1. A photomask having a corrected pattern, said corrected pattern having an original feature and first and second auxiliary features for said original feature, said first and second auxiliary features being added to both adjacent corners of said original feature, said both adjacent corners being located at both ends of a first side of said original feature, wherein each of said auxiliary features is a figure of a triangle or a tetragon, said figure having one side which is an extension of said first side, said figure having another side which is a portion of a second side of said original feature, said second side being adjacent to said first side.