Patent ID: 9502580
Filing Date: 2016-11-22
CPC Classification: H01L,Y02E

Claim Text:
1. A semiconductor device comprising: a gate electrode; a gate insulating film over the gate electrode; a first oxide semiconductor film over the gate insulating film; a second oxide semiconductor film having a crystalline structure over the first oxide semiconductor film; and a third oxide semiconductor film over the second oxide semiconductor film, a source electrode and a drain electrode which are in contact with the third oxide semiconductor film, wherein a bottom of a conduction band in the second oxide semiconductor film is deeper from a vacuum level than a bottom of a conduction band in the first oxide semiconductor film and a bottom of a conduction band in the third oxide semiconductor film, wherein each of the first oxide semiconductor film, the second oxide semiconductor film, and the third oxide semiconductor film includes indium, zinc, and gallium, wherein the first oxide semiconductor film has a lower degree of crystallinity than the second oxide semiconductor film, and wherein the third oxide semiconductor film has a lower degree of crystallinity than the second oxide semiconductor film.