Phase-shifting masks gain an edge

The potential, working principles, and approaches in phase shifting masks for optical lithography are discussed. The tradeoffs of each approach, and fabrication, inspection, repair, and tolerances are considered. It is feasible to use the phase shifting technology to improve optical lithography to 0.18- mu m feature size with k/sub 1/=0.35, lambda =248 nm, and NA=0.5. Further resolution improvements are still possible, but much development is required for making phase shifting masks a manufacturing reality.<
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