The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 24, 2026
Filed:
Jun. 30, 2023
Onto Innovation Inc., Wilmington, MA (US);
John M. Thornell, Richardson, TX (US);
Onto Innovation Inc., Wilmington, MA (US);
Abstract
Image sensors assist in inspecting semiconductor substrates, including semiconductor wafers, during the semiconductor manufacturing process. However, due to the non-uniformity of cells between image sensors, which is referred to as photo response non-uniformity (PRNU), each image sensor can generate a different voltage level when illuminated with a uniform light source, which leads to a luminance inaccuracy at the pixel level that is referred to as photo response non-uniformity (or illumination flat fielding). Photo response non-uniformity (PRNU) can be corrected using a system calibration that calibrates to a substrate, including wafers, for a given illumination condition, objective, and camera. The PRNU correction is then applied to all images acquired with the given setup to produce a uniform image. Techniques are described to correct the PRNU at runtime even when there is a contour, e.g., tilt or warp, in the substrate as it relates to the normal axis of the optics.