Patent ID: 11923204
Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for manufacturing a semiconductor device, comprising the steps of:
performing a first heat treatment on an oxide semiconductor film at a temperature higher than or equal to 500° C. and lower than or equal to 850° C.;
adding oxygen into the oxide semiconductor film after the step of performing the first heat treatment; and
performing a second heat treatment on the oxide semiconductor film at a temperature higher than or equal to 500° C. and lower than or equal to 850° C. after the step of adding the oxygen,
wherein the oxide semiconductor film comprises In, Ga, and Zn,
wherein the oxide semiconductor film has a crystal region with a grain size of 1 nm or more and 20 nm or less, and
wherein each of the first heat treatment and the second heat treatment is performed under a reduced pressure atmosphere, an inert gas atmosphere, an oxygen gas atmosphere, or an ultra dry air atmosphere (air whose moisture content is less than or equal to 20 ppm (dew point conversion, −55° C.), in the case where measurement is performed using a dew-point meter of a cavity ring-down laser spectroscopy (CRDS) system).