The Key Technologies of SOI Micro-Accelerometer Front Release Process

Abstract

In order to develop the SOI micro-accelerometer front release process, this paper discusses in details the key technologies of the process. There are three problems need to be resolved: the corrosion of the electrode, the corrosion rate of the buried silicon dioxide layer as well as the anti-adhesion of the micro-structure. The corrosion characteristic of the electrode is studied, and a metal electrode of high ability of anti-HF acid corrosion is designed, after release of the micro-structure, the electrode does not fall off. The corrosion property of the buried silicon dioxide is studied, and the corrosion rate is exactly known for 2um and 5um thick buried silicon dioxide layer. Based on this, the buried silicon dioxide layer etching time can be controlled, preventing over-etching of the oxide layer. The adhesion of comb fingers and the mass with the substrate is settled at last. By electron microscopy tests, found that the process can get a good micro-structure surface, with smaller footing effects. By test, the sensitivity of the accelerometer is about 144.5mv/g.