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

The low-temperature pre-annealing effects on ultrashallow junctions were investigated. p/sup +//n and n/sup +//p ultrashallow junctions were prepared by low energy B/sub 2/H/sub 6/ & PH/sub 3/ plasma doping (PLAD) and excimer laser annealing (ELA). For the p/sup +//n junction, the junction depth was reduced significantly with increasing the pre-annealing temperature from 300/spl deg/C to 500/spl deg/. For the n/sup +//p junction, the dopant deactivation with subsequent annealing was reduced from 60/spl sim/80% to 20/spl sim/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.