SPIE Preview: EUV vs. optical battle, “alternatives” get attention

by Griff Resor, Resor Associates

February 22, 2010 – The SPIE Advanced Lithography Conference in San Jose, CA, provides a once-a-year opportunity to see the future of IC manufacturing. For years, this has been the conference where experts in lithography, resists, metrology, and design come to tell about their recent advances. Typically the good ideas move into IC production within two to three years.

Everyone will be watching the battle between optical lithography and EUV, which for the first time will have its own conference. The EUV conference has 127 papers — compared to 124 for the optical lithography conference, a huge advance for EUV in just one year — mostly aimed at high-volume insertion at the 22nm node by 2013. It will be interesting to learn how attendees feel about this schedule. Key challenges for EUV remain mask defects, resist resolution, and line-edge roughness (LER), and source power. As source power increases, there is a renewed concern for the lifetime of mirrors in the EUV optical train. I expect to hear credible evidence that progress on resist, sources, and lifetime will support the schedule. Progress on EUV mask defects is not so certain, so will set the pace from this week on.

The optical lithography conference has 124 papers, evenly split between the 32nm and 22 nm nodes. Computer modeling to optimize what’s left for a process window is the #1 topic (30 papers); double patterning comes in second (17 papers). For several years now it has been clear that some form of double patterning lithography (DPL) would be required to move optical lithography to the next node. Many variations on this theme will be reported this week. With overlay error budgets in the single digits of nanometers, masks and matching of scanner tools are also key topics.

A quick scan of the resist track’s 123 papers provides a sanity check on the EUV vs. optical lithography battle. Thirty-six of the resist papers describe optical and DPL materials and methods; 18 papers discuss products for EUV use. Many papers describe generic improvements in materials. It seems that material suppliers still see a larger market for optical and DPL products than for EUV products.

Three emerging technologies are the focus of the "alternative lithography" track. 26 papers describe direct writing tools, most using multi-beam e-beam. IC foundries such as TSMC are pushing for these tools as a workaround to the ever higher cost of masks for optical and EUV lithography. Nano-imprint lithography (NIL) continues to conquer new applications — structured media for high-density disk drives looks like a natural, and will be covered this week. Finally, self-assembly techniques continue to get attention, as nano-structures built in the IC industry and biotechnology converge.

After a busy week, Griff will report on his findings at this key lithography conference next week.

Griff Resor, an SST editorial advisory board member, is president of Resor Associates, ph 978-897-2200, e-mail [email protected].


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