An attenuating phase shifting mask has been designed, fabricated, and tested at 157 nm. It consists of two layers, a metal attenuator and a transparent phase shifter. The metal, platinum, was chosen for its chemical and radiation stability. The phase shifter was a commercial spin-on glass. A single step of pattern transfer has been implemented, which significantly simplifies the fabrication process of the mask. The lithographic advantage in increased depth of focus was demonstrated for 130-nm spaces and contacts, and it was found to agree with numerical simulations.
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