Method for manufacturing semiconductor device including a MOS-type transistor

A method for manufacturing a semiconductor device comprising:

• laminating an oxide film layer and a semiconductor layer of a first-conductive-type on a semiconductor layer of a second-conductive-type in order;
• forming an active region of the first-conductive-type in the semiconductor layer of the first-conductive-type;
• forming an insulating film on the semiconductor layer of the first-conductive-type;
• forming a first region of the first-conductive-type by diffusing, based on a position of the active region of the first-conductive-type, an impurity of the first-conductive-type within a first region of the semiconductor layer of the second-conductive-type that includes a lower portion of the active region of the first-conductive-type;
• forming a MOS-type transistor in the active region of the first-conductive-type;
• removing the oxide film layer from a predetermined region, the predetermined region being a region of the semiconductor layer of the first-conductive-type in which a first electrode, a second electrode and a third electrode are to be formed;
• forming, in the first region of the first-conductive-type, a second region of the first-conductive-type by diffusing the impurity of the first-conductive-type within the predetermined region from which the oxide film layer has been removed and on which the first electrode is to be formed and, forming a third region of the first-conductive-type by diffusing the impurity of the first-conductive-type within the predetermined region on which the third electrode is to be formed;
• forming a region of the second-conductive-type by diffusing an impurity of the second-conductive-type within the predetermined region from which the oxide film layer has been removed and in which the second electrode is to be formed;
• and
• forming the first electrode, the second electrode and the third electrode.