Electron beam apparatus

Abstract

Secondary electrons emitted from a sample (W) by an electron beam irradiation is deflected by a beam separator (77), and is deflected again in a perpendicular direction by an aberration correction electrostatic deflector (711) to form a magnified image on the principal plane of an auxiliary lens (712). The secondary electron beam diverged from the auxiliary lens (712) passes through axial chromatic aberration correction lenses (714-717) and images on a principal plane of an auxiliary lens (718) for a magnifying lens (719). The magnified image is formed in a position spaced apart from the optical axis. Therefore, when the secondary electron beam diverged from the auxiliary lens (712) is incident on the axial chromatic aberration correction lenses without any change, large abaxial aberration occurs. To avoid it, the auxiliary lens (712) is used to form the image of an NA aperture (724) in substantially a middle (723) in the light axis direction of the axial chromatic aberration correction lenses (714-717).

Dependencies are inferred from the claim text.