Semiconductor device including gate electrode for applying tensile stress to silicon substrate, and method of manufacturing the same

Abstract

A gate insulating film () and a gate electrode () of non-single crystalline silicon for forming an NMOS transistor are provided on a silicon substrate (). Using the gate electrode () as a mask, n-type dopants having a relatively large mass number (70 or more) such as As ions or Sb ions are implanted, to form a source/drain region of the NMOS transistor, whereby the gate electrode () is amorphized. Subsequently, a silicon oxide film () is provided to cover the gate electrode (), at a temperature which is less than the one at which recrystallization of the gate electrode () occurs. Thereafter, thermal processing is performed at a temperature of about 1000° C., whereby high compressive residual stress is exerted on the gate electrode (), and high tensile stress is applied to a channel region under the gate electrode (). As a result, carrier mobility of the NMOS transistor is enhanced.