US 11,913,874 B2
Optical metrology tool equipped with modulated illumination sources
Andrei V. Shchegrov, Campbell, CA (US); Lawrence D. Rotter, Pleasanton, CA (US); David Y. Wang, Santa Clara, CA (US); Andrei Veldman, Sunnyvale, CA (US); Kevin Peterlinz, Fremont, CA (US); Gregory Brady, San Jose, CA (US); and Derrick A. Shaughnessy, San Jose, CA (US)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on Apr. 5, 2021, as Appl. No. 17/222,330.
Application 16/284,950 is a division of application No. 15/217,549, filed on Jul. 22, 2016, granted, now 10,215,688, issued on Feb. 26, 2019.
Application 17/222,330 is a continuation of application No. 16/284,950, filed on Feb. 25, 2019, granted, now 10,969,328.
Application 15/217,549 is a continuation of application No. 13/648,768, filed on Oct. 10, 2012, granted, now 9,400,246, issued on Jul. 26, 2016.
Claims priority of provisional application 61/545,965, filed on Oct. 11, 2011.
Prior Publication US 2021/0223166 A1, Jul. 22, 2021
Int. Cl. G01N 21/21 (2006.01); G03F 7/00 (2006.01); G01B 11/06 (2006.01); G01N 21/47 (2006.01); G01N 21/55 (2014.01)
CPC G01N 21/211 (2013.01) [G01B 11/0616 (2013.01); G01N 21/4738 (2013.01); G01N 21/55 (2013.01); G03F 7/70608 (2013.01); G03F 7/70625 (2013.01); G03F 7/70633 (2013.01); G01N 2021/213 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An optical metrology tool, comprising:
a modulatable pumping source configured to generate illumination beam;
a plasma cell, the plasma cell including a bulb for containing a volume of gas;
a set of optical elements configured to shape the illumination beam and focus the illumination beam from the modulatable pumping source into the volume of gas in order to maintain a plasma within the volume of gas;
a set of illumination optics configured to direct the illumination beam from the plasma cell to the surface of a sample;
a set of collection optics;
a detector configured to detect at least a portion of illumination emanating from a surface of a sample, wherein the set of collection optics is configured to direct illumination from the surface of the sample to the detector;
a pump control system communicatively coupled to the modulatable pumping source, wherein the pump control system includes one or more processors configured to execute program instructions maintained on a carrier medium configured to cause the pump control system to modulate a drive current of the modulatable pumping source at a selected modulation frequency in order to produce time-varying characteristics within the plasma contained within the plasma cell.