Micro-Raman study of stress distribution in local isolation structures and correlation with transmission electron microscopy

Wolf, Ingrid De; Vanhellemont, Jan; Romano‐Rodríguez, A.; Norström, H; Maes, H.E.

doi:10.1063/1.351311

Cited by 155 publications

(76 citation statements)

References 7 publications

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“…Here, 1 ' corresponds to the axis perpendicular to the crack plane and 3 is along the direction of the growth axis. In order to properly use these stresses to determine the associated Raman frequency shifts, as is done in [16] for silicon, the six piezospectroscopic coefficients for the hexagonal nitrides are required. Since these have not yet been reported, we apply the biaxial analysis in order to estimate the stress from the frequency shift.…”

Section: Resultsmentioning

confidence: 99%

Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

et al. 2001

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We report post-growth micro-Raman stress mapping of cracks in GaN, AlN, and Al x Ga 1-x N grown on (111) oriented silicon. Cracks with an average spacing of ~ 100 µm are observed. These cracks are categorized into two types. The first type of crack propagates through the epilayer, and several microns deep into the substrate and is observed in all the samples investigated. The second type cracks epilayer only and is observed only in GaN. The microRaman stress mapping of the first type of crack shows that the epilayers are under biaxial tensile (< 0) stress and the silicon substrate is under compressive (> 0) stress far away from the cracks. The stress in the epilayers as well the substrate is found to relax from the equilibrium (far away from the cracks) value of -0.5 GPa (AlN), -0.16 GPa (GaN), -0.6 GPa (Al x Ga 1-x N) and 0.36 GPa (Si) as the crack position is approached. Partial relaxation is observed to occur over a range of 10 µm. At the crack position, the epilayers and the substrate are relaxed to nearly zero stress values. The stress mapping of the second type of crack reveals that the substrate is completely relaxed (stress is close o zero) far away from the cracks. At the crack position the GaN epilayer is partially relaxed from -0.2 GPa to -0.08 GPa, while the silicon substrate is seen to be under tensile stress of -0.39 GPa. The stress map of epilayers is well described by the distributed force model for both types of cracks. Furthermore, the calculated stress profiles of cracked and uncracked substrate using the above mentioned model are in excellent agreement with the experimental data.

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Section: Resultsmentioning

confidence: 99%

Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

et al. 2001

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“…3,4 In nanoscale devices, however, the surface-tovolume ratio is so large that the influence of surfaces, edges, and corners on elastic properties become significant. In addition, chemical bonding at the Si/Si 3 N 4 interface introduces types of stresses not present in silicon or silicon nitride materials.…”

mentioning

confidence: 99%

Multimillion-atom molecular dynamics simulation of atomic level stresses in Si(111)/Si3N4(0001) nanopixels

Bachlechner

Omeltchenko

Nakano

et al. 1998

Applied Physics Letters

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Ten million atom multiresolution molecular-dynamics simulations are performed on parallel computers to determine atomic-level stress distributions in a 54 nm nanopixel on a 0.1 m silicon substrate. Effects of surfaces, edges, and lattice mismatch at the Si͑111͒/Si 3 N 4 ͑0001͒ interface on the stress distributions are investigated. Stresses are found to be highly inhomogeneous in the nanopixel. The top surface of silicon nitride has a compressive stress of ϩ3 GPa and the stress is tensile, Ϫ1 GPa, in silicon below the interface. © 1998 American Institute of Physics. ͓S0003-6951͑98͒00116-8͔Sub-100 nm pixel sizes pose special challenges in Si electronics. In this regime, the significance of spatial inhomogeneities in the dopant distribution to the device characteristics is being increasingly appreciated.1 Spatially nonuniform stresses induced by such nanoscale pixellation may have profound impact 2 -rapidly varying stresses at and near edges may lead to defect formation or even initiate a crack. Understanding the stress distribution is therefore essential in the design of nanoscale devices.On larger (Ͼ1 m) length scales, edge stresses in Si/SiO 2 and Si/Si 3 N 4 have been examined utilizing the framework of linear elasticity and finite-element ͑FE͒ simulations. 3,4 In nanoscale devices, however, the surface-tovolume ratio is so large that the influence of surfaces, edges, and corners on elastic properties become significant. In addition, chemical bonding at the Si/Si 3 N 4 interface introduces types of stresses not present in silicon or silicon nitride materials. These effects have to be included in constitutive relations to achieve realistic description of nanoscale devices in the FE approach. An alternative approach is to use molecular-dynamics ͑MD͒ simulations where surface and interface bonding effects are explicitly included at the atomistic level. With recent progress in parallel computer architectures, it has now become possible to carry out direct atomistic simulations for submicron structures with realistic descriptions of the materials involved. In particular, largescale MD simulations have proven to be useful in the study of dynamic fracture.5 MD simulations provide spatially resolved stress distributions on the length scales not accessible to experimental techniques, such as MicroRaman spectroscopy.6 Such numerical experiments can be used to establish the validity of constitutive relations used in FE simulations, in particular the treatment of surface/interface/ edge effects.In this letter, the results of a ten million atom moleculardynamics study of atomic stress distribution in a Si/Si/Si 3 N 4 nanopixel are reported. The simulations were performed on 128 processors of the 256-processor HP Exemplar at Caltech requiring a total of 180 h of computational time. We have considered a crystalline Si 3 N 4 film forming a coherent Si͑111͒/Si 3 N 4 ͑0001͒ interface 7 with the Si mesa. An interatomic potential model for the Si/Si 3 N 4 interface has been developed using the charge transfer values computed from...

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“…The anomalous feature may also be a defect due to stress. Large tensile stress at the bird's beak edge due to bending of the nitride mask has been observed by micro-Raman spectroscopy [78,79] and x-ray diffraction imaging [80] which can generate defects or even break the pad oxide there. This tensile stress may be related to the anomalous profile.…”

Section: Parameterization Of Locos Profilementioning

confidence: 99%

“…Therefore a large dI/dV contrast that can offer an accurate picture of P S can only be achieved if the ILDOS does not have a sizable spin polarization and we can assume a constant tunnel distance [78]. The minimum requirement for observing any contrast is to at least have different spin polarizations for LDOS and ILDOS but in this case an accurate value of P S is not possible.…”

Section: Spin-polarized Stmmentioning

confidence: 99%

“…Even though SP-STS is appropriate for studying nanoscale magnetism, the spectroscopic nature of the technique makes the extraction of accurate spin polarization difficult [78] and also limits the applicability to a wider range of material systems. A primary reason for these limitations is the need of strong spin-polarized features in the LDOS of the sample, as the exchange-split (surface) state of Gd(0001).…”

Section: Spin-polarized Stmmentioning

confidence: 99%

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Spin-filter scanniing tunneliing microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

Vera‐Marun

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Micro-Raman study of stress distribution in local isolation structures and correlation with transmission electron microscopy

Cited by 155 publications

References 7 publications

Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

Multimillion-atom molecular dynamics simulation of atomic level stresses in Si(111)/Si3N4(0001) nanopixels

Spin-filter scanniing tunneliing microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

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Micro-Raman study of stress distribution in local isolation structures and correlation with transmission electron microscopy

Cited by 155 publications

References 7 publications

Micro-Raman Scattering From Hexagonal GaN, AlN, and AlxGa1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

Micro-Raman Scattering From Hexagonal GaN, AlN, and AlxGa1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

Multimillion-atom molecular dynamics simulation of atomic level stresses in Si(111)/Si3N4(0001) nanopixels

Spin-filter scanniing tunneliing microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

Contact Info

Product

Resources

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Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks

Micro-Raman Scattering From Hexagonal GaN, AlN, and Al_xGa_1-xN Grown on (111) Oriented Silicon: Stress Mapping of Cracks