Midterm Project

授課老師：劉承賢　　老師 Student : G923795 蘇家興

Abstract Piezoresistive Effect Design of Piezoresistive Pressure SensorParameters of Commercial Product

Piezoresistive Effect Variation of resistance caused by stress (1)

Piezoresistance matrix for (1 0 0) crystal (2)

(1) ,

lkklijklij i

(2)

00000

00000

00000

000

000

000

6

5

4

3

2

1

44

44

44

111212

121112

121211

6

5

4

3

2

1

Piezoresistive Effect

Change in resistance (3) (for diffused resistors with longitudinal stress and transvers

e stress)

Piezoresistive Coefficient (4)

(3) ttllR

R (4)

22

2244441211

44441211

t

l

Piezoresistive Effect

From the equation (2)(3)(4) , the resistance equation(5) of <1 0 0> piezoresistor

(5) )(244

tlR

R

Design of Piezoresistive Pressure Sensor

Piezoresisitive Sensor

Bulk Piezoresistive Sensor Commercially useful

Surface Mounted Piezoresistive Sensor Experimental

Design of Piezoresistive Pressure Sensor

Design of Piezoresistive Pressure Sensor Bulk Piezoresistive Pr

essure Sensor A thin monocrystalin

e silicon membrane Silicon diaphragm

Substrate Elastic material

Design of Piezoresistive Pressure Sensor

Design of Piezoresistive Pressure Sensor

2

2

44

44

t

l

ttllR

R

)(244

tlR

R

Design of Piezoresistive Pressure Sensor

biasRR

out

inout

VR

RV

VRRR

RRV

RR

RR

VRR

R

RR

RV

21

021

21

242

131

21

2

43

3

2

RR

RR

applied is load If

)(

situation load No

Design of Piezoresistive Pressure Sensor Differential Voltage Output of Pressure

Sensor (6) Sensitivity of pressure sensor (7)

(7) 11

RP

R

VP

VS

bias

(6)VR

V bias

R

Design of Piezoresistive Pressure Sensor Operation Parameters

of Pressure sensor Symbol Typical Unit

P 0~50 kPa

Voffset 10 mv

S 1.5 mv/kPa

Parameter

Pressure Range

Offset Voltage

Pressure Sensitivity

mv 85~10

85505.110(max)

out

offsetout

V

mvkPakPamvmvPSVV

Design of Piezoresistive Pressure Sensor

Parameters of Membrane

Parameter  

Size of the membrane1500*1500*100 um (L*W*

H)

Size of the piezoresistor 350*5*1 um

Spacing between the piezoresistor and the silicon edge 50 um

Parameters of Commercial Product

Parameters of Commercial Product

1kPa=0.145Psi

Parameters of Commercial Product

Reference

Ranjit Singh, Low Lee Ngo, Ho Soon Seng, Frederick Neo Chwee Mok. A Silicon Piezoresistive Pressure Sensor.I

EEE(2002). William P. Eaton, James H. Smith, David J. Monk, Gary

O’Brien, and Todd F. Miller. Comparison of Bulk- and Surface- Micromachined Pressure Sensors. Micromachined Devices and Components, Proc SPIE, Vol 3514, p. 431.

Reference

Motorola Semiconductors H.K. Ltd.; Silicon Harbour Center, No. 2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong.

http://www.allsensors.com http://www.amsys.info

Thank You