PROBING POINT DEFECTS IN STACKS OF ULTRATHIN HIGH-K METAL OXIDES ON SEMICONDUCTORS BY ELECTRON SPIN RESONANANCE: THE Si/HfO_2 vs THE Ge/HfO_2 SYSTEM

摘要

Combined electron spin resonance and electrical analysis of (100)Si/HfO_2 and (100)Ge/HfO_2 interfaces reveals dramatic differences in their interface defect properties. No interfacial Ge dangling bond type defects could be revealed. The observed paramagnetic defects do not correlate with the slow acceptor states dominating the Ge/insulator trap spectrum, and are resistant to passivation. The dangling bond type defects observed, upon hydrogen detachment, at the (100)Si/HfO_2 interfaces are the trivalent Si defects common for Si/SiO_2 interfaces, P_(b0) and P_(b1) centers. The density of the Pbo is higher than in the (100)Si/SiO_2 structures and is sensitive to the deposition process. However, the density can be significantly reduced by annealing of the Si/HfO_2 structures in O-containing ambient, likely through re-establishing the Si/SiO_2 interface. Also, the Pb-type centers can be entirely passivated by hydrogen already at 400 °C. The density of fast interface states closely follows the variations in the Pbo center density, suggesting it as the dominant contribution to the fast interface states.