Role of C and B clusters in transient diffusion of B in silicon

Cowern, N.E.B.; Cacciato, A.; Custer, J. S.; Saris, F.W.; Vandervorst, Wilfried

doi:10.1063/1.115706

Cited by 59 publications

(28 citation statements)

References 6 publications

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“…As mentioned in the introduction, the interest in the behavior of carbon in silicon increased drastically when it was shown that a high concentration of grown-in carbon almost suppressed TED of boron [11,12]. Initially, it was assumed that substitutional carbon would simply trap silicon self-interstitials and thus reduce their concentration.…”

Section: Behavior Of Grown-in Carbon At High Concentrationsmentioning

confidence: 99%

“…The fact that implanted carbon does not lead to interstitial-type dislocation loops [4] indicates that carbon atoms somehow 're-absorb' the produced self-interstitials. The additional observation that carbon implantation may even reduce TED of boron indicates that carbon may capture back more than just the one extra self-interstitial generated, but roughly ten to fifteen percent more, if the actual results are taken into account [12]. In analogy to the popular "+1 model" one could speak of a "minus 0.1 model" in the case of carbon implantation.…”

Section: Precipitation Behaviormentioning

confidence: 99%

“…This interest in carbon in silicon increased dramatically when it was shown by the group around Gossmann at Bell Labs [10][11][12] that a relatively high grown-in concentration of carbon practically suppressed TED of boron. This opened up the possibility to fabricate silicon bipolar transistors or Si-Ge based heterobipolar transistors with a very narrow base region (due to the suppressed diffusion of the base dopant boron) which is of enormous interest for ultra-high frequency applications [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Diffusion Engineering by Carbon in Silicon

et al. 2000

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The possibility to suppress undesirable diffusion of the base dopant boron in siliconbased bipolar transistor structures by the incorporation of a high concentration of carbon has lead to renewed interest in the behavior of carbon in crystalline silicon. The present paper will review essential features of carbon in silicon including solubility, diffusion mechanisms and precipitation behavior. Based on this information the possibilities to use carbon to influence diffusion of dopants in silicon by the introduction of non-equilibrium concentrations of intrinsic point defects will be discussed as well as the reason for the relatively high resilience against carbon precipitation. Interactions between carbon and oxygen will be mentioned, especially in the context of an as yet unexplained fast out-diffusion of carbon close to the surface.

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Section: Behavior Of Grown-in Carbon At High Concentrationsmentioning

confidence: 99%

Section: Precipitation Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diffusion Engineering by Carbon in Silicon

et al. 2000

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“…73 Further confirmation of this came with the evidence that B clustering effectively contributes to lower the I supersaturation following ion implantation. 74 In addition, a proper substitutional B concentration was demonstrated to suppress the typical {311} defects, by a competitive BIC formation. 75 The phenomenon of B-I clustering has a clear negative drawback as far as the dopant activation is concerned, but in addition, it has a weighty effect on the B diffusion process and on its simulation.…”

Section: B-i Clusters Formation and Dissolutionmentioning

confidence: 99%

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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“…[7][8][9] Nonequilibrium B diffusion and BIC formation have been the subject of many studies to control and suppress them. Different approaches have been proposed, [10][11][12][13][14] but a method suitable for both c-Si and PA-Si, that is also easily implemented in industrial Si-based device production, is still lacking.…”

Section: Introductionmentioning

confidence: 99%

He implantation to control B diffusion in crystalline and preamorphized Si

Bruno

Mirabella

Priolo

et al. 2008

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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We demonstrate that He can be a powerful tool to control B diffusion both in crystalline ͑c-Si͒ and preamorphized Si ͑PA-Si͒. By means of positron annihilation spectroscopy ͑PAS͒, we showed in He-implanted c-Si the formation after annealing of large open-volume defects at the implant projected range R p of He ͑voids͒ and of smaller vacancy-type defects toward the surface ͑nanovoids͒. In particular, these nanovoids locally suppress the amount of self-interstitials ͑Is͒ generated by B implantation, as verified by PAS, eventually reducing B diffusion and leading to a boxlike shape of the B-implanted profile. On the other hand, for B implantation in PA-Si, the authors demonstrated that if He-induced voids are formed between the end-of-range ͑EOR͒ defects and the surface, they act as a diffusion barrier for Is coming from the EOR defects. Indeed, this barrier strongly reduces diffusion of B placed in proximity of the surface.

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Role of C and B clusters in transient diffusion of B in silicon

Cited by 59 publications

References 6 publications

Diffusion Engineering by Carbon in Silicon

Diffusion Engineering by Carbon in Silicon

Mechanisms of boron diffusion in silicon and germanium

He implantation to control B diffusion in crystalline and preamorphized Si

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