A monocrystalline absolute pressure sensor with a pseudo-MOSFET read-out device for life-science applications

Based on silicon on insulator (SOI) technology, a novel absolute pressure sensor with a pseudo-MOSFET read-out is designed and fabricated, in which a buried silicon dioxide layer in the silicon material is the sacrifice layer for the cavity. The membrane is a monocrystalline silicon top layer which contains nanoholes (120 nm x 2 mu m) created by electron-beam lithography [1]. These nano-holes are used for isotropic etching of the cavity into the buried oxide (BOX). This idea based on the previous work of Lee et al. [2] and Sato et al. [3]. To encapsulate the cavity the holes are sealed by using non-stressed PECVD-nitride. The drain-and source-connections of the pseudo-MOSFET are compounded by evaporation of aluminum on top of the membrane and a backside metallization is attached for the gate connection. The experimental results show that this kind of sensor possesses good static performance, which meet the sophisticated pressure measurement demands of the medical industry.