New ALD processes for hafnium silicate films have been developed at Aviza Technology by co-injection of tetrakis(ethylmethylamino)hafnium and tetrakis(ethylmethylamino)silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400°C to grow HfₓSi₁₋ₓO₂ films. Film characterization, including film density, crystallinity, and thermal anneal effect, was performed on five 20 nm thick HfₓSi₁₋ₓO₂ films where x = 0.2, 0.4, 0.6, 0.8, 1.0. X-ray measurements revealed the film densities and thicknesses for the as-deposited and 1000°C annealed samples. The densification with anneals seen in the optical measurements were confirmed. The as-deposited amorphous HfO₂ and Hf<sub>0.8</sub>Si<sub>0.2</sub>O₂ were crystallized after a 600°C anneal. The HfO₂ formed the well known monoclinic phase while the silicate formed a face-centered-cubic (fcc) structure. This fcc phase has only recently been mentioned in the literature .