MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To provide a method of forming a contact window in a source drain region, where an etching mask pattern is enhanced in aligning margin, the opening of the master pattern correspondent to the contact window can be enlarged in diameter even if the contact window is micronized, and the contact window can accurately be formed. CONSTITUTION:A third insulating film (Si2O film) 6 is formed on all the surface of an Si semiconductor substrate 1 leaving a second insulating film (Si3N4 film) 5 on the side wall of a gate electrode 4. Thereafter, a resist pattern 7 used for providing a contact window 8 is formed through a photolithography technique, and the third insulating film 6 is anisotropically etched for the formation of the contact window 8 under such a condition that the third insulating film 6 (Si2O film) is selectively etched to the second insulating film (Si3N4 film) 5.