Array-level vacuum packaging structure and fabrication method of uncooled infrared detector

Abstract

This invention belongs to the field of uncooled infrared detector technology, specifically an array-level vacuum packaging structure for uncooled infrared detectors and its fabrication method. This invention employs an array-level vacuum packaging structure, which reduces the size, cost, and weight of uncooled infrared detectors. The array-level vacuum packaging method utilizes MEMS technology, introducing no additional materials or components, and the fabrication process is fully compatible with the uncooled infrared structure process, eliminating the need for additional production lines. This reduces the packaging steps and costs, while also facilitating chip miniaturization.

Description

Technical Field

[0001] This invention belongs to the field of uncooled infrared detector technology, specifically an array-level vacuum packaging structure for uncooled infrared detectors and its fabrication method. Background Technology

[0002] Infrared imaging technology is widely used in night vision and night combat equipment, vehicle-mounted systems, security monitoring, medical quarantine, disaster early warning, and industrial fields. Its core component is the infrared focal plane array detector (FLAD), which detects the infrared radiation of a target and converts the target's temperature distribution into a video image. Its imaging capabilities include long range, good anti-interference performance, strong smoke penetration, and all-weather, all-time operation, making it a strategically significant dual-use technology. Uncooled infrared detectors absorb the infrared radiation energy of objects, causing changes in the resistance of the thermistor material in the detection unit, which in turn causes changes in the current or voltage in the circuit. Finally, by collecting the information on these changes in current or voltage, an infrared image is formed.

[0003] Uncooled infrared detectors are MEMS systems integrating micromechanical components, miniature sensors, actuators, signal processing circuits, and control circuits. Due to their suspended microbridge structure, uncooled infrared detectors are susceptible to environmental factors and therefore require vacuum packaging. Existing vacuum packaging methods for uncooled infrared detectors include metal packaging, ceramic packaging, and wafer-level packaging. These methods face challenges in the miniaturization and cost reduction of uncooled infrared detectors, necessitating the research of a new vacuum packaging method to further reduce the size and cost of uncooled infrared detectors.

[0004] Therefore, a solution is needed to address the problems in existing technologies. Array-level vacuum packaging is a technology that directly vacuum-packages the MEMS structural units of an uncooled infrared detector using MEMS processes. Array-level vacuum packaging does not introduce additional independent components and features high integration. Summary of the Invention

[0005] This invention provides an array-level vacuum packaging structure for uncooled infrared detectors and its fabrication method, which can at least solve some of the problems existing in the prior art.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] An array-level vacuum encapsulation structure for an uncooled infrared detector, the encapsulation structure including:

[0008] A substrate with built-in readout circuitry;

[0009] The detector array structure located above the substrate includes multiple pixels, each pixel including a support anchor and a support microbridge structure, the support anchor being a cavity structure, and a sacrificial layer material being retained inside the cavity;

[0010] The microcap is supported on the substrate and support anchor on the outside of the detector array. An inverted microcavity is formed between the microcap and the substrate, and multiple pixels of the same detector array are placed in the same microcavity structure.

[0011] As a preferred embodiment of the packaging structure described in this invention, the packaging structure further includes a connecting metal located between the support anchor and the substrate, and a getter disposed on the upper surface of the substrate. The connecting metal and the getter are arranged in the same layer and are made of the same metal material.

[0012] As a preferred embodiment of the packaging structure described in this invention, the microcap includes a first support film layer and a sealing film. The first support film layer has a release hole, and the sealing film is disposed on the surface of the first support film layer to seal the release hole.

[0013] As a preferred embodiment of the packaging structure described in this invention, the microcap further includes an antireflection film layer, which is disposed on the upper surface of the sealing film and / or the lower surface of the first support film layer.

[0014] As a preferred embodiment of the packaging structure described in this invention, the first support film layer is selected from amorphous silicon or silicon, and the thickness of the first support film layer is 0.5-5 micrometers.

[0015] As a preferred embodiment of the packaging structure described in this invention, the connecting metal is a common metal such as titanium, aluminum, gold, silver, copper, or a mixture thereof.

[0016] As a preferred embodiment of the packaging structure described in this invention, the getter is a surface-active metal or non-metal material, such as titanium, zirconium, vanadium, etc., with the getter thickness between 0.2 and 2 micrometers.

[0017] As a preferred embodiment of the encapsulation structure described in this invention, the sealing film is selected from germanium, amorphous silicon, and zinc sulfide, and has a thickness of 0.5-8 micrometers; the antireflective coating layer is selected from a single layer of germanium or a single layer of zinc sulfide or an alternating combination of the two.

[0018] As a preferred embodiment of the packaging structure described in this invention, the first supporting film layer is further provided with release holes. The number of release holes is one or more, the pore diameter is 0.3-2 micrometers, and the release holes can be prepared as straight holes, Z-shaped holes, or Y-shaped holes using a multilayer film structure.

[0019] To solve the above-mentioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0020] The fabrication method of the array-level vacuum packaging structure of the above-mentioned uncooled infrared detector includes the following steps:

[0021] S1. A probe array structure is fabricated on the upper surface of a substrate. The probe array structure includes multiple pixels, and each pixel includes a support anchor and a support microbridge structure.

[0022] S2. A sacrificial layer is prepared on the substrate and the detector array structure, the sacrificial layer material on the support anchor is etched, and the sacrificial layer material inside the support anchor cavity is retained;

[0023] S3. Fabricate a microcap, which is supported on a substrate and a support anchor on the outside of the detector array. An inverted microcavity is formed between the microcap and the substrate, and multiple pixels of the same detector array are placed in the same microcavity structure.

[0024] As a preferred embodiment of the method for preparing the packaging structure described in this invention, the method further includes the following steps:

[0025] S0. Connecting metal and getter are simultaneously fabricated on the substrate before fabricating the detector array structure. When the connecting metal and getter are made of the same material, the fabrication can be completed simultaneously.

[0026] As a preferred embodiment of the method for preparing the packaging structure described in this invention, the method further includes preparing and etching a first sacrificial layer after the bonding metal and getter are prepared and before the probe array structure is prepared, to expose the bonding metal. The sacrificial layer material can be polyimide, silicon dioxide, silicon, or other materials.

[0027] As a preferred embodiment of the method for preparing the encapsulation structure described in this invention, the method further includes preparing a second sacrificial layer and etching the second sacrificial layer above the support anchor post. The etching stops at the upper end of the support anchor post, and the sacrificial layer material is retained inside the cavity of the support anchor post.

[0028] As a preferred embodiment of the method for preparing the packaging structure described in this invention, it further includes etching a first sacrificial layer and a second sacrificial layer outside the uncooled infrared detection array structure.

[0029] As a preferred embodiment of the method for preparing the packaging structure described in this invention, the method further includes preparing a first support film layer for the microcavity.

[0030] As a preferred embodiment of the method for preparing the packaging structure described in this invention, it further includes opening a release hole on the first support film layer.

[0031] As a preferred embodiment of the method for preparing the encapsulation structure described in this invention, it further includes releasing the first sacrificial layer and the second sacrificial layer. The second sacrificial layer inside the support anchor is sealed by the first support film layer and will not be released.

[0032] As a preferred embodiment of the method for preparing the packaging structure described in this invention, the method further includes preparing a sealing film, which achieves complete sealing of the release hole.

[0033] As a preferred embodiment of the method for preparing the packaging structure described in this invention, an antireflection coating layer is also deposited.

[0034] As a preferred embodiment of the method for preparing the packaging structure described in this invention, it further includes preparing an antireflection film layer on the surface of the second sacrificial layer before preparing the first support film layer.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. An array-level vacuum encapsulation structure is adopted, which reduces the size, cost, and weight of the uncooled infrared detector. Sacrificial layer material is retained within the support anchor cavity, preventing the first support film layer of the microcap from falling into the support anchor cavity during fabrication, thus reducing the fabrication difficulty of the first support film layer. Besides connecting to the substrate on the outer side of the array to form support, the portion of the first support film layer that falls onto the support anchor layer works together with the support anchor layer to provide support, reinforcing the stability of the vacuum microcavity.

[0037] 2. The first support film layer, the sealing film, and the antireflection film layer together form an inverted microcavity. The microcavity is a vacuum environment, and the detector array is placed in the same microcavity. The getter below all detector arrays is placed in the same microcavity, sharing the same adsorbed gas to ensure that the microcavity is maintained in a vacuum for a long time.

[0038] 3. The array-level vacuum packaging of the uncooled infrared detector is fabricated using MEMS technology, without introducing additional materials or components. The fabrication process is fully compatible with the uncooled infrared structure process, eliminating the need for additional production lines. This reduces the packaging steps and costs, while also facilitating chip miniaturization. Attached Figure Description

[0039] 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 the structures shown in these drawings without creative effort.

[0040] Figure 1 A schematic diagram of the encapsulation structure of the present invention, which includes a connecting metal and a getter;

[0041] Figure 2 This is a schematic diagram of the packaging structure of the present invention, which includes an etched first sacrificial layer.

[0042] Figure 3A schematic diagram of the packaging structure of the present invention, which includes an uncooled infrared detection array structure;

[0043] Figure 4 This is a schematic diagram of the packaging structure of the present invention with an etched second sacrificial layer;

[0044] Figure 5 A schematic diagram of the encapsulation structure of the present invention, which includes an etched first sacrificial layer and a second sacrificial layer.

[0045] Figure 6 This is a schematic diagram of the encapsulation structure of the present invention with a first supporting film layer;

[0046] Figure 7 A schematic diagram of the encapsulation structure with a release hole provided in this invention;

[0047] Figure 8 This is a schematic diagram of the encapsulation structure after the release of the first and second sacrificial layers in this invention.

[0048] Figure 9 A schematic diagram of the encapsulation structure of the present invention with a sealing film;

[0049] Figure 10 A schematic diagram of the encapsulation structure of the present invention with an antireflection film;

[0050] Figure 11 This is a schematic diagram of the encapsulation structure of the present invention with two layers of antireflective film.

[0051] Explanation of icon numbers:

[0052] 1-Substrate, 2-Connecting metal, 3-Getter, 4-First sacrificial layer, 5-Supporting anchor, 6-Microbridge structure, 7-Second sacrificial layer, 8-First supporting film layer, 9-Release hole, 10-Sealing film, 11-Antireflection film layer.

[0053] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0054] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

[0055] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0056] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0057] Example 1

[0058] Embodiment 1 of the present invention provides an array-level vacuum packaging structure for an uncooled infrared detector, such as... Figure 10 As shown.

[0059] An array-level vacuum packaging structure for an uncooled infrared detector, the packaging structure comprising:

[0060] The substrate 1 has a readout circuit inside it. The upper surface of the substrate 1 is provided with a connecting metal 2 and a getter 3. The connecting metal 2 is located at the reserved connection hole of the readout circuit. The connecting metal 2 and the getter 3 are arranged in the same layer and are made of the same metal material, that is, a metal material that has both gas-absorbing performance and conductivity.

[0061] The detector array structure located above the substrate 1 can be one or more sets, each set of detector array structures corresponds to an infrared detector, the detector array structure includes multiple pixels, each pixel includes a supporting anchor 5 and a supporting microbridge structure 6, the supporting anchor 5 is set on the surface of the connecting metal 2, and the getter 3 is located below the microbridge structure 6. Of course, the getter 3 can also be located around the detector array structure. The supporting anchor 5 plays the role of supporting the microbridge structure 6, and at the same time forms an electrical connection with the sensitive material in the microbridge structure 6, so that the electrical signal generated by the sensitive material is conducted to the readout circuit through the connecting metal 2.

[0062] The microcap includes a first support film layer 8, which is supported on a substrate 1 and a support anchor 5 outside the detection array, forming an inverted microcavity between the microcap and the substrate. One or more release holes 9 are formed on the first support film layer 8, and the shape of the release holes 9 can be a straight hole, a Y-shaped hole, or a Z-shaped hole.

[0063] The microcap also includes a sealing film 10 and an anti-reflection film 11, which are sequentially disposed on the outside of the first support film layer 8. The sealing film 10 covers the release holes 9 on the first support film layer 8, and the anti-reflection film 11 is used to enhance the transmittance of infrared light.

[0064] During the fabrication of the detector array structure, a first sacrificial layer 4 needs to be fabricated on top of the substrate 1. During the fabrication of the microcap, a second sacrificial layer 7 needs to be fabricated on top of the detector array structure. The supporting anchor 5 of this invention has a cavity structure; therefore, the material of the second sacrificial layer 7 falls into the cavity of the supporting anchor 5. Furthermore, during the fabrication of the microcap, only the material of the second sacrificial layer 7 above the supporting anchor 5 is etched, leaving the material of the second sacrificial layer 7 within the cavity of the supporting anchor 5. The first supporting film layer 8 does not fall into the cavity of the supporting anchor 5 during fabrication, reducing the fabrication difficulty of the first supporting film layer 8. Moreover, by sealing the material of the second sacrificial layer 7 within the cavity of the supporting anchor 5 through the first supporting film layer 8, the material of the second sacrificial layer 7 within the cavity of the supporting anchor 5 will not be released when the sacrificial layer material is released. Ultimately, together with the supporting anchor 5, it forms a support for the microcap, resulting in more reliable support. In addition to connecting with the substrate on the outside of the array to form a support, the portion of the first support film layer 8 that falls on the support anchor 5 forms a support column. The diameter of the support column is larger than the diameter of the cavity inside the support anchor 5. That is, the support column is supported on the support anchor 5 body on all sides, and the middle part is supported on the second sacrificial layer 7 material inside the cavity of the support anchor 5. The support column, the support anchor 5 and the second sacrificial layer 7 material inside it work together to provide support and strengthen the stability of the vacuum microcavity.

[0065] The first support film layer 8, the sealing film 10, and the antireflection film layer 11 together form an inverted microcavity. The microcavity is a vacuum environment, and multiple pixels of the same detector array are placed in the same microcavity. Furthermore, the getter 3 below the same detector array structure is also placed in the same microcavity to adsorb gas and ensure that the microcavity is maintained in a vacuum for a long time.

[0066] Example 2

[0067] Embodiment 2 of the present invention provides an array-level vacuum packaging structure for an uncooled infrared detector, such as... Figure 11 As shown. Its structure is basically the same as that of Embodiment 1 of the present invention, except that the microcap structure is different. In this embodiment, the microcap also includes a sealing film 10 and an anti-reflection film layer 11. The sealing film is disposed on the outside of the first support film layer 8, and there are at least two anti-reflection film layers, which are disposed on the outside of the sealing film 10 and the bottom of the first support film layer 8, respectively.

[0068] Of course, the antireflective coating layer 11 can also be disposed only on the lower side of the first support coating layer 8.

[0069] Example 3

[0070] Embodiment 3 of the present invention provides a method for fabricating an array-level vacuum packaging structure for an uncooled infrared detector, such as... Figure 1-9 As shown.

[0071] A method for fabricating an array-level vacuum encapsulation structure for an uncooled infrared detector includes the following steps:

[0072] (1) A substrate 1 with a built-in readout circuit is provided.

[0073] (2) A connecting metal 2 and a getter 3 are prepared on a substrate 1. The connecting metal 2 is set at the reserved connection hole of the readout circuit. The connecting metal 2 is a common metal such as titanium, aluminum, gold, silver, copper or a mixture thereof. The getter 3 is a metal or non-metal material with surface activity, such as a material with titanium, zirconium, vanadium or the like as the main components. The thickness of the getter 3 is between 0.2 and 2 micrometers. When the getter 3 is made of the same conductive material as the connecting metal 2, the two can be prepared at the same time.

[0074] (3) Prepare the first sacrificial layer 4 and etch it to expose the connecting metal 2. The sacrificial layer material can be polyimide, silicon dioxide, silicon and other materials.

[0075] (4) Prepare an uncooled infrared detection array structure, including a support anchor 5 and a support microbridge structure 6. The support anchor 5 has a cavity structure and is located on the surface of the connecting metal 2. The microbridge structure 6 is set above the getter 3.

[0076] (5) Prepare the second sacrificial layer 7 and etch the sacrificial layer material above the support anchor. The etching process stops at the upper end of the support anchor, leaving the second sacrificial layer material inside the cavity of the support anchor 5.

[0077] (6) Etch the first sacrificial layer 4 and the second sacrificial layer 7 outside the uncooled infrared detection array structure.

[0078] (7) A release hole 9 is formed on the first support film layer 8. The size of the release hole is between 0.3 and 2 micrometers. The number of release holes 9 on a single infrared imaging unit can be one or more. The release hole can be made into a straight hole, Z or Y type hole by using a multilayer film structure.

[0079] (8) Release the first sacrificial layer 4 and the second sacrificial layer 7. The sacrificial layer material inside the support anchor 5 is sealed by the first support membrane layer 8 and will not be released.

[0080] (9) Prepare a sealing film 10, which completely seals the release hole 9. The thickness of the sealing film is between 0.5 and 8 micrometers.

[0081] (10) An antireflective film layer 11 is prepared on the surface of the sealing film 10.

[0082] Example 4

[0083] The preparation steps are the same as those in Example 3, except that after the preparation and etching of the second sacrificial layer 7, the preparation of the first support film layer 8 includes the step of preparing the antireflection film layer 11.

[0084] This invention employs an array-level vacuum packaging structure, which can reduce the size, cost, and weight of uncooled infrared detectors. The array-level vacuum packaging method is fabricated using MEMS technology, without introducing additional materials or components, and the fabrication process is fully compatible with the uncooled infrared structure process, eliminating the need for additional production lines. This reduces the packaging steps and costs, while also facilitating chip miniaturization.

[0085] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An array-level vacuum packaging structure of a uncooled infrared detector, characterized in that, The package structure comprises: a substrate (1) with built-in readout circuitry; a detection array structure above the substrate (1), the detection array structure comprising a plurality of pixels, each pixel comprising a support anchor column (5) and a support micro-bridge structure (6), the support anchor column (5) being a hollow structure with a sacrificial layer material reserved inside the hollow; a micro-cover supported on the substrate (1) and the support anchor column (5) outside the detection array, the micro-cover and the substrate forming an inverted micro-cavity therebetween, and a plurality of pixels of the same detection array being arranged in the same micro-cavity structure.

2. The array-level vacuum packaging structure of a uncooled infrared detector according to claim 1, wherein, The package structure further comprises a connecting metal (2) between the support anchor column (5) and the substrate (1), and a getter (3) arranged on the upper surface of the substrate (1), the connecting metal (2) and the getter (3) being arranged in the same layer and using the same metal material.

3. The array-level vacuum packaging structure of a uncooled infrared detector according to claim 1, wherein, The micro-cover comprises a first support film layer (8) and a hole sealing film (10), the first support film layer (8) being provided with a release hole (9), and the hole sealing film (10) being arranged on the surface of the first support film layer (8) to seal the release hole (9).

4. The array-level vacuum packaging structure of a non-refrigerator infrared detector according to claim 3, wherein, The micro-cover further comprises an anti-reflection film layer (11) arranged on the upper surface of the hole sealing film (10) and / or the lower surface of the first support film layer (8).

5. The array-level vacuum packaging structure of a non-refrigerator infrared detector according to any one of claim 3, wherein, The material of the first support film layer (8) is selected from amorphous silicon or silicon; and / or the thickness of the first support film layer (8) is 0.5-5 microns.

6. The array-level vacuum packaging structure of a uncooled infrared detector according to claim 3, wherein: The material of the hole sealing film (10) is selected from germanium, amorphous silicon or zinc sulfide; and / or the thickness of the hole sealing film (10) is 0.5-8 microns.

7. The array-level vacuum packaging structure of a uncooled infrared detector according to claim 4, wherein: The material of the anti-reflection film layer (11) is selected from single-layer germanium or single-layer zinc sulfide or an alternating combination of the two.

8. The array-level vacuum packaging structure of claim 3, wherein: The aperture of the release hole (9) is 0.3-2 microns; and / or the shape of the release hole (9) is selected from straight hole, Y-shaped hole or Z-shaped hole.

9. A method of fabricating an array-level vacuum packaging structure of a uncooled infrared detector, characterized by, The method comprises the following steps: S1. Preparing a detection array structure on the upper surface of the substrate (1), the detection array structure comprising a plurality of pixels, each pixel comprising a support anchor column (5) and a support micro-bridge structure (6); S2. Preparing a sacrificial layer above the substrate (1) and the detection array structure, etching the sacrificial layer material above the support anchor column (5), and reserving the sacrificial layer material inside the hollow of the support anchor column (5); S3. Preparing a micro-cover supported on the substrate (1) and the support anchor column (5) outside the detection array, the micro-cover and the substrate forming an inverted micro-cavity therebetween, and a plurality of pixels of the same detection array being arranged in the same micro-cavity structure.

10. The method of claim 9, wherein the method further comprises: The method further comprises the following steps: S0. Simultaneously preparing the connecting metal (2) and the getter (3) on the substrate (1) before preparing the detection array structure.

Images