Piezoelectric MEMS device and preparation method thereof

Abstract

The invention provides a piezoelectric MEMS device and a preparation method thereof, and relates to the technical field of semiconductors. The piezoelectric MEMS device comprises a first vibration layer, an electrode layer and a second vibration layer, the electrode layer and the second vibration layer are arranged on the first vibration layer, the electrode layer is provided with a first electrode surface and a second electrode surface which are opposite in a preset direction, and an electrode side face connected with the first electrode surface and the second electrode surface. The outer contour of the orthographic projection of the electrode side face on the first vibration layer is located in the outer contour of the surface, facing the electrode layer, of the first vibration layer, the first vibration layer completely covers the first electrode surface, and the second vibration layer completely covers the second electrode surface and the electrode side face. According to the piezoelectric MEMS device, the first vibration layer and the second vibration layer are arranged on the two sides of the electrode layer respectively, all the exposed faces of the electrode layer are wrapped by the first vibration layer and the second vibration layer, and all-dimensional anti-corrosion protection of the electrode layer is achieved. Therefore, the piezoelectric MEMS device can prevent the electrode layer from being corroded, and has relatively long service life.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and more particularly, to a piezoelectric MEMS device and a method for manufacturing the same. Background Art

[0002] Please refer to Figure 1 , the piezoelectric structure 10 generally includes at least two electrode layers 11 and a piezoelectric layer 12 located between two adjacent electrode layers 11. Please refer to Figure 2 and Figure 3 , when the piezoelectric structure 10 is applied to a diaphragm-type device, the surfaces of the top electrode layer 11a and the bottom electrode layer 11b facing away from each other can be in direct contact with the application environment respectively (as indicated by the straight arrows in Figure 3 ). Please refer to Figure 4 and Figure 5 , when a through hole 13 is provided in the piezoelectric structure 10 to penetrate the piezoelectric structure 10, then the surfaces of the top electrode layer 11a and the bottom electrode layer 11b facing away from each other, and the side surfaces of the top electrode layer 11a, the bottom electrode layer 11b and the middle electrode layer 11c (if any) at the through hole 13 can all be in direct contact with the application environment (as indicated by the straight arrows in Figure 5 ). The electrode layer 11 being exposed to the application environment for a long time will be corroded to varying degrees, thus reducing the service life of the diaphragm-type device. Summary of the Invention

[0003] The purpose of the present application is to provide, in view of the above deficiencies in the prior art, a piezoelectric MEMS device and a method for manufacturing the same, which can prevent the electrode layer from being corroded and have a relatively high service life.

[0004] To achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

[0005] On the one hand, an embodiment of the present application provides a piezoelectric MEMS device, including: a first vibration layer, an electrode layer disposed on the first vibration layer along a preset direction, and a second vibration layer. The electrode layer has a first electrode surface and a second electrode surface opposite to each other in the preset direction, and an electrode side surface connecting the first electrode surface and the second electrode surface. The outer contour of the orthographic projection of the electrode side surface on the first vibration layer is located within the outer contour of the surface of the first vibration layer facing the electrode layer. The first vibration layer completely covers the first electrode surface, and the second vibration layer completely covers the second electrode surface and the electrode side surface.

[0006] Optionally, the included angle between the electrode side surface and the first vibration layer is an acute angle, and the area of the first electrode surface is larger than the area of the second electrode surface.

[0007] Optionally, through holes are provided in the piezoelectric MEMS device, the through holes penetrate two opposite surfaces of the piezoelectric MEMS device in a preset direction, and there is no overlapping area between the outer contour of the orthographic projection of the through holes on the first vibration layer and the outer contour of the orthographic projection of the electrode layer on the first vibration layer.

[0008] Optionally, the electrode layer is a top electrode layer, the first vibration layer is a piezoelectric layer, and the second vibration layer is a barrier layer.

[0009] Optionally, the electrode layer is a bottom electrode layer, the first vibration layer is a barrier layer, and the second vibration layer is a piezoelectric layer.

[0010] Optionally, the electrode layer is a middle electrode layer, and both the first vibration layer and the second vibration layer are piezoelectric layers.

[0011] Optionally, a base layer is further included, the first vibration layer is disposed on the base layer, a back cavity is provided on the base layer, and the back cavity penetrates two opposite surfaces of the base layer in a preset direction.

[0012] On the other hand, an embodiment of the present application provides a method for manufacturing a piezoelectric MEMS device, including: providing a first vibration layer, and forming an electrode layer on the surface of the first vibration layer, wherein the electrode layer has a first electrode surface completely covered by the first vibration layer and a second electrode surface facing away from the first vibration layer, and an electrode side surface connecting the first electrode surface and the second electrode surface, and the outer contour of the orthographic projection of the electrode side surface of the electrode layer on the first vibration layer is located within the outer contour of the surface of the first vibration layer facing the electrode layer; forming a second vibration layer on the side of the electrode layer facing away from the first vibration layer, wherein the second vibration layer completely covers the second electrode surface and the electrode side surface.

[0013] Optionally, providing a first vibration layer and forming an electrode layer on the surface of the first vibration layer includes: providing a first vibration layer, and depositing a layer of electrode material on the surface of the first vibration layer to form a complete electrode film layer; etching the electrode film layer to remove part of the electrode material to form an electrode layer; forming a second vibration layer on the side of the electrode layer facing away from the first vibration layer includes: depositing a layer of second material on the second electrode surface and the surface of the first vibration layer exposed by the electrode layer to form a second vibration layer.

[0014] Optionally, etching the electrode film layer to remove part of the electrode material to form an electrode layer includes: performing a gentle slope etching on the electrode film layer to remove part of the electrode material to form an electrode layer having an inclined electrode side surface, wherein the included angle between the electrode side surface and the first vibration layer is an acute angle, and the area of the first electrode surface is larger than the area of the second electrode surface.

[0015] Optionally, after forming a second vibration layer on a side of the electrode layer facing away from the first vibration layer, the method further includes: forming a through hole on a surface of the second vibration layer facing away from the electrode layer, wherein the through hole penetrates through the second vibration layer, the electrode layer, and the first vibration layer, and an outer contour of a positive projection of the through hole on the first vibration layer has no overlapping region with an outer contour of a positive projection of the electrode layer on the first vibration layer.

[0016] Optionally, providing the first vibration layer includes: providing a base layer, and forming the first vibration layer on the base layer; after forming the second vibration layer on a side of the electrode layer facing away from the first vibration layer, the method further includes: forming a back cavity on a surface of the base layer facing away from the first vibration layer, wherein the back cavity penetrates through two opposite surfaces of the base layer.

[0017] The beneficial effects of the present application include:

[0018] The present application provides a piezoelectric MEMS device, including: a first vibration layer, an electrode layer disposed on the first vibration layer along a preset direction, and a second vibration layer. The electrode layer has a first electrode surface and a second electrode surface opposite to each other in the preset direction, and an electrode side surface connecting the first electrode surface and the second electrode surface. An outer contour of a positive projection of the electrode side surface on the first vibration layer is located within an outer contour of a surface of the first vibration layer facing the electrode layer. The first vibration layer completely covers the first electrode surface, and the second vibration layer completely covers the second electrode surface and the electrode side surface. The above piezoelectric MEMS device is provided with the first vibration layer and the second vibration layer on both sides of the electrode layer respectively, and the first vibration layer and the second vibration layer cooperate to completely wrap all exposed surfaces of the electrode layer, thereby achieving all-round anti-corrosion protection for the electrode layer. Therefore, the above piezoelectric MEMS device can prevent the electrode layer from being corroded and has a relatively high service life. Description of the Drawings

[0019] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 is a schematic structural diagram of a piezoelectric structure in the prior art;

[0021] Figure 2 is one of the top views of a diaphragm-type device in the prior art;

[0022] Figure 3 is Figure 2 a cross-sectional view taken along A - A' in

[0023] Figure 4The second top view of the diaphragm device in the prior art;

[0024] Figure 5 It is Figure 4 The cross-sectional view taken along B-B' in

[0025] Figure 6 One of the schematic structural diagrams of the piezoelectric MEMS device provided by the embodiment of the present application;

[0026] Figure 7 The schematic structural diagram of the first vibration layer and the electrode layer in the piezoelectric MEMS device provided by the embodiment of the present application;

[0027] Figure 8 Two of the schematic structural diagrams of the piezoelectric MEMS device provided by the embodiment of the present application;

[0028] Figure 9 Three of the schematic structural diagrams of the piezoelectric MEMS device provided by the embodiment of the present application;

[0029] Figure 10 The simulation result diagram of the piezoelectric MEMS device provided by the embodiment of the present application;

[0030] Figure 11 Four of the schematic structural diagrams of the piezoelectric MEMS device provided by the embodiment of the present application;

[0031] Figure 12 Five of the schematic structural diagrams of the piezoelectric MEMS device provided by the embodiment of the present application;

[0032] Figure 13 One of the flowcharts of the manufacturing method of the piezoelectric MEMS device provided by the embodiment of the present application;

[0033] Figure 14 Two of the flowcharts of the manufacturing method of the piezoelectric MEMS device provided by the embodiment of the present application;

[0034] Figure 15 Three of the flowcharts of the manufacturing method of the piezoelectric MEMS device provided by the embodiment of the present application;

[0035] Figure 16 Four of the flowcharts of the manufacturing method of the piezoelectric MEMS device provided by the embodiment of the present application;

[0036] Figure 17 Five of the flowcharts of the manufacturing method of the piezoelectric MEMS device provided by the embodiment of the present application;

[0037] Figure 18 One of the schematic diagrams of the manufacturing process of the piezoelectric MEMS device provided by the embodiment of the present application;

[0038] Figure 19Schematic diagram II of the preparation process of the piezoelectric MEMS device provided by the embodiment of the present application;

[0039] Figure 20 Schematic diagram III of the preparation process of the piezoelectric MEMS device provided by the embodiment of the present application.

[0040] Icons: 10 - piezoelectric structure; 11 - electrode layer; 11a - top electrode layer; 11b - bottom electrode layer; 11c - middle electrode layer; 12 - piezoelectric layer; 13 - via hole; 100 - piezoelectric MEMS device; 110 - first vibration layer; 120 - electrode layer; 120a - top electrode layer; 120b - bottom electrode layer; 120c - middle electrode layer; 121 - first electrode surface; 122 - second electrode surface; 123 - electrode side; 130 - second vibration layer; 140 - barrier layer; 150 - piezoelectric layer; 160 - via hole; 170 - base layer; 171 - back cavity; L1 - outer contour of the positive projection of the electrode side on the first vibration layer; L2 - outer contour of the surface of the first vibration layer facing the electrode layer. Detailed implementation manners

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. It should be noted that, without conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the protection scope of the present application.

[0043] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0044] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "coupled" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0046] On the one hand of the embodiments of the present application, please refer to Figure 6 and Figure 7 , to provide a piezoelectric MEMS device 100, including: a first vibration layer 110, an electrode layer 120 disposed on the first vibration layer 110 along a preset direction, and a second vibration layer 130. The electrode layer 120 has a first electrode surface 121 and a second electrode surface 122 opposite to each other in the preset direction, and an electrode side surface 123 connecting the first electrode surface 121 and the second electrode surface 122. The outer contour L1 of the orthographic projection of the electrode side surface on the first vibration layer is located within the outer contour L2 of the surface of the first vibration layer facing the electrode layer. Please refer to Figure 8 , the first vibration layer 110 completely covers the first electrode surface 121, and the second vibration layer 130 completely covers the second electrode surface 122 and the electrode side surface 123.

[0047] Among them, MEMS is the abbreviation of Micro-Electro-Mechanical Systems. The preset direction is preferably perpendicular to the surface of the first vibrating layer 110. The first vibrating layer 110 and the second vibrating layer 130 are respectively located on opposite sides of the electrode layer 120. The first vibrating layer 110 is attached to and completely covers the first electrode surface 121 of the electrode layer 120, and the second vibrating layer 130 is attached to and completely covers the second electrode surface 122 of the electrode layer 120, thereby protecting the first electrode surface 121 and the second electrode surface 122 of the electrode layer 120 respectively. At the same time, the second vibrating layer 130 is also attached to and completely covers the electrode side surface 123 of the electrode layer 120, thereby protecting the electrode side surface 123 of the electrode layer 120. The first vibrating layer 110 and the second vibrating layer 130 cooperate to completely wrap all the exposed surfaces of the electrode layer 120, thereby achieving all-round anti-corrosion protection of the electrode layer 120.

[0048] It should be noted that the electrode side surface 123 is the side surface of the electrode layer 120 that would come into direct contact with the application environment without being wrapped by the second vibrating layer 130. The number of electrode side surfaces 123 can be one, two, or more. When the number of electrode side surfaces 123 is two or more, the second vibrating layer 130 simultaneously completely covers the two or more electrode side surfaces 123.

[0049] The preparation of the first vibrating layer 110, the electrode layer 120, and the second vibrating layer 130 generally uses a material deposition process. The outer contour L1 of the positive projection of the electrode side surface on the first vibrating layer is located within the outer contour L2 of the surface of the first vibrating layer facing the electrode layer. When forming the second vibrating layer 130, the material of the second vibrating layer 130 will be simultaneously laid on the surface of the electrode layer 120 and the first vibrating layer 110 exposed by the electrode layer 120. At this time, as long as the thickness of the second vibrating layer 130 is sufficient, the second vibrating layer 130 can directly completely cover the second electrode surface 122 and the electrode side surface 123 of the electrode layer 120 during the deposition process.

[0050] Please refer to Figure 9 , the electrode layer 120 can be a top electrode layer 120a, a bottom electrode layer 120b, or a middle electrode layer 120c. Among them, the bottom electrode layer 120b refers to the electrode layer 120 located at the bottommost, the top electrode layer 120a refers to the electrode layer 120 located at the topmost, and the middle electrode layer 120c refers to the electrode layer 120 located between the bottom electrode layer 120b and the top electrode layer 120a. Therefore, the number of both the bottom electrode layer 120b and the top electrode layer 120a is one, and the number of the middle electrode layer 120c can be one, two, or more.

[0051] When the electrode layer 120 is the top electrode layer 120a, a piezoelectric layer 150 needs to be provided below the top electrode layer 120a. Therefore, the first vibration layer 110 can be the piezoelectric layer 150, and the second vibration layer 130 is the barrier layer 140. By using the piezoelectric layer 150 to protect the first electrode surface 121 of the top electrode layer 120a and then setting the barrier layer 140 on the second electrode surface 122 of the top electrode layer 120a, the protection of the top electrode layer 120a can be achieved.

[0052] When the electrode layer 120 is the bottom electrode layer 120b, a piezoelectric layer 150 needs to be provided above the bottom electrode layer 120b. Therefore, the first vibration layer 110 is the barrier layer 140, and the second vibration layer 130 can be the piezoelectric layer 150. By setting the barrier layer 140 on the first electrode surface 121 of the bottom electrode layer 120b and then using the piezoelectric layer 150 to protect the second electrode surface 122 of the bottom electrode layer 120b, the protection of the top electrode layer 120a can be achieved.

[0053] When the electrode layer 120 is the middle electrode layer 120c, piezoelectric layers 150 need to be provided both above and below the middle electrode layer 120c. Therefore, both the first vibration layer 110 and the second vibration layer 130 can be the piezoelectric layer 150, and the middle electrode layer 120c is wrapped and protected by the upper and lower piezoelectric layers 150.

[0054] It can be understood that when the number of electrode layers 120 is two or more, the second vibration layer 130 of the lower electrode layer 120 can be the first vibration layer 110 of the upper electrode layer 120 at the same time. For example, if the piezoelectric MEMS device 100 includes the bottom electrode layer 120b, the piezoelectric layer 150, and the top electrode layer 120a at the same time, then the piezoelectric layer 150 is both the second vibration layer 130 of the bottom electrode layer 120b and the first vibration layer 110 of the top electrode layer 120a.

[0055] The above piezoelectric MEMS device 100 is provided with the first vibration layer 110 and the second vibration layer 130 on both sides of the electrode layer 120. The first vibration layer 110 and the second vibration layer 130 cooperate to completely wrap all the exposed surfaces of the electrode layer 120, thereby achieving all-round anti-corrosion protection of the electrode layer 120. Therefore, the above piezoelectric MEMS device 100 can prevent the electrode layer 120 from being corroded and has a relatively high service life.

[0056] When the electrode layer 120 is the bottom electrode layer 120b or the middle electrode layer 120c, the second vibration layer 130 can be the piezoelectric layer 150. The thickness of the piezoelectric layer 150 is significantly greater than the thickness of the electrode layer 120. At this time, the piezoelectric layer 150 prepared by the deposition process can generally directly wrap the second electrode surface 122 and the electrode side surface 123 of the electrode layer 120, and it is not easy to have the situation where the electrode side surface 123 cannot be covered.

[0057] When the electrode layer 120 is the top electrode layer 120a, the second vibration layer 130 is the barrier layer 140. The introduction of the barrier layer 140 will affect the piezoelectric output of the piezoelectric MEMS device 100 and have an impact on the performance of the piezoelectric MEMS device 100. As Figure 10 shown, when the thickness of the electrode layer 120 remains unchanged, the output voltage of the piezoelectric MEMS device 100 will decrease as the thickness of the barrier layer 140 increases. When the thickness of the barrier layer 140 is equal to the thickness of the electrode layer 120, the output voltage of the piezoelectric MEMS device 100 is weakened by approximately 12% compared to when the barrier layer 140 is not introduced. Thus, it can be seen that the thinner the thickness of the barrier layer 140, the better. However, when the barrier layer 140 becomes thinner, it may cause the electrode side surface 123 of the electrode layer 120 to be exposed, and the protection of the barrier layer 140 for the electrode layer 120 is no longer effective.

[0058] In order to enable the thinner second vibration layer 130 to also well cover the electrode side surface 123 of the electrode layer 120, optionally, please refer to Figure 9 and Figure 11 , the included angle between the electrode side surface 123 and the first vibration layer 110 is an acute angle, and the area of the first electrode surface 121 is larger than the area of the second electrode surface 122.

[0059] Setting the electrode side surface 123 of the electrode layer 120 as an inclined slope to form a gentle slope, and then depositing a thin layer as the second vibration layer 130 of the electrode layer 120 can enable the thinner second vibration layer 130 to also well cover the electrode layer 120, thereby forming more effective protection for the electrode layer 120 and avoiding the situation where the electrode side surface 123 of the electrode layer 120 is not completely covered due to the too thin second vibration layer 130. This method can be applied to the piezoelectric MEMS device 100 in which the second electrode surface 122 and the electrode side surface 123 of the top electrode layer 120a are directly exposed to the application environment.

[0060] Optionally, the material of the barrier layer 140 is scandium aluminum nitride.

[0061] Selecting scandium aluminum nitride with a higher density as the material of the barrier layer 140 can more effectively block the entry of water vapor and oxygen at a lower thickness of the barrier layer 140, thereby achieving effective protection for the electrode layer 120 with as little weakening of the piezoelectric response as possible.

[0062] Optionally, please refer to Figure 12, a through hole 160 is provided in the piezoelectric MEMS device 100. The through hole 160 penetrates two opposite surfaces of the piezoelectric MEMS device 100 in a preset direction. There is no overlapping area between the outer contour of the orthographic projection of the through hole 160 on the first vibration layer 110 and the outer contour of the orthographic projection of the electrode layer 120 on the first vibration layer 110. In this way, it is possible to prevent the side surface of the electrode layer 120 from being exposed due to the setting of the through hole 160, and prevent the electrode layer 120 from being corroded.

[0063] It should be noted that the cross-sectional shape (the section perpendicular to the preset direction) of the through hole 160 can be circular, strip-shaped or irregular, etc. The through hole 160 can also be located at the edge of the film layer of the piezoelectric MEMS device 100 and penetrate the side surface of the piezoelectric MEMS device 100.

[0064] Optionally, the piezoelectric MEMS device 100 further includes a base layer 170. The first vibration layer 110 is disposed on the base layer 170. A back cavity 171 is provided on the base layer 170. The back cavity 171 penetrates two opposite surfaces of the base layer 170 in a preset direction.

[0065] The base layer 170 provides support for the first vibration layer 110, the electrode layer 120 and the second vibration layer 130. The back cavity 171 on the base layer 170 provides a stable sound pressure environment for the first vibration layer 110, the electrode layer 120 and the second vibration layer 130, ensuring that their vibrations can be accurately detected. The base layer 170 can be a single-layer film layer or a composite film layer formed by stacking two or more film layers along the preset direction.

[0066] This embodiment also provides a preparation method of a piezoelectric MEMS device. Please refer to Figure 13 , including:

[0067] S100: Provide a first vibration layer, and form an electrode layer on the surface of the first vibration layer. Among them, the electrode layer has a first electrode surface completely covered by the first vibration layer, a second electrode surface facing away from the first vibration layer, and an electrode side surface connecting the first electrode surface and the second electrode surface. The outer contour of the orthographic projection of the electrode side surface of the electrode layer on the first vibration layer is located within the outer contour of the surface of the first vibration layer facing the electrode layer.

[0068] S200: Form a second vibration layer on the side of the electrode layer facing away from the first vibration layer. Among them, the second vibration layer completely covers the second electrode surface and the electrode side surface.

[0069] Please refer to Figure 6, first obtain the first vibration layer 110, and then successively form the electrode layer 120 and the second vibration layer 130 with the first vibration layer 110 as the support. The first vibration layer 110 and the second vibration layer 130 cooperate to completely wrap all the exposed surfaces of the electrode layer 120, thereby achieving all-round anti-corrosion protection for the electrode layer 120. The piezoelectric MEMS device 100 prepared by the above preparation method of the piezoelectric MEMS device can prevent the electrode layer 120 from being corroded and has a relatively long service life.

[0070] Optionally, please refer to Figure 14 , providing the first vibration layer and forming the electrode layer on the surface of the first vibration layer includes:

[0071] S110: Provide the first vibration layer and deposit a layer of electrode material on the surface of the first vibration layer to form a complete electrode film layer.

[0072] S120: Etch the electrode film layer to remove part of the electrode material to form the electrode layer.

[0073] Please refer to Figure 7 together. First, deposit a layer of electrode material on the surface of the first vibration layer 110 to form an electrode film layer. At this time, the electrode film layer completely covers the surface of the first vibration layer 110. Then, etch the electrode film layer to remove part of the electrode material, thereby forming the electrode layer 120. After the etching is completed, the outer contour L1 of the positive projection of the electrode side of the electrode layer 120 on the first vibration layer is located within the outer contour L2 of the surface of the first vibration layer facing the electrode layer, and part of the surface of the first vibration layer 110 is exposed.

[0074] Forming the second vibration layer on the side of the electrode layer facing away from the first vibration layer includes:

[0075] S210: Deposit a layer of second material on the surface of the second electrode and the surface of the first vibration layer exposed by the electrode layer to form the second vibration layer.

[0076] Please refer to Figure 8 together. Deposit a layer of second material on the surface of the second electrode 122 and the surface of the first vibration layer 110 exposed by the electrode layer 120. At this time, as long as the thickness of the second vibration layer 130 is sufficient, the second vibration layer 130 can directly cover the second electrode surface 122 and the electrode side 123 of the electrode layer 120 during the deposition process.

[0077] It should be noted that if the second vibration layer 130 is the piezoelectric layer 150, the second material is a piezoelectric material, such as scandium-doped aluminum nitride, aluminum nitride, etc. If the second vibration layer 130 is the barrier layer 140, the second material is a barrier material, such as silicon dioxide, scandium aluminum nitride, etc.

[0078] Optionally, etching the electrode film layer to remove part of the electrode material to form the electrode layer includes:

[0079] The electrode film layer is etched gently to remove part of the electrode material to form an electrode layer with an inclined electrode side surface, wherein the angle between the electrode side surface and the first vibration layer is an acute angle, and the area of ​​the first electrode surface is greater than that of the second electrode surface.

[0080] Please refer to Figure 9 and Figure 11 , a gentle slope etching method is adopted to make the electrode side surface 123 of the electrode layer 120 become an inclined slope, forming a gentle slope. At this time, the thinner second vibration layer 130 can also well cover the electrode layer 120, avoiding the situation where the electrode side surface 123 of the electrode layer 120 cannot be completely covered due to the thinness of the second vibration layer 130. When the second vibration layer 130 is a barrier layer 140, the influence on the piezoelectric performance of the piezoelectric MEMS device 100 can be minimized under the premise of ensuring that the electrode layer 120 is completely wrapped.

[0081] Optionally, see Figure 13 After forming a second vibration layer on a side of the electrode layer away from the first vibration layer, the method further includes:

[0082] S300: forming a through hole on a surface of the second vibration layer facing away from the electrode layer, wherein the through hole penetrates the second vibration layer, the electrode layer and the first vibration layer, and an outer contour of an orthographic projection of the through hole on the first vibration layer has no overlapping area with an outer contour of an orthographic projection of the electrode layer on the first vibration layer.

[0083] Please refer to Figure 11 and Figure 12 Selecting a region without the electrode layer 120 to process the through hole 160 can avoid exposing the electrode layer 120 during the processing and prevent the electrode layer 120 from being corroded.

[0084] Optionally, see Figure 15 , providing a first vibration layer includes:

[0085] S130: providing a base layer, and forming a first vibration layer on the base layer.

[0086] After forming a second vibration layer on a side of the electrode layer facing away from the first vibration layer, the method further includes:

[0087] S400: forming a back cavity on a surface of the base layer away from the first vibration layer, wherein the back cavity runs through two opposite surfaces of the base layer.

[0088] Please refer to Figure 11 and Figure 12, a first vibration layer 110 is formed on a base layer 170. The first vibration layer 110 and the base layer 170 can be directly adhered, or other film layers can be provided. A back cavity 171 is formed on the surface of the base layer 170 and penetrates the base layer 170. The setting of the back cavity 171 makes partial regions of the first vibration layer 110, the electrode layer 120, and the second vibration layer 130 suspended. If through holes 160 are processed in the first vibration layer 110, the electrode layer 120, and the second vibration layer 130, the through holes 160 correspond to and communicate with the position of the back cavity 171.

[0089] Optionally, please refer to Figure 16 and Figure 17 , a preparation method of a piezoelectric MEMS device, comprising:

[0090] S10: Provide a base layer and form a barrier layer on the base layer.

[0091] S20: Form a bottom electrode layer on the barrier layer. Among them, the bottom electrode layer has a first electrode surface completely covered by the barrier layer, a second electrode surface facing away from the barrier layer, and an electrode side connecting the first electrode surface and the second electrode surface. The outer contour of the electrode side of the bottom electrode layer in the positive projection on the barrier layer is located within the outer contour of the surface of the barrier layer facing the bottom electrode layer.

[0092] S30: Form a piezoelectric layer on the bottom electrode layer. Among them, the piezoelectric layer completely covers the second electrode surface and the electrode side of the bottom electrode layer.

[0093] S40: Form a middle electrode layer on the piezoelectric layer. Among them, the middle electrode layer has a first electrode surface completely covered by the piezoelectric layer, a second electrode surface facing away from the piezoelectric layer, and an electrode side connecting the first electrode surface and the second electrode surface. The outer contour of the electrode side of the middle electrode layer in the positive projection on the piezoelectric layer is located within the outer contour of the surface of the piezoelectric layer facing the middle electrode layer.

[0094] S50: Form another piezoelectric layer on the middle electrode layer. Among them, the piezoelectric layer completely covers the second electrode surface and the electrode side of the middle electrode layer.

[0095] S60: Form a top electrode layer on the piezoelectric layer. Among them, the top electrode layer has a first electrode surface completely covered by the piezoelectric layer, a second electrode surface facing away from the piezoelectric layer, and an electrode side connecting the first electrode surface and the second electrode surface. The outer contour of the electrode side of the top electrode layer in the positive projection on the piezoelectric layer is located within the outer contour of the surface of the piezoelectric layer facing the top electrode layer. The included angle between the electrode side of the top electrode layer and the piezoelectric layer is an acute angle, and the area of the first electrode surface of the top electrode layer is larger than the area of the second electrode surface.

[0096] S70: Form another barrier layer on the top electrode layer. Among them, the barrier layer completely covers the second electrode surface and the electrode side of the top electrode layer.

[0097] S80: Form a through-hole on the surface of the barrier layer facing away from the base layer, wherein the through-hole penetrates through two barrier layers, two piezoelectric layers, the top electrode layer, the middle electrode layer, and the top electrode layer, and there is no overlapping area between the outer contour of the positive projection of the through-hole on the base layer and the outer contours of the positive projection of the top electrode layer, the middle electrode layer, and the top electrode layer on the first vibration layer.

[0098] S90: Form a back cavity on the surface of the base layer facing away from the barrier layer, wherein the back cavity penetrates through two opposite surfaces of the base layer, and the back cavity corresponds to and communicates with the position of the through-hole.

[0099] Please refer to Figures 18 to 20 、 Figure 11 and Figure 12 . The barrier layer 140 closest to the base layer 170 is the first vibration layer 110 of the bottom electrode layer 120b, and the piezoelectric layer 150 on the bottom electrode is the second vibration layer 130 of the bottom electrode layer 120b. At the same time, the piezoelectric layer 150 on the bottom electrode is also the first vibration layer 110 of the middle electrode layer 120c. The piezoelectric layer 150 on the middle electrode is the second vibration layer 130 of the middle electrode, and at the same time, the piezoelectric layer 150 on the middle electrode is also the first vibration layer 110 of the top electrode. The barrier layer 140 farthest from the bottom layer is the second vibration layer 130 of the top electrode layer 120a.

[0100] It should be understood that although the steps in the above flowcharts are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowchart may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0101] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A piezoelectric MEMS device, characterized in that: include: A first vibration layer, an electrode layer and a second vibration layer arranged on the first vibration layer along a preset direction, the electrode layer having a first electrode surface and a second electrode surface opposite to each other in the preset direction, and an electrode side surface connecting the first electrode surface and the second electrode surface, an outer contour of an orthographic projection of the electrode side surface on the first vibration layer is located within an outer contour of a surface of the first vibration layer facing the electrode layer, the first vibration layer completely covers the first electrode surface, and the second vibration layer completely covers the second electrode surface and the electrode side surface.

2. The piezoelectric MEMS device according to claim 1, characterized in that: The angle between the side surface of the electrode and the first vibration layer is an acute angle, and the area of ​​the surface of the first electrode is greater than the area of ​​the surface of the second electrode.

3. The piezoelectric MEMS device according to claim 1, characterized in that: A through hole is provided in the piezoelectric MEMS device, and the through hole passes through two opposite surfaces of the piezoelectric MEMS device in the preset direction. The outer contour of the orthographic projection of the through hole on the first vibration layer has no overlapping area with the outer contour of the orthographic projection of the electrode layer on the first vibration layer.

4. The piezoelectric MEMS device according to any one of claims 1 to 3, characterized in that: The electrode layer is a top electrode layer, the first vibration layer is a piezoelectric layer, and the second vibration layer is a barrier layer.

5. The piezoelectric MEMS device according to any one of claims 1 to 3, characterized in that: The electrode layer is a bottom electrode layer, the first vibration layer is a barrier layer, and the second vibration layer is a piezoelectric layer.

6. The piezoelectric MEMS device according to any one of claims 1 to 3, characterized in that: The electrode layer is a middle electrode layer, and the first vibration layer and the second vibration layer are both piezoelectric layers.

7. The piezoelectric MEMS device according to claim 1, characterized in that: It also includes a base layer, the first vibration layer is arranged on the base layer, a back cavity is arranged on the base layer, and the back cavity runs through two surfaces of the base layer that are opposite to each other in the preset direction.

8. A method for preparing a piezoelectric MEMS device, characterized in that: include: Providing a first vibration layer, and forming an electrode layer on a surface of the first vibration layer, wherein the electrode layer comprises a first electrode surface completely covered by the first vibration layer, a second electrode surface facing away from the first vibration layer, and an electrode side surface connecting the first electrode surface and the second electrode surface, and an outer contour of an orthographic projection of the electrode side surface on the first vibration layer is located within an outer contour of a surface of the first vibration layer facing the electrode layer; A second vibration layer is formed on a side of the electrode layer facing away from the first vibration layer, wherein the second vibration layer completely covers the second electrode surface and the electrode side surface.

9. The method for preparing a piezoelectric MEMS device according to claim 8, characterized in that: The providing of a first vibration layer and forming an electrode layer on a surface of the first vibration layer comprises: Providing a first vibration layer, and depositing a layer of electrode material on the surface of the first vibration layer to form a complete electrode film layer; Etching the electrode film layer to remove part of the electrode material to form an electrode layer; The forming of the second vibration layer on the side of the electrode layer away from the first vibration layer comprises: A layer of second material is deposited on the surface of the second electrode and the surface of the first vibration layer exposed by the electrode layer to form a second vibration layer.

10. The method for preparing a piezoelectric MEMS device according to claim 9, characterized in that: The step of etching the electrode film layer to remove a portion of the electrode material to form an electrode layer comprises: The electrode film layer is etched in a gentle slope to remove part of the electrode material to form an electrode layer with an inclined electrode side surface, wherein the angle between the electrode side surface and the first vibration layer is an acute angle, and the area of ​​the first electrode surface is greater than the area of ​​the second electrode surface.

11. The method for preparing a piezoelectric MEMS device according to claim 8, characterized in that: After forming the second vibration layer on the side of the electrode layer away from the first vibration layer, the method further includes: A through hole is formed on a surface of the second vibration layer facing away from the electrode layer, wherein the through hole passes through the second vibration layer, the electrode layer and the first vibration layer, and an outer contour of an orthographic projection of the through hole on the first vibration layer has no overlapping area with an outer contour of an orthographic projection of the electrode layer on the first vibration layer.

12. The method for preparing a piezoelectric MEMS device according to claim 8, characterized in that: Providing the first vibration layer comprises: Providing a base layer, and forming a first vibration layer on the base layer; After forming the second vibration layer on the side of the electrode layer away from the first vibration layer, the method further includes: A back cavity is formed on a surface of the base layer away from the first vibration layer, wherein the back cavity runs through two opposite surfaces of the base layer.

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