Nanolithography goes high-speed

Fabrication and processing

May 8, 2008

Polymer grating pattern imprinted on a flexible strip by R2RNIL. (Courtesy of L. Jay Guo.)

Nanoimprint lithography (NIL) is a technique for nanometer-scale patterning of the flexible substrates used in photonics, electronics, biotechnology, and renewable energy devices. However, low throughput has so far been a major obstacle in making this a commercially viable technique.

Now researchers from the University of Michigan have succeeded in overcoming this problem, by devising a method called roll-to-roll nanoimprint lithography (R2RNIL) that is 20 times faster than conventional nanoimprint methods [Ahn and Guo, Adv. Mater. (2008), doi:10.1002/adma.200702650].

L. Jay Guo explains, “Our work targets a bottleneck in nanostructure fabrication for many practical applications and could push nanoscale lithography to an entirely new level with drastically increased throughput.”

Unlike conventional NIL methods, R2RNIL uses a mold in the form of a roller, and the mold-sample separation proceeds in a ‘peeling’ fashion. This requires much less force to imprint a large surface area, and reduces the probability of defect generation.

To demonstrate the efficacy of their technique, Guo and Ahn used R2RNIL to continuously imprint 70 nm polymer patterns on a flexible strip. Such a task would have been very problematic using conventional NIL.

“The notion of roll-to-roll nanolithography is certainly appealing, due to its potential for use in low cost, high volume applications”, comments John A. Rogers, of the University of Illinois at Urbana-Champaign. “These results represent the most sophisticated implementation of nanoimprint lithography”.

Guo plans to scale up the technique to print large-area plastic webs and on rigid substrates such as glass, adding that he is very encouraged by his team’s initial results.

Andrea Taroni