| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device which has a transistor having excellent dynamic characteristics (ON characteristic and frequency characteristic) and a transistor having a suppressed OFF current, on the same substrate.SOLUTION: Oxide semiconductor layers 404a, 404b that are intrinsic or substantially intrinsic, and contain crystal regions on their surfaces, are used for transistors 440A, 440B. A material which removes impurities that become an electron donor (donor) in the oxide semiconductor, and has an energy gap being larger than that of a silicon semiconductor, is used as an intrinsic or substantially intrinsic semiconductor. Electric characteristics of transistors 440A, 440B are controlled by controlling electric potentials of a pair of conductive films 421a, 422a and 421b, 422b arranged above and below oxide semiconductor layers 404a, 404b through insulation films 402, 428, and changing a position of a channel formed on the oxide semiconductor layers. |
