Fluorine-enhanced boron diffusion in amorphous silicon

Jacques, Jeannette M.; Robertson, L. S.; Jones, K. S.; Law, Mark E.; Rendon, M.J.; Bennett, Joe

doi:10.1063/1.1576508

Cited by 40 publications

(25 citation statements)

References 9 publications

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“…The extracted B diffusivity is about 10 -16 cm 2 /s. This observation agrees with the previous report showing B diffusivity in aSi is 5 orders of magnitude greater than in crystalline Si (cSi) [9]. Fig.…”

Section: B Boron Diffusion During Sub-ms Annealing Processsupporting

confidence: 93%

Analysis of Dopant Diffusion and Defect Evolution during sub-millisecond Non-melt Laser Annealing based on an Atomistic Kinetic Monte Carlo Approach

Noda¹,

Vandervorst²,

Felch³

et al. 2006

2006 International Electron Devices Meeting

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Sub-millisecond (ms) non-melt laser annealing (NLA) is investigated through experiments and atomistic KMC modeling.NLA can improve the dopant activation dramatically and achieve shallow junctions. B diffusivity during sub-ms annealing is discussed for the first time. Our KMC model with F n V m complexes indicates that the thermal budget of sub-ms annealing is too small for full defect evolution and one possible solution for defect stabilization is F co-implant.

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Section: B Boron Diffusion During Sub-ms Annealing Processsupporting

confidence: 93%

Analysis of Dopant Diffusion and Defect Evolution during sub-millisecond Non-melt Laser Annealing based on an Atomistic Kinetic Monte Carlo Approach

Noda¹,

Vandervorst²,

Felch³

et al. 2006

2006 International Electron Devices Meeting

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“…4 In that work, more diffusion was observed for boron coimplanted with fluorine in silicon pre-amorphized silicon. 4 In that work, more diffusion was observed for boron coimplanted with fluorine in silicon pre-amorphized silicon.…”

mentioning

confidence: 80%

Boron diffusion in amorphous silicon and the role of fluorine

Duffy

Venezia

Heringa

et al. 2004

Applied Physics Letters

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We demonstrate that boron diffuses at high concentrations during low-temperature thermal annealing in amorphous silicon pre-amorphized by germanium ion implantation. For a typical boron ultrashallow junction doping profile, concentrations as high as 2ϫ10 20 cm Ϫ3 appear to be highly mobile at 500 and 600°C in the amorphous silicon region before recrystallization. In crystalline silicon at the same temperatures the mobile boron concentration is at least two orders of magnitude lower. We also show that boron diffusivity in the amorphous region is similar with and without fluorine. The role of fluorine is not to enhance boron diffusivity, but to dramatically slow down the recrystallization rate, allowing the boron profile to be mobile up to the concentration of 2 ϫ10 20 cm Ϫ3 for a longer time.

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“…One of the first evidence of B diffusion in a-Si was given by Jacques et al in ultra-low energy (0.5 keV) B implanted preamorphized Si enriched with fluorine and annealed at 550 C, 39 showing the formation of a large shoulder in the B profile at the concentration range of 5 Â 10 18 -1 Â 10 20 B/ cm 3 . Later on, the role of fluorine was ruled out by Ray Duffy et al, evidencing how during low temperature annealing (500-600 C) B diffusion occurs also in F-free a-Si up to very high B concentrations (2 Â 10 20 at./cm 3 ), at least two orders of magnitude higher than the mobile boron concentration in c-Si at the same temperatures (Fig.…”

Section: B Main Features Of B Migrationmentioning

confidence: 97%

Mechanisms of boron diffusion in silicon and germanium

Mirabella

Salvador

Napolitani

et al. 2013

Journal of Applied Physics

104

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B migration in Si and Ge matrices raised a vast attention because of its inﬂuence on the production of conﬁned, highly p-doped regions, as required by the miniaturization trend. In this scenario, the diffusion of B atoms can take place under severe conditions, often concomitant, such as very large concentration gradients, non-equilibrium point defect density, amorphous-crystalline transition, extrinsic doping level, co-doping, B clusters formation and dissolution, ultra-short high-temperature annealing. In this paper, we review a large amount of experimental work and present our current understanding of the B diffusion mechanism, disentangling concomitant effects and describing the underlying physics. Whatever the matrix, B migration in amorphous (a-) or crystalline (c-) Si, or c-Ge is revealed to be an indirect process, activated by point defects of the hosting medium. In a-Si in the 450-650 C range, B diffusivity is 5 orders of magnitude higher than in c-Si, with a transient longer than the typical amorphous relaxation time. A quick B precipitation is also evidenced for concentrations larger than 2 x10^20 B/cm3. B migration in a-Si occurs with the creation of a metastable mobile B, jumping between adjacent sites, stimulated by dangling bonds of a-Si whose density is enhanced by B itself (larger B density causes higher B diffusivity). Similar activation energies for migration of B atoms (3.0 eV) and of dangling bonds (2.6 eV) have been extracted. In c-Si, B diffusion is largely affected by the Fermi level position, occurring through the interaction between the negatively charged substitutional B and a self-interstitial (I) in the neutral or doubly positively charged state, if under intrinsic or extrinsic (p-type doping) conditions, respectively. After charge exchanges, the migrating, uncharged BI pair is formed. Under high n-type doping conditions, B diffusion occurs also through the negatively charged BI pair, even if the migration is depressed by Coulomb pairing with n-type dopants. The interplay between B clustering and migration is also modeled, since B diffusion is greatly affected by precipitation. Small (below 1 nm) and relatively large (5-10 nm in size) BI clusters have been identiﬁed with different energy barriers for thermal dissolution (3.6 or 4.8 eV, respectively). In c-Ge, B motion is by far less evident than in c-Si, even if the migration mechanism is revealed to be similarly assisted by Is. If Is density is increased well above the equilibrium (as during ion irradiation), B diffusion occurs up to quite large extents and also at relatively low temperatures, disclosing the underlying mechanism. The lower B diffusivity and the larger activation barrier (4.65 eV, rather than 3.45 eV in c-Si) can be explained by the intrinsic shortage of Is in Ge and by their large formation energy. B diffusion can be strongly enhanced with a proper point defect engineering, as achieved with embedded GeO2 nanoclusters, causing at 650 °C a large Is supersaturation. These aspects of B diffusion are presented and discus...

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Fluorine-enhanced boron diffusion in amorphous silicon

Cited by 40 publications

References 9 publications

Analysis of Dopant Diffusion and Defect Evolution during sub-millisecond Non-melt Laser Annealing based on an Atomistic Kinetic Monte Carlo Approach

Analysis of Dopant Diffusion and Defect Evolution during sub-millisecond Non-melt Laser Annealing based on an Atomistic Kinetic Monte Carlo Approach

Boron diffusion in amorphous silicon and the role of fluorine

Mechanisms of boron diffusion in silicon and germanium

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