Dear colleagues, My friend gived me this email address because he thought it might be a forum site for discussing etching-related issues. Anyway, I like to have a goahead. My problem is to find an etchant for SiO2 which does not substantially etch alumina Al2O3. Is somebody there who happens to know the formula of this sort of etchant. Your suggestion and help would be much appreciated. Cheers. Yagang Li Department of Materials Oxford University Yagang.LI@materials.ox.ac.uk