Properties as conducting diffusion barrier against Cu of two types of original Cr-based thin films grown by low-pressure metallorganic chemical vapor deposition (MOCVD) on Si(100) and SiO2/Si patterned substrates were investigated. Amorphous as-deposited CrCxNy and CrSixCy layers were deposited using Cr(NEt2)(4) and Cr[CH2SiMe3](4), respectively, as single-source precursor in the low-temperature range 400-420 degrees C and 475-500 degrees C. Then Cu films were grown on top of these barrier by low-pressure MOCVD using Cu(thd)(2) as molecular precursor. These Si/barrier/Cu structures were annealed under various conditions and they were thoroughly characterized in order to analyze the failure mechanism of the barrier. The CrCxNy barrier fails at 650 degrees C due to the crystallization of the ternary compound Cr-3(C0.8N0.2)(2). The CrSixCy barrier is more thermally stable and the failure temperature was found in the range 650-700 degrees C due to Cu diffusion through the barrier and the formation of Cu3Si. The behavior of these two barriers is compared and their performances are discussed with literature data. (c) 2005 The Electrochemical Society. All rights reserved.