Method for correcting drift of charged particle beam, and charged particle beam writing apparatus

1. A drift correction method for correcting drifts of a charged particle beam comprising:

determining a representative position of a deflection result range in which the charged particle beam was deflected with respect to a writing direction by a deflector during past writing on a target object, the deflection result range being a range on a surface to be written in the writing direction; and

correcting drift of the charged particle beam based on a drift amount at the representative position of the deflection result range.

2. The method according to claim 1 , further comprising:

measuring the drift amount of the charged particle beam at the representative position of the deflection result range.

3. The method according to claim 1 , further comprising:

measuring drift amounts of the charged particle beam at a plurality of positions in a deflection range of the deflector;

performing fitting of the drift amounts at the plurality of positions in order to acquire an approximate expression; and

calculating a drift amount of the charged particle beam at the representative position based on the approximate expression.

4. The method according to claim 1 , wherein

the charged particle beam irradiates, in order, each of a plurality of stripe regions obtained by virtually dividing a target object serving as a writing target, and

the drift of the charged particle beam is corrected using an average value of drift amounts at representative positions of each deflection result range in which the charged particle beam was deflected, in at least two stripe regions having been irradiated by the charged particle beam in the plurality of stripe regions.

5. The method according to claim 1 , further comprising:

calculating a correction amount for correcting drift of the charged particle beam based on the drift amount at the representative position of the deflection result range.

6. The method according to claim 5 , further comprising:

writing a pattern on a target object by the charged particle beam, wherein:

a writing region of the target object is virtually divided into a plurality of stripe regions,

writing processing is performed in each stripe region of the plurality of stripe regions, and

the drift amount of the charged particle beam is measured after the writing processing has been completed for at least one of the plurality of stripe regions and before starting the writing processing for a next stripe region.

7. The method according to claim 6 , wherein

the correction amount is calculated after the writing processing has been completed for at least one of the plurality of stripe regions and before starting the writing processing for a next stripe region.

8. The method according to claim 7 , wherein

the drift of the charged particle beam is corrected when a first stripe region is written after the correction amount has been calculated.

9. A charged particle beam writing apparatus comprising:

a writing unit that includes a deflector for deflecting a charged particle beam and write a pattern on a target object by the charged particle beam;

a decision unit configured to determine a representative position of a deflection result range in which the charged particle beam was deflected with respect to a writing direction by the deflector during past writing on a target object, the deflection result range being a range on a surface to be written in the writing direction; and

a correction unit configured to correct drift of the charged particle beam based on a drift amount at the representative position of the deflection result range.

10. The apparatus according to claim 9 , further comprising:

a correction amount calculation unit configured to calculate a correction amount for correcting the drift of the charged particle beam based on the drift amount at the representative position of the deflection result range.