Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy

Oili M.E. Ylivaara, Pasi Hyttinen, Karsten Arts, Feng Gao, Wilhelmus M.M. Erwin Kessels, Riikka, L. Puurunen, Mikko Utriainen

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

    Abstract

    Atomic Layer Deposition (ALD) is a key technology in 3D microelectronics enabling conformal coatings into deep microscopic trenches and high aspect ratio cavities. However‚ conformality characterization in 3D trench walls is challenging and requires sample preparation. The MEMS-based all-silicon Lateral High Aspect Ratio (LHAR) test structure‚ developed at VTT‚ named PillarHall® [1-3]‚ provides a fast and accurate substrate and characterization concept for the thin film conformality analysis [4‚5]. The most important outcome from the PillarHall® characterization is the film saturation profile‚ which provides valuable data for reaction kinetics modelling and quantifying conformality. Since the LHAR enables utilization of planar metrology instruments‚ multiple approaches are compatible.

    In this study‚ we focus on characterization methods suitable to extract the saturation profile and show the advantage of simple optical microscopy image analysis. Studied material was prototypical ALD Al2O3 (40-50 nm thick layers) made in two separate research facilities. The study consisted of SEM/EDX planar view‚ micro-spot reflectometry and ellipsometry and optical microscopy image analyses. These experiments were carried out by two research labs and supported by leading edge optical metrology tool vendors‚ Semilab Ltd‚ JA Woollam and Filmetrics.

    We also introduce advanced LHAR 4th generation design‚ which enables characterization of the penetration depth profile with distinct advantages. Namely‚ new pillar design enables employment of optical line scanners up to 50 µm spot sizes. Furthermore‚ internal distance indicators support positioning the characterization tools more accurately. These features are illustrated in Supplementary Material Fig S1.

    The results show that the gray-scale optical microscopy image analysis with the thickness determination in opening area gives similar results as the reflectometry or ellipsometry line scans‚ within the accuracy limits. Optical thickness/λ of the film is a limitation for the image analysis‚ but designing the experiments properly‚ the grayscale optical micrograph can be a powerful‚ widely compatible and easy method for conformality analysis.
    Support from Semilab Ltd is gratefully acknowledged.

    References

    [1] F. Gao et al.‚ J. Vac. Sci. Technol. A Vacuum‚ Surfaces‚ Film.33‚ 010601 (2015).

    [2] R. Puurunen and F. Gao‚ 2016. doi: 10.1109/BALD.2016.7886526

    [3] M. Mattinen et al.‚ Langmuir‚ 32‚ 10559 (2016).

    [4] M. Ylilammi et al.‚ J. Appl. Phys.‚ 123‚ 205301 (2018).
    [5] V. Cremers et al.‚ Applied Physics Reviews‚ in press (2019).
    Original languageEnglish
    Title of host publicationALD 2019 Technical Program & Abstracts
    PublisherAmerican Vacuum Society AVS
    Publication statusPublished - 22 Jul 2019
    MoE publication typeNot Eligible
    Event19th International Conference on Atomic Layer Deposition, ALD 2019 - Bellevue, Washington, United States
    Duration: 21 Jul 201924 Jul 2019
    https://ald2019.avs.org/

    Conference

    Conference19th International Conference on Atomic Layer Deposition, ALD 2019
    Abbreviated titleALD2019
    CountryUnited States
    CityWashington
    Period21/07/1924/07/19
    Internet address

    Fingerprint

    high aspect ratio
    microscopy
    image analysis
    atomic layer epitaxy
    metrology
    ellipsometry
    profiles
    saturation
    research facilities
    gray scale
    leading edges
    microelectronics
    optical thickness
    scanners
    positioning
    microelectromechanical systems
    reaction kinetics
    penetration
    coatings
    vacuum

    Cite this

    Ylivaara, O. M. E., Hyttinen, P., Arts, K., Gao, F., Erwin Kessels, W. M. M., Puurunen, R. L., & Utriainen, M. (2019). Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy. In ALD 2019 Technical Program & Abstracts American Vacuum Society AVS.
    Ylivaara, Oili M.E. ; Hyttinen, Pasi ; Arts, Karsten ; Gao, Feng ; Erwin Kessels, Wilhelmus M.M. ; Puurunen, Riikka, L. ; Utriainen, Mikko. / Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy. ALD 2019 Technical Program & Abstracts. American Vacuum Society AVS, 2019.
    @inbook{94e39c70519849a38a2d63cd621960b9,
    title = "Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy",
    abstract = "Atomic Layer Deposition (ALD) is a key technology in 3D microelectronics enabling conformal coatings into deep microscopic trenches and high aspect ratio cavities. However‚ conformality characterization in 3D trench walls is challenging and requires sample preparation. The MEMS-based all-silicon Lateral High Aspect Ratio (LHAR) test structure‚ developed at VTT‚ named PillarHall{\circledR} [1-3]‚ provides a fast and accurate substrate and characterization concept for the thin film conformality analysis [4‚5]. The most important outcome from the PillarHall{\circledR} characterization is the film saturation profile‚ which provides valuable data for reaction kinetics modelling and quantifying conformality. Since the LHAR enables utilization of planar metrology instruments‚ multiple approaches are compatible.In this study‚ we focus on characterization methods suitable to extract the saturation profile and show the advantage of simple optical microscopy image analysis. Studied material was prototypical ALD Al2O3 (40-50 nm thick layers) made in two separate research facilities. The study consisted of SEM/EDX planar view‚ micro-spot reflectometry and ellipsometry and optical microscopy image analyses. These experiments were carried out by two research labs and supported by leading edge optical metrology tool vendors‚ Semilab Ltd‚ JA Woollam and Filmetrics.We also introduce advanced LHAR 4th generation design‚ which enables characterization of the penetration depth profile with distinct advantages. Namely‚ new pillar design enables employment of optical line scanners up to 50 µm spot sizes. Furthermore‚ internal distance indicators support positioning the characterization tools more accurately. These features are illustrated in Supplementary Material Fig S1.The results show that the gray-scale optical microscopy image analysis with the thickness determination in opening area gives similar results as the reflectometry or ellipsometry line scans‚ within the accuracy limits. Optical thickness/λ of the film is a limitation for the image analysis‚ but designing the experiments properly‚ the grayscale optical micrograph can be a powerful‚ widely compatible and easy method for conformality analysis.Support from Semilab Ltd is gratefully acknowledged.References[1] F. Gao et al.‚ J. Vac. Sci. Technol. A Vacuum‚ Surfaces‚ Film.33‚ 010601 (2015).[2] R. Puurunen and F. Gao‚ 2016. doi: 10.1109/BALD.2016.7886526[3] M. Mattinen et al.‚ Langmuir‚ 32‚ 10559 (2016).[4] M. Ylilammi et al.‚ J. Appl. Phys.‚ 123‚ 205301 (2018).[5] V. Cremers et al.‚ Applied Physics Reviews‚ in press (2019).",
    author = "Ylivaara, {Oili M.E.} and Pasi Hyttinen and Karsten Arts and Feng Gao and {Erwin Kessels}, {Wilhelmus M.M.} and Puurunen, {Riikka, L.} and Mikko Utriainen",
    year = "2019",
    month = "7",
    day = "22",
    language = "English",
    booktitle = "ALD 2019 Technical Program & Abstracts",
    publisher = "American Vacuum Society AVS",
    address = "United States",

    }

    Ylivaara, OME, Hyttinen, P, Arts, K, Gao, F, Erwin Kessels, WMM, Puurunen, RL & Utriainen, M 2019, Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy. in ALD 2019 Technical Program & Abstracts. American Vacuum Society AVS, 19th International Conference on Atomic Layer Deposition, ALD 2019, Washington, United States, 21/07/19.

    Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy. / Ylivaara, Oili M.E.; Hyttinen, Pasi; Arts, Karsten; Gao, Feng; Erwin Kessels, Wilhelmus M.M.; Puurunen, Riikka, L.; Utriainen, Mikko.

    ALD 2019 Technical Program & Abstracts. American Vacuum Society AVS, 2019.

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

    TY - CHAP

    T1 - Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy

    AU - Ylivaara, Oili M.E.

    AU - Hyttinen, Pasi

    AU - Arts, Karsten

    AU - Gao, Feng

    AU - Erwin Kessels, Wilhelmus M.M.

    AU - Puurunen, Riikka, L.

    AU - Utriainen, Mikko

    PY - 2019/7/22

    Y1 - 2019/7/22

    N2 - Atomic Layer Deposition (ALD) is a key technology in 3D microelectronics enabling conformal coatings into deep microscopic trenches and high aspect ratio cavities. However‚ conformality characterization in 3D trench walls is challenging and requires sample preparation. The MEMS-based all-silicon Lateral High Aspect Ratio (LHAR) test structure‚ developed at VTT‚ named PillarHall® [1-3]‚ provides a fast and accurate substrate and characterization concept for the thin film conformality analysis [4‚5]. The most important outcome from the PillarHall® characterization is the film saturation profile‚ which provides valuable data for reaction kinetics modelling and quantifying conformality. Since the LHAR enables utilization of planar metrology instruments‚ multiple approaches are compatible.In this study‚ we focus on characterization methods suitable to extract the saturation profile and show the advantage of simple optical microscopy image analysis. Studied material was prototypical ALD Al2O3 (40-50 nm thick layers) made in two separate research facilities. The study consisted of SEM/EDX planar view‚ micro-spot reflectometry and ellipsometry and optical microscopy image analyses. These experiments were carried out by two research labs and supported by leading edge optical metrology tool vendors‚ Semilab Ltd‚ JA Woollam and Filmetrics.We also introduce advanced LHAR 4th generation design‚ which enables characterization of the penetration depth profile with distinct advantages. Namely‚ new pillar design enables employment of optical line scanners up to 50 µm spot sizes. Furthermore‚ internal distance indicators support positioning the characterization tools more accurately. These features are illustrated in Supplementary Material Fig S1.The results show that the gray-scale optical microscopy image analysis with the thickness determination in opening area gives similar results as the reflectometry or ellipsometry line scans‚ within the accuracy limits. Optical thickness/λ of the film is a limitation for the image analysis‚ but designing the experiments properly‚ the grayscale optical micrograph can be a powerful‚ widely compatible and easy method for conformality analysis.Support from Semilab Ltd is gratefully acknowledged.References[1] F. Gao et al.‚ J. Vac. Sci. Technol. A Vacuum‚ Surfaces‚ Film.33‚ 010601 (2015).[2] R. Puurunen and F. Gao‚ 2016. doi: 10.1109/BALD.2016.7886526[3] M. Mattinen et al.‚ Langmuir‚ 32‚ 10559 (2016).[4] M. Ylilammi et al.‚ J. Appl. Phys.‚ 123‚ 205301 (2018).[5] V. Cremers et al.‚ Applied Physics Reviews‚ in press (2019).

    AB - Atomic Layer Deposition (ALD) is a key technology in 3D microelectronics enabling conformal coatings into deep microscopic trenches and high aspect ratio cavities. However‚ conformality characterization in 3D trench walls is challenging and requires sample preparation. The MEMS-based all-silicon Lateral High Aspect Ratio (LHAR) test structure‚ developed at VTT‚ named PillarHall® [1-3]‚ provides a fast and accurate substrate and characterization concept for the thin film conformality analysis [4‚5]. The most important outcome from the PillarHall® characterization is the film saturation profile‚ which provides valuable data for reaction kinetics modelling and quantifying conformality. Since the LHAR enables utilization of planar metrology instruments‚ multiple approaches are compatible.In this study‚ we focus on characterization methods suitable to extract the saturation profile and show the advantage of simple optical microscopy image analysis. Studied material was prototypical ALD Al2O3 (40-50 nm thick layers) made in two separate research facilities. The study consisted of SEM/EDX planar view‚ micro-spot reflectometry and ellipsometry and optical microscopy image analyses. These experiments were carried out by two research labs and supported by leading edge optical metrology tool vendors‚ Semilab Ltd‚ JA Woollam and Filmetrics.We also introduce advanced LHAR 4th generation design‚ which enables characterization of the penetration depth profile with distinct advantages. Namely‚ new pillar design enables employment of optical line scanners up to 50 µm spot sizes. Furthermore‚ internal distance indicators support positioning the characterization tools more accurately. These features are illustrated in Supplementary Material Fig S1.The results show that the gray-scale optical microscopy image analysis with the thickness determination in opening area gives similar results as the reflectometry or ellipsometry line scans‚ within the accuracy limits. Optical thickness/λ of the film is a limitation for the image analysis‚ but designing the experiments properly‚ the grayscale optical micrograph can be a powerful‚ widely compatible and easy method for conformality analysis.Support from Semilab Ltd is gratefully acknowledged.References[1] F. Gao et al.‚ J. Vac. Sci. Technol. A Vacuum‚ Surfaces‚ Film.33‚ 010601 (2015).[2] R. Puurunen and F. Gao‚ 2016. doi: 10.1109/BALD.2016.7886526[3] M. Mattinen et al.‚ Langmuir‚ 32‚ 10559 (2016).[4] M. Ylilammi et al.‚ J. Appl. Phys.‚ 123‚ 205301 (2018).[5] V. Cremers et al.‚ Applied Physics Reviews‚ in press (2019).

    M3 - Conference abstract in proceedings

    BT - ALD 2019 Technical Program & Abstracts

    PB - American Vacuum Society AVS

    ER -

    Ylivaara OME, Hyttinen P, Arts K, Gao F, Erwin Kessels WMM, Puurunen RL et al. Advanced Lateral High Aspect Ratio Test Structures for Conformality Characterization by Optical Microscopy. In ALD 2019 Technical Program & Abstracts. American Vacuum Society AVS. 2019