Methods for manufacturing semiconductor devices and semiconductor devices

摘要

Semiconductor devices and methods for manufacturing the same in which deterioration of the electrical characteristic is suppressed are described. One method for manufacturing a semiconductor device includes the steps of: forming a first polysilicon layer 32 on a gate dielectric layer 20; forming a silicon nitride layer 92 on the first polysilicon layer 32; forming a second polysilicon layer 94 on the silicon nitride layer 92; forming sidewall spacers; forming an insulation layer 60 that covers the second polysilicon layer 94; planarizing the insulation layer 60 until an upper surface of the second polysilicon layer 94 is exposed; removing the second polysilicon layer 94; removing the silicon nitride layer 92 to form a recessed section 80; and filling a metal layer 34 in the recessed section 80 to form a gate electrode 30 that includes at least the first polysilicon layer 32 and the metal layer 34.