Method for manufacturing insulated-gate type field effect transistor

Abstract

A poly-silicon layer is deposited on a surface of a substrate after forming a gate insulating film in an element hole of a field insulating film, and thereon a silicon oxide layer is formed by a thermal oxidation process. After patterning the silicon oxide layer in accordance with a gate electrode pattern, the poly-silicon layer is patterned by dry-etching using a remaining resist layer as a mask. After removing the resist layer, a gate electrode layeris formed by decreasing a width of the poly-silicon layer by isotropic etching using the silicon oxide layerA as a mask. N-type source and drain regionsandand n-type source and drain regionsandare formed by doping impurity ions via the gate insulating filmthrough the silicon oxide layerA. The silicon oxide layerA may be made of a layer of tungsten silicide.