Patent ID: 7821077

Claim:
A semiconductor device comprising: an element isolation structure in which trenches formed in an element isolation region on a semiconductor substrate are filled up with insulating materials; a first conductivity type element formed in a first active region divided by said element isolation structure; and a second conductivity type element formed in a second active region divided by said element isolation structure, said element isolation structure comprising: a first element isolation region of said element isolation region including regions adjacent to a pair of opposed ends of said second active region, said first element isolation region being filled with a first insulating material a second element isolation region of said element isolation; other than said first element isolation region, said second element isolation region being filled with a second insulating material which is sparser than the first insulating material; an upper layer portion of said first element isolation region is filled with said first insulating material; and said first insulating material is an HDP silicon oxide and said second insulating material is nano clustering silica (NCS); and wherein said first element isolation region is entirely surrounded by said first active region, said second active region and said second element isolation region.