Detection of molecular oxygen adsorbate during room-temperature oxidation of Si(100)2 × 1 surface: In situ synchrotron radiation photoemission study

Yoshigoe, Akitaka; Yamada, Y.; Taga, Ryo; Ogawa, Shuichi; Takakuwa, Yuji

doi:10.7567/jjap.55.100307

Cited by 6 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous ab initio calculations showed that the initial oxidation of a clean Si surface is based on chemisorption events resulting in the dissociation of the adsorbing O 2 molecule directly at the surface [21][22][23]. This was confirmed experimentally in recent electron microscopy and photoemission studies [24][25][26]. In addition to directly dissociative O 2 adsorption, metastable molecular surface states were observed by means of scanning electron microscopy (SEM) and electron spectroscopy techniques on thin oxide layers [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 70%

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Cvitkovich¹,

Waldhoer²,

El-Sayed³

et al. 2022

Preprint

View full text Add to dashboard Cite

Silicon together with its native oxide SiO2 was recognized as an outstanding material system for the semiconductor industry in the 1950s. In state-of-the-art device technology, SiO2 is widely used as an insulator in combination with high-k dielectrics such as HfO2, demanding fabrication of ultra-thin interfacial layers. The classical standard model derived by Deal and Grove accurately describes the oxidation of Si in a progressed stage, however, strongly underestimates growth rates for thin oxide layers. Recent studies report a variety of oxidation mechanisms during the growth of oxide films in the range of 10 A with various details still under debate. This paper presents a firstprinciples based approach to theoretically assess the thermal oxidation process of the technologically relevant Si(100) surface during this initial stage. Our investigations range from the chemisorption of single O2 molecules onto the p(2 × 2) reconstructed Si surface to oxidized Si surface layers with a thickness of up to 20 A. The initially observed enhanced growth rate is assigned to barrierless O2 chemisorption events upon which the oxygen molecule dissociate. We present strong evidence for an immediate amorphization of the oxide layer from the onset of oxidation. Following the oxidation of the first Si layers a slower oxygen incorporation mechanism is available by molecular precursor states that spontaneously dissociate after a few ps. This process dominates until the surface is saturated with oxygen and separated from the Si substrate by a 5 A transition region. Despite the extremely thin layer, the oxide shows structural characteristics of bulk a-SiO2. The saturated surface becomes inert to dissociative reactions and enables the diffusion of molecular oxygen to the Si/SiO 2 interface as assumed within the Deal-Grove model. Further oxidation of the Si substrate is then provided by O2 dissociations at the interface due to the same charge transfer process responsible for the chemisorption at the surface.

show abstract

Section: Introductionmentioning

confidence: 70%

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Cvitkovich¹,

Waldhoer²,

El-Sayed³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…O 2 dissociative adsorption takes place on the Si(001)2 × 1 surface with no apparent potential barrier for oxygen atom to occupy the dimer backbond. 25,85) The dimer Si atom and the subsurface Si atom change to the oxidation state of Si 1+ as shown in Fig. 38(b).…”

Section: 2mentioning

confidence: 99%

“…On the Si(001) surface, the dimer backbond is preferentially occupied by the oxygen atom with no apparent potential barrier. 25,85) On the analogy to the surface oxidation, the dissociative adsorption of O 2 molecule at the V + and V − sites results in the formation of two couples of P b0 and P b1 centers in Branch III. In this case, there remains four dangling bonds and hence further oxidation is necessary for oxidizing the vacancy completely.…”

Section: Reaction Of O 2 Molecule With Vacancy At Thementioning

confidence: 99%

“…Angle-resolved XPS was also employed to measure the depth profile of SiO near the SiO 2 surface to clarify the reaction between SiO and O 2 molecules in the SiO 2 film. 74) In this paper, we review the study of the unified Si oxidation reaction model mediated by point defect generation: The competition between the SiO 2 growth and decomposition, [74][75][76] the phase transitions in the surface oxidation, [77][78][79][80][81][82][83][84][85] the SiO 2 decomposition kinetics, 86,87) the lattice site of the adsorbed O atom, 88,89) the correlation between the SiO 2 growth rate and the SiO 2 decomposition rate, 90) the Si emission kinetics, 72,91) the self-accelerating oxidation, 92) the thermal strain-induced enhancement of dX O /dt, 93) the P O2 dependence of dX O /dt, 94) the temperature and P O2 dependence of dX O /dt during the layer-by-layer oxidation, 95) the oxidation reaction kinetics of the Si 1−x C x alloy layer (x ; 0.1) formed on Si(001) surfaces. 96) This review paper consists of five chapters.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Roles of strain and carrier in silicon oxidation

Ogawa

Yoshigoe

Tang³

et al. 2020

Jpn. J. Appl. Phys.

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…[11][12][13][14][15][16] Recently, Yoshigoe et al observed a subtle peak attributed to the presence of a chemisorbed molecular oxygen on Si (001) surfaces during the oxidation process by the XPS experiments. 17) They suggested that the most plausible structure for the chemisorbed molecular oxygen is the paul configuration adsorbed on a Si dimer with being oxidized by two O atoms, based on the experimental results for the oxidation states of Si and O atoms and the surface O coverage. However, detailed adsorption states have not been cleared yet, because it is difficult to distinguish the paul and grif configurations only with experiments.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on adsorption state of chemisorbed oxygen molecule on partially oxidized Si(001) surface

Kadowaki

Oda

Nara

2021

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

We theoretically investigate the structures and electronic states of a chemisorbed oxygen molecule on partially oxidized Si(001) surfaces by using first-principles calculation. For two configurations, paul and grif, suggested as a chemisorbed oxygen molecule, we obtained: (i) the grif is more stable than the paul, while the relative stability between the two depends on the surrounding structures. (ii) The charge states of the paul and the grif are −1 and −2, respectively. (iii) The paul is spin polarized, while the grif is not. (iv) The paul exhibits two peaks in the XPS calculation, while the grif exhibits one degenerate peak. These results provide fundamental information for the surface species to understand the oxidation process of Si(001) surfaces.

show abstract

Detection of molecular oxygen adsorbate during room-temperature oxidation of Si(100)2 × 1 surface: In situ synchrotron radiation photoemission study

Cited by 6 publications

References 31 publications

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Roles of strain and carrier in silicon oxidation

Theoretical study on adsorption state of chemisorbed oxygen molecule on partially oxidized Si(001) surface

Contact Info

Product

Resources

About