Semiconductor device and method of fabricating the same

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

• forming an ONO film on a semiconductor substrate in which a diffused region is formed;
• forming an interlayer insulating film containing phosphorus on the ONO film;
• forming a contact hole in the interlayer insulating film and the ONO film;
• and
• forming a metal interconnection line on the interlayer insulating film, the metal interconnection line contacting the diffused region via the contact hole, wherein the step of forming the interlayer insulating film includes the steps of:
• forming a first portion of the interlayer insulating film comprising a PSG film provided directly on the ONO film and containing phosphorus in the range of 4.5 wt % to 10.0 wt %;
• and
• forming a second portion of the interlayer insulating film comprising a BPSG film provided on the first portion and containing a total of a phosphorus concentration and a boron concentration equal to or less than 10.0 wt %.