Transistor having enhanced metal silicide and a self-aligned gate electrode

Abstract

A transistor and a method for making a transistor are described. A metal layer is formed upon a semiconductor substrate, and a masking layer is formed upon the metal layer. The masking layer is patterned to form an opening therein, and portions of the metal layer not covered by the masking layer are removed. A gate dielectric layer is formed within the opening upon the semiconductor substrate; in an embodiment, spacers are also formed upon opposed sidewall surfaces of the masking layer. A conductive material is then deposited upon the dielectric material to form a gate conductor. The masking material is then removed, source and drain and lightly doped drain impurity areas are formed in the semiconductor substrate, and the metal layer is annealed to form a silicide in close proximity to the channel region. By depositing the metal layer prior to forming the gate conductor, the process described herein allows formation of a metal silicide adjacent or in close proximity to the channel region of the transistor. The process also allows formation of a metal gate conductor self-aligned with lightly doped drain or source-drain impurity areas.