Chemical vapor deposition of HfO2 thin films using a novel carbon-free precursor

HfO2 thin films were deposited on Si wafers by a chemical vapor deposition (CVD) technique at temperatures ranging from 200 to 400 degreesC using a new carbon-free precursor [Hf(NO3)(4)]. The growth behavior was under a steady state when the interfacial oxide layer was excluded in film thickness estimation by ellipsometry. The as-grown interfacial layer formed at 200 degreesC was apparently composed of Hf, Si, and O. Postannealing under a N-2 atmosphere at temperatures >500 degreesC resulted in a decrease in interfacial layer thickness by decomposition of the Hf-Si-O layer to SiO2 and HfO2. The HfO2 film showed a crystalline microstructure even in the as-deposited state when the film thickness was 170 Angstrom. However, the films were amorphous when the film thickness was <70 <Angstrom>. The dielectric constant of the as-deposited and postannealed HfO2 thin films were approximately 18 and 22, respectively. (C) 2001 The Electrochemical Society.