Magnetic multipole device, charged particle beam apparatus, and method of influencing a charged particle beam propagating along an optical axis

A magnetic multipole device for influencing a charged particle beam propagating along an optical axis, comprising:

• a first magnetic deflector for deflecting the charged particle beam in an x-direction, comprising a plurality of first saddle coils with eight first saddle coils;
• and
• a second magnetic deflector for deflecting the charged particle beam in a y-direction perpendicular to the x-direction, comprising a plurality of second saddle coils with eight second saddle coils,
• wherein the plurality of first saddle coils and the plurality of second saddle coils are arranged around the optical axis to provide a 12-pole magnetic corrector structure with 12 poles at uniformly spaced angular intervals, with four of the eight first saddle coils being provided at same angular intervals as four of the eight second saddle coils, resulting in the 12-pole magnetic corrector structure.

A magnetic multipole device for influencing a charged particle beam propagating along an optical axis, comprising:

• a first magnetic deflector for deflecting the charged particle beam in an x-direction, comprising a plurality of first saddle coils;
• and
• a second magnetic deflector for deflecting the charged particle beam in a y-direction perpendicular to the x-direction, comprising a plurality of second saddle coils,
• wherein the plurality of first saddle coils and the plurality of second saddle coils are arranged around the optical axis to provide a 12-pole magnetic corrector structure with 12 poles at uniformly spaced angular intervals,
• the plurality of first saddle coils comprises two sets of first saddle coils arranged on opposite sides of the optical axis in the y-direction, each set comprising four first saddle coils arranged next to each other in a circumferential direction, and
• the plurality of second saddle coils comprises two sets of second saddle coils arranged on opposite sides of the optical axis in the x-direction, each set comprising four second saddle coils arranged next to each other in the circumferential direction.

A method of influencing a charged particle beam propagating along an optical axis, comprising:

• guiding the charged particle beam through a magnetic multipole device that comprises a first magnetic deflector with a plurality of first saddle coils and a second magnetic deflector with a plurality of second saddle coils, wherein the plurality of first saddle coils and the plurality of second saddle coils are arranged around the optical axis in a 12-pole magnetic corrector structure with 12 poles at uniformly spaced angular intervals, the plurality of first saddle coils comprising eight first saddle coils and the plurality of second saddle coils comprising eight second saddle coils, with four of the eight first saddle coils being provided at same angular intervals as four of the eight second saddle coils, resulting in the 12-pole magnetic corrector structure;
• and one or both of
• (i) deflecting the charged particle beam in an x-y-plane by applying an x-deflection current to the first magnetic deflector and a y-deflection current to the second magnetic deflector;
• and
• (ii) correcting one or more beam aberrations of the charged particle beam by individually adjusting currents that flow through the 12 poles for exerting a beam correction field on the charged particle beam.