Transient Enhanced Diffusion Boron implantation is widely used to form shallow junctions in silicon devices. The diffusion of boron is enhanced by excess silicon self-interstitials created by the implant. The ability to reliably predict the behaviour of implanted boron requires a much better understanding of the mechanisms which contribute to enhanced diffusion. It has been shown that carbon acts as a sink for interstitials present during thermal annealing of implanted silicon. This has the effect of suppressing processes driven by the supersaturation of silicon interstitials, namely secondary defect formation and enhanced diffusion of boron.
Current studies relate to the interaction of carbon and interstitial silicon in crystalline silicon.
Although ion implantation damage and recovery has been extensively studied for more than 25 years, there is not, as yet, a complete understanding of these processes. Ion implantation damage to the crystal lattice is due to nuclear collisions of the incident ions with the substrate constituents. In the case of subsaturated damage, thermal annealing will often result in the formation of dislocation loops and dipoles which are stable up to relatively high temperatures. Current studies focus on the role of impurity carbon in the suppression of these secondary defects. In general, the amorphous phase of a material has a different refractive index than the crystalline phase.