An improved model for boron diffusion and activation in silicon

Kwok, Charlotte T. M.; Braatz, Richard D.; Paul, S.; Lerch, W.; Seebauer, Edmund G.

doi:10.1002/aic.11984

Cited by 4 publications

(8 citation statements)

References 41 publications

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“…24,41 In addition, it seems unlikely that the charge state of either B or Si interstitials would change under the conditions of these experiments. The rationale is as follows.…”

Section: Discussionmentioning

confidence: 97%

“…The temperature range of the experiments was 850-900 • C, and was chosen to permit the dissolution of most interstitials clusters over the time scale of the experiment yet without producing a concentration of thermally generated carriers sufficiently large to obscure photostimulation effects. 24 Given this constraint, the laser intensity was chosen as an optimum compromise between the two opposing criteria of maximizing the concentration of photogenerated carriers (via increased intensity) and minimizing the degree of thermal heating (via decreased intensity). Changes in defect charge state, and associated changes in dopant diffusion and activation behavior, occur when the minority carrier concentration rises substantially above the background concentration of thermally generated carriers.…”

Section: Methodsmentioning

confidence: 99%

“…24 Given this constraint, the laser intensity was chosen as an optimum compromise between the two opposing criteria of maximizing the concentration of photogenerated carriers (via increased intensity) and minimizing the degree of thermal heating (via decreased intensity). Changes in defect charge state, and associated changes in dopant diffusion and activation behavior, occur when the minority carrier concentration rises substantially above the background concentration of thermally generated carriers.…”

mentioning

confidence: 99%

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Interface-Mediated Photostimulation Effects on Diffusion and Activation of Boron Implanted into Silicon

Kondratenko

Seebauer

2013

ECS J. Solid State Sci. Technol.

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Recent work has demonstrated the existence of nonthermal illumination effects on the diffusion of boron, arsenic, and isotopic silicon ion-implanted into silicon for ultra-shallow junction applications. In some cases, the degree of electrical activation is affected as well. The effects arise from super-bandgap light's direct action on bulk point defects via changes in their charge state. By contrast, the present work demonstrates the existence of a distinct mechanism whereby light acts indirectly on bulk defects via changes at a nearby interface. The changes occur in interfacial annihilation probability and/or electric potential, and affect the efficiency with which the interface absorbs point defects emitted by extended end-of-range defects during annealing.Formation of shallow pn junctions for integrated circuits requires ion implantation of dopants followed by annealing to reduce implantation damage and to promote electrical activation of the dopants. Annealing technology relies upon rapid heating by incandescent lamps, flash lamps or lasers. 1 The optical stimulation was long thought to supply heating alone, although scattered experimental evidence had hinted at additional nonthermal influences on diffusion and activation of phosphorous, 2 arsenic, 3-5 and boron. 4,6-8 However, the experiments were difficult to interpret reliably because lamps supplied the heating, thereby complicating the decoupling of heating and photostimulation effects. Some progress was achieved in quantifying photoenhanced diffusion in II-VI semiconductors (using computational methods) 9 and a-Si:H (experimentally), 10 yet the understanding of the photostimulated dopant diffusion in c-Si remained inadequate. This laboratory has employed a novel experimental configuration to eliminate the ambiguity, and has thereby demonstrated the influences of low-intensity (<1 W/cm 2 ) super-bandgap illumination − first on the surface diffusion of various adsorbates on Si, 11,12 and subsequently on the bulk self-diffusion of Si 13,15 as well as the bulk diffusion and electrical activation of As and B implanted into silicon. 14 As first suggested for surface diffusion 11,12,15,16 and later modeled quantitatively for bulk Si self-diffusion, 13 photostimulation can influence diffusional flux rates by changing the average electrical charge state of point defects involved with diffusion, although the exact mechanism depends upon the specific case. For surface diffusion of Group III, IV and V elements on Si, the mass flux is carried by adatoms that can be rendered immobile by substitution into the top layer of the substrate. Escape from this substitutional state leaves behind a surface vacancy that can take on a variety of charge states depending upon the local concentrations of electrons and holes. Photostimulation exerts its influence by changing these carrier concentrations, which propagates into the average charge state of the vacancies, then into the effective formation energy for creating an adatom and vacancy, and finally into the concentration of ad...

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“…24,41 In addition, it seems unlikely that the charge state of either B or Si interstitials would change under the conditions of these experiments. The rationale is as follows.…”

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Interface-Mediated Photostimulation Effects on Diffusion and Activation of Boron Implanted into Silicon

Kondratenko

Seebauer

2013

ECS J. Solid State Sci. Technol.

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show abstract

“…In the same way, the present work shows that identification of injection (and annihilation) sites sometimes entails significant effort. Photoenhancements are possible as in catalysis, and microkinetic modeling is helpful, , but complications do arise from a complicated reaction network of defects in the bulk, especially in mixed-element materials, yet the comparative simplicity of the ZnO(0001) case offers hope that large surface-based defect engineering sometimes does follow a straightforward picture.…”

Section: Discussionmentioning

confidence: 99%

Surface-Based Control of Oxygen Interstitial Injection into ZnO via Submonolayer Sulfur Adsorption

Seebauer

2016

J. Phys. Chem. C

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Semiconductor surfaces offer efficient pathways for injecting native point defects into the underlying bulk. Adsorption of a suitably chosen foreign element serves to modulate the injection rate, even at small percentages of a monolayer. Through self-diffusion experiments using isotopic exchange with labeled oxygen, the present work demonstrates such behavior in the case of sulfur adsorption on c-axis Znterminated ZnO(0001), wherein the clean surface injects with exceptional efficiency. The experiments provide strong evidence that the injection sites comprise only a small fraction of the total surface atom density and that sulfur adsorption merely blocks those sites. Comparison with related systems shows this simple mechanism is surprisingly uncommon.

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“…16 Detailed reasoning can be found in Ref. 5. For spike and flash annealing, band bending was incorporated by setting the surface Fermi level at 0.4 eV above the valance band edge, in accord with the experimental value.…”

Section: Model Formulationmentioning

confidence: 99%

Mechanistic benefits of millisecond annealing for diffusion and activation of boron in silicon

Kwok

Braatz

Paul

et al. 2009

Journal of Applied Physics

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Millisecond annealing techniques with flash lamps or lasers have become increasingly common for activating dopants and eliminating implantation-induced damage after ion implantation for transistor junction formation in silicon. Empirical data show that such techniques confer significant benefits, but key physical mechanisms underlying these benefits are not well understood. The present work employs numerical simulation and analytical modeling to show that for boron, millisecond annealing reduces unwanted dopant spreading by greatly reducing the time for diffusion, which more than compensates for an increased concentration of Si interstitials that promote dopant spreading. Millisecond annealing also favorably alters the relative balance of boron interstitial sequestration by the crystal lattice vs interstitial clusters, which leads to improved electrical activation at depths just short of the junction.

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An improved model for boron diffusion and activation in silicon

Cited by 4 publications

References 41 publications

Interface-Mediated Photostimulation Effects on Diffusion and Activation of Boron Implanted into Silicon

Interface-Mediated Photostimulation Effects on Diffusion and Activation of Boron Implanted into Silicon

Surface-Based Control of Oxygen Interstitial Injection into ZnO via Submonolayer Sulfur Adsorption

Mechanistic benefits of millisecond annealing for diffusion and activation of boron in silicon

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