Silicon pressure sensors have historically been fabricating by bonding a glass wafer to a micro-machined silicon wafer. The sensor may be sealed as an absolute pressure sensor by using planar glass and can then be used for detection of barometric pressure changes.

It has generally been assumed that as long as the glass and silicon are reasonable clean, then the silicon-glass seal is good and the part becomes a reliable, stable sensor. This paper addresses a low-level drift that was identified in such an absolute pressure sensor. A Zero drift in the range of 0.1% FS was detectable under humidity stresses. The stress always caused drift in the same direction, indicating an effective increased pressure in the sealed cavity.

The impact of various cleaning processes in reducing drift are reported. The improved process assure reliable product for applications such as automotive and altimeter applications.