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Nanocrystals key to sub-32nm optical litho

Posted: 02 Jun 2009 ?? ?Print Version ?Bookmark and Share

Keywords:optical lithography? photolithography? nanocrystal?

Pixelligent Technologies LLC claim to have developed a nanocrystalline material that can enhance the resolution of existing photolithography equipment to below 32nm.

The company recently closed a $2 million round of equity financing to commercialize its nanocrystals, which it says have applications in optical lithography and as nanocomposite coatings for microelectronics.

"We are using nanotechnology to develop new materials for photolithography," said Greg Cooper, founder and president of Pixelligent. "The industry has pushed optical lithography nearly as far as it will go, but we believe we can extend its lifetime with new materials that have unique optical properties that don't exist today."

In addition to nanocrystals for photoresist, the company is developing nanocomposite chip coatings that "that assist in thermal management, getting the heat out of chips," said CEO Craig Bandes.

Pixelligent's secret sauce involves the fabrication of non-silicon nanocrystals with properties custom-designed for specific applications. The company declined to identify the exact composition of its proprietary nanoparticles, except to say that they are non-silicon.

By combining the semiconducting nanocrystals with lithographic polymers, Pixelligent claims traditional resists can be improved so that they can image much finer lines. The company also claims its nanocrystal coatings result in higher yields, lower materials costs and improved throughput, all while using existing chip fabrication equipment.

Since its founding in 2000, Pixelligent has been running on research contracts from the National Science Foundation's Small Business Innovation Research (SBIR) program and from the National Institute of Standards and Technology's Advanced Technology Program (ATP). The latter program awarded Pixelligent a $2 million contract in 2007, and the company has received a total of $600,000 in SBIR awards, which were fulfilled with development support from commercial photoresist makers Brewer Science Inc., Honeywell Electronic Materials and JSR Micro Inc.

For the NIST ATP contract, Pixelligent developed a semiconductor nanocrystal-based reversible contrast enhancement layer (R-CEL) using a unique photobleachable material that's said to allow double patterning of wafers at ultrahigh resolutions. Today, 193nm-wavelength light can reliably image circuit features at 65nm, but extending that capability to 45nm and below requires double patterning (the use of two separate exposures with slightly offset patterns).

Pixelligent says the R-CEL allows ultrahigh resolutions by virtue of the reversible photobleaching effect, which prevents interference between the two exposures. The R-CEL can be selectively bleached in one pattern to allow the lithography light to go through, then reversed to an opaque state and rebleached for the second-stage pattern.

Pixelligent sells its photoresists to traditional suppliers but also plans to license its nanocrystalline expertise to lithographic material suppliers.

- R. Colin Johnson
EE Times

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