CN114235233A - MEMS pressure sensor and preparation method thereof - Google Patents
MEMS pressure sensor and preparation method thereof Download PDFInfo
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- CN114235233A CN114235233A CN202111541027.8A CN202111541027A CN114235233A CN 114235233 A CN114235233 A CN 114235233A CN 202111541027 A CN202111541027 A CN 202111541027A CN 114235233 A CN114235233 A CN 114235233A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 59
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 59
- 239000010703 silicon Substances 0.000 claims abstract description 59
- 229910052751 metal Inorganic materials 0.000 claims abstract description 33
- 239000002184 metal Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 15
- 238000003466 welding Methods 0.000 claims abstract description 12
- 238000002161 passivation Methods 0.000 claims abstract description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 5
- 239000001301 oxygen Substances 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 238000001259 photo etching Methods 0.000 claims description 12
- 238000000059 patterning Methods 0.000 claims description 10
- 238000001312 dry etching Methods 0.000 claims description 9
- 238000005530 etching Methods 0.000 claims description 8
- 238000004518 low pressure chemical vapour deposition Methods 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 6
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 238000000151 deposition Methods 0.000 claims description 5
- 238000005516 engineering process Methods 0.000 claims description 5
- 238000001020 plasma etching Methods 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims description 5
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 5
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 5
- 238000005468 ion implantation Methods 0.000 claims description 3
- 229920002120 photoresistant polymer Polymers 0.000 claims description 3
- 238000004528 spin coating Methods 0.000 claims description 3
- 239000012212 insulator Substances 0.000 claims description 2
- 238000004544 sputter deposition Methods 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 16
- 230000000694 effects Effects 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000000788 chromium alloy Substances 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Images
Classifications
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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
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
-
- 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
- G01L9/02—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 ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
- G01L9/06—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 ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses an MEMS pressure sensor and a preparation method thereof, and the MEMS pressure sensor mainly comprises a bulk silicon layer, an oxygen burying layer, a top silicon layer, a piezoresistor, a heavy doping area, an insulating medium layer, a pressure welding block and a passivation layer; a large cavity is arranged at the center of the top silicon layer, and small cavities are arranged above the centers of four sides of the large cavity; the top silicon layer and the insulating medium layer above the large cavity form a pressure sensitive film; the upper surface of the pressure sensitive film is provided with a cross beam structure, four end parts of the cross beam structure are provided with piezoresistors, a heavily doped region and a metal lead, and each group of piezoresistors and the metal lead form a Wheatstone bridge through the heavily doped region; the cross beam structure inhibits the deformation of the pressure sensitive film, so that the linearity is improved; the small cavity structure improves the stress concentration of the piezoresistor area, so that the sensor keeps miniaturization and improves the sensitivity; in addition, the preparation method of the sensor is compatible with CMOS and MEMS processes, and cost is saved.
Description
Technical Field
The invention provides an MEMS pressure sensor and a preparation method thereof, belonging to the technical field of micro-electro-mechanical systems (MEMS).
Background
MEMS (Micro-Electro-Mechanical System) pressure sensors have wide application in the fields of automotive electronics, medical electronics, aerospace and the like due to the advantages of miniaturization, high sensitivity, easy integration and the like. Among them, the MEMS piezoresistive pressure sensor is an important branch of the MEMS pressure sensor, and its performance is particularly prominent in the above application fields.
Piezoresistive pressure sensors are made based on the piezoresistive effect. When the strain film of the sensor is subjected to external pressure, deformation can occur, and the deformation can be transmitted to the piezoresistor on the strain film; due to the piezoresistive effect, the resistance value of the piezoresistor can be changed, so that the output voltage is changed; the measurement of the external pressure is performed by measuring the change in the output voltage. The MEMS piezoresistive pressure sensor is manufactured by utilizing a semiconductor processing technology and an MEMS body etching technology and mainly comprises a piezoresistive resistor, a pressure sensitive film and a substrate with a cavity.
Sensitivity and linearity are the main performance indicators for MEMS piezoresistive pressure sensors. In measurement, in order to pursue high sensitivity, a thin strained film structure is generally designed. However, such a strained membrane structure results in a large membrane deflection, which results in a reduced linearity of the pressure sensor. The literature states that good linearity and higher sensitivity can be achieved by designing the island film structure, but in order to increase its sensitivity, it is generally necessary to increase the size of the strained film, which results in an overall larger size of the device. Therefore, based on the above problems, the present invention provides a high-sensitivity MEMS pressure sensor and a method for manufacturing the same, in order to achieve compatibility between high sensitivity and high linearity, and achieve miniaturization.
Disclosure of Invention
The technical problem is as follows: based on the above problems, the present invention aims to provide an MEMS pressure sensor and a method for manufacturing the same, in which a cross beam structure is disposed at the center of a pressure sensitive film, so as to suppress deformation of the pressure sensitive film, thereby improving linearity of the pressure sensor; by adopting the structure that the small cavity is arranged below the piezoresistor, the sensitivity of the MEMS pressure sensor is improved while the size of the device is not increased. Therefore, the MEMS pressure sensor has high sensitivity and good linearity while meeting the miniaturization characteristic.
The MEMS pressure sensor mainly comprises a bulk silicon layer, an oxygen burying layer, a top silicon layer, a piezoresistor, a heavy doping area, an insulating medium layer, a metal lead, a pressure welding block and a passivation layer.
The top silicon layer is internally provided with two cavities with different functions; one of the two cavities is a large cavity and is positioned in the center of the top silicon layer, and the function of the cavity is to form a pressure sensitive film; the second cavity is a small cavity and is positioned above the center of four sides of the large cavity, and the second cavity has the function of improving the stress concentration near the piezoresistor, so that the sensitivity of the sensor is improved; one large cavity and four small cavities, and the length and width of each small cavity are slightly larger than the piezoresistor, so that the small cavities can contain the piezoresistor;
the pressure sensitive film is composed of a top silicon layer and an insulating medium layer above the large cavity; the center of the pressure sensitive film is provided with a cross beam structure, and the cross beam structure is used for inhibiting the deformation of the pressure sensitive film, so that the linearity of the sensor is improved; the four tail ends of the cross beam structure are respectively provided with a piezoresistor, a heavily doped region and a metal lead, wherein the piezoresistor is connected with the heavily doped region in series, and the other end of the heavily doped region is connected with the metal lead; the heavily doped region forms ohmic contact with the piezoresistor and the metal lead;
four groups of piezoresistors positioned on the pressure sensitive film are connected with the metal lead wire through the heavily doped region to form a Wheatstone bridge, and a small cavity is arranged below each group of piezoresistors; the four pressure welding blocks are connected with the piezoresistors through metal leads, and each pressure welding block is positioned between two piezoresistors;
the insulating medium layer covers the top silicon layer, and a contact hole is reserved above the heavily doped region, so that a metal lead can be conveniently led out subsequently; the passivation layer covers the upper surface area except the bonding pads of the pressure sensor and is used for protecting devices.
Further, the material of the insulating dielectric layer may be silicon dioxide, low-stress silicon nitride, or an organic insulating material.
Furthermore, the material of the metal lead may be aluminum or chromium alloy, and chromium/gold may be preferably used as the metal material to prevent oxygen generated by anodic bonding from oxidizing the metal lead.
Further, each said set of piezoresistors may comprise a plurality of piezoresistors.
The preparation method of the MEMS pressure sensor comprises the following steps:
step 1: preparing an N-type SOI (silicon on insulator) sheet, and etching the top silicon layer by adopting an anisotropic dry etching method to form a silicon groove;
step 2: keeping the silicon grooves at the center positions of the four sides of the top silicon layer by using a mask, and then continuously carrying out anisotropic dry etching on the rest silicon grooves to etch the silicon grooves to an oxygen buried layer;
and step 3: carrying out isotropic dry etching on the top silicon layer to form a large cavity and a small cavity;
and 4, step 4: sealing the large cavity and the small cavity by adopting an epitaxial cavity sealing process;
and 5: photoetching and ion implantation are sequentially carried out on the top silicon layer to respectively form a piezoresistor and a heavily doped region;
step 6: depositing a silicon oxide layer and a silicon nitride layer on the surface of the top silicon layer by an LPCVD (low pressure chemical vapor deposition) technology to be used as insulating medium layers; photoetching and patterning the insulating medium layer, and forming a contact hole above the heavily doped region;
and 7: sputtering a metal layer, and photoetching and patterning to form a metal lead and a pressure welding block;
and 8: spin-coating photoresist in the region of the cross beam structure, performing photoetching and patterning, performing RIE (reactive ion etching) in the peripheral window region of the cross beam structure on the pressure sensitive film, and etching peripheral windows of the cross beam structure to form the cross beam structure;
and step 9: and depositing a passivation layer by an LPCVD (low pressure chemical vapor deposition) technology, and then carrying out photoetching and patterning to expose the metal bonding pad so as to finish the preparation of the MEMS pressure sensor.
Has the advantages that: compared with the prior art, the invention has the following advantages:
(1) on the basis of improving the sensitivity, the MEMS pressure sensor abandons the traditional method for thinning the thickness of the strain film, and improves the stress concentration near the piezoresistor by adopting a method of adding a small cavity below the piezoresistor, thereby improving the sensitivity of the sensor and reducing the adverse effect of the sensor on the linearity.
(2) The cross beam structure is arranged on the upper surface of the pressure sensitive film and is positioned in the center, so that the deformation of the strain film is restrained, and the linearity of the sensor is improved.
(3) In addition, the small cavity structure arranged below the piezoresistor of the MEMS pressure sensor enables the sensitivity of the sensor to be improved under the condition that the size of a device is not increased, and the MEMS pressure sensor has the characteristic of miniaturization; meanwhile, the preparation method is compatible with CMOS and MEMS processes, and has the characteristic of low cost.
Drawings
FIG. 1 is a schematic top view of a MEMS pressure sensor according to the present invention;
FIG. 2 is a cross-sectional view of a MEMS pressure sensor of the present invention taken along the line A-A' in FIG. 1;
FIG. 3 is a schematic view of the structure A-A' corresponding to step 1 of manufacturing the MEMS pressure sensor according to the present invention;
FIG. 4 is a schematic view of the structure A-A' corresponding to step 2 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 5 is a schematic view of the structure A-A' corresponding to step 3 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 6 is a schematic view of the structure A-A' corresponding to step 4 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 7 is a schematic view of the structure A-A' in the direction corresponding to step 5 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 8 is a schematic view of the structure A-A' corresponding to step 6 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 9 is a schematic view of the structure A-A' corresponding to step 7 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 10 is a schematic view of a structure B-B' in the direction corresponding to step 8 of manufacturing the MEMS pressure sensor of the present invention;
FIG. 11 is a schematic view of the structure A-A' in the direction corresponding to step 9 of manufacturing the MEMS pressure sensor of the present invention;
in the figure, 1-the piezoresistor; 2-a heavily doped region; 3-a bulk silicon layer; 4-large cavity; 5-small cavity; 6-a silicon oxide layer; a 7-silicon nitride layer; 8-a metal lead; 9-buried oxide layer; 10-a top silicon layer; 11-a passivation layer; 12-a cross beam structure; 13-pressure welding block.
Detailed Description
The invention will be further explained with reference to the drawings.
As shown in fig. 1 and 2, the MEMS pressure sensor mainly has a structure including a bulk silicon layer 3, a buried oxide layer 9, a top silicon layer 10, a varistor 1, a heavily doped region 2, an insulating dielectric layer, a metal lead 8, a bonding pad 13, and a passivation layer 11.
The top silicon layer 10 has two cavities with different functions inside; one of them is a large cavity 5, located in the central position of the top silicon layer 10, whose function is to constitute a pressure-sensitive membrane; the second cavity is a small cavity 4 which is positioned above the center of four sides of the large cavity 5 and has the function of improving the stress concentration near the piezoresistor, thereby improving the sensitivity of the sensor; one large cavity 5 and four small cavities 4, and the length and width of each small cavity 4 are slightly larger than the piezoresistor 1, so that the small cavities 5 can contain the piezoresistor 1;
the pressure sensitive film is composed of a top silicon layer 10 and an insulating medium layer above the large cavity 5; the center of the pressure sensitive film is provided with a cross beam structure 12, and the cross beam structure 12 is used for inhibiting the deformation of the pressure sensitive film, so that the linearity of the sensor is improved; four tail ends of the cross beam structure 12 are respectively provided with a piezoresistor 1, a heavily doped region 2 and a metal lead 8, wherein the piezoresistor 1 is connected with the heavily doped region 2 in series, and the other end of the heavily doped region 2 is connected with the metal lead 8; the heavily doped region 2, the piezoresistor 1 and the metal lead 8 are in ohmic contact;
four groups of piezoresistors 1 positioned on the pressure sensitive film form a Wheatstone bridge through the connection of a heavily doped region 2 and a metal lead 8, and a small cavity 4 is arranged below each group of piezoresistors 1; the four pressure welding blocks 13 are connected with the piezoresistors 1 through metal leads 8, and each pressure welding block 13 is positioned between two piezoresistors 1;
the insulating medium layer covers the top silicon layer 10, and a contact hole is reserved above the heavily doped region 2, so that a metal lead 8 can be conveniently led out subsequently; the passivation layer 11 covers the upper surface area except for the bonding pads 13 of the pressure sensor for protecting the device.
A method for preparing the MEMS pressure sensor comprises the following steps:
step 1: an N-type (100) SOI wafer is prepared in which the buried oxide layer 9 has a thickness of 0.1-5 μm, the bulk silicon layer 3 has a thickness of 100-650 μm, and the top silicon layer 10 has a thickness of 5-30 μm, and then silicon trenches having a depth of about 2-20 μm are etched in the top silicon layer 10 by an anisotropic dry etching process, as shown in fig. 3.
Step 2: and (3) retaining the silicon grooves at the center positions of the four sides of the top silicon layer by using a mask, and then continuing to perform anisotropic dry etching on the remaining silicon grooves to etch the silicon grooves to the buried oxide layer 9, so that the etching depth of the silicon grooves can be accurately controlled, as shown in FIG. 4.
And step 3: the top silicon layer 10 is subjected to isotropic dry etching to form large cavities 4 and small cavities 5, as shown in fig. 5.
And 4, step 4: by using an epitaxial cavity sealing process, a single crystal silicon epitaxy is performed on the top silicon layer 10, and the silicon trench is completely sealed by using the epitaxial silicon material, thereby sealing the large cavity 4 and the small cavity 5, as shown in fig. 6.
And 5: the top silicon layer 10 is subsequently subjected to photolithography and ion implantation to form the varistor 1 and the heavily doped region 2, respectively, as shown in fig. 7.
Step 6: depositing a silicon oxide layer 6 with the thickness of 0.01-1 μm and a silicon nitride layer 7 with the thickness of 0.01-1 μm on the surface of the top silicon layer 10 to be used as insulating medium layers; and the insulating dielectric layer is subjected to photoetching and patterning, so that a contact hole is formed above the heavily doped region 2, as shown in fig. 8.
And 7: a metal layer of 0.1-1 μm thickness of chromium/gold is sputtered and patterned by photolithography to form metal leads 8 and bonding pads 13, as shown in fig. 9.
And 8: spin-coating photoresist in the region of the cross beam structure, performing photoetching and patterning, performing RIE etching in the peripheral window region of the cross beam structure on the pressure sensitive film, and etching to obtain the peripheral window of the cross beam structure with a depth of 5-10 μm, thereby forming the cross beam structure, as shown in FIG. 10.
And step 9: a passivation layer 11 is deposited by LPCVD techniques and is then lithographically patterned to expose the bonding pads 13.
The criteria for distinguishing whether this structure is present are as follows:
according to the MEMS pressure sensor, the cross beam structure is arranged in the right center of the pressure sensitive film; each end part of the cross beam structure is provided with a group of piezoresistors 1, a group of heavily doped regions 2 and a group of metal leads 8, and a small cavity 5 is arranged right below each group of piezoresistors 1 to improve the sensitivity of the device; the upper surface of the piezoresistor 1 is covered with an insulating medium layer for protection. The structure satisfying the above conditions is regarded as a MEMS pressure sensor with high sensitivity of the present invention.
Claims (4)
1. An MEMS pressure sensor is characterized by comprising a bulk silicon layer (3), a buried oxide layer (9), a top silicon layer (10), a piezoresistor (1), a heavily doped region (2), an insulating medium layer, a metal lead (8), a pressure welding block (13) and a passivation layer (11); the top silicon layer (10) is internally provided with two cavities; one of the two cavities is a large cavity (5) and is positioned at the center of the top silicon layer (10); the second cavity is a small cavity (4) and is positioned above the center of four sides of the large cavity (5); one large cavity (5) and four small cavities (4); the pressure sensitive film is composed of a top silicon layer (10) above the large cavity (5) and an insulating medium layer; a cross beam structure (12) is arranged at the center of the pressure sensitive film, four tail ends of the cross beam structure (12) are respectively provided with a piezoresistor (1), a heavily doped region (2) and a metal lead (8), wherein the piezoresistor (1) is connected with the heavily doped region (2) in series, and the other end of the heavily doped region (2) is connected with the metal lead (8); the heavily doped region (2) forms ohmic contact with the piezoresistor (1) and the metal lead (8); four groups of piezoresistors (1) positioned on the pressure sensitive film are connected with a metal lead (8) through a heavily doped region (2) to form a Wheatstone bridge, and a small cavity (4) is arranged below each group of piezoresistors (1); the four pressure welding blocks (13) are connected with the piezoresistors (1) through metal leads (8), and each pressure welding block (13) is positioned between the two piezoresistors (1); the insulating medium layer covers the top silicon layer (10), and a contact hole is reserved above the heavily doped region (2); the passivation layer (11) covers the upper surface area except the bonding pads (13) of the pressure sensor.
2. The MEMS pressure sensor according to claim 1, wherein the MEMS pressure sensor is provided with a total of 4 groups of the piezoresistors (1) on the upper surface of the top silicon layer (10), and four groups of the piezoresistors are respectively provided above the midpoint positions of four sides of the large cavity (4).
3. MEMS pressure sensor according to claim 1, characterized in that a small cavity (5) is provided below each group of piezoresistors (1), and that the length and width of each small cavity (4) is slightly larger than the piezoresistors (1), so that the small cavities (5) can envelop the piezoresistors (1).
4. A method of manufacturing a MEMS pressure sensor according to any of claims 1-3, comprising the steps of:
step 1: preparing an N-type SOI (silicon on insulator) sheet, and then etching the top silicon layer (10) by adopting an anisotropic dry etching method to form a silicon groove;
step 2: keeping the silicon grooves at the center positions of the four sides of the top silicon layer by using a mask, and then continuously carrying out anisotropic dry etching on the rest silicon grooves to etch the silicon grooves to an oxygen buried layer (9);
and step 3: carrying out isotropic dry etching on the top silicon layer (10) to form a large cavity (4) and a small cavity (5);
and 4, step 4: sealing the large cavity (4) and the small cavity (5) by adopting an epitaxial process;
and 5: photoetching and ion implantation are sequentially carried out on the top silicon layer (10) to respectively form a piezoresistor (1) and a heavily doped region (2);
step 6: depositing a silicon oxide layer (6) and a silicon nitride layer (7) on the surface of the top silicon layer (10) by an LPCVD technique, wherein the silicon oxide layer and the silicon nitride layer are used as insulating medium layers; photoetching and patterning the insulating medium layer, and forming a contact hole above the heavily doped region (2);
and 7: sputtering a metal layer, and photoetching and patterning to form a metal lead (8) and a pressure welding block (13);
and 8: spin-coating photoresist in the region of the cross beam structure, carrying out photoetching and patterning, carrying out RIE (reactive ion etching) in the peripheral window region of the cross beam structure on the pressure sensitive film, and etching the peripheral window of the cross beam structure to form the cross beam structure (12);
and step 9: and depositing a passivation layer (11) by an LPCVD (low pressure chemical vapor deposition) technology, and then carrying out photoetching and patterning to expose the bonding pads (13) so as to finish the preparation of the MEMS pressure sensor.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114705332A (en) * | 2022-05-06 | 2022-07-05 | 西安思微传感科技有限公司 | High-sensitivity low-nonlinearity pressure sensor and preparation method thereof |
| CN116026501A (en) * | 2023-01-06 | 2023-04-28 | 苏州锐光科技有限公司 | Pressure sensor and manufacturing method thereof |
| CN117007219A (en) * | 2023-06-13 | 2023-11-07 | 北京智芯传感科技有限公司 | Inverted force sensor array |
| CN117030078A (en) * | 2023-08-10 | 2023-11-10 | 无锡胜脉电子有限公司 | Silicon force sensitive chip and preparation method and packaging method thereof |
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