| 摘要 |
PROBLEM TO BE SOLVED: To fine a thin-film transistor, and to improve its performance, where a field effect transistor formed on a substrate having an insulation surface is thinned and its performance is improved, especially a channel formation region is formed in a semiconductor layer crystallized by applying heat or thermal energy to a semiconductor having an amorphous structure. SOLUTION: The semiconductor device has a so-called SOI structure in which an element is constituted by a semiconductor layer on an insulating surface, and the semiconductor layer is extremely thin, namely 5 nm to 30 nm. The semiconductor device is provided with a field effect transistor that includes in addition to such a semiconductor layer, a gate insulating layer with a thickness of 2 nm to 20 nm and a gate electrode, and a channel length is not less than ten times and less than 40 times larger than the thickness of the semiconductor layer. By thinning the semiconductor layer, the semiconductor device operates so as not to be easily influenced by the concentration of one-conductivity-type impurities added to a channel formation region. COPYRIGHT: (C)2008,JPO&INPIT |
