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Ionic Liquids as Additives to Polystyrene- Block-Poly(Methyl Methacrylate) Enabling Directed Self-Assembly of Patterns with Sub-10 nm Features.
- Source :
-
ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2018 May 16; Vol. 10 (19), pp. 16747-16759. Date of Electronic Publication: 2018 May 03. - Publication Year :
- 2018
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Abstract
- Polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) is one of the prototypical block copolymers in directed self-assembly (DSA) research and development, with standardized protocols in place for processing on industrially relevant 300 mm wafers. Scaling of DSA patterns to pitches below 20 nm using PS- b-PMMA, however, is hindered by the relatively low Flory-Huggins interaction parameter, χ. Here, we investigate the approach of adding small amounts of ionic liquids (ILs) into PS- b-PMMA, which selectively segregates into the PMMA domain and effectively increases the χ parameter and thus the pattern resolution. The amount of IL additive is small enough to result in limited changes in PS- b-PMMA's surface and interfacial properties, thus maintaining industry-friendly processing by thermal annealing with a free surface. Three different ILs are studied comparatively regarding their compositional process window, capability of increasing χ, and thermal stability. By adding ∼3.1 vol % of the champion IL into a low-molecular-weight PS- b-PMMA ( M <subscript>n</subscript> = 10.3k- b-9.5k), we demonstrated DSA on chemically patterned substrates of lamellar structures with feature sizes <8.5 nm. Compatibility of the PS- b-PMMMA/IL blends with the standardized processes that have been previously developed suggests that such blend materials could provide a drop-in solution for sub-10 nm lithography with the processing advantages of PS- b-PMMA.
Details
- Language :
- English
- ISSN :
- 1944-8252
- Volume :
- 10
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- ACS applied materials & interfaces
- Publication Type :
- Academic Journal
- Accession number :
- 29667409
- Full Text :
- https://doi.org/10.1021/acsami.8b02990