Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device including a MOS capacitive element and a MOS transistor element, the method comprising:

• forming a first insulating film and a second insulating film on a main surface of a semiconductor substrate;
• forming an electrode material on the main surface of the semiconductor substrate so as to cover the first insulating film and the second insulating film, the electrode material having a first portion and a second portion;
• wherein the first portion of the electrode material is located on the first insulating film, and the second portion of the electrode material is located on the second insulating film;
• forming a first impurity region in the semiconductor substrate by implanting an impurity into the first portion of the electrode material and a portion of the semiconductor substrate located under the first portion of the electrode material in a state where the second portion of the electrode material is covered with a mask;
• and
• forming a first electrode from the first portion and forming a second electrode from the second portion by processing the electrode material,
• wherein the MOS capacitive element includes the first impurity region, the first insulating film, and the first electrode,
• wherein the MOS transistor element includes a second impurity region disposed in the semiconductor substrate, the second insulating film, and the second electrode, and
• wherein an impurity concentration in the first electrode is higher than an impurity concentration in the second electrode.