Picture Information

Picture Title:LISA
Photographer/ Operator/ Designer Name:Stephen Y. Chou
Institute Site:http://www.abc.net.au/science/news/stories/s67654.htm
Description:In LISA, Lithographically Induced Self Assembly, a smooth, thin, single-homopolymer film (like PMMA) is first cast on a flat substrate. Then a mask with protruding patterns is placed above the film, but it is separated, using a spacer, from the film by a gap.  The mask, the polymer film, and the substrate are heated uniformly to a temperature above the polymer’s glass transition temperature, then are cooled down to room temperature. During the heat-cool cycle, the initially flat polymer film self-assembles into periodic supramolecular pillar arrays. The pillars, formed by rising against the gravitational force and surface tension, bridge the two plates. The pillar height is equal to the plate–mask separation. After pillar formation, due to a constant polymer volume, there is little polymer left in the area between the pillars. Moreover, if the surface of the mask has a protruding pattern (e.g., a triangle or rectangle), the pillar array can be formed only under the protruding pattern with the edge of the array aligned to the boundary of the mask pattern (such as that shown in the above AFM image).  The array’s lattice structure is determined by the shape and size of the mask pattern. The location of each pillar can be precisely controlled by the patterns on the mask. In principle, the LISA process can be used repeatedly to further demagnify the self-assembled pattern size.
Institute Site:http://www.nanopicoftheday.org/2004Pics/June2004/LISA.htm
Dimensions:306 * 282

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