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A method to electrolessly plate a CoWP alloy on copper in a reproducible manner that is effective for a manufacturable process. In the method, a seed layer of palladium (Pd) is deposited on the copper by an aqueous seeding solution of palladium acetate, acetic acid and chloride. Thereafter, a compl

A method to electrolessly plate a CoWP alloy on copper in a reproducible manner that is effective for a manufacturable process. In the method, a seed layer of palladium (Pd) is deposited on the copper by an aqueous seeding solution of palladium acetate, acetic acid and chloride. Thereafter, a complexing solution is applied to remove any Pd ions which are adsorbed on surfaces other than the copper. Finally, a plating solution of cobalt (Co), tungsten (W) and phosphorous (P) is applied to the copper so as to deposit a layer of CoWP on the Pd seed and copper.

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What is claimed is: 1. A method of electrolessly plating on copper contained in or on a substrate comprising the steps of: applying to the substrate an aqueous seeding solution of palladium acetate, acetic acid, and chloride so as to form a seed layer consisting of palladium on the copper only and

What is claimed is: 1. A method of electrolessly plating on copper contained in or on a substrate comprising the steps of: applying to the substrate an aqueous seeding solution of palladium acetate, acetic acid, and chloride so as to form a seed layer consisting of palladium on the copper only and not on the remainder of the substrate; applying to the substrate a complexing solution to remove palladium ions adsorbed on the substrate; and electrolessly plating the copper with a plating solution comprising cobalt, tungsten and phosphorus so as to deposit a layer of cobalt, tungsten and phosphorus on the palladium seed. 2. The method of claim 1 further comprising the step of precleaning the copper prior to the step of applying to the substrate a seeding solution. 3. The method of claim 2 wherein the step of precleaning comprises heating the substrate at 100째 C. in nitrogen followed by applying an oxalic acid solution to the substrate. 4. The method of claim 2 wherein the step of precleaning comprises applying an oxalic acid solution to the substrate. 5. The method of claim 1 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 5 volume percent acetic acid and 3 to 10 ppm chloride. 6. The method of claim 5 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 7. The method of claim 5 wherein the chloride is hydrochloric acid. 8. The method of claim 1 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 1 volume percent acetic acid and 3 to 10 ppm chloride. 9. The method of claim 8 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 10. The method of claim 8 wherein the chloride is hydrochloric acid. 11. The method of claim 1 wherein the complexing solution comprises a complexing agent selected from the group consisting of sodium citrate and ethylenediamine tetraacetic acid (EDTA). 12. The method of claim 11 wherein the complexing agent is present in the amount of 25 g/l. 13. The method of claim 1 comprising the step of circulating at least the seeding solution through a gas filter to remove unwanted particles. 14. The method of claim 13 wherein the gas filter has an average pore size of 0.006 microns. 15. A method of depositing a seed layer on copper comprising the step of: applying to the copper an aqueous solution of palladium acetate, acetic acid, and a chloride so as to form a palladium seed layer on the copper only. 16. The method of claim 15 further comprising the step of precleaning the copper prior to the step of applying to the copper a seeding solution. 17. The method of claim 16 wherein the step of precleaning comprises heating the copper at 100째 C. in nitrogen followed by applying an oxalic acid solution to the copper. 18. The method of claim 16 wherein the step of precleaning comprises applying an oxalic acid solution to the copper. 19. The method of claim 15 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 5 volume percent acetic acid and 3 to 10 ppm chloride. 20. The method of claim 19 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 21. The method of claim 19 wherein the chloride is hydrochloric acid. 22. The method of claim 15 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 1 volume percent acetic acid and 3 to 10 ppm chloride. 23. The method of claim 22 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 24. The method of claim 22 wherein the chloride is hydrochloric acid. 25. The method of claim 15 comprising the step of circulating the seeding solution through a gas filter to remove unwanted particles. 26. The method of claim 25 wherein the gas filter has an average pore size of 0.006 microns. 27. A method of electrolessly plating on copper contained in or on a semiconductor wafer comprising the steps of: providing a semiconductor wafer having copper areas and non-copper areas; applying to the semiconductor wafer an aqueous solution of palladium acetate, acetic acid, and chloride so as to form a palladium seed layer on the copper areas only and not on the non-copper areas; applying to the semiconductor wafer a complexing solution to remove palladium ions adsorbed on the non-copper areas; and electrolessly plating the copper with a plating solution comprising cobalt, tungsten and phosphorus so as to deposit a layer of cobalt, tungsten and phosphorus on the palladium seed. 28. The method of claim 27 further comprising the step of precleaning the copper prior to the step of applying to the semiconductor wafer a seeding solution. 29. The method of claim 28 wherein the step of precleaning comprises heating the semiconductor wafer at 100째 C. in nitrogen followed by applying an oxalic acid solution to the semiconductor wafer. 30. The method of claim 28 wherein the step of precleaning comprises applying an oxalic acid solution to the semiconductor wafer. 31. The method of claim 27 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 5 volume percent acetic acid and 3 to 10 ppm chloride. 32. The method of claim 31 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 33. The method of claim 31 wherein the chloride is hydrochloric acid. 34. The method of claim 27 wherein the solution of palladium acetate, acetic acid, and chloride comprises 0.01 g/l palladium acetate, 0.25 to 1 volume percent acetic acid and 3 to 10 ppm chloride. 35. The method of claim 34 wherein the chloride is selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and palladium chloride. 36. The method of claim 34 wherein the chloride is hydrochloric acid. 37. The method of claim 27 wherein the complexing solution comprises a complexing agent selected from the group consisting of sodium citrate and ethylenediamine tetraacetic acid (EDTA). 38. The method of claim 37 wherein the complexing agent is present in the amount of 25 g/l. 39. The method of claim 27 comprising the step of circulating at least the seeding solution through a gas filter to remove unwanted particles. 40. The method of claim 39 wherein the gas filter has an average pore size of 0.006 microns. 41. The method of claim 27 wherein the copper comprises copper interconnect wiring.