FABRICATION OF MICROSTRUCTURES USING SHRINKABLE POLYSTYRENE FILMS

This paper demonstrates the combination of reactive ion etching (RIE) and shrinkable polystyrene (PS) films to reduce the feature size of mi crostructures and to generate microstructures with high aspect ratios on both planar and curved surfaces. A shrinkable PS film is patterned with relief structures using RIE through a physical mask. The patterne d surface is heated and shrinks. After shrinking, the size of microstr uctures decreases by a factor of four to five, and their height increa ses by a factor of similar to 20. Thermal shrinkage results in a 100-f old increase in the aspect ratio of the patterned microstructures in t he PS film. Microstructures as high as similar to 126 mu m with aspect ratio of similar to 9.5 have been generated. The smallest structures fabricated using this strategy are rectangular pits similar to 1.4 mu m X 1.7 mu m in size. Fabrication of microstructures on curved surface s has been demonstrated by folding a patterned PS film and allowing it to shrink in place. (C) 1998 Elsevier Science S.A.