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20 May 2004 Performance and scaling of a dense plasma focus light source for EUV lithography
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Over the past several years, a continuous improvement of the performance parameters of discharge produced plasmas as potential sources of 13.5 nm radiation for commercial EUV lithography systems has been achieved. At Cymer we have continued developing the dense plasma focus (DPF) discharge as an EUV source. The majority of the data presented here is focused on DPF operation with xenon gas. We have recently started investigating the DPF operation with Sn, as well. A significant improvement in conversion efficiency (CE) was observed. We have investigated DPF configurations with different polarity of the drive voltage. Central to both configurations is the pulsed power system, which is being developed to operate in continuous mode at 5 kHz while delivering approximately 10 J to the load. Significant differences have been observed for the energy deposition profiles in the positive and negative polarity systems. Calorimetric data show that the fraction of energy deposited into each discharge electrode depends on the polarity. The thermal engineering of the central electrode remains a major challenge. With the present generation DPF we have demonstrated operation at 5 kHz in burst mode and at 2.3 kHz in continuous mode, with 76 W of in-band energy generated at the source. We observed that certain transient effects in the EUV output were correlated with the degree of energy coupling during the burst. However, we found that the pulsed power system is well matched to the load with >90% of the stored energy coupled to the discharge and electrodes. The conversion efficiency of the DPF operated with Xe is near 0.5% for both polarities, while measurements with Sn show a CE ~1.7%. Plasma modeling supported the optimization of the pinch dynamics and electrodes. Debris mitigation studies were also carried out and the carbon contamination was reduced.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Igor V. Fomenkov, Richard M. Ness, Ian Roger Oliver, Stephan T. Melnychuk, Oleh V. Khodykin, Norbert R. Boewering, Curtis L. Rettig, and Jerzy R. Hoffman "Performance and scaling of a dense plasma focus light source for EUV lithography", Proc. SPIE 5374, Emerging Lithographic Technologies VIII, (20 May 2004);


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