Formation of confined macroporous silicon membranes on pre‐defined areas on the Si substrate

Abstract In this work we investigated the formation of confined macroporous silicon membranes on pre‐defined areas on the silicon substrate. Two different cases were considered: a) membranes supported by the silicon substrate and b) membranes suspended over a cavity on Si. The confined areas were defined lithographically and porous silicon formation took place at mask openings. The main difficulty to overcome was to avoid trenching and silicon over‐etching at mask borders, related with the masking technology used. An appropriate masking technology was developed and used to fabricate a) single macroporous and b) bilayers of macroporous over mesoporous silicon. In the second case, by selectively removing the mesoporous layer, suspended confined macroporous silicon membranes over a cavity on the silicon substrate were fabricated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)