Patent ID: 7897467

Claim:
A method of manufacturing a semiconductor integrated circuit device having a first MISFET for use as a selecting MISFET of a memory cell formed in a first region of a semiconductor substrate; and a second MISFET formed in a second region of the semiconductor substrate, the method comprising: (a) forming a first insulating film over the first and second regions; (b) after the step (a), removing the first insulating film over the second region, wherein the first insulating film over the first region is kept; (c) after the step (b), forming a second insulating film over the second region; (d) after the step (c), forming a third insulating film, a first portion of the third insulating film being formed over the first insulating film of the first region and a second portion of the third insulating film being formed over the second insulating film of the second region; and (e) after the step (d), forming a first gate electrode of the first MISFET over the first portion of the third insulating film and forming a second gate electrode of the second MISFET over the second portion of the third insulating film, wherein a first gate insulating film of the first MISFET is comprised of the first insulating film and the first portion of the third insulating film, wherein a second gate insulating film of the second MISFET is comprised of the second insulating film and the second portion of the third insulating film, wherein the first and second insulation films include silicon, oxygen, and nitrogen, wherein the first and second portions of the third insulation film of the first and second MISFETs, respectively, have a greater dielectric constant than each of the first and second insulation films, wherein a thickness of the first insulation film is larger than a thickness of the second insulation film, and wherein thicknesses of the first and second portions of the third insulation film of the first and second MISFETs, respectively, are larger than the thicknesses of the first insulation film and the second insulation film, respectively.