CN203216646U - Piezoresistive high frequency dynamic soil stress sensor - Google Patents

Abstract

The utility model discloses a piezoresistive high frequency dynamic soil stress sensor comprising a sensor housing (7), a stress sensitive assembly, a signal conditioning amplification circuit (11) and a lead-out cable (13); the stress sensitive assembly comprises a substrate (1), an insulation isolation layer (2), a strain resistor (3) and an insulation protection layer (5); and the stress sensitive assembly is packaged on a clamped step (18) on a front end of the sensor housing (7) through high borosilicate glass (6). The sensor sensitive assembly is integrated with the strain resistor (3) and an adjusting resistor (19), effectively reduces the size, simplifies processing technology, lowers making cost, large scale production is easily realized, thereby improving product cost performance and market competitiveness.

Description

The dynamic soil stress sensor of piezoresistance type high-frequency

Technical field

The utility model relates to the dynamic soil stress sensor of a kind of piezoresistance type high-frequency, the soil stress measurement sensor that particularly a kind of soil stress for underground danger wastes surrounding enviroment is measured, chemical explosion shock wave and seismic event cause.

Background technology

Developing rapidly of nuclear industry produced a large amount of nuclear wastes, and how the especially high nuclear waste of putting carries out safe disposal and become the urgent day by day environmental problem that needs solution.At present, put the dark geology burying storage of the general employing of nuclear waste disposal for height, by leakage and migration natural and artificial barrier system prevention nucleic, reach the purpose that height is put the nuclear waste safe disposal.Nuclear explosion or chemical explosion shock wave and seismic event may destroy the protection system that height is put the nuclear waste storing place, therefore are necessary peripheral soil environment is monitored timely and effectively.In addition, nuclear explosive shock wave, deep layer are implemented bomb and also can be exerted an influence to buildings, building fortification, and this just requires soil stress sensor to have the better dynamic characteristic, can in time and reflect truly that the soil stress of generation distributes.The utility model is based on MEMS(Micro Electro Mechanical System) sensor made of micromachined technology, more conventional sensor of the same type has higher sensitivity, have good static and dynamic performance simultaneously, the soil stress that can adapt to multiple field is measured.

Traditional soil stress sensor sensing assembly normally constitutes Wheatstone bridge in the strain voltage dependent resistor (VDR) that monocrystalline silicon substrate utilizes oxidation, diffusion or methods such as ion implantation doping, photoetching to be made into.Adopt the piezoresistance sensitivity assembly of SMD structure, shortcoming is that the device diameter is big, and frequency response is low, and the rise time is longer, and sensor accuracy and long-time stability are relatively poor, the processing technology complexity.

Summary of the invention

The sensor diameter that the problem of first aspect to be solved in the utility model is to overcome prior art is big, frequency response low and defective such as low precision, and a kind of have high dynamic response frequency, anti-interference, dynamic property is good by force the dynamic soil stress sensor of piezoresistance type high-frequency are provided.

In order to solve the technical matters of above-mentioned first aspect, the technical scheme that the utility model provides is: the dynamic soil stress sensor of a kind of piezoresistance type high-frequency, comprise sensor housing, stress sensitive assembly, signal condition amplifying circuit and outgoing cable, it is characterized in that described stress sensitive assembly comprises the structure that substrate-dielectric isolation layer-strain resistor-insulating protective layer constitutes; And described stress sensitive assembly is packaged on the solid Zhi Taijie of sensor housing front end by high-boron-silicon glass.

Preferably, described basalis is the stainless steel diaphragm of high Young's modulus, and described sensor housing is made by high-quality Hitachi alloy, and described strain resistor is semiconductor strain resistance.

Preferably, described strain resistor is boron-doping P type microcrystal silicon strain resistor.

Preferably, dielectric isolation layer and insulating protective layer are prepared from by the silicon dioxide insulator material.

Preferably, described stress sensitive assembly also comprises the adjustment resistance that is located at the strain resistor periphery, as standby compensating resistance.

The preparation method of stress sensitive assembly is characterized in that, comprises the steps:

(1) at basalis ion beam sputtering one deck dielectric isolation layer;

(2) on the dielectric isolation layer in the quick district of power, prepare boron-doping P type microcrystal silicon strain resistor with chemical vapour deposition technique, make the resistor disc of strain sensitive then of lithography corrosion process, constitute Wheatstone bridge;

(3) prepare the different NiCr of a series of resistances with the mask sputtering method and adjust resistance and corresponding gold electrode;

(4) with ion beam sputtering one deck insulating protective layer.

Preferably, boron-doping P type microcrystal silicon can be by PECVD or the preparation of ICP chemical vapour deposition technique.

Preferably, dielectric isolation layer (2) and insulating protective layer (5) are prepared from by the silicon dioxide insulator material.

The utility model is according to sensitive material layer, insulation course, transition matching layer and encapsulating structure design characteristic and difference, select flexibly MEMS technology such as magnetron sputtering, ion beam sputtering, PECVD and micrographics realization or adopt the quick soil stress sensor of novel dynamic force of two kinds and two or more fabrication techniques simultaneously, have high dynamic response frequency, anti-interference, rise time submicrosecond level, high range, the dynamic soil stress sensor of piezoresistance type high-frequency that dynamic property is good by force.

The utility model has the advantages that: the stainless steel of high Young's modulus is adopted in the sensing assembly substrate of the soil stress high frequency dynamic pickup in the utility model, can directly experience the strain pressure of surrounding soil, effectively improve precision, natural frequency and the long-time stability of stress sensitive assembly.The piezoresistive principles of utilizing this sensor realizes the conversion between stress-electric signal, adopt MEMS micromachining technologies such as sputter, micrographics realization to make boron-doping P type microcrystal silicon pressure resistance photosensitive elements, thereby the sensing assembly size is little, and (diameter is Φ 15mm to Φ 30mm, thickness be not more than this profile diameter 1/2), the rigidity height, natural frequency is at 500KHz to 2.5MHz, rise time be microsecond to the submicrosecond level, detect ess-strain sensitivity and can reach 0.1 below the microstrain.This sensor sensing assembly is integrated with strain resistor and adjusts resistance, effectively reduces volume, has simplified processing technology, reduces cost of manufacture, realizes easily producing in enormous quantities, has improved product price ratio and the market competitiveness.

Description of drawings

Fig. 1 is the structural representation of the dynamic soil stress sensor of the utility model piezoresistance type high-frequency.

Wherein:

The 1-substrate	The 2-dielectric isolation layer
		The 3-strain resistor	The 4-gold electrode
The 5-insulating protective layer	The 6-high-boron-silicon glass
		The 7-sensor housing	The 8-spun gold
The 9-card extender	The 10-inner cable
		11-signal condition magnification circuit plate	12-stainless steel bonnet
The 13-outgoing cable	The 14-solidus is chewed
		15-solidus cap	16-stainless steel flexible hose line outlet
17-electrostatic sealing-in face	The solid Zhi Taijie of 18-
		19-adjusts resistance	?

Embodiment

Be further described below in conjunction with accompanying drawing 1:

A kind of high frequency dynamic force sensor of measuring underground danger wastes surrounding enviroment soil stress mainly is made up of sensor housing 7, stress sensitive assembly and signal condition amplifying circuit 11, this sensor housing is made by high-quality Hitachi alloy, and described stress sensitive assembly comprises that the structure of the stress sensitive assembly of the soil stress high frequency dynamic pickup in the utility model is made of substrate 1-dielectric isolation layer 2-boron-doping P type microcrystal silicon strain resistor 3-insulating protective layer 5; Patty stress sensitive assembly passes through high-boron-silicon glass 6 electrostatic sealing-ins in the solid Zhi Taijie 18 of sensor housing 7 front ends, the stainless steel diaphragm 1 of this stress sensitive assembly adopts the laser bonding mode to fix with sensor housing 7, adopt the gold ball bonding method to draw spun gold internal lead 8 on the gold electrode 4 on this sensing assembly, be connected to the card extender 9 that is fixed in sensor housing 7 inside, be connected to the signal condition amplifying circuit 11 that is fixed in sensor housing 7 by inner cable 10 then, stress signal passes solidus bottom the sensor housing through conditioning amplifying circuit 11 back successively by outgoing cable 13 and chews 14 and screwed solidus cap 15, by 16 outputs of stainless steel flexible hose line outlet, this solidus cap sealing is rotated with this solidus chews, be convenient to lock this outgoing cable, stainless steel bonnet 12 is fixed with sensor housing 7 employing welding manners and is sealed.

In the utility model one preferred embodiment, sensor housing 7 adopts high-quality Hitachi alloy, high-quality 17-4 stainless steel flexible sheet is adopted in the substrate 1 of this stress sensitive assembly, 1., surperficial no marking (no penetrability cut after 50 times of amplifications) membrane surface polishes through precision lapping machine, reaches following standard:; 2., flatness: ± 0.005mm; 3., roughness: Ra≤0.05.This stress sensitive structural manufacturing process flow process is as follows: (1) prepares layer of silicon dioxide dielectric isolation layer 2 with ion beam sputtering method; (2) prepare boron-doping P type microcrystal silicon strain resistor 3 films with the PECVD method, adopt photoetching technique to make wheatstone bridge configuration as strain resistor then; (3) prepare NiCr with mask and magnetically controlled sputter method and adjust resistance 19 and gold electrode 4; (4) can not be exposed to atmosphere with ion beam sputtering layer of silicon dioxide insulating protective layer 5 with protection strain resistor and adjustment resistance, in order to avoid the resistor stripe oxidation.

On the front dielectric isolation layer 2 of this stress sensitive assembly, except strain resistor 3 and adjustment resistance 19, also preparation has series of gold electrode 4, and different gold electrodes connects with the adjustment resistance of different resistances, looks it and need select different gold electrode 4.The diameter of this stress sensitive assembly is no more than Φ 8mm, and the substrate of stress sensitive assembly is stainless steel diaphragm 1, and its thickness is 2mm～4mm; The thickness of dielectric isolation layer 2 is 1 μ m～3 μ m, and resistivity surpasses 10 ¹⁴Ω ﹒ m; Boron-doping P type microcrystal silicon 3 is made Wheatstone bridge as strain resistor, and thickness is 1 μ m～3 μ m, and resistance is 1K Ω～10K Ω; The thickness of insulating protective layer 5 is 0.3 μ m～0.5 μ m.

The signal condition amplifying circuit 11 of this sensor is provided with thermo-compensator, outgoing cable 13 is drawn from signal condition amplifying circuit 11, the solidus of passing housing 7 bottom sides successively chews 14, draw behind screwed solidus cap 15 and the stainless steel flexible hose line outlet 16, these solidus cap 15 sealings are rotated with in solidus chews 14, is convenient to lock this outgoing cable 13.This sensor profile diameter is Φ 15mm to Φ 30mm, and thickness is not more than 1/2 of profile diameter.This signal condition amplifying circuit 11 is converted into the output of this sensor the standard signal output of 0～5VDC, 1～5VDC or 4～20mADC.

When technical measures according to the rules, with the sensor landfill in the utility model in the soil body in tested zone, when the external force that the soil body is subjected to is delivered to sensor, directly by the impression of the stainless steel-based end of the high Young's modulus of stress sensitive assembly.The big or small δ of this strain and the pressure P that compression face is experienced have following relation:

${\mathrm{\δ}}_r=\frac{3p}{8{\mathrm{Eh}}^2}[{r_0}^2(1+\mathrm{\μ})-r^2(3+\mathrm{\μ})]$

${\mathrm{\δ}}_t=\frac{3p}{8{\mathrm{Eh}}^2}[{r_0}^2(1+\mathrm{\μ})-r^2(1+3\mathrm{\μ})]$

The natural frequency of the round flat diaphragm of periphery fixed:

$f_0=\frac{5.11\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002826237900011.png"\; state="\{\{state\}\}">h</figure-callout>}}{2{\mathrm{\&pi;r}}_0^2}{\left[\frac{E}{3(1-{\mathrm{\&mu;}}^2)\mathrm{\&rho;}}\right]}^{1/2}$

In the formula, δ _rRadial stress; δ _tTangential stress; f ₀Natural frequency; The stainless elastic modulus of E; The thickness of h stainless steel diaphragm; r ₀Effective radius of clean-up of stainless steel diaphragm; The Poisson ratio of μ stainless steel material; The mass density of ρ stainless steel material.

Certainly, above-described embodiment only is explanation technical conceive of the present utility model and characteristics, and its purpose is to allow people can understand content of the present utility model and implements according to this, can not limit protection domain of the present utility model with this.All equivalent transformation or modifications of doing according to the spiritual essence of the utility model main technical schemes all should be encompassed within the protection domain of the present utility model.

Claims (5)

1. the dynamic soil stress sensor of piezoresistance type high-frequency, comprise sensor housing (7), stress sensitive assembly, signal condition amplifying circuit (11) and outgoing cable (13), it is characterized in that described stress sensitive assembly comprises the structure that substrate (1)-dielectric isolation layer (2)-strain resistor (3)-insulating protective layer (5) constitutes; And described stress sensitive assembly is packaged on the solid Zhi Taijie (18) of sensor housing (7) front end by high-boron-silicon glass (6).

2. the dynamic soil stress sensor of piezoresistance type high-frequency according to claim 1, it is characterized in that, described substrate (1) layer is the stainless steel diaphragm of high Young's modulus, and described sensor housing (7) is made by high-quality Hitachi alloy, and described strain resistor (3) is semiconductor strain resistance.

3. the dynamic soil stress sensor of piezoresistance type high-frequency according to claim 1 and 2 is characterized in that, described strain resistor (3) is boron-doping P type microcrystal silicon strain resistor.

4. the dynamic soil stress sensor of piezoresistance type high-frequency according to claim 1 and 2 is characterized in that, dielectric isolation layer (2) and insulating protective layer (5) are prepared from by the silicon dioxide insulator material.

5. the dynamic soil stress sensor of piezoresistance type high-frequency according to claim 1 is characterized in that, described stress sensitive assembly also comprises the adjustment resistance that is located at the strain resistor periphery.

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