Patent ID: 8234596

Claim:
A mask pattern data creating method comprising: acquiring a first simulation result obtained by applying process simulation to a first mask pattern data based on a first evaluation target cell pattern on evaluation target data, by using a computer; evaluating, whether marginal error patterns as sections in the first evaluation target cell pattern having insufficient margins are present using the first simulation result; extracting the marginal error patterns; creating a second evaluation target cell pattern with deteriorating transfer fidelity pattern in which a deteriorating transfer fidelity pattern is arranged with respect to the marginal error patterns such that a second simulation result obtained when a second mask data pattern is created and the process simulation is applied to the second mask pattern data is more deteriorated than the first simulation result; and determining whether a fatal error is present using a result obtained by applying the process simulation to the second mask pattern data based on the second evaluation target cell pattern with deteriorating transfer fidelity pattern and correcting, when the fatal error is present, the second evaluation target cell pattern including the marginal error patterns or the second mask pattern data based on the second evaluation target cell pattern.