Utilizing amorphorization of polycrystalline structures to achieve T-shaped MOSFET gate

摘要

A method of forming a generally T-shaped structure. The method comprises forming a poly/amorphous silicon layer stack which comprises a polysilicon layer and a generally amorphous silicon layer overlying the polysilicon layer. The method further comprises selectively etching the poly/amorphous silicon layer stack, wherein an etch rate associated with the generally amorphous silicon layer in an over etch step associated therewith is less than an etch rate associated with the polysilicon layer, thereby causing a lateral portion of the generally amorphous silicon layer to extend beyond a corresponding lateral portion of the polysilicon layer.