Effects of Ni silicidation on the shallow p+n junctions formed by BF2+ implantation into thin polycrystalline-Si films on Si substrates

Effects of Ni silicidation on the samples that form shallow p+n junctions by BF2+ implantation into thin polycrystalline-Si films on Si substrates have been studied. The pre-formed junctions of the pre-annealed samples are slightly improved as a post Ni silicidation is applied to them, since silicidation can enhance the dopant diffusion. A silicided junction with a leakage of about 1 nA/cm2 at -5 V is obtained by the sample pre-annealed at 800 °C and post NiSi-silicided at 600 °C. On the other hand, as the samples are treated by depositing thin Ni films just after the implantation and then annealing, the resulting junctions are much better than the above pre-formed ones, without deepening the junction. During annealing, the simultaneous presence of both the driving forces arising from the Si interstitial and the Ni silicidation would significantly enhance the dopant drive-in efficiency. As a result, an NiSi-silicided shallow junction with a leakage of about 0.8 nA/cm2 and an ideality factor of about 1.00 can be obtained even at 700 °C.