Metal mesh exposure system and method for sapphire optical windows

Abstract

This invention relates to the field of optical window technology, and more particularly to a metal mesh grating exposure system and method for sapphire optical windows. The method includes the following steps: acquiring substrate feature data, photoresist feature data, exposure light source feature data, and metal mesh grating pattern structure feature data of the sapphire optical window; predicting standing wave effects and determining exposure dose fluctuation characteristic parameters under the influence of standing wave effects; analyzing the coupling degree between the metal mesh grating pattern structure and the standing wave effect, and determining the standing wave coupling characteristic parameters under the influence of the metal mesh grating pattern structure; determining the exposure dose fluctuation range in different regions of the sapphire optical window; and providing early warning of metal mesh grating exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window. This invention improves the process stability and reliability of metal mesh grating exposure by quantifying the standing wave amplification effect and periodic resonance effect caused by the metal mesh grating pattern structure.

Description

Technical Field

[0001] This invention relates to the field of optical window technology, and more particularly to a metal mesh exposure system and method for sapphire optical windows. Background Technology

[0002] Sapphire material is widely used in optical windows, infrared detection windows, and high-power optical systems due to its excellent mechanical strength, high-temperature resistance, and good optical transmittance. To achieve electromagnetic shielding, optical windows require the formation of a metal mesh structure on their surface using photolithography. The pattern precision and morphological quality of the metal mesh directly affect optical transmittance, resistivity uniformity, and reliability.

[0003] However, during photolithography on a sapphire substrate, the high refractive index of sapphire causes multiple reflections and interferences of the exposure light within the photoresist layer, resulting in a standing wave effect distributed along the thickness of the photoresist. This standing wave effect causes periodic fluctuations in the exposure dose within the photoresist along its thickness, leading to problems such as rough edges, sidewall wobble, or uneven development. Furthermore, when the metal mesh pattern has high pattern density and a complex topology, the local intensity of the standing wave field can be further amplified through scattering and diffraction, resulting in significant differences in the exposure dose distribution across different regions.

[0004] Current technologies for suppressing standing wave (SWR) effects largely rely on empirical methods such as anti-reflective layer design, optimized photoresist thickness, or adjusted exposure dose, lacking a systematic approach for quantitative analysis of specific pattern structures. Especially when metal mesh gratings have different periods, linewidths, and cross-structure densities, the degree of coupling enhancement to SWRs varies across different regions, making it difficult for traditional overall dose setting methods to accurately predict the risk of localized exposure failure. Therefore, there is an urgent need for a quantitative evaluation method that comprehensively considers the optical properties of the sapphire substrate, photoresist process parameters, and the structural characteristics of the metal mesh grating, enabling spatial prediction of exposure dose fluctuations and providing early warning of exposure quality in conjunction with the photoresist process window. Summary of the Invention

[0005] To overcome the defects and shortcomings of existing technologies, this invention provides a metal mesh exposure system and method for sapphire optical windows. By quantifying the standing wave amplification effect and periodic resonance effect caused by the metal mesh pattern structure, the process stability and reliability of metal mesh exposure are improved.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for exposing a metal mesh grid for a sapphire optical window, comprising: S1, acquiring substrate feature data, photoresist feature data, exposure light source feature data, and pattern structure feature data of the sapphire optical window, wherein the photoresist feature data includes the refractive index of the photoresist material and the photoresist exposure dose process window; S2, predicting the standing wave effect based on the substrate feature data, photoresist feature data, and exposure light source feature data, and determining the exposure dose fluctuation feature parameters under the influence of the standing wave effect; S3, analyzing the coupling degree between the metal mesh grid pattern structure and the standing wave effect based on the pattern structure feature data, and determining the standing wave coupling feature parameters under the influence of the metal mesh grid pattern structure; S4, determining the exposure dose fluctuation range of different regions of the sapphire optical window based on the exposure dose fluctuation range and the matching relationship between the photoresist exposure dose process window; and S5, providing an early warning of the metal mesh grid exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window.

[0008] Further, in step S2, determining the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect includes:

[0009] S21. Construct a layered dielectric optical structure model containing an air layer, a photoresist layer, and a sapphire substrate layer based on substrate feature data, photoresist feature data, and exposure light source feature data.

[0010] S22. The optical field propagation analysis of the layered medium optical structure model is performed by the thin film optical transfer matrix method to obtain the predicted results of the light intensity distribution of the exposed light along the thickness direction in the photoresist layer.

[0011] S23. Based on the light intensity distribution prediction results, determine the spatial spacing between adjacent light intensity peaks in the photoresist thickness direction, and use the average spatial spacing as the exposure dose fluctuation period.

[0012] S24. Based on the light intensity distribution prediction results, determine the maximum and minimum light intensity values ​​in the light intensity distribution, and use the difference between the maximum and minimum light intensity values ​​as the exposure dose fluctuation range.

[0013] S25. The exposure dose fluctuation period and exposure dose fluctuation amplitude are used as characteristic parameters of exposure dose fluctuation to characterize the intensity of the standing wave effect under the reflection of the sapphire substrate.

[0014] Further, in step S3, determining the standing wave coupling characteristic parameters under the influence of the metal mesh pattern structure includes:

[0015] S31. Divide the graphic area of ​​the sapphire optical window into different sub-regions, and extract the topological structure feature parameters of the metal mesh in each sub-region based on the graphic structure feature data. The topological structure feature parameters include the line width, period, and intersection density of the metal mesh.

[0016] S32. Based on rigorous coupled-wave analysis and combined with topological characteristic parameters, a coupled field model of pattern structure and standing wave effect is constructed. The influence of metal mesh pattern structure on the redistribution of light intensity inside photoresist is analyzed, and the light intensity redistribution prediction results are obtained.

[0017] S33. Based on the light intensity redistribution prediction results, determine the standing wave amplification coefficient and periodic resonance coefficient of the metal mesh pattern structure for the standing wave effect, and use the standing wave amplification coefficient and periodic resonance coefficient as standing wave coupling characteristic parameters to characterize the enhancement degree of the standing wave effect by the metal mesh pattern structure.

[0018] Further, determining the standing wave amplification factor in step S33 includes:

[0019] S331. Based on the light intensity distribution prediction results in step S22, extract the average light intensity in each sub-region and use the average light intensity as the reference light intensity value without the influence of graphic structure.

[0020] S332. Based on the light intensity redistribution prediction results, extract the mean redistributed light intensity in each sub-region, and use the mean redistributed light intensity as the coupled light intensity value under the influence of the metal mesh pattern structure.

[0021] S333. The ratio of the coupled light intensity value to the reference light intensity value is used as the standing wave amplification factor to characterize the degree of local enhancement of the standing wave amplitude characteristics by the grid topology.

[0022] Further, determining the periodic resonance coefficient in step S33 includes:

[0023] S334. Determine the horizontal spatial frequency based on the horizontal period of the metal mesh, where the horizontal spatial frequency is the reciprocal of the period of the metal mesh.

[0024] S335. Take the reciprocal of the exposure dose fluctuation period as the vertical spatial frequency, and calculate the sine of the angle between the propagation direction of the exposure light source and the pattern direction of the metal mesh as the direction matching factor.

[0025] S336. The absolute value of the product of the ratio of the horizontal spatial frequency to the vertical spatial frequency and the direction matching factor is used as the periodic resonance coefficient to characterize the dose fluctuation superposition effect caused by the matching degree between the grid geometric period and the standing wave period.

[0026] Further, in step S4, determining the range of exposure dose fluctuations at different spatial locations of the sapphire optical window includes:

[0027] S41. Determine the baseline dose fluctuation amplitude based on the exposure dose fluctuation amplitude and the preset exposure dose range;

[0028] S42. Based on the sub-region division results in step S33, extract the standing wave amplification coefficient and periodic resonance coefficient corresponding to each sub-region, and use the product of the standing wave amplification coefficient and the periodic resonance coefficient as the local coupling enhancement coefficient corresponding to the sub-region.

[0029] S43. Calculate the exposure dose fluctuation amplitude of each sub-region based on the reference dose fluctuation amplitude and the local coupling enhancement coefficient to obtain the exposure dose fluctuation range corresponding to each sub-region.

[0030] Furthermore, step S5 includes providing an early warning of the metal mesh exposure quality, comprising:

[0031] The minimum and maximum exposure dose values ​​of each sub-region are compared with the lower and upper limits of the photoresist exposure dose process window, respectively. If the exposure dose fluctuation range falls within the range of the photoresist exposure dose process window, no metal grid exposure quality warning is issued; otherwise, a metal grid exposure quality warning is issued.

[0032] In a second aspect, the present invention provides a metal mesh exposure system for sapphire optical windows, comprising:

[0033] The data acquisition module is used to acquire substrate feature data, photoresist feature data, exposure light source feature data, and metal mesh grid pattern structure feature data of the sapphire optical window. The photoresist feature data includes the refractive index of the photoresist material and the photoresist exposure dose process window.

[0034] The standing wave effect prediction module is used to predict the standing wave effect based on substrate feature data, photoresist feature data and exposure light source feature data, and to determine the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect.

[0035] The standing wave coupling analysis module is used to analyze the coupling degree between the metal mesh grid pattern structure and the standing wave effect based on the pattern structure feature data, and to determine the standing wave coupling characteristic parameters under the influence of the metal mesh grid pattern structure.

[0036] The fluctuation range determination module is used to determine the exposure dose fluctuation range of different regions of the sapphire optical window based on the exposure dose fluctuation characteristic parameters and the standing wave coupling characteristic parameters.

[0037] The exposure quality early warning module is used to provide early warning of metal mesh exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window.

[0038] Thirdly, the present invention provides an electronic device, comprising: a processor and a memory, wherein the memory stores a computer program that can be called by the processor, and the processor executes a metal mesh exposure method for a sapphire optical window by calling the computer program stored in the memory.

[0039] Fourthly, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform a metal mesh exposure method for a sapphire optical window.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) This invention constructs a layered medium optical structure model and combines it with the thin film optical transfer matrix method to predict the light intensity distribution in the photoresist thickness direction, thereby quantifying the exposure dose fluctuation period and exposure dose fluctuation amplitude, thus realizing the quantitative characterization of the standing wave effect of sapphire substrate.

[0042] (2) This invention establishes a coupling model between the pattern structure and the standing wave field by introducing a rigorous coupled wave analysis method, thereby quantifying the standing wave amplification effect and periodic resonance effect caused by the pattern structure, realizing closed-loop control of pattern coupling enhancement analysis and space risk warning, and improving the forming consistency and process stability of the metal mesh pattern of the sapphire optical window. Attached Figure Description

[0043] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0044] Figure 1 This is a schematic flowchart of the metal mesh exposure method for sapphire optical windows provided in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the standing wave effect provided in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the analysis process for standing wave coupling characteristic parameters provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of a metal grid exposure system for sapphire optical windows provided in an embodiment of the present invention. Detailed Implementation

[0048] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0049] Please see Figure 1 , Figure 1This is a schematic diagram of the overall process of the metal mesh exposure method for sapphire optical windows provided in an embodiment of the present invention, which specifically includes the following steps:

[0050] S1. Obtain the substrate characteristic data, photoresist characteristic data, exposure light source characteristic data, and metal mesh pattern structure characteristic data of the sapphire optical window. The photoresist characteristic data includes the refractive index of the photoresist material and the photoresist exposure dosage process window. Specifically, the substrate characteristic data includes the complex refractive index of the sapphire substrate layer at the exposure wavelength, which can be obtained by actual measurement of the sapphire optical window substrate using an ellipsometer, or by using the standard complex refractive index parameters at the corresponding exposure wavelength provided by the sapphire material supplier. The photoresist characteristic data includes the refractive index of the photoresist material and the photoresist exposure dosage process window, which can be obtained by technical analysis provided by the photoresist supplier. Technical parameter acquisition; Exposure light source characteristic data includes incident light wavelength, incident angle, polarization state (TE polarization or TM polarization), and incident light intensity, which can be obtained through the parameter setting interface of the exposure equipment; Graphic structure characteristic data of the metal mesh includes the topological structure characteristic parameters of the metal mesh, including the line width, period, and intersection density of the metal mesh, which can be obtained by measuring the metal mesh design layout using a high-precision optical microscope or scanning electron microscope (SEM). Among them, the line width and period can be obtained by directly measuring the geometric dimensions of the metal mesh, and the intersection density can be calculated by counting the number of cross intersections of the metal mesh per unit area;

[0051] S2. Based on substrate feature data, photoresist feature data and exposure light source feature data, predict the standing wave effect and determine the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect.

[0052] Please see Figure 2 , Figure 2This is a schematic diagram of the standing wave effect provided in an embodiment of the present invention. During the exposure process, the refractive index of the photoresist does not match that of the substrate material, resulting in interference between the reflected light and the incident light formed on the substrate surface, generating standing waves. The generation of the standing wave effect causes a decrease in the resolution of the photoresist and also impairs the verticality of the sidewall curves of the photoresist's appearance shape. Therefore, by analyzing the optical characteristics of the sapphire substrate, photoresist layer, and exposure light source, a layered medium optical structure model is constructed to quantify the exposure dose fluctuation period and amplitude, thereby determining the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect. The core of this method is to predict the light intensity distribution in the photoresist thickness direction using the layered medium optical model, revealing the interference phenomenon caused by reflection from the high refractive index interface of sapphire and its periodic dose fluctuation characteristics. By transforming the physical phenomenon of standing waves into quantifiable periodic and amplitude parameters, not only can the degree of influence of standing waves on the photolithography process be clarified, but also basic reference values ​​are provided for subsequent pattern structure coupling analysis, realizing a technical improvement from qualitative understanding of the existence of standing waves to quantitative description of standing wave intensity. The determination of the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect includes:

[0053] S21. Based on substrate feature data, photoresist feature data, and exposure light source feature data, construct a layered dielectric optical structure model including an air layer, a photoresist layer, and a sapphire substrate layer. Specifically, based on substrate feature data, photoresist feature data, and exposure light source feature data, determine the complex refractive index parameters of each layer at the exposure wavelength, including the refractive index of the air layer, the complex refractive index of the photoresist layer, and the complex refractive index of the sapphire substrate layer. Simultaneously, determine the physical thickness of the photoresist layer based on the photoresist feature data, and determine the incident light wavelength, incident angle, and polarization state (TE polarization) based on the exposure light source feature data. (or TM polarization), and regard the air layer and sapphire substrate as a semi-infinite thickness medium to construct a layered medium optical structure model. The light propagation direction of the layered medium optical structure model is perpendicular to the surface of the sapphire optical window. From top to bottom, it is divided into three continuous medium layers: a semi-infinite thickness air layer, a photoresist layer (thickness is the physical thickness of the photoresist layer), and a semi-infinite thickness sapphire substrate layer. The interfaces of each layer satisfy Fresnel boundary conditions. The layered medium optical structure model is used to simulate the reflection, transmission, and interference processes of exposure light in the multilayer medium, providing a structural basis for subsequent prediction of standing wave effects.

[0054] S22. The optical field propagation analysis of the layered medium optical structure model is performed by the thin film optical transfer matrix method to obtain the predicted light intensity distribution of the exposed light along the thickness direction in the photoresist layer. Specifically, the thin film optical transfer matrix method describes the propagation of electromagnetic waves in a multilayer medium in the form of a matrix. The motion law in the propagation process of each layer of the medium satisfies the Maxwell equations, and the electromagnetic field boundary conditions between layers are satisfied. This method is a commonly used and effective method in optical thin film calculation and design.

[0055] In a specific embodiment of the present invention, the steps for optical field propagation analysis using the thin-film optical transfer matrix method can be as follows: selecting the corresponding characteristic admittance expression based on the polarization type of the incident light, and calculating the optical admittance of each layer respectively. and optical phase thickness ; Construct 2×2 feature matrices for the photoresist layer and the sapphire substrate layer respectively. The characteristic matrix is ​​in the form of In the formula This represents the phase evolution of the tangential component of the electric (or magnetic) field as it passes through the film layer. This represents the propagation contribution term from the coupling of the electric field component to the magnetic field component, where... To represent a complex unit, This represents the propagation contribution term from the coupling of the magnetic field component to the electric field component. Based on the principle of superposition of layered media, the characteristic matrices of each layer are multiplied sequentially to obtain the total transmission matrix of the layered media optical structure model. The calculation of the total transmission matrix follows the matrix multiplication rule, i.e., the total transmission matrix is ​​the sequential product of the air layer transmission matrix, the photoresist layer transmission matrix, and the sapphire substrate layer transmission matrix. Based on the total transmission matrix and Fresnel reflection and transmission theory, the interface reflection coefficients between the air layer and the photoresist layer, and between the photoresist layer and the sapphire substrate layer are calculated. The optical structure of the layered media is then calculated using the principle of superposition interference. The model is constructed based on the total reflection coefficient. The light field amplitude distribution at any depth along the thickness direction inside the photoresist layer is calculated based on the total reflection coefficient and the incident light intensity. The total light field amplitude at any depth inside the photoresist layer is obtained by superimposing the forward incident light field amplitude and the reflected light field amplitude at each interface. The light intensity at any depth inside the photoresist layer is calculated according to the relationship between light intensity and light field amplitude (light intensity is the square of the light field amplitude modulus). The light intensity distribution curve along the thickness direction inside the photoresist layer is obtained. The light intensity distribution curve is the predicted result of the light intensity distribution of the exposure light along the thickness direction inside the photoresist layer, which is used to describe the light intensity fluctuation characteristics caused by the standing wave effect.

[0056] S23. Based on the light intensity distribution prediction results, determine the spatial spacing between adjacent light intensity peaks in the photoresist thickness direction, and use the average spatial spacing as the exposure dose fluctuation period. The exposure dose fluctuation period is the periodic spatial characteristic of the standing wave interference phenomenon in the photoresist thickness direction, which is jointly determined by the optical characteristics of the sapphire substrate, photoresist and exposure light source. By quantifying the exposure dose fluctuation period, the spatial distribution law of the standing wave effect can be accurately captured, and the interval characteristics of the dose fluctuation in the photoresist thickness direction can be clarified. This provides a quantitative basis for subsequent analysis of the matching relationship between the metal mesh pattern period and the standing wave period and for revealing the generation mechanism of the periodic resonance effect.

[0057] S24. Based on the light intensity distribution prediction results, determine the maximum and minimum light intensity values ​​in the light intensity distribution, and use the difference between the maximum and minimum light intensity values ​​as the exposure dose fluctuation amplitude. The exposure dose fluctuation amplitude is a quantitative indicator that characterizes the intensity of the standing wave effect. The magnitude of the exposure dose fluctuation amplitude directly reflects the strength of the superposition interference between the incident light and the substrate reflected light.

[0058] S25. The exposure dose fluctuation period and exposure dose fluctuation amplitude are used as characteristic parameters of exposure dose fluctuation to characterize the intensity of the standing wave effect under the reflection of the sapphire substrate, thereby providing a basic reference for the subsequent coupling analysis of the metal mesh pattern structure and the standing wave effect, as well as the quantitative calculation of the exposure dose fluctuation range of each sub-region.

[0059] S3. Based on the characteristic data of the graphic structure, analyze the coupling degree between the graphic structure of the metal mesh and the standing wave effect, and determine the standing wave coupling characteristic parameters under the influence of the graphic structure of the metal mesh.

[0060] Based on the structural characteristics of metal mesh patterns, the coupling degree between the pattern structure and the standing wave effect is analyzed. The standing wave amplification factor and periodic resonance factor are determined. Furthermore, the topological characteristics of the metal mesh, such as linewidth, period, and intersection density, are considered to model and analyze the scattering, diffraction, and local enhancement effects of the pattern on the light field. This allows for the quantitative characterization of the enhancement effect of the pattern structure on the standing wave in different regions. The standing wave amplification factor reflects the degree of enhancement of local light intensity amplitude, while the periodic resonance factor characterizes the superposition effect caused by the matching degree between the pattern period and the standing wave period. The standing wave field, determined by material and optical parameters, is then extended to a coupled field model that includes pattern geometry, making the standing wave influence analysis closer to the actual pattern distribution and improving the accuracy of regional difference prediction. (See [link to relevant documentation]). Figure 3 , Figure 3 This is a schematic diagram of the analysis process for standing wave coupling characteristic parameters provided in an embodiment of the present invention. The process for determining the standing wave coupling characteristic parameters under the influence of the metal mesh grid pattern structure includes:

[0061] S31. Divide the graphic area of ​​the sapphire optical window into different sub-regions, and extract the topological structure feature parameters of the metal mesh in each sub-region based on the graphic structure feature data. The topological structure feature parameters include the line width, period, and intersection density of the metal mesh.

[0062] S32. Based on rigorous coupled-wave analysis and combined with topological characteristic parameters, a coupled field model of pattern structure and standing wave effect is constructed. The influence of metal mesh pattern structure on the redistribution of light intensity inside photoresist is analyzed, and the light intensity redistribution prediction results are obtained.

[0063] In a specific embodiment of the present invention, the coupled field model is constructed based on the Rigorous Coupled-Wave Analysis (RCWA) method. The Rigorous Coupled-Wave Analysis method is a mature frequency domain electromagnetic field solution method, which is suitable for analyzing optical diffraction and field distribution problems with periodic structures. It can accurately describe the modulation effect of the periodic structure of the metal mesh on the incident light field. The specific steps are as follows: Based on the topological structure characteristic parameters of each sub-region obtained in step S31, a corresponding two-dimensional periodic unit model is constructed. Specifically, a basic periodic unit structure is established based on the linewidth and period of the metal mesh, and the intersection density is mapped to the two-dimensional periodic arrangement parameters within a unit area. In the two-dimensional periodic cell model, the photoresist thickness direction is divided into a multi-layer dielectric structure, including an air layer, a metal mesh layer, a photoresist layer, and a sapphire substrate layer. The material parameters of each layer can be determined with reference to step S21. The light intensity distribution prediction result in step S22 is introduced into the RCWA model as the incident field condition. Specifically, the light intensity distribution prediction result is converted into the corresponding electromagnetic field amplitude distribution and used as the initial boundary condition of the incident field above the metal mesh layer. The metal mesh periodic cell is then expanded using Fourier series to represent its dielectric constant distribution. The frequency components in the two-dimensional space are superimposed, and the coupled wave matrix equation is established. By solving the eigenvalue equation of the coupled wave matrix, the electromagnetic field propagation constants of different diffraction orders and their field distribution in the photoresist layer are obtained. The electromagnetic fields between the air layer, the metal grid layer, the photoresist layer and the sapphire substrate layer are matched and solved in combination with the boundary continuity condition. The electric field intensity distribution inside the photoresist layer in three-dimensional space is obtained, which is used to describe the scattering, diffraction and local field enhancement effect of the metal grid structure on the original standing wave field, that is, to obtain the light intensity redistribution prediction result.

[0064] S33. Based on the light intensity redistribution prediction results, determine the standing wave amplification coefficient and periodic resonance coefficient of the metal mesh pattern structure for the standing wave effect, and use the standing wave amplification coefficient and periodic resonance coefficient as standing wave coupling characteristic parameters to characterize the enhancement degree of the standing wave effect by the metal mesh pattern structure.

[0065] Determining the standing wave amplification factor includes:

[0066] S331. Based on the light intensity distribution prediction results in step S22, extract the average light intensity in each sub-region, and use the average light intensity as the reference light intensity value without the influence of the graphic structure. The reference light intensity value is used as the benchmark light intensity reference without interference from the metal mesh pattern, which is used to eliminate the influence of the metal mesh structure and retain only the light intensity distribution characteristics caused by the standing wave effect itself.

[0067] S332. Based on the light intensity redistribution prediction results, extract the average redistributed light intensity in each sub-region, and use the average redistributed light intensity as the coupled light intensity value under the influence of the metal mesh pattern structure. The coupled light intensity value is used to describe the actual distribution characteristics of the light intensity in the photoresist layer after the metal mesh pattern structure is coupled with the standing wave effect, thereby quantifying the modulation effect of the pattern structure on the original standing wave light field.

[0068] S333. The ratio of the coupled light intensity value to the reference light intensity value is used as the standing wave amplification factor to characterize the degree of local enhancement of the standing wave amplitude characteristics by the grid topology.

[0069] Determining the periodic resonance coefficient includes:

[0070] S334. Determine the horizontal spatial frequency based on the horizontal period of the metal mesh grating. The horizontal spatial frequency is the reciprocal of the period of the metal mesh grating. By converting the geometric periodic characteristics of the metal mesh grating into spatial frequency parameters, it adapts to the quantitative characterization method of periodic structures in optical field analysis.

[0071] S335. The reciprocal of the exposure dose fluctuation period is taken as the vertical spatial frequency, and the sine of the angle between the propagation direction of the exposure light source and the pattern direction of the metal mesh is calculated as the direction matching factor. By converting the periodic characteristics of the standing wave into the vertical spatial frequency corresponding to the horizontal spatial frequency of the metal mesh, the two are compared in the same dimension. At the same time, the influence of the spatial relationship between the propagation direction of the light source and the pattern direction on the periodic resonance effect is quantified by the direction matching factor.

[0072] S336. The absolute value of the product of the ratio of the horizontal spatial frequency to the vertical spatial frequency and the direction matching factor is used as the periodic resonance coefficient to characterize the dose fluctuation superposition effect caused by the matching degree between the grid geometric period and the standing wave period.

[0073] S4. Based on the exposure dose fluctuation characteristic parameters and standing wave coupling characteristic parameters, determine the exposure dose fluctuation range of different regions of the sapphire optical window;

[0074] Based on exposure dose fluctuation characteristic parameters and standing wave coupling characteristic parameters, the spatial quantification calculation of the exposure dose fluctuation range in different regions of the sapphire optical window is performed. By combining the basic exposure dose fluctuation amplitude with the standing wave amplification coefficient and periodic resonance coefficient corresponding to each sub-region, the local exposure dose fluctuation amplitude of different regions is obtained, and the corresponding dose range is further determined. This generates an exposure dose fluctuation map with spatial distribution characteristics, revealing the potential dose differences that may occur in regions with different pattern densities under the same exposure conditions. This transforms exposure dose control from global average control to regional differentiated evaluation, determining the exposure dose fluctuation range at different spatial locations of the sapphire optical window, including:

[0075] S41. Determine the reference dose fluctuation amplitude based on the exposure dose fluctuation amplitude and the preset exposure dose range. Specifically, take the center value of the preset exposure dose range as the reference exposure dose. The preset exposure dose range consists of the lowest effective exposure dose and the highest effective exposure dose that can ensure the photoresist morphology quality meets the requirements. Based on the symmetrical distribution characteristics of the exposure dose fluctuation amplitude relative to the reference exposure dose, calculate the positive deviation of the peak value of the exposure dose fluctuation amplitude from the reference exposure dose and the negative deviation of the valley value of the exposure dose fluctuation amplitude from the reference exposure dose. Select the maximum value of the positive deviation and the negative deviation as the reference dose fluctuation amplitude. The reference dose fluctuation amplitude is used to characterize the intrinsic fluctuation degree of the exposure dose around the reference value under the current substrate and light source conditions, without considering the influence of the pattern structure.

[0076] S42. Based on the sub-region division results in step S33, extract the standing wave amplification coefficient and periodic resonance coefficient corresponding to each sub-region, and use the product of the standing wave amplification coefficient and the periodic resonance coefficient as the local coupling enhancement coefficient corresponding to the sub-region. The local coupling enhancement coefficient is used to describe the dual influence of the metal mesh pattern structure on the standing wave effect, namely the amplitude amplification effect and the periodic resonance superposition effect.

[0077] S43. Calculate the exposure dose fluctuation amplitude of each sub-region based on the reference dose fluctuation amplitude and the local coupling enhancement coefficient to obtain the exposure dose fluctuation range corresponding to each sub-region. Specifically, multiply the reference dose fluctuation amplitude by the local coupling enhancement coefficient of each sub-region to obtain the local exposure dose fluctuation amplitude of each sub-region after pattern structure modulation. Take the center value of the preset exposure dose range as the exposure dose reference value of each sub-region, calculate the difference and sum of the exposure dose reference value and the local exposure dose fluctuation amplitude of each sub-region, and take the difference and sum as the lower limit and upper limit of the exposure dose fluctuation range of the sub-region, respectively, to obtain the exposure dose fluctuation range of each sub-region in the photoresist thickness direction.

[0078] S5. Based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window, perform early warning of metal grid exposure quality.

[0079] By performing interval matching analysis between the exposure dose fluctuation range of each sub-region and the photoresist exposure dose process window, and issuing an exposure quality warning for the metal mesh grid based on the matching results, specifically, when the dose fluctuation range of a certain region is completely within the process window range, its exposure is determined to be in a safe state; when it partially or completely exceeds the process window range, an exposure quality warning is triggered, thereby realizing the direct conversion from physical modeling results to process quality control, enabling the standing wave prediction results to establish a quantitative relationship with the actual process qualification standards, thus predicting potential failure areas before exposure is implemented. The metal mesh grid exposure quality warning includes:

[0080] The minimum and maximum exposure dose values ​​of each sub-region are compared with the lower and upper limits of the photoresist exposure dose process window, respectively. No metal mesh exposure quality warning is issued only when the exposure dose fluctuation range falls within the range of the photoresist exposure dose process window; otherwise, a metal mesh exposure quality warning is issued. Specifically, the metal mesh exposure quality warning can be made by marking the coordinate range of the sub-region whose exposure dose fluctuation range exceeds the photoresist exposure dose process window on the sapphire optical window, which facilitates the accurate location of the problem area.

[0081] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a metal mesh exposure system for sapphire optical windows provided in an embodiment of the present invention, including:

[0082] The data acquisition module 210 is used to acquire substrate feature data, photoresist feature data, exposure light source feature data and metal mesh grid pattern structure feature data of the sapphire optical window. The photoresist feature data includes the refractive index of the photoresist material and the photoresist exposure dose process window.

[0083] The standing wave effect prediction module 220 is used to predict the standing wave effect based on substrate feature data, photoresist feature data and exposure light source feature data, and to determine the exposure dose fluctuation characteristic parameters under the influence of the standing wave effect.

[0084] The standing wave coupling analysis module 230 is used to analyze the coupling degree between the metal mesh grid pattern structure and the standing wave effect based on the pattern structure feature data, and to determine the standing wave coupling characteristic parameters under the influence of the metal mesh grid pattern structure.

[0085] The fluctuation range determination module 240 is used to determine the exposure dose fluctuation range of different regions of the sapphire optical window based on the exposure dose fluctuation characteristic parameters and the standing wave coupling characteristic parameters.

[0086] The exposure quality early warning module 250 is used to provide early warning of metal mesh exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window.

[0087] In this embodiment of the invention, the standing wave effect prediction module 220 is used to predict the standing wave effect based on substrate feature data, photoresist feature data, and exposure light source feature data, and to determine the exposure dose fluctuation characteristic parameters under the influence of the standing wave effect, including:

[0088] A layered dielectric optical structure model containing an air layer, a photoresist layer, and a sapphire substrate layer was constructed based on substrate feature data, photoresist feature data, and exposure light source feature data.

[0089] The optical field propagation analysis of the layered medium optical structure model was performed by the thin film optical transfer matrix method, and the predicted results of the light intensity distribution of the exposed light along the thickness direction in the photoresist layer were obtained.

[0090] Based on the light intensity distribution prediction results, the spatial spacing between adjacent light intensity peaks in the photoresist thickness direction is determined, and the average spatial spacing is used as the exposure dose fluctuation period.

[0091] Based on the light intensity distribution prediction results, the maximum and minimum light intensity values ​​in the light intensity distribution are determined, and the difference between the maximum and minimum light intensity values ​​is taken as the exposure dose fluctuation range.

[0092] Exposure dose fluctuation period and exposure dose fluctuation amplitude are used as characteristic parameters of exposure dose fluctuation to characterize the intensity of standing wave effect under the reflection of sapphire substrate.

[0093] In this embodiment of the invention, the standing wave coupling analysis module 230 is used to analyze the coupling degree between the metal mesh grid pattern structure and the standing wave effect based on the pattern structure feature data, and to determine the standing wave coupling characteristic parameters under the influence of the metal mesh grid pattern structure, including:

[0094] The graphic area of ​​the sapphire optical window is divided into different sub-regions, and the topological structure feature parameters of the metal mesh in each sub-region are extracted based on the graphic structure feature data. The topological structure feature parameters include the line width, period, and intersection density of the metal mesh.

[0095] Based on rigorous coupled-wave analysis and combined with topological characteristic parameters, a coupled field model of patterned structure and standing wave effect is constructed. The influence of metal mesh patterned structure on the redistribution of light intensity inside photoresist is analyzed, and the light intensity redistribution prediction results are obtained.

[0096] Based on the light intensity redistribution prediction results, the standing wave amplification coefficient and periodic resonance coefficient of the metal mesh pattern structure for the standing wave effect are determined, and the standing wave amplification coefficient and periodic resonance coefficient are used as standing wave coupling characteristic parameters to characterize the degree of enhancement of the standing wave effect by the metal mesh pattern structure.

[0097] Determining the standing wave amplification factor includes:

[0098] The average light intensity in each sub-region is extracted based on the light intensity distribution prediction results, and the average light intensity is used as the reference light intensity value without the influence of graphic structure.

[0099] The mean value of redistributed light intensity in each sub-region is extracted based on the light intensity redistribution prediction results, and the mean value of redistributed light intensity is used as the coupled light intensity value under the influence of the metal mesh pattern structure.

[0100] The ratio of the coupled light intensity value to the reference light intensity value is used as the standing wave amplification factor to characterize the degree of local enhancement of the standing wave amplitude characteristics by the grid topology.

[0101] Determining the periodic resonance coefficient includes:

[0102] The horizontal spatial frequency is determined based on the horizontal period of the metal mesh, and the horizontal spatial frequency is the reciprocal of the period of the metal mesh.

[0103] Based on the photoresist development rate, the reciprocal of the exposure dose fluctuation period is used as the vertical spatial frequency, and the sine of the angle between the propagation direction of the exposure light source and the pattern direction of the metal mesh is calculated as the direction matching factor.

[0104] The absolute value of the product of the ratio of horizontal spatial frequency to vertical spatial frequency and the direction matching factor is used as the periodic resonance coefficient to characterize the dose fluctuation superposition effect caused by the matching degree between the grid geometric period and the standing wave period.

[0105] In this embodiment of the invention, the fluctuation range determination module 240 is used to determine the exposure dose fluctuation range of different regions of the sapphire optical window based on the exposure dose fluctuation characteristic parameters and the standing wave coupling characteristic parameters, including:

[0106] The baseline dose fluctuation amplitude is determined based on the exposure dose fluctuation amplitude combined with a preset exposure dose range;

[0107] Based on the sub-region division results in step S33, the standing wave amplification coefficient and periodic resonance coefficient corresponding to each sub-region are extracted, and the product of the standing wave amplification coefficient and the periodic resonance coefficient is used as the local coupling enhancement coefficient corresponding to the sub-region.

[0108] The exposure dose fluctuation amplitude of each sub-region is calculated based on the reference dose fluctuation amplitude and the local coupling enhancement coefficient, thus obtaining the exposure dose fluctuation range corresponding to each sub-region.

[0109] In this embodiment of the invention, the exposure quality early warning module 250 is used to provide early warning of metal mesh exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window, including:

[0110] The minimum and maximum exposure dose values ​​of each sub-region are compared with the lower and upper limits of the photoresist exposure dose process window, respectively. If the exposure dose fluctuation range falls within the range of the photoresist exposure dose process window, no metal grid exposure quality warning is issued; otherwise, a metal grid exposure quality warning is issued.

[0111] The parameters and steps of each unit module in the metal grid exposure system for sapphire optical windows described above can be referred to the parameters and steps in the embodiments of the metal grid exposure method for sapphire optical windows described above, and will not be repeated here.

[0112] Embodiments of the present invention also provide an electronic device, including a memory, a processor, and a communication bus; the memory and the processor are connected via the communication bus. The memory stores a metal mesh exposure method for sapphire optical windows, as provided in the above embodiments, which can be loaded by the processor and executed.

[0113] The memory can be used to store instructions, programs, code, code sets, or instruction sets. The memory may include a program storage area and a data storage area. The program storage area may store instructions for implementing an operating system, instructions for at least one function, and instructions for implementing the metal mesh exposure method for sapphire optical windows provided in the above embodiments, etc. The data storage area may store data involved in the metal mesh exposure method for sapphire optical windows provided in the above embodiments, etc.

[0114] A processor may include one or more processing cores. The processor executes instructions, programs, code sets, or instruction sets stored in memory, and calls data stored in memory to perform various functions and process data according to the present invention. The processor may be at least one of the following: Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), Central Processing Unit (CPU), controller, microcontroller, and microprocessor. It is understood that, for different devices, the electronic devices used to implement the above-described processor functions may also be other types, and the embodiments of the present invention do not specifically limit this.

[0115] A communication bus can include a pathway for transmitting information between the aforementioned components. The communication bus can be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Communication buses can be categorized into address buses, data buses, control buses, etc.

[0116] This invention provides a computer-readable storage medium storing a computer program that can be loaded by a processor and executed as described in the above embodiments for the exposure method of a metal mesh grid for a sapphire optical window.

[0117] In this embodiment of the invention, the computer-readable storage medium can be a tangible device that holds and stores instructions used by an instruction execution device. The computer-readable storage medium can be, but is not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof. Specifically, the computer-readable storage medium can be a portable computer disk, a hard disk, a USB flash drive, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), lectern random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory stick, floppy disk, optical disk, magnetic disk, mechanical encoding device, or any combination thereof.

[0118] The terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0119] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the foregoing concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions claimed in this invention.

Claims

1. A method for exposing a metal mesh grid for sapphire optical windows, characterized in that, include: S1. Obtain substrate feature data, photoresist feature data, exposure light source feature data, and metal mesh grid pattern structure feature data of the sapphire optical window. The photoresist feature data includes the refractive index of the photoresist material and the photoresist exposure dose process window. S2. Based on substrate feature data, photoresist feature data and exposure light source feature data, predict the standing wave effect and determine the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect. S3. Based on the characteristic data of the graphic structure, analyze the coupling degree between the graphic structure of the metal mesh and the standing wave effect, and determine the standing wave coupling characteristic parameters under the influence of the graphic structure of the metal mesh. S4. Based on the exposure dose fluctuation characteristic parameters and standing wave coupling characteristic parameters, determine the exposure dose fluctuation range of different regions of the sapphire optical window; S5. Based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window, perform early warning of metal grid exposure quality.

2. The metal mesh exposure method for sapphire optical windows according to claim 1, characterized in that, The step S2, which determines the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect, includes: S21. Construct a layered dielectric optical structure model containing an air layer, a photoresist layer, and a sapphire substrate layer based on substrate feature data, photoresist feature data, and exposure light source feature data. S22. The optical field propagation analysis of the layered medium optical structure model is performed by the thin film optical transfer matrix method to obtain the predicted results of the light intensity distribution of the exposed light along the thickness direction in the photoresist layer. S23. Based on the light intensity distribution prediction results, determine the spatial spacing between adjacent light intensity peaks in the photoresist thickness direction, and use the average spatial spacing as the exposure dose fluctuation period. S24. Based on the light intensity distribution prediction results, determine the maximum and minimum light intensity values ​​in the light intensity distribution, and use the difference between the maximum and minimum light intensity values ​​as the exposure dose fluctuation range. S25. The exposure dose fluctuation period and exposure dose fluctuation amplitude are used as characteristic parameters of exposure dose fluctuation to characterize the intensity of the standing wave effect under the reflection of the sapphire substrate.

3. The metal mesh exposure method for sapphire optical windows according to claim 1, characterized in that, The step S3, determining the standing wave coupling characteristic parameters under the influence of the metal mesh pattern structure, includes: S31. Divide the graphic area of ​​the sapphire optical window into different sub-regions, and extract the topological structure feature parameters of the metal mesh in each sub-region based on the graphic structure feature data. The topological structure feature parameters include the line width, period, and intersection density of the metal mesh. S32. Based on rigorous coupled-wave analysis and combined with topological characteristic parameters, a coupled field model of pattern structure and standing wave effect is constructed. The influence of metal mesh pattern structure on the redistribution of light intensity inside photoresist is analyzed, and the light intensity redistribution prediction results are obtained. S33. Based on the light intensity redistribution prediction results, determine the standing wave amplification coefficient and periodic resonance coefficient of the metal mesh pattern structure for the standing wave effect, and use the standing wave amplification coefficient and periodic resonance coefficient as standing wave coupling characteristic parameters to characterize the enhancement degree of the standing wave effect by the metal mesh pattern structure.

4. The metal mesh exposure method for sapphire optical windows according to claim 3, characterized in that, Determining the standing wave amplification factor in step S33 includes: S331. Based on the light intensity distribution prediction results in step S22, extract the average light intensity in each sub-region and use the average light intensity as the reference light intensity value without the influence of graphic structure. S332. Based on the light intensity redistribution prediction results, extract the mean redistributed light intensity in each sub-region, and use the mean redistributed light intensity as the coupled light intensity value under the influence of the metal mesh pattern structure. S333. The ratio of the coupled light intensity value to the reference light intensity value is used as the standing wave amplification factor to characterize the degree of local enhancement of the standing wave amplitude characteristics by the grid topology.

5. The metal mesh exposure method for sapphire optical windows according to claim 3, characterized in that, Determining the periodic resonance coefficient in step S33 includes: S334. Determine the horizontal spatial frequency based on the horizontal period of the metal mesh, where the horizontal spatial frequency is the reciprocal of the period of the metal mesh. S335. Take the reciprocal of the exposure dose fluctuation period as the vertical spatial frequency, and calculate the sine of the angle between the propagation direction of the exposure light source and the pattern direction of the metal mesh as the direction matching factor. S336. The absolute value of the product of the ratio of the horizontal spatial frequency to the vertical spatial frequency and the direction matching factor is used as the periodic resonance coefficient to characterize the dose fluctuation superposition effect caused by the matching degree between the grid geometric period and the standing wave period.

6. The metal mesh exposure method for sapphire optical windows according to claim 1, characterized in that, Step S4, which determines the range of exposure dose fluctuations at different spatial locations of the sapphire optical window, includes: S41. Determine the baseline dose fluctuation amplitude based on the exposure dose fluctuation amplitude and the preset exposure dose range; S42. Based on the sub-region division results in step S33, extract the standing wave amplification coefficient and periodic resonance coefficient corresponding to each sub-region, and use the product of the standing wave amplification coefficient and the periodic resonance coefficient as the local coupling enhancement coefficient corresponding to the sub-region. S43. Calculate the exposure dose fluctuation amplitude of each sub-region based on the reference dose fluctuation amplitude and the local coupling enhancement coefficient to obtain the exposure dose fluctuation range corresponding to each sub-region.

7. The metal mesh exposure method for sapphire optical windows according to claim 1, characterized in that, The metal mesh exposure quality warning in step S5 includes: The minimum and maximum exposure dose values ​​of each sub-region are compared with the lower and upper limits of the photoresist exposure dose process window, respectively. If the exposure dose fluctuation range falls within the range of the photoresist exposure dose process window, no metal grid exposure quality warning is issued; otherwise, a metal grid exposure quality warning is issued.

8. A metal grid exposure system for sapphire optical windows, used to implement the metal grid exposure method for sapphire optical windows according to any one of claims 1-7, characterized in that, The system includes: The data acquisition module is used to acquire substrate feature data, photoresist feature data, exposure light source feature data, and metal mesh grid pattern structure feature data of the sapphire optical window. The photoresist feature data includes the refractive index of the photoresist material and the photoresist exposure dose process window. The standing wave effect prediction module is used to predict the standing wave effect based on substrate feature data, photoresist feature data and exposure light source feature data, and to determine the characteristic parameters of exposure dose fluctuation under the influence of the standing wave effect. The standing wave coupling analysis module is used to analyze the coupling degree between the metal mesh grid pattern structure and the standing wave effect based on the pattern structure feature data, and to determine the standing wave coupling characteristic parameters under the influence of the metal mesh grid pattern structure. The fluctuation range determination module is used to determine the exposure dose fluctuation range of different regions of the sapphire optical window based on the exposure dose fluctuation characteristic parameters and the standing wave coupling characteristic parameters. The exposure quality early warning module is used to provide early warning of metal mesh exposure quality based on the matching relationship between the exposure dose fluctuation range and the photoresist exposure dose process window.

9. An electronic device, comprising: A processor and a memory, wherein the memory stores a computer program that can be called by the processor; characterized in that the processor executes the metal mesh exposure method for sapphire optical windows as described in any one of claims 1-7 by calling the computer program stored in the memory.

10. A computer-readable storage medium, characterized in that, The device stores instructions that, when executed on a computer, cause the computer to perform the metal mesh exposure method for sapphire optical windows as described in any one of claims 1-7.

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