Volker Dr Graeger

Temperature-independent pressure sensors using polycrystalline silicon strain gauges

Abstract The sheet resistance and piezoresistive effect (k-factor) and their temperature coefficients for LPCVD-polysilicon films are examined as a function of the boron concentration and the averaged grain size. In particular, heavily boron-doped polysilicon strain gauges show a TCR of +0.1%/K and a TCk of −0.1%/K. Using a constant current supply for a Wheatstone bridge, a nearly complete temperature compensation of sensitivity can be realized. We show results of pressure sensors with a temperature deviation of only 0.2%/10K without any external compensation network.