Hf1 xSixOy dielectric films deposited by UV-photo-induced chemical vapour deposition (UV-CVD)

Hf1 xSixOy is an attractive candidate material for high-k dielectrics. We report in this work the deposition of ultra-thin Hf1 xSixOy films (0.1 x 0.6) on silicon substrate at 450 8C by UV-photo-induced chemical vapour deposition (UV-CVD) using 222 nm excimer lamps. Silicon(IV) and hafnium(IV) organic compounds were used as the precursors. Films from around 5 to 40 nm in thickness with refractive indices from 1.782 to 1.870 were grown. The deposition rate was found to be of 6 nm/min at a temperature of 450 8C. The physical, interfacial and electrical properties of hafnium silicate (Hf1 xSixOy) thin films were investigated by using X-ray photoelectron spectroscopy, ellipsometry, FT-IR, C–V and I–V measurements. XRD showed that they were basically amorphous, while Fourier transform infrared spectroscopy (FT-IR), clearly revealed Hf–O–Si absorption in the photo-CVD deposited Hf1 xSixOy films. Surface and interfacial properties were analysed by TEM and XPS. It is found that carbon content in the films deposited by UV-CVD is very low and it also decreases with increasing Si/(Si + Hf) ratio, as low as about 1 at.% at the Si/(Si + Hf) ratio of 60 at.%.