In order to solve the pressure measurement problem in harsh environments

such as high temperature above 200 ℃

a special piezoresistive pressure sensor with the ranges of 0~120 kPa is developed based on the Micro Electro-mechanical System(MEMS) and Separation by Implantation of Oxygen(SIMOX) technology. The piezoresistive pressure sensor chip consists of a silicon substrate

a thin silicon dioxide layer

an optimized boron ion implantation layer photolithographically patterned on a Wheatstone bridge configuration

a stress matching layer with silicon nitride

a Ti-Pt-Au beam lead layer for bonding gold wires

and a cavity fabricated by the wet etching. A special buried silicon dioxide layer with a thickness of 367 nm is fabricated by the SIMOX technology with the oxygen ion dose of 1.4×10

18

/cm

2

and an implantation energy of 200 keV. The buried SiO

2

layer is used to isolate the upper measuring circuit layer from the silicon substrate to avoid the leak-current influence

so the fabricated sensor chip can be used in a high temperature above 200 ℃. In order to improve the stability in the wide temperature range

the temperature compensation methods are studied and carried out

so the Temperature Coefficient of Sensitivity(TCS) and Temperature Coefficient of Offset(TCO) of the compensated sensor are easily obtained to be less than 1×10

-4

/℃·FS. The calibration results show that the developed high temperature pressure sensor has good performances under 200 ℃ for a linearity error of 0.12%FS

a repeatability error of 0.1%FS

a hysteresis error of 0.12%FS

and the sensor’s accuracy of 0.197%FS. which shows it is able to meet the requirements of modern industry

such as oilcans

wind tunnels

mobiles

petrochemical industry

etc

..