Hello, The researchers at VTT, Finland, have done some work on using Al2O3 as a masking layer for DRIE, follow the link below: http://www.vtt.fi/vtt_search.jsp?target=julk&form=lse&search=(cn%3D23787%20OR%20 au%3DPuurunen%2C+Riikka) Recently, they also had a paper at Eurosensors 2008, Dresden, Germany, titled: FIB Direct Write of ALD Al2O3 Mask for Silicon DRIE. Vijay DIMES, TU Delft, NL