Semiconductor device

摘要

A transistor including an oxide semiconductor and having favorable operation characteristics is provided. Further, by using the transistor, a semiconductor having improved operation characteristics can be provided. In planar view, one of a source electrode and a drain electrode of the transistor is surrounded by a ring-shaped gate electrode. Further, in planar view, one of the source electrode and the drain electrode of the transistor is surrounded by a channel formation region. Accordingly, the source electrode is not electrically connected to the drain electrode through a parasitic channel generated in an end portion of an island-shaped oxide semiconductor layer.

主权项

1. A semiconductor device comprising:
a first insulating layer over a first wiring; an island-shaped semiconductor layer over the first insulating layer; a source electrode and a drain electrode over the island-shaped semiconductor layer, wherein one of the source electrode and the drain electrode is electrically connected to the first wiring through an opening in the island-shaped semiconductor layer and the first insulating layer; a second insulating layer over the island-shaped semiconductor layer, the source electrode, and the drain electrode; and a gate electrode over the second insulating layer, wherein an entire outer edge of one of the source electrode and the drain electrode is surrounded by the gate electrode in planar view, and wherein an outer edge of the gate electrode is surrounded by the other of the source electrode and the drain electrode in the planar view.