Infrared lens manufacturing method and infrared camera module

Abstract

The invention relates to a manufacturing method of an infrared lens, which comprises the following steps: S1, manufacturing a plurality of first photoresist patterns on one surface of a wafer, each first photoresist pattern comprising a plurality of columnar structures, and the columnar structures are arranged at intervals and perpendicular to the surface of the wafer; s2, etching the wafer by using each first photoresist pattern as a mask to obtain a plurality of super-structure surface structures; s3, manufacturing a plurality of second photoresist patterns on the other surface of the wafer, wherein each second photoresist pattern is in a curved surface shape; s4, the second photoresist patterns serve as masks, the wafer is etched to obtain a plurality of convex structures, and the convex structures and the super-structure surface structures are located on the two opposite sides of the wafer respectively; and S5, the wafer is cut to obtain a plurality of single infrared lenses, and each infrared lens comprises a metasurface structure and a convex surface structure. The invention further provides an infrared camera module. A wafer-level semiconductor manufacturing process is utilized, the cost is low, the efficiency is high, and batch manufacturing is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared optical imaging technology, in particular to a manufacturing method of an infrared lens and an infrared camera module. BACKGROUND

[0002] Infrared optical technology is a technology that uses infrared band light for optical imaging and measurement, and is widely used in thermal imaging, remote sensing, medical diagnosis and other fields. With the rapid development of infrared technology, infrared cameras can achieve good imaging effect at night and in harsh environments, so the market demand for them is increasing. In addition to being widely used in the military field, in recent years, with the popularization of infrared detection technology, great breakthroughs have been made in important fields such as security monitoring, surveying and mapping, non-contact temperature measurement, outdoor sports, industrial detection, smart home, etc. The infrared optical lens is an important component. The development of infrared imaging optical systems has become a key factor in the development of infrared detection technology, requiring the thinning and miniaturization of infrared imaging equipment, i.e. the number and structure of the lenses in the optical imaging system need to be limited; the increasingly low cost and high resolution and performance of infrared imaging equipment also represent the need for optical systems to have lower cost and high performance.

[0003] In related infrared imaging technology, long-wave infrared lenses are mainly processed by traditional methods such as cold processing, single-point turning or molding, and the materials are mainly germanium single crystals and chalcogenide materials.

[0004] Optical elements processed in the above manner use traditional design schemes, each lens must have a certain optical power, i.e. must have a certain curvature and thickness. When the optical power distribution is insufficient or the aberration correction ability is insufficient, the number of lenses needs to be further increased, so it is not conducive to the realization of lightweight and miniaturization, and the volume and weight cannot be effectively reduced. At the same time, the traditional design scheme has high material and processing costs, and the production capacity and yield are strictly limited by the processing capacity, which limits the cost to a range that cannot be widely applied, limiting the application of infrared imaging technology in the consumer market. SUMMARY

[0005] The purpose of the present application is to provide a manufacturing method of an infrared lens and an infrared camera module, which can at least solve some of the defects in the prior art.

[0006] To achieve the above purpose, the embodiments of the present application provide the following technical scheme: a manufacturing method of an infrared lens, comprising the following steps:

[0007] S1, a plurality of first photoresist patterns are made on one side of the wafer, each first photoresist pattern comprises a plurality of columnar structures, and each columnar structure is spaced apart and perpendicular to the surface of the wafer;

[0008] S2, etching the wafer to obtain a plurality of super-structured surfaces using each first photoresist pattern as a mask;

[0009] S3, making a plurality of second photoresist patterns on the other side of the wafer, each second photoresist pattern being curved in shape;

[0010] S4, etching the wafer to obtain a plurality of convex structures using each second photoresist pattern as a mask, the convex structures and the super-structured surfaces being respectively located on opposite sides of the wafer;

[0011] S5, cutting the wafer to obtain a plurality of single infrared lenses, each infrared lens comprising a super-structured surface and a convex structure.

[0012] Further, after the super-structured surface of the wafer is made, the super-structured surface is first protected, then the wafer is turned over, and then the convex structure is made.

[0013] Further, the method for protecting the super-structured surface is specifically:

[0014] Filling polyimide or silicon oxide between adjacent columnar structures of the super-structured surface, and causing the polyimide or silicon oxide to overflow outside the super-structured surface and form a protective layer.

[0015] Further, after the convex structure is made, the polyimide is released by using oxygen plasma release process, or the silicon oxide is released by using HF solution or HF gas.

[0016] Further, the cross-sectional shape of each columnar structure of the first photoresist pattern is one or more of a circle, a triangle, and a rectangle, and the thickness of the first photoresist pattern ranges from 0.1 to 50 μm, and the diameter of the first photoresist pattern ranges from 0.1 to 8 μm.

[0017] Further, the height of the columnar structure of the super-structured surface ranges from 1 to 100 μm.

[0018] Further, in the S3 step, an infrared lens is used for image alignment to obtain a second photoresist pattern of a curved shape consistent with the diameter of the infrared lens.

[0019] Further, after the S2 step, a temporary substrate is bonded to one side of the super-structured surface of the wafer, and the other side of the wafer is thinned using the substrate as a gripping part, and after thinning, the substrate is removed, and in the S3 step, the second photoresist pattern is made on the thinned side.

[0020] Further, the wafer is cut into single infrared lenses by a knife wheel cutting process or a plasma cutting process.

[0021] The embodiment of the present application provides another technical scheme: an infrared camera module, comprising an infrared lens, wherein the infrared lens is manufactured by using the manufacturing method of the infrared lens.

[0022] Compared with the prior art, the present application has the beneficial effects that: when the super-structured surface structure and the first convex surface structure are manufactured on two surfaces of the wafer respectively, the plasticity of the photoresist is ingeniously utilized, a plurality of photoresist patterns similar to the shapes of the super-structured surface structure and the first convex surface structure are obtained after the photoresist is patterned, and a plurality of infrared lenses are obtained at one time through the etching process, so that batch manufacturing is realized. Compared with the prior manufacturing method, the manufacturing process is simplified, the manufacturing efficiency is improved, and the cost is low and the consistency is good. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A schematic diagram of coating photoresist on a wafer in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0024] Figure 2 A schematic diagram of patterning the photoresist to obtain a plurality of first photoresist patterns in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0025] Figure 3 A schematic diagram of etching to obtain a plurality of super-structured surface structures in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0026] Figure 4 A schematic diagram of protecting the super-structured surface structure in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0027] Figure 5 A schematic diagram of coating photoresist after turning over the wafer and performing pattern alignment by using the infrared lens in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0028] Figure 6 A schematic diagram of patterning the photoresist to obtain a plurality of second photoresist patterns in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0029] Figure 7 A schematic diagram of etching to obtain a plurality of convex surface structures in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0030] Figure 8 A structural schematic diagram of releasing the protective material in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0031] Figure 9 A schematic diagram of cutting the wafer to obtain a plurality of single infrared lenses in the manufacturing method of the infrared lens provided by the embodiment of the present application;

[0032] Figure 10 A structural schematic diagram of an infrared lens of an infrared camera module provided by an embodiment of the present application;

[0033] In the drawing, 1 is a first photoresist layer; 2 is a wafer; 3 is a first photoresist pattern; 4 is a super-structured surface structure; 5 is a second photoresist layer; 6 is a second photoresist pattern; 7 is a convex structure; and 8 is a protective layer. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0035] Please refer to Figures 1 to 10 The present application provides a manufacturing method of an infrared lens, comprising the following steps: S1, manufacturing a plurality of first photoresist patterns 3 on one side of a wafer 2, each first photoresist pattern 3 comprising a plurality of columnar structures, and each columnar structure being spaced apart and perpendicular to the surface of the wafer 2; S2, using each first photoresist pattern 3 as a mask to etch the wafer 2 to obtain a plurality of super-structured surface structures 4; S3, manufacturing a plurality of second photoresist patterns 6 on the other side of the wafer 2, each second photoresist pattern 6 being in a curved surface shape and consistent with the diameter of an infrared lens; S4, using each second photoresist pattern 6 as a mask to etch the wafer 2 to obtain a plurality of convex structures 7, and the convex structures 7 and the super-structured surface structures 4 being respectively located on opposite sides of the wafer 2; and S5, cutting the wafer 2 to obtain a plurality of single infrared lenses, each infrared lens comprising a super-structured surface structure 4 and a convex structure 7. In the present embodiment, the wafer-level semiconductor manufacturing process is used, which is low in cost, good in consistency, and high in efficiency, and is conducive to batch manufacturing. Specifically, when the super-structured surface structures 4 and the convex structures 7 are manufactured on the two sides of the wafer 2, the plasticity of the photoresist is ingeniously used, and a plurality of photoresist patterns similar in shape to the super-structured surface structures 4 and the convex structures 7 can be obtained after the photoresist is patterned, and a plurality of infrared lenses can be obtained at one time through an etching process, thereby realizing batch manufacturing. Compared with the existing manufacturing method, the manufacturing process is simplified, the manufacturing efficiency is improved, the cost is low, and the consistency is good. Preferably, the wafer 2 can be a silicon wafer. Preferably, the curved surface shape can be a hemispherical shape.

[0036] Please refer to Figures 1 to 10After the super-structured surface 4 of the wafer 2 is completed, the super-structured surface 4 is first protected, then the wafer 2 is turned over, and then the first convex structure 7 is made. The protection can avoid the super-structured surface 4 from being damaged after being turned over. The action of turning over is also convenient for making the first convex structure 7 on the other side of the wafer 2.

[0037] Further refine the above scheme, please refer to Figure 4 There are two methods for protecting the super-structured surface 4, such as filling polyimide in the super-structured surface, and then performing surface planarization after high-temperature curing; or filling silicon oxide in the super-structured surface 4, and then performing surface planarization. Specifically, one is to fill polyimide between adjacent columnar structures of the super-structured surface 4, and make the polyimide overflow to the outside of the super-structured surface 4 and form a protection layer 8, or the second is to fill silicon oxide between adjacent columnar structures of the super-structured surface 4, and make the silicon oxide overflow to the outside of the super-structured surface 4 and form a protection layer 8. Correspondingly, after the first convex structure 7 is completed, as shown in Figure 8 , the protection material needs to be removed before being cut into a single infrared lens, so when the protection material is polyimide, an oxygen plasma release process is used to release the polyimide, and when the protection material is silicon oxide, an HF solution or HF gas is used to release the silicon oxide.

[0038] Please refer to Figure 2 , the cross-sectional shape of each columnar structure of the first photoresist pattern 3 is one or more of a circle, a triangle, and a rectangle, and the thickness of the first photoresist pattern 3 ranges from 0.1 to 50 μm, and the diameter of the first photoresist pattern 3 ranges from 0.1 to 8 μm, that is, the diameter of the entire first photoresist pattern 3 ranges from 0.1 to 8 μm. As shown in Figure 1 , in the first step, a double-side polished single crystal wafer 2 is prepared, a first layer of photoresist 1 is spin-coated or sprayed on one side, and the thickness of the photoresist ranges from 0.1 to 50 um, and then as shown in Figure 2 , the photoresist is patterned, that is, exposed and developed, to form a circular pattern with a sub-wavelength size, or a triangular pattern, a rectangular pattern, or other specific design patterns.

[0039] Please refer to Figure 3 , the photoresist pattern is used as a mask to perform a deep silicon etching process to form a silicon column super-structured surface 4 with a specific depth on the silicon wafer, and the depth ranges from 1 to 100 um, that is, the height of the columnar structure ranges from 1 to 100 um.

[0040] Please refer to Figure 5In the S3 step, image alignment is performed using an infrared lens to obtain a second photoresist pattern 6 with a curved surface shape consistent with the diameter of the infrared lens. In this embodiment, after the wafer 2 is turned over and a second layer of photoresist 5 is spin-coated or sprayed, image alignment is performed using an infrared lens, and exposure and development are performed so that the photoresist forms a pattern with the size of a lens.

[0041] Referring to Figure 6 The second photoresist pattern 6 is made using a thermal reflow process or a nanoimprint process. In this embodiment, there are two methods for making the second photoresist pattern 6. One method is to melt the photoresist and then reflow it into the curved surface shape of a lens by a high-temperature thermal reflow process, with a temperature of 90-200°C and a time of 60s-5min. The other method is to directly spin-coat an imprint adhesive and use nanoimprint technology to imprint and solidify the adhesive into a designed curved surface shape.

[0042] As an optimization scheme of the embodiment of the present application, after the S2 step, a temporary substrate is temporarily bonded to one side of the super-structured surface of the wafer, and the other side of the wafer is thinned using the substrate as a gripping part. After thinning is completed, the substrate is removed, and the second photoresist pattern is made on the thinned surface in the S3 step. In this embodiment, since the infrared transmittance of the wafer is inversely proportional to the thickness of the wafer, in order to improve the infrared transmittance of the lens, the super-structured surface structure side of the wafer can be temporarily bonded to a temporary substrate by using adhesive, paraffin wax or photoresist and other materials. The substrate can be silicon, glass or other carrier materials that can be used in the semiconductor processing process. Then, the wafer is thinned to a suitable thickness by grinding and polishing. The thickness is in the range of 100-600 microns according to the design of the super-structured surface and the curved surface.

[0043] Referring to Figure 7 In the S4 step, a deep silicon etching process is used to etch the second photoresist pattern 6 to the surface of the wafer 2 to form a first convex structure 7 with a silicon curved surface. In this embodiment, by controlling the parameters such as etching gas ratio, power and time in the deep silicon etching process, the curved photoresist pattern is etched to the silicon surface to form a silicon curved surface.

[0044] Referring to Figure 9 The wafer is cut into individual infrared lenses by a knife wheel cutting or plasma cutting process. Specifically, when the plasma cutting process is used, photoetching, etching and cleaning are performed first, and then the cutting area is separated by etching. In this way, all lenses on the wafer can be cut at the same time, which is high in production efficiency and low in cost. Moreover, the lenses cut by the plasma cutting process can have any shape, such as a hexagonal shape, an octagonal shape and other special shapes, which is beneficial to the subsequent assembly of the lenses.

[0045] Referring to Figures 1 to 10The embodiment of the present application provides an infrared camera module, comprising an infrared lens, the infrared lens is manufactured by using the manufacturing method of the infrared lens, and the infrared lens is like Figures 1 to 9 is a continuous manufacturing process. Figure 10 As shown in the figure, the infrared lens comprises a wafer 2, one side of the wafer 2 is provided with a super-structured surface structure 4, and the other side is provided with a first convex surface structure 7, and one hemispherical surface and one super-structured surface constitute an independent optical element, the structure mode can combine the advantages of the two surface types, efficiently utilize the optical element, realize light focusing and aberration control, improve imaging quality, reduce cost, reduce system weight and reduce system volume.

[0046] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing an infrared lens, characterized in that, Includes the following steps: S1, a plurality of first photoresist patterns are formed on one side of the wafer. Each first photoresist pattern includes a plurality of columnar structures, and each columnar structure is spaced apart and perpendicular to the surface of the wafer. S2, using each of the first photoresist patterns as a mask, the wafer is etched to obtain several metasurface structures; S3, several second photoresist patterns are fabricated on the other side of the wafer, each of which is a curved surface. S4, using each of the second photoresist patterns as a mask, the wafer is etched to obtain several convex structures, wherein the convex structures and the metasurface structures are located on opposite sides of the wafer. S5, the wafer is cut to obtain several individual infrared lenses, each of which includes a metasurface structure and a convex structure.

2. The method for manufacturing an infrared lens as described in claim 1, characterized in that: After the metasurface structure of the wafer is fabricated, the metasurface structure is first protected, then the wafer is flipped over, and the convex structure is fabricated.

3. The method for manufacturing an infrared lens as described in claim 2, characterized in that: The specific methods for protecting metasurface structures are as follows: Polyimide or silicon dioxide is filled between adjacent columnar structures of the metasurface structure, and the polyimide or silicon dioxide overflows outside the metasurface structure to form a protective layer.

4. The method for manufacturing an infrared lens as described in claim 3, characterized in that: After the convex structure is fabricated, an oxygen plasma release process is used to release polyimide, or an HF solution or HF gas is used to release silicon oxide.

5. The method for manufacturing an infrared lens as described in claim 1, characterized in that: The cross-sectional shape of each columnar structure in the first photoresist pattern is one or more of the following: circular, triangular, and rectangular. The thickness of the first photoresist pattern ranges from 0.1 to 50 μm, and the diameter of the first photoresist pattern ranges from 0.1 to 8 μm.

6. The method for manufacturing an infrared lens as claimed in claim 1, characterized in that: The height of the columnar structure of the metasurface structure ranges from 1 to 100 μm.

7. The method for manufacturing an infrared lens as described in claim 1, characterized in that: In step S3, an infrared lens is used for image alignment to obtain a second photoresist pattern with a curved shape that matches the diameter of the infrared lens.

8. The method for manufacturing an infrared lens as claimed in claim 1, characterized in that: After step S2, a substrate is temporarily bonded to one side of the metasurface of the wafer, and the other side of the wafer is thinned using the substrate as a gripping part. After the thinning is completed, the substrate is removed. In step S3, the second photoresist pattern is fabricated on the thinned surface.

9. The method for manufacturing an infrared lens as claimed in claim 1, characterized in that: The wafer is cut into individual infrared lenses using a blade cutting process or a plasma cutting process.

10. An infrared camera module, characterized in that: It includes an infrared lens, which is manufactured using the method for manufacturing an infrared lens as described in any one of claims 1-9.

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