| 摘要 |
Transmittance of a photomask is determined using optical metrology. In particular, reflectance of a portion of the photomask is determined by directing an incident beam of light at the portion of the photomask. The reflectance is determined by measuring light diffracted from the portion of the photomask. One or more geometric features of the portion of the photomask are determined using the measured light diffracted from the portion of the photomask. A wave coupling is determined using the determined one or more geometric features of the portion of the photomask. The transmittance of the photomask is determined using the determined wave coupling and the determined reflectance of the portion of the photomask.
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