Method for manufacturing semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming an oxide film on one surface of a semiconductor substrate;
• forming a first conductor film on the oxide film;
• implanting a P-type impurity from a region where the first conductor film is formed on the one surface of the semiconductor substrate toward an inside of the semiconductor substrate with a first acceleration energy;
• forming a nitride film provided with a first opening on the first conductor film;
• forming an insulating film that covers a side surface of the first opening of the nitride film and is provided with a second opening from which the first conductor film is exposed;
• forming a second conductor film to fill the second opening of the insulating film;
• removing the nitride film and a portion of the first conductor film positioned below the nitride film to expose the oxide film in a peripheral area of a formation region of the insulating film on the one surface of the semiconductor substrate;
• and
• implanting the P-type impurity from a region from which the oxide film is exposed of the one surface of the semiconductor substrate toward an inside of the semiconductor substrate with a second acceleration energy smaller than the first acceleration energy.