Diffusion, activation, and regrowth behavior of high dose P implants in Ge

Satta, Alessandra; Simoen, Eddy; Duffy, Ray; Janssens, Tom; Clarysse, Trudo; Benedetti, Alessandro; Meuris, Marc; Vandervorst, Wilfried

doi:10.1063/1.2196227

Cited by 98 publications

(70 citation statements)

References 17 publications

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“…1 Whereas a p-channel Ge-MOSFET made of heavily boron ͑B͒ doped source and drain regions have already been demonstrated, 2,3 the n-channel MOSFET remains a challenge due to the enhanced diffusion of n-type dopants under extrinsic doping conditions and the deactivation of the donors for concentrations exceeding 10 19 cm −3 . [3][4][5][6][7] The enhanced diffusion and deactivation are directly associated with the properties of the point defects involved in the diffusion mechanisms. 6,7 In the case of phosphorus ͑P͒, arsenic ͑As͒, and antimony ͑Sb͒ diffusion in Ge, the mass transport is mediated by singly negatively charged donor-vacancy pairs.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic and extrinsic diffusion of indium in germanium

Kube

Bracht

Chroneos

et al. 2009

Journal of Applied Physics

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Diffusion experiments with indium ͑In͒ in germanium ͑Ge͒ were performed in the temperature range between 550 and 900°C. Intrinsic and extrinsic doping levels were achieved by utilizing various implantation doses. Indium concentration profiles were recorded by means of secondary ion mass spectrometry and spreading resistance profiling. The observed concentration independent diffusion profiles are accurately described based on the vacancy mechanism with a singly negatively charged mobile In-vacancy complex. In accord with the experiment, the diffusion model predicts an effective In diffusion coefficient under extrinsic conditions that is a factor of 2 higher than under intrinsic conditions. The temperature dependence of intrinsic In diffusion yields an activation enthalpy of 3.51 eV and confirms earlier results of Dorner et al. ͓Z. Metallk. 73, 325 ͑1982͔͒. The value clearly exceeds the activation enthalpy of Ge self-diffusion and indicates that the attractive interaction between In and a vacancy does not extend to third nearest neighbor sites which confirms recent theoretical calculations. At low temperatures and high doping levels, the In profiles show an extended tail that could reflect an enhanced diffusion at the beginning of the annealing.

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Section: Introductionmentioning

confidence: 99%

Intrinsic and extrinsic diffusion of indium in germanium

Kube

Bracht

Chroneos

et al. 2009

Journal of Applied Physics

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“…2 This is particularly important for donor impurities for which activation control can be problematic. 3 In previous studies, it has been concluded that most impurities mainly occupy substitutional lattice sites in Ge and, with the exception of boron ͑B͒, dopant diffusion is mainly mediated by vacancies ͑V͒ as interstitial mechanisms typically have significantly higher activation enthalpies. 2, Aluminium ͑Al͒, gallium ͑Ga͒, indium ͑In͒, and B are acceptor atoms that can potentially be used as p-type dopants in Ge technology.…”

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confidence: 99%

Vacancy-mediated dopant diffusion activation enthalpies for germanium

Chroneos

Bracht

Grimes

et al. 2008

Applied Physics Letters

135

113

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Electronic structure calculations are used to predict the activation enthalpies of diffusion for a range of impurity atoms ͑aluminium, gallium, indium, silicon, tin, phosphorus, arsenic, and antimony͒ in germanium. Consistent with experimental studies, all the impurity atoms considered diffuse via their interaction with vacancies. Overall, the calculated diffusion activation enthalpies are in good agreement with the experimental results, with the exception of indium, where the most recent experimental study suggests a significantly higher activation enthalpy. Here, we predict that indium diffuses with an activation enthalpy of 2.79 eV, essentially the same as the value determined by early radiotracer studies. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2918842͔ Germanium ͑Ge͒ has the potential to replace silicon ͑Si͒ in advanced nanoelectronic devices because of the higher mobility of holes and electrons, compatibility with Si manufacturing processes, increased dopant solubility, and smaller band gap. 1 The precise control required for the fabrication of these devices would be greatly aided by an accurate determination of the diffusion properties of impurities in Ge. 2 This is particularly important for donor impurities for which activation control can be problematic. 3 In previous studies, it has been concluded that most impurities mainly occupy substitutional lattice sites in Ge and, with the exception of boron ͑B͒, dopant diffusion is mainly mediated by vacancies ͑V͒ as interstitial mechanisms typically have significantly higher activation enthalpies. 2, Aluminium ͑Al͒, gallium ͑Ga͒, indium ͑In͒, and B are acceptor atoms that can potentially be used as p-type dopants in Ge technology. Recent experiments 4 on B diffusion in Ge yield an activation enthalpy of 4.65 eV that agrees with earlier results, but the absolute values of the B diffusion coefficients are several orders of magnitude lower than those reported earlier. 5 Previous experimental studies on Al diffusion yield activation enthalpies in the range of 3.2-3.45 eV. 6,7 Södervall et al. 8 obtained an activation enthalpy of 3.31 eV for Ga diffusion in Ge. This value is supported by the more recent experimental studies of Riihimäki et al. 9 who determined an activation enthalpy of 3.21 eV for Ga diffusion in Ge via a V-mediated mechanism. The spread in the data reported for the activation enthalpy of In diffusion in Ge is especially large ͑0.85 eV͒. The radiotracer studies of Pantaleev 10 suggest a value of 2.78 eV, whereas the In profiles measured by Dorner et al. 11 by means of secondary ion mass spectrometry ͑SIMS͒ yield a value of 3.63 eV.Carbon ͑C͒, Si, and tin ͑Sn͒ are important isovalent impurities. C atoms have been observed to be relatively immobile; however, they can retard the diffusion of phosphorus ͑P͒, arsenic ͑As͒, and antimony ͑Sb͒ atoms in Ge. 26,27 Recent experimental studies by Silvestri et al. 15 ͑using SIMS͒ concluded that Si diffusion in Ge is mediated by V with an activation enthalpy of 3.32 eV, whereas previous studies ...

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“…[6][7][8][9] Quantifying the expected diffusion is difficult as available diffusivity values were either extracted under intrinsic conditions, or at higher temperatures than studied here. 1 However, extrapolating diffusivity values from Chui et al, 6 which are accurate for high concentrations, only a few nanometers of diffusion could be expected for the highest thermal budgets in this work.…”

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confidence: 99%

“…n-type dopants in germanium have proven to be problematic, and are now a key bottleneck in the realization of advanced n-type MOS ͑NMOS͒ device performance and scaling. 5 In short, phosphorus ͑P͒ and arsenic ͑As͒ are relatively difficult to activate and diffuse quickly, [6][7][8][9] leading to high resistances and limited capability to reduce the device dimensions.…”

mentioning

confidence: 99%

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

Duffy

Shayesteh

White

et al. 2010

Applied Physics Letters

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Design and optimization of n-type doped regions in germanium by solid phase epitaxial recrystallization (SPER) have been studied by the authors. A systematic study is presented of process variables that influence activation and thermal stability, including preamorphization, coimplants, recrystallization temperature, and postrecrystallization thermal treatments. Unlike silicon, activation after recrystallization in germanium is not optimum where the postrecrystallization thermal budget is kept to a minimum. With the aid of modeling, a maximum peak activation of 7 X 10(19) cm(-3) was extracted. A steady increase in sheet resistance during postrecrystallization anneals confirms the formation of metastable activation by SPER. It is predicted that active concentrations of 6-8 X 10(19) cm(-3) are sufficient to meet targets for sub-20 nm technologies. (C) 2010 American Institute of Physics. (doi: 10.1063/1.3452345

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Diffusion, activation, and regrowth behavior of high dose P implants in Ge

Cited by 98 publications

References 17 publications

Intrinsic and extrinsic diffusion of indium in germanium

Intrinsic and extrinsic diffusion of indium in germanium

Vacancy-mediated dopant diffusion activation enthalpies for germanium

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

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