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 TiO₂-ZrO₂(TiO₂/ZrO₂ and ZrO₂/TiO₂) and Si-doped ZrO₂ (TiO₂/Si-doped ZrO₂) dielectrics. High capacitance densities (> 42 fF/ μm²), low leakage current densities (<; 5×10^-7 A/cm² 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 (TiO₂/Si-doped ZrO₂) helps to reduce leakage current density and improve reliability, with a marginal reduction in capacitance density; compared to their undoped counterparts (TiO₂/ZrO₂ and ZrO₂/TiO₂). We compare the device performance of the fabricated capacitors with other stacked high-k MIM capacitors reported in recent literature.