Development of high-temperature piezoresistive pressure sensor based silicon on insulator

Abstract

Silicon on insulator (SOI) substrate was prepared using ion implantation of oxygen technique. For piezoresistive detection, the top layer (0.2 &mgr;m thick) silicon was used as an active material with the excellent single crystal silicon properties. The structure of the pressure sensor chip was simulated and analyzed using the finite element method. The pressure gauge chips were manufactured using MEMS techniques. The Si3N4 films were applied for the mask, and the silicon cups were manufactured using KOH anisotropic wet etching process. Cr/Ni/Au multi-layers metal electrodes were applied to guarantee the reliable work at high temperature. The manufactured sensors were measured with an applied pressure of 0 to 6.0MPa at 300 . The test results showed that the sensitivity was approximately 30mV/ (mA MPa), the non-linearity was less than 1.5&perthou; FS, the repetition was less than 0.9&perthou; FS. The research showed that the SOI piezoresistive pressure sensor could reliably work at a high temperature.