Electrical characterization of Ru-and RuO2/Ta2O5 gate stacks for nanoscale DRAM technology

Author

M. Tapajna;E. Dobrocka;A. Paskaleva;K. Husekova;E. Atanassova;K. Frohlich

Author_Institution

Institute of Electrical Engineering, Centre of Excellence CENG, Slovak Academy of Sciences, D?bravsk? cesta 9, 841 04 Bratislava, Slovakia. e-mail: milan.tapajna@savba.sk

fYear

2008

Firstpage

267

Lastpage

270

Abstract

Electrical properties of metal-oxide-semiconductor structures composed of MOCVD grown Ru or RuO₂ metal gates, rf sputtered Ta₂O₅ oxide layers, and nitrided Si was investigated. The dielectric constant of Ta₂O₅ as extracted from capacitance-voltage characteristics was found to be 24 and 28 for Ru and RuO₂ gated structures, respectively. Interfacial SiO₂-like layer with a thickness of ~2 nm was observed from X-ray reflectivity analysis. The effective work functions of Ru and RuO₂ in contact with Ta₂O₅ were found to be 4.65 and 4.8 eV, respectively. Temperature dependent current-voltage measurements indicate the transition from the Pool-Frenkel emission (or thermionic field emission) to the field emission conduction mechanism in combination with the direct tunneling across the SiO₂-like interfacial layer under gate as well as substrate injection.

Keywords

"Capacitance-voltage characteristics","Metal-insulator structures","Temperature measurement","Dielectric substrates","Random access memory","MOCVD","Thickness measurement","Sputtering","Reflectivity","Current measurement"

Publisher

ieee

Conference_Titel

Advanced Semiconductor Devices and Microsystems, 2008. ASDAM 2008. International Conference on

Print_ISBN

978-1-4244-2325-5

Type

conf

DOI

10.1109/ASDAM.2008.4743334

Filename

4743334