Infrared FPA-on-MEMS technology

Abstract

The application discloses infrared FPA-on-MEMS technology, belongs to the field of optical imaging and micro-electro-mechanical system integration technology, is used for manufacturing of infrared FPA-on-MEMS chip, utilizes the design of electrothermal-electrostatic dual driving module manufacturing process and the integration of infrared FPA unit on the middle platform of electrothermal-electrostatic dual driving module, can realize the coupling design of infrared FPA unit and MEMS driving technology on the chip level, and obtains infrared FPA-on-MEMS chip with automatic displacement control capability.The infrared FPA-on-MEMS technology of the application can effectively overcome the problems of large volume, slow speed, high power consumption and complex system caused by the fact that the traditional infrared imaging system relies on external optical mechanical components to realize functions such as anti-shake, scanning and zooming, improves the integration and reliability of the infrared thermal imaging system, breaks through the application bottleneck of the infrared thermal imaging technology, greatly improves the system integration and comprehensive use performance of the infrared thermal imaging system, and has excellent application prospect.

Description

Technical Field

[0001] This invention belongs to the field of optical imaging and microelectromechanical system integration technology, and relates to infrared FPA-on-MEMS technology, and in particular provides an infrared FPA-on-MEMS chip and its fabrication method. Background Technology

[0002] In the field of optical imaging, infrared thermal imaging technology has a wide range of applications. For traditional infrared thermal imaging systems, the overall performance mainly depends on the sensitivity, resolution, and frame rate characteristics of the detector itself, and is limited by the mechanical stability, flexibility, and complexity of the optical components.

[0003] In the application of infrared thermal imaging systems, challenges arise from issues such as image stabilization, field-of-view switching and zooming, and system integration. For example, in vibrating environments such as handheld, vehicle-mounted, or airborne systems, conventional infrared thermal imaging systems often require complex lens-based optical image stabilization or post-processing image algorithms to compensate for shake, thus solving the system's image stabilization problem. The former increases size, weight, and cost, while the latter sacrifices image quality and real-time performance. Furthermore, traditional infrared thermal imaging systems typically require mechanical zoom lenses for field-of-view switching and zoom adjustment, which are bulky, slow, and power-consuming, making them unsuitable for miniaturized and highly agile applications (such as drones and AR / VR applications). In addition, in traditional infrared thermal imaging systems, the detector, stabilization module, and scanning module are usually separate components, resulting in a bloated system and low reliability.

[0004] The aforementioned technical problems have hindered the development of infrared thermal imaging technology, preventing it from fully realizing its technological potential and resulting in significant application limitations. Summary of the Invention

[0005] To address one or more of the above-mentioned defects or improvement needs of existing technologies, this invention provides infrared FPA-on-MEMS technology, which can reliably integrate infrared FPA with a MEMS movable platform to obtain an integrated device with functions such as optical image stabilization, electronic image stabilization, micro-scanning, and fast field-of-view switching. By utilizing the precise control of the MEMS movable platform, the translation, rotation, or deformation control of the infrared FPA can be achieved, thereby improving the overall performance of the infrared thermal imaging system.

[0006] To achieve the above objectives, one aspect of the present invention provides an infrared FPA-on-MEMS chip, comprising an infrared FPA unit and an electrothermal-electrostatic dual-drive module; The electrothermal-electrostatic dual-drive module includes a central platform, an inner frame, and an outer frame; wherein: The four corners of the central platform are connected to the inner frame via spring beams, and several electrostatic drive units are provided between each side of the outer periphery of the central platform and the inner periphery of the inner frame. The inner frame is located inside the outer frame, and several electrothermal drive units are provided between each side of the outer periphery of the inner frame and the inner periphery of the outer frame. The infrared FPA unit is located on the central platform.

[0007] Another aspect of the present invention provides a method for fabricating an infrared FPA-on-MEMS chip, wherein the infrared FPA-on-MEMS chip includes an infrared FPA unit and an electrothermal-electrostatic dual-drive module; wherein: The electrothermal-electrostatic dual-drive module includes a central platform, an inner frame, and an outer frame. The four corners of the central platform are connected to the inner frame via spring beams, and several electrostatic drive units are arranged between the outer periphery of the central platform and the inner periphery of the inner frame. The inner frame is located inside the outer frame, and several electrothermal drive units are arranged between the outer periphery of the inner frame and the inner periphery of the outer frame. The manufacturing process of the electrothermal-electrostatic dual-drive module is as follows: (1) Prepare the wafer and etch the electrostatic isolation channel, and fill the electrostatic isolation channel with insulating material and cure it; (2) Fabricate a first insulating layer for forming an electrothermal drive, comb tooth mask; (3) Deposit and strip the heating resistor forming the electrothermal drive unit on the first insulating layer; (4) Make a second insulating layer on the heating resistor and open the connection through hole; (5) Fabricate the Bimorph part of the electrothermal drive unit, on-chip traces and pads; (6) Etch the front structure of the wafer to obtain the comb teeth, spring beam and central platform of the electrostatic drive unit; (7) Fill the comb tooth area of ​​the electrostatic drive unit with photoresist, and make the photoresist fill the gap between each comb tooth; (8) Apply adhesive, perform photolithography patterning, and deep silicon etching on the back side of the wafer to remove excess back side portion of the wafer; (9) Release the electrothermal drive unit, remove the photoresist on the front side of the wafer, and obtain the electrothermal-electrostatic dual drive module; The infrared FPA unit is set on the central platform; and the infrared FPA unit is fabricated in layers on the central platform during the manufacturing process of the electrothermal-electrostatic dual-drive module; or, the infrared FPA unit is a prefabricated part, which is set on the central platform after the process (9) is completed.

[0008] As a further improvement of the present invention, in process (1), the insulating material filled in the electrostatic isolation channel is BCB resin; and / or In process (1), after the insulating material is filled, a chemical mechanical polishing process is also performed to remove excess insulating material from the wafer surface; and / or In process (1), the wafer is an SOI wafer or a pure silicon wafer.

[0009] As a further improvement of the present invention, in process (3), the heating resistance is a platinum layer, tungsten layer, polycrystalline silicon layer or nickel-chromium alloy layer deposited; and / or The first insulating layer and / or the second insulating layer are SiO2 layers prepared by deposition.

[0010] As a further improvement of the present invention, in process (5), a metal layer is deposited and stripped to form an electrically heated Bimorph portion, on-chip traces, and pads; and The metal layer is an Al layer, an Au layer, or a Cu layer.

[0011] As a further improvement of the present invention, in process (9), a laser scribing process is also performed, and the wafer is divided into individual chips according to the distribution of each electrothermal-electrostatic dual-drive module.

[0012] As a further improvement of the present invention, the infrared FPA unit is fabricated in layers on the central platform during the fabrication of the electrothermal-electrostatic dual-drive module; and The electrostatic isolation channel obtained in process (1) includes a first isolation channel for electrostatic isolation between the spring beam and the inner frame and a second isolation channel for electrostatic isolation between the infrared FPA unit and the central platform; the second isolation channel is opened in the circumferential direction; and / or, the forming process of the infrared FPA unit is carried out between process (4) and process (5).

[0013] As a further improvement of the present invention, the forming process of the infrared FPA unit is as follows: In the middle of the central platform, a support layer of silicon nitride and a thermistor layer of vanadium oxide are deposited sequentially from bottom to top.

[0014] As a further improvement of the present invention, the infrared FPA unit is a prefabricated part, and the integration of the infrared FPA unit on the central platform is achieved by a packaging fixture; The packaging fixture includes a support boss, a receiving groove surrounding the outside of the support boss, and a limiting frame formed on the outer periphery of the receiving groove; wherein, the support boss is used to support the inner frame and the middle platform when setting the infrared FPA unit, and the receiving groove is used to support the outer frame.

[0015] As a further improvement of the present invention, the packaging fixture has a chip-taking notch with a connecting receiving groove on either side. and / or The height of the support boss above the bottom of the receiving groove is equal to the height of the inner frame relative to the outer frame after the release of the electrothermal drive unit in process (9).

[0016] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0017] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The infrared FPA-on-MEMS chip in this invention includes an infrared FPA unit and an electrothermal-electrostatic dual-drive module. By utilizing the combined design of the central platform, inner frame, outer frame, electrostatic drive unit and electrothermal drive unit in the electrothermal-electrostatic dual-drive module, and the integration of the infrared FPA unit on the central platform, the infrared FPA chip itself becomes an "adjustable" intelligent sensing unit. There is no need to set up separate optical and mechanical components for the infrared FPA chip. This improves the integration of the infrared thermal imaging system, reduces the system size, and ensures the accuracy of infrared thermal imaging control, thereby improving the overall performance of the infrared thermal imaging system.

[0018] (2) The method for fabricating the infrared FPA-on-MEMS chip of the present invention utilizes the design of the electrothermal-electrostatic dual-drive module fabrication process to accurately integrate electrostatic drive technology and electrothermal drive technology. Combined with the integration of the infrared FPA unit on the middle platform of the electrothermal-electrostatic dual-drive module, the coupling design of the infrared FPA unit and MEMS drive technology at the chip level can be realized, thereby enabling the infrared FPA unit at the chip level to have the ability of automatic displacement control. While ensuring that the infrared FPA unit achieves accurate planar displacement and vertical displacement, the setting of optical and mechanical components in the infrared thermal imaging system is avoided, thereby improving the system integration of the infrared thermal imaging system, reducing the system size, and improving the overall performance.

[0019] (3) The infrared FPA-on-MEMS technology of the present invention can realize the deep integration of infrared FPA and MEMS. By utilizing the miniaturization, low power consumption, high speed and high precision motion control characteristics of MEMS technology, it can effectively overcome the problems of large size, slow speed, high power consumption and system complexity caused by the reliance of traditional infrared imaging systems on external optical and mechanical components to achieve functions such as image stabilization, scanning and zooming. It can improve the integration and reliability of infrared thermal imaging systems, making the detector of the infrared thermal imaging system itself a "dynamic" intelligent sensing unit, breaking through the application bottleneck of infrared thermal imaging technology, greatly improving the system integration and comprehensive performance of infrared thermal imaging systems, and has excellent application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments 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.

[0021] Figure 1 This is a schematic diagram of the structure of the infrared FPA-on-MEMS chip in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the planar structure of the electrothermal-electrostatic dual-drive module obtained in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the process for fabricating an infrared FPA-on-MEMS chip in Embodiment 1 of the present invention; Figures 4-17 This is a schematic diagram illustrating the specific process of manufacturing the electrothermal-electrostatic dual-drive module in Embodiment 1 of the present invention; Figure 18 This is a schematic diagram of the packaging fixture structure used in the fabrication of the infrared FPA-on-MEMS chip in Embodiment 1 of the present invention; Figure 19 This is a schematic diagram of the process for fabricating an infrared FPA-on-MEMS chip in Embodiment 2 of the present invention; Figure 20 This is a schematic diagram of the infrared FPA-on-MEMS chip in Embodiment 2 of the present invention; In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 100. Infrared FPA unit; 200. Electrothermal-electrostatic dual-drive module; 1. Central platform; 2. Inner frame; 3. Outer frame; 4. Spring beam; 5. Electrostatic drive unit; 6. Electrothermal drive unit; 7. Packaging fixture; 8. Electrostatic isolation channel; 501. Moving comb teeth; 502. Fixed comb teeth; 601, First insulating layer; 602, Heating resistor; 603, Second insulating layer.

[0022] 701. Support boss; 702. Accommodating groove; 703. Sheet removal notch; 704. Limiting frame; 801, First isolation trench; 802, Second isolation trench. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] In the description of this invention, it should be understood that, unless otherwise expressly specified and limited, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0025] Furthermore, unless otherwise expressly defined, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] Terminology Explanation: Infrared FPA: Infrared Focal Plane Array; A focal plane detector has an array of photosensitive elements arranged on its focal plane. Infrared rays emitted from a distance are imaged onto the photosensitive elements on the focal plane of the system by the optical system. The detector converts the received light signals into electrical signals, integrates and amplifies them, samples and holds them, and finally sends them to the monitoring system to form an image through the output buffer and multiplexing system.

[0029] MEMS: Micro-Electro-Mechanical System; a miniaturized, intelligent, and integrated system that integrates microsensors, microactuators, microstructures, and signal processing circuits, fabricated on substrates such as silicon wafers, glass, or polymers using microfabrication processes. Its internal structure is generally at the micrometer or even nanometer scale, and it is an independent intelligent system.

[0030] Infrared FPA-on-MEMS: The entire infrared FPA is integrated into the MEMS actuator platform; the MEMS actuator platform completes the position control and attitude adjustment of the infrared FPA.

[0031] Bimorph: Bimorph Piezoelectric Element; a micro-mechanical-electronic composite structure composed of two layers of piezoelectric material (or piezoelectric material and non-piezoelectric material). It utilizes the inverse piezoelectric effect (electric field-induced mechanical deformation) to achieve "electromechanical" energy conversion and is a classic component in the fields of sensors and actuators and microelectromechanical systems (MEMS).

[0032] SOI wafer: Silicon-On-Insulator wafer; it is generally a three-layer structure (i.e., top silicon, middle insulating layer, and bottom silicon substrate), and the middle insulating layer is usually a SiO2 layer (thickness of 10nm~100nm). CMP: Chemical Mechanical Planarization; DRIE: Deep Reactive Ion Etching; RIE: Reactive Ion Etching; PECVD: Plasma Enhanced Chemical Vapor Deposition.

[0033] Below, for reference Figures 1-20 The infrared FPA-on-MEMS technology according to a preferred embodiment of the present invention is described.

[0034] The infrared FPA-on-MEMS technology in this invention aims to integrate infrared FPA and MEMS technologies to obtain an infrared FPA-on-MEMS chip. By utilizing the MEMS driving module, it achieves precise vertical displacement driving (corresponding to focusing, zooming, and other operations), deflection displacement driving (corresponding to optical image stabilization, electronic image stabilization, and other functions), and planar displacement driving (corresponding to field-of-view switching, micro-scanning, and other operations) of the infrared FPA unit 100. Simultaneously, the direct integration of the MEMS driving module and the infrared FPA avoids the need for traditional mechanical optical driving components, resulting in a self-active intelligent sensing unit. This breaks through the existing system architecture of imaging systems, reducing the size, response speed, system complexity, and power consumption of infrared imaging systems.

[0035] Specifically, as one aspect of the present invention, a preferred embodiment provides an infrared FPA-on-MEMS chip, such as... Figure 1 As shown, it includes an infrared FPA unit 100 and an electrothermal-electrostatic dual-drive module 200. Wherein: The electrothermal-electrostatic dual-drive module 200 includes a central platform 1, an inner frame 2, and an outer frame 3, such as Figure 2 As shown in the figure. The four corners of the central platform 1 are connected to the inner frame 2 by spring beams 4, and several electrostatic drive units 5 are provided between the outer periphery of the central platform 1 and the inner periphery of the inner frame 2; the inner frame 2 is located inside the outer frame 3, and several electrothermal drive units 6 are provided between the outer periphery of the inner frame 2 and the inner periphery of the outer frame 3.

[0036] Meanwhile, the infrared FPA unit 100 is mounted on the central platform 1 and can be adjusted in position to follow the movement of the central platform 1.

[0037] On the infrared FPA-on-MEMS chip, the planar displacement of the central platform 1 can be adjusted by the electrostatic driving units 5 around the inner side of the inner frame 2, thereby completing the planar displacement control of the infrared FPA unit 100. Furthermore, the electrothermal driving units 6 around the outer side of the inner frame 2 enable the inner frame 2 and its mounted central platform 1 and infrared FPA unit 100 to complete vertical displacement adjustment or deflection displacement adjustment under the drive of the electrothermal driving units 6, thereby completing the vertical displacement control (simultaneous control of the four electrothermal driving units 6) or deflection displacement control (simultaneous control of the two electrothermal driving units 6).

[0038] More specifically, in the preferred embodiment, the electrostatic drive unit 5 includes movable comb teeth 501 and fixed comb teeth 502. The movable comb teeth 501 are disposed on the outer periphery of the central platform 1, and the fixed comb teeth 502 are disposed on the inner periphery of the inner frame 2. The movable comb teeth 501 and the fixed comb teeth 502 are alternately arranged on each side of the central platform 1.

[0039] Furthermore, in the preferred embodiment, the electrothermal drive unit 6 preferably has a multi-layer structure in the thickness direction, including a heating resistance layer and electrothermal deformation layers with different coefficients of thermal expansion. Simultaneously, the electrothermal drive unit 6 includes a first fixing plate connected to the outer periphery of the inner frame and a second fixing plate connected to the inner side of the outer frame, with at least one transition plate disposed between the two fixing plates. Each transition plate has a bent portion at both ends, and the two fixing plates are connected to the transition plate through the bent portions. Then, by electrothermal heating of the heating resistance layer after energization, each electrothermal deformation layer undergoes corresponding deformation, causing the bent portion of the electrothermal drive unit 6 to bend, resulting in a vertical displacement of the first fixing plate relative to the second fixing plate. This completes the vertical displacement drive of the infrared FPA unit 100, completing the focusing and adjustment process of the infrared FPA unit 100.

[0040] Furthermore, to ensure the accuracy of directional control of the electrothermal-electrostatic dual-drive module 200, in actual installation, the electrothermal drive units 6 and / or the electrostatic drive units 5, which are opposite to each other on both sides of the inner frame 2, are symmetrically arranged relative to the centerline of the inner frame 2. For example, on the inner side of the inner frame 2, the number and arrangement of the comb-tooth structures opposite to each other are symmetrical. As another example, on the outer side of the inner frame 2, the number of electrothermal drive units 6 opposite to each other is the same. Through the above arrangement, it is ensured that the displacement stroke on each side of the central platform 1 remains consistent during planar or vertical displacement, avoiding the introduction of deflection errors during the displacement of the central platform 1.

[0041] By transferring dynamic functions such as image stabilization and scanning from the bulky lens assembly to the miniaturized detector chip, the optical system structure is greatly simplified, achieving an ultra-compact design. This also enables a single chip to switch between multiple modes, including image stabilization, micro-scanning, and field-of-view control, greatly improving the adaptability and intelligence of the imaging system.

[0042] Furthermore, as another aspect of the present invention, a method for fabricating the aforementioned infrared FPA-on-MEMS chip is also provided. The fabrication method mainly includes the fabrication process of the electrothermal-electrostatic dual-drive module 200, the fabrication process of the infrared FPA unit 100, and the coupling and integration process of the infrared FPA unit 100 on the electrothermal-electrostatic dual-drive module 200.

[0043] In actual manufacturing, the infrared FPA unit 100 and the electrothermal-electrostatic dual-drive module 200 can be fabricated separately, or the fabrication process of the infrared FPA unit 100 can be integrated into the fabrication process of the electrothermal-electrostatic dual-drive module 200. For the former, the fabrication of the electrothermal-electrostatic dual-drive module 200 does not require consideration of the infrared FPA unit 100, making its fabrication process relatively simpler. In this case, the infrared FPA unit 100 can be considered a prefabricated component, and only its final integration process on the central platform 1 needs to be considered. For the latter, the infrared FPA unit 100 is fabricated simultaneously during the fabrication process of the electrothermal-electrostatic dual-drive module 200, requiring only one tape-out process. This simplifies the fabrication process of the infrared FPA-on-MEMS chip to some extent, shortens the manufacturing cycle, and improves chip fabrication efficiency. Both methods have their advantages and disadvantages; the appropriate fabrication process can be selected according to the needs when actually fabricating the infrared FPA-on-MEMS chip.

[0044] The following two examples illustrate the two molding methods.

[0045] Example 1: In this embodiment, the infrared FPA unit 100 is a prefabricated component, which is integrated and set on the central platform 1 after the electrothermal-electrostatic dual-drive module 200 is manufactured.

[0046] Meanwhile, the manufacturing process of the electrothermal-electrostatic dual-drive module 200 in the preferred embodiment is referenced. Figure 3 As shown, the preferred process includes the following: (1) Prepare a wafer and etch an electrostatic isolation channel 8, and fill the electrostatic isolation channel 8 with insulating material and cure it.

[0047] Specifically, in actual setup, the wafer type in the preferred embodiment can be selected according to requirements. It can be a pure silicon wafer (e.g., a single-crystal silicon wafer) or an SOI wafer. SOI wafers, because they have a buried oxide layer in the middle, allow the etching process to automatically stop upon reaching the buried oxide layer when etching silicon on the back side of the wafer. Similarly, when etching the buried oxide layer, the etching process will automatically stop upon reaching the surface silicon layer. This simplifies the control of the etching process on the back side of the wafer. For pure silicon wafers, since they lack a central buried oxide layer, etching time needs to be calculated based on etching rate and thickness, while retaining a certain amount of silicon to ensure structural rigidity. Therefore, the process control is relatively more stringent. However, pure silicon wafers do not require separate etching of the buried oxide layer, saving an etching step and further shortening the chip manufacturing cycle.

[0048] Furthermore, in the preferred embodiment, the electrostatic isolation channel 8 is located between the central platform 1 and the inner frame 2 (equivalent to between the moving comb tooth 501 and the fixed comb tooth 502), i.e., the first isolation channel 801, and the number and position of the first isolation channel 801 are directly related to the design number and position of the spring beam 4.

[0049] For example, in such Figure 1 , Figure 2 In the preferred embodiment shown, spring beams 4 are provided at the four corners between the central platform 1 and the inner frame 2. In this case, the electrostatic isolation channels 8 are preferably four first isolation channels 801 located at the four corners of the inner side of the inner frame 2.

[0050] More specifically, in the preferred embodiment, the insulating material filled in the electrostatic isolation channel 8 is BCB resin. Furthermore, after the insulating material is filled, a chemical mechanical polishing process is preferably performed to remove excess insulating material from the wafer surface.

[0051] (2) Fabricate a first insulating layer 601 for forming an electrothermal drive comb mask.

[0052] (3) A heating resistor 602 is deposited and stripped on the first insulating layer 601 to form the electrothermal drive unit 6.

[0053] In actual setup, the material of the heating resistor 602 can be determined according to the needs. For example, the heating resistor 602 can be a deposited platinum layer, tungsten layer, polycrystalline silicon layer or nickel-chromium alloy layer.

[0054] In this preferred embodiment, the heating resistor 602 is preferably a platinum layer due to its high patterning precision and good chemical stability. Furthermore, different processes can be selected to fabricate the heating resistor 602 depending on the material. For example, if uniformity after film formation is required, magnetron sputtering can be used to fabricate the platinum layer; if rapid film formation is required, electron beam evaporation / thermal evaporation can be used.

[0055] (4) Make a second insulating layer 603 on the heating resistor 602 and open the connection through hole.

[0056] Specifically, in the preferred embodiment, the insulating layers (i.e., the first insulating layer 601 and / or the second insulating layer 603) are preferably SiO2 layers. Meanwhile, the thicknesses of the two insulating layers can be designed according to the requirements of the product design.

[0057] (5) Fabricate the Bimorph part, on-chip traces and pads of the electrothermal drive unit 6.

[0058] In practical applications, it is preferable to use ion beam evaporation to fabricate the metal layer and then peel it off to form the electrically driven Bimorph portion, on-chip traces, and pads. If a mirror surface is required on the central platform 1, it can also be formed simultaneously during the metal layer peeling process.

[0059] Meanwhile, in the preferred embodiment, the metal layer is preferably an Al layer, an Au layer, or a Cu layer. Different molding processes can be selected depending on the molding material, such as deposition by magnetron sputtering or ion beam evaporation, and patterning is achieved by stripping.

[0060] (6) Etch the front structure of the wafer to obtain the comb teeth (i.e., moving comb teeth 501 and fixed comb teeth 502), spring beam 4 and central platform 1 of the electrostatic drive unit 5.

[0061] Since a first insulating layer 601 (i.e., a comb mask) is provided for the comb teeth of the electrostatic drive unit 5 in process (2), the design area of ​​each comb tooth can be accurately protected from being etched away during the front etching process of the wafer, and thus the two comb teeth of the electrostatic drive unit 5 can be fabricated through etching.

[0062] Meanwhile, for SOI wafers, based on the presence of the buried oxide layer, the surface silicon layer can be directly etched. The etching operation will automatically stop after reaching the buried oxide layer, thereby obtaining the spring beam 4 and the central platform 1, and separating the design areas of the inner frame 2 and the outer frame 3.

[0063] Furthermore, it is understandable that before etching the front side of the wafer, the structure fabricated on the front side needs to be protected by a mask. For example, patterned photoresist can be used to protect the corresponding structures / parts (such as the central platform 1 and the comb teeth). This can be achieved using existing technology and will not be elaborated here. After the front side etching is completed, the aforementioned mask protection can be removed using appropriate processes, or the mask can be designed so that the mask protection layer is simultaneously etched away during the front side etching process.

[0064] (7) Fill the comb tooth area of ​​the electrostatic drive unit 5 with photoresist, and make the photoresist fill the gap between each comb tooth.

[0065] By filling the comb tooth area with photoresist, the silicon in the comb tooth part is prevented from being reacted by the subsequent etching gas, thus providing sufficient protection for the comb teeth of the electrostatic drive unit 5.

[0066] In actual setup, it is preferable to apply photoresist to the front side of the wafer and fill the gap between the comb teeth by vacuuming; then, remove the excess photoresist by photolithography and finally retain the photoresist in the comb tooth area and the central platform 1 area.

[0067] (8) Apply adhesive, perform photolithography patterning and deep silicon etching on the back side of the wafer to remove excess back side portion of the wafer.

[0068] The preferred etching process on the back side of the wafer differs depending on the type of wafer. Taking SOI wafers as an example, it is preferable to undergo two etching processes, etching away the bottom silicon layer and the middle buried oxide layer, respectively. For pure silicon wafers, it is preferable to undergo one etching process, and the etching rate and depth need to be controlled to ensure that the electrothermal-electrostatic dual-drive module 200 has sufficient thickness after etching, thereby providing the corresponding structural strength.

[0069] (9) Release the electrothermal drive unit 6 and remove the photoresist on the front side of the wafer to obtain the electrothermal-electrostatic dual drive module 200.

[0070] During this process, by removing the residual silicon layer at the bottom of the electrothermal drive unit 6 at specific points, the Bimorph part of the electrothermal drive unit 6 can bend under the action of internal residual stress, so that the inner frame 2 and the middle area supported by the inner frame 2 can be lifted synchronously.

[0071] Accordingly, by removing the photoresist on the front side of the wafer (used as comb protection), the electrostatic drive unit 5 can be released, ultimately resulting in the electrothermal-electrostatic dual drive module 200.

[0072] Preferably, during the above process, a laser dicing process with chips is further preferred, and the complete wafer is divided into individual chips according to the distribution of each electrothermal-electrostatic dual-drive module.

[0073] Furthermore, after completing the fabrication of the electrothermal-electrostatic dual-drive module 200, an infrared FPA unit 100 is coupled and integrated onto the electrothermal-electrostatic dual-drive module 200. That is: (10) An infrared FPA unit 100 is set on the middle platform 1 of the electrothermal-electrostatic dual drive module 200 to obtain an infrared FPA-on-MEMS chip.

[0074] Specifically, when setting up the infrared FPA unit 100, it is preferable to fix it to the central platform 1 using adhesive. Simultaneously, when packaging and integrating the infrared FPA unit 100, it is preferable to configure the wiring of each pin on the infrared FPA unit 100, which can be accomplished using existing technology and will not be elaborated here. Furthermore, the infrared FPA unit 100 in this embodiment is preferably a ready-made product obtained through existing molding processes; the specific molding process is not the focus of this invention and will not be elaborated here.

[0075] More preferably, to facilitate the integration of the infrared FPA unit 100 on the central platform 1, the preferred embodiment further incorporates features such as... Figure 18The packaging fixture shown in 7.

[0076] Specifically, in the preferred embodiment, the packaging fixture 7 has a plate-like structure, which can be regarded as being obtained by opening a square annular groove on a plate with a certain thickness. The top surface of the plate has a square annular groove, namely a receiving groove 702, and a support boss 701 protruding from the bottom of the receiving groove 702 is formed in the middle, and a limiting frame 704 is formed on the outer periphery.

[0077] Using the above-described configuration of the packaging fixture 7, the electrothermal-electrostatic dual-drive module 200 manufactured through processes (1) to (9) can be placed in the packaging fixture 7. At this time, the inner frame 2 and the middle platform 1 of the electrothermal-electrostatic dual-drive module 200 can be supported on the support boss 701, while the outer frame 3 can be supported in the receiving groove 702, and the electrothermal drive unit 6 is suspended above the bottom of the receiving groove 702. Subsequently, the infrared FPA unit 100 is fixed to the middle platform 1, and the signal is led to the pad on the inner frame 2 through wire bonding. Then, the signal is led to the outer frame 3 through the A1 wire integrated on the electrothermal drive unit 6, and finally connected to the peripheral reading circuit, thereby realizing the outward transmission of the infrared image signal.

[0078] Based on the design of the packaging fixture 7, each part of the electrothermal-electrostatic dual-drive module 200 can be reliably supported during the integration and setting of the infrared FPA unit 100 and the central platform 1, thus avoiding damage to the electrothermal-electrostatic dual-drive module 200 of the chip during the setting of the infrared FPA unit 100.

[0079] More specifically, in the preferred embodiment, the height of the support boss 701 above the bottom of the receiving groove 702 is preferably matched with the height of the middle platform 1 of the chip obtained in process (9) above the outer frame 3, that is, the height of the support boss 701 is just matched with the height of the middle part of the electric heating drive unit 6 after it is released from the silicon wafer constraint.

[0080] More preferably, a chip removal notch 703 communicating with the receiving groove 702 is provided on either side of the packaging fixture 7, for removing the infrared FPA-on-MEMS chip from the packaging fixture 7 after the fabrication of the chip is completed. For example, the two chip removal notches 703 are used to clamp the two sides of the outer frame 3 or to lift the bottom of the two sides of the outer frame 3, thereby removing the chip from the fixture.

[0081] As an example, the notch 703 is located in a diagonal region on opposite sides of the fixture, such as... Figure 18 As shown in the diagram. At this time, the line connecting the centers of the two notches 703 preferably passes through the center of the support boss 701.

[0082] Through the above-mentioned work process and the design of corresponding fixtures, the electrothermal-electrostatic dual-drive module 200 can be accurately manufactured and the infrared FPA unit 100 can be set on the central platform 1, thereby obtaining the infrared FPA-on-MEMS chip.

[0083] Example 2: In this embodiment, the biggest difference from embodiment 1 is that the molding process of the infrared FPA unit 100 is integrated with the molding process of the electrothermal-electrostatic dual-drive module 200. In this case, the fabrication of the infrared FPA-on-MEMS chip can be completed in only one fabrication process.

[0084] Specifically, the molding process of the electrothermal-electrostatic dual-drive module 200 in this embodiment refers to... Figure 19 As shown, its preferred method is largely the same as the process (1) to (9) in Example 1, with the only difference being: First, in process (1), when setting the electrostatic isolation channel 8, in addition to setting the first isolation channel 801, a second annular isolation channel 802 is also opened in the circumferential direction for the infrared FPA unit 100 in the setting area of ​​the central platform 1, such as... Figure 20 As shown in the diagram. Accordingly, insulating material is also filled and cured in the second isolation channel 802 to achieve electrostatic isolation between the subsequent infrared FPA unit 100 and the outer edge region of the central platform 1.

[0085] Simultaneously, between process (4) and process (5), an infrared FPA unit 100 deposition process is also performed, namely, the silicon nitride support layer and the vanadium oxide thermistor layer are deposited sequentially from bottom to top, finally obtaining the infrared FPA unit 100. At this time, the preferred fabrication process of the infrared FPA-on-MEMS chip is as follows: Figure 19 As shown, after the front photoresist removal process in process (9) (i.e., process (p)) is completed, an infrared FPA-on-MEMS chip can be obtained.

[0086] It is understandable that, in actual operation, the timing of the production of the infrared FPA unit 100 can be adjusted according to actual needs, as long as it is ensured that the infrared FPA unit 100 after production can be fully protected, and the production process of the infrared FPA unit 100 does not affect the production process of the electrothermal-electrostatic dual drive module 200.

[0087] By coupling and integrating the fabrication process of the infrared FPA unit 100 with the fabrication process of the electrothermal-electrostatic dual-drive module 200, the fabrication process of the infrared FPA-on-MEMS chip can be further simplified and the chip fabrication efficiency can be improved.

[0088] Obviously, in actual operation, the manufacturing method of the two aforementioned embodiments can be selected as needed.

[0089] The following is a specific embodiment to illustrate the aforementioned manufacturing process. In this embodiment, the specific manufacturing method of the infrared FPA-on-MEMS chip preferably includes the manufacturing process of the electrothermal-electrostatic dual-drive module 200 and the integration process of the infrared FPA unit 100 on the electrothermal-electrostatic dual-drive module 200, which corresponds to the manufacturing process in Embodiment 1.

[0090] Specifically, such as Figures 4-17 As shown, i.e. Figure 3 In processes (a) to (n), the preferred manufacturing process of the electrothermal-electrostatic dual-drive module 200 in the preferred embodiment is as follows: (a) such as Figure 4 As shown, an SOI wafer (20μm / 1μm / 400μm) is prepared; wherein, the SOI wafer includes pure silicon layers on the top and bottom sides and a buried oxide layer (i.e., SiO2 layer) located between the two silicon layers.

[0091] (b) such as Figure 5 As shown, according to the design position and size of the central platform 1, the electrostatic isolation channel 8 is etched using the DRIE process, and the electrostatic isolation channel 8 is used to achieve electrical insulation between the moving comb tooth 501 and the fixed comb tooth 502. (c~d) such as Figure 6 As shown, the electrostatic isolation channel 8 is filled with BCB resin (benzocyclobutene resin) and cured; subsequently, excess BCB resin on the SOI wafer surface is removed using a CMP process, resulting in the following form. Figure 7 As shown in the image.

[0092] (e) A 1 μm thick SiO2 layer is deposited on the wafer surface using PECVD, and a first insulating layer 601 for electrothermal drive, comb mask, and electrostatic drive signal transmission is formed using RIE. Figure 8 As shown in the image.

[0093] (f) A 150 nm thick Pt layer is deposited on the first insulating layer 601 using a magnetron sputtering process, and the heating resistor 602 forming the electrothermal drive unit 6 is stripped off, as shown in the figure. Figure 9 As shown in the image.

[0094] (g~h) A 200nm thick SiO2 layer was deposited using PECVD process, such as Figure 10 As shown in the diagram; subsequently, etching is performed using a RIE process to open the connection vias, and a second insulating layer 603 is formed on the heating resistor 602, as shown in the diagram. Figure 11 As shown in the image.

[0095] (i) A 1 μm thick Al layer was prepared using ion beam evaporation, and the Bimorph portion for electrothermal drive, as well as on-chip traces, pads, and mirrors, were stripped off, as shown below. Figure 12 As shown in the image.

[0096] (j) The front side of the SOI wafer is etched using the DRIE process, specifically etching away the surface silicon layer in the corresponding area of ​​the SOI wafer to form a structure as shown in the image. Figure 13 The front structure shown.

[0097] (k) Photoresist is applied to the front side of the SOI wafer by rotation, and preferably by vacuuming to fill the gaps with photoresist, retaining the photoresist in the comb area of ​​the electrostatic drive unit 5 and the central platform 1 area, and removing the photoresist in other areas by photolithography, such as... Figure 14 As shown in the diagram. This arrangement allows the structure of the electrostatic drive unit 5 and the central platform 1 area to be protected by photoresist, preventing the silicon in this area from being reacted away by the etching gas.

[0098] (l) On the back side of the SOI wafer, processes such as resist coating, photolithography patterning, and deep silicon etching are performed. The pure silicon layer on the back side of the SOI wafer is etched away sequentially using the DRIE process, and the buried oxide layer in the middle of the SOI wafer is etched away using the RIE process. Figure 15 As shown in the image.

[0099] (m) The SOI wafer is placed in a xenon fluoride etching apparatus, and the electrothermal drive unit 6 is released from the front side of the wafer, freeing it from the constraint of the wafer silicon on the electrothermal drive unit 6 (the Bimorph portion). This allows the electrothermal drive unit 6 to be lifted upwards under the action of internal residual stress, as shown below. Figure 16 As shown in the image.

[0100] More preferably, in the above process, a laser scribing operation is further performed to divide the SOI wafer into individual chip structures.

[0101] (n) such as Figure 17 As shown in the diagram, the chip is placed in a plasma etching apparatus, and the photoresist in the central region of the chip is removed by bombardment with oxygen plasma, thereby obtaining an electrothermal-electrostatic dual-drive module 200 integrating an electrothermal drive unit 6 and an electrostatic drive unit 5, the structure of which is as follows. Figure 2 As shown in the image.

[0102] Furthermore, after completing the fabrication of the electrothermal-electrostatic dual-drive module 200 through the above process, an integration and setup process is also performed on the infrared FPA unit 100 on the electrothermal-electrostatic dual-drive module 200. The details are as follows: (o) Obtain the fabricated infrared FPA unit 100 and package and integrate it onto the central platform 1 to finally obtain an infrared FPA-on-MEMS chip, such as... Figure 1 As shown in the image.

[0103] The infrared FPA-on-MEMS technology of this invention is simple in procedure and convenient in operation. It can achieve the integrated coupling of infrared FPA technology and MEMS technology to obtain a detector unit with automatic displacement adjustment function. Without using traditional external optical and mechanical components, it can accurately complete the displacement control of the infrared FPA unit, realize the image stabilization, scanning and zoom functions of the infrared FPA unit, and avoid the problems of large size, slow speed, high power consumption and system complexity caused by the increase of functions in infrared imaging systems. It realizes the multi-functional integration of infrared imaging systems and has excellent application prospects.

[0104] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An infrared FPA-on-MEMS chip, characterized in that, Includes an infrared FPA unit and an electrothermal-electrostatic dual-drive module; The electrothermal-electrostatic dual-drive module includes a central platform, an inner frame, and an outer frame; wherein: The four corners of the central platform are connected to the inner frame via spring beams, and several electrostatic drive units are provided between each side of the outer periphery of the central platform and the inner periphery of the inner frame. The inner frame is located inside the outer frame, and several electrothermal drive units are provided between each side of the outer periphery of the inner frame and the inner periphery of the outer frame. The infrared FPA unit is located on the central platform.

2. A method for fabricating an infrared FPA-on-MEMS chip, characterized in that, The infrared FPA-on-MEMS chip includes an infrared FPA unit and an electrothermal-electrostatic dual-drive module; wherein: The electrothermal-electrostatic dual-drive module includes a central platform, an inner frame, and an outer frame. The four corners of the central platform are connected to the inner frame via spring beams, and several electrostatic drive units are arranged between the outer periphery of the central platform and the inner periphery of the inner frame. The inner frame is located inside the outer frame, and several electrothermal drive units are arranged between the outer periphery of the inner frame and the inner periphery of the outer frame. The manufacturing process of the electrothermal-electrostatic dual-drive module is as follows: (1) Prepare the wafer and etch the electrostatic isolation channel, and fill the electrostatic isolation channel with insulating material and cure it; (2) Fabricate a first insulating layer for forming an electrothermal drive, comb tooth mask; (3) Deposit and strip the heating resistor forming the electrothermal drive unit on the first insulating layer; (4) Make a second insulating layer on the heating resistor and open the connection through hole; (5) Fabricate the Bimorph part of the electrothermal drive unit, the on-chip traces and pads; (6) Etch the front structure of the wafer to obtain the comb teeth, spring beam and central platform of the electrostatic drive unit; (7) Fill the comb tooth area of ​​the electrostatic drive unit with photoresist, and make the photoresist fill the gap between each comb tooth; (8) Apply adhesive, perform photolithography patterning, and deep silicon etching on the back side of the wafer to remove excess back side portion of the wafer; (9) Release the electrothermal drive unit, remove the photoresist on the front side of the wafer, and obtain the electrothermal-electrostatic dual drive module; The infrared FPA unit is set on the central platform; and the infrared FPA unit is fabricated in layers on the central platform during the manufacturing process of the electrothermal-electrostatic dual-drive module; or, the infrared FPA unit is a prefabricated part, which is set on the central platform after the process (9) is completed.

3. The method for fabricating an infrared FPA-on-MEMS chip according to claim 2, characterized in that, In process (1), the insulating material filled in the electrostatic isolation channel is BCB resin; and / or In process (1), after the insulating material is filled, a chemical mechanical polishing process is also performed to remove excess insulating material from the wafer surface; and / or In process (1), the wafer is an SOI wafer or a pure silicon wafer.

4. The method for fabricating an infrared FPA-on-MEMS chip according to claim 2, characterized in that, In process (3), the heating resistance is a platinum layer, tungsten layer, polycrystalline silicon layer or nickel-chromium alloy layer deposited; and / or The first insulating layer and / or the second insulating layer are SiO2 layers prepared by deposition.

5. The method for fabricating an infrared FPA-on-MEMS chip according to claim 2, characterized in that, In process (5), a metal layer is deposited and stripped to form the electrically heated Bimorph portion, on-chip traces, and pads; and The metal layer is an Al layer, an Au layer, or a Cu layer.

6. The method for fabricating an infrared FPA-on-MEMS chip according to any one of claims 2 to 5, characterized in that, In process (9), a laser scribing process is also performed, and the wafer is divided into individual chips according to the distribution of each electrothermal-electrostatic dual-drive module.

7. The method for fabricating an infrared FPA-on-MEMS chip according to any one of claims 2 to 5, characterized in that, The infrared FPA unit is fabricated in layers on the central platform during the manufacturing process of the electrothermal-electrostatic dual-drive module; and The electrostatic isolation channel obtained in process (1) includes a first isolation channel for electrostatic isolation between the spring beam and the inner frame and a second isolation channel for electrostatic isolation between the infrared FPA unit and the central platform. The second isolation channel is opened circumferentially; and / or, the forming process of the infrared FPA unit is carried out between process (4) and process (5).

8. The method for fabricating an infrared FPA-on-MEMS chip according to claim 7, characterized in that, The forming process of the infrared FPA unit is as follows: In the middle of the central platform, a support layer of silicon nitride and a thermistor layer of vanadium oxide are deposited sequentially from bottom to top.

9. The method for fabricating an infrared FPA-on-MEMS chip according to any one of claims 2 to 5, characterized in that, The infrared FPA unit is a prefabricated component, and the integration of the infrared FPA unit on the central platform is achieved through a packaging fixture; The packaging fixture includes a support boss, a receiving groove surrounding the outside of the support boss, and a limiting frame formed on the outer periphery of the receiving groove; wherein, the support boss is used to support the inner frame and the middle platform when setting the infrared FPA unit, and the receiving groove is used to support the outer frame.

10. The method for fabricating an infrared FPA-on-MEMS chip according to claim 9, characterized in that, The packaging fixture has a wafer-taking notch on either side that connects to the receiving groove; and / or The height of the support boss above the bottom of the receiving groove is equal to the height of the inner frame relative to the outer frame after the release of the electrothermal drive unit in process (9).

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