Advanced microlithography photoresist technology and decreasing imaging wavelengths have enabled the semiconductor industry to fulfill the prediction by Intel's Gordon Moore ('Moore's Law') that chip circuit density will double approximately every 18 months. Critical feature sizes under 100 nm (650 C-C bond lengths) are being sought with the current generation of Deep Ultraviolet (DUV) photoresists imaged at 248 nm. In 2004, 90 nm circuit features were first commercialized with 193 nm (ArF) photoresists using methacrylate polymer systems. Recent advances in 193 nm photoresists including immersion lithography and double patterning enable resolution at or below 32 nm. Extreme Ultraviolet (EUV), E-Beam direct write and Directed Self Assembly (DSA) are being developed for next generation means to achieve single digit nm image features. It has been accepted in the industry that the polymer is one of the most important chemicals in the photoresist and that many important lithographic properties depend on polymer structure to be in specification and reproducible from lot to lot. To achieve and extend such extremely fine resolution, the industry is very actively seeking to understand how specific polymer properties impact lithographic performance. DuPont Electronic Polymers, LP is working closely with its customers and industry consortia to enable this effort.Currently, RAFT (R  eversible A  ddition F  ragmentation Chain T  ransfer) technology is being used to produce polymers with low polydispersity and high compositional uniformity for a variety of photoresist applications as well as to produce block copolymers in support of DSA development. RAFT polymerization enables the production of these materials provided that careful process monitoring and compositional homogeneity measurement systems are employed. It is uniquely suited to construction of multiblocks with components of widely divergent surface energies and functionality. In view of required levels of construct defectivity, polymer compositional uniformity and reproducibility is under intense scrutiny. Production processes and metrologies are being developed to provide control over long-range order, registered pattern geometries, and pattern perfection commensurate with lithographic needs. Industry R&D programs on Line Edge Roughness (LER) are being supported with polymers made using RAFT technology. More recently, high chi block copolymers synthesized using RAFT technology have been developed specifically for < 10 nm DSA applications. Unique partially fluorinated polymer systems are among those being tested to enable smaller and smaller features using this emerging technology.This paper will review a brief history of 248 nm and 193 polymer development as well as the current status of RAFT technology used for 193 nm photoresists and DSA applications.

Advanced nanopatterning using RAFT technology: History and future material requirements

248th National Meeting (2014)

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