EOT Scaling and Flatband Voltage Shift with Al Addition into TiN

Abstract

We present both EOT scaling and flatband voltage (Vfb) shift for Hf-based high-k containing metal-oxide-semiconductor capacitors (MOSCAPs) due to Al addition into the TiN metal gate. The metal gate was deposited using chemical vapor deposition (CVD) and the Hf-based high-k films were deposited using CVD or atomic layer deposition (ALD) in 300nm deposition chambers. We found that the Vfb shift amount by Al addition into TiN depends on the high-k film (HfO2 vs. HfSiON) as the shift for the HfO2 containing stack was greater than that in the HfSiON containing stack. We also examined the effect of the thermal budget of the MOSCAP flow on the Vfb shift by Al addition into TiN. We observed that the Vfb shift direction by Al addition into TiN was dependant on the MOSCAP flow (gate-first vs. gate-last like) and this Vfb shift behavior can be explained by Al-based dipole and oxygen vacancy models.