Two-step annealing effects on ultrathin EOT higher-k (k = 40) ALD-HfO2 gate stacks

We fabricated ultrathin HfO
₂
gate stacks of very high permittivity by atomic layer deposition (ALD) and novel two-step post-deposition annealing (PDA) technique. First, no-cap PDA degasses residual contaminations in ALD layer, and second, Ti-cap PDA enhances permittivity of HfO
₂
by generating cubic crystal phase without SiO
₂
interfacial layer growth. Using these techniques, the dielectric constant of the ALD-HfO
₂
can be enhanced to ~40, and a 0.3 nm equivalent oxide thickness is obtained.