METHOD FOR FABRICATING SEMICONDUCTOR DEVICE WITH POLY METAL GATE ELECTRODE TO BASICALLY PREVENT INTERFACIAL REACTION BETWEEN METAL LAYER AND POLYSILICON LAYER IN HIGH TEMPERATURE ANNEALING PROCESS

摘要

PURPOSE: A method for fabricating a semiconductor device with a poly metal gate electrode is provided to basically prevent interfacial reaction between a metal layer and a polysilicon layer in a high temperature annealing process by performing a source/drain annealing process before the metal layer is formed. CONSTITUTION: A gate stack in which a gate dielectric layer(32), a polysilicon layer(33), an etch stop layer, a sacrificial layer and a hard mask are sequentially formed is formed on a semiconductor substrate(31). A gate reoxidation process is performed to form a gate reoxidation layer(37) on the sidewall of the polysilicon layer, the etch stop layer and the sacrificial layer. A sidewall spacer(39) is formed on both sidewalls of the gate stack including the gate reoxidation layer. An ion implantation process and an annealing process are performed to form a source/drain region in the semiconductor substrate in the outside the sidewall spacer. An interlayer dielectric(41) is formed on the front surface of the semiconductor substrate. The interlayer dielectric is planarized until the surface of the sacrificial layer among the gate stack is exposed. A part of the sacrificial layer, the etch stop layer and the gate reoxidation layer is selectively removed to form a groove in the upper part of the polysilicon layer. A metal layer(44) for filling the groove is formed on the polysilicon layer.