Anomalous B penetration through ultrathin gate oxides during rapid thermal annealing

We have observed accelerated diffusion of B in ultrathin gate oxides during rapid thermal annealing (RTA) of the gate stack. Enhanced diffusion by 10-100 times over standard furnace annealing has been measured in SiO/sub 2/. The activation energy for B diffusion in SiO/sub 2/ during RTA is decreased by about 0.5 eV when compared to furnace annealing results. We propose a model that involves the capture of optically generated holes by diffusion defects which results in reduced B migration enthalpy through the modified defect, whose bonding has been weakened by the presence of captured positive charge. No similar optical radiation effect was observed when F was present in the oxide.