Ultrathin Ta2 O 5 Film Capacitor with Ru Bottom Electrode

The characteristics of the ultrathin Ta 2 O 5 film capacitors with Ru bottom electrodes have been investigated. Ru films are deposited on n-Si by sputtering in 10% O 2 /Ar ambient, for the bottom electrode, and Ta 2 O 5 films are deposited by chemical vapor deposition using Ta(OC 2 H 5 ) 5 and O 2 . By O 2 plasma treatment at 400°C after N 2 thermal treatment at 700°C, excellent properties, are obtained such that the effective SiO 2 film thickness is 0.68 nm for 6 nm thick Ta 2 O 5 film and the leakage current is less than 1 × 10 8 A/cm 2 between the range of -2.1 and +1.8 V. The Ta 2 O 5 film with a Ru bottom electrode is one of the most suitable structures for Gbit dynamic random access memory capacitors.