Magnetic Mitigation of Debris for EUV Sources

摘要

Extreme Ultraviolet (EUV) lithography sources expel high-energy ions and neutral particles, which degrade the quality of the collector optic. The mitigation of this debris is one of the main problems facing potential manufacturers of EUV sources. The use of magnetic fields to deflect ionic debris has been proposed and is investigated here. In this paper, we present a detailed computational model of magnetic mitigation, along with experimental results that confirm the correctness of the model. Using a strong permanent magnet, it is experimentally shown that, using high enough fields, magnetic mitigation can be a successful method of deflecting ionic debris from an EUV source. For example, through an orifice centered at 0° from the pinch, we saw a flux of 1.65×10~8 +/- 1.5×10~7 ions/(m~(2*)pulse~*eV) of 4keV ions without deflection and a negligible flux with deflection. With the orifice at a 35° angle from the pinch, a negligible 4keV flux was seen without deflection. However, with magnetic deflection, a 4keV flux of 1.03×10~8 +/- 9.4×10~6 ions/(m~(2*)pulse~*eV) were seen. The half-angle spread of the orifice was .047° with a tolerance of .008°.