The kinetic Monte Carlo method is an event-driven technique, i.e., it simulates events (e.g. diffusion hops) at random, with probabilities according to their respective event rates. In this way it self-adjusts the time-step as the simulation proceeds and, thus, is able to simulate the time scales involved in typical technological processing steps (seconds to hours). In this method is necessary to define the relevant events or reactions to be considered in the simulator (e.g. defect formation and dissolution) and provide the values of the activation energies and prefactors for each one of the reactions that may take place. Generally, this kind of information (formation energies, migration energies, energy barriers...) can be obtained from more fundamental atomistic simulation methods (classical molecular dynamics, ab initio...). Only in a few cases these parameters can be obtained directly from experiments, due to the difficulty of extracting information at the atomic scale. The use of the Kinetic Monte Carlo method within a non-lattice scheme allows us the simulation of the system dynamics from an atomistic point of view while reaching the size dimensions of current ULSI devices at a macroscopic scale.
We use the Kinetic Monte Carlo method within a non-lattice scheme to develop atomistic models that capture complex dopant-defect interactions in order to simulate defect evolution, amorphization and recrystallization processes, evolution of dopant profiles and dopant electrical activation associated to technological process for semiconductor devices fabrication.
Lateral view of the boron (B) concentration in a fully-depleted CMOS device as obtained from Kinetic Monte Carlo simulations after implantation (0,5 keV B 5·1015 cm-2, 10º tilt) and 1100ºC spike annealed typically used to fabricate source-drain extension regions.
|Classical molecular dynamics|
|Binary collision approximation|
|Kinetic Monte Carlo|