Heating and melting solid materials over small space- and time-scales is a way to access the early stages of the melting phenomenon. Nanosecond-pulse laser annealing (LA) is a powerful processing tool for both fundamental investigations of molten phase ultra-rapid kinetics and technological applications, such as nanoscale reshaping, or alloy fraction and defects manipulation, which are crucial for the fabrication of unconventional 3D sequentially integrated devices.

Modelling such ultrafast non-equilibrium melting phenomena with atomic resolution can be fundamental to understand how to tailor the LA process to seek specific device features, however state-of-the-art LA process simulators, being based on continuum models, are blind to such fine details. In this talk a multiscale hybrid approach will be presented, coupling a µm-scale continuum model for laser-matter interaction and thermal diffusion with an atomistic Kinetic Monte Carlo scheme, able to capture the highly crystal-orientation dependent evolution of liquid-solid interfaces during the laser irradiation.

Benchmarks against experimental data and non-atomistic phase-field models, validating the approach, will be discussed, and the results of LA simulations for a Si(001) surface at various laser fluences and pulse shapes will be shown, assuming both homogeneous and inhomogeneous nucleation mechanisms. On-going efforts and developments of the simulator will also be highlighted, aiming at modelling defect generation and evolution during the LA process and generalizing the method to more complex materials, such as silicon-germanium alloys.

[1] G. Calogero, D. Raciti, P. Acosta-Alba, F. Cristiano, I. Deretzis, G. Fisicaro, K. Huet, S. Kerdilès, A. Sciuto & A. La Magna. Multiscale modeling of ultrafast melting phenomena. npj Computational Materials 8, 36 (2022)