Patent ID: 7163865

Claim:
A method of forming a transistor having a recess channel, said method comprising: sequentially forming a pad oxide film and a mask film on a semiconductor substrate having a device separation film, and then forming an opening for partially exposing the pad oxide film by performing a photolithography and etching process; simultaneously etching the pad oxide film exposed in the opening and the pad oxide film provided at a lower edge of the mask Film to expose a partial surface of the semiconductor substrate in an undercut region of the mask film; performing an etching process to form a recess in the semiconductor substrate by using the mask film as an etch mask and to simultaneously form a sidewall spacer that extends from the undercut region and that surrounds both sidewalls of the mask film; forming a gate oxide film on the semiconductor substrate including a surface of the recess, then forming a gate electrode inside the recess that overlaps an upper edge of the recess and is positioned higher than an upper part of the recess, then forming a gate insulation film on the gate electrode; and forming a gate spacer on a sidewall of the gate electrode and the gate insulation film, and forming a source region and a drain region.