@article{7938,
  author = {A. Dolgov and D. Lopaev and T. Rachimova and A. Kovalev and A. Vasil'Eva and C. J. Lee and V. M. Krivtsun and O. Yakushev and F. Bijkerk},
  title = {Comparison of H2 and He carbon cleaning mechanisms in extreme ultraviolet induced and surface wave discharge plasmas},
  abstract = {Cleaning of contamination of optical surfaces by amorphous carbon (a-C) is highly relevant for extreme ultraviolet (EUV) lithography. We have studied the mechanisms for a-C removal from a Si surface. By comparing a-C removal in a surface wave discharge (SWD) plasma and an EUV-induced plasma, the cleaning mechanisms for hydrogen and helium gas environments were determined. The C-atom removal per incident ion was estimated for different sample bias voltages and ion fluxes. It was found that H2 plasmas generally had higher cleaning rates than He plasmas: up to seven times higher for more negatively biased samples in EUV-induced plasma. Moreover, for H2, EUV-induced plasma was found to be 2-3 times more efficient at removing carbon than the SWD plasma. It was observed that carbon removal during exposure to He is due to physical sputtering by He+ ions. In H2, on the other hand, the increase in carbon removal rates is due to chemical sputtering. This is a new C cleaning mechanism for EUV-induced plasma, which we call 'EUV-reactive ion sputtering'. © 2014 IOP Publishing Ltd.},
  year = {2014},
  journal = {Journal of Physics D: Applied Physics},
  volume = {47},
  pages = {065205},
  url = {http://doc.utwente.nl/88098/},
  doi = {10.1088/0022-3727/47/6/065205},
  language = {eng},
}