Method of fabricating semiconductor device

A method of fabricating a semiconductor device, comprising:

• forming on a semiconductor substrate a plurality of gate insulating films having different film thicknesses;
• forming a plurality of gate electrodes on the gate insulating films respectively;
• forming an insulating film for element isolation protruding from a surface of the semiconductor substrate;
• forming an oxide film on an entire surface of the semiconductor substrate with the gate insulating films, the gate electrodes and the element isolation insulating film having been formed;
• opening a forming region for a self-aligned contact hole, exposing thicker gate insulating films around the gate electrodes and a surface of the element isolation insulating film, and forming a resist pattern which is shaped so as to cover regions around the gate electrodes;
• removing the oxide film of the region in which the contact hole is to be formed with the resist pattern serving as a mask, and etching a part of the element isolation insulating film protruding from the surface of the semiconductor substrate so that said part is substantially on a level with the surface of the semiconductor substrate.