Deep trench etching combining aluminum thermomigration and electrochemical silicon dissolution

Abstract

A micromachining technique for silicon deep anisotropic etching and isolating porous silicon structures is developed. This original method combines aluminum thermomigration and silicon electrochemical etching. In this way, we have generated high aspect ratio trenches and porous silicon isolating regions as well, through the entire thickness of the wafer. In order to evaluate our method, we performed etching rate measurements varying the current density. A maximum value of 22μm∕min has been already measured. The interest of the method in terms of cost and structures diversity is also justified.