Fabrication and characterization of T-gate polysilicon thin-film transistors with lightly-doped drain

Abstract

We report detailed fabrication and characterization of poly-Si thin-film transistors (TFTs) with T-shaped gate (T-gate) and lightly-doped drain (LDD) structures. The formation of the LDD underneath the wings of a T-gate primarily relies on the shadowing of implanted dopants during the implantation of source and drain. Therefore, the fabrication of LDD structures in our proposed T-gate poly-Si TFTs can save a number of process steps as compared to conventional poly-Si TFTs with LDD structures. Our fabricated T-gated poly-Si TFTs with LDD structures not only exhibit suppressed off-state leakage current but also show a significant improvement in on-state current as compared to that of conventional poly-Si TFTs with the same top-gate dimension.