CN114314498A - MEMS film vacuum gauge and preparation method thereof - Google Patents
MEMS film vacuum gauge and preparation method thereof Download PDFInfo
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- CN114314498A CN114314498A CN202210244071.0A CN202210244071A CN114314498A CN 114314498 A CN114314498 A CN 114314498A CN 202210244071 A CN202210244071 A CN 202210244071A CN 114314498 A CN114314498 A CN 114314498A
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Abstract
The invention provides an MEMS film vacuum gauge and a preparation method thereof, comprising a first substrate, a second substrate and a third substrate which are superposed; the first closed cavity and the second closed cavity are closed between the first substrate and the third substrate at intervals; a first electrode corresponding to a region of the first substrate above the first sealed chamber; the sensitive film corresponds to the area of the first substrate, which is positioned above the second closed cavity; the first stop layer is arranged in a first closed cavity below the first electrode; the second stop layer is arranged in a second closed cavity below the sensitive film; the first stop layer and the second stop layer are formed by etching the second substrate. The MEMS capacitance type film vacuum gauge and the piezoresistive film vacuum gauge are integrated on the same wafer, the process is simple and convenient, and the measuring range of the MEMS film vacuum gauge is effectively improved on the premise of ensuring the sensitivity and the linearity of the two vacuum gauges.
Description
Technical Field
The invention relates to the field of MEMS, in particular to an MEMS (Micro-Electro-Mechanical System) film vacuum gauge and a preparation method thereof.
Background
The MEMS film vacuum gauge is a direct measurement vacuum gauge manufactured by utilizing the principle that an elastic film generates elastic deformation under the action of pressure difference, and can measure the pressure of the elastic film
Low vacuum pressure measurements are made in the Pa range. The transformation method between the deformation amount and the electric signal can be classified into an inductance type, a piezoelectric type, a piezoresistive type, a capacitance type, and the like. The MEMS piezoresistive film vacuum gauge utilizes the piezoresistive effect of semiconductor materials, and a Wheatstone bridge is formed by interconnection of piezoresistors on a sensitive film to convert the vacuum environment pressure into an electric signal, so that the measurement of low vacuum pressure is realized. The MEMS capacitive film vacuum gauge utilizes the deformation of a film under the action of pressure, so that the capacitance of a sensitive capacitor formed by the film and a fixed electrode is changed, and the capacitance change is read out through a peripheral circuit to measure the external low vacuum pressure. The MEMS capacitance and piezoresistive film vacuum gauge is widely applied to the field of vacuum measurement due to small volume, high precision, easy integration and no relation between measurement sensitivity and gas types, and has obvious effect.
The existing MEMS capacitive film vacuum gauge has small volume, and the vacuum gauge needs to use extremely small electrode spacing to ensure sensitivity and capacitance, so the upper limit value of measuring low vacuum pressure is limited. The existing MEMS piezoresistive film vacuum gauge mainly adopts a sensitive film structure, and piezoresistors are distributed on the surface of a film. In pursuit of performance requirements for high sensitivity at low vacuum pressures, the thickness of the sensitive film is designed to be thinner and thinner, and the linearity is designed to be worse and worse.
In view of the above problems, there is a need for a MEMS thin film vacuum gauge and a method for manufacturing the same, which are reasonably designed and can effectively solve the above problems.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to at least solve one technical problem in the prior art and provides an MEMS film vacuum gauge and a preparation method thereof.
Specifically, the technical scheme of the invention is as follows:
a MEMS thin film vacuum gauge comprising:
a first substrate, a second substrate, and a third substrate which are stacked;
the first closed cavity and the second closed cavity are closed between the first substrate and the third substrate at intervals;
a first electrode corresponding to a region of the first substrate above the first hermetically sealed cavity;
the sensitive film corresponds to the area of the first substrate above the second closed cavity;
the first stop layer is arranged in a first closed cavity below the first electrode;
the second stop layer is arranged in a second closed cavity below the sensitive film;
the first stop layer and the second stop layer are formed by etching the second substrate.
Optionally, the first substrate and the second substrate are a top silicon layer and a bulk silicon layer of the SOI substrate, respectively.
Optionally, the touch panel further comprises a first insulating layer disposed on the first stopper layer, wherein the first insulating layer is used for electrical insulation between the first electrode layer and the first stopper layer.
Optionally, the distance between the first stop layer and the first electrode and the distance between the second stop layer and the sensitive film are the sum of the thicknesses of the first insulating layer and the second insulating layer of the SOI substrate.
Optionally, the sensor further comprises a piezoresistor, wherein the piezoresistor is arranged on the sensitive film; and/or the piezoresistors form a Wheatstone bridge.
Optionally, the first electrode is formed by ion implantation into the first substrate.
Optionally, a third insulating film is further included, and the third insulating film is provided on the upper surface of the first substrate.
Optionally, the getter layer is arranged on the surface of the third substrate in the first closed cavity and the second closed cavity.
The invention also provides a preparation method of the MEMS film vacuum gauge, which comprises the following steps:
selecting a first substrate comprising opposing first and second surfaces;
preparing a second insulating layer on the second surface of the first substrate;
selecting a second substrate comprising opposing third and fourth surfaces;
preparing a first stop layer and a second stop layer which are arranged at intervals on a third surface of the second substrate, wherein the surface of the first stop layer further comprises a first insulating layer;
bonding the second surface of the first substrate with the second insulating layer and the third surface of the second substrate;
thinning the first surface of the first substrate, wherein the first substrate, the first insulating layer, the second insulating layer and the second substrate form an SOI structure;
etching areas, corresponding to the first stop layer and the second stop layer, of the fourth surface of the second substrate until the second insulating layer;
removing the first stop layer and the second insulating layer of the second stop layer region;
selecting the third substrate;
and bonding the third substrate and the fourth surface of the second substrate to form a first closed cavity and a second closed cavity.
Optionally, after removing the first stop layer and the second insulating layer of the second stop layer region, a step of preparing a piezoresistor on a first surface of the first substrate corresponding to the second stop layer is further included; and/or the piezoresistors form a Wheatstone bridge.
Optionally, the method further comprises the step of preparing a getter layer on the bonding surface of the third substrate.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. compared with the traditional MEMS film vacuum gauge, the MEMS film vacuum gauge provided by the invention integrates the MEMS capacitive film vacuum gauge and the piezoresistive film vacuum gauge on the same wafer by combining an SOI (silicon on insulator) silicon wafer with a back cavity etching process, is simple and convenient in process, and effectively improves the measuring range of the MEMS film vacuum gauge on the premise of ensuring the sensitivity of the two gauges.
2. According to the MEMS film vacuum gauge, the ultrathin first electrode layer 12 and the sensitive film 14 are prepared by utilizing the top silicon layer of the SOI structure, the deformation of the first electrode layer 12 and the sensitive film 14 is limited in a narrow cavity above the first stop layer 3 and the second stop layer 4 by etching the first stop layer 3 and the second stop layer 4 formed by the bulk silicon layer of the SOI structure, and the sensitivity and the linearity of the MEMS film vacuum gauge are improved.
3. The invention is prepared by adopting the MEMS technology, and the sensor has the advantages of small size, high precision, good consistency, easy batch manufacturing and low cost.
Drawings
FIG. 1 is a schematic top view of a MEMS thin film vacuum gauge in accordance with one embodiment of the present invention;
FIG. 2 is a schematic plan view of a stopper layer structure of a MEMS thin film vacuum gauge according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a Wheatstone bridge connection of piezoresistors of the MEMS thin film vacuum gauge according to one embodiment of the invention;
FIG. 4 is a cross-sectional view of the MEMS thin film gauge of FIG. 1 taken along the line A-A' in accordance with one embodiment of the present invention;
FIG. 5 is a schematic flow chart of a method for manufacturing a MEMS thin film vacuum gauge according to an embodiment of the present invention;
fig. 6-23 are schematic process diagrams of a manufacturing method of the MEMS thin film vacuum gauge according to an embodiment of the invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Example 1
The present embodiment provides a MEMS thin film vacuum gauge, as shown in fig. 1 to 4, including:
a first substrate 1, a second substrate 2, and a third substrate 15 which are stacked;
a first sealed cavity 17 and a second sealed cavity 18 sealed between the first substrate 1 and the third substrate 15 at intervals;
a first electrode 12, the first electrode 12 corresponding to a region of the first substrate located above the first closed cavity 17;
a sensitive film 14 corresponding to the area of the first substrate 1 above the second closed cavity 18;
the first stop layer 3 is arranged in a first closed cavity below the first electrode;
the second stop layer 4 is arranged in a second closed cavity below the sensitive film;
the first stop layer and the second stop layer are formed by etching the second substrate 2.
Specifically, the MEMS thin film vacuum gauge of the invention comprises a capacitance thin film vacuum gauge and a piezoresistive thin film vacuum gauge structure which are arranged in parallel.
The second substrate 2, the first stopper layer 3, the first insulating layer 5, the first ohmic contact layer 6, the second insulating layer 7, the lead layer 11, the first electrode layer 12 and the first sealed cavity 17 together form a capacitance type thin film vacuum gauge structure. The first electrode layer 12 is used as a thin film electrode, and the second substrate 2 and the first stopper layer 3 are used as fixed electrodes, which form a sensitive capacitor structure. Under low vacuum pressure, the film electrode is pressed and deformed, the distance between the film electrode and the fixed electrode is changed, and the capacitance is changed, so that the conversion from a pressure signal to an electric signal is realized.
The second substrate 2, the second stop layer 4, the piezoresistor 8, the second ohmic contact layer 9, the second electrode layer 13, the sensitive film 14 and the second closed cavity 18 together form a piezoresistive film vacuum gauge structure. Under low vacuum pressure, the sensitive film 14 is pressed and deformed, the resistance value of the piezoresistor 8 on the sensitive film is changed under the action of stress, and the resistance value is converted into a corresponding electric signal through the Wheatstone bridge to be output.
Further, the material of the first substrate 1 is monocrystalline silicon, and the thickness is 1-10
The first substrate 1 includes a first surface and a second surface, and in this embodiment, an upper surface is taken as the first surface, and a lower surface opposite to the first surface is taken as the second surface.
Further, a second insulating layer 7 is disposed on the second surface of the first substrate 1, and the material is, for example, silicon dioxide with a thickness of 200-1000 nm.
Further, the second substrate 2 is disposed on the lower surface of the second insulating layer 7, and the material is, for example, low-resistance silicon and has a thickness of, for example, 200-. The second substrate 2 includes a third surface and a fourth surface, in this embodiment, the upper surface shown in the figure is the third surface, and the lower surface opposite to the third surface is the fourth surface.
Further, the third substrate 15 is disposed on the fourth surface of the second substrate 2, and is made of glass, preferably a BF33 type glass sheet, and has a thickness of 200-.
Further, the first sealed cavity 17 and the second sealed cavity 18 are vacuum cavities respectively disposed on the upper surface of the third substrate 15, and the depths thereof are both 200-
。
Further, the getter device further comprises two getter layers 16 arranged on the upper surface of the third substrate 15 and respectively located in the first closed cavity 17 and the second closed cavity 18, wherein the thickness of the getter layers is 50-200nm, the getter layers are made of non-evaporable getters, and the getter layer is used for solving the problem of air bleeding of the first closed cavity 17 and the second closed cavity 18 when the second substrate 2 is bonded with the third substrate 15.
Further, the first electrode layer 12 is disposed on the first substrate 1, faces the first cavity 17, and is formed by doping the first substrate 1, and the thickness of the first electrode layer is the same as that of the first substrate 1.
Further, the sensitive film 14 is disposed on the first substrate 1, opposite to the second cavity 18, and both the material and the thickness are the same as those of the first substrate 1.
Further, the first ohmic contact layer 6 is located on the third surface of the second substrate 2, and is formed by doping the second substrate 2, so as to realize ohmic contact between the second substrate 2 and the lead layer 11.
Furthermore, the first stopper layer 3 and the second stopper layer 4 are respectively disposed right below the first electrode layer 12 and the sensitive film 14, and are made of the same material as the second substrate 2, and have a thickness of 100-.
Further, the first insulating layer 5 is disposed on the upper surface of the first stopper layer 3, and the material is, for example, silicon nitride, and the thickness is 200-1000 nm.
Further, the first insulating layer 5 serves for electrical insulation when the first electrode layer 12 is in contact with the first stopper layer 3.
Furthermore, eight second ohmic contact layers 9 are respectively disposed on two sides of the four piezoresistors 8, and are formed by doping the first substrate 1, so as to realize ohmic contact between the piezoresistors 8 and the interconnection metal electrodes.
Further, the four piezoresistors 8R1, R2, R3 and R4 are arranged at the edge of the sensitive film 14, and the four piezoresistors are connected by a Wheatstone bridge. The purpose of this is to place the piezoresistors at the maximum stress of the sensitive membrane 14, so as to increase the sensitivity of the gauge as much as possible.
Furthermore, the lead layer 11 is disposed on the upper surfaces of the first ohmic contact layer 6 and the first electrode layer 12, and is made of metal, preferably at least one of Al, Ti, Au, Cu, and Pt, and has a thickness of 100-.
Further, the second electrode layer 13 is disposed on the upper surface of the second ohmic contact layer 9, and is made of a metal, preferably at least one of Al, Ti, Au, Cu, and Pt, and has a thickness of 100-500 nm. The second electrode layer 13 is used to realize electrode lead-out of the varistor 8.
Further, the third insulating layer 10 is disposed on the first surface of the first substrate 1, and is made of silicon dioxide or silicon nitride and has a thickness of 200-500 nm.
Further, the third insulating layer 10 functions to achieve electrical isolation between the lead layer 11 and the second electrode layer 12 and the second substrate 2. Meanwhile, the protective layer is also used as a passivation layer of the piezoresistor 8 and used for protecting the piezoresistor 8 and improving the stability of the vacuum gauge.
The capacitive thin film gauge structure operates at lower vacuum pressure ranges. In a higher vacuum pressure range, the film electrode contacts the first insulating layer 5, the capacitance type film vacuum gauge structure stops working, and the piezoresistive type film vacuum gauge structure starts working. After the measuring range of the MEMS film vacuum gauge is exceeded, the sensitive film 14 contacts the second stop layer 4, and the piezoresistive film vacuum gauge structure stops working. The two vacuum gauge structures work alternately, and the measuring range of the MEMS film type vacuum gauge is widened.
In addition, the first stop layer 3, the first insulating layer 5 and the second stop layer 4 are used for overload and normal pressure protection of the thin film vacuum gauge, and reliability of the vacuum gauge is improved.
In the above structure, the first substrate 1, the second substrate 2, the first stop layer 3, the second stop layer 4, the first insulating layer 5 and the second insulating layer 7 together form an SOI structure, and the first electrode layer 12 and the sensitive film 14 are formed by a top silicon layer of the SOI structure, so that a large aspect ratio film electrode and an ultrathin sensitive film can be realized, and the sensitivity of the MEMS film vacuum gauge is improved.
The first stop layer 3 and the second stop layer 4 are formed by an SOI structural silicon layer, the distance between the thin film electrode and the fixed electrode is the sum of the thicknesses of the first insulating layer 5 and the second insulating layer 7, the minimum distance between the electrodes can be ensured, and the sensitivity of the MEMS thin film vacuum gauge is further improved.
The distance between the sensitive film 14 and the second stop layer 4 is also the sum of the thicknesses of the first insulating layer 5 and the second insulating layer 7, the second stop layer 4 limits the maximum displacement of the sensitive film 14, and the free deformation of the sensitive film 14 only occurs in a narrow cavity above the second stop layer 4, so that the maximum displacement of the sensitive film 14 is ensured to be less than one fifth of the thickness of the sensitive film, and the good linearity of the MEMS film vacuum gauge is realized.
The working principle of the MEMS film vacuum gauge is as follows:
the second substrate 2, the first stop layer 3, the first insulating layer 5, the first ohmic contact layer 6, the second insulating layer 7, the lead layer 11, the first electrode layer 12 and the first cavity 17 together form a capacitance type thin film vacuum gauge structure. The first electrode layer 12 is used as a thin film electrode, and the second substrate 2 and the first stopper layer 3 are used as fixed electrodes, which form a sensitive capacitor structure. Under low vacuum pressure, the film electrode is pressed and deformed, the distance between the film electrode and the fixed electrode is changed, and the capacitance is changed, so that the conversion from a pressure signal to an electric signal is realized.
The second substrate 2, the second stop layer 4, the piezoresistor 8, the second ohmic contact layer 9, the second electrode layer 13, the sensitive film 14 and the second cavity 18 jointly form a piezoresistive thin-film vacuum gauge structure. Under low vacuum pressure, the sensitive film is pressed and deformed, the resistance value of the piezoresistor 8 on the sensitive film 14 is changed under the action of stress, and the resistance value is converted into a corresponding electric signal through the Wheatstone bridge to be output.
The working state of the MEMS film vacuum gauge is determined by low vacuum pressure, and the capacitance film vacuum gauge structure works in a lower vacuum pressure range. In a higher vacuum pressure range, the film electrode contacts the first insulating layer 5, the capacitance type film vacuum gauge structure stops working, and the piezoresistive type film vacuum gauge structure starts working. After the measuring range of the MEMS film vacuum gauge is exceeded, the sensitive film 14 contacts the second stop layer 5, and the piezoresistive film vacuum gauge structure stops working. The two vacuum gauge structures work alternately, and the measuring range of the MEMS film vacuum gauge is effectively widened.
The SOI structure top silicon layer forms an ultrathin first electrode layer 12 and a sensitive film 14, the SOI structure body silicon layer forms a first stop layer 3 and a second stop layer 4, the minimum electrode spacing of the capacitance type film vacuum gauge structure and the narrow deformation gap of the piezoresistive type film vacuum gauge structure are respectively realized, and the sensitivity and the linearity of the MEMS film vacuum gauge are improved.
Example 2
A method for preparing the MEMS thin film vacuum gauge of example 1, comprising the steps of:
the preparation method of the MEMS film vacuum gauge comprises the following steps:
selecting a first substrate comprising opposing first and second surfaces;
preparing a second insulating layer on the second surface of the first substrate;
selecting a second substrate comprising opposing third and fourth surfaces;
preparing a first stop layer and a second stop layer which are arranged at intervals on a third surface of the second substrate, wherein the surface of the first stop layer further comprises a first insulating layer;
bonding the second surface of the first substrate with the second insulating layer and the third surface of the second substrate;
thinning the first surface of the first substrate, wherein the first substrate, the first insulating layer, the second insulating layer and the second substrate form an SOI structure;
etching areas, corresponding to the first stop layer and the second stop layer, of the fourth surface of the second substrate until the second insulating layer;
removing the first stop layer and the second insulating layer of the second stop layer region;
preparing a piezoresistor on a first surface of the first substrate corresponding to the second stop layer;
selecting the third substrate;
and bonding the third substrate and the fourth surface of the second substrate to form a first closed cavity and a second closed cavity.
Specifically, the method comprises the following steps: referring to fig. 5 to 23, the method for manufacturing the MEMS vacuum gauge according to the present invention may include the steps of:
(a) selecting an N-type 100 silicon wafer with the thickness of 300mm as a first substrate 1, as shown in FIG. 6;
(b) selecting a low-resistance silicon wafer with the thickness of 300mm as the second substrate 2, and carrying out CMP and cleaning on the second substrate 2, as shown in FIG. 7;
(c) a notch for preparing the first insulating layer 5 is etched on the third surface of the second substrate 2 by photolithography and RIE (Reactive Ion Etching), as shown in fig. 8;
(d) preparing the first stopper layer 3 and the second stopper layer 4 on the third surface of the second substrate 2 by photolithography and RIE, as shown in fig. 9;
(e) silicon nitride as a first insulating layer 5 was prepared to a thickness of 500nm on the upper surface of the first stopper layer 3 by PECVD (Plasma Enhanced Chemical Vapor Deposition), as shown in fig. 10;
(f) preparing a first ohmic contact layer 5 on the third surface of the second substrate 2 by photolithography and a thick B implantation, as shown in fig. 11;
(g) silicon dioxide of 500nm is prepared as the second insulating layer 7 on the second surface of the first substrate 1 by thermal oxidation, as shown in fig. 12;
(h) performing oxygen plasma activation and hydrophilic treatment on the third surface of the second substrate 2, and then performing low-temperature direct bonding with the second surface of the first substrate 1 with the second insulating layer 7, as shown in fig. 13;
(i) the bonded first substrate 1 is thinned to 5mm by CMP, and the first substrate 1, the second substrate 2, the first stopper layer 3, the second stopper layer 4, the first insulating layer 5, and the second insulating layer 7 collectively form an SOI structure, as shown in fig. 14.
(j) The fourth surface of the second substrate 2 is etched by RIE stopping to the lower surfaces of the first stopper layer 3 and the second stopper layer 4. As shown in fig. 15;
(k) etching the second insulating layer 7 by gaseous HF to form a cavity above the first insulating layer 5 and the second stopper layer 4, while releasing to form the sensitive film 14, as shown in fig. 16;
(l) BF33 type glass is selected as a third substrate 15, and a TiZrV film with the thickness of 200nm is prepared on the upper surface of the third substrate 15 as a getter layer 16 through magnetron sputtering, as shown in FIG. 17;
(m) closely attaching the fourth surface of the second substrate 2 to the upper surface of the third substrate 15 by anodic bonding to form a first sealed cavity 17 and a second sealed cavity 18, as shown in fig. 18;
(n) preparing the piezoresistors 8 on the first side of the first substrate 1 by photolithography and light B implantation, as shown in fig. 19;
(o) preparing a first electrode layer 12 and a second ohmic contact layer 9 on the first surface of the first substrate 1 by photolithography and a dense B implantation, as shown in fig. 20;
(p) etching a lead layer window and an electrical isolation window between the first electrode layer 12 and the sensitive film 14 on the first substrate 1 by photolithography and RIE, as shown in fig. 21;
(q) preparing silicon dioxide as a third insulating layer 10 with a thickness of 200nm on the first surface of the first substrate 1 and the inner surface of the window of the wiring layer by thermal oxidation, as shown in fig. 22;
(r) a metal electrode window was etched on the third insulating layer 10 by photolithography and RIE, and Cr of 20nm and Au of 180nm in thickness were prepared as the lead layer 11 and the second electrode layer 13 on the metal electrode window and the lead layer window by photolithography and magnetron sputtering, and the device was completed as shown in fig. 23.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. compared with the traditional MEMS film vacuum gauge, the MEMS film vacuum gauge provided by the invention integrates the MEMS capacitive film vacuum gauge and the piezoresistive film vacuum gauge on the same wafer by combining an SOI (silicon on insulator) silicon wafer with a back cavity etching process, is simple and convenient in process, and effectively improves the measuring range of the MEMS film vacuum gauge on the premise of ensuring the sensitivity of the two gauges.
2. According to the MEMS film vacuum gauge, the ultrathin first electrode layer 12 and the sensitive film 14 are prepared by utilizing the top silicon layer of the SOI structure, the deformation of the first electrode layer 12 and the sensitive film 14 is limited in a narrow cavity above the first stop layer 3 and the second stop layer 4 by etching the first stop layer 3 and the second stop layer 4 formed by the bulk silicon layer of the SOI structure, and the sensitivity and the linearity of the MEMS film vacuum gauge are improved.
3. The invention is prepared by adopting the MEMS technology, and the sensor has the advantages of small size, high precision, good consistency, easy batch manufacturing and low cost.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (10)
1. A MEMS thin film vacuum gauge, comprising:
a first substrate, a second substrate, and a third substrate which are stacked;
the first closed cavity and the second closed cavity are closed between the first substrate and the third substrate at intervals;
a first electrode corresponding to a region of the first substrate above the first hermetically sealed cavity;
the sensitive film corresponds to the area of the first substrate above the second closed cavity;
the first stop layer is arranged in a first closed cavity below the first electrode;
the second stop layer is arranged in a second closed cavity below the sensitive film;
the first stop layer and the second stop layer are formed by etching the second substrate.
2. The MEMS thin film gauge of claim 1, wherein the first and second substrates are a top silicon layer and a bulk silicon layer, respectively, of an SOI substrate.
3. The MEMS thin film gauge according to claim 1 or 2, further comprising a first insulating layer provided on the first stopper layer, the first insulating layer being for electrical insulation between the first electrode layer and the first stopper layer.
4. The MEMS thin film gauge of claim 2, wherein the spacing between the first stop layer and the first electrode and between the second stop layer and the sensitive thin film is the sum of the thicknesses of the first insulating layer and the second insulating layer of the SOI substrate.
5. The MEMS thin film vacuum gauge according to claim 1, further comprising a piezoresistor disposed on the sensitive thin film; and/or the piezoresistors form a Wheatstone bridge.
6. The MEMS thin film gauge according to claim 1, wherein the first electrode is formed by ion implantation into the first substrate.
7. The MEMS thin film vacuum gauge according to claim 3, further comprising a third insulating film provided on an upper surface of the first substrate.
8. The MEMS thin film vacuum gauge of claim 1, further comprising a getter layer disposed on a surface of a third substrate within the first and second sealed cavities.
9. A preparation method of an MEMS film vacuum gauge is characterized by comprising the following steps:
selecting a first substrate comprising opposing first and second surfaces;
preparing a second insulating layer on the second surface of the first substrate;
selecting a second substrate comprising opposing third and fourth surfaces;
preparing a first stop layer and a second stop layer which are arranged at intervals on a third surface of the second substrate, wherein the surface of the first stop layer further comprises a first insulating layer;
bonding the second surface of the first substrate with the second insulating layer and the third surface of the second substrate;
thinning the first surface of the first substrate, wherein the first substrate, the first insulating layer, the second insulating layer and the second substrate form an SOI structure;
etching areas, corresponding to the first stop layer and the second stop layer, of the fourth surface of the second substrate until the second insulating layer;
removing the first stop layer and the second insulating layer of the second stop layer region;
preparing a piezoresistor on a first surface of the first substrate corresponding to the second stop layer;
selecting a third substrate;
and bonding the third substrate and the fourth surface of the second substrate to form a first closed cavity and a second closed cavity.
10. The method of claim 9, further comprising a step of forming a getter layer on the bonding surface of the third substrate.
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| CN114720048A (en) * | 2022-06-09 | 2022-07-08 | 季华实验室 | Capacitor film vacuum gauge and NEG film preparation method |
| CN115057406A (en) * | 2022-04-15 | 2022-09-16 | 山东大学 | MEMS vacuum gauge based on snake-shaped porous silicon heat insulation layer and preparation method |
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| CN114720048B (en) * | 2022-06-09 | 2022-09-02 | 季华实验室 | Capacitor film vacuum gauge and NEG film preparation method |
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