Oxidation Characteristics of Thin Al-Mo Alloy Films with Various Compositions as Metal Capping Layer on Cu

摘要

The oxidation characteristics of Al-Mo alloy films (50 nm) deposited on Cu as a metal capping layer have been examined by varying the alloy composition. Cu oxidation from the surface and Cu out-diffusion toward the surface are well suppressed when using Al-Mo alloy with a Mo-rich composition. By using an AI_(15)Mo_(85) alloy film, in which fine crystalline grains of AIM03 are dispersed in an amorphous phase of the alloy, a well-separated layer configuration of oxide/Al-Mo alloy/Cu without excess Cu diffusion and/or preferential Al oxidation in the alloy layer is realized upon oxidation at 350 ℃ for 1 h in air. It is revealed that Al_(15)Mo_(85) alloy films are a useful candidate material of a metal capping layer for Cu interconnects.