THE CHEMICAL-VAPOR-DEPOSITION OF COPPER AND COPPER-ALLOYS

The chemical vapor deposition of copper and copper alloys for very lar ge scale integrated interconnects is described using a series of Lewis base stabilized copper(I) 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato ( hfac) complexes. When the Lewis base is dimethyl-1,5-cyclooctadiene, h igh-purity copper metal is deposited at substrate temperatures from 15 0 to 250 degrees C. The deposition rate becomes mass-transport limited at the higher substrate temperatures, but excellent filling of sub-mi cron vias (3:1 aspect ratio) was achieved. The deposition of copper-ti n alloys can also be achieved when vinyl trialkyltin is used as the Le wis base. At 180 degrees C, a carbon-free copper film, containing 0.6 at.%Sn, is deposited. A very strong substrate temperature dependence t owards film purity was observed and results from thermal decomposition of the tin-containing ligand. These preliminary results demonstrate t he utility of using single-source, mixed-metal precursors for copper a lloy formation.