D eposition of Cu films from supercritical fluids using Cu ( I ) b - diketonate precursors *

Cu films were deposited onto planar and etched silicon substrates by the hydrogen-assisted reduction of a series of copper(I)(1,1,1,5,5,5-hexafluoro-2,4-acetylacetonate)L compounds [Cu(I)(hfac)L] where L is (2butyne), (1,5-cyclooctadiene), (vinyltrimethylsilane) or (2-methyl-1-hexene-3-yne) in supercritical solvents using a cold wall, high pressure reactor. At substrate temperatures of 225 8C and a pressure of 200 bar, H reduction 2 of Cu(I)(hfac)(2-butyne) in CO yielded high purity films with exceptional step coverage in features as narrow 2 as 100 nm with an aspect ratio of eight. Planar films deposited by H reduction of each of the precursors in 2 supercritical CO and Cu(I)(hfac)(2-butyne) in supercritical C F exhibited little carbon or oxygen contamina2 2 6 tion. Attempts to deposit high purity Cu films by the thermal disproportionation of the Cu(I)(hfac)L precursors in supercritical CO in the absence of H at 225 8C were unsuccessful and yielded highly oxidized Cu films in 2 2 each case. Thermal disproportionation of Cu(I)(hfac)(2-butyne) in supercritical C F also yielded poor quality 2 6 films, although oxygen contamination was less severe than in CO . 2  2002 Elsevier Science B.V. All rights reserved.