US 12,142,456 B2
Self-differential confocal tilt sensor for measuring level variation in charged particle beam system
Jinmei Yang, Beijing (CN); Jian Zhang, San Jose, CA (US); Zhiwen Kang, Milpitas, CA (US); and Yixiang Wang, Fremont, CA (US)
Assigned to ASML NETHERLANDS B.V., Veldhoven (NL)
Appl. No. 17/638,777
Filed by ASML Netherlands B.V., Veldhoven (NL)
PCT Filed Aug. 20, 2020, PCT No. PCT/EP2020/073443
§ 371(c)(1), (2) Date Feb. 25, 2022,
PCT Pub. No. WO2021/037695, PCT Pub. Date Mar. 4, 2021.
Claims priority of application No. PCT/CN2019/103819 (WO), filed on Aug. 30, 2019.
Prior Publication US 2022/0328283 A1, Oct. 13, 2022
Int. Cl. H01J 37/28 (2006.01); G01N 23/2251 (2018.01); H01J 37/26 (2006.01)
CPC H01J 37/28 (2013.01) [G01N 23/2251 (2013.01); H01J 37/265 (2013.01); H01J 2237/20207 (2013.01); H01J 2237/20292 (2013.01); H01J 2237/2482 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a light source configured to irradiate a sample;
a first optical element configured to supply light from the light source in a first direction to the sample and to supply light input to the first optical element in a second direction to a second optical element in a third direction, wherein
the second optical element is configured to supply light in a fourth direction to a first sensing element and to supply light to a third optical element in a fifth direction;
the third optical element, wherein the third optical element is configured to supply light to a second sensing element that is coplanar with the first sensing element in a plane parallel to the sample;
a lens configured to focus light from the light source, wherein the lens is arranged between the second optical element and an aperture; and
the aperture, wherein the aperture is arranged between the third optical element and the second sensing element, and the aperture is arranged at a focal plane of the lens.