METHOD FOR PROVIDING ORGANIC RESIST ADHESION TO A COPPER OR COPPER ALLOY SURFACE
The present invention relates to a method for increasing the adhesion of organic resist materials on copper or copper alloy surfaces. The copper or copper alloy surface is contacted with an aqueous adhesion promoting solution comprising at least one organic acid, a peroxide compound and optionally one or more substances selected from the group consisting of urea, derivatives thereof and water-soluble polymers.
1 . Method for increasing the adhesion of organic resist materials on a copper or copper alloy surface, the method comprising the steps of
a. providing a substrate having a copper or copper alloy surface,
b. contacting said surface with an aqueous adhesion promoting solution comprising
i. at least one organic acid and
ii. a peroxide compound
wherein the concentration of the at least one organic acid or in case of more than one organic acid the overall concentration of all organic acids ranges from 0.005 to 0.04 mol/l,
and thereby forming a layer of copper oxide phase(s) on top of the copper or copper alloy surface and
c. attaching an organic resist material onto the layer of said copper oxide phase(s).
2 . Method according to claim 1 wherein the at least one organic acid of the adhesion promoting solution is selected from the group consisting of carboxylic acids, hydroxycarboxylic acids, aminocarboxylic acids and sulfonic acids.
3 . Method according to claim 2 wherein the concentration of the sulfonic acid ranges from 0.005 to 0.008 mol/l.
4 . Method according to claim 2 wherein the carboxylic acid is an alkane carboxylic acid.
5 . Method according to claim 2 wherein the aminocarboxylic acid is selected from the group consisting of 6-aminohexanoic acid, glycine and cysteine.
6 . Method according to claim 2 wherein the sulfonic acid is selected from the group consisting of alkane sulfonic acids and aromatic sulfonic acids.
7 . Method according to claim 1 wherein the concentration of the peroxide compound in the aqueous adhesion promoting solution ranges from 0.01 to 2.5 mol/l.
8 . Method according to claim 1 wherein the peroxide compound is hydrogen peroxide.
9 . Method according to claim 1 wherein the aqueous adhesion promoting solution further comprises a water soluble polymer selected from the group consisting of polyethylene glycol, polypropylene glycol and co-polymers of the aforementioned.
10 . Method according to claim 1 wherein the aqueous adhesion promoting solution further comprises urea or a derivative thereof.
11 . Method according to claim 1 wherein the aqueous adhesion promoting solution is essentially free of a N-heterocyclic compound.
12 . Method according to claim 1 wherein the pH value of the aqueous adhesion promoting solution ranges from 1.8 to 5.
13 . Method according to claim 1 wherein the layer of copper oxide phase(s) has a thickness of 5 to 300 nm.
14 . Method according to claim 1 wherein the layer of copper oxide phase(s) has a RSAI value of >50% compared to the underlying copper or copper alloy layer and a R a value of <150 nm as determined by atomic force microscopy.
15 . Method according to claim 1 wherein the aqueous adhesion promoting solution in step b. has a temperature of 20 to 50° C.
16 . Method according to claim 1 wherein the substrate is contacted with the aqueous adhesion promoting solution in step b. for at least 5 s.
17 . Method according to claim 1 wherein the substrate is contacted with the aqueous adhesion promoting solution by spraying.
18 . A layer on top of a copper or copper alloy surface, said layer comprising
copper and oxygen,
having a thickness in the range of 5 to 300 nm,
having a RSAI value of >50% compared to the underlying copper or copper alloy surface and a R a value <150 nm as determined by atomic force microscopy,
wherein said layer is obtained by applying step b. according to claim 1 to a substrate having a copper or copper alloy surface.