US Patent 7825493 Field-effect transistor and method for fabricating the same

A field-effect transistor that increases the operation speeds of complementary field-effect transistors. Each of an nMOSFET and a pMODFET has a Ge channel and source and drain regions formed of an NiGe layer. The height of Schottky barriers formed at a junction between a channel region and the source region of the nMOSFET and at a junction between the channel region and the drain region of the nMOSFET is changed by very thin high-concentration segregation layers formed by making As atoms, Sb atoms, S atoms, or the like segregate at the time of forming the NiGe layer. As a result, Schottky barrier height suitable for the nMOSFET and the pMODFET can be obtained, thus being capable of realizing high-speed CMOSFETs.