Semiconductor device including oxide semiconductor and manufacturing method thereof

A method for manufacturing a semiconductor device comprising the step of:

• forming an oxide semiconductor film serving as a channel formation region of a transistor by a sputtering method at a temperature higher than 300° C. and lower than or equal to 500° C. so that the number of water molecules eliminated from the oxide semiconductor film is 0.5/nm3 or less according to thermal desorption spectroscopy and a carrier density of the oxide semiconductor film is less than 1×1012/cm3,
• wherein the number of water molecules is calculated by comparing a first value of integral of a TDS spectrum of water molecules in the oxide semiconductor film with a second value of integral of a TDS spectrum of hydrogen molecules in a reference sample,
• wherein the first value of integral and the second value of integral are calculated within a temperature range of higher than or equal to 150° C. and lower than or equal to 400° C.,
• wherein the reference sample is a silicon wafer, and
• wherein the oxide semiconductor film is an i-type oxide semiconductor film.

A method for manufacturing a semiconductor device comprising the steps of:

• forming an oxide semiconductor film serving as a channel formation region of a transistor by a sputtering method at a temperature higher than 300° C. and lower than or equal to 500° C. so that the number of water molecules eliminated from the oxide semiconductor film is 0.5/nm3 or less according to thermal desorption spectroscopy and a carrier density of the oxide semiconductor film is less than 1×1012/cm3, and
• performing an oxygen doping treatment on the oxide semiconductor film,
• wherein the number of water molecules is calculated by comparing a first value of integral of a TDS spectrum of water molecules in the oxide semiconductor film with a second value of integral of a TDS spectrum of hydrogen molecules in a reference sample,
• wherein the first value of integral and the second value of integral are calculated within a temperature range of higher than or equal to 150° C. and lower than or equal to 400° C., and
• wherein the reference sample is a silicon wafer.