CN119197864A - MEMS capacitive pressure sensor and preparation method thereof - Google Patents
MEMS capacitive pressure sensor and preparation method thereof Download PDFInfo
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- CN119197864A CN119197864A CN202411409458.2A CN202411409458A CN119197864A CN 119197864 A CN119197864 A CN 119197864A CN 202411409458 A CN202411409458 A CN 202411409458A CN 119197864 A CN119197864 A CN 119197864A
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- 238000002360 preparation method Methods 0.000 title abstract description 13
- 239000000758 substrate Substances 0.000 claims abstract description 135
- 229910052751 metal Inorganic materials 0.000 claims description 52
- 239000002184 metal Substances 0.000 claims description 52
- 238000005530 etching Methods 0.000 claims description 34
- 229910052710 silicon Inorganic materials 0.000 claims description 22
- 239000010703 silicon Substances 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 11
- 238000000151 deposition Methods 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 7
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 21
- 239000003990 capacitor Substances 0.000 description 10
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- 238000001514 detection method Methods 0.000 description 3
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
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- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
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Classifications
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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
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
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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]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
-
- 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
- G01L9/125—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 with temperature compensating means
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Measuring Fluid Pressure (AREA)
- Pressure Sensors (AREA)
Abstract
本申请涉及一种MEMS电容式压力传感器及其制备方法，涉及微电子技术领域；压力传感器包括导电衬底；沿导电衬底所在平面方向上，压力传感器包括空腔区和环绕空腔区的边缘区；第一电极层，形成于导电衬底的表面，位于空腔区；第一电极层包括多个绝缘设置的环形第一电极；压力应变膜片，位于第一电极层远离导电衬底的一侧；第二电极层，形成于压力应变膜片朝向第一电极层的一侧，位于空腔区；第二电极层包括多个绝缘设置的环形第二电极；绝缘层，形成于导电衬底和压力应变膜片之间，位于边缘区；沿导电衬底所在平面中的中心点指向边缘区的方向上，第一电极和第二电极交替且间隔设置；有利于避免压力传感器使用时第一电极和第二电极误接触的问题。
The present application relates to a MEMS capacitive pressure sensor and a preparation method thereof, and relates to the field of microelectronic technology; the pressure sensor comprises a conductive substrate; along the plane direction where the conductive substrate is located, the pressure sensor comprises a cavity area and an edge area surrounding the cavity area; a first electrode layer is formed on the surface of the conductive substrate and is located in the cavity area; the first electrode layer comprises a plurality of insulating annular first electrodes; a pressure strain diaphragm is located on a side of the first electrode layer away from the conductive substrate; a second electrode layer is formed on a side of the pressure strain diaphragm facing the first electrode layer and is located in the cavity area; the second electrode layer comprises a plurality of insulating annular second electrodes; an insulating layer is formed between the conductive substrate and the pressure strain diaphragm and is located in the edge area; along the direction from the center point in the plane where the conductive substrate is located to the edge area, the first electrode and the second electrode are alternately and spaced apart; this is conducive to avoiding the problem of the first electrode and the second electrode contacting by mistake when the pressure sensor is used.
Description
Technical Field
The application relates to the technical field of microelectronics, in particular to a MEMS capacitive pressure sensor and a preparation method thereof.
Background
The pressure monitoring requirements of the social production are huge, and the method is particularly suitable for the fields of industry, automobiles and the like. The Micro-Electro-MECHANICAL SYSTEM (MEMS) pressure sensor has better industrialized application due to the advantages of small volume, high performance, strong reliability, low cost, easy mass production, strong portability and the like, and has wide application in consumer electronics, industrial measurement and control, aerospace, medical appliances and automobile manufacturing, and is the most successful case of MEMS sensor marketization.
The main flow technology of the MEMS pressure sensor can be divided into a piezoresistive type and a capacitive type, the piezoresistive type utilizes the piezoresistive effect, and the resistance of the piezoresistive material changes when the piezoresistive material receives external pressure, so that the pressure is detected, the capacitive pressure sensor consists of a capacitor formed by a strain film, and the pressure changes the capacitance value of the capacitor, so that the pressure is detected. The piezoresistive pressure sensor has the advantage of high linearity compared with the capacitive pressure sensor, but has the biggest disadvantage of temperature drift phenomenon because the piezoresistor of the piezoresistive pressure sensor is made of silicon doped, and the resistance value of the piezoresistor is extremely easy to be influenced by temperature. The capacitive pressure sensor has the advantages of low power consumption, high sensitivity, excellent temperature characteristic and the like, has great advantages when working in a wide temperature range, and is lower in linearity than the piezoresistive pressure sensor because the pressure strain film serving as the capacitive plate is not parallel to the other capacitive plate when being deformed under pressure.
Accordingly, there is a need to provide a capacitive pressure sensor with good linearity.
Disclosure of Invention
Based on this, it is necessary to provide a MEMS capacitive pressure sensor capable of improving linearity of the capacitive pressure sensor and a method of manufacturing the same, in order to solve the problem of poor linearity of the capacitive pressure sensor.
In a first aspect, the present application provides a MEMS capacitive pressure sensor comprising:
the pressure sensor comprises a cavity area and an edge area surrounding the cavity area along the direction of the plane of the conductive substrate;
The first electrode layer is formed on one side surface of the conductive substrate and is positioned in the cavity area, and the first electrode layer comprises a plurality of annular first electrodes which are arranged in an insulating manner;
A pressure strain diaphragm located at one side of the first electrode layer away from the conductive substrate;
The second electrode layer is formed on one side of the pressure strain membrane, which faces the first electrode layer, and is positioned in the cavity area;
An insulating layer formed between the conductive substrate and the pressure strain membrane and located in the edge region;
The first electrodes and the second electrodes are alternately and alternately arranged at intervals along the direction that the central point of the plane of the conductive substrate points to the edge area.
In one embodiment, the cavity region includes a first cavity region and a second cavity region surrounding the first cavity region;
the first electrode and the second electrode are both located in the second cavity region.
In one embodiment, the semiconductor device further comprises a first metal pad and a second metal pad positioned in the edge area;
the first metal pad is formed on one side of the pressure strain diaphragm, which is far away from the conductive substrate, the second metal pad is formed on one side of the insulating layer, which is far away from the conductive substrate, and the second metal pad is electrically connected with the conductive substrate through the insulating layer.
In one embodiment, the first metal pad and the second metal pad are respectively arranged at two sides of the cavity area along the direction that the cavity area points to the edge area.
In one embodiment, the sum of the dimensions of the first electrode layer and the second electrode layer in a direction in which the conductive substrate points toward the pressure-strained diaphragm is less than or equal to the dimension between the conductive substrate and the pressure-strained diaphragm.
In one embodiment, the dimensions of the first electrodes are the same and the dimensions of the second electrodes are the same along the direction of the conductive substrate toward the pressure-strained diaphragm.
In one embodiment, the preparation material of at least one of the conductive substrate and the pressure strained diaphragm comprises low resistance silicon.
In one embodiment, the preparation material of at least one of the first electrode and the second electrode comprises at least one of gold and aluminum.
In a second aspect, the present application provides a method for manufacturing a MEMS capacitive pressure sensor, comprising:
the pressure sensor comprises a cavity area and an edge area surrounding the cavity area along the direction of the plane of the conductive substrate;
Depositing an insulating layer on one side surface of the conductive substrate;
etching a part of the insulating layer in the cavity area to form a plurality of annular first grooves which are arranged in an insulating manner;
preparing a first electrode in the first groove to form a first electrode layer;
Etching another part of the insulating layer of the cavity area;
depositing an insulating layer on the surface of one side of the conductive substrate facing the first electrode layer;
Etching a part of the insulating layer in the cavity area to form a plurality of annular second grooves which are arranged in an insulating way, wherein the first grooves and the second grooves are alternately and alternately arranged at intervals along the direction that the central point in the plane of the conductive substrate points to the edge area;
preparing a second electrode in the second groove to form a second electrode layer;
preparing a pressure strain membrane on the surface of one side of the second electrode layer far away from the first electrode layer;
Etching part of the pressure strain membrane in the cavity area along the direction of the pressure strain membrane towards the conductive substrate to form an etching hole penetrating through the pressure strain membrane;
And etching the insulating layer of the cavity area based on the etching hole, and filling the etching hole.
In one embodiment, the method further comprises:
Etching part of the pressure strain membrane and the insulating layer in the edge area along the direction of the pressure strain membrane towards the conductive substrate to form a through hole penetrating the pressure strain membrane and the insulating layer;
Preparing a first metal bonding pad on the surface of one side of the pressure strain membrane far away from the conductive substrate, preparing a second metal bonding pad on the surface of one side of the insulating layer where the through holes are located far away from the conductive substrate, and electrically connecting the second metal bonding pad with the conductive substrate through the through holes where the insulating layer is located.
The MEMS capacitive pressure sensor comprises a conductive substrate, a first electrode layer, a pressure strain membrane, a second electrode layer, an insulating layer, a first electrode and a second electrode, wherein the conductive substrate is arranged in the direction of a plane of the conductive substrate, the pressure sensor comprises a cavity area and an edge area surrounding the cavity area, the first electrode layer is formed on one side surface of the conductive substrate and is positioned in the cavity area, the first electrode layer comprises a plurality of annular first electrodes which are arranged in an insulating mode, the pressure strain membrane is positioned on one side of the first electrode layer away from the conductive substrate, the second electrode layer is formed on one side of the pressure strain membrane, which faces the first electrode layer, and is positioned in the cavity area, the second electrode layer comprises a plurality of annular second electrodes which are arranged in an insulating mode, the insulating layer is formed between the conductive substrate and the pressure strain membrane and is positioned in the edge area, the central point in the plane of the conductive substrate is directed towards the edge area, and the first electrodes are alternately arranged at intervals, and the pressure sensor is arranged in the direction of the plane of the conductive substrate in a plurality of annular first electrodes and the annular second electrodes, and the pressure sensor is arranged in the insulating layer alternately, and the pressure sensor is beneficial to increasing capacitance based on the capacitance of the conductive substrate and the first electrode and the second electrode, and the pressure sensor is beneficial to increasing the capacitance and the capacitance sensor.
Drawings
FIG. 1 is a top view of a MEMS capacitive pressure sensor provided in an embodiment of the application;
FIG. 2 is a cross-sectional view of AA' of FIG. 1 according to one embodiment of the present application;
FIG. 3 is a partial perspective view of a MEMS capacitive pressure sensor according to an embodiment of the present application;
FIG. 4 is a flow chart of a method for fabricating the first electrode layer of FIG. 1 according to an embodiment of the present application;
FIG. 5 is a flow chart of a method for fabricating the second electrode layer and the pressure strain gage of FIG. 1 according to an embodiment of the application;
FIG. 6 is a flow chart of one preparation of the sealed cavity of FIG. 1 according to an embodiment of the present application;
Fig. 7 is a flowchart of a preparation process of the first metal pad and the second metal pad in fig. 1 according to an embodiment of the present application.
Detailed Description
In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.
In the description of the present application, it should be understood that, if any, these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., are used herein with respect to the orientation or positional relationship shown in the drawings, these terms refer to the orientation or positional relationship for convenience of description and simplicity of description only, and do not indicate or imply that the apparatus or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.
Furthermore, the terms "first," "second," and the like, if any, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "plurality" and "a plurality" if any, mean at least two, such as two, three, etc., unless specifically defined otherwise.
In the present application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly. For example, they may be fixedly connected, detachably connected or integrally formed, mechanically connected, electrically connected, directly connected or indirectly connected through an intermediate medium, and communicated between two elements or the interaction relationship between two elements unless clearly defined otherwise. 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.
In the present application, unless expressly stated or limited otherwise, the meaning of a first feature being "on" or "off" a second feature, and the like, is that the first and second features are either in direct contact or in indirect contact through an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
It will be understood that if an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein, if any, are for descriptive purposes only and do not represent a unique embodiment.
Referring to fig. 1-3, a MEMS capacitive pressure sensor 100 according to an embodiment of the application includes:
The pressure sensor 100 comprises a cavity region 11 and an edge region 10 surrounding the cavity region 11 in the direction of the plane of the conductive substrate 1;
the first electrode layer 20 is formed on one side surface of the conductive substrate 1 and is positioned in the cavity area 11, wherein the first electrode layer 20 comprises a plurality of annular first electrodes 12 which are arranged in an insulating manner;
a pressure strain diaphragm 3 located on a side of the first electrode layer 20 remote from the conductive substrate 1;
the second electrode layer 30 is formed on one side of the pressure strain membrane 3 facing the first electrode layer 20 and is positioned in the cavity area 11, and the second electrode layer 30 comprises a plurality of annular second electrodes 31 which are arranged in an insulating manner;
an insulating layer 4 formed between the conductive substrate 1 and the pressure strain membrane 3 and located in the edge region 10;
The first electrodes 12 and the second electrodes 31 are alternately and alternately arranged at intervals in a direction in which the center point in the plane of the conductive substrate 1 is directed to the edge region 10.
Specifically, the MEMS capacitive pressure sensor 100 provided by the present application may include, in a direction perpendicular to the conductive substrate 1 included therein, that is, in a thickness direction thereof, the conductive substrate 1, the first electrode layer 20, the second electrode layer 30, and the pressure-strained diaphragm 3, which are stacked in this order, and an insulating layer 4 disposed between the conductive substrate 1 and the pressure-strained diaphragm 3.
The pressure sensor 100 includes a cavity region 11 and an edge region 10 surrounding the cavity region 11 along a plane of the conductive substrate 1, the conductive substrate 1 and the pressure strain membrane 3 of the mems capacitive pressure sensor 100 are disposed in the entire cavity region 11 and the entire edge region 10, the insulating layer 4 is disposed only in the edge region 10, and the first electrode 12 included in the first electrode layer 20 and the second electrode 31 included in the second electrode layer 30 are disposed only in the cavity region 11.
The present application provides an alternative arrangement of the first electrode layer 20 and the second electrode layer 30, in which the first electrode layer 20 includes a plurality of annular first electrodes 12, the second electrode layer 30 includes a plurality of annular second electrodes 31, the surrounding shapes of the first electrodes 12 and the second electrodes 31 may be the same, for example, rectangular or circular, and the surrounding shapes of the first electrodes 12 and the second electrodes 31 may be the same as the planar shape of the conductive substrate 1. Further, the arrangement of the orthographic projections of the first electrode 12 and the second electrode 31 on the plane of the conductive substrate 1 is such that the first electrode 12 and the second electrode 31 are alternately arranged at intervals in the direction of pointing the center point in the plane of the conductive substrate 1 to the edge region 10, that is, in the direction of pointing the plane of the conductive substrate 1, one annular first electrode 12, one annular second electrode 31 are arranged in this order from the center point of the cavity region 11 to the edge region 10, that is, in the direction of pointing the center point of the cavity region 11 to the edge region 10, the adjacently arranged first electrode 12 and second electrode 31 are insulated, and the adjacently arranged first electrode 12 and second electrode 31 have a gap space therebetween. The number of the first electrodes 12 included in the first electrode layer 20 is not particularly limited, and the number of the second electrodes 31 included in the second electrode layer 30 is not particularly limited, and for example, the number of the first electrodes 12 and the number of the second electrodes 31 may be selected to be the same according to the need.
In the MEMS capacitive pressure sensor 100 with the above structure, the conductive substrate 1 and the first electrode 12 correspond to a first polar plate forming a capacitor, the pressure strain membrane 3 and the second electrode 31 correspond to a second polar plate forming a capacitor, the conductive substrate 1 and the pressure strain membrane 3 are arranged in parallel, when a user applies pressure to the pressure strain membrane 3 in the MEMS capacitive pressure sensor 100, the pressure strain membrane 3 is deformed to approach to one side of the conductive substrate 1, and the capacitance between the two polar plates (the first polar plate and the second polar plate) can be increased due to the reduction of the gap between the conductive substrate 1 and the pressure strain membrane 3.
In the MEMS capacitive pressure sensor 100 with the above structure provided by the present application, the conductive substrate 1, the pressure strain membrane 3 and the insulating layer 4 form a sealed cavity around the cavity region 11. The sealing cavity can be optionally provided with air, can be set to be vacuum according to the requirement, can be filled with other gases according to the requirement, or can be filled with elastic materials according to the requirement, and the substances contained in the sealing cavity are not particularly limited in the application.
The MEMS capacitive pressure sensor 100 provided by the application comprises a conductive substrate 1; the pressure sensor 100 comprises a cavity region 11 and an edge region 10 surrounding the cavity region 11 in the direction of the plane of the conductive substrate 1; a first electrode layer 20 formed on one side surface of the conductive substrate 1 and located in the cavity region 11; the application is advantageous in increasing the effective area between a capacitance plate formed by the conductive substrate 1 and the first electrode 12 and a capacitance plate formed by the pressure strain 3 and the second electrode 31, in favor of increasing the overall sensitivity of the pressure sensor 100, and in favor of increasing the capacitance of the pressure sensor 100 and in favor of increasing the capacitance of the first electrode 12 and the second electrode 31 and in favor of increasing the capacitance plate formed by the pressure strain 3 and the second electrode 31 by alternately arranging the plurality of annular first electrodes 12 and the plurality of annular second electrodes 31 in the direction of the plane of the conductive substrate 1, as well as in favor of increasing the linear sensitivity of the pressure sensor 100 by alternately arranging the plurality of annular first electrodes 12 and the plurality of annular second electrodes 31 in the direction of the plane of the conductive substrate 1 and in favor of increasing the capacitance plate formed by the pressure strain 3 and the second electrode 31, in favor of increasing the linear sensitivity of the pressure sensor 100 by alternately arranging the plurality of annular first electrodes 12 and the plurality of annular second electrodes 31 in the direction of the plane of the conductive substrate 1 and the second electrode 31, and the pressure detection accuracy of the capacitive sensor is improved.
With continued reference to fig. 1-3, in some embodiments, the cavity region 11 includes a first cavity region 181 and a second cavity region 182 surrounding the first cavity region 181, and the first electrode 12 and the second electrode 31 are both located in the second cavity region 182.
Specifically, the cavity region 11 may include a first cavity region 181 and a second cavity region 182 along a plane of the conductive substrate 1, wherein the second cavity region 182 surrounds the first cavity region 181, and an alternative embodiment is provided according to the present application, in which both the first electrode 12 and the second electrode 31 are disposed in the second cavity region 182, i.e. neither the first electrode 12 nor the second electrode 31 is disposed in the first cavity region 181.
The first cavity area 181 is equivalent to the central area of the MEMS capacitive pressure sensor 100, and the present application does not provide an electrode in the central area of the pressure sensor 100, but alternatively provides annular protruding electrodes, that is, the annular first electrode 12 and the annular second electrode 31, at a position (the second cavity area 182) far away from the central area of the pressure sensor 100. The height direction of the sealed cavity, i.e. the direction perpendicular to the plane of the conductive substrate 1, i.e. the direction in which the conductive substrate 1 points towards the pressure strain gage 3.
With continued reference to fig. 1-3, in some embodiments, the device further includes a first metal pad 51 and a second metal pad 52 located in the edge region 10, wherein the first metal pad 51 is formed on a side of the pressure strain membrane 3 away from the conductive substrate 1, the second metal pad 52 is formed on a side of the insulating layer 4 away from the conductive substrate 1, and the second metal pad 52 is electrically connected to the conductive substrate 1 through the insulating layer 4.
Specifically, the MEMS capacitive pressure sensor 100 provided by the present application further includes a metal pad 5, specifically including a first metal pad 51 disposed on a side surface of the pressure strain membrane 3 away from the conductive substrate 1, and a second metal pad 52 disposed on a side surface of the insulating layer 4 away from the conductive substrate 1, where the area where the second metal pad 52 is located is not provided with the pressure strain membrane 3, so that at least a side surface of the second metal pad 52 away from the conductive substrate 1 can be exposed, and further, the second metal pad 52 is electrically connected with the conductive substrate 1 through a through hole 2 in the insulating layer 4.
Based on this structure, the capacitance between the first electrode plate and the second electrode plate is made variable, and can be led out via the pads (the first metal pad 51 and the second metal pad 52). When a user applies pressure to the pressure strain diaphragm 3 in the MEMS capacitive pressure sensor 100, the pressure strain diaphragm 3 is deformed to approach to one side of the conductive substrate 1, the gap between the conductive substrate 1 and the pressure strain diaphragm 3 is reduced, the capacitance between the two polar plates (the first polar plate and the second polar plate) is increased, a capacitance change signal is led out from the bonding pad, so that the capacitance change is detected by utilizing the micro capacitance detection circuit, relevant pressure data is obtained through processing, and the MEMS capacitive pressure sensor 100 senses the received pressure.
With continued reference to fig. 1-3, in some embodiments, the first metal pad 51 and the second metal pad 52 are disposed on two sides of the cavity region 11 along the direction of the cavity region 11 toward the edge region 10. The arrangement is beneficial to improving the extraction precision of the change signal of the capacitance sensed by the capacitive pressure sensor 100.
With continued reference to fig. 1-3, in some embodiments, the sum of the dimensions of the first electrode layer 20 and the dimensions of the second electrode layer 30 along the direction of the conductive substrate 1 toward the pressure-strained diaphragm 3 is less than or equal to the dimension between the conductive substrate 1 and the pressure-strained diaphragm 3.
Specifically, the sum of the dimensions of the first electrode layer 20 and the dimensions of the second electrode layer 30 can be selected to be smaller than the dimension of the gap between the conductive substrate 1 and the pressure strain membrane 3, or the sum of the dimensions of the first electrode layer 20 and the dimensions of the second electrode layer 30 can be selected to be exactly equal to the dimension of the gap between the conductive substrate 1 and the pressure strain membrane 3, i.e. the sum of the heights of the first electrode layer 20 and the second electrode layer 30 in the present application is not greater than the height of the sealed cavity, along the thickness direction of the MEMS capacitive pressure sensor 100, i.e. along the direction of the conductive substrate 1 toward the pressure strain membrane 3.
Because the height of the electrode bulge (the first electrode 12 and the second electrode 31) is too high, the deformation amount of the pressure strain diaphragm 3 can be influenced, so that the measuring range of the pressure sensor 100 is reduced, and moreover, if the electrode bulge is too low, the effect of increasing the sensitivity cannot be achieved.
With continued reference to fig. 1-3, in some embodiments, the dimensions of the first electrodes 12 are the same and the dimensions of the second electrodes 31 are the same in a direction along the conductive substrate 1 toward the pressure-strained diaphragm 3.
Specifically, the dimensions of each first electrode 12 and the dimensions of each second electrode 31 may be selected to be the same along the thickness direction of the capacitive pressure sensor 100, and the dimensions of each first electrode 12 and each second electrode 31 may be further selected to be the same along the thickness direction of the capacitive pressure sensor 100. In this way, the difficulty in preparing the first electrode layer 20 and the second electrode layer 30 is advantageously reduced.
In some embodiments, the preparation material of at least one of the conductive substrate 1 and the pressure strained diaphragm 3 comprises low resistance silicon. Specifically, the conductive substrate 1 can be prepared by using low-resistance silicon, and the pressure strain membrane 3 can be prepared by using low-resistance silicon, and compared with the traditional silicon wafer, the low-resistance silicon wafer has lower resistivity, higher electron migration speed and better conductive performance, so that the conductive substrate 1 and the pressure strain membrane 3 prepared by using low-resistance silicon also have good conductive performance.
The use of low resistance silicon to produce the conductive substrate 1 and the pressure strain gage 3 is only an alternative embodiment of the application, and other materials with good conductivity properties can be used to produce the conductive substrate 1 and the pressure strain gage 3, if desired.
In some embodiments, the preparation material of at least one of the first electrode 12 and the second electrode 31 comprises at least one of gold and aluminum. Specifically, the first electrode 12 may be selectively made of metal gold or metal aluminum, the second electrode 31 may be selectively made of metal gold or metal aluminum, and further, the first electrode 12 and the second electrode 31 may be selectively made of other metal materials having good electric conductivity. I.e. the one in the form of a ring. The electrode material is not limited to aluminum or gold, but may be some other metal material or alloy material having good conductivity. The first electrode 12 and the second electrode 31 may alternatively be prepared using the same material.
In addition, the present application also provides an alternative embodiment, in which the first electrode 12 and the second electrode 31 may be made of low-resistance silicon.
Based on this, for the MEMS capacitive pressure sensor 100 provided by the present application, an alternative structure is provided, which includes a fixed lower plate, a metal lead-out structure and a pressure strain membrane 3 assembly, wherein the fixed lower plate includes a low-resistance silicon substrate (conductive substrate 1), a dielectric insulating layer 4, a low-resistance silicon open cavity region (sealed cavity 11) and a homogeneous silicon material annular bump (first electrode 12), the low-resistance silicon substrate and the homogeneous silicon material annular bump form a capacitive first plate, the metal lead-out structure includes a through hole 2, a metal pad 5 (first metal pad 51 and second metal pad 52), wherein the "through hole" is formed in the insulating layer 4 on a side of the second metal pad 52 facing the low-resistance silicon substrate, and may be filled with a conductive material, and the pressure strain membrane 3 assembly includes a silicon material (e.g., low-resistance silicon) elastic strain membrane (pressure strain membrane 3) and an annular bump (second electrode 31), both of which form a capacitive second plate. The low-resistance silicon substrate and the annular protrusions (the first electrode 12 and the second electrode 31) on the pressure strain membrane 3 are arranged in a staggered mode, orthographic projections of the annular protrusion structures (the first electrode 12 and the second electrode 31) on the plane where the low-resistance silicon substrate is located are not overlapped, and staggered pattern gaps of the orthographic projections are larger than zero. The thickness of the staggered annular projection structure in the thickness direction is about half the height of the cavity (seal cavity).
According to the MEMS capacitive pressure sensor 100 provided by the application, the pressure strain diaphragm 3 works in a small deflection range, and when the pressure strain diaphragm 3 works, the pressure strain diaphragm 3 is linearly close to the low-resistance silicon substrate, so that capacitance change between polar plates is caused, pressure measurement is realized, and annular protrusions which are staggered away from the center of a device increase the effective area between the capacitive polar plates under the condition of not increasing the height of a capacitive cavity, so that the overall sensitivity of the device is improved.
Therefore, the pressure strain membrane 3 and the annular bulge structure on the low-resistance silicon substrate are arranged in a staggered manner, and the cavity height is not negatively influenced under the condition that the distance between the capacitor electrode plates is locally reduced. The annular protrusions staggered up and down are matched with each other, so that the effective area between the first polar plate and the second polar plate of the capacitor can be increased, and the sensitivity of the device is improved. The process of the application is simple and easy to realize, and the electrode material is not limited to aluminum or gold, but can be some other metal material or alloy material.
Referring to fig. 4 to fig. 7 in conjunction with fig. 1 to fig. 3, based on the same inventive concept, the present application further provides a method for manufacturing a MEMS capacitive pressure sensor 100, comprising steps 101 to 111, wherein:
step 101, providing a conductive substrate 1, wherein the pressure sensor 100 comprises a cavity area 11 and an edge area 10 surrounding the cavity area 11 along the direction of the plane of the conductive substrate 1;
Step 102, depositing an insulating layer 4 on one side surface of a conductive substrate 1;
step 103, etching a part of the insulating layer 4 of the cavity area 11 to form a plurality of annular first grooves which are arranged in an insulating manner;
step 104, preparing the first electrode 12 in the first groove to form a first electrode layer 20;
Step 105, etching another part of the insulating layer 4 of the cavity region 11;
step 106, depositing an insulating layer 4 on the surface of the side of the conductive substrate 1 facing the first electrode layer 20;
Step 107, etching a part of the insulating layer 4 of the cavity region 11 to form a plurality of annular second grooves which are arranged in an insulating way, wherein the first grooves and the second grooves are alternately and alternately arranged at intervals along the direction that the central point of the plane of the conductive substrate 1 points to the edge region 10;
step 108, preparing the second electrode 31 in the second groove to form a second electrode layer 30;
step 109, preparing a pressure strain membrane 3 on the surface of one side of the second electrode layer 30 away from the first electrode layer 20;
step 110, etching part of the pressure strain membrane 3 in the cavity region 11 along the direction of the pressure strain membrane 3 towards the conductive substrate 1 to form an etching hole 32 penetrating the pressure strain membrane 3;
Step 111, etching the insulating layer 4 of the cavity region 11 based on the etching hole, and filling the etching hole 32.
Further, the method for manufacturing the MEMS capacitive pressure sensor 100 further comprises a step 112 and a step 113 performed after the step 111, wherein:
step 112, etching part of the pressure strain membrane 3 in the edge region 10 and the insulating layer 4 along the direction of the pressure strain membrane 3 towards the conductive substrate 1 to form a through hole 49 penetrating the pressure strain membrane 3 and the insulating layer 4;
In step 113, a first metal pad 51 is prepared on a surface of the pressure strain membrane 3, which is far away from the conductive substrate 1, and a second metal pad 52 is prepared on a surface of the insulating layer 4, which is far away from the conductive substrate 1, where the through hole is located, and the second metal pad 52 is electrically connected with the conductive substrate 1 through the through hole 49, which is located by the insulating layer 4.
Wherein prior to step 113, a step of filling the portion of the via 2 corresponding to the insulating layer 4 in the through hole 49 with a conductive material may be further included.
Based on this, an alternative embodiment of a method (process flow) for manufacturing the MEMS capacitive pressure sensor 100 is provided, which includes steps 201 to 204, wherein:
Step 201, firstly, preparing a low-resistance silicon wafer (conductive substrate 1), vapor depositing a dielectric insulating layer 4 such as SiO 2 (silicon dioxide), using the insulating layer 4 as a sacrificial layer, etching the insulating layer 4, further growing annular protrusions (first electrodes 12) on the low-resistance silicon substrate, and etching the insulating layer 4 to form a cavity structure, as shown in fig. 4, completing the required process of the substrate, and completing the preparation of the first electrode plate of the capacitor.
Step 202, further, continuing to deposit a dielectric insulating layer 4 on the substrate, performing photolithography once after the insulating layer 4 reaches a certain thickness, opening the annular groove, and further depositing a layer of low-resistance silicon material to prepare the bump structure (the second electrode 31) on the pressure strain membrane 3, as shown in fig. 5, where the step completes the process required for the pressure strain membrane 3, and completes the preparation of the second electrode plate of the capacitor.
Step 203, further, etching the pressure strain membrane 3 prepared in the step 202, and opening the etching hole 32 on the membrane, and further etching the sacrificial layer to release the capacitor cavity. After the cavity is released, the cavity is dried, and then the etching hole 32 is filled by a deposition process, the process is shown in fig. 6, and the cavity is released under the pressure strain film.
Step 204, further, as shown in fig. 7, etching one side of the pressure strain membrane 3, windowing the top layer material, further etching the dielectric insulating material (to form a through hole 49), depositing a layer of conductive material into the etching channel (through hole 2) after etching is completed to lead out the electrode, and finally forming the bonding pad 5 by metal sputtering and removing the redundant metal layer. The step is to complete the process required by the electrode of the capacitor plate, and complete the preparation of the electrode.
In the structure of the application, the annular bulges of the substrate and the pressure strain diaphragms 3 are arranged in a staggered manner, namely the first electrode 12 and the second electrode 31, so that the effective area between the two capacitance plates is increased, meanwhile, the projection of the annular bulges on the plane where the conductive substrate 1 is positioned is not overlapped, the projection clearance is larger than 0, and the thickness of the annular bulge structure is about one half of the capacitance clearance (the height of the sealed cavity), and the like, so that the pressure strain diaphragms 3 can not collide when being close to the substrate (the conductive substrate 1), namely the first electrode 12 and the second electrode 31 can not collide, and therefore, the height of the capacitance clearance is not required to be additionally increased under the condition of increasing the sensitivity of the MEMS capacitive pressure sensor 100.
When pressure is applied to the pressure strain diaphragm 3, the diaphragm generates a shape to approach to the substrate, the capacitance between the two polar plates is increased due to the reduction of the gap, a capacitance change signal can be led out from a bonding pad, and a tiny capacitance detection circuit is used for detecting the capacitance change, so that pressure data can be obtained through processing.
The capacitive effect is utilized by the application, the microminiaturization characteristic of a micro-electro-mechanical system (MEMS) is combined with the low temperature drift and low power consumption of the capacitive pressure sensor 100, and the capacitive pressure sensor has the characteristics of high sensitivity, low temperature drift, wide temperature region operation, low power consumption, strong portability and the like.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
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