Composition Control of Ni Silicide by Chemical Vapor Deposition Using Ni(PF3)4 and Si3H8

Ni silicide film was deposited by chemical vapor deposition (CVD) using an Ni(PF3)4/Si3H8 gas system. Ni(PF3)4 has no carbon atoms in its molecules and has sufficiently high vapor pressure for a mass flow controller to be used. We selected Si3H8 as the silicon precursor, which was decomposed by the interaction of a metalorganic Ni precursor at a low temperature at which thermal decomposition could not occur. Using these precursors, Ni silicide film was deposited at low temperatures (~160 °C). The deposited Ni silicide film was polycrystalline and had low crystallinity. Ni2Si and Ni5Si2 were also formed. Varying the Si3H8 flow rate and substrate temperature changed the Si/Ni ratio of the films resulting in the flat-band voltage (Vfb) for the Ni silicide electrode shifting with the Si/Ni ratio. This CVD-deposited Ni silicide should be able to be applied to the fabrication of metal gate in future metal oxide semiconductor field-effect transistors (MOSFETs).