Controlling Dopant Diffusion and Activation through Surface Chemistry.

The degree of chemical bond saturation at surfaces can affect dopant activation and transient enhanced diffusion (TED) in silicon during annealing for ultrashallow junction formation. Point defects such as interstitial atoms can more easily combine with unsaturated dangling bonds than with saturated ones. Thus, maintaining an atomically clean surface during annealing greatly increases the annihilation probability. Statistical arguments show that such a surface removes Si interstitials from the underlying solid much faster than dopant interstitials. Simulations for boron and experiments for arsenic show that this effect leads to large and simultaneous improvements in dopant activation and TED. This surface-based method of defect engineering is relatively easy to integrate into a process line, and offers benefits over and above what can be obtained with methods used in parallel such as carbon co-implantation and laser annealing. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]