Comparison of Hafnium Precursors for the MOCVD of HfO2 for Gate Dielectric Applications

Abstract

Hafnium oxide films were deposited on Si (100) substrates using metal-organic chemical vapor deposition (MOCVD) and evaluated for gate dielectric applications. For this study, two types of precursors were tested: an oxygenated one, Hf butoxide-mmp, and an oxygen-free one, Hf diethyl-amide. Depositions were carried out in the temperature range of 350–650°C. However, the discussion is focused on amorphous films. The films were compared on the basis of growth rate, phase development, density, interface characteristics, and electrical properties. A similar amorphous to polycrystalline phase transition temperature was found for both precursors. For low deposition temperatures the growth rate for the amide precursor was significantly higher than for the butoxide-mmp precursor and films prepared with the amide precursor contained a lower carbon impurity content than with the butoxide-mmp one. The dielectric constant was slightly higher for amorphous HfO2 deposited from the amide precursor than for the butoxide-mmp one. Only in respect to the trap density does the butoxide precursor seem advantageous.