Performance Enhancement of TiO2-Based Capacitors via Plasma-Enhanced Atomic Layer Deposition and Plasma Pre-Treatment

As dynamic random-access memory (DRAM) devices continue to scale, reducing the equivalent oxide thickness (EOT) of capacitors and achieving precise control of the dielectric-electrode interface have become critical challenges. TiO₂ has emerged as a promising high-k dielectric material due to its crystalline phases, anatase (dielectric constant of 30-75) and rutile (dielectric constant of 90-170). However, its application is limited by high leakage current that arises from the low conduction band offset with conventional electrodes. In particular, the low-temperature formation of rutile TiO₂ is strongly influenced by lattice mismatch with the bottom electrode. Interface engineering strategies, such as the introduction of RuO₂ layers on Ru electrodes, have been proposed to mitigate this issue. In this work, TiN, a bottom electrode widely adopted in mass-production processes, was employed to enhance the electrical performance of TiO₂-based capacitors through systematic interface control. The effects of different TiN deposition methods on substrate properties were investigated, and argon plasma treatment was introduced to tailor the dielectric-electrode interface and promote rutile TiO₂ formation. Both the TiN bottom electrode and the TiO₂ dielectric layer were deposited using plasma-enhanced atomic layer deposition to ensure high film quality. As a result, the leakage current density was suppressed to approximately 10⁻⁵A/cm² at 0.8V, while the EOT was reduced to 1.32nm. These results indicate that the crystallization behavior of TiO₂ thin films strongly depends on dielectric thickness and substrate crystallinity. The findings provide important guidelines for developing TiO₂-based high-k dielectric thin films for advanced capacitor applications.