# Optimization Method for the Synergistic Control of DRIE Process Parameters on Sidewall Steepness and Aspect Ratio

## TL;DR

This paper presents a method to optimize Deep Reactive Ion Etching parameters to improve precision in silicon micromachining.

## Contribution

A novel optimization method for DRIE process parameters to enhance sidewall steepness and aspect ratio control is introduced.

## Key findings

- Dynamic adjustment of bottom RF power significantly affects sidewall angle precision.
- Combining incremental bottom RF power adjustment overcomes depth limitations but causes aperture dimension variation.
- Optimizing the passivation-to-etch time ratio effectively controls etch morphology characteristics.

## Abstract

Deep Reactive Ion Etching (DRIE), as a key process in silicon micromachining, remains constrained in high-precision applications by sidewall angle deviation and aspect ratio limitations. This study systematically investigates the mapping relationship between process parameters and etching morphology, focusing on the following aspects: the influence mechanism of C4F8 passivation time and bottom RF power on sidewall perpendicularity; and the effect patterns of etch cycle count, single-step time, and bottom RF power on aspect ratio and top–bottom line width (CD) difference. The findings reveal that dynamic adjustment of bottom RF power significantly influences sidewall angle: incremental adjustment tends to cause sharp angles (decreased angular precision), while decremental adjustment tends to form obtuse angles. Simply increasing the cycle count leads to a bottleneck in etch depth growth. Combining incremental bottom RF power adjustment can overcome depth limitations but induces axial variation in aperture dimensions. Optimizing the passivation-to-etch time ratio effectively controls etch morphology characteristics. This study achieved an etch depth of 112.2 μm for a 5 μm wide trench with an overall aperture size difference of 0.279 μm, providing a theoretical basis and practical guidance for parameter optimization in DRIE processes for high-precision silicon structure fabrication.