Patent ID: 6547973
Filing Date: 2003-04-15
Classification: G01F,G01L

Abstract:
A method for fabricating a suspended structure comprising a layer of membrane material over a substrate, said suspended structure overlying a cavity in said substrate, said method comprising the steps of:generating a sacrificial layer comprising a first material that will remain bonded to said substrate at a temperature greater than 450Â° C.; depositing said layer of membrane material over said sacrificial layer, said membrane material comprising a second material different from said first material; opening at least one via in said layer of membrane material thereby exposing said sacrificial layer; applying a first etchant to said sacrificial layer through said via to remove part of said sacrificial layer and leave a portion of said sacrificial layer to provide an etch cavity having a periphery bounded by said remaining portion of said sacrificial layer, said first etchant being chosen such that said first etchant removes said first material more rapidly than said second material; and introducing a second etchant into said etch cavity, said second etchant being chosen such that said second etchant removes said substrate more rapidly than said second material.