Acidic treatment liquid and method of treating copper surfaces

Treatment liquid according to any of the preceding claims, wherein R1 and R2 contain a group mediating the solubility of the microstructure modifying agent in an aqueous solution.

Treatment liquid according to any of the preceding claims, wherein the at least one five-membered heterocyclic compound is selected from the group comprising tetrazole and the derivatives thereof.

Treatment liquid according to any of the preceding claims, wherein the at least one microstructure modifying agent is selected from the group comprising L-cysteine, DL-cysteine, 2-aminoethanethiol, mercaptoacetic acid, 3-mercaptopropionic acid, 2-mercaptoethanesulfonic acid, 3-mercaptopropanesulfonic acid, L-cystine, DL-cystine, D-cystine, bis-(2-aminoethyl) disulfide, dithiodiacetic acid, 3,3′-dithiodipropionic acid, 4,4′-dithiodibutyric acid, 3,3′-dithio-bis-(propanesulfonic acid), thiodiacetic acid, 3,3′-thiodipropionic acid, 3,3′-thio-bis-(propanesulfonic acid), thiourea, thiobenzamide as well as the salts thereof.

Treatment liquid according to any of the preceding claims, wherein at least one an inorganic acid is contained.

Method of treating copper surfaces comprising bringing into contact the copper surfaces with an acidic treatment liquid comprising

• a. hydrogen peroxide and
• b. at least one five-membered heterocyclic compound wherein
• c. additionally at least one microstructure modifying agent is contained, selected from the group comprising organic thioles, organic sulfides, organic disulfides and thioamides.

Copper substrates having roughened surfaces with two structural dimensions, the first one having an average size in the range of from 1 to 10 microns and the second one having an average size in the range of from 50 to 500 nanometers.