Electromagnetic lens, scanning electron microscope, and multi-electron beam inspection apparatus

A scanning electron microscope comprising:

• an electromagnetic lens configured to include
• a coil,
• a yoke, made of magnetic material, which includes an upper wall on an upstream side with respect to an advancing direction of a primary electron beam passing, an outer peripheral wall, an inner peripheral wall, and one of a lower wall in which a gap is formed on a downstream side with respect to the advancing direction of the primary electron beam and an inclined wall in which a gap is formed on a downstream side with respect to the advancing direction of the primary electron beam, which is configured to let the primary electron beam pass through a space surrounded by the inner peripheral wall, and which surrounds the coil by the upper wall, the outer peripheral wall, the inner peripheral wall, and the one of the lower wall and the inclined wall, and
• a cover, made of a non-magnetic conductor, which contacts and covers an end surface of the yoke on the downstream side with respect to the advancing direction of the primary electron beam, the end surface of the yoke including a corner portion on an inner peripheral side, wherein the corner portion of the cover is formed to have a curved surface;
• a stage configured to place thereon a target object which is to be irradiated with the primary electron beam having passed through the electromagnetic lens;
• and
• a detector configured to detect a secondary electron beam emitted from the target object.

An electron beam inspection apparatus comprising:

• an electromagnetic lens configured to include
• a coil,
• a yoke, made of magnetic material, which includes an upper wall on an upstream side with respect to an advancing direction of a primary electron beam passing, an outer peripheral wall, an inner peripheral wall, and one of a lower wall in which a gap is formed on a downstream side with respect to the advancing direction of the primary electron beam and an inclined wall in which a gap is formed on a downstream side with respect to the advancing direction of the primary electron beam, which is configured to let the primary electron beam pass through a space surrounded by the inner peripheral wall, and which surrounds the coil by the upper wall, the outer peripheral wall, the inner peripheral wall, and the one of the lower wall and the inclined wall, and
• a cover, made of a non-magnetic conductor, which contacts and covers an end surface of the yoke on the downstream side with respect to the advancing direction of the primary electron beam, the end surface of the yoke including a corner portion on an inner peripheral side, wherein the corner portion of the cover is formed to have a curved surface;
• a stage configured to place thereon a target object which is to be irradiated with the primary electron beam having passed through the electromagnetic lens;
• and
• a detector configured to detect a secondary electron beam emitted from the target object.