CN205317381U

CN205317381U - Sensitive chip of SOI pressure based on sacrifice layer technique

Info

Publication number: CN205317381U
Application number: CN201620017149.5U
Authority: CN
Inventors: 揣荣岩; 衣畅; 张晓民; 关若飞; 关艳霞; 李新; 刘一婷
Original assignee: Shenyang University of Technology
Current assignee: Shenyang University of Technology
Priority date: 2016-01-08
Filing date: 2016-01-08
Publication date: 2016-06-15
Anticipated expiration: 2026-01-08

Abstract

The utility model discloses a sensitive chip of SOI pressure based on sacrifice layer technique. This chip adopts single crystalline silicon thin film (SOI) material manufacturing on the insulating layer, and including SOI's monocrystalline silicon underlay, the SOI silica insulating layer is as the cavity of sacrifice layer formation, the sculpture shield groove formed on single crystalline silicon thin film four meet an emergency resistance and plain conductor. Silicon nitride insulation protective layer and outermost polysilicon structure layer about the plain conductor constitute sensitive chip pressure sensing membrane, eight quad slits of pressure sensing membrane edge sculpture with single crystalline silicon thin film jointly for corrode the silica sacrifice layer. Four resistance of meeting an emergency connect into wheatstone bridge through plain conductor, convert pressure signal to voltage signal output. The sensitive chip of SOI pressure based on sacrifice layer technique of preparation has that sensilla sensitivity is high, repeatability and stability is good, the reliability is high, high temperature resistant, radioresistance and advantages such as manufacturing process and integrated circuit technology compatibility.

Description

Based on the SOI presser sensor chip of sacrificial layer technology

Technical field

The utility model relates generally to a kind of SOI presser sensor chip based on sacrificial layer technology. Belong to MEMS (micro electro mechanical system) (MEMS) field.

Background technology

Constantly promote the background of modern industry high speed development in information technology under, MEMS sensor receives much concern, and particularly MEMS pressure sensor has been widely used in all trades and professions such as industrial production, aerospace, electric power petrochemical industry. Current diffusion silicon pressure sensor is still the maximum pressure transmitter of market sales volume, but the operating temperature range of this kind of pressure resistance type sensor is generally no more than 120 DEG C, this is because the strain resistor of diffusion silicon pressure sensor is the electrical isolation realizing itself and substrate using pn knot as sealing coat. And when working temperature is more than 120 DEG C, silicon materials are due to intrinsic excitation, the reverse leakage current that its pn ties increases rapidly, so generally can not carry out pressure survey under higher than the environment of 120 DEG C. And in modern industry production, aerospace and Military activity, the pressure survey under high-temperature severe environment is essential, needs the pressure transmitter of working temperature more than 150 DEG C in a large number at vehicle electric field especially at present. Just under the background of this kind of market requirement, this patent proposes the SOI presser sensor chip based on sacrificial layer technology and manufacture method thereof, and obtains the subsidy (project approval number 61372019) of state natural sciences fund.

SOI material introduces silicon dioxide insulating layer between its top layer silicon film and substrate silicon, achieves media isolated, it is possible to make the working temperature of sensor reach more than 300 DEG C between top layer and substrate. Therefore, SOI material is the good material making high-temp pressure sensor.

Currently, most of SOI high-temp pressure sensor is that SOI top monocrystalline silicon film is made 4 strain resistors, and strain resistor is linked to be comparison bridge by splash-proofing sputtering metal, afterwards at the wafer rear making structure of silicon cup formation flexible sheet of the suitable position of corresponding 4 strain resistors.Owing to adopting structure of silicon cup, sensor bulk is relatively big, and technique and integrated circuit technology are not easily compatible, are unfavorable for integrated.

The cavity of MEMS sacrificial layer fabrication techniques is adopted to overcome the above-mentioned shortcoming of structure of silicon cup. This kind of sacrificial layer structure pressure transmitter adopts silicon-dioxide to be sacrifice layer usually, polysilicon is sensitive diaphragm, the polysilicon membrane of media isolated is strain resistor, has that volume is little, an operating temperature range width and be conducive to integrated advantage with ic process compatibility. But owing to using polysilicon strain resistor, the repeatability of sensor and sluggishness wait poor-performing.

Based on the problems referred to above, the utility model is intended to propose the three aspect advantages such as a kind of comprehensive silicon single crystal strain resistor, sacrifice layer cavity configuration and media isolated semiconductor pressure sensor chip.

Summary of the invention

Goal of the invention:

The utility model is a kind of SOI presser sensor chip based on sacrificial layer technology. Object is to improve device temperature characteristic, reduce sensor bulk and widen operating temperature range.

Technical scheme:

The utility model is achieved through the following technical solutions:

Based on the SOI presser sensor chip of sacrificial layer technology, it is characterized in that: this chip adopts monocrystalline silicon thin film (SOI) the material manufacture on insulation layer, comprise the monocrystalline substrate of SOI, the cavity that SOI silicon dioxide insulating layer is formed as sacrifice layer, etches four strain resistors and metal wire thereof that isolation channel is formed on monocrystalline silicon thin film; Polysilicon structure layer and the monocrystalline silicon thin film of the insulating silicon nitride protective layer that metal wire is upper and lower and twice deposit formation form sensitive chip pressure sensitive film jointly, and pressure sensitive film etching edge has eight square corrosion holes, for corrode silicon dioxide sacrifice layer; Four strain resistors connect into comparison bridge by metal wire, pressure signal converts to voltage signal and exports.

Strain resistor is made up of the monocrystalline silicon thin film on SOI material, realizes electric isolution by isolation channel and monocrystalline silicon thin film, is positioned at inside polysilicon structure layer.

Advantage and effect:

The utility model has the following advantages and useful effect:

SOI presser sensor chip based on sacrificial layer technology described in the utility model adopt monocrystalline silicon thin film make strain resistor, make sensor highly sensitive, repeatability and good stability; Strain resistor is positioned at inside polysilicon structure layer, is subject to good protection, it is to increase the reliability of chip; Media isolated is adopted to improve senor operating temperature scope.

Accompanying drawing explanation

Fig. 1 is the utility model chip plane schematic diagram.

Fig. 2 is the utility model chip AA ＇ diagrammatic cross-section.

Fig. 3 be in the utility model chip manufacture process first time photoetching after schematic diagram, wherein, Fig. 3 (a) be in the utility model chip manufacture process first time photoetching after floor map; Fig. 3 (b) be in the utility model chip manufacture process first time photoetching after AA ＇ diagrammatic cross-section.

Fig. 4 is that in the utility model chip manufacture process, second time photoetching forms the AA ＇ diagrammatic cross-section after isolation channel.

Fig. 5 is AA ＇ diagrammatic cross-section after deposit the first layer silicon nitride protective layer in the utility model chip manufacture process.

Fig. 6 is that in the utility model chip manufacture process, third time photoetching forms the AA ＇ diagrammatic cross-section after fairlead.

Fig. 7 is that in the utility model chip manufacture process, four mask forms the AA ＇ diagrammatic cross-section after metal wire.

Fig. 8 is AA ＇ diagrammatic cross-section after deposit second layer silicon nitride protective layer in the utility model chip manufacture process.

Fig. 9 is AA ＇ diagrammatic cross-section after deposit the first layer polysilicon structure layer in the utility model chip manufacture process.

Figure 10 is that in the utility model chip manufacture process, the 5th photoetching forms the BB ＇ diagrammatic cross-section after corrosion hole.

Figure 11 is BB ＇ diagrammatic cross-section after corrode silicon dioxide sacrifice layer in the utility model chip manufacture process.

Figure 12 is that in the utility model chip manufacture process, deposit second layer polysilicon forms the BB ＇ diagrammatic cross-section after enclosed housing.

Description of reference numerals:

1. monocrystalline substrate, 2. cavity, 3. monocrystalline silicon thin film, 4. isolation channel, 5. strain resistor, 6. metal wire, the 7. square corrosion hole of insulating silicon nitride protective layer 8. polysilicon structure layer 9..

Embodiment

Below by accompanying drawing, the utility model is described in further detail:

The utility model provides a kind of SOI presser sensor chip based on sacrificial layer technology, as depicted in figs. 1 and 2, it is characterized in that: this chip adopts monocrystalline silicon thin film (SOI) the material manufacture on insulation layer, comprise the monocrystalline substrate 1 of SOI, it it is the cavity 2 that SOI silicon dioxide insulating layer is formed as sacrifice layer above monocrystalline substrate 1, it is monocrystalline silicon thin film 3 above cavity 2, monocrystalline silicon thin film 3 etches four strain resistors 5 and metal wire 6 thereof that isolation channel 4 is formed. Being positioned at the insulating silicon nitride protective layer 7 above and below metal wire 6 and outermost polysilicon structure layer 8 and monocrystalline silicon thin film 3 and jointly form sensitive chip pressure sensitive film, the square corrosion hole 9 of pressure sensitive film etching edge eight, for corrode silicon dioxide sacrifice layer. Four strain resistors 5 connect into comparison bridge by metal wire 6, pressure signal converts to voltage signal and exports.

By changing thickness and the size of the utility model sensor enclosed housing pressure sensitive film, the pressure transmitter of various range can be designed.

Principle of design of the present utility model: main structure of the present utility model is made up of silicon substrate, pressure sensitive film, cavity, corrosion hole and strain resistor. Pressure sensitive film is made up of monocrystalline silicon layer, silicon nitride protective layer and polysilicon structure layer three part; cavity adopts MEMS surface micro-fabrication technology; i.e. sacrificial layer technology; remove silicon dioxide sacrificial layer with hydrofluoric acid by corrosion hole and become; corrosion hole is closed with polysilicon; pressure sensitive film and silicon substrate form closed cavity, are approximately vacuum. Selecting [110] crystal orientation on monocrystalline silicon thin film to arrange four monocrystalline silicon thin film strain resistors, and connect into comparison bridge, form pressure measurement circuitry, circuit adopts constant voltage source or constant current source power supply.

When pressure effect, sensor diaphragm bends, and membrane strains acts on strain resistor and produces pressure inhibition effect, and it is corresponding with force value that Hui Sitong exports differential voltage signal. When pressure is when transducer range scope, sensor exports and the linear magnitude of voltage of pressure, when pressure exceed range reach a certain value time, the pressure sensitive film of sensor contacts with substrate, slowing down diaphragm stress with pressure trend, under ensureing big pressure, diaphragm does not rupture, it is to increase overload capacity.

SOI wafer material is adopted to make presser sensor chip radiation hardness, high temperature resistant, applicable in the compound integrated circuit or the high-withstand-voltage integrated circuit that carry multiple power element. Wherein, strain resistor is positioned at inside polysilicon structure layer, realizes, by isolation ring, the reliability that electrical isolation improves chip.

The step of preparation process of sensor chip described in the utility model is as follows:

(1) suitable SOI wafer (suitable monocrystalline silicon thin film resistivity and thickness of insulating layer) is selected.

(2) conventional clean after, select [110] crystal orientation to carry out first time photoetching, SOI material formed such as Fig. 3 (a), 3(b) shown in structure.

(3) carry out second time photoetching, the monocrystalline silicon thin film that step (1) is formed etches isolation channel, forms four strain resistors, as shown in Figure 4.

(4) silicon nitride film of Low Pressure Chemical Vapor Deposition (LPCVD) deposit suitable thickness (thickness is selected according to concrete process condition) is utilized to do the first layer insulating silicon nitride protective layer, as shown in Figure 5.

(5) carry out third time photoetching, utilize plasma etching method to form strain resistor fairlead, as shown in Figure 6.

(6), after forming fairlead, deposited metal, carries out four mask and forms metal wire, as shown in Figure 7.

(7) adopt the silicon nitride passivation film of LPCVD deposit suitable thickness, form second layer insulating silicon nitride protective layer, as shown in Figure 8.

(8) adopt the polysilicon of LPCVD deposit suitable thickness (thickness is suitably selected according to chip range) as the first layer structural sheet, as shown in Figure 9.

(9), after annealing, carry out the 5th photoetching and form eight square corrosion holes, as shown in Figure 10.

(10) chip be put in hydrofluoric acid solution by corrosion hole corrosion remove silicon dioxide sacrificial layer, adopt critical desiccating method, namely corrosive fluid uses high-pressure liquid CO gradually₂Replacing, sample is placed in CO afterwards₂In stagnation point, the interface of gas, liquid disappears, drier silicon chip, as shown in figure 11.

(11) utilize the polysilicon of LPCVD deposit suitable thickness (thickness is suitably selected according to chip range), form enclosed housing, form the pressure sensitive film containing polysilicon, silicon nitride and silicon single crystal three layers, as shown in figure 12.

(12) six photoetching form outer lead pressure welding point.

(13) scribing, test.

This kind of the utility model can extensively for the pressure survey in the fields such as multichannel pressure survey in automobile, environmental Kuznets Curves pressure survey and airline, petrochemical industry, electric power based on the SOI presser sensor chip of sacrificial layer technology.

Claims

1. based on the SOI presser sensor chip of sacrificial layer technology, it is characterized in that: this chip adopts the monocrystalline silicon thin film SOI material on insulation layer to manufacture, comprise the monocrystalline substrate (1) of SOI, the cavity (2) that SOI silicon dioxide insulating layer is formed as sacrifice layer, etches four strain resistors (5) and metal wire (6) thereof that isolation channel (4) is formed on monocrystalline silicon thin film (3); The insulating silicon nitride protective layer (7) that metal wire (6) is upper and lower and the polysilicon structure layer (8) that twice deposit is formed form sensitive chip pressure sensitive film jointly with monocrystalline silicon thin film (3), pressure sensitive film etching edge has eight square corrosion holes (9), for corrode silicon dioxide sacrifice layer; Four strain resistors (5) connect into comparison bridge by metal wire (6), pressure signal converts to voltage signal and exports.

2. the SOI presser sensor chip based on sacrificial layer technology according to claim 1, it is characterized in that: strain resistor (5) is made up of the monocrystalline silicon thin film on SOI material, realize electric isolution by isolation channel (4) and monocrystalline silicon thin film (3), it is positioned at polysilicon structure layer (8) inner side.