Selective chemical vapor deposition of copper on AZ 5214™-patterned silicon substrates

Copper features with dimensions down to 0.5 mum were fabricated on silicon substrates by selective chemical vapor deposition. For the fabrication, oxidized (100) silicon substrates were used, covered with a film grown by low-pressure chemical vapor deposition at 0.1 Torr and 550 degreesC, from W(CO)(6) decomposition. These substrates were subsequently covered with AZ 5214 (TM) photosensitive polymer, which has been developed as both positive and negative tone resist. Copper was then chemically vapor deposited on the patterned substrates by 1, 5-cyclooctadiene Cu(I) hexafluoroacetylacetonate decomposition, at 1 Torr and temperatures of 110 and 140 degreesC. A vertical, cold-wall reactor was used, equipped with an UV lamp permitting photon-assisted deposition. Under UV illumination, copper was deposited on resist covered and uncovered parts of the substrate. In the absence of illumination, the metal was selectively grown on the tungsten film only at relatively slow rates (1 and 3.5 nm/min at 110 and 140 degreesC, respectively). Copper films had a granular form with a grain size increasing with temperature (150 and 550 nm at 110 and 140 degreesC, respectively). After depositions, the resist wad removed in oxygen plasma leading to the formation of fine copper features. (C) 2001 American Vacuum Society.