Stability of Si-Interstitial Defects: From Point to Extended Defects

Kim, Jeongnim; Kirchhoff, F.; Wilkins, John W.; Khan, F. S.

doi:10.1103/physrevlett.84.503

Cited by 156 publications

(85 citation statements)

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“…The I 2 and I 3 formation energies are calculated to be 2.63 and 1.99 eV, respectively ͑in excellent agreement with the values of 2.5 and 1.9 eV obtained in recent DFT-LDA calculations͒. 16 We calculate the formation energy for a Si self-interstitial to be 3.3 eV, very close to the result of 3.3-3.35 eV from other DFT-LDA calculations. 15 We also examined the possibility of boron liberation from the B-containing interstitial clusters.…”

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confidence: 72%

“…For crystalline Si, the compact tri-interstitial cluster (I 3 ) has a formation energy ϳ0.2 eV lower than the ring cluster and 0.4 eV lower than elongated clusters. 16 Figure 1 also shows compact I 2 and I 3 clusters ͑fully relaxed structures͒. The I 2 and I 3 formation energies are calculated to be 2.63 and 1.99 eV, respectively ͑in excellent agreement with the values of 2.5 and 1.9 eV obtained in recent DFT-LDA calculations͒.…”

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confidence: 67%

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Catalytic role of boron atoms in self-interstitial clustering in Si

Hwang

Goddard

2003

Applied Physics Letters

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Using density functional theory ͑DFT͒ calculations and kinetic simulations, we have investigated the influence of boron atoms on self-interstitial clustering in Si. From DFT calculations of neutral interstitial clusters with a single B atom ͑B s I n , nр4͒, we find that the binding of B ͑B s I n →I nϪ1 ϩB s I) becomes substantially weaker than that of an interstitial ͑B s I n →B s I nϪ1 ϩI) when nу4. This implies boron can be liberated while leaving an interstitial cluster behind. Our kinetic simulations including the boron liberation explain well experimental observations reported by J. L. Continued scaling of Si devices below 0.1 m requires formation of ultrashallow junctions to avoid short-channel effects. 1 Ultralow-energy ion beams are currently most widely used to introduce dopants into the Si substrate. Generally this must be followed by high-temperature thermal annealing to eliminate substrate damage generated by energetic ion bombardment and to electrically activate the injected dopants. During the implantation and annealing, the dopant atoms exhibit transient enhanced diffusion ͑TED͒. This is a particularly serious problem for boron ͑a major p-type dopant͒, which exhibits large TED. The consequent doping profile spreading imposes a great difficulty in forming ultrashallow pn junctions in deep submicron device structures.It is now well understood that excess Si self-interstitials generated during implantation are mainly responsible for the B TED. Due to large mobility even at room temperature, 2 single interstitials can diffuse and annihilate at the surface. Therefore, at the onset of annealing most interstitials are likely to remain in the form of clusters. It is widely believed that, in ultrashallow junction formation by ultralow energy ion implantation, the main sources for free interstitials during postimplantation annealing are small interstitial clusters and boron-interstitial complexes 3-6 along with extended ͕311͖ defects. The formation of boron-interstitial complexes have been extensively studied using first principles calculations, 7,8 also supported by recent experiments. 9 However, little is known about the role of single B atoms in the growth of small interstitial clusters.Deep level transient spectroscopy recently provided direct evidence for the existence of small Si interstitial clusters. 10 These results showed that the small interstitial clusters did not contain large numbers of B atoms even in a B doped layer ͑where B concentration was not high enough to induce B clustering͒. This was surprising because recent ab initio calculations 7,8 suggested that Si interstitials interact very strongly with substitutional B to form stable B s I, B s I 2 , and B s I 3 complexes with large thermal stability comparable to that of small interstitial clusters. 7,8 In order to provide a basis for understanding the formation of interstitial clusters in the presence of B, we have carried out ͑i͒ first-principles quantum mechanics calculations on the structures and energetics of small interstitial cluster...

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supporting

confidence: 72%

supporting

confidence: 67%

Catalytic role of boron atoms in self-interstitial clustering in Si

Hwang

Goddard

2003

Applied Physics Letters

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“…[4][5][6][14][15][16][17][18][19][20][21][22] These studies have employed a broad range of theory to describe interatomic interactions, ranging from empirical potentials, 4,14,15 to tight binding, [16][17][18] to electronic density-functional theory ͑DFT͒. 5,6,[20][21][22][23] While there are some discrepancies between the various studies regarding the precise values and ordering of the predicted formation energies, some general conclusions can be drawn. First, it is clear that on a per-interstitial basis, and in the limit of infinite size, the formation energy of all ͕111͖ planar defects is lower than either ͕100͖ or ͕113͖ defects.…”

Section: Formation Thermodynamics For Self-interstitial Clusters-prevmentioning

confidence: 99%

“…The various predicted structures were found to be in excellent structural agreement with microscopy observations and electronic-structure calculations. [2][3][4][5][6][7] Overall, the three different potentials employed, namely, the environment-dependent interatomic potential ͑EDIP͒, 8 Tersoff, 9 and Stillinger-Weber ͑SW͒, 10 all predicted consistent overall trends, leading to a qualitatively coherent picture for some aspects of selfinterstitial clustering in silicon. In particular, it was found that cluster morphology is sensitively dependent on both the temperature and stress within the lattice.…”

Section: Introductionmentioning

confidence: 99%

Detailed microscopic analysis of self-interstitial aggregation in silicon. II. Thermodynamic analysis of single clusters

2010

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We analyze results generated by large-scale molecular-dynamics simulations of self-interstitial clusters in crystalline silicon using a recently developed computational method for probing the thermodynamics of defects in solids. In this approach, the potential-energy landscape is sampled with lengthy moleculardynamics simulations and repeated energy minimizations in order to build distribution functions that quantitatively describe the formation thermodynamics of a particular defect cluster. Using this method, a comprehensive picture for interstitial aggregation is proposed. In particular, we find that both vibrational and configuration entropic factors play important roles in determining self-interstitial cluster morphology. In addition to the expected role of temperature, we also find that applied (hydrostatic) pressure and the commensurate lattice strain greatly influence the resulting aggregation pathways. Interestingly, the effect of pressure appears to manifest not by altering the thermodynamics of individual defect configurations but rather by changing the overall energy landscape associated with the defect. These effects appear to be general and are predicted using multiple, well-tested, empirical interatomic potentials for silicon. Our results suggest that internal stress environments within a silicon wafer (e.g., created by ion implantation) could have profound effects on the observed selfinterstitial cluster morphology. We analyze results generated by large-scale molecular-dynamics simulations of self-interstitial clusters in crystalline silicon using a recently developed computational method for probing the thermodynamics of defects in solids. In this approach, the potential-energy landscape is sampled with lengthy molecular-dynamics simulations and repeated energy minimizations in order to build distribution functions that quantitatively describe the formation thermodynamics of a particular defect cluster. Using this method, a comprehensive picture for interstitial aggregation is proposed. In particular, we find that both vibrational and configuration entropic factors play important roles in determining self-interstitial cluster morphology. In addition to the expected role of temperature, we also find that applied ͑hydrostatic͒ pressure and the commensurate lattice strain greatly influence the resulting aggregation pathways. Interestingly, the effect of pressure appears to manifest not by altering the thermodynamics of individual defect configurations but rather by changing the overall energy landscape associated with the defect. These effects appear to be general and are predicted using multiple, well-tested, empirical interatomic potentials for silicon. Our results suggest that internal stress environments within a silicon wafer ͑e.g., created by ion implantation͒ could have profound effects on the observed selfinterstitial cluster morphology. Disciplines Biochemical and Biomolecular Engineering | Chemical Engineering | Engineering

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“…For example, in silicon, antimony impurities are vacancy diffusers and phosphorus are interstitial diffusers 1 . Therefore, self-diffusion in Si has been extensively investigated by experiments 1,2,3,4,5 and simulations 6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33 .…”

Section: Introductionmentioning

confidence: 99%

Sampling the diffusion paths of a neutral vacancy in silicon with quantum mechanical calculations

2004

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We report a first-principles study of vacancy-induced self-diffusion in crystalline silicon. Starting form a fully relaxed configuration with a neutral vacancy, we proceed to search for local diffusion paths. The diffusion of the vacancy proceeds by hops to first nearest neighbor with an energy barrier of 0.40 eV in agreement with experimental results. Competing mechanisms are identified, like the reorientation, and the recombination of dangling bonds by Wooten-Winer-Weaire process.

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Stability of Si-Interstitial Defects: From Point to Extended Defects

Cited by 156 publications

References 20 publications

Catalytic role of boron atoms in self-interstitial clustering in Si

Catalytic role of boron atoms in self-interstitial clustering in Si

Detailed microscopic analysis of self-interstitial aggregation in silicon. II. Thermodynamic analysis of single clusters

Sampling the diffusion paths of a neutral vacancy in silicon with quantum mechanical calculations

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