Method of characteristic signatures matching through discrepancy enhanced library generation process

Wang, Shih-Chun; Ku, Yi-Sha; Ko, Chun-Hung; Smith, Nigel

doi:10.1117/12.616383

Cited by 2 publications

(1 citation statement)

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“…Another difficulty of the theoretical modeling method is that the sensitivity of the scatterometry signal to overlay is significant smaller than the sensitivity to other parameters in general, such as film thickness or critical dimension (CD). Thus, small errors in the inferring of other parameters from measurements of diffracted signatures may lead to large errors in an overlay estimate [5,6]. An alternative is a full empirical solution, which involves measurements of the spectra corresponding to intentional overlay offsets written to the reticle.…”

Section: Introductionmentioning

confidence: 98%

Improved diffraction-based overlay metrology by use of two dimensional array target

Pang

Hsu

et al. 2009

SPIE Proceedings

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We report results of theoretical modeling into a scatterometry-based method relevant to overlay measurement. A set of two array targets were designed with intentional offsets difference, d and d+20 nm, between the top and bottom grid arrays along the X and Y directions. The correlation of bi-azimuth measurements is the first critical issue been taken into account. The method linearizes the differential values of scatterometry signatures at the first diffraction order with respect to designed offsets, and hence permits determination of overlay using a classical linear method. By evaluating the process variations (eg. CD, roundness and thickness) on overlay measurement error, a set of two overlay target design were optimized to minimize the correlation of bi-azimuth measurements and maximize the measurement sensitivity.

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Section: Introductionmentioning

confidence: 98%