At the EUVA, for both the LPP and DPP methods, the brightness of the light source successfully reached 10 W or more at the intermediate focus, which is the highest level in the world. The EUVA has promoted research on the light source aiming at increasing the brightness up to 50 W by the end of 2007. Figure 1 shows the benchmark of the output data for both the LPP and DPP methods developed by the EUVA. This demonstrates the world-class performance of both the LPP and DPP methods.
The EUVA Gotenba Center has developed the DPP method (figure 2)₁₎. It has already achieved 43 W at IF (Intermediate Focus) by using a combination of the Sn target and high-speed power supply, and is just one step away from the target of 50 W. Currently, work is underway on advanced engineering challenges, such as extending both the life of the electrode and the life of the condenser mirror. The EUVA Gotenba Center proved, for the first time in the world, a unique discharge method that uses stannum gas (SnH4) as a discharge gas and recorded world-class output.
On the other hand, the EUVA Hiratsuka Center has developed the LPP method (figure 3) ₂₎. The LPP method mainly uses a combination of the Xe target and the YAG laser. However, the Hiratsuka Center has developed a unique method (patent pending) that combines the Sn target with a high-repetition-rate pulse CO₂ laser, and it has already achieved 10 W at IF, which is currently the top output level in the world. This method theoretically has no limitation to increasing the output, so that it is expected to achieve a high-output light source of 100 W or more. The Hiratsuka Center is currently working on the conflicting challenges of preventing contamination of the mirror with debris at the Sn target and increasing the output, and it has developed technologies that are unique in the world, such as protection of plasma with magnetic fields.
In addition, in parallel with the development of light sources with higher performance, the EUVA and Selete (Semiconductor Leading-Edge Technologies) have jointly developed a Small Field Exposure Tool (SFET) with a small field, which used for researching EUV processes at the Tsukuba R&D Center. Even though this exposure tool has a small angle of view, it has been developed as an exposure tool that can achieve the resolution required for imaging the line and space of 32 nm. The light source group at the EUVA provides a 0.5-W LPP light source that uses an excimer laser as a driver (figure 4)₃₎. From FY2006, this SFET exposure tool will start being used to conduct EUV exposure tests, and it will be fully used as a powerful tool for development of EUV lithography processes.

Figure 1. EUVA’s Benchmark for Development of the DPP and LPP Methods

Figure 2. DPP Test at the EUVA Gotenba Center ₄₎

Figure 3. LPP Test at the EUVA Hiratsuka Center₄₎

Figure 4. A 0.5-W Light Source for SFET ₄₎

< References >

1. G. Niimi, Y. Teramoto, H. Sato, K. Bessho, T. Shirai, D. Yamatani, Y. Joshima, T. Takemura, H. Yabuta, T. Yokota, K. C. Paul, K. Kabuki, K. Miyauchi, K. Hotta, M. Yoshioka, K. Toyoda, EMERGING LITHOGRAPHIC TECHNOLOGIES X (21－23 February 2006,Santa Jose, California, USA) Proceedings of SPIE Vol. #6151 [6151-149]
2. H. Mizoguchi, A. Endo, T. Ariga, T. Miura, H. Hoshino, Y. Ueno, M. Nakano, H. Komori, A. Sumitani, T. Abe, T. Suganuma, G. Soumagne, H. Someya, Y. Takabayashi, K. Toyoda, EMERGING LITHOGRAPHIC TECHNOLOGIES X (21－23 February 2006,Santa Jose, California, USA) Proceedings of SPIE Vol. #6151 [6151-27].
3. G. Soumagne, T. Abe, Y. Itakura, M. Moriya, H. Someya, T. Suganuma, T. Watanabe, A. Sumitani, A. Endo, and H. Mizoguchi: Emerging Lithographic Technologies X (21–23 February 2006, Santa Jose, California, USA), Proceedings of SPIE, Vol. 6151 [6151-133].
4. EUV Website: http://www.euva.or.jp/index.html.

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