Charged particle beam writing apparatus and method thereof

A charged particle beam writing apparatus comprising:

• a fogging electron amount distribution calculation unit configured to calculate a fogging electron amount distribution generated by applying a charged particle beam onto a writing region of a target workpiece having an irradiated region which is irradiated by the charged particle beam and a non-irradiated region which is not irradiated by the charged particle beam;
• a charge amount distribution calculation unit configured to calculate a sum by adding, in the irradiated region, a first charge amount distribution based on a fogging electron amount distribution, a pattern density distribution, a dose distribution, and an irradiation amount distribution, to a second charge amount distribution resulting from a charge decay, and calculate a union of sets of the sum and a third charge amount distribution based on a fogging electron amount distribution in the non-irradiated region, so as to obtain a fourth charge amount distribution;
• a position displacement amount distribution calculation unit configured to calculate a position displacement amount of each writing position due to charge amounts the fourth charge amount distribution, by performing convolution of each charge amount of the fourth charge amount distribution with a response function;
• and
• a writing unit configured to write a pattern on the each writing position where the position displacement amount has been corrected, by using the charged particle beam.

A charged particle beam writing method comprising:

• calculating a charge amount distribution which is charged by irradiation of a charged particle beam onto a writing region of a target workpiece, by using a charge decay amount and a charge decay time constant both of which depend on a pattern area density;
• calculating a position displacement amount of each writing position due to charge amounts of the charge amount distribution, by performing convolution of each charge amount of the charge amount distribution with a response function;
• and
• writing a pattern on the each writing position where the position displacement amount has been corrected, using a charged particle beam.