Parameter estimation method, parameter estimation system, and parameter estimation program

Abstract

This tool accurately estimates the optical parameters of various materials. [Solution] The parameter calculation method includes the steps of: obtaining composite layer measurements for the first irradiation and the second irradiation, respectively, of a composite layer which includes a layer made of a target material of a predetermined thickness between a support layer and a substrate, performed by a computer; and estimating the optical parameters of the target material based on the composite layer measurements and optical parameters including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and substrate material.

Description

Technical Field

[0001] The present invention relates to a parameter estimation method, a parameter estimation system, and a parameter estimation program.

Background Art

[0002] Conventionally, a technique for estimating the optical parameters of a material based on the transmitted light characteristics and reflected light characteristics of the material has been known.

[0003] For example, the light scattering characteristic measurement method described in Patent Document 1 actually measures the transmitted light characteristics and reflected light characteristics of the light scatterer of the measurement target, generates the value of the parameter used in the Monte Carlo method of light scattering by a computer, and changes the value of the parameter. While executing the Monte Carlo method calculation for the light scatterer, the value of the parameter that matches the calculation result and the actually measured measurement data is obtained, and the value of the parameter is used as the characteristic data of the light scatterer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the light scattering characteristic measurement method described in Patent Document 1 assumes that the transmitted light characteristics and reflected light characteristics of the measurement target can be actually measured. Therefore, the case where the transmitted light characteristics and reflected light characteristics of the measurement target cannot be actually measured is not considered. Further, although the light scattering characteristic measurement method obtains the value of the parameter by setting the value of the light absorption coefficient of the light scatterer to 0, in the case of a measurement target for which light absorption cannot be ignored, the light absorption coefficient must also be considered and compared with the actually measured measurement data. There is a risk that the accuracy of the obtained parameter value will decrease as the number of parameters to be searched increases.

[0006] Therefore, the present invention aims to improve the accuracy of estimating the optical parameters of various materials. [Means for solving the problem]

[0007] A parameter estimation method according to one aspect of the present invention is performed by a computer and includes a composite layer measurement acquisition step in which a composite layer having a predetermined thickness of a target material between a support layer made of a support material and a substrate made of a substrate material is measured by optical measurement by a first irradiation in which light of a predetermined wavelength is irradiated from the support layer side of the composite layer and by optical measurement by a second irradiation in which light of a predetermined wavelength is irradiated from the substrate side of the composite layer, thereby obtaining composite layer measurement values ​​that are at least one of the total transmittance, straight transmittance and reflectance of the composite layer in the case of the first irradiation and the case of the second irradiation, respectively; and a target material estimation step in which the optical parameters of the target material are estimated based on the composite layer measurement values ​​obtained in the composite layer measurement acquisition step and optical parameters including the absorption coefficient, scattering coefficient and scattering anisotropy parameter of the support material and substrate material. [Effects of the Invention]

[0008] According to the present invention, the accuracy of estimating the optical parameters of various materials can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an overview of the processing in a parameter estimation system 100, which is one embodiment of the present invention. [Figure 2] This figure shows the configuration of a parameter estimation system 100, which is one embodiment of the present invention. [Figure 3A] This figure shows an example of a measurement method in the measuring device 200. [Figure 3B] This figure shows an example of a measurement method in the measuring device 200. [Figure 4] This diagram shows an overview of the inverse Monte Carlo method. [Figure 5A]This figure shows the evaluation results, which assess the accuracy of the estimated optical parameters of the target material. [Figure 5B] This figure shows the evaluation results, which assess the accuracy of the estimated optical parameters of the target material. [Figure 6] This figure shows an example of the hardware configuration of Computer 600. [Modes for carrying out the invention]

[0010] A preferred embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a diagram showing an overview of the processing in a parameter estimation system 100, which is one embodiment of the present invention.

[0011] The parameter estimation system 100 is an information processing system implemented by a parameter estimation program. The parameter estimation system 100 estimates the optical parameters of a target material based on the composite layer measurement values ​​of a composite layer having a layer made of the target material between a support layer made of a support material (hereinafter also simply referred to as the "support layer") and a substrate made of a substrate material (hereinafter also simply referred to as the "substrate"), and the optical parameters of the support material and the substrate material. In descriptions relating to embodiments of the parameter estimation system 100, the composite layer having a layer made of the target material between the support layer and the substrate may be simply referred to as the composite layer.

[0012] First, the parameter estimation system 100 acquires the optical parameters of the support material and the substrate material. If the optical parameters of the support material and the substrate material are known, their values ​​may be acquired. If the optical parameters of the support material and the substrate material are unknown, the system may further perform a reference layer measurement acquisition step, in which reference layer measurement values, which are at least one of the total transmittance, directional transmittance, and reflectance at a predetermined film thickness of the support layer and the substrate, are acquired by optical measurement using light of a predetermined wavelength; and a reference layer estimation step, in which optical parameters including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and the substrate material are estimated based on the reference layer measurement values ​​acquired in the reference layer measurement acquisition step. The processing of the parameter estimation system 100 will be explained below using the case where the optical parameters of the support material and the substrate material are unknown as an example.

[0013] The parameter estimation system 100 obtains reference layer measurements for each reference layer (hereinafter also referred to as the "reference layer"), which are at least one of the total transmittance, straight transmittance, and reflectance of the support layer and substrate (hereinafter also referred to as the "reference layer") at a predetermined film thickness, by optical measurement using light of a predetermined wavelength (S101). The parameter estimation system 100 uses the inverse Monte Carlo method to estimate optical parameters, including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and substrate material, based on the reference layer measurements, which are at least one of the total transmittance, straight transmittance, and reflectance of the reference layer (S102).

[0014] Subsequently, in the composite layer, the parameter estimation system 100 obtains a composite layer measurement value that is at least one of the total transmittance, direct transmittance, and reflectance of the composite layer for each of the first irradiation case and the second irradiation case, by optical measurement using light of a predetermined wavelength irradiating from the support layer side of the composite layer and optical measurement using light of a predetermined wavelength irradiating from the substrate side of the composite layer (S103). The parameter estimation system 100 estimates the optical parameters of the target material based on the composite layer measurement value obtained in S103 and the optical parameters of the support material and the substrate material estimated in S102, using the inverse Monte Carlo method (S104). Thus, the parameter estimation system 100 can estimate the optical parameters of the target material based on the composite layer measurement values for the first irradiation case and the second irradiation case, which are obtained by, so to speak, inverting the composite layer.

[0015] FIG. 2 is a diagram showing the configuration of a parameter estimation system 100 according to an embodiment of the present invention. The parameter estimation system 100 may be communicably connected via a network such as the Internet to a measuring device 200. Details of the parameter estimation system 100 will be described later.

[0016] The measuring device 200 obtains a reference layer measurement value that is at least one of the total transmittance, direct transmittance, and reflectance of the reference layer at a predetermined film thickness, by optical measurement using light of a predetermined wavelength, and outputs reference layer measurement value information regarding the reference layer measurement value to the parameter estimation system 100.

[0017] Also, the measuring device 200 obtains a composite layer measurement value that is at least one of the total transmittance, direct transmittance, and reflectance of the composite layer for each of the first irradiation case and the second irradiation case, and outputs composite layer measurement value information regarding the composite layer measurement value to the parameter estimation system 100.

[0018] The measurement method by the measuring device 200 will be described later.

[0019] Although only one measuring device 200 is shown in Figure 2, there may be multiple measuring devices 200. Furthermore, the user may input the measurement data acquired by the measuring device 200 (i.e., reference layer measurement data and composite layer measurement data) into the parameter estimation system 100.

[0020] The parameter estimation system 100 comprises a storage unit 110, a reference layer measurement value acquisition unit 120, a reference layer estimation unit 130, a composite layer measurement value acquisition unit 140, and a target material estimation unit 150. Each of the units shown in Figure 2 can be realized, for example, by using a storage area or by having a processor execute a program stored in the storage area.

[0021] The storage unit 110 stores information processed in the parameter estimation system 100. The storage unit 110 can store, for example, reference layer measurement information, reference layer estimation result information, composite layer measurement information, and target material estimation result information, which will be described later.

[0022] The reference layer measurement value acquisition unit 120 acquires reference layer measurement values, which are at least one of the total transmittance, straight transmittance, and reflectance at a predetermined thickness of the reference layer, by optical measurement using light of a predetermined wavelength, and stores the reference layer measurement value information related to the reference layer measurement values ​​in the storage unit 110.

[0023] The reference layer measurement value acquisition unit 120 may acquire reference layer measurement value information relating to the reference layer measurement value measured by the measuring device 200. The reference layer measurement value acquisition unit 120 may acquire reference layer measurement value information from the measuring device 200.

[0024] The specified wavelength may be a single wavelength or multiple wavelengths. For example, it may be multiple wavelengths in the ultraviolet-visible region. If the wavelengths used for optical measurement are multiple wavelengths, the reference layer measurement information may include reference layer measurement information for each of the multiple wavelengths, or it may include only the support measurement information for the wavelengths used to estimate the optical parameters.

[0025] The support material and substrate material are not particularly limited and may be, for example, inorganic materials (e.g., glass), organic materials (e.g., polyester or bismaleimide-triazine resin), or metals (e.g., copper). The support material and substrate material are preferably materials that have sufficient light transmittance at the wavelength at which optical measurement is performed and that are self-supporting. For example, they may be glass or polymers, and the polymer may be polyester such as PET (polyethylene terephthalate).

[0026] The support layer is a base layer made of a support material, and plays the role of temporarily supporting the target material when laminating the target material layer onto the substrate. Therefore, it is preferable that the support layer is easily peelable after the target material layer has been laminated onto the substrate, and for example, a PET film is preferred.

[0027] The substrate is a reference layer made of substrate material, and since it is a layer that performs various functions while holding the layer made of the target material, it is preferable that it is a layer with sufficient strength, for example, a glass substrate is preferred.

[0028] Figures 3A and 3B show examples of measurement methods in the measuring device 200.

[0029] Figure 3A shows an example of the measurement method for total transmittance and directional transmittance using the measuring device 200.

[0030] In the measurement method of the measuring device 200 shown in Figure 3A, light irradiated from the light source 310 passes through the material 320 (reference layer or composite layer), and the detector 330 measures the straight-transmitted light 340 (T s ) and diffuse transmitted light 350(T d ) including total transmitted light (T t ) is detected. The measuring device 200 measures the total transmittance based on the straight transmitted light 340 and diffuse transmitted light 350 detected in the detector 330, and measures the straight transmittance based on the straight transmitted light 340 detected in the detector 330.

[0031] Figure 3B shows an example of a method for measuring reflectance using the measuring device 200.

[0032] In the measurement method of the measuring device 200 shown in Figure 3B, light irradiated from the light source 310 is reflected by the material 320 (reference layer or composite layer), and the reflected light 360 (R) is detected by the detector 330. t ) is detected. The measuring device 200 measures the reflectance based on the reflected light 360 detected by the detector 330.

[0033] The reference layer estimation unit 130 estimates optical parameters, including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and substrate material, based on reference layer measurement values, which are at least one of the total transmittance, straight transmittance, and reflectance at a predetermined thickness of the reference layer, and stores the reference layer estimation result information related to the estimation results in the storage unit 110.

[0034] The reference layer estimation unit 130 can estimate the optical parameters of the support material and the substrate material based on at least one of the reference layer measurements of total transmittance, directional transmittance, and reflectance at a predetermined thickness of the reference layer, for example, using the inverse Monte Carlo method.

[0035] Specifically, the reference layer estimation unit 130 can estimate the optical parameters of the support material and substrate material by searching for optical parameters of the support material and substrate material that minimize an evaluation function that evaluates the error between the reference layer measurement value, which is at least one of the total transmittance, straight transmittance, and reflectance at a predetermined thickness of the reference layer, and the reference layer calculation value, which is at least one of the total transmittance, straight transmittance, and reflectance at a predetermined thickness of the reference layer calculated based on the generated optical parameters of the support material and substrate material. The method for generating the optical parameters may be exhaustive generation or random generation. The method for searching for the optical parameters may be a search method that evaluates all the generated parameters or a search method that evaluates only a portion of the generated parameters using a Bayesian optimization method.

[0036] Here, the predetermined thickness of the reference layer may be one thickness or multiple thicknesses. Since the reference layer is made of a material that has sufficient light transmittance at a predetermined wavelength and is less affected by absorption and scattering, the influence of the reference layer on the total transmittance, direct transmittance, and reflectance of the composite layer is small. Therefore, even if the optical parameters of the reference layer are estimated based only on measurements of a single-thickness reference layer, the optical parameters of the target material can be estimated with high accuracy in the target material estimation unit 150 described later.

[0037] The total transmittance, directional transmittance, and reflectance of a layer made of a material depend on the optical parameters of the material. That is, the total transmittance, directional transmittance, and reflectance of a layer made of a given material can be calculated based on the optical parameters of the material and other parameters (e.g., the position of the light source, the angle of the irradiated light, the film thickness, the refractive index of the material, etc.). Specific calculation methods will be described later.

[0038] Therefore, the reference layer estimation unit 130 generates optical parameters for the support material or substrate material, and calculates a reference layer calculated value which is at least one of the total transmittance, direct transmittance, and reflectance at a predetermined thickness of the reference layer, based on the generated optical parameters. The reference layer estimation unit 130 compares the calculated reference layer value with the reference layer measured value indicated by the reference layer measured value information. The reference layer estimation unit 130 repeats the generation of optical parameters, calculation of the reference layer calculated value, and comparison with the reference layer measured value. This repetition may be performed a number of times set by the administrator of the parameter estimation system 100, or it may terminate when the value of the evaluation function described later falls below a predetermined value.

[0039] The reference layer estimation unit 130 then estimates the optical parameters that most accurately reproduce the reference layer measurements as the optical parameters for the support material and the substrate material. At this time, the reference layer estimation unit 130 may use, for example, an evaluation function to evaluate the error between the calculated reference layer values ​​and the measured reference layer values. The evaluation function may be, for example, the sum of the squares of the errors between each calculated value (calculated values ​​of total transmittance, straight transmittance, and reflectance) and each measured value (measured values ​​of total transmittance, straight transmittance, and reflectance), or it may be the square root of the sum of squares.

[0040] In this way, the reference layer estimation unit 130 generates optical parameters and searches for appropriate optical parameters by comparing the reference layer calculated values ​​of total transmittance, straight transmittance, and reflectance based on the generated optical parameters with the reference layer measured values.

[0041] Figure 4 shows an overview of the method used by the reference layer estimation unit 130 to estimate the optical parameters of a reference layer using the inverse Monte Carlo method. First, the reference layer estimation unit 130 generates optical parameters (S401). Next, the reference layer estimation unit 130 calculates the reference layer calculated values ​​for total transmittance, straight transmittance, and reflectance at a predetermined thickness of the reference layer based on the generated optical parameters (S402). The reference layer estimation unit 130 compares the calculated reference layer values ​​with the reference layer measured values ​​indicated by the reference layer measurement information based on an evaluation function (S403). The process returns to S401, generates another set of optical parameters, and repeats the steps up to S403. At a predetermined timing, the reference layer estimation unit 130 terminates the repetition and determines the optical parameters of the reference layer (S404). The target material estimation unit 150, described later, can also estimate the optical parameters of a target material using a similar method.

[0042] Next, we will detail an example of how to calculate the total transmittance, direct transmittance, and reflectance values ​​in S402. The scattering coefficient is μ s , the absorption coefficient is μ a Considering the case where a single photon is incident on the surface of a material with a scattering anisotropy parameter of g, the mean free path L of that photon is expressed by the following equation (1).

[0043]

number

[0044] Here, r1 is a random number between 0 and 1.

[0045] Assuming that a photon traveling a distance L undergoes both scattering and absorption simultaneously, the photon's light intensity is attenuated by the weight of W shown in equation (2), and scattered in the direction of the zenith angle θ shown in equation (3) relative to the direction of the photon's propagation. Furthermore, scattering occurs isotropically in the azimuthal direction.

[0046]

number

[0047]

number

[0048] Here, f(θ) represents the cumulative distribution function of the scattering phase function p(θ), and r² is a random number between 0 and 1. Examples of phase functions include the Henyey-Greenstein phase function shown in equation (4).

[0049]

number

[0050] In equation (4), when g ≠ 0, cosθ is given by equation (5).

[0051]

number

[0052] Using these equations, the scattering coefficient μ s , extinction coefficient μ aFrom the scattering anisotropy parameter g, it is possible to simulate the propagation path of a photon and the attenuation of light intensity during that process. When the light intensity of a photon becomes sufficiently small (for example, when it becomes less than 1 / 10,000th of the incident light intensity), the photon can be considered to have vanished. If the photon is emitted from the incident surface of the material, it is considered to have been reflected, and if the photon is emitted from the surface opposite to the incident surface of the material (i.e., if the photon propagates in the direction of the material's film thickness over a distance greater than or equal to the material's film thickness d), it is considered to have been transmitted, and the light intensity of the emitted photon is recorded.

[0053] Furthermore, if a photon reaches a material interface, for example, the interface between a material layer and air, the interface between a support layer and the target material layer in a composite layer, or the interface between a substrate and the target material layer in a composite layer, it may be assumed that the photon was reflected or transmitted based on a probability calculated using Fresnel's equation.

[0054] By performing such calculations for multiple photons, the total transmittance, straight-line transmittance, and reflectance of a layer made of material can be calculated as the light intensity of transmitted photons, straight-line transmitted photons, and reflected photons in relation to the light intensity of incident photons.

[0055] The range of values ​​from which the optical parameters are generated may be set for each optical parameter by the administrator of the parameter estimation system 100.

[0056] Furthermore, when the reference layer estimation unit 130 estimates the optical parameters of the support material and substrate material, it may use measured values ​​of the refractive indices of the support material and substrate material, or it may estimate the refractive indices of the support material and substrate material simultaneously. As a method for measuring the refractive index, for example, it may be measured using a prism coupler, and the refractive index at a predetermined wavelength may be estimated using Cauchy's dispersion formula or Selmeyer's dispersion formula based on the refractive index values ​​at each wavelength measured using the prism coupler. When estimating the refractive index of the support material and substrate material, the refractive index may be generated simultaneously when generating the optical parameters, and the refractive index that can reproduce the reference layer measurement value with the most accuracy may be estimated as the refractive index of the reference layer.

[0057] The composite layer measurement value acquisition unit 140 acquires composite layer measurement values, which are at least one of the total transmittance, direct transmittance, and reflectance of the composite layer, for both the first and second irradiation cases, by performing optical measurements by first irradiation, in which light of a predetermined wavelength is irradiated from the support layer side of the composite layer, and by second irradiation, in which light of a predetermined wavelength is irradiated from the substrate side of the composite layer, and stores the composite layer measurement value information related to the composite layer measurement values ​​in the storage unit 110.

[0058] Here, the target material may be, for example, a composite material containing multiple materials, or it may be a non-self-supporting film material in which it is difficult to measure the total transmittance, directional transmittance, and reflectance of a target material layer consisting only of the target material. The target material may be a photosensitive resin composition, for example, a solder resist or a photosensitive interlayer insulating material.

[0059] In this regard, when the target material is a composite material (e.g., solder resist), it is extremely difficult to individually measure the optical parameters of each material contained in the composite material, and therefore it is difficult to calculate the optical parameters of the target material based on the optical parameters of each material. Therefore, the parameter estimation method of this embodiment can estimate the optical parameters of the target material, which is a composite material, by treating the target material as a single uniform material. Furthermore, when the target material is a non-self-supporting film material (e.g., a thin film of solder resist), it is difficult to obtain a self-supporting film of the target material layer consisting only of the target material, and therefore it is difficult to measure the total transmittance, directional transmittance, and reflectance of the target material layer. Therefore, the parameter estimation method of this embodiment can estimate the optical parameters of the target material even if it is a non-self-supporting film material, by using at least one of the total transmittance, directional transmittance, and reflectance of the composite layer, along with the optical parameters of the support material and the substrate material.

[0060] The film thickness of the support layer and the substrate in the composite layer may be the same as, or different from, the film thickness of the support layer and the substrate in the reference layer measurement values ​​indicated by the reference layer measurement value information.

[0061] The composite layer measurement value acquisition unit 140 may acquire composite layer measurement value information relating to the composite layer measurement value measured by the measuring device 200. The composite layer measurement value acquisition unit 140 may acquire composite layer measurement value information from the measuring device 200.

[0062] The composite layer measurement value acquisition unit 140 may acquire composite layer measurement values ​​for each of a plurality of composite layers, each of which layers made of target materials with different film thicknesses are laminated between a support layer and a substrate, for the case of a first or second irradiation, and composite layer measurement values ​​for at least one of the plurality of composite layers, for the case of both the first and second irradiation. In other words, the composite layer measurement value acquisition unit 140 may acquire composite layer measurement values ​​for at least one composite layer among the plurality of composite layers that has a target material layer of a predetermined film thickness, for the case of both the first and second irradiation, and for the other composite layers, it may acquire composite layer measurement values ​​for either the first or second irradiation. In this case, the composite layer measurement value acquisition unit 140 may acquire composite layer measurement values ​​for each of the plurality of composite layers, for the case of both the first and second irradiation.

[0063] Furthermore, the composite layer measurement value acquisition unit 140 may acquire composite layer measurement values ​​for each of a plurality of composite layers, each containing one substrate from a plurality of different substrates.

[0064] The predetermined wavelength may be a single wavelength or multiple wavelengths. For example, it may be multiple wavelengths in the ultraviolet-visible region. If the predetermined wavelength is multiple wavelengths, the composite layer measurement information may include composite layer measurement information for each of those multiple wavelengths, or it may include only the composite layer measurement information for the wavelength used to estimate the optical parameters.

[0065] The target material estimation unit 150 estimates the optical parameters of the target material based on at least one composite layer measurement value of the total transmittance, straight transmittance, and reflectance of the composite layer for the first irradiation and the second irradiation, respectively, and the optical parameters of the support material and substrate material estimated by the reference layer estimation unit 130, and stores the composite layer estimation result information related to the estimation result in the storage unit 110.

[0066] The target material estimation unit 150 can estimate the optical parameters of the target material by, for example, using the inverse Monte Carlo method, based on at least one of the composite layer measurements of total transmittance, directional transmittance, and reflectance for the first and second irradiation cases, respectively, and the optical parameters of the support material and substrate material estimated by the reference layer estimation unit 130.

[0067] Specifically, the target material estimation unit 150 includes searching for and estimating optical parameters of the target material that minimize the error between the composite layer measurement values ​​obtained by the composite layer measurement value acquisition unit 140 and the composite layer calculation values, which are at least one of the total transmittance, direct transmittance, and reflectance of the composite layer for the first irradiation and the second irradiation, respectively, calculated based on the optical parameters of the generated target material and the optical parameters of the support material and substrate material estimated by the reference layer estimation unit 130.

[0068] The target material estimation unit 150 generates optical parameters for the target material and calculates a composite layer calculation value, which is at least one of the total transmittance, direct transmittance, and reflectance of the composite layer, for both the first and second irradiation cases, based on the generated optical parameters for the target material and the optical parameters of the support material and substrate material estimated by the reference layer estimation unit 130. The target material estimation unit 150 compares the composite layer calculation value with the composite layer measurement value indicated by the composite layer measurement value information. The target material estimation unit 150 repeats the generation of optical parameters for the target material, the calculation of the composite layer calculation value, and the comparison with the composite layer measurement value. This repetition may be performed a number of times set by the administrator of the parameter estimation system 100, or it may terminate when the value of the evaluation function described later reaches a predetermined value. The method of repetition may be the same as or different from the method of repetition in the reference layer estimation unit 130. The method of calculating the calculated values ​​of the total transmittance, direct transmittance, and reflectance of the composite layer is the same as the calculation method in the reference layer estimation unit 130.

[0069] The target material estimation unit 150 then estimates the optical parameters that most accurately reproduce the composite layer measurements as the optical parameters of the target material. At this time, the target material estimation unit 150 may use, for example, an evaluation function to evaluate the error between the calculated composite layer values ​​and the measured composite layer values. The evaluation function may be, for example, the sum of the squares of the errors between each calculated value (calculated values ​​of total transmittance, straight transmittance, and reflectance) and each measured value (measured values ​​of total transmittance, straight transmittance, and reflectance), or it may be the square root of the sum of squares. The evaluation function may be the same as the evaluation function in the reference layer estimation unit 130, or it may be different.

[0070] In this way, the target material estimation unit 150 generates optical parameters and can estimate appropriate optical parameters by comparing the composite layer calculation values ​​of total transmittance, straight transmittance, and reflectance based on the generated optical parameters with the composite layer measurement values.

[0071] The reason why the parameter estimation method of this embodiment can estimate optical parameters with high accuracy is presumed to be as follows.

[0072] When the target material is a composite material, it is treated as a single, uniform material. However, depending on the individual materials contained in the composite material, strict uniformity may not be achieved during the lamination process, such as laminating layers of the target material onto a substrate. Furthermore, when estimating the refractive index, reflection, absorption, and scattering affect the composite layer measurement. For optical parameters to be estimated, such as refractive index, scattering coefficient, absorption coefficient, and scattering anisotropy parameter, there may be multiple optimal solutions that minimize the error between the measured and calculated values. In this case, even if an optical parameter can accurately reproduce one measurement, it may not be able to accurately reproduce the measurement of a composite layer with layers of the target material of a different thickness, or a composite layer using a different support material or substrate material.

[0073] The parameter estimation system 100 of this embodiment estimates optical parameters using composite layer measurements for both the first and second irradiation cases. Therefore, it is possible to estimate optical parameters based on two measurements taken under different conditions for a single target material, thus enabling highly accurate estimation of optical parameters. In this way, by estimating optical parameters based on multiple measurements, it is considered possible to estimate highly accurate and reproducible optical parameters.

[0074] Furthermore, the parameter estimation system 100 can utilize measurement values ​​from multiple composite layers, each consisting of layers of the target material with different film thicknesses, which are laminated between the support layer and the substrate. This allows the parameter estimation system 100 to obtain multiple measurement values ​​for the same target material measured under different conditions, enabling the estimation of optical parameters with higher accuracy and reproducibility.

[0075] Figures 5A and 5B show the evaluation results, which assess the accuracy of the estimated optical parameters of the target material.

[0076] The accuracy of the estimation results for the optical parameters of the target material shown in Figures 5A and 5B was evaluated as a score based on the Mean Absolute Error (MAE) or Root Mean Squared Error (RMSE) of the difference (i.e., error) between the composite layer calculated value using the optical parameters of the target material estimated by the parameter estimation system 100 etc. based on each estimation condition, and the composite layer measured value (actual measurement value). The accuracy of the estimation results for the optical parameters of the target material shown in Figures 5A and 5B was evaluated three times for each estimation condition.

[0077] "Estimation Condition 1" corresponds to the case where the optical parameters of the target material are estimated using composite layer measurements taken only during the first irradiation in a composite layer containing a target material layer of one specified thickness between the support layer and the substrate. "Estimation Condition 2" corresponds to the case where, in addition to Estimation Condition 1, the optical parameters of the target material are estimated using composite layer measurements taken during the second irradiation in a composite layer containing the target material layer of the same one specified thickness. "Estimation Condition 3" corresponds to the case where the optical parameters of the target material are estimated using composite layer measurements taken only during the first irradiation in each of the composite layers having target material layers of three specified thicknesses between the support layer and the substrate. "Estimation Condition 4" corresponds to the case where, in addition to Estimation Condition 3, the optical parameters of the target material are estimated using composite layer measurements taken during the second irradiation in each of the composite layers containing the target material layers of the three specified thicknesses.

[0078] In all estimation conditions, the same values ​​were used for the optical parameters of the support material and substrate material, which were estimated in advance according to the reference layer measurement process and the reference layer estimation process.

[0079] As shown in Figures 5A and 5B, comparing the evaluation results of estimation condition 1 and estimation condition 2, estimation condition 2, which further uses composite layer measurements for the second irradiation case, showed improved evaluation results for the estimated optical parameters of the target material.

[0080] Furthermore, comparing the evaluation results of estimation condition 3 and estimation condition 4, estimation condition 4, which further utilized composite layer measurements in the case of the second irradiation, showed improved evaluation results for the estimated optical parameters of the target material.

[0081] Furthermore, comparing the evaluation results of estimation condition 2 and estimation condition 4, estimation condition 4, which further used composite layer measurements for the first and second irradiation cases for the target material layer with the film thickness of the three conditions, showed improved evaluation results for the estimated optical parameters of the target material.

[0082] The parameters of the target material estimated by estimation condition 2 or 4 are estimated using composite layer measurements (actual values) of a composite layer that includes a layer made of the target material between the support layer and the substrate in the reference layer. Therefore, the transmittance, directional transmittance, and reflectance of the composite layer when actually used can be reproduced with high accuracy. In conventional technology, the parameters of the target material were estimated using composite layer measurements of a composite layer that includes a layer made of the target material on a support layer or a composite layer that includes a layer made of the target material on a substrate. However, since composite layer measurements obtained from a composite layer with a different structure from the composite layer actually used are used, the influence of the substrate (for example, the presence of the substrate and scattering caused by the interface between the substrate and the target material) is not sufficiently considered. This is considered one of the reasons why the transmittance, directional transmittance, and reflectance of the composite layer when actually used cannot be reproduced with high accuracy. Therefore, the parameter estimation system 100 estimates the optical parameters of the target material using composite layer measurements (actual values) of a composite layer that includes a layer made of the target material between the support layer and the substrate in the reference layer, for example, the parameters of the target material estimated by estimation condition 2 or 4. As a result, the parameter estimation system 100 can estimate the optical parameters of the target material, for example, by further considering the influence of the substrate, and can reproduce the transmittance, directional transmittance, and reflectance of the composite layer when actually used with high accuracy.

[0083] Furthermore, depending on the properties of the target material, the accuracy of estimating the optical parameters of the target material may be limited. For example, if it is possible to create a composite layer having target material layers of different thicknesses, as in estimation condition 3, it may be possible to predict the parameters of the target material with sufficient accuracy. However, if it is difficult to thin the target material, it is difficult to change the conditions for the thickness at which composite layer measurements can be obtained, as in the estimation under estimation condition 3, and as a result, the accuracy of the estimated optical parameters of the target material may be limited. Also, for example, if the target material has high light absorption, the difference between each composite layer measurement value of multiple thicknesses may become small in the estimation under estimation condition 3. In this case, the influence of errors (e.g., measurement errors) in the difference between each composite layer measurement value of multiple thicknesses becomes relatively large, and the accuracy of the estimated optical parameters of the target material may be limited. Therefore, the parameter estimation system 100 estimates the optical parameters of the target material using estimation condition 2, with reference layer measurement values ​​of a reference layer consisting of a support layer and a substrate, and composite layer measurement values ​​of a single composite layer formed by laminating a layer of the target material between the support layer and the substrate. As a result, the parameter estimation system 100 can estimate the optical parameters of a target material with high accuracy, even when it is not possible to create multiple composite layers, such as in estimation condition 3, or when the target material has high light absorption properties.

[0084] Next, with reference to Figure 6, an example of a hardware configuration when the parameter estimation system 100 is implemented by the computer 600 will be described. Figure 6 is a diagram showing an example of the hardware configuration of the computer 600.

[0085] As shown in Figure 6, the computer 600 includes, for example, a processor 601, memory 602, storage device 603, input I / F unit 604, data I / F unit 605, communication I / F unit 606, and display device 607.

[0086] Computer 600 may be, for example, a server computer, a personal computer (e.g., a desktop, laptop, tablet, etc.), a media computer platform (e.g., a cable, satellite set-top box, digital video recorder, etc.), a handheld computer device (e.g., a PDA, email client, etc.), or any other type of computer or communication platform.

[0087] The processor 601 is a control unit that controls various processes in the computer 600 by executing programs stored in the memory 602.

[0088] Memory 602 is a storage medium such as RAM (Random Access Memory). Memory 602 temporarily stores the program code of the program executed by the processor 601, as well as data required during program execution.

[0089] The storage device 603 is a non-volatile storage medium such as a hard disk drive (HDD) or flash memory. The storage device 603 stores the operating system and various programs necessary to implement the above configurations.

[0090] The input interface unit 604 is a device for receiving input from the user. The input interface unit 604 can be, for example, a keyboard, mouse, touch panel, various sensors, or a wearable device. The input interface unit 604 may be connected to the computer 600 via an interface such as USB (Universal Serial Bus).

[0091] The data I / F unit 605 is a device for inputting data from outside the computer 600. The data I / F unit 605 is, for example, a drive device for reading data stored on various storage media. The data I / F unit 605 may be located outside the computer 600. If the data I / F unit 605 is located outside the computer 600, it is connected to the computer 600 via an interface such as USB.

[0092] The communication interface unit 606 is a device for performing data communication with external devices of the computer 600 via a network such as the Internet, either by wire or wireless connection. The communication interface unit 606 may be located outside the computer 600. If the communication interface unit 606 is located outside the computer 600, it is connected to the computer 600 via an interface such as USB.

[0093] The display device 607 is a device for displaying various types of information. The display device 607 may be, for example, a liquid crystal display, an organic EL (Electro-Luminescence) display, or a display for a wearable device. The display device 607 may be located outside the computer 600. If the display device 607 is located outside the computer 600, it is connected to the computer 600, for example, via a display cable. Furthermore, if a touch panel is used as the input I / F unit 604, the display device 607 may be integrated with the input I / F unit 604.

[0094] One embodiment of the present invention has been described above. The parameter estimation system 100 acquires reference layer measurements at predetermined film thicknesses of a support layer made of a support material and a substrate made of a substrate material, estimates the optical parameters of the support material and the substrate material based on the reference layer measurements, acquires composite layer measurements for the first irradiation case and the second irradiation case of a composite layer having a layer made of a target material of a predetermined film thickness between the support layer and the substrate, and estimates the optical parameters of the target material based on the composite layer measurements and the optical parameters of the reference layer. As a result, the parameter estimation system 100 can improve the accuracy of estimating the optical parameters of various materials, in particular materials for which it is difficult to measure, for example, total transmittance, direct transmittance, and reflectance.

[0095] Furthermore, the parameter estimation system 100 searches for and estimates the optical parameters of the support material and substrate material that minimize an evaluation function that evaluates the error between the reference layer measurement value and the reference layer calculation value, which is at least one of the total transmittance, directional transmittance, and reflectance calculated based on the optical parameters of the generated support material and substrate material. It can also search for and estimate the optical parameters of the target material that minimize an evaluation function that evaluates the error between the composite layer measurement value for the first and second irradiation cases and the composite layer calculation value, which is at least one of the total transmittance, directional transmittance, and reflectance of the composite layer for the first and second irradiation cases, calculated based on the optical parameters of the generated target material and the optical parameters of the support material and substrate material. As a result, the parameter estimation system 100 can improve the accuracy of estimating the optical parameters of various materials using the inverse Monte Carlo method.

[0096] Furthermore, the parameter estimation system 100 can obtain composite layer measurements for each of a plurality of composite layers, each formed by laminating layers of target materials with different film thicknesses between a support layer and a substrate, for the case of either the first or second irradiation, and composite layer measurements for at least one of the plurality of composite layers for both the first and second irradiations. In this case, the parameter estimation system 100 may also obtain composite layer measurements for each of the plurality of composite layers for both the first and second irradiations. This allows the parameter estimation system 100 to improve the accuracy of estimating the optical parameters of various materials.

[0097] Furthermore, the parameter estimation system 100 can acquire composite layer measurements for each of multiple composite layers, each containing one of several different substrates. This allows the parameter estimation system 100 to improve the accuracy of estimating optical parameters for various materials, particularly those for which it is difficult to measure total transmittance, directional transmittance, and reflectance, by using composite layer measurements with different substrate conditions.

[0098] Furthermore, the parameter estimation system 100 can estimate the optical parameters of a target material that is a composite material consisting of multiple materials, and is a non-self-supporting film material in which it is difficult to measure the total transmittance, directional transmittance, and reflectance of a target material layer consisting only of the target material, particularly a target material that is a photosensitive resin composition. This allows the parameter estimation system 100 to improve the accuracy of estimating the optical parameters of various materials.

[0099] This embodiment is provided to facilitate understanding of the present invention and is not intended to limit its interpretation. The present invention may be modified or improved without departing from its spirit, and equivalents thereof are also included.

[0100] Furthermore, in this invention, "part" does not merely mean a physical means, but also includes cases where the functions of that "part" are realized by software. Also, even if the functions of one "part" or device are realized by two or more physical means, devices, or software, the functions of two or more "parts" or devices may be realized by one physical means, device, or software. [Explanation of symbols]

[0101] 100 Parameter estimation system, 110 Storage unit, 120 Reference layer measurement value acquisition unit, 130 Reference layer estimation unit, 140 Composite layer measurement value acquisition unit, 150 Target material estimation unit, 200 Measuring device

Claims

1. Executed by a computer, A composite layer measurement value acquisition step involves obtaining composite layer measurement values, which are at least one of the total transmittance, straight transmittance, and reflectance of the composite layer, for each of the first and second irradiation cases, by optical measurement by first irradiation, in which light of a predetermined wavelength is irradiated from the support layer side of the composite layer, and second irradiation, in which light of a predetermined wavelength is irradiated from the substrate side of the composite layer, respectively. A target material estimation step, which estimates the optical parameters of the target material based on the composite layer measurement values ​​obtained in the composite layer measurement value acquisition step and the optical parameters including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and the substrate material, A parameter estimation method that includes this.

2. The target material estimation step includes searching for and estimating the optical parameters of the target material that minimize an evaluation function that evaluates the error between the composite layer measurements obtained in the composite layer measurement acquisition step for the first and second irradiation cases, and the composite layer calculation value, which is calculated based on the optical parameters of the generated target material and the optical parameters of the support material and the substrate material, and is at least one of the total transmittance, direct transmittance and reflectance of the composite layer for the first and second irradiation cases, respectively. The parameter estimation method according to claim 1.

3. The composite layer is a plurality of composite layers, each consisting of a target material with a different thickness, laminated between the support layer and the substrate. The composite layer measurement acquisition step includes acquiring the composite layer measurement value for each of the plurality of composite layers in the case of the first irradiation or the second irradiation, and the composite layer measurement value for at least one of the plurality of composite layers in the case of both the first irradiation and the second irradiation. The parameter estimation method according to claim 1 or 2.

4. The parameter estimation method according to claim 3, wherein the composite layer measurement value acquisition step includes acquiring the composite layer measurement values ​​for each of the plurality of composite layers in the case of the first irradiation and the second irradiation.

5. The composite layer measurement value acquisition step involves acquiring the composite layer measurement value for each of a plurality of composite layers, each containing one of a plurality of different substrates. The parameter estimation method according to claim 1 or 2.

6. The parameter estimation method according to claim 1 or 2, wherein the target material is a composite material consisting of multiple materials, and is a non-self-supporting film material for which it is difficult to measure the total transmittance, straight transmittance, and reflectance of a target layer consisting only of the target material.

7. The parameter estimation method according to claim 6, wherein the target material is a photosensitive resin composition.

8. A composite layer measurement value acquisition unit obtains composite layer measurement values, which are at least one of the total transmittance, straight transmittance, and reflectance of a composite layer, having a layer of a target material with a predetermined thickness between a support layer made of a support material and a substrate made of a substrate material, by optical measurement by first irradiation, in which light of a predetermined wavelength is irradiated onto the composite layer from the support layer side, and second irradiation, in which light of a predetermined wavelength is irradiated onto the composite layer from the substrate side. A target material estimation unit estimates the optical parameters of the target material based on the composite layer measurement values ​​obtained by the composite layer measurement value acquisition unit and optical parameters including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and the substrate material. A parameter estimation system equipped with the following features.

9. On the computer, A composite layer measurement value acquisition process is performed to obtain composite layer measurement values ​​that are at least one of the total transmittance, straight transmittance, and reflectance of a composite layer, which has a layer of a target material with a predetermined thickness between a support layer made of a support material and a substrate made of a substrate material, by optical measurement by first irradiation in which light of a predetermined wavelength is irradiated onto the composite layer from the support layer side and second irradiation in which light of a predetermined wavelength is irradiated onto the composite layer from the substrate side, A target material estimation process that estimates the optical parameters of the target material based on the composite layer measurement values ​​obtained in the composite layer measurement value acquisition process and optical parameters including the absorption coefficient, scattering coefficient, and scattering anisotropy parameter of the support material and the substrate material, A parameter estimation program to execute the command.

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