Litho Guru Optimistic About Nanoimprint
Laura Peters, Editor-in-Chief -- Semiconductor International, 4/30/2008 7:36:00 AM
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Eynon also provided an update on the challenges that EUV lithography has yet to overcome. “We look for the weakest link in going from ArF to EUV.” These include development of photoresist, autofocus, pellicle, reflector, absorber, optics, debris mitigation, a vacuum processing environment, mask handling, mask haze, shadowing and chucking. Then, once EUV is established in high-volume manufacturing, taking it to the next level will involve the usual additions of high-numerical-aperture (NA) optics, phase-shift masks, optical proximity correction (OPC), etc. Among these, the top challenge (Table) is developing a source with adequate power — at least 100 W is necessary. One of the candidates for the high-index photoresist that Sematech is testing is hafnium oxide nanoparticles suspended in water — although the shelf life of this material is not encouraging. Mask blanks with 0.04 defects/cm2 at 53 nm have recently been achieved, a big breakthrough according to Eynon. A new reticle inspection tool (M7360), priced at $10M, is allowing researchers to see even smaller defects than was possible with the previous-generation tool. In addition, a smoothing process has been developed — a deposition and etch process that can smooth, for instance, a 50 nm pit to 1 nm in dimension. “With this smoothing method and other techniques, we can get to the point where we don’t need completely defect-free masks, but can have a manageable level for manufacturing,” Eynon said.
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At the 2008 Litho Forum, hosted by Sematech, participants will vote on the most likely technology to meet the high-volume production needs of the 22 nm node. When the group voted in 2006, EUV was unanimously chosen as the technique of choice for 22 nm in the year 2012. Unfortunately, even Intel (Santa Clara, Calif.) admits that EUV will not be ready for 22 nm, so immersion lithography with high-index materials or double patterning will have to come into play.
Stay tuned for our coverage of the Litho Forum.
