Method of forming a MOSFET with a recessed-gate having a channel length beyond photolithography limit

摘要

A method of forming a MOSFET having a recessed-gate with a channel length beyond the photolithography limit is disclosed in the present invention. First, a first dielectric layer and a second dielectric layer are formed on a semiconductor substrate. A first opening is next formed in the second dielectric layer. After forming first spacers on sidewalls of the first opening and removing the first dielectric layer within the first opening, a trench is formed in the semiconductor substrate by an anisotropic etching process. After forming second spacers with dopant source material on sidewalls of the trench, a gate dielectric layer is formed within the trench. A conductive layer is formed to refill said trench. After removing the portion of the conductive layer outside the trench, a gate plug is then formed. After removing the second dielectric layer, source and drain regions and source/drain extensions are formed