Origins of Debris and Mitigation through a Secondary RF Plasma system for Discharge-Produced EUV Sources

February 1, 2005

Microelectronics Engineering, 77, 95-102 (2005).

Vargas-Lopez, E., Jurczyk, B. E., Jaworski, M. A., Neumann, M. J., Ruzic, D. N.

RF plasma based mitigation has been studied as an improved debris mitigation scheme for extreme ultraviolet (EUV) sources. The RF plasma ionizes sputtered neutral debris and, when used in conjunction with a collimator (also known as a foil trap), inhibits that debris from reaching the collector optics. An ionization fraction of 61 ± 3% has been measured. In addition, increased scattering of the ion component of the debris has led to a decrease in erosive flux reaching the diagnostics. Results from in situ high-precision quartz crystal oscillators, ex situ surface characterization (Auger, XPS), and secondary plasma characterization is presented for a series of mitigation schemes, including a foil trap in conjunction with the RF plasma.