Method of manufacturing semiconductor device and semiconductor device

A semiconductor device comprising:

• an insulating film formed on a semiconductor substrate;
• a groove formed in the insulating film;
• a first conductive film formed on inner walls of the groove;
• a second conductive film formed on the inner walls via the first conductive film;
• and
• a third conductive film formed so as to cover the upper of the second conductive film,
• wherein the level of the surface of the insulating film near the first conductive film is gradually lowered from a position close to the first conductive film.

A semiconductor device comprising:

• a first insulating film formed on a semiconductor substrate;
• a groove formed in the first insulating film;
• a second insulating film formed on inner walls of the groove;
• a conductive film formed on the inner walls via the second conductive film;
• and
• a third insulating film formed so as to cover the upper of the conductive film,
• wherein the surface of the first insulating film and the surface of the third insulating film in the center portion of the groove are almost at the same level, and the surface of the second insulating film and ends of the third insulating film are higher than the level.