Implementation of rutile-TiO2 thin films on TiN without post-annealing through introduction of SnO2 and its improved electrical properties

Abstract

Rutile-TiO2 has been actively studied as a high-k candidate for next-generation dynamic random-access memory (DRAM) capacitors due to its higher dielectric constant compared to commercially used ZrO2 and HfO2 based dielectrics. However, because the thermodynamic stabilization temperature of rutile-TiO2 is above 750 °C, which is not acceptable for the DRAM process, noble metal-based functional electrodes, such as RuO2 have been indispensably used for the formation of rutile-TiO2 thin films. The proposed method suggests the strategic introduction of Sn to reliably achieve mass production of rutile-TiO2 thin film on TiN electrodes. However, the atomic layer deposition (ALD) process with a commercially employed Sn precursor had issues such as requiring additional thermal process for crystallization due to low process temperature or generating a reducing by-product. Therefore, in this study, we realized rutile-TiO2 thin films on TiN electrodes without an additional post-thermal process using a new Sn precursor capable of high-temperature deposition. By employing an optimized Sn-doped TiO2 on seed layer, it was possible to implement a high dielectric constant of over 100, and the leakage current improvement effect was also confirmed. Therefore, the process presented in this study suggests a direction for future high-k research on next-generation DRAM capacitors. © 2023 Elsevier B.V.