Method for manufacturing metal oxide semiconductor transistor having raised source/drain

Abstract

A method for manufacturing a metal oxide semiconductor transistor having a raised source/drain is described. A first spacer is formed on a sidewall of a gate electrode. An epitaxial layer is then formed on the exposed surface of the substrate and a top surface of the gate electrode. A light implantation step is then performed on the substrate while using the gate electrode and the first spacer as a first mask. Thereafter, a second spacer is formed on the sidewall of the gate electrode. A heavy implantation step is then performed on the substrate while using the gate electrode, the first spacer and the second spacer as a second mask. The epitaxial layer is then formed before the forming of the extension structure of the source/drain. Therefore, dopants in a source/drain extension structure avoid suffering the high temperature needed to form the epitaxial layer so that the redistribution of the dopants is prevented.