The Experts below are selected from a list of 1755 Experts worldwide ranked by ideXlab platform
Jan Vanhellemont - One of the best experts on this subject based on the ideXlab platform.
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impacts of thermal stress and doping on intrinsic point defect properties and clustering during single Crystal silicon and germanium growth from a melt
Journal of Crystal Growth, 2017Co-Authors: Jan Vanhellemont, Piotr Spiewak, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:Abstract This paper reviews recent considerable progress made in the last few years in understanding the behavior and properties of intrinsic point defects close to moving melt/solid Si interfaces during single Crystal Si growth from a melt. The so called Voronkov criterion allows to determine whether the grown Si Crystal is interstitial I - or vacancy V -rich. This criterion is written as the ratio Γ of the Pulling rate v over the thermal gradient G at the interface. Crystals pulled with Γ above a critical value Γ crit are vacancy-rich while below Γ crit , they are interstitial-rich. Various expressions based on the intrinsic point defect thermal equilibrium concentration and diffusivity have been proposed to calculate Γ crit and are briefly discussed in this paper. Recently it was shown that the thermal stress at the interface and heavy doping with neutral and/or electrically active impurities, have a considerable impact on the intrinsic point defect balance and thus also on Γ crit . Furthermore, high energy barriers of formation energies of I and V around three or four atom layers from (001) free surface support a model in which the boundary conditions of the point defect concentrations at the surface in simulations can be set at fixed values. The situation is quite different for Ge single Crystal Pulling where the vacancy is always the dominant intrinsic point defect so that the Voronkov criterion cannot be applied. Prediction of vacancy cluster concentration/size distributions as a function of the Pulling conditions is however still possible. The possibility of reaching Voronkov criterion conditions for Ge by doping with specific impurities is also discussed. Finally, impacts of stress and doping on self-diffusion in Si and Ge are evaluated with comparing the previous experimental results.
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theoretical study of the impact of stress and interstitial oxygen on the behavior of intrinsic point defects in growing czochralski si Crystals
Journal of Crystal Growth, 2017Co-Authors: Koji Sueoka, Kozo Nakamura, Jan VanhellemontAbstract:Abstract For the development of Crystal Pulling processes for 450 mm-diameter defect-free Si Crystals, it is important to evaluate the impact of thermal stress on intrinsic point defect behavior during Crystal growth. In a Crystal growing from a melt, the melt/solid interface can be considered as being stress-free. Due to that the thermal stress in the growing substrate near the interface is internal plane stress. Previously, we evaluated the impact of (001) planar-isotropic stress on the formation enthalpy ( H f ) of the vacancy ( V ) and the self-interstitial ( I ) using density functional theory (DFT) calculations, and explained quantitatively the published experimental values of the so-called “Voronkov criterion”. The thermal stress in a growing Crystal is indeed planar but is not isotropic in the plane except for the central region of the Crystal. The purpose of the present study is to estimate the impact of planar-anisotropic stress on the formation enthalpy H f of V and I . It is found that the three stress dependencies of σ x : σ y =1: 1 (planar-isotropic), 2: 1, 5: 1 (planar-anisotropic) are close to each other, independent of the assumption of isotropic or anisotropic planar stress. This is the reason why the experimental results obtained over the whole radial direction of the Crystal are well reproduced by the calculated results assuming planar-isotropic stress. A uniaxial stress dependence which is a good assumption for the Crystal peripheral region, leads also to results that are close to those for the planar stress dependence. Also the mechanisms behind the experimentally observed impact of interstitial oxygen (O i ), introduced during Czochralski Si growth, on V and I concentrations are clarified. DFT calculations are performed to obtain the formation energies ( E f ) of V and I at all sites within a sphere with 5 A radius around the O i atom. Formation (vibration) entropy ( S f ) calculations for V and I are also performed. It is found that both E f V and S f V of V in the zigzag-bond (1st, 2nd, 5th) including the Oi atom decrease while E f I of I is not affected by the Oi atom. “Total V ” is defined as the sum of free V and V trapped by the Oi atoms. The total V concentration at the melting point is evaluated by considering the E f V and S f V at each site. The calculated V concentration increases by about 2.9% with 1×10 18 O i cm −3 and agrees well with the experimentally estimated value of a few % increase with 1×10 18 O i cm −3 .
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Intrinsic point defect behavior close to silicon melt/solid interface
2015 China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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intrinsic point defect behavior close to silicon melt solid interface
China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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theoretical study of the impact of stress on the behavior of intrinsic point defects in large diameter defect free si Crystals
Solid State Phenomena, 2013Co-Authors: Koji Sueoka, Eiji Kamiyama, Jan VanhellemontAbstract:For the development of the Crystal Pulling process for 450 mm-diameter defect-free Si Crystals, the impact of thermal stress on intrinsic point defect behavior during Crystal growth is studied using extensive density functional theory calculations. The impact of thermal stress on the so-called Voronkov criterion and on void formation is clarified and compared with published experimental results.
Koji Sueoka - One of the best experts on this subject based on the ideXlab platform.
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impacts of thermal stress and doping on intrinsic point defect properties and clustering during single Crystal silicon and germanium growth from a melt
Journal of Crystal Growth, 2017Co-Authors: Jan Vanhellemont, Piotr Spiewak, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:Abstract This paper reviews recent considerable progress made in the last few years in understanding the behavior and properties of intrinsic point defects close to moving melt/solid Si interfaces during single Crystal Si growth from a melt. The so called Voronkov criterion allows to determine whether the grown Si Crystal is interstitial I - or vacancy V -rich. This criterion is written as the ratio Γ of the Pulling rate v over the thermal gradient G at the interface. Crystals pulled with Γ above a critical value Γ crit are vacancy-rich while below Γ crit , they are interstitial-rich. Various expressions based on the intrinsic point defect thermal equilibrium concentration and diffusivity have been proposed to calculate Γ crit and are briefly discussed in this paper. Recently it was shown that the thermal stress at the interface and heavy doping with neutral and/or electrically active impurities, have a considerable impact on the intrinsic point defect balance and thus also on Γ crit . Furthermore, high energy barriers of formation energies of I and V around three or four atom layers from (001) free surface support a model in which the boundary conditions of the point defect concentrations at the surface in simulations can be set at fixed values. The situation is quite different for Ge single Crystal Pulling where the vacancy is always the dominant intrinsic point defect so that the Voronkov criterion cannot be applied. Prediction of vacancy cluster concentration/size distributions as a function of the Pulling conditions is however still possible. The possibility of reaching Voronkov criterion conditions for Ge by doping with specific impurities is also discussed. Finally, impacts of stress and doping on self-diffusion in Si and Ge are evaluated with comparing the previous experimental results.
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theoretical study of the impact of stress and interstitial oxygen on the behavior of intrinsic point defects in growing czochralski si Crystals
Journal of Crystal Growth, 2017Co-Authors: Koji Sueoka, Kozo Nakamura, Jan VanhellemontAbstract:Abstract For the development of Crystal Pulling processes for 450 mm-diameter defect-free Si Crystals, it is important to evaluate the impact of thermal stress on intrinsic point defect behavior during Crystal growth. In a Crystal growing from a melt, the melt/solid interface can be considered as being stress-free. Due to that the thermal stress in the growing substrate near the interface is internal plane stress. Previously, we evaluated the impact of (001) planar-isotropic stress on the formation enthalpy ( H f ) of the vacancy ( V ) and the self-interstitial ( I ) using density functional theory (DFT) calculations, and explained quantitatively the published experimental values of the so-called “Voronkov criterion”. The thermal stress in a growing Crystal is indeed planar but is not isotropic in the plane except for the central region of the Crystal. The purpose of the present study is to estimate the impact of planar-anisotropic stress on the formation enthalpy H f of V and I . It is found that the three stress dependencies of σ x : σ y =1: 1 (planar-isotropic), 2: 1, 5: 1 (planar-anisotropic) are close to each other, independent of the assumption of isotropic or anisotropic planar stress. This is the reason why the experimental results obtained over the whole radial direction of the Crystal are well reproduced by the calculated results assuming planar-isotropic stress. A uniaxial stress dependence which is a good assumption for the Crystal peripheral region, leads also to results that are close to those for the planar stress dependence. Also the mechanisms behind the experimentally observed impact of interstitial oxygen (O i ), introduced during Czochralski Si growth, on V and I concentrations are clarified. DFT calculations are performed to obtain the formation energies ( E f ) of V and I at all sites within a sphere with 5 A radius around the O i atom. Formation (vibration) entropy ( S f ) calculations for V and I are also performed. It is found that both E f V and S f V of V in the zigzag-bond (1st, 2nd, 5th) including the Oi atom decrease while E f I of I is not affected by the Oi atom. “Total V ” is defined as the sum of free V and V trapped by the Oi atoms. The total V concentration at the melting point is evaluated by considering the E f V and S f V at each site. The calculated V concentration increases by about 2.9% with 1×10 18 O i cm −3 and agrees well with the experimentally estimated value of a few % increase with 1×10 18 O i cm −3 .
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Intrinsic point defect behavior close to silicon melt/solid interface
2015 China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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intrinsic point defect behavior close to silicon melt solid interface
China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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theoretical study of the impact of stress on the behavior of intrinsic point defects in large diameter defect free si Crystals
Solid State Phenomena, 2013Co-Authors: Koji Sueoka, Eiji Kamiyama, Jan VanhellemontAbstract:For the development of the Crystal Pulling process for 450 mm-diameter defect-free Si Crystals, the impact of thermal stress on intrinsic point defect behavior during Crystal growth is studied using extensive density functional theory calculations. The impact of thermal stress on the so-called Voronkov criterion and on void formation is clarified and compared with published experimental results.
Eiji Kamiyama - One of the best experts on this subject based on the ideXlab platform.
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impacts of thermal stress and doping on intrinsic point defect properties and clustering during single Crystal silicon and germanium growth from a melt
Journal of Crystal Growth, 2017Co-Authors: Jan Vanhellemont, Piotr Spiewak, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:Abstract This paper reviews recent considerable progress made in the last few years in understanding the behavior and properties of intrinsic point defects close to moving melt/solid Si interfaces during single Crystal Si growth from a melt. The so called Voronkov criterion allows to determine whether the grown Si Crystal is interstitial I - or vacancy V -rich. This criterion is written as the ratio Γ of the Pulling rate v over the thermal gradient G at the interface. Crystals pulled with Γ above a critical value Γ crit are vacancy-rich while below Γ crit , they are interstitial-rich. Various expressions based on the intrinsic point defect thermal equilibrium concentration and diffusivity have been proposed to calculate Γ crit and are briefly discussed in this paper. Recently it was shown that the thermal stress at the interface and heavy doping with neutral and/or electrically active impurities, have a considerable impact on the intrinsic point defect balance and thus also on Γ crit . Furthermore, high energy barriers of formation energies of I and V around three or four atom layers from (001) free surface support a model in which the boundary conditions of the point defect concentrations at the surface in simulations can be set at fixed values. The situation is quite different for Ge single Crystal Pulling where the vacancy is always the dominant intrinsic point defect so that the Voronkov criterion cannot be applied. Prediction of vacancy cluster concentration/size distributions as a function of the Pulling conditions is however still possible. The possibility of reaching Voronkov criterion conditions for Ge by doping with specific impurities is also discussed. Finally, impacts of stress and doping on self-diffusion in Si and Ge are evaluated with comparing the previous experimental results.
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Intrinsic point defect behavior close to silicon melt/solid interface
2015 China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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intrinsic point defect behavior close to silicon melt solid interface
China Semiconductor Technology International Conference, 2015Co-Authors: Jan Vanhellemont, Eiji Kamiyama, Kozo Nakamura, Koji SueokaAbstract:The impact of various Crystal Pulling process and silicon material parameters on the so called Voronkov criterion for “perfect” Crystal Pulling is revised. It is shown that thermal stress effects should be taken into account in particular for the development of the 450 mm diameter single Crystal silicon Pulling technology. An improved Voronkov criterion is proposed and its application illustrated showing that all published experimental results on grown-in defects dependence on doping and Crystal Pulling conditions can be explained at least semi-quantitatively.
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theoretical study of the impact of stress on the behavior of intrinsic point defects in large diameter defect free si Crystals
Solid State Phenomena, 2013Co-Authors: Koji Sueoka, Eiji Kamiyama, Jan VanhellemontAbstract:For the development of the Crystal Pulling process for 450 mm-diameter defect-free Si Crystals, the impact of thermal stress on intrinsic point defect behavior during Crystal growth is studied using extensive density functional theory calculations. The impact of thermal stress on the so-called Voronkov criterion and on void formation is clarified and compared with published experimental results.
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theoretical study of the impact of stress on the behavior of intrinsic point defects in large diameter defect free si Crystals
Journal of Crystal Growth, 2013Co-Authors: Koji Sueoka, Eiji Kamiyama, Jan VanhellemontAbstract:Abstract For the development of the Crystal Pulling process for 450 mm-diameter defect-free Si Crystals, it is important to evaluate the impact of thermal stress on intrinsic point defect behavior during Crystal growth. In this study, we evaluated the impact of thermal stress between −30 MPa (tensile) and 30 MPa (compressive), which covers the complete range of stress levels that can be expected in mass production for 450 mm-diameter Crystals, on the so-called Voronkov criterion. This criterion predicts the dominant point defect based on a critical Pulling speed over axial temperature gradient ratio. The internal pressure dependencies of both the formation and the migration enthalpies of intrinsic point defects were obtained with a density functional theory study, and it was found that assuming internal stress only, the thermal stress shifts the growing Si Crystal towards more vacancy-rich under compressive and towards more self-interstitial-rich under tensile stresses. Also Si Crystals containing interstitial clusters and heavily doped Crystals were studied to evaluate the effect of thermal and dopant-related stresses on the intrinsic point defect formation and diffusivity. It was concluded that the experimentally observed increase in the number of interstitial clusters and the increase in the concentration of self-interstitials in heavily doped Si cannot be explained by the thermal and/or dopant-related stresses.
Koichi Kakimoto - One of the best experts on this subject based on the ideXlab platform.
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transient global modeling for the Pulling process of czochralski silicon Crystal growth ii investigation on segregation of oxygen and carbon
Journal of Crystal Growth, 2020Co-Authors: Xin Liu, H Harada, Yoshiji Miyamura, Xue Feng Han, Satoshi Nakano, Shinichi Nishizawa, Koichi KakimotoAbstract:Abstract We conducted the transient global simulations for the Crystal Pulling process of Czochralski silicon (CZ-Si) growth with the cusp-shaped magnetic field (CMF). The generation, transport, and segregation of oxygen (O) were considered for the Crystal growing process. Further, the incorporation, accumulation, and segregation of carbon (C) were also predicted based on our previous studies on CZ-Si growth. The distributions of O and C at the growth interface were dynamically predicted for the diameter Pulling stages, and their segregations were plotted as a function of solidified fraction and Crystal length. The O level and uniformities at the growth interface exhibit a strong correlation with the depth of melt in the crucible and the flow structures inside the melt. The comparisons of different CMFs indicated that adjustments of the zero-Gauss plane (ZGP) have the potential to optimize the O segregation into the Pulling Crystal from the level, axial, and radial uniformities. Further, the C concentration increased with the increase in the Crystal length because of the continuous contamination and the lower segregation coefficient. Hence, the developed dynamic global model also has applications in the segregation prediction of other dopants and impurities in the CZ-Si growing process.
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transient global modeling for the Pulling process of czochralski silicon Crystal growth i principles formulation and implementation of the model
Journal of Crystal Growth, 2020Co-Authors: Xin Liu, H Harada, Yoshiji Miyamura, Xue Feng Han, Satoshi Nakano, Shinichi Nishizawa, Koichi KakimotoAbstract:Abstract A transient global model for the Crystal Pulling process was developed for magnetic-field-applied Czochralski silicon (CZ-Si) growth. Heat transfer by solid conduction, melt convection, and diffuse gray radiation is taken into account for the Crystal, melt, and other components in the furnace. The mesh adaption and view factor updating for the dynamic Pulling process were realized by the structured grid deformations for different domains. By imposing the thermal boundary conditions in the vicinity of the triple point, the inverse control by the virtual proportional integral derivative controller and heat flux is acceptable for the transient global simulation of the Pulling process in CZ-Si Crystal growth. The applied cusp-shaped magnetic field (CMF) suppressed the turbulent melt flow and stabilized the heat and mass transport. CMF with different zero-Gauss-plane locations resulted in different flow patterns, which could affect the impurity transport during the Pulling process. This developed transient global model can be applied for the segregation predictions of impurities (oxygen and carbon) and dopants in the CZ-Si growing process.
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an analysis of temperature distribution near the melt Crystal interface in silicon czochralski growth with a transverse magnetic field
Journal of Crystal Growth, 2005Co-Authors: Lijun Liu, Satoshi Nakano, Koichi KakimotoAbstract:A three-dimensional (3D) global analysis was carried out numerically for a small silicon Czochralski furnace in a transverse magnetic field to clarify temperature distribution near a melt–Crystal interface. The melt–Crystal interface shape and the axial temperature gradients in solid and liquid near the interface were calculated as functions of the magnetic field intensity and the Pulling rate of a Crystal. It was found that the axial temperature gradient in the Crystal increases with increase in the Crystal-Pulling rate and that in the melt decreases near the interface. With increase in intensity of the magnetic field, the axial temperature gradients in both Crystal and melt increase. The influence of melt convection becomes smaller with increase in either the magnetic field intensity or the Crystal-Pulling rate. The melt–Crystal interface moves upward with increase in either the ratio between Crystal-Pulling rate and temperature gradient in the Crystal or the intensity of the applied magnetic field.
Werner Zulehner - One of the best experts on this subject based on the ideXlab platform.
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historical overview of silicon Crystal Pulling development
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2000Co-Authors: Werner ZulehnerAbstract:Abstract The first silicon single Crystals were grown by crucible Pulling in 1950, 2 years after the invention of the transistor, which was first made from germanium. Two years later, the crucible-free float zone Pulling was invented. In this stage, the low purity of the starting polysilicon for the Crystal Pulling was the biggest problem. A great help in the purification of polysilicon were the very low distribution coefficients of most of the impurities. This effect was used in the refining of silicon by repeated crucible-free zone melting (zone refining). However, boron cannot be sufficiently removed by this technique. Since 1961, the raw silicon is first transformed into a silane, then the silane is purified by distillation and adsorption, and finally retransformed to elemental silicon by chemical vapor deposition. This purification technique yields a polysilicon that needs no further purification by zone refining. A big step forward was the invention of the dislocation-free Crystal growth in 1958, an absolute necessity for the manufacturing of highly integrated devices. The first Crystals were small with about 0.5′′ diameter and about 100 g weight. Predominantly for economical reasons, the size of the crucible pulled Crystals increased stepwise about every 4 years to 12′′ diameter (for 300 mm wafers) and to 250 kg in weight until today. The maximum diameter of float zone grown Crystals is only 6′′ at present, because there was no need for larger float zone-Si diameters in the past. But this has changed recently.