A method for preparing a double-layer biomimetic compound eye microlens

Abstract

The application discloses a method for preparing a double-layer biomimetic compound eye microlens, and solves the problem that the double-layer biomimetic compound eye microlens must rely on expensive processing equipment or utilize a complex technical combination to be realized at present. The application has the advantages of low implementation threshold and low cost. The method comprises the following steps: designing a mask for preparing the double-layer biomimetic compound eye microlens; and using the mask to perform exposure and development on a positive photoresist thick coating layer, so that the double-layer biomimetic compound eye microlens can be prepared on the surface of a substrate by using an exposure and development and heat reflow process only once. The application is suitable for application fields of optical devices, microfabrication, multi-scale microstructure manufacturing and the like.

Description

Technical Field

[0001] This invention relates to the fields of optical devices, microfabrication, and multi-scale microstructure manufacturing, and specifically to a method for preparing a double-layer biomimetic compound eye microlens. Background Technology

[0002] The applications of optical imaging systems are becoming increasingly widespread, and the demands on them are constantly rising, with expectations for lightweight, compact, wide-field-of-view, and more sensitive targets. However, with advancements in detectors and computer science, single-aperture optical systems are proving less than satisfactory in fields such as automation, image recognition, and military target detection; furthermore, miniaturization of single-aperture optical systems is becoming increasingly difficult due to factors such as the diffraction limit.

[0003] Insect compound eyes are collections of many small ommatidia arranged in parallel. All these ommatidia can image independently, yet they can also receive and process data centrally. Therefore, they can meet the requirements of large field-of-view imaging while recording the depth and spectral information of the target, thus achieving rapid multi-dimensional response within a large field of view. Inspired by the advantages of insect compound eyes—small size, large field of view, and sensitivity to high-speed moving objects—biomimetic compound eye imaging systems have been proposed. The research results related to biomimetic compound eyes are now widely used in fields such as miniature compound eye cameras, radar systems, miniature aircraft, precision-guided weapons, night vision devices, and motion robots.

[0004] The artificial construction of bionic compound eyes is the first step that all related research must consider. Single-layer bionic compound eye microlenses are relatively easy to fabricate, and there are many methods available. However, fabricating double-layer bionic compound eye microlenses is much more difficult. Generally, double-layer bionic compound eye microlens structures can be fabricated using femtosecond laser processing and ultra-precision machining, or through a combination of extremely complex technologies. However, the former requires extremely expensive equipment; the latter involves cumbersome steps and has low accuracy and success rates, making implementation very difficult. These current technological limitations significantly restrict the widespread research and application of double-layer bionic compound eye microlenses. Summary of the Invention

[0005] This invention provides a method for preparing a double-layer biomimetic compound eye microlens.

[0006] The technical solution of this invention is:

[0007] 1. A method for preparing a double-layered biomimetic compound eye microlens, characterized by comprising the following steps:

[0008] S1: Design a mask for fabricating a double-layer biomimetic compound eye microlens. The mask pattern consists of small regular hexagonal patterns stacked together to form a large regular hexagon. The large regular hexagon is honeycomb-shaped. Each small regular hexagon is opaque. The distance between its two opposite sides is 30 μm, and the distance between two adjacent small regular hexagons is 3 μm, which is the light-transmitting area. The width of the light-transmitting area between two adjacent large regular hexagons is 240 μm.

[0009] S2: The fabrication of the double-layer biomimetic compound eye microlens is carried out through the following steps:

[0010] S21: Clean the substrate and spin-coat it with AZ9260 positive photoresist. Set the process parameters of the spin coater to 500rpm / 10s, 1000rpm / 60s, and 500rpm / 10s in a cycle. Drop AZ9260 photoresist onto the center of the substrate and complete the first spin coat with the above process parameters.

[0011] S22: After the first coating is completed, place the substrate on a 70℃ hot plate and heat for 5 minutes. After that, cool the substrate to room temperature.

[0012] S23: Complete the second spin coating of the substrate using the process parameters of the spin coater in S21;

[0013] S24: After the second coating is completed, place the substrate in a 90℃ oven and heat for 100 minutes. After that, cool the substrate to room temperature.

[0014] S25: Place the substrate obtained in S24 on a spin coater, set the spin coater parameters to 1000 rpm / 5 min, start the spin coater, and use a syringe to spray acetone solvent onto the edge of the substrate. A thicker ring of photoresist at the edge of the substrate is washed away by acetone. After completing this step, place the substrate on a hot plate at 90°C and heat for 10 min to remove the acetone solvent. Finally, remove the substrate and cool it to room temperature to obtain a photoresist coating with a thickness of 40 μm on the substrate.

[0015] S26: Bring the photomask from S1 into close contact with the AZ9260 photoresist coating obtained in S25, and apply 1000 mJ / cm². 2 The exposure energy is used for ultraviolet exposure;

[0016] S27: Mix AZ400K developer with deionized water at a volume ratio of 1:3 to prepare a diluted developer. Then, place the exposed substrate from S26 into the developer and develop for 30 minutes. Remove the substrate and rinse it with deionized water.

[0017] S28: Place the developed substrate from S27 on a hot plate at 130°C and heat for 25 minutes to obtain a double-layer biomimetic compound eye microlens on the substrate.

[0018] This invention offers the following advantages: It utilizes optical exposure technology and conventional thermal reflow processes to fabricate double-layer biomimetic compound eye microlenses on a substrate in a single step, solving the problem that current methods require expensive processing equipment or extremely complex technical combinations. This significantly reduces the fabrication difficulty and costs of double-layer biomimetic compound eye microlenses. Furthermore, it provides a novel technical solution for fabricating such microlenses. Attached Figure Description

[0019] Figure 1 Flowchart of the fabrication process for a double-layer biomimetic compound eye microlens.

[0020] In the image: 1. Photomask, 2. Positive photoresist, 3. Substrate.

[0021] Figure 2 A cross-sectional photograph of the prepared double-layer biomimetic compound eye microlens sample. Detailed Implementation

[0022] Detailed Implementation: A method for preparing a double-layer biomimetic compound eye microlens comprises the following steps:

[0023] S1: Design a mask for fabricating a double-layer biomimetic compound eye microlens. The mask pattern consists of small regular hexagonal patterns stacked together to form a large regular hexagon. The large regular hexagon is honeycomb-shaped. Each small regular hexagon is opaque. The distance between its two opposite sides is 30 μm, and the distance between two adjacent small regular hexagons is 3 μm, which is the light-transmitting area. The width of the light-transmitting area between two adjacent large regular hexagons is 240 μm.

[0024] S2: The fabrication of the double-layer biomimetic compound eye microlens is carried out through the following steps:

[0025] S21: Clean the substrate and spin-coat it with AZ9260 positive photoresist. Set the process parameters of the spin coater to 500rpm / 10s, 1000rpm / 60s, and 500rpm / 10s in a cycle. Drop AZ9260 photoresist onto the center of the substrate and complete the first spin coat with the above process parameters.

[0026] S22: After the first coating is completed, place the substrate on a 70℃ hot plate and heat for 5 minutes. After that, cool the substrate to room temperature.

[0027] S23: Complete the second spin coating of the substrate using the process parameters of the spin coater in S21;

[0028] S24: After the second coating is completed, place the substrate in a 90℃ oven and heat for 100 minutes. After that, cool the substrate to room temperature.

[0029] S25: Place the substrate obtained in S24 on a spin coater, set the spin coater parameters to 1000 rpm / 5 min, start the spin coater, and use a syringe to spray acetone solvent onto the edge of the substrate. A thicker ring of photoresist at the edge of the substrate is washed away by acetone. After completing this step, place the substrate on a hot plate at 90°C and heat for 10 min to remove the acetone solvent. Finally, remove the substrate and cool it to room temperature to obtain a photoresist coating with a thickness of 40 μm on the substrate.

[0030] S26: Bring the photomask from S1 into close contact with the AZ9260 photoresist coating obtained in S25, and apply 1000 mJ / cm². 2 The exposure energy is used for ultraviolet exposure;

[0031] S27: Mix AZ400K developer with deionized water at a volume ratio of 1:3 to prepare a diluted developer. Then, place the exposed substrate from S26 into the developer and develop for 30 minutes. Remove the substrate and rinse it with deionized water.

[0032] S28: Place the developed substrate from S27 on a hot plate at 130°C and heat for 25 minutes to obtain a double-layer biomimetic compound eye microlens on the substrate.

[0033] In this embodiment, the mask pattern structure and size described in step S1 can be redesigned and adjusted according to the size of the double-layer bionic compound eye microlens to be prepared. The core idea of ​​the design is that the light-transmitting area is designed in the middle of the adjacent small regular hexagons, and the light-transmitting area outside the outermost small regular hexagon is much wider than the light-transmitting area in the middle.

[0034] In this embodiment, the positive photoresist material used in step S2 is AZ9260 photoresist, but it is not limited to this and other positive photoresist materials can also be used.

[0035] In this embodiment, the substrate mentioned in step S2 is a silicon wafer, glass sheet, quartz sheet, or PET flexible substrate.

[0036] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the concept of the present invention, such as changing the mask pattern structure and size, replacing the photoresist material, changing the photolithography process parameters, replacing the rigid substrate material with a flexible substrate material, etc. These improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a double-layer biomimetic compound eye microlens, characterized in that, It comprises the following steps: S1: design a mask for preparing the double-layer biomimetic compound eye microlens, the mask pattern is composed of small regular hexagonal patterns intersecting and stacking together into a large regular hexagon, the large regular hexagon is in a honeycomb shape, each small regular hexagon itself is opaque, the distance between two opposite edges thereof is 30 μm, the distance between adjacent two small regular hexagons is 3 μm, which is a light transmission region, and the width of the light transmission region between adjacent two large regular hexagons is 240 μm; S2: preparation of the double-layer biomimetic compound eye microlens, the steps are as follows: S21: clean the substrate and spin-coat AZ9260 positive photoresist thereon, the process parameters of the spin coater are set as a cycle of 500 rpm / 10 s, 1000 rpm / 60 s and 500 rpm / 10 s, drop the AZ9260 photoresist at the center of the substrate, and complete the first spin coating according to the above process parameters; S22: after the first spin coating is completed, place the substrate on a 70℃ hot plate for heating for 5 min, and then cool the substrate to room temperature; S23: complete the second spin coating of the substrate according to the process parameters of the spin coater in S21; S24: after the second spin coating is completed, place the substrate in a 90℃ oven for heating for 100 min, and then cool the substrate to room temperature; S25: place the substrate obtained in S24 on the spin coater, set the spin coater parameters to 1000 rpm / 5 min, start the spin coater, and then use a needle tube to spray the acetone solvent at the edge of the substrate, the thick photoresist at the edge of the substrate is washed away by the acetone, after this step, place the substrate on a 90℃ hot plate for heating for 10 min to remove the acetone solvent, and finally take off the substrate and cool it to room temperature, thereby obtaining a photoresist coating with a thickness of 40 μm on the substrate; S26: The mask in S1 is brought into close contact with the AZ9260 photoresist coating obtained in S25, and ultraviolet exposure is performed at an exposure energy of 1000 mJ / cm 2 ; S27: mix AZ400K developer and deionized water according to a volume ratio of 1:3 to prepare a diluted developer, then place the substrate exposed in S26 in the developer for 30 min, and then take it out and rinse it with deionized water; S28: place the substrate developed in S27 on a 130℃ hot plate for heating for 25 min, thereby preparing the double-layer biomimetic compound eye microlens on the substrate.

2. The method of claim 1, wherein the method of preparing a double-layered biomimic compound eye microlens is characterized by, The positive photoresist material is used in step S2.

3. The method of claim 1, wherein the method of preparing a double-layered biomimic compound eye microlens is characterized by, The substrate used in step S2 is a silicon wafer, a glass wafer, a quartz wafer or a PET flexible substrate.

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