Modeling inactive boron during predeposition processes

Vandenbossche, Eric; Baccus, B.

doi:10.1063/1.354022

Cited by 16 publications

(8 citation statements)

References 27 publications

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“…18,20,45 Then in 1999, there appeared simultaneously two DFT-based reports that led to an explicit debate regarding the dominant mechanism. Windl et al 49 used two variants of the nudged elastic band method (NEBM) in concert with a monopole correction for charged systems to obtain barriers between 39 and 68 kJ/mol (0.4 and 0.7 eV) for pair diffusion.…”

Section: History Of the Questionmentioning

confidence: 98%

Pair diffusion and kick‐out: Contributions to diffusion of boron in silicon

Jung¹,

Braatz²,

Seebauer³

2004

AIChE Journal

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Section: History Of the Questionmentioning

confidence: 98%

Pair diffusion and kick‐out: Contributions to diffusion of boron in silicon

Jung¹,

Braatz²,

Seebauer³

2004

AIChE Journal

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“…Based on a kinetic model, Vandenbossche and Baccus [11] showed that including a mobile and inactive substitutional-interstitial boron cluster B s -B i gave the best agreement with the experimental results of Inada et al [12]. However, based on ab initio density functional theory (DFT) studies Zhu et al [5] claimed that ''B s -B i is (relatively) immobile; it is impossible to find a migration path that only breaks one or two bonds while still keeping two B atoms together.''…”

mentioning

confidence: 99%

“…where the factor of 2 arises since two boron atoms are In addition to Vandenbossche and Baccus's work [11], the role of B s -B i diffusion can also be inferred from the observation of anomalous shouldering in diffusion profiles [9]. Clearly, such behavior cannot be explained by B s -Si i diffusion alone.…”

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confidence: 99%

Diffusion of the Diboron Pair in Silicon

Hwang

Goddard

2002

Phys. Rev. Lett.

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We propose a novel mechanism for the diffusion of a diboron pair in Si, based on first principles density functional theory. We find a reaction pathway along which the boron pair diffuses from one lowest energy configuration of [B-B](s)-< 001> to an equivalent structure at an adjacent equivalent site through three local minimum states denoted as [B-B](s)-< 111>, B(s)-B (i), and B(s)-B (s)-Si (i). The activation energy for the diffusion is estimated to be 1.81 eV in the generalized gradient approximation. A kinetic model suggests that the diboron diffusion plays an important role in determining diffusion profiles during ultrashallow junction processing (which requires high boron-dopant concentration as well as high annealing temperature).

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“…10 Attempts have been made to reproduce an evolution of boron profiles under such experimental environments, with low concentration of self-interstitials using a kinetic Monte Carlo approach. 11 The main conclusion of that work was that neither boron-interstitial diffusion mechanism nor boron-interstitial plus boron clustering mechanisms can provide a good fit to experiment. Reasonable fit is only possible if mobile boron pairs are introduced into the model.…”

mentioning

confidence: 91%

“…Reasonable fit is only possible if mobile boron pairs are introduced into the model. 11 In response, Hwang et al used ab initio calculations to demonstrate that the ͗100͘ pair of interstitial and substitutional borons (B 2 I pair of Tarnow 12 ͒ can be mobile with intermediate energy barriers below 1 eV and total energy barrier of 1.8 eV. 13 However, the magnitude of this barrier ͑in comparison to other barriers for boron diffusion͒ could well render the assumption of immobility of the B 2 I pair to be fairly reasonable.…”

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confidence: 98%

Structure and diffusion of interstitial boron pairs in silicon

Shishkin

Souza

2004

Phys. Rev. B

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Using the plane wave pseudopotential approach, the structure and mechanism of migration of an interstitial boron pair are proposed. The energy of the proposed configuration is lower by at least 0.2 eV in comparison to other interstitial boron pairs. The proposed model, which is equivalent to a B 2 I 2 pair ͑using the notation where B m I n refers to m boron atoms and n silicon atoms occupying m regular sites͒, migrates in the ͗110͘ channel with energy barriers between intermediate sites not greater than 0.1 eV and a total energy barrier of 0.6 eV between stable sites. Conventional continuum and kinetic Monte Carlo models of formation of boron interstitial clusters ͑BIC's͒ do not consider the mobility of the proposed configuration in the growth process. Its stability against dissociation could have considerable implications for the modeling of transient enhanced diffusion of boron in silicon.The relentless decrease of feature sizes of semiconductor devices introduces a serious problem in precise control of dopant distribution due to the phenomenon of transient enhanced diffusion ͑TED͒. Although this ultrafast diffusion occurs only for a short period after thermal annealing, swiftly diffusing species have sufficient amount of time to migrate for distances that are comparable to device feature size, creating a problem in monitoring the depth of dopant penetration into the material. It is believed that TED is induced by interactions between dopants and native defects ͑self-interstitials or vacancies͒, which are produced as a result of bombardment by energetic ions during the process of ion implantation. 1 In silicon, TED of boron, a widely used acceptor dopant, is caused predominantly by interstitials as generally agreed on the basis of experimental observations, 2 kinetic Monte Carlo simulations, 3 and ab initio modeling. 4 -7 On an atomic level it was proposed that boron diffuses via alternating ''kick-out'' and ''kick-in'' of boron atom by a self-interstitial. 4,5 In such a mechanism the boron atom at a substitutional site is displaced by a self-interstitial ͑kick-out͒ and forced to migrate until it falls into another substitutional site releasing a self-interstitial ͑kick-in͒. Using experiment, Cowern et al. estimated that kick-out is associated with an energy barrier less than 0.3 eV, 8 which is substantially lower than ''kick-in'' ͑1 eV͒, as obtained by ab initio calculations. 4 Furthermore, Monte Carlo simulations have shown that a kick-in reaction is usually followed by immediate kick-out and therefore boron atoms are not trapped at substitutional sites but migrate as boron-interstitial pairs. 9 In this study the migrational barrier of boron diffusion energy required to fit mean migrational path length was estimated to be 0.55 eV and kick-out and kick-in barriers were 0 and 0.8 eV, respectively. 9 Subsequent ab initio calculations 6,7 confirmed that boron diffuses forming a mobile boron-self-interstitial pair with energy barrier in the range 0.4 -0.7 eV and kick-in dissociation barrier of 0.8 eV.To realize ...

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Modeling inactive boron during predeposition processes

Cited by 16 publications

References 27 publications

Pair diffusion and kick‐out: Contributions to diffusion of boron in silicon

Pair diffusion and kick‐out: Contributions to diffusion of boron in silicon

Diffusion of the Diboron Pair in Silicon

Structure and diffusion of interstitial boron pairs in silicon

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