Charged particle beam writing apparatus and method thereof

A charged particle beam writing apparatus comprising:

• an emitting unit configured to emit a charged particle beam;
• a stage on which a target workpiece to be written is placed;
• a first correction unit configured to correct a reference position of a small region in a writing region of the target workpiece to be written, by performing a calculation using a coefficient obtained by combining a coefficient of a correction equation for correcting position errors of the small region induced by an optical system for the charged particle beam and a coefficient of a correction equation for correcting global position errors in the whole writing region, and a value of the reference position of the small region in target workpiece coordinates, wherein the correction equation for correcting global position errors is based on a pattern distortion obtained from positions of a plurality of figures spread over substantially all of the writing region of a dummy target workpiece and written without correcting, wherein the position errors of the small region induced by the optical system include distortion of the reference position of the small region induced by the optical system;
• a first deflector configured to deflect the charged particle beam, to a corrected reference position obtained by correcting the reference position;
• a second correction unit configured to correct a relative distance from the corrected reference position to an arbitrary position in the small region, by performing a calculation using a coefficient obtained by combining a coefficient of a correction equation for correcting position errors induced by an optical system in the small region and the coefficient of the correction equation for correcting global position errors in the whole writing region, and the value of the reference position of the small region in the target workpiece coordinates, wherein the position errors induced by the optical system in the small region include distortion of the arbitrary position induced by the optical system;
• and
• a second deflector configured to further deflect the charged particle beam from a position deflected by the first deflector, based on the relative distance corrected.