Atom redistribution during co-doped amorphous silicon crystallization

A. Portavoce (1) , D. Mangelinck (1) , R Simola (2) , R Daineche (1) , J. Bernardini (1)

1 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2 ST-ROUSSET - STMicroelectronics [Rousset]

Atom redistribution during crystallization of a B and P co-doped amorphous Si layer produced by Si and P chemical vapor co-deposition and B implantation has been investigated. The crystallization of the entire layer is quasi-instantaneous for annealing temperature greater than 650 °C. The crystallization rate is well reproduced by the Avrami-Johnson-Mehl-Kolmogorov model of transformation. The Avrami n is found equal to 4, which is corresponding to 3D bulk crystallization. Crystallization promotes a non-Fickian redistribution of B atoms, allowing for an abrupt interface between B-doped and B-undoped regions. After crystallization, B diffuses in the polycrystalline Si layer for concentrations lower than 1.5 × 10 20 at cm −3 via the type B kinetic regime. Crystallization has no significant (or detectable) influence on the P profile. For temperatures higher than 750 °C, P diffuses in the poly-Si layer towards the region of highest B concentration via the type B kinetic regime, leading to P uphill diffusion. This phenomenon can be simulated considering chemical interactions between B and P atoms in both grains and grain boundaries.

Mots clés: diffusion; phosphorus; boron; dopant interactions; Silicon crystallization

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

A. Portavoce, D. Mangelinck, R Simola, R Daineche, J. Bernardini. Atom redistribution during co-doped amorphous silicon crystallization. Defect and Diffusion Forum, 2009, 289-292, pp.329-337. ⟨hal-02406667⟩