US 12,449,352 B2
Optics for 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 Jun. 15, 2023, as Appl. No. 18/210,558.
Prior Publication US 2024/0418635 A1, Dec. 19, 2024
Int. Cl. G01N 21/31 (2006.01)
CPC G01N 21/31 (2013.01) [G01N 2201/06113 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A spectroscopic metrology system comprising:
an illumination source configured to generate an amount of illumination light including wavelengths less than 150 nanometers;
an illumination optics subsystem configured to direct the amount of illumination light from the illumination source to a measurement spot on a surface of a specimen under measurement at one or more angles of incidence, one or more azimuth angles, or a combination thereof;
a reflective collection optics subsystem configured to collect an amount of collected light from the measurement spot on the surface of the specimen, the reflective collection optics subsystem including a collection mask disposed at or near a pupil plane of the reflective collection optics subsystem and a plurality of reflective relay optical elements, the plurality of reflective relay optical elements configured to image the amount of collected light from the collection mask to a dispersive element of the spectroscopic metrology system with a field demagnification greater than 1.0 in imaging space;
at least one detector having a planar, two-dimensional surface sensitive to incident light, the at least one detector configured to detect the amount of collected light dispersed by the dispersive element and generate output signals indicative of the detected light; and
a computing system configured to generate an estimated value of a parameter of interest of the specimen under measurement based on an analysis of the output signals.