| 摘要 |
The present invention relates to a photomask and a method for forming an overlay mark in a substrate using the same. The photomask comprises a plurality of patterns. At least one of the patterns comprises a plurality of ring areas and a plurality of inner areas enclosed by the ring areas, wherein the light transmittancy of the ring areas is different from that of the inner areas. When the photomask is applied in a photolithography process, the formed overlay mark has a large thickness. Therefore, the contrast is high when a metrology process is performed, and it is easy to find the overlay mark.
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