Thermal lithography for 0.1 μm pattern fabrication

We have succeeded in patterning narrow lines and dots with 100 nm dimensions in a photoresist film by a 'thermal lithography' technique using a semiconductor laser with 635 nm wavelength. The demonstrated resolution of the patterns produced is far beyond the diffraction limit of 530 nm given by our optical set-up. We utilized a focused laser spot, which approximately has a Gaussian profile in its light intensity distribution, to produce a spatially confined hot area in a phase change recording layer on a conventional polycarbonate optical disk. This hot area induced a thermal cross-linking reaction in an adjacent photoresist film. By optimizing the sample rotation speed and the laser power, we were able to confine the area where the thermal cross-linking reaction in the photoresist occurred and patterned extremely fine structures. (C) 2002 Published by Elsevier Science B.V.