Two types of Cr-based thin films were grown by MOCVD and their behavior as diffusion barrier against Cu was investigated. Cr-3(CN)(2) layers were deposited using Cr(NEt2)(4) as single-source precursor in the temperature range 400-420 degreesC and CrSixCy was grown using Cr[CH(2)SiN(4)e(3)](4) at 475-500 degreesC. Both films are XRD amorphous. Annealing experiments of the Cu/banier/Si structures revealed the Cr-C-N barrier fails at 650 degreesC due to the crystallization of Cr-3(C0.8N0.2)(2). The barrier CrSixCy is more thermally stable and the failure temperature was found in the range 650-700 degreesC due to Cu diffusion through the barrier and the formation Of Cu3Si.