Abstract
This paper describes temperature dependence of an output voltage nonlinearity on a silicon diaphragm pressure sensor utilizing the piezoresistance effect for high pressure measurements of a 50MPa span. The diffused gage resistor has temperature dependence of the nonlinearity and it is necessary that the nonlinearity of the pressure sensor fabricated in a pressure transmitter for industrial use is within ±0.2% and an output voltage/supply voltage is above 43mV/V at the same time.
When stresses on the silicon diaphragm are analyzed by a plate theory of fixed periphery of a classical dynamics and a finite element method (FEM), the stresses calculated by the latter shift about 125MPa for compressive side from those by the former. A value of the gage resistor diffused on the silicon diaphragm is calculated by an equation which is expressed quantitatively as a function of the tri-axial stresses by FEM, the high degrees piezoresistance coefficient and its temperature coefficients obtained by our previous experiments. When the calculated results of the nonlinearity are compared with the experimental results, we found that stresses calculation by FEM is more effective than the one by the plate theory of a fixed periphery in order to forecast the experimental results.
We found from the experimental results that there is the gage resistor configuration within ±0.1% of a nonlinearity at a measuring span pressure of 50MPa under temperature range of -40-120°C, and there is also the gage resistor configuration whose temperature dependence of the nonlinearity within 0.02% can be neglected.
