Fabrication of thin layer membrane using CMOS process for very low pressure sensor applications

A very low pressure sensor has been proposed to be used in the eye for glaucoma treatment with pressure ranging from 10 mmHg to 75 mmHg. This paper presents process development of thin layer membrane for very low pressure sensor application. The structure of the membrane consists of parallel plate which both top and bottom electrodes were fixed at both sides. Utilizing CMOS compatible process, fabrication of the thin layer membrane involved in three stages; i) hole opening etch, ii) sacrificial intermediate oxide release etch and iii) closing of etch holes. Our work focuses on the characterization of holes opening etch size for the intermediate oxide release. Another study was carried out to understand the behavior of sealing off the hole openings etch. This study involved different deposition technique such as LPCVD, PECVD and combination both of them. The findings from these experiments are presented in this paper.