CN104359611B - A kind of internal stress influence lower pressure sensor nonlinear discriminant method - Google Patents
A kind of internal stress influence lower pressure sensor nonlinear discriminant method Download PDFInfo
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- CN104359611B CN104359611B CN201410581587.XA CN201410581587A CN104359611B CN 104359611 B CN104359611 B CN 104359611B CN 201410581587 A CN201410581587 A CN 201410581587A CN 104359611 B CN104359611 B CN 104359611B
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- 239000010409 thin film Substances 0.000 claims abstract description 36
- 238000006073 displacement reaction Methods 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000009826 distribution Methods 0.000 claims abstract description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 239000010703 silicon Substances 0.000 claims description 11
- TWXTWZIUMCFMSG-UHFFFAOYSA-N nitride(3-) Chemical compound [N-3] TWXTWZIUMCFMSG-UHFFFAOYSA-N 0.000 claims description 7
- 239000010408 film Substances 0.000 claims description 6
- 239000012528 membrane Substances 0.000 claims description 4
- 238000007373 indentation Methods 0.000 claims description 3
- 239000011159 matrix material Substances 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 12
- 239000007787 solid Substances 0.000 abstract description 5
- 238000005457 optimization Methods 0.000 abstract description 4
- 238000011068 load Methods 0.000 description 9
- 229910004541 SiN Inorganic materials 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 238000007906 compression Methods 0.000 description 2
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000005459 micromachining Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 210000004369 Blood Anatomy 0.000 description 1
- MROCJMGDEKINLD-UHFFFAOYSA-N Dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000003750 conditioning Effects 0.000 description 1
- 230000004059 degradation Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000003628 erosive Effects 0.000 description 1
- 238000010197 meta-analysis Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000001131 transforming Effects 0.000 description 1
Abstract
The invention provides a kind of internal stress influence lower pressure sensor nonlinear discriminant method, first, measure the Young's modulus of pressure sensor chip structure sheaf thin film, initial inner-stress value；Utilize ANSYS software to use Solid 186 cell type, create pressure sensor chip structural model, after completing Geometric Modeling and definition material parameter, model is carried out stress and strain model；Apply displacement constraint, described model periphery is fixed, limit the degree of freedom in tri-directions of X, Y, Z, apply impressed pressure, solve stress, amount of deflection distribution, obtain equivalent stress cloud atlas；The initial internal stress of thin film is introduced by equivalent heat stress method, the input-output characteristic of the different internal stress lower pressure sensor of emulation, and it is non-linear to calculate it.The present invention has the advantage that method is simple, accuracy is high, it is possible to quickly weigh nonlinearity erron and the sensitivity of pressure transducer, designs with the optimization of guiding pressure sensor performance.
Description
Technical field
The present invention relates to a kind of internal stress influence lower pressure sensor nonlinear discriminant method.
Background technology
Piezoresistive pressure sensor makes its sensing element be miniaturized due to the development of micromachining technology, production lot, low one-tenth
This change, establishes its leading position in field of pressure measurement, closes potentiometer type, force balance type, power transformation sense than traditional film
Formula, becomes condenser type, and on metal strain chip and semiconductor strain chip sensor technology, advanced person is much, has highly sensitive, sound
Answer that speed is fast, the more high and low power consumption of good reliability, precision, be prone to miniaturization and the series of advantages such as integrated, at industry, vapour
The field such as car and medical science has a wide range of applications.
Generally, the processing mode of piezoresistive pressure sensor is divided into bulk silicon micromachining and surface micromachined.And table
The pressure sensor chip of face micromachined is mutually compatible with IC technique because of its technique, can be by circuit for signal conditioning, microprocessor
Etc. integrating, and can other test functions be integrated by same technique, such as acceleration test, temperature is surveyed
Examinations etc. so that chip multifunction, more meet the demand for development testing system integration, miniaturization and cost degradation at present.
The pressure sensor chip of surface micromachined would generally be owing to the structural agent of thin film itself be with scarce in preparation process
Falling into, or between substrate with diaphragm, thermal coefficient of expansion does not mates and introduces initial internal stress, the initial internal stress of thin film would generally affect pressure
Certainty of measurement during force transducer work, has document proposition internal stress at present and can reduce the sensitivity of sensor；Additionally, it is electric
Initial internal stress on resistance passivation layer also can affect the output nonlinear of sensor.
The mechanical property of thin film is had a great impact by the existence of stress in thin films, when stress is excessive, may result in film separation,
Be full of cracks, makes membrane structure be destroyed and causes losing efficacy.Additionally, stress in thin films also to the machinery of micro-machined sensors,
The performances such as electricity have a great impact.Verify the generation root of stress in thin films, and control its size, it is thus achieved that more small, more line
Property and highly sensitive sensing element structure；Solve that lower range high sensitivity and the ultra-thin big deflection of beam film cause non-linear between the two
Contradiction, it is thus achieved that the ultra micro range pressure sensor that linear precision is higher.Therefore the present invention provides a kind of internal stress influence downforce
Sensor nonlinear method of discrimination.
Summary of the invention
For Shortcomings in prior art, the invention provides a kind of internal stress influence lower pressure sensor nonlinear discriminant method.
The present invention realizes above-mentioned technical purpose by techniques below means.
A kind of internal stress influence lower pressure sensor nonlinear discriminant method, it is characterised in that comprise the following steps:
(1) Young's modulus of pressure sensor chip structure sheaf thin film is measured；
(2) the initial inner-stress value of pressure sensor chip structure sheaf thin film is measured；
(3) pressure sensor chip structural model is created: utilize ANSYS software to use Solid 186 cell type, complete several
After what modeling and definition material parameter, model is carried out stress and strain model；
(4) apply displacement constraint, described model periphery be fixed, limit the degree of freedom in tri-directions of X, Y, Z,
Apply impressed pressure, solve stress, amount of deflection distribution, obtain equivalent stress cloud atlas；
(5) the initial internal stress of thin film is introduced by equivalent heat stress method, the input of the different internal stress lower pressure sensor of emulation-defeated
Go out characteristic, and it is non-linear to calculate it.
Further, described step (1) use TriboIndenter nano indentation system measure.
Further, described step (2) use FLX-2320 membrane stress instrument measure the difference of described thin film silicon matrix amount of bow
Value, calculates the initial internal stress trying to achieve described thin film.
Further, described step (3) carries out stress and strain model to model in Mesh Tool in Global Size
SIZE option is set to 5e-6。
Further, described pressure sensor chip structure sheaf thin film is low stress nitride silicon thin film, the material defined in step (3)
Material parameter is: Young's modulus E=2.24e11Pa, Poisson's ratio υ=0.23, thermalexpansioncoefficientα=2.1e-6/k。
The non-linear important indicator being to weigh pressure transducer performance, when the use range of pressure transducer is little, needs to solve
Contradiction between the nonlinearity erron that the output of lower range high sensitivity and ultra-thin beam film large deflection cause.
By reducing the thickness of pressure sensor chip structure sheaf thin film, improve the sensitivity of pressure transducer, but, when logical
When the mode of excessive erosion reduces the thickness of pressure sensor chip structure sheaf thin film, the midplane at described thin film can stretch
Deformation, i.e. " balloon effect " so that the nonlinearity erron of pressure transducer substantially becomes big, thus reduce and linear precision is required relatively
The production qualification rate of high micro-pressure sensor.
Internal stress influence lower pressure sensor nonlinear discriminant method of the present invention, uses ANSYS software, by limited
Meta-analysis, sets up the FEM (finite element) model of pressure sensor chip structure, the different initial internal stress lower pressure sensor of analog simulation
Input-output characteristic, judges the non-linear of pressure transducer.There is the advantage that method is simple, accuracy is high, it is possible to quickly weigh
The nonlinearity erron of piezometric force transducer and sensitivity, design with the optimization of guiding pressure sensor performance.
Accompanying drawing explanation
The loading of nano impress when Fig. 1 is to measure low stress nitride silicon thin film Young's modulus and discharge time.
Load and the relation of compression distance when Fig. 2 is to measure low stress nitride silicon thin film Young's modulus.
Described model when Fig. 3 is the face load being perpendicular to described mould plate face sized by the pressure loading applied for 60kPa and position
Amount of deflection, Stress Map distribution.
Fig. 4 is the Input output Relationship figure of the described pressure transducer with different initial internal stress.
Fig. 5 is pressure transducer experiment (scatterplot) and the Nonlinear Characteristic Curve of emulation (solid line).
Fig. 6 is the pressure transducer non-linear and sensitivity curve of output under different stress in thin films.
Detailed description of the invention
Below in conjunction with the accompanying drawings and specific embodiment the present invention is further illustrated, but protection scope of the present invention is not limited to
This.
As a example by using low stress nitride silicon thin film as pressure sensor structure layer film, describe internal stress shadow of the present invention in detail
Ring lower absolute pressure transducer nonlinear discriminant method.
First, using low-pressure chemical vapor deposition (LPCVD) method, regulation dichlorosilane and the flow-rate ratio of ammonia, at 850 DEG C
Growth temperature under, deposition low stress nitride silicon thin film (be called for short LS SiN), and using this low stress nitride silicon thin film as pressure
The structure sheaf thin film of sensor chip.
Use Hysitron company TriboIndenter nano indentation system, by continuous control and record add unloading load and
Displacement data, obtains the Young's modulus of LS SiN.Concrete, load loads as it is shown in figure 1, load and compression distance such as Fig. 2
Shown in.Young's modulus is solved according to below equation:
Therefore:
In formula, E and ν is respectively elastic modelling quantity and the Poisson's ratio of sample, EiAnd νiIt is respectively elastic modelling quantity and the Poisson's ratio of pressure head, respectively
It is comprehensive Young's modulus for 1141GPa and 0.07, Er.
Use FLX-2320 membrane stress instrument to measure the difference of LS SiN silicon substrate amount of bow, calculate and try to achieve described LS SiN's
Initial internal stress.
Then, utilize ANSYS software to use Solid186 cell type, create pressure sensor chip structural model, complete
After Geometric Modeling and definition material parameter, model is carried out stress and strain model.Concrete, the physical dimension setting up model is 360 μm
× 80 μm, thickness is 1.2 μm；For LS SiN, the material parameter set is as Young's modulus E=2.24e11Pa, Poisson's ratio
υ=0.23, thermalexpansioncoefficientα=2.1e-6/k.During it is preferred that model is carried out stress and strain model, it is Global in Mesh Tool
SIZE option in Size is set to 5e-6.Theoretical model after stress and strain model includes 7779 unit, 16084 nodes, owns
Unit be all 20 node Solid186 unit.
To described pressure sensor chip structural model apply displacement constraint, model periphery is fixed, limit X, Y,
The degree of freedom in tri-directions of Z, applies impressed pressure, solves stress, amount of deflection distribution, obtains equivalent stress cloud atlas.
When being perpendicular to the face load in described mould plate face sized by the pressure loading applied for 60kPa and position, described model
Amount of deflection, Stress Map are as shown in Figure 3.Shown in ANSYS displacement cloud atlas such as Fig. 3 (a) under 60kPa impressed pressure,
Big displacement occurs in the center position of described model, and size is 0.185 μm, and the closer to marginal position, displacement is the least, until
It is reduced to 0 to boundary.ANSYS longitudinal stress under 60kPa impressed pressure and lateral stress cloud atlas respectively as Fig. 4 (b),
Shown in 3 (c), maximum stress occurs in the long limit boundary of described model.The ANSYS of described model under 60kPa impressed pressure
Shown in equivalent stress cloud atlas such as Fig. 3 (d).
Finally, introduce the initial internal stress of thin film by equivalent heat stress method, the input of the different internal stress lower pressure sensor of emulation-
Output characteristics, and it is non-linear to calculate it.Concrete, according to the surface stress distribution under the initial internal stress of difference of the described model,
Calculating the output voltage of Wheatstone bridge, when impressed pressure gets 500kPa, the internal stress of LS SiN is respectively 0, and 50,
When 135 and 350MPa, the input-output characteristic curve of described pressure transducer is as shown in Figure 4, and output nonlinear is respectively
16.03%FSO, 10.87%FSO, 6.42%FSO, 3.59%FSO, i.e. initial internal stress is the biggest, and nonlinearity erron is the least.
Along with the increase of initial internal stress, Wheatstone bridge output voltage also decreases.Pressure transducer is shown in order to more specific
The variation tendency of output nonlinear, initial internal stress is respectively 0,50,135, and 350MPa, particular measurement pressure piUnder
Nonlinearity erron, as it is shown in figure 5, in Fig. 5, scatterplot represents the experimental result of Nonlinear Characteristic Curve, in solid line represents difference
Simulation result under stress, scatterplot has distribution in the both sides of solid line.When initial internal stress is tension, pressure transducer
Non-linear is just.Along with the increase of initial internal stress, nonlinearity erron reduces, and input-output characteristic curve is not further referring to centre
Axial symmetry.
Additionally, the sensitivity of pressure transducer is also had a certain impact by the initial internal stress of described thin film.Press under different internal stress
Non-linear and the sensitivity of force transducer, as shown in Figure 6, it will be appreciated from fig. 6 that reduce initial internal stress, it is possible to increase pressure passes
The sensitivity of sensor, but nonlinearity erron can be caused to increase；Improve internal stress, although can reduce nonlinearity erron, but simultaneously
Also reduce sensitivity.
The internal stress of described thin film is inevitable during substrate, and internal stress size is generally warm with the thickness of thin film, annealing
Degree and fabrication process condition are relevant, therefore, by the size of conservative control stress in thin films, weigh the non-linear of pressure transducer
And sensitivity, to realize the optimization of pressure transducer performance.Method provided by the present invention can quickly differentiate internal stress shadow
Ringing lower absolute pressure transducer non-linear, the optimization to pressure transducer performance designs offer guidance.
Described embodiment be the present invention preferred embodiment, but the present invention is not limited to above-mentioned embodiment, without departing substantially from this
In the case of the flesh and blood of invention, any conspicuously improved, replacement or modification that those skilled in the art can make are equal
Belong to protection scope of the present invention.
Claims (5)
1. an internal stress influence lower pressure sensor nonlinear discriminant method, it is characterised in that comprise the following steps:
(1) Young's modulus of pressure sensor chip structure sheaf thin film is measured；
(2) the initial inner-stress value of pressure sensor chip structure sheaf thin film is measured；
(3) pressure sensor chip structural model is created: utilize ANSYS software to use Solid186 cell type, complete several
After what modeling and definition material parameter, model is carried out stress and strain model；
(4) apply displacement constraint, model periphery is fixed, limit the degree of freedom in tri-directions of X, Y, Z, execute
Add impressed pressure, solve stress, amount of deflection distribution, obtain equivalent stress cloud atlas；
(5) the initial internal stress of thin film is introduced by equivalent heat stress method, the input of the different internal stress lower pressure sensor of emulation-defeated
Go out characteristic, and it is non-linear to calculate it.
Pressure transducer nonlinear discriminant method the most according to claim 1, it is characterised in that in described step (1)
TriboIndenter nano indentation system is used to measure.
Pressure transducer nonlinear discriminant method the most according to claim 1, it is characterised in that in described step (2)
Use FLX-2320 membrane stress instrument to measure described thin film silicon matrix amount of bow, calculate the initial internal stress trying to achieve described thin film.
Pressure transducer nonlinear discriminant method the most according to claim 1, it is characterised in that in described step (3)
It is, in Mesh Tool, the SIZE option in Global Size is set to 5e that model carries out stress and strain model-6。
Pressure transducer nonlinear discriminant method the most according to claim 1, it is characterised in that described pressure transducer core
Chip architecture layer film is low stress nitride silicon thin film, and the material parameter defined in step (3) is: Young's modulus E=2.24e11Pa、
Poisson's ratio υ=0.23, thermalexpansioncoefficientα=2.1e-6/k。
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Application publication date: 20150218 Assignee: Wenzhou Huaxin Instrument Co., Ltd. Assignor: Wenzhou University Contract record no.: 2018330000050 Denomination of invention: Method for discriminating nonlinearity of pressure sensors under influence of internal stress Granted publication date: 20170104 License type: Common License Record date: 20180509 |
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Application publication date: 20150218 Assignee: Aikesai Intelligent Technology (Taizhou) Co., Ltd. Assignor: Wenzhou University Contract record no.: 2019330000024 Denomination of invention: Method for discriminating nonlinearity of pressure sensors under influence of internal stress Granted publication date: 20170104 License type: Common License Record date: 20190306 Application publication date: 20150218 Assignee: Zhejiang God energy Polytron Technologies Inc Assignor: Wenzhou University Contract record no.: 2019330000023 Denomination of invention: Method for discriminating nonlinearity of pressure sensors under influence of internal stress Granted publication date: 20170104 License type: Common License Record date: 20190306 Application publication date: 20150218 Assignee: Zhejiang Dresden Pump Industry Co., Ltd. Assignor: Wenzhou University Contract record no.: 2019330000025 Denomination of invention: Method for discriminating nonlinearity of pressure sensors under influence of internal stress Granted publication date: 20170104 License type: Common License Record date: 20190306 |