Reduced etch lag and high aspect ratios by deep reactive ion etching (DRIE)

TL;DR

This paper presents an optimized deep reactive ion etching (DRIE) process that significantly reduces etch lag and enables the fabrication of high aspect ratio structures with improved stability for MEMS and microfluidic applications.

Contribution

The authors introduce an optimized Bosch process that reduces etch lag below 1.5% and a three-step process for fabricating thick, stable microstructures with high aspect ratios.

Findings

Etch lag reduced to below 1.5%.

Achieved 6 micrometre thick structures at 180 micrometre depth.

Maintained structural stability during deep etching.

Abstract

Deep reactive ion etching (DRIE) with the Bosch process is one of the key procedures used to manufacture micron-sized structures for MEMS and microfluidic applications in silicon and, hence, of increasing importance for miniaturization in biomedical research. While guaranteeing high aspect ratio structures and providing high design flexibility, the etching procedure suffers from reactive ion etching lag and often relies on complex oxide masks to enable deep etching. In this work, we introduce an optimized Bosch process that reduces the etch lag to below 1.5 %. Furthermore, we improved a three-step Bosch process, allowing the fabrication of structures with 6 micrometre thickness at depths up to 180 micrometre while maintaining their stability.