Apparatus of plural charged particle beams with multi-axis magnetic lens

A multi-axis charged particle apparatus, comprising:

• a multi-axis electromagnetic compound immersion objective lens comprising:
• a multi-axis magnetic immersion objective lens comprising:
• a pair of parallel magnetic conductor plates with a plurality of through round holes in pairs therein, the pair of parallel magnetic conductor plates including an upper plate and a lower plate, for each paired through round holes, an upper through round hole in the upper plate aligned with a corresponding lower through round hole in the lower plate;
• a plurality of magnetic rings in pairs inside and aligned with the plurality of through round holes with a plurality of first radial gaps in pairs respectively, wherein for each pair of magnetic rings in the pair of parallel magnetic conductor plates respectively, an upper magnetic ring is aligned with and extends downward through inside a corresponding lower magnetic ring with a second radial gap, wherein each paired first radial gaps include a first upper radial gap between inner sidewall of the upper through round hole and outer sidewall of the upper magnetic ring, and a first lower radial gap between inner sidewall of the lower through round hole and outer sidewall of the lower magnetic ring,
• thereby forming a plurality of magnetic sub-lens modules for focusing a plurality of charged particle beams respectively, wherein for each sub-lens module, the upper magnetic ring functions as an inner pole-piece and the corresponding lower magnetic ring functions as an outer pole-piece;
• and
• a common excitation coil located between the pair of parallel magnetic conductor plates for providing magnetic flux to the plurality of magnetic sub-lens modules;
• an upper magnetic shielding plate located above the pair of parallel magnetic conductor plates;
• a lower magnetic shielding plate located below the pair of parallel magnetic conductor plates, wherein the upper and lower magnetic shielding plates have a plurality of circular openings aligned with the plurality of through round holes respectively;
• a specimen located below the lower magnetic shielding plate;
• and
• a plurality of flat electrodes located above the specimen and below the lower magnetic shielding plate with a plurality of circle orifices, wherein the plurality of circle orifices are respectively aligned with the plurality of circular openings in the lower magnetic shielding plate,
• thereby forming a plurality of electrostatic sub-lens modules respectively aligned with the plurality of magnetic sub-lens modules, wherein each electrostatic sub-lens module includes the inner pole-piece, a flat electrode of the plurality of flat electrodes and the specimen as a first electrode, a second electrode, and a third electrode respectively;
• a plurality of deflection scanning and compensation units respectively located inside the plurality of magnetic sub-lens modules in the multi-axis electromagnetic compound immersion objective lens, wherein each of the plurality of deflection scanning and compensation units comprising:
• an upper electrostatic multi-pole lens located at an upper end of and aligned with the inner pole-piece, and generating a dipole field only, or a dipole field as well as a quadrupole field;
• and
• a lower electrostatic multi-pole lens located at a lower end of and aligned with the inner pole-piece, and generating a dipole field only or a dipole field and a quadrupole field,
• thereby forming a deflection scanning unit to scan one of the plurality of charged particle beams on the specimen, and a compensation unit to compensate the influence of the dipole field and the quadrupole field generated by the multi-axis electromagnetic compound immersion objective lens;
• and
• a plurality of sub-columns located over the multi-axis electromagnetic compound immersion objective lens, providing the plurality of charged particle beams, and aligned with the plurality of magnetic sub-lens modules respectively, wherein each of the plurality of sub-columns comprises:
• a charged particle source for generating a charged particle beam;
• a condenser below the charged particle source for condensing the charged particle beam;
• a beam limit aperture below the condenser for confining the charged particle beam;
• a detector below the beam limit aperture for collecting a signal charged particle beam emanated from the specimen;
• a first magnetic shielding tube enclosing a first space between the detector and the upper magnetic shielding plate and aligned with an opening in the upper magnetic shielding plate, wherein a lower end of the first magnetic shielding tube stacks on a top surface of the upper magnetic shielding plate;
• a second magnetic shielding tube enclosing a second space between the condenser and the beam limit aperture;
• a third magnetic shielding tube enclosing the charged particle source and the condenser;
• a fourth magnetic shielding tube enclosing the charged particle source inside the third magnetic shielding tube;
• and
• a magnetic shielding house enclosing the plurality of sub-columns.