Diffusion of near surface defects during the thermal oxidation of silicon

Ganem, J.‐J.; Trimaille, I.; André, P; Rigo, S.; Stedile, Fernanda Chiarello; Baumvol, Israel Jacob Rabin

doi:10.1063/1.365420

Cited by 37 publications

(59 citation statements)

References 9 publications

(10 reference statements)

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“…[20] that the oxygen gas was quite dry, and in Refs. [21,22] a residual water concentration of about 10 ppm was claimed. These correlations provide strong evidence that trace water is the main source of the 18 O profile measured at the silica-gas surface in these studies.…”

Section: Effect Of Residual Water On Measurements Of Oxygen Diffusionmentioning

confidence: 97%

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Transport of oxygen in silicate glasses

Doremus

2004

Journal of Non-Crystalline Solids

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Section: Effect Of Residual Water On Measurements Of Oxygen Diffusionmentioning

confidence: 97%

“…S T = 4.41 (10) 22 O atoms/cm 3 , and the diffusion coefficient D of molecular water equals 1.7(10) À7 cm 2 /s at 1000°C [10]. From these numbers and the D e values in Table 1 C T values can be calculated from Eq.…”

Section: Effect Of Residual Water On Measurements Of Oxygen Diffusionmentioning

confidence: 99%

Transport of oxygen in silicate glasses

Doremus

2004

Journal of Non-Crystalline Solids

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“…The quartz tube was exposed to 15 a transition at 10 mbar, where below 10 mbar it has a square root dependence of pressure and above 10 mbar the pressure dependency is less than 1/2. The results in Fig.…”

Section: Methodsmentioning

confidence: 99%

Reactions in the System O 2 ‐ NO ‐ SiO2 in a Conventional Furnace: I. Oxygen Exchange Reactions

Åkermark¹,

Ganem²,

Trimaille³

et al. 1999

J. Electrochem. Soc.

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There are many chemical reactions occurring when samples are oxidized in a conventional furnace, both with the sample and within the furnace itself. Many of the reactions are not gas-phase reactions, but take place on a third body (catalyst), which is typically a surface or interface. Thereby the catalytic activity of these third bodies is vital for reaction kinetics. The third body can be both the sample itself and the walls of the furnace. The oxidation mechanisms are, of course, directly related to the reactions taking place on the sample. The reactions in the furnace can result in changes in gas-phase composition and pressure, and thereby change the oxidation conditions. The oxidation kinetics can be extremely sensitive to gas-phase composition and an example is oxidation of silicon where parts per million of water vapor increase the oxidation rate considerably. 1 In order to control the atmosphere in the furnace it is therefore vital to know the chemical reactions that occurs. A chemical reaction usually proceeded in many steps and, to fully understand the reaction, knowledge of all steps and the mechanisms active in each step are required. However, we seldom have this complete understanding of the reactions. Luckily, it is in many cases sufficient to understand the main steps of the reaction and in particular the rate-limiting step. Oxidation of silicon and metals (substrate) involves reactions like bond breaking in the O 2 molecule, charge transfer between O 2 and the substrate, and incorporation of oxygen in the oxide. Apart from the chemical reactions, there are also other processes, like diffusion, which can limit the oxidation kinetics. 2 The formation of a solid oxide will separate the oxygen source from the substrate and for the reaction to proceed the oxidizing species (which can be, for example, O 2Ϫ , O 2 , O, Me, or Me nϩ ) has to be transported through the growing oxide (diffusion). However, even when diffusion is rate limiting, an understanding of the chemical reactions active at the two interfaces (O 2 -oxide and oxide-substrate) is needed, since these reactions set the boundary conditions for diffusion. 3,4 The various oxygen exchange reactions, by using isotopic labeled oxygen, 3,5-7 can be used to study the chemical reactions and the diffusion. There are three stable isotopes of oxygen which can be used, and the natural abundance of oxygen is 99.76% 16 O, 0.04% 17 O, and 0.2% 18 O. All three isotopes are available highly enriched on the commercial market. Today the isotopes 16 O and 18 O are the most frequently used, especially when studying oxidation in pure O 2 .The exchange reactions of most interest in oxidation are the oxygen exchange between oxygen molecules catalyzed by the surface of the oxide (O 2 o O 2 ) and between oxygen molecules and the oxide (O 2 o SiO 2 and O 2 o Me x O y ). Although the rate of the exchange reactions depends on many parameters, like the thickness of the growing oxide, a study of the bulk oxide can give valuable information on the active mechanisms. In princ...

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“…7,25 This is an argument for atomic oxygen not being the transported species since atomic oxygen is so reactive that it would react with the oxygen network.…”

Section: Same Activation Energy Of Diffusion For O 2 Andmentioning

confidence: 98%

Molecular or Atomic Oxygen as the Transported Species in Oxidation of Silicon

Åkermark¹

2000

J. Electrochem. Soc.

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Oxidation of silicon is one of the most studied oxidation processes, mainly because it is a vital step in the fabrication of data chips for the computer industry. Several review articles have been published, 1-7 and since the end of the 1980s it has been generally accepted that the oxide growth occurs by transport of molecular oxygen through the oxide. This belief originates from the oxidation model proposed by Deal and Grove. 8 The Deal-Grove theory, and thereby the transport of molecular oxygen, cannot explain the initial stage of oxidation and has difficulties explaining the sensitivity of oxidation to interface modifications and contaminants (both in the gas phase and on the surface of the SiO 2 ). Several experimental results and arguments have been used to support molecular oxygen as the transported species. The main experimental results and arguments are 1-7 (i) a linear pressure dependence of the parabolic rate constant over a large range of temperatures and pressures; (ii) the activation energy of oxygen diffusion in SiO 2 is the same as for Ar, since O 2 and Ar have the same diameter; (iii) the lack of a straightforward dissociation mechanism for O 2 in SiO 2 ; and (iv) "conventional physicochemical wisdom." 3 Conventional physicochemical wisdom is based on the reaction order, thermodynamics, and the extreme reactivity of radicals (like atomic oxygen), i.e., that oxygen should react with the oxygen network when transported through the oxide, producing oxygen exchange. However, closer examination of these results does not prove that O 2 is the transported species and does not disfavor atomic oxygen at all as the transported species. Recent experiments have shown that (i) the dissociation rate of the oxygen molecules at the surface of the SiO 2 is much higher than the oxidation rate; 9 (ii) there is a coupling between the dissociation rate and the oxidation kinetics; 10 (iii) the oxygen exchange between O 2 molecules catalyzed by the SiO 2 surface (O 2 } O 2 ) varies with pressure raised to the second power; and (iv) there is an oxygen exchange at the internal interface. 11 The pressure dependency squared of the oxygen exchange (O 2 } O 2 ) indicates that the concentration of atomic oxygen depends linearly on the oxygen pressure and so explains a linear pressure dependency of the parabolic rate constant. All these experimental results favor atomic oxygen as the migrating species. In this study the different experimental results are used to argue for atomic and molecular oxygen, respectively, as the transported species. Each result is discussed as an argument for atomic or molecular oxygen as the transported species and given a mark on a seven-graded scale (ϩϩϩ to ϪϪϪ). Summing up the marks, atomic oxygen receives 17ϩ and 0Ϫ (⌺17ϩ), while molecular oxygen receives 3ϩ and 5Ϫ (⌺2Ϫ), leading us to conclude that atomic oxygen is much more likely to be the transported species. ExperimentalA mass spectrometer setup was used to measure the oxygen exchange between O 2 molecules catalyzed by an SiO 2 surface (O 2 ...

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Diffusion of near surface defects during the thermal oxidation of silicon

Cited by 37 publications

References 9 publications

Transport of oxygen in silicate glasses

Transport of oxygen in silicate glasses

Reactions in the System O 2 ‐ NO ‐ SiO2 in a Conventional Furnace: I. Oxygen Exchange Reactions

Molecular or Atomic Oxygen as the Transported Species in Oxidation of Silicon

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