Effects of postdeposition annealing on physical and electrical properties of high- k Yb₂ TiO₅ dielectrics

This article describes the structure and electrical properties of a high- k ytterbium titanium oxide (Yb₂ TiO₅) gate dielectric deposited on Si(100) substrates through reactive cosputtering. X-ray diffraction, x-ray photoelectron spectroscopy, and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures ranging from 600 to 800 °C). It is found that the Yb₂ TiO₅ dielectrics annealed at 800 °C exhibited a thinner capacitance equivalent thickness of 1.65 nm, a lower gate leakage current of 38.4 nA/cm² at a gate voltage of -1 V, a smaller density of interface state of 9.61 × 10 ¹⁰ 1/cm² eV, and a relatively lower hysteresis voltage of ∼3 mV compared to those at other annealing temperatures. These results are attributed to the formation of a rather well-crystallized Yb₂ TiO₅ structure, composition, and a smooth surface. This film also shows almost negligible charge trapping under high constant voltage stress.