Deposition and Characterization of Low-Stress Plasma Enhanced Chemical Vapor Deposition of Tetraethoxysilane Oxide for Micro-Electro-Mechanical-Systems Applications

Abstract

Micro-electro-mechanical systems (MEMS) often use insulated suspended microstructures such as cantilever beams, bridges and membranes for supporting the functional active part of devices. Moreover, these structures are themselves functional devices. In this paper we report a comprehensive study of low-stress plasma-enhanced chemical vapor deposition (PECVD) tetraethoxysilane (TEOS) oxide with respect to the relationship of its deposition process parameters with its properties after deposition such as stress, deposition rate and etching rate in buffered oxide etchant (BOE) or N2H4 silicon etchant. The effect of annealing on the oxide stress is also studied. Low-stress, low-temperature oxides which are resistant to N2H4 silicon micromachining etching were obtained and demonstrated in the fabrication of long and thin cantilever beams. The same technology can also be used for the deposition of thick oxides as a sacrificial layer in MEMS applications.