Luciana Capello

X-ray scattering study of hydrogen implantation in silicon

The effect of hydrogen implantation in silicon single crystals is studied using high-resolution x-ray scattering. Large strains normal to the sample surface are evidenced after implantation. A simple and direct procedure to extract the strain profile from the scattering data is described. A comparison between different crystallographic orientation of the implanted silicon surface is then presented, namely, for ⟨100⟩, ⟨110⟩, and ⟨111⟩ orientations, showing a dependence that can be related to bond orientation. Effect of annealing on the stressed structure is finally described.

Rough Surface Adhesion Mechanisms for Wafer Bonding.

Wafer bonding can be viewed as an example of rough surface adhesion. We show that formalisms developed to describe rough surface adhesion can be rescaled to nanometer range and applied to silicon wafer bonding, with results that fit well with experimental observations.

Quantitative study of hydrogen-implantation-induced cavities in silicon by grazing incidence small angle x-ray scattering

We used grazing-incidence small angle x-ray scattering to investigate properties of hydrogen implantation-induced platelets and cavities formed in silicon as a function of the implantation and annealing parameters. Density, orientation, and size (thickness and diameter) of these buried objects can be extracted from quantitative x-ray scattering intensity measurements, in a nondestructive manner. Detailed balance of hydrogen-induced defect evolution can be made with such data. Different defect populations result from different implantation temperatures and a low limit H dose is found for {111} platelets formation.

Development of microcracks in hydrogen-implanted silicon substrates

The development of microcracks in hydrogen-implanted silicon has been studied up to the final split using optical microscopy and mass spectroscopy. It is shown that the amount of gas released when splitting the material is proportional to the surface area of microcracks. This observation is interpreted as a signature of a vertical collection of the available gas. The development of microcracks is modeled taking into account both diffusion and mechanical crack propagation. The model reproduces many experimental observations such as the dependence of split time upon temperature and implanted dose.

Lattice strain of hydrogen-implanted silicon: Correlation between X-ray scattering analysis and ab-initio simulations

Hydrogen implanted silicon has been studied using high resolution X-ray scattering. Strain induced by implantation has been measured as a function of implantation dose. The dependence of strain with implanted dose shows different regimes starting from linear to quadratic and saturation. The observed strain is consistent with ab-initio and elasticity calculations. Strain rate changes can be associated to the predominant location of hydrogen in bond center location.

Light scattering from dislocations in silicon

Nondecorated glide dislocations in Czochralski grown silicon have been studied by laser scattering tomography technique. Dependence of intensity of scattered light on polarization of the incident light has been measured for different orientations of the dislocation line and Burgers vector. Detailed theory of light scattering by dislocation in silicon crystals is presented. It is shown that by combination of polarization and tomography measurements it is possible to determine slip system of nondecorated mixed dislocation in Si.

Investigation of non-decorated glide dislocations by infra-red light scattering tomography

The laser scattering tomography technique enables the observation of non-decorated dislocations in Si crystals. In polarization and tomography measurements, changes in the dislocation scattering intensity are observed. A study of the light scattering by a dislocation was then developed and described in this paper. Based on theoretical results and experimental observations, slip system of a non-decorated mixed dislocation can be totally determined.