A new wide-dimensional freestanding microstructure fabrication technology using laterally formed porous silicon as a sacrificial layer

Abstract

A new fabrication method for wide-dimensional freestanding microstructures has been developed. The technology uses porous silicon (PS) as a sacrificial layer. It is laterally formed along the p + layer in the n/p + /p - structure. This is because the current flows laterally through p + layer underneath n layer in the p - substrate. As a result, the PS formation rate in the lateral direction is about two orders of magnitude higher than that in the vertical direction. Thus, the width of the microstructure can be enlarged up to several millimeters. And the gap distance between microstructure and substrate can be controlled by the depths of boron and phosphorus diffusion. Various microstructures such as cantilever and discs have been demonstrated. (C) 2000 Elsevier Science S.A. All rights reserved.