Method for manufacturing semiconductor device

摘要

An object is to provide a semiconductor device including an oxide semiconductor, which has stable electrical characteristics and high reliability. In a manufacturing process of a bottom-gate transistor including an oxide semiconductor layer, heat treatment in an atmosphere containing oxygen and heat treatment in vacuum are sequentially performed for dehydration or dehydrogenation of the oxide semiconductor layer. In addition, irradiation with light having a short wavelength is performed concurrently with the heat treatment, whereby elimination of hydrogen, OH, or the like is promoted. A transistor including an oxide semiconductor layer on which dehydration or dehydrogenation treatment is performed through such heat treatment has improved stability, so that variation in electrical characteristics of the transistor due to light irradiation or a bias-temperature stress (BT) test is suppressed.

主权项

1. A method for manufacturing a semiconductor device, comprising the sequential steps of:
forming a gate electrode layer; forming a gate insulating layer over the gate electrode layer; forming an oxide semiconductor layer over the gate insulating layer so as to overlap with the gate electrode layer; increasing a temperature of the oxide semiconductor layer in an inert gas atmosphere, a dry air atmosphere, or an oxygen atmosphere; performing first heat treatment on the oxide semiconductor layer in an oxygen atmosphere after the step of increasing the temperature of the oxide semiconductor layer; performing second heat treatment on the oxide semiconductor layer under reduced pressure after the step of performing the first heat treatment; performing cooling of the oxide semiconductor layer in an oxygen atmosphere after the step of performing the second heat treatment; forming a source electrode layer and a drain electrode layer which are electrically connected to the oxide semiconductor layer after the step of performing the cooling; and forming an insulating layer over the oxide semiconductor layer, the source electrode layer, and the drain electrode layer.