Roles of strain and carrier in silicon oxidation

Abstract

In this paper we review the study of the unified Si oxidation reaction model mediated by point defect generation, in which O 2 dissociative adsorption occurs at dangling bonds of point defects (emitted Si atoms and vacancies) at the SiO 2 /Si interface, and the point defect generation rate is given by a combination of oxidation-induced strain, thermal strain due to the difference in thermal expansion coefficient between Si and SiO 2 , thermal excitation of Si emission rate, and heat of adsorption. The band bending of the SiO 2 /Si interface is caused by the electron and hole trapping at the vacancy for n-and p-Si substrates, respectively, leading to the charged states with unpaired electrons that is responsible for the dissociative adsorption of O 2 molecule. Since P b0 and P b1 centers with unpaired electron are not concerned with the charge transfer of band bending, they are also the active sites for O 2 dissociative adsorption.

Oxidation Mechanisms of Hafnium Overlayers Deposited on an Si(111) Substrate

“…A peak attributed to a strained Si component appears at +0.27 eV relative to the region between the Si 2p 1/2 and Si 2p 3/2 peaks of the bulk component. This peak corresponds to the first strained Si layer. , A weak Si peak appearing at a lower BE around −0.3 eV, relative to the Si bulk, may be attributed to the second strained Si layer at the SiO 2 /Si interface in Figure e. , The observation of strained Si species strongly supports the hypothesis that volatile Si atoms are generated. − …”

“…The ratio of the area under the O 4 component (SiO 2 ) to the total area under the O 1s peak was clearly reduced from 39% in the surface-sensitive result [escape depth (ED) ≈ 2.1−2.4 Å] to 29% in the bulksensitive result (ED ≈ 6.1−7.1 Å). 39,40 Moreover, the intensity of the interfacial Hf silicate (Si*) component in Figure 6e is lower than that in Figure 6d. These results indicate that some SiO 2 overlayers were formed on the Hf silicate layers as the outermost layers.…”

“…This peak corresponds to the first strained Si layer. 38,39 A weak Si peak appearing at a lower BE around −0.3 eV, relative to the Si bulk, may be attributed to the second strained Si layer at the SiO 2 /Si interface in Figure 6e. 38,39 The observation of strained Si species strongly supports the hypothesis that volatile Si atoms are generated.…”

“…38,39 A weak Si peak appearing at a lower BE around −0.3 eV, relative to the Si bulk, may be attributed to the second strained Si layer at the SiO 2 /Si interface in Figure 6e. 38,39 The observation of strained Si species strongly supports the hypothesis that volatile Si atoms are generated. 38−41 Consistent oxidation behaviors were confirmed in the O 1s photoelectron spectra, following SOMB irradiation, and their fitting results.…”

“…In previous oxidation studies of clean Si substrates, the first and second strained Si layers were observed in the Si 2p 1/2,3/2 photoelectron spectrum accompanied by the generation of interfacial SiO 2 layers. 38,39 In the fit plotted in Figure 6e, strained Si layers are also required to reproduce the recorded profile. These strained Si layers were generated in the interfacial region of SiO 2 /Si beneath the outermost HfO 2 layers.…”