A doubly anchored surface micromachined Pirani gauge for vacuum package characterization

Abstract

This paper presents a surface micromachined Pirani gauge for measuring vacuum pressure inside sealed micro cavities. This thin gap (800nm) SiO/sub 2//Si/sub 3/N/sub 4//SiO/sub 2/ gauge can measure absolute pressure from atmospheric to less than 1mTorr without sophisticated interface electronics by using a reliable software calibration technique. This allows the sensor to be integrated with common vacuum packaging technologies to measure leak rates as low as 10/sup -17/cm/sup 3//s. This represents a 5 order of magnitude improvement over traditional helium leak testing with a substantially reduced cost.