Investigation of polycrystalline nickel silicide films as a gate material

The work function of polycrystalline nickel silicide film formed by rapid t hermal annealing (RTA) has been studied using capacitance-voltage (C-V) mea surements and metal-oxide semiconductor (MOS) structures. The effect of sin tering temperature on work function has also been studied. Results show tha t the work function of n(+)-doped NiSi gate is about 4.6 eV and is stable f rom 400 to 800 degreesC. For p(+)-doped NiSi gate, the work function is 5 e V. The gate-substrate leakage current is small and the oxide quality is sim ilar to that in Al-gate MOS capacitors even for oxides as thin as 8 nm. The poly-gate depletion effect (PDE) has also been investigated by quasi-stati c C-V. Compared with that of poly-Si and poly-Si1-xGex, no PDE is observed in silicide-gate n-MOS device even when the gate is undoped. The results su ggest that nickel silicide film may be used as a potential gate material in complementary MOS or thin-film transistor devices. (C) 2001 The Electroche mical Society.