US 12,487,175 B2
Three-dimensional imaging with enhanced resolution
Xiumei Liu, Fremont, CA (US); and Mark S. Wang, San Ramon, CA (US)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on Jan. 5, 2022, as Appl. No. 17/568,995.
Claims priority of provisional application 63/146,749, filed on Feb. 8, 2021.
Prior Publication US 2022/0252512 A1, Aug. 11, 2022
Int. Cl. G01N 21/47 (2006.01); G01B 11/27 (2006.01); G01B 21/04 (2006.01); G01N 21/17 (2006.01)
CPC G01N 21/4788 (2013.01) [G01B 11/272 (2013.01); G01B 21/045 (2013.01); G01N 21/1717 (2013.01); G01N 2021/1785 (2013.01)] 50 Claims
OG exemplary drawing
 
20. An imaging system comprising:
an imaging metrology tool, wherein aberration correction of the imaging metrology tool is adjustable within three or more degrees of freedom, wherein the imaging metrology tool comprises:
a translation stage for securing a sample;
an illumination source;
one or more illumination optics to direct illumination from the illumination source to the sample;
a detector;
one or more collection optics to image the sample onto the detector; and
one or more aberration-controlling components providing aberration correction for imaging the sample onto the detector according to the three or more degrees of freedom, wherein the one or more aberration-controlling components are integrated with at least one of the one or more illumination optics, the one or more collection optics, the detector, or the translation stage, wherein the one or more aberration-controlling components are adjustable in both position and rotation; and
a controller including one or more processors configured to execute program instructions causing the one or more processors to:
determine configurations of the one or more aberration-controlling components associated with the three or more degrees of freedom providing imaging of the sample onto the detector with a quality metric above a selected threshold for a plurality of imaging depths; and
direct the imaging metrology tool to image at least a portion of the sample at two or more imaging depths in the plurality of imaging depths using the determined configurations of the imaging metrology tool, wherein the imaging metrology tool is configured for sub-surface imaging at a range of sample depths, wherein the one or more aberration-controlling components are configured to maintain imaging quality across all depths within the range of sample depths by adjusting at least one of the three or more degrees of freedom for aberration control.