Patent Document ID: 4845558
Application ID: 07128130
Patent Status: 1

Claim One:
1. A method of detecting defects in microminiature patterns repeated over a particular surface area of an object such as a semiconductor wafer, photomask, reticle or flat panel TV screen, comprising the steps of: providing an image detection means capable of resolving the information content of each pixel of an array of m.times.n pixels of a light image projected thereupon; illuminating an object having illuminatable feature determining patterns repeated in a regular array over a surface area thereof; projecting a focused image of light reflected from said surface area onto said detection means; rotating said object relative to said detection means so that an axis of said image is aligned with an axis of said detection means; adjusting the magnification of said image such that the dimension of the period of said repeated patterns in said image is equivalent to the distance across a selected integer number of pixels of said m.times.n array; and comparing one repeated feature to another to detect said defects.