Abstract: On a charged-particle optical system for achieving optimum aberration correction and obtaining a minimum probe diameter, the optical system focuses a beam of charged particles onto a surface of a specimen, and has four stages of multipole elements arranged along the optical axis of the beam, power supplies capable of supplying five or more independent octopole electric or magnetic potentials, and a control portion for correcting third-order aperture aberrations by adjusting the five or more independent octopole electric or magnetic potentials independently. The power supplies apply normal octopole electric or magnetic potentials to at least three of the four stages of multipole elements independently and apply skew octopole electric or magnetic potentials to at least two of the multipole elements independently.

Abstract: A charged particle beam instrument capable of reducing the spread of the probe diameter while maintaining the probe current constant. An electrical current Id is detected by a detection aperture to create a feedback signal. The feedback signal is supplied to a condenser lens control and to an objective lens control via a signal adjuster. The objective lens control portion controls the objective lens such that the charged particle probe is in focus.

Abstract: An aberration correction method and charged-particle beam instrument with four stages of multipole units. The two central stages of multipole units function as two stages of magnetic quadrupole components for superimposing a magnetic potential distribution analogous with an applied electric potential distribution on this electric potential distribution. The instrument further includes an objective lens, an objective aperture mounted in the optical path for a beam of charged particles, an operation portion for varying the accelerating voltage or the working distance between the objective lens and a specimen, and a control portion for controlling the multipole units according to an operation of the operation portion.

Abstract: A charged-particle beam instrument with an aberration corrector which comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central quadrupole elements of the four stages of electrostatic quadrupole elements on this electric potential distribution, and four stages of electrostatic octopole elements for superimposing an electric octopole potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements.

Abstract: Particle-beam apparatus is realized which is equipped with an aberration corrector capable of controlling the angular aperture of a particle beam after performing aberration correction. The corrector comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central stages of the electrostatic quadrupole elements, and four stages of electrostatic octupole elements for superimposing an octupole electric potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements. An objective lens is located downstream of the corrector. An objective aperture is located upstream of the corrector. An angular aperture control lens is located downstream of the objective aperture to control the angular aperture of the probe hitting a specimen surface.

Abstract: An aberration correction method and charged-particle beam instrument with four stages of multipole units. The two central stages of multipole units function as two stages of magnetic quadrupole components for superimposing a magnetic potential distribution analogous with an applied electric potential distribution on this electric potential distribution. The instrument further includes an objective lens, an objective aperture mounted in the optical path for a beam of charged particles, an operation portion for varying the accelerating voltage or the working distance between the objective lens and a specimen, and a control portion for controlling the multipole units according to an operation of the operation portion.

Abstract: On a charged-particle optical system for achieving optimum aberration correction and obtaining a minimum probe diameter, the optical system focuses a beam of charged particles onto a surface of a specimen, and has four stages of multipole elements arranged along the optical axis of the beam, power supplies capable of supplying five or more independent octopole electric or magnetic potentials, and a control portion for correcting third-order aperture aberrations by adjusting the five or more independent octopole electric or magnetic potentials independently. The power supplies apply normal octopole electric or magnetic potentials to at least three of the four stages of multipole elements independently and apply skew octopole electric or magnetic potentials to at least two of the multipole elements independently.

Abstract: An aberration corrector comprises four stages of electrostatic quadrupole elements, two stages of electrostatic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central ones of the four stages of the electrostatic quadrupole elements on the electric potential distribution, an objective lens, a manual operation portion permitting a user to modify the accelerating voltage or the working distance, a power supply for supplying voltages to the four stages of electrostatic quadrupole elements, a power supply for exciting the two stages of magnetic quadrupole elements, a power supply for the objective lens, and a control portion for controlling the power supplies according to a manual operation or setting performed on the manual operation portion.

Abstract: A charged-particle beam instrument with an aberration corrector which comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central quadrupole elements of the four stages of electrostatic quadrupole elements on this electric potential distribution, and four stages of electrostatic octopole elements for superimposing an electric octopole potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements.

Abstract: Particle-beam apparatus is realized which is equipped with an aberration corrector capable of controlling the angular aperture of a particle beam after performing aberration correction. The corrector comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central stages of the electrostatic quadrupole elements, and four stages of electrostatic octupole elements for superimposing an octupole electric potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements. An objective lens is located downstream of the corrector. An objective aperture is located upstream of the corrector. An angular aperture control lens is located downstream of the objective aperture to control the angular aperture of the probe hitting a specimen surface.

Abstract: An aberration corrector comprises four stages of electrostatic quadrupole elements, two stages of electrostatic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central ones of the four stages of the electrostatic quadrupole elements on the electric potential distribution, an objective lens, a manual operation portion permitting a user to modify the accelerating voltage or the working distance, a power supply for supplying voltages to the four stages of electrostatic quadrupole elements, a power supply for exciting the two stages of magnetic quadrupole elements, a power supply for the objective lens, and a control portion for controlling the power supplies according to a manual operation or setting performed on the manual operation portion.

Abstract: A charged particle beam instrument capable of reducing the spread of the probe diameter while maintaining the probe current constant. An electrical current Id is detected by a detection aperture to create a feedback signal. The feedback signal is supplied to a condenser lens control and to an objective lens control via a signal adjuster. The objective lens control portion controls the objective lens such that the charged particle probe is in focus.

Abstract: An electron microscope capable of switching its depth-of-focus mode between a first and a second mode. The microscope includes an electron gun, a first condenser lens, a second condenser lens, an objective aperture, scan coils, and an objective lens arranged in this order in the direction of travel of the electron beam. The mode is switched by changing the excitation of the first and second condenser lenses and of the objective lens so that the electron beam is in focus at the specimen surface. The distance a between the principal plane of the objective lens and the focal point of the second condenser lens in the first mode and the distance b between the principal plane of the objective lens and the focal point of the second condenser lens in the second mode are set sufficiently larger than the maximum distance w.sub.2 between the principal plane of the objective lens and the specimen.