Pileup of boron atoms near the maximum melt depth in bulk silicon and silicon-on-insulator (SOI) substrates upon laser annealing (LA) was studied. The results show that boron atoms accumulate near the maximum melt depth in shallow melting and increases with increasing laser pulses. The pileup is found to be related to the recrystallization behavior of the melted silicon during LA and occurs at a recrystallization transient, RT0, of about 10nm from the maximum melt depth in both SOI and bulk silicon substrates. An abrupt recrystallization process in preamorphized silicon, on the other hand, suppresses the formation of the boron pileup during LA.

In this letter, the authors study the dopant activation and dopant distribution in a Si+ subamorphized Si (SAI-Si) when subjected to laser annealing (LA). The results show an enhanced boron activation in the SAI-Si in the nonmelt regime as compared to a crystalline Si (c-Si). The enhancement is caused by a vacancy-rich surface generated by the Si+ preimplantation that promotes the incorporation of boron atoms into the substitutional sites. On the other hand, shallow-melt LA produces a similar boron activation in both SAI-Si and c-Si samples due to a melting that consumes the entire as-implanted profile and the vacancy-rich region.

In this letter, a low-cost alternative for forming high grade silicon germanium (SiGe) by a laser-induced crystallization of an amorphous Ge layer deposited directly on Si+ preamorphized implantation Si substrate is demonstrated. The results show that a fully strained epitaxial SiGe layer on the Si (100) substrate can be obtained at laser fluence above the epitaxial threshold. This is due to a liquid-phase epitaxial regrowth process of the laser annealing induced melted layer. Below the epitaxial threshold, polycrystalline SiGe is formed due to explosive recrystallization process. Simultaneous boron activation is achieved with the SiGe formation, a result due to the high temperature induced by the laser annealing.

In this letter, the effect of vacancies generated by preirradiated laser on dopant diffusion and activation in preamorphized silicon substrate has been studied. Laser-induced melting in silicon was used to generate excess vacancies near the maximum melt depth before silicon substrate amorphization and subsequent boron implantation. We demonstrate that by matching the preirradiated laser melt depth with the implant amorphize depth, it can effectively reduce the silicon self-interstitials released from the end-of-range defect band. The results show great suppression in boron transient enhanced diffusion and significant removal of end-of-range defects. This is attributed to the recombination of laser-generated excess vacancies with preamorphizing induced free silicon interstitials at the end-of-range region.

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