Transient enhanced diffusion of dopants in preamorphized Si layers

Conference · Sat Nov 01 04:00:00 EST 1997

OSTI ID:541101

Claverie, A; Bonafos, C; Omri, M; Mauduit, B de; Ben Assayag, G; Martinez, A; Alquier, D ^[1]; Mathiot, D ^[2]

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1. CNRS, Toulouse (France)
2. CNRS, Strasbourg (France). Lab. Phase

Transient Enhanced Diffusion (TED) of dopants in Si is the consequence of the evolution, upon annealing, of a large supersaturation of Si self-interstitial atoms left after ion bombardment. In the case of amorphizing implants, this supersaturation is located just beneath the c/a interface and evolves through the nucleation and growth of End-Of-Range (EOR) defects. For this reason, the authors discuss here the relation between TED and EOR defects. Modelling of the behavior of these defects upon annealing allows one to understand why and how they affect dopant diffusion. This is possible through the development of the Ostwald ripening theory applied to extrinsic dislocation loops. This theory is shown to be readily able to quantitatively describe the evolution of the defect population (density, size) upon annealing and gives access to the variations of the mean supersaturation of Si self-interstitial atoms between the loops and responsible for TED. This initial supersaturation is, before annealing, at least 5 decades larger than the equilibrium value and exponentially decays with time upon annealing with activation energies that are the same than the ones observed for TED. It is shown that this time decay is precisely at the origin of the transient enhancement of boron diffusivity through the interstitial component of boron diffusion. Side experiments shed light on the effect of the proximity of a free surface on the thermal behavior of EOR defects and allow us to quantitatively describe the space and time evolutions of boron diffusivity upon annealing of preamorphized Si layers.

• OSTI ID: 541101
• Report Number(s): CONF-961202--; ISBN 1-55899-343-6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
ANNEALING
CRYSTAL DEFECTS
CRYSTAL DOPING
DIFFUSION
ION IMPLANTATION
PHYSICAL RADIATION EFFECTS
SILICON