Analysis, simulation, and experimental studies of YAG and CO[sub]2[/sub] laser-produced plasma for EUV lithography sources

A. Hassanein; V. Sizyuk; S. S. Harilal; T. Sizyuk

doi:10.1117/12.848222

19 March 2010 Analysis, simulation, and experimental studies of YAG and CO₂ laser-produced plasma for EUV lithography sources

A. Hassanein, V. Sizyuk, S. S. Harilal, T. Sizyuk

Author Affiliations +

Proceedings Volume 7636, Extreme Ultraviolet (EUV) Lithography; 76360A (2010) https://doi.org/10.1117/12.848222
Event: SPIE Advanced Lithography, 2010, San Jose, California, United States

Abstract

Efficient laser systems are essential for the realization of high volume manufacturing in extreme ultraviolet lithography (EUVL). Solid-state Nd:YAG lasers usually have lower efficiency and source suppliers are alternatively investigating the use of high power CO₂ laser systems. However, CO₂ laser-produced plasmas (LPP) have specific characteristics and features that should be taken into account when considering them as the light source for EUVL. The analysis of recent experimental and theoretical work showed significant differences in the properties of plasma plumes produced by CO₂ and the Nd:YAG lasers including EUV radiation emission, source formation, debris generation, and conversion efficiency. The much higher reflectivity of CO₂ laser from liquid, vapor, and plasma of a tin target results in the production of optically thinner plumes with higher velocity and in a better formation of plasma properties (temperature and density values) towards more efficient EUV source. However, the spikes in the temporal profiles of current CO₂ laser will additionally affect the properties of the produced plasma. We have developed unique combination of state-of-the-art experimental facilities (CMUXE Laboratory) and advanced computer simulation (HEIGHTS) package for studying and optimizing various lasers, discharge produced plasmas (DPP), and target parameters as well as the optical collection system regarding EUV lithography. In this work, detailed characteristics of plasmas produced by CO₂ and Nd:YAG lasers were analyzed and compared both experimentally and theoretically for optimizing EUV from LPP sources. The details of lower overheating of plasma produced by CO₂ laser are given with time and explain how to utilize the high reflectivity of such lasers in plasmas produced in different target geometries to significantly enhance the conversion efficiency of EUV radiation.

Citation Download Citation

A. Hassanein, V. Sizyuk, S. S. Harilal, and T. Sizyuk "Analysis, simulation, and experimental studies of YAG and CO₂ laser-produced plasma for EUV lithography sources", Proc. SPIE 7636, Extreme Ultraviolet (EUV) Lithography, 76360A (19 March 2010); https://doi.org/10.1117/12.848222

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