Micro-structural modifications of semiconductor systems under irradiation: experiment, modeling and simulation analysis.

Research on the micro-structural modifications of semiconductor systems has played a central role in the last decades. In particular, Laser Thermal Annealing receives a great interest in the formation of ultra-shallow junctions essential in nanoscale metal-oxide-semiconductor technology. An intriguing poorly understood issue is the post-implant kinetics of the defects-dopant system in the extremely far-from-the equilibrium conditions caused by the laser irradiation both in the non-melting and melting regime. For this purpose, the activation mechanism in the solid phase of phosphorus implanted silicon under excimer laser irradiation has been investigated by means of experimental analysis and modeling. The models have been originally formulated and implemented in numerical codes, which belong to the class of the continuum (based on Partial Differential Equations) and atomistic (Kinetic Monte Carlo) approaches for kinetic simulation of the dopant-defect system under laser irradiation. Continuum models will be also presented which clarified the boron non-equilibrium segregation during the fast solidification, i.e. the dopant pile-up phenomenon at the maximum melt depth. We will elucidate the dopant evolution mechanism in the melting phase considering the possibility of two different states governing the dopant diffusion in a tight temperature range around the melting temperature. Finally, an accurate study of the feasibility of laser irradiation as a heat source for real patterned substrates has been carried out for the case of SiGe and Ge based MOS devices. We developed a continuum simulation code which simulates the interaction between the laser light and the transistor periodic structure in order to estimate the heat source as well as the heat diffusion, phase changes and material redistribution under irradiation.