High-temperature amorphous hafnia (HfO₂) for microelectronics

We have found that a hafnia precursor (hafnium bis-isopropoxy bis-thd) for chemical solution deposition (CSD) yields a crystallization temperature ca. 80°C above that usually found for CSD film deposition (e.g., 521°C for Hf-butoxide). These results are considered in terms of two models: the coordination oligomerism model of Turova and Yanovskaya, and a model of competing surface assembly mechanisms from monomeric precursors; although both are compatible with Raman data on film crystallisation temperatures, DTA/TG results on bulk samples support the competing surface assembly model, as do differing values of surface roughness for the different precursors. Implications for commercial production of hafnia gate oxides capable of withstanding conventional FET front-end processing are emphasised.