Extremely Scaled Equivalent Oxide Thickness of High-k (k=40) HfO2 Gate Stacks Prepared by Atomic Layer Deposition and Ti Cap Anneal

We fabricate ultra-thin HfO2 gate stacks of very high permittivity value by using atomic layer deposition (ALD) and Ti-cap post deposition annealing. The HfO2 layer is directly deposited on hydrophilicized Si surface by ALD. A cubic crystallographic phase is generated in ALD-HfO2 by short time annealing with Ti capping layer. The Ti layer absorbs residual oxygen in HfO2 layer. The reduced oxygen concentration during annealing suppresses the growth of the interfacial SiO2 layer. The dielectric constant of ALD-HfO2 is enhanced to ～40, and extremely scaled ～0.2 nm equivalent oxide thickness of total gate stack is obtained.