On the manifestation of phosphorus-vacancy complexes in epitaxial Si:P films

Dhayalan, Sathish Kumar; Kujala, Janne V.; Slotte, Jonatan; Pourtois, Geoffrey; Simoen, Eddy; Rosseel, Erik; Hikavyy, Andriy; Shimura, Yosuke; Iacovo, Serena; Stesmans, André; Loo, Roger; Vandervorst, Wilfried

doi:10.1063/1.4942605

Cited by 21 publications

(29 citation statements)

References 21 publications

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“…7) are indeed negative (−0.16 eV and −0.6 eV). 27 Therefore, our finding suggests that from an energetic perspective, P n V clusters could be present both as monovacancies (P 4 V) and divacancies (P 6 V 2 ) in the Si:P lattice. Hence, P atoms are expected to form local nearest neighbor arrangements in the presence of vacancies.…”

Section: Understanding the Structure Of Si:p Filmsmentioning

confidence: 93%

“…The data points of the as-grown samples fall all on the same line. As we reported elsewhere, 27 using a high resolution CDOBS measurement technique enabled us to identify the chemical surroundings of the vacancies as well. It was deduced that vacancies were decorated with P atoms similar to P 4 V complexes, which were predicted in the Influence of vacancy on P arrangement section of this paper.…”

Section: Experimental Verification Of P 4 V Complexes Using Pasmentioning

confidence: 99%

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On the Evolution of Strain and Electrical Properties in As-Grown and Annealed Si:P Epitaxial Films for Source-Drain Stressor Applications

Dhayalan

Kujala

Slotte

et al. 2018

ECS J. Solid State Sci. Technol.

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Heavily P doped Si:P epitaxial layers have gained interest in recent times as a promising source-drain stressor material for n type FinFETs (Fin Field Effect Transistors). They are touted to provide excellent conductivity as well as tensile strain. Although the as-grown layers do provide tensile strain, their conductivity exhibits an unfavorable behavior. It reduces with increasing P concentration (P > 1E21 at/cm 3 ), accompanied by a saturation in the active carrier concentration. Subjecting the layers to laser annealing increases the conductivity and activates a fraction of P atoms. However, there is also a concurrent reduction in tensile strain (<1%). Literature proposes the formation of local semiconducting Si 3 P 4 complexes to explain the observed behaviors in Si:P [Z. Ye et al., ECS Trans., 50(9) 2013, p. 1007-1011. The development of tensile strain and the saturation in active carrier is attributed to the presence of local complexes while their dispersal on annealing is attributed to strain reduction and increase in active carrier density. However, the existence of such local complexes is not proven and a fundamental void exists in understanding the structure-property correlation in Si:P films. In this respect, our work investigates the reason behind the evolution of strain and electrical properties in the as-grown and annealed Si:P epitaxial layers using ab-initio techniques and corroborate the results with physical characterization techniques. It will be shown that the strain developed in Si:P films is not due to any specific complexes while the formation of Phosphorus-vacancy complexes will be shown responsible for the carrier saturation and the increase in resistivity in the as-grown films. Interstitial/precipitate formation is suggested to be a reason for the strain loss in the annealed films. The microelectronics industry is currently in the 14 nm node where 3 dimensional(3D) Si FinFET devices are already in production. Although new technologies and materials (e.g. Tunnel FETs, III-V channels, Ge channels etc.) have been proposed for the future transistor nodes, several technological and reliability challenges need to be overcome before those devices can be realized.1,2 Hence, the next couple of nodes (possibly up to 5 nm) may continue to be dominated by the Si FinFET technology. The performance of the Si FinFETs can be further scaled by the re-introduction of the source-drain S/D stressors that were first introduced in the 65 nm node for planar transistors. Typically, SiGe(B) S/D stressors that provide compressive stress are used for p type FinFETs 3 while Si:C(P) ones that provide tensile stress are for n-FinFETs. 4 Out of the two, the Si:C(P) stressors suffer from the problem of increasing resistivity with increasing C contents. 5,6 Subjecting the as-grown Si:C(P) layers to laser or spike annealing does not result in any significant improvement in the conductivity or carrier concentration. 5,6 Hence, instead of Si:C(P), heavily P doped Si:P films have gained prominent interest in recent times. ...

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Section: Understanding the Structure Of Si:p Filmsmentioning

confidence: 93%

Section: Experimental Verification Of P 4 V Complexes Using Pasmentioning

confidence: 99%

On the Evolution of Strain and Electrical Properties in As-Grown and Annealed Si:P Epitaxial Films for Source-Drain Stressor Applications

Dhayalan

Kujala

Slotte

et al. 2018

ECS J. Solid State Sci. Technol.

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“…At the same time, it will be shown that larger C-related clusters give rise to a deeper band of hole traps closer to the epitaxial interface. This can partly explain the observed loss in strain of the stressor layer after annealing [6], [13]. …”

Section: Resultsmentioning

confidence: 81%

Study of electrically active defects in epitaxial layers on silicon

Simoen

Dhayalan

Jayachandran

et al. 2016

2016 China Semiconductor Technology International Conference (CSTIC)

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Electrically active defects in silicon-based epitaxial layers on silicon substrates have been studied by Deep-Level Transient Spectroscopy (DLTS). Several aspects have been investigated, like, the impact of the pre-epi cleaning conditions and the effect of a post-deposition anneal on the deep-level properties. It is shown that the pre-cleaning thermal budget has a strong influence on the defects at the substrate/epi layer interface. At the same time, a post-deposition Forming Gas Anneal can passivate to a large extent the active defect states. Finally, it is shown that application of a post-deposition anneal increases the out-diffusion of carbon from a Si:C stressor layer into the p-type CZ substrate.

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“…The generation of free carriers requires achieving high concentration of electrically active dopants, typically controlled by doping and annealing techniques. The selective growth of in-situ doped epitaxial Si:P [1][2][3][4] is a major innovation that can significantly reduce source-drain external resistance and simultaneously act as stressor for advanced field effect transistor options beyond 3nm including gate-all-around (GAA) nanowire and FinFET devices. [5][6][7] The continuing device scaling demands for ever-increasing phosphorus concentration [P] in epitaxial Si:P. There has been significant efforts to increase phosphorus concentration [P] in epitaxial Si:P, and the highest [P] achieved nowadays is about 3x10 21 at./cm 3 by state-of-the-art epitaxial Si:P processes, virtually limited by its solid solubility.…”

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confidence: 99%

Achieving junction stability in heavily doped epitaxial Si:P

Tsai

Hsu

Santos

et al. 2021

Materials Science in Semiconductor Processing

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Junction stability and donor deactivation in silicon at high doping limit has been a longstanding issue in advanced semiconductor devices. Recently, heavily doped epitaxial Si:P layer with phosphorus concentrations as high as 3 x 10 21 at. /cm 3 has been employed in nanowire field-effect transistor (FET) devices for sub-3 nm technology node as low resistance sourcedrain and channel stressor. In such highly doped Si:P, the actual dopant activation is much less than nominal phosphorus concentration due to inactive phosphorus atoms arising from dopantvacancy defects (PnV) clustering phenomenon. Even with state-of-the-art high temperature millisecond annealing, this epitaxial film is thermally unstable upon subsequent thermal treatments. To overcome this limitation, we demonstrate a selective dopant activation scheme

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On the manifestation of phosphorus-vacancy complexes in epitaxial Si:P films

Cited by 21 publications

References 21 publications

On the Evolution of Strain and Electrical Properties in As-Grown and Annealed Si:P Epitaxial Films for Source-Drain Stressor Applications

On the Evolution of Strain and Electrical Properties in As-Grown and Annealed Si:P Epitaxial Films for Source-Drain Stressor Applications

Study of electrically active defects in epitaxial layers on silicon

Achieving junction stability in heavily doped epitaxial Si:P

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