Method for self-aligned vertical double-gate mosfet

Abstract

A method of forming a self-aligned vertical double-gate metal oxide semiconductor field effect transistor (MOSFET) device is provided that includes processing steps that are CMOS compatible. The method include the steps of growing an oxide layer on a surface of a silicon-on-insulator (SOI) substrate, said SOI substrate having a buried oxide region located between a top Si-containing layer and a bottom Si-containing layer, wherein said top and bottom Si-containing layers are of the same conductivity-type; patterning and etching gate openings in said oxide layer, said top Si-containing layer and said buried oxide region stopping on said bottom Si-containing layer of said SOI substrate; forming a gate dielectric on exposed vertical sidewalls of said gate openings and filling said gate openings with silicon; removing oxide on horizontal surfaces which interface with said Si-containing bottom layer; recrystallizing silicon interfaced to said gate dielectric and filling said gate openings with expitaxial silicon; forming a mask on said oxide layer so as cover one of the silicon filled gate openings, while leaving an adjacent silicon filled gate opening exposed; selectively implanting dopants of said first conductivity-type into said exposed silicon filled gate opening and activating the same, wherein said dopants are implanted at an ion dosage of about 1E15 cm or greater; selectively etching the exposed oxide layer and the underlying top Si-containing layer of said SOI substrate stopping on said buried oxide layer; removing said mask and implanting a graded-channel dopant profile in said previously covered silicon filled gate opening; etching any remaining oxide layer and forming spacers about said silicon filled gate openings; and saliciding any exposed silicon surfaces.