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12 May 2005 Feature profile control and the influence of scan artifacts
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Competitive high volume semiconductor manufacturing yields require that critical feature profiles be continually monitored for uniformity and production control. Historically this has involved long and tedious analyses of Scanning Electron Microscope (SEM) photos that resulted in an average feature profile or a qualitative comparison of a matrix of black and white images. Many factors influence profiles including wafer flatness, focus and film thicknesses. Characterizing profile uniformity as a function of these parameters not only stabilizes high product yields but also significantly reduces the time spent in problem aversion and solution discovery. Scatterometry uniquely provides the combination of feature metrics and spatial coverage needed to monitor production profiles. The vast amount of data gathered by these systems is not well handled by classic statistical methods. A more practical approach taken by the authors is to apply spatial models to the profile data to determine the relative stability and contributions of film, substrate and the exposure tool to process perturbations. Recent work performed by Agere and TEA Systems is shown to be capable of quantitatively modeling the relative contributions of lens slit, reticle-scan and lens degradation to feature size and side-wall angle (SWA). This work describes the models used and the slit-and-scan contributions that are unique for each exposure tool. Finally it is shown that the direction and linearity of the reticle scan can be a contributing factor to the feature profile error budget with direct influence production image stability.
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Richard Dare, Paul R. Rowland, and Terrence E. Zavecz "Feature profile control and the influence of scan artifacts", Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005);

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