Stability of RuO_2 Bottom Electrode and its Effect on the Ba-Sr-Ti Oxide Film Quality

摘要

We have performed the thermodynamic calculations to evaluate the thermal stability of RuO_2 film and its effect on the BST film quality in MOCVD process. The degradation of RuO_2 occurs in two different reaction pathways depending on process conditions. One is the simple decomposition of RuO_2 producing metallic Ru and gaseous oxygen, which mainly happens when no excess O_2 is present in the feed at low pressures. The other is the etching of RuO_2 film by excess O_2 in the gaseous stream, which produces RuO_3 and RuO_4 species. The calculation results on Ba-Sr-Ti-Ru-C-H-O system also present the optimal feed composition and process conditions that result the high-quality (Ba,Sr)TiO_3 film.