Manufacturing method of semiconductor device

摘要

Disclosed is a semiconductor device using an oxide semiconductor, with stable electric characteristics and high reliability. In a process for manufacturing a bottom-gate transistor including an oxide semiconductor film, dehydration or dehydrogenation is performed by heat treatment and oxygen doping treatment is performed. The transistor including a gate insulating film subjected to the oxygen doping treatment and the oxide semiconductor film subjected to the dehydration or dehydrogenation by the heat treatment is a transistor having high reliability in which the amount of change in threshold voltage of the transistor by the bias-temperature stress (BT) test can be reduced.

主权项

1. A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode layer; forming a gate insulating film over the gate electrode layer, wherein the gate insulating film contains an oxygen atom at a ratio greater than a stoichiometric proportion and less than four times as high as the stoichiometric proportion; performing a first heat treatment on the gate insulating film so as to remove water or hydroxide from the gate insulating film; forming an oxide semiconductor film over the gate insulating film so as to overlap with the gate electrode layer; performing a second heat treatment on the oxide semiconductor film so as to remove water or hydroxide from the oxide semiconductor film; forming a source electrode layer and a drain electrode layer which are electrically connected to the oxide semiconductor film; and forming an insulating film over the oxide semiconductor film, the source electrode layer, and the drain electrode layer so as to be in contact with the oxide semiconductor film, wherein the insulating film contains an oxygen atom at a ratio greater than a stoichiometric proportion and less than four times as high as the stoichiometric proportion.