| 摘要 |
<p>A charged particle beam system equipped with a higher-order aberration corrector (C) capable of correcting fifth-order spherical aberration and third-order chromatic aberration such that the primary trajectory (36) of an electron beam is not affected by the strength of a transfer lens (40). The corrector is so adjusted that the image point (42) of the corrector is located at a position shifted a distance of L0 from the principal plane (38) of an objective lens (24) toward the electron source. The transfer lens is so disposed that the position of the principal plane is coincident with the image point of the corrector. Therefore, the primary trajectory of the electron beam passes through the center of the transfer lens. Consequently, the primary trajectory is not affected by the strength of the transfer lens. Under this condition, the strength of the transfer lens is so set that an aberration generation point (33) in the corrector is projected at the front focal point (34) of the objective lens. Thus, the fifth-order spherical aberration and third-order chromatic aberration are corrected.</p> |
