Multi charged particle beam writing apparatus and adjusting method for multi charged particle beam writing apparatus

A multi charged particle beam writing apparatus comprising:

• an emitter emitting a charged particle beam;
• a shaping aperture array including a plurality of opening portions and forming multiple beams by allowing the charged particle beam to pass through the plurality of opening portions:
• a blanking aperture array including a plurality of blankers each configured to perform
• blanking deflection of a corresponding beam of the multiple beams;
• a stage holding a substrate thereon, the substrate being irradiated with the multiple beams;
• an alignment unit disposed between the emitter and the shaping aperture array, the alignment unit including an aperture plate, a detector provided in the aperture plate and detecting charged particles, and an alignment coil adjusting an angle of incidence of the charged particle beam on the aperture plate;
• and
• circuitry configured to
• generate an alignment scan image which visualizes a passage of the charged particle beam through a hole of the aperture plate based on a detection value of the detector and calculate a feature quantity representing a perpendicularity of the angle of incidence of the charged particle beam on the aperture plate;
• and
• control an excitation value of the alignment coil based on the feature quantity;
• wherein the circuitry calculates, as the feature quantity, a value representing uniformity of brightness of the alignment scan image.