CD bias reduction in CD-SEM of very small line patterns: sidewall shape measurement using model-based library matching method

Shishido, Chie; Tanaka, Maki; Osaki, Mayuka

doi:10.1117/12.846402

Cited by 9 publications

(7 citation statements)

References 9 publications

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“…For CD measurement, there are methods to measure both the sidewall angle and CD bias and optimize the threshold for edge detection using CDbeam scan direction beam scan direction Ode 180de Signal profile Asymmetric contrast diffusion SEM [8,9]. In the case of positional measurement, optimizing the threshold condition remains to be effective for WIS reduction, although its optimization flow has to be modified.…”

Section: In-line Correction Methods For Mark Asymmetrymentioning

confidence: 98%

“…For IBO and DBO, a systematic way of correcting the inaccuracy arising from measurement patterns was suggested [6,7]. For CD-SEM measurement, on the contrary, although a way of correcting CD bias was proposed [8], it has not been argued yet how to correct the inaccuracy arising from pattern asymmetry using CD-SEM itself. In this study we propose how to quantify and correct the measurement inaccuracy affected by target pattern asymmetry.…”

Section: Introductionmentioning

confidence: 98%

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Improvement of CD-SEM mark position measurement accuracy

Kasa

Fukuhara

2014

Metrology, Inspection, and Process Control for Microlithography XXVIII

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CD-SEM is now attracting attention as a tool that can accurately measure positional error of device patterns. However, the measurement accuracy can get worse due to pattern asymmetry as in the case of image based overlay (IBO) and diffraction based overlay (DBO). For IBO and DBO, a way of correcting the inaccuracy arising from measurement patterns was suggested. For CD-SEM, although a way of correcting CD bias was proposed, it has not been argued how to correct the inaccuracy arising from pattern asymmetry using CD-SEM. In this study we will propose how to quantify and correct the measurement inaccuracy affected by pattern asymmetry.

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Section: In-line Correction Methods For Mark Asymmetrymentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Improvement of CD-SEM mark position measurement accuracy

Kasa

Fukuhara

2014

Metrology, Inspection, and Process Control for Microlithography XXVIII

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“…For example, we previously applied the MBL method to a pattern having space widths of approximately 100 nm and were able to achieve accurate measurements. 8 However, the above assumption does not appear to hold under real CD-SEM conditions as the width of the spaces becomes narrow. We attempted to calculate the electric field distribution around the space pattern taking the CD-SEM optics into consideration.…”

Section: Conventional Extraction Modelmentioning

confidence: 94%

“…The effectiveness of the modified MBL method was verified by applying it to actual silicon patterns with linewidths in the range 10 to 30 nm. 8 In the present paper, we consider narrow space patterns. In order to accurately measure such patterns, we improve the secondary-electron extraction efficiency model.…”

Section: Introductionmentioning

confidence: 99%

Improved secondary electron extraction efficiency model for accurate measurement of narrow-space patterns using model-based library matching

2011

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In order to accurately measure narrow space patterns, we propose an improved secondary-electron extraction efficiency model for the model-based library (MBL) method. In the conventional model, the same extraction efficiency is applied to all electrons, regardless of where they are emitted from. This is a simplified model assuming a uniform extraction electric field strength. In the improved model, the extraction efficiency is calculated as a function of the pattern shape and the emission position of the electrons. The function is based on simulation results for the electric field strength of critical-dimension scanning electron microscopy (CD-SEM) optics. We verify the effectiveness of the improved extraction model by applying it to actual patterns with space widths in the range 20 to 30 nm. The measurement bias of the sidewall angle (SWA) is evaluated through comparison with cross-sectional SEM measurements. We show that the average SWA bias is improved from 0.8° for the conventional model to 0.04° for the improved model.

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“…With the help of MC modelling, not only the linewidth but also the 3D morphological shape of the structure can be derived [26][27][28][29][30][31][32][33][34][35][36][37][38]. Then, the model-based library (MBL) algorithm [28,34,37,[39][40][41][42] can be extended to 3D metrology of the CD by including many more geometrical structure parameters, such as top CD, bottom CD, height and sidewall angles. It has been experimentally verified that this characterization method is effective even down to patterned lines with a size of 10 nm [37].…”

Section: Introductionmentioning

confidence: 99%

Critical-dimension scanning electron microscope characterization of smoothly varying wave structures with a Monte Carlo simulation

Khan¹,

Yang²,

Xiao³

et al. 2021

J. Phys. D: Appl. Phys.

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Scanning electron microscopy (SEM) characterization of a smoothly varying nanograting structure (a Pt-coated Cr grid on a Si substrate) with a sinusoidal waveform has been carried out by a Monte Carlo (MC) simulation technique. Previous studies with critical-dimension (CD) SEM (CD-SEM) have mostly concerned line structures with sharp edges so that there is an obvious edge bloom in the linescan profile of secondary electrons. In contrast, the present grating structures prepared by a laser-focused atomic deposition technique have a smoothly varying waveform in the cross-sectional profile, which pose greater difficulty for quantitative structural characterization by SEM. The grating structure, with a fixed pitch of λ/2 as the period of the standing-wave laser light field, where λ is the wavelength of the corresponding laser light, can be used as an ideal nanoscale metrological length tool; therefore, it is important to characterize its structural features over a large deposited area by SEM imaging for quality control, with the aim of mass reproduction. The present work extends the CD characterization of MC simulation methods to more complex structures. Taking into account different experimental factors, i.e. primary electron beam parameters, geometrical parameters and material properties, the unknown geometrical parameters (i.e. base height, peak height, linewidth shrinkage and peak tilt angle) of the grating lines have been successfully extracted from the experimental linescan profiles of SEM images.

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CD bias reduction in CD-SEM of very small line patterns: sidewall shape measurement using model-based library matching method

Cited by 9 publications

References 9 publications

Improvement of CD-SEM mark position measurement accuracy

Improvement of CD-SEM mark position measurement accuracy

Improved secondary electron extraction efficiency model for accurate measurement of narrow-space patterns using model-based library matching

Critical-dimension scanning electron microscope characterization of smoothly varying wave structures with a Monte Carlo simulation

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