties of a microstructure according to the present invention is performed, for example, by steps configured as shown in Fig. 23. Note that, although a waveguide diffraction grating is used as an example of the microstructure here, the present invention is not limited to this and can also be applied to other microstructures with birefringence properties, such as phase difference elements and metalenses.

[0126] (1) The structural factors of the microstructure whose shape is to be determined are input into a program or device. Structural factors include, for example, the type of diffraction grating (microstructure), structural parameters, and optical properties of the material. Types of diffraction gratings include, for example, vertical binary (line-and-space grating), slanted (inclined line-and-space grating), and blazed (serrated line-and-space grating) used in waveguide input and output couplers. Structural parameters include the pitch, width, height, and fill factor of the pattern. Optical properties of the material include the refractive index of the pattern or substrate and the wavelength dependence of the refractive index.

[0127] (2) Select the most appropriate light measurement wavelength and measurement angle for the shape to be evaluated. The operator can select these appropriately based on optical simulations or previous measurement data, or the optimal conditions can be determined using a pre-prepared lookup table or AI that has learned from simulations and measurement data.

[0128] (3) Based on optical simulations of the structure and measurement conditions or on past experimental data, a lookup table of structural parameters and retardation and a lookup table of structural parameters and diffraction efficiency are created or selected.

[0129] (4) Measure the phase difference and phase axis of the measurement sample at the wavelength and measurement angle selected in (2). The measurement can be performed using the phase difference information detection means described above. The measurement range can be a single point, a line distribution, or a two-dimensional distribution within a plane.

[0130] (5) The shape of the sample's microstructure (pattern width and tilt) is derived from the phase difference and phase axis data for each wavelength and measurement angle obtained in (3) by referencing a lookup table. Alternatively, the shape (pattern width and tilt) can be derived using AI that has learned from simulations and measurement data.

[0131] (6) The diffraction efficiency is calculated by referring to a lookup table for the derived microstructure.

[0132] (7) The derived diffraction efficiency of the microstructure is output as numerical data, statistical data such as its average and standard deviation, graphs, and contours. It is also determined whether the predicted optical properties are within the target values.

[0133] [Example 10] This example shows the structure determination of Examples 6 and 7, in which the two-dimensional distribution of a two-dimensional diffraction grating is measured using a polarization camera. Figure 24 illustrates an overview of the measurement method of the present invention, graphically showing data obtained at each step of the structure determination. Here, two-dimensional retardation distribution measurement is performed using a polarization camera for the line-and-space pattern shown in Figure 8, and a pre-created lookup table, line width distribution, and diffraction efficiency distribution are derived. In this analysis, the pattern height distribution and pattern pitch are assumed to be uniform. However, it is also possible to create a lookup table by varying these parameters, or by varying multiple parameters. When determining the structure taking into account variations in multiple parameters, it is necessary to determine the structure by measuring under multiple conditions, such as by varying multiple incident wavelengths or angles, as described above. In this case, the lookup table can be created by effectively utilizing the characteristics obtained by the various methods shown in the examples.

[0134] [Example 11] The above examples have been described using molded waveguides. Meanwhile, nanoimprinting also requires the evaluation of the processed state of master molds. Master molds are typically made from silicon substrates. Specifically, patterns are created directly on the silicon substrate by dry etching, or patterns are formed by dry etching an SiO2 or SiN film deposited on the silicon substrate. To use the method of the present invention to inspect master molds with patterns formed on silicon substrates, the light used for measurement must have a wavelength that can penetrate silicon, and the image sensor must be able to detect this wavelength. To transmit through silicon, the inspection wavelength must be 1 μm or longer, preferably 1.2 μm or longer. While this wavelength range cannot be detected by conventional silicon image sensors, image sensors that detect infrared light in this range (SWIR) using low-bandgap compound semiconductors such as GaInAs and GaInP have recently become commercially available. Therefore, inspection is possible by creating a polarization camera in which a polarizer such as that described above is placed in each pixel of such an image sensor. Specifically, light with a wavelength of 1550 nm is emitted from an LED or laser and passed through a circular polarization filter consisting of a wire grid and a structural retarder to become circularly polarized light. This circularly polarized light is then passed through a master mold on a Si substrate and detected by a SWIR image sensor with azimuth polarizers of 0°, 45°, 90°, and 135° attached to each pixel. This allows for observations similar to those achieved by the method of the present invention described above.

[0135] [Example 12] In all of the above-mentioned measurement methods, circularly polarized light emitted from a light source was irradiated onto the evaluation object and the transmitted light was measured using a polarization camera. However, when using a master mold with a Si substrate as described above, a conventional image sensor cannot be used; a special compound semiconductor image sensor is required. In this case, a conventional image sensor can be used by using a reflection-type measurement method as shown in Figure 25. Specifically, light emitted from the light source is transmitted through a circular polarizing filter and then irradiated onto the master mold. The reflected light is imaged using a lens and received by a polarization image sensor with polarizers oriented at 0°, 45°, 90°, and 135° arranged at each pixel. The phase difference and principal axis direction can be calculated by evaluating this result using the method of the present invention described above. Note that in the reflection method, the light travels back and forth through the diffraction grating by reflection, so the calculated phase difference is twice the phase difference calculated using the transmission method.

[0136] The structure of a mold for an SiO2 pattern on a Si substrate is shown in Figure 26(a). The diffraction efficiency of reflected light from this structure at an incident angle of 30° is shown in Figure 27(a). The structure of a mold for an Si pattern on a Si substrate is shown in Figure 26(b). The diffraction efficiency of reflected light from this structure at an incident angle of 10° is shown in Figure 27(b). In both cases, no diffraction occurs at wavelengths of 700 nm or more, and the phase can be detected by detecting the zeroth-order reflected light. Therefore, the structure can be calculated from a lookup table, just like the transmission method described above.

[0137] So far, we have discussed waveguides that have birefringence due to periodic patterns, but it goes without saying that even for metasurfaces and metalenses with more complex structures, if they are optical elements that have birefringence properties locally due to the anisotropy of their structure, it is possible to calculate the phase difference using the method shown here and inspect the structure from a lookup table of the structure and phase difference. [Explanation of symbols]

[0138] 1 Judgment System 2. Judgment Program 9 Microstructure 10 Phase difference information detection means 11 Input Methods 12 Structure determination means 13 Transportation 21 Databases 41 Phase difference information detection means 42 Structure determination means 90 Mold 91 Waveguide 101 CPU 102 ROM 103 RAM 104 Storage device 106 Input Device 107 Display device 110 Irradiation unit 120 Detector 121 Image Sensor 122 Image Sensor 123 Lens 124 Circular Polarizing Filter 125 Linear Polarizing Filter

Claims

1. A determination program for determining the shape of a microstructure having birefringence characteristics, an input means for inputting phase difference information regarding the phase difference between the fast axis and the slow axis of zero-order light obtained by transmitting or reflecting circularly polarized light, elliptically polarized light, or linearly polarized light through or on the microstructure; a structure determination means for determining the shape of the microstructure based on the phase difference information input by the input means; A determination program that causes a computer to function as a

2. The determination program according to claim 1, characterized in that the structure determination means determines the shape of the microstructure based on the phase difference information input by the input means and a lookup table showing the relationship between phase difference and shape that has been stored in advance.

3. 2. The determination program according to claim 1, wherein the structure determination means determines the shape of the microstructure based on AI that has previously learned the relationship between phase difference and shape.

4. 2. The determination program according to claim 1, wherein the structure determination means determines the shape of the fine structure by a statistical estimation method based on a relationship between a phase difference and a shape stored in advance.

5. 2. The determination program according to claim 1, wherein the structure determination means determines the shape of the fine structure based on a pre-stored threshold value of phase difference.

6. 2. The determination program according to claim 1, wherein the structure determination means determines the shape of the microstructure based on a change in phase difference between a plurality of microstructures input by an input means.

7. 2. The determination program according to claim 1, wherein the program makes a computer function as a phase difference information detection means that detects the phase difference information and inputs the phase difference information to the input means.

8. 8. The determination program according to claim 7, wherein the phase difference information is a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

9. 8. The determination program according to claim 7, wherein the phase difference information is image data detected by a polarization camera.

10. The determination program according to claim 1, characterized in that the phase difference information includes information about the phase difference between the fast axis and the slow axis of the zeroth order light of multiple wavelengths in a wavelength region in which the diffraction efficiency of at least one of −1st order diffraction and 1st order diffraction is 10% or less.

11. The determination program according to claim 1, characterized in that the phase difference information includes information regarding the phase difference between the fast axis and the slow axis of the zeroth-order light having a wavelength in a wavelength region in which the diffraction efficiency of the zeroth-order diffraction is 50% or more and 90% or less.

12. 2. The determination program according to claim 1, wherein the phase difference information includes a phase difference between a fast axis and a slow axis of the zero-order light transmitted through or reflected by the microstructure at a plurality of different angles of incidence.

13. 2. The determination program according to claim 1, wherein the structure determination means calculates the shape of the microstructure.

14. 2. The judgment program according to claim 1, wherein the structure judgment means judges whether the shape of the microstructure is good or bad.

15. 2. The determination program according to claim 1, wherein the microstructure is one of a diffraction grating, a phase difference element, and a metalens.

16. 16. A determination system comprising hardware on which the determination program according to claim 1 is installed.

17. 16. A determination program recording medium, which is a recording medium on which the determination program according to claim 1 is recorded.

18. A determination device for determining the shape of a microstructure having birefringence characteristics, comprising: a phase difference information detecting means having an irradiating unit that irradiates the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and a detecting unit that detects phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light irradiated from the irradiating unit and transmitted through or reflected by the microstructure; a structure determination means for determining the shape of the microstructure based on the phase difference information detected by the detection unit; A determination device comprising:

19. The determination device according to claim 18, characterized in that the structure determination means determines the shape of the microstructure based on the phase difference information detected by the phase difference information detection means and a lookup table showing the relationship between phase difference and shape that has been stored in advance.

20. 19. The determination device according to claim 18, wherein the structure determination means determines the shape of the microstructure based on AI that has previously learned the relationship between phase difference and shape.

21. 19. The determination apparatus according to claim 18, wherein the structure determination means determines the shape of the fine structure by a statistical estimation method based on a relationship between a phase difference and a shape stored in advance.

22. 19. The determination apparatus according to claim 18, wherein the structure determination means determines the shape of the fine structure based on a pre-stored threshold value of the phase difference.

23. 19. The determination device according to claim 18, wherein the structure determination means determines the shape of the microstructure based on a change in phase difference between a plurality of microstructures detected by a phase difference information detection means.

24. 19. The determination device according to claim 18, wherein the phase difference information detection means detects, as the phase difference information, a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

25. 19. The determination device according to claim 18, wherein the phase difference information detection means includes a polarization camera that detects detected image data or the phase difference calculated from the image data as the phase difference information.

26. The determination device according to claim 18, characterized in that the irradiation unit irradiates light of multiple wavelengths in a wavelength range in which the diffraction efficiency of at least one of -1st order diffraction and 1st order diffraction for the microstructure is 10% or less.

27. 19. The determination device according to claim 18, wherein the irradiating unit irradiates light with a wavelength in a wavelength range in which the diffraction efficiency of zero-order diffraction for the microstructure is 50% or more and 90% or less.

28. 19. The determination device according to claim 18, wherein the irradiating unit irradiates the microstructure with light at a plurality of different angles of incidence.

29. 19. The determination apparatus according to claim 18, wherein the structure determination means calculates the shape of the microstructure.

30. 19. The determination apparatus according to claim 18, wherein the structure determination means determines whether the shape of the microstructure is good or bad.

31. 19. The determination apparatus according to claim 18, further comprising a moving means for moving the fine structure to a position where the zero-order light can be detected by the phase difference information detecting means.

32. 19. The determination device according to claim 18, wherein the microstructure is one of a diffraction grating, a phase difference element, and a metalens.

33. a microstructure manufacturing device for manufacturing a microstructure having birefringence properties; A microstructure manufacturing system comprising the determination device according to any one of claims 18 to 32 for determining the shape of the microstructure.

34. 34. The microstructure manufacturing system according to claim 33, further comprising a classification means for classifying the microstructures based on the result of the determination of the shape of the microstructure by the determination device.

35. A method for determining the shape of a microstructure having birefringence properties, comprising: a phase difference information detection step of irradiating the microstructure with circularly polarized light, elliptically polarized light, or linearly polarized light, and detecting phase difference information relating to the phase difference between the fast axis and the slow axis of the zero-order light transmitted through or reflected by the microstructure; a structure determination step of determining the shape of the microstructure based on the phase difference information detected in the phase difference information detection step; A determination method comprising:

36. The determination method according to claim 35, characterized in that the structure determination step determines the shape of the microstructure based on the phase difference information detected by the phase difference information detection step and a lookup table showing the relationship between phase difference and shape.

37. The method according to claim 35, wherein the structure determination step determines the shape of the microstructure based on AI that has learned the relationship between phase difference and shape.

38. 36. The method according to claim 35, wherein the structure determining step determines the shape of the fine structure by a statistical estimation method based on the relationship between phase difference and shape.

39. 36. The method according to claim 35, wherein the structure determination step determines the shape of the fine structure based on a threshold value of a phase difference.

40. The determination method according to claim 35, characterized in that the structure determination step determines the shape of the microstructure based on a change in phase difference between multiple microstructures detected by the phase difference information detection step.

41. 36. The method according to claim 35, wherein the phase difference information detection step detects, as the phase difference information, a Mueller matrix obtained by spectroscopic ellipsometry measurement or the phase difference calculated from the Mueller matrix.

42. 36. The method according to claim 35, wherein the phase difference information detection step detects, as the phase difference information, image data detected by a polarization camera or the phase difference calculated from the image data.

43. The method according to claim 35, characterized in that the phase difference information detection step involves irradiating light of multiple wavelengths in a wavelength region in which the diffraction efficiency of at least one of -1st order diffraction and 1st order diffraction for the microstructure is 10% or less.

44. 36. The method according to claim 35, wherein the phase difference information detection step irradiates the microstructure with light having a wavelength in a wavelength range in which the diffraction efficiency of zero-order diffraction is 50% or more and 90% or less.

45. 36. The determination method according to claim 35, wherein the phase difference information detection step includes irradiating the fine structure with light at a plurality of different angles of incidence.

46. 36. The method according to claim 35, wherein the structure determination step calculates the shape of the microstructure.

47. 36. The method according to claim 35, wherein the structure determining step determines whether the shape of the microstructure is good or bad.

48. 36. The method according to claim 35, wherein the microstructure is one of a diffraction grating, a phase difference element, and a metalens.

49. a microstructure fabrication process for fabricating microstructures having birefringent properties; and a determining step of determining the shape of the fine structure by using the determining method according to any one of claims 35 to 48.

50. 50. A method for producing a fine structure according to claim 49, further comprising a classification step of classifying the fine structures based on the results of the determination of the shape of the fine structures in the determination step.

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