| abstract |
The present invention provides a transistor having high electrical characteristics with a high yield even with a microstructure. The present invention also achieves high performance, high reliability, and high production in a semiconductor device including the transistor. In a semiconductor device having a transistor in which an oxide semiconductor layer, a gate insulating layer, and a gate electrode layer provided with a side wall insulating layer are stacked in this order, a source is provided in contact with the oxide semiconductor layer and the side wall insulating layer. An electrode layer and a drain electrode layer. In the manufacturing process of the semiconductor device, a conductive layer and an interlayer insulating layer are laminated so as to cover the oxide semiconductor layer, the sidewall insulating layer, and the gate electrode layer, and the interlayer insulating layer on the gate electrode layer is removed by a chemical mechanical polishing method. And a conductive layer to form a source electrode layer and a drain electrode layer. Before the gate insulating layer is formed, the oxide semiconductor layer is washed. |