Patent ID: 7224038

Claim:
A semiconductor device comprising: a semiconductor substrate having a main surface; and an element isolation trench formed on said main surface of said semiconductor substrate, said element isolation trench being substantially filled with an insulator, wherein the trench width of an upper end of said element isolation trench is larger than the trench width of a bottom surface while the length of a side surface located between said upper end and an end of said bottom surface is larger than the length of a straight line connecting said upper end and said end of said bottom surface, and said side surface of said element isolation trench includes: a first side surface located in the vicinity of said upper end of said element isolation trench and formed to be substantially perpendicular to and extending downwardly from said main surface of said semiconductor substrate, a second side surface located in the vicinity of said bottom surface of said element isolation trench and formed to be substantially perpendicular to said main surface of said semiconductor substrate, and a substantially single, straight and linearly inclined third side surface directly connecting said first side surface and said second side surface with each other.