Method of acquiring offset deflection amount for shaped beam and lithography apparatus

A lithography apparatus comprising:

• an emitting unit configured to emit a charged particle beam for forming shots of charged particle beams;
• first and second shaping aperture plates configured to shape the charged particle beams of the shots into first and second figures;
• a stage configured to be arranged a mark thereon;
• a first forming unit configured to form reference images of the first and second figures;
• a second forming unit configured to form a reference image of the mark using design data of the mark;
• a third forming unit configured to form a first convolution reference image obtained by a convolution calculation of a reference image of the mark and the reference image of the first figure and a second convolution reference image obtained by a convolution calculation of the reference image of the mark and the reference image of the second figure;
• a deflector configured to respectively scan over the mark by using the charged particle beams having shaped into the first and second figures;
• a detector configured to detect reflected electrons from the mark;
• an optical image acquiring unit configured to acquire optical images of the first and second figures using output values from the detector;
• a fourth forming unit configured to form a first convolution synthesis image obtained by a convolution calculation of the first convolution reference image and the optical image of the first figure and a second convolution synthesis image obtained by a convolution calculation of the second convolution reference image and the optical image of the second figure;
• a first calculating unit configured to calculate center-of-gravity positions of the first and second convolution synthesis images;
• and
• a second calculating unit configured to calculate an offset deflection amount for the charged particle beam having shaped into the second figure to match reference positions of the first and second figures based on the center-of-gravity positions of the first and second convolution synthesis images.