| 摘要 |
A method and apparatus for determining lens distortion in a projection imaging tool are described. The techniques include exposing at least one alignment attribute onto a substrate having a recording media. A complementary alignment attribute is also exposed onto the substrate such that the complementary alignment attribute and alignment attribute form a completed alignment attribute. The exposure of the alignment attributes, or the complementary alignment attribute, or both, may be accomplished by multiple sub nominal dose exposures. Intra field distortion of the projection imaging tool is determined from measurements of the exposed completed alignment attributes. The alignment attributes and complimentary alignment attribute may be part of a reticle. The transmission of the alignment attribute may be different than the transmission of the complementary alignment attribute.
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