Development of Porous Silicon Microfilters

Abstract

This study develops a one-step anodization separation process (OSS) after examining two step and multi step liftoff procedures in which porous silicon (PS) films lift off from their substrates. This lift-off process provides a means to produce silicon filters, a worthy alternative to alumina filters that cannot withstand high temperatures as well as silicon and whose pore diameter has yet to reach into the order of microns. By electrochemical etching of p-type silicon wafers in a hydrofluoric acid-based solution, microporous filters with pore diameters varying from 1 to 2 microns whose depths range from 3 to 70 micrometers are fabricated. Using wafers with a resistivity of 14-22 Ω-cm, mobile filters with consistent structural qualities can be reproduced.