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21 June 2006 A correlation for predicting film-pulling velocity in immersion lithography
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Proceedings Volume 6281, 22nd European Mask and Lithography Conference; 62810Q (2006)
Event: 22nd European Mask and Lithography Conference, 2006, Dresden, Germany
Immersion lithography seeks to extend the resolution of optical lithography by filling the gap between the final optical element and the wafer with a liquid characterized by a high index of refraction. Several engineering obstacles are associated with the insertion of the immersion fluid. One issue that has recently been identified is the deposition of the immersion liquid onto the wafer from the receding contact line during the scanning process; any residual liquid left on the wafer represents a potential source of defects. The process of residual liquid deposition is strongly dependent on the behavior of the receding three-phase contact line. This paper focuses on an experimental investigation of this behavior under conditions that are relevant to immersion lithography. Specifically, the static and dynamic contact angle and the critical velocity for liquid deposition are presented together with a semi-empirical correlation developed from these measurements. The correlation allows the film-pulling velocity to be predicted for a given resist-coated surface using only a measurement of the static receding contact angle and knowledge of the fluid properties. This correlation represents a useful tool that can serve to approximately guide the development of resists for immersion systems as well as to evaluate alternative immersion fluid candidates to minimize film pulling and defects while maximizing throughput.
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Scott Schuetter, Timothy Shedd, Keith Doxtator, Gregory Nellis, and Chris Van Peski "A correlation for predicting film-pulling velocity in immersion lithography", Proc. SPIE 6281, 22nd European Mask and Lithography Conference, 62810Q (21 June 2006);

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