Interfacial optimization and enhancement of electrical properties of Ti-doped ZrO2 gate dielectric films prepared by the sol-gel method

Abstract

As the conventional gate dielectric material $\text{Si}{O}_2$ is no longer sufficient for metal-oxide-semiconductor (MOS) electronic devices, the replacement of $\text{Si}{O}_2$ with high-k material $\text{Zr}{O}_2$ has proven to be an effective strategy for further reducing device feature size. In this study, we optimized the crystallization temperature, dielectric constant, and interfacial quality of $\text{Zr}{O}_2$ thin films by exploring the appropriate Ti doping concentration. This approach addresses the issue of large leakage current in MOS capacitor applications. To easily adjust the Ti content and reduce the cost, $\text{ZrTi}{O}_x$ thin films with varying Ti concentrations were deposited on Si substrates using a sol-gel method. The effects of different Ti doping concentrations on the structural, optical, interfacial chemical, and electrical properties of the $\text{ZrTi}{O}_x$ films were systematically evaluated using various characterization techniques. The results indicate that the ZTO-12 sample exhibits an excellent dielectric constant (36.5), a large conduction band offset (2.86 eV), a small hysteresis (0.05 V), and a low leakage current density ($9.2\times {10}^{-5}A/{\text{cm}}^2$). Additionally, the leakage current conduction mechanism of the Al/ $\text{ZrTi}{O}_x$/Si capacitor was analyzed, which mainly includes ohmic conduction, Schottky emission, and Poole-Frenkel emission. In summary, the optimal Ti doping concentration is 12 %, at which point the $\text{ZrTi}{O}_x$ films exhibit excellent integrated properties. These findings will provide new insights for enhancing the performance of high-k materials in MOS electronic devices.