MEMS device and manufacturing method thereof

Abstract

The invention discloses an MEMS device and a manufacturing method thereof, the device comprises a first structure and a second structure, the first structure at least comprises a substrate, a fixed electrode layer, a first supporting part, a movable electrode layer and a second supporting part which are sequentially arranged from bottom to top, and the second structure at least comprises a cap layer. The first structure and the second structure are bonded to form a cavity between the fixed electrode layer and the cap layer; wherein the movable electrode layer divides the cavity into a first cavity and a second cavity, a plurality of piezoelectric sensitive columns are formed in the first cavity, the two ends of each piezoelectric sensitive column are connected to the fixed electrode layer and the movable electrode layer respectively, a mass block is formed in the second cavity, and the mass block is connected to the fixed electrode layer and the movable electrode layer respectively. The mass block is formed on the movable electrode layer, and the mass block is only in contact with the movable electrode layer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a MEMS device and a manufacturing method thereof. Background Art

[0002] Micro-Electro-Mechanical System (MEMS) technology is a high-tech that has developed rapidly in recent years. It uses advanced semiconductor manufacturing processes to achieve mass production of sensors, actuators and other devices. Compared with corresponding traditional devices, MEMS devices have very obvious advantages in size, power consumption, weight and price. In the market, the main application examples of MEMS devices include accelerometers, pressure sensors and silicon microphones.

[0003] Currently, consumer-grade accelerometers on the market are mainly capacitive type, which are widely used due to their high precision and easy measurement. However, they also have problems such as relatively complex processing technology, failure caused by adhesion of comb teeth, and excessive impact that can easily cause beam wear. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] The present invention provides a MEMS device, comprising a first structure and a second structure, wherein the first structure at least comprises a substrate, a fixed electrode layer, a first support portion, a movable electrode layer, and a second support portion arranged in sequence from bottom to top, and the second structure at least comprises a cap layer, and the first structure and the second structure are bonded to form a cavity between the fixed electrode layer and the cap layer;

[0006] The active electrode layer divides the cavity into a first cavity and a second cavity, a plurality of piezoelectric sensitive columns are formed in the first cavity, two ends of the plurality of piezoelectric sensitive columns are respectively connected to the fixed electrode layer and the active electrode layer, a mass block is formed in the second cavity, the mass block is formed on the active electrode layer, and the mass block is only in contact with the active electrode layer.

[0007] Exemplarily, the plurality of piezoelectric sensitive pillars include one-dimensional nanopillars.

[0008] Exemplarily, the material of the plurality of piezoelectric sensitive columns includes one or more of AlN, ZnO, PZT or PVDF.

[0009] Exemplarily, the plurality of piezoelectric sensitive columns and the mass block are correspondingly arranged on both sides of the active electrode layer.

[0010] Exemplarily, the first structure and the second structure further have a bonding layer respectively, and the bonding layer is used to bond the first structure to the second structure.

[0011] Exemplarily, the active electrode layer has a through hole to connect the first cavity and the second cavity.

[0012] Exemplarily, the cavity is in a vacuum state or a low-pressure state.

[0013] Exemplarily, the MEMS device includes a piezoelectric accelerometer.

[0014] The present invention also provides a method for manufacturing a MEMS device, comprising:

[0015] Forming a first structure, comprising at least:

[0016] Providing a substrate, and sequentially forming a fixed electrode layer and a first supporting layer on the substrate;

[0017] forming a plurality of piezoelectric sensitive columns in the first supporting layer;

[0018] forming an active electrode layer on the first supporting layer, and patterning the active electrode layer to form a plurality of through holes in the active electrode layer;

[0019] Etching the first supporting layer to form a first cavity between the fixed electrode layer and the movable electrode layer, wherein the remaining portion of the first supporting layer forms a first supporting portion, wherein a plurality of piezoelectric sensitive columns are formed in the first cavity, and two ends of the plurality of piezoelectric sensitive columns are respectively connected to the fixed electrode layer and the movable electrode layer;

[0020] forming a mass block layer on the movable electrode layer, etching the mass block layer to form a mass block on the movable electrode layer, and a remaining portion of the mass block layer above the first supporting portion forms a second supporting portion;

[0021] The second structure is formed, comprising at least:

[0022] Providing a cap layer;

[0023] The first structure and the second structure are bonded, a gap is provided between the mass block and the cap layer, a second cavity is formed between the cap layer and the active electrode layer, and the first cavity is connected with the second cavity to form a cavity.

[0024] Exemplarily, by making the thickness of the second support portion greater than the thickness of the mass block, or forming a third support portion on the second support portion, or making the second structure a concave structure, one or more of the above, a gap is provided between the mass block and the cap layer after the first structure and the second structure are bonded.

[0025] According to the MEMS device and the manufacturing method thereof provided by the present invention, the first structure and the second structure are bonded to form a cavity, the active electrode layer separates the cavity into a first cavity and a second cavity, a plurality of pressure-sensitive columns are formed in the first cavity, wherein the two ends of the pressure-sensitive columns are respectively connected to the fixed electrode layer and the active electrode layer, a mass block is formed in the second cavity, wherein the mass block is formed on the active electrode layer and only contacts the active electrode layer, and by forming an active electrode layer with a mass block on the pressure-sensitive column, when the external acceleration changes, the piezoelectric response is obvious, the sensitivity is high, and the manufacturing cost is low, and large-scale production can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0027] In the attached figure:

[0028] Figure 1 A schematic diagram of the structure of a MEMS device according to an embodiment of the present invention;

[0029] Figure 2 is a flow chart of a method for manufacturing a first structure of a MEMS device according to an embodiment of the present invention;

[0030] Figures 3A-3G The cross-sectional schematic diagram is a structure obtained by sequentially implementing the method for manufacturing a MEMS device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0032] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0033] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0034] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0035] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0036] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0037] The present invention provides a MEMS device, such as Figure 1 As shown, it includes a first structure 100 and a second structure 200, the first structure 100 at least includes a substrate 101, a fixed electrode layer 102, a first support portion 103, a movable electrode layer 104 and a second support portion 105 arranged in sequence from bottom to top, the second structure 200 at least includes a cap layer 201, and the first structure 100 and the second structure 200 are bonded to form a cavity 300 between the fixed electrode layer 102 and the cap layer 201;

[0038] The active electrode layer 104 divides the cavity 300 into a first cavity 301 and a second cavity 302. A plurality of piezoelectric sensitive columns 106 are formed in the first cavity 301. Both ends of the plurality of piezoelectric sensitive columns 106 are respectively connected to the fixed electrode layer 102 and the active electrode layer 104. A mass block 107 is formed in the second cavity 302. The mass block 107 is formed on the active electrode layer 104. The mass block 107 is only in contact with the active electrode layer 104.

[0039] The main application examples of MEMS devices include but are not limited to accelerometers, pressure sensors and silicon microphones. In the embodiments of the present application, the MEMS device includes a pressure accelerometer. Conventional capacitive accelerometers require an external voltage for power supply, while the piezoelectric accelerometer of the present application is a self-powered device and does not require an external power supply voltage.

[0040] Exemplarily, the plurality of piezoelectric sensitive columns 106 are made of piezoelectric material. In one embodiment, the material of the piezoelectric sensitive columns 106 includes one or more of AlN, ZnO, PZT or PVDF, which is not limited in the present application.

[0041] Exemplarily, the mass block 107 is used to sense changes in external acceleration. In one embodiment, the material of the mass block 107 includes one or more of single crystal silicon, polycrystalline silicon or silicon nitride, which is not limited in the present application.

[0042] Exemplarily, the mass block 107 and the plurality of piezoelectric sensitive columns 106 are disposed correspondingly on both sides of the active electrode layer 104 .

[0043] Since the piezoelectric sensitive column 106 is made of piezoelectric material, when the external acceleration changes, the mass block 107 will drive the active electrode layer 104 to vibrate, causing the piezoelectric sensitive column 106 to deform, and the potential difference at both ends of the piezoelectric sensitive column 106 to change. Since the two ends of the piezoelectric sensitive column 106 are respectively connected to the fixed electrode layer 102 and the active electrode layer 104, the potential difference at both ends of the piezoelectric sensitive column 106 can be output through the fixed electrode layer 102 and the active electrode layer 104, thereby obtaining the magnitude of the acceleration.

[0044] Exemplarily, the plurality of piezoelectric sensitive pillars 106 include one-dimensional nanopillars.

[0045] Nanomaterials refer to materials whose dimensions in at least one dimension (such as length (x), width (y), and height (z)) are between 0.1nm and 100nm. Among them, materials whose dimensions in one of the three dimensions are not between 0.1nm and 100nm are called one-dimensional nanomaterials. One-dimensional nanomaterials can be classified according to their shapes, such as nanotubes, nanorods, nanowires, nanobelts, etc. In the embodiment of the present application, the piezoelectric sensitive column 106 is a one-dimensional nanocolumn, whose radial dimension is in the range of 0.1nm to 100nm, and whose length dimension is greater than 100nm and much higher than the radial dimension.

[0046] Since the piezoelectric sensitive column 106 is a one-dimensional nanomaterial, it has a higher piezoelectric coefficient than the piezoelectric film. The axial deformation can be defaulted to the d33 direction, so a larger output voltage can be obtained; at the same time, the radial deformation caused by the torsion of the mass block 107 is smaller than the axial deformation, which can reduce the measurement errors caused by the other two axes.

[0047] Exemplarily, the cavity 300 is in a vacuum state or a low pressure state. The movable electrode layer 104 has a through hole to connect the first cavity 301 and the second cavity 302 .

[0048] It should be noted that the low pressure state of the cavity 300 refers to a low pressure state close to vacuum, for example, the air pressure in the cavity 300 is less than 0.1 MPa. By making the cavity 300 a vacuum state or a low pressure state close to vacuum, the damping effect of air and the like on the mass 107 when the acceleration changes is avoided.

[0049] Exemplarily, the first structure 100 and the second structure 200 also have a bonding layer respectively, and the bonding layer is used to bond the first structure 100 and the second structure 200. The bonding layer is made of metal material, and the material of the bonding layer includes one or more of Au, Ge, Al or Cu.

[0050] In one embodiment, a first bonding layer is formed above the second supporting portion 105 of the first structure 100, and a second bonding layer is formed at a corresponding position of the cap layer 201 of the second structure 200. The first structure 100 and the second structure 200 are bonded together by face-to-face eutectic bonding of the first bonding layer and the second bonding layer, thereby achieving face-to-face eutectic bonding between the first bonding layer and the second structure 200. The cavity 300 can be in a vacuum state or a low-pressure state close to a vacuum through the bonding process.

[0051] In one embodiment, the second structure 200 may be a concave structure, such as Figure 1 As shown. The second cavity 302 is formed by the active electrode layer 104, the second support portion 105 and the cap layer 201. The mass block 107 is located in the second cavity 302 and is only in contact with the active electrode layer 104. The gap between the mass block 107 and the cap layer 201 can be set as needed. Even if a bonding layer is formed between the second support portion 105 and the cap layer 201, the bonding layer is usually a thin metal layer, and it is difficult to control the distance between the mass block 107 and the cap layer 201 by the thickness of the bonding layer. Therefore, the second structure 200 is usually designed as a concave structure, the concave area of ​​which corresponds to the cavity formed in the first structure 100, and the convex area of ​​which corresponds to the second support portion 105 of the first structure 100, so as to facilitate the bonding of the first structure 100 and the second structure 200.

[0052] According to the MEMS device provided by the present invention, the first structure and the second structure are bonded to form a cavity, the active electrode layer separates the cavity into a first cavity and a second cavity, a plurality of pressure-sensitive columns are formed in the first cavity, wherein two ends of the pressure-sensitive columns are respectively connected to the fixed electrode layer and the active electrode layer, a mass block is formed in the second cavity, wherein the mass block is formed on the active electrode layer and only contacts the active electrode layer, and an active electrode layer with a mass block is formed on the pressure-sensitive column, when the external acceleration changes, the mass block drives the active electrode layer to vibrate, causing the piezoelectric sensitive column to deform, the potential difference at both ends of the piezoelectric sensitive column to change, the piezoelectric response is obvious, and the sensitivity is high.

[0053] The present invention also provides a method for manufacturing a MEMS device, such as Figure 2 As shown, the following steps are included:

[0054] Forming a first structure, comprising at least:

[0055] Step S210: providing a substrate, and sequentially forming a fixed electrode layer and a first supporting layer on the substrate;

[0056] Step S220: forming a plurality of piezoelectric sensitive columns in the first supporting layer;

[0057] Step S230: forming an active electrode layer on the first supporting layer, and patterning the active electrode layer to form a plurality of through holes in the active electrode layer;

[0058] Step S240: etching the first supporting layer to form a first cavity between the fixed electrode layer and the movable electrode layer, wherein the remaining portion of the first supporting layer forms a first supporting portion, wherein a plurality of piezoelectric sensitive columns are formed in the first cavity, and two ends of the plurality of piezoelectric sensitive columns are respectively connected to the fixed electrode layer and the movable electrode layer;

[0059] Step S250: forming a mass block layer on the active electrode layer, etching the mass block layer to form a mass block on the active electrode layer, and the remaining portion of the mass block layer above the first supporting portion forms a second supporting portion;

[0060] The second structure is formed, comprising at least:

[0061] Providing a cap layer;

[0062] The first structure and the second structure are bonded, a gap is provided between the mass block and the cap layer, a second cavity is formed between the cap layer and the active electrode layer, and the first cavity is connected with the second cavity to form a cavity.

[0063] In order to fully understand the present invention, detailed steps and structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0064] Below, reference Figures 3A to 3G The manufacturing method of the MEMS device of the present invention is described in detail, wherein 3A to Figure 3G The cross-sectional schematic diagram shows a waveguide structure obtained by sequentially implementing the method for manufacturing a MEMS device according to an embodiment of the present invention.

[0065] First, the first structure 100 is formed through the following steps.

[0066] Execute step S210, such as Figure 3A As shown, a substrate 101 is provided, and a fixed electrode layer 102 and a first supporting layer 103' are sequentially formed on the substrate.

[0067] In one embodiment, the substrate 101 may be any suitable semiconductor substrate, such as a silicon substrate, and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, including multilayer structures composed of these semiconductor materials, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), or may also be double-sided polished silicon wafers (Double Side Polished Wafers, DSP), or may be ceramic substrates such as alumina, quartz or glass substrates, etc.

[0068] In one embodiment, a buffer layer 108, a fixed electrode layer 102, and a first support layer 103' are sequentially formed on a substrate 101. The materials of the buffer layer 108 and the first support layer 103' include but are not limited to silicon dioxide, and the materials of the fixed electrode layer 102 include but are not limited to doped polysilicon. The formation process of the buffer layer 108, the fixed electrode layer 102, and the first support layer 103' can adopt any existing technology well known to those skilled in the art, preferably chemical vapor deposition (CVD), such as low temperature chemical vapor deposition (LTCVD), low pressure chemical vapor deposition (LPCVD), metal organic chemical vapor deposition (MOCVD), rapid thermal chemical vapor deposition (RTCVD), and plasma enhanced chemical vapor deposition (PECVD).

[0069] Next, execute step S220, such as Figure 3B As shown, a plurality of piezoelectric sensitive columns 106 are formed in the first supporting layer 103 ′.

[0070] In one embodiment, the first supporting layer 103' is etched to form a plurality of through holes in the first supporting layer 103', wherein the plurality of through holes expose the fixed electrode layer 102. The method for etching the first supporting layer 103' may adopt any existing technology well known to those skilled in the art, preferably dry etching, which includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching, laser ablation or any combination of these methods.

[0071] In one embodiment, a plurality of through holes in the first support layer 103' are filled with piezoelectric material to form a plurality of piezoelectric sensitive columns 106. The piezoelectric material includes one or more of AlN, ZnO, PZT or PVDF, which is not limited in the present application.

[0072] Next, execute step S230, such as Figure 3CAs shown, an active electrode layer 104 is formed on the first supporting layer 103 ′, and the active electrode layer 104 is patterned to form a plurality of through holes in the active electrode layer.

[0073] In one embodiment, the material of the active electrode layer 104 includes but is not limited to doped polysilicon. The formation process of the active electrode layer 104 can adopt any existing technology well known to those skilled in the art, which will not be described in detail here.

[0074] In one embodiment, the active electrode layer 104 is etched to form a plurality of through holes in the active electrode layer 104, wherein the plurality of through holes expose the first support layer 103'. The method for etching the active electrode layer 104 may adopt any prior art known to those skilled in the art, which will not be described in detail herein.

[0075] Next, execute step S240, such as Figure 3D As shown, the first supporting layer 103' is etched to form a first cavity 301 between the fixed electrode layer 102 and the active electrode layer 104, and the remaining part of the first supporting layer 103' forms the first supporting portion 103. A plurality of piezoelectric sensitive columns 106 are formed in the first cavity 301, and both ends of the plurality of piezoelectric sensitive columns 106 are respectively connected to the fixed electrode layer 102 and the active electrode layer 104.

[0076] In one embodiment, the method for etching the first supporting layer 103' can adopt any existing technology well known to those skilled in the art, preferably wet etching, and the solution of the wet etching method is selective. For the case where the first supporting layer 103' is made of silicon dioxide, and the fixed electrode layer 102 and the movable electrode layer 104 are made of doped polysilicon, the wet etching solution can be BOE solution, which is prepared from HF, NH4F and deionized water.

[0077] Exemplarily, the plurality of piezoelectric sensitive pillars 106 include one-dimensional nanopillars.

[0078] Nanomaterials refer to materials whose dimensions in at least one dimension (such as length (x), width (y), and height (z)) are between 0.1nm and 100nm. Among them, materials whose dimensions in one of the three dimensions are not between 0.1nm and 100nm are called one-dimensional nanomaterials. One-dimensional nanomaterials can be classified according to their shapes, such as nanotubes, nanorods, nanowires, nanobelts, etc. In the embodiment of the present application, the piezoelectric sensitive column 106 is a one-dimensional nanocolumn, whose radial dimension is in the range of 0.1nm to 100nm, and whose length dimension is greater than 100nm and much higher than the radial dimension.

[0079] Next, step S250 is performed, such as Figure 3EAs shown, a mass block layer is formed on the active electrode layer 104 , and the mass block layer is etched to form a mass block 107 on the active electrode layer. The remaining portion of the mass block layer above the first supporting portion 103 forms a second supporting portion 105 .

[0080] In one embodiment, the material of the mass block layer includes but is not limited to single crystal silicon, polycrystalline silicon or silicon nitride. The method for forming the mass block layer can adopt any existing technology well known to those skilled in the art, which will not be described in detail here.

[0081] In one embodiment, the mass block 107 and the second support portion 105 may be formed synchronously by etching the mass block layer, or may be formed asynchronously. The advantage of synchronously forming the mass block 107 and the second support portion 105 is that only one mask is required and only one photolithography process is performed. The advantage of asynchronously forming the mass block 107 and the second support portion 105 is that the thickness of the second support portion 105 can be adjusted as needed, which facilitates adjusting the distance between the mass block 107 and the second structure 200 in subsequent steps. In addition, after the mass block 107 and the second support portion 105 are synchronously formed, a third support portion (not shown) may be formed on the second support portion 105, and the distance between the mass block 107 and the second structure 200 may be adjusted by the thickness of the third support portion.

[0082] In one embodiment, Figure 3E As shown, the mass block 107 and the plurality of piezoelectric sensitive columns 106 are correspondingly arranged on both sides of the active electrode layer 104. Since the piezoelectric sensitive columns 106 are made of piezoelectric material, when the external acceleration changes, the mass block 107 will drive the active electrode layer 104 to vibrate, causing the piezoelectric sensitive columns 106 to deform, and the potential difference between the two ends of the piezoelectric sensitive columns 106 to change. Since the two ends of the piezoelectric sensitive columns 106 are respectively connected to the fixed electrode layer 102 and the active electrode layer 104, the potential difference between the two ends of the piezoelectric sensitive columns 106 can be output through the fixed electrode layer 102 and the active electrode layer 104, thereby obtaining the magnitude of the acceleration.

[0083] In addition, since the piezoelectric sensitive column 106 is a one-dimensional nanomaterial, it has a higher piezoelectric coefficient than the piezoelectric film. The axial deformation can be defaulted to the d33 direction, so a larger output voltage can be obtained; at the same time, the radial deformation caused by the torsion of the mass block 107 is smaller than the axial deformation, which can reduce the measurement errors caused by the other two axes.

[0084] In one embodiment, after forming the second support portion 105, a step of forming a first bonding layer 109 on the second support portion 105 is also included. The material of the first bonding layer 109 includes but is not limited to metals such as Au, Ge, Al, and Cu. The method for forming the first bonding layer 109 can adopt any existing technology well known to those skilled in the art, which will not be repeated here.

[0085] At this point, the manufacturing of the first structure 100 is completed.

[0086] Next, the second structure 200 is formed through the following steps.

[0087] like Figure 3F As shown, a cap layer 201 is provided.

[0088] In one embodiment, the material of the cap layer 201 may be consistent with that of the substrate 101 , or may be silicon oxide or silicon nitride, etc., which is not limited in the present invention.

[0089] In one embodiment, after providing the cap layer 201, when the first bonding layer 109 is formed on the second support portion 105, the second bonding layer 202 may also be formed at a corresponding position of the cap layer 201, such as Figure 3F shown.

[0090] At this point, the manufacturing of the second structure 200 is completed.

[0091] It should be noted that the second structure 200 is usually designed as a concave structure, the concave area of ​​which corresponds to the cavity formed in the first structure 100, and the convex area of ​​which corresponds to the second support portion 105 of the first structure 100, such as Figure 3F As shown, it is convenient to achieve bonding between the first structure 100 and the second structure 200.

[0092] Next, if Figure 3G As shown, the first structure 100 and the second structure 200 are bonded, a gap is provided between the mass block 107 and the cap layer 201 , a second cavity 302 is formed between the cap layer 201 and the active electrode layer 104 , and the first cavity 301 and the second cavity 302 are connected to form a cavity 300 .

[0093] In one embodiment, after the first structure 100 and the second structure 200 are bonded, there is a gap between the mass block 107 and the cap layer 201 by making the thickness of the second support portion 105 greater than the thickness of the mass block 107, or forming a third support portion (not shown) on the second support portion 105, or making the second structure 200 a concave structure.

[0094] In one embodiment, the cavity 300 can be in a vacuum state or a low-pressure state through a bonding process, wherein the low-pressure state of the cavity 300 refers to a low-pressure state close to vacuum, for example, the air pressure in the cavity 300 is less than 0.1 MPa. By making the cavity 300 in a vacuum state or a low-pressure state close to vacuum, the damping effect of air and the like on the mass block 107 when the acceleration changes is avoided.

[0095] The key steps of the method for manufacturing the MEMS device of the present invention have been introduced so far. A plurality of other process steps may be required for the complete device preparation, which will not be described one by one here.

[0096] It is worth mentioning that the order of the above steps is only an example. Under the premise of no conflict, the order of the above steps can also be swapped or performed alternately.

[0097] In one embodiment, the main application examples of MEMS devices include but are not limited to accelerometers, pressure sensors, and silicon microphones. In the embodiment of the present application, the MEMS device includes a pressure accelerometer. Conventional capacitive accelerometers require an external voltage for power supply, while the piezoelectric accelerometer of the present application is a self-powered device and does not require an external power supply voltage.

[0098] According to the MEMS device and the manufacturing method thereof provided by the present invention, the first structure and the second structure are bonded to form a cavity, the active electrode layer separates the cavity into a first cavity and a second cavity, a plurality of pressure-sensitive columns are formed in the first cavity, wherein the two ends of the pressure-sensitive columns are respectively connected to the fixed electrode layer and the active electrode layer, a mass block is formed in the second cavity, wherein the mass block is formed on the active electrode layer and only contacts the active electrode layer, and by forming an active electrode layer with a mass block on the pressure-sensitive column, when the external acceleration changes, the piezoelectric response is obvious, the sensitivity is high, and the manufacturing cost is low, and large-scale production can be achieved.

[0099] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A MEMS device, characterized in that: The invention comprises a first structure and a second structure, wherein the first structure comprises at least a substrate, a fixed electrode layer, a first support portion, a movable electrode layer and a second support portion arranged in sequence from bottom to top, and the second structure comprises at least a cap layer, and the first structure and the second structure are bonded to form a cavity between the fixed electrode layer and the cap layer; The active electrode layer divides the cavity into a first cavity and a second cavity, a plurality of piezoelectric sensitive columns are formed in the first cavity, two ends of the plurality of piezoelectric sensitive columns are respectively connected to the fixed electrode layer and the active electrode layer, a mass block is formed in the second cavity, the mass block is formed on the active electrode layer, and the mass block is only in contact with the active electrode layer.

2. The MEMS device according to claim 1, characterized in that The plurality of piezoelectric sensitive pillars include one-dimensional nanopillars.

3. The MEMS device according to claim 2, characterized in that The material of the plurality of piezoelectric sensitive columns includes one or more of AlN, ZnO, PZT or PVDF.

4. The MEMS device according to claim 1, characterized in that The plurality of piezoelectric sensitive columns and the mass block are correspondingly arranged on both sides of the active electrode layer.

5. The MEMS device according to claim 1, characterized in that The first structure and the second structure further have a bonding layer respectively, and the bonding layer is used to bond the first structure to the second structure.

6. The MEMS device according to claim 1, characterized in that The movable electrode layer has a through hole to connect the first cavity and the second cavity.

7. The MEMS device according to claim 1, characterized in that: The cavity is in a vacuum state or a low-pressure state.

8. The MEMS device according to claim 1, characterized in that: The MEMS device includes a piezoelectric accelerometer.

9. A method for manufacturing a MEMS device, characterized in that: include: Forming a first structure, comprising at least: Providing a substrate, and sequentially forming a fixed electrode layer and a first supporting layer on the substrate; forming a plurality of piezoelectric sensitive columns in the first supporting layer; forming an active electrode layer on the first supporting layer, and patterning the active electrode layer to form a plurality of through holes in the active electrode layer; Etching the first supporting layer to form a first cavity between the fixed electrode layer and the movable electrode layer, wherein the remaining portion of the first supporting layer forms a first supporting portion, wherein a plurality of piezoelectric sensitive columns are formed in the first cavity, and two ends of the plurality of piezoelectric sensitive columns are respectively connected to the fixed electrode layer and the movable electrode layer; forming a mass block layer on the movable electrode layer, etching the mass block layer to form a mass block on the movable electrode layer, and a remaining portion of the mass block layer above the first supporting portion forms a second supporting portion; The second structure is formed, comprising at least: Providing a cap layer; The first structure and the second structure are bonded, a gap is provided between the mass block and the cap layer, a second cavity is formed between the cap layer and the active electrode layer, and the first cavity is connected with the second cavity to form a cavity.

10. The manufacturing method according to claim 9, characterized in that: By making the thickness of the second support portion greater than the thickness of the mass block, or forming a third support portion on the second support portion, or making the second structure a concave structure, one or more of the above, a gap is provided between the mass block and the cap layer after the first structure and the second structure are bonded.

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