Thin film transistor with a sub-gate structure and a drain offset region

Abstract

A novel structure of a polycrystalline silicon thin film transistor manifested in a drain offset region and a sub-gate structure. The drain offset region is formed between a channel region and a drain region in the polycrystalline silicon thin film. The sub-gate structure comprises at least one sub-gate, except for a main gate which is provided in a normal field effect transistor. This structure is applicable to either an upper gate type or a bottom gate type thin film transistor. The sub-gate structure may include an upper sub-gate and/or a bottom sub-gate. The upper sub-gate overlays the channel region, drain offset and drain regions through an insulation layer. The bottom sub-gate underlies the channel region, drain offset and drain regions through an insulation layer. The sub-gate is applied with the same voltage or less as the drain voltage thereby permitting a relaxation of a high field concentration caused at a drain junction to be realized. This may provide a reduction of a leakage current and a security of a high ON-current.

Dependencies are inferred from the claim text.