Patent ID: 8956929
Filing Date: 2015-02-17
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device comprising the steps of: forming an oxide semiconductor layer over an insulating surface; etching a part of the oxide semiconductor layer so that an island-shaped oxide semiconductor layer is formed; cleaning a top surface and a side surface of the island-shaped oxide semiconductor layer; and forming a source electrode layer and a drain electrode layer over the island-shaped oxide semiconductor layer after the cleaning step; further comprising the steps of: forming an oxide insulating layer having the insulating surface; forming a gate insulating layer over the island-shaped oxide semiconductor layer after the cleaning step; forming a gate electrode layer over the gate insulating layer; forming an insulating layer over the gate electrode layer to overlap with the gate electrode layer; introducing a dopant into a part of the island-shaped oxide semiconductor layer with use of the gate electrode layer and the insulating layer as a mask; forming a sidewall insulating layer over the gate insulating layer to cover a side surface of the gate electrode layer and a side surface of the insulating layer; forming a conductive layer over the island-shaped oxide semiconductor layer, the gate insulating layer, the gate electrode layer, the insulating layer, and the sidewall insulating layer; forming an interlayer insulating layer over the conductive layer; and removing a part of the interlayer insulating layer and a part of the conductive layer with a chemical mechanical polishing method until the insulating layer over the gate electrode layer is exposed, thereby forming the source electrode layer and the drain electrode layer.