Role of oxygen states in high-K gate stack engineering

Fundamental properties of SiO
₂
and high-k dielectrics are compared, and the differences can be used to explain physical phenomena in high-k gate stacks. Interfacial reactions and gate Fermi-level pinning arise from the ionic nature of oxygen states in high-k dielectrics. Film crystallization is actually preferable for high-k gate dielectrics due to their lack of bond flexibility, while phase separation in silicates must be avoided because it leads to severe degradation of film properties