Effect of pulse number on dopant activation in silicon during shallow p+/n junction formation by non-melt excimer laser annealing

Abstract

Shallow p+/n junctions were formed using Ge-PAI and low-energy/high-dose boron-ion implantation, followed by thermal annealing involving nano second non-melt excimer laser annealing and rapid thermal annealing. The effect of laser pulse number on dopant activation and regrowth of a-Si layer are discussed.We found that laser annealing alone is insufficient to regrow a-Si layer and activate dopant. In contrast, activation was observed in the samples that were subjected to pre annealing rapid thermal annealing followed by non-melt laser annealing; with slight increase of sheet resistance value when the number of laser pulse shot was increased. This is considered due to the interaction of dopant and supersaturated defect in the remaining a-Si layer.The percentage of defect-dopant interaction increased with the pulse shot numbers which contributed to the decrease in activation level.