We present the results of both theoretical and experimental investigations of materials for application either as a reversible Contrast Enhancement Layer (rCEL) or a Two-Stage PAG. The purpose of these materials is to enable Litho- Litho-Etch (LLE) patterning for Pitch Division (PD) at the 16nm logic node (2013 Manufacturing). For the rCEL, we find from modeling using an E-M solver that such a material must posses a bleaching capability equivalent to a Dill A parameter of greater than 100. This is at least a factor of ten greater than that achieved so far at 193nm by any usable organic material we have tested. In the case of the Two-Stage PAG, analytical and lithographic modeling yields a usable material process window, in terms of reversibility and two-photon vs. one-photon acid production rates (branching ratio). One class of materials, based on the cycloadduct of a tethered pair of anthracenes, has shown promise under testing at 193nm in acetonitrile. Sufficient reversibility without acid production, enabled by near-UV exposure, has been achieved. Acid production as a function of dose shows a clear quadratic component, consistent with a branching ratio greater than 1. The experimental data also supports a acid contrast value of approximately 0.05 that could in principle be obtained with this molecule under a pitch division double-exposure scenario.
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