Mr. Elad Sommer Profile

Elad Sommer

at Applied Materials

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Publications (4)

Proceedings Article | 20 March 2020 Presentation + Paper

Contact etch process control application for advanced NAND memory structures

R. Kris, G. Klebanov, E. Frishman, S. Duvdevani Bar, J. Geva, D. Rathore, D. Rogers, I. Friedler, V. Mirovoy, N. Teomim, J. Chess, B. Watson

Proceedings Volume 11325, 113251F (2020) https://doi.org/10.1117/12.2559399

KEYWORDS: Etching, Scanning electron microscopy, Process control, Critical dimension metrology, Metrology, Image processing, Signal processing, Shape analysis, Image classification, Image analysis, Machine learning

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CD measurements of advanced 3D-NAND Staircase process require development of new approaches in CD metrology [1]. The current CD SEM Contact Analysis used for 3D-NAND assumes that process control could be provided through a set of geometric parameters defining the contact shape (i.e. parameters of contact shape elliptic fit such as equivalent contact top diameter (Top CD), equivalent contact bottom diameter (Bottom CD), ellipticity, minor, major axis). The limitation of this approach for process control of complex structures was considered, and a new approach based on Grey Level Analysis of contact features in SEM images was proposed. However, this analysis is not enough for controlling the complicated 3D-NAND Staircase formation process steps, as contact holes with same geometric parameters but different depths cannot be separated by traditional CD SEM metrology measurement procedure (Figures 1 and 2). Thus, traditional CD SEM approach needs revisiting in order to work in situations where process control requires analysis of sophisticated Grey Level uniformity distribution. We propose a novel approach combining traditional metrology with machine learning methods. The essence of this new approach is to combine Grey Level attributes and traditional CD measured geometric parameters of the feature, obtained by traditional CD metrology flow, in a classification scheme (Figures 2 and 3). The proposed approach was qualified at Micron site demonstrating ~98% purity classification results.
The proposed approach is generic and can be extended to a large variety of process control applications. Enhancing regular metrology flow with the capability to classify Etch process quality eliminates the need for the expensive and destructive cross-sectional SEM analysis. Furthermore, this method has a clear advantage during the early R&D phase of process development as it increases the usefulness of the in-line metrology tool while the process is still immature and unstable.

Proceedings Article | 8 April 2019 Paper

Macro CDSEM 2D metrology supporting advanced DRAM patterning

R. Kris, L. Gershtein, B. Mathew, I. Schwarzband, G. Klebanov, E. Sommer, E. Noifeld, S. Levy, R. Alkoken, O. Novak, H. Miroku, D. Rathore , S. Duvdevani-Bar, T. Bar-On, I. Horikawa, S. Pastur

Proceedings Volume 10959, 109592S (2019) https://doi.org/10.1117/12.2515233

KEYWORDS: Metrology, Critical dimension metrology, Process control, Scanning electron microscopy, Optical lithography, Algorithm development, Detection and tracking algorithms, Mathematical modeling, Image enhancement, Computer aided design

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Proceedings Article | 4 April 2008 Paper

Physical matching of CD-SEM: noise analysis and verification in FAB environment

Galit Zuckerman, Alessandra Navarra, Roman Kris, Jan Kaiser, Amir Len, Elad Sommer, Frank Voss, Dirk Schöne, Goeran Fleischer, Stefano Ventola, Shalev Dror, Uwe Kramer, Igal Ben-Dayan

Proceedings Volume 6922, 69221R (2008) https://doi.org/10.1117/12.776865

KEYWORDS: Signal to noise ratio, Scanning electron microscopy, Calibration, Critical dimension metrology, Image acquisition, Interference (communication), Sensors, Visualization, Metrology, Statistical analysis

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CD-SEMs fleet matching is a widely discussed subject and various approaches and procedures to determine it were described in the literature [1,2,4-6]. The different approaches for matching are all based on statistical treatment of CD measurements that are performed on dedicated test structures. The test structures are a limited finite set of features, thus the matching results should be treated as valid only for the specific defined set of test features. The credibility of the matching should be in question for different layers and specifically production layers. Since matching is crucial for reliable process monitoring by a fleet of CD-SEMs, the current matching approaches must be extended so that the matching will be only tool dependent and reproducible on all layers regardless their specific material or topographic characteristics. In our previous work [1] the new approach named "Physical Matching" was introduced and a new matching procedure based on the direct estimation of tool physical parameters was described. This approach extends the conventional matching methods to enable significant improvement of the matching between CD-SEM tools in production environment. In this work we present results of applying the physical matching method in FAB environment by using the physical parameters of the brightness and SNR, extend it to noise frequency domain characteristics monitoring, and enhanced collection uniformity. Improving the collection uniformity is also demonstrated and proved to be a significant factor. The advantage of the physical matching with noise spectra analysis approach for a case study is demonstrated. This method will enable detection of specific reasons for mismatching between the tools, based on analysis of specific frequencies that are resulted from known mechanical/electrical noise. The proposed procedure allows tool problems fixing before CD measurements are affected. In order to get a reliable visualization of the difference between two systems, new automatic and manual tool finger print methods were developed. The application of the proposed approach to vendor to vendor matching problem is considered.

Proceedings Article | 12 April 2007 Paper

Physical matching versus CD matching for CD SEM

Elad Sommer, Aviram Tam, Galit Zuckerman, Roman Kris, Naftali Shcolnik, Shalev Dror, Zion Hadad

Proceedings Volume 6518, 65180O (2007) https://doi.org/10.1117/12.711768

KEYWORDS: Signal to noise ratio, Scanning electron microscopy, Sensors, Interference (communication), Critical dimension metrology, Target detection, Image acquisition, Etching, Calibration, Statistical analysis

Read Abstract +

CD-SEMs fleet matching is a widely discussed subject and various approaches and procedures to determine it were described in the literature. The different approaches for matching are all based on statistical treatment of regular CD measurements that are performed on dedicated test structures. The test structures are a limited finite set of features, thus the matching results should be treated as valid only for the specific defined set of test features. The credibility of the matching should be in question for different layers and specifically production layers. Since matching is crucial for reliable process monitoring by a fleet of CD-SEMs, the current matching approaches (such as TMU) must be extended so that the matching will be only tool dependent and reproducible on all layers regardless their specific material or topographic characteristics. In this work the term "Physical Matching" is introduced and a new matching procedure based on physical parameters is described. This approach extends the conventional matching methods to enable significant improvement of the matching between CD-SEM tools in production environment. To study and demonstrate the physical matching, we focus on the limited parameters set - the image brightness and Signal/Noise ratio(SNR). We test the sensitivity of CD measurements to changes in these parameters both on different test layers - Etch and Litho. We show that sensitivity of CD based measurements is low and reasonable change of the image brightness or SNR has small effect. The advantage of the physical matching approach for case study is demonstrated. The improved matching procedures are based on new targets that are used to measure the above image parameters directly. This way it is possible to characterize correctly the physical state of the measurement tool and guarantee the same image characteristics which in turn guarantee improved matching on all layers. In the framework of the proposed matching approach a proper determination of the minimal set of physical parameters that is needed to guarantee CD-SEM tools stability and matching should be included.

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