Chemical states and electrical properties of a high-K metal oxide/silicon interface with oxygen-gettering titanium-metal-overlayer

摘要

The authors report on the chemical bonding structure of the HfO_2/Si (001) stack after the SiO_2 interfacial layer (IL) is partially removed by a reactive titanium metal overlayer. Using synchrotron photoelectron spectroscopy, they found that ultrathin SiO_2-like IL ～6.5 A thick, which is significantly less than the initial SiO_2 IL thickness of ～15 A, exists at the HfO_2/Si interface with an overlying Ti electrode. The dissociated Si from SiO_2 IL is believed to go onto Si substrate where it regrows epitaxially. The interfacial trap density of the Ti-electrode sample was extracted to be ～1.6 X 10~(11) eV~(-1) cm~(-2) near the midgap of Si, which was comparable to that of the control sample with W electrode.