29 June 1998 Feasibility studies of operating KrF lasers at ultranarrow spectral bandwidths for 0.18-μm line widths
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The use of higher NA lenses and higher throughput of the next generation 248 nm microlithography systems sets tight requirements on the spectral properties of the laser as well as its power output and dose stability. We demonstrate that such scaling of spectral widths, power and repetition rates is possible by revisiting some of the dynamics of evolution of laser spectrum and stability of laser discharge. In the following, we present results of several optical configurations, that result in spectral widths between 1.0 and 2.0 pm (95% integrated linewidth). The optical configurations are derivatives of Cymer's standard Littrow grating and prism expander configuration. Thereby, the other parameters (beam size, coherence, etc.) are not impacted. Simultaneously, we provide results of scaling a laser to 2 kHz with a dose stability of less than plus or minus 0.5% over a 16 ms window. The resulting laser is now capable of meeting the technical requirements of the next generation microlithography scanners.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Alexander I. Ershov, Alexander I. Ershov, Thomas Hofmann, Thomas Hofmann, William N. Partlo, William N. Partlo, Igor V. Fomenkov, Igor V. Fomenkov, George Everage, George Everage, Palash P. Das, Palash P. Das, Dave Myers, Dave Myers, } "Feasibility studies of operating KrF lasers at ultranarrow spectral bandwidths for 0.18-μm line widths", Proc. SPIE 3334, Optical Microlithography XI, (29 June 1998); doi: 10.1117/12.310732; https://doi.org/10.1117/12.310732

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