US 11,854,765 B2
Multiple charged-particle beam apparatus and methods
Weiming Ren, San Jose, CA (US); Xuedong Liu, San Jose, CA (US); Xuerang Hu, San Jose, CA (US); Zhong-wei Chen, San Jose, CA (US); and Martinus Gerardus Johannes Maria Maassen, San Francisco, CA (US)
Assigned to ASML Netherlands B.V., Veldhoven (NL)
Filed by ASML Netherlands B.V., Veldhoven (NL)
Filed on May 28, 2020, as Appl. No. 16/885,872.
Claims priority of provisional application 62/984,760, filed on Mar. 3, 2020.
Claims priority of provisional application 62/853,670, filed on May 28, 2019.
Prior Publication US 2020/0381211 A1, Dec. 3, 2020
Int. Cl. H01J 37/317 (2006.01); H01J 37/145 (2006.01); H01J 37/28 (2006.01)
CPC H01J 37/3177 (2013.01) [H01J 37/145 (2013.01); H01J 37/28 (2013.01); H01J 2237/0453 (2013.01)] 17 Claims
OG exemplary drawing
 
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.