Method for manufacturing semiconductor device including step of adding cation to oxide semiconductor layer

摘要

An object of an embodiment of the present invention is to provide a semiconductor device including a normally-off oxide semiconductor element whose characteristic variation is small in the long term. A cation containing one or more elements selected from oxygen and halogen is added to an oxide semiconductor layer, thereby suppressing elimination of oxygen, reducing hydrogen, or suppressing movement of hydrogen. Accordingly, carriers in the oxide semiconductor can be reduced and the number of the carriers can be kept constant in the long term. As a result, the semiconductor device including the normally-off oxide semiconductor element whose characteristic variation is small in the long term can be provided.

主权项

1. A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode over an insulator; forming a gate insulating layer over the gate electrode; adding cations containing oxygen to the gate insulating layer; forming a first oxide semiconductor layer over the gate insulating layer; adding cations containing oxygen to the first oxide semiconductor layer; forming a second oxide semiconductor layer over the first oxide semiconductor layer after adding the cations containing oxygen to the first oxide semiconductor layer; forming a source electrode and a drain electrode over the second oxide semiconductor layer; and forming an insulating layer over the second oxide semiconductor layer, the source electrode, and the drain electrode; wherein a heat treatment is performed at the time of the adding cations containing oxygen to the first oxide semiconductor layer, and wherein a concentration of hydrogen in the gate insulating layer is less than or equal to 5×1020 atoms/cm3.