Most microchips are made by using light to create patterns on silicon surfaces-a process requiring sophisticated equipment costing tens of millions of dollars. A cheaper chip-making process involves coating the silicon surface with a polymer, heating the polymer until it softens and then mechanically stamping it with a patterned mold. Chemicals dissolve the stamped polymer where it’s thinnest, exposing the silicon beneath and etching the pattern into it. A drawback: the polymer can be stamped only once, since reheating deforms it.
Researchers at the Seoul National University in Korea may have brought imprint lithography a big step forward. The key development: doing away with the heating step, which they discovered to be unnecessary. Even at room temperature, chemical engineering professor Hong H. Lee showed, the polymer flattens far more under mechanical pressure than had been anticipated. Repeating the process on the same surface with a different mold allows more complex patterning. The technique, still at least two years away from commercial readiness, could drive down the costs of micro and nano devices.