Gray photoetching lens manufacturing method for correcting lens curvature in combination with baking process

Abstract

The invention discloses a gray-scale photoetching lens manufacturing method for correcting lens curvature in combination with a baking process. The method comprises the steps of S1, substrate surface pretreatment, S2, gray-scale photoresist plate manufacturing, S3, gray-scale photoetching, S4, post-exposure baking, S5, developing, S6, lens morphology measurement, S7, preliminary layer-by-layer progressive hot baking correction and S8, gray-scale photoetching exposure dose distribution adjustment. According to the method, the optical lens is manufactured through gray photoetching, higher controllability and the capacity of manufacturing a high-precision and complex 3D micro-nano structure are achieved, the method has more advantages on machining of aspheric lenses and even free-form lenses compared with a traditional technology, and machining of some special structures is easier. Meanwhile, the morphology curvature and height of the lens can be corrected through a subsequent baking process, so that the lens with the optimal precise optical effect can be processed; the lens template manufactured by the method is higher in consistency, better in shape and shorter in manufacturing time.

Description

Technical Field

[0001] The invention relates to the technical field of optical lens manufacturing, and in particular to a method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens. Background Art

[0002] At present, the traditional methods of making lenses include organic machining (precision carving), photolithography and other processes. Due to the limitations of processing equipment and processes, the precision of lenses made using traditional processes has a certain upper limit, and even some special structures cannot be made. Once the lens is formed, it is almost impossible to modify or adjust it on the original basis. If adjustment is required, the design parameters need to be readjusted, and a new substrate needs to be prepared for re-production. Generally, multiple rounds of adjustments are required, and this process is time-consuming and costly. Summary of the invention

[0003] In order to solve the above technical problems, the present invention designs a method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens.

[0004] The present invention adopts the following technical solution: A method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens, characterized in that the method steps are: S1. Substrate surface pretreatment: polish the upper and lower surfaces of the substrate respectively to keep the surface of the substrate flat, and clean the substrate to keep the surface of the substrate clean; S2. Grayscale photoresist plate production: adding a photoresist layer on the substrate by spin coating or spray coating, and performing thermal curing or soft baking after spin coating to obtain a photoresist plate; S3, Grayscale lithography: Import the design required pattern into the grayscale lithography equipment, place the photoresist plate on the equipment platform, adjust the exposure dose and exposure time to a suitable level, and start grayscale lithography on the photoresist plate in the corresponding exposure area; S4, post-exposure baking: placing the photoresist plate after grayscale photolithography on a hot plate for baking; S5, development: soaking the developer on the surface of the baked photoresist board, after the photoresist and the developer react, use deionized water to rinse by spin coating, and use an ion air gun to air dry or spin coat to dry the residual water stains on the surface, and a lens structure appears on the photoresist board; S6. Lens profile measurement: measuring the profile curvature and height parameters of the lens on the photoresist board, and obtaining the test results of the profile curvature and height parameters of the lens on the grayscale photoresist board; S7, preliminary layer-by-layer progressive thermal baking correction: according to the test results, set preliminary layer-by-layer progressive baking parameters, place the photoresist plate with the lens on the hot plate and the cold plate cyclically, and measure the lens morphology after each round of thermal baking correction. According to the measurement results, fine-tune the set layer-by-layer progressive baking parameters until the thermal baking correction is completed, and the morphological curvature and height parameters of the lens meet the preliminary correction requirements; S8. Grayscale photolithography exposure dose distribution adjustment: According to the result of preliminary lens production, the difference between different positions and the design value is obtained. According to the difference, the distribution of grayscale photolithography exposure dose is compensated accordingly, and the above steps S1-S6 are repeated to obtain a photoresist plate with a precisely corrected lens morphology. Then, the photoresist plate is subjected to progressive thermal baking correction layer by layer to finally obtain an optical lens whose morphology curvature and height parameters meet the final requirements.

[0005] Preferably, in step S1, the flatness of the substrate is required to be less than 5 μm.

[0006] Preferably, in steps S3 and S4, the exposure dose, exposure time, and baking temperature and time need to be adjusted according to the type and thickness of the photoresist.

[0007] Preferably, in step S7, the error between the shape curvature of the optical lens required for preliminary correction and the shape curvature of the design value is less than ±2um, and the height error is less than ±2um.

[0008] Preferably, in step S8, the error between the shape curvature of the optical lens finally obtained and the design shape curvature is less than ±1 um, and the height error is less than ±1 um.

[0009] The beneficial effects of the present invention are as follows: (1) The method of the present invention adopts grayscale photolithography to produce optical lenses, which has higher controllability and the ability to produce high-precision, complex 3D micro-nano structures. It is also more advantageous than traditional processes for processing non-spherical or even free-form surface lenses, and is easier to process for some special structures. Most importantly, the lens produced by the grayscale photolithography process can be corrected in terms of lens morphology, curvature radius, lens height, etc. through a subsequent baking process. The process is relatively simpler and more controllable, and multiple rounds of adjustments can be made in a short time to produce a lens with the best precision optical effect; (2) The lens template produced by this method has higher consistency, better morphology, and shorter production time than the lens template produced by the traditional process. DETAILED DESCRIPTION

[0010] The technical solution of the present invention is further described in detail below through specific embodiments: Example

[0011] A method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens is used to manufacture a lens with a morphology curvature of ±1um and a height parameter of 36±1um. The method steps are as follows: S1. Substrate surface pretreatment: polish the upper and lower surfaces of the substrate respectively. After polishing, the surface flatness of the substrate is TTV 5um, and the substrate is cleaned to keep the surface of the substrate clean; S2. Grayscale photoresist board production: add a photoresist layer on the substrate by spin coating or spray coating, and perform heat curing or soft baking after spin coating to obtain a photoresist board. The baking is carried out on a hot plate at a temperature of 85±10°C for 40±5 minutes, and the board is cooled for 30 minutes after baking. S3, Grayscale lithography: Import the required pattern into the grayscale lithography equipment, place the stencil on the equipment platform, and adjust the exposure dose to a suitable value. The maximum output energy of the exposure dose is 1500mJ / cm 2 (Different grayscale uses different energy), start grayscale lithography on the photoresist board in the corresponding exposure area, the total lithography time for 6 inches area takes about 40 hours; S4, post-exposure baking: placing the photoresist plate after grayscale photolithography on a hot plate for baking; the baking temperature is 100° C. and the time is 1 minute; S5, development: soaking the developer on the surface of the baked photoresist board, after the photoresist and the developer react, use deionized water to rinse by spin coating, and use an ion air gun to air dry or spin coat to dry the residual water stains on the surface, and a lens structure appears on the photoresist board; S6. Lens morphology measurement: The lens on the photoresist board is measured for shape curvature and height parameters, and the shape curvature of the lens on the grayscale photoresist board is 3.7122um, and the height parameter is 39.5um.

[0012] S7, preliminary layer-by-layer progressive thermal baking correction: according to the test results, set preliminary layer-by-layer progressive baking parameters, place the photoresist plate with the lens on the hot plate and the cold plate in a cycle, and measure the morphology of the lens after each round of thermal baking correction. According to the measurement results, fine-tune the set layer-by-layer progressive baking parameters until the thermal baking correction is completed. The first round is a baking temperature of 90°C, a time of 2 minutes, and cooling after baking. The morphology curvature becomes 2.2402um and the height becomes 38.1um. The second round is a baking temperature of 100°C, a time of 2 minutes, and cooling after baking. The morphology curvature becomes 1.1458um and the height becomes 36.9um. The third round is a baking temperature of 110°C, a time of 2 minutes, and cooling after baking. The morphology curvature becomes 0.7931um and the height becomes 36.3um. S8. Adjustment of grayscale lithography exposure dose distribution: Based on the result of preliminary lens production, the difference between different positions and the design value is obtained. After the distribution of grayscale lithography exposure dose is compensated accordingly based on the difference, the above steps S1-S6 are repeated to obtain a photoresist plate with a precisely corrected lens morphology. The photoresist plate is then subjected to progressive thermal baking correction layer by layer, and finally the lens morphology curvature becomes 0.2611um and the height becomes 35.9um.

[0013] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens, characterized in that: The method steps are: S1. Substrate surface pretreatment: polish the upper and lower surfaces of the substrate respectively to keep the surface of the substrate flat, and clean the substrate to keep the surface of the substrate clean; S2. Grayscale photoresist plate production: adding a photoresist layer on the substrate by spin coating or spray coating, and performing thermal curing or soft baking after spin coating to obtain a photoresist plate; S3, Grayscale lithography: Import the design required pattern into the grayscale lithography equipment, place the photoresist plate on the equipment platform, adjust the exposure dose and exposure time to a suitable level, and start grayscale lithography on the photoresist plate in the corresponding exposure area; S4, post-exposure baking: placing the photoresist plate after grayscale photolithography on a hot plate for baking; S5, development: soaking the developer on the surface of the baked photoresist board, after the photoresist and the developer react, use deionized water to rinse by spin coating, and use an ion air gun to air dry or spin coat to dry the residual water stains on the surface, and a lens structure appears on the photoresist board; S6. Lens profile measurement: measuring the profile curvature and height parameters of the lens on the photoresist board, and obtaining the test results of the profile curvature and height parameters of the lens on the grayscale photoresist board; S7, preliminary layer-by-layer progressive thermal baking correction: according to the test results, set preliminary layer-by-layer progressive baking parameters, place the photoresist plate with the lens on the hot plate and the cold plate cyclically, and measure the lens morphology after each round of thermal baking correction. According to the measurement results, fine-tune the set layer-by-layer progressive baking parameters until the thermal baking correction is completed, and the morphological curvature and height parameters of the lens meet the preliminary correction requirements; S8. Grayscale photolithography exposure dose distribution adjustment: According to the result of preliminary lens production, the difference between different positions and the design value is obtained. According to the difference, the distribution of grayscale photolithography exposure dose is compensated accordingly, and the above steps S1-S6 are repeated to obtain a photoresist plate with a precisely corrected lens morphology. Then, the photoresist plate is subjected to progressive thermal baking correction layer by layer to finally obtain an optical lens whose morphology curvature and height parameters meet the final requirements.

2. The method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens according to claim 1, characterized in that: In the step S1, the flatness of the substrate is required to be less than 5 μm.

3. The method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens according to claim 1, characterized in that: In the steps S3 and S4, the exposure dose, exposure time, and baking temperature and time need to be adjusted according to the type and thickness of the photoresist.

4. The method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens according to claim 1, characterized in that: In the step S7, the error between the shape curvature of the optical lens required for preliminary correction and the design value shape curvature is less than ±2um, and the height error is less than ±2um.

5. The method for manufacturing a lens by grayscale photolithography combined with a baking process to correct the curvature of the lens according to claim 1, characterized in that: In step S8, the error between the shape curvature of the optical lens finally obtained and the design shape curvature is less than ±1 um, and the height error is less than ±1 um.