STRESS-REDUCED POLYMETAL GATE ELECTRODE CAPABLE OF REDUCING MECHANICAL STRESS GENERATED FROM GATE STACK IN POST THERMAL PROCESS AND FABRICATING METHOD THEREOF

摘要

PURPOSE: A stress-reduced polymetal gate electrode and a fabricating method thereof are provided to improve a refresh characteristic and reliability by implanting ions into a low resistant metal to adjust a thermal expansion coefficient thereof. CONSTITUTION: A gate insulating layer(302) is formed on a semiconductor substrate(301). A gate stack(300) is formed on the gate insulating layer. The gate stack includes a polysilicon layer(303) as a bottom layer, a hardmask insulating layer(307) as a top layer, and a metal layer(305) formed therebetween. The metal layer has a minimum thermal expansion coefficient difference in comparison with the hardmask insulating layer and the polysilicon layer. An ion implantation buffer layer(306) is formed on the metal layer to perform a buffering function in an impurity implantation process.