US 12,461,041 B2
Measurement of thick films and high aspect ratio structures
David Y. Wang, Santa Clara, CA (US); and Shankar Krishnan, Cupertino, CA (US)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on Mar. 16, 2023, as Appl. No. 18/185,100.
Claims priority of provisional application 63/332,710, filed on Apr. 20, 2022.
Prior Publication US 2023/0341337 A1, Oct. 26, 2023
Int. Cl. G01N 21/95 (2006.01)
CPC G01N 21/9501 (2013.01) [G01N 2021/9511 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system comprising:
a light source configured to emit light along an illumination path;
a projection optical assembly disposed in the illumination path;
a target disposed in the illumination path, wherein the target is configured to reflect the light along a collection path;
a collection optical assembly disposed in the collection path;
a detector disposed in the collection path, wherein the detector is configured to detect the light reflected from the target and generate an output signal based on the detected light; and
a processor in electronic communication with the detector, wherein the processor is configured to generate a measurement of the target based on the output signal;
wherein the projection optical assembly defines a first numerical aperture at the target and the collection optical assembly defines a second numerical aperture at the target, and the first numerical aperture is slightly larger than the second numerical aperture.