Thin film transistor including buffer layers with high resistivity

摘要

A transistor in a display device is expected to have higher withstand voltage, and it is an object to improve the reliability of a transistor which is driven by high voltage or large current. A semiconductor device includes a transistor in which buffer layers are provided between a semiconductor layer forming a channel formation region and source and drain electrode layers. The buffer layers are provided between the semiconductor layer forming a channel formation region and the source and drain electrode layers in order to particularly relieve an electric field in the vicinity of a drain edge and improve the withstand voltage of the transistor.

主权项

1. A semiconductor device comprising:
a transistor comprising: a gate electrode layer; a gate insulating layer over the gate electrode layer; a semiconductor layer comprising a channel formation region over the gate insulating layer; a buffer layer comprising an oxide of indium, a silicon oxide, and an oxide of tin over the semiconductor layer; and a source electrode layer and a drain electrode layer over the buffer layer, wherein the semiconductor layer is an oxide semiconductor layer, wherein the semiconductor layer is electrically connected to the source electrode layer and the drain electrode layer through the buffer layer, and wherein a percentage of the silicon oxide contained in the buffer layer is higher than or equal to 1 wt % and lower than or equal to 20 wt %.