Method for manufacturing semiconductor device

A method for manufacturing a semiconductor device including a transistor comprises:

• forming an oxide semiconductor film;
• forming a first insulating film over the oxide semiconductor film;
• forming a metal oxide film over and in contact with the first insulating film;
• performing a heat treatment after forming the metal oxide film;
• forming a conductive film over the metal oxide film after performing the heat treatment;
• and
• forming a second insulating film over the conductive film,
• wherein a top surface of the oxide semiconductor film comprises a first region, a second region, and a third region between the first region and the second region,
• wherein each of the first region and the second region is in contact with the second insulating film,
• wherein the conductive film overlaps with the third region with the first insulating film and the metal oxide film therebetween,
• wherein the second insulating film comprises hydrogen, and
• wherein the metal oxide film and the conductive film are collectively configured to be a gate electrode of a transistor.

A method for manufacturing a semiconductor device including a transistor comprises:

• forming an oxide semiconductor film;
• forming a first insulating film over the oxide semiconductor film;
• forming a metal oxide film over and in contact with the first insulating film;
• performing a heat treatment after forming the metal oxide film;
• forming a conductive film over the metal oxide film after performing the heat treatment;
• and
• forming a second insulating film over the conductive film,
• wherein a top surface of the oxide semiconductor film comprises a first region, a second region, and a third region between the first region and the second region,
• wherein each of the first region and the second region is in contact with the second insulating film,
• wherein the conductive film overlaps with the third region with the first insulating film and the metal oxide film therebetween,
• wherein the second insulating film comprises hydrogen, and
• wherein the metal oxide film is formed by sputtering.

A method for manufacturing a semiconductor device including a transistor comprises:

• forming an oxide semiconductor film;
• forming a first insulating film over the oxide semiconductor film;
• forming a metal oxide film over and in contact with the first insulating film;
• performing a heat treatment after forming the metal oxide film;
• forming a conductive film over the metal oxide film after performing the heat treatment;
• and
• forming a second insulating film over the conductive film,
• wherein a top surface of the oxide semiconductor film comprises a first region, a second region, and a third region between the first region and the second region,
• wherein each of the first region and the second region is in contact with the second insulating film,
• wherein the conductive film overlaps with the third region with the first insulating film and the metal oxide film therebetween,
• wherein the second insulating film comprises hydrogen, and
• wherein the first insulating film comprises a fourth region which does not overlap with the conductive film in a channel length direction of the transistor.