A new contactless electrochemical etch-stop based on a gold/silicon/TMAH galvanic cell

Fabrication of micromechanical structures with a reproducible thickness is usually accomplished by electrochemically controlled etching. This method requires an external contact to the n-type silicon to be passivated. The contact is usually accomplished by a wafer holder, which may introduce stress into the wafer and complicate batch fabrication. A new technique based on a gold/silicon/TMAH galvanic cell is presented. The passivation potential and current are generated internally, eliminating the need for external contacts and making the technique more suitable for batch fabrication. The theory of operation, experimental results and an application of the technique are presented in this paper. (C) 1998 Elsevier Science S.A. All rights reserved.