Reduced area metal contact to a thin polysilicon layer contact structure having low ohmic resistance

摘要

Reduced area metal contacts to a thin polysilicon layer contact structure having low ohmic resistance was achieved. The structure involves forming contact openings in an insulating layer over a buffer layer composed of a thick polysilicon layer. A portion of the sidewall in the opening includes a patterned thin polysilicon layer that forms part of a semiconductor device and also forms the electrical connection to the metal contact. The structure provides metal contacts having very low resistance and reduced area for increased device packing densities. The metal contact structure also eliminates the problem of forming P+/N+ non-ohmic junctions usually associated with making P+/N+ stacked contact. The structure further allows process steps to be used that provide larger latitude in etching the contact opening and thereby provides a structure that is very manufacturable.