Ultrathin TaSiC amorphous films prepared by magnetron cosputtering using TaSi 2 and C targets on Si͑100͒, in a sandwiched scheme Si͑100͒ / TaSiC͑5 nm͒ / Cu, were evaluated for barrier performance in copper metallization. Optimizing carbon content maximizes thermal stability of the films as depicted by sheet-resistance, x-ray diffraction, and transmission electron microscopy examination. The stability temperatures of 700°C ͑24 at. % C͒ and 750°C ͑34 at. % C͒ have been systematically verified and discussed. Since Ta, Si, and C are compatible with integrated circuit ͑IC͒ processing, the TaSiC films are readily applicable for sub-65-nm IC production.

Structural changes at high temperature of amorphous TaSi 2 C x films deposited on Si͑100͒ were evaluated. Increased carbon content remarkably raises crystallization temperature; thus, TaSi 2 C x films ͑x Ͼ 16 atom %͒ sustain amorphous phase at 800°C for at least 30 min. A preliminary evaluation of such films as a diffusion barrier of Cu metallization in a sandwich scheme Si͑100͒/TaSi 2 C x ͑20 nm͒/Cu showed the stability of 750°C ͑x = 19 atom %͒ or 800°C ͑x = 22 atom %͒ for at least 5 min without a sharp increase in sheet resistance nor the formation of Cu 3 Si. Because Ta, Si, and C are compatible with integrated-circuit processing, these films are readily applicable as diffusion barriers in Cu metallization.

Ta–Si–C amorphous films 5nm thick were found applicable as a diffusion barrier against Cu penetration for sub- 65nm integrated circuit processing. The failure mechanisms of such a barrier were still unknown and were explored in this study. Ta–Si–C films were prepared by magnetron cosputtering using TanormalSi2 and C targets on p-type Si(100) substrate. Failure mechanisms were explored by Auger electron spectroscopy, X-ray diffraction, transmission electron microscopy, and four-point probe measurement on annealed films. In a sandwiched scheme Si∕Ta–Si–C (50.3emnm)∕Cu , the failure temperatures 750 (18 atom % C) and 800°C (24 atom % C) were demonstrated. Deterioration of Ta–Si–C barriers arose from local nucleation of TanormalSi2 crystallites, providing short paths for copper penetration. Carbon addition significantly inhibited the formation of TanormalSi2 and increased the failure temperature of the barriers. From the understanding of the failure mechanism a possible solution is proposed to research thinner barriers (such as 2nm ) to meet the 2016 International Technology Roadmap for Semiconductors.

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