Method for manufacturing semiconductor device with oxide semiconductor ohmic conatct layers

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 method for manufacturing a semiconductor device, comprising steps of:
forming a gate electrode over an insulating surface; forming a gate insulating layer over the gate electrode by sputtering; forming a first semiconductor layer over the gate insulating layer by sputtering without exposure to air after forming the gate insulating layer; forming a second semiconductor layer over the first semiconductor layer by sputtering; and patterning the second semiconductor layer to form a source region and a drain region over the first semiconductor layer, wherein the first semiconductor layer is an oxide semiconductor layer, and wherein the source region and the drain region are oxide semiconductor layers containing indium, gallium, and zinc, and have a lower oxygen concentration than the first semiconductor layer, and wherein the source region and the drain region include a crystal grain with a size of 1 nm to 10 nm.