SPIE Advanced Lithography and Patterning Symposium 2024 – day 3

Wednesday was the peak of busy for me, attending many papers (and giving one).  It was also a very typical day in that almost all of the papers I saw were exactly what I expected:  incremental advances.  Nothing jaw dropping, just the small advances that have fueled this industry’s progress for the 40 years I have been involved. 

Jodi Grzeskowiak of TEL did a great job explaining their new “anti-spacer” process, using acid diffusion into a resist pattern to form a skin that turns into a negative tone version of a spacer pattern.  She described it as a “track-based pitch split.”  I was especially happy that the process didn’t have a cute acronym with a trademark symbol and no description of how it worked.

Indira Seshadri of IBM showed off what IBM is good at, optimizing all aspect of a process (in this case the Lam dry resist) to get high yield at tight pitches.  Hyeon Bo Shim of Samsung provided a simple geometric model for how electrons escape out of a contact hole (for the case of vertical sidewalls only), showing that the aspect ratio controls the visibility of the hole bottom.  Since I am a coauthor (with Ben Bunday) on a paper on a similar topic on Thursday, I was especially interested.  I’ve already checked out this Samsung geometric model against our SEM simulations and it works surprisingly well.

Boris Habets (KLA) collected overlay data on the “micron scale”.  He was able to measure overlay directly on the device, but did so in a memory cell so that he could achieve extremely high sampling over length scales we don’t normally interrogate.  Over a distance of a few microns overlay variations are not due to scanner effects, but rather shorter-range proximity effects.  In this case, each memory array tile (a few microns square) had a regular signature, possibly due to film stress relaxation.  The magnitude was a few tenths of a nanometer, but if stable and consistent would be correctable on the mask.

I attempted to attend the panel discussion on the future of EUV lithography, but was unsuccessful.  The event was standing room only, and I was unwilling the elbow my way through the crowd standing three deep at the door.  I hope it was useful.  I did make it to the poster session, however, and actually walked the whole circuit.  There were some nice posters and a fun crowd.

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