Semiconductor device and manufacturing method of semiconductor device

A method for manufacturing a semiconductor device, comprising

• forming a first insulating film;
• forming an oxide film over the first insulating film;
• performing first heat treatment;
• forming a first conductive film and a second insulating film sequentially over the oxide film;
• processing the first insulating film, the oxide film, the first conductive film, and the second insulating film into island shapes to form a first insulator, an oxide, a conductive layer, and a first insulating layer;
• forming a second insulator over the first insulator, the oxide, the conductive layer, and the first insulating layer;
• forming a third insulator over the second insulator;
• forming an opening reaching the oxide, in the conductive layer, the first insulating layer, the second insulator, and the third insulator, thereby forming a first conductor and a second conductor from the conductive layer and a fourth insulator and a fifth insulator from the first insulating layer;
• performing second heat treatment;
• forming a third insulating film over the third insulator and the opening;
• forming a fourth insulating film over the third insulating film;
• forming a fifth insulating film over the fourth insulating film;
• performing microwave treatment;
• forming a second conductive film over the fifth insulating film;
• and
• performing CMP treatment on the third insulating film, the fourth insulating film, the fifth insulating film, and the second conductive film until a top surface of the third insulator is exposed, to form a sixth insulator, a seventh insulator, an eighth insulator, and a third conductor,
• wherein the step of forming the fourth insulating film is performed by a PEALD method using a qas containing silicon but not containing hydrocarbon, an oxidizing gas, and a dilution gas.