Taishi Furukawa

Fabrication of Ir-Based Electrodes by Metal Organic Chemical Vapor Deposition Using Liquid Ir Precursors

Ir-based electrodes were fabricated by metal organic chemical vapor deposition (MOCVD) using a newly developed liquid precursor, (ethylcyclopentadienyl)bis(ethylene) iridium [Ir(EtCp)(C2H4)2], with a lower decomposition temperature than previous precursors, (ethylcyclopentadienyl)(1,5-cyclooctadiene) iridium [Ir(EtCp)(COD)] and (ethylcyclopentadienyl)(1,3-cyclohexadiene) iridium [Ir(EtCp)(CHD)]. Film growth behavior during MOCVD using Ir(EtCp)(C2H4)2 was investigated and compared with that using Ir(EtCp)(COD) and Ir(EtCp)(CHD). When Ir(EtCp)(C2H4)2 was used, significantly higher nucleation was observed at the initial growth stage than that using Ir(EtCp)(COD) and Ir(EtCp)(CHD) owing to the lower thermal decomposition temperature of 220 °C. Ir, IrO2 and Ir/IrO2 films were successfully prepared using Ir(EtCp)(C2H4)2 on underlying SiO2, TiN and Pb(Zr,Ti)O3, showing that Ir-based top and bottom electrodes can be fabricated by MOCVD. The root-mean-square surface roughnesses and electrical resistivities of Ir and IrO2 films on SiO2 were 2.2 nm and 9.4 µΩcm, and 3.3 nm and 1.8×102 µΩcm, respectively. The step coverages of Ir films prepared at 230–400 °C were 35–45%.

PROPERTIES OF A NOVEL BISMUTH PERCURSOR FOR MOCVD

ABSTRACT A novel liquid bismuth precursor dimethyl(2-N,N-dimethylaminomethylphenyl)bismuth, BiMe2(Me2NCH2Ph), was synthesized and its physical properties were examined. BiMe2(Me2NCH2Ph) showed physical properties suitable for metalorganic chemical vapor deposition (MOCVD) and is a nonexplosive compound. It exhibited enough vapor pressure (0.1 Torr/55°C), excellent volatility, and adequate decomposition temperature. As films preparation, Bi4Ti3O12 thin films could be prepared by MOCVD using BiMe2(Me2NCH2Ph) Ti(OiC3H7)4 and O2 gas as starting materials. Other bismuth-contained oxide films can be also prepared by using BiMe2(Me2NCH2Ph).

A Novel Iridium Precursor for MOCVD

A novel liquid iridium precursor (1,3-cyclohexadiene)(ethylcyclopentadienyl)iridium, Ir(EtCp)(CHD), was synthesized and its physical properties examined. Ir (EtCp) (CHD) showed physical properties suitable for metalorganic chemical vapor deposition (MOCVD). It exhibited enough vapor pressure (0.1 Torr/75°C), excellent volatility, and adequate decomposition temperature. The characteristics of Ir films deposited by MOCVD method using Ir(EtCp)(CHD) and a conventional Ir precursor (1,5-cyclooctadiene) (ethylcyclopentadienyl) iridium Ir(EtCp)(COD) were compared. The Ir films grown using Ir(EtCp)(CHD) showed shorter incubation time and higher nucleation density than those from Ir(EtCp)(COD) at initial growth stage of deposition. 3

Characterization of Ru thin films from a novel CVD/atomic layer deposition precursor “Rudense” for capping layer of Cu interconnects

The authors have succeeded in development of a novel Ru precursor, Ru(EtCp)(η5-CH2C(Me)CHC(Me)O) [Rudense], for CVD and atomic layer deposition (ALD) processes under nonoxidative condition. Rudense has sufficient vapor pressure and good thermal stability (decomposition temperature = ca. 230 °C). Ru thin films were grown on Pt, Ru, Si, and SiO2 substrates using Rudense and NH3 as Ru precursor and reactant, respectively. Rudense gave the conformal, low-impurity (<1021 atoms/cc), and low-resistivity (16 μΩ cm) Ru thin films. Moreover, Rudense showed substrate selectivity; therefore, Rudense will be a candidate for area-selective CVD and ALD precursor for Ru capping layers of Cu interconnects.