Kla Corporation

Kla Tencor Corporation

Premchandra M Shankar

Ashok Varadarajan

Yong Zhang

Tao Luo

Songyang Yu

Jie Gong

JuHwan Rha

Chaohong Wu

Methods and systems for image alignment are provided. One method includes selecting three or more salient feature points for use in test image to reference image alignment by applying a selected salient feature point detection method to at least a reference image generated for the specimen. The method also includes detecting the three or more salient feature points in the test image and the reference image and aligning the detected three or more salient feature points in the test image to the detected three or more salient feature points in the reference image. The method further includes aligning remaining portions of the test image to remaining portions of the reference image based on results of the previous aligning step.

Salient feature point based image alignment

For semiconductor inspection images, detection thresholds can be determined based on probability density functions at a pixel intensity. The detection thresholds can then be applied to an image. This can find outliers at a fixed probability at all pixel intensity levels by estimating the probability distribution of underlying data and adapting the detection threshold values. Laser power can be optimized based on the detection thresholds.

Equi-probability defect detection

A system for defining flexible regions on a sample is disclosed. The system includes an inspection system configured to acquire one or more swath images. The system includes a controller communicatively coupled to the inspection system, the controller configured to: generate one or more median reference die (MRD) images based on the one or more swath images; generate one or more flexible region masks based on the one or more MRD images; identify a set of alignment sites on the one or more flexible region masks based on one or more coordinates of the one or more MRD images; perform patch-to-mask alignment between the one or more flexible region masks and one or more scan images by aligning the scan images and the one or more MRD images at the identified set of alignment sites; and position the one or more flexible region masks on the scan images.

System and method for defining flexible regions on a sample during inspection

Repeater defects on a wafer can be detected by fusing multiple die images. In an instance, multiple die images are statistically fused to form a die-fused image. Each of the die images can be of a different die on a wafer. A presence of a repeater defect is detected in the die-fused image. The die images can be generated using a laser-scanning system or other systems.

Repeater defect detection

An inspection method includes receiving a plurality of inspection images of a substrate. The method includes generating a first noise image from a first image from the first channel and an additional noise image from the additional image from the additional channel. The method further includes generating a first signal-to-noise ratio (SNR) image from the first noise image and an additional SNR image from the additional noise image and identifying one or more first pixel candidates in the first SNR image and in the additional SNR image. The method further includes combining image data from the first SNR image and image data from the additional SNR image at common pixel candidate sites based on the one or more identified first pixel candidates and the one or more identified additional pixel candidates to form a combined image used to detect defects on the substrate.

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Fremont, CA, United States of America

Premchandra M Shankar