Charge trajectory calculating method, system, and program

A charge trajectory calculating system comprising at least one computer for calculating, by simulation, trajectories of charges scattered by irradiating a target object with a charged beam, the at least one computer comprising:

• a region setting section configured to set a simulation region, which corresponds to an existence region of the target object;
• a region dividing section configured to divide the simulation region into a plurality of segment regions;
• a charge trajectory calculating section configured to calculate, by a Monte Carlo calculation, the trajectories of charges scattered by irradiating an inside of a predetermined segment region with the charged beam;
• a charge distribution calculating section configured to calculate, based on the Monte Carlo calculation, a charge distribution which occurs in the simulation region by irradiating the inside of the predetermined segment region with the charged beam;
• a potential distribution calculating section configured to calculate, based on the charge distribution, a potential distribution which occurs in the simulation region by irradiating the inside of the predetermined segment region with the charged beam;
• an approximate function processing section configured to calculate, based on the potential distribution or the charge distribution, function values of an approximate function of the potential distribution or the charge distribution;
• a potential distribution approximating section configured to calculate, based on the function values of the approximate function, the potential distribution which occurs in the simulation region by irradiating an outside of the predetermined segment region with the charged beam;
• and
• a charge trajectory approximating section configured to calculate, by the Monte Carlo calculation, and based on the potential distribution calculated based on the function values of the approximate function, the trajectories of charges scattered by irradiating the outside of the predetermined segment region with the charged beam.

A computer readable record medium storing a charge trajectory calculating program for making a computer perform a charge trajectory calculating method, which calculates, by simulation, trajectories of charges scattered by irradiating a target object with a charged beam, the method comprising:

• setting a simulation region, which corresponds to an existence region of the target object;
• dividing the simulation region into a plurality of segment regions;
• calculating, by a Monte Carlo calculation, the trajectories of charges scattered by irradiating an inside of a predetermined segment region with the charged beam;
• calculating, based on the Monte Carlo calculation, a charge distribution which occurs in the simulation region by irradiating the inside of the predetermined segment region with the charged beam;
• calculating, based on the charge distribution, a potential distribution which occurs in the simulation region by irradiating the inside of the predetermined segment region with the charged beam;
• calculating, based on the potential distribution or the charge distribution, function values of an approximate function of the potential distribution or the charge distribution;
• calculating, based on the function values of the approximate function, the potential distribution which occurs in the simulation region by irradiating an outside of the predetermined segment region with the charged beam;
• and
• calculating, by the Monte Carlo calculation, and based on the potential distribution calculated based on the function values of the approximate function, the trajectories of charges scattered by irradiating the outside of the predetermined segment region with the charged beam.