| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent the occurrence of defects in an optical film formed on a transparent substrate (a defective fraction of a photomask blank) and to improve the production yield of a photomask blank. <P>SOLUTION: The number of defects on the surface (film forming surface) of a quartz substrate 11 to be used for the manufacture of a photomask blank is measured by use of a surface inspection device to obtain the number of defects having a predetermined size (such as a diameter of 0.1 to 0.5μm) on the film forming surface. Only a quartz substrate 11 having a predetermined number or less of defects having diameters of 0.1 to 0.5μm is taken out and used as a film forming substrate (a substrate selecting step). The predetermined number is 5 or less, and preferably 2 or less. A light shielding film such as a light shielding film and an antireflection film sequentially layered is formed on the selected film forming substrate (film forming step). When a phase shift type photomask blank is required, a phase shift layer is formed between the film forming substrate and the light shielding film. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
