Influence of fluorine in BF2+ implantation on the formation of ultrashallow and low-leakage silicon p+n junctions by 450–500 °C annealing

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Abstract
The influence of fluorine upon the annealing behavior at 450–500 °C of BF2+ implanted layers on silicon wafers was investigated by measurement of the sheet resistance, the carrier profile, and the crystallinity. The junction leakage current was also measured. Approximately one order of magnitude retardation in the average regrowth rate and lower electrical activation of implanted boron were observed in BF2+ implanted layers as compared with B+ implanted preamorphized layers. However, a leakage current level as low as 1.97×10−9 A/cm2 was measured, which is about three orders of magnitude less than reported in the literature. This result was obtained in the BF2+ implanted silicon p+n junction at an annealing temperature as low as 500 °C by employing ultraclean ion implantation techniques.