High-performance stacked TiO2-ZrO2 and Si-doped ZrO2 metal-insulator-metal capacitors

Metal-insulator-metal (MIM) capacitors for DRAM applications have been realised using stacked TiO
₂
-ZrO
₂
(TiO
₂
/ZrO
₂
and ZrO
₂
/TiO
₂
) and Si-doped ZrO
₂
(TiO
₂
/Si-doped ZrO
₂
) dielectrics. High capacitance densities (> 42 fF/ μm
²
), low leakage current densities (<; 5×10
^-7
A/cm
²
at -1 V), and sub-nm EOT (<; 0.8 nm) have been achieved. The effects of constant voltage stress on the device characteristics is studied. The structural analysis of the samples is performed by X-ray diffraction measurements, and this is correlated to the electrical characteristics of the devices. The surface chemical states of the films are analyzed through X-ray photoelectron spectroscopy measurements. The doped-dielectric stack (TiO
₂
/Si-doped ZrO
₂
) helps to reduce leakage current density and improve reliability, with a marginal reduction in capacitance density; compared to their undoped counterparts (TiO
₂
/ZrO
₂
and ZrO
₂
/TiO
₂
). We compare the device performance of the fabricated capacitors with other stacked high-k MIM capacitors reported in recent literature.