| 摘要 |
PROBLEM TO BE SOLVED: To provide a material capable of obtaining a photomask high in quality and high in precision by using a substrate having specified physical properties such as deposition of foreign matters, mixing of bubbles, flatness, smoothness and transmittance. SOLUTION: This photomask material is obtd. by using a substrate satisfying the following conditions. As for deposition of foreign matters, it is practically no problem if a matter larger than 20μm in size is not present. As for bubbles in a glass, it is required that bubbles larger than 30μm in size are not present so as to maintain high quality and high precision and to realize stable production. As for preferable flatness, displacement in the X and Y axes is measured by using an autocolimeter and calculated, and >=300R as a calculated value is preferable. As for preferable smoothness of the both surfaces, <=10μm roughness in 100mm×100mm area is required. As for preferable transmittance, >=65% transmittance for light in 350 to 400μm wavelength region, and more preferable >80% for 365μm wavelength is required. |
