| 摘要 |
PURPOSE:To enable the easy detection of the defect occurring in the film thickness of a phase shift mask by simple means. CONSTITUTION:The intensity of the reflected light of the same wavelength lambda1 obtd. by irradiating the front surface of an optical mask 11 which is the phase shift mask with light of, for example, the wavelength lambda1 is detected by a 1st light intensity detector 8. The intensity of the transmitted light of the same wavelength lambda2 obtd. by irradiating the rear surface of the same optical mask 11 with light of, for example, the wavelength lambda2 which is different from the wavelength lambda1 is detected by a 2nd light intensity detector 9. These detected signals are processed in a signal processor 10 so as to obtain the film thickness of the phase shifter formed on the optical mask 11. |
