Design of 6H-SiC High Temperature Pressure Sensor Chip

Over the last decade, a relatively in-depth research on the different structures and types of the full SiC pressure sensors including the piezoresistive, the capacitive and the optical SiC pressure sensors etc. has been conducted with a view to realizing the pressure measurement in high temperature circumstances. The piezoresistive SiC pressure sensor has gradually become the focus of research due to its simple structure and convenience application. In our research, the piezoresistance strip is designed on the deep-etching sensitive circular diaphragm formed via deep etching. Firstly, the 6H-SiC strain coefficient GF value is compared on the radial direction and the transverse direction by analyzing the circular diaphragm deformation theory. It’s concluded that both in the radial direction, four resistance strips are assigned in the center of circular diaphragm and along the edge respectively, with equal number on these two locations. Better consistency and sensitivity are achieved by this solution. Secondly, the design size of the sensitive circular diaphragm and the pressure resistance strips are determined with the expected work temperature and the target measuring range being taken into consideration. The final layout scheme design of four pressure resistance strips is determined through simulation on the consideration of the thermal stress caused by the AlN packaging.