US Patent 7297450 Optical proximity correction method

An integrated circuit layout includes dense figures and at least one isolated figure. A plurality of dummy patterns are formed to surround the isolated figure, so as to reduce the difference in pattern density of the integrated circuit layout. A transmitted light of the dummy patterns provides a phase difference of 0 or 180 degrees relative to a transmitted light of the integrated circuit layout. The integrated circuit layout and the plurality of dummy patterns are formed on a photo-mask.