Patent ID: 8946812
Filing Date: 2015-02-03
Classification: H01L

Abstract:
1. A semiconductor device comprising: an oxide insulating layer; a trench formed in the oxide insulating layer; an oxide semiconductor film in contact with a bottom portion and side portions of the trench, the oxide semiconductor film including indium, gallium, and zinc; a source electrode and a drain electrode electrically connected to the oxide semiconductor film; a gate insulating layer over the oxide semiconductor film; and a gate electrode over the gate insulating layer, wherein the side portions have side surfaces substantially perpendicular to a top surface of the oxide insulating layer, wherein a width between upper ends of the trench is greater than or equal to 1 time and less than or equal to 1.5 times a width between the side surfaces, wherein at least one of the bottom portion and a lower corner portion in which the bottom portion meets one of the side portions has a curved shape, and wherein a center of curvature of the curved shape is positioned in the oxide insulating layer.