Control of the interfacial layer thickness in hafnium oxide gate dielectric grown by PECVD

The HfO2 thin films for use in gate dielectric applications were deposited at 300degreesC onto p-type Si(100) substrates using Hf[OC(CH3)(3)](4) as the precursor in the absence of oxygen by plasma-enhanced chemical vapor deposition (PECVD). The HfO2 films deposited in the absence of O-2 show excellent electrical properties such as low equivalent oxide thickness (EOT) and good thermal stability. The deposited films have an interfacial layer of approximately 10 Angstrom in thickness, resulting in a decrease in the thickness of the interfacial layer by about 50% compared to films deposited in the presence of oxygen. The leakage current density of HfO2 films was approximately four orders of magnitude lower than an electrically comparable SiO2 at the same EOT. The improvement of electrical properties can be attributed to the decrease in the SiO2 interfacial layer. The thickness of the interfacial layer can be controlled by deposition in the absence of oxygen after evacuation of the reaction chamber by means of an ultrahigh vacuum. (C) 2003 The Electrochemical Society.