Quantitative Transmission Electron Microscopy Analysis of the Pressure of Helium-Filled Cracks in Implanted Silicon

Tillmann, Karsten; Hüging, N.; Trinkaus, H.; Luysberg, M.

doi:10.1017/s1431927604040024

Cited by 10 publications

(15 citation statements)

References 18 publications

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“…Usually, at temperatures between 200 and 300°C, divacancies ͑V 2 ͒ recombine with diinterstitials ͑I 2 ͒. 13 Voids in crystalline Si interact with other lattice defects, such as misfit dislocations 14 via the strain field. 11 These He-V 2 clusters are active centers to capture other migrating vacancies, while I can recombine elsewhere, e.g., at the surface.…”

Section: Role Of C In the Formation And Kinetics Of Nanovoids Inducedmentioning

confidence: 99%

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

D’Angelo

Mirabella

Bruno

et al. 2008

Journal of Applied Physics

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The formation and growth of nanovoids in a C-doped Si layer after He+ implantation and thermal annealing are reported. A structure consisting of 240 nm of Si, 20 nm of Si doped with C at 0.8 at. %, and 240 nm of Si cap was realized by molecular beam epitaxy onto a 100 Si Czochralsky substrate. Three sets of samples were implanted with He+ at 30 keV and different doses of 81015, 31016, and 51016 cm−2 and subsequently annealed at 800 °C in N2 atmosphere. Cross-section transmission electron microscopy was used to determine the void size and location. The tensile strain of the C-doped layer was measured by high-resolution x-ray diffraction. Our studies report the double role of C in the formation and evolution of nanovoids. After the low dose implantation, the C-doped layer still shows tensile strain due to substitutional C, and voids are localized only within this layer. At higher implantation doses, all the C atoms have been displaced from substitutional sites. No more strain is present in the C-doped layer and the presence of large cavities in its neighborhood is strongly inhibited. This work shows how localized strain in epitaxial films can be effectively used to drive nanovoid formation and evolution

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Section: Role Of C In the Formation And Kinetics Of Nanovoids Inducedmentioning

confidence: 99%

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

D’Angelo

Mirabella

Bruno

et al. 2008

Journal of Applied Physics

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“…Figure 1 shows the pressure values measured for such platelet shaped He precipitates in Si, which were formed after He implantation and annealing at 400 °C (13). Theses pressure values were quantitatively determined from the Figure 1.…”

Section: Nucleation Of Dislocationsmentioning

confidence: 99%

Nucleation and Movement of Dislocations during Relaxation of He Implanted Si_xGe_1-x/Si_x Heterostructures

et al. 2006

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The fabrication of strain relaxed SixGe1-xbuffer layers is technologically of great importance, because biaxial, tensile strain can be achieved within a thin Si layer grown onto these SixGe1-x virtual substrates. Strain relaxation of the SixGe1-x layer can be accomplished by He implantation and subsequent annealing. In this paper we address the nucleation and movement of dislocations in He implanted SixGe1-x/Si heterostructures. By in-situ transmission electron microscopy we find clear evidence, that He precipitates formed during annealing act as internal dislocation sources and therefore promote the relaxation. This can be understood in view of the results of quantitative evaluation of the shear stress around He filled precipitates. Clearly, for some of the precipitates, the critical resolved shear stress for dislocation formation is exceeded at the edge of the platelets.

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“…Measurements of the pressure within the platelike shaped He precipitates, which represent the initial stage of He precipitates, 10,11 revealed the shear stress to reach the critical value of dislocation formation. 12 This indicates that He platelets may be capable to emit dislocations. In order to gain deeper insight into the relaxation mechanism of SiGe layers, we studied the evolution of the helium bubble structure as well as its interplay with nucleation and growth of dislocation loops utilizing in situ annealing investigations by transmission electron microscopy ͑TEM͒.…”

mentioning

confidence: 99%

“…7 In order to start the in situ experiment with a defined defect structure, the formation of overpressurized He filled platelets was provided by an ex situ annealing step at 420°C for 1 min. 11,12 Subsequently, TEM plan-view samples were prepared by mechanical polishing and subsequent argon ion milling.…”

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Evolution of the defect structure in helium implanted SiGe∕Si heterostructures investigated by in situ annealing in a transmission electron microscope

et al. 2005

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The evolution of the He-implantation induced defect structure in SiGe/ Si heterostructures is observed during in situ annealing at 650 and 800°C within a transmission electron microscope. The He implantation and annealing results in the formation of He precipitates below the SiGe/ Si interface, which at first show a platelike shape and subsequently decay into spherical bubbles. The coarsening mechanism of the He bubbles is revealed as coalescence via movement of entire bubbles. The nucleation of dislocation loops at overpressurized He platelets and their propagation into the heterostructure could be observed as well. We found distinctly different velocities of the dislocations which we attribute to glide and climb processes. The in situ experiments clearly show that the He platelets act as internal dislocation sources and play a key role in the relaxation of SiGe layers. Since strained silicon is generally realized by epitaxial deposition of Si on relaxed SiGe layers, relaxed buffers in an adequate quality are required. Efficient relaxation of thin SiGe films with a thickness of 100-200 nm and Ge contents of up to 30% was demonstrated by ion implantation of H or He and subsequent annealing.2-7 Its mechanism, however, is still under debate. Recently, Schwarz 8 simulated for a similar model system the dislocation dynamics during strain relaxation by assuming solely dislocation glide processes. Here, we follow an analytical model proposed by Trinkaus et al. 9 where H / He implantation and annealing induces the formation of dislocation loops created at overpressurized He precipitates located underneath the SiGe/ Si heterointerface. These loops glide to the interface where subsequently one part unlaces up to the surface and creates two threading segments, whereas the lagging part in the interface forms a strain-relieving misfit dislocation segment. Driven by the misfit strain the two threading segments move apart and eventually annihilate with threading dislocations of opposite Burgers vector. As a consequence, efficient and "healthy" strain relaxation is observed. Measurements of the pressure within the platelike shaped He precipitates, which represent the initial stage of He precipitates, 10,11 revealed the shear stress to reach the critical value of dislocation formation. 12This indicates that He platelets may be capable to emit dislocations. In order to gain deeper insight into the relaxation mechanism of SiGe layers, we studied the evolution of the helium bubble structure as well as its interplay with nucleation and growth of dislocation loops utilizing in situ annealing investigations by transmission electron microscopy ͑TEM͒.Si 81 Ge 19 layers with a thickness of 170 nm were deposited onto Si ͑001͒ substrates by chemical vapor deposition. Helium was implanted with an energy of 37 keV at a dose of 1 ϫ 10 16 cm −2 resulting in a helium concentration profile with its maximum in a depth about double the layer thickness. These implant conditions are optimum with respect to high degree of relaxation and low th...

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Quantitative Transmission Electron Microscopy Analysis of the Pressure of Helium-Filled Cracks in Implanted Silicon

Cited by 10 publications

References 18 publications

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

Nucleation and Movement of Dislocations during Relaxation of He Implanted Si_xGe_1-x/Si_x Heterostructures

Evolution of the defect structure in helium implanted SiGe∕Si heterostructures investigated by in situ annealing in a transmission electron microscope

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Quantitative Transmission Electron Microscopy Analysis of the Pressure of Helium-Filled Cracks in Implanted Silicon

Cited by 10 publications

References 18 publications

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

Role of C in the formation and kinetics of nanovoids induced by He+ implantation in Si

Nucleation and Movement of Dislocations during Relaxation of He Implanted SixGe1-x/Six Heterostructures

Evolution of the defect structure in helium implanted SiGe∕Si heterostructures investigated by in situ annealing in a transmission electron microscope

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Nucleation and Movement of Dislocations during Relaxation of He Implanted Si_xGe_1-x/Si_x Heterostructures