Plasma-charging damage to gate SiO2 and SiO2/Si interfaces in submicron n-channel transistors: Latent defects and passivation/depassivation of defects by hydrogen

Osama O. Awadelkarim, S. J. Fonash, P. I. Mikulan, Y. D. Chan

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Abstract

New experimental results are presented which provide evidence for hydrogen passivation and depassivation of plasma-charging-induced defects in gate oxides and at oxide/silicon interfaces. The devices used in this study were 0.5 μm n-channel metal-oxide-semiconductor field-effect transistors fabricated on 200 mm boron-doped silicon substrates. The processing included Cl2/HBr-based chemistries for the polycrystalline silicon gate definition etch, and CHF3/CF4-based chemistries for the contact etch. Plasma-charging defects resulting from the processing are shown to have the following properties: (i) plasma-induced charging defects are latent (electrically inactive) directly after our processing and before postmetallization annealing (PMA); (ii) these defects continue to be latent after N2 and Ar anneals done at temperatures T in the range 200°C≤T≤400°C; (iii) these defects are also latent after our standard PMA done in forming gas at 400°C; (iv) these defects are electrically activated by room-temperature Fowler-Nordheim stress, and (v) equivalently these defects are electrically activated by annealing below 400°C in hydrogen-rich ambients. We show hydrogen passivation/depassivation is responsible for this behavior. This passivation/depassivation has been previously suggested to occur for defects at SiO2/Si interface; here it is also proposed to describe defect-hydrogen interactions in the bulk gate oxide for defects caused by plasma-charging damage.

Original languageEnglish (US)
Pages (from-to)517-525
Number of pages9
JournalJournal of Applied Physics
Volume79
Issue number1
DOIs
Publication statusPublished - Jan 1 1996

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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