22 August 2009 Improvements to optical performance in diffractive elements used for off-axis illumination
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Proceedings Volume 7430, Laser Beam Shaping X; 743005 (2009); doi: 10.1117/12.827396
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States
Abstract
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.
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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 (22 August 2009); doi: 10.1117/12.827396; https://doi.org/10.1117/12.827396
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KEYWORDS
Diffractive optical elements

Manufacturing

Optical alignment

Overlay metrology

Diffraction gratings

Fiber optic illuminators

Source mask optimization

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