A bottom filling method of a table structure infrared detector and an infrared detector

Abstract

The present application discloses a method for filling the bottom of a mesa structure infrared detector and an infrared detector, which relates to infrared detectors and semiconductor technologies, including: covering the top of the mesa structure of the infrared detector chip with a first thickness of photoresist by a photolithography process, wherein there are grooves between the mesa structures; growing a second thickness of a dielectric layer on the surface of the infrared chip by a thermal evaporation coating device; removing the photoresist on the top of the mesa structure of the infrared detector chip by a stripping process to retain the dielectric layer in the grooves between the mesa structures; flip-chip interconnecting the infrared detector chip that has undergone the stripping process with the readout circuit, and filling the gap with glue to complete. The present application solves the problem of infrared detector performance degradation caused by the different thermal expansion coefficients of the infrared detector bottom filling glue and the infrared chip, thereby improving the long-term reliability of the infrared detector.

Description

Technical Field

[0001] The present application relates to the fields of infrared detectors and semiconductor technology, and in particular to a bottom filling method for a mesa-structured infrared detector and an infrared detector. Background Art

[0002] 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, animal husbandry, forest resource survey, development and management, weather forecast, geothermal distribution, earthquake, volcanic activity, space astronomical detection, etc. Since infrared detectors need to work at a low temperature of 77K, the detector will return to room temperature when it is turned off, which causes it to be subjected to a temperature shock of more than 200 degrees during the power on and off process, causing the infrared photosensitive chip and readout circuit of the detector to crack, resulting in damage to the detector.

[0003] The on / off (long-term) reliability of infrared detectors directly affects the application range of infrared detectors. Therefore, the bottom filling method of infrared detectors is the core technology of infrared detector manufacturing.

[0004] The infrared detector bottom filling process is one of the core technologies in the infrared detector manufacturing. Its principle is: by setting a glue strip on the edge of the infrared chip, such as Figure 1 As shown in FIG. 1 , the glue penetrates into the gap between the infrared chip and the readout circuit due to capillary action, completing the bottom filling of the infrared detector. Figure 2 As shown. However, due to the presence of a mesa structure on the surface of the infrared chip of the mesa structure infrared detector, the array of the mesa structure forms a mesh groove, and the glue will flow into the groove during the bottom filling process. Since there is glue filling inside the groove, and the thermal expansion coefficient of the glue and the infrared chip is quite different, the glue will exert pressure on the side wall of the infrared chip mesa during the temperature change of the detector, causing damage to the infrared chip structure and deterioration of the detector performance. Summary of the invention

[0005] The embodiment of the present application provides a table-structured infrared detector bottom filling method and an infrared detector, which are used to solve the problem of infrared detector performance degradation caused by the different thermal expansion coefficients of the infrared detector bottom filling glue and the infrared chip, thereby improving the long-term reliability of the infrared detector.

[0006] The present application embodiment provides a method for filling the bottom of a mesa structure infrared detector, comprising:

[0007] Covering the top of the mesa structure of the infrared detector chip with a photoresist of a first thickness by a photolithography process, wherein grooves are present between the mesa structures;

[0008] Using thermal evaporation coating equipment to grow a dielectric layer of a second thickness on the surface of the infrared chip, wherein the grown dielectric layer covers the photoresist on the mesa structure on the surface of the infrared chip and the grooves between the mesa structures;

[0009] The photoresist on the mesa structure of the infrared detector chip is removed by a stripping process to retain the dielectric layer in the grooves between the mesa structures;

[0010] The infrared detector chip that has undergone the lift-off process is flip-chip interconnected with the readout circuit.

[0011] Optionally, the first thickness of the photoresist covering the top of the infrared detector chip mesa structure is 1 / 4-3 / 4 of the groove depth.

[0012] Optionally, the dielectric layer grown on the surface of the infrared chip includes a dielectric layer of ZnS, CdTe, SiO2, or SiNx.

[0013] Optionally, the second thickness of the dielectric layer grown on the surface of the infrared chip is 1 / 4-3 / 4 of the groove depth.

[0014] Optionally, after flip-chip interconnecting the infrared detector chip that has undergone the peeling process with the readout circuit, the method further includes: filling a gap between the infrared detector chip and the readout circuit with glue.

[0015] An embodiment of the present application also proposes an infrared detector, including an infrared detector chip and a readout circuit, wherein the infrared detector chip adopts the aforementioned table-structure infrared detector bottom filling method to fill a flush dielectric layer between the table-structure of the infrared detector chip, the infrared detector chip and the readout circuit are flip-chip interconnected, and the gap between the infrared detector chip and the readout circuit is filled with glue.

[0016] The method of the embodiment of the present application solves the problem of infrared detector performance degradation caused by the different thermal expansion coefficients between the infrared detector bottom filling glue and the infrared chip, thereby improving the long-term reliability of the infrared detector.

[0017] 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

[0018] 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:

[0019] Figure 1 It is a schematic diagram of applying glue filling to the infrared detector of the prior art;

[0020] Figure 2 It is a schematic diagram of the bottom filling of the infrared detector with a mesa structure of the infrared detector in the prior art;

[0021] Figure 3 The process diagram of the bottom filling method of the mesa structure infrared detector of the embodiment of the present application is shown;

[0022] Figure 4 This is a schematic diagram of the surface of the infrared chip mesa structure of an embodiment of the present application. DETAILED DESCRIPTION

[0023] 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.

[0024] The present application embodiment provides a method for filling the bottom of a mesa structure infrared detector, such as Figure 3 As shown, the following steps are included:

[0025] In step S101, a photoresist with a first thickness is covered on the top of the infrared detector chip mesa structure by a photolithography process, wherein Figure 4 As shown, there are groove structures between the mesa structures.

[0026] In step S102, a dielectric layer of a second thickness is grown on the surface of the infrared chip by using a thermal evaporation coating device, wherein the grown dielectric layer covers the photoresist on the mesa structure on the surface of the infrared chip and the grooves between the mesa structures;

[0027] In step S103, the photoresist on the mesa structure of the infrared detector chip is removed by a stripping process to retain the dielectric layer in the grooves between the mesa structures;

[0028] In step S104, the infrared detector chip that has undergone the peeling process is flip-chip interconnected with the readout circuit.

[0029] In some embodiments, the method further includes, after the infrared detector chip that has undergone the peeling process is flip-chip interconnected with the readout circuit in step S105 , filling a gap between the infrared detector chip and the readout circuit with glue.

[0030] In some embodiments, the first thickness of the photoresist covering the top of the infrared detector chip mesa structure is 1 / 4-3 / 4 of the groove depth. For example, in some specific examples, the thickness of the photoresist covering the top of the infrared detector chip mesa structure is half of the groove depth.

[0031] In some embodiments, the dielectric layer grown on the surface of the infrared chip includes a dielectric layer of ZnS, CdTe, SiO2, or SiNx.

[0032] In some embodiments, the second thickness of the dielectric layer grown on the surface of the infrared chip is 1 / 4-3 / 4 of the groove depth. For example, in some specific examples, the thickness of the dielectric layer grown on the surface of the infrared chip is also half of the groove depth.

[0033] After flip-chip interconnection, glue is filled in the gap between the infrared chip and the readout circuit.

[0034] The method of the embodiment of the present application solves the problem that due to the different thermal expansion coefficients of the bottom filling glue of the infrared detector and the infrared chip, the glue in the groove between the countertops squeezes the side walls of the countertops during the temperature change process, causing the infrared chip countertop structure to be damaged and the performance of the infrared detector to deteriorate, thereby improving the long-term reliability of the infrared detector.

[0035] An embodiment of the present application also proposes an infrared detector, including an infrared detector chip and a readout circuit, wherein the infrared detector chip adopts the aforementioned table-structure infrared detector bottom filling method to fill a flush dielectric layer between the table-structure of the infrared detector chip, the infrared detector chip and the readout circuit are flip-chip interconnected, and the gap between the infrared detector chip and the readout circuit is filled with glue.

[0036] 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.

[0037] 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.

[0038] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0039] 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. A method for filling the bottom of a mesa structure infrared detector, characterized in that: include: Covering the top of the mesa structure of the infrared detector chip with a photoresist of a first thickness by a photolithography process, wherein grooves are present between the mesa structures; Using thermal evaporation coating equipment to grow a dielectric layer of a second thickness on the surface of the infrared chip, wherein the grown dielectric layer covers the photoresist on the mesa structure on the surface of the infrared chip and the grooves between the mesa structures; The photoresist on the mesa structure of the infrared detector chip is removed by a stripping process to retain the dielectric layer in the grooves between the mesa structures; The infrared detector chip that has undergone the lift-off process is flip-chip interconnected with the readout circuit.

2. The bottom filling method of the mesa structure infrared detector according to claim 1, characterized in that: The first thickness of the photoresist covering the top of the infrared detector chip mesa structure is 1 / 4-3 / 4 of the groove depth.

3. The bottom filling method of the mesa structure infrared detector according to claim 1, characterized in that: The dielectric layers grown on the surface of the infrared chip include dielectric layers of ZnS, CdTe, SiO2, and SiNx.

4. The method for filling the bottom of a mesa structure infrared detector according to claim 3, characterized in that: The second thickness of the dielectric layer grown on the surface of the infrared chip is 1 / 4-3 / 4 of the groove depth.

5. The bottom filling method of the mesa structure infrared detector according to claim 1, characterized in that: After the infrared detector chip that has undergone the peeling process is flip-chip interconnected with the readout circuit, the method further includes: filling glue in the gap between the infrared detector chip and the readout circuit.

6. An infrared detector, characterized in that: It comprises an infrared detector chip and a readout circuit, wherein the infrared detector chip adopts the table structure infrared detector bottom filling method as described in claims 1-5 to fill a flush dielectric layer between the table structures of the infrared detector chip, the infrared detector chip and the readout circuit are flip-chip interconnected, and the gap between the infrared detector chip and the readout circuit is filled with glue.

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