Type

Journal Article

Authors

Michael A. Morris
Apostolos Avgeropoulos
Justin D. Holmes
Matthew T. Shaw
Christos Ntaras
Tandra Ghoshal

Subjects

Chemistry

Topics
thin films self assembly polyethylene oxides block copolymers copolymers chlorine compounds surface roughness low molecular weight

A vertical lamellae arrangement of sub-16 nm pitch (domain spacing) in a microphase separated PS-b-PEO thin film by salt addition (2015)

Abstract Ultra-small feature size (∼8 nm domain width) nanopatterns have been achieved using a symmetric polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) of low molecular weight (PS and PEO blocks of 5.5 and 5.3 kg mol−1 respectively). The work represents the smallest feature size attained and the first observation of a well-controlled film of a perpendicularly oriented lamellar pattern in thin film form for this system. The polymer synthesized and described herein has a value χN (=7.7), below the expected BCP phase segregation limit of 10.5. These patterns were achieved by amplification of the effective interaction parameter (χeff) of the BCP system by the addition of lithium chloride (LiCl) salt. A model where the Li+ ions strongly coordinate with the PEO block without affecting the PS chain is proposed to explain the ordered self-assembly. The morphological and structural evolution for these PS-b-PEO/LiCl thin films was investigated by variation of the experimental parameters such as temperature, annealing time, salt concentrations, solution aging time, annealing solvent etc. All the experimental parameters have significant effects on the morphology, domain spacing, defectivity or surface roughness of these symmetric BCP thin films as evident from different microscopic and spectroscopic techniques. Possible hard mask applications in the area of lithography are demonstrated.
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Full list of authors on original publication

Michael A. Morris, Apostolos Avgeropoulos, Justin D. Holmes, Matthew T. Shaw, Christos Ntaras, Tandra Ghoshal

Experts in our system

1
Michael A. Morris
University College Cork
Total Publications: 164
 
2
Apostolos Avgeropoulos
Trinity College Dublin
Total Publications: 5
 
3
Justin D. Holmes
University College Cork
Total Publications: 287
 
4
Matthew T Shaw
University College Cork
Total Publications: 24
 
5
Christos Ntaras
University College Cork
Total Publications: 3
 
6
Tandra Ghoshal
University College Cork
Total Publications: 32