THIN FILM TRANSISTOR

摘要

PROBLEM TO BE SOLVED: To provide a thin film transistor which has an active layer of silicon carbide on an insulating substrate, source and drain electrodes in contact with the surface of the active layer, and a gate electrode provided on the source and drain electrodes via an insulator film, and which has smaller leakage current and less fluctuation in threshold voltage than a polysilicon TFT. SOLUTION: In a manufacturing process according to the mode for carrying out the invention, a silicon layer 11 is first formed on a glass substrate 10, and a polycrystal SiC layer is formed on the entire surface. After that, patterning is carried out to form a polycrystal SiC active layer. In this case, the density of group Vb elements in the active layer is less than 1×10<19> /cm<3> and the density of group IIIb elements is less than 1×10<20> /cm<3> . After a silicon film 13 is formed, a gate 14 is formed thereon, and the silicon oxide film 13 on source and drain regions is removed by etching to open contact holes, thereby forming source and drain electrodes. Meanwhile, results of evaluation show that a thin film transistor according to the mode for carrying out the invention has sufficiently small fluctuation in threshold voltage.