Correlating overlay metrology precision to interlayer dielectric film properties

Kris R. Paserba

doi:10.1117/12.771723

24 March 2008 Correlating overlay metrology precision to interlayer dielectric film properties

Kris R. Paserba

Proceedings Volume 6922, Metrology, Inspection, and Process Control for Microlithography XXII; 69221F (2008) https://doi.org/10.1117/12.771723
Event: SPIE Advanced Lithography, 2008, San Jose, California, United States

Abstract

Current ITRS projections indicate that overlay metrology measurement uncertainty requirements will be less than 1 nm by the year 2009. The challenge in attaining this level of precision for semiconductor and thin-film head (TFH) applications is complicated by the use of increasingly complex multilayer dielectric stacks in the fabricated devices. This paper details results from a fundamental study designed to quantify and understand the effects of dielectric film optical properties on overlay metrology uncertainty. Overlay precision was measured for a series of advanced imaging metrology (AIM) targets having a region of interest (ROI) ranging from 2.8 - 19.5 μm and mark pitch ranging from 1.9 - 4.5 μm. The interlayer dielectric (ILD) film separating the layers of relevance was systematically varied in both thickness (0 - 5 μm) and refractive index (1.60 - 2.54). A reasonable correlation is observed between the measured precision values and the Rayleigh optical thickness, indicating that the optical clarity of ILD films contributes significantly to the minimum achievable overlay metrology precision.

Citation Download Citation

Kris R. Paserba "Correlating overlay metrology precision to interlayer dielectric film properties", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69221F (24 March 2008); https://doi.org/10.1117/12.771723

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