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

1996; American Institute of Physics; Volume: 79; Issue: 1 Linguagem: Inglês

10.1063/1.360860

1520-8850

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

Diamond and Carbon-based Materials Research

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.