Recessed gate electrode and method of forming the same and semiconductor device having the recessed gate electrode and method of manufacturing the same

Abstract

A recessed gate electrode structure includes a first recess and a second recess in communication with the first recess both formed in a substrate. The second recess is larger than the first recess. A gate dielectric layer is formed on a top surface of the substrate and on an inner surface of the first and second recesses. A first polysilicon layer fills the first recess and is doped with impurities at a first impurity density. A second polysilicon layer fills the second recess and is doped with the impurities at a second impurity density. A void is defined within the second polysilicon layer. A third polysilicon layer is formed on the gate dielectric and first polysilicon layers and is doped with the impurities at a third impurity density. Due to impurities in the second polysilicon layer, migration of the void within the second recess may be substantially prevented.