Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device including a first field effect transistor (Qa) formed in a first region (1A) of a semiconductor substrate (1), and a second field effect transistor (Qb) formed in a second region (1B), which is different from the first region, of the semiconductor substrate, comprising:

• (a) preparing the semiconductor substrate including an insulating film (2) formed on the semiconductor substrate in the first region, and a semiconductor layer (3) formed on the insulating film, the semiconductor substrate in the second region being exposed from the insulating film and the semiconductor layer;
• (b) after the (a), forming a first gate electrode (7a) of the first field effect transistor on the semiconductor layer via a first gate insulating film (6a), and forming a second gate electrode (7b) of the second field effect transistor on the semiconductor substrate in the second region via a second gate insulating film (7b);
• (c) after the (b), forming a first silicon nitride film (12a) on each of the side surface of the first gate electrode, the semiconductor substrate in the second region, and the side surface of the second gate electrode;
• and
• (d) after the (c), forming an epitaxial layer (14) on the semiconductor layer exposed from each of the first gate electrode and the first silicon nitride film in a state that the semiconductor substrate in the second region is covered with the first silicon nitride film.