SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

摘要

PURPOSE: A semiconductor device and a manufacturing method thereof are provided to reduce power consumption by decreasing an average surface roughness of a surface of an oxide semiconductor layer. CONSTITUTION: An oxide semiconductor layer(55) is formed on an insulation surface. An average surface roughness of an oxide semiconductor layer is reduced by irradiating oxygen ions(53) to the oxide semiconductor layer. A gate insulation layer(63) is formed on the oxide semiconductor layer after the oxygen ions are irradiated to the oxide semiconductor layer. A gate electrode is formed on the gate insulation layer to overlap the oxide semiconductor layer. An oxide semiconductor layer including a crystal with a C axis which is vertical to the surface of the oxide semiconductor layer is formed by heating the oxide semiconductor layer after the oxygen ions are irradiated to the oxide semiconductor layer.