Multi-electron beam image acquisition apparatus, and multi-electron beam image acquisition method

A multi-electron beam image acquisition apparatus comprising:

• a multiple beam forming mechanism configured to form multiple primary electron beams;
• a primary electron optical system configured to irradiate a target object surface with the multiple primary electron beams;
• a beam separator, arranged at a position conjugate to an image plane of each primary electron beam of the multiple primary electron beams, configured to form an electric field and a magnetic field to be perpendicular to each other, to separate multiple secondary electron beams, emitted from the target object surface due to irradiation with the multiple primary electron beams, from the multiple primary electron beams by using actions of the electric field and the magnetic field, and to have a lens action on the multiple secondary electron beams in at least one of the electric field and the magnetic field;
• a multi-detector configured to detect the multiple secondary electron beams;
• and
• a secondary electron optical system configured to lead the multiple secondary electron beams to the multi-detector,
• wherein the beam separator includes
• a magnetic lens,
• a first set of multipolar magnetic poles, being a first stage, composed of at least two poles,
• a second set of multipolar magnetic poles, being a second stage, composed of at least two poles,
• a first set of multipolar electrodes, being a first stage, composed of at least two poles, arranged at a same height position as that of the first set of the multipolar magnetic poles, and
• a second set of multipolar electrodes, being a second stage, composed of at least two poles, arranged at a same height position as that of the second set of the multipolar magnetic poles.

A multi-electron beam image acquisition method comprising:

• irradiating a target object surface with multiple primary electron beams;
• separating, at a position conjugate to an image plane of each primary electron beam of the multiple primary electron beams, multiple secondary electron beams, which were emitted from the target object surface due to the irradiating with the multiple primary electron beams, from the multiple primary electron beams, and refracting the multiple secondary electron beams in a converging direction at the position conjugate to the image plane;
• further refracting the multiple secondary electron beams which have been separated from the multiple primary electron beams and refracted in the converging direction at the position conjugate to the image plane, in the converging direction at a position away from a trajectory of the multiple primary electron beams;
• and
• detecting the multiple secondary electron beams which have been refracted at the position away from the trajectory of the multiple primary electron beams,
• wherein the multiple secondary electron beams are separated from the multiple primary electron beams and refracted in the converging direction at the position conjugate to the image plane by using a beam separator including
• a magnetic lens,
• a first set of multipolar magnetic poles, being a first stage (upper stage), composed of at least two poles,
• a second set of multipolar magnetic poles, being a second stage (lower stage), composed of at least two poles, and
• a set of electrodes arranged between poles of the first set of the multipolar magnetic poles and poles of the second set of the multipolar magnetic poles, the first set of the multipolar magnetic poles and the second set of the multipolar magnetic poles being arranged symmetrically at upper and lower sides with respect to a magnetic field center position of the magnetic lens.

A multi-electron beam image acquisition method comprising:

• irradiating a target object surface with multiple primary electron beams;
• separating, at a position conjugate to an image plane of each primary electron beam of the multiple primary electron beams, multiple secondary electron beams, which were emitted from the target object surface due to the irradiating with the multiple primary electron beams, from the multiple primary electron beams, and refracting the multiple secondary electron beams in a converging direction at the position conjugate to the image plane;
• further refracting the multiple secondary electron beams which have been separated from the multiple primary electron beams and refracted in the converging direction at the position conjugate to the image plane, in the converging direction at a position away from a trajectory of the multiple primary electron beams;
• and
• detecting the multiple secondary electron beams which have been refracted at the position away from the trajectory of the multiple primary electron beams,
• wherein the multiple secondary electron beams are separated from the multiple primary electron beams and refracted in the converging direction at the position conjugate to the image plane by using a beam separator including
• a magnetic lens,
• a first set of multipolar magnetic poles, being a first stage, composed of at least two poles,
• a second set of multipolar magnetic poles, being a second stage, composed of at least two poles,
• a first set of multipolar electrodes, being a first stage, composed of at least two poles, arranged at a same height position as that of the first set of the multipolar magnetic poles, and
• a second set of multipolar electrodes, being a second stage, composed of at least two poles, arranged at a same height position as that of the second set of the multipolar magnetic poles.