Piezoelectric MEMS micromirror and manufacturing method
By deposition and etching on the SOI substrate to form a multi-layer stacked structure, the problems of low detection accuracy and complex manufacturing are solved, and more efficient driving and more sensitive feedback control are achieved.
Patent Information
- Application Number
- CN202411193037.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-28
- Publication Date
- 2025-01-07
AI Technical Summary
The existing piezoelectric MEMS micromirrors use piezoresistive detection method to detect subtle resistance changes, low detection accuracy, complex manufacturing process, and poor compatibility.
Multi-layer metal layers and piezoelectric material layers are deposited on the SOI substrate to form a multi-layer stacked structure, and the stepped structure and hollow structure are formed through etching to improve the mechanical strength and driving efficiency of the micromirror. Real-time monitoring is adopted using a self-feedback control system. Position and automatically adjust the driving voltage.
It improves the detection accuracy and manufacturing compatibility of micromirrors, enhances mechanical performance and response speed, and achieves more sensitive feedback signals and precise control.
Smart Images
Figure CN119263194A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of micromirrors, and in particular to a piezoelectric MEMS micromirror and a manufacturing method thereof. Background Art
[0002] Piezoelectric MEMS micromirrors combine piezoelectric drive and position sensing functions, using piezoelectric materials to generate stress deformation in an electric field to drive the micromirror to rotate, in order to achieve more accurate and rapid feedback control of the rotation angle.
[0003] In the prior art, piezoelectric MEMS micromirrors usually adopt a piezoresistive detection method. First, a variable resistor is buried at the position where rotation needs to be detected to form a Wheatstone bridge. The resistance value of the piezoresistance changes by detecting the deformation of the object. Finally, information such as the deflection angle of the micromirror can be obtained through data processing. However, this type of piezoelectric MEMS micromirror has two problems. On the one hand, the piezoresistance change is small, and the detection of slight deformation is not obvious enough. Once the resistance change is relatively slight, its detection accuracy is difficult to meet the requirements. On the other hand, multiple steps such as multiple injections and annealing need to be added before the micromirror is manufactured, which affects the compatibility of the manufacturing process. Summary of the invention
[0004] In view of the shortcomings of the above-mentioned prior art, the present invention provides a piezoelectric MEMS micromirror and a manufacturing method, which solves the technical problems that the prior art piezoelectric MEMS micromirror adopts piezoresistive detection, cannot detect slight resistance changes, has low detection accuracy, complex manufacturing process and poor compatibility.
[0005] In one aspect, the present invention provides a method for manufacturing a piezoelectric MEMS micromirror, comprising:
[0006] Making SOI substrate;
[0007] Depositing multiple metal layers and multiple piezoelectric material layers on the SOI substrate to form a multi-layer stacked structure, and etching the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape;
[0008] Deep silicon etching is performed on a side of the SOI substrate away from the multi-layer stacking structure, so that the SOI substrate forms a hollow structure.
[0009] Optionally, the SOI substrate includes a bottom silicon layer, an insulating layer and a top silicon layer arranged in sequence from bottom to top; and the manufacturing of the SOI substrate includes:
[0010] Selecting a silicon wafer as the bottom silicon of the SOI substrate;
[0011] Forming a layer of silicon oxide on the upper surface of the bottom silicon by a thermal oxidation process as an insulating layer of the SOI substrate;
[0012] When the preset temperature is reached, another silicon wafer is bonded to the insulating layer to form a top silicon layer of the SOI substrate, and the top silicon layer is polished to a preset thickness.
[0013] Optionally, depositing multiple metal layers and multiple piezoelectric material layers on the SOI substrate to form a multi-layer stacked structure includes:
[0014] A first metal layer, a first piezoelectric material layer, a second metal layer, a second piezoelectric material layer and a third metal layer are sequentially deposited on the SOI substrate from bottom to top to form a multi-layer stacked structure.
[0015] Optionally, the piezoelectric materials in the first piezoelectric material layer and the second piezoelectric material layer include barium titanate, lead zirconate titanate, modified lead zirconate titanate, lead metaniobate, barium lithium lead niobate and modified lead titanate.
[0016] Optionally, the first metal layer, the second metal layer and the third metal layer are deposited by magnetron sputtering or metal evaporation;
[0017] The first piezoelectric material layer and the second piezoelectric material layer are deposited by magnetron sputtering or sol-gel method.
[0018] Optionally, etching the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape includes:
[0019] The multi-layer stacked structure is etched by dry etching or wet etching, so that the multi-layer stacked structure is in a step shape.
[0020] Optionally, the etching of the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape further comprises:
[0021] Etching the first piezoelectric material layer and the second metal layer respectively so that the first piezoelectric material layer and the second metal layer have the same length, wherein the length of the second metal layer is less than the length of the first metal layer;
[0022] The second piezoelectric material layer and the third metal layer are etched respectively so that the second piezoelectric material layer and the third metal layer have the same length, wherein the length of the third metal layer is shorter than that of the second metal layer.
[0023] Optionally, performing deep silicon etching on a side of the SOI substrate away from the multi-layer stacked structure so that the SOI substrate forms a hollow structure includes:
[0024] The top silicon layer of the SOI substrate is retained, and deep silicon etching is performed on the bottom silicon layer and the insulating layer located at the center of the SOI substrate, so that the SOI substrate forms a hollow structure.
[0025] Another aspect of the present invention provides a piezoelectric MEMS micromirror manufactured based on any of the above-mentioned methods for manufacturing a piezoelectric MEMS micromirror, comprising an SOI substrate and a multi-layer stacked structure;
[0026] The multi-layer stacked structure is arranged on the upper surface of the SOI substrate, and the multi-layer stacked structure includes a first metal layer, a first piezoelectric material layer, a second metal layer, a second piezoelectric material layer and a third metal layer arranged in sequence from bottom to top, wherein the length of the third metal layer is less than the length of the second metal layer, the length of the second metal layer is less than the length of the first metal layer, and the length of the first piezoelectric material layer is the same as that of the second metal layer, and the length of the second piezoelectric material layer is the same as that of the third metal layer;
[0027] The SOI substrate comprises a bottom silicon layer, an insulating layer and a top silicon layer which are arranged in sequence from bottom to top, and the centers of the insulating layer and the bottom silicon layer are hollow structures.
[0028] Optionally, the first metal layer, the first piezoelectric material layer and the second metal layer constitute a piezoelectric driving layer, and an excitation voltage is applied through the first metal layer and the second metal layer to cause the first piezoelectric material layer to deform;
[0029] The second metal layer, the second piezoelectric material layer and the third metal layer constitute a piezoelectric self-feedback layer. The second piezoelectric material layer deforms based on the deformation of the first piezoelectric material layer, thereby generating an electric potential difference and generating a self-feedback signal, and outputting the self-feedback signal through the second metal layer and the third metal layer.
[0030] The piezoelectric MEMS micromirror and manufacturing method provided by the present invention form a multi-layer stacking structure by depositing multiple metal layers and piezoelectric material layers on an SOI substrate, thereby improving the stability and durability of the overall structure of the micromirror. The stepped multi-layer stacking structure formed after etching not only improves the mechanical strength and reliability of the micromirror, but also provides a larger driving area, increases the driving efficiency, and enables the micromirror to respond to changes in electrical signals more quickly. The hollow structure formed by deep silicon etching reduces the mass of the micromirror and improves the mechanical properties and response speed of the micromirror. Based on the self-feedback control system formed by the multiple piezoelectric material layers in the multi-layer stacking structure, the position of the micromirror can be monitored in real time, and the driving voltage can be automatically adjusted so that the piezoelectric MEMS micromirror can obtain a more sensitive feedback signal when working, thereby realizing accurate control and correction of the micromirror's own state. At the same time, the technologies involved in the manufacturing method, such as the production of SOI substrates, the deposition of metals and piezoelectric materials, etching technology, and deep silicon etching technology, have themselves been widely used in the manufacture of MEMS devices. The use of mature materials and process flows, as well as high compatibility with existing production equipment, ensures maximum compatibility with existing processes.
[0031] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.
[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:
[0034] Figure 1 A flowchart of a method for manufacturing a piezoelectric MEMS micromirror in an embodiment provided in the present application;
[0035] Figure 2 A schematic diagram of the steps of making an SOI substrate in a method for manufacturing a piezoelectric MEMS micromirror in an embodiment provided in the present application;
[0036] Figure 3 A schematic diagram of the steps of depositing multiple metal layers and multiple piezoelectric material layers on an SOI substrate to form a multi-layer stacked structure in a method for manufacturing a piezoelectric MEMS micromirror in an embodiment provided in the present application;
[0037] Figure 4A schematic diagram of the steps of etching a multi-layer stacked structure in a method for manufacturing a piezoelectric MEMS micromirror in an embodiment provided in the present application, so that the multi-layer stacked structure is in a stepped shape;
[0038] Figure 5 A schematic diagram of the structure of a piezoelectric MEMS micromirror formed by performing deep silicon etching on a side of an SOI substrate away from a multi-layer stacked structure in a method for manufacturing a piezoelectric MEMS micromirror in an embodiment provided in the present application;
[0039] Figure 6 A functional schematic diagram of a piezoelectric MEMS micromirror in an embodiment provided in the present application.
[0040] In the figure:
[0041] 1. SOI substrate; 101. bottom silicon; 102. insulating layer; 103. top silicon;
[0042] 2. Multi-layer stacking structure; 201. first metal layer; 202. first piezoelectric material layer; 203. second metal layer; 204. second piezoelectric material layer; 205. third metal layer;
[0043] V1, applied excitation voltage; V2, read-out self-feedback signal. DETAILED DESCRIPTION
[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.
[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0047] The present invention provides a method for manufacturing a piezoelectric MEMS (Micro-Electro-Mechanical Systems) micromirror, such as Figure 1 As shown, the process includes first making a SOI (Silicon-on-Insulator) substrate, then depositing multiple metal layers and multiple piezoelectric material layers on the SOI substrate 1 to form a multi-layer stacking structure 2, and etching the multi-layer stacking structure 2 so that the multi-layer stacking structure 2 is stepped, and finally performing deep silicon etching on the side of the SOI substrate 1 away from the multi-layer stacking structure 2 so that the SOI substrate 1 forms a hollow structure.
[0048] The manufacturing method of the piezoelectric MEMS micromirror provided in the present application forms a multi-layer stacking structure 2 by depositing multiple metal layers and piezoelectric material layers on an SOI substrate 1, thereby improving the stability and durability of the overall structure of the micromirror. The stepped multi-layer stacking structure 2 formed after etching not only improves the mechanical strength and reliability of the micromirror, but also provides a larger driving area, increases the driving efficiency, and enables the micromirror to respond to changes in electrical signals more quickly. The hollow structure formed by deep silicon etching reduces the mass of the micromirror and improves the mechanical properties and response speed of the micromirror. Based on the self-feedback control system formed by the multiple piezoelectric material layers in the multi-layer stacking structure 2, the position of the micromirror can be monitored in real time, and the driving voltage can be automatically adjusted so that the piezoelectric MEMS micromirror can obtain a more sensitive feedback signal when working, thereby realizing precise control and correction of the micromirror's own state. At the same time, the technologies involved in the manufacturing method, such as the production of the SOI substrate 1, the deposition and etching technology of metals and piezoelectric materials, and the deep silicon etching technology, have themselves been widely used in the manufacture of MEMS devices. The use of mature materials and process flows, as well as high compatibility with existing production equipment, ensures maximum compatibility with existing processes.
[0049] Further, such as Figure 2As shown, the SOI substrate 1 includes a bottom silicon 101, an insulating layer 102 and a top silicon 103 arranged in sequence from bottom to top; manufacturing the SOI substrate 1 includes first selecting a silicon wafer as the bottom silicon 101 of the SOI substrate 1, then using a thermal oxidation process to form a layer of silicon oxide on the upper surface of the bottom silicon 101 as the insulating layer 102 of the SOI substrate 1, and finally, under a preset temperature condition, bonding another silicon wafer to the insulating layer 102 to form the top silicon 103 of the SOI substrate 1, and polishing the top silicon 103 to a preset thickness.
[0050] In this embodiment, the SOI substrate 1, as the basic supporting material of the piezoelectric MEMS micromirror, has good electrical isolation performance and mechanical properties, and can effectively reduce the thermal stress and mechanical stress on the device, thereby improving the reliability and durability of the device; specifically, by forming a layer of silicon oxide as the insulating layer 102 on the bottom silicon 101, the electrical connection between the top silicon 103 and the bottom silicon 101 can be effectively isolated, the parasitic capacitance effect can be reduced, and the electrical isolation performance of the device can be improved; the insulating layer 102 is formed by a thermal oxidation process to ensure the quality and uniformity of the insulating layer 102, and another silicon wafer is bonded to the insulating layer 102, which can ensure that a strong bond is formed between the top silicon 103 and the insulating layer 102, thereby improving the structural stability of the entire SOI substrate 1, and by polishing the top silicon 103 to a preset thickness, the final thickness of the SOI substrate 1 can be accurately controlled, which is beneficial to the subsequent micromachining process.
[0051] Further, such as Figure 3 As shown, multiple metal layers and multiple piezoelectric material layers are deposited on the SOI substrate 1 to form a multilayer stacked structure 2, including depositing a first metal layer 201, a first piezoelectric material layer 202, a second metal layer 203, a second piezoelectric material layer 204 and a third metal layer 205 in sequence from bottom to top on the SOI substrate 1 to form a multilayer stacked structure 2.
[0052] In this embodiment, by depositing multiple layers of piezoelectric material layers on the SOI substrate 1, the driving area can be increased and the utilization rate of the piezoelectric effect can be improved, so that the micromirror can respond to changes in electrical signals more efficiently. Among them, the metal layer serves as an electrode, which can improve the connection between the piezoelectric material layer and the external circuit and improve the transmission efficiency of the driving voltage. In addition, the multi-layer stacking structure 2 improves the overall structural stability of the micromirror and enhances the mechanical strength. While reducing the weight of the micromirror, it reduces inertia and improves the response speed. The multi-layer stacking structure 2 can also support more complex driving modes, so that the micromirror can be precisely controlled in different directions. At the same time, it can also increase the area of the effective feedback area and improve the signal collection efficiency. In addition, by optimizing the number and configuration of the piezoelectric material layer, the strength of the feedback signal can be improved, making the feedback signal more sensitive and easier to detect.
[0053] Specifically, in the above embodiment, the piezoelectric materials in the first piezoelectric material layer 202 and the second piezoelectric material layer 204 include barium titanate, lead zirconate titanate, modified lead zirconate titanate, lead metaniobate, barium lithium lead niobate and modified lead titanate.
[0054] In this embodiment, barium titanate (BaTiO3) has a higher piezoelectric coefficient and is suitable for applications requiring larger deformations; lead zirconate titanate (PZT) has a very high piezoelectric coefficient and is one of the commonly used high-performance piezoelectric materials; modified lead zirconate titanate (MPZT) improves the performance of lead zirconate titanate by doping and other means, which can further improve the piezoelectric coefficient; lead barium lithium niobate (PLN) has good temperature stability and can maintain good performance even at higher temperatures; modified lead titanate (MPT) also has a wider operating temperature range; lead metaniobate (PNN) has good mechanical strength and toughness, which helps to improve the durability and reliability of piezoelectric MEMS micromirrors. Based on this, in addition to good temperature stability, lithium lead barium niobate also has good mechanical properties, which helps to improve the mechanical strength of the micromirror; both lead zirconate titanate and modified lead zirconate titanate have a wide frequency response range, which is suitable for applications that need to work at different frequencies; barium titanate also has a wide operating frequency range, and both barium titanate and lead zirconate titanate have good processing performance, and a variety of deposition techniques can be used for thin film preparation. Lithium lead barium niobate and modified lead titanate are also relatively easy to process and suitable for large-scale production; from a cost perspective, the cost of barium titanate is lower. Although the cost of lead zirconate titanate is slightly higher than that of barium titanate, it has obvious advantages in performance and is a cost-effective choice for high-performance applications. In this application, different piezoelectric materials are selected to customize the performance of piezoelectric MEMS micromirrors according to specific application requirements, and the use of a multilayer piezoelectric structure composed of different materials can improve the driving efficiency, so that the micromirror can respond to changes in electrical signals more efficiently.
[0055] Specifically, in the above embodiment, the first metal layer 201, the second metal layer 203 and the third metal layer 205 are deposited by magnetron sputtering or metal evaporation; the first piezoelectric material layer 202 and the second piezoelectric material layer 204 are deposited by magnetron sputtering or sol-gel.
[0056] In this embodiment, the metal layer can usually be deposited by magnetron sputtering or metal evaporation, and the piezoelectric material layer can be deposited by magnetron sputtering or sol-gel. Specifically, magnetron sputtering can provide a uniform and dense deposition layer, and by adjusting the sputtering time and power, the thickness of the film can be accurately controlled, which helps to improve the quality of the metal layer and the piezoelectric material layer; metal evaporation is suitable for depositing metal layers, which can form a dense and uniform film, which helps to improve the electrical performance of the device; sol-gel can accurately control the thickness of the piezoelectric material layer by controlling the concentration of the solution and the deposition conditions. Whether it is magnetron sputtering, sol-gel or metal evaporation, they are all relatively mature thin film deposition technologies, which can be compatible and matched with existing manufacturing processes and are easy to implement on the production line. Among them, metal evaporation and sol-gel also have the advantage of low cost.
[0057] Specifically, in the above embodiment, if Figure 4 As shown, the multi-layer stacked structure 2 is etched so that the multi-layer stacked structure 2 is in a step shape, including etching the multi-layer stacked structure 2 by dry etching or wet etching so that the multi-layer stacked structure 2 is in a step shape.
[0058] In this embodiment, dry etching is an etching process performed in the absence of a liquid medium, and plasma or ion beam is usually used to remove materials. Its working principle is to remove materials by chemically or physically reacting active particles in the plasma, such as free radicals or ions, with the material to be etched, and generally includes reactive ion etching and ion milling; wet etching is an etching method that uses chemical solutions, such as acids, alkalis or solvents, to dissolve or corrode materials. Its working principle is to remove materials by chemical reactions between chemical solutions and materials, and generally includes acid etching and alkaline etching. Specifically, although dry etching is more expensive, it can accurately control the depth and shape of etching, which helps to form a stepped structure of the multilayer stacking structure 2, while wet etching is low in cost and can selectively etch certain materials. By optimizing the etching conditions, the multilayer stacking structure 2 is easy to manufacture and the yield rate is improved.
[0059] Specifically, in the above embodiment, the multilayer stacked structure 2 is etched so that the multilayer stacked structure 2 is stepped, and also includes etching the first piezoelectric material layer 202 and the second metal layer 203 respectively so that the length of the first piezoelectric material layer 202 is the same as that of the second metal layer 203, wherein the length of the second metal layer 203 is smaller than the length of the first metal layer 201; etching the second piezoelectric material layer 204 and the third metal layer 205 respectively so that the length of the second piezoelectric material layer 204 is the same as that of the third metal layer 205, wherein the length of the third metal layer 205 is smaller than the length of the second metal layer 203.
[0060] In this embodiment, a stepped structure is formed by etching, which can increase the area of the effective feedback region, improve the signal collection efficiency, and make the feedback signal more sensitive and easier to detect. Specifically, by accurately controlling the length of each layer, the distribution of the piezoelectric material can be optimized, thereby improving the control accuracy of the micromirror, and the stepped structure helps to improve the mechanical strength and reliability of the micromirror, reduce deformation caused by material stress, and thus improve control accuracy. At the same time, based on the present application, the length of the first metal layer 201 is unchanged and is the longest, the first piezoelectric material layer 202 and the second metal layer 203 are of the same length and are in the middle length, and the second piezoelectric material layer 204 and the third metal layer 205 are of the same length and are the shortest, forming a three-level ladder, which can be directly distinguished as a piezoelectric self-feedback layer and a piezoelectric drive layer, which is convenient for receiving the excitation signal and collecting the self-feedback signal.
[0061] Further, such as Figure 5 As shown, deep silicon etching is performed on the side of the SOI substrate 1 away from the multi-layer stacking structure 2, so that the SOI substrate 1 forms a hollow structure, including retaining the top silicon 103 of the SOI substrate 1, and deep silicon etching is performed on the bottom silicon 101 and the insulating layer 102 located at the center of the SOI substrate 1, so that the SOI substrate 1 forms a hollow structure.
[0062] Among them, deep silicon etching usually uses plasma etching technology, the most common of which is reactive ion etching (RIE). Specifically, in the RIE process, the SOI substrate 1 is placed in a reaction chamber, and a specific gas, such as hydrogen fluoride gas HF or SF6, is introduced into the reaction chamber, and plasma is generated under the action of a high-voltage electric field. The active ions and free radicals in the plasma react with silicon to peel off the silicon atoms, thereby achieving etching.
[0063] In this embodiment, a hollow structure is formed by deep silicon etching, which can improve the yield rate in the manufacturing process, reduce the overall weight of the piezoelectric MEMS micromirror, reduce inertia, thereby improving the response speed and mechanical properties. The hollow structure reduces the constraints on the movement of the micromirror, helps to improve the driving efficiency, and enables the micromirror to respond to changes in electrical signals more efficiently. At the same time, it can also optimize the collection of feedback signals and improve the strength and sensitivity of the signal. The hollow structure can also improve the heat dissipation efficiency of the piezoelectric MEMS micromirror, reduce heat accumulation, and extend the service life.
[0064] Another aspect of the present invention provides a piezoelectric MEMS micromirror, which is manufactured based on any of the above-mentioned piezoelectric MEMS micromirror manufacturing methods, such as Figure 5As shown, it includes an SOI substrate 1 and a multilayer stacking structure 2; the multilayer stacking structure 2 is arranged on the upper surface of the SOI substrate 1, and the multilayer stacking structure 2 includes a first metal layer 201, a first piezoelectric material layer 202, a second metal layer 203, a second piezoelectric material layer 204 and a third metal layer 205 arranged in sequence from bottom to top, wherein the length of the third metal layer 205 is less than the length of the second metal layer 203, the length of the second metal layer 203 is less than the length of the first metal layer 201, and the lengths of the first piezoelectric material layer 202 and the second metal layer 203 are the same, and the lengths of the second piezoelectric material layer 204 and the third metal layer 205 are the same; the SOI substrate 1 includes a bottom silicon 101, an insulating layer 102 and a top silicon 103 arranged in sequence from bottom to top, and the centers of the insulating layer 102 and the bottom silicon 101 are hollow structures.
[0065] In this embodiment, by forming a three-level stepped structure, the area of the effective feedback region can be increased, the signal collection efficiency can be improved, and the strength of the feedback signal can be increased, making the feedback signal more sensitive and easier to detect; by optimizing the distribution of piezoelectric materials, the control accuracy of the micromirror is improved, the driving efficiency is improved, and the micromirror can respond to changes in electrical signals more efficiently; a hollow structure is formed at the center of the bottom silicon 101 and the insulating layer 102 of the SOI substrate 1, which can improve the heat dissipation efficiency of the piezoelectric MEMS micromirror, reduce heat accumulation, extend the service life, reduce the overall weight, reduce inertia, and help improve the response speed and mechanical properties.
[0066] Specifically, based on the existing process flow, the present application changes the structure so that the piezoelectric MEMS micromirror can obtain a more sensitive feedback signal when working, and correct its own state in real time, thereby increasing the sensitivity of the device feedback from 1-3mV / ° to 10-30mV / °.
[0067] Furthermore, the first metal layer 201, the first piezoelectric material layer 202 and the second metal layer 203 constitute a piezoelectric driving layer, and an excitation voltage is applied through the first metal layer 201 and the second metal layer 203 to cause the first piezoelectric material layer 202 to deform; the second metal layer 203, the second piezoelectric material layer 204 and the third metal layer 205 constitute a piezoelectric self-feedback layer, and the second piezoelectric material layer 204 is deformed based on the deformation of the first piezoelectric material layer 202, thereby generating a potential difference and generating a self-feedback signal, and the self-feedback signal is output through the second metal layer 203 and the third metal layer 205.
[0068] In this embodiment, if Figure 6As shown, the first metal layer 201, the first piezoelectric material layer 202 and the second metal layer 203 constitute a piezoelectric driving layer. The excitation voltage V1 is applied through the first metal layer 201 and the second metal layer 203 to cause the first piezoelectric material layer 202 to warp, thereby driving the flipping and rotation of the device. The piezoelectric self-feedback layer utilizes the positive piezoelectric effect. The deformation of the first piezoelectric material layer 202 in the lower piezoelectric driving layer is driven to deform the second piezoelectric material layer 204 in the piezoelectric self-feedback layer. Due to the deformation of the second piezoelectric material layer 204, an electric potential difference is formed on the upper and lower surfaces. The self-feedback signal V2 can be read out through the second metal layer 203 and the third metal layer 205 electrodes. Based on the overall structure of the piezoelectric MEMS micromirror provided in the present application, the coverage area of the piezoelectric self-feedback layer can be maximized, thereby improving the detection sensitivity of the device.
[0069] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A method for manufacturing a piezoelectric MEMS micromirror, characterized in that: include: Making SOI substrate; Depositing multiple metal layers and multiple piezoelectric material layers on the SOI substrate to form a multi-layer stacked structure, and etching the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape; Deep silicon etching is performed on a side of the SOI substrate away from the multi-layer stacking structure, so that the SOI substrate forms a hollow structure.
2. The method for manufacturing a piezoelectric MEMS micromirror according to claim 1, characterized in that: The SOI substrate comprises a bottom silicon layer, an insulating layer and a top silicon layer arranged in sequence from bottom to top; The method for preparing the SOI substrate comprises: Selecting a silicon wafer as the bottom silicon of the SOI substrate; Forming a layer of silicon oxide on the upper surface of the bottom silicon by a thermal oxidation process as an insulating layer of the SOI substrate; When the preset temperature is reached, another silicon wafer is bonded to the insulating layer to form a top silicon layer of the SOI substrate, and the top silicon layer is polished to a preset thickness.
3. The method for manufacturing a piezoelectric MEMS micromirror according to claim 1, characterized in that: The method of depositing multiple metal layers and multiple piezoelectric material layers on the SOI substrate to form a multi-layer stacked structure comprises: A first metal layer, a first piezoelectric material layer, a second metal layer, a second piezoelectric material layer and a third metal layer are sequentially deposited on the SOI substrate from bottom to top to form a multi-layer stacked structure.
4. The method for manufacturing a piezoelectric MEMS micromirror according to claim 3, characterized in that: The piezoelectric materials in the first piezoelectric material layer and the second piezoelectric material layer include barium titanate, lead zirconate titanate, modified lead zirconate titanate, lead metaniobate, barium lithium lead niobate and modified lead titanate.
5. The method for manufacturing a piezoelectric MEMS micromirror according to claim 3, characterized in that: The first metal layer, the second metal layer and the third metal layer are deposited by magnetron sputtering or metal evaporation; The first piezoelectric material layer and the second piezoelectric material layer are deposited by magnetron sputtering or sol-gel method.
6. The method for manufacturing a piezoelectric MEMS micromirror according to claim 3, characterized in that: The etching of the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape comprises: The multi-layer stacked structure is etched by dry etching or wet etching, so that the multi-layer stacked structure is in a step shape.
7. The method for manufacturing a piezoelectric MEMS micromirror according to claim 3 or 6, characterized in that: The etching of the multi-layer stacked structure so that the multi-layer stacked structure is in a stepped shape further comprises: Etching the first piezoelectric material layer and the second metal layer respectively so that the first piezoelectric material layer and the second metal layer have the same length, wherein the length of the second metal layer is less than the length of the first metal layer; The second piezoelectric material layer and the third metal layer are etched respectively so that the second piezoelectric material layer and the third metal layer have the same length, wherein the length of the third metal layer is less than that of the second metal layer.
8. The method for manufacturing a piezoelectric MEMS micromirror according to claim 1, characterized in that: The step of performing deep silicon etching on a side of the SOI substrate away from the multi-layer stack structure so that the SOI substrate forms a hollow structure includes: The top silicon layer of the SOI substrate is retained, and deep silicon etching is performed on the bottom silicon layer and the insulating layer located at the center of the SOI substrate, so that the SOI substrate forms a hollow structure.
9. A piezoelectric MEMS micromirror, characterized in that: The piezoelectric MEMS micromirror is manufactured based on the manufacturing method of any one of claims 1 to 8, comprising an SOI substrate and a multi-layer stacking structure; The multi-layer stacked structure is arranged on the upper surface of the SOI substrate, and the multi-layer stacked structure includes a first metal layer, a first piezoelectric material layer, a second metal layer, a second piezoelectric material layer and a third metal layer arranged in sequence from bottom to top, wherein the length of the third metal layer is less than the length of the second metal layer, the length of the second metal layer is less than the length of the first metal layer, and the length of the first piezoelectric material layer is the same as that of the second metal layer, and the length of the second piezoelectric material layer is the same as that of the third metal layer; The SOI substrate comprises a bottom silicon layer, an insulating layer and a top silicon layer which are arranged in sequence from bottom to top, and the centers of the insulating layer and the bottom silicon layer are hollow structures.
10. The piezoelectric MEMS micromirror according to claim 9, characterized in that: The first metal layer, the first piezoelectric material layer and the second metal layer constitute a piezoelectric driving layer, and an excitation voltage is applied through the first metal layer and the second metal layer to cause the first piezoelectric material layer to deform; The second metal layer, the second piezoelectric material layer and the third metal layer constitute a piezoelectric self-feedback layer. The second piezoelectric material layer deforms based on the deformation of the first piezoelectric material layer, thereby generating an electric potential difference and generating a self-feedback signal, and outputting the self-feedback signal through the second metal layer and the third metal layer.