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Low temperature plasma nitridation of thin thermal SiO2 and a silicon surface with native oxide

1990; Volume: 21; Issue: 1 Linguagem: Inglês

10.1016/0026-2692(90)90003-l

0026-2692

E. Atanassova, J. Kassabov, E. Goranova,

Advanced ceramic materials synthesis

The interface, oxide and transport characteristics of the silicon/thin thermal SiO2 (20–35 nm) system after nitridation in a low temperature, "soft" ammonia plasma are investigated. Plasma conditions are found which lead to full transformation of the initial thermal oxide (thickness about 20 nm) into stoichiometric oxynitride film. The nitridation process consists of two stages: (i) formation of an oxynitride layer with worse dielectric and interface characteristics than those of the initial thermal oxide; and (ii) a further nitridation process leading to improvement of the properties of the formed oxynitride layer and its interface with Si without any stoichiometric change. It is shown that the "soft" r.f. ammonia plasma, reacting with the native oxide on the silicon, induces growing of ultrathin oxynitride film. The properties of this layer in terms of its dependence on the substrate temperature (293–573 K) and plasma nitridation time (2–180 min) are investigated.