A method for preparing a silicon lens array with controllable surface

Abstract

The application discloses a preparation method of a silicon lens array with controllable surface type, and comprises the following steps: S1, preparing an initial mold with a concave lens array surface type; S2, pretreating a silicon substrate and coating a stamping adhesive; S3, stamping by using the initial mold, demolding after curing, and forming a convex lens array of the stamping adhesive on the silicon substrate; S4, transferring the convex lens array of the stamping adhesive to the silicon substrate by using a fixed dry etching process, and forming a preliminary silicon lens array; S5, testing surface type parameters of the preliminary silicon lens array, comparing the surface type parameters with target design parameters, quantitatively correcting the concave lens array surface type of the initial mold according to a comparison result, and obtaining a corrected mold; and S6, repeatedly executing steps S2 to S4 by using the corrected mold, and preparing a final silicon lens array with a surface type meeting design requirements. The method can prepare the silicon lens array with a high filling coefficient, an accurate surface type and excellent uniformity in a high-repeatability and high-throughput manner.

Description

Technical Field

[0001] This invention relates to the field of micro-nano optical device manufacturing technology, specifically to a method for fabricating a silicon lens array with controllable surface shape, applicable to the fabrication of silicon lens arrays required for infrared optical communication, imaging and detection systems. Background Technology

[0002] In fields such as high-speed optical communication, lidar (LiDAR), and infrared focal plane arrays, silicon lens arrays have become key optical components for achieving efficient beam shaping, focusing, and coupling due to their unique subwavelength-scale wavefront manipulation and on-chip integration capabilities. Meanwhile, silicon, with its high transmittance in the mid-to-long infrared band, good thermal stability, and compatibility with semiconductor micro / nano fabrication processes, is an ideal substrate material for fabricating high-performance infrared microlens arrays.

[0003] However, existing mainstream silicon microlens array fabrication technologies, such as grayscale lithography and photoresist thermal reflow, still have significant limitations. For example, in dense arrays designed to achieve high fill factors, the dry etching process often causes systematic deviations in lens focal length and surface profile due to micro-load effects, making it difficult to achieve overall optical uniformity. Meanwhile, the aspherical and other high-order optical surface profiles required to correct aberrations rely on complex process parameter adjustments in grayscale lithography; while in thermal reflow, the surface profile is mainly limited by material surface tension, generally resulting in narrow process windows, low surface profile accuracy, and low fill factors. Furthermore, the performance of these methods is highly dependent on complex etching process parameter adjustments, leading to poor repeatability and making it difficult to meet the practical needs of large-scale, consistent production.

[0004] Therefore, there is an urgent need for a method to fabricate silicon lens arrays that can simultaneously achieve high fill factor, high surface accuracy, and excellent array uniformity, while also being stable and suitable for mass production. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide a method for fabricating silicon lens arrays with controllable surface profiles, addressing the shortcomings of existing technologies. This method, through a closed-loop process of "mold preparation—imprint etching—measurement—mold correction—formal production," can fabricate silicon lens arrays with high repeatability and high throughput, exhibiting high fill factor, precise surface profiles (including aspherical surfaces), and excellent uniformity. The silicon lens arrays fabricated using this method can significantly improve the coupling efficiency of optical systems and reduce optical losses, demonstrating great application potential.

[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a method for fabricating a silicon lens array with controllable surface shape, comprising the following steps: S1. Prepare an initial mold with a concave lens array surface; S2. Pre-treat the silicon substrate and coat the pre-treated silicon substrate with imprinting adhesive. S3. Using the initial mold, the silicon substrate coated with imprinting adhesive is imprinted, and after curing, it is demolded to form an imprinting adhesive convex lens array on the silicon substrate. S4. Using a fixed dry etching process, the imprinted resist convex lens array is transferred to a silicon substrate to form a preliminary silicon lens array. S5. Test the surface parameters of the initial silicon lens array and compare them with the target design parameters. Based on the comparison results, perform quantitative correction processing on the surface of the concave lens array of the initial mold to obtain the correction mold. S6. Repeat steps S2 to S4 using the correction mold to obtain the final silicon lens array whose surface shape meets the design requirements.

[0007] The core innovation of this invention lies in a closed-loop surface shape control based on mold iterative correction. This method abandons the traditional approach of directly controlling the final surface shape through fine-tuning the etching selectivity. Instead, it first uses a fixed and stable dry etching process for pattern transfer, then measures the resulting systematic surface shape deviation, and finally compensates for this deviation in the mold design and manufacturing through reverse calculation. After 1-2 iterations, the corrected mold can be used to batch replicate silicon lens arrays that meet design requirements under a fixed dry etching process, solving the problem of surface shape inconsistency caused by etching process fluctuations in traditional methods and improving the stability of batch production. Furthermore, the corrected mold can be reused repeatedly, resulting in high manufacturing efficiency and precision, significantly reducing the manufacturing cost of silicon lens arrays.

[0008] The core innovative idea of ​​mold iterative correction in the method of this invention can be extended to the manufacturing of micro-optical devices in other material systems (such as chalcogenide glass, germanium and other infrared materials).

[0009] Preferably, the quantitative correction process described in step S5 involves reverse calculation based on the etching selectivity model of the fixed dry etching process, converting the measured silicon lens surface deviation into the compensation amount required for the mold surface. The quantitative correction process used in this invention is not based on empirical estimation, but rather on reverse calculation based on the correspondence between the etching rate of the imprinting adhesive and the etching rate of the silicon material under fixed dry etching process parameters. Through quantitative correction processing, the measured silicon lens surface error can be accurately reverse-calculated into the compensation amount required for the mold surface, improving the accuracy of the correction. Typically, only 1-2 iterations are needed to achieve the required surface shape, reducing the cost of repeated trial and error.

[0010] Preferably, the initial mold is made of a material capable of ultra-precision machining and secondary correction machining. The initial mold can be a metal mold, a silicon-based mold, a glass-based mold, or a polymer mold. More preferably, the metal mold is a nickel, nickel-phosphorus alloy, or aluminum alloy mold machined by single-point diamond turning; the silicon-based mold is prepared by femtosecond laser scanning combined with anisotropic or isotropic wet etching processes; the glass-based mold is prepared by precision hot pressing; and the polymer mold is an epoxy resin or polymethyl methacrylate mold machined by single-point diamond turning. Metal, silicon-based, glass-based, or polymer materials can all achieve micron- or even nanometer-level structural machining and possess the capability for secondary correction machining on the original basis. This provides a hardware foundation for subsequent mold correction, ensures the operability of the correction process, and allows for flexible selection of mold materials based on cost or precision requirements.

[0011] Preferably, in step S2, the pretreatment of the silicon substrate is a hydrophilization treatment, which includes cleaning with piranha solution or plasma; the imprinting adhesive is polydimethylsiloxane (PDMS), and the ratio of the PDMS prepolymer to the curing agent is (7-10):1. Cleaning with piranha solution or plasma can achieve an ultra-clean and high-energy state on the silicon substrate surface, enhancing adhesion to the imprinting adhesive. Therefore, during imprinting and demolding, the imprinting adhesive pattern can firmly adhere to the silicon substrate, preventing displacement or detachment and ensuring pattern fidelity. The specific ratio range of the PDMS prepolymer to the curing agent ensures that the imprinting adhesive has both sufficient fluidity to fill the mold and the ability to cure and set.

[0012] As a further preferred option, in step S2, the coating thickness of the imprinting adhesive is determined according to the height of the lens structure pattern: when the height of the lens structure pattern is less than 5 micrometers, spin coating is used; when the height of the lens structure pattern is greater than or equal to 5 micrometers, solution self-leveling is used. Before coating, the prepared polydimethylsiloxane is subjected to vacuuming or static treatment to remove air bubbles. The purpose of adopting the above technical solution is that: when the lens is thin (less than 5 micrometers), spin coating can accurately control the adhesive layer thickness; when the lens is thick (greater than or equal to 5 micrometers), solution self-leveling can ensure uniform coverage of the adhesive layer and reduce air bubbles, thereby ensuring the molding quality of lens arrays of different specifications. De-bubbling the prepared polydimethylsiloxane before coating can prevent defects such as pinholes after etching.

[0013] Preferably, in step S3, the imprinting is performed under vacuum conditions, and the imprinting adhesive is cured by heat curing at a temperature of 60-100℃, with the curing time determined by the curing temperature. Imprinting under vacuum conditions avoids air residue at the bottom of the mold's concave surface, which could cause graphic defects. This ensures that the imprinting adhesive can completely replicate the microstructure on the mold, resulting in a clear and bubble-free convex lens array after curing, thus improving the integrity of the graphic transfer.

[0014] Preferably, in step S4, the fixed dry etching process is inductively coupled plasma (ICP) etching, using a mixed gas composed of SF6, C4F8, and Ar. By adjusting the gas ratio, power, and pressure, a stable etching selectivity ratio of polydimethylsiloxane to silicon is obtained. Using a fixed ICP process and specific etching gas establishes a stable and repeatable etching environment, fixing the etching selectivity ratio of the imprint adhesive to the silicon substrate. This provides a reliable mathematical model for the reverse die correction calculation in step S5, a prerequisite for achieving controllable surface shape. After dry etching, the silicon substrate can be cleaned to remove residual adhesive from its surface.

[0015] Preferably, in step S5, a testing instrument with nanometer-level resolution is used to test the surface parameters of the preliminary silicon lens array. By using a testing instrument with nanometer-level resolution (such as UA3P), minute deviations between the preliminary silicon lens array and the design target can be accurately captured, providing accurate data input for quantitative correction of the mold and ensuring the surface accuracy of the final product.

[0016] Preferably, the final silicon lens array is a convex lens array, with a surface shape including spherical or aspherical surfaces. The array arrangement and fill rate are determined according to optical design requirements. This invention, through mold correction, overcomes the limitation of traditional hot reflow methods, which can only produce spherical lenses. It can stably prepare aspherical lens arrays for aberration correction, and the fill rate of the array can be adjusted according to system design requirements, thus expanding the application range of silicon lenses.

[0017] Compared with existing technologies, this invention has the following advantages: The method of this invention, through a closed-loop strategy of surface shape control based on mold iterative correction, shifts the surface shape control of silicon lenses from precise adjustment of etching process parameters to precise mold processing and iterative correction. This eliminates the need for repeated adjustments to the unstable dry etching process to correct surface shape deviations, as in traditional methods. The method of this invention, through a closed-loop process of "mold preparation—imprint etching—measurement—mold correction—formal production," can fabricate silicon lens arrays with high fill factor, accurate surface shape (including spherical and aspherical), and excellent uniformity in a highly repeatable and high-throughput manner. This solves the problem of surface shape inconsistency caused by etching process fluctuations in traditional methods, improving the stability of batch production. The silicon lens arrays fabricated by the method of this invention can significantly improve the coupling efficiency of optical systems and reduce optical losses, showing great application potential. This method is particularly suitable for fabricating aspherical silicon lens arrays required for the infrared band. Attached Figure Description

[0018] Figure 1 This is a front view schematic diagram of the initial mold in Examples 1 and 2; Figure 2 This is a schematic diagram showing the relative positions of the imprinting template, imprinting adhesive, and silicon substrate before imprinting in Examples 1 and 2. Figure 3 This is a schematic diagram showing the relative positions of the imprinting template, imprinting adhesive, and silicon substrate during imprinting in Examples 1 and 2. Figure 4 This is a schematic diagram of the silicon substrate with a PDMS convex lens array on its surface obtained after demolding in Examples 1 and 2. Figure 5 This is a schematic diagram of the silicon lens array after the imprinted adhesive convex lens array is transferred to the silicon substrate in Examples 1 and 2; Figure 6 This is a schematic diagram illustrating the secondary processing of the mold to obtain the corrected mold in Examples 1 and 2; Figure 7 This is a schematic diagram of the final silicon lens arrays prepared in Examples 1 and 2; Figures 1-7 The specific reference numerals in the attached figures are as follows: 1-Initial mold, 11-Design surface structure, 2-Imprint adhesive, 3-Silicon substrate, 21-PDMS convex lens array, 31-Preliminary silicon lens array, 12-Finish surface structure, 13-Finish mold, 32-Final silicon lens array. Detailed Implementation

[0019] To more clearly illustrate the objectives, technical solutions, and advantages of this invention, the technical solutions in the embodiments of the invention will be described in detail and completely below with reference to the accompanying drawings. It should be understood that the following embodiments are only for illustrating the invention and are not intended to limit the invention. The embodiments described herein are only some embodiments of the invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Raw materials, processes, equipment, etc., not limited in this invention, all adopt conventional technical means in the art.

[0020] Example 1: A method for fabricating a silicon lens array with controllable surface shape based on a metal mold, comprising the following steps: S1. A metal mold with a concave lens array surface is prepared by machining a nickel-phosphorus alloy with a single-point diamond turning. This metal mold is used as the initial mold 1 with the designed surface structure 11.

[0021] Nickel-phosphorus alloys possess high hardness and a low coefficient of friction, enabling high-precision machining and facilitating easy demolding. Single-point diamond turning is an ultra-precision machining technique with extremely high motion accuracy and very low surface roughness. Other materials and machining methods with similar functions that can achieve the same results can also be used; no specific limitations are made here.

[0022] In Example 1, the initial mold 1 has a concave lens array with a square arrangement, a microlens diameter of 30 μm, and a fill factor >99%. Understandably, other arrangements include hexagonal, triangular, and staggered arrangements, and the microlens diameter can range from tens to hundreds of micrometers. The fill factor is determined by project requirements and optical design, and is not limited here.

[0023] S2. Prepare single-crystal silicon that meets the requirements for semiconductor device fabrication, specifically with the following crystal phase: <111> The wafer-level silicon wafers were laser-cut to the designed size to serve as silicon substrate 3. A piranha solution was prepared on-site by mixing concentrated sulfuric acid and 30% hydrogen peroxide solution at a volume ratio of 3:1. After pre-cleaning, the cut silicon wafers were immersed in the piranha solution at 80°C for 2 hours for hydrophilication treatment. The piranha solution further removes organic matter from the surface of silicon substrate 3 and creates a hydroxyl-rich, ultra-clean, high-energy-state surface, thus exhibiting strong hydrophilicity and facilitating the adhesion of imprinting adhesive 2 to silicon substrate 3. After hydrophilication treatment, imprinting adhesive 2, which is Dow Corning 184 series polydimethylsiloxane (PDMS), was coated onto silicon substrate 3. The preparation and coating method of the imprinting adhesive 2 is as follows: Dow Corning 184 series polydimethylsiloxane prepolymer and curing agent are mixed at a ratio of 10:1, and then stirred with a magnetic stirrer for 20 minutes to ensure thorough mixing, thus obtaining a PDMS solution; then the hydrophilicated silicon substrate 3 is placed at the bottom of an open container, and the PDMS solution is poured into the open container. After that, the air bubbles generated during the stirring process are removed by standing for more than 30 minutes.

[0024] In Example 1, the ratio between the PDMS precursor and the curing agent can be adjusted according to time requirements. A higher proportion of curing agent can appropriately shorten the curing time in step S3, resulting in higher hardness of PDMS. The etching time of ICP in step S4 needs to be adjusted accordingly. It is understandable that adjustments can be made according to actual needs, without specific limitations.

[0025] In Example 1, the imprinting adhesive 2 is coated using a solution self-leveling method. PDMS naturally spreads into a PDMS layer of a certain thickness in an open container containing a silicon substrate 3. For scenarios with strict requirements on the thickness of the PDMS layer, spin coating or other methods can be selected to apply the imprinting adhesive 2. It is understandable that adjustments can be made according to actual needs, without specific limitations.

[0026] S3. Using the initial mold 1, the silicon substrate 3 coated with imprinting adhesive 2 is imprinted. After curing, it is demolded, forming an imprinting adhesive convex lens array on the silicon substrate 3. Specifically, during the imprinting process, the initial mold 1 is fixed on the upper shaft of the imprinting equipment, and the silicon substrate 3 coated with imprinting adhesive 2 and the open container are fixed on the lower shaft of the imprinting equipment. The relative positions of the imprinting template, imprinting adhesive 2, and silicon substrate 3 before imprinting are shown in the schematic diagram below. Figure 2 As shown; the upper and lower shafts are driven by high-precision servo motors and equipped with pressure sensors. The entire imprinting chamber is sealed by a quartz tube and a rubber sleeve on the lower platform, allowing for vacuuming, and is also equipped with a heating device. During imprinting, the entire chamber is evacuated to 10... -3Pa, then control the upper axis with the imprinting mold to move downwards, set the pressure to 30kN, and when imprinting is complete, the chamber temperature is raised to 80℃ at a rate of 5℃ / min and maintained for 2 hours, then cooled to room temperature at a rate of 2℃ / min to obtain a silicon-PDMS structure. The schematic diagram of the relative positions of the imprinting template, imprinting adhesive 2 and silicon substrate 3 during the above imprinting process is shown in the figure. Figure 3 As shown; a schematic diagram of the structure of the silicon substrate 3 with the PDMS convex lens array 21 on its surface obtained after demolding is shown. Figure 4 As shown.

[0027] S4. Dry etching of the silicon-PDMS structure was performed using an inductively coupled plasma etching (ICP) machine. The process is as follows: First, the etching chamber was cleaned for 30 minutes using the equipment's preset process. Then, the etched sample was placed into the etching chamber, and the chamber was evacuated to 10°C. -5 Pa, HF power set to 60W, ICP power set to 400W, etching gas a mixture of SF6, C4F8, and Ar, with flow rates of SF6, C4F8, and Ar at 15 sccm, 7 sccm, and 4 sccm respectively. After exploration, the etching time was set to 15 minutes to completely remove the PDMS imprinting adhesive 2, forming a preliminary silicon lens array 31. A schematic diagram of the silicon lens array after transferring the imprinting adhesive convex lens array to the silicon substrate 3 is shown below. Figure 5 As shown.

[0028] In Example 1, because the etching rates of the imprint adhesive 2 and the silicon substrate 3 are different during the etching process, the surface shape of the silicon lens array after etching is different from the designed surface shape, as shown below. Figure 1 The design surface structure 11 in the two are not the same. In conventional methods, the etching rate of the imprinting adhesive 2 and silicon can be controlled by controlling the etching process. However, this process requires precise adjustment of the dry etching process parameters and has low stability. Therefore, the method of the present invention achieves control of the surface shape of the silicon lens array by correcting the mold and fixing the etching process.

[0029] S5. The surface parameters of the preliminary silicon lens array 31 are tested using a UA3P testing instrument with nanometer-level resolution. Test items include PV value, aspheric coefficient, and two-dimensional profile. The tested radius of curvature, aperture, and aspheric coefficient of the silicon lens array prepared under the given process are compared with the target design parameters of the designed surface structure 11. A deviation model is established based on the deviation obtained from the comparison, and correction calculations are performed. Then, based on the corrected surface parameters, a new CAD drawing is generated. The mold is then further processed using single-point diamond turning on the basis of the original metal mold. Figure 6 As shown, a correction mold 13 with a correction face shape structure 12 is obtained.

[0030] S6. Using the correction mold 13, repeat steps S2 to S4. The final silicon lens array 32 prepared is consistent with the designed surface structure 11 after testing. Figure 7 As shown.

[0031] Using the corrected mold, rapid, large-scale, and consistent silicon lens array fabrication can be achieved without changing the ICP etching process.

[0032] In Example 1, the metal mold is almost undamaged during the imprinting process. The residual imprinting adhesive on the metal mold can also be etched by ICP without any damage to the metal mold.

[0033] Example 2: A method for fabricating a silicon lens array with controllable surface shape based on a polymer mold, comprising the following steps: S1. Polymethyl methacrylate (acrylic) is machined by single-point diamond turning to prepare a polymer mold with a concave lens array surface. This polymer mold is used as the initial mold 1 with the designed surface structure 11 (e.g., Figure 1 (As shown).

[0034] In Example 2, the initial mold 1 has a hexagonal arrangement of concave lens array surfaces, with a microlens diameter of 100 μm and a fill factor of >99%.

[0035] S2. Prepare single-crystal silicon that meets the requirements for semiconductor device fabrication, specifically with the following crystal phase: <111> The wafer-level silicon wafers were laser-cut to the designed size to serve as silicon substrate 3. A piranha solution was prepared on-site by mixing concentrated sulfuric acid and 30% hydrogen peroxide solution at a volume ratio of 3:1. After pre-cleaning, the cut silicon wafers were immersed in the piranha solution at 80°C for 2 hours for hydrophilization treatment. After hydrophilization treatment, an imprinting adhesive 2, which is Dow Corning 184 series polydimethylsiloxane (PDMS), was coated onto the silicon substrate 3. The preparation and coating method of the imprinting adhesive 2 is as follows: the Dow Corning 184 series PDMS prepolymer and curing agent were mixed at a ratio of 8:1, and stirred with a magnetic stirrer for 20 minutes to obtain a PDMS solution; then the hydrophilized silicon substrate 3 was placed at the bottom of an open container, and the PDMS solution was poured into the open container. The mixture was then allowed to stand for more than 30 minutes to remove air bubbles generated during stirring.

[0036] In Example 2, the imprinting adhesive 2 is coated using a solution self-leveling method. PDMS naturally spreads into a PDMS layer of a certain thickness in an open container containing a silicon substrate 3.

[0037] S3. Using the initial mold 1, the silicon substrate 3 coated with imprinting adhesive 2 is imprinted. After curing, it is demolded, forming an imprinting adhesive convex lens array on the silicon substrate 3. Specifically, during the imprinting process, the initial mold 1 is fixed on the upper shaft of the imprinting equipment, and the silicon substrate 3 coated with imprinting adhesive 2 and the open container are fixed on the lower shaft of the imprinting equipment. The relative positions of the imprinting template, imprinting adhesive 2, and silicon substrate 3 before imprinting are shown in the schematic diagram below. Figure 2 As shown; the upper and lower shafts are driven by high-precision servo motors and equipped with pressure sensors. The entire imprinting chamber is sealed by a quartz tube and a rubber sleeve on the lower platform, allowing for vacuuming, and is also equipped with a heating device. During imprinting, the entire chamber is evacuated to 10... -3 Pa, then control the upper axis with the imprinting mold to move downwards, set the pressure to 40kN, and when imprinting is complete, the chamber temperature is raised to 80℃ at a rate of 5℃ / min and maintained for 1.5 hours, then cooled to room temperature at a rate of 2℃ / min to obtain a silicon-PDMS structure. A schematic diagram of the relative positions of the imprinting template, imprinting adhesive 2, and silicon substrate 3 during the above imprinting process is shown below. Figure 3 As shown; a schematic diagram of the structure of the silicon substrate 3 with the PDMS convex lens array 21 on its surface obtained after demolding is shown. Figure 4 As shown.

[0038] S4. Dry etching of the silicon-PDMS structure was performed using an inductively coupled plasma etching (ICP) machine. The process is as follows: First, the etching chamber was cleaned for 30 minutes using the equipment's preset process. Then, the etched sample was placed into the etching chamber, and the chamber was evacuated to 10°C. -5 Pa, HF power set to 60W, ICP power set to 500W, etching gas a mixture of SF6, C4F8, and Ar, with flow rates of SF6, C4F8, and Ar at 15 sccm, 4 sccm, and 6 sccm respectively. After experimentation, the etching time was set to 24 minutes to completely remove the PDMS imprinting adhesive 2, forming a preliminary silicon lens array 31. A schematic diagram of the silicon lens array after transferring the imprinting adhesive convex lens array to the silicon substrate 3 is shown below. Figure 5 As shown.

[0039] S5. The surface parameters of the preliminary silicon lens array 31 are tested using a white light interferometer. Test items include PV value, aspheric coefficient, and two-dimensional profile. The tested radius of curvature, aperture, and aspheric coefficient of the silicon lens array prepared under the given process are compared with the target design parameters of the designed surface structure 11. A deviation model is established based on the deviation obtained from the comparison, and correction calculations are performed. Then, based on the corrected surface parameters, a new CAD drawing is generated. The mold is then further processed using single-point diamond turning on the basis of the original metal mold. Figure 6 As shown, a correction mold 13 with a correction face shape structure 12 is obtained.

[0040] S6. Using the correction mold 13, repeat steps S2 to S4. The final silicon lens array 32 prepared is consistent with the designed surface structure 11 after testing. Figure 7 As shown.

[0041] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make various adjustments to the mold material, processing method, type of imprinting adhesive, and combination of etching gases within the technical scope of the present invention, and these adjustments should all be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a silicon lens array with controllable surface shape, characterized in that, Includes the following steps: S1. Prepare an initial mold with a concave lens array surface; S2. Pre-treat the silicon substrate and coat the pre-treated silicon substrate with imprinting adhesive. S3. Using the initial mold, the silicon substrate coated with imprinting adhesive is imprinted, and after curing, it is demolded to form an imprinting adhesive convex lens array on the silicon substrate. S4. Using a fixed dry etching process, the imprinted resist convex lens array is transferred to a silicon substrate to form a preliminary silicon lens array. S5. Test the surface parameters of the initial silicon lens array and compare them with the target design parameters. Based on the comparison results, perform quantitative correction processing on the surface of the concave lens array of the initial mold to obtain the correction mold. S6. Repeat steps S2 to S4 using the correction mold to obtain the final silicon lens array whose surface shape meets the design requirements.

2. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, The quantitative correction process described in step S5 is based on the etching selectivity model of the fixed dry etching process, which is used to perform reverse calculations to convert the measured silicon lens surface deviation into the compensation amount required for the mold surface.

3. The method for fabricating a silicon lens array with controllable surface shape according to claim 1 or 2, characterized in that, The initial mold is made of a material that can be machined with ultra-precision and secondary correction. The initial mold is a metal mold, a silicon-based mold, a glass-based mold, or a polymer mold.

4. The method for fabricating a silicon lens array with controllable surface shape according to claim 3, characterized in that, The metal mold is a nickel, nickel-phosphorus alloy, or aluminum alloy mold produced by single-point diamond turning; the silicon-based mold is prepared by femtosecond laser scanning combined with anisotropic or isotropic wet etching process; the glass-based mold is prepared by precision hot pressing process; and the polymer mold is an epoxy resin or polymethyl methacrylate mold produced by single-point diamond turning.

5. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, In step S2, the pretreatment of the silicon substrate is a hydrophilization treatment, which includes cleaning with piranha solution or plasma; the imprinting adhesive is polydimethylsiloxane, and the ratio of the prepolymer of polydimethylsiloxane to the curing agent is (7-10):

1.

6. The method for fabricating a silicon lens array with controllable surface shape according to claim 5, characterized in that, In step S2, the coating thickness of the imprinting adhesive is determined according to the height of the lens structure pattern: when the height of the lens structure pattern is less than 5 micrometers, spin coating is used; when the height of the lens structure pattern is greater than or equal to 5 micrometers, solution self-leveling is used; before coating, the prepared polydimethylsiloxane is vacuumed or allowed to stand to remove air bubbles.

7. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, In step S3, the imprinting is performed under vacuum conditions, and the imprinting adhesive is cured by heat curing at a temperature of 60-100℃.

8. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, In step S4, the fixed dry etching process is inductively coupled plasma etching, which uses a mixed gas composed of SF6, C4F8 and Ar. By adjusting the gas ratio, power and pressure, a stable etching selectivity ratio of polydimethylsiloxane to silicon is obtained.

9. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, In step S5, the surface parameters of the preliminary silicon lens array are tested using a testing instrument with nanometer-level resolution.

10. The method for fabricating a silicon lens array with controllable surface shape according to claim 1, characterized in that, The final silicon lens array is a convex lens array, and its surface shape includes spherical or aspherical surfaces. The array arrangement and fill rate are determined according to the optical design requirements.

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