Reaction Kinetics of Poly-Si Etching in TMAH Solution

Abstract

Tetramethylammonium hydroxide (TMAH) is a metal-free strong alkaline solution which can etch poly-Si. The concentration of dissolved gas as well as the concentration of TMAH affects etching rate of poly-Si. The detailed kinetics of poly-Si etching in TMAH solution is investigated in this study. The effect of water and TMAH concentration on the etching kinetics of poly-Si was investigated by using various concentrations of TMAH solution. It is found that H2O in TMAH solution plays an important role in etching poly-Si. Presence of dissolved CO2 and O2 in TMAH solution tends to inhibit etching of poly-Si. The concentration of dissolved CO2 and O2 in TMAH were reduced by Ar bubbling, thereby the poly-Si etching rate increased.