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Sub-10-nm patterning via directed self-assembly of block copolymer films with a vapour-phase deposited topcoat

Abstract

Directed self-assembly (DSA) of the domain structure in block copolymer (BCP) thin films is a promising approach for sub-10-nm surface patterning. DSA requires the control of interfacial properties on both interfaces of a BCP film to induce the formation of domains that traverse the entire film with a perpendicular orientation. Here we show a methodology to control the interfacial properties of BCP films that uses a polymer topcoat deposited by initiated chemical vapour deposition (iCVD). The iCVD topcoat forms a crosslinked network that grafts to and immobilizes BCP chains to create an interface that is equally attractive to both blocks of the underlying copolymer. The topcoat, in conjunction with a chemically patterned substrate, directs the assembly of the grating structures in BCP films with a half-pitch dimension of 9.3 nm. As the iCVD topcoat can be as thin as 7 nm, it is amenable to pattern transfer without removal. The ease of vapour-phase deposition, applicability to high-resolution BCP systems and integration with pattern-transfer schemes are attractive properties of iCVD topcoats for industrial applications.

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Figure 1: iCVD to form a crosslinked topcoat directly on a BCP film.
Figure 2: Orientation control of high-χ BCP films using an iCVD topcoat and pattern transfer.
Figure 3: Sub-10-nm DSA patterning with the iCVD topcoat.
Figure 4: Cut-mask application with an integrated iCVD topcoat.
Figure 5: Mechanism of interfacial engineering with the iCVD topcoat.

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Acknowledgements

The authors acknowledge support from the National Science Foundation (Award no. 1344891). This work was supported in part by the US Army Research Laboratory and the US Army Research Office through the Institute for Soldier Nanotechnologies, under Contract no. W911NF-13-D-0001. Use of the CNM and APS, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Argonne National Laboratory, is supported by the US DOE under Contract no. DE-AC02-06CH11357. For XPS, the authors made use of the Cornell Center for Materials Research Shared Facilities, which are supported by the National Science Foundation Materials Research Science and Engineering Centers program (DMR-1120296). We thank G. Frache for helpful discussion on the ToF–SIMS data and C. Zhou for help in preparing the XPS samples. We thank EMD Performance Materials for supporting materials.

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Contributions

H.S.S. and D.H.K. contributed equally to this work, designing and carrying out the experiments, and analysing the data, with supervision from K.K.G. and P.F.N. P.M. contributed to characterization of the surfaces and discussed the mechanism. S.X. helped to optimize the SIS process. L.E.O. contributed to the nanofabrication processes, including e-beam lithography, SIS and RIE. N.J.Z. helped to characterize the samples using electron microscopes. H.S.S., D.H.K., K.K.G. and P.F.N. wrote the manuscript.

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Correspondence to Karen K. Gleason or Paul F. Nealey.

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Suh, H., Kim, D., Moni, P. et al. Sub-10-nm patterning via directed self-assembly of block copolymer films with a vapour-phase deposited topcoat. Nature Nanotech 12, 575–581 (2017). https://doi.org/10.1038/nnano.2017.34

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