Effect of pressure on the solid phase epitaxial regrowth rate of Si

Nygren, E.; Aziz, Michael J.; Turnbull, David; Poate, J. M.; Jacobson, D. C.; Hull, R.

doi:10.1063/1.96228

Cited by 44 publications

(19 citation statements)

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“…The average value of ∆V* is -3.3 ± 0.3 cm 3 /mol, which is about -28% of Ω Si . This negative activation volume agrees qualitatively but not quantitatively with that of Nygren et al 40 , who found a value of roughly -70% Ω Si for the same process. They used a piston cylinder apparatus with solid NaCl as the pressure transmission medium to generate pressures up to 2.0 GPa and used Rutherford backscattering spectrometry (RBS) and ion-channeling techniques to measure the growth rates.…”

Section: Pressure-enhanced Speg Of Gesupporting

confidence: 81%

Pressure-enhanced crystallization kinetics of amorphous Si and Ge: Implications for point-defect mechanisms

Lü

Nygren

Aziz

1991

Journal of Applied Physics

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152

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The effects of hydrostatic pressure on the solid-phase epitaxial growth (SPEG) rate v of intrinsic Ge(100) and undoped and doped Si(100) into their respective self-implanted amorphous phases are reported. Samples were annealed in a high-temperature, high-pressure diamond anvil cell. Cryogenically loaded fluid Ar, used as the pressure transmission medium, ensured a clean and hydrostatic environment. v was determined by in situ time-resolved visible (for Si) or infrared (for Ge) interferometry. v increased exponentially with pressure, characterized by a negative activation volume of −0.46Ω in Ge, where Ω is the atomic volume, and −0.28Ω in Si. The activation volume in Si is independent of both dopant concentration and dopant type. Structural relaxation of the amorphous phases has no significant effect on v. These and other results are inconsistent with all bulk point-defect mechanisms, but consistent with all interface point-defect mechanisms, proposed to date. A kinetic analysis of the Spaepen–Turnbull interfacial dangling bond mechanism is presented, assuming thermal generation of dangling bonds at ledges along the interface, independent migration of the dangling bonds along the ledges to reconstruct the network from the amorphous to the crystalline structure, and unimolecular annihilation kinetics at dangling bond ‘‘traps.’’ The model yields v = 2 sin(θ)vsnr exp[(ΔSf + ΔSm)/k] exp− [(ΔHf + ΔHm)/kT], where ΔSf and ΔHf are the standard entropy and enthalpy of formation of a pair of dangling bonds, ΔSm and ΔHm are the entropy and enthalpy of motion of a dangling bond at the interface, vs is the speed of sound, θ is the misorientation from {111}, and nr is the net number of hops made by a dangling bond before it is annihilated. It accounts semiquantitatively for the measured prefactor, orientation dependence, activation energy, and activation volume of v, and the pressure of a ‘‘free-energy catastrophe’’ beyond which the exponential pressure enhancement of SPEG cannot continue uninterrupted due to a vanishing barrier to dangling bond migration. The enhancement of v by doping can be accounted for by an increased number of charged dangling bonds, with no change in the number of neutrals, at the interface. Quantitative models for the doping dependence of v are critically reviewed. At low concentrations the data can be accounted for by either the fractional ionization or the generalized Fermi-level-shifting models; methods to further test these models are enumerated. Ion irradiation may affect v by altering the populatio

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Section: Pressure-enhanced Speg Of Gesupporting

confidence: 81%

Pressure-enhanced crystallization kinetics of amorphous Si and Ge: Implications for point-defect mechanisms

Lü

Nygren

Aziz

1991

Journal of Applied Physics

Self Cite

152

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“…2,3 Early investigations revealed exponential enhancement of the ͓001͔ SPE using hydrostatic pressure while subsequent investigations revealed uniaxial stress in the plane of the regrowing ␣/crystalline interface caused smaller changes to SPE rates. [4][5][6] In-plane compression also caused significant roughening of the regrowing ␣/crystalline interface. 7 This is significant since interfacial roughening is known to cause SPE-related defect formation.…”

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confidence: 99%

Solid phase epitaxy in uniaxially stressed (001) Si

Rudawski

Jones

Gwilliam

2007

Applied Physics Letters

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The effect of ͓110͔ uniaxial stresses up to 1.5 GPa on defect nucleation during solid phase epitaxy of amorphous ͑001͒ Si created via ion implantation was examined. The solid phase epitaxial regrowth velocity was slowed in compression. However, in tension, the velocity was unaffected. Both compression and tension resulted in an increase in regrowth defects compared to the stress-free case. The defects in compression appear to arise from roughening of the crystallizing interface whereas in tension it is proposed that reorientation of crystallites near the initial amorphous/ crystalline interface is responsible for defect formation. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2801518͔ Solid phase epitaxy ͑SPE͒ in amorphous ͑␣͒ Si created via ion implantation produces enhanced dopant activation and shallower junctions. 1 However, stresses found during typical device fabrication may influence the SPE process. 2,3 Early investigations revealed exponential enhancement of the ͓001͔ SPE using hydrostatic pressure while subsequent investigations revealed uniaxial stress in the plane of the regrowing ␣/crystalline interface caused smaller changes to SPE rates. [4][5][6] In-plane compression also caused significant roughening of the regrowing ␣/crystalline interface. 7 This is significant since interfacial roughening is known to cause SPE-related defect formation. 8,9 However, while BarvosaCarter et al. 7 quantified and modeled the roughness of the regrowing interface, they did not quantify the resulting defects or examine tensile stresses. Furthermore, the stresses used were fairly small in magnitude ͑Ͻ0.5 GPa͒ and the stresses present in Si-based technology can be ϳ1 GPa or more. 2 Thus, the goal of this study is to examine the effect of very high uniaxial ͓110͔ stresses on SPE in ͑001͒ Si.For this study, 50-m-thick polished ͑001͒ Si wafers were used. The specimens were first Si + implanted at 50 and 200 keV with doses of 1.0ϫ 10 15 cm −2 and subsequently As + implanted at 300 keV to a dose of 1.8ϫ 10 15 cm −2 . Samples were cleaved along ͗110͘ directions into ϳ0.3ϫ 1.8 cm 2 strips. Stress was applied by bending and inserting the strips into slots in a quartz tray spaced ϳ1.5 cm apart. A Philtec laser displacement measurement system accurate to 1 m measured the local radius of curvature along the strips. The bent strips were symmetric and parabolic in shape with the smallest radius of curvature at midlength. The ͓110͔ stress ͑ ͓110͔ ͒ was calculated using the ͓110͔ Young's modulus of Si near ϳ500°C ͑ϳ1.61ϫ 10 11 Pa͒, the wafer halfthickness, and the local radius of curvature as presented elsewhere. 10,11 Maximum repeatable stresses of 1.5± 0.1 GPa were attained. Specimens were annealed at 525°C in N 2 ambient for 0.7-3.2 h. Stress-free, tensile, and compressive specimens were annealed simultaneously for each anneal time. Upon removal from the quartz tray after annealing, the specimens exhibited no detectable radii of curvature ͑ӷ2.0 m͒ indicating no measurable plastic strain. Regrowth of the ␣-Si layers was ex...

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“…The study of stressed solid-solid phase transformations has been a topic of fundamental and technological importance for several years [1][2][3]. However, there are inconsistencies between understanding the atomistic nature of solid-solid phase transformations and the current model of stress-dependent growth.…”

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confidence: 99%

“…Hence, it is assumed V ij V n ij V m ij , where V n ij and V m ij are the activation strain tensors associated with nucleation and migration processes [6]. The use of V ij is accepted for stressed solid phase epitaxial growth (SPEG) of (001) Si amorphized via ion-implantation [1,6,9,10]. However, using new results of stressed SPEG of (001) Si as a model system, a model of stressed solid-solid phase transformations is advanced which isolates the nucleation and migration processes.…”

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confidence: 99%

Kinetics and Morphological Instabilities of Stressed Solid-Solid Phase Transformations

Gwilliam³

2008

Phys. Rev. Lett.

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An atomistic model of the growth kinetics of stressed solid-solid phase transformations is presented. Solid phase epitaxial growth of (001) Si was used for comparison of new and prior models with experiments. The results indicate that the migration of crystal island ledges in the growth interface may involve coordinated atomic motion. The model accounts for morphological instabilities during stressed solid-solid phase transformations. DOI: 10.1103/PhysRevLett.100.165501 PACS numbers: 61.72.uf, 61.43.Dq, 68.55.Aÿ The study of stressed solid-solid phase transformations has been a topic of fundamental and technological importance for several years [1][2][3]. However, there are inconsistencies between understanding the atomistic nature of solid-solid phase transformations and the current model of stress-dependent growth. Current atomistic theory suggests growth occurs via nucleation of two-dimensional crystal islands of the growing phase with subsequent migration of island ledges in the interface between the two phases [4,5]. However, the current stress-dependent growth model does not address this and assumes growth occurs via a single, unspecified atomistic process [6]. In this Letter, a model of stress-dependent growth is presented to account for new experimental observations of stress-dependent growth kinetics in conjunction with the current understanding of the atomistic nature of growth.The current model used to describe the influence of a stress state, ij , on the macroscopic velocity, v, of an advancing growth interface is given by the activation strain tensor, V ij kT@ lnv=@ ij , given bywhere v0 is the stress-free velocity, kT has the usual meaning, and i and j refer to axes in the coordinate frame of reference [6]. By convention, 1 and 2 are the in-plane directions, 3 is the growth direction, and positive (negative) elements of ij are tensile (compressive). The basis for Eq. (1) is the observation that for many solid-solid phase transformations, v0 v 0 expÿG =kT over a wide temperature range where v 0 is a temperature-independent prefactor and G is the activation energy for macroscopic growth as given by transition state theory (TST) [7,8]. However, Eq. (1) assumes a single, unspecified atomistic process is responsible for growth thus contradicting current understanding of solid-solid phase transformations [4,5]. Hence, it is assumed V ij V n ij V m ij , where V n ij and V m ij are the activation strain tensors associated with nucleation and migration processes [6]. The use of V ij is accepted for stressed solid phase epitaxial growth (SPEG) of (001) Si amorphized via ion-implantation [1,6,9,10]. However, using new results of stressed SPEG of (001) Si as a model system, a model of stressed solid-solid phase transformations is advanced which isolates the nucleation and migration processes. The results suggest that coordinated atomic motion may play a role in island ledge migration.In this study, a polished 50 m-thick (001) Si wafer was Si -implanted at 50, 100, and 200 keV to doses of 1 10 15 , 1 10 15 ...

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Effect of pressure on the solid phase epitaxial regrowth rate of Si

Cited by 44 publications

References 6 publications

Pressure-enhanced crystallization kinetics of amorphous Si and Ge: Implications for point-defect mechanisms

Pressure-enhanced crystallization kinetics of amorphous Si and Ge: Implications for point-defect mechanisms

Solid phase epitaxy in uniaxially stressed (001) Si

Kinetics and Morphological Instabilities of Stressed Solid-Solid Phase Transformations

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