Method for fabricating semiconductor device

A method of fabricating a semiconductor device, comprising the steps of:

• a) forming a doped layer of a first conductivity type within an entire surface of a semiconductor substrate;
• b) depositing an insulating film on the semiconductor substrate after formation of the doped layer of the first conductivity type in the step a), thereafter removing a portion of the insulating film located in a first region where a trench isolation is to be formed, and, then forming the trench isolation in the semiconductor substrate in the first region such that the trench isolation has a bottom lower than that of the doped layer of the first conductivity type;
• c) removing at least the insulating film in a second region where a gate electrode is to be formed, to form a recess in the insulating film, after formation of the trench isolation in the step (b);
• d) forming a gate insulating film on the surface of the semiconductor substrate, which is exposed inside the recess;
• e) forming the gate electrode on the gate insulating film by filling in the recess formed in the insulating film with a conductive film;
• and
• f) forming a contact hole which leads to the doped layer of the first conductivity type, passing through a portion of the insulating film in which portion the gate electrode is not formed, and subsequently forming an extension electrode for the doped layer of the first conductivity type in the contact hole.