Optical imaging of IC critical designs is impacted by optical proximity effects, OPEs,
originating from finite numerical aperture of projection lenses used in modern projectors. The
OPE's are caused by filtering of pattern diffraction orders falling outside of the lens band pass.
Controlling OPEs is so critical to IC performance, that IC design community implemented optical
proximity correction, OPC, modifying the IC mask patterns to provide wafer images matching the
IC design intent. The mainstream OPC uses optical models representing fundamental imaging
setup and it does not capture the impacts of engineering scanner tool constraints.
The OPEs are impacted by scanner lens and illuminator signatures causing CD excursions
large in comparison to the CD error budgets(1). The magnitude of the scanner impacts on OPEs
necessitated new optical modeling paradigm involving imaging models imbedding scanner
signatures representing population of scanners of a given type. These scanner-type based models
represent quantum leap in accuracy of lithography simulation technology, resulting in OPE and
OPC representing a broad range of realistic scanner characteristics(2).
In this context, a relevant question is: to what degree, the signatures of individual scanners
impact the accuracy of imaging models and OPE predictions? To answer this question, we
analyzed optical proximity responses of hyper-NA scanners represented by their signatures. We
first studied a set of OPEs impacted by the scanner-type signatures. We then generated a set of
corresponding OPEs impacted by the signatures of individual scanners. We compared the two
kinds of OPEs and highlighted the scanner-specific image formation responses.