Method of manufacturing a semiconductor device

A method of manufacturing a semiconductor device comprising a transistor and a capacitor, both being formed in a single substrate, the method comprising the steps of:

• forming an isolation oxide film on a silicon substrate;
• forming a pad oxide film on an active region of the silicon substrate;
• forming a lower electrode of the capacitor on the isolation oxide film;
• forming a silicon nitride film on entire surface of the silicon substrate so as to cover the lower electrode;
• forming a mask on the silicon nitride film so as to cover only the area in the vicinity of the lower electrode;
• patterning the silicon nitride film through use of the mask by means of wet etching capable of selectively removing a silicon nitride film;
• removing the pad oxide film through wet etching capable of selectively removing silicon oxide, after patterning of the silicon nitride film;
• forming a gate oxide film on the active region, after removal of the pad oxide film;
• forming a gate electrode on the gate oxide film;
• and
• forming an upper electrode of the capacitor on the patterned silicon nitride film.