PVD grown high-k SrTiO3 for capacitor applications: reliability and leakage current behavior

Low rate rf-sputtering was used to grow a 12 nm SrRuO3/SrTiO3/ SrRuO3 thin film capacitor with high dielectric constant and low leakage current behavior. Leakage current analysis and time dependent dielectric breakdown (TDDB) measurements as a function of temperature were performed. Poole-Frenkel emission and trap assisted tunneling were found to explain the leakage current behavior at different electric field ranges. Shallow trap levels between 0.75-0.85 eV below the conduction band were found whereas at higher temperatures conduction is governed by deeper traps at 1.2 eV. Constant voltage stress (CVS) measurements indicate that electron trapping is predominant and stress induced leakage current occurs before hard breakdown. Based on the Weibull model a projected lifetime of several years was obtained at product conditions. The high lifetime in combination with a high effective permittivity of approximately 200 making it a promising candidate for future DRAM applications.