Methods of fabricating a dual polysilicon gate and methods of fabricating a semiconductor device using the same

Abstract

A dual polysilicon gate is fabricated by, inter alia, forming a polysilicon layer doped with impurities of a first conductivity type on a substrate having a first region and a second region, forming a mask pattern that covers the polysilicon layer in the first region and leaves the polysilicon layer in the second region, injecting impurities of a second conductivity type into the polysilicon layer in the second region left exposed by the mask pattern. Removing the mask pattern, and patterning the polysilicon layer to form a first polysilicon pattern in the first region and a second polysilicon pattern in the second region. The second polysilicon pattern is formed to have protrusions that laterally protrude from sidewalls thereof. Subsequently, impurities of the second conductivity type are injected into the substrate in the second region and into the protrusions of the second polysilicon pattern.