Oxygen Diffusion Barriers for High-Density FeRAMs

• Published in: Integrated ferroelectrics Vol. 47; no. 1; pp. 79 - 88
• Main Authors: Moon, B. K., Pinnow, C. U., Imai, K., Arisumi, O., Itokawa, H., Hornik, K., Tsutsumi, K., Hilliger, A., Kunishima, I., Nagel, N., Yamakawa, K., Beitel, G.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.01.2002
• Subjects: Capacitor Over Plug; Feram; Hysteresis; Iro 2; Oxygen Barrier; Pzt; Rapid Thermal Annealing; Rto; Sputter
• ISSN: 1058-4587; 1607-8489
• DOI: 10.1080/10584580215412

For high-density ferroelectric random access memories (FeRAMs) with capacitor over plug (COP) structure, oxygen diffusion barriers have been investigated. This paper describes the excellent properties of two newly developed diffusion barriers, which are based on a) stoichiometric-IrO 2 films and b) surface treated Ir-films. The IrO 2 barrier was successfully optimized by forming stoichiometric IrO 2 , by deposition temperature control and by decreasing mechanical stress. Surface treatment of Ir-metal layer by using RTO (rapid thermal oxidation) was very effective for obtaining excellent barrier properties, which could be further improved by repeated deposition and RTO treatment leading to bi- or multilayer structures. When applied to fully stacked-PZT capacitors, both barrier types inhibited the oxidation of an underlying W-plug even after annealing at 650C for 2 hours in oxygen ambient. Q sw values of PZT capacitors were around 30 w C/cm 2.