Sub-Half-Micron i-Line Lithography by Use of LMR-UV Resist

Negative photoresist, LMR-UV, has been developed for i-line lithography. It resolves isolated 0.3 µm space and 0.35 µm hole patterns of 1.0 µm thickness by using a 0.42-numerical-aperture i-line reduction projection aligner. LMR-UV gives overhung profiles because of its large absorption coefficient of 3.8 µm -1 at the i-line. New phase-shifting mask patterns which are adapted to isolated space and hole patterns for negative resist have been developed. By use of this mask, LMR-UV clearly resolves 0.25 µm space and 0.3 µm hole patterns by using the i-line aligner. This phase-shifting mask improves both resolution and focus margin.