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

Metal-insulator-metal (MIM) capacitors with single TiO
₂
and a TiO
₂
/Y
₂
O
₃
stack as an insulator are explored in this letter. It is found that, at the process temperature higher than 400°C, 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°C, TiO
₂
/Y
₂
O
₃
MIM capacitors display desirable characteristics in terms of a large capacitance density of 32.2 fF/μm
²
, a low VCC of 3490 ppm/ V
²
, small frequency dispersion, and a low leakage current of 4.5 × 10
^-9
A/cm
²
at -1 V. The Y
₂
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 Y
₂
O
₃
film prevents a TiO
₂
film from crystallization at 500°C due to the increased entropy caused by incorporated Y atoms, and the amorphous TiO
₂
film offers a high κ value to achieve a large capacitance density without sacrificing leakage current and VCC.