A. De Veirman

Spectroscopic ellipsometry and transmission electron microscopy study of annealed high‐dose oxygen implanted silicon

The first results are presented of a comparative study of separation by implanted oxygen structures using spectroscopic ellipsometry (SE) and transmission electron microscopy. The strength of SE to measure the layer thicknesses of multilayer structures nondestructively is illustrated. Some limitations of the technique are also indicated.

HREM Investigation of Twinning in Very High Dose Phosphorus Ion-Implanted Silicon

Results are discussed of a study by means of high-resolution electron microscopy (HREM), electron diffraction, optical diffraction and image simulation of twinning in very high dose phosphorus ion-implanted (011) silicon wafers. Except for twins on the (111) planes (i. e.,Σ3 boundaries) andΣ9 boundaries, also regions showing, in the high-resolution image, a threefold periodicity are frequently observed. It is demonstrated that the diffraction pattern and the image of such regions can be explained by the overlap of twinned grains. Interpretation by the presence of polytypes of silicon is excluded. The possibility to image twins on inclined (111) planes is discussed.

Spectroscopic ellipsometry studies of SIMOX structures and correlation with cross-section TEM

Abstract The results are presented of a spectroscopic ellipsometry (SE) study of separation by implanted oxygen (SIMOX) structures both as-implanted and annealed at different temperatures. The obtained results are compared with transmission electron microscopy (TEM) observations of the same structures. It is shown that both techniques give comparable results but that SE allows additional information to be obtained. The strength of SE is not only to measure the layer thickness of multilayer structures nondestructively, but also to obtain quantitative information on the composition and crystal quality of the layers. Some limitations of the SE technique are also indicated.

Role of impurities in zone melting recrystallization of 10 μm thick polycrystalline silicon films

Zone melting recrystallization (ZMR) of polycrystalline silicon on SiO2 can offer an interesting, i.e., cheaper, alternative to the dielectric isolation technology used for high‐voltage integrated circuits or smart power devices. For that purpose crystalline Si layers of 10–15 μm thickness are needed. In this work a mercury‐arc lamp stripheater was used to recrystallize 10 μm thick polycrystalline silicon films. In unseeded layers, grain boundaries and subgrain boundaries appeared. By applying seeding, single crystalline areas of at least 1 mm by 1 mm were obtained. In these layers stacking faults were revealed as being the major crystal defect. In ZMR oxygen, nitrogen, and carbon are the major impurities which are incorporated into the silicon either intentionally or unintentionally. Among these impurities, nitrogen and carbon are believed to play a crucial role in promoting the wetting of the insulator and cap layer by liquid silicon. In this paper the distribution and transport of oxygen and nitrogen d...

Identification of CoSi inclusions within buried CoSi2 layers formed by ion implantation

High‐dose Co ion implantation in Si at elevated temperatures is used to synthesize buried CoSi2 layers. It is shown that inclusions of CoSi occur in the CoSi2 layer, when the stoichiometry level is exceeded at the peak of the Co distribution. These CoSi precipitates are observed prior to annealing and after a 5 s rapid thermal annealing (RTA) at 800 °C. During furnace annealing at 1000 °C or for RTA at temperatures above 900 °C, the CoSi phase transforms into CoSi2. In this communication the results of a transmission electron microscopy study of the CoSi inclusions are correlated with the Co depth profile, as determined by Rutherford backscattering spectrometry.

TEM study of combined oxygen and nitrogen implanted silicon

Abstract Silicon-on-insulator (SOI) structures can be obtained by the combined implantation of oxygen and nitrogen into silicon. A thorough transmission electron microscope study of the sequential N and O implantation in Si is reported. It is shown that the resulting microstructure strongly depends on the implantation sequence and dose. In general the buried layer remains amorphous. Only in one case did the lower part of the buried layer crystallize in the α-Si3N4 phase. When nitrogen is implanted prior to oxygen, α-Si3N4 precipitates are formed below the buried layer. They contain a considerable portion of the implanted nitrogen. A particular orientation relationship was found to exist between the α-Si3N4 precipitate and the Si matrix; it was determined as (00.1)αSi3N4//{111}Si.

The buried stacked insulator—a new silicon on insulator structure formed by ion beam synthesis

Abstract Using ion beam synthesis, a buried stacked layer consisting of silicon dioxide (upper part), silicon oxynitride (medium part) and silicon nitride (lower part) was formed in single-crystal silicon. Characterization was performed by Rutherford backscattering spectrometry and channelling, Auger electron spectroscopy and electron microscopy on cross-sectional samples.

Defects in high-dose oxygen implanted silicon: a TEM study

Abstract Results are discussed of a transmission electron microscopy study of high-dose oxygen implanted silicon. In addition to the general high temperature (>1200°C) annealing treatments also annealings at ‘low’ temperatures (1000–1100°C) were performed in order to slow down the precipitate and defect reactions. The observed dissolution of the oxide precipitates during prolonged high temperature annealing is explained by critical radius considerations. Threading dislocations are the remaining lattice defects in the silicon overlayer and cannot be removed by further annealing. Low temperature annealing results in the formation and subsequent unfaulting of extrinsic stacking fault loops below the buried oxide layer.

Transmission Electron Microscopy Study of Epitaxial Co/Au and Co/Pd (111) Multilayers

The results of a transmission electron microscopy study of Co/Au and Co/Pd multilayers are reported. Special emphasis is put on the epitaxial growth and the relaxation of the misfit strain of these high misfit systems. In bright-field cross-sectional images, periodic contrast fringes are observed at the interfaces, which are the result of Moire interference and which allow determination of the degree of misfit relaxation at the interface. It was established that 80-85% of the misfit is relaxed. From high resolution electron microscopy images the Burgers vector of the misfit dislocations was derived, being a/2 lying in the (111) interface plane. The results obtained for the Co/Au and Co/Pd multilayers will be discussed in comparison with those obtained for a bilayer of Co and Au.

Electron Microscopy of Interfaces in New Materials

Electron microscopy and electron diffraction are shown to be most useful for the characterisation of different interfaces in new materials. High resolution microscopy provides atomic scale information on the local structure of such interfaces. These structural characteristics strongly influence the physical properties of the materials. We will study planar interfaces in the high Tc superconductor YBa2Cu3O7-δ, in silverhalogenides such as AgC1, in the luminescent Y1-x(Sr,Li)xTa04 and in semiconductor devices.