Manufacturing method of InSb focal plane detector and InSb focal plane detector

Abstract

The application relates to a manufacturing method of an InSb focal plane detector and the InSb focal plane detector, and the method comprises the following steps: thinning the back surface of an InSb detector chip to a preset lens design thickness, and performing surface treatment on the back surface of the InSb detector chip; etching the back surface of the InSb detector chip to form a concave lens and a convex lens; and setting a reflective film on the side of the concave lens and the convex lens away from the InSb detector chip to form a microlens array, so that the manufacturing efficiency is high, the coupling stress with the detector material is small, the coupling precision is high, and the concave lens and the convex lens are simultaneously arranged, so that the overall filling rate of the microlens array is relatively high.

Description

Technical Field

[0001] This invention relates to the field of microlens array fabrication, and more particularly to a method for fabricating an InSb focal plane detector and an InSb focal plane detector. Background Technology

[0002] InSb focal plane array infrared detectors are mid-wave infrared detectors that detect infrared light through the photovoltaic effect of a PN junction. They typically come in two types: mesa-type and planar-type. These are achieved by fabricating independent mesa structures or arrayed injection regions to create an arrayed PN junction, which is then integrated with readout circuitry to achieve multi-pixel imaging. Isolation structures between the pixel arrays are used for optical and electrical isolation between different photosensitive elements, but these limit the area and fill rate of the PN junction region, thus limiting its quantum efficiency and introducing crosstalk issues. Coupled with a microlens array on the surface of the InSb infrared detector, light from between pixels can be focused into the photosensitive region of each pixel, reducing signal loss, crosstalk, and improving energy and position resolution.

[0003] Refractive lenses, as optical devices, focus and diverge light through refraction, finding wide applications in sensing, illumination, and imaging. With advancements in manufacturing processes, it has become possible to fabricate high-precision, high-quality microlens arrays, which are widely used in beam shaping, collimation, focusing, imaging, and sensing. Existing fabrication methods mainly include: mechanical and micro / nano fabrication processes, which offer high precision but are inefficient and costly; methods such as photolithography with thermal reflow and microdroplet inkjet printing, which limit the fill factor and radius of curvature of microlenses; and methods like transfer printing, which suffer from issues related to uniformity, lens curvature, and integration accuracy. Summary of the Invention

[0004] To solve the above-mentioned technical problems, or at least partially solve them, the present invention provides a method for manufacturing an InSb focal plane detector and an InSb focal plane detector.

[0005] In a first aspect, the present invention provides a method for fabricating an InSb focal plane detector, the method comprising: thinning the back side of an InSb detector chip to a preset lens design thickness; performing surface treatment on the back side of the InSb detector chip; etching the back side of the InSb detector chip to form a concave lens and a convex lens; and setting a reflective film on the side of the concave lens and the convex lens away from the InSb detector chip to form a microlens array.

[0006] Optionally, the method further includes connecting the InSb detector chip readout circuit.

[0007] Optionally, connecting the InSb detector chip readout circuit includes: connecting the InSb detector chip readout circuit through an interconnect structure.

[0008] Optionally, the back side of the InSb detector chip is thinned to a preset lens design thickness, and the back side of the InSb detector chip is surface treated, including: after thinning the back side of the InSb detector chip to the preset lens design thickness, cleaning the back side of the InSb detector chip; drying the back side of the InSb detector chip with a nitrogen gun, and then surface treating the back side of the InSb detector chip with photoresist and oxygen plasma.

[0009] Optionally, etching the back side of the InSb detector chip to form concave and convex lenses includes: photolithographically etching a square wet etching mask with photoresist, and performing wet etching to etch the back side of the InSb detector chip to form concave and convex lenses.

[0010] Secondly, the present invention provides an InSb focal plane detector, the InSb focal plane detector comprising: a microlens array, an InSb detector chip, a readout circuit, and an interconnection structure, wherein the microlens array is fabricated using the method described in any of the preceding claims; the InSb detector chip is connected to the readout circuit through the interconnection structure, and the microlens array is disposed on the side of the InSb detector chip away from the readout circuit.

[0011] Optionally, the microlens array consists of an antireflective film, a convex lens, and a concave lens.

[0012] Optionally, the microlens array and the InSb detector chip are integrally formed.

[0013] The technical solutions provided in the embodiments of the present invention have the following advantages compared with the prior art:

[0014] The method for fabricating the InSb focal plane detector provided in this embodiment of the invention includes: thinning the back side of the InSb detector chip to a preset lens design thickness; performing surface treatment on the back side of the InSb detector chip; etching the back side of the InSb detector chip to form a concave lens and a convex lens; and setting a reflective film on the side of the concave lens and the convex lens away from the InSb detector chip to form a microlens array. This method has high fabrication efficiency, low coupling stress with the detector material, high coupling accuracy, and the simultaneous setting of concave and convex lenses results in a high overall fill rate of the microlens array. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A basic cross-sectional schematic diagram of an InSb focal plane detector provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the basic structure of an InSb focal plane detector provided in an embodiment of the present invention;

[0019] Figure 3 This is a basic schematic diagram of a cross-section of a microlens array provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention;

[0021] Explanation of reference numerals in the attached figures:

[0022] 1-Incident light, 2-Antireflective coating, 3-Convex lens, 4-Concave lens, 5-InSb detector chip, 6-InSb detector chip photosensitive area, 7-Interconnection structure, 8-Readout circuit. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Figure 1 The present invention provides a method for fabricating an InSb focal plane detector, the method comprising: thinning the back side of an InSb detector chip 5 to a preset lens design thickness; performing surface treatment on the back side of the InSb detector chip 5; etching the back side of the InSb detector chip 5 to form a concave lens 4 and a convex lens 3; and setting a reflective film on the side of the concave lens 4 and the convex lens 3 away from the InSb detector chip 5 to form a microlens array.

[0025] Optionally, the method further includes connecting the InSb detector chip 5 to the readout circuit 8.

[0026] Optionally, connecting the InSb detector chip 5 readout circuit 8 includes connecting the InSb detector chip 5 readout circuit 8 through interconnection structure 7.

[0027] Optionally, the back side of the InSb detector chip 5 is thinned to a preset lens design thickness, and the back side of the InSb detector chip 5 is surface treated, including: after thinning the back side of the InSb detector chip 5 to the preset lens design thickness, cleaning the back side of the InSb detector chip 5; drying the back side of the InSb detector chip 5 with a nitrogen gun, and then surface treating the back side of the InSb detector chip 5 with photoresist and oxygen plasma.

[0028] Optionally, etching the back side of the InSb detector chip 5 to form a concave lens 4 and a convex lens 3 includes: photolithographically etching a square wet etching mask with photoresist, and performing wet etching to etch the back side of the InSb detector chip 5 to form the concave lens 4 and the convex lens 3.

[0029] Specifically, for example, the InSb detector chip 5 readout circuit 8 is connected via interconnect structure 7. Then, the surface of the back side of the interconnected InSb detector chip 5 is cleaned by cleaning twice with acetone and once with anhydrous ethanol, followed by drying with a nitrogen gun and surface treatment with photoresist and oxygen plasma. Next, a square wet etching mask is photolithographically patterned with photoresist, and wet etching is performed to etch a refractive microlens structure onto the back side of the InSb detector chip 5. The surface is then cleaned with acetone and anhydrous ethanol, dried with a nitrogen gun, and finally, an antireflective film 2 is grown.

[0030] Based on the same concept, this invention provides an InSb focal plane detector, such as... Figure 1 As shown, the InSb focal plane detector includes: a microlens array, an InSb detector chip 5, a readout circuit 8, and an interconnection structure 7. The microlens array is fabricated using the method described in any of the above-mentioned methods. The InSb detector chip 5 is connected to the readout circuit 8 through the interconnection structure 7, and the microlens array is disposed on the side of the InSb detector chip 5 away from the readout circuit 8.

[0031] Optionally, the microlens array consists of an antireflective film 2, a convex lens 3, and a concave lens 4.

[0032] Optionally, the microlens array and the InSb detector chip 5 are integrally formed.

[0033] Among them, such as Figure 1 As shown, the front side of the InSb detector chip 5, that is, the photosensitive area 6 of the InSb detector chip, is connected to the interconnect structure 7, thereby enabling the InSb detector chip 5 to be connected to the readout circuit 8 through the interconnect structure 7.

[0034] like Figure 1 As shown, incident light 1 passes through antireflective coating 2 and then enters concave lens 4 or convex lens 3.

[0035] Among them, such as Figure 2 As shown, Figure 2 This is a schematic diagram of an InSb focal plane array detector, including a refractive microlens array on the surface, an InSb detector chip 5 below the microlens array, a readout circuit 8 placed below the chip, and a flip-chip interconnect structure 7 between the chip and the circuit. Microscopic images of the refractive microlens array show convex lenses 3 and recessed structures of convex lenses 3 in the gaps, and the lateral and longitudinal morphologies of the microlens array produced by etching are uniform. Figure 3 As shown, from Figure 3 As can be seen in the height cross-sectional view, the microlens array includes a convex lens structure with a central protrusion and a concave lens structure with gaps. The transverse array structure has uniform size and good surface continuity. The microlens array has low roughness, and the fabricated convex lens has a high radius of curvature, resulting in a short back focal length and good converging effect.

[0036] The refractive microlens fabrication method provided by this invention can produce microlens arrays with large array area, high lens fill rate, good consistency, and large radius of curvature. The lenses are fabricated directly on the back of the InSb focal plane detector hybrid chip, generated by photolithography etching of InSb itself. The process is simple, suitable for mass production, and does not require secondary coupling, resulting in high integration alignment accuracy and eliminating issues related to material thermal expansion coefficient matching and temperature resistance. By designing the thickness of the InSb focal plane detector and the curvature and size of the microlens array, various mesa sizes of InSb focal plane detectors can be applied, focusing light onto the mesa region, reducing crosstalk, and improving quantum efficiency.

[0037] like Figure 4 As shown, this embodiment of the invention provides an electronic device, including a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114.

[0038] Memory 113 is used to store computer programs;

[0039] In one embodiment of the present invention, when the processor 111 executes the program stored in the memory 113, it implements the steps of the method for manufacturing an InSb focal plane detector provided in any of the foregoing method embodiments.

[0040] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method for fabricating an InSb focal plane detector as provided in any of the foregoing method embodiments.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for fabricating an InSb focal plane detector, characterized in that, The method includes: The back side of the InSb detector chip is thinned to the preset lens design thickness, and the back side of the InSb detector chip is surface treated. A concave lens and a convex lens are formed by etching the back side of the InSb detector chip; An antireflective coating is disposed on the side of the concave lens and the convex lens away from the InSb detector chip to form a microlens array; The method further includes: connecting the photosensitive region of the InSb detector chip to an interconnect structure, thereby connecting the InSb detector chip and the readout circuit through the interconnect structure, so that the incident light passes through the antireflection film and then enters the concave lens or convex lens.

2. The method as described in claim 1, characterized in that, The back side of the InSb detector chip is thinned to a predetermined lens design thickness, and surface treatment is performed on the back side of the InSb detector chip, including: After thinning the back side of the InSb detector chip to the preset lens design thickness, the back side of the InSb detector chip is cleaned. The back side of the InSb detector chip was dried using a nitrogen gun, and then surface-treated with photoresist and oxygen plasma.

3. The method as described in claim 1, characterized in that, Etching the back side of the InSb detector chip to form concave and convex lenses includes: A square wet etching mask is photolithographically patterned using photoresist, and wet etching is performed to etch concave and convex lenses onto the back side of the InSb detector chip.

4. An InSb focal plane detector, characterized in that, The InSb focal plane detector includes: a microlens array, an InSb detector chip, a readout circuit, and an interconnection structure. The microlens array is fabricated using the method described in any one of claims 1-3. The InSb detector chip is connected to the readout circuit through the interconnect structure, and the microlens array is disposed on the side of the InSb detector chip away from the readout circuit.

5. The InSb focal plane detector according to claim 4, characterized in that, The microlens array consists of an antireflective film, a convex lens, and a concave lens.

6. The InSb focal plane detector according to claim 4, characterized in that, The microlens array and the InSb detector chip are integrally formed.

Images