Method of enhancing copper electroplating
Crystal plane orientation enrichment compounds are applied to copper to modify copper grain orientation distribution to the favorable crystal plain orientation to enhance copper electroplating. Electroplating copper on the modified copper enables faster and selective electroplating.
1. A method comprising:
a) providing a substrate comprising copper;
b) selectively applying a composition to the copper of the substrate to increase exposed copper grains having crystal plane (111) orientations, wherein the composition consists of water, a crystal plane (111) orientation enrichment compound, optionally a pH adjusting agent, an oxidizing agent and optionally a surfactant;
c) electroplating copper on the copper of the substrate having increased exposed copper grains having crystal plane (111) orientations and field copper of the substrate with a copper electroplating bath, wherein copper electroplated on the copper treated with the composition electroplates at a faster rate than copper electroplated on the field copper; and
d) anisotropic etching the copper plated on the copper of the substrate having increased exposed copper grains having crystal plane (111) orientations and simultaneously anisotropic etching the field copper, wherein the field copper is etched at a faster rate than the copper plated on the copper of the substrate having increased exposed copper grains having crystal plane (111) orientations.
2. The method of claim 1 , the crystal plane (111) orientation compound is a quaternary amine.
3. The method of claim 2 , wherein the quaternary amine has the formula:
wherein R 1 -R 4 are independently chosen from hydrogen, C 1 -C 4 alkyl and benzyl with the proviso that up to three of R 1 -R 4 can be hydrogen at the same instance.
4. The method of claim 1 , wherein the oxidizing agent is a metal ion selected from the group consisting of copper (II), cerium (IV), titanium (IV), iron (III), manganese (IV), manganese (VI), manganese (VII), vanadium (III), vanadium (V), nickel (II), nickel (IV), cobalt (III), silver (I), molybdenum (IV), gold (I), palladium (II), platinum (II), iridium (I), germanium (II), bismuth (III), and mixtures thereof.
5. The method of claim 4 , wherein the metal ion is copper (II) at a concentration of 1 ppm or greater.
6. The method of claim 1 , where the copper electroplating bath comprises one or more sources of copper ions, a suppressor, an accelerator and optionally a leveler.
7. The method of claim 6 , wherein the copper electroplating bath further comprises the leveler.
8. The method of claim 7 , where a concentration of the accelerator is greater than the concentration of the leveler.
9. The method of claim 8 , wherein a ratio of the concentration of the accelerator to the concentration of the leveler is 5:1 or greater.
10. The method of claim 6 , wherein the suppressor has the formula:
wherein a molecular weight ranges from 1000-10000 g/mol and variables x, x′, x″, x′″, y, y′, y″ and y′″ are integers greater than or equal to 1 to provide the molecular weight range of 1000-10,000 g/mol.
11. The method of claim 6 , wherein the suppressor has the formula:
wherein a molecular weight ranges from 1000-10000 g/mol and variables x, x′, x″, x′″, y, y′, y″ and y′″ are integers greater than or equal to 1 to provide the molecular weight range of 1000-10,000 g/mol.
12. The method of claim 1 , wherein the oxidizing agent is a compound selected from the group consisting of hydrogen peroxide, monopersulfates, iodates, chlorates, magnesium perthalate, peracetic acid, persulfate, bromates, perbromate, peracetic acid, periodate, halogens, hypochlorites, nitrates, nitric acid, benzoquinone, ferrocene, derivatives of ferrocene, and mixtures thereof.