On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition

Xuwen Liu (Corresponding author), Eero Haimi, Simo-Pekka Hannula, Riikka L. Puurunen, Oili Ylivaara

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

    Abstract

    Atomic layer deposition (ALD) is one of the most promising technologies in producing highly conformal coatings with a strict tolerance in thickness. In the study, ALD Al2O3 coatings of thickness varying from 10 to 600 nm are produced on single-side polished silicon (SSP-Si) wafer at the deposition temperature of 300 °C. This study aims in developing a convenient, efficient and inexpensive method of obtaining reliable coating properties via instrumented nanoindentation to meet the demand of silicon-based microelectronics industry. Hardness and elastic modulus are the most common mechanical properties that are directly derived from nanoindentation data. From Oliver and Pharr's analysis, the unloading data can be well described by a power-law relation: P = a(h-hf)m, where P is the indent load, hf is the residual depth after complete unloading and a and m are material constants. The power-law exponent, m, is found only slightly material dependent for a variety of materials, its value falling between 1.2 and 1.6. However, large m values up to 4 are obtained in certain materials in a consistent basis so that instrument/environment origin can be ruled out. According to the elastic assumption and the extended Hertzian treatment on unloading, m>2 has no physical meaning. The large m is often ascribed to inelastic or reverse plasticity in unloading. Silicon is one of the materials that can demonstrate reverse plasticity through phase transformation during unloading. A careful investigation of the unloading phenomena of the silicon wafer established that reverse plasticity occurred when contact depth was larger than about 8 nm, indicated by large m values at about 3.5. Meanwhile, the characteristics of the loading curve indicate that this depth marked the moment at which transition from elastic to elastic-plastic deformation on loading occurred. When the ALD Al2O3 coatings on the Si-wafer were indented, m dropped and varied narrowly around 1.5 over a large range of indent depths. A conclusion was then reached that the plot of m vs. hC (indent depth) could be used to monitor whether the Si substrate was in elastic or elastic-plastic state when the whole system was under external loading. This provided a guideline for picking up correct values of coating property under the conditions that the substrate only provided elastic support of a small fraction of the indenting load. As a result, it was found that the 10% rule commonly used in extracting coating property from a layered structure could be relaxed and the subtle property differences between the Al2O3 coatings and the Si substrate were revealed with good confidence.
    Original languageEnglish
    Title of host publicationTechnical Program & Abstracts
    PublisherAmerican Vacuum Society AVS
    Publication statusPublished - 2012
    Event12th International Conference on Atomic Layer Deposition, ALD 2012 - Dresden, Germany
    Duration: 17 Jun 201220 Jun 2012
    Conference number: 12

    Conference

    Conference12th International Conference on Atomic Layer Deposition, ALD 2012
    Abbreviated titleALD 2012
    CountryGermany
    CityDresden
    Period17/06/1220/06/12

    Fingerprint

    unloading
    atomic layer epitaxy
    nanoindentation
    wafers
    coatings
    thin films
    plastic properties
    silicon
    elastic deformation
    falling
    microelectronics
    plastic deformation
    phase transformations
    coating
    confidence
    modulus of elasticity
    hardness
    plastics
    plots
    industries

    Keywords

    • atomic layer deposition
    • ALD
    • aluminum oxide
    • nanoindentation

    Cite this

    Liu, X., Haimi, E., Hannula, S-P., Puurunen, R. L., & Ylivaara, O. (2012). On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition. In Technical Program & Abstracts American Vacuum Society AVS.
    Liu, Xuwen ; Haimi, Eero ; Hannula, Simo-Pekka ; Puurunen, Riikka L. ; Ylivaara, Oili. / On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition. Technical Program & Abstracts. American Vacuum Society AVS, 2012.
    @inbook{ca573cbb24c043a994a7ee5d0a535c86,
    title = "On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition",
    abstract = "Atomic layer deposition (ALD) is one of the most promising technologies in producing highly conformal coatings with a strict tolerance in thickness. In the study, ALD Al2O3 coatings of thickness varying from 10 to 600 nm are produced on single-side polished silicon (SSP-Si) wafer at the deposition temperature of 300 °C. This study aims in developing a convenient, efficient and inexpensive method of obtaining reliable coating properties via instrumented nanoindentation to meet the demand of silicon-based microelectronics industry. Hardness and elastic modulus are the most common mechanical properties that are directly derived from nanoindentation data. From Oliver and Pharr's analysis, the unloading data can be well described by a power-law relation: P = a(h-hf)m, where P is the indent load, hf is the residual depth after complete unloading and a and m are material constants. The power-law exponent, m, is found only slightly material dependent for a variety of materials, its value falling between 1.2 and 1.6. However, large m values up to 4 are obtained in certain materials in a consistent basis so that instrument/environment origin can be ruled out. According to the elastic assumption and the extended Hertzian treatment on unloading, m>2 has no physical meaning. The large m is often ascribed to inelastic or reverse plasticity in unloading. Silicon is one of the materials that can demonstrate reverse plasticity through phase transformation during unloading. A careful investigation of the unloading phenomena of the silicon wafer established that reverse plasticity occurred when contact depth was larger than about 8 nm, indicated by large m values at about 3.5. Meanwhile, the characteristics of the loading curve indicate that this depth marked the moment at which transition from elastic to elastic-plastic deformation on loading occurred. When the ALD Al2O3 coatings on the Si-wafer were indented, m dropped and varied narrowly around 1.5 over a large range of indent depths. A conclusion was then reached that the plot of m vs. hC (indent depth) could be used to monitor whether the Si substrate was in elastic or elastic-plastic state when the whole system was under external loading. This provided a guideline for picking up correct values of coating property under the conditions that the substrate only provided elastic support of a small fraction of the indenting load. As a result, it was found that the 10{\%} rule commonly used in extracting coating property from a layered structure could be relaxed and the subtle property differences between the Al2O3 coatings and the Si substrate were revealed with good confidence.",
    keywords = "atomic layer deposition, ALD, aluminum oxide, nanoindentation",
    author = "Xuwen Liu and Eero Haimi and Simo-Pekka Hannula and Puurunen, {Riikka L.} and Oili Ylivaara",
    note = "Published abstract of a poster 74717 MECHALD",
    year = "2012",
    language = "English",
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    Liu, X, Haimi, E, Hannula, S-P, Puurunen, RL & Ylivaara, O 2012, On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition. in Technical Program & Abstracts. American Vacuum Society AVS, 12th International Conference on Atomic Layer Deposition, ALD 2012, Dresden, Germany, 17/06/12.

    On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition. / Liu, Xuwen (Corresponding author); Haimi, Eero; Hannula, Simo-Pekka; Puurunen, Riikka L.; Ylivaara, Oili.

    Technical Program & Abstracts. American Vacuum Society AVS, 2012.

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

    TY - CHAP

    T1 - On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition

    AU - Liu, Xuwen

    AU - Haimi, Eero

    AU - Hannula, Simo-Pekka

    AU - Puurunen, Riikka L.

    AU - Ylivaara, Oili

    N1 - Published abstract of a poster 74717 MECHALD

    PY - 2012

    Y1 - 2012

    N2 - Atomic layer deposition (ALD) is one of the most promising technologies in producing highly conformal coatings with a strict tolerance in thickness. In the study, ALD Al2O3 coatings of thickness varying from 10 to 600 nm are produced on single-side polished silicon (SSP-Si) wafer at the deposition temperature of 300 °C. This study aims in developing a convenient, efficient and inexpensive method of obtaining reliable coating properties via instrumented nanoindentation to meet the demand of silicon-based microelectronics industry. Hardness and elastic modulus are the most common mechanical properties that are directly derived from nanoindentation data. From Oliver and Pharr's analysis, the unloading data can be well described by a power-law relation: P = a(h-hf)m, where P is the indent load, hf is the residual depth after complete unloading and a and m are material constants. The power-law exponent, m, is found only slightly material dependent for a variety of materials, its value falling between 1.2 and 1.6. However, large m values up to 4 are obtained in certain materials in a consistent basis so that instrument/environment origin can be ruled out. According to the elastic assumption and the extended Hertzian treatment on unloading, m>2 has no physical meaning. The large m is often ascribed to inelastic or reverse plasticity in unloading. Silicon is one of the materials that can demonstrate reverse plasticity through phase transformation during unloading. A careful investigation of the unloading phenomena of the silicon wafer established that reverse plasticity occurred when contact depth was larger than about 8 nm, indicated by large m values at about 3.5. Meanwhile, the characteristics of the loading curve indicate that this depth marked the moment at which transition from elastic to elastic-plastic deformation on loading occurred. When the ALD Al2O3 coatings on the Si-wafer were indented, m dropped and varied narrowly around 1.5 over a large range of indent depths. A conclusion was then reached that the plot of m vs. hC (indent depth) could be used to monitor whether the Si substrate was in elastic or elastic-plastic state when the whole system was under external loading. This provided a guideline for picking up correct values of coating property under the conditions that the substrate only provided elastic support of a small fraction of the indenting load. As a result, it was found that the 10% rule commonly used in extracting coating property from a layered structure could be relaxed and the subtle property differences between the Al2O3 coatings and the Si substrate were revealed with good confidence.

    AB - Atomic layer deposition (ALD) is one of the most promising technologies in producing highly conformal coatings with a strict tolerance in thickness. In the study, ALD Al2O3 coatings of thickness varying from 10 to 600 nm are produced on single-side polished silicon (SSP-Si) wafer at the deposition temperature of 300 °C. This study aims in developing a convenient, efficient and inexpensive method of obtaining reliable coating properties via instrumented nanoindentation to meet the demand of silicon-based microelectronics industry. Hardness and elastic modulus are the most common mechanical properties that are directly derived from nanoindentation data. From Oliver and Pharr's analysis, the unloading data can be well described by a power-law relation: P = a(h-hf)m, where P is the indent load, hf is the residual depth after complete unloading and a and m are material constants. The power-law exponent, m, is found only slightly material dependent for a variety of materials, its value falling between 1.2 and 1.6. However, large m values up to 4 are obtained in certain materials in a consistent basis so that instrument/environment origin can be ruled out. According to the elastic assumption and the extended Hertzian treatment on unloading, m>2 has no physical meaning. The large m is often ascribed to inelastic or reverse plasticity in unloading. Silicon is one of the materials that can demonstrate reverse plasticity through phase transformation during unloading. A careful investigation of the unloading phenomena of the silicon wafer established that reverse plasticity occurred when contact depth was larger than about 8 nm, indicated by large m values at about 3.5. Meanwhile, the characteristics of the loading curve indicate that this depth marked the moment at which transition from elastic to elastic-plastic deformation on loading occurred. When the ALD Al2O3 coatings on the Si-wafer were indented, m dropped and varied narrowly around 1.5 over a large range of indent depths. A conclusion was then reached that the plot of m vs. hC (indent depth) could be used to monitor whether the Si substrate was in elastic or elastic-plastic state when the whole system was under external loading. This provided a guideline for picking up correct values of coating property under the conditions that the substrate only provided elastic support of a small fraction of the indenting load. As a result, it was found that the 10% rule commonly used in extracting coating property from a layered structure could be relaxed and the subtle property differences between the Al2O3 coatings and the Si substrate were revealed with good confidence.

    KW - atomic layer deposition

    KW - ALD

    KW - aluminum oxide

    KW - nanoindentation

    M3 - Conference abstract in proceedings

    BT - Technical Program & Abstracts

    PB - American Vacuum Society AVS

    ER -

    Liu X, Haimi E, Hannula S-P, Puurunen RL, Ylivaara O. On the nanoindentation characterization of Al2O3 thin films grown on Si-wafer by atomic layer deposition. In Technical Program & Abstracts. American Vacuum Society AVS. 2012