Rensselaer touts new polymer for conventional, nanoimprint litho

Feb. 2, 2008 – Scientists at Rensselaer Polytechnic Institute say a new cheaper, quick-drying polymer could enable better performance and lower costs in both conventional photolithography processes and on-chip nanoimprint lithography.

“With this new material, chip manufacturers will be able to trim several steps from their production and packaging processes,” said prof. Toh-Ming Lu, who oversaw the study, in a statement.

The new material, called “polyset epoxy siloxane” (PES), codeveloped with NY-based Polyset Co., offers advantages over benzocyclobutene and polyimide materials typically used as redistribution layers deposited onto silicon wafers to ease signal propagation delay and protect the surface, the researchers say. It cures at 165°C, about 35% cooler than those materials, and has <0.2% water uptake rate, less than the other materials. It also adheres well to Cu, "and can easily made less brittle if needed," they said in a statement.

Moreover, PES’ ability to also be used as a thin polymer film for UV on-chip nanoimprint litho would provide an easier transition to the newer litho process, something that should be “very attractive to manufacturers,” Lu noted. In a paper just published in the Journal of Vacuum Science & Technology B, they indicate SEM images of UV-cured patterns show “appealing resolution,” and <200nm features with imprint litho.

Scanning electron microscope image of PES in a UV-imprint lithography application shows a well-defined pattern. (Source: Rensselaer)

“The results demonstrate that PES is feasible to be used as UV-curable resist for both the redistribution application for electronic packaging and micro/nano imprint lithography,” said Rensselaer research associate Pei-I Wang, co-author of the paper. He noted that it also has potential in applications in other optical devcies, flat-panel displays, biotech devices, and microelectromechanical systems (MEMS).

Interestingly, Applied Materials seems to figure prominently in this work — two of the paper’s coauthors are from AMAT, including CTO Omkaram Nalamasu, and another is from Santa Clara-based Transfer Devices, which is funded by AMAT’s VC arm.

The Rensselaer research appears in the Jan. issue of the Journal of Vacuum Science and Technology B.


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