F-enhanced morphological and thermal stability of NiSi films on BF2+-implanted Si(001)

The morphological and thermal stability of conducting NiSi films formed on Si(001) are significantly enhanced by pre-implantation of the Si wafer with ${\mathrm{BF}}_2^{+}.$ In the absence of F, the maximum silicidation temperature $T_{\max }$ is 650 °C; higher temperatures lead to the formation of the competing high-resistivity ${\mathrm{NiSi}}_2$ phase. $T_{\max },$ however, is increased to ⩾750 °C during NiSi formation on Si(001) implanted with 20 keV ${\mathrm{BF}}_2^{+}$ at a dose of ${\text{5×10}}^{15}\hspace{0.17em}{\mathrm{cm}}^{\text{−2}}.$ The observed enhancement in NiSi thermal stability is due to F segregation to the silicide/Si(001) interface and silicide grain boundaries, which retards NiSi grain growth, leading to much smoother layers, and inhibits ${\mathrm{NiSi}}_2$ nucleation.