Semiconductor device and manufacturing method of semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming a first insulating layer;
• processing the first insulating layer to form a first opening and a second opening;
• forming a first conductive film over the first insulating layer to fill the first opening and the second opening;
• performing CMP treatment on the first conductive film until a top surface of the first insulating layer is exposed, thereby forming, in the first opening, a first conductive layer having a top surface substantially level with the top surface of the first insulating layer and forming, in the second opening, a second conductive layer having a top surface substantially level with the top surface of the first insulating layer;
• processing the first insulating layer to form a third opening between the first conductive layer and the second conductive layer;
• forming a first metal oxide film in contact with the top surface and a side surface of the first conductive layer, the top surface and a side surface of the second conductive layer, and the top surface and a side surface of the first insulating layer, thereby covering the third opening;
• processing the first metal oxide film to form a semiconductor layer in contact with the side surface of the first conductive layer in the third opening, the side surface of the second conductive layer in the third opening, and the side surface of the first insulating layer in the third opening;
• forming a second insulating layer over the semiconductor layer, the first conductive layer, the second conductive layer, and the first insulating layer;
• forming a second conductive film over the second insulating layer;
• and
• processing the second conductive film to form a third conductive layer that comprises a region overlapping with the semiconductor layer in a plan view.