Patent attributes
To provide a miniaturized semiconductor device with stable electric characteristics in which a short-channel effect is suppressed. Further, to provide a manufacturing method of the semiconductor device. The semiconductor device (transistor) including a trench formed in an oxide insulating layer, an oxide semiconductor film formed along the trench, a source electrode and a drain electrode which are in contact with the oxide semiconductor film, a gate insulating layer over the oxide semiconductor film, a gate electrode over the gate insulating layer is provided. The lower corner portions of the trench are curved, and the side portions of the trench have side surfaces substantially perpendicular to the top surface of the oxide insulating layer. Further, the width between the upper ends of the trench is greater than or equal to 1 time and less than or equal to 1.5 times the width between the side surfaces of the trench.
