To provide an invention for a logic circuit, a light-emitting device, a semiconductor device, and an electronic device, wherein an object is to obtain a desired threshold voltage for a thin-film transistor with oxide semiconductors, and another object is to suppress a change of the threshold voltage over time, and a further object is to specifically apply the thin-film transistor to a logic circuit to be formed by a transistor with a desired threshold voltage.
In order to achieve each object, a thin-film transistor in which oxide semiconductor layers with respectively different thicknesses are included is formed on the same substrate, and a logic circuit is formed by using the thin-film transistor whose threshold voltage is controlled by the thicknesses of the oxide semiconductor layers. In addition, a change in a threshold voltage over time is suppressed and the reliability of a logic circuit can be improved by using an oxide semiconductor film which is formed when an oxide insulating film is in contact thereto after dehydration or dehydrogenation treatment.
OIKAWA YOSHIAKI
MARUYAMA HODAKA
GOTO HIROMITSU
YAMAZAKI SHUNPEI
| JP2009004733A | 2009-01-08 |