Structure and stability of alternative gate dielectrics for Si CMOS

The thermodynamic analysis of both interfacial SiO/sub 2/ and silicide reactions, and phase separation of HfO/sub 2/ and ZrO/sub 2/ 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 ZrO/sub 2/-SiO/sub 2/ show that compositions between /spl sim/45 mol% and /spl sim/90 mol% SiO/sub 2/ 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.