PHOTOMASK SUBSTRATE WITH IDENTIFICATION TAG, PHOTOMASK, AND IDENTIFICATION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a photomask substrate and a photomask with an identification tag which has high visibility and can be directly processed on a photomask substrate in a short period of time without influencing the process or the quality of the mask so as to control the manufacture of the photomask, and to provide a method for efficiently identifying the information written in the tag.

SOLUTION: The photomask substrate has an identification tag comprising an information pattern to be used for identification and control of the photomask in the process of manufacturing a photomask. The identification tag comprises a diffraction grating written by direct processing using two-beam interference exposure of an ultrashort pulse laser in the inner region of the photomask substrate except for the surface.

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