Chemical vapor deposition of Cr-based thin films as diffusion barriers in copper metallization

摘要

Two types of Cr-based thin films were grown by MOCVD and their behavior as diffusion barrier against Cu was investigated. Cr_3(C,N)_2 layers were deposited using Cr(NEt_2)_4 as single-source precursor in the temperature range 400-420℃ and CrSi_xC_y was grown using Cr[CH_2SiMe_3]_4 at 475-500℃. Both films are XRD amorphous. Annealing experiments of the Cu/barrier/Si structures revealed the Cr-C-N barrier fails at 650℃ due to the crystallization of Cr_3(C_(0.8)N_(0.2))_2. The barrier CrSi_xC_y is more thermally stable and the failure temperature was found in the range 650-700℃ due to Cu diffusion through the barrier and the formation of Cu_3Si.