Does anyone know what the wattage of the LPP light source China has reached with EUV research? This was the bottleneck of EUV for over a decade. Western sources were rather transparent. For instance, by 2011 Cymer had reached 11 W, by 2013 ASML had reached 55 W, by 2016 it reached 200 W. Once it reached 250 W it enabled EUV. The key to increasing wattage was prepulse”—a low-intensity laser that flattens each tin droplet into a pancake shape so that more of its area is hit by the main, vaporizing laser. The basic approach isn’t all that new—Cymer presented early results on the prepulse approach in 2011. But thanks to a combination of modeling and experimentation, ASML has been optimizing the process. “The reason why the progress has been so dramatic in the last year—maybe year and a half—is understanding the physics of what’s happening in that process,” says (ASML marketing director) Michael Lercel. “It’s a lot of things that really are at the cutting edge of the plasma physics.”
What physics is he referring to?
