Self-aligned contact schemes for source-drains in submicron devices

This paper reviews the basic limitations in source-drain parasitics and source-drain contacts as devices are scaled to the submicron regime. The major portion of the paper reviews the various proposals to provide local interconnect layers which interface with the source-drain and from which all contact windows to metal-1 are made over field oxide. Among the promising approaches are HPSAC, TiN local interconnect, BOMOS and UPMOS. Significant improvements in parasitic reduction, layout density, and reliability can be achieved.