A double-sided microlens element

Abstract

The utility model discloses a kind of double-sided microlens elements, comprising: first substrate layer, antireflection film layer and second substrate layer are sequentially arranged;The side of the first substrate layer away from the antireflection film layer is formed with first microstructure layer, as first microlens group;The side of the second substrate layer away from the antireflection film layer is formed with second microstructure layer, as second microlens group.The utility model is by relatively arranged first microlens group and second microlens group, the combination of two groups of microlenses can greatly improve coupling collimation and focusing efficiency, and introduce antireflection and anti-reflection function film between double-sided microlens, namely antireflection film layer, reduce the reflected light on the surface of microlens by functional film to increase luminous flux, with higher collection efficiency;Eliminate the stray light of other waveband to obtain higher detection precision.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano optical technology, specifically relating to a double-sided microlens element. Background Technology

[0002] Microlenses are typically hemispherical three-dimensional structures with a light-transmitting aperture or surface relief depth in the micrometer range. They can be manufactured using semiconductor manufacturing technology, eliminating the need for complex and numerous lens assemblies. They utilize the principles of light refraction and diffraction to achieve functions such as wavefront segmentation, homogenization, and phase adjustment. Compared to traditional mechanical or injection-molded optical lenses, they have advantages such as small unit size, high integration, and high precision, and are widely used in optical communication, electronics, medical, and industrial fields.

[0003] Currently, the main processes for fabricating microlenses using semiconductor manufacturing technology are thermal reflow and nanoimprint lithography. Both involve first forming a three-dimensional microlens pattern on the surface of a substrate material, and then transferring it into the substrate material using dry etching. To achieve high optical performance, microlenses have very high requirements for material and surface morphology. However, when a light source is incident, the light is reflected by the microlens material, resulting in loss and reducing luminous flux and light collection ability. In addition, some light sources are absorbed by the microlens material itself, causing further loss and reducing the utilization rate of the light source. Furthermore, stray light from different wavelengths causes interference, leading to a decrease in resolution. Ultimately, all of these factors contribute to problems such as low detection accuracy, poor coupling and collimation, and unclear imaging. Utility Model Content

[0004] In view of all or part of the deficiencies of the prior art described above, the purpose of this utility model is to provide a double-sided microlens element that can significantly improve coupling collimation and focusing efficiency, increase light flux, and eliminate stray light in other bands to obtain higher detection accuracy, thus obtaining a low-loss, high-precision integrated microlens.

[0005] To achieve the above-mentioned objectives, this utility model provides the following technical solution: This invention provides a double-sided microlens element, comprising: a first substrate layer, an antireflective coating layer, and a second substrate layer sequentially disposed therefrom; a first microstructure layer is formed on the side of the first substrate layer away from the antireflective coating layer, serving as a first microlens group; a second microstructure layer is formed on the side of the second substrate layer away from the antireflective coating layer, serving as a second microlens group. This invention, through the relatively disposed first and second microlens groups, can significantly improve coupling collimation and focusing efficiency by combining the two groups of microlenses. Furthermore, the introduction of an antireflective coating layer between the double-sided microlenses reduces reflected light from the microlens surface, thereby increasing light flux and achieving higher collection efficiency; it also eliminates stray light in other wavelength bands, thus obtaining higher detection accuracy.

[0006] The antireflective coating comprises alternating stacked first and second refractive index layers, with the first refractive index layer in direct contact with the first and second substrate layers; the refractive index of the first refractive index layer is lower than that of the second refractive index layer. By setting a multilayer composite antireflective and antireflective functional film, a lower and more stable reflectivity than a single-layer antireflective film is achieved over a wider wavelength range and a larger incident angle range.

[0007] The first refractive index film has four layers, and the second refractive index film has three layers; the material of the first refractive index film is silicon dioxide, the material of the second refractive index film is amorphous silicon, and the materials of the first substrate layer and the second substrate layer are silicon.

[0008] The thickness of the first refractive index film is 30 nm, and the thickness of the second refractive index film is 50 nm. The refractive index n of the first refractive index film is 1.5, and the refractive index n of the second refractive index film is 1.9. The refractive indices and thicknesses of the first and second refractive index films are subject to very high requirements, necessitating calculations and extensive adjustments, and they must also be translucent.

[0009] Both the first microlens group and the second microlens group are composed of several microlenses arranged in an array.

[0010] Each microlens in the first microlens group corresponds to a microlens in the second microlens group, and the positions of the corresponding two microlenses overlap and are aligned. This overlap of microlens positions increases the modulation and utilization of infrared light, resulting in higher coupling accuracy and efficiency.

[0011] The microlens is hemispherical in shape and is prepared by a hot reflux process.

[0012] The diameter of a single microlens is 300 μm.

[0013] In the first and second microlens groups, the spacing between several microlenses in the same microlens group is 200 μm.

[0014] The distance between the bottom of the first microlens group and the antireflective coating is 250 μm; the distance between the bottom of the second microlens group and the antireflective coating is 250 μm.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a double-sided microlens element that significantly improves coupling collimation and focusing efficiency by utilizing double-sided microlenses. Furthermore, a multi-layered composite anti-reflection and anti-reflection functional film is introduced between the double-sided microlenses. This functional film reduces reflected light from the microlens surface, thereby increasing light flux and achieving higher collection efficiency. It can also eliminate stray light in other wavelength bands, thus obtaining higher detection accuracy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the cross-sectional structure of a double-sided microlens element in Example 1; Figure 2 This is a schematic diagram of the cross-sectional structure of the antireflective coating layer, i.e., the functional layer, in Example 1; Figure 3 This is a schematic diagram of the process for fabricating the first microlens group; Figure 4 This is a schematic diagram of the process for fabricating the second microlens group; Figure 5 This is a schematic diagram of the planar structure after the front photolithography layer is patterned.

[0018] Reference numerals: 10-First substrate layer; 11-Antireflective coating layer; 111-First refractive index coating layer; 112-Second refractive index coating layer; 12-Second substrate layer; 21-First microlens group; 22-Second microlens group; 200-Microlens; 2-Photoresist. Detailed Implementation

[0019] The technical solutions in specific embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0020] Example 1 A double-sided microlens element, see Figure 1 and Figure 2 ,include: The first base layer 10, the antireflective film layer 11, and the second base layer 12 are sequentially arranged.

[0021] A first microstructure layer is formed on the side of the first substrate layer 10 away from the antireflective coating layer 11, serving as the first microlens group 21; a second microstructure layer is formed on the side of the second substrate layer 12 away from the antireflective coating layer 11, serving as the second microlens group 22. Both the first microlens group 21 and the second microlens group 22 consist of an array of microlenses 200. The microlenses 200 are hemispherical in shape and are fabricated using a hot reflow process. In this embodiment, the diameter of a single microlens 200 is 300 μm, and the spacing between the microlenses 200 within the same microlens group in both the first and second microlens groups 21 is 200 μm. Each microlens 200 in the first microlens group 21 corresponds to one microlens 200 in the second microlens group 22, and the positions of the corresponding two microlenses 200 overlap and align (a slight offset may occur due to process errors), i.e., they are vertically aligned rather than staggered.

[0022] The first substrate layer 10 and the second substrate layer 12 are made of silicon. The first microlens group 21 is a part of the first substrate layer 10, and the second microlens group 22 is a part of the second substrate layer 12. The bottom of the first microlens group 21 is 250 μm away from the antireflective coating layer 11; the bottom of the second microlens group 22 is 250 μm away from the antireflective coating layer 11. The bottom of the first microlens group 21 and the bottom of the second microlens group 22 refer to the bottom of the microlens 200, that is, the surface at the interval between adjacent microlenses 200.

[0023] See Figure 2 The antireflective coating 11 comprises alternating stacked first refractive index layers 111 and second refractive index layers 112. In this embodiment, the first refractive index layers 111 are configured to have four layers, and the second refractive index layers 112 are configured to have three layers. The first refractive index layers 111 are in direct contact with the first substrate layer 10 and the second substrate layer 12. The refractive index of the first refractive index layer 111 is less than that of the second refractive index layer 112. In this embodiment, the material of the first refractive index layer 111 is silicon dioxide, and the material of the second refractive index layer 112 is amorphous silicon. The thickness of the first refractive index layer 111 is 30 nm, the thickness of the second refractive index layer 112 is 50 nm, the refractive index n of the first refractive index layer 111 is 1.5, and the refractive index n of the second refractive index layer 112 is 1.9. In other embodiments, the material, number of layers, and thickness of the antireflective coating 11 can be adjusted according to the actual light wavelength requirements.

[0024] Reference Figures 3 to 5 The aforementioned double-sided microlens element can be formed by (including but not limited to) the following process steps: Step 1: Using PECVD (Polyethylene Chemical Vapor Deposition) technology, a functional layer, namely an antireflection film 11, with antireflection, anti-reflection, and filtering effects is prepared on the surface of a 300-micron-thick double-sided polished high-resistivity silicon wafer, namely the first substrate layer 10. The functional layer consists of a first dielectric layer and a second dielectric layer, which are alternately prepared by PECVD. The first dielectric layer material is silicon dioxide, serving as the first refractive index film 111, with a refractive index n=1.5. The second dielectric layer material is amorphous silicon, serving as the second refractive index film 112, with a refractive index n=1.9.

[0025] Step 2: Using a hot-press silicon-oxygen silicon bonding process, another 300-micron thick double-sided polished high-resistivity silicon wafer, namely the second substrate layer 12, is bonded to the antireflection film layer 11. Finally, silicon wafers are integrated on both sides of the antireflection film layer 11 as substrates.

[0026] Step 3: Spin-coat a layer of photoresist 2 on the front side, i.e., the first substrate layer 10, and denoted as the front photoresist layer.

[0027] Step 4: After photolithography and development of the front-side photoresist, a circular pattern is formed in the front-side photoresist layer. (See attached image) Figure 5 This is a schematic diagram of the planar structure after the front photoresist layer is patterned. By heating the front photoresist layer at high temperature, the circular patterned photoresist 2 shrinks under the action of high temperature, forming a three-dimensional microlens structure on the front side, i.e., the surface of the first substrate layer 10, which serves as the first patterned photoresist layer.

[0028] Step 5: Using a dry etching process, the first base layer 10 is etched with the first patterned photoresist layer as a masking layer. Finally, the pattern is transferred and a microlens structure is obtained on the front substrate, i.e., the first base layer 10, as the first microlens group 21.

[0029] Step 6: Flip the wafer over and spin-coat a layer of photoresist 2 on the back side, i.e., the second substrate layer 12, which is denoted as the back photoresist layer.

[0030] Step 7: After photolithography and development of the back photoresist, a circular pattern is formed in the back photoresist layer. By heating the back photoresist layer at high temperature, the photoresist 2 of the circular pattern shrinks under the action of high temperature, forming a three-dimensional microlens structure on the back side, i.e., the surface of the second substrate layer 12, as the second pattern photoresist layer.

[0031] Step 8: Using a dry etching process, the second patterned photoresist layer is used as a masking layer to etch the second base layer 12. Finally, the pattern is transferred and a microlens structure is obtained on the back surface substrate, i.e., the second base layer 12, as the second microlens group 22.

[0032] The result is a double-sided microlens element, namely a double-sided low-loss high-precision integrated microlens.

[0033] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the scope of protection of the claims of this utility model.

Claims

1. A double-sided microlens element, characterized in that, include: A first base layer (10), an antireflective coating layer (11), and a second base layer (12) are sequentially arranged. A first microstructure layer is formed on the side of the first base layer (10) away from the antireflective coating layer (11), serving as a first microlens group (21). A second microstructure layer is formed on the side of the second base layer (12) away from the antireflective coating layer (11), serving as a second microlens group (22).

2. A double-sided microlens element according to claim 1, characterized in that, The antireflective coating (11) includes an alternately stacked first refractive index film (111) and second refractive index film (112). The first refractive index film (111) is in direct contact with the first substrate layer (10) and the second substrate layer (12). The refractive index of the first refractive index film (111) is less than the refractive index of the second refractive index film (112).

3. A double-sided microlens element according to claim 2, characterized in that, The first refractive index film (111) has four layers, and the second refractive index film (112) has three layers; the material of the first refractive index film (111) is silicon dioxide, the material of the second refractive index film (112) is amorphous silicon, and the materials of the first substrate layer (10) and the second substrate layer (12) are silicon.

4. A double-sided microlens element according to claim 2, characterized in that, The thickness of the first refractive index film (111) is 30 nm, and the thickness of the second refractive index film (112) is 50 nm; the refractive index n of the first refractive index film (111) is 1.5, and the refractive index n of the second refractive index film (112) is 1.

9.

5. A double-sided microlens element according to claim 1, characterized in that, Both the first microlens group (21) and the second microlens group (22) are composed of several microlenses (200) arranged in an array.

6. A double-sided microlens element according to claim 5, characterized in that, Each microlens (200) of the first microlens group (21) corresponds to a microlens (200) of the second microlens group (22), and the positions of the corresponding two microlenses (200) overlap and are aligned.

7. A double-sided microlens element according to claim 5, characterized in that, The microlens (200) is hemispherical in shape and is prepared by a hot reflux process.

8. A double-sided microlens element according to claim 5, characterized in that, The diameter of a single microlens (200) is 300 μm.

9. A double-sided microlens element according to claim 5, characterized in that, In the first microlens group (21) and the second microlens group (22), the spacing between several microlenses (200) in the same microlens group is 200 μm.

10. A double-sided microlens element according to claim 1, characterized in that, The bottom of the first microlens group (21) is 250 μm away from the antireflective coating layer (11); the bottom of the second microlens group (22) is 250 μm away from the antireflective coating layer (11).

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