Fabrication of MEMS Resonators in Thin SOI

TL;DR

This paper presents a rapid fabrication process for MEMS resonators in thin SOI wafers, combining UV-lithography and FIB milling to enable fast prototyping with deep sub-micron gaps suitable for CMOS integration.

Contribution

It introduces a simplified, two-step process using UV-lithography and FIB milling for efficient MEMS resonator fabrication in thin SOI, optimizing for deep sub-micron transduction gaps.

Findings

FIB parameters significantly affect etching quality

The process achieves deep sub-micron trenches efficiently

Compatible with CMOS integration requirements

Abstract

A simple and fast process for micro-electromechanical (MEM) resonators with deep sub-micron transduction gaps in thin SOI is presented in this paper. Thin SOI wafers are important for advanced CMOS technology and thus are evaluated as resonator substrates for future co-integration with CMOS circuitry on a single chip. As the transduction capacitance scales with the resonator thickness, it is important to fabricate deep sub-micron trenches in order to achieve a good capacitive coupling. Through the combination of conventional UV-lithography and focused ion beam (FIB) milling the process needs only two lithography steps, enabling therefore a way for fast prototyping of MEM-resonators. Different FIB parameters and etching parameters are compared in this paper and their effect on the process are reported.