Method of fabricating semiconductor device

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

• forming a first insulation film on a first interconnection;
• forming a coating film on the first insulation film and forming a second insulation film which has been modified by implanting impurities into the coating film;
• forming a third insulation film serving as an etch stopper on the second insulation film;
• forming a coating film on the third insulation film and forming a fourth insulation film which has been modified by implanting impurities into the coating film;
• etching away the fourth insulation film, the third insulation film, and the second insulation film, to form a via hole;
• etching away the fourth insulation film in order to form a recess serving as a trench interconnection portion;
• etching away the third insulation film and the first insulation film which are exposed;
• and
• filling the recess with a conductive material, to form a conductive plug in the via hole and a second interconnection.