Patent ID: 8050490

Claim:
A method of inspecting a charged particle microscopic image for misalignment of photolithographic masks, comprising: providing a charged particle microscopic image of a sample, said image representing at least two different patterns formed as part of said sample by using two successive photolithographic masks; identifying an inspection pattern period from said image, said inspection pattern period comprising a contact point of said two patterns; averaging said image taking said inspection pattern period as a unit so as to reduce said image into an averaged inspection pattern period; estimating an average width of the averaged inspection pattern period; and comparing said average width with a threshold value thereby determining the presence of misalignment of said successive photolithographic masks, wherein if said average width is equal to or greater than said threshold value it is determined that misalignment of said successive photolithographic masks is present, and otherwise it is not determined that misalignment of said successive photolithographic masks is present.