Study of dielectric properties in stacked high-k dielectric metal oxide semiconductor capacitor (MOSCAP) devices

With the current technology having reached the physical limits of size downscaling, efforts need to be made toward the development of new dielectric materials to ensure a low leakage current density that can prevent the tunneling of charges through the dielectric layer. The tunneling of the charges through the dielectric layer is a major factor for degradation in performance as well as higher power consumption. Therefore, recent research has been focused on using materials with high dielectric constants and low leakage characteristics. In this work, we present a detailed study on ZrO₂ and Ta₂O₅ as potential high-k dielectric replacements. MOSCAP devices fabricated using high-k materials have been investigated to study their dielectric properties. Furthermore, a stacked bilayer structure of ZrO₂ and Ta₂O₅ was also investigated to alleviate some of the issues that come along with using high-k dielectrics instead of the more conventional SiO₂ dielectric thin film. ZrO₂ and Ta₂O₅ dielectric thin films were successfully fabricated on N⁺⁺ doped silicon substrates using the electron beam evaporation technique displaying dielectric constants of 20 and 34, respectively. The fabricated MOSCAP devices exhibited leakage current densities as low as 10^–8 A/cm².