Area array-level packaged uncooled infrared detector and preparation method therefor

Abstract

The present invention relates to the field of detectors. Disclosed are an area array-level packaged uncooled infrared detector and a preparation method therefor. The area array-level packaged uncooled infrared detector comprises a readout circuit substrate and active elements of a pixel region which is arranged on the upper surface of the readout circuit substrate and is electrically connected to the readout circuit substrate. The area array-level packaged uncooled infrared detector further comprises a getter deposition region. According to the area array-level packaged uncooled infrared detector, an independent region is opened up for a getter main body, and deposition of the getter main body is carried out after a structural sacrificial layer is released, so as to prevent the influence of high temperature and organic solutions on the performance of the getter main body during a MEMS process. Furthermore, thermal activation is adopted, and an activation mode of the getter main body is simple, thereby facilitating batch production and manufacturing.

Description

An array-level packaged uncooled infrared detector and its preparation method Technical Field

[0001] The present invention relates to the field of detector technology, and in particular to an area array-level packaged uncooled infrared detector and a preparation method thereof. Background Art

[0002] Uncooled infrared focal plane detectors (IFPDs) perform imaging in an ultra-high vacuum environment by absorbing external infrared energy and converting it into electrical signals. During the production of uncooled IR detectors, a getter must be used and activated within the detector's vacuum-sealed environment to remove residual gas and maintain a higher vacuum level. Furthermore, if the vacuum level drops during later use, the getter can be reactivated to absorb the residual gas, restoring the detector's high vacuum.

[0003] Currently, uncooled infrared detector packaging methods mainly include metal, ceramic, wafer-level, and pixel-level packaging. Metal and ceramic packaging uses columnar getters, which are welded to the tube and case leads. High vacuum is maintained by electrically or thermally activating the getters before packaging. Wafer-level packaging uses thin-film getters, which are integrated into the cap wafer and then thermally activated during bonding, utilizing the high temperature of the bonding process. This prevents the temperature from affecting the getters during the MEMS fabrication process. Pixel-level packaging integrates a cap wafer with a MEMS wafer based on wafer-level packaging, directly encapsulating the entire surface of the MEMS microstructure with a single material. Based on this packaging format, a getter needs to be integrated into the entire microcavity structure. Currently, reported solutions place the getter at the very bottom of the infrared microbolometer, completing getter deposition in the MEMS front-end process. However, the multiple high-temperature baking and organic solution cleaning processes involved in conventional semiconductor process flows can affect getter performance. Furthermore, after the MEMS structure is completed, the sacrificial layer in the structure is removed by oxygen release in a high-temperature environment. In this environment, the getter is prematurely activated, resulting in a loss of gettering ability and an inability to maintain vacuum in the cavity, resulting in a poor detector vacuum life. Therefore, it is necessary to redesign the getter's structural layout and preparation method to ensure getter performance and enable full activation of the getter to function effectively. To address the shortcomings of the prior art, the present invention provides an array-level packaged uncooled infrared detector and a preparation method thereof to address these issues.

[0004] Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides an array-level packaged non-cooled infrared detector and a preparation method thereof, which opens a separate area for the getter body, and deposits the getter body after the structural sacrificial layer is released. The preparation process of the getter body is designed in the last stage of the entire MEMS process, avoiding the influence of various previous processes on the getter body, that is, avoiding the influence of high temperature and organic solution in the MEMS process on the performance of the getter body. In addition, thermal activation is adopted, and the activation method of the getter body is simple, which is easy to carry out mass production.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A non-cooled infrared detector in an area array package includes a readout circuit substrate having a pixel area, wherein the pixel area is provided with an effective element electrically connected to the readout circuit substrate. The invention is characterized in that: the readout circuit substrate also has a getter deposition area, wherein the getter deposition area is provided with a getter body, a structural cavity is provided on the top of the readout circuit substrate, wherein the structural cavity is provided with a release hole, and the getter body corresponds to the release hole located above the getter deposition area.

[0010] Preferably, a sealing film for sealing the release hole is provided on the top of the structural cavity, and a vacuum cavity is formed between the readout circuit substrate, the structural cavity and the sealing film.

[0011] Preferably, the release holes include a first release hole located above the pixel area and a second release hole located above the getter deposition area, the second release hole is larger than the first release hole, and the getter body corresponds to the second release hole in position and shape.

[0012] A method for preparing an array-level packaged uncooled infrared detector comprises the following steps:

[0013] S1: Dividing the readout circuit substrate into a pixel area and a getter deposition area, preparing an effective element in the pixel area on the readout circuit substrate through a sacrificial layer, and making a structural cavity covering the readout circuit substrate, making a sacrificial layer release hole in the structural cavity, and completing the release of the sacrificial layer;

[0014] S2: Cover the release holes above the pixel area and only open the release holes above the getter deposition area;

[0015] S3: depositing a getter material on the structure manufactured in step S2. The getter material is deposited into the getter deposition area through the release holes above the getter deposition area to form a getter body.

[0016] S4: After the getter body is deposited, the release hole located above the pixel area is opened;

[0017] S5: A sealing film is plated on the structural cavity to complete the sealing of the vacuum cavity, and the getter body is activated by heating.

[0018] Preferably, when the getter body is placed in the getter deposition area, a shielding baffle is set on the top of the structural cavity to shield the release hole located above the pixel area. After the getter body is deposited into the getter deposition area through the release hole located above the getter deposition area, the shielding baffle is removed and a sealing film is used to complete the sealing of the vacuum cavity.

[0019] Preferably, the sealing film is an infrared anti-reflection film.

[0020] Preferably, the structural cavity and the shielding baffle are combined by temporary bonding.

[0021] Preferably, the getter body is deposited in the getter deposition zone using a physical vapor deposition process.

[0022] Preferably, the sealing film is deposited on the structural cavity by an electron beam evaporation process.

[0023] Preferably, the getter deposition area is arranged inside the vacuum cavity.

[0024] The present invention discloses an array-level packaged uncooled infrared detector and a preparation method thereof, which have the following beneficial effects:

[0025] 1. This array-level packaged uncooled infrared detector has a separate area for the getter body. The getter body is deposited after the structural sacrificial layer is released. The preparation process of the getter body is designed at the end of the entire MEMS process, avoiding the impact of various previous processes on the getter body. In other words, it avoids the impact of high temperature and organic solution in the MEMS process on the performance of the getter body. In addition, the getter body is activated by heat, which is simple and easy to mass produce.

[0026] 2. The array-level packaged non-cooled infrared detector conveniently blocks the first release hole by setting a shielding baffle, thereby facilitating the positioning and deposition of the getter body through the release hole, thereby completing the positioning of the getter body. After the shielding baffle is temporarily bonded to complete the positioning and deposition of the getter body, it is convenient to remove the shielding baffle and use a sealing film coating to complete the sealing of the vacuum cavity.

[0027] 3. The array-level packaged uncooled infrared detector uses an electron beam evaporation coating process to coat the sealing film on the structural cavity. Unlike traditional evaporation methods, electron beam evaporation uses the coordination of electromagnetic fields to accurately use high-energy electrons to bombard the target material in the crucible, causing it to melt and then deposit on the substrate. Electron beam evaporation can produce high-purity and high-precision films, thereby ensuring the good effect of the sealing film. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] FIG1 is a schematic diagram of the overall structure of the present invention;

[0030] FIG2 is an initial schematic diagram of the getter deposition area of ​​the present invention;

[0031] FIG3 is a schematic structural diagram of a shielding baffle according to the present invention;

[0032] FIG4 is a schematic diagram of getter deposition according to the present invention;

[0033] FIG5 is a schematic diagram of removing the shielding baffle according to the present invention;

[0034] FIG6 is a schematic diagram of the plated sealing film layer of the present invention.

[0035] In the figure: 1. Readout circuit substrate; 2. Active element; 3. Getter deposition area; 301. Getter body; 302. Second release hole; 4. Structural cavity; 401. First release hole; 5. Sealing film; 6. Vacuum cavity; 7. Shielding baffle. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] The embodiments of the present application provide an array-level packaged non-cooled infrared detector and a preparation method thereof, thereby solving the problem that the existing solution at this stage is to place the desirability agent at the bottom of the infrared micro-bolometer, which means that the deposition of the desirability agent is completed 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 desirability agent. At the same time, after the MEMS structure is completed, the sacrificial layer in the structure will be released and removed by oxygen in a high-temperature environment. In this environment, the desirability agent will be activated prematurely, resulting in the loss of desirability and the inability to ensure the vacuum degree in the cavity, which manifests as a poor vacuum life of the detector.

[0038] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0039] An embodiment of the present invention discloses an area array-level packaged uncooled infrared detector, which, as shown in Figures 1-6, includes a readout circuit substrate 1, wherein the readout circuit substrate 1 has a pixel area, and the pixel area is provided with an effective element 2 electrically connected to the readout circuit substrate 1. The readout circuit substrate 1 also has a getter deposition area 3, and the getter deposition area 3 is provided with a getter body 301. The top of the readout circuit substrate 1 is provided with a structural cavity 4, and the structural cavity 4 is provided with a release hole. The getter body 301 corresponds to the release hole located above the getter deposition area 3.

[0040] Specifically, a sealing film 5 for sealing the release hole is provided on the top of the structural cavity 4 .

[0041] Specifically, a vacuum cavity 6 is formed between the readout circuit substrate 1 , the structural cavity 4 and the sealing film 5 .

[0042] Specifically, the release holes include a first release hole 401 located above the pixel area and a second release hole 302 located above the getter deposition area 3. The second release hole 302 is larger than the first release hole 401. The position and shape of the getter body 301 and the second release hole 302 correspond one to one.

[0043] Furthermore, when the getter body 301 is placed in the getter deposition area 3, a shielding baffle 7 is set on the top of the structural cavity 4 to block the first release hole 401. After the getter body 301 is deposited into the getter deposition area 3 through the second release hole 302, the shielding baffle 7 is removed and the sealing film 5 is used to complete the sealing of the vacuum cavity 6. The shielding baffle 7 is set to facilitate the blocking of the first release hole 401, thereby facilitating the positioning and deposition of the getter body 301 through the second release hole 302, thereby completing the positioning of the getter body 301.

[0044] Furthermore, the structural cavity 4 and the shielding baffle 7 are combined by temporary bonding. After the shielding baffle 7 completes the positioning and deposition of the getter body 301 after temporary bonding, it is convenient to remove and use the sealing film 5 to coat the vacuum cavity 6. The sealing film 5 is an infrared anti-reflection film.

[0045] Specifically, the activation method of the getter body 301 is thermal activation. By adopting thermal activation, the activation method of the getter body 301 is simple and easy to carry out batch production.

[0046] Specifically, the getter body 301 adopts a physical vapor deposition process when depositing in the getter deposition area 3. Physical vapor deposition technology refers to the technology of using physical methods to vaporize the surface of the material source into gaseous atoms or molecules, or partially ionize it into ions under vacuum conditions, and deposit a thin film on the surface of the substrate through a low-pressure gas or plasma process. Physical vapor deposition is one of the main surface treatment technologies.

[0047] Specifically, the sealing film 5 is coated on the structural cavity 4 using an electron beam evaporation coating process. Unlike traditional evaporation methods, electron beam evaporation uses the cooperation of electromagnetic fields to accurately use high-energy electrons to bombard the target material in the crucible, causing it to melt and then deposit on the substrate. Electron beam evaporation can produce high-purity and high-precision films, thereby ensuring that the sealing film 5 has a good effect.

[0048] The present invention also discloses a method for preparing an area array-level packaged uncooled infrared detector, comprising the following steps:

[0049] S1: Dividing the readout circuit substrate into a pixel area and a getter deposition area 3, preparing an effective element 2 in the pixel area on the readout circuit substrate 1 through a sacrificial layer, and making a structural cavity covering the readout circuit substrate 1, making a sacrificial layer release hole in the structural cavity, and completing the release of the sacrificial layer;

[0050] S2: Combine the vacuum chamber 6 with the designed shielding baffle 7 by temporary bonding, and only open the second release hole 302 at the getter deposition area 3;

[0051] S3: A getter body 301 is produced on the structure produced in step S2. In the unblocked area, the gettered gas is deposited into the vacuum chamber 6 through the second release holes 302.

[0052] S4: After the deposition of the getter body 301 is completed, the shielding baffle 7 is removed;

[0053] S5: a sealing film 5 is plated on the structural cavity to complete the sealing of the vacuum cavity 6, and the getter body 301 is activated by heating.

[0054] The preparation method of the getter body 301 of the array-level packaged uncooled infrared detector is as follows: after the structural sacrificial layer is released, a temporary bonding process is performed with the wafer structure cavity 4 through the shielding baffle 7, and only the getter deposition area 3 is opened. The getter body 301 is deposited in the getter deposition area 3 and inside the vacuum cavity 6 through a coating process;

[0055] The present invention opens a separate area for the getter body 301, and deposits the getter body 301 after the structural sacrificial layer is released. The preparation process of the getter body 301 is designed in the last section of the entire MEMS process, thereby avoiding the influence of various previous processes on the getter body 301, that is, avoiding the influence of high temperature and organic solution in the MEMS process on the performance of the getter body 301. In addition, by adopting thermal activation, the activation method of the getter body 301 is simple and easy to carry out mass production.

[0056] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0057] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An array-level packaged uncooled infrared detector, characterized in that: The invention comprises a readout circuit substrate (1), wherein the readout circuit substrate (1) has a pixel region, wherein the pixel region is provided with an effective element (2) electrically connected to the readout circuit substrate (1), wherein the readout circuit substrate (1) also has a getter deposition region (3), wherein the getter deposition region (3) is provided with a getter body (301), wherein a structural cavity (4) is provided on the top of the readout circuit substrate (1), wherein a release hole is provided on the structural cavity (4), and wherein the getter body (301) corresponds to the release hole located above the getter deposition region (3).

2. The area array level packaged uncooled infrared detector according to claim 1, characterized in that: A sealing film (5) for sealing the release hole is provided on the top of the structural cavity (4), and a vacuum cavity (6) is formed between the readout circuit substrate (1), the structural cavity (4) and the sealing film (5).

3. The area array level packaged uncooled infrared detector according to claim 1, characterized in that: The release holes include a first release hole (401) located above the pixel area and a second release hole (302) located above the getter deposition area (3), wherein the second release hole (302) is larger than the first release hole (401), and the getter body (301) and the second release hole (302) have a one-to-one correspondence in position and shape.

4. A method for preparing an array-level packaged uncooled infrared detector, characterized in that: The steps include: S1: dividing a pixel region and a getter deposition region (3) on a readout circuit substrate, preparing an effective element (2) in the pixel region on the readout circuit substrate (1) through a sacrificial layer, and making a structural cavity covered on the readout circuit substrate (1), making a sacrificial layer release hole on the structural cavity, and completing the release of the sacrificial layer; S2: blocking the release hole (401) located above the pixel area, and only opening the release hole (302) located above the getter deposition area (3); S3: depositing a getter material on the structure manufactured in step S2, wherein the getter material is deposited to the getter deposition area (3) through the release hole (302) above the getter deposition area (3), forming a getter body (301); S4: After the deposition of the getter body (301) is completed, the release hole (401) located above the pixel area is opened; S5: a sealing film (5) is plated on the structural cavity to complete the sealing of the vacuum cavity (6), and the getter body (301) is activated by heating.

5. The method for preparing an area array level packaged uncooled infrared detector according to claim 4, characterized in that: When the getter body (301) is placed in the getter deposition area (3), a shielding baffle (7) is arranged on the top of the structural cavity (4) to shield the release hole (401) located above the pixel area; after the getter body (301) is deposited into the getter deposition area (3) through the release hole (302) located above the getter deposition area (3), the shielding baffle (7) is removed and a sealing film (5) is used to complete the sealing of the vacuum cavity (6).

6. The method for preparing an area array level packaged uncooled infrared detector according to claim 5, characterized in that: The sealing film (5) is an infrared anti-reflection film.

7. The method for preparing an area array level packaged uncooled infrared detector according to claim 5, characterized in that: The structural cavity (4) and the shielding baffle (7) are combined by means of temporary bonding.

8. The method for preparing an area array level packaged uncooled infrared detector according to claim 4, characterized in that: The getter body (301) is deposited in the getter deposition area (3) using a physical vapor deposition process.

9. The method for preparing an area array level packaged uncooled infrared detector according to claim 5, characterized in that: The sealing film (5) is coated on the structural cavity (4) by using an electron beam evaporation coating process.

10. The method for preparing an area array level packaged uncooled infrared detector according to claim 4, characterized in that: The getter deposition area (3) is arranged inside the vacuum chamber (6).

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