Morphology Control and Ordering of PS-b-PMMA Block Copolymer by The Use of Neutral Monolayer and E-beam Lithography
Babak, Baradaran Shokouhi
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As the conventional nanofabrication methods are reaching their limits of miniaturization, new methods are being studied to overcome this miniaturization challenge. Among the new emerging nanofabrication methods, bottom-up self assembly of Block Copolymers (BCPs) is gaining significant popularity among the researchers and the semiconductor industries. BCP self assembly has many advantages among which, low processing cost, high resolution, and large scale processing are the more prominent ones. Controlling the polymer fraction in the BCP mix leads to variety of different morphologies, these morphologies can be used to create nanofabrication masks and templates. A great amount of research has been conducted on how to control BCP morphologies. However, orientation of these BCP morphologies are very important and crucial to the nanofabrication technologies. Ideally, morphologies with perpendicular orientation to the surface of the substrate with very high aspect ratios are preferred for pattern transfer. To obtain this unique orientation many different methods have been studied, however in this research we employed a unique method to modify the surface energy of the substrate and create perpendicular morphologies for the BCP of PS-b-PMMA. Further, electron beam lithography was used to modify the properties of the PS-b-PMMA block copolymer in order to obtain different morphologies within the same BCP thin film.