A study of swing-curve physics in diffraction-based overlay

Bhattacharyya, Kaustuve; Boef, Arie den; Storms, Greet; Heijst, Joost van; Noot, Marc; An, Kevin R.; Park, Noh-Kyoung; Jeon, Se-Ra; Oh, Nang-Lyeom; McNamara, Elliott; Mast, Frank van de; Oh, SeungHwa; Lee, Seung Yoon; Hwang, Chan-Soo; Lee, Kuntack

doi:10.1117/12.2222040

Cited by 15 publications

(15 citation statements)

References 2 publications

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“…Interestingly, y 1 , which contains projections onto the first and most significant SV component, shows a linear behavior as function of OV (shown in blue in Figure f). This observation is in line with the simple analytic expectation for DBO based on the asymmetry of the main first diffraction orders . The fact that complex targets with more complex Fourier patterns carry more information is evident from the fact that also higher order eigenbasis coordinates show variations with overlay (see y j , with j = 2, 3, and 4 in Figure f).…”

Section: Simulation and Uncertainty Estimationsupporting

confidence: 85%

“…To ensure working devices, the OV error has to be smaller than a fraction of the minimum feature size. Continuously shrinking node sizes and increasing product stack complexity have reduced OV error tolerances down to only a few nanometers, which is why OV metrology could become a limiting factor for further progress of the industry. , A widely used OV metrology technique is diffraction-based overlay scatterometry (DBO), − in which diffraction patterns backscattered from two gratings that are stacked on top of each other are analyzed to infer the OV error. The idea is that for perfect alignment the OV target possesses a symmetric scattering signature, similar to a single grating.…”

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confidence: 99%

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Uncertainty Estimation and Design Optimization of 2D Diffraction-Based Overlay Metrology Targets

et al. 2020

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Scatterometry is an optical metrology technique in which light scattered from a specifically designed grating stack (overlay target) is measured in the far-field. Using 1D periodic overlay target designs, the technique has been shown to have nanometer-scale sensitivity to spatial misalignments of subsequent patterned layers, which are also known as overlay errors. However, while scatterometry is highly sensitive to overlay errors, multiple sources of systematic errors hinder its absolute accuracy. Here, we investigate how an extended version of scatterometry called Fourier scatterometry, in combination with more complex overlay target designs, can help addressing those challenges. To this end, we developed a statistical method that can determine the influence of 2D overlay targets on the overlay measurement uncertainty. We study periodic and deterministic aperiodic designs as well as designs that emerged from simulated annealing optimizations. Our results suggest that current overlay target designs could be augmented by more complex 2D designs to fulfill specific purposes, such as fabrication robustness and high sensitivity over a large overlay range.

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Section: Simulation and Uncertainty Estimationsupporting

confidence: 85%

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confidence: 99%

Uncertainty Estimation and Design Optimization of 2D Diffraction-Based Overlay Metrology Targets

et al. 2020

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“…With multiple wavelengths and polarizations to choose from, finding the optimum combination of measurement settings to guard against process induced overlay errors, such as those from etch and CMP, we developed the HMQ recipe algorithm [2].…”

Section: Overlay Recipe Optimizationmentioning

confidence: 99%

“…Second we show how to characterize the behavior of multiple wavelengths and polarizations with respect to target design. The purpose of which is to find the optimum target setup combination to guard against processing effects, such as those from etching and CMP [2]. Next a method is developed to not only flag processing effects that can physically make the bottom target asymmetric, but also how to cope with these effects to keep the overlay measurement quality intact.…”

Section: Introductionmentioning

confidence: 99%

An integrated approach to holistic metrology qualification for multi-patterning process layers: AM: Advanced metrology

Schmitt-Weaver

Willems

Laan

et al. 2016

2016 27th Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC)

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Multi-patterning lithography at the 10-nm and 7-nm nodes is driving an exponential increase of metrology complexity in the overlay and alignment tree. Coupled with the highly involved process stacks required to reach these nodes, the setup and verification of the metrology recipes have reached new levels of importance. With an all-encompassing holistic mindset the authors present four node-enabling technologies using production data from a leading logic customer. Firstly an optimized layout is defined using a metric that ranks the importance of available wafer coordinate positions based on the model to be use for lithographic apparatus actuation. Next to minimize influence of process induced target asymmetry on overlay, the authors define how to find the optimum wavelength and polarization settings for overlay metrology. Once the process has reached a high volume-manufacturing (HVM) environment, we propose a method of monitoring using a single point key performance indicator (KPI). In the last section all learning is applied with integrated metrology (IM) within HVM to realize improved correctable error in measured overlay.

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“…6 The use of multiple wavelengths in μDBO has significantly improved process-robustness and allowed accuracy levels in the subnanometer range even in the presence of process variations. [7][8][9] As a result, metrology using μDBO-marks has become the standard for many overlay-critical layers in logic and memory devices.…”

Section: Introductionmentioning

confidence: 99%

Diffraction-based overlay metrology from visible to infrared wavelengths using a single sensor

Schaijk

Messinis

Pandey

et al. 2022

J. Micro/Nanopattern. Mats. Metro.

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Background: Integrated circuits are fabricated layer by layer. It is crucial to their performance that these layers are well aligned to each other, and any undesired translation of a layer is called overlay. Thus far, overlay measurements have been limited to visible wavelengths, but the use of materials that are opaque to visible wavelengths necessitates measurements using infrared light.Aim: We set out to demonstrate that an overlay sensor based on digital holographic microscopy can perform such overlay measurement at infrared wavelengths, while maintaining functionality at visible wavelengths.Approach: This was done by constructing a breadboard setup that is capable of measuring overlay at wavelengths ranging from 400 to 1100 nm.Results: Using the setup, we demonstrated good linearity between an applied amount of overlay and the measured amount. In addition, we demonstrated that the setup is only sensitive to structures at the top of the wafer. Measurements are therefore unaffected by the fact that Si is transparent at 1100 nm.Conclusions: These results demonstrate the viability of an overlay sensor that is sensitive to visible and infrared light, allowing more freedom in choice of materials for integrated circuits.

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A study of swing-curve physics in diffraction-based overlay

Cited by 15 publications

References 2 publications

Uncertainty Estimation and Design Optimization of 2D Diffraction-Based Overlay Metrology Targets

Uncertainty Estimation and Design Optimization of 2D Diffraction-Based Overlay Metrology Targets

An integrated approach to holistic metrology qualification for multi-patterning process layers: AM: Advanced metrology

Diffraction-based overlay metrology from visible to infrared wavelengths using a single sensor

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