HfO2/Si and HfSiO/Si Structures Fabricated by Oxidation of Metal Thin Films

Abstract

Hafnium metal deposition followed by oxidation, either on bare silicon or SiO2/Si substrates, was performed for the fabrication of high-k/Si gate stacks with small equivalent oxide thickness values. HfO2/Si structures were fabricated without substrate heating but with the electron cyclotron resonance (ECR) plasma oxidation of Hf metal deposited on bare Si substrates by DC magnetron sputtering. These HfO2/Si structures have ideal abrupt interface without interfacial layer (IL)-SiO2 and silicide layers, as determined by an X-ray photoelectron spectroscopy (XPS) measurements. A direct stacking was induced by the characteristic film growth of ECR plasma in a buried interfacial region. On the other hand, on SiO2/Si substrates, the HfSiO/Si structures were successfully fabricated by thermal treatment for both the interdiffusion of Hf metal and SiO2, and the oxidation of the layer. The HfSiO/Si structures show small leakage currents because of high barrier heights and have no hafnium silicide layer.