Method for fabricating a transistor gate with a T-like structure

摘要

A method for fabricating a field effect transistor (FET) with a T-like gate structure includes forming a silicon nitride layer over a silicon substrate and patterning it to form an opening that exposes the substrate. A dielectric layer is formed on a lower portion of each side-wall of the opening so that the opening has a T-like free space. A doped polysilicon layer fills the T-like free space through only one deposition. After performing a planarization on the doped polysilicon layer, a titanium metal layer is formed over the substrate. A self-aligned titanium silicide is formed over the substrate other than the dielectric layer surface through a rapid thermal process (RTP). A selective etching process is performed to remove the remaining titanium metal layer. After removing the dielectric layer a RTP is performed again to reform the crystal structure of the titanium silicide layer so as to reduce its resistance. A T-like gate structure is formed.