CPC H01J 37/3177 (2013.01) [H01J 37/145 (2013.01); H01J 37/28 (2013.01); H01J 2237/0453 (2013.01)] | 17 Claims |
1. A charged-particle beam apparatus comprising:
a charged-particle source configured to generate a primary charged-particle beam along a primary optical axis;
a first aperture array comprising a first plurality of apertures configured to generate a plurality of primary beamlets from the primary charged-particle beam;
a condenser lens comprising a plane adjustable along the primary optical axis; and
a second aperture array comprising a second plurality of apertures configured to generate a plurality of probing beamlets,
wherein each of the plurality of probing beamlets comprises a portion of charged particles of a corresponding primary beamlet, and
wherein the portion of the charged particles is determined based on at least a position of the plane of the condenser lens and characteristics of the second aperture array, and
wherein an off-axis aperture of the first plurality of apertures comprises an elongated aperture having a first rounded end close to the primary optical axis and a second rounded end radially opposite from the first rounded end, and wherein a radius of curvature of the first rounded end is smaller than a radius of curvature of the second rounded end.
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