Mercury cadmium telluride infrared detector with in-situ integrated diffraction lens structure and preparation method thereof
By integrating the diffraction lens structure in situ on the pixel surface of the mercury cadmium tellurium infrared detector, the problem of difficulty in converging infrared signals at the edge of the pixel is solved, efficient collection of photogenerated electrons and reduction of crosstalk between pixels is achieved, and the imaging quality of the detector is improved.
Patent Information
- Application Number
- CN202411762309.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-03
- Publication Date
- 2025-04-04
AI Technical Summary
The infrared signals received by existing mercury cadmium tellurium infrared detectors are difficult to effectively converge, resulting in low photogenerated electron collection efficiency and serious crosstalk between pixels, affecting detection capabilities and imaging quality.
The diffraction lens structure is integrated in situ on the pixel surface of the mercury cadmium tellurium infrared detector, including a plurality of periodically distributed, concentric, annular metal protrusions, with a width of sub-wavelength width, and the width between adjacent protrusions is also sub-wavelength width to achieve the convergence of infrared light.
Through the in-situ integration of the diffraction lens structure, the incident infrared light is effectively concentrated in the center of the pixel, improving the collection efficiency of photogenerated electrons, reducing crosstalk between pixels, and improving the quantum efficiency and overall imaging quality of the detector.
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Figure CN119767811A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of infrared detectors, and in particular to a mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure and a preparation method thereof. Background Art
[0002] Infrared detectors are widely used in many fields including but not limited to military reconnaissance, environmental monitoring, astronomical research, industrial detection, etc. Mercury cadmium telluride infrared detector is one of the representative products of infrared detection technology.
[0003] The HgCdTe infrared detector is made of infrared photosensitive materials (HgCdTe chip) and silicon-based readout circuits through device inversion interconnection. Its working principle is: the HgCdTe chip receives the infrared radiation of the target, causing electron transitions inside the chip to generate photogenerated electrons and photogenerated holes to form a weak current, and then the readout circuit reads this weak current and converts it into a voltage signal output.
[0004] Infrared detectors are usually composed of multiple pixel units, each of which is responsible for converting the received infrared radiation into electrical signals. However, when photogenerated electrons are generated at the edge of a pixel, the photoelectrons need to move a distance of half a pixel size before they can be output by the readout circuit. During this process, the photoelectrons are very likely to recombine with holes or be scattered by internal defects in the material, resulting in the inability to be output by the circuit, thereby reducing the detection capability of the infrared detector; in addition, these photoelectrons may also be read and output by adjacent pixels, causing crosstalk between the pixels of the infrared detector. Summary of the invention
[0005] The invention provides a mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure and a preparation method thereof, which solves the problem of how to effectively converge infrared signals irradiated on the edge of a pixel.
[0006] In order to achieve the above purpose, this application adopts the following technical solutions:
[0007] In a first aspect, a mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure is provided, comprising:
[0008] A mercury cadmium telluride chip and a readout circuit, wherein the mercury cadmium telluride chip and the readout circuit are flip-chip interconnected;
[0009] A diffractive lens structure is prepared on the pixel surface of the mercury cadmium telluride chip, and each pixel corresponds to one diffractive lens structure, which is used to converge the light within the pixel area to the center of the pixel;
[0010] The diffractive lens structure comprises a plurality of periodically distributed, concentric, annular metal protrusions, the width of the metal protrusions is a sub-wavelength width, and the width between adjacent metal protrusions is a sub-wavelength width.
[0011] In a first possible implementation manner of the first aspect, the diffractive lens structure is configured as concentric square rings.
[0012] In a second possible implementation manner of the first aspect, the diffractive lens structure is configured as concentric rings.
[0013] Based on the first or second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the material of the diffractive lens structure is specifically configured as copper.
[0014] Based on the first or second possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the material of the diffractive lens structure is specifically configured as aluminum.
[0015] In a second aspect, a method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure is provided.
[0016] Growing a metal film layer for preparing a diffractive lens structure on a pixel surface of an infrared detector;
[0017] According to the response band of the infrared detector, the shape and sub-wavelength width of the diffractive lens structure are determined, and the diffractive lens pattern is designed; wherein the diffractive lens structure includes a plurality of periodically distributed, concentric, annular metal protrusions, the width of the metal protrusions is the sub-wavelength width, and the width between adjacent metal protrusions is the sub-wavelength width;
[0018] Using a photolithography device to transfer the diffraction lens pattern to the detector surface through the photoresist layer in pixel alignment;
[0019] Using plasma etching equipment to remove the metal film layer not covered by the photoresist;
[0020] The remaining photoresist is removed to obtain an infrared detector with a pixel-aligned diffraction lens structure.
[0021] In a first possible implementation manner of the second aspect, the material of the metal film layer is specifically configured as copper.
[0022] In a second possible implementation manner of the second aspect, the material of the metal film layer is specifically configured as aluminum.
[0023] In a third possible implementation manner of the second aspect, the shape of the diffractive lens structure is configured as concentric square rings.
[0024] In a fourth possible implementation manner of the second aspect, the shape of the diffractive lens structure is configured as concentric rings.
[0025] Beneficial effects:
[0026] This application uses a diffractive lens structure that is in-situ integrated on the pixel surface and aligned at the pixel level to effectively focus the incident infrared light at the center of the pixel, thereby improving the collection efficiency of photogenerated electrons and reducing crosstalk between pixels. This solution not only improves the quantum efficiency of the detector, but also improves the overall imaging quality, providing a new solution for the development of infrared imaging technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 A schematic diagram of the shape of a diffractive lens structure provided in an embodiment of the present application;
[0028] Figure 2 A schematic diagram of the shape of another diffractive lens structure provided in an embodiment of the present application;
[0029] Figure 3 A schematic diagram of a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure provided in an embodiment of the present application;
[0030] Figure 4 A simulation diagram of the convergence of infrared light on a pixel area provided in an embodiment of the present application;
[0031] Figure 5 A schematic flow chart of a method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure provided in an embodiment of the present application;
[0032] Figure 6 A schematic flow chart of another method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure provided in an embodiment of the present application. DETAILED DESCRIPTION
[0033] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the technical solutions in the embodiments of the present application are clearly described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.
[0034] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.
[0035] The description of the method flow in the specification of the present application and the steps of the flowchart in the drawings of the present specification do not have to be strictly executed according to the step numbers, and the method steps can be executed in a different order. Moreover, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.
[0036] The mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure and a preparation method thereof provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings and preferred embodiments.
[0037] First, the application scenario of the mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure in the embodiment of the present application is described in detail.
[0038] Infrared focal plane detection technology has significant advantages such as wide spectral response band, more ground target information, and day and night operation. It is widely used in agriculture and animal husbandry, forest resource survey, development and management, weather forecast, geothermal distribution, earthquake, volcanic activity, space astronomical detection and other fields. The signal detection capability of mercury cadmium telluride infrared detector is one of the important technical indicators of infrared detection. When the infrared signal is irradiated on the edge of the infrared detector pixel, the generated photoelectrons need to move half a pixel size before they can be output. These photoelectrons may also be read and output by adjacent pixels, causing crosstalk between infrared detector pixels. In the process of photoelectrons at the edge of the pixel being read out, photoelectrons are very likely to recombine with holes, be scattered by internal defects of the material, or be absorbed by its adjacent pixels, and cannot be output, thereby affecting the quantum efficiency of the infrared detector and increasing the crosstalk between pixels. To this end, it is necessary to converge the infrared signal within each pixel area at the center of the pixel for photoelectric conversion as much as possible to improve the quantum efficiency of the detector and reduce the crosstalk between adjacent pixels.
[0039] This application proposes a HgCdTe infrared detector with an in-situ integrated diffraction lens structure, which aims to design and prepare an HgCdTe infrared detector with an in-situ integrated diffraction lens by using the principle of optical diffraction, so that the light irradiated on the edge of the pixel converges to the center of the pixel. By achieving effective convergence of the incident infrared signal, not only can the quantum efficiency of the detector be significantly improved, but also the crosstalk between pixels can be effectively reduced, thereby improving the overall imaging quality.
[0040] See also Figure 1-3 , the embodiment of the present application provides a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure, such as Figure 1-3 As shown, the mercury cadmium telluride infrared detector of the embodiment of the present application includes:
[0041] A mercury cadmium telluride chip and a readout circuit, wherein the mercury cadmium telluride chip and the readout circuit are flip-chip interconnected;
[0042] The pixel surface of the HgCdTe chip is prepared with a diffractive lens structure, and each pixel corresponds to a diffractive lens structure, which is used to converge the light within the pixel area to the center of the pixel;
[0043] The diffractive lens structure includes a plurality of periodically distributed, concentric, annular metal protrusions. The width of the metal protrusions is sub-wavelength, and the width between adjacent metal protrusions is sub-wavelength, that is, the width of the metal protrusions and the width between adjacent metal protrusions are much smaller than the wavelength of the incident light.
[0044] The principles of this application are:
[0045] When the size of an obstacle is much smaller than the wavelength of the incident light, the light wave will bypass these obstacles and diffraction will occur (diffraction effect). The diffraction effect causes the light wave to interfere and produce diffraction patterns around the obstacle without being blocked. The propagation distance of a light wave in a complete cycle can be represented by the symbol λ, and the subwavelength width refers to a structure with a characteristic size much smaller than λ. For example, if the wavelength of the incident light is 1000 nanometers, then a structure with a characteristic size of 100 nanometers or less can be considered a subwavelength structure. The diffraction lens structure is achieved by manufacturing a specific microstructure on the surface of the pixel. When the incident light passes through the diffraction lens structure, diffraction will occur, changing the phase of the incident light, so that light waves at different positions interfere at the center of the pixel to form a focal point instead of dispersing at the edge of the pixel.
[0046] By adjusting the parameters of the diffractive lens structure (such as period, width, shape, etc.), the diffraction angle and focal position of the light can be controlled so that the incident light converges at the center of the pixel (see Figure 4 , the z-axis value represents the multiple of the incident light intensity).
[0047] In some possible implementations, see Figure 1 , the diffractive lens structure is configured as concentric square rings.
[0048] In some possible implementations, see Figure 1 , the diffractive lens structure is configured as concentric rings.
[0049] Furthermore, the material of the diffractive lens structure can be specifically configured as copper (Au) or aluminum (Al).
[0050] Based on the above technical solution, this application integrates a diffraction lens structure in situ on the pixel surface, and aligns the diffraction lens structure at the pixel level, which can effectively focus the incident infrared light at the center of the pixel, thereby improving the collection efficiency of photogenerated electrons and reducing crosstalk between pixels. The in-situ integrated diffraction lens can accurately control the propagation path of light at the pixel scale, ensuring that more photogenerated electrons are effectively read out at the center of the pixel, avoiding losses caused by long-distance transmission. This solution not only improves the quantum efficiency of the detector, but also improves the overall imaging quality, providing a new solution for the development of infrared imaging technology.
[0051] See also Figure 5-6 The present application embodiment provides a method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure, such as Figure 5-6 As shown, the preparation method of the embodiment of the present application includes the following steps:
[0052] Step S1, growing a metal film layer for preparing a diffractive lens structure on a pixel surface of an infrared detector.
[0053] The detector is a mercury cadmium telluride infrared detector, including: a mercury cadmium telluride chip and a readout circuit, the mercury cadmium telluride chip and the readout circuit are flip-chip interconnected. The pixel surface is the side of the mercury cadmium telluride chip away from the readout circuit.
[0054] In specific implementation, this step can be performed by growing a metal film layer on the surface of the infrared detector through a metal coating device.
[0055] Furthermore, the material of the metal film layer can be specifically configured as copper (Au) or aluminum (Al).
[0056] Step S2, determining the shape and sub-wavelength width of the diffraction lens structure according to the response band of the infrared detector, and designing the diffraction lens pattern.
[0057] The diffractive lens structure includes a plurality of periodically distributed, concentric, annular metal protrusions. The sub-wavelength width of the diffractive lens structure, that is, the width of the metal protrusions and the width between adjacent metal protrusions, is much smaller than the wavelength of the incident light.
[0058] In some possible implementations, see Figure 1 , the shape of the diffractive lens structure is configured as concentric square rings.
[0059] In some possible implementations, see Figure 1 , the shape of the diffractive lens structure is configured as concentric rings.
[0060] Step S3, using a photolithography device to transfer the diffraction lens pattern to the detector surface through the photoresist layer in a pixel-aligned manner.
[0061] Step S4, using plasma etching equipment to remove the metal film layer not covered by the photoresist.
[0062] Step S5, removing the remaining photoresist to obtain an infrared detector with a pixel-aligned diffraction lens structure.
[0063] The method for preparing the mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure can achieve the same technical effect as the embodiment of the mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure mentioned above, and will not be described again here to avoid repetition.
[0064] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.
[0065] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.
Claims
1. An HgCdTe infrared detector with an in-situ integrated diffractive lens structure, characterized in that: include: A mercury cadmium telluride chip and a readout circuit, wherein the mercury cadmium telluride chip and the readout circuit are flip-chip interconnected; A diffractive lens structure is prepared on the pixel surface of the mercury cadmium telluride chip, and each pixel corresponds to one diffractive lens structure, which is used to converge the light within the pixel area to the center of the pixel; The diffractive lens structure comprises a plurality of periodically distributed, concentric, annular metal protrusions, the width of the metal protrusions is a sub-wavelength width, and the width between adjacent metal protrusions is a sub-wavelength width.
2. The HgCdTe infrared detector with an in-situ integrated diffractive lens structure according to claim 1, characterized in that: The diffractive lens structure is configured as concentric square rings.
3. The HgCdTe infrared detector with an in-situ integrated diffractive lens structure according to claim 1, characterized in that: The diffractive lens structure is configured as concentric rings.
4. The mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure according to claim 2 or 3, characterized in that: The material of the diffractive lens structure is specifically configured to be copper.
5. The mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure according to claim 2 or 3, characterized in that: The material of the diffractive lens structure is specifically configured as aluminum.
6. A method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffraction lens structure, characterized in that: include: Growing a metal film layer for preparing a diffractive lens structure on a pixel surface of an infrared detector; According to the response band of the infrared detector, the shape and sub-wavelength width of the diffractive lens structure are determined, and the diffractive lens pattern is designed; wherein the diffractive lens structure includes a plurality of periodically distributed, concentric, annular metal protrusions, the width of the metal protrusions is the sub-wavelength width, and the width between adjacent metal protrusions is the sub-wavelength width; Using a photolithography device to transfer the diffraction lens pattern to the detector surface through the photoresist layer in pixel alignment; Using plasma etching equipment to remove the metal film layer not covered by the photoresist; The remaining photoresist is removed to obtain an infrared detector with a pixel-aligned diffractive lens structure.
7. The method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure according to claim 6, characterized in that: The material of the metal film layer is specifically configured to be copper.
8. The method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure according to claim 6, characterized in that: The material of the metal film layer is specifically configured to be aluminum.
9. The method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure according to claim 6, characterized in that: The diffractive lens structure is configured in the shape of concentric square rings.
10. The method for preparing a mercury cadmium telluride infrared detector with an in-situ integrated diffractive lens structure according to claim 6, characterized in that: The diffractive lens structure is configured in the shape of concentric rings.