Tunable Tiny Features

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Science  21 Mar 2003:
Vol. 299, Issue 5614, pp. 1817
DOI: 10.1126/science.299.5614.1817a

Patterning at the nanometer scale is an area of intense investigation, because current fabrication methods have their limitations at this length scale. For top-down approaches like lithography or molding, the problem is making reproducible features smaller than 50 nm, whereas for bottom-up approaches like self-assembly, the challenge is patterning large areas with exact positioning. By combining a molding step with a subsequent polymerization, von Werne et al. overcame some of these limitations. The key to their method is the inclusion in the curable photopolymer used to make the initial pattern of an “inimer,” namely, a molecule with both an initiator and a monomer fragment for subsequent polymerization steps. Some of the inimers remain on the surface of the molded pattern, and then a second polymer can be directly synthesized onto the mold via living free-radical polymerization. Feature sizes between parts of the pattern could be reduced from a spacing of 100 nm to 20 nm. Also, because several different polymers could be grafted onto the same initial molded pattern, it was possible to change the surface chemistry using the same basic processing steps. — MSL

J. Am. Chem. Soc. 10.1021/ja028866n (2003).

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