CN116659711B - MEMS pressure sensor and electronic equipment - Google Patents
MEMS pressure sensor and electronic equipment Download PDFInfo
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- CN116659711B CN116659711B CN202310938869.XA CN202310938869A CN116659711B CN 116659711 B CN116659711 B CN 116659711B CN 202310938869 A CN202310938869 A CN 202310938869A CN 116659711 B CN116659711 B CN 116659711B
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- 238000001514 detection method Methods 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 10
- 230000007613 environmental effect Effects 0.000 description 5
- 238000002955 isolation Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 3
- 238000009530 blood pressure measurement Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
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- 238000013461 design Methods 0.000 description 1
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- 238000005530 etching Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
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- 239000011295 pitch Substances 0.000 description 1
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- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
- G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
- G01L1/148—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors using semiconductive material, e.g. silicon
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/12—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in capacitance, i.e. electric circuits therefor
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Abstract
The application discloses an MEMS pressure sensor and electronic equipment. The MEMS pressure sensor comprises a substrate, a vibrating diaphragm and a back electrode plate which are sequentially arranged in a laminated mode, wherein the back electrode plate comprises an insulating layer and a conducting layer fixedly connected with the insulating layer, the conducting layer comprises a first electrode area and a second electrode area which are mutually isolated, the first electrode area and the second electrode area respectively form a first capacitor and a second capacitor with the vibrating diaphragm, and when the MEMS pressure sensor is in a working state, the difference value of the first capacitor and the second capacitor is configured to be in a linear relation with the pressure applied to the MEMS pressure sensor. The technical scheme disclosed by the application is beneficial to improving the accuracy and linearity of the pressure detection of the MEMS pressure sensor.
Description
Technical Field
The application relates to the field of semiconductor device manufacturing, in particular to an MEMS pressure sensor and electronic equipment.
Background
The structure of the traditional capacitive pressure sensor is generally composed of metal diaphragms on two sides and a central diaphragm, and the sensor has the advantages of high measuring range of products, low testing precision, large size of finished products and limited application.
With the increasing miniaturization, MEMS (Micro-Electro-Mechanical System, microelectromechanical system) pressure sensors also begin to suffer from performance problems. For example, problems with insensitivity, inaccuracy and signal drift occur.
Accordingly, improvements in the art are needed.
Disclosure of Invention
The application aims to at least solve one of the technical problems in the prior art and provides an MEMS pressure sensor and electronic equipment.
According to an aspect of the present application, there is provided a MEMS pressure sensor comprising:
a substrate, a diaphragm and a back plate which are sequentially arranged in a laminated manner, wherein the substrate is provided with a back cavity penetrating in the thickness direction;
the back electrode plate comprises an insulating layer and a conductive layer fixedly connected with the insulating layer, the conductive layer comprises a first electrode area and a second electrode area which are isolated from each other, the first electrode area forms a first electrode, the second electrode area forms a second electrode, the vibrating diaphragm forms a third electrode, the first electrode and the third electrode form a first capacitor, and the second electrode and the third electrode form a second capacitor;
the difference between the first capacitance and the second capacitance is configured to be in a linear relationship with a pressure applied to the MEMS pressure sensor when the MEMS pressure sensor is in an operational state.
Further, with the geometric center of the diaphragm as the center of a circle, the axial distance from any point on the first electrode area to the geometric center of the diaphragm is unequal to the axial distance from any point on the second electrode area to the geometric center of the diaphragm.
Further, the first capacitance and the second capacitance are configured to be equal when the MEMS pressure sensor is in a non-operational state.
In some embodiments, the first electrode region and the second electrode region are both disposed within a projection range of a vibration region of the diaphragm in a thickness direction of the substrate.
In some embodiments, the first electrode region and the second electrode region are equal in area.
In some embodiments, the first electrode region and the second electrode region are disposed concentrically.
In some embodiments, one of the first electrode region and the second electrode region is surrounded by the other.
In some embodiments, one of the first electrode region and the second electrode region includes a first portion surrounded by the other and a second portion surrounding the other.
In some embodiments, the first electrode region is located on one side of the second electrode region,
the first electrode area and the second electrode area are matched to form an annular area, and the annular area and the vibration area of the vibrating diaphragm are eccentrically arranged.
In some embodiments, the first electrode region and the second electrode region are disposed in axial symmetry.
In some embodiments, in the thickness direction of the substrate, one of the first electrode region and the second electrode region is disposed within a projection range of the vibration region of the diaphragm, and a partial region of the other is disposed outside the projection range of the vibration region of the diaphragm.
Further, a linear relationship between a difference of the first capacitance and the second capacitance and the pressure applied to the MEMS pressure sensor is adjusted based on adjusting the stiffness of the diaphragm.
In some embodiments, a first insulator with a part of the region penetrating is arranged between the diaphragm and the substrate, and a second insulator with a part of the region penetrating is arranged between the back electrode plate and the diaphragm.
In some embodiments, the back plate is provided with at least one through hole penetrating the back plate in a thickness direction.
In some embodiments, a first anti-sticking structure is arranged on one side of the insulating layer of the back electrode plate, which faces the vibrating diaphragm; and in the thickness direction of the substrate, the orthographic projection of the first anti-sticking structure on the vibrating diaphragm is positioned in the range of orthographic projection of the back cavity on the vibrating diaphragm.
In some embodiments, the first release structure is integrally formed with the insulating layer of the back plate.
In some embodiments, the MEMS pressure sensor further comprises a signal processing circuit chip, wherein the signal processing circuit chip is respectively and electrically connected with the first capacitor and the second capacitor to receive and process signal output of the MEMS pressure sensor corresponding to each working state;
and carrying out preset differential operation on the signal output values of the first capacitor and the second capacitor corresponding to the MEMS pressure sensor when the MEMS pressure sensor is in each working state so as to obtain differential output corresponding to the MEMS pressure sensor.
According to another aspect of the present application, there is further provided an electronic device including the MEMS pressure sensor according to any one of the above embodiments of the present application.
The MEMS pressure sensor and the electronic device provided by the application have at least one advantage that: by using the difference value of the first capacitor and the second capacitor as the sensing capacitor of the actual MEMS pressure sensor, zero drift caused by the environmental capacitor is restrained, and the accuracy of pressure detection of the MEMS pressure sensor is improved.
Furthermore, the problem of non-linearity of the output of the MEMS pressure sensor can be solved under the rigidity of a specific vibrating diaphragm, the difference value of the first capacitor and the second capacitor is used as a capacitance value which is actually sensed to represent the pressure applied to the MEMS pressure sensor, and the pressure is in a linear relation with the pressure applied to the MEMS pressure sensor, so that the high-precision and small-range pressure measurement is realized. The technical solution and other advantageous effects of the present application will be made apparent by the following detailed description of the specific embodiments of the present application with reference to the accompanying drawings.
Drawings
Fig. 1 shows a schematic structural diagram of a MEMS pressure sensor according to an embodiment of the present application.
Fig. 2 is a schematic top view of the back plate in fig. 1.
Fig. 3 is a schematic cross-sectional structural view of the MEMS pressure sensor provided in fig. 2.
Fig. 4A is a schematic structural diagram of an electrical connection between a MEMS pressure sensor and a signal processing circuit chip according to an embodiment of the present application.
FIG. 4B shows a schematic diagram of a comparison of a pressure nonlinear output in the prior art with a pressure linear output in an embodiment of the present application.
Fig. 5 is a schematic top view of a back plate of a MEMS pressure sensor according to another embodiment of the present application.
Fig. 6 is a schematic top view of a back plate of a MEMS pressure sensor according to still another embodiment of the present application.
Fig. 7 is a schematic structural diagram of a MEMS pressure sensor according to another embodiment of the present application.
Fig. 8 is a schematic top view of the back plate of fig. 7.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
The MEMS pressure sensor and the electronic device according to the present application will be described in detail with reference to the accompanying drawings and the embodiments.
An embodiment of the present application provides an MEMS pressure sensor, including:
a substrate, a diaphragm and a back plate which are sequentially arranged in a laminated manner, wherein the substrate is provided with a back cavity penetrating in the thickness direction;
the back electrode plate comprises an insulating layer and a conductive layer fixedly connected with the insulating layer, the conductive layer comprises a first electrode area and a second electrode area which are isolated from each other, the first electrode area forms a first electrode, the second electrode area forms a second electrode, the vibrating diaphragm forms a third electrode, the first electrode and the third electrode form a first capacitor, and the second electrode and the third electrode form a second capacitor;
the difference between the first capacitance and the second capacitance is configured to be proportional to a pressure applied to the MEMS pressure sensor when the MEMS pressure sensor is in an operational state.
The MEMS pressure sensor has at least one advantage: the capacitance difference detected by an ASIC (Application Specific Integrated Circuit ) chip is intended to be linear with the change of external pressure by optimizing the shape, distribution and design of the first electrode and the second electrode. The problem of nonlinear output of the MEMS pressure sensor can be solved under the rigidity of a specific vibrating diaphragm.
Example 1
Fig. 1 is a schematic structural diagram of a MEMS pressure sensor according to an embodiment of the present application, fig. 2 is a schematic structural diagram of a top view of a back plate in fig. 1, and fig. 3 is a schematic structural diagram of a cross-section of the MEMS pressure sensor provided in fig. 2. FIG. 4B shows a schematic diagram of a comparison of a pressure nonlinear output in the prior art with a pressure linear output in an embodiment of the present application.
As shown in fig. 1-3 and 4B, the MEMS pressure sensor 1000 includes:
a substrate 100, a diaphragm 300, and a back plate 600 sequentially disposed in a stacked manner, the substrate 100 having a back cavity 11 penetrating in a thickness direction thereof;
the back electrode plate 600 includes an insulating layer 610 and a conductive layer 620 fixedly connected to the insulating layer 610, the conductive layer 620 includes a first electrode area 621 and a second electrode area 622 that are isolated from each other, the first electrode area 621 forms a first electrode, the second electrode area 622 forms a second electrode, the diaphragm 300 forms a third electrode, the first electrode and the third electrode form a first capacitor, and the second electrode and the third electrode form a second capacitor;
the first capacitance and the second capacitance are configured to be unequal when the MEMS pressure sensor 1000 is in an operational state, and a difference between the first capacitance and the second capacitance is configured to be in a linear relationship with a pressure applied to the MEMS pressure sensor 1000.
In some embodiments, the backplate 600 includes an isolation structure 640, the isolation structure 640 extending through the conductive layer 620 in a thickness direction to separate the conductive layer 620 into a first electrode region 621 and a second electrode region 622. In particular, the isolation structure 640 may be an isolation groove, and the conductive layer 620 of the back plate 600 is divided into a first electrode region 621 and a second electrode region 622 by the isolation structure 640.
In some embodiments, a first support 200 with a partial region passing through is provided between the diaphragm 300 and the substrate 100, and a second support 400 with a partial region passing through is provided between the back plate 600 and the diaphragm 300.
Illustratively, in the embodiment of the present application, a first support 200 for supporting the diaphragm 300 is disposed on a side of the substrate 100 close to the diaphragm 300, and a second support 400 for supporting the back plate 600 is disposed on a side of the diaphragm 300 away from the substrate 100, where the first support 200 and the second support 400 are insulating supports, such as silicon oxide or silicon nitride.
Illustratively, the first supporting body 200 is located at an edge of the substrate 100 to support the diaphragm 300, so that the diaphragm 300 is suspended above the back cavity 11, where the diaphragm 300 includes a vibration area and a supporting area, and the supporting area is used to overhead the diaphragm 300 above the back cavity 11 through the first supporting body 200. The second support 400 is located at the edge of the diaphragm 300, so that the back plate 600 is suspended above the diaphragm 300 and is insulated from the diaphragm 300. The thickness of the first support 200 and the second support 400 is between 2 um and 3um, for example, about 2.5 um. The third electrode on the diaphragm 300 is respectively opposite to the first electrode and the second electrode on the back plate 600 and is spaced apart from the first electrode and the second electrode, so that an oscillating acoustic cavity for vibrating the diaphragm 300 is formed between the back plate 600 and the diaphragm 300.
It should be noted that, in the embodiment of the present application, the diaphragm 300 is a planar membrane structure located directly above the back cavity 11, and in general, when the MEMS pressure sensor is subjected to an external force, the diaphragm 300 deforms, and the deformation amount (the amplitude of the deformation of the diaphragm) of the diaphragm 300 decreases in sequence along the direction outward from the geometric center of the diaphragm 300.
In order to solve the problem of nonlinearity of the output of the MEMS pressure sensor under the rigidity of a specific vibrating diaphragm, when the MEMS pressure sensor is in a non-working state (not pressed), the shapes and the distributions of the first electrode area and the second electrode area corresponding to the first capacitor and the second capacitor are optimally designed, and when the MEMS pressure sensor is in a working state (pressed), the first capacitor and the second capacitor are configured to be in a linear relation with the pressure applied to the MEMS pressure sensor. And further, high-precision and small-range pressure measurement is realized, and zero drift of the MEMS pressure sensor caused by environmental capacitance can be restrained.
Illustratively, the axial distance from any point on the first electrode area 621 to the geometric center of the diaphragm 300 is not equal to the axial distance from any point on the second electrode area 622 to the geometric center of the diaphragm 300, with the geometric center passing through the diaphragm 300 as an axis. So that when the MEMS pressure sensor 1000 is in an operating state (under pressure), the deformation amount of the diaphragm at the position corresponding to the first electrode area 621 and the deformation amount of the diaphragm at the position corresponding to the second electrode area 622 are unequal, a first capacitance corresponding to the first electrode area 621 and a second capacitance corresponding to the second electrode area 622 are unequal, and thus the pressure applied to the MEMS pressure sensor is characterized by using the difference between the first capacitance and the second capacitance as a capacitance value actually sensed.
Further, the first capacitance and the second capacitance are configured to be equal when the MEMS pressure sensor is in a non-operational state. It should be understood that "equal" in the embodiments of the present application refers to that the initial capacitance values of the first capacitor and the second capacitor are as close as possible or within a certain error range, and are not required to be completely equal, so that the calibration operation of the MEMS pressure sensor in the non-operating state can be achieved.
Further, in the thickness direction of the substrate 100, the first electrode region 621 and the second electrode region 622 are both disposed within a projection range of the vibration region of the diaphragm 300.
In this embodiment, since the dielectric constants of the first capacitor and the second capacitor are equal (both are air media), the pitches of the plate capacitors are also equal, so that the initial capacitance values of the first capacitor and the second capacitor corresponding to the first electrode area 621 and the second electrode area 622 are equal, so as to ensure that the initial capacitance values of the first capacitor and the second capacitor are equal.
In some embodiments, the first electrode region 621 and the second electrode region 622 are disposed concentrically.
Illustratively, one of the first electrode region 621 and the second electrode region is surrounded by the other. For example, the first electrode area 621 is an inner circular electrode, and the second electrode area 622 is an outer circular electrode surrounding the first electrode area 621.
The terms "first" and "second" are used herein to distinguish between different objects, and are not intended to order objects or limit the number of objects, and in addition, the relative positions of the first electrode region and the second electrode region are limited only, and are not limited at all, and the shape of the first electrode region and the second electrode region may be rectangular, circular, annular, or other polygonal shape. The embodiments of the present application are not limited herein.
In some embodiments, at least one through hole 601 penetrating the back plate 600 in the thickness direction is provided on the back plate 600, and the at least one through hole 601 communicates with the back cavity 11, so that air flows through the at least one through hole 601.
Further, in some embodiments, a side of the insulating layer 610 of the back plate 600 facing the diaphragm 300 is provided with a first anti-sticking structure 613; wherein, in the thickness direction of the substrate 100, the orthographic projection of the first anti-sticking structure 613 on the diaphragm 300 is located within the range of the orthographic projection of the back cavity 11 on the diaphragm 300.
Further, in some embodiments, the first release structure 613 is integrally formed with the insulating layer 610 of the backplate 600. Specifically, the first anti-adhesion structure 613 and the insulating layer 610 are made of the same insulating material, and then the first anti-adhesion structure 613 is formed by etching a surface of the insulating layer 610 facing the diaphragm 300.
Further, as shown in fig. 4A, the MEMS pressure sensor further includes a signal processing circuit chip 800, where the signal processing circuit chip 800 is electrically connected to the first capacitor and the second capacitor, respectively, so as to receive and process signal outputs of the MEMS pressure sensor corresponding to respective working states; and carrying out preset differential operation on the signal output values of the first capacitor and the second capacitor corresponding to the MEMS pressure sensor when the MEMS pressure sensor is in each working state so as to obtain differential output corresponding to the MEMS pressure sensor.
In order to clearly express the electrical connection relationship between the micro-electromechanical structure and the signal processing circuit chip 800, the package structure of the MEMS pressure sensor is not shown in fig. 4A.
Illustratively, as shown in fig. 4A, the signal processing circuit chip 800 includes an ASIC (Application Specific Integrated Circuit ) chip for signal amplification. In some embodiments, the MEMS pressure sensor may further include a packaging structure, such as a substrate (e.g., PCB substrate) of the MEMS structure and the signal processing circuitry chip 800, a housing that together with the substrate defines a cavity in which the MEMS structure and the signal processing circuitry chip 800 are located. However, the embodiments of the present application are not limited thereto, and those skilled in the art may make other arrangements for the functions of the package structure of the MEMS pressure sensor as needed.
In some embodiments, the conductive layer 620 includes a first pad 71, a second pad 72, and a third pad 73; the first pad 71 is electrically connected to the first electrode, and is configured to receive or transmit an electrical signal of the first electrode; the second pad 72 is electrically connected to the second electrode, and is configured to receive or transmit an electrical signal of the second electrode; the third pad 73 is electrically connected to the third electrode 310, and is configured to receive or transmit an electrical signal of the third electrode.
It should be appreciated that in some embodiments, the electrical connection of the third pad 73 to the third electrode may be achieved by providing openings through the thickness of the back plate 600 and the second support 400.
Example two
Fig. 5 is a schematic top view of a back plate of a MEMS pressure sensor according to another embodiment of the present application.
As shown in fig. 5, in the present embodiment, unlike the first embodiment, one of the first electrode region 621 and the second electrode region 622 includes a first portion 6211 and a second portion 6212, the first portion 6211 being surrounded by the other, the second portion 6212 being surrounded by the other.
That is, the first electrode area 621 and the second electrode area 622 are intertwined with each other, and by optimizing the shape and distribution of the first electrode area 621 and the second electrode area 622, it is also possible to realize that the first capacitance and the second capacitance are configured to be equal when the MEMS pressure sensor is in a non-operating state, the first capacitance and the second capacitance are configured to be unequal when the MEMS pressure sensor is in an operating state, and the difference between the first capacitance and the second capacitance is configured to have a linear relationship with the pressure applied to the MEMS pressure sensor.
Example III
Fig. 6 is a schematic top view of a back plate of a MEMS pressure sensor according to still another embodiment of the present application.
As shown in fig. 6, in this embodiment, unlike the first and second embodiments, the first electrode area 621 is located at one side of the second electrode area 622, and the first electrode area 621 and the second electrode area 622 cooperate to form an annular area 623, and the annular area 623 is disposed eccentrically with respect to the vibration area of the diaphragm 300.
Illustratively, by adjusting the geometrical center point a of the annular region 623 to be offset with respect to the geometrical center point B of the diaphragm, in other words, there is a misalignment between the geometrical center point a of the annular region 623 and the geometrical center point B of the diaphragm, such that the change between the first capacitance formed by the first electrode region 621 and the second capacitance formed by the second electrode region 622 is different when the MEMS pressure sensor is in an operating state, the difference between the first capacitance and the second capacitance is finally adjusted to enable a linear relationship with the pressure applied to the MEMS pressure sensor. The offset distance between the point a and the point B can be adjusted according to the actual application requirement, and the embodiment of the application is not limited herein.
In some embodiments, the first electrode region 621 and the second electrode region 622 are disposed in axial symmetry.
Example IV
Fig. 7 is a schematic structural diagram of a MEMS pressure sensor according to another embodiment of the present application, and fig. 8 is a schematic structural diagram of a top view of the back plate in fig. 7.
As shown in fig. 7 and 8, unlike the first to third embodiments, in the present embodiment, in the thickness direction of the substrate 100, one of the first electrode region 621 and the second electrode region 622 is disposed within the projection range of the vibration region of the diaphragm 300, and a partial region of the other is disposed outside the projection range of the vibration region of the diaphragm 300.
In some embodiments, a partial region of the second electrode region 622 is disposed outside the projection range of the vibration region of the diaphragm 300. That is, the orthographic projection of the second electrode region 622 on the diaphragm 300 is located near the fixed boundary of the diaphragm 300. In other words, the first electrode area 621 faces the vibration sensitive area of the diaphragm 300, and the second electrode area 622 faces the non-vibration sensitive area of the diaphragm 300. Therefore, when the MEMS pressure sensor is in an operating state, there is a difference between the first capacitance formed by the third electrode and the first electrode and the second capacitance formed by the third electrode and the second electrode.
In order to eliminate zero drift caused by environmental capacitance, the embodiment of the application is based on the fact that when the MEMS sensor is in a non-working state, the patterns of a first electrode area and a second electrode area corresponding to the first capacitance and the second capacitance are optimally designed so as to set initial capacitance values of the corresponding first capacitance and second capacitance to be equal, and the difference value of the first capacitance and the second capacitance is used as a sensed capacitance value of an actual MEMS pressure sensor so as to inhibit zero drift caused by the environmental capacitance, and is configured to be in linear relation with pressure applied to the MEMS pressure sensor so as to realize linear output of the MEMS pressure sensor.
Further, a linear relationship between a difference between the first capacitance and the second capacitance and the pressure applied to the MEMS pressure sensor is adjusted based on adjusting the stiffness of the diaphragm 300.
In some embodiments, the second electrode area 622 may also be disposed entirely outside the projection range of the vibration area of the diaphragm 300.
At least one embodiment of the present application also provides an electronic device including the MEMS pressure sensor according to any one of the embodiments described above.
By adopting the MEMS pressure sensor and the electronic device provided by the embodiment of the application, the zero drift caused by the environmental capacitance is eliminated by utilizing the difference value of the first capacitance and the second capacitance, and the accuracy of pressure detection of the MEMS pressure sensor is greatly improved.
Furthermore, the problem of non-linearity of the output of the MEMS pressure sensor can be solved under the rigidity of a specific vibrating diaphragm, the difference value of the first capacitor and the second capacitor is used as a capacitance value which is actually sensed to represent the pressure applied to the MEMS pressure sensor, and the pressure is in a linear relation with the pressure applied to the MEMS pressure sensor, so that the high-precision and small-range pressure measurement is realized.
In various embodiments of the application, where no special description or logic conflict exists, terms or descriptions between the various embodiments have consistency and may reference each other, and features of the various embodiments may be combined to form new embodiments based on their inherent logic. In the present application, "at least one" means one or more, and "a plurality" means two or more.
It will be appreciated that the various numerical numbers referred to in the embodiments of the present application are merely for ease of description and are not intended to limit the scope of the embodiments of the present application. The sequence number of each process does not mean the sequence of the execution sequence, and the execution sequence of each process should be determined according to the function and the internal logic.
The MEMS pressure sensor and the electronic device provided by the embodiments of the present application are described in detail, and specific examples are applied to illustrate the principles and embodiments of the present application, and the description of the above embodiments is only for helping to understand the MEMS pressure sensor and the core idea of the present application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (17)
1. A MEMS pressure sensor, comprising:
a substrate, a diaphragm and a back plate which are sequentially arranged in a laminated manner, wherein the substrate is provided with a back cavity penetrating in the thickness direction;
the back electrode plate comprises an insulating layer and a conductive layer fixedly connected with the insulating layer, the conductive layer comprises a first electrode area and a second electrode area which are isolated from each other, the first electrode area forms a first electrode, the second electrode area forms a second electrode, the vibrating diaphragm forms a third electrode, the first electrode and the third electrode form a first capacitor, and the second electrode and the third electrode form a second capacitor;
the difference between the first capacitance and the second capacitance is configured to be in a linear relationship with a pressure applied to the MEMS pressure sensor when the MEMS pressure sensor is in an operational state;
the axial distance from any point on the first electrode area to the geometric center of the diaphragm is unequal to the axial distance from any point on the second electrode area to the geometric center of the diaphragm by taking the geometric center passing through the diaphragm as an axis.
2. The MEMS pressure sensor as claimed in claim 1, wherein,
the first capacitance and the second capacitance are configured to be equal when the MEMS pressure sensor is in a non-operational state.
3. The MEMS pressure sensor as claimed in claim 2, wherein,
in the thickness direction of the substrate, the first electrode region and the second electrode region are both disposed within a projection range of the vibration region of the diaphragm.
4. The MEMS pressure sensor as claimed in claim 3, wherein,
the areas of the first electrode region and the second electrode region are equal.
5. The MEMS pressure sensor as claimed in claim 4, wherein,
the first electrode region and the second electrode region are concentrically arranged.
6. The MEMS pressure sensor as claimed in claim 5, wherein,
one of the first electrode region and the second electrode region is surrounded by the other.
7. The MEMS pressure sensor as claimed in claim 5, wherein,
one of the first electrode region and the second electrode region includes a first portion surrounded by the other and a second portion surrounding the other.
8. The MEMS pressure sensor as claimed in claim 4, wherein,
the first electrode region is located on one side of the second electrode region,
the first electrode area and the second electrode area are matched to form an annular area, and the annular area and the vibration area of the vibrating diaphragm are eccentrically arranged.
9. The MEMS pressure sensor as claimed in claim 8, wherein,
the first electrode area and the second electrode area are arranged in an axisymmetric mode.
10. The MEMS pressure sensor as claimed in claim 2, wherein,
in the thickness direction of the substrate, one of the first electrode region and the second electrode region is disposed within a projection range of the vibration region of the diaphragm, and a partial region of the other is disposed outside the projection range of the vibration region of the diaphragm.
11. The MEMS pressure sensor as claimed in claim 10, wherein,
a linear relationship between a difference between the first capacitance and the second capacitance and the pressure applied to the MEMS pressure sensor is adjusted based on adjusting the stiffness of the diaphragm.
12. The MEMS pressure sensor as claimed in claim 1, wherein,
a first support body with a through part area is arranged between the vibrating diaphragm and the substrate, and a second support body with a through part area is arranged between the back electrode plate and the vibrating diaphragm.
13. The MEMS pressure sensor as claimed in claim 1, wherein,
at least one through hole penetrating through the back plate in the thickness direction is formed in the back plate.
14. The MEMS pressure sensor as claimed in claim 1, wherein,
a first anti-sticking structure is arranged on one side, facing the vibrating diaphragm, of the insulating layer of the back electrode plate;
and in the thickness direction of the substrate, the orthographic projection of the first anti-sticking structure on the vibrating diaphragm is positioned in the range of orthographic projection of the back cavity on the vibrating diaphragm.
15. The MEMS pressure sensor as claimed in claim 14, wherein,
the first anti-sticking structure and the insulating layer of the back electrode plate are integrally formed.
16. The MEMS pressure sensor according to any one of claims 1-15, further comprising a signal processing circuit chip,
the signal processing circuit chip is respectively and electrically connected with the first capacitor and the second capacitor to receive and process signal output of the MEMS pressure sensor corresponding to each working state;
and carrying out preset differential operation on the signal output values of the first capacitor and the second capacitor corresponding to the MEMS pressure sensor when the MEMS pressure sensor is in each working state so as to obtain differential output corresponding to the MEMS pressure sensor.
17. An electronic device comprising the MEMS pressure sensor of claim 16.
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