Negative Charge in Plasma Oxidized SiO2 Layers

Arjen Boogaard, Alexeij Y. Kovalgin, Rob Wolters

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    12 Citations (Scopus)
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    Abstract

    SiO2 gate dielectric layers were deposited on n-type Si by inductively-coupled plasma-enhanced chemical vapor deposition (ICPECVD) at 150°C. In contrast to the well-accepted positive charge for thermally grown SiO2, the net oxide charge was negative and a function of the layer thickness. Our experiments suggested that the negative charge was created due to unavoidable oxidation of the silicon surface by plasma species. The CVD component added a positive space charge to the oxide. Additional measurements showed that the negative charge in SiO2 also persisted on p-type substrates. We suggest that plasma oxidation of the silicon surface results in SiO2 with a surplus of oxygen, which is able to accumulate a negative charge. This assumption is addressed by a series of experiments wherein oxygen is implanted into thermal SiO2. It is shown that the implantation can result in a negative charge to the bulk oxide layer.
    Original languageEnglish
    Pages (from-to)259-272
    Number of pages14
    JournalECS transactions
    Volume35
    Issue number4
    DOIs
    Publication statusPublished - 1 Jul 2011
    Event219th ECS Meeting - The Palais des Congres de Montreal, Montreal, QC, Canada
    Duration: 1 May 20116 May 2011
    Conference number: 219

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