Hybrid metrology co-optimization of critical dimension scanning electron microscope and optical critical dimension

Vaid, Alok; Osorio, Carmen; Tsai, Jamie; Bozdog, Cornel; Sendelbach, Matthew; Grubner, Eyal; Koret, Roy; Wolfling, Shay

doi:10.1117/1.jmm.13.4.041413

Cited by 4 publications

(7 citation statements)

References 10 publications

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“…To improve the parametric uncertainties of model-based measurements, multi-tool methods [5,6] have been proposed and implemented that use Bayesian methods to incorporate these reference measurement values (AFM, TEM, SEM, etc) as well as their measurement uncertainties into the model-based techniques. This multi-tool approach has been named 'hybrid metrology' in the literature of semiconductor manufacturing [7][8][9][10][11][12]. Most publications in this nascent subfield of nanoscale dimensional metrology have focused on incorporating this prior information from reference tools into the modeling, but only a few have considered the combination of raw data from multiple tools [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…, which is a N by ( + K 1) matrix with 1 as a unit vector of length = N and with D(0) a N by K matrix. From (8), (10) and the Gauss-Markov-Aitken theorem (see pp 24-7 and pp 96-8 in [16]), the generalized least squares (GLS) gives the best linear unbiased estimator (BLUE) of β′(0)…”

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confidence: 99%

“…We now investigate the uncertainties for the estimators of a subset of parameters in the model as given in (10). For the given set of parameters β′(0) in ( 10), sometimes we would like to estimate only a subset of the parameters as individual methodologies will yield smaller uncertainties for certain quantities than for others.…”

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confidence: 99%

“…We will compare the uncertainties of the parameter estimators based on the models for the whole set and for the subset parameters, respectively. Here for simplicity, we suppress the symbol for the initial values and consider a generic form of the regression model in (10),…”

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confidence: 99%

“…Considering the model in (10), in practice we need to check whether the parameter b or intercept in the model is statistically significant from zero. Under the assumption that the random error ε i is Gaussian distributed, a t-test can be performed by…”

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confidence: 99%

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Combining model-based measurement results of critical dimensions from multiple tools

Zhang

Barnes

Zhou

et al. 2017

Meas. Sci. Technol.

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Model-based measurement techniques use experimental data and simulations of the underlying physics to extract quantitative estimates of the measurands of a specimen based upon a parametric model of that specimen. The uncertainties of these estimates are based upon not only the uncertainties in the experimental data, but also the sensitivity of that data to the model parameters, and parametric correlations among those parameters. The combination of two or more model-based techniques as well as the Bayesian approach are shown to be optimal for obtaining the lowest possible uncertainties. As an example, using this form of hybrid metrology, state-of-the-art sub-14 nm wide lines from semiconductor manufacturing are measured using a combined regression from critical-dimension small-angle x-ray scattering and scanning electron microscopy that leads to lower uncertainties.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Combining model-based measurement results of critical dimensions from multiple tools

Zhang

Barnes

Zhou

et al. 2017

Meas. Sci. Technol.

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Evaluation of carbon nanotube probes in critical dimension atomic force microscopes

Choi

Park

Ahn

et al. 2016

J. Micro/Nanolith. MEMS MOEMS

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The decreasing size of semiconductor features and the increasing structural complexity of advanced devices have placed continuously greater demands on manufacturing metrology, arising both from the measurement challenges of smaller feature sizes and the growing requirement to characterize structures in more than just a single critical dimension. For scanning electron microscopy, this has resulted in increasing sophistication of imaging models. For critical dimension atomic force microscopes (CD-AFMs), this has resulted in the need for smaller and more complex tips. Carbon nanotube (CNT) tips have thus been the focus of much interest and effort by a number of researchers. However, there have been significant issues surrounding both the manufacture and use of CNT tips. Specifically, the growth or attachment of CNTs to AFM cantilevers has been a challenge to the fabrication of CNT tips, and the flexibility and resultant bending artifacts have presented challenges to using CNT tips. The Korea Research Institute for Standards and Science (KRISS) has invested considerable effort in the controlled fabrication of CNT tips and is collaborating with the National Institute of Standards and Technology on the application of CNT tips for CD-AFM. Progress by KRISS on the precise control of CNT orientation, length, and end modification, using manipulation and focused ion beam processes, has allowed us to implement ball-capped CNT tips and bent CNT tips for CD-AFM. Using two different generations of CD-AFM instruments, we have evaluated these tip types by imaging a line/space grating and a programmed line edge roughness specimen. We concluded that these CNTs are capable of scanning the profiles of these structures, including re-entrant sidewalls, but there remain important challenges to address. These challenges include tighter control of tip geometry and careful optimization of scan parameters and algorithms for using CNT tips.

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Hybrid metrology implementation: server approach

et al. 2015

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Hybrid metrology co-optimization of critical dimension scanning electron microscope and optical critical dimension

Cited by 4 publications

References 10 publications

Combining model-based measurement results of critical dimensions from multiple tools

Combining model-based measurement results of critical dimensions from multiple tools

Evaluation of carbon nanotube probes in critical dimension atomic force microscopes

Hybrid metrology implementation: server approach

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