Patent ID: 7985517

Claim:
A pattern forming method comprising: forming a resist on a substrate; exposing the resist using a photo mask having a mask pattern to form resist pattern; and etching the substrate using the resist pattern to form a pattern; wherein the mask pattern is determined using a lithography simulation method for estimating an optical image to be formed on a substrate when a mask pattern is transferred onto the substrate, the method comprising: dividing the mask pattern into a plurality of first calculation areas, the plurality of first calculation areas having sizes determined by a range affected by optical proximity effect, the range affected by optical proximity effect being obtained correspondingly to an exposure wavelength, a numerical aperture and an illumination shape which are used in the transferring the mask pattern onto the substrate; dividing the each of the plurality of first calculation areas into a plurality of second calculation areas; calculating a plurality of first electromagnetic field distributions which are formed by illuminating areas of the mask pattern which corresponds to the plurality of second calculation areas with exposure light; obtaining a plurality of second electromagnetic field distributions corresponding to the plurality of first calculation areas by synthesizing the plurality of first electromagnetic field distributions for each of the plurality of first calculation areas; and calculating the optical image to be formed on the substrate by using the plurality of second electromagnetic field distributions.