Structure and stability of alternative gate dielectrics for Si CMOS

The thermodynamic analysis of both interfacial SiO₂ and silicide reactions, and phase separation of HfO₂ and ZrO₂ are performed. The analysis includes gaseous species, because typical gate dielectrics are ultra-thin layers and diffusivities for species from the surrounding atmosphere, such as oxygen, may be high. Calculations for the ZrO₂-SiO₂ show that compositions between ∼45 mol% and ∼90 mol% SiO₂ lie within the metastable extension of the spinodal at typical annealing temperatures of 1000 C. Grazing-incidence small-angle X-ray scattering (GISAXS) and high-resolution transmission electron microscopy (HRTEM) are used to investigate phase separated microstructure in hafnium silicate films after rapid thermal annealing between 700 and 1000 C.