Trap assisted leakage current conduction in thin silicon oxynitride films grown by rapid thermal oxidation combined microwave excited plasma nitridation

Thin films of silicon oxynitride (SiON) were grown on Si substrates by nitriding rapid thermally grown SiO2 layers in a microwave-excited nitrogen plasma and by subsequent re-oxidation. The enhanced leakage current in SiON at oxide fields 5-7 MV/cm is due to a trap assisted tunneling current. Trap assisted tunneling current analysis indicated a trap level of 1 eV below the conduction band edge, which is shallower than ∼2.5 eV level reported for nitrogen related traps in thermally nitrided SiO2. This shallower trap level suggests that its origin could be oxygen vacancies in the rapid thermal oxide, generated in the plasma nitridation.

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