Micro-electro-mechanical systems fast fabrication by selective thick polysilicon growth in epitaxial reactor

Abstract

A thick layer selective polysilicon growth technique has been developed for micro-electro-mechanical systems (MEMS) fabrication. It allows fast MEMS fabrication without using silicon on insulator wafers or deep ICPRIE etching. The fabrication technique is based on two main steps: a first seed layer of polysilicon is deposited and patterned; the second step consists in the selective growth of this layer in an epitaxial reactor. The first part of this work is devoted to the optimisation of growth parameters. Afterwards, this technique is applied for fabrication of different kinds of actuators, involving films several microns thick with good mechanical properties such as a low mechanical stress and a low roughness of the polysilicon film surface. Furthermore, thermal actuator prototypes were fabricated by using this technique;showing good mechanical properties and high reliability.