| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device that can reduce an influence of a back-ground noise on superposition inspection in a production process of a semi-conductor, so as to be able to realize a highly precise superposition inspection. SOLUTION: In this inspection method, in which alignment marks formed in a plurality of layers on a wafer 28 are irradiated with illumination light, reflected lights or diffracted lights by the alignment marks are image-focused to image-picked up the alignment marks by a CCD camera 24, and a superposition error in the plurality of layers is measured based on an image-picked-up signal provided by processing the image-picked-up images, the each alignment mark is image-picked up while a focus is changed when the alignment mark is image-picked up, a noise in the image of the alignment mark image-picked up while changing the focus is brought into a numerical value, and the optimum focus value used for measurement of the superposition error is determined based on a numerical result of the noise. COPYRIGHT: (C)2003,JPO
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