METHOD FOR DETECTING MISALIGNMENT OF TWO MASKING STEPS IN MANUFACTURE OF SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To detect mask misalignment by comparing a moire pattern which is optically observed with a moire pattern which is relevant to allowable alignment between two masks. SOLUTION: When two patterns are superposed each other, a repetition pattern which generates a moire pattern being a scale of the degree of misalignment between the two patterns is provided in each of two masks used in two masking steps. Each mask is used one by one and is put one upon another on a surface of a treated semiconductor wafer for printing a pattern of a mark of two masks. Then, a moire pattern formed by two pattern of a mark is optically observed. A known moire pattern which defines the range of allowable misalignment between two masks is compared with an observed moire pattern and it is judged whether or not the continuous treatment of the wafer is proper.