Abstract: In a method of designing cells applicable to different first and second design automation systems, first and second cells circuit-designed by the first and second design automation systems, respectively, are demarcated into a logic function portion and an input/output portion. A plurality of sets of common lithography patterns for the logic function portions of the first and second cells are determined such that each common lithography pattern set is shared by those of the first and second cells which have same logic function in the first and second design automation systems. A first set of lithography patterns for the input/output portions of the first cells in the first design automation system and a second set of lithography patterns for the input/output portions of the second cells in the second design automation system are determined, respectively.