Synthesis and Properties of SrRuO3 and RuO2 Thin Films Using Metalorganic CVD

• Main Authors: Hung Chih Lee, 李鴻志
• Other Authors: Dah-Shyang Tsai
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/85370671627430898006

碩士 === 國立臺灣科技大學 === 化學工程系 === 89 === Synthesis of strontium ruthenate and ruthenium oxide thin films have been carried out in a hot-wall tubular reactor, using Ru(C5H5)2 and Sr(DPM)2 precursors. The reactivity of Ru(C5H5)2 is much higher than that of Sr(DPM)2, and so is its volatility. Growth temperature of ruthenium oxide can be as low as 275C, yet the lowest temperature for growing strontium oxide is 410C. The vast difference in growth temperatures makes the stoichiometric control of two oxides difficult if the simultaneous sublimation and deposition is applied. RuO2 tends to deposit at upstream positions, while SrO deposits at downstream positions. Therefore, RuO2 and SrO are sublimed and deposited at separate temperatures. It is of interest to find that the deposition sequence is an important factor. If the deposition sequence is RuO2-SrO, single phase of SrRuO3 can be synthesized after 700C annealing. On the other hand, if the sequence is SrO-RuO2, mixed phases of RuO2, SrRuO3 and SrCO3 after 800C annealing. The incomplete solid state reaction is owing to the dense SrO film that poses an obstacle for RuO2 diffusion, while the open microstructure of columnar RuO2 film is much easier for SrO diffusion. The room-temperature film resistivity of SrRuO3 with Ru/(Sr+Ru)=0.5 is 910 -cm. The room-temperature film resistivity of SrRuO3 decreases with the increasing Ru content, 479 -cm at Ru/(Sr+Ru)=0.53, 280 -cm at Ru/(Sr+Ru)=0.55. The surface roughness of SrRuO3 film is minimum at 700C annealing temperature. The root mean square roughness of 700C is 21.9 nm. The RuO2 thin film is featured with columnar microstructure. The resistivity of RuO2 thin film decreases with its growth temperature, the room temperature resistivity is 252 -cm for 295C-grown film and 47-cm for 355C-grown film. The reduction in resistivity is attributed to the less electron scattering at grain boundaries of large-grain film that is grown at high temperatures. The average grain size of RuO2 film increases with the deposition temperature, 59 nm (275C) to 253 nm (355C). The root mean square roughness of RuO2 generally increases with the deposition temperature, 12 nm (315C) to 35 nm (355C).