Fabrication of crystalline membranes oriented in the (111) plane in a (100) silicon wafer

Abstract

Anisotropic wet etching on the front and backside of a (100) silicon wafer is applied to fabricate free standing crystalline membranes oriented in the (111) plane. The effective area of the membranes is in the order of several tenths of a millimeter, whereas thickness ranges from several hundreds of microns down to less than a micron. The fabrication process requires two masks and a wet etch. Cantilevers with (111) orientation were milled from the membranes by means of a Focused Ion Beam. We propose the application of (111) oriented silicon membranes as filtration elements in a microfluidic system. Cantilevers oriented in {111} planes can be applied as (bio-) chemical sensor structures that can be integrated in the medium channel.