Calculation of dopant segregation ratios at semiconductor interfaces

Ahn, Chi‐Hyung; Dunham, Scott T.

doi:10.1103/physrevb.78.195303

Cited by 9 publications

(9 citation statements)

References 34 publications

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“…From Fig.6, it can also be seen that the boron concentration in silicon substrate is high with the implantation energy of 60KeV. Because dopant segregation occurs until the chemical potential reaches the same value on both sides of interface [13], there will be a saturation value for the boron at the interface, with the redundant boron gradually diffusing into the silicon substrate. Thus, it can be expected that the dopants at the interface may finally saturate.…”

Section: Resultsmentioning

confidence: 89%

Design consideration of ion implantation in dopant segregation technique at NiSi/Si interface

Guo

Huang

et al. 2010

2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology

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The impacts of drive-in annealing and ion implantation process have been experimentally analyzed for the dopant segregation method by silicide as diffusion source, which provides the design guidelines for the application of dopant segregation technique. The results illustrate that the silicide as diffusion source technique is more sensitive to the ion implantation process. By optimizing the post-implantation energy, Schottky diodes of NiSi/n-Si with large I on /I off ratio up to 10 9 have been fabricated. The extracted electron Schottky barrier height increases to 0.92eV, which means a relative low hole Schottky barrier height of about 0.2eV, which is suitable for Schottky barrier source/drain PMOS fabrication.

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Section: Resultsmentioning

confidence: 89%

Design consideration of ion implantation in dopant segregation technique at NiSi/Si interface

Guo

Huang

et al. 2010

2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology

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“…However, in multilayered structures, the band offsets can build an electric potential causing dopant segregation. 12,13 Therefore, in such structures, changes in solubility are due not only to the stress effect but also to the band offsets.…”

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confidence: 98%

“…8,31 The temperature dependence of V 0 and C due to thermal expansion is ignored since they tend to compensate each other and the stress energy is nearly temperature independent. 13 Figure 2 shows the effects of biaxial stress on the equilibrium solubility of all common dopants in Si. A large enhancement in B solubility is possible under compressive strain.…”

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confidence: 99%

Stress effects on impurity solubility in crystalline materials: A general model and density-functional calculations for dopants in silicon

et al. 2009

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We present a general theory of stress effects on the solid solubility of impurities in crystalline materials, including the effects of ionization and the Fermi level in semiconductors. Critical errors and limitations in previously proposed theory are discussed, and a rigorous accurate treatment incorporating charge-carrierinduced lattice strain and correct statistics is presented. Considering all contributing effects, we find that the strain compensation energy is the primary contribution to solubility enhancement in essentially all material systems of interest. An exception is the case of low-solubility charged impurities in semiconductors, where a Fermi-level contribution is also found. We present explicit calculations for a range of dopant impurities in Si, utilizing this system as a model example and vehicle for comparison with experiment. Our results agree closely with experimental solubilities for dopants with widely different ionic sizes.The effect of stress on impurity solubility is one of the simplest examples of a mechanical effect on the phase diagram of a material system. It influences mechanical properties such as ductility 1 and crack evolution 2 electronic properties such as carrier density in semiconductors 3 and other phenomena, such as superconductivity. 4 Consequently it has a role to play in research topics ranging from materials science, geophysics, and superconductivity to semiconductor technology.Despite this very broad significance, our basic understanding of impurity solubility under stress is incomplete and no general physical model has yet emerged. In the case of dopant solubility in silicon, where the phenomenon has been closely studied, previously reported theoretical works have shown either inconsistencies 5,6 or important differences in formulation. 7-9 Until we understand the origin of these weaknesses it is uncertain whether solubility theory can be reliably applied to key technology problems, for example, dopant activation in nanoelectronic devices where high stress levels are introduced for band gap and mobility engineering, or stress-driven fracture 2 during the lifetime of critical engineering components. Moreover, since a small set of accurate experimental measurements has recently been reported for the case of impurities in Si, 3,10,11 it is especially worthwhile to develop an accurate comprehensive model to compare with these data and test theoretical understanding.Early theoretical work investigated stress-dependent B solubility in Si ͑Refs. 5 and 6͒ and suggested that the main contributing effect is a stress-induced change in the Fermi level. It was concluded that Fermi-level change produces a strong enhancement of B solubility in compressively strained silicon, while a relatively small additional enhancement occurs as a result of strain compensation arising from the size mismatch between B and Si. Adey et al. 6 later predicted that Fermi level and strain compensation contributions are both important in the case of As in Si but are of nearly equal magnitude and opposite i...

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“…The change in solubility with strain follows the same behavior since induced strain for inactive clusters is negligibly small. Note that there is also a contribution of band-offsets (built-in voltage) to segregation (but not solubility), which is small for acceptors such as B, but dominates segregation of donors [6]. stress on interstitial mediated diffusion varies strongly between dopants and is anisotropic for B, P and selfdiffusion.…”

Section: Diffusivitymentioning

confidence: 97%

“…Although, dopant/impurity binding has often been cited as basis for effect of alloy concentration on diffusion and segregation [5], we find that such direct binding effects between substitutional impurities are quite small (or repulsive) as listed in Table II and to a lesser extent band offsets [6]. The models of binding and strain energies over possible configurations can be used to derive activation as a function of Ge or C content.…”

Section: Segregation and Solubilitymentioning

confidence: 97%

Atomistic modeling of dopant diffusion and segregation in strained SiGeC

Dunham

Guo

Song

et al. 2008

2008 International Conference on Simulation of Semiconductor Processes and Devices

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In this work, density functional theory calculations are used to calculate the separate effects of stress/strain and chemical binding on diffusion, segregation and solubility of dopants in group IV alloy materials. Kinetic lattice Monte Carlo calculations are used to extract the effects of anisotropic stress and random alloy distributions. We find that segregation and solubility is dominated by stress effects, but that chemical interactions of Ge and C with point defects have a significant effect on diffusivity in SiGeC alloys.

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Calculation of dopant segregation ratios at semiconductor interfaces

Cited by 9 publications

References 34 publications

Design consideration of ion implantation in dopant segregation technique at NiSi/Si interface

Design consideration of ion implantation in dopant segregation technique at NiSi/Si interface

Stress effects on impurity solubility in crystalline materials: A general model and density-functional calculations for dopants in silicon

Atomistic modeling of dopant diffusion and segregation in strained SiGeC

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