Siemens Aktiengesellschaft

Klaus Ergenzinger

Rainer Pforr

Christoph Friedrich

Uwe Griesinger

Fritz Gans

J&uuml;rgen Knobloch

Wilhelm Maurer

For lithographically producing the smallest structures at less than the exposure wavelengths in semiconductor fabrication, a double exposure is carried out using a thick phase mask and a trimming mask, the trimming mask further structures the phase-contrast lines produced by the phase mask. Besides transparent or opaque regions, the trimming mask also has phase-shifting regions. These surround transparent regions of the trimming mask through which the phase-contrast lines produced by the first mask are locally re-exposed, that is to say interrupted. The intensity profile of successive line sections is especially rich in contrast through the addition of the phase-shifting partially transparent regions on the second mask; the distances between the line sections can be reduced. The trimming mask, otherwise used only for larger structures, is therefore suitable for the configuration of the finest dimensionally critical structures.

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Oberhaching, Germany

Klaus Ergenzinger