By Tuesday my focus has fully shifted to attending technical talks. This has gotten easier for me in the last few years since I am becoming less of a generalist and more of a specialist on line-edge roughness (LER). I search out all the LER papers first, and then find other interesting topics to listen too when there aren’t any LER papers to hear.

I started in the optical lithography session, with three very good invited talks. Prof. Zhang of Berkeley gave an informative talk on the hot science topics of super-lenses, plasmonic imaging, and negative refractive index metamaterials. Fascinating stuff, showing that looking at old physics in new ways can lead to very strange results. It’s funny, though, to watch someone from the science research community address lithography. They frequently talk about “breaking the classical resolution limit” with their new approach. Then, they either show an isolated feature (which has no classical resolution limit), or a dense feature with a classical pitch limit of wavelength/NA. When they show a (very poor) result with resolved features of half of this “classical limit” (typically hundreds of nanometers in size since they use i-line), there is much rejoicing in Nature or Science. Ahem, excuse me? Look at all the results at this conference where the pitch is near 0.5*wavelength/NA, the images are beautiful, and we can print 10 billion of them for a dollar! Claims of revolutions in lithography aside, the science is still very good. There was also a great paper on transistor architectures beyond the metal gate MOSFET, and Luigi Capodieci talked about kumbaya lithography (can’t we all just work together?). Luigi had some of the most insightful statements I’ve heard so far this week: “We often call ‘random’ what we can’t model”, and the subtle switch from thinking about controlling variability to managing (i.e., living with) variability. His attempt to coin “computational technology” as an extension of computation lithography that includes design optimization will, I suspect, fall flat.

There was an LER metrology session in the morning, but I didn’t see anything to make me think that LER metrology has improved in the last year. Scattered throughout the day there were various resist papers addressing LER (both 193 and EUV). There has been some progress in figuring out how to lower acid diffusion, but overall the best LER numbers reported don’t seem to have changed in the last year. For EUV resists, the consensus seems to be that we should work on resolution and sensitivity improvements, and hope that LER will work itself out by the time we get to manufacturing. Maybe some post-develop treatment (a magic rinse) will reduce LER and make the problem go away. Maybe we can find a rinse that will make our CD variations across the wafer go away, too.

At the poster session, the difference between this year and years past was manifest. The number of posters looked to be down by two-thirds, and one could easily wander around and find all the posters of interest, with plate of Mexican food in hand, in 30 minutes. I gave a poster and the number of people who meandered past was quite minimal.

Finally, after a full day of technical papers, there was the “trial”, a mock trial of EUV versus double patterning (Kafka would have been pleased). People have said it was fun for everyone, and I hear that consensus put the conclusion at a draw. But I just couldn’t go. I needed a beer and so I unwound at Gordon Biersch. A little rest and I’ll be ready to do it all again tomorrow.