Silicon sub-micron-gap deep trench Pirani vacuum gauge for operation at atmospheric pressure

Abstract

The operation of a bulk micromachined Pirani vacuum gauge at atmospheric pressure is demonstrated. The device is fabricated on a silicon-on-insulator (SOI) wafer with a 5 µm thick device layer by using a one-mask, deep etching process. The 250 nm wide vertical gap fabricated by the deep etching of silicon has made operation at atmospheric pressure possible. The pressure range dependence on the change in the length of the heater and the length of the gap is discussed. Further, the performance dependence on different gaps is measured using 1.5 µm and 5.5 µm wide gaps. Measurement from 4 to 101 300 Pa is performed, and high sensitivity from 1000 to 101 300 Pa is confirmed.