US 11,988,641 B2
Characterization of patterned structures using acoustic metrology
Manjusha Mehendale, Morristown, NJ (US); Michael Kotelyanskii, Chatham, NJ (US); Priya Mukundhan, Lake Hopatcong, NJ (US); and Robin Mair, West Chicago, IL (US)
Assigned to Onto Innovation Inc., Wilmington, MA (US)
Filed by Onto Innovation Inc., Wilmington, MA (US)
Filed on Mar. 30, 2021, as Appl. No. 17/217,527.
Claims priority of provisional application 63/008,903, filed on Apr. 13, 2020.
Prior Publication US 2021/0318270 A1, Oct. 14, 2021
Int. Cl. G01N 29/24 (2006.01); G01N 29/06 (2006.01)
CPC G01N 29/2418 (2013.01) [G01N 29/06 (2013.01); G01N 2291/2697 (2013.01)] 23 Claims
OG exemplary drawing
 
1. A method for characterizing a patterned structure of a sample, the method comprising:
directing a plurality of pump beams and associated probe beams to be incident on a surface of the sample, wherein pump beams and associated probe beams are controlled to be incident on the surface of the sample at different distances from each other, wherein each pump beam induces a surface acoustic wave in the sample, and each probe beam is affected by the surface acoustic wave induced by an associated pump beam when the each probe beam reflects from the surface of the sample;
detecting reflected probe beams;
analyzing the detected reflected probe beams to identify frequency modes in the reflected probe beams as a function of the different distances between the probe beams and associated pump beams; and
based on the identified frequency modes, determining at least one of a width or a pitch of a patterned feature in the sample.