The interfacial chemistry of a strontium/silicon oxynitride nanostructure was investigated with x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) to determine if can serve as a barrier for the strontium titanate high-k dielectric. The structure consisted of 19 Å (5 ML) of Sr on a 10 Å barrier layer on a Si(100) substrate. Both XPS and SIMS results suggest that strontium oxide (SrO) and silicon dioxide at the interface form strontium silicate even at 300 K. The kinetics of this reaction were accelerated by heating the structure in a stepwise fashion to 1000 K. After the 500 K anneal, the SrO and XPS chemical states attenuate leaving predominantly two silicate phases. Annealing the nanostructure to 1000 K tested the barrier capability of the 10 Å layer to Sr diffusion. SIMS and signals reveal that Sr containing species do not significantly penetrate below the bonds characteristic of Comparison of 10 Å and 10 Å confirms that the bonds are the key to the barrier properties. Without N atoms, the signal increased by a factor of 3.6 and penetrated 26 Å deeper into the Si substrate after a 900 K anneal. These results show that N atoms in the barrier layer retard Sr diffusion and silicate formation. Comparison of Ba and Sr on suggests that Ba is more likely to form silicide, whereas Sr is more likely to form silicate.
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Research Article| September 01 2001
Interfacial chemistry of the nanostructure
P. D. Kirsch;
P. D. Kirsch, J. G. Ekerdt; Interfacial chemistry of the nanostructure. J. Vac. Sci. Technol. A 1 September 2001; 19 (5): 2222–2231. https://doi.org/10.1116/1.1379803
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