The Property of Ta2O5 on Chemical Vapor Deposited Ru Film Fabricated using Tris(2,4-octanedionato)ruthenium for Application to Dynamic Random Access Memory Capacitor

Abstract

Chemical vapor deposited (CVD) Ru was adopted as a bottom electrode of Ta2O5 capacitor for application to gigabit scale dynamic random access memory (DRAM). Ru film was deposited with the precursor of tris(2,4-octanedionato)ruthenium, Ru(od)3, at 260°C in O2 ambient. We obtained Ru film with 44 µΩ·cm of electric resistivity after annealing at 700°C. The root mean square (RMS) surface roughness of the film was 3.3 nm on SiO2 and 7.4 nm on TiN. We also obtained a leakage current of 4.45×10-9 A/cm2 at 1 V with a SiO2 equivalent thickness of 1.12 nm in the TiN/Ta2O5/Ru capacitor. Double plasma treatment on Ta2O5 was more effective than single plasma treatment for obtaining low leakage current. The TiN layer under Ru was oxidized into TiOx during the rapid thermal process (RTP) annealing of the Ru film at 600°C in N2 ambient. The remaining oxygen in the Ru film is believed to be an oxygen source for the oxidation of TiN.