Phase shift masks help demonstrate sub-100nm features from 248nm lithography

February 26, 2001–Jupiter, Florida–Photronics, Inc. announced today that its Sub-Wavelength Reticle Solutions phase shift photomasks were recently used as part of a joint development effort that successfully demonstrated the ability to produce sub-100nm features using KrF (248nm) exposure technology.

The work, conducted by MIT Lincoln Laboratory under U.S. Department of Defense sponsorship, demonstrates the feasibility of extending 248nm optical lithography technology beyond its currently anticipated limits. Prior to this work, KrF technology was not envisioned as a possible option for the sub-100nm regime.

Photronics produced a variety of advanced phase shift reticles for this project using its proprietary Sub-Wavelength Reticle Solutions processes. The first reticle set was a double exposure strong phase shift mask pair, combined with simple optical proximity correction (OPC) to control proximity effects. A second approach avoided proximity effects through the use of a dense-only phase shift mask. Significant deep sub-100nm critical dimension (CD) control was achieved by employing an imaging strategy based on a chromeless phase shift, double exposure reticle technology.

“The results produced by MIT will have broad appeal across the semiconductor industry, as they demonstrate the extension of 248nm lithography well beyond what was thought to be the technology’s initial limits,” says Steve Carlson, senior vice president of Technology at Photronics. “Together with leading research institutions, we continue to discover just how far wafer lithographers can progress along the International Technology Roadmap for Semiconductors (ITRS) by employing well designed phase shift reticles and optical enhancements–and that appears to be a lot farther than anyone imagined.”

The full results of these experiments will be presented this week at the SPIE Microlithography Conference in Santa Clara, CA. Dr. Michael Fritze et. al, of MIT Lincoln Laboratory will deliver two presentations, titled “100nm Node Lithography With KrF?” and “Investigation of Full-Field CD Control of Sub-100nm Gates Produced by Phase Shift 248nm Lithography.” These two works are co-authored by Dr. David Chan and Peter Rhyins of Photronics.


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