| 摘要 |
PROBLEM TO BE SOLVED: To provide a spherical aberration correction lens system which cancels spherical aberration of an axisymmetric lens having a great aberration coefficient, and an axisymmetric probe formation lens with no spherical aberration. SOLUTION: A charged particle optical lens system is formed of quadrupole lenses of 4 stages, and three aperture electrodes. The aperture electrodes for inducing octopole lens action are arranged between the first and second stages, between the second and third stages, and between the third and fourth stages. Excitation control of the quadrupole lens is actuated to develop concave-convex-concave-convex lens action on an XZ plane, and convex-concave-convex-concave lens action on a YZ plane, and excitation intensity of the respective quadrupole lenses is adjusted so that a charged particle trajectory on the YZ plane intersects with an optical axis once between the quadrupole lenses of the second and third stages, the charged particle trajectories on the XZ plane and YZ plane intersect with an axis behind the quadrupole lens of the last stage so that the charged particle lens system satisfies an axisymmetric lens condition. COPYRIGHT: (C)2009,JPO&INPIT
|
