An extensive study on the boron junctions formed by optimized pre-spike∕multiple-pulse flash lamp annealing schemes : junction formation, stability and leakage

In this work, the electrical activation of Boron in Germanium pre‐amorphized silicon substrate upon flash lamp annealing (FLA) is investigated. We demonstrate that FLA helps in the reduction of the EOR defects, resulting in minimal transient enhanced diffusion and dopant deactivation effect. It has also been observed that the junction stability improves with the increasing number of flash pulses, which is clearly reflected by the dopant deactivation level upon post‐thermal treatment. In another FLA scheme, the spike rapid thermal annealing (RTA) performed prior to the flash further enhances the junction stability. However, this pre‐spike RTA step induces extensive dopant diffusion and an overall degradation in sheet resistance. The above observations are concluded to be due to the different extent of silicon interstitial supersaturation that can be explained by the interactions between the extended defects and dopants. Lastly, leakage current for the junctions formed under different FLA schemes are compared. Typical single pulse FLA junction shows high leakage current and it can be reduced through the additional pulses of FLA or effectively suppressed by the pre‐spike RTA flash scheme. In addition, it is also found that the junction leakage can be correlated to the FLA residual defects.Published versio