Method of eliminating buried contact trench in sram technology

Abstract

A new method of forming an improved buried contact junction is described. A first polysilicon layer is deposited overlying a gate silicon oxide layer on the surface of a semiconductor substrate. The first polysilicon and gate oxide layers are etched away where they are not covered by a buried contact mask to provide an opening to the semiconductor substrate. Ions are implanted through the opening into the semiconductor substrate to form a buried contact junction. A layer of dielectric material is deposited over the first polysilicon layer and over the semiconductor substrate within the opening. The layer is anisotropically etched to leave spacers on the sidewalls of the first polysilicon layer and adjacent the opening. A second layer of polysilicon is deposited overlying the first polysilicon layer and over the substrate within the opening. The second polysilicon layer is patterned to form gate electrodes and a polysilicon contact overlying the buried contact junction wherein the mask used for the patterning is misaligned and a portion of a spacer overlying the buried contact junction is exposed and wherein a portion of the second polysilicon layer other than that of the contact remains as residue. The second polysilicon layer residue is etched away wherein the exposed spacer protects the buried contact junction within the semiconductor substrate from the etching to complete the formation of a buried contact in the fabrication of an integrated circuit.