Double nitridation of crystalline ZrO 2 /Al 2 O 3 buffer gate stack with high capacitance, low leakage and improved thermal stability

Jhih Jie Huang, Yi Jen Tsai, Meng Chen Tsai, Min-Hung Lee, Miin Jang Chen

    Research output: Contribution to journalArticle

    4 Citations (Scopus)

    Abstract

    The gate dielectric stack composed of crystalline ZrO 2 and Al 2 O 3 buffer layer treated with double nitridation was developed to reduce the capacitance equivalent thickness (CET), leakage current density (J g ), interfacial state density (D it ), and enhance thermal stability as well. A high dielectric constant of the gate stack was provided by the crystalline ZrO 2 with tetragonal/cubic phase. The J g and D it were suppressed by the insertion of the Al 2 O 3 buffer layer treated with remote NH 3 plasma nitridation because of the deactivation of the oxygen vacancies and the well passivation of the Si dangling bonds. A further nitridation using remote N 2 plasma on ZrO 2 was carried out to reduce the CET and J g by the enhancement of the dielectric constant and the deactivation of the grain boundaries and oxygen vacancies. Accordingly, a low CET of 1.09 nm, J g of 3.43 × 10 -5 A/cm 2 , and D it of 3.35 × 10 11 cm -2 eV -1 were achieved in the crystalline ZrO 2 /Al 2 O 3 buffer gate stack treated with the double nitridation. The hysteresis was also minimized significantly by the post-deposition annealing at 800 °C, which is attributed to the enhanced thermal stability. The results indicate that the crystalline high-K dielectrics/buffer layer with double nitridation treatments is a promising gate stack structure beneficial to the sub-nanometer CET scaling in the future.

    Original languageEnglish
    Pages (from-to)221-227
    Number of pages7
    JournalApplied Surface Science
    Volume330
    DOIs
    Publication statusPublished - 2015 Mar 1

    Fingerprint

    Nitridation
    Buffers
    Thermodynamic stability
    Capacitance
    Crystalline materials
    Buffer layers
    Oxygen vacancies
    Permittivity
    Plasmas
    Dangling bonds
    Gate dielectrics
    Passivation
    Leakage currents
    Hysteresis
    Grain boundaries
    Current density
    Annealing

    Keywords

    • Atomic layer deposition
    • Buffer layer
    • High-K gate dielectrics
    • Nitridation
    • Zirconium oxide

    ASJC Scopus subject areas

    • Surfaces, Coatings and Films

    Cite this

    Double nitridation of crystalline ZrO 2 /Al 2 O 3 buffer gate stack with high capacitance, low leakage and improved thermal stability . / Huang, Jhih Jie; Tsai, Yi Jen; Tsai, Meng Chen; Lee, Min-Hung; Chen, Miin Jang.

    In: Applied Surface Science, Vol. 330, 01.03.2015, p. 221-227.

    Research output: Contribution to journalArticle

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    AB - The gate dielectric stack composed of crystalline ZrO 2 and Al 2 O 3 buffer layer treated with double nitridation was developed to reduce the capacitance equivalent thickness (CET), leakage current density (J g ), interfacial state density (D it ), and enhance thermal stability as well. A high dielectric constant of the gate stack was provided by the crystalline ZrO 2 with tetragonal/cubic phase. The J g and D it were suppressed by the insertion of the Al 2 O 3 buffer layer treated with remote NH 3 plasma nitridation because of the deactivation of the oxygen vacancies and the well passivation of the Si dangling bonds. A further nitridation using remote N 2 plasma on ZrO 2 was carried out to reduce the CET and J g by the enhancement of the dielectric constant and the deactivation of the grain boundaries and oxygen vacancies. Accordingly, a low CET of 1.09 nm, J g of 3.43 × 10 -5 A/cm 2 , and D it of 3.35 × 10 11 cm -2 eV -1 were achieved in the crystalline ZrO 2 /Al 2 O 3 buffer gate stack treated with the double nitridation. The hysteresis was also minimized significantly by the post-deposition annealing at 800 °C, which is attributed to the enhanced thermal stability. The results indicate that the crystalline high-K dielectrics/buffer layer with double nitridation treatments is a promising gate stack structure beneficial to the sub-nanometer CET scaling in the future.

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