Semiconductor device comprising an oxide semiconductor layer

摘要

A thin film transistor structure in which a source electrode and a drain electrode formed from a metal material are in direct contact with an oxide semiconductor film may lead to high contact resistance. One cause of high contact resistance is that a Schottky junction is formed at a contact plane between the source and drain electrodes and the oxide semiconductor film. An oxygen-deficient oxide semiconductor layer which includes crystal grains with a size of 1 nm to 10 nm and has a higher carrier concentration than the oxide semiconductor film serving as a channel formation region is provided between the oxide semiconductor film and the source and drain electrodes.

主权项

1. A semiconductor device comprising:
a gate electrode over an insulating surface; a gate insulating layer over the gate electrode; a semiconductor layer over the gate insulating layer; a first source region and a first drain region over the semiconductor layer; and a second source region and a second drain region over the first source region and the first drain region, wherein the semiconductor layer is an oxide semiconductor layer, wherein the first source region and the first drain region are oxide semiconductor layers, have a lower oxygen concentration than the semiconductor layer and include a crystal grain with a size of 1 nm to 10 nm, and wherein the second source region and the second drain region are oxide semiconductor layers, and contain W, Mo, Ti, Ni, or Al.