Area array level package uncooled infrared detector and preparation method thereof

Abstract

The application discloses a face array level packaged non-refrigeration infrared detector and a preparation method thereof, and relates to the field of detectors. The face array level packaged non-refrigeration infrared detector comprises a readout circuit substrate and effective elements of a pixel area arranged on the upper surface of the readout circuit substrate and electrically connected with the readout circuit substrate, and further comprises a getter deposition area. The face array level packaged non-refrigeration infrared detector opens a separate area for the getter main body, and the deposition of the getter main body is performed after the release of the structural sacrifice layer, so that the influence of high temperature and organic solution on the performance of the getter main body in the MEMS process is avoided, and the getter main body is activated by heat, so that the activation mode of the getter main body is simple and batch production and manufacturing are easy to realize.

Description

Technical Field

[0001] This invention relates to the field of detector technology, specifically to an array-level packaged uncooled infrared detector and its fabrication method. Background Technology

[0002] Uncooled infrared focal plane array detectors (FLADs) perform imaging by absorbing infrared energy from the surrounding environment and converting it into electrical signals in an ultra-high vacuum environment. The fabrication of uncooled infrared detectors requires the use of a getter, which is activated within a vacuum-sealed environment to remove residual gases and maintain a higher vacuum level. Furthermore, if the vacuum level decreases during later use, the getter can be reactivated to absorb residual gases, restoring the high vacuum environment to the detector.

[0003] Currently, uncooled infrared detectors are mainly packaged using metal, ceramic, wafer-level, and pixel-level methods. Metal and ceramic packaging uses columnar getters, which are soldered to the lead wires of the housing. Before packaging, the getter is electrically or thermally activated to maintain a high vacuum. Wafer-level packaging uses thin-film getters, integrating them onto the cap wafer. Finally, during bonding, the high temperature of the bonding process thermally activates the getter, thus avoiding the influence of temperature on the getter during MEMS fabrication. Pixel-level packaging integrates a cap wafer with a MEMS wafer, building upon wafer-level packaging. It uses a single material to directly encapsulate the entire surface of the MEMS microstructure. In this packaging method, the getter needs to be integrated into the entire microcavity structure. Currently reported solutions place the getter at the bottom of the infrared microelectrothermal agent, meaning the getter deposition is completed during the MEMS front-end process. However, the multiple high-temperature baking and organic solution cleaning processes involved in conventional semiconductor processes can affect the getter's performance. Furthermore, after the MEMS structure is completed, oxygen is released at high temperatures to remove the sacrificial layer. In this environment, the getter is prematurely activated, leading to a loss of getter capability and compromising the vacuum level within the cavity, resulting in poor detector vacuum lifetime. Therefore, it is necessary to redesign the getter's structural layout and fabrication method to ensure its performance and enable full activation for effective getter action. To address the shortcomings of existing technologies, this invention provides an array-level packaged uncooled infrared detector and its fabrication method to solve the aforementioned problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an array-level packaged uncooled infrared detector and its fabrication method. A separate region is created for the getter body, and the getter body is deposited after the structural sacrificial layer is released. The fabrication process of the getter body is designed as the final stage of the entire MEMS process, avoiding the influence of previous processes on the getter body. Specifically, it avoids the impact of high temperatures and organic solutions during the MEMS process on the getter body's performance. Furthermore, thermal activation is employed, making the activation method of the getter body simple and easy for mass production.

[0005] Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An array-packaged uncooled infrared detector includes a readout circuit substrate, wherein the readout circuit substrate has a pixel region and the pixel region is provided with effective elements electrically connected to the readout circuit substrate, characterized in that: the readout circuit substrate also has a getter deposition region, the getter deposition region is provided with a getter body, the top of the readout circuit substrate is provided with a structural cavity, the structural cavity is provided with a release hole, and the getter body corresponds to the release hole located above the getter deposition region.

[0008] Preferably, the top of the structural cavity is provided with a sealing film to block the release hole, and a vacuum cavity is formed between the readout circuit substrate, the structural cavity, and the sealing film.

[0009] Preferably, the release hole includes 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 position and shape of the getter body correspond one-to-one with those of the second release hole.

[0010] A method for fabricating an array-level packaged uncooled infrared detector includes the following steps:

[0011] S1: Divide the pixel area and getter deposition area on the readout circuit substrate. Prepare effective elements in the pixel area on the readout circuit substrate through a sacrificial layer and fabricate a structural cavity covered on the readout circuit substrate. Make sacrificial layer release holes in the structural cavity to complete the release of the sacrificial layer.

[0012] S2: Block the release hole located above the pixel area, and only open the release hole located above the getter deposition area;

[0013] S3: Deposit getter material on the structure completed in step S2. The getter material will be deposited into the getter deposition area through the release hole above the getter deposition area to form the getter body.

[0014] S4: After the getter body is deposited, open the release hole located above the pixel area;

[0015] S5: A sealing film is deposited on the structural cavity to complete the vacuum cavity sealing, and the getter body is activated by heating.

[0016] Preferably, when the getter body is placed in the getter deposition area, a shielding baffle is provided 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 the vacuum cavity is sealed with a sealing film.

[0017] Preferably, the sealing film is an infrared antireflective film.

[0018] Preferably, the structural cavity and the shielding baffle are joined by a temporary bonding method.

[0019] Preferably, the getter body is deposited in the getter deposition zone using a physical vapor deposition process.

[0020] Preferably, the sealing film is deposited on the structural cavity using an electron beam evaporation coating process.

[0021] Preferably, the getter deposition zone is located inside the vacuum chamber.

[0022] This invention discloses an array-level packaged uncooled infrared detector and its fabrication method, which has the following beneficial effects:

[0023] 1. This array-level packaged uncooled infrared detector provides a separate area for the getter body. The getter body is deposited after the structural sacrificial layer is released. The fabrication process of the getter body is designed to be the last stage of the entire MEMS process, avoiding the influence of previous processes on the getter body. That is, it avoids the influence of high temperature and organic solution in the MEMS process on the performance of the getter body. Moreover, it adopts thermal activation, and the activation method of the getter body is simple and easy to mass-produce.

[0024] 2. This array-encapsulated uncooled infrared detector can easily block the first release hole through a shielding baffle, thereby facilitating the positioning and deposition of the getter body through the release hole. After the shielding baffle is temporarily bonded and the getter body is positioned and deposited, it can be easily removed and sealed with a sealing film to complete the vacuum chamber sealing.

[0025] 3. In this array-level packaged uncooled infrared detector, the sealing film is deposited on the structural cavity using electron beam evaporation coating technology. Unlike traditional evaporation methods, electron beam evaporation utilizes the coordination of electromagnetic fields to precisely bombard the target material in the crucible with high-energy electrons, causing it to melt and then deposit it on the substrate. Electron beam evaporation can deposit high-purity and high-precision films, thus ensuring the good performance of the sealing film. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 This is an initial schematic diagram of the getter deposition zone of the present invention;

[0029] Figure 3 This is a schematic diagram of the shielding baffle of the present invention;

[0030] Figure 4 This is a schematic diagram of the getter deposition of the present invention;

[0031] Figure 5 This is a schematic diagram illustrating the removal of the shielding baffle in this invention;

[0032] Figure 6 This is a schematic diagram of the sealing film layer of the present invention.

[0033] 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 Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This application provides an array-level packaged uncooled infrared detector and its fabrication method, which solves the problem that existing solutions place the getter at the bottom of the infrared microroofing calorimeter, which involves depositing the getter during the MEMS front-end process. However, the multiple high-temperature baking and organic solution cleaning processes involved in conventional semiconductor processes can affect the performance of the getter. In addition, after the MEMS structure is completed, oxygen is released at high temperatures to remove the sacrificial layer in the structure. Under such conditions, the getter is prematurely activated, resulting in the loss of gettering ability and the inability to guarantee the vacuum level in the cavity, which manifests as poor detector vacuum life.

[0036] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0037] This invention discloses an array-packaged uncooled infrared detector, according to the attached... Figure 1-6 As shown, the system includes a readout circuit substrate 1, which has a pixel area and an active element 2 electrically connected to the readout circuit substrate 1. The readout circuit substrate 1 also has a getter deposition area 3, which has a getter body 301. A structural cavity 4 is provided on the top of the readout circuit substrate 1, and a release hole is provided on the structural cavity 4. The getter body 301 corresponds to the release hole located above the getter deposition area 3.

[0038] Specifically, the top of the structural cavity 4 is provided with a sealing film 5 to block the release hole.

[0039] Specifically, a vacuum cavity 6 is formed between the readout circuit substrate 1, the structural cavity 4, and the sealing film 5.

[0040] 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, and the positions and shapes of the getter body 301 and the second release hole 302 correspond one-to-one.

[0041] 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 vacuum cavity 6 is sealed with a sealing film 5. The shielding baffle 7 facilitates the blocking of the first release hole 401, thereby making it easier for the getter body 301 to be positioned and deposited through the second release hole 302, thus completing the positioning of the getter body 301.

[0042] Furthermore, the structural cavity 4 and the shielding baffle 7 are bonded together by a temporary bonding method. After the shielding baffle 7 completes the positioning and deposition of the getter body 301 after the temporary bonding, it can be easily removed and coated with a sealing film 5 to complete the sealing of the vacuum cavity 6. The sealing film 5 is an infrared anti-reflection film.

[0043] Specifically, the activation method of the getter body 301 is thermal activation. Thermal activation is a simple method for activating the getter body 301 and is easy to mass-produce.

[0044] Specifically, when the getter body 301 is deposited in the getter deposition zone 3, a physical vapor deposition process is used. Physical vapor deposition technology refers to the technology of vaporizing the surface of the material source into gaseous atoms or molecules, or partially ionizing them into ions, under vacuum conditions using physical methods, and depositing a thin film on the substrate surface through a low-pressure gas or plasma process. Physical vapor deposition is one of the main surface treatment technologies.

[0045] Specifically, the sealing film 5 is deposited on the structural cavity 4 using an electron beam evaporation coating process. Unlike traditional evaporation methods, electron beam evaporation utilizes the coordination of an electromagnetic field to precisely bombard the target material inside the crucible with high-energy electrons, causing it to melt and then deposit onto the substrate. Electron beam evaporation can deposit high-purity and high-precision films, thus ensuring the good performance of the sealing film 5.

[0046] This invention also discloses a method for fabricating an array-packaged uncooled infrared detector, comprising the following steps:

[0047] S1: Divide the pixel area and getter deposition area 3 on the readout circuit substrate. Prepare effective elements 2 in the pixel area on the readout circuit substrate 1 through a sacrificial layer. Make a structural cavity covered on the readout circuit substrate 1. Make sacrificial layer release holes in the structural cavity to complete the release of the sacrificial layer.

[0048] S2: The vacuum chamber 6 is combined with the designed shielding baffle 7 by temporary bonding, and only the second release hole 302 at the position of the getter deposition area 3 is opened;

[0049] S3: The getter body 301 is fabricated on the structure completed in step S2. In the unblocked area, the getter will be deposited into the vacuum chamber 6 through the second release hole 302.

[0050] S4: After the getter body 301 has been deposited, remove the shielding baffle 7;

[0051] S5: A sealing film 5 is deposited on the structural cavity to complete the sealing of the vacuum cavity 6, and the getter body 301 is activated by heating.

[0052] The uncooled infrared detector in this array-level packaged method is to prepare the getter body 301 by temporarily bonding the shielding baffle 7 to the wafer structure cavity 4 after the structural sacrificial layer is released, only opening the getter deposition area 3, and depositing the getter body 301 into the getter deposition area 3 and the vacuum cavity 6 through a coating process.

[0053] This invention creates a separate region 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 to be in the last stage of the entire MEMS process, avoiding the influence of previous processes on the getter body 301. That is, it avoids the influence of high temperature and organic solution in the MEMS process on the performance of the getter body 301. Moreover, it adopts thermal activation, and the activation method of the getter body 301 is simple and easy to mass-produce.

[0054] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating an array-level packaged uncooled infrared detector, characterized in that: The array-encapsulated uncooled infrared detector includes a readout circuit substrate (1), a pixel area on the readout circuit substrate (1), an effective element (2) electrically connected to the readout circuit substrate (1) in the pixel area, a getter deposition area (3) on the readout circuit substrate (1), a getter body (301) in the getter deposition area (3), a structural cavity (4) on the top of the readout circuit substrate (1), a release hole on the structural cavity (4); a sealing film (5) for sealing the release hole on the top of the structural cavity (4), and a vacuum cavity (6) formed between the readout circuit substrate (1), the structural cavity (4), and the sealing film (5); the release hole includes a first release hole (401) located above the pixel area and a second release hole (302) located above the getter deposition area (3), the position and shape of the getter body (301) and the second release hole (302) correspond one-to-one; The preparation method includes the following steps: S1: Divide the pixel area and getter deposition area (3) on the readout circuit substrate. Prepare effective elements (2) in the pixel area on the readout circuit substrate (1) through a sacrificial layer. Make a structural cavity covered on the readout circuit substrate (1). Make a release hole on the structural cavity to complete the release of the sacrificial layer. S2: Block the first release hole (401) located above the pixel area and only open the second release hole (302) located above the getter deposition area (3). S3: Deposit getter material on the structure completed in step S2. The getter material will be deposited into the getter deposition area (3) through the second release hole (302) above the getter deposition area (3) to form the getter body (301). S4: After the getter body (301) is deposited, the first release hole (401) located above the pixel area is opened. S5: A sealing film (5) is deposited on the structural cavity to complete the sealing of the vacuum cavity (6), and the getter body (301) is activated by heating.

2. The method for fabricating an array-level packaged uncooled infrared detector according to claim 1, characterized in that: 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 shield the first release hole (401) located above the pixel area. After the getter body (301) is deposited into the getter deposition area (3) through the second release hole (302) located above the getter deposition area (3), the shielding baffle (7) is removed and the vacuum cavity (6) is sealed with a sealing film (5).

3. The method for fabricating an array-level packaged uncooled infrared detector according to claim 2, characterized in that: The sealing film (5) is an infrared anti-reflection film.

4. The method for fabricating an array-level packaged uncooled infrared detector according to claim 3, characterized in that: The structural cavity (4) and the shielding baffle (7) are joined together by a temporary bonding method.

5. The method for fabricating an array-level packaged uncooled infrared detector according to claim 1, characterized in that: The getter body (301) is deposited in the getter deposition zone (3) using a physical vapor deposition process.

6. The method for fabricating an array-level packaged uncooled infrared detector according to claim 2, characterized in that: The sealing film (5) is coated on the structural cavity (4) using an electron beam evaporation coating process.

7. The method for fabricating an array-level packaged uncooled infrared detector according to claim 1, characterized in that: The getter deposition zone (3) is located inside the vacuum chamber (6).

8. The method for fabricating an array-level packaged uncooled infrared detector according to claim 1, characterized in that: The second release hole (302) is larger than the first release hole (401).

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