Abstract
The evolution of high-NA projection optics design and manufacturing tolerances has been remarkable in
recent years. Nevertheless, different instances of identical scanner models can still exhibit unique optical
fingerprints which can impart subtle patterning differences for a given mask exposed at nominally identical
conditions on different scanners. In some cases, a product can be shown statistically to yield lower when a
certain layer is exposed on a particular scanner. Thus it is common to have a certain subset of the total
population of tools allowed for certain critical levels, such as gate. Since a single mask is typically shared
between the multiple allowed scanners, the optical proximity correction model which is employed in the
generation of that mask must represent the average fingerprint of those tools. In practice, CD data may be
collected from multiple tools, but more often a single tool is somehow identified as the "golden" tool for
the purpose of calibrating the OPC model. Once the mask is generated, however, its printing behavior on
multiple scanners can readily be simulated using tool-specific optical models. Such models can be easily
generated based upon known optical fingerprint data, such as measured illumination source maps, Jones
pupil or Zernike aberration files. This paper investigates the use of tool-specific optical models to elucidate
the intersection of design and process variability, which will manifest differently on each scanner,
depending upon subtle details of the scanner fingerprint.
