In this paper, it is shown that Silicon-On-Insulator (SOI) wafers with good surface finish and thickness control can be realized using Silicon Fusion Bonding along with an optimized ethylenediamine-pyrocatechol-water (EDP) etching approach. Single crystal diaphragms of 11 μm thickness have been fabricated using these SOI wafers. These diaphragms were tested and found to withstand N2 gas pressures in excess of 260 psi without rupturing.
In this paper, the design and fabrication of polysilicon piezoresistive pressure sensor are presented. The design considerations such as the membrane thickness and the arrangement pattern of polysilicon piezo-resistors on the membrane are discussed with emphasis on the use of SOI approach. The results obtained on the pressure sensors and the temperature coefficient of resistivity of polysilicon resistors are presented. The results presented include the electrical trimming of polysilicon resistors for compensating zero offset voltage in the pressure sensors.