Use of multiple azimuthal angles to enable advanced scatterometry applications

Matthew Sendelbach; Alok Vaid; Pedro Herrera; Ted Dziura; Michelle Zhang; Arun Srivatsa

doi:10.1117/12.846692

1 April 2010 Use of multiple azimuthal angles to enable advanced scatterometry applications

Matthew Sendelbach, Alok Vaid, Pedro Herrera, Ted Dziura, Michelle Zhang, Arun Srivatsa

Proceedings Volume 7638, Metrology, Inspection, and Process Control for Microlithography XXIV; 76381G (2010) https://doi.org/10.1117/12.846692
Event: SPIE Advanced Lithography, 2010, San Jose, California, United States

Abstract

The ability to extract critical parameters using scatterometry depends on the parameter sensitivity and correlation at different wavelengths. These, in turn, determine the key metrics: accuracy, precision, and tool-to-tool matching. Parameter sensitivity and correlation can vary drastically, depending on whether the oblique incident light beam is parallel (azimuth angle = 90 degrees), perpendicular (azimuth angle = 0 degrees), or at an intermediate angle to the measured structures. In this paper, we explore the use of both variable- and multiple-azimuth (AZ) (or multi-AZ) angle spectroscopic ellipsometry (SE) to optimize the measurement performance for different applications. The first example compares the sensitivity and results using SE at 0 and 90 degree AZ angles for a BEOL post-litho metal trench application. We observe up to a sixfold improvement in key metrics for critical parameters using 90 degree over 0 degree AZ angle spectra. The second example illustrates the benefits of a multiple-AZ angle approach to extract critical parameters for a two-dimensional logic High-K Metal Gate (HKMG) structure. Typically, this approach simultaneously fits two sets of SE spectra collected from the same location on the wafer at different AZ angles with the same physical model. This helps both validate and decorrelate critical parameters, enabling robust measurements. Results show that, for this application, the measurement performance metrics for each critical parameter are improved in almost every case.

Citation Download Citation

Matthew Sendelbach, Alok Vaid, Pedro Herrera, Ted Dziura, Michelle Zhang, and Arun Srivatsa "Use of multiple azimuthal angles to enable advanced scatterometry applications", Proc. SPIE 7638, Metrology, Inspection, and Process Control for Microlithography XXIV, 76381G (1 April 2010); https://doi.org/10.1117/12.846692

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