| 摘要 |
An objective of the present invention is to provide a technology for improving an in-plane characteristic uniformity of an optical film constituting photomask blank. In a chamber (50), a quartz substrate (10) having a main surface on which an optical film (20) is formed is put on a susceptor (30). A flash lamp (60) is housed in a lamp house (90), and the optical film (20) is irradiated with flash light through two quartz plates (70a and 70b). A transmittance adjustment region (80) is formed on a surface of the quartz plate (70b) of the two quartz plates (70a and 70b), and the amount of light with which the optical film (20) is irradiated has an in-plane distribution. If the optical film (20) is irradiated with the flash light, because optical characteristics of the optical film (20) change depending on the received irradiation energy, for example, when the characteristics of the optical film are not uniform and has a distribution and the optical film is irradiated with flash light having irradiation energy distribution that cancels the in-plane distribution, the in-plane characteristic uniformity of the optical film can be improved. |
