b626bc89_tsugi_JP___Patent_applications__Description
[Patent application number] 20110084266 [Published] 04-14-2011 [Description] 
SEMICONDUCTOR DEVICE, DISPLAY DEVICE, AND ELECTRONIC APPLIANCE - In a channel protected thin film transistor in which a channel formation region is formed using an oxide semiconductor, an oxide semiconductor layer which is dehydrated or dehydrogenated by a heat treatment is used as an active layer, a crystal region including nanocrystals is included in a superficial portion in the channel formation region, and the rest portion is amorphous or is formed of a mixture of amorphousness/non-crystals and microcrystals, where an amorphous region is dotted with microcrystals. By using an oxide semiconductor layer having such a structure, a change to an n-type caused by entry of moisture or elimination of oxygen to or from the superficial portion and generation of a parasitic channel can be prevented and a contact resistance with a source and drain electrodes can be reduced.
Kengo Akimoto, Atsugi JP - Patent applications