Atomistic Modeling of Boron Activation and Diffusion in Strained SiGe

S. Dunham (1) , J. Song (1) , C. Ahn

1 ECE - Department of Electrical and Computer Engineering

We used a combination of atomistic models, DFT and KLMC, to analyze the complex issues associated with B diffusion and activation in nanoscale Si devices. Using DFT, we developed general models which separate out global strain from local binding of B with Ge in Si1-yGey alloys for both substitutional B as well as the Bi transition state which controls diffusion. The models were used to derive segregation/activation and diffusion of boron as a function of Ge content, plus any additional applied stress. We found that the increase of segregation and activation in strained Si1-yGey alloys is mainly due to the effect of strain rather than binding, with model accurately predicting experimental observations. B diffusion in SiGe is a complex system due to multi-step diffusion process, anisotropic strain and multiplicity of local Ge arrangements. By using DFT calculations spanning a range of Ge configurations and strain conditions, we are able to identify the mechanisms leading to retarded B diffusion: a combination of local Bi-Ge repulsion and global strain interactions. KLMC using DFT parameters predicts experimental results accurately up to 50% Ge.

Mots clés: Diffusion silicon boron activation modeling stress strain CMOS

Domaines: Science des matériaux [cond-mat.mtrl-sci]

S. Dunham, J. Song, C. Ahn. Atomistic Modeling of Boron Activation and Diffusion in Strained SiGe. ENS 2005, Dec 2005, Paris, France. pp.126-130. ⟨hal-00166995⟩