| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device using an oxide semiconductor, capable of achieving higher reliability by imparting with stable electrical characteristics.SOLUTION: An oxide semiconductor film serving as a channel formation region of a transistor is formed by a sputtering method at a temperature higher than 200°C, so that the number of water molecules eliminated from the oxide semiconductor film can be 0.5/nmor less in thermal desorption spectroscopy. A substance including a hydrogen atom such as hydrogen, water, a hydroxyl group, or hydride which causes variation in the electric characteristics of a transistor using an oxide semiconductor is prevented from entering the oxide semiconductor film, and thereby the oxide semiconductor film can be highly purified and made to be an electrically i-type (intrinsic) semiconductor.SELECTED DRAWING: Figure 1 |
