Abstract
Paul Chaikin: „Nanolithography with diblock copolymers: "What Fingerprints taught us about getting long range order in 2D"”
New York University
We have been using monolayer films of cylindrical and spherical phase diblock copolymers to make ultradense patterns over wide areas on arbitrary substrates. For example we cover a three inch wafer with ~ 3 trillion posts, holes, etc. spaced by ~ 25nm, to make quantum dots (for semiconductor lasers), metal particles and wires (for UV polarizers). In trying to understand how the polymer patterns order we have used atomic force microscopy (AFM) to image the cylindrical phase which lies flat on a substrate. The patterns look like fingerprints and Benard rolls and the coarsening (annealing) law we observe is t^(1/4) as in previous studies of these striped phases. Guided by previous studies of fingerprints and their defects we made time lapse AFM movies which show that the annealing dynamics is governed by the attraction of disclination PAIRS, quadrupoles, rather than simple +/- annihilation. However, the annealing is too slow to be useful. Instead we have shown that simple shear can lead to ordering of these nanometer patterns on centimeter and larger scales. We have then quantified and successfully modeled the shear alignment process.