Composition, its use and a process for selectively etching silicon-germanium layers

Abstract

by weight of an SiOx protecting agent of formula O1 or derivatives thereof obtainable by condensation of the compounds of formula O1; and (e) water; wherein RO1 is a group or its hydrolysis products; RO2, RO3 are independently selected from H or C1 to C6 alkyl which may be unsubstituted or substituted by -NRO21RO22 or -ORO21; RO4 is selected from H, C1 to C6 alkyl or C1 to C6 alkoxy, which alkyl and alkoxy may be unsubstituted or substituted by -NRO21RO22 or -ORO21; RO11 is selected from H, and a C1 to C6 alkyl, preferably H; XO11 is a divalent group selected from a C1 to C6 alkanediyl; XO12 is a divalent group selected from a C1 to C6 alkanediyl; RO21, RO22 are independently selected from H, methyl, ethyl, propyl or butyl.