Control of the Interfacial Layer Thickness in Hafnium Oxide Gate Dielectric Grown by PECVD

The HfO 2 thin films for use in gate dielectric applications were deposited at 300°C onto p-type Si(100) substrates using Hf [ OC ( CH 3 ) 3 ] 4 as the precursor in the absence of oxygen by plasma-enhanced chemical vapor deposition (PECVD). The HfO 2 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 Å 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 HfO 2 films was approximately four orders of magnitude lower than an electrically comparable SiO 2 at the same EOT. The improvement of electrical properties can be attributed to the decrease in the SiO 2 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.