Characteristics of low-temperature preannealing effects on laser-annealed P+/N and N+/P ultra-shallow junctions

The low-temperature pre-annealing effects on ultrashallow junctions were investigated. p⁺/n and n⁺/p ultrashallow junctions were prepared by low energy B₂H₆ & PH₃ plasma doping (PLAD) and excimer laser annealing (ELA). For the p⁺/n junction, the junction depth was reduced significantly with increasing the pre-annealing temperature from 300°C to 500°. For the n⁺/p junction, the dopant deactivation with subsequent annealing was reduced from 60∼80% to 20∼40% by low-temperature pre-annealing. The significant improvements of ultrashallow junction characteristics were attributed to the reduction of point defects by low-temperature preannealing.