Tetsuya Okuyama

Dynamical diffraction effect on HOLZ-pattern geometry in Si-Ge alloys and determination of local lattice parameter

Abstract Higher-order Laue zone (HOLZ) patterns are observed in convergent-beam electron diffraction (CBED) patterns of Si-Ge alloys and the dynamical effect on HOLZ lines is discussed in relation to the kinematical approximation to simulate the HOLZ lines. Double lines often appear from one HOLZ reflection due to the excitation of the first and second branches of the zeroth-layer dispersion surface. The magnitude of the systematic line shift from the line positions predicted by the kinematical simulation changes sensitively with specimen thickness and alloy composition depending on which branch is dominantly excited. The kinematical simulation is applicable to accurate determination of lattice parameters with a proper correction δ E : a difference between the effective electron energy and the actual microscope operating voltage. Usefulness of the kinematical simulation is demonstrated in the investigation of the segregation in a Si-Ge alloy.

Analysis of Local Lattice Strains Around Plate-Like Oxygen Precipitates in Czochralski-Silicon Wafers by Convergent-Beam Electron Diffraction

Convergent-beam electron diffraction (CBED) is used to study lattice strain around plate-like oxygen precipitates in Czochralski (CZ)-grown silicon. Local lattice strain determined from higher-order Laue zone (HOLZ) patterns shows that compressive and tensile stress fields exist near the precipitates. The spatial variation of local lattice strain and lattice rotation is visualized in a defocused large angle CBED disc, or a convergent-beam imaging (CBIM) disc.

Dynamical diffraction effects on higher-order Laue zone lines in CBED patterns of semiconductors

Abstract We studied the dynamical diffraction effects on the defect lines of higher-order Laue zone reflections (HOLZ lines) in bright field disks of convergent-beam electron diffraction (CBED). The positions of the HOLZ lines were confirmed experimentally to deviate by a small amount from the positions expected from the kinematical approximation. The amount of line shift is represented by the corresponding deviation of the accelerating voltage Δ E . In the case of [111] incidence, one HOLZ reflection can generate two lines with negative and positive values of Δ E . Calculations based on the dynamical diffraction theory clarified that the HOLZ lines with negative and positive Δ E arise from the first and second branches of the zeroth-layer dispersion surface, respectively. Either, or occasionally both, of the lines is observed in the HOLZ pattern, depending upon which branch is dominantly excited. The dependency of Δ E on the material species and thickness of specimen and on the zone axis is discussed in detail for Si, Ge and some III–V compound semiconductors.

Strain Analysis of Si by FEM and Energy-Filtering CBED

Lattice strains around a platelet oxygen precipitate in Si wafer is studied by energy filtering convergent-beam electron diffraction (CBED) and calculations based on the finite element method (FEM). Local lattice strains are measured from CBD patterns obtained with a probe size less than 2 nm in a specimen thicker than 450 nm. Strains measured are compressive along a direction normal to a plate of the precipitation and tensile along a direction parallel to the plate. Two-dimensional stress fields near the precipitate are obtained with FEM computer analyses by fitting the measured strains. It appears that shear stresses are concentrated at the end of the precipitate edge and the maximum shear stress at an interface between the precipitate and the Si-matrix is 1.9 GPa. It is demonstrated that a combination of the energy filtering CBED and FEM is very useful for the study of local strains near interfaces in semiconductor devices, in particular for the study of stress fields that are too steep for application of the conventional CBED technique.