Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device comprising steps of:

• (a) preparing a semiconductor substrate of a first conductivity type having an upper surface and a lower surface;
• (b) after the step (a), forming a first hard mask on the upper surface of the semiconductor substrate to selectively cover the upper surface of the semiconductor substrate;
• (c) after the step (b), forming a trench in the semiconductor substrate exposed out from the first hard mask;
• (d) after the step (c), forming a first gate insulating film in the trench;
• (e) after the step (d), forming a first conductive film on the first gate insulating film and the first hard mask;
• (f) after the step (e), removing the first conductive film on the first hard mask and forming a first gate electrode in the trench to be embedded into the trench to interpose the first gate insulating film therebetween by performing anisotropic etching process to the first conductive film;
• (g) after the step (f), forming a first cap film composed of an insulating film on an upper surface of the first gate electrode;
• (h) after the step (g), removing the first hard mask;
• (i) after the step (h), forming a second gate insulating film on the upper surface of the semiconductor substrate;
• (j) after the step (i), forming a second conductive film on the second gate insulating film and the first cap film;
• and
• (k) after the step (j), removing the second conductive film on the first cap film and forming a second gate electrode on the upper surface of the semiconductor substrate to interpose the second gate insulating film therebetween by patterning the second conductive film.