METHOD FOR DECIDING DIFFUSION RESISTANCE CALCULATING EXPRESSION FOR IMPURITY DIFFUSION LAYER IN LSI CIRCUIT DESIGN

PROBLEM TO BE SOLVED: To decide an optimum diffusion resistance calculation expression for impurity diffusion layer at the time of designing an LSI circuit. SOLUTION: A graphic constituting a layout L is extracted by a graphic extraction part 11. In a calculation expression storing table T, plural calculation expressions for calculating the diffusion resistance of impurity diffusion layer are prepared and each calculation expression is successively selected by a calculation expression selection part 13 to be given to a parameter extraction part 12. The parameter extraction part 12 applies the respective calculation expressions to a graphic constituting the impurity diffusion layer to obtain a diffusion resistance value as a parameter. A net list N is prepared through the use of this parameter and circuit simulation is executed by a circuit simulator 20 to obtain a delay time as a characteristic value V. On the other hand, an actual device is produced based on the layout L to obtain the device measurement value M of the delay time to select the characteristic value V closest to this measured value M by a comparator 30 and the calculation expression used to obtain the selected characteristic value V is decided to be the optimum calculation value.