Patent ID: 6180465
Filing Date: 2001-01-30
Classification: H01L

Abstract:
A method for forming a scaled transistor on a substrate, the method comprising:forming a trench around an active region in the substrate;filling the trench with a dielectric material to isolate the active region;doping the active region to form a source/drain region in an upper portion of the active region;forming a thick dielectric layer across the surface of the substrate;forming a channel opening in the thick dielectric layer above a central portion of the source/drain region, the channel opening extending to the surface of the source/drain region and including a plurality of sidewalls;forming a thin dielectric layer across the surface of the substrate;etching the thin dielectric layer to remove portions of the thin dielectric layer residing upon the thick dielectric layer and to form spacers upon the plurality of sidewalls of the dielectric layer in the channel opening, the spacers residing upon the source/drain region such that the area of the channel opening is reduced;removing a portion of the source/drain region corresponding to the channel opening to extend the channel opening past the source/drain region into an undoped portion of the active region, the channel opening as extended segregating the source/drain region to form a source and a drain;forming a first gate dielectric layer in the channel opening, wherein a lower surface of the first gate dielectric layer in the channel opening resides below a lower surface of the source/drain region;forming a second dielectric layer across the surface of the substrate such that the second dielectric layer forms a second gate dielectric layer residing upon the first gate dielectric layer and also forms second spacers that reside upon the first spacers so that the area of the channel opening is again reduced;forming a gate conductor upon the second gate dielectric layer in the channel opening; andremoving portions of the thick dielectric layer to expose the source and the drain.