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

Two types of Cr-based thin films were grown by MOCVD and their behavior as diffusion barrier against Cu was investigated. Cr3(C,N)2 layers were deposited using Cr(NEt2)4 as single-source precursor in the temperature range 400-420 °C and CrSixCy was grown using Cr[CH2SiMe3]4 at 475-500 °C. Both films are XRD amorphous. Annealing experiments of the Cu/barrier/Si structures revealed the Cr-C-N barrier fails at 650 °C due to the crystallization of Cr3(C0.8N0.2)2. The barrier CrSixCy is more thermally stable and the failure temperature was found in the range 650-700 °C due to Cu diffusion through the barrier and the formation of Cu3Si.