US 12,451,321 B2
Apparatus for obtaining optical measurements in a charged particle apparatus
Jan-Gerard Cornelis Van Der Toorn, Eindhoven (NL); and Zhong-wei Chen, San Jose, CA (US)
Assigned to ASML Netherlands B.V., Veldhoven (NL)
Appl. No. 17/420,123
Filed by ASML Netherlands B.V., Veldhoven (NL)
PCT Filed Dec. 19, 2019, PCT No. PCT/EP2019/086461
§ 371(c)(1), (2) Date Jun. 30, 2021,
PCT Pub. No. WO2020/141091, PCT Pub. Date Jul. 9, 2020.
Claims priority of provisional application 62/786,905, filed on Dec. 31, 2018.
Prior Publication US 2022/0084777 A1, Mar. 17, 2022
Int. Cl. H01J 37/09 (2006.01); H01J 37/00 (2006.01); H01J 37/22 (2006.01)
CPC H01J 37/09 (2013.01) [H01J 37/00 (2013.01); H01J 37/226 (2013.01); H01J 2237/026 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An article, comprising:
a substantially planar plate comprising an electrically conductive material and structure defining a through aperture, the through aperture configured to be positioned above a conductive surface of a wafer stage; and
a field shaping element positioned at the through aperture, the field shaping element being configured to counteract effects of the through aperture on an electric field near the substantially planar plate to minimize or prevent a component of the electrical field from being tangential to the conductive surface of the wafer stage, the field shaping element being electrically conductive and transmissive to light.