The innovation engine for new materials

Matthew Luger

Matthew Luger


University of California Santa Barbara


Chemical Engineering

Site Abroad: 

Chemistry Department, University College Cork


Ciara Bolger

Faculty Sponsor(s): 

Justin Holmes

Project Title: 

Ordered, Ultra Thin AAO Hard Masks Prepared by Pattern Transfer of Templated, Self Assembled Block Copolymers

Project Description: 

The highly ordered hexagonally close packed pores of Anodic Aluminum Oxide (AAO) would suit as an ideal ultra thin hard etch mask due to the chemical and thermal robustness of the membrane. AAO can be prepared through electrochemical anodization of a thin Al film connected to a silicon substrate. Perfect ordering of a thin AAO film requires pre-patterning of the Al. One novel method would be to transfer the long range ordered pattern offered by templated block copolymer (BCP) films into the Al to direct AAO pore nucleation. This work explored the formation of BCP thin films on Al for such an application. Cylinder forming PS-PMMA films were microphase separated on Al films, which to our knowledge has not previously been reported. It was found that neutralization of the Al surface was required, achieved via surface hydroxylation combined with polymer brush grafting, in order to obtain the desired vertical orientation. A systematic study was carried out to establish the optimal annealing conditions for both the polymer brush and the PS-PMMA thin film. Our findings suggest that surface hydroxylation can be achieved via UV-Ozone exposure or treatment with water at elevated temperatures. A random brush of PS-PMMA or a PS brush could both serve to neutralise the Si/Al substrate. Annealed PS-PMMA thin films (fps=0.7) formed vertically oriented cylinders with a diameter ~30nm on this substrate which, when etched, will serve to nucleate AAO pore growth.