Phenomenological model of Silicon-On-Diamond laser bonding

A recently proposed method of fabrication of a Silicon-On-Diamond material, based on pulsed laser irradiation of the diamond–silicon interface [1,2], has been modeled by means of a finite element one-dimensional numerical algorithm. A wide set of mechanisms of energy-transport and exchange has been taken into account: reflection, transmission and absorption of light; generation, diffusion, recombination and energy relaxation of the electron–hole plasma; heat transfer; phase changes; generation and propagation of pressure waves. The model allows us to determine the energy thresholds for the adhesion of diamond and silicon at each pulse width and also gives predictions about the behavior of other measurable quantities, like thickness of the amorphized layer and reflectivity of the interface during and after irradiation. This work is meant to be both a basis for the optimization of the process, in view to its application in microelectronics, and a reference to explore wider ranges of process parameters with respect to those reported in the previous literature.

Research highlights
► Finite element modeling of the Silicon-On-Diamond laser bonding process
► Radiation-matter interaction, plasma effects and pressure waves are considered.
► Energy density threshold for Si–D adhesion, as a function of wavelength and pulse width
► Prediction of the interface layer thickness and of the reflectivity temporal profile