Manufacture of electroless cobalt deposition compositions for microelectronics applications
View Patent ↗A method of preparing an aqueous electroless deposition composition for electrolessly depositing Co or a Co alloy onto a substrate in manufacture of microelectronic devices by treating water or an aqueous electroless deposition composition with a deoxygenating treatment to reduce the oxygen concentration.
1. A method of preparing an aqueous electroless deposition composition for electrolessly depositing Co or a Co alloy onto a substrate in manufacture of microelectronic devices, the method comprising:
treating water with a deoxygenating treatment to yield treated water having an oxygen concentration below 2 ppm;
adding a source of Co 2+ ions, a B-based or P-based reducing agent, and a complexing agent to the treated water to yield an aqueous electroless Co deposition composition comprising at least about 0.5 g/L Co 2+ ions and an oxygen concentration no greater than 2 ppm; and
incorporating an oxygen scavenger into the electroless deposition composition wherein the oxygen scavenger is selected from the group consisting of SO 3 2− , HSO 3 − , hydroquinone, catechol, resorcinol, and combinations thereof.
2. The method of claim 1 wherein said treating said water with said deoxygenating treatment comprises a treatment selected from the group consisting of gas purging, heating, applying a vacuum, sonicating, and flowing over a gas transfer membrane.
3. The method of claim 2 wherein said treating said water with said deoxygenating treatment comprises gas purging.
4. The method of claim 3 wherein said gas purging comprises purging with a gas selected from between nitrogen and argon.
5. The method of claim 2 wherein said treating said water with said deoxygenating treatment comprises heating.
6. The method of claim 5 wherein said heating comprises heating to a temperature not greater than about 85° C.
7. The method of claim 5 wherein said heating comprises heating to a temperature not greater than about 85° C. under a noble gas ambient.
8. The method of claim 2 wherein said treating said water with said deoxygenating treatment comprises applying a vacuum.
9. The method of claim 2 wherein said treating said water with said deoxygenating treatment comprises sonicating.
10. The method of claim 2 wherein said treating said water with said deoxygenating treatment comprises flowing over a gas transfer membrane.
11. The method of claim 1 wherein the oxygen scavenger comprises SO 3 2− , HSO 3 − , or a combination thereof.
12. The method of claim 11 wherein the oxygen scavenger is present in the electroless deposition composition at a concentration between about 0.01 g/L and about 1 g/L.
13. The method of claim 1 wherein the oxygen scavenger comprises hydroquinone at a concentration between about 0.01 g/L and about 0.5 g/L.
14. The method of claim 1 wherein the oxygen scavenger comprises catechol in a concentration between about 0.01 g/L and about 0.5 g/L.
15. The method of claim 1 wherein the oxygen scavenger comprises resorcinol in a concentration between about 0.01 g/L and about 0.5 g/L.
16. The method of claim 1 further comprising incorporating hydrazine as an oxygen scavenger into the electroless deposition composition in a concentration between about 0.01 g/L and about 0.5 g/L.
17. The method of claim 1 further comprising incorporating ascorbic acid as an oxygen scavenger into the electroless deposition composition.
18. The method of claim 1 wherein the treated water and the aqueous electroless Co deposition composition have an oxygen concentration no greater than about 1 ppm.
19. The method of claim 1 wherein the treated water and the aqueous electroless Co deposition composition have an oxygen concentration no greater than about 0.5 ppm.
20. The method of claim 1 wherein the water prior to said deoxygenating treatment has an oxygen concentration of at least about 7 ppm and the treated water and the aqueous electroless Co deposition composition have an oxygen concentration no greater than about 2 ppm.
21. The method of claim 1 wherein the water prior to said deoxygenating treatment has an oxygen concentration of at least about 7 ppm and the treated water and the aqueous electroless Co deposition composition have an oxygen concentration no greater than about 1 ppm.
22. The method of claim 1 wherein the water prior to said deoxygenating treatment has an oxygen concentration of at least about 7 ppm and the treated water and the aqueous electroless Co deposition composition have an oxygen concentration no greater than about 0.5 ppm.