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Herein is described the most convenient manner to generate the precise wavelength of light required to print on EUV photomask: - A molten tin droplet drops in
by 11thEarlOfMar 5y ago
Herein is described the most convenient manner to generate the precise wavelength of light required to print on EUV photomask:
- A molten tin droplet drops into a vacuum
- It's pulsed by a high-power (25kW) laser
- Tin atoms are ionized, creating plasma
- A precision ground concave mirror captures EUV radiation emitted by plasma
- The Mirror transfers EUV to wafer (wavelength=13.5 nanometers, basically X-ray level, through a series of reducing lenses...)
- ragebol 5y agoApparently, they zap the tin droplet with a soft pulse first to flatten it before hitting it with a big pulse to make the plasma. A former colleague of mine worked on tuning the laser-hitting -droplet process. Happens inside a vacuum of course, but after some time the vacuum would always drop. Turns out that when you miss the droplet often enough and thus hit the steel walls of the chamber, eventually you'll punch through the walls. And not be able to hold a vacuum this way. Not sure of just a tall story or true...
- 11thEarlOfMar 5y agoThe vacuum chamber is likely aluminum. Tin melts at 232 C, aluminum at 660 C. Vaporizing the tin could require enough power in the laser to melt the aluminum. It seems feasible to me, anyway, and is certainly sounds like the kind of thing that happens in equipment development.