Optimized electrode and interface for enhanced reliability of high-k based metal-insulator-metal capacitors

This paper focuses on zirconia and TiN based MIM buffer capacitors integrated in immediate vicinity to the Si substrate. Process variations and integration schemes are investigated regarding their influence on capacitance, leakage current and reliability characteristics. Especially, the effect of interface pre-treatments between the Si substrate and the bottom electrode as well as processing conditions of the TiN top electrode is studied in detail. It is shown that the reliability of high-k MIM capacitors is significantly dominated by the kind of pre-treatment of the Si substrate and also by the deposition temperature of the metal nitride top electrode. As a result, it is recommended to introduce chemical oxidation of the substrate before MIM deposition as well as lowering the deposition temperature to about 400 °C for the top TiN electrode in order to enhance the lifetime of the MIM dielectric.