| abstract |
A method for fabricating a dual layer gate electrode having a polysilicon layer and a workfunction metal layer comprises depositing a layer of a workfunction metal on a semiconductor substrate, depositing a layer of polysilicon on the workfunction metal layer, depositing a hard mask layer on the polysilicon layer, etching the hard mask layer to form a hard mask structure defining a gate electrode, etching the polysilicon layer to remove a portion of the polysilicon layer not protected by the hard mask structure, thereby forming a polysilicon structure beneath the hard mask structure, applying a mixture of ozone and water to exposed sidewalls of the polysilicon structure, thereby forming a silicon dioxide layer on the sidewalls, and etching the workfunction metal layer to remove a portion of the workfunction metal layer not protected by the hard mask structure, thereby forming a workfunction metal structure beneath the polysilicon structure. |