Method for acquiring parameter for dose correction of charged particle beam, charged particle beam writing method, and charged particle beam writing apparatus
A parameter acquiring method for dose correction of a charged particle beam includes writing evaluation patterns on a substrate coated with resist; writing, while varying writing condition, a peripheral pattern on a periphery of any different one of the evaluation patterns, after an ignorable time as to influence of resist temperature increase due to writing of an evaluation pattern concerned has passed; and calculating a parameter for defining correlation among a width dimension change amount of the evaluation pattern concerned, a temperature increase amount of the evaluation pattern concerned, and a backscatter dose reaching the evaluation pattern concerned, by using, under each writing condition, a width dimension of the evaluation pattern concerned, the temperature increase amount of the evaluation pattern concerned at each shot time, and the backscatter dose reaching the evaluation pattern concerned from each shot.
1. A charged particle beam writing method comprising:
extracting information on a type of resist coated on a writing target substrate;
reading out a corresponding correlation parameter which corresponds to the resist of an extracted type from a storage device which stores, for each type of the resist, a correlation parameter for a width dimension change amount of a figure pattern, a temperature increase amount of the figure pattern, and a backscatter dose reaching the figure pattern, and calculating the width dimension change amount of the figure pattern by using the correlation parameter when writing the figure pattern under a predetermined writing condition by using a charged particle beam;
determining, using the width dimension change amount, whether it is necessary to correct a dose of the charged particle beam when writing, under the predetermined writing condition, the figure pattern by using the charged particle beam;
calculating a correction coefficient for correcting the dose of the charged particle beam for writing the figure pattern when it is determined that correction of the dose is needed;
correcting, using the correction coefficient, the dose of the charged particle beam for writing the figure pattern; and
writing, under the predetermined writing condition, the figure pattern on the writing target substrate by using the charged particle beam of the dose having been corrected.
2. The method according to claim 1 , further comprising:
calculating the backscatter dose which reaches a shot position of the figure pattern from each of a plurality of shots of the charged particle beam in a case where the shot position of the figure pattern exists in an influence range of a proximity effect due to the each of the plurality of shots; and
calculating the temperature increase amount at the shot position of the figure pattern, which is increased due to heat transferred from another shot, at each shot time of the plurality of shots, wherein
the width dimension change amount of the figure pattern is calculated using the temperature increase amount at the shot position of the figure pattern at the each shot time, the backscatter dose reaching from a shot concerned at the each shot time to the shot position of the figure pattern, and the correlation parameter, and
the correction coefficient is calculated so that the width dimension change amount of the figure pattern which has been calculated using the correlation parameter is corrected.
3. The method according to claim 1 , wherein
the backscatter dose and the temperature increase amount at the shot position of the figure pattern at reaching time of the backscatter dose are calculated whenever the backscatter dose resulting from another shot reaches the shot position of the figure pattern, and
the width dimension change amount of the figure pattern is calculated using a sum of products of the backscatter dose with respect to all of the another shot whose backscatter dose reaches the shot position of the figure pattern, and the temperature increase amount at the reaching time.