Synthesis of bgr;hyphen; and agr;hyphen;FeSi2phases by Fe ion implantation into Si using metal vapor vacuum arc ion source

摘要

Highhyphen;current Fe ion implantation technique was employed to synthesize Fehyphen;silicide layers on Si wafers, using a newly constructed metal vapor vacuum arc ion source. The Fe ions were extracted at a voltage of 40 kV with a varying ion current density from 65 to 152 mgr;A/cm2and a nominal ion dose varied from 3times;1017to 3times;1018Fe/cm2. At a fixed nominal dose of 4times;1017Fe/cm2, a semiconducting bgr;hyphen;FeSi2layer gradually grew on Si with increasing ion current density and a qualified bgr;hyphen;FeSi2layer with a relative sharp interface was obtained, when the ion current densities exceeded 115 mgr;A/cm2. While implanting at a fixed ion current density of 152 mgr;A/cm2with varying ion dose, the bgr;hyphen;FeSi2phase began to form first at a nominal dose of 3times;1017Fe/cm2, and eventually transformed into a metallic agr;hyphen;FeSi2phase when the nominal dose reached 3times;1018Fe/cm2. Further information of the formation of Fe disilicides was obtained by comparing the postannealing results of some of the implanted wafers with those observed immediately after implantation. The formation mechanism of the Fe disilicides is discussed in terms of the beam heating effect, which in turn resulted in a simultaneous thermal annealing during Fe ion implantation.