Feb 4, 2008
Nanoimprint lithography moves into markets
Nanosprint's "NanoTransfer" event brought together three key players in the field of nanoimprint lithography (NIL) for an exclusive panel discussion on future industrial applications. nanotechweb.org was there to find out what they had to say.
Lars Montelius of Lund University's Nanometer Structure Consortium, Sweden, had set the scene earlier in the day with his keynote on the development of NIL from a research tool to an industrial technology.
In the mid-1990s, Stephen Chou and his team (then based at the University of Minnesota and now Princeton University, both US) showed that it was possible to make a 6 nm feature using a stamp in polymer material. The result pointed to a low-cost way of making structures beyond the reach of conventional lithography techniques and arguably marked the birth of NIL.
"Around 1996-1997, we set up a small NIL machine in our lab," said Montelius. "Our ambition was to have a system that could print over a large area." Fast forward to 2008 and Montelius now sits on the board of Obducat, a Swedish firm that is busy commercializing nanoimprint technology originally developed by the Lund University group. Scaling up, the company's latest systems can now handle 90 wafers (up to 8 inch in diameter) per hour.
"NIL makes sense as soon as you have to make small dimensions over a wafer-sized area," said Pascal Gubbini of Molecular Imprints, a US-based developer of NIL systems. "We have a NIL solution for the makers of hard disk drives that delivers 20 nm cost-efficient features today."
Markets and more
Molecular Imprints has shipped four of its systems to three major hard disk drive manufacturers, adding to the evidence that non-volatile memory is shaping up to be one of the big applications for NIL. "The only economical way to put non-volatile memory on a smaller area is to use NIL," commented Gubbini. "For makers of hard disk drives, NIL patterned media is the key to maintaining their density roadmap."
But it's not just about magnetic media, the optics industry has also taken a shine to NIL and optoelectronics is next in line to embrace the technology. The manufacturing process has captured the imagination of the big names and as Montelius pointed out, Samsung, Sony and LG are all selling products today that feature components made by NIL.
Photonics powerhouse Jenoptik is using the technique to fabricate optical and fluidic devices. The firm's hot embossing process provides highly precise moulding of micro and nanostructures. With a 300 mm (12 inch) imprint area, the company's HEX04 unit is designed for high-volume applications. Manufacturing trials have shown that the equipment can deliver 28,000 fluidic chips for blood testing, in 8 hours.
"In situ point of care treatment has potential for NIL," said Erico Piechotka of Jenoptik's optical systems division. "We could see strong developments over the next 20–30 years."
Other applications put forward during the session include the patterning of substrates for nanowire growth as well as the production of functionalized surfaces for biochips.
Each supplier has its own variation on the theme, but NIL essentially involves coating a substrate with an imprint material, stamping the soft surface with a template, fixing the impression (typically by exposure to UV radiation) and then removing the stamp. The procedure is completed by an etching process that transfers the impression permanently into the substrate.
As Gubbini revealed, the economics of NIL are attractive. "You are looking at less than $10 million for a sub-32 nm CMOS imprint lithography production tool or around $100,000 for a basic research system," he said. "The capital costs of NIL are much lower than UV lithography, perhaps by a factor of 10."
Let there be light
Pricing is key to LED makers, but then again so is performance. Developers are racing to improve the amount of light that can be extracted from their chips and inserting an NIL-produced photonic crystal into the LED package is one of the options being considered.
Today, as much as half of the light generated by high-brightness LEDs can become trapped within the device. Nanometre-scale periodic structures have been shown to improve light extraction, outperforming index matching or surface roughening techniques and present a golden opportunity for NIL.
"We have sold tools to the LED industry," said Gubbini. "But they need to validate the changes to their manufacturing process, which means that it's going to take one to two years before they can go into mass production of enhanced devices."
About the author
James Tyrrell is editor of nanotechweb.org.