Method for forming dual gate electrodes using damascene gate process

Abstract

A method for forming dual gate electrodes using a damascene gate process is disclosed. A disclosed method comprises: growing a first gate oxide layer on a semiconductor substrate; performing a thermal treatment for a first gate oxide layer; removing a predetermined part of the first gate oxide layer until the top surface of the semiconductor substrate is exposed; growing a second gate oxide layer as a thin oxide layer on the exposed semiconductor substrate, thereby making the first gate oxide layer as a thick oxide layer; depositing polysilicon on the entire surface of the semiconductor substrate and forming dummy gates through a photolithography and an etching processes; forming sidewall spacers on the lateral faces of the dummy gates; forming source and drain regions in the substrate under both sides of the dummy gates; removing the dummy gates and the second gate oxide layer; forming an insulating layer where the second gate oxide layer is removed; performing a thermal treatment for the insulating layer; filling polysilicon for gate electrodes where the dummy gates were removed; and planarizing the resulting structure until the gate electrodes are exposed.