PURPOSE: To improve the durability of the checking blanks to be used for the checking of a coordinate system of the electron beam exposure device for the manufacture of a photomask by a method wherein a laminated film, composed of a thin film layer having Au as the main ingredient, a thin film layer having metal chrome as the main ingredient and a thin film layer having chrome oxide as the main ingredient, is provided on a transparent substrate.

CONSTITUTION: Checking blanks consists of an Au thin film 2 of 500W1,000 in thickness formed on one main plane surface of a transparent quartz substrate 1 by performing a vacuum deposition method, a metal chrome film 3 of 800W1,000 in thickness formed on the thin film 2 by performing a sputtering vapor-deposition method, and a chrome oxide layer 4 of 100W300 in thickness formed thereon. On this blanks, an electron beam resist 5 is applied, an exposure is performed on the desired check pattern using an electron beam 6, a developing treatment is performed subsequently, and a resist pattern is formed. Then, after an etching has been performed with a chrome etchant using said pattern as a mask, the resist pattern is peeled off. As a result, a checking mask to be used for the coordinate system of an electron beam exposure device, having excellent chemical and mechanical durability, can be obtained.