Charged particle beam axial alignment device, charged particle beam irradiation device and charged particle beam axial alignment method

A charged particle beam irradiation device comprising:

• a charged particle source that produces a charged particle beam;
• a converging lens that converges the charged particle beam, which is produced by the charged particle source, by a magnetic field;
• a first deflector that adjusts a positional relationship between an axis of the charged particle beam and an optical axis of the converging lens by deflecting the charged particle beam produced by the charged particle source;
• an objective aperture plate that restricts an electric current of the charged particle beam converged by the converging lens;
• a second deflector that adjusts a positional relationship of the charged particle beam on a subject surface by deflecting the charged particle beam converged by the converging lens;
• and
• a charged particle beam axial alignment device that adjusts the axis of the charged particle beam, wherein
• the charged particle beam axial alignment device includes
• a strength changer that alternately and repeatedly changes magnetic field strength of the converging lens between first strength and second strength,
• a producer that produces first information corresponding to a position of a first aperture image indicating an opening of the objective aperture plate when the magnetic field strength is the first strength, and produces second information corresponding to a position of a second aperture image indicating the opening of the objective aperture plate when the magnetic field strength is the second strength,
• a first movement instructor that gives a first movement instruction of the first and second aperture images based on the first information and the second information during repetitive changes between the first strength and the second strength by the strength changer,
• a first deflection controller that controls the first deflector to move the first and second aperture images based on the first movement instruction,
• a second movement instructor that gives a second movement instruction of the first and second aperture images based on the first information and the second information during repetitive changes between the first strength and the second strength by the strength changer, and
• a second deflection controller that controls the second deflector to move the first and second aperture images based on the second movement instruction.

A charged particle beam axial alignment method for adjusting an axis of a charged particle beam in a charged particle beam irradiation device that irradiates an subject surface with a charged particle beam through a first deflector, a converging lens, a second deflector and an objective aperture plate, comprising:

• changing magnetic field strength of the converging lens between first strength and second strength;
• producing first information corresponding to a position of a first aperture image indicating an opening of the objective aperture plate when the magnetic field strength is the first strength, and producing second information corresponding to a position of a second aperture image indicating the opening of the objective aperture plate when the magnetic field strength is the second strength;
• giving a first movement instruction of the first and second aperture images based on the first information and the second information during repetitive changes of the magnetic field strength;
• controlling the first deflector to move the first and second aperture images based on the first movement instruction;
• giving a second movement instruction of the first and second aperture images based on the first information and the second information during repetitive changes of the magnetic field strength;
• and
• controlling the second deflector to move the first and second aperture images based on the second movement instruction.