Semiconductor Device and Manufacturing Method Thereof

A manufacturing method of a semiconductor device comprising:

• forming an island-shaped semiconductor layer over a substrate;
• forming a first insulating layer to be in contact with a top surface and a side surface of the island-shaped semiconductor layer;
• forming a second insulating layer that is in contact with the side surface of the island-shaped semiconductor layer by selectively removing the first insulating layer until the top surface of the island-shaped semiconductor layer is exposed;
• forming a third insulating layer to be in contact with the top surface of the island-shaped semiconductor layer and the second insulating layer;
• and
• forming a gate electrode layer over the top surface of the island-shaped semiconductor layer with the third insulating layer interposed therebetween and to cross over the island-shaped semiconductor layer.

A manufacturing method of a semiconductor device comprising:

• forming an island-shaped first semiconductor layer over a substrate;
• forming a first insulating layer to be in contact with a top surface and a side surface of the first semiconductor layer;
• forming a second insulating layer that is in contact with the side surface of the first semiconductor layer and forming an amorphous region in an upper layer of the first semiconductor layer, by selectively removing the first insulating layer until the top surface of the first semiconductor layer is exposed;
• forming an island-shaped second semiconductor layer by removing the amorphous region formed in the first semiconductor layer;
• forming a third insulating layer to be in contact with the second semiconductor layer and the second insulating layer;
• and
• forming a gate electrode layer over the top surface of the second semiconductor layer with the third insulating layer interposed therebetween and to cross over the second semiconductor layer.

A manufacturing method of a semiconductor device comprising:

• forming an island-shaped first semiconductor layer over a substrate;
• forming a first insulating layer to be in contact with a top surface and a side surface of the first semiconductor layer;
• forming an island-shaped second semiconductor layer and a second insulating layer that is in contact with the second semiconductor layer, by thinning the first semiconductor layer and the first insulating layer by etching mainly in a vertical direction;
• forming a third insulating layer to be in contact with the second semiconductor layer and the second insulating layer;
• and
• forming a gate electrode layer over the top surface of the second semiconductor layer with the third insulating layer interposed therebetween and to cross over the second semiconductor layer.