To make correctable a white defect, a black defect or a glass projection defect of a Levenson mask with one kind of gas.
By using diacetone acrylamide, a light-shielding film 17 to correct a white defect can be formed both on a glass substrate 16 and on a chromium pattern 15 by varying the gas pressure or the probe current and scanning conditions of an ion beam 2. Also, chromium or glass can be etched by using diacetone acrylamide at a high etching rate so that a black defect region 18 or a glass projection defect region 19 can be removed. The conditions of gas supply or the conditions of ion beam irradiation are switched in accordance with correction of a white defect, a black defect or a glass projection defect of a Levenson mask to perform the correction, respectively.
AIDA KAZUO
ARAMAKI BUNRO
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