An RIE process for submicron, silicon electromechanical structures

Abstract

A reactive ion etching (RIE) process was used for the fabrication of submicron, single-crystal silicon (SCS) mechanical structures. The process gives excellent control of lateral dimensions (<0.8 mu m) with large vertical depth (4 mu m). The etch rate is independent of crystal orientation; thus, the process can produce complex SCS structures. The released (freely suspended) submicron. SCS mechanical structures are produced using silicon RIE. Anisotropic silicon RIE is used to form unreleased SCS structures from a silicon substrate with vertical sidewall profiles. Isotropic silicon RIE is used to release the SCS structures by etching silicon underneath the SCS structures. Self-aligned silicon dioxide is used for masking the top and sidewalls of the SCS structures and for electrical insulation. The process incorporates the formation of side-drive capacitor structures using aluminum electrodes to induce the driving force on the SCS mechanical structures. A compatible 4- mu m step coverage aluminum metallization process using aluminum sputter deposition and isotropic RIE complements the basic RIE process. The two integrated processes offer unique materials and processing technologies for micromechanics.<>