26 March 2007 Thermal aberration control for low-k1 lithography
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For many years, we have used a lens aberration controller that works via positioning elements of the projection lens assembly. While this has worked well, its disadvantage is that controllable aberrations are only relatively low order components and not enough for the degree of compensation of thermal aberrations required by leading-edge lithography. We have developed two methods to overcome thermal aberrations specific to dipole illumination exposure. One scheme is process-dedicated aberration control by the conventional aberration controller. The other is aberration control system using infra-red irradiation. This system can compensate uniform astigmatism which is generated by asymmetric setting of illumination light sources, such as dipole illumination schemes. Theses two techniques allow us to increase productivity by reducing pattern imaging performance degradation due to thermal aberrations. These schemes are applicable not only to current systems but also to next generation very low k1 lithography systems with very high throughput.
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Yusaku Uehara, Yusaku Uehara, Tomoyuki Matsuyama, Tomoyuki Matsuyama, Toshiharu Nakashima, Toshiharu Nakashima, Yasuhiro Ohmura, Yasuhiro Ohmura, Taro Ogata, Taro Ogata, Kosuke Suzuki, Kosuke Suzuki, Noriaki Tokuda, Noriaki Tokuda, } "Thermal aberration control for low-k1 lithography", Proc. SPIE 6520, Optical Microlithography XX, 65202V (26 March 2007); doi: 10.1117/12.711440; https://doi.org/10.1117/12.711440

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