Ultrathin initiated chemical vapor deposition polymer interfacial energy control for directed self-assembly hole-shrink applications

• Published in: Journal of vacuum science and technology. B, Nanotechnology & microelectronics Nanotechnology & microelectronics, 2019-11, Vol.37 (6)
• Main Authors: Dolejsi, Moshe, Moni, Priya, Bezik, Cody T., Zhou, Chun, de Pablo, Juan J., Gleason, Karen K., Nealey, Paul F.
• Format: Article
• Language: English
• ISSN: 2166-2746; 2166-2754
• DOI: 10.1116/1.5121541

Integrated circuit layouts consist of patterned lines and holes, where holes define the electrical contacts between adjacent layers. Block copolymer directed self-assembly (DSA) successfully shrinks the critical dimension (CD) of these contacts beyond the resolution of conventional lithography. DSA also radically improves the CD uniformity. One particularly difficult step of the DSA hole-shrink process involves establishing the correct interfacial energy throughout a lithographically templated hole to ensure good assembly. Initiated chemical vapor deposition (iCVD) is a uniform, ultrathin, ultraconformal, all-organic deposition technique that allows for precise control of the interfacial energy. In this work, the authors use iCVD of polydivinylbenzene at film thicknesses below 5 nm to blend the interfacial energy of the coated film with that of the silicon/spin-on carbon template. They fully characterize the iCVD surface by means of two liquid surface energy measurements. They further identify the interfacial energies presented by these functionalized templates through qualitative hole-island tests as well as quantitative harmonic mean estimations. In parallel, the authors run theoretically informed coarse grained simulations with the determined interaction parameters and DSA experiments and find good agreement across the range of chemistries created. Through careful control of iCVD conditions, especially filament temperature, they achieve a strong polystyrene-preferential sidewall with a nonpreferential bottom which they then demonstrate, both in the simulation and in the experiment, allows for a successful hole-shrink process across a wide range of template hole diameters.