18 March 2015 Forbidden pitches: causes, source optimization, and their role in design rules
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Abstract
Forbidden pitches are the result of unwanted, non-linear effects that limit yield and not always well understood. Yet, as approximations, they are implicitly deployed through design rules. Many believe they result as a consequence of more complicated light sources. We develop an analytical model of aerial image quality as a function of light source. We show the effect is most pronounced for a point light source, the simplest of all. We develop a method to improve print image quality by illumination source optimization, and show promising first results. Additionally, it is shown how design rules capture forbidden pitches unsatisfactorily.
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Ştefan Apostol, Ştefan Apostol, Paul Hurley, Paul Hurley, } "Forbidden pitches: causes, source optimization, and their role in design rules", Proc. SPIE 9426, Optical Microlithography XXVIII, 94261K (18 March 2015); doi: 10.1117/12.2085753; https://doi.org/10.1117/12.2085753
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