Point defect production, geometry and stability in silicon: A molecular dynamics simulation study

We present results of molecular dynamics computer simulation studies of the threshold energy for point defect production in silicon. We employ computational cells with 8000 atoms at ambient temperature of 10 K that interact via the Stillinger-Weber potential. Our simulations address the orientation dependence of the defect production threshold as well as the structure and stability of the resulting vacancy-interstitial pairs. Near the directions, a vacancy tetrahedral-interstitial pair is produced for 25 eV recoils. However, at 30 eV recoil energy, the resulting interstitial is found to be the split dumbbell configuration. This Frenkel pair configuration is lower in energy than the former by 1.2 eV. Moreover, upon warming of the sample from 10 K the tetrahedral interstitial converts to a split before finally recombining with the vacancy. Along directions, a vacancy- split interstitial configuration is found at the threshold energy of 22 eV. Near directions, a wide variety of closed replacement chains are found to occur for recoil energies up to 45 eV. At 45 eV, the low energy vacancy- split configuration is found. At 300 K, the results are similar. We provide details on the atomic structure and relaxations near these defects as well as on their mobilities

Front-end process modeling in silicon

Front-end processing mostly deals with technologies associated to junction formation in semiconductor devices. Ion implantation and thermal anneal models are key to predict active dopant placement and activation. We review the main models involved in process simulation, including ion implantation, evolution of point and extended defects, amorphization and regrowth mechanisms, and dopant-defect interactions. Hierarchical simulation schemes, going from fundamental calculations to simplified models, are emphasized in this Colloquium. Although continuum modeling is the mainstream in the semiconductor industry, atomistic techniques are starting to play an important role in process simulation for devices with nanometer size features. We illustrate in some examples the use of atomistic modeling techniques to gain insight and provide clues for process optimization