The chemical vapor deposition of copper and copper alloys

Abstract

The chemical vapor deposition of copper and copper alloys for very large 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, high-purity copper metal is deposited at substrate temperatures from 150 to 250 °C. The deposition rate becomes mass-transport limited at the higher substrate temperatures, but excellent filling of sub-micron vias (3:1 aspect ratio) was achieved. The deposition of copper-tin alloys can also be achieved when vinyl trialkyltin is used as the Lewis base. At 180 °C, a carbon-free copper film, containing 0.6 at.%Sn, is deposited. A very strong substrate temperature dependence towards film purity was observed and results from thermal decomposition of the tin-containing ligand. These preliminary results demonstrate the utility of using single-source, mixed-metal precursors for copper alloy formation. © 1995.