Charged-particle beam apparatus equipped with aberration corrector

摘要

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. This control lens makes it possible to correct aberrations more stably and to set an optimum angular aperture when the operator modifies accelerating voltage, working distance, or probe current through a manual operation-and-display portion.