The method involves determining a reference forward scattering intensity on the basis of a forward scattering intensity distribution of a pattern having a minimum design width included in the block pattern. Each pattern width in the block pattern is adjusted such that a width of a forward scattering intensity distribution at the reference forward scattering intensity becomes equal to a corresponding design width. The corrected exposure dose is determined such that a value obtained by multiplying a sum of the reference forward scattering intensity and a backscattering intensity by the corrected exposure dose become equal to each other. Independent claims are also included for the following: a rectangle-to-lattice data conversion method.
Rectangle/lattice data conversion method for charged particle beam exposure mask pattern and charged particle beam exposure method