MEMS pressure sensor and manufacturing method therefor, and electronic device

Abstract

A MEMS pressure sensor and a manufacturing method therefor, and an electronic device. The method comprises: on a surface of a first substrate (210), forming at least two first pressure structures spaced apart from each other, wherein each first pressure structure comprises a first electrode layer (211), a first sacrificial layer (212), a first support layer (213), a second electrode layer (214), and a second support layer (215) from bottom to top, and further comprises a first cavity (216); on a surface of a second substrate (220), forming at least two second pressure structures spaced apart from each other, wherein each second pressure structure comprises a third electrode layer (221) and a second sacrificial layer (222) from bottom to top, and further comprises a second cavity (224); bonding the second support layer (215) to the second sacrificial layer (222), wherein the first cavity (216) and the second cavity (224) are disposed corresponding to each other; and removing the second substrate (220) to expose the third electrode layer (221), wherein the third electrode layer (221) and the second electrode layer (214) form a variable capacitor structure, the second electrode layer (214) and the first electrode layer (211) form a reference capacitor structure, and two variable capacitor structures and two reference capacitor structures jointly form a Wheatstone bridge.

Description

MEMS pressure sensor, manufacturing method thereof and electronic device

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 202410835058.1, filed on June 25, 2024, and entitled "MEMS pressure sensor, manufacturing method thereof and electronic device", the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the field of semiconductor technology, and in particular to a MEMS pressure sensor, a manufacturing method thereof and an electronic device. BACKGROUND

[0004] Micro-Electro-Mechanical System (MEMS) pressure sensors are a frontier research field developed on the basis of MEMS technology, which are suitable for harsh environments such as high impact, high overload, electrical conduction, corrosion, radiation, etc., and are widely used in aerospace, electronics, industry, medical health and environmental monitoring fields. Compared with piezoresistive pressure sensors, capacitive pressure sensors have the advantages of high sensitivity, low power consumption, good temperature characteristics, etc., and are widely used in various fields.

[0005] According to the capacitance formula, capacitive pressure sensors can be divided into three types: variable spacing, variable area and variable dielectric. Due to the convenience of implementation, the variable spacing capacitive pressure sensor is the most common, whose principle is that the change of spacing leads to the change of capacitance value, and the integrated circuit obtains the signal and then performs amplification processing. However, the variable spacing capacitive pressure sensor in the related art has problems such as high output impedance, weak load capacity, and low measurement accuracy. SUMMARY

[0006] A series of simplified concepts are introduced in the summary section, which will be further described in detail in the specific embodiment section. The summary section of the present application does not mean to attempt to limit the key features and necessary technical features of the claimed technical solutions, and even less to determine the protection scope of the claimed technical solutions.

[0007] In view of the existing problems, the present application provides a manufacturing method of a MEMS pressure sensor, comprising:

[0008] A first substrate is provided, and at least two first pressure structures are formed on a surface of the first substrate, each of the first pressure structures comprising, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer, and a second support layer, further comprising a first cavity between the first support layer and the first electrode layer, and a plurality of first release holes penetrating through the second support layer, the second electrode layer, and the first support layer and exposing the first cavity;

[0009] A second substrate is provided, and at least two second pressure structures are formed on a surface of the second substrate, each of the second pressure structures comprising, from bottom to top, a third electrode layer and a second sacrificial layer, further comprising a second cavity in the second sacrificial layer and exposing the third electrode layer;

[0010] The second support layer is bonded with the second sacrificial layer, wherein the first cavity and the second cavity are arranged corresponding to each other;

[0011] The second substrate is removed to expose the third electrode layer, the third electrode layer and the second electrode layer form a variable capacitance structure, the second electrode layer and the first electrode layer form a reference capacitance structure, and the two variable capacitance structures and the two reference capacitance structures together form a Wheatstone bridge.

[0012] In some embodiments, the second pressure structure further comprises a third support layer on the second sacrificial layer, the third support layer is formed with a plurality of second release holes penetrating through the third support layer and exposing the second cavity, and the bonding step joins the second support layer and the third support layer, wherein the plurality of first release holes and the plurality of second release holes are arranged one-to-one corresponding to each other.

[0013] In some embodiments, after exposing the third electrode layer, the method further comprises:

[0014] First pads and second pads are formed, each of the first pads is electrically connected to one of the first electrode layers and one of the third electrode layers, and each of the second pads is electrically connected to one of the second electrode layers.

[0015] Exemplarily, the third electrode layer comprises first sub-electrode layers and second sub-electrode layers arranged in intervals, the second cavity exposes the first sub-electrode layers, the second sub-electrode layers are located outside the second cavity, each of the first pads is located on one of the first sub-electrode layers, each of the second pads is located on one of the second sub-electrode layers, and the first sub-electrode layers and the second electrode layers form the variable capacitance structure;

[0016] The first pressure structure further comprises a first conductive contact penetrating through the second support layer, the second electrode layer, the first support layer and the first sacrificial layer and electrically connecting the first electrode layer, and a second conductive contact penetrating through the second support layer and electrically connecting the second electrode layer;

[0017] The second pressure structure further comprises a third conductive contact penetrating through the second sacrificial layer and electrically connecting the first sub-electrode layer, and a fourth conductive contact penetrating through the second sacrificial layer and electrically connecting the second sub-electrode layer;

[0018] The first conductive contact and the third conductive contact are electrically connected to constitute a first conductive structure in the bonding step, the second conductive contact and the fourth conductive contact are electrically connected to constitute a second conductive structure in the bonding step, the first pad is electrically connected to the first electrode layer through the first conductive structure, and the second pad is electrically connected to the second electrode layer through the second conductive structure.

[0019] In some embodiments, the materials of the first conductive contact, the second conductive contact, the third conductive contact and the fourth conductive contact comprise copper, and the bonding is performed by a copper hybrid bonding process.

[0020] In some embodiments, a first insulating layer is further formed between the first substrate and the first electrode layer, and the material of the first insulating layer comprises one of oxide, nitride and oxynitride of silicon.

[0021] In some embodiments, a second insulating layer is further formed between the second substrate and the third electrode layer, and the material of the second insulating layer comprises one of oxide, nitride and oxynitride of silicon.

[0022] Another aspect of the present application provides a MEMS pressure sensor, comprising:

[0023] a first substrate;

[0024] at least two first pressure structures arranged at intervals and located on the surface of the first substrate, each of the first pressure structures comprising, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer and a second support layer, further comprising a first cavity between the first support layer and the first electrode layer, and a plurality of first release holes penetrating through the second support layer, the second electrode layer and the first support layer and exposing the first cavity;

[0025] at least two second pressure structures spaced apart from each other and located on the second support layer, each of the second pressure structures comprising, from bottom to top, a second sacrificial layer and a third electrode layer, the second pressure structure further comprising a second cavity formed in the second sacrificial layer and exposing the third electrode layer, the second cavity and the first cavity being arranged corresponding to each other;

[0026] wherein one of the third electrode layers and one of the second electrode layers form a variable capacitance structure, one of the second electrode layers and one of the first electrode layers form a reference capacitance structure, and two of the variable capacitance structures and two of the reference capacitance structures together form a Wheatstone bridge.

[0027] In some embodiments, the second pressure structure further comprises a third support layer, the second sacrificial layer is located on the third support layer, and a plurality of second release holes are formed in the third support layer and expose the second cavity, wherein the plurality of first release holes and the plurality of second release holes are arranged corresponding to each other one by one.

[0028] In some embodiments, the third electrode layer comprises a first sub-electrode layer and a second sub-electrode layer spaced apart from each other, the second cavity exposes the first sub-electrode layer, and the second sub-electrode layer is located outside the second cavity, and the MEMS pressure sensor further comprises:

[0029] one or more first conductive structures, each of the first conductive structures penetrating through the second sacrificial layer, the second support layer, the second electrode layer, the first support layer and the first sacrificial layer and electrically connecting one of the first electrode layers and one of the first sub-electrode layers;

[0030] one or more second conductive structures, each of the second conductive structures penetrating through the second sacrificial layer and the second support layer and electrically connecting one of the second electrode layers and one of the second sub-electrode layers;

[0031] one or more first pads located on the first sub-electrode layer, each of the first pads electrically connecting one of the first electrode layers through one of the first conductive structures;

[0032] one or more second pads located on the second sub-electrode layer, each of the second pads electrically connecting one of the second electrode layers through one of the second conductive structures.

[0033] In some embodiments, the first conductive structures and the second conductive structures are made of copper.

[0034] In some embodiments, the MEMS pressure sensor further comprises a first insulating layer between the first substrate and the first electrode layer, and the first insulating layer is made of one of an oxide, a nitride and an oxynitride of silicon.

[0035] In some embodiments, the MEMS pressure sensor further comprises a second insulating layer between the second substrate and the third electrode layer, and the second insulating layer is made of one of an oxide, a nitride and an oxynitride of silicon.

[0036] In still another aspect, the present application provides an electronic device comprising the MEMS pressure sensor of any of the preceding embodiments.

[0037] The MEMS pressure sensor and the manufacturing method thereof, and the electronic device according to the embodiments of the present application, the third electrode layer and the second electrode layer form a variable capacitance structure, the second electrode layer and the first electrode layer form a reference capacitance structure, and the two variable capacitance structures and the two reference capacitance structures together form a Wheatstone bridge, and the pressure is measured through the Wheatstone bridge, which effectively improves the problem of high output impedance and weak load capacity of the conventional capacitive pressure sensor, and improves the measurement accuracy, and further improves the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device, and reduces the cost. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the embodiment or related art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0039] FIG. 1 is a flow chart of a manufacturing method of a MEMS pressure sensor according to an embodiment of the present application.

[0040] FIGS. 2A to 2E are cross-sectional schematic views of devices obtained by sequentially implementing the manufacturing method of the MEMS pressure sensor according to some embodiments of the present application.

[0041] FIG. 3 is a schematic view of a circuit structure of a Wheatstone bridge according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] The application will be described in greater detail with reference to the drawings. The drawings show some embodiments of the application. However, the application can be implemented in forms different from those disclosed here without departing from the scope of the application. The application is not to be interpreted as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete. It will be apparent that the drawings described below are only some embodiments of the application and that other drawings can be obtained from these drawings by a person of ordinary skill in the art without any creative effort. In the drawings, the size and relative sizes of layers and regions can be exaggerated for clarity. The same reference numbers in the specification denote the same elements throughout.

[0043] It will be understood that when an element or layer is referred to as being "on", "adjacent", "connected to", or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly adjacent", "directly connected to", or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0044] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] Embodiments of the application are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the present application. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments of the present application should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and / or a gradient of implant concentration at its edges rather than a binary change between implanted and non-implanted regions. Similarly, a buried region formed by implantation can result in some implantation in a region between the buried region and a surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the present application.

[0047] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this present application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and / or the present specification, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0048] For a more complete understanding of the present application, reference is made to the following description and appended claims taken in conjunction with the accompanying drawings. Preferred embodiments of the present application are described in detail below with reference to the following figures.

[0049] Therefore, in view of the foregoing technical problems, the present application provides a manufacturing method of a MEMS pressure sensor, as shown in FIG. 1, which mainly comprises the following steps S1-S4.

[0050] Step S1: providing a first substrate, at least two first pressure structures are formed on the surface of the first substrate, each first pressure structure comprises, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer and a second support layer, further comprising a first cavity between the first support layer and the first electrode layer, and a plurality of first release holes penetrating through the second support layer, the second electrode layer and the first support layer and exposing the first cavity.

[0051] Step S2: providing a second substrate, at least two second pressure structures are formed on the surface of the second substrate, each second pressure structure comprises, from bottom to top, a third electrode layer and a second sacrificial layer, the second pressure structure further comprises a second cavity in the second sacrificial layer and exposing the third electrode layer.

[0052] Step S3: bonding the second support layer with the second sacrificial layer, wherein the first cavity and the second cavity are arranged corresponding to each other.

[0053] In some embodiments, the first cavity and the second cavity arranged corresponding to each other can be arranged in vertical direction.

[0054] Step S4: removing the second substrate to expose the third electrode layer, the third electrode layer and the second electrode layer constitute a variable capacitance structure, the second electrode layer and the first electrode layer constitute a reference capacitance structure, and the two variable capacitance structures and the two reference capacitance structures together constitute a Wheatstone bridge.

[0055] According to the manufacturing method of the MEMS pressure sensor of the present application, the third electrode layer and the second electrode layer constitute a variable capacitance structure, the second electrode layer and the first electrode layer constitute a reference capacitance structure, and the two variable capacitance structures and the two reference capacitance structures together constitute a Wheatstone bridge, through which the pressure is measured, effectively improving the problem of high output impedance and weak load capacity existing in conventional capacitive pressure sensors, and improving the measurement accuracy, thereby improving the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device, thereby reducing the cost.

[0056] Embodiment one

[0057] The manufacturing method of the MEMS pressure sensor of the present application will be described in detail below with reference to FIG. 1, FIG. 2A to FIG. 2E and FIG. 3, wherein FIG. 1 shows a flow chart of the manufacturing method of the MEMS pressure sensor according to an embodiment of the present application, FIG. 2A to FIG. 2E show the cross-sectional schematic diagrams of the devices obtained by sequentially implementing the manufacturing method of the MEMS pressure sensor according to some embodiments of the present application, and FIG. 3 shows a schematic diagram of the circuit structure of the Wheatstone bridge according to an embodiment of the present application.

[0058] Exemplarily, the manufacturing method of the MEMS pressure sensor of the present application comprises the following steps.

[0059] Firstly, step S1 is performed to provide a first substrate, at least two first pressure structures are formed on the surface of the first substrate, the first pressure structure comprises, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer and a second support layer, further comprises a first cavity between the first support layer and the first electrode layer, and a plurality of first release holes penetrating through the second support layer, the second electrode layer and the first support layer and exposing the first cavity.

[0060] In one example, as shown in FIG. 2A, the first substrate 210 is a bulk silicon substrate, which can be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs or other III / V compound semiconductors, further includes a multi-layer structure composed of these semiconductors, etc., or a silicon-on-insulator (SOI), a stacked silicon-on-insulator (SSOI), a stacked silicon germanium-on-insulator (S-SiGeOI), a silicon germanium-on-insulator (SiGeOI) and a germanium-on-insulator (GeOI), etc.

[0061] In one example, as shown in FIG. 2A, at least two first pressure structures are formed on the surface of the first substrate 310, the first pressure structure comprises, from bottom to top, a first electrode layer 211, a first sacrificial layer 212, a first support layer 213, a second electrode layer 214 and a second support layer 215, further comprises a first cavity 216 between the first support layer 213 and the first electrode layer 211, and a plurality of first release holes 217 penetrating through the second support layer 215, the second electrode layer 214 and the first support layer 213 and exposing the first cavity 216. Exemplarily, the first pressure structures are spaced apart refers to that the first electrode layers 211 of two adjacent first pressure structures are spaced apart and the second electrode layers 214 of two adjacent first pressure structures are spaced apart, but other insulating film layers of non-conductive nature of two adjacent first pressure structures can be communicated with each other. For example, as shown in FIG. 2A, the first sacrificial layers 212 and the second support layers 215 of two adjacent first pressure structures are communicated with each other, and the first electrode layers 211 and the second electrode layers 214 of adjacent first pressure structures are isolated by the first sacrificial layers 212.

[0062] In one example, the first electrode layer 211 and the second electrode layer 214 can be made of doped polysilicon or SiGe, and are not limited to a certain material. The first electrode layer 211 and the second electrode layer 214 can be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or a combination thereof. In one example, the first electrode layer 211 and the second electrode layer 214 can be formed by furnace tube growth or selective epitaxial growth (SEG).

[0063] In one example, the first sacrificial layer 212 is made of an oxide layer, such as silicon oxide and carbon-doped silicon oxide (SiOC), and is not limited to the above examples. The first sacrificial layer 212 can be formed by various deposition methods, such as plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), physical vapor deposition (PVD), or atomic layer deposition (ALD).

[0064] In one example, the first support layer 213 and the second support layer 215 are used to improve the strength and stability of the device. The first support layer 213 and the second support layer 215 can be made of SiCN, SiN, SiC, SiON, or other suitable materials that can improve the strength and stability of the device. The first support layer 213 and the second support layer 215 can be formed by various deposition methods, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD).

[0065] In one example, the first cavity 216 is formed by removing part of the first sacrificial layer 212 through the first release hole 217. The first sacrificial layer 212 can be removed by etching, such as wet etching, buffer oxide etchant, or gaseous hydrogen fluoride (VHF). The release boundary of the first sacrificial layer 212 can be set according to actual needs.

[0066] In one example, a first insulating layer can also be formed between the first substrate 210 and the first electrode layer 211, which can include any of a number of dielectric materials, non-limiting examples of which include oxides, nitrides, or oxynitrides, particularly oxides, nitrides, or oxynitrides of silicon. The first insulating layer can be formed using any of a number of methods, non-limiting examples of which include ion implantation methods, thermal or plasma oxidation or nitridation methods, plasma enhanced chemical vapor deposition methods, low pressure chemical vapor deposition methods, or physical vapor deposition methods, among others.

[0067] Next, step S2 is performed to provide a second substrate having at least two spaced-apart second pressure structures formed on a surface thereof, the second pressure structures including, from bottom to top, a third electrode layer and a second sacrificial layer, the second pressure structures further including second cavities in the second sacrificial layer that expose the third electrode layer.

[0068] In one example, as shown in FIG. 2B, the second substrate 220 is a bulk silicon substrate, which can be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors, including multilayer structures of these semiconductors, among others, or a silicon-on-insulator (SOI), a silicon-on-silicon-on-insulator (SSOI), a silicon-germanium-on-silicon-on-insulator (S-SiGeOI), a silicon-germanium-on-insulator (SiGeOI), and a germanium-on-insulator (GeOI), among others.

[0069] In one example, as shown in FIG. 2B, at least two spaced-apart second pressure structures are formed on a surface of the second substrate 220, the second pressure structures including, from bottom to top, a third electrode layer 221 and a second sacrificial layer 222, the second pressure structures further including second cavities 224 in the second sacrificial layer 222 that expose the third electrode layer 221. Exemplarily, the spaced-apart second pressure structures refer to the third electrode layers 221 of adjacent second pressure structures being spaced apart, but other non-conducting, insulating layers of the second pressure structures can be in communication with each other, for example, as shown in FIG. 2B, the second sacrificial layers 222 of adjacent second pressure structures are in communication with each other and separate the third electrode layers 221 of adjacent second pressure structures via the second sacrificial layers 222.

[0070] In one example, the third electrode layer 221 can be made of doped polysilicon, SiGe, or the like, and is not limited to a certain material. The third electrode layer 221 can be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or the like, or can be formed by one of a furnace tube growth and selective epitaxial growth (SEG), and the present application is not limited thereto.

[0071] In one example, the second sacrificial layer 222 is made of an oxide layer, such as silicon oxide or carbon-doped silicon oxide (SiOC), or the like, and is not limited to the above examples. In addition, the second sacrificial layer 222 can be formed by various deposition methods commonly used in the art, such as plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), physical vapor deposition, or atomic layer deposition (ALD), or the like.

[0072] In one example, a second insulating layer can also be formed between the second substrate 220 and the third electrode layer 221. The second insulating layer can be made of any of a plurality of dielectric materials, non-limiting examples of which include oxides, nitrides, or oxynitrides, particularly oxides, nitrides, and oxynitrides of silicon, but not oxides, nitrides, and oxynitrides of other elements. The second insulating layer can be formed by any of a plurality of methods, non-limiting examples of which include ion implantation, thermal or plasma oxidation or nitridation, plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, or physical vapor deposition.

[0073] Next, a step S3 of bonding the second support layer to the second sacrificial layer is performed, wherein the first cavity and the second cavity are arranged corresponding to each other. For example, as shown in FIG. 2C, the second support layer 215 and the second sacrificial layer 222 are bonded, wherein the first cavity 216 and the second cavity 224 are arranged corresponding to each other. In some embodiments, the first cavity 216 and the second cavity 224 arranged corresponding to each other can be arranged in vertical alignment with each other.

[0074] In one example, as shown in FIGS. 2B and 2C, the second pressure structure further includes a third support layer 223 on the second sacrificial layer 222, and a plurality of second release holes 225 are formed in the third support layer 223 to expose the second cavity 224 through the third support layer 223. At this time, in the bonding step, the second support layer 215 and the third support layer 223 are bonded, wherein the first release hole 217 and the second release hole 225 are arranged corresponding to each other. For example, the third support layers 223 of adjacent second pressure structures are in communication with each other.

[0075] In one example, the cavity 224 is formed by removing part of the second sacrificial layer 222 through the second release hole 225. In one example, the second sacrificial layer 222 can be removed by using a conventional etching process in the art, for example, the second sacrificial layer 222 can be removed by using a wet etching process, more specifically, the second sacrificial layer 222 can be removed by using a Buffer Oxide Etchant, or the second sacrificial layer 222 can be removed by using a gaseous hydrogen fluoride (VHF). In one example, the release boundary of the second sacrificial layer 222 can be set according to actual needs, wherein the release boundary refers to the width of the remaining second sacrificial layer 222.

[0076] In one example, the third support layer 223 can further improve the strength and stability of the device. In one example, the third support layer 223 has the same material as the first support layer 213 and the second support layer 215, including but not limited to SiCN, SiN, SiC, SiON, etc. In one example, the third support layer 223 can be formed by using various deposition methods in the art, for example, the third support layer 223 can be formed by using a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or an atomic layer deposition (ALD) method, etc. In one example, because the third support layer 223 and the second support layer 215 have the same material, the bonding effect is better.

[0077] Finally, step S4 is performed to remove the second substrate to expose the third electrode layer, the third electrode layer and the second electrode layer form a variable capacitance structure, the second electrode layer and the first electrode layer form a reference capacitance structure, and the two variable capacitance structures and the two reference capacitance structures together form a Wheatstone bridge. In one example, the second substrate 220 can be removed to expose the third electrode layer 221 by using a conventional thinning process, etc.

[0078] In one example, the corresponding third electrode layer 221 and the second electrode layer 214 constitute a variable capacitance structure, the second electrode layer 214 and the first electrode layer 211 constitute a reference capacitance structure, the capacitance value of the reference capacitance structure is a fixed value, the third electrode layer 221 acts as a pressure-sensitive film layer, when subjected to pressure, the third electrode layer 221 deforms, the distance between the third electrode layer 221 and the second electrode layer 214 changes, and the capacitance value of the variable capacitance structure changes. Because the MEMS pressure sensor of the present application includes at least two first pressure structures and at least two second pressure structures, that is, at least two variable capacitance structures and at least two reference capacitance structures, two variable capacitance structures and two reference capacitance structures constitute a Wheatstone bridge, as shown in FIG. 3, one variable capacitance structure Cs and one reference capacitance structure Cr are respectively arranged on two bridge arms of the Wheatstone bridge, wherein the variable capacitance structure Cs is connected to the positive electrode of the power supply on one bridge arm, and the reference capacitance structure Cr is connected to the positive electrode of the power supply on the other bridge arm. When subjected to pressure, the capacitance value of the variable capacitance structure Cs changes, causing the voltage value of the output voltage between V+ and V- to change, and by measuring the output voltage, the change in the capacitance value of the variable capacitance structure Cs can be obtained, and the magnitude of the corresponding pressure value can be further obtained, that is, the measurement of pressure is completed. Illustratively, the initial capacitance values of the variable capacitance structure Cs and the reference capacitance structure Cr can be set to equal capacitance values, at which time the Wheatstone bridge is in a balanced state, and the output voltage is 0. When subjected to pressure, the Wheatstone bridge is unbalanced, and the output voltage changes from 0. The change in the output voltage is easier to measure, and the magnitude of the corresponding pressure value is also easier to obtain. Illustratively, the Wheatstone bridge composed of two variable capacitance structures and two reference capacitance structures can effectively improve the problem of high output impedance and weak load capacity existing in conventional capacitive pressure sensors, and can improve the measurement accuracy, thereby improving the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device and reduce the cost.

[0079] In one example, as shown in FIG. 2E, after the third electrode layer 221 is exposed, the method of the present application further includes forming first pads 230 and second pads 240, wherein each first pad 230 is electrically connected to one first electrode layer 211 and one third electrode layer 221, and each second pad 240 is electrically connected to one second electrode layer 214. Illustratively, the first electrode layer 211 and the third electrode layer 221 are led out through the first pad 230 and connected to an external circuit, at which time the first electrode layer 211 and the third electrode layer 221 are at the same potential; the second electrode layer 214 is led out through the second pad 240 and connected to an external circuit. Illustratively, the first pad 230 and the second pad 240 can be formed by sputtering or evaporation, etc.

[0080] In one example, as shown in FIGS. 2B to 2E, the third electrode layer 221 includes first sub-electrode layers 2211 and second sub-electrode layers 2212 arranged in intervals, the second cavities 224 expose the first sub-electrode layers 2211, and the second sub-electrode layers 2212 are located outside the second cavities 224, each first pad 230 is located on one first sub-electrode layer 2211, and each second pad 240 is located on one second sub-electrode layer 2212. The first sub-electrode layers 2211 and the second electrode layer 214 constitute a variable capacitance structure.

[0081] In one example, as shown in FIG. 2A, the first pressure structure further includes a first conductive contact 218 penetrating through the second support layer 215, the second electrode layer 214, the first support layer 213, and the first sacrificial layer 212 and electrically connecting the first electrode layer 211, and a second conductive contact 219 penetrating through the second support layer 215 and electrically connecting the second electrode layer 214. Illustratively, the sidewalls of the first conductive contact 218 and the second conductive contact 219 are covered by the second support layer 215 to function as isolation of the first conductive contact 218 and the second conductive contact 219. In other embodiments, the sidewalls of the first conductive contact 218 and the second conductive contact 219 can also be covered by other insulating materials.

[0082] In one example, as shown in FIG. 2B, the second pressure structure further includes a third conductive contact 226 penetrating through the second sacrificial layer 222 and electrically connecting the first sub-electrode layer 2211, and a fourth conductive contact 227 penetrating through the second sacrificial layer 222 and electrically connecting the second sub-electrode layer 2212. Illustratively, when the third support layer 223 is formed, the third conductive contact 226 and the fourth conductive contact 227 also penetrate through the third support layer 223. Illustratively, the sidewalls of the third conductive contact 226 and the fourth conductive contact 227 are covered by the third support layer 223 to function as isolation of the third conductive contact 226 and the fourth conductive contact 227. In other embodiments, the sidewalls of the third conductive contact 226 and the fourth conductive contact 227 can also be covered by other insulating materials.

[0083] In one example, in the bonding step, the first conductive contact 218 and the third conductive contact 226 electrically connect to constitute a first conductive structure, the second conductive contact 219 and the fourth conductive contact 227 electrically connect to constitute a second conductive structure, the first pad 230 is electrically connected to the first electrode layer through the first conductive structure, and the second pad 240 is electrically connected to the third electrode layer through the second conductive structure, so that the first pad 230 and the second pad 240 can avoid forming a too high step difference, thereby avoiding device packaging difficulties caused by a too high step difference.

[0084] In one example, the material of the first conductive contact 218, the second conductive contact 219, the third conductive contact 226 and the fourth conductive contact 227 includes copper, and a copper hybrid bonding process is used to bond. In this example, the surface of the first conductive contact 218 and the second conductive contact 219 is slightly lower than the surface of the second support layer 215 before bonding; when the third support layer 223 is not formed, the surface of the third conductive contact 226 and the fourth conductive contact 227 is slightly lower than the surface of the second sacrificial layer 222 before bonding; when the third support layer 223 is formed, the surface of the third conductive contact 226 and the fourth conductive contact 227 is slightly lower than the surface of the third support layer 223 before bonding. In the copper hybrid bonding process, the second support layer 215 and the second sacrificial layer 222 are first bonded, or, when the third support layer 223 is formed, the second support layer 215 and the third support layer 223 are bonded; then, a low-temperature annealing process is performed, and because the first conductive contact 218, the second conductive contact 219, the third conductive contact 226 and the fourth conductive contact 227 have a larger thermal expansion coefficient, the first conductive contact 218 and the third conductive contact 226 are expanded and bonded to form a first conductive structure, and the second conductive contact 219 and the fourth conductive contact 227 are expanded and bonded to form a second conductive structure. In this example, the copper hybrid bonding process can effectively reduce the manufacturing difficulty of the device and improve the vertical integration of the device.

[0085] It is worth mentioning that the above steps are only examples, and the order of the above steps can be adjusted without conflict.

[0086] The description of the key steps of the manufacturing method of the MEMS pressure sensor of the present application is completed, and other steps can be included in the complete manufacturing of the MEMS pressure sensor, which will not be described here.

[0087] In summary, according to the manufacturing method of the MEMS pressure sensor of the present application, the third electrode layer and the second electrode layer form a variable capacitance structure, the second electrode layer and the first electrode layer form a reference capacitance structure, the two variable capacitance structures and the two reference capacitance structures together form a Wheatstone bridge, and the pressure is measured through the Wheatstone bridge, effectively improving the problem of high output impedance and weak load capacity of the conventional capacitive pressure sensor, and improving the measurement accuracy, thereby improving the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device and reduce the cost. More specifically, the first sub-electrode layer and the second electrode layer form a variable capacitance structure. Exemplarily, the manufacturing method of the present application has no high heat budget process, which can effectively reduce the influence of heat budget on the device. Exemplarily, the first pad and the second pad have no excessively high step difference, which can effectively reduce the influence on packaging. Exemplarily, the bonding is performed through the copper hybrid bonding process, which can effectively reduce the manufacturing difficulty of the device and improve the vertical integration of the device.

[0088] Embodiment two

[0089] The present application also provides a MEMS pressure sensor, which is manufactured by the method in the foregoing embodiment one, as shown in FIG. 2E, the MEMS pressure sensor of the present application comprises:

[0090] a first substrate 210;

[0091] at least two first pressure structures arranged at intervals, located on the surface of the first substrate 210, each first pressure structure comprises a first electrode layer 211, a first sacrificial layer 212, a first support layer 213, a second electrode layer 214 and a second support layer 215 from bottom to top, further comprising a first cavity 216 between the first support layer 213 and the first electrode layer 211, and a plurality of first release holes 217 penetrating through the second support layer 215, the second electrode layer 214 and the first support layer 213 and exposing the first cavity 216;

[0092] at least two second pressure structures arranged at intervals, located on the second support layer 215, each second pressure structure comprises a second sacrificial layer 222 and a third electrode layer 221 from bottom to top, the second pressure structure further comprises a second cavity 224 in the second sacrificial layer 222 and exposing the third electrode layer 221, and the second cavity 224 and the first cavity 216 are arranged corresponding to each other;

[0093] wherein one third electrode layer 221 and one second electrode layer 214 form a variable capacitance structure, one second electrode layer 214 and one first electrode layer 211 form a reference capacitance structure, and two variable capacitance structures and two reference capacitance structures together form a Wheatstone bridge.

[0094] In one example, as shown in FIG. 2E and FIG. 3, the corresponding third electrode layer 221 and the second electrode layer 214 constitute a variable capacitance structure, the second electrode layer 214 and the first electrode layer 211 constitute a reference capacitance structure, the capacitance value of the reference capacitance structure is a fixed value, the third electrode layer 221 acts as a pressure-sensitive film layer, when subjected to pressure, the third electrode layer 221 deforms, the distance between the third electrode layer 221 and the second electrode layer 214 changes, and the capacitance value of the variable capacitance structure changes. Because the MEMS pressure sensor of the present application includes at least two first pressure structures and at least two second pressure structures, i.e., at least two variable capacitance structures and at least two reference capacitance structures, the two variable capacitance structures and the two reference capacitance structures constitute a Wheatstone bridge, as shown in FIG. 3, one variable capacitance structure Cs and one reference capacitance structure Cr are respectively arranged on two bridge arms of the Wheatstone bridge, wherein the variable capacitance structure Cs is connected to the positive electrode of the power supply on one bridge arm, and the reference capacitance structure Cr is connected to the positive electrode of the power supply on the other bridge arm. When subjected to pressure, the capacitance value of the variable capacitance structure Cs changes, causing the voltage value of the output voltage between V+ and V- to change, and by measuring the output voltage, the change in the capacitance value of the variable capacitance structure Cs can be obtained, and the magnitude of the corresponding pressure value can be further obtained, i.e., the measurement of pressure is completed. Exemplarily, the initial capacitance values of the variable capacitance structure Cs and the reference capacitance structure Cr can be set to equal capacitance values, at which time the Wheatstone bridge is in a balanced state and the output voltage is 0. When subjected to pressure, the Wheatstone bridge is unbalanced and the output voltage changes from 0, and the change in the output voltage is easier to measure, so the magnitude of the corresponding pressure value is easier to obtain. Thus, the Wheatstone bridge composed of two variable capacitance structures and two reference capacitance structures can effectively improve the problem of high output impedance and weak load capacity existing in conventional capacitive pressure sensors, and can improve the measurement accuracy, thereby improving the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device and reduce the cost.

[0095] In one example, as shown in FIG. 2E, the second pressure structure further includes a third support layer 223, the second sacrificial layer 222 is located on the third support layer 223, and a plurality of second release holes 225 are formed in the third support layer 223, which penetrate through the third support layer 223 and expose the second cavities 224, wherein the plurality of first release holes 217 and the plurality of second release holes 225 are arranged one-to-one respectively.

[0096] In one example, as shown in FIGS. 2B and 2E, the third electrode layer 221 includes a first sub-electrode layer 2211 and a second sub-electrode layer 2212 arranged at intervals, the second cavity 224 exposes the first sub-electrode layer 2211, and the second sub-electrode layer 2212 is located outside the second cavity 224. The MEMS pressure sensor provided by the application further includes: one or more first conductive structures, each first conductive structure penetrates the second sacrificial layer 222, the second support layer 215, the second electrode layer 214, the first support layer 213 and the first sacrificial layer 212 and electrically connects one first electrode layer 211 and one first sub-electrode layer 2211; one or more second conductive structures, each second conductive structure penetrates the second sacrificial layer 222 and the second support layer 215 and electrically connects one second electrode layer 214 and one second sub-electrode layer 2212; one or more first pads 230 located on the first sub-electrode layer 2211, each first pad 230 is electrically connected to one first electrode layer 211 through one first conductive structure; and one or more second pads 240 located on the second sub-electrode layer, each second pad 240 is electrically connected to one second electrode layer 214 through one second conductive structure. Exemplarily, the material of the first conductive structure and the second conductive structure includes copper. Exemplarily, as shown in FIG. 2E, the first conductive structure is composed of the first conductive contact 218 and the third conductive contact 226 electrically connected, and the second conductive structure is composed of the second conductive contact 219 and the fourth conductive contact 227 electrically connected. Exemplarily, the first sub-electrode layer 2211 and the second electrode layer 214 constitute a variable capacitance structure.

[0097] The structure of the MEMS pressure sensor provided by the application has been introduced above, and the complete device can further include other component structures, which are not described herein.

[0098] According to the MEMS pressure sensor provided by the application, the third electrode layer and the second electrode layer constitute a variable capacitance structure, the second electrode layer and the first electrode layer constitute a reference capacitance structure, the two variable capacitance structures and the two reference capacitance structures together constitute a Wheatstone bridge, and the pressure is measured through the Wheatstone bridge, which effectively improves the problem of high output impedance and weak load capacity of the conventional capacitive pressure sensor, improves the measurement precision, and further improves the device performance; and the vertical Wheatstone bridge structure can reduce the planar size of the device and reduce the cost. Exemplarily, the first pad and the second pad have no excessively high step difference, which can effectively reduce the influence on packaging.

[0099] Embodiment three

[0100] The application further provides an electronic device including the MEMS pressure sensor described in embodiment two or the MEMS pressure sensor manufactured through the method described in embodiment one.

[0101] The electronic device can be a mobile phone, a tablet computer, a notebook computer, a netbook, a game console, a television, a VCD, a DVD, a navigator, a camera, a video camera, a voice recorder, an MP3, an MP4, a PSP, or any other electronic product or device, or can be an intermediate product having the MEMS pressure sensor, such as a mobile phone mainboard having the integrated circuit. The electronic device of the embodiment of the present application has better performance due to the use of the MEMS pressure sensor.

[0102] The technical features of the above embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, but it should be understood that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in contradictions.

[0103] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for manufacturing a microelectromechanical system (MEMS) pressure sensor, comprising: A first substrate is provided, and at least two spaced-apart first pressure structures are formed on the surface of the first substrate. Each first pressure structure includes, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer, and a second support layer, and also includes a first cavity located between the first support layer and the first electrode layer, and a plurality of first release holes penetrating the second support layer, the second electrode layer, and the first support layer and exposing the first cavity. A second substrate is provided, and at least two spaced-apart second pressure structures are formed on the surface of the second substrate. Each second pressure structure includes a third electrode layer and a second sacrificial layer from bottom to top. The second pressure structure also includes a second cavity located in the second sacrificial layer and exposing the third electrode layer. The second support layer and the second sacrificial layer are bonded together, wherein the first cavity and the second cavity are disposed correspondingly to each other; The second substrate is removed to expose the third electrode layer, which together with the second electrode layer forms a variable capacitor structure. The second electrode layer and the first electrode layer form a reference capacitor structure. The two variable capacitor structures and the two reference capacitor structures together form a Wheatstone bridge.

2. The manufacturing method according to claim 1, wherein the second pressure structure further comprises a third support layer located on the second sacrificial layer, wherein a plurality of second release holes are formed in the third support layer, penetrating the third support layer and exposing the second cavity, and the bonding step joins the second support layer and the third support layer, wherein, The plurality of first release holes and the plurality of second release holes are respectively provided in a one-to-one correspondence.

3. The manufacturing method according to claim 1, wherein after exposing the third electrode layer, the method further comprises: One or more first pads and one or more second pads are formed, each first pad being electrically connected to a first electrode layer and a third electrode layer, and each second pad being electrically connected to a second electrode layer.

4. The manufacturing method according to claim 3, wherein The third electrode layer includes a first sub-electrode layer and a second sub-electrode layer spaced apart. The second cavity exposes the first sub-electrode layer. The second sub-electrode layer is located outside the second cavity. Each first pad is located on a first sub-electrode layer, and each second pad is located on a second sub-electrode layer. The first sub-electrode layer and the second electrode layer constitute the variable capacitor structure. The first pressure structure further includes a first conductive contact that penetrates the second support layer, the second electrode layer, the first support layer and the first sacrificial layer and is electrically connected to the first electrode layer, and a second conductive contact that penetrates the second support layer and is electrically connected to the second electrode layer; The second pressure structure further includes a third conductive contact that penetrates the second sacrificial layer and is electrically connected to the first sub-electrode layer, and a fourth conductive contact that penetrates the second sacrificial layer and is electrically connected to the second sub-electrode layer; The first conductive contact and the third conductive contact are electrically connected in the bonding step to form a first conductive structure, and the second conductive contact and the fourth conductive contact are electrically connected in the bonding step to form a second conductive structure. The first pad is electrically connected to the first electrode layer through the first conductive structure, and the second pad is electrically connected to the second electrode layer through the second conductive structure.

5. The manufacturing method according to claim 4, wherein the first conductive contact, the second conductive contact, the third conductive contact and the fourth conductive contact are made of copper, and the bonding is performed using a copper hybrid bonding process.

6. The manufacturing method according to claim 1, wherein a first insulating layer is further formed between the first substrate and the first electrode layer, the material of the first insulating layer including one of silicon oxide, nitride and oxynitride.

7. The manufacturing method according to claim 1, wherein a second insulating layer is further formed between the second substrate and the third electrode layer, the material of the second insulating layer including one of silicon oxide, nitride and oxynitride.

8. A microelectromechanical system (MEMS) pressure sensor, comprising: First substrate; At least two spaced-apart first pressure structures are located on the surface of the first substrate. Each first pressure structure includes, from bottom to top, a first electrode layer, a first sacrificial layer, a first support layer, a second electrode layer, and a second support layer. It also includes a first cavity located between the first support layer and the first electrode layer, and a plurality of first release holes penetrating the second support layer, the second electrode layer, and the first support layer and exposing the first cavity. At least two spaced-apart second pressure structures are located on the second support layer. Each second pressure structure includes a second sacrificial layer and a third electrode layer from bottom to top. The second pressure structure also includes a second cavity located in the second sacrificial layer and exposing the third electrode layer. The second cavity and the first cavity are arranged corresponding to each other. In this structure, one of the third electrode layers and one of the second electrode layers constitute a variable capacitor structure, one of the second electrode layers and one of the first electrode layers constitute a reference capacitor structure, and the two variable capacitor structures and the two reference capacitor structures together constitute a Wheatstone bridge.

9. The MEMS pressure sensor according to claim 8, wherein the second pressure structure further comprises a third support layer, the second sacrificial layer is located on the third support layer, and a plurality of second release holes are formed in the third support layer, penetrating the third support layer and exposing the second cavity, wherein, The plurality of first release holes and the plurality of second release holes are respectively provided in a one-to-one correspondence.

10. The MEMS pressure sensor according to claim 8, wherein the third electrode layer comprises a first sub-electrode layer and a second sub-electrode layer spaced apart, the second cavity exposes the first sub-electrode layer, the second sub-electrode layer is located outside the second cavity, and the MEMS pressure sensor further comprises: One or more first conductive structures, each first conductive structure passing through the second sacrificial layer, the second support layer, the second electrode layer, the first support layer and the first sacrificial layer and electrically connected to a first electrode layer and a first sub-electrode layer; One or more second conductive structures, each second conductive structure penetrating the second sacrificial layer and the second support layer and electrically connected to a second electrode layer and a second sub-electrode layer; One or more first pads are located on the first sub-electrode layer, and each first pad is electrically connected to a first electrode layer through a first conductive structure. One or more second pads are located on the second sub-electrode layer, and each second pad is electrically connected to the second electrode layer through a second conductive structure.

11. The MEMS pressure sensor according to claim 10, wherein the first conductive structure and the second conductive structure are made of copper.

12. The MEMS pressure sensor according to claim 8 further includes a first insulating layer located between the first substrate and the first electrode layer, wherein the material of the first insulating layer includes one of silicon oxide, nitride and oxynitride.

13. The MEMS pressure sensor according to claim 8 further includes a second insulating layer located between the second substrate and the third electrode layer, wherein the material of the second insulating layer includes one of silicon oxide, nitride and oxynitride.

14. An electronic device comprising a MEMS pressure sensor according to any one of claims 8 to 13.

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