Method of fabricating a stacked oxide material for thin film transistor

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

• forming a first electrode over a substrate;
• forming a first oxide semiconductor film over the first electrode;
• performing first heat treatment to the first oxide semiconductor film to cause crystal growth from a surface to an inside portion of the first oxide semiconductor film;
• forming a second oxide semiconductor film over the first oxide semiconductor film;
• forming a conductive film over the second oxide semiconductor film;
• performing second heat treatment to the second oxide semiconductor film to cause crystal growth in the second oxide semiconductor film;
• forming a second electrode by etching the conductive film;
• etching the first oxide semiconductor film and the second oxide semiconductor film so as to have an island shape;
• forming a gate insulating film covering the first electrode, the first oxide semiconductor film, the second oxide semiconductor film and the second electrode;
• and
• forming a gate electrode over the gate insulating film.

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

• forming a first electrode over a substrate;
• forming a first oxide semiconductor film over the first electrode;
• performing first heat treatment to the first oxide semiconductor film to cause crystal growth from a surface to an inside portion of the first oxide semiconductor film;
• forming a second oxide semiconductor film having crystallinity over the first oxide semiconductor film by a sputtering method while heating is performed;
• etching the first oxide semiconductor film and the second oxide semiconductor film so as to have an island shape;
• forming a second electrode over the second oxide semiconductor film;
• forming a gate insulating film covering the first electrode, the first oxide semiconductor film, the second oxide semiconductor film, and the second electrode;
• and
• forming a gate electrode over the gate insulating film.

A semiconductor device comprising:

• a first electrode formed over a substrate;
• a stacked body of an oxide semiconductor formed over the first electrode, the stacked body comprising:
• a first oxide semiconductor film having crystallinity with a crystal grown from a surface to an inside portion;
• and
• a second oxide semiconductor film having crystallinity over the first oxide semiconductor film;
• a second electrode formed over the stacked body of the oxide semiconductor;
• a gate insulating film covering the first electrode, the stacked body of the oxide semiconductor, and the second electrode;
• and
• a third electrode having a ring shape and facing at least a side surface of the stacked body of the oxide semiconductor with the gate insulating film provided therebetween.

A semiconductor device comprising:

• a first electrode formed over a substrate;
• a stacked body of an oxide semiconductor formed over the first electrode, the stacked body comprising:
• a first oxide semiconductor film having crystallinity with a crystal grown from a surface to an inside portion;
• and
• a second oxide semiconductor film having crystallinity over the first oxide semiconductor film;
• a second electrode being over the stacked body of the oxide semiconductor and being formed inside a periphery of the stacked body of the oxide semiconductor;
• a gate insulating film covering the first electrode, the stacked body of the oxide semiconductor, and the second electrode;
• and
• a third electrode having a ring shape and facing at least a side surface of the stacked body of the oxide semiconductor and a side surface of the second electrode with the gate insulating film provided therebetween.