21 August 2009 Improvements to optical performance in diffractive elements used for off-axis illumination
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As photolithographic tools are pressed to print the ever shrinking features required in today's devices, complex off-axis illumination is taking an ever increasing role in meeting this challenge. This, in turn, is driving tighter, more stringent requirements on the diffractive elements used in these illumination systems. Specifically, any imbalance in the poles of an off-axis illuminator will contribute to reductions in the ultimate imaging performance of a lithographic tool and increased complexity in tool-to-tool matching. The article will focus on improvements to the manufacturing process that achieve substantially better pole balance. The modeling of the possible process contributors will be discussed. Challenges resulting from the manufacturing methodology will be shared. Finally, the improvement in manufacturing process performance will be reported by means of a pole balance capability index.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kevin Welch, Adam Fedor, Daniel Felder, John Childers, Tim Emig, "Improvements to optical performance in diffractive elements used for off-axis illumination", Proc. SPIE 7430, Laser Beam Shaping X, 743005 (21 August 2009); doi: 10.1117/12.827396; https://doi.org/10.1117/12.827396

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