Abstract
Recently transition-metal nitrides and carbides have received great interest as diffusion barrier materials in contact structures for silicon semiconductor devices. Excellent stability of the contact structure is achievable through heat treatments of up to 600 °C when Ni is used as the top metal layer. However, the same transition-metal compounds show poor barrier properties with Al as the top layer if heat treated to 600 °C. We have therefore investigated the failure mechanism of transition-metal nitride and carbide barrier materials in Al overlayer metallizations. This knowledge has enabled us to develop high-temperature contact structures for silicon semiconductor devices by using an intermetallic compound of Al instead of plain Al for the top layer.