Non-refrigeration infrared detector pixel-level packaging structure and preparation method

Abstract

The invention belongs to the technical field of semiconductors, and discloses an uncooled infrared detector pixel-level packaging structure and a preparation method thereof, and the method comprises the steps: manufacturing MEMS micro-bridge structures on a readout circuit substrate based on a sacrificial layer, and enabling the MEMS micro-bridge structures to be covered with pixel packaging structure cavities; a deposition hole is formed in the pixel packaging structure cavity, and the sacrificial layer below the deposition hole is etched; depositing a getter into the cavity of the pixel packaging structure through the deposition hole; the getter film layer above the pixel packaging structure cavity is removed, and release of the sacrificial layer is completed through the deposition hole; and finally, plating a hole sealing film layer outside the cavity of the pixel packaging structure to seal the deposition hole so as to complete sealing of the cavity of the pixel packaging structure. According to the invention, the preparation of the getter is designed at the last stage of the whole set of MEMS process, the influence of the previous processes on the getter is avoided, the getter is activated in a high-temperature thermal activation mode, and the vacuum degree of the detector cavity is ensured.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology and relates to a pixel-level packaging structure of an uncooled infrared detector and a preparation method thereof. Background Art

[0002] Uncooled infrared detection is a detector that absorbs external infrared energy and converts it into electrical signals for imaging in an ultra-high vacuum environment. Therefore, a getter must be used and activated during the packaging process of the uncooled infrared detector to remove residual gas to maintain a higher vacuum degree. And if the vacuum degree decreases during later use, the getter can be activated again to maintain a high vacuum environment again.

[0003] At present, the packaging process of uncooled infrared detectors in the industry mainly includes four forms: metal packaging, ceramic packaging, wafer-level packaging and pixel-level packaging. Among them, metal packaging and ceramic packaging use columnar getters, which are welded to the tube shell leads by welding, and electrically activated or thermally activated getters are used to maintain high vacuum before packaging. Wafer-level packaging uses thin film getters, which are integrated into the cap wafer, and finally the high temperature of bonding is used to activate the getters during bonding. Pixel-level packaging is to integrate the cap wafer with the MEMS wafer on the basis of wafer-level packaging, and use a material to directly encapsulate the entire surface of the MEMS microstructure. Based on this packaging form, the getter needs to be integrated into the entire microcavity structure, which belongs to the deposition of the getter in the MEMS front-end process. However, the multiple high-temperature baking and organic solution cleaning processes involved in the conventional semiconductor process will affect the performance of the getter, resulting in the loss of the suction ability, and the vacuum degree in the cavity cannot be guaranteed, resulting in a poor vacuum life of the detector. Summary of the invention

[0004] In view of the above problems, the present invention proposes a non-cooled infrared detector pixel-level packaging structure and a preparation method, aiming to improve the performance of the pixel-level packaging structure.

[0005] In the first aspect, the present invention provides a non-cooled infrared detector pixel-level packaging structure, including: a readout circuit substrate 1, a MEMS micro-bridge structure 2 is provided on the readout circuit substrate 1, each of the MEMS micro-bridge structures 2 is covered with a pixel packaging structure cavity 3, a deposition hole 5 is opened on the pixel packaging structure cavity 3, a getter 4 is provided under the deposition hole 5, and a sealing film layer 6 is provided on the outside of the pixel packaging structure cavity 3, and the sealing film layer 6 blocks the deposition hole 5.

[0006] Furthermore, the sealing film layer 6 is disposed outside the pixel encapsulation structure cavity 3 .

[0007] Furthermore, the sealing film layers 6 outside the adjacent pixel encapsulation structure cavities 3 are connected and fill the gaps between the adjacent pixel encapsulation structure cavities 3 .

[0008] Furthermore, the getter 4 is located around the MEMS micro-bridge structure 2 .

[0009] Furthermore, there is a getter 4 between adjacent pixel encapsulation structure cavities 3 .

[0010] In a second aspect, the present invention provides a method for preparing a pixel-level uncooled infrared detector, comprising the following steps:

[0011] Step S1: manufacturing a MEMS micro-bridge structure 2 and a pixel packaging structure cavity 3 covering each MEMS micro-bridge structure on a readout circuit substrate 1 based on a sacrificial layer;

[0012] Step S2: opening a deposition hole 5 on the pixel encapsulation structure cavity 3 and etching the sacrificial layer 7 below the deposition hole 5;

[0013] Step S3: depositing the getter 4 into the pixel encapsulation structure cavity 3 through the deposition hole 5;

[0014] Step S4: removing the getter film layer above the pixel encapsulation structure cavity 3 and completing the release of the sacrificial layer 7 through the deposition hole 5;

[0015] Step S5: plating a sealing film layer 6 outside the pixel packaging structure cavity 3, wherein the sealing film layer 6 blocks the deposition hole 5, thereby completing the sealing of the pixel packaging structure cavity 3.

[0016] Furthermore, after step S5, the getter 4 is activated by thermal activation.

[0017] Furthermore, the getter 4 is deposited into the pixel encapsulation structure cavity 3 by a physical / chemical vapor deposition process.

[0018] Furthermore, the physical vapor deposition process is an electron beam evaporation coating process.

[0019] Furthermore, the process of removing the getter film layer above the pixel encapsulation structure cavity 3 is a chemical mechanical polishing process.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the getter deposition is performed after the preparation of the pixel packaging structure cavity is completed, and the preparation process of the getter is designed at the last stage of the whole MEMS process, avoiding the influence of the previous processes on the getter, and the getter is activated by high-temperature thermal activation. After the vacuum cavity structure is sealed, the getter is directly thermally activated by an external high-temperature environment to ensure the vacuum degree of the detector cavity. The getter activation method of this solution is simple and easy to carry out mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of manufacturing the cavity of the pixel packaging structure of the present invention;

[0024] Figure 3 A schematic diagram of opening a deposition hole in a pixel encapsulation structure cavity and etching a sacrificial layer below the deposition hole according to the present invention;

[0025] Figure 4 It is a schematic diagram of depositing a getter film layer according to the present invention;

[0026] Figure 5 A schematic diagram of removing the external getter film layer according to the present invention;

[0027] Figure 6 A schematic diagram of releasing and removing the sacrificial layer of the present invention;

[0028] Figure 7 This is a schematic diagram of the infrared anti-reflection film layer of the present invention;

[0029] In the figure: 1. readout circuit substrate; 2. MEMS microbridge structure; 3. pixel packaging structure cavity; 4. getter; 5. deposition hole; 6. sealing film layer; 7. sacrificial layer. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the specific embodiments described herein are only used to explain the present invention and are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] The present invention provides a non-cooled infrared detector pixel-level packaging structure, comprising: a readout circuit substrate 1, a MEMS micro-bridge structure 2 is provided on the readout circuit substrate 1, a pixel packaging structure cavity 3 is covered on each of the MEMS micro-bridge structures 2, a deposition hole 5 is opened on the pixel packaging structure cavity 3, a getter 4 is provided below the deposition hole 5, and a sealing film layer 6 is provided outside the pixel packaging structure cavity 3, and the sealing film layer 6 blocks the deposition hole 5.

[0033] Furthermore, in order to ensure the stability of the packaging structure, a sealing film layer 6 is covered outside the pixel packaging structure cavity 3, the sealing film layers 6 outside adjacent pixel packaging structure cavities 3 are connected and fill the gaps between adjacent pixel packaging structure cavities 3, and there is an air-absorbing agent 4 between adjacent pixel packaging structure cavities 3.

[0034] Furthermore, in order to prevent the getter from affecting the performance of the MEMS micro-bridge structure, the getter 4 is disposed around the MEMS micro-bridge structure 2 .

[0035] Furthermore, the sealing film layer 6 may be an infrared anti-reflection film.

[0036] Example 2

[0037] The present invention provides a method for preparing a pixel-level uncooled infrared detector, comprising the following steps:

[0038] Step S1: manufacturing a MEMS micro-bridge structure 2 and a pixel packaging structure cavity 3 covering each MEMS micro-bridge structure on a readout circuit substrate 1 based on a sacrificial layer.

[0039] Step S2: opening a deposition hole 5 on the pixel encapsulation structure cavity 3 and etching the sacrificial layer 7 below the deposition hole 5; specifically, opening the deposition hole 5 on the pixel encapsulation structure cavity 3 by using a photolithography process.

[0040] Step S3: depositing the getter 4 into the pixel encapsulation structure cavity 3 through the deposition hole 5 .

[0041] Specifically, the present invention uses a physical / chemical vapor deposition process to deposit the getter into the interior of the pixel packaging structure cavity. The physical vapor deposition process is an electron beam evaporation coating process. Electron beam evaporation is a surface coating technology based on an electron beam heat source, and its principle is simple and effective. In this process, a high-energy electron beam is focused on the surface of the material to be evaporated, and the material is locally heated through energy transfer, so that it evaporates into a gaseous state. Subsequently, the gaseous material is deposited on the target substrate in a vacuum environment to form a thin film. This process is highly controllable and repeatable, and can achieve precise control of the film thickness, composition and structure. The present invention deposits the getter after the preparation of the pixel packaging structure cavity is completed, and the preparation process of the getter is designed in the last stage of the entire MEMS process, avoiding the influence of the previous processes on the getter.

[0042] Step S4: removing the getter film layer above the pixel encapsulation structure cavity 3 and releasing the sacrificial layer 7 through the deposition hole 5 .

[0043] Specifically, the process of removing the getter film layer above the pixel encapsulation structure cavity 3 is a chemical mechanical polishing process.

[0044] Step S5: plating a sealing film layer 6 outside the pixel packaging structure cavity 3, wherein the sealing film layer 6 blocks the deposition hole 5, thereby completing the sealing of the pixel packaging structure cavity 3.

[0045] Furthermore, the getter 4 is activated by thermal activation, that is, the getter is activated by external high-temperature heat. The getter of the present invention is thermally activated, the activation method is simple, and it is easy to carry out batch production.

[0046] The above embodiments only express the preferred implementation mode of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An uncooled infrared detector pixel level packaging structure, comprising: A readout circuit substrate (1), wherein the readout circuit substrate (1) has a MEMS micro-bridge structure (2), each of the MEMS micro-bridge structures (2) is covered with a pixel packaging structure cavity (3), a deposition hole (5) is opened on the pixel packaging structure cavity (3), a getter (4) is provided below the deposition hole (5), and a sealing film layer (6) is provided outside the pixel packaging structure cavity (3), and the sealing film layer (6) blocks the deposition hole (5).

2. The uncooled infrared detector pixel level packaging structure according to claim 1, characterized in that: The sealing film layer (6) is disposed outside the pixel packaging structure cavity (3).

3. The uncooled infrared detector pixel level packaging structure according to claim 1, characterized in that: The sealing film layers (6) outside the adjacent pixel packaging structure cavities (3) are connected and fill the gaps between the adjacent pixel packaging structure cavities (3).

4. The uncooled infrared detector pixel level packaging structure according to claim 1, characterized in that: The getter (4) is located around the MEMS microbridge structure (2).

5. The uncooled infrared detector pixel level packaging structure according to claim 1, characterized in that: A getter (4) is provided between adjacent pixel encapsulation structure cavities (3).

6. A method for preparing an uncooled infrared detector pixel-level packaging structure, comprising the following steps: Step S1: manufacturing a MEMS micro-bridge structure (2) and a pixel packaging structure cavity (3) covering each MEMS micro-bridge structure based on a sacrificial layer on a readout circuit substrate (1); Step S2: opening a deposition hole (5) on the pixel encapsulation structure cavity (3) and etching the sacrificial layer (7) below the deposition hole (5); Step S3: depositing the getter (4) into the interior of the pixel encapsulation structure cavity (3) through the deposition hole (5); Step S4: removing the getter film layer above the pixel encapsulation structure cavity (3), and completing the release of the sacrificial layer (7) through the deposition hole (5); Step S5: plating a sealing film layer (6) on the outside of the pixel packaging structure cavity (3), wherein the sealing film layer (6) blocks the deposition hole (5), thereby completing the sealing of the pixel packaging structure cavity (3).

7. The method for preparing the uncooled infrared detector pixel level packaging structure according to claim 6, characterized in that: After step S5, the getter (4) is activated by thermal activation.

8. The method for preparing the uncooled infrared detector pixel level packaging structure according to claim 6, characterized in that: The getter (4) is deposited inside the pixel packaging structure cavity (3) using a physical / chemical vapor deposition process.

9. The method for preparing the uncooled infrared detector pixel level packaging structure according to claim 6, characterized in that: The physical vapor deposition process is an electron beam evaporation coating process.

10. The method for preparing the uncooled infrared detector pixel level packaging structure according to claim 6, characterized in that: The process for removing the getter film layer above the pixel encapsulation structure cavity (3) is a chemical mechanical polishing process.

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