Modeling the effect of line profile variation on optical critical dimension metrology

Germer, Thomas A.

doi:10.1117/12.704246

Cited by 13 publications

(7 citation statements)

References 23 publications

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“…Work by Germer has investigated line edge and line width roughness in the long period regime and found that the results can be approximated by a incoherent average of line widths. 22,23 More recent results by Bergner, et al, investigated roughness in the short period regime and found that the results could be modeled with an effective medium layer, provided the layer was treated as a birefringent effective medium. 24…”

Section: Line Width/line Edge Roughnessmentioning

confidence: 96%

Developing an uncertainty analysis for optical scatterometry

Germer

Patrick

Silver

et al. 2009

Metrology, Inspection, and Process Control for Microlithography XXIII

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This article describes how an uncertainty analysis may be performed on a scatterometry measurement. A method is outlined for propagating uncertainties through a least-squares regression. The method includes the propagation of the measurement noise as well as estimates of systematic effects in the measurement. Since there may be correlations between the various parameters determined by the measurement, a method is described for visualizing the uncertainty in the extracted profile. The analysis is performed for a 120 nm pitch grating, consisting of photoresist lines 120 nm high, 45 nm critical dimension, and 88 • side wall angle, measured with a spectroscopic rotating compensator ellipsometer. The results suggest that, while scatterometry is very precise, there are a number of sources of systematic errors that limit its absolute accuracy. Addressing those systematic errors may significantly improve scatterometry measurements in the future.

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Section: Line Width/line Edge Roughnessmentioning

confidence: 96%

Developing an uncertainty analysis for optical scatterometry

Germer

Patrick

Silver

et al. 2009

Metrology, Inspection, and Process Control for Microlithography XXIII

Self Cite

View full text Add to dashboard Cite

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“…Quintanilha et al [26] presented an experimental study which yielded a negligible influence of LER on scatterometry measurements for the considered samples and tool configurations. Germer [27] investigated the effect of linewidth and line position variation from trench to trench, i.e. in the direction orthogonal to the lines.…”

Section: Introductionmentioning

confidence: 99%

Influence of line edge roughness (LER) on angular resolved and on spectroscopic scatterometry

2008

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Scatterometry or optical CD metrology (OCD) has become one of the most common techniques in quantitative wafer metrology within the recent years. Different tool configurations are either available in commercial inspection tools or subject of recent and present research activities. Among these are normal incidence reflectometry, 2-θ scatterometry, spectroscopic ellipsometry and angle resolved Fourier scatterometry. The two latter techniques appear to be promising for future use in semiconductor fabs. Spectroscopic ellipsometry is well established, and Fourier scatterometry has become of increasing interest within the recent time. Line edge roughness, i.e. an edge position variation of printed lines in lithography, has been of less importance up to now, as its amplitude could largely be neglected with respect to the feature dimensions. This will, however, not be the case for future nodes, as on the one hand CDs are getting smaller and smaller, and on the other hand, even the absolute amplitude is expected to increase due to the higher complexity of lithography and etch processes. In this paper a comparison of scatterometric reconstructions in both spectroscopic and angle resolved techniques considering LER afflicted samples is presented. The validity and benefit of a simple effective medium model is investigated.

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“…Quintanilha et al [18] presented an experimental study which yielded a neghgible influence of LER on scatterometry measurements for the considered samples and tool configurations. Germer [19] investigated the effect of linewidth and line position variation from trench to trench, i.e. in the direction orthogonal to the hues.…”

Section: Introductionmentioning

confidence: 99%

Simulations of Scatterometry Down to 22 nm Structure Sizes and Beyond with Special Emphasis on LER

Paz¹,

Frenner²,

Schuster³

et al. 2009

AIP Conference Proceedings

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Abstract. In recent years, scatterometry has become one of the most commonly used methods for CD metrology. With decreasmg structure size for future technology nodes, the search for optimized scatterometry measurement configurations gets more important to exploit maximum sensitivity. As widespread industrial scatterometry tools mainly still use a pre-set measurement configuration, there are still free parameters to improve sensitivity. Our current work uses a simulation based approach to predict and optimize sensitivity of future technology nodes. Since line edge roughness is getting important for such small structures, these imperfections of the periodic continuation cannot be neglected. Using fourier methods like e.g. rigorous coupled wave approach (RCWA) for diffraction calculus, nonperiodic features are hard to reach. We show that in this field certain types of fieldstitching methods show nice numerical behaviour and lead to useful results.

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Modeling the effect of line profile variation on optical critical dimension metrology

Cited by 13 publications

References 23 publications

Developing an uncertainty analysis for optical scatterometry

Developing an uncertainty analysis for optical scatterometry

Influence of line edge roughness (LER) on angular resolved and on spectroscopic scatterometry

Simulations of Scatterometry Down to 22 nm Structure Sizes and Beyond with Special Emphasis on LER

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