Infrared polarization detector structure and preparation method

Abstract

The invention discloses an infrared polarization detector structure and a preparation method, and relates to the photoelectric detection technology, and the infrared polarization detector structure comprises a reading circuit (1) which is in inverted connection with an infrared material (2); one face of the infrared material (2) is connected with the reading circuit (1), array type polarization grating structures (4) are arranged on the other face of the infrared material (2), any polarization grating structure (4) forms a pixel, isolation groove structures (9) are arranged between the pixels on the infrared material (2), and the isolation groove structures (9) are filled with infrared isolation materials. According to the infrared polarization detector structure provided by the embodiment of the invention, the crosstalk of an infrared detector can be reduced, and the extinction ratio of the infrared polarization detector is improved.

Description

Technical Field

[0001] The present application relates to the field of photoelectric detection technology, and in particular to an infrared polarization detector structure and a preparation method thereof. Background Art

[0002] Polarized infrared detectors integrate micro-nano polarization devices with infrared detector chips, integrate polarizers with different polarization directions on the focal plane, and use them one by one with the pixels of the detector. Different pixels detect different polarization directions. The extinction ratio is an important indicator for evaluating the performance of polarized infrared detectors. The higher the extinction ratio, the higher the recognition of the target by the polarized infrared detector.

[0003] After the infrared detector is integrated with the polarization device, the extinction ratio is significantly reduced, which has always been a key indicator restricting the application of infrared detectors. Improving the extinction ratio of polarized infrared detectors is a very necessary task. Among them, signal crosstalk is the main reason for the low extinction ratio of infrared polarization detectors. Summary of the invention

[0004] The embodiment of the present application provides an infrared polarization detector structure, which is used to reduce the crosstalk of the infrared detector and improve the extinction ratio of the infrared polarization detector.

[0005] The present application embodiment provides an infrared polarization detector structure, including:

[0006] A readout circuit 1 is flip-chip connected to an infrared material 2;

[0007] The infrared material 2 has one side interconnected with the readout circuit 1 and an arrayed polarization grating structure 4 on the other side. Any polarization grating structure 4 constitutes a pixel. An isolation groove structure 9 is provided between each pixel on the infrared material 2, and the isolation groove structure 9 is filled with infrared isolation material.

[0008] Optionally, the readout circuit 1 is flip-chip connected to the n-type injection region 3 of the infrared material 2 through the indium column 5, the n-type injection region 3 is embedded in one side of the infrared material 2, and the number and position of the polarization grating structure 4 on the other side of the n-type injection region 3 and the infrared material 2 correspond one to one.

[0009] Optionally, the material filled with the inner sidewalls of the isolation groove structure 9 includes a passivation layer 6, a metal layer 7 is arranged between the indium column 5 and the n-type injection region 3 of the infrared material 2, and the passivation layer 6 covers the inner sidewalls of the isolation groove structure 9 and the area on the side of the n-type injection region 3 on the infrared material 2 except the metal layer 7.

[0010] Optionally, the passivation layer 6 is filled with infrared non-transparent material 8 .

[0011] Optionally, the infrared non-transparent material 8 covers the passivation layer 6 , or is filled into the isolation trench structure 9 .

[0012] Optionally, the infrared material 2 is made of P-type mercury cadmium telluride material.

[0013] Optionally, the polarization grating structure 4 disposed on the other surface of the infrared material 2 is arranged into a plurality of polarization super-pixel specifications according to specified array specifications.

[0014] The present application also provides a method for preparing an infrared polarization detector structure, comprising the following steps:

[0015] Prepare infrared materials;

[0016] preparing an isolation groove structure 9 on the infrared material, and covering a passivation layer 6 based on the prepared isolation groove structure 9;

[0017] Covering the infrared non-transparent material 8 and the metal layer 7 by film deposition and photolithography;

[0018] Perform flip-chip interconnection to form an infrared polarization detector structure.

[0019] The embodiments of the present application propose an infrared polarization detector structure that can reduce the crosstalk of the infrared detector and improve the extinction ratio of the infrared polarization detector.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0022] Figure 1 This is a schematic diagram of the structure of an infrared polarization detector according to an embodiment of the present application;

[0023] Figure 2 A schematic diagram of the cross-sectional structure of an infrared polarization detector structure according to an embodiment of the present application;

[0024] Figure 3 The overall structure of the infrared polarization detector structure of the embodiment of the present application is schematically shown;

[0025] Figure 4The figure is a schematic diagram of the preparation process of the infrared polarization detector structure according to the embodiment of the present application. DETAILED DESCRIPTION

[0026] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0027] The extinction ratio is defined as the ratio of the maximum response voltage of the detector when the transmission axes of the polarizer and the polarization grating on the micro-nano polarization integrated detector chip are parallel to the minimum response voltage when the transmission axes are perpendicular. Theoretically, the response value of the pixel is the largest when the transmission axes of the polarizer and the polarization grating are parallel; theoretically, when the transmission axes of the polarizer and the polarization grating are perpendicular, the response value of the pixel tends to be infinitely small. In actual operation, the signals of adjacent pixels will crosstalk to the pixel, reducing the extinction ratio of the pixel.

[0028] Taking into account the wavelength characteristics and process difficulty of the medium-wave infrared detector, the polarization grating line width generally has a good extinction ratio when it is hundreds of nanometers. However, the extinction ratio of the infrared polarization detector after the actual integration process is much smaller than the extinction ratio of the designed grating structure, mainly due to the following reasons:

[0029] The medium wave signal will diffract when passing through the grating structure, causing crosstalk between adjacent pixels and reducing the extinction ratio of the infrared polarization detector;

[0030] The electrical crosstalk between adjacent pixels affects the extinction ratio of infrared polarization detectors;

[0031] The influence of stray light in the test system, Dewar structure, detector surface and body reduces the extinction ratio of the infrared polarization detector.

[0032] The present application embodiment provides an infrared polarization detector structure, such as Figure 1 , Figure 2 As shown, including:

[0033] A readout circuit 1 is flip-chip connected to an infrared material 2;

[0034] The infrared material 2 has one side interconnected with the readout circuit 1 and an arrayed polarization grating structure 4 on the other side. Any polarization grating structure 4 constitutes a pixel. An isolation groove structure 9 is provided between each pixel on the infrared material 2, and the isolation groove structure 9 is filled with infrared isolation material.

[0035] In some embodiments, the readout circuit 1 is flip-chip connected to the n-type injection region 3 of the infrared material 2 through an indium column 5, the n-type injection region 3 is embedded in one side of the infrared material 2, and the number and position of the polarization grating structure 4 on the other side of the n-type injection region 3 and the infrared material 2 correspond one to one.

[0036] In some embodiments, the material filled with the inner sidewalls of the isolation trench structure 9 includes a passivation layer 6, a metal layer 7 is arranged between the indium column 5 and the n-type injection region 3 of the infrared material 2, and the passivation layer 6 covers the inner sidewalls of the isolation trench structure 9 and the area on the side of the n-type injection region 3 on the infrared material 2 except the metal layer 7.

[0037] The infrared polarization detector structure of the embodiment of the present application reduces the electrical crosstalk between pixels by designing the infrared detector structure. In the specific example, the present application designs an isolation groove structure 9 and fills the isolation groove structure 9 with infrared isolation material to block the signal crosstalk between adjacent pixels, thereby reducing the response value when the transmission axes of the polarizer and the polarization grating are perpendicular, and improving the extinction ratio of the infrared polarization detector.

[0038] In some embodiments, the passivation layer 6 is filled with infrared non-transparent material 8 .

[0039] In some embodiments, the infrared non-transparent material 8 covers the passivation layer 6, or is filled into the isolation groove structure 9. That is, the infrared non-transparent material 8 can be used to cover the outside of the passivation layer 6, or the infrared non-transparent material 8 can be directly filled into the isolation groove structure 9. The material of the infrared non-transparent material 8 can be the same as that of the metal layer 7, or other materials can be selected according to actual conditions.

[0040] In some embodiments, the infrared material 2 is a P-type mercury cadmium telluride material.

[0041] In some embodiments, the polarization grating structure 4 disposed on the other side of the infrared material 2 is arranged according to a specified array specification to form a plurality of polarization super-pixel specifications. For example, the polarization grating structure is arranged in a 2×2 pattern to form a polarization super-pixel specification. Figure 3 The overall structure shown.

[0042] The infrared polarization detector structure proposed in this application can reduce the signal crosstalk between adjacent pixels of the infrared integrated polarization detector, thereby improving the extinction ratio of the infrared integrated polarization detector, providing a technical breakthrough for the preparation and application of infrared integrated polarization detectors.

[0043] The present application also provides a method for preparing an infrared polarization detector structure. Figure 4 As shown, the following steps are included:

[0044] Prepare infrared materials;

[0045] preparing an isolation groove structure 9 on the infrared material, and covering a passivation layer 6 based on the prepared isolation groove structure 9;

[0046] Covering the infrared non-transparent material 8 and the metal layer 7 by film deposition and photolithography;

[0047] Perform flip-chip interconnection to form an infrared polarization detector structure.

[0048] The embodiments of the present application propose an infrared polarization detector structure that can reduce the crosstalk of the infrared detector and improve the extinction ratio of the infrared polarization detector.

[0049] It should be noted that in the various embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a 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, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0050] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0051] 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 infrared polarization detector structure, characterized in that: include: A readout circuit (1) is flip-chip connected to the infrared material (2); An infrared material (2) is interconnected with the readout circuit (1) on one side and is provided with an arrayed polarization grating structure (4) on the other side, wherein any polarization grating structure (4) constitutes a picture element, and an isolation groove structure (9) is provided between each picture element on the infrared material (2), wherein the isolation groove structure (9) is filled with infrared isolation material.

2. The infrared polarization detector structure according to claim 1, characterized in that: The readout circuit (1) is flip-chip connected to an n-type injection region (3) of an infrared material (2) via an indium column (5); the n-type injection region (3) is embedded in one side of the infrared material (2); and the number and position of the polarization grating structures (4) on the other side of the n-type injection region (3) and the infrared material (2) correspond one to one.

3. The infrared polarization detector structure according to claim 2, characterized in that: The material filled in the inner sidewall of the isolation groove structure (9) comprises a passivation layer (6); a metal layer (7) is provided between the indium column (5) and the n-type injection region (3) of the infrared material (2); the passivation layer (6) covers the inner sidewall of the isolation groove structure (9) and the region on one side of the n-type injection region (3) on the infrared material (2) except the metal layer (7).

4. The infrared polarization detector structure according to claim 3, characterized in that: The passivation layer (6) is covered with an infrared non-transparent material (8).

5. The infrared polarization detector structure according to claim 4, characterized in that: The infrared non-transparent material (8) covers the passivation layer (6), or is filled into the isolation groove structure (9).

6. The infrared polarization detector structure according to claim 1, characterized in that: The infrared material (2) is a P-type mercury cadmium telluride material.

7. The infrared polarization detector structure according to claim 1, characterized in that: The polarization grating structure (4) disposed on the other surface of the infrared material (2) is arranged to form a plurality of polarization super-pixel specifications according to a specified array specification.

8. A method for preparing an infrared polarization detector structure, characterized in that: The steps include: Prepare infrared materials; Preparing an isolation groove structure (9) on the infrared material, and covering a passivation layer (6) based on the prepared isolation groove structure (9); Covering the infrared non-transparent material (8) and the metal layer (7) by film deposition and photolithography; Perform flip-chip interconnection to form an infrared polarization detector structure.

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