Patent ID: 11921052
Assignee: KLA CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 10:
11. The inspection system of claim 1, wherein generating the multi-step difference image by the weighted subtraction of the combination of at least one of the second-step comparison images and at least two of the first-step images from the test image comprises:
generating the multi-step difference image (IMSDIFF,i) based on the equation IMSDIFF,i=ISecondStep,i−Σj≠iαjISecondStep,j−γ[IFirstStep,i−Σj≠iβjIFirstStep,j], where ISecondStep,i corresponds to the test image, Σj≠iαjISecondStep,j corresponds to the at least one of the second-step comparison images, and [IFirstStep,i−Σj≠iβjIFirstStep,j] corresponds to the at least one of the first-step images, wherein subscripts i and j correspond to the sample regions, wherein α, β, and γ correspond to weights.