Selective silicide thin-film transistor having polysilicon active layers with crystallizing metal agent introduced only in the source/drain regions

Abstract

A method for annealing amorphous silicon film to produce polycrystalline film suitable for thin-film transistors fabricated on glass substrates is provided. The method involves using the selective location of nickel on a predetermined region of silicon to define the pattern of the lateral growth front as the silicon is crystallized. The method defines the resistivity of the silicide formed. The method also defines a specific range of nickel thicknesses to form the nickel silicide. A minimum thickness ensures that a continuous layer of nickel silicide exists on the growth front to promote an isotropic lateral growth front to form a crystalline film having high electron mobility. A maximum thickness limit reduces the risk of nickel silicide enclaves in the crystalline film to degrade the leakage current. Strategic placement of the nickel helps prevent nickel silicide contamination of the transistor channel regions, which degrade the leakage current. A TFT polycrystalline film is also provided made by the above mentioned process of using a defined thickness, silicide resisitivity, and placement of nickel on amorphous silicon to form a silicide which induces a controlled crystallization growth front.