Ramp-rate effects on transient enhanced diffusion and dopant activation

Use of high ramp rates ( > 400 deg C/s) in rapid thermal annealing after ion implantation leads to experimentally observed improvements in junction depth and the reverse narrow-channel effect. However, a straightforward explanation for this effect has been lacking. Via modeling, we find that increasing the heating rate permits clusters with dissociation energies lower than the maximum of 3.5-3.7 eV to survive to higher temperatures. This improved survival delays the increase in Si interstitial concentrations near the top of an annealing spike, which decreases the profile spreading.