Silicon-based liquid crystal substrate, design method and liquid crystal spatial light modulator

Abstract

The application relates to the technical field of laser processing manufacturing, and particularly discloses a silicon-based liquid crystal substrate, a design method and a liquid crystal spatial light modulator. The silicon-based liquid crystal substrate comprises a reflecting layer arranged on a silicon substrate, the reflecting layer is a first composite film layer, the first composite film layer comprises a flat film and a high-reflection film; the flat film is arranged on the silicon substrate, and the high-reflection film is arranged on the flat film. The design method of the silicon-based liquid crystal substrate comprises the design of the reflecting layer; and / or the design of a glass cover plate; and / or the design of liquid crystal material used by a liquid crystal layer; and / or the design of the silicon substrate; and / or the design of a liquid crystal packaging process. The application not only improves the light energy utilization rate, but also improves the damage threshold.

Description

Technical Field

[0001] This invention relates to the field of laser processing and manufacturing technology, specifically to a silicon-based liquid crystal substrate and its design method, and a liquid crystal spatial light modulator. Background Technology

[0002] Liquid Crystal on Silicon (LCoS) is a novel reflective liquid crystal packaging technology. The manufacturing process involves fabricating a CMOS integrated circuit backplane on a silicon substrate, then using advanced processes to grind it smooth and deposit an aluminum film as a reflective layer, forming a complete silicon-based CMOS circuit substrate. Finally, the CMOS substrate is bonded to a cover glass substrate containing transparent electrodes, and liquid crystal is injected into the package. LCoS places the control circuitry below the display device so that it does not interfere with light beam transmission, thereby achieving greater light output and higher resolution. Compared to traditional LCDs, which are fabricated on glass substrates and typically use a transmissive structure where light shines from behind the substrate, the light utilization efficiency of LCDs is limited to less than 5% due to the obstruction of circuit metal lines and color resist layers, making it difficult to improve resolution. In contrast, LCoS (Liquid Crystal on Silicon) is fabricated on silicon wafers. The CMOS circuitry incorporates reflective aluminum films, allowing light to shine from the front and be reflected off the same side. This reflective projection structure, combined with different color resists and the synchronized color synthesis of different light sources, significantly improves the light utilization efficiency of LCoS, currently reaching 60%–85% or higher. Furthermore, the biggest advantage of silicon-based CMOS substrates is that the substrate material is monocrystalline silicon, which possesses excellent electron mobility and allows for the formation of finer circuits. Therefore, it is easier to achieve higher resolution than LCDs. These advantages make silicon-based liquid crystals more promising in terms of application scenarios and market penetration.

[0003] The silicon-based liquid crystal substrate consists of, from bottom to top, a silicon substrate, a CMOS circuit, a reflector (aluminum film), an alignment layer, a liquid crystal layer, another alignment layer, and a glass cover plate containing ITO electrodes.

[0004] A liquid crystal spatial light modulator (LC-SLM) utilizes the photoelectric effect of liquid crystals to alter the amplitude, intensity, phase, polarization state, and wavelength of light distribution in space by changing the properties of liquid crystal molecules under the control of time-varying electrical drive signals or other signals. It can also convert incoherent light into coherent light, thereby writing specific information into the light wave to achieve optical wave modulation. It can conveniently load information into one-dimensional or two-dimensional light fields, leveraging the wide bandwidth and multi-channel parallel processing advantages of light to rapidly process the loaded information. It is a core component of real-time optical information processing, optical interconnects, and optical computing systems. Spatial light modulators are generally classified into reflective and transmissive types based on the readout method; and into optically addressed (OA-SLM) and electrically addressed (EA-SLM) types based on the input control signal method. A liquid crystal spatial light modulator consists of three parts: a silicon-based liquid crystal substrate, a driving circuit board, and a housing structure.

[0005] Existing silicon-based liquid crystal substrates and liquid crystal spatial light modulators still have certain problems and drawbacks, preventing their widespread application and promotion, or making them unsuitable for key sectors such as people's livelihood and industrial manufacturing. The main problems are as follows:

[0006] Question 1: The light utilization rate of silicon-based liquid crystal light valves (silicon-based liquid crystal substrates) and liquid crystal spatial light modulators is relatively low (35%-75%). The main reason is that during the design and fabrication of silicon-based liquid crystal LCOS substrates, aluminum or a combination of aluminum and copper is used as the coating material for the surface reflective layer. These coating materials have low self-reflectivity in commonly used wavelength bands (UV-A, VIS, NIR, TELCO), poor surface smoothness, and a small pixel fill factor, which are the main reasons for the low light utilization rate of silicon-based liquid crystal light valves and spatial light modulators.

[0007] Question 2: Silicon-based liquid crystal light valves and liquid crystal spatial light modulators have low laser damage thresholds (poor resistance to strong lasers) (average power density ≤ 10 W / cm²). 2 Existing silicon-based liquid crystal light valves and liquid crystal spatial light modulators are mainly designed for use in environments with weak light (low energy) light sources such as lasers, LEDs, and halogen lamps. When these devices are subjected to strong lasers in fields such as scientific research, industrial laser manufacturing, medical care, and aerospace, their unreasonable or defective film system design, material selection, and manufacturing process can cause damage or destruction, rendering them unusable or causing significant economic losses.

[0008] The above two issues are the main problems limiting the performance improvement and application expansion of silicon-based liquid crystal light valves and liquid crystal spatial light modulators, and they urgently need to be solved. The performance of liquid crystal spatial light modulators and their derived application modules or systems mainly depends on the silicon-based liquid crystal light valve (silicon-based liquid crystal substrate), especially its optical performance and damage threshold. Summary of the Invention

[0009] The purpose of this invention is to provide a silicon-based liquid crystal substrate, a design method, and a liquid crystal spatial light modulator, which not only improves light energy utilization but also increases the damage threshold.

[0010] This invention is achieved through the following technical solution:

[0011] A silicon-based liquid crystal substrate includes a reflective layer disposed on the silicon substrate. The reflective layer is a first composite film layer, which includes a planarization film and a high-reflectivity film. The planarization film is disposed on the silicon substrate, and the high-reflectivity film is disposed on the planarization film.

[0012] The reflective layer in the existing silicon-based liquid crystal substrate is a reflective mirror on the silicon substrate (metal film: aluminum and copper, usually aluminum film), which has the following problems: 1) insufficient LCoS light energy utilization (reflectivity); 2) silicon-based circuits are susceptible to strong lasers, that is, the performance of strong lasers is insufficient (low damage threshold).

[0013] The main reason for insufficient light energy utilization is the low reflectivity of the aluminum film. Additionally, the presence of the pixel gap causes diffraction after light incident, with some energy reflected as diffracted spots, which is detrimental to its use. The main reason for insufficient high-power laser performance is that the absorption of light by the metal film far exceeds the heat transfer of the LCoS substrate in the same time period, leading to severe heat accumulation and burn-out of the metal film (aluminum or copper).

[0014] The reflective layer of the present invention is composed of a planarization film and a high-reflectivity film. The planarization film includes, but is not limited to, organic PI, organic epoxy, inorganic silicon nitride, and inorganic silicon oxide. The preparation method of the planarization film includes, but is not limited to, spraying, spin coating, vapor deposition, and chemical or physical deposition. The high-reflectivity film is an inorganic dielectric film, including, but not limited to, hafnium oxide and tantalum oxide, and is formed by vapor deposition and chemical or physical deposition.

[0015] The planarization film of the present invention can reduce the problem of insufficient flatness of the substrate itself and the presence of pixel gap, which causes the planarization film to still have unevenness. This reduces the degree of influence of strong laser on silicon-based circuits and improves the damage threshold of silicon-based liquid crystal substrates. At the same time, the reflective layer composed of the planarization film and the high-reflectivity film can improve the light energy utilization rate, which can exceed 98% in actual measurements.

[0016] Furthermore, the thickness of the first composite film layer is 4μm to 20μm, and the thickness selection depends on the corresponding high laser performance and reflection performance. The residual transmittance T of the composite film layer used for high laser device design is <0.01%.

[0017] Furthermore, the preparation process of the first composite film layer is as follows: first, a planarization film is deposited on a silicon substrate, then the planarization film is polished to form a flat surface with small undulations and high flatness, and then a high-reflectivity film is deposited on the flat surface.

[0018] Due to insufficient flatness of the substrate itself and the presence of pixel gaps, the planarization film still has unevenness. By polishing the planarization film (including but not limited to chemical mechanical polishing), a flat surface with small undulations and high flatness is formed. Then, a high-reflectivity film is deposited on the flat surface to form a planar-high-reflectivity composite film layer. This can reduce the impact of the unevenness of the planarization film caused by insufficient flatness of the substrate itself and the presence of pixel gaps on the damage threshold of the silicon-based liquid crystal substrate in one step.

[0019] Furthermore, an antireflective film is provided on the outer side of the glass cover, and a matching film is provided on the inner side of the glass cover. A transparent conductive film is deposited on the matching film, and an alignment film is coated on the transparent conductive film to form a second composite film layer. This second composite film layer as a whole completes the antireflective effect on the glass cover and the liquid crystal interface.

[0020] Furthermore, the manufacturing process of the glass cover is as follows:

[0021] The matching film is deposited and polished until an optical matching effect is achieved. Then, a transparent conductive film is deposited on the matching film using laser pulse deposition, followed by annealing and heat treatment.

[0022] Furthermore, it also includes a liquid crystal layer placed between the silicon substrate and the glass cover, wherein the liquid crystal material is a nematic liquid crystal; the liquid crystal material used in the liquid crystal layer has a liquid crystal birefringence ≥0.3; the liquid crystal material is matched with the first composite film layer and the second composite film layer; the liquid crystal material has the characteristics of refractive index matching, low absorption, and good transmittance performance in a specified band.

[0023] Furthermore, the fabrication process of the silicon substrate is as follows:

[0024] After the final layer of the silicon-based liquid crystal CMOS circuit is fabricated, the surface of the reflector (aluminum film) is subjected to a second polishing process using chemical mechanical polishing to ensure that the protrusion height of the reflector surface is controlled within 50nm. Then, the first composite film layer is deposited on the silicon substrate.

[0025] Furthermore, in the liquid crystal packaging process, the silicon-based liquid crystal substrate uses a high-precision filter to filter the frame adhesive and liquid crystal material.

[0026] Furthermore, the design value for the PixelGap of the silicon substrate is 0.2 μm.

[0027] A design method for a silicon-based liquid crystal substrate includes the design of a reflective layer; and / or the design of a glass cover plate; and / or the design of a liquid crystal material used in the liquid crystal layer; and / or the design of a silicon substrate; and / or the design of a liquid crystal packaging process.

[0028] A liquid crystal spatial light modulator includes the aforementioned silicon-based liquid crystal substrate, wherein the liquid crystal spatial light modulator employs a 1:1 square target surface.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] 1. The reflective layer of the present invention is composed of a flat film and a high-reflectivity film; it not only improves the light energy utilization rate, but also improves the damage threshold. By polishing the flat film, the influence of the unevenness of the flat film on the damage threshold of the silicon-based liquid crystal substrate caused by the insufficient flatness of the substrate itself and the presence of pixel gaps can be further reduced.

[0031] 2. The design of the common electrode and cover glass in this invention significantly reduces overall absorption while increasing light energy utilization efficiency.

[0032] 3. This invention employs a chemical mechanical polishing process to perform secondary polishing on the surface of the reflector, ensuring that the protrusion height of the reflector surface is controlled within 50nm, thus guaranteeing the yield of the wafer (silicon substrate) and the quality of subsequent coating. Furthermore, in the packaging process of reflective devices using liquid crystal (silicon-based liquid crystal substrate), a high-precision filter should be selected to ensure the filtration of the frame adhesive and liquid crystal material, reducing impurities introduced during the process and ensuring the quality of the reflective device. The design of the reflective layer, the glass cover plate, the liquid crystal material used in the liquid crystal layer, the silicon substrate, and the liquid crystal packaging process in this invention, used individually or in combination, significantly improve the modulation effect and damage threshold of the liquid crystal spatial light modulator. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram of the silicon-based liquid crystal substrate of the present invention;

[0035] Figure 2 Comparison diagrams showing the effects of different square target surfaces combined with optical systems;

[0036] Figure 3 This is a comparison image of silicon-based liquid crystal surface treatment before and after. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. The embodiments described below are some, but not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, materials, or methods are not specifically described to avoid obscuring the invention. Unless otherwise specified, the materials, instruments, and reagents used in the following embodiments are commercially available. Unless otherwise specified, the techniques used in the embodiments are conventional methods well known to those skilled in the art.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0040] Example 1:

[0041] like Figure 1 As shown, a silicon-based liquid crystal substrate comprises, from bottom to top, a silicon substrate, a CMOS circuit, a reflective layer, an alignment layer, a liquid crystal layer, another alignment layer, and a glass cover plate containing ITO electrodes. To address the problems of low light energy utilization and low damage threshold in existing silicon-based liquid crystal substrates, this embodiment uses a reflective layer as a first composite film layer. The first composite film layer includes a planarization film and a high-reflectivity film; the planarization film is disposed on the silicon substrate, and the high-reflectivity film is disposed on the planarization film. The thickness of the first composite film layer is 4 μm to 20 μm; the thickness selection depends on the corresponding high-intensity laser performance and reflectivity. For devices designed for high-intensity lasers, the residual transmittance T of the composite film layer is <0.01%.

[0042] The planarization film includes, but is not limited to, organic PI, organic epoxy, inorganic silicon nitride, and inorganic silicon oxide. Organic PI includes, but is not limited to, polyimide; organic epoxy includes, but is not limited to, SU8 photoresist; and inorganic silicon nitride includes, but is not limited to, SiN. xInorganic oxygen silicon includes, but is not limited to, SiO2. The methods for preparing planar films include, but are not limited to, spraying, spin coating, vapor deposition, and chemical or physical deposition. High-reflectivity films are inorganic dielectric films, including, but not limited to, hafnium oxide and tantalum oxide, and are formed by vapor deposition and chemical or physical deposition.

[0043] The planarization film in this embodiment can reduce the flatness of the substrate itself to a certain extent. The presence of pixel gaps causes the planarization film to still have unevenness, thereby reducing the susceptibility of silicon-based circuits to strong lasers and increasing the damage threshold of silicon-based liquid crystal substrates. At the same time, the reflective layer composed of the planarization film and the high-reflectivity film can improve the light energy utilization rate, which can exceed 98% in actual measurements.

[0044] In a preferred embodiment, the preparation process of the first composite film layer is as follows: first, a planarization film is deposited on a silicon substrate, then the planarization film is polished to form a flat surface with small undulations and high flatness, and then a high-reflectivity film is deposited on the flat surface.

[0045] Because the silicon substrate itself has insufficient flatness and pixel gaps, the flatness film still has undulations. By polishing the flatness film (including but not limited to chemical mechanical polishing), a flat surface with small undulations and high flatness is formed. Then, a high reflectivity film is deposited on the flat surface to form a flatness-high reflectivity composite film layer. This can further reduce the impact of the unevenness of the flatness film caused by the insufficient flatness of the substrate itself and the presence of pixel gaps on the damage threshold of the silicon-based liquid crystal substrate.

[0046] In a preferred embodiment, an antireflective film is provided on the outer side of the glass cover, a matching film is provided on the inner side of the glass cover, a transparent conductive film is deposited on the matching film, and an alignment film is coated on the transparent conductive film to form a second composite film layer.

[0047] This embodiment also optimizes the design of the glass cover, specifically:

[0048] The cover glass is made of fused silica material, processed mechanically and optically. An antireflective coating is deposited on the outward-facing side of the cover glass, with a residual reflectance R < 0.2%. A matching film is deposited on the inward-facing side. This matching film, together with the transparent conductive film and the alignment film, forms a composite layer that collectively reduces reflection at the cover glass and liquid crystal interface. The matching film is polished to achieve optical matching while reducing surface roughness. Depositing a common electrode on a low-roughness surface effectively improves conductivity. The common electrode is deposited on the matching film using laser pulse deposition at 400°C with an excimer laser at a wavelength of 248 nm, a frequency of 6 Hz, and an energy density of 0.4 J / cm². It is then annealed and subjected to a second heat treatment at 200°C before use. The design of the common electrode and the cover glass significantly reduces overall absorption while increasing light energy utilization efficiency.

[0049] In a preferred embodiment, the liquid crystal is a nematic liquid crystal, and the liquid crystal material used in the liquid crystal layer has a liquid crystal birefringence ≥ 0.3; the liquid crystal material is matched with the first composite film layer and the second composite film layer; the liquid crystal material has the characteristics of refractive index matching, low absorption, and good transmittance performance in a specified wavelength band.

[0050] In other words, this embodiment features an optimized design for the liquid crystal material, specifically:

[0051] The design of liquid crystals considers three factors. First, due to the presence of composite layers, the thickness of the composite layers affects electric field transmission. In this design, the liquid crystal birefringence is ≥0.3 to match the corresponding beam phase modulation requirements. The liquid crystal birefringence is controlled using, but not limited to, a mixed crystal process. Second, for the use of high-intensity laser bands, the liquid crystal material is designed to suppress vibrational resonance absorption and overtone absorption. The liquid crystal material undergoes chemical treatment to replace resonant groups and is then subjected to a mixed crystal process to prepare a liquid crystal material with matching refractive index, low absorption, and good transmittance in the specified band. Third, the refractive index of the liquid crystal should match that of the composite layers to reduce interface reflection and scattering, reduce laser interference, and improve laser utilization and high-intensity laser performance.

[0052] In the fabrication of ordinary silicon-based liquid crystal CMOS circuits, the mirror layer may suffer from short circuits, residues, and surface particles. To maintain wafer yield, the semiconductor industry often uses a grading system. If the number of pixels affected by these issues is less than a certain value, the product is still considered acceptable. Under strong light, these factors become major contributors to heat absorption and accumulation, simultaneously affecting the deposition effect and film structure of the non-metallic dielectric film on the wafer surface. Ultimately, this leads to either excessive light transmission or excessive light absorption, lowering the device's damage threshold.

[0053] Therefore, in a preferred embodiment, after the last layer of the silicon-based liquid crystal CMOS circuit is fabricated, the surface of the reflector (aluminum film) is subjected to secondary polishing using a chemical-mechanical polishing (CMP) process. The polishing result is based on the flatness test result, ensuring that the protrusion height on the surface of the reflector (aluminum film) is controlled within 50nm, thus guaranteeing the wafer yield and the quality of subsequent coating.

[0054] In a preferred embodiment, a high-precision filter is used in the liquid crystal packaging process of the silicon-based liquid crystal substrate to filter the sealant and liquid crystal material. This reduces impurities introduced during the process and ensures the quality of the reflective device. Replacing the silicon-based liquid crystal substrate with a filter has proven to significantly improve the modulation effect and damage threshold of the liquid crystal spatial light modulator. A comparison of the silicon-based liquid crystal surface treatment before and after is shown in the figure. Figure 3 As shown.

[0055] In a preferred embodiment, the PixelGap design value for the silicon substrate is 0.2 μm.

[0056] In a specific case:

[0057] A planarization film is deposited on the surface of an LCoS silicon substrate (silicon substrate). The planarization film only covers the pixel area, while the electrode area is shielded by a mask fixture. The thickness of the planarization film ranges from 100 nm to 4000 nm. After the planarization film is deposited, it undergoes precision polishing to bring the planarization layers between pixel blocks to the same height. The thickness of the polished planarization film ranges from 100 nm to 3000 nm. Subsequently, a dielectric reflective layer (high reflectivity film) is deposited on the planarization film to form a planarization-high reflectivity composite film layer, i.e., the first composite film layer. The total thickness of the first composite film layer is 4 μm to 20 μm, and the thickness is determined by the corresponding high-intensity laser performance and reflectivity. The design of the dielectric reflective layer considers the refractive index and thickness of the planarization layer, ensuring a reflectivity R ≥ 99% while also ensuring a transmittance T ≤ 0.01%. The conductive cover plate is deposited using laser pulse deposition with a wavelength of 248 nm, a frequency of 6 Hz, and an energy density of 0.4 J / cm². 2 Using excimer lasers, a film-coated glass cover was deposited at 400℃, followed by annealing. Before use, it underwent a second heat treatment at 200℃. An alignment layer was coated onto the silicon substrate and the electrode-containing glass cover, and the alignment layer was cured. Then, it was rubbed aligned. After placing spacers and applying edge adhesive, the silicon substrate and the conductive cover (glass cover) were antiparallel to form a cell, which was then cured at 120℃~150℃ and 0.3MPa. Liquid crystal material was injected under a vacuum environment below 10Pa. The liquid crystal material was treated to suppress vibrational resonance absorption and overtone absorption. The resonant groups in the liquid crystal material were replaced by chemical treatment, and a mixed crystal treatment was performed to prepare a liquid crystal material with refractive index matching, low absorption, and good transmittance in a specified wavelength band. Uniformity correction was then performed using a pressure of 0.1MPa, completing the fabrication of the LCoS device (silicon-based liquid crystal substrate).

[0058] Example 2:

[0059] A liquid crystal spatial light modulator includes a silicon-based liquid crystal substrate as described in Example 1, and also includes a driving circuit board and a housing structure. The liquid crystal spatial light modulator adopts a 1:1 square target surface.

[0060] Traditional liquid crystal spatial light modulator (LCS) designs primarily employ aspect ratios of 4:3, 16:9, 16:10, or a near-perfect balance between the long and short sides. This is mainly because liquid crystal on silicon (LCoS) displays were initially designed for display and projection, and the most comfortable aspect ratios for the human eye are 4:3, 16:9, and 16:10. However, this design limits the application of LCS in optical simulation testing, ultra-precision laser processing, additive manufacturing 3D printing, and maskless photolithography. This is because most existing detectors have square target designs, and all existing optical systems are circular. The mismatch between the detectors / optical systems and the 4:3, 16:9, and 16:10 aspect ratio LCS results in inefficient pixel utilization, leading to insufficient short-side dimensions and pixels, and redundant long-side dimensions and pixels.

[0061] The liquid crystal spatial light modulator of this invention, with its 1:1 square target surface and high-resolution design, offers significant advantages. It maximizes the target surface and pixel utilization in fields such as optical simulation testing, ultra-precision laser processing, additive manufacturing 3D printing, and maskless exposure lithography, thereby providing detectors and optical systems in these fields with a larger target field of view, higher-resolution target information, and improved processing accuracy.

[0062] The contrasting effects of different square target surfaces combined with optical systems are as follows: Figure 2 As shown in Table 1:

[0063] Table 1

[0064]

[0065] Example 3:

[0066] A design method for a silicon-based liquid crystal substrate includes the design of a reflective layer; and / or the design of a glass cover plate; and / or the design of a liquid crystal material used in the liquid crystal layer; and / or the design of a silicon substrate; and / or the design of a liquid crystal packaging process.

[0067] This embodiment aims to improve the reflectivity of silicon-based liquid crystal wafers, reduce the absorption of strong light by the wafer surface, design a unique microstructure of non-metallic reflective film, select non-metallic optical film materials with high damage thresholds, optimize the monomer structure of liquid crystal materials and the performance of synthesized materials, adjust the composition of the common electrode material of the upper substrate, change the material of the cover glass, vapor deposition of optical films on the front and back of the upper substrate, and improve the process of silicon-based liquid crystal packaging. These are some of the design and fabrication methods used to solve the existing problems of silicon-based liquid crystal light valves and liquid crystal spatial light modulators, significantly improve the damage threshold and optical performance of the devices themselves and their derivative application equipment or systems, and achieve the goal of extending equipment life and enhancing system reliability.

[0068] The above five designs improve the overall performance of silicon-based liquid crystal substrates by selecting one or more improvements.

[0069] The design of the reflective layer is the same as the preparation process of the first composite film layer described in Example 1.

[0070] The design process for the liquid crystal material is as follows: the liquid crystal material was optimized in the same way as in Example 1.

[0071] The design process for the glass cover is as follows: the glass cover is optimized in the same way as in Example 1.

[0072] The silicon substrate design process includes the silicon substrate design process described in Example 1, and also includes the high fill factor design and fabrication process optimization of silicon-based liquid crystal wafers.

[0073] Currently, the fill factor design of liquid crystal on silicon (LCoS) wafers is basically between 80% and 91%. To improve the fill factor to 93% or 96%, there are usually two solutions. Solution one requires increasing the pixel size to improve the fill factor accordingly, but this will lead to a decrease in the resolution of products of the same size or an increase in the size of products of the same resolution, resulting in a decrease in wafer utilization. Solution two is to improve the manufacturing process capability of LCoS wafers, such as upgrading the 180nm process to 90nm or higher. However, this will greatly increase the design cost and tape-out cost of LCoS wafers, and at the same time reduce the wafer yield.

[0074] The present invention addresses this issue by optimizing wafer design and fabrication processes to maintain a high fill factor in silicon-based liquid crystal wafers. This approach ensures wafer performance without increasing the difficulty and cost of wafer fabrication, while also guaranteeing wafer yield. The fill factor is calculated as follows:

[0075] Fillfactor=(Pixelsize-PixelGap)2 / (Pixelsize*Pixelsize)*100%

[0076] Considering cost and existing technology, the design value of the PixelGap in this invention is determined to be 0.2μm. Due to the characteristics of liquid crystals, LCoS is generally used in the band above 300nm. This design value completely avoids the band used by the device and optimizes diffraction loss. At this time, the fill factor and electrical test yield can be guaranteed. At the same time, for a 0.2μm PixelGap, the planarization layer material at the corresponding position of the PixelGap in subsequent processes will not fall into the PixelGap. Instead, the thin film structure is pulled up between the two pixels by the adhesive pull, which is beneficial to the planarization of the structure.

[0077] The liquid crystal packaging process design process is the same as described in the embodiment, which introduces a high-precision filter to ensure the filtration of the frame adhesive and liquid crystal material.

[0078] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0079] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

Claims

1. A silicon-based liquid crystal substrate, characterized in that, The device includes a reflective layer disposed on a silicon substrate, the reflective layer being a first composite film layer, the first composite film layer comprising a planarization film and a high-reflectivity film; the planarization film is disposed on the silicon substrate, and the high-reflectivity film is disposed on the planarization film; The thickness of the first composite film layer is 4μm to 20μm, and the residual transmittance T < 0.01%; The silicon substrate is fabricated as follows: after the last layer of the silicon-based liquid crystal CMOS circuit is fabricated, the surface of the reflector is polished a second time by chemical mechanical polishing to ensure that the protrusion height of the reflector surface is controlled within 50nm, and then the first composite film layer is set on the silicon substrate. The silicon substrate has a designed pixel gap of 0.2 μm.

2. The silicon-based liquid crystal substrate according to claim 1, characterized in that, The preparation process of the first composite film layer is as follows: first, the flat film is deposited on the silicon substrate, then the flat film is polished to form a flat surface with small undulations and high flatness, and then a high reflectivity film is deposited on the flat surface.

3. The silicon-based liquid crystal substrate according to claim 1 further includes a glass cover plate, characterized in that, An antireflective film is provided on the outer side of the glass cover, and a matching film is provided on the inner side of the glass cover. A transparent conductive film is deposited on the matching film, and an alignment film is coated on the transparent conductive film to form a second composite film layer.

4. A silicon-based liquid crystal substrate according to claim 3, characterized in that, The glass cover plate is prepared as follows: The matching film is deposited and polished until an optical matching effect is achieved. Then, a transparent conductive film is deposited on the matching film using laser pulse deposition, followed by annealing and heat treatment.

5. A silicon-based liquid crystal substrate according to claim 3, further comprising a liquid crystal layer disposed between the silicon substrate and the glass cover plate, characterized in that, The liquid crystal material used in the liquid crystal layer is a nematic liquid crystal; the liquid crystal birefringence of the liquid crystal material used in the liquid crystal layer is ≥0.3; the liquid crystal material is matched with the first composite film layer and the second composite film layer; the liquid crystal material has the characteristics of refractive index matching, low absorption, and good transmittance performance in a specified wavelength band.

6. A silicon-based liquid crystal substrate according to any one of claims 1-5, characterized in that, In the liquid crystal packaging process, the silicon-based liquid crystal substrate uses a high-precision filter to filter the frame adhesive and liquid crystal material.

7. The design method for a silicon-based liquid crystal substrate as described in any one of claims 1-6, characterized in that, This includes the design of the reflective layer; and / or the design of the glass cover; and / or the design of the liquid crystal material used in the liquid crystal layer; and / or the design of the silicon substrate; and / or the design of the liquid crystal packaging process.

8. A liquid crystal spatial light modulator, characterized in that, The liquid crystal spatial light modulator includes a silicon-based liquid crystal substrate as described in any one of claims 1-6, wherein the liquid crystal spatial light modulator employs a 1:1 square target surface.

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