Investigation of Multilayer TiNi Alloys as the Gate Metal for nMOS In0.53Ga0.47As

Abstract

To achieve low power consumption for CMOS devices, the gate metals must have effective work function (EWF) aligned with the band edges of the channel material and have a small WF variation (WFV). The multilayer TiNi alloys have been successfully applied as the gate metals for HfO2/In0.53Ga0.47As MOS devices in this paper. The EWF of TiNi alloys was found to increase from 4.41 eV for as-deposited sample to 4.62 eV after the alloy was annealed due to the diffusion of Ni atoms into Ti layer. The multilayer TiNi alloy remained amorphous phase with small WFV until annealed at 600 degrees C. The TiNi alloy is thermally more stable as compared with either Ti or Ni metal, because the TiOxNi interfacial layer prevents the diffusion of Ni atoms into HfO2 film and the further reaction of Ti with HfO2. The results can be applied for InGaAs nMOS fabrication.