In-plane three-axis large-displacement actuating platform based on MEMS and manufacturing method of in-plane three-axis large-displacement actuating platform

Abstract

The invention discloses an in-plane three-axis large-displacement actuating platform based on MEMS and a manufacturing method thereof.The in-plane three-axis large-displacement actuating platform mainly comprises an outer frame, a cross island frame, a bidirectional comb-shaped driving unit, a long spring beam and a short spring beam, and the manufacturing method comprises the steps that a cavity structure on a glass substrate is anisotropically etched through magnetic neutral loop discharge plasma (NLD); the method comprises the following steps of: bonding a BF33 glass wafer with a cavity structure with a low-resistance silicon wafer by using an anodic bonding process, thinning the low-resistance silicon wafer, performing deep silicon etching (DRIE) on the low-resistance silicon wafer to form an electrical isolation channel and filling a BCB material, removing the BCB on the surface of the low-resistance silicon wafer by using a chemical mechanical polishing (CMP) process, sputtering a metal layer and forming a lead layer by using a lift-off process, and performing deep silicon etching (DRIE) on the low-resistance silicon wafer to form a final device. The method has the beneficial effects that the filling rate of the device is improved, the size is reduced, the structural rigidity, the response speed, the resonant frequency and the heat dissipation performance are improved, and meanwhile, a routing method for heterogeneously integrating the micro-motion platform and the CMOS chip is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-electromechanical systems (MEMS), and in particular relates to an in-plane three-axis large-displacement actuation platform based on MEMS and a manufacturing method thereof. Background Art

[0002] Image stabilization (IS) is a key technology to improve image quality, which is mainly divided into two categories: software-based image stabilization and hardware-based image stabilization. Software-based image stabilization includes digital image stabilization (DIS) and electronic image stabilization (EIS), which process image data through software algorithms to reduce image blur caused by camera shake or hand tremors. Specifically, digital image stabilization (DIS) technology relies on image post-processing algorithms to correct jitters, and corrects the jitter of captured images by analyzing the movement between image frames, focusing on optimization after shooting; while electronic image stabilization (EIS) technology performs real-time image stabilization during shooting. It needs to combine the built-in sensors of the mobile phone (such as accelerometers and gyroscopes) to obtain real-time dynamic data of the device, and use software algorithms to process images, including adjusting image frames, cropping, alignment and synthesis, etc., to reduce jitter and improve image quality. Hardware-based image stabilization includes optical image stabilization (OIS) and mechanical image stabilization. OIS uses accelerometers and gyroscopes to obtain device motion information in real time and accurately adjust the position of the lens or sensor to compensate for camera shake; while mechanical image stabilization uses external devices (such as a gimbal) to physically stabilize the device, further reducing shake during shooting and ensuring a more stable imaging effect.

[0003] Micro-electromechanical systems (MEMS) is a technology that combines electronic components with moving parts. It uses micro-machining technology to manufacture micro-scale mechanical and electronic structures, so that the equipment used in MEMS can achieve complex functions while achieving miniaturization. MEMS-based actuators have gradually been used in smartphone camera anti-shake. The invention patent application with application number 2016106283145 and the name of multi-directional actuator discloses a MEMS multi-directional actuator, which consists of two inner and outer frames and a bidirectional comb drive unit. The comb drive actuator drives the inner frame to move relative to the outer frame in the X and Y axes and rotate around the Z axis, with three degrees of freedom. At present, the technology of inner frame, outer frame and bidirectional comb drive unit has been widely used in the field of camera anti-shake, especially in the camera modules of high-end smartphones. In the actual application process, it was found that there are still some technical problems in the structure of the inner and outer frames, which need to be improved.

[0004] 1. Limited miniaturization. A separate moving frame structure usually requires a larger gap between the moving frame and the drive platform to accommodate the long spring beam. Since the long spring beam is longer (usually 1 to 1.5 times the current design), this means that the moving frame structure will occupy a larger space in size, thus limiting the miniaturization of the overall system.

[0005] 2. Low response speed and resonant frequency. The long spring beam structurally reduces the stiffness of the system, resulting in a decrease in the resonant frequency. The long beam deforms greatly when subjected to force and rebounds slowly, resulting in a decrease in the response speed of the system and an inability to quickly respond to external control signals. Summary of the invention

[0006] In view of the technical problems existing in the inner and outer double-frame structure of the current MEMS actuator, an in-plane three-axis large-displacement actuation platform based on MEMS and a manufacturing method thereof are provided.

[0007] The present invention is achieved through the following technical solutions: An in-plane three-axis large-displacement actuation platform based on MEMS: comprising an outer frame, a cross-island frame, a bidirectional comb-shaped drive unit, a long spring beam and a short spring beam; The outer frame includes a cavity for accommodating the cross island frame and a cavity for accommodating the bidirectional comb drive unit; The cross island frame includes a cross and cross bars, wherein four cross bars are respectively arranged at the outer ends of the cross; The bidirectional comb drive unit is composed of a stator and a mover, wherein the stator is provided with an open slot, the left side of the open slot is provided with a first left comb-shaped array, and the right side is provided with a first right comb-shaped array, and the mover is provided with a rectangular protrusion block, the left side of the rectangular protrusion block is provided with a second left comb-shaped array, and the right side is provided with a second right comb-shaped array, the rectangular protrusion block is inserted into the middle of the open slot, the first left comb-shaped array and the second left comb-shaped array are interlaced with each other and there is a gap, and the first right comb-shaped array and the second right comb-shaped array are interlaced with each other and there is a gap; One end of the short spring beam is connected to the mover and the other end is connected to the stator; One end of the long spring beam is connected to the mover, and the other end is connected to the cross island frame; There are four bidirectional comb drive units, which are respectively located in the four quadrants of the cross island frame. Each bidirectional comb drive unit is connected to the cross island frame through a long spring beam. Each adjacent two of the four bidirectional comb drive units are arranged at a difference of 90 degrees.

[0008] Among them, the MEMS-based in-plane three-axis large-displacement actuation platform: the middle part of the rectangular protrusion block is provided with protruding extension parts on the left and right sides to form a limit block, a limit groove is formed in the middle of the opening groove, and the limit block is located in the limit groove.

[0009] Among them, the MEMS-based in-plane three-axis large-displacement actuation platform: the open slots on the stator and the rectangular protrusions on the mover correspond one to one, two are a pair, there are three open slots on the stator, and correspondingly, there are three rectangular protrusions on the mover, and each open slot and rectangular protrusion block has a matching comb-shaped array.

[0010] A method for manufacturing an in-plane three-axis large displacement actuation platform based on MEMS, wherein the in-plane three-axis large displacement actuation platform based on MEMS comprises an outer frame, a cross island frame, a bidirectional comb drive unit, a long spring beam and a short spring beam, and comprises the following steps: Step 1: Etching of glass substrate; A piece of BF33 glass is organically cleaned and then spin-coated with photoresist, which is then photolithographically processed in a photolithography machine through a mask; Step 2: using magnetic neutral loop discharge plasma (NLD) anisotropic etching technology to etch out the cavity structure, and wet remove the photoresist; Step 3: Bond the side of the BF33 glass wafer with the cavity structure to the low-resistance silicon wafer using an anodic bonding process; Step 4: Use a thinning machine to thin the low-resistance silicon wafer surface of the bonding sheet; Step 5: Deep silicon etching an electrical isolation channel on the low-resistance silicon, cutting the stator from the low-resistance silicon to form an independent part, and then cutting the left comb-shaped array and the right comb-shaped array of the stator into two independent parts to achieve electrical isolation between the two, and then etching the electrical isolation channel at a set position, and the electrical isolation channel at the lower position of the left comb-shaped array and the right comb-shaped array is U-shaped; Step 6: Filling the BCB material in the electrical isolation trench, bonding the cut and separated left comb array and right comb array into a whole, and then bonding the right comb array and low-resistance silicon into a whole, vacuum pumping BCB liquid into the isolation trench of the removed low-resistance silicon as an insulating layer, and curing the BCB material at high temperature, removing the BCB on the surface of the low-resistance silicon through the chemical mechanical polishing (CMP) process, and only retaining the BCB material in the trench; Step 7: Depositing a PECVD oxide layer on the low-resistance silicon, one comb array on the left and one comb array on the right; Step 8: Sputter the metal layer and use the lift-off process to make the metal conductor layer, which is used to lay three circuits, one stator left comb array, one stator right comb array and one mover comb array. The metal layers of the stator left comb array and the right comb array are laid on the insulating layer PECVD oxide layer. The mover comb array is integrated with the entire low-resistance silicon, and the circuit is directly led out on the low-resistance silicon. Step nine: deep silicon etching process etches low-resistance silicon. First, spin-coat photoresist, and then photolithography is performed in a photolithography machine through a mask. Deep silicon etches low-resistance silicon and simultaneously etches out a cross island frame, a bidirectional comb drive unit, a long spring beam, a short spring beam, and several process beams. One end of the process beam is connected to the cross island frame, and the other end is connected to the outer frame.

[0011] Beneficial effects of the present invention: 1. Through the compact drive unit layout, the cross island frame is surrounded by four drive units, which improves the platform filling rate, reduces the size of the device, makes it easier to miniaturize, and is suitable for high-integration microelectronic equipment applications; 2. The cross-island frame design replaces the inner frame structure, effectively shortens the length of the spring beam, and improves the stiffness and response speed of the device. At the same time, it increases the resonance frequency, improves the imaging quality of the device under high-frequency jitter, and better applies image stabilization technology. 3. Through the design of the process beam, not only can the heat dissipation performance of the device in the deep silicon etching (DRIE) process be improved, the device etching yield rate can be improved, but also the structural strength of the device during transportation can be enhanced. In addition, when the device is wire-bonded, the impact force of the wire bonding can easily cause structural damage. The design of the process beam improves the stability and reliability of the device structure during the wire bonding process, effectively improving the success rate of heterogeneous integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of an embodiment of the present invention; Figure 2 This is a schematic diagram of the external frame structure of an embodiment of the present invention; Figure 3 This is a schematic diagram of a cross island framework according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a stator according to an embodiment of the present invention; Figure 5 A schematic diagram of a comb drive unit of a comb array according to an embodiment of the present invention; Figure 6 Schematic diagram of comb drive units of three comb arrays according to an embodiment of the present invention; Figure 7 It is a cross-sectional view and a top view of the glass after etching in the manufacturing step of the actuating platform according to an embodiment of the present invention; Figure 8 A cross-sectional view of a device in a manufacturing step of an actuating platform according to an embodiment of the present invention; Fig. 9 It is a schematic diagram of the stator cutting line and BCB material filling position of the present invention; Fig.10 This is a schematic diagram of the straight-shaped cutting opening of the present invention after being filled with BCB material; Fig.11 for Fig.10 Schematic diagram of the process of sputtering metal materials; Fig.12 This is a schematic diagram of the U-shaped cutting opening of the present invention after being filled with BCB material; Fig.13 It is a schematic diagram of the sputtering metal material of the present invention; Fig.14 This is a schematic diagram of a micro-motion platform of the present invention after sputtering metal material. DETAILED DESCRIPTION

[0013] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0014] See also Figure 1-Figure 14 , this embodiment provides an in-plane three-axis large-displacement actuation platform based on MEMS and a manufacturing method thereof.

[0015] like Figure 1 As shown, the MEMS-based in-plane three-axis large-displacement actuation platform includes an outer frame 1, a cross-island frame 2, a bidirectional comb drive unit 3, a long spring beam 4 and a short spring beam 5.

[0016] like Figure 2 As shown, material is removed from the outer frame 1 to form a cavity for accommodating the cross island frame 2 , and material is removed to form a cavity for accommodating the bidirectional comb drive unit 3 .

[0017] like Figure 3 As shown, the cross island frame 2 includes a cross 21 and cross bars 22 , and four cross bars 22 are respectively arranged at the outer ends of the cross 21 .

[0018] like Figure 4 As shown, the bidirectional comb drive brake 3 is composed of a stator 31 and a mover 32. Figure 4 As shown, the stator 31 has an open slot 40 , a first left comb-shaped array 41 is provided on the left side of the open slot 40 , a first right comb-shaped array 42 is provided on the right side, and a limiting slot 43 is formed in the middle of the open slot 40 .

[0019] like Figure 5As shown, a rectangular protrusion block 33 is provided on the mover 32, a second left comb-shaped array 34 is provided on the left side of the rectangular protrusion block, a second right comb-shaped array 35 is provided on the right side, and a protruding extension portion is provided on the left and right sides of the middle part of the rectangular protrusion block 33 to form a stop block 36. The rectangular protrusion block 33 is inserted into the middle of the opening slot 40, the first left comb-shaped array 41 and the second left comb-shaped array 34 are interlaced but not in contact with each other, the first right comb-shaped array 42 and the second right comb-shaped array 35 are interlaced but not in contact with each other, and the stop block 36 is located in the stop slot 43, which plays a role of limiting, preventing the mover's comb array and the stator's comb array from producing a side wall suction effect, contacting each other and causing a short circuit.

[0020] One end of the short spring beam 5 is connected to the mover 32, and the other end is connected to the stator 31. One end of the long spring beam 4 is connected to the mover 32, and the other end is connected to the cross island frame 2. In this way, a voltage is applied to the comb array on the mover 32 and the stator 31 through the circuit to drive the mover to move relative to the stator, and the driving force is applied to the cross island frame through the action of the long spring beam 4, thereby realizing the driving of the cross island frame.

[0021] Description of the bidirectional comb drive actuator drive mode. Figure 5 As shown, when the first left comb-shaped array 41 and the second left comb-shaped array 34 are powered on, the mover 32 moves leftward along the X-axis due to the electrostatic force. Conversely, when the first right comb-shaped array 42 and the second right comb-shaped array 35 are powered on, the mover 32 moves rightward along the X-axis due to the electrostatic force.

[0022] The open slots 40 on the stator and the rectangular protrusions 33 on the mover correspond one to one, and the two form a pair, which can realize bidirectional driving. In order to increase the driving force, the number of open slots and rectangular protrusions can be increased between the two. With the increase of open slots and rectangular protrusions, the number of comb-shaped arrays increases, and the increase of the number of comb-shaped arrays means the increase of electrostatic force. Figure 6 As shown, there are three open slots on the stator, and correspondingly, there are three rectangular protrusions 33 on the mover, so as to obtain a larger driving force.

[0023] like Figure 1As shown, there are four bidirectional comb-shaped drive actuators 3, which are respectively located in the four quadrants of the cross island frame, and each bidirectional comb-shaped drive unit 3 is connected to the cross island frame 2 through a long spring beam 4. Each adjacent two of the four bidirectional comb-shaped drive units 3 are set 90 degrees apart. This design ensures the uniformity and consistency of the platform's movement in all directions, and greatly improves the platform's motion control accuracy. The difference of 90 degrees is the angle of the moving direction of the stator. The drive units in the upper left corner and the lower right corner control the displacement in the X-axis direction, while the drive units in the upper right corner and the lower left corner control the displacement in the Y-axis direction. The platform can achieve independent and precise in-plane motion in the X-axis and Y-axis directions.

[0024] By controlling the differential motion of the four drive units, the in-plane rotation control of the cross-island platform can be achieved. This innovative design provides more flexible two-dimensional motion control while maintaining high precision. Through the compact drive unit layout, the cross-island structure is surrounded by four units, which improves the platform's fill rate and reduces the size of the device, making it easier to miniaturize and suitable for highly integrated microelectronic device applications.

[0025] The specific method of moving the Cross Island platform is as follows: The cross island moves left along the X axis: the left comb arrays of drive units A and C are powered on; The cross island moves along the Y axis: the upper comb arrays of driving power supplies B and D are powered on; The cross island rotates clockwise along the Z axis: the right comb array of drive unit A, the lower comb array of drive unit B, the left comb array of drive unit C, and the upper comb array of drive unit D are powered on. Similarly, the movement in other directions can be obtained by replacing the powered comb arrays, which will not be repeated. It should be noted that when the comb array on one side of the drive unit is powered on, the comb array on the other side is not powered on.

[0026] by Figure 1 Take the structure as an example, there are three open slots on the stator of each drive unit, and there are comb-shaped arrays on the left and right sides of each open slot. From the above introduction, we can know that: first, the comb-shaped array on the left and the comb-shaped array on the right need to be powered on to drive, and power needs to be laid out; second, the circuits of the comb-shaped array on the left and the comb-shaped array on the right should be isolated from each other, and when the left side is powered on, the right side cannot be powered on; third, the comb-shaped array on the left side of the three open slots should be treated as an electrically connected whole, and it needs to be connected through a circuit.

[0027] Three technical problems were encountered during the processing of the MEMS in-plane three-axis large-displacement actuator platform. One was how to isolate the left and right comb-shaped arrays of the three open slots to form two isolated circuits; the other was how to electrically connect the left comb-shaped arrays of the three open slots into a whole through the circuit; and the last one was that so many comb-shaped arrays would generate a lot of heat during the processing. If the heat dissipation was poor, the weak parts of the device would be burned, affecting the product yield.

[0028] The first step is to isolate the stator from the mover circuit. The method used is to cut the stator off from the entire part so that the stator and the part are separated to form an isolated block, such as Fig. 9 As shown, they are bonded together with benzocyclobutene resin (BCB) material to ensure insulation and integrity. The mover is connected to the entire part through a long spring beam. The second step is to cut out the three left comb arrays on the stator separately to form three independent blocks. Fig. 9 As shown in the figure, the white one is the cutting path. The black one is also the cutting path. The reason why it is black is that the BCB material is filled after the white cutting path, and the isolated blocks cut out are bonded together by BCB, but they are kept insulated from each other. Then, by laying an insulating layer and then laying a conductive metal on the insulating layer, the comb array on the left is connected together to form an electrically connected whole.

[0029] like Fig.10 As shown in the figure, in the actual processing, a straight cut is used at the beginning. After the cut is filled with BCB material and bonded, it is covered with insulating material, such as silicon dioxide. Finally, the conductive metal material is precipitated. Experiments have found that this process method has a low product yield. Analysis has found that the insulating material (silicon dioxide) at both ends of the straight cut will fall off to varying degrees during wet etching, resulting in the exposure of the low-resistance silicon layer under the insulating material. When covering the metal conductive layer, the exposed silicon layer will connect the left and right sides, such as Fig.11 As shown, the process eventually failed. After repeated experiments, a solution with a U-shaped cut was proposed, as shown in Fig.12 As shown in FIG. 1 , a U-shaped blade design is adopted. Although the exposed two ends still exist, the metal conductive layer is laid through the middle part of the U-shaped mouth instead of the exposed two ends. Fig.13 As shown, the properties of the insulating material in this part are relatively stable, which greatly improves the electrical isolation performance of the device.

[0030] The embodiment of the present invention also provides a method for manufacturing an in-plane three-axis large displacement actuation platform based on MEMS. The in-plane three-axis large displacement actuation platform based on MEMS includes an outer frame 1, a cross island frame 2, a bidirectional comb drive unit 3, a long spring beam 4 and a short spring beam 5, and includes the following steps: Step 1: Etching of glass substrate. The glass substrate is the supporting structure of the entire device.

[0031] First, prepare a 4-inch, 500-micron-thick BF33 glass 81, such as Figure 8 As shown in a, after organic cleaning, photoresist is spin-coated, and the photoresist is photolithographically processed in a photolithography machine through a mask; Step 2: Use magnetic neutral loop discharge plasma (NLD) anisotropic etching technology to etch a 12μm cavity and wet remove the photoresist, such as Figure 7 , 8 As shown in b, the white part is the cavity formed by etching away the material; Step 3: Prepare 4 inches of low-resistance silicon 82 (thickness 400 microns), such as Figure 8 As shown in c, the anodic bonding process is used to bond the side of the BF33 glass wafer with the cavity structure to the low-resistance silicon wafer; Step 4: Use a thinning machine to thin the low-resistance silicon wafer surface of the bonded wafer to 100 μm thick, such as Figure 8 As shown in d, low-resistance silicon 82 is used as the device layer.

[0032] Step 5: Deep silicon etching (DRIE) is used to electrically isolate the channel on the low-resistance silicon, and the stator is cut out of the low-resistance silicon to form an independent part. Then the left comb array and the right comb array of the stator are cut into two independent parts to achieve electrical isolation between the two parts. Fig. 9 As shown, an electrical isolation channel is etched at a set position. In order to achieve electrical isolation between the two and ensure that the two are a whole, to prevent the comb array on the left from hanging in the air and falling off the low-resistance silicon, the two cut parts need to be bonded together. Fig. 9 As shown, the electrical isolation channels at the lower positions of the comb-shaped array on the left and the comb-shaped array on the right are U-shaped. The reason for adopting the U-shape is as mentioned above and will not be repeated here. Similarly, the connection between the comb-shaped array on the right and the low-resistance silicon also adopts a U-shaped electrical isolation channel. The specific process is to spin-coat the photoresist, then photolithography through the mask in the photolithography machine, and use the deep silicon etching (DRIE) technology to etch the electrical isolation channel on the low-resistance silicon wafer, and finally remove the photoresist.

[0033] Step 6: Fill the BCB material 83 in the electrical isolation channel, bond the cut and separated left comb-shaped array and right comb-shaped array into a whole, and then bond the right comb-shaped array and the low-resistance silicon 82 into a whole, as shown in FIG. Fig. 9 As shown. Figure 8 As shown in FIG. 5 , the BCB liquid is pumped into the isolation trench of the removed low-resistance silicon as an insulating layer, and the BCB material is cured at high temperature. The BCB on the surface of the low-resistance silicon is removed by chemical mechanical polishing (CMP), and only the BCB material in the trench needs to be retained, such as Fig. 9As shown. The left comb array and the right comb array are bonded together by BCB material to form a complete block. The right comb array is bonded together with low-resistance silicon by BCB material to form a complete block. BCB material is insulating and also ensures the electrical isolation of the left comb array and the right comb array, and the electrical isolation of the right comb array from the entire low-resistance silicon wafer.

[0034] Step 7: Deposit a PECVD oxide layer 84 on the low-resistance silicon, one on the left comb-shaped array and one on the right comb-shaped array, such as Figure 8 h. Fig. 9 As shown, the three comb-shaped arrays on the left side of the stator are already three independent electrically isolated plates, which need to be interconnected with metal to form a conductive whole. When laying the metal layer on the entire low-resistance silicon board, the independent plates of the three comb-shaped arrays on the right side of the stator will pass through. Because low-resistance silicon itself is conductive, a metal conductive layer must be laid on the low-resistance silicon board to electrically isolate it from the three comb-shaped arrays on the right side, so an oxide layer needs to be deposited as an insulating layer. First, the three left comb-shaped arrays of the stator are connected by laying an insulating layer on the low-resistance silicon board, and then a conductive metal layer is laid on the insulating layer to electrically connect the three comb-shaped arrays on the left. At the same time, an insulating layer must also be laid for the three comb-shaped arrays on the right side of the stator. Although the three comb-shaped arrays on the right side are already complete independent blocks, the manufacturing process of electrical isolation still needs to be completed.

[0035] Step 8: Sputter a 400nm metal layer and use a lift-off process to make a metal conductor layer 85, and lay three circuits, one for the comb-shaped array on the left side of the stator, one for the comb-shaped array on the right side of the stator, and one for the comb-shaped array on the mover. Fig.14 As shown, the three comb-shaped arrays on the left side of the stator are electrically connected using a metal wire layer. At the same time, a metal wire layer is also laid for the three comb-shaped arrays on the right side to form a separate circuit. Thus, three independent circuits are formed: (1) the comb-shaped array circuit of the mover, which is directly connected to the low-resistance silicon; (2) the comb-shaped array circuit on the left side of the stator; (3) the comb-shaped array circuit on the right side of the stator. The metal layers of the comb-shaped array on the left side of the stator and the comb-shaped array on the right side are laid on the insulating layer PECVD oxide layer. The comb-shaped array of the mover is integrated with the entire low-resistance silicon, and the circuit can be directly led out on the low-resistance silicon.

[0036] Step 9: Deep silicon etching (DRIE) process etches low-resistance silicon, such as Figure 8 Similarly, the photoresist is first spin-coated, and then photolithography is performed in the photolithography machine through a mask plate, and deep silicon etching (DRIE) is performed on low-resistance silicon to form the actuating structure of the device layer.

[0037] like Figure 1As shown, the deep silicon etching (DRIE) process simultaneously etches out the cross island frame, the bidirectional comb drive unit 3, the long spring beam 4 and the short spring beam 5. During the etching process, a number of process beams 9 are reserved, one end of the process beam is connected to the cross island frame, and the other end is connected to the outer frame.

[0038] The process beam has three functions. The first function is to improve the heat dissipation performance of the device in the deep silicon etching (DRIE) process and improve the device etching yield. In the manufacturing process of the suspended structure of the device, especially in deep silicon etching (DRIE), if the heat conduction structure is improperly designed or there is no effective thermal management, the photoresist may become sticky during the etching process, which will affect the integrity and function of the device. In the deep silicon etching (DRIE) process, the etching area continuously removes silicon materials through ion bombardment and chemical reactions, generating a large amount of heat. The suspended structure is usually an area with a large cavity, and the heat below it cannot be effectively dissipated through the substrate. In conventional processes, the silicon wafer itself can exchange heat with the tray or cooling system through the substrate to take away the heat generated during the etching process. However, in the etching of the suspended structure, due to the cavity under the structure, the heat cannot be effectively conducted to the heat dissipation system through the silicon wafer substrate. If an effective heat conduction structure is not designed, the heat generated during the etching process cannot be discharged in time, resulting in a local temperature increase on the suspended structure. When the temperature reaches the thermal stability limit of the photoresist, the photoresist will denature due to excessive temperature, commonly known as sticky glue. The denatured photoresist loses its original corrosion resistance and cannot effectively shield the etching gas, thus exposing the areas that should be protected and causing these areas to be directly etched. In the case of photoresist paste, tiny structures that should be covered by photoresist (such as spring beams, cantilever beams and other precision structures) are exposed to the etching gas. The etching gas (such as SF6) in the DRIE process not only etches the silicon surface, but also corrodes the exposed precision structures through physical and chemical reactions. These structures are often very fragile and delicate. Once exposed to a high-energy etching environment, the integrity of the structure may be destroyed, resulting in device failure.

[0039] Through the design of the process beam, the cross island frame that was originally disconnected from the outer frame is connected through the process beam. During the deep silicon etching process, the heat generated by the comb array is transferred to the cross island frame through the long spring beam, and then transferred to the outer frame through the process beam, thereby improving the heat dissipation efficiency and avoiding device failure caused by overheating.

[0040] The second function of the process beam is to enhance the structural strength of the device during transportation and prevent damage to the device due to external forces during transportation. Suspended structures are usually fragile and easily damaged by the external environment during transportation, thereby reducing product reliability and shipment yield.

[0041] The third function of the process beam is to improve the stability and reliability of the device structure when the image sensor is wired on the in-plane three-axis large displacement actuation platform. When sensitive devices such as CMOS are integrated into the MEMS actuation platform, the instantaneous pressure generated in the wire bonding process may cause structural damage to the suspension platform, thereby affecting the device performance and yield. At present, the solution to this problem is to add a separate process support structure under the device suspension structure, and then remove the process support structure after the wire bonding process is completed. The process steps are relatively complicated (Design, fabrication and actuation of a MEMSbased image stabilizer for photographic cell phone applications, Jin-Chern Chiou et al 2010 J. Micromech. Microeng. 20 075025). The design of this patent application provides sufficient support through the design of the process beam, ensures the structural integrity of the wire bonding process, and solves the balance problem between flexibility and rigidity of the suspension structure, thereby improving the application potential of the MEMS platform in highly integrated devices. Scenarios such as optical image stabilization that require the integration of sensitive devices such as Figure 8 As shown in Figure 1, after the CMOS image sensor is mounted on the MEMS platform, wire bonding is required. Since the cross island frame is a suspended structure and lacks support, the instantaneous downward pressure applied during the wire bonding process may damage the MEMS platform. At this time, the process beam can provide support, withstand instantaneous pressure, and prevent damage to the platform. Before the wire bonding is completed and ready for use, the process beam can be removed through a laser sintering process to ensure the normal function and operation of the platform without affecting the final performance of the device.

[0042] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “up”, “down”, “left”, “right”, “clockwise” and “counterclockwise” are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0043] The above embodiments are only to illustrate the basic principles and characteristics of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and modifications, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An in-plane three-axis large displacement actuation platform based on MEMS, characterized by: It comprises an outer frame (1), a cross island frame (2), a bidirectional comb drive unit (3), a long spring beam (4) and a short spring beam (5); The outer frame (1) comprises a cavity for accommodating the cross island frame (2) and a cavity for accommodating the bidirectional comb drive unit (3); The cross island frame (2) comprises a cross (21) and cross bars (22), wherein a total of four cross bars (22) are respectively arranged at the outer ends of the cross (21); The bidirectional comb-shaped drive unit (3) is composed of a stator (31) and a mover (32). The stator (31) is provided with an open slot (40). The left side of the open slot (40) is provided with a first left comb-shaped array (41), and the right side is provided with a first right comb-shaped array (42). The mover (32) is provided with a rectangular protrusion block (33). The left side of the rectangular protrusion block is provided with a second left comb-shaped array (34), and the right side is provided with a second right comb-shaped array (35). The rectangular protrusion block (33) is inserted into the middle of the open slot (40). The first left comb-shaped array (41) and the second left comb-shaped array (34) are interlaced with each other and there is a gap. The first right comb-shaped array (42) and the second right comb-shaped array (35) are interlaced with each other and there is a gap. One end of the short spring beam (5) is connected to the mover (32), and the other end is connected to the stator (31); One end of the long spring beam (4) is connected to the mover (32), and the other end is connected to the cross island frame (2); There are four bidirectional comb-shaped drive units (3), which are respectively located in four quadrants of the cross island frame. Each bidirectional comb-shaped drive unit (3) is connected to the cross island frame (2) via a long spring beam (4). Each adjacent two of the four bidirectional comb-shaped drive units (3) are arranged at a 90-degree difference.

2. The MEMS-based in-plane three-axis large-displacement actuation platform according to claim 1, characterized in that: The rectangular raised block (33) has protruding extensions on both sides of the middle portion thereof to form a limit block (36). A limit groove (43) is formed in the middle of the opening groove (40), and the limit block (36) is located in the limit groove (43).

3. The MEMS-based in-plane three-axis large-displacement actuation platform according to claim 1, characterized in that: The open slots (40) on the stator (31) and the rectangular protrusions (33) on the mover (32) correspond one to one, and two of them form a pair. The stator (31) has three open slots (40) in total, and correspondingly, the mover (32) has three rectangular protrusions (33), and each open slot (40) and rectangular protrusion (33) has a matching comb-shaped array.

4. A method for manufacturing an in-plane three-axis large displacement actuation platform based on MEMS as claimed in any one of claims 1 to 3, wherein the in-plane three-axis large displacement actuation platform based on MEMS comprises an outer frame (1), a cross island frame (2), a bidirectional comb drive unit (3), a long spring beam (4) and a short spring beam (5), and comprises the following steps: Step 1: Etching of glass substrate; A piece of BF33 glass is organically cleaned and then spin-coated with photoresist, which is then photolithographically processed in a photolithography machine through a mask; Step 2: using magnetic neutral loop discharge plasma (NLD) anisotropic etching technology to etch out the cavity structure, and wet remove the photoresist; Step 3: Bond the side of the BF33 glass wafer with the cavity structure to the low-resistance silicon wafer using an anodic bonding process; Step 4: Use a thinning machine to thin the low-resistance silicon wafer surface of the bonding sheet; Step 5: Deep silicon etching an electrical isolation channel on the low-resistance silicon, cutting the stator from the low-resistance silicon to form an independent part, and then cutting the left comb-shaped array and the right comb-shaped array of the stator into two independent parts to achieve electrical isolation between the two, and then etching the electrical isolation channel at a set position, and the electrical isolation channel at the lower position of the left comb-shaped array and the right comb-shaped array is U-shaped; Step 6: Filling the BCB material in the electrical isolation trench, bonding the cut and separated left comb array and right comb array into a whole, and then bonding the right comb array and low-resistance silicon into a whole, vacuum pumping BCB liquid into the isolation trench of the removed low-resistance silicon as an insulating layer, and curing the BCB material at high temperature, removing the BCB on the surface of the low-resistance silicon through the chemical mechanical polishing (CMP) process, and only retaining the BCB material in the trench; Step 7: Depositing a PECVD oxide layer on the low-resistance silicon, one comb array on the left and one comb array on the right; Step 8: Sputter the metal layer and use the lift-off process to make the metal conductor layer, which is used to lay three circuits, one stator left comb array, one stator right comb array and one mover comb array. The metal layers of the stator left comb array and the right comb array are laid on the insulating layer PECVD oxide layer. The mover comb array is integrated with the entire low-resistance silicon, and the circuit is directly led out on the low-resistance silicon. Step nine: deep silicon etching process etches low-resistance silicon. First, spin-coat photoresist, then use a mask plate to be photoetched in a photolithography machine, deep silicon etches low-resistance silicon, and at the same time etches out a cross island frame, a bidirectional comb drive unit (3), a long spring beam (4) and a short spring beam (5), and a plurality of process beams (9). One end of the process beam (9) is connected to the cross island frame (2), and the other end is connected to the outer frame (1).

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