An aqueous etching solution for copper and copper alloy surfaces comprising at least one acid, at least one oxidising agent suitable to oxidise copper, at least one source of halide ions and further at least one polyamide containing at least one polymeric moiety according to formula (I) wherein each a is independently from each other selected from 2 and 3; each b is an integer independently from each other ranging from 5 to 10000; each R 1 is a monovalent residue independently from each other selected from the group consisting of substituted or unsubstituted C1-C8-alkyl groups and a method forits use are provided. Such etching solution is particularly useful for retaining the shape of treated copper and copper alloy lines.