September 6, 2007 – Scientists at Princeton U. say they’ve figured out how make gratings on microchips with 60nm half-pitch periodic lines, using what they call a simple, low-cost technique called “fracture-induced structuring.”

The process involves sandwiching a thin polymer film between two substrates, heated to ensure adhesion, and prying them apart. As the film fractures, it automatically breaks into two complementary sets of nanoscale gratings (one on each plate), with the distance between the lines consistently 4x the film’s thickness regardless of molecular weight or chemical composition.

Originally the researchers, led by profs. Stephen Chou and William Russel, was trying to use instabilities in various molten polymers to create patterns, but found that fracturing a solid polymer could generate gratings automatically, and figured out how to optimize the process of grating formation.

The technique has worked to create gratings over 2 sq. cm with 120nm-200nm periodic lines, and patterning of “much larger areas” should be possible once the technique is optimized, the researchers say. The process can also be used in conjunction with other patterning methods — e.g., the nanoprinting method invented by Chou in the 1990s, combining to create a mold enabling mass duplication of high-precision, low-cost patterns.

The research is described in the newest issue of the online version of Nature Nanotechnology.

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Fracture-induced structuring results in the self-formation of periodic lines, or gratings, separated by as few as 60nm. (Source: Princeton U.)