Method for manufacturing a MEMS acoustic sensor
By using photolithography and gas pressure to form an arched polymer layer during the fabrication of MEMS acoustic sensors, the problems of alignment accuracy and reliability were solved, enabling the fabrication of high-precision and high-reliability MEMS acoustic sensors, simplifying the process and reducing costs.
Patent Information
- Application Number
- CN202310148526.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-20
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2043-02-20
AI Technical Summary
Existing MEMS acoustic sensors suffer from low alignment accuracy and low reliability during manufacturing, resulting in poor sensor consistency and low yield.
By sequentially stacking structural layers and piezoelectric material layers on a substrate, and using photolithography to create grooves, etching to form cavities, and using a jig and air pressure to form an arched polymer layer, the deformation and bonding of the polymer layer are achieved by combining temperature and air pressure control. Finally, wafer dicing is performed to fabricate a MEMS acoustic sensor.
It improves processing accuracy and reliability, reduces costs, simplifies processes, and increases yield and repeatability.
Smart Images
Figure CN116199180B_ABST
Abstract
Description
[0001] The present application relates to the technical field of MEMS manufacturing, and particularly relates to a MEMS acoustic sensor manufacturing method.
[0002] MEMS acoustic sensors are widely used in portable mobile electronic products, such as mobile phones, to realize conversion of audio signals into sound playing. Miniaturization of portable mobile electronic products drives miniaturization of MEMS acoustic sensors more and more widely.
[0003] In the related art, a MEMS acoustic sensor includes a substrate enclosing a cavity and having two ends open, a cantilever beam bent and extended from one end of the substrate to the cavity, a piezoelectric driver fixed to a side of the cantilever beam away from the cavity, and an elastic connecting piece made of a polymer layer. The cantilever beam includes a plurality of cantilever beams spaced from each other, and a structural gap is formed between two adjacent cantilever beams. The elastic connecting piece completely covers the cantilever beam, the piezoelectric driver, and the cavity and is attached to the cantilever beam and the piezoelectric driver. The elastic connecting piece, the cantilever beam, and the piezoelectric driver together form a piezoelectric composite vibration diaphragm structure for vibration sound production. The MEMS acoustic sensor of the related art seals the structural gap through the elastic connecting piece, so that short circuit does not occur when the MEMS acoustic sensor produces sound or detects sound pressure. The part of the elastic connecting piece opposite to the structural gap is in an arch shape. Since the arch has low bending stiffness, the vibration of the arch design can minimize the vibration limitation of the cantilever beam or other forms of drivers, and improve the sound production or detection sensitivity.
[0004] However, in the manufacturing of the MEMS acoustic sensor of the related art, the arch part of the elastic connecting piece is generally made separately in advance. The manufacturing method generally prepares a thin film piece with a certain 3D structure through hot pressing of a high polymer planar film or through mold injection, and the thin film piece is attached to the surface of the prepared driver (i.e., covering the structural gap) through mechanical equipment. However, the MEMS acoustic sensor of the related art has the following problems in manufacturing: first, the alignment accuracy is not high. The traditional mechanical alignment accuracy cannot be compared with the MEMS processing accuracy, resulting in low consistency of the MEMS acoustic sensor. Second, the attached parts are extremely fragile (all in micrometer level), and the cantilever structure cannot withstand the force during attachment, resulting in a very low yield.
[0005] Therefore, it is necessary to provide a new method to solve the above technical problems.
[0006] The present application relates to the technical field of MEMS manufacturing, and particularly relates to a MEMS acoustic sensor manufacturing method.
[0007] To achieve the above objectives, the present invention provides 1. a method for fabricating a MEMS acoustic sensor, the method comprising the following steps:
[0008] A substrate is provided, wherein a structural layer and a piezoelectric material layer are sequentially stacked on one side of the substrate;
[0009] The piezoelectric material layer and the structural layer are sequentially shaped by photolithography to generate a first groove penetrating the piezoelectric material layer and a second groove penetrating the structural layer, respectively; the first groove and the second groove are directly opposite each other and communicate with each other to form a structural gap;
[0010] A polymer layer is stacked on the side of the piezoelectric material layer away from the substrate, and the polymer layer completely covers the first groove;
[0011] The substrate is etched from the side away from the piezoelectric material layer toward the piezoelectric material layer to form a cavity through it. The structural layer is covered on the side of the substrate near the piezoelectric material layer and the second groove communicates with the cavity.
[0012] A first part of a prefabricated fixture is stacked on the polymer layer on the side away from the substrate. The first part has an arched groove, which is aligned with the structural gap. The fixture, the substrate, the piezoelectric material layer, and the polymer layer are then heated together to a first temperature to make the polymer layer rubbery. The first part also has a first vent hole that connects the arched groove to the outside. The first temperature is the glass transition temperature of the polymer layer.
[0013] Gas at a preset pressure is blown into the cavity, and the pressure inside the cavity is controlled to reach a preset value, so that the polymer layer facing the arched groove deforms and adheres to the inner wall of the arched groove to form an arched part.
[0014] Maintain the gas pressure load and cool it below the first temperature to make the polymer layer glassy;
[0015] Stop controlling the air pressure in the cavity and reduce the air pressure, disassemble the fixture, and then cut the wafer according to the preset shape to obtain the MEMS acoustic sensor.
[0016] Preferably, the substrate is an SOI wafer or a silicon wafer, and the piezoelectric material layer includes at least one layer of piezoelectric material and upper and lower electrodes respectively attached to opposite sides of the piezoelectric material.
[0017] Preferably, the piezoelectric material is any one of PZT, AlN, AlScN, and ZnO.
[0018] Preferably, the polymer layer is any one of PEEK, PEI, PI, and PEN.
[0019] Preferably, the gas blown into the cavity at a preset pressure specifically includes:
[0020] The second part of the fixture is stacked on the side of the substrate away from the piezoelectric material layer and completely covers the cavity; the second part is provided with a second vent hole through it, so that the cavity is connected to the second vent hole, and air is blown into the cavity through the second vent hole.
[0021] Preferably, both the first groove and the second groove include multiple grooves, and they are arranged in a one-to-one correspondence.
[0022] Preferably, the polymer layer is in the form of a block and completely covers the structural gaps.
[0023] Preferably, the width of the arched groove is the same as the width of the structural gap.
[0024] Compared with the prior art, the MEMS acoustic sensor fabrication method of the present invention preferably provides a substrate, and sequentially stacks a structural layer and a piezoelectric material layer on one side of the substrate; sequentially performs photolithography on the piezoelectric material layer and the structural layer to form a first groove penetrating the piezoelectric material layer and a second groove penetrating the structural layer, respectively; stacks a polymer layer on the side of the piezoelectric material layer away from the substrate, and makes the polymer layer completely cover the first groove; etches the substrate from the side away from the piezoelectric material layer toward the direction closer to the piezoelectric material layer, so that the substrate forms a cavity penetrating therethrough, and the structural layer covers the side of the substrate near the piezoelectric material layer, so that the second groove communicates with the cavity; and stacks the first part of a pre-fabricated fixture on the substrate. The polymer layer is located away from the substrate. The first portion has an arched groove, which is aligned with the structural gap. The fixture, substrate, piezoelectric material layer, and polymer layer are heated together to a first temperature to make the polymer layer rubbery. Gas at a preset pressure is blown into the cavity, and the pressure inside the cavity is controlled to reach a preset value, causing the portion of the polymer layer facing the arched groove to deform and adhere to the inner wall of the arched groove to form an arched portion. The gas pressure load is maintained, and the temperature is lowered to below the first temperature to make the polymer layer glassy. The pressure control inside the cavity is stopped and the pressure is reduced. The fixture is disassembled, and the wafer is cut according to a preset shape to obtain the MEMS acoustic sensor. The above steps utilize the dramatic changes in the mechanical properties of the polymer layer at a first temperature, combined with the control of temperature and air pressure loads, to achieve the fabrication of a 3D morphology. Since traditional assembly processes are not used in the process, it features high alignment accuracy, high yield, good repeatability, low cost, and simple process; thus, the MEMS acoustic sensor fabrication method of the present invention can effectively improve processing accuracy and high reliability. [Attached Image Description]
[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of 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.
[0026] Figure 1 This is a flowchart of the MEMS acoustic sensor fabrication method of the present invention;
[0027] Figure 2 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S1 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0028] Figure 3 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S2 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0029] Figure 4 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S3 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0030] Figure 5 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S4 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0031] Figure 6 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S5 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0032] Figure 7 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S6 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0033] Figure 8 This is a schematic diagram of the structure of the MEMS acoustic sensor completed in step S8 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0034] Figure 9 This is a three-dimensional structural diagram of the MEMS acoustic sensor completed in step S8 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0035] Figure 10 This is a partial three-dimensional exploded view of the MEMS acoustic sensor completed in step S8 of the first embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0036] Figure 11 for Figure 9 Anatomical diagram along the BB direction;
[0037] Figure 12 This is a three-dimensional structural diagram of the MEMS acoustic sensor completed in step S8 of the second embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0038] Figure 13 This is a partial three-dimensional exploded view of the MEMS acoustic sensor completed in step S8 of the second embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0039] Figure 14A three-dimensional structural diagram of the MEMS acoustic sensor completed in step S8 of the third embodiment of the MEMS acoustic sensor fabrication method of the present invention.
[0040] Figure 15 This is a partial three-dimensional exploded view of the MEMS acoustic sensor completed in step S8 of the third embodiment of the MEMS acoustic sensor fabrication method of the present invention.
Detailed Implementation Methods
[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0042] (First Embodiment)
[0043] This invention provides a method for fabricating a MEMS acoustic sensor. Please also refer to... Figures 1-11 As shown in the figure, in this embodiment, the MEMS acoustic sensor fabrication method is used to fabricate a MEMS acoustic sensor 100.
[0044] Please refer to Figure 1 As shown, specifically, the MEMS acoustic sensor fabrication method includes the following steps:
[0045] Step S1: Provide a substrate 1, and sequentially stack a structural layer 2 and a piezoelectric material layer 3 on one side of the substrate 1.
[0046] In step S1, the substrate 1 is an SOI wafer or a silicon wafer.
[0047] The piezoelectric material layer 3 includes at least one layer of piezoelectric material and upper and lower electrodes respectively attached to opposite sides of the piezoelectric material. The piezoelectric material is any one of PZT, AlN, AlScN and ZnO.
[0048] Step S2: Perform photolithography on the piezoelectric material layer 3 and the structural layer 2 in sequence to generate a first groove 31 penetrating the piezoelectric material layer 3 and a second groove 21 penetrating the structural layer 2, respectively.
[0049] The first groove 31 and the second groove 21 are directly opposite each other and communicate with each other to form a structural gap 4.
[0050] The first groove 31 is used to form the main structure of the piezoelectric actuator of the MEMS acoustic sensor 100 by forming the piezoelectric material layer 3.
[0051] Step S3: Stack a polymer layer 5 on the side of the piezoelectric material layer 3 away from the substrate 1, and make the polymer layer 5 completely cover the first groove 31.
[0052] In this embodiment, the polymer layer 5 is any one of PEEK, PEI, PI and PEN.
[0053] In this embodiment, the polymer layer 5 is in the shape of a block that matches the shape of the piezoelectric material layer 3.
[0054] It should be noted that the MEMS acoustic sensor fabrication method may have different variations in the preparation of the main structure of the piezoelectric actuator in steps S1 and S2. For example, the upper electrode may be fabricated after the preparation in step S2, to ensure that the shape of the vibration structure and functional layer composed of the piezoelectric material layer 3 and the structural layer 2 is completed before the start of step S3.
[0055] Step S4: The substrate 1 is etched from the side away from the piezoelectric material layer 3 toward the side closer to the piezoelectric material layer 3, so that a cavity 10 is formed through the substrate 1. The structural layer 2 is covered on the side of the substrate 1 closer to the piezoelectric material layer 3 and the second groove 21 is connected to the cavity 10.
[0056] After step S4 is performed, the vibration structure formed by the piezoelectric material layer 3 and the structural layer 2 can be released for vibration. Before step S4 is performed, step S3 is required to attach the polymer layer 5 to the piezoelectric material layer 3. If the cavity 10 is etched out before attaching the polymer layer 5, the success rate of attachment and fixation will be low because the cantilever beam structure formed by etching the piezoelectric material layer 3 is completely non-resistant.
[0057] Step S5: The first portion 201 of the prefabricated fixture 200 is stacked on the side of the polymer layer 5 away from the substrate 1. The first portion 201 has an arched groove 2011, which is aligned with the structural gap 4. Then, the fixture 200, the substrate 1, the piezoelectric material layer 3, and the polymer layer 5 are heated together to a first temperature Tg to make the polymer layer 5 rubbery. The rubbery state refers to the state in which the polymer layer 5 has a low Young's modulus and is easily deformed.
[0058] The first part 201 is further provided with a first vent 2012 extending through it, which connects the arched groove 2011 to the outside. The first temperature Tg is the glass transition temperature of the polymer layer 5.
[0059] In this embodiment, the width of the arched groove 2011 is greater than or equal to the width of the structural gap 4. This structure is beneficial for improving the performance of the MEMS acoustic sensor 100.
[0060] Step S6: Gas at a preset pressure is blown into the cavity 10, and the pressure in the cavity 10 is controlled to reach the preset value, so that the polymer layer 5 is deformed in the part facing the arched groove 2011 to form an arched part 51 that matches the shape of the arched groove 2011.
[0061] In this embodiment, the gas blown into the cavity 10 at a preset pressure specifically includes:
[0062] The second part 202 of the fixture 200 is stacked on the side of the substrate 1 away from the piezoelectric material layer 3 and completely covers the cavity 10.
[0063] The second part 202 has a second vent 2021 extending through it, allowing the cavity 10 to communicate with the second vent 2021, through which air is blown into the cavity 10. The preset air pressure value is closely related to the final arch height of the arched portion 51. Alternatively, in another embodiment, the second part 202 is omitted, meaning the fixture 200 only has the first part 201. In this case, a specific arch shape can be prepared as long as the air pressure is high enough. The arched portion 51 of the molding fixture for the polymer layer 5 needs to have a certain number of small holes to allow for deformation of the polymer layer 5. Simultaneously, areas outside the arched portion 51 can be partially contacted to reduce adhesion between the mold and the polymer layer 5 after the process is completed.
[0064] In this embodiment, the structural gap 4 and the second vent 2021 are both positioned opposite each other. Because the arched portion 51 has low stiffness, meaning the arched portion 51 of the polymer layer 5 is positioned opposite the structural gap 4, this structure can prevent sound leakage without excessively interfering with its vibration. Conversely, if the polymer layer 5 were laid flat at the structural gap 4, the vibration of the MEMS acoustic sensor 100 would be greatly limited, reducing its sensitivity.
[0065] Step S7: Maintain the gas pressure load and cool it down to below the first temperature Tg so that the polymer layer 5 is in a glassy state.
[0066] Step S8: Stop controlling the air pressure in the cavity 10 and reduce the air pressure, disassemble the fixture 200, and then cut the wafer according to the preset shape to obtain the MEMS acoustic sensor 100.
[0067] The MEMS acoustic sensor 100 can be manufactured by performing steps 1 to S8. Please also refer to... Figures 9-11 As shown,
[0068] Specifically, the MEMS acoustic sensor 100 includes a substrate 1 that forms a cavity 10 and is open at both ends, a structural layer 2 that extends from one end of the substrate 1 into the cavity 10 and is at least partially suspended above the cavity 10, a piezoelectric material layer 3 that is fixed to the side of the cantilever beam away from the cavity 10, and a polymer layer 5.
[0069] The structural layer 2 has a through-hole 4; the structural gap 4 communicates with the cavity 10. The structural layer 2 is used to form a cantilever arm. The piezoelectric material layer 3 is used to form a piezoelectric actuator.
[0070] The polymer layer 5 completely covers the structural layer 2, the piezoelectric material layer 3, and the cavity 10 and is attached to the structural layer 2 and the piezoelectric material layer 3; the portion of the polymer layer 5 facing the structural gap 4 is recessed away from the cavity 10 to form an arc-shaped arch 51.
[0071] In this embodiment, the polymer layer 5 is block-shaped and completely covers the structural gap 4. The polymer layer 5 is block-shaped and matches the piezoelectric material layer 3. This structure is compact, easy to manufacture, and highly reliable.
[0072] (Second Embodiment)
[0073] The second embodiment of the present invention uses a MEMS acoustic sensor fabrication method to fabricate a MEMS acoustic sensor 100a.
[0074] The MEMS acoustic sensor 100a of the second embodiment of the present invention is basically the same as the MEMS acoustic sensor 100 of the first embodiment of the present invention. The difference between the MEMS acoustic sensor 100a of the second embodiment of the present invention and the MEMS acoustic sensor 100 is as follows:
[0075] Please also refer to Figures 12-13 As shown, in step S3, the shape of the arched portion 51a matches the shape of the structural gap 4a. That is, the structural gap 4a only needs to cover the arched portion 51a; the polymer layer 5 of the MEMS acoustic sensor 100 of the first embodiment of the present invention does not need to fully cover the piezoelectric material layer 3. Simply covering the structural gap 4a forms the MEMS acoustic sensor 100a of the second embodiment of the present invention. This structure uses less material, reduces weight, and is beneficial for the miniaturization of the MEMS acoustic sensor 100a.
[0076] The MEMS acoustic sensor fabrication method provided in the second embodiment of the present invention can realize the various implementation methods and corresponding beneficial effects of the MEMS acoustic sensor fabrication method in the first embodiment of the present invention. To avoid repetition, it will not be described again here.
[0077] (Third Embodiment)
[0078] The third embodiment of the present invention uses a MEMS acoustic sensor fabrication method to fabricate a MEMS acoustic sensor 100b.
[0079] The MEMS acoustic sensor 100b of the third embodiment of the present invention is basically the same as the MEMS acoustic sensor 100 of the first embodiment of the present invention. The difference between the MEMS acoustic sensor 100b of the third embodiment of the present invention and the MEMS acoustic sensor 100 is as follows:
[0080] Please also refer to Figures 12-13 As shown, both the first groove 31 and the second groove 21 include multiple grooves, which are arranged in a one-to-one correspondence. In step S2, the piezoelectric material layer 3b forms multiple cantilever beams that are spaced apart from each other. A first structural gap 41 is formed between two adjacent cantilever beams. The multiple cantilever beams are each located at one end of the outer portion of the piezoelectric material layer 3b that is close to each other and are spaced apart from each other, together forming a second structural gap 42. The first structural gap 41 and the second structural gap 42 are connected and together form the structural gap 4b. The second structural gap 42 is located in the central region of the cavity 10b, and the structural gap 4b is connected to the cavity 10b.
[0081] The arched portion 51b includes a first arched portion 511 and a second arched portion 512 in an annular shape. The shape of the first arched portion 511 matches the shape of the first structural gap 41, and the second arched portion 512 is positioned opposite to the second structural gap 42.
[0082] This structure allows the arched portion 51b to be arranged without strictly conforming to the shape of the structural gap 4b. The surface of the piezoelectric material layer 3b near the second structural gap 42 is relatively narrow, preventing the arched portion 51b from being adhered to it during molding, thus forming the 3D shape of the second arched portion 512. This structure of the second arched portion 512 facilitates the piezoelectric material layer 3b in fulfilling its function as a vibration structure for the catenary arm. Furthermore, whether or not to fabricate an arched 3D structure on the structural gap 4b is optional. If not, the corresponding part in the molding fixture will not have an arched shape, thereby achieving a specific desired 3D shape.
[0083] The MEMS acoustic sensor fabrication method provided in the third embodiment of the present invention can realize the various implementation methods and corresponding beneficial effects of the MEMS acoustic sensor fabrication method in the first embodiment of the present invention. To avoid repetition, it will not be described again here.
[0084] The embodiments described in this invention are for ease of explanation. The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Therefore, equivalent variations made according to the claims of this invention are still within the scope of this invention.
[0085] Compared with the prior art, the MEMS acoustic sensor fabrication method of the present invention preferably provides a substrate, and sequentially stacks a structural layer and a piezoelectric material layer on one side of the substrate; sequentially performs photolithography on the piezoelectric material layer and the structural layer to form a first groove penetrating the piezoelectric material layer and a second groove penetrating the structural layer, respectively; stacks a polymer layer on the side of the piezoelectric material layer away from the substrate, and makes the polymer layer completely cover the first groove; etches the substrate from the side away from the piezoelectric material layer toward the direction closer to the piezoelectric material layer, so that the substrate forms a cavity penetrating therethrough, and the structural layer covers the side of the substrate near the piezoelectric material layer, so that the second groove communicates with the cavity; and stacks the first part of a pre-fabricated fixture on the substrate. The polymer layer is located away from the substrate. The first portion has an arched groove, which is aligned with the structural gap. The fixture, the substrate, the piezoelectric material layer, and the polymer layer are heated together to a first temperature to make the polymer layer rubbery. Gas at a preset pressure is blown into the cavity, and the pressure in the cavity is controlled to reach a preset value, causing the portion of the polymer layer facing the arched groove to deform and adhere to the inner wall of the arched groove to form an arched portion. The gas pressure load is maintained, and the temperature is lowered to below the first temperature to make the polymer layer glassy. The pressure control in the cavity is stopped and the pressure is reduced. The fixture is disassembled, and the wafer is cut according to a preset shape to obtain the MEMS acoustic sensor. The above steps utilize the dramatic changes in the mechanical properties of the polymer layer at a first temperature, combined with the control of temperature and air pressure loads, to achieve the fabrication of a 3D morphology. Since traditional assembly processes are not used in the process, it features high alignment accuracy, high yield, good repeatability, low cost, and simple process; thus, the MEMS acoustic sensor fabrication method of the present invention can effectively improve processing accuracy and high reliability.
[0086] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for fabricating a MEMS acoustic sensor, characterized in that, The method includes the following steps: A substrate is provided, wherein a structural layer and a piezoelectric material layer are sequentially stacked on one side of the substrate; The piezoelectric material layer and the structural layer are sequentially shaped by photolithography to generate a first groove penetrating the piezoelectric material layer and a second groove penetrating the structural layer, respectively; the first groove and the second groove are directly opposite each other and communicate with each other to form a structural gap; A polymer layer is stacked on the side of the piezoelectric material layer away from the substrate, and the polymer layer completely covers the first groove; The substrate is etched from the side away from the piezoelectric material layer toward the piezoelectric material layer to form a cavity through it. The structural layer is covered on the side of the substrate near the piezoelectric material layer and the second groove communicates with the cavity. A first part of a prefabricated fixture is stacked on the polymer layer on the side away from the substrate. The first part has an arched groove, which is aligned with the structural gap. The fixture, the substrate, the piezoelectric material layer, and the polymer layer are then heated together to a first temperature to make the polymer layer rubbery. The first part also has a first vent hole that connects the arched groove to the outside. The first temperature is the glass transition temperature of the polymer layer. Gas at a preset pressure is blown into the cavity, and the pressure inside the cavity is controlled to reach a preset value, so that the polymer layer facing the arched groove deforms and adheres to the inner wall of the arched groove to form an arched part. Maintain the gas pressure load and cool it below the first temperature to make the polymer layer glassy; Stop controlling the air pressure in the cavity and reduce the air pressure, disassemble the fixture, and then cut the wafer according to the preset shape to obtain the MEMS acoustic sensor.
2. The method for fabricating a MEMS acoustic sensor according to claim 1, characterized in that, The substrate is an SOI wafer or a silicon wafer, and the piezoelectric material layer includes at least one layer of piezoelectric material and upper and lower electrodes respectively attached to opposite sides of the piezoelectric material.
3. The method for fabricating a MEMS acoustic sensor according to claim 1, characterized in that, The piezoelectric material is any one of PZT, AlN, AlScN, and ZnO.
4. The method for fabricating a MEMS acoustic sensor according to claim 1, characterized in that, The polymer layer is any one of PEEK, PEI, PI, and PEN.
5. The method for fabricating a MEMS acoustic sensor according to claim 1, characterized in that, The gas blown into the cavity at a preset pressure specifically includes: The second part of the fixture is stacked on the side of the substrate away from the piezoelectric material layer and completely covers the cavity; the second part is provided with a second vent hole through it, so that the cavity is connected to the second vent hole, and air is blown into the cavity through the second vent hole.
6. The method for fabricating a MEMS acoustic sensor according to claim 1, characterized in that, Both the first groove and the second groove include multiple grooves, and they are arranged in a one-to-one correspondence.
7. The method for fabricating a MEMS acoustic sensor according to claim 6, characterized in that, The polymer layer is blocky and completely covers the gaps in the structure.
8. The method for fabricating a MEMS acoustic sensor according to claim 6, characterized in that, The width of the arched groove is greater than or equal to the width of the structural gap.
Citation Information
Patent Citations
MEMS loudspeaker and MEMS loudspeaker manufacturing method
CN113365196A
Microchannel fabrication
US20040046290A1