High-Performance Metal–Insulator-Metal Capacitor Using Stacked $hbox{TiO}_{2}/hbox{Y}_{2}hbox{O}_{3}$ as Insulator

摘要

Metal-insulator-metal (MIM) capacitors with single $hbox{TiO}_{2}$ and a $hbox{TiO}_{2}/hbox{Y}_{2}hbox{O}_{3}$ stack as an insulator are explored in this letter. It is found that, at the process temperature higher than 400 $^{circ}hbox{C}$, $ hbox{TiO}_{2}$ MIM capacitors demonstrate a high capacitance density at the price of an unacceptably high leakage current and voltage coefficient of capacitance (VCC). On the other hand, with the process temperature of 500 $^{circ}hbox{C}$, $hbox{TiO}_{2}/hbox{Y}_{2}hbox{O}_{3}$ MIM capacitors display desirable characteristics in terms of a large capacitance density of 32.2 $ hbox{fF}/muhbox{m}^{2}$, a low VCC of 3490 $hbox{ppm}/ hbox{V}^{2}$, small frequency dispersion, and a low leakage current of $hbox{4.5}! times! hbox{10}^{-9} hbox{A}/hbox{cm}^{2}$ at $-$1 V. The $hbox{Y}_{2} hbox{O}_{3}$ film not only provides a high dielectric–electrode band offset but also possesses high thermal stability against crystallization; both are important to suppress leakage current. In addition, the $hbox{Y}_{2}hbox{O}_{3}$ film prevents a $hbox{TiO}_{2}$ film f-n-nrom crystallization at 500 $^{circ}hbox{C}$ due to the increased entropy caused by incorporated Y atoms, and the amorphous $hbox{TiO}_{2}$ film offers a high $kappa$ value to achieve a large capacitance density without sacrificing leakage current and VCC.