A single crystal silicon micro-Pirani vacuum gauge with high aspect ratio structure

This paper presents a very simple micro-Pirani vacuum gauge made of single crystal silicon. It was fabricated by conventional bulk micromachining technology with only three masks. The gauge has 80 μm thick bulk silicon as structure layer and dual heat sinks, which is very robust with very little internal stress and also provide large heat transfer area. Highly phosphorus ion doping at bottom of the anchors forms ohmic contact with Cr/Au leads. I–V curve shows good linear resistance characteristic of the single crystal silicon heater. The dynamic range of the Pirani vacuum gauge is 1–1000 Pa, and the average sensitivity in the dynamic range is 117 K/W/Pa. With an uncertainty of 1%, the resolution of the gauge is 12 Pa at 1000 Pa and 0.2 Pa at 4 Pa.