First-principles study of strain effect on oxygen vacancy in silicon oxide

Abstract

The strain dependence of stability and diffusion barrier height of the O vacancy in Si oxide is examined using the first-principles calculation. It is found that the stability and the diffusion barrier height increase as the oxide is compressed. The analysis shows that the diffusion barrier height is determined by the Si–Si distance of the O vacancy. Based on these results, the dielectric breakdown of the gate Si oxide film in the three-dimensional structure metal-oxide-semiconductor field-effect transistor is also considered. It is suggested that the interfacial O-vacancy density increases because the interfacial oxide is subjected to compressive strain. On the other hand, the surface O-vacancy density decreases and the surface O-vacancy diffusion is promoted because the surface oxide is subjected to tensile strain. The reliability of the oxide film might be thus affected by the strain.

First-principles study on barrier height of silicon emission from interface into oxide during silicon thermal oxidation

“…barrier height of 2.84 eV for the VOT in this study is rather close to the barrier height of 2.86 eV for V O diffusion in homogeneous bulk SiO 2 with 10% tensile strain. 45) This suggests that V O , which appear temporarily during the Si emission process, are placed in a tensile strain of about 10% on average. This is surely reasonable if we consider that V O appear during the I SiO diffusion process when I SiO temporarily takes O from the surroundings to become I SiO2 , and that the presence of I SiO2 also causes very local tensile strain in the surroundings.…”

“…However, we have already seen that the barrier height for V O diffusion is largely enhanced when compressive strain is applied. 45) This means that V O diffusion should be suppressed when compressive strain is applied. Contrarily, it is known that Si self-diffusion in SiO 2 is enhanced when strain is applied.…”

“…This time, we calculated the barrier height of each microscopic processes between the neighboring metastable structures by using the nudged elastic band (NEB) method. [44][45][46] The start and goal structures of the path are shown in Fig. 1, and the detailed metastable structures on the path are shown in Fig.…”

A novel route of colloidal chemistry: room temperature reactive interactions between titanium monoxide and silicon monoxide sols produced by laser ablation in liquid resulting in the formation of titanium disilicide

“…8A). These could be neutral O vacancies enlarged by electron trapping, 74 metastable O vacancies with a longer lifetime, 75 cluster growth and interface obliteration in SiO disproportionation associated with cluster coarsening and vacancy mediated diffusion, 76 surface O-vacancy diffusion affected by surface strain, 77 the existence of several silicon oxidation states in the near-interface region, 78 different extents of Si-substituted Ti 4+ sites and Si incorporated interstitial sites 79 or enhanced diffusion of Ti in the SiO 2 layer. 80 In addition, contrary to the bulk and extended surfaces, it was computationally predicted 81 that removing an oxygen atom from SiO 2 nanoclusters is energetically more favorable than from the respective TiO 2 species and that this unexpected chemical behavior is in line with the inherent occurrence of terminal unsaturated oxygens in these clusters.…”