A novel process for the preparation of thick porous silicon layers with very high porosity

A novel process for the preparation of thick porous silicon layers having very high porosities is proposed. Starting with thick layers of intermediate porosity the porosity is further increased in an additional step. This is done by means of controlled partial oxidation of the silicon skeleton followed by selective removal of the oxide film in an HF vapor phase etching process. Due to this, porosities beyond 90% are accessible since any further liquid phase contact is avoided and therefore no additional drying steps are necessary. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)