| 摘要 |
A highly reliable transistor which includes an oxide semiconductor and has high field-effect mobility and in which a variation in threshold voltage is small is provided. By using the transistor, a high-performance semiconductor device, which has been difficult to realize, is provided. The transistor includes an oxide semiconductor film which contains two or more kinds, preferably three or more kinds of elements selected from indium, tin, zinc, and aluminum. The oxide semiconductor film is formed in a state where a substrate is heated. Further, oxygen is supplied to the oxide semiconductor film with an adjacent insulating film and/or by ion implantation in a manufacturing process of the transistor, so that oxygen deficiency which generates a carrier is reduced as much as possible. In addition, the oxide semiconductor film is highly purified in the manufacturing process of the transistor, so that the concentration of hydrogen is made extremely low.
|
