Anisotropic dopant diffusion in Si under stress using both continuum and atomistic methods

Abstract

In this paper we present a predictive simulation capability for dopant diffusion under anisotropic non uniform stress/strain using two different simulation techniques: continuum and atomistic Kinetic Monte Carlo (KMC). Due to the different nature of these techniques, different implementations have been developed. We explain the necessity and show the details of these implementations.The continuum model uses an anisotropic tensor matrix to simulate the diffusion. For the atomistic model, diffusion is the composition of multiple hops with different rates. For each particle, a different migration rate per axis is used. The value of the rate takes into account the local stress tensor. The stress is also utilized for modeling surface point defect injection and dopant pairing.These models have been included in a TCAD simulator (Synopsys: Sentaurus reference Manual, 3rd edn., 2007) as an extension to the already existing models. We show that both continuum and atomistic approaches predict similar behavior for boron diffusion under tensile and compressive stresses in 2D.

Mechanism behind the stress‐induced change in boron and arsenic diffusion in silicon devices and its experimental verification

“…However, there are conflicting reports on the effects of compressive stress on boron diffusion. Several research groups reported on the enhanced boron diffusion through compressive stress that is induced by the nitride spacer 5, 6, shallow trench isolation (STI) 7, Si 1− x Ge x S/D stressor 8, and TiN metal gate 9. At the same time, the retardation of boron has been observed for STI‐induced compressive stress 10, 11, and compressive stressed Si 1− x Ge x layer 12.…”