Patent ID: 7374988
Filing Date: 2008-05-20
Classification: H01L

Abstract:
1. A method of fabricating a field effect transistor, comprising: (a) providing a single-crystal silicon substrate having a single-crystal Ge comprising layer formed on a top surface of said single-crystal silicon substrate and a single-crystal silicon layer formed on a top surface of said single-crystal Ge comprising layer; (b) forming a gate dielectric layer on a top surface of said single-crystal silicon layer; (c) forming a gate electrode on a top surface of said dielectric layer; (d) removing a region of said single-crystal silicon layer to form a single crystal-silicon island under said gate electrode where said single crystal layer is not protected by said gate electrode followed by thinning said single-crystal Ge comprising layer where said single-crystal Ge comprising layer is not protected by said single crystal silicon layer; (e) oxidizing an entire remaining portion of said single-crystal Ge comprising layer not protected by said single crystal silicon layer, and a less than whole portion of said single-crystal Ge comprising layer under said gate electrode to form a single-crystal Ge comprising island under said single-crystal silicon island, said oxidizing forming a first dielectric layer on a first side and a second dielectric layer on a second and opposite side of said single-crystal Ge comprising island, said first dielectric layer and said second dielectric layer each extending under said gate electrode; and (f) forming a polysilicon source region over said first dielectric layer and forming a polysilicon drain region over said second dielectric layer, said polysilicon source region and said polysilicon drain region abutting opposite sides of said single-crystal silicon island.