Ultrashallow P⁺/n junction formed by $B18H22+$ Ion Implantation and Excimer Laser Annealing

Conventional ultrashallow junction processes require two‐step implantation such as pre‐amorphization by Si⁺ or Ge⁺ implantation and ultra‐low (<0.5 keV) energy B⁺ implantation. In this report, we investigate B₁₈H₂₂ molecular ion implantation. Due to the heavy mass of cluster ions, one step ion implantation at equivalent implant energy of 0.25 keV readily forms a 5 nm‐thick a‐Si layer and an ultrashallow junction without boron channeling. By employing excimer laser annealing (ELA), we have obtained a shallow junction depth (<10 nm) and low sheet resistance (∼830 ohm/sq.). When applied pre‐annealing step prior to ELA, junction depth can be further scaled down with reduced residual damage.