A method for creating a photolithography mask from a set of initial mask cells arranged to form an initial mask. The set includes first and second initial mask cells having a mask element in common within an initial region of the initial mask. The method includes a creation of a first modified mask cell and of a second modified mask cell including OPC processing operations, a comparison of the position of the mask element in common between the first modified mask cell and the second modified mask cell, and if the result of the comparison is greater than a threshold, a creation of a new mask region including an optical proximity correction processing operation on the initial region, and a creation of the photolithography mask from the new mask region.