Arsenic diffusivity in heavily-doped n-type silicon was observed to increase strongly with donor concentration. This was related to percolation effects, but explanations such as mobile As2V clusters or mobile AsDV clusters (where D was a donor) had also been postulated. Modeling and simulation of arsenic diffusion for high donor concentrations, based upon AsDV mobile clusters, were performed here within the framework of the atomistic non-lattice kinetic Monte Carlo model. Expressions for arsenic diffusivity in terms of microscopic parameters were developed, and the parameter set was calibrated using basic experiments and ab initio calculations. For donor concentrations above 2 x 1020/cm3, the model predicted a concentration-dependence of the arsenic diffusivity, with an exponent of 3.5. This was in close agreement with experimental observations, and was quite similar to the percolation model. Long hopping distances of AsDV clusters were also analyzed. Good agreement with experimental arsenic profiles was obtained for a wide variety of process conditions, including low ion-energy, high-dose and amorphizing implants, and annealing temperatures of 750 to 1050C.

Atomistic Modeling and Simulation of Arsenic Diffusion Including Mobile Arsenic Clusters. I.Martin-Bragado, N.Zographos, P.Castrillo: Physica Status Solidi A, 2014, 211[1], 147-51