Patent ID: 6890452

Claim:
An aqueous etch solution comprising: a) an acid, and b) a surfactant of the formula: R f —Q—R 1 —SO 3 − M + wherein R f is a C 1 to C 12 perfluoroalkyl group, R 1 is an alkylene of the formula —C n H 2n (CHOH) o C m H 2m —, wherein n and m are independently 1 to 6, and o is 0 or 1, and is optionally substituted by a catenary oxygen or nitrogen group; M + is a cation; and Q is —O—, or —SO 2 NR 2 —, wherein R 2 is an H—, alkyl, aryl, hydroxyalkyl, aminoalkyl, or sulfonatoalkyl group, optionally containing one or more catenary oxygen or nitrogen heteroatoms.