Alternating phase-shifting mask with reduced aberration sensitivity: lithography considerations

Alfred K. K. Wong; Lars W. Liebmann; Antoinette F. Molless

doi:10.1117/12.435742

14 September 2001 Alternating phase-shifting mask with reduced aberration sensitivity: lithography considerations

Alfred K. K. Wong, Lars W. Liebmann, Antoinette F. Molless

Proceedings Volume 4346, Optical Microlithography XIV; (2001) https://doi.org/10.1117/12.435742
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

Abstract

Aberration sensitivity of alternating phase-shifting masks (PSMs) can be reduced by taking advantage of the trim exposure. Rather than a single phase region bordering each edge of a line, the enhanced alternating PSM technique uses multiple phase regions. The number of phase regions and their widths can be optimized for overall process tolerance including aberration sensitivity and exposure latitude. For exposure with a wavelength of 248 nm and a numerical aperture of 0.68, the optimal number of phase regions is two, with widths between 100 nm and 200 nm. These auxiliary phase regions do not affect the final pattern if a light-field trim mask is used. No extra processing step is necessary. With the enhanced alternating PSM technique, isolated lines of average dimension as small as 36 nm can be delineated using 248 nm lithography with a 3(sigma) linewidth control of 13.4 nm. The mean critical dimension of 36 nm corresponds to k₁ equals 0.1.

Citation Download Citation

Alfred K. K. Wong, Lars W. Liebmann, and Antoinette F. Molless "Alternating phase-shifting mask with reduced aberration sensitivity: lithography considerations", Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); https://doi.org/10.1117/12.435742

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