Interface structure of HfNx/SiO2 stack grown by MOCVD using TDEAHf precursor

Hafnium nitride (HfNx) thin films were fabricated for the gate electrode application by metal organic chemical vapor deposition (MOCVD) using tetrakis-diethylamido hafnium (TDEAHf) precursor and NH3 reactant. The characterization and control for the interface between HfNx film and SiO2 substrate were investigated using both XPS and TEM techniques. As a result, HfNx films with low impurities of O and C and smooth interface were prepared on SiO2 substrates; a thin hafnium silicate (HfOxSiy) interlayer was verified to form between HfNx and SiO2. It may result from the interfacial reaction at the initial growth stage. In addition, the interlayer growth was found to be nearly independent of the growth temperature and the length of growth time, but greatly on the precursor partial pressure, which promises an expected capability to engineer the interfacial characteristics.