Field-effect transistor including oxide semiconductor, and memory and semiconductor circuit including the same

摘要

Provided is a field-effect transistor (FET) having small off-state current, which is used in a miniaturized semiconductor integrated circuit. The field-effect transistor includes a thin oxide semiconductor which is formed substantially perpendicular to an insulating surface, a gate insulating film formed to cover the oxide semiconductor, and a gate electrode which is formed to cover the gate insulating film. The gate electrode partly overlaps a source electrode and a drain electrode. The source electrode and the drain electrode are in contact with at least a top surface of the oxide semiconductor. In this structure, three surfaces of the thin oxide semiconductor are covered with the gate electrode, so that electrons injected from the source electrode or the drain electrode can be effectively removed, and most of the space between the source electrode and the drain electrode can be a depletion region; thus, off-state current can be reduced.

主权项

1. A semiconductor device comprising a transistor, the transistor comprising:
an oxide semiconductor over a substrate, the oxide semiconductor including a bottom surface, a top surface and side surfaces, the side surfaces extending in a channel length direction of the transistor, wherein a height of the oxide semiconductor is greater than a length of the oxide semiconductor at the bottom surface along a direction perpendicular to the channel length direction; a source electrode in contact with at least the top surface of the oxide semiconductor; a drain electrode in contact with at least the top surface of the oxide semiconductor; and a gate electrode along the top surface and the side surfaces with a gate insulating film between the gate electrode and the oxide semiconductor, wherein the gate electrode partly overlaps the source electrode, and wherein the gate electrode partly overlaps the drain electrode.