Fabrication of Megasonic-Agitated Module for Improving the Characteristics of Wet Etching

Abstract

The megasonic-agitated module (MAM) has been fabricated for improving the characteristics of wet etching. The characteristics of the MAM were investigated during the wet etching with and without megasonic agitation in this study. The use of the MAM has improved the characteristics of wet etching, such as the etch rate, etch uniformity, and surface roughness. Particularly, the etching uniformity on the entire wafer was less than ±1% in both cases of Si and glass. Generally, the initial root-mean-square roughness (Rrms) of the single-crystal silicon is less than 0.5 nm. Roughnesses of 566 and 66 nm were achieved with magnetic stirring and ultrasonic agitation respectively, by some researchers. In this study, the roughness of the etched Si surface was less than 60 nm. Wet etching of silicon with megasonic agitation can maintain nearly the original surface roughness during etching. The results confirmed that megasonic agitation is an effective way to improve the etching characteristics, such as the etch rate, etch uniformity and surface roughness, and that the developed micromachining system is suitable for the fabrication of devices with complex structures.