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Graphoepitaxial Directed Self‐Assembly of Polystyrene‐ Block ‐Polydimethylsiloxane Block Copolymer on Substrates Functionalized with Hexamethyldisilazane to Fabricate Nanoscale Silicon Patterns
Author(s) -
Borah Dipu,
Rasappa Sozaraj,
Senthamaraikannan Ramsankar,
Holmes Justin D.,
Morris Michael A.
Publication year - 2014
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201300102
Subject(s) - polydimethylsiloxane , materials science , copolymer , polystyrene , substrate (aquarium) , silicon , nanotechnology , wetting , surface modification , nanolithography , nanoscopic scale , self assembly , chemical engineering , polymer , composite material , fabrication , optoelectronics , medicine , oceanography , alternative medicine , pathology , engineering , geology
In block copolymer (BCP) nanolithography, microphase separated polystyrene‐ block ‐polydimethylsiloxane (PS‐ b ‐PDMS) thin films are particularly attractive as they can form small features and the two blocks can be readily differentiated during pattern transfer. However, PS‐ b ‐PDMS is challenging because the chemical differences in the blocks can result in poor surface‐wetting, poor pattern orientation control and structural instabilities. Usually the interfacial energies at substrate surface are engineered with the use of a hydroxyl‐terminated polydimethylsiloxane (PDMS‐OH) homopolymer brush. Herein, we report a facile, rapid and tuneable molecular functionalization approach using hexamethyldisilazane (HMDS). The work is applied to both planar and topographically patterned substrates and investigation of graphoepitaxial methods for directed self‐assembly and long‐range translational alignment of BCP domains is reported. The hexagonally arranged in‐plane and out‐of‐plane PDMS cylinders structures formed by microphase separation were successfully used as on‐chip etch masks for pattern transfer to the underlying silicon substrate. The molecular approach developed here affords significant advantages when compared to the more usual PDMS‐OH brushes used.