Process characterisation of deep reactive ion etching for microfluidic application

The goal of this paper is to investigate the influence of parameters of the Bosch deep reactive ion etching (DRIE) process on etched surface profile, sidewall profile and etch rate of micrometre silicon features. By investigating these parameters, we found the conditions to obtain smooth sidewall, high etch rate and balance of chemical and physical etching in the DRIE process. In this paper, the silicon surface was covered by a thin silver patterning, created by lift-off, as a hard mask for the DRIE process. The etched samples were characterised by optical microscopy and mechanical profilometry. The results show smooth sidewall of 136 mu m-deep silicon trenches obtained at a high etch rate of 4 mu m/min using 5 sccm C4F8, 8 sccm O-2 and 24 W of bias power.