Method for fabricating semiconductor device

The present invention provides a method for fabricating a semiconductor device capable of suppressing stresses concentrated at bottom corners of a gate electrode as simultaneously as preventing an oxidation of a metal included in a gate electrode. The inventive method includes the steps of: forming a gate oxide layer on a substrate; forming a gate electrode including at least one metal layer on the gate oxide layer; forming an oxide layer on the substrate including the gate electrode at a temperature lower than oxidation temperature of the metal layer; and etching selectively the densified oxide layer so as to form an oxide spacer on the lateral sides of the gate electrode.