US 12,174,128 B2
High resolution multispectral multi-field-of-view imaging system for wafer inspection
John A Tejada, Londonderry, NH (US)
Assigned to Onto Innovation Inc., Wilmington, MA (US)
Filed by Onto Innovation Inc., Wilmington, MA (US)
Filed on Sep. 8, 2022, as Appl. No. 17/930,606.
Claims priority of provisional application 63/242,354, filed on Sep. 9, 2021.
Prior Publication US 2023/0075747 A1, Mar. 9, 2023
Int. Cl. G01N 21/95 (2006.01); G01J 3/28 (2006.01); G01N 21/64 (2006.01); G01N 21/88 (2006.01)
CPC G01N 21/9501 (2013.01) [G01J 3/2823 (2013.01); G01N 21/6458 (2013.01); G01N 21/8806 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical system for inspection of a substrate, the optical system comprising:
a microscope objective;
an off-axis reflective focusing system comprising:
a primary concave mirror with positive power to receive light beams from the microscope objective,
a secondary convex mirror with negative power to receive converged light beams from the primary mirror, and
a tertiary concave mirror with a positive power to receive redirected light beams from the secondary mirror;
a beamsplitter to receive a light from the off-axis reflective focusing system and to separate the light into a first spectrum and a second spectrum;
a first detector to generate a first image of the substrate based on the first spectrum; and
a second detector to generate a second image of the substrate based on the second spectrum.