Use of the polysilicon gate layer for local interconnect in a CMOS technology incorporating LDD structures

In conventional single-level polysilicon technologies, the polysilicon gate layer can be used as an interconnect layer through buried contacts between polysilicon and one type of junction (usually n ⁺) in the underlying substrate. The formation and characteristics of buried contacts between n⁺ and p⁺ junctions and a single polysilicon gate layer are discussed. In addition, it is shown that the obstacles posed by the inclusion of oxide-sidewall spacers (common in present-day VLSI CMOS technologies) are surmountable with respect to the formation of useful buried contacts and the resultant local interconnect level that they provide