US 12,339,214 B2
Apparatus for and method of monitoring droplets in a droplet stream
Joshua Mark Lukens, San Diego, CA (US)
Assigned to ASML Netherlands B.V., Veldhoven (NL)
Appl. No. 17/782,695
Filed by ASML Netherlands B.V., Veldhoven (NL)
PCT Filed Nov. 18, 2020, PCT No. PCT/EP2020/082453
§ 371(c)(1), (2) Date Jun. 6, 2022,
PCT Pub. No. WO2021/121837, PCT Pub. Date Jun. 24, 2021.
Claims priority of provisional application 62/951,893, filed on Dec. 20, 2019.
Prior Publication US 2023/0028848 A1, Jan. 26, 2023
Int. Cl. G01N 15/10 (2024.01); G03F 7/00 (2006.01); H05G 2/00 (2006.01)
CPC G01N 15/10 (2013.01) [G03F 7/70033 (2013.01); G03F 7/7055 (2013.01); H05G 2/006 (2013.01)] 26 Claims
OG exemplary drawing
 
1. An apparatus for monitoring a stream of droplets of target material for generating a radiation beam in a radiation source, wherein the apparatus comprises:
a target material emitter configured to create the stream of droplets of target material,
wherein the target material emitter comprises a chamber configured for the target material to pass through;
a first transducer configured to generate acoustic pressures in the chamber and to sense acoustic pressures in the chamber, and
a second transducer configured to sense the acoustic pressures in the chamber.