Impact of long-period line-edge roughness (LER) on accuracy in CD measurement

Atsuko Yamaguchi; Hiroshi Fukuda; Hiroki Kawada; Takashi Iizumi

doi:10.1117/12.602674

10 May 2005 Impact of long-period line-edge roughness (LER) on accuracy in CD measurement

Atsuko Yamaguchi, Hiroshi Fukuda, Hiroki Kawada, Takashi Iizumi

Proceedings Volume 5752, Metrology, Inspection, and Process Control for Microlithography XIX; (2005) https://doi.org/10.1117/12.602674
Event: Microlithography 2005, 2005, San Jose, California, United States

Abstract

The influence of long-period line-edge roughness (LER) on measured critical-dimension (CD) values is identified, and a guideline for LER-impact-free CD measurement is introduced. There are two kinds of meanings of CD, one is the average pattern-size calculated in a limited area (i.e., local CD), and the other is the representative pattern-size (average CD). The width of a line pattern measured by CD-SEM is a local CD, which deviates from the average CD because of long-period LER. This LER impact on the CD measurement is investigated in two typical measurements of CD-SEM, evaluation of across-wafer CD-variation and dynamic repeatability of the equipment. It is shown that both results strongly depend upon the height of the inspection area along the line-edge (L) because of long-period LER. It is found that a large L can reduce the LER-impact, and a 2-μm inspection-area or more is recommended for CD measurements. Furthermore, the validity and limitation of the patchwork method, in which several inspection areas are connected to obtain one large area, is examined.

Citation Download Citation

Atsuko Yamaguchi, Hiroshi Fukuda, Hiroki Kawada, and Takashi Iizumi "Impact of long-period line-edge roughness (LER) on accuracy in CD measurement", Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005); https://doi.org/10.1117/12.602674

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