Presentation + Paper
28 April 2023 EUV sub-resolution assist feature impact: experimental and simulation evaluation
Author Affiliations +
Abstract
Aggressive off-axis illumination must be used to resolve line space pitches of 28nm and below. The consequence is that the best focus (BF) shifts a lot and depth of focus shrinks rapidly through pitch. This is mainly due to the mask 3D effects. To reduce the impact the best-known method is to introduce sub-resolution assist features (SRAF). We explored wafer printing with SARF size of 6-8 nm and analyzed BF and DOF impact. Clear SRAF sizes of 6-8 nm do not print with PCAR but some 7-8 nm clear SRAF printed with NTD MOR due to the higher resolution and over exposure preference. Then we validated the experiments with SLITHO simulation tool, and we found a good experiment-simulation match of BF/DOF/EL/MEF w and w/o SRAF through pitch with the three P28 illumination candidates. Overall SRAF can improve the DOF and exposure latitude (EL) for the given pitches with SRAF capable and help shift the BF to the favored focus direction. With the validated model we further study BF/DOF/EL/MEF w and w/o SRAF through pitch with the small/medium/large sigma illuminations designed for 28nm pitch, with traditional TaBN and other three candidate absorbers. We will also discuss the SRAF size and placement sensitivities. Through this work we are confident to implement SRAF to enlarge the common process window for a large range of pitches.
Conference Presentation
© (2023) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zheng Chen, Martin Burkhardt, Stuart Sieg, and Luciana Meli "EUV sub-resolution assist feature impact: experimental and simulation evaluation", Proc. SPIE 12494, Optical and EUV Nanolithography XXXVI, 124940U (28 April 2023); https://doi.org/10.1117/12.2657634
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KEYWORDS
SRAF

Light sources and illumination

Printing

Electroluminescence

Extreme ultraviolet

Line edge roughness

Nickel

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