A THERMAL-CONDUCTIVITY MICROSTRUCTURAL PRESSURE SENSOR FABRICATED IN STANDARD COMPLEMENTARY METAL-OXIDE SEMICONDUCTOR

We have investigated polysilicon-based microstructural thermal conductivity pressure sensors fabricated in complementary metal-oxide-semiconductor technology and operated as a Pirani gauge. The thermally isolated polysilicon resistor showed a 2% change over the pressure range 0.01-100 Torr when the device was operated with a constant current of 200-mu-A. Larger changes were observed at higher currents. The device was tested in SF6, N2, and He, and was most sensitive in He and least sensitive in SF6. Heat losses were calculated to be mainly due to heat conduction through the support arms, especially at low pressures, with heat conduction through the gas increasing to approximately 37% at 1 atm.