Sputtered (Ba, Sr)TiO3 (BST) thin film capacitors have been fabricated with thick RuO2/TiN-based storage electrodes and poly-Si contact plugs, and the electrical properties of the storage electrodes have been studied. The electrode height was higher than 450 nm and the contact size was 0.8×0.8 µ m2. Resistance of the storage electrodes including contact plugs can be evaluated from the dispersion observed in capacitance-frequency measurements. TiN oxidation at the RuO2/TiN interface and native oxide at the TiN/Si contact contribute to the electrode resistance of RuO2/TiN electrodes. With increasing BST deposition temperature, the thickness of oxidized TiN in RuO2/TiN electrodes increases and the electrode resistance increases correspondingly. A Ru layer inserted at the RuO2/TiN interface, a T i N/T i S i 2/S i junction and rapid thermal annealing in N2 ambient of the TiN layer are effective ways to reduce the resistance of RuO2/TiN-based electrodes.

We describe the formation of ultrathin tantalum oxide capacitors, using rapid thermal nitridation of the storage-node polycrystalline-silicon surface prior to low pressure chemical vapor deposition of tantalum oxide. The amorphous tantalum oxide film is deposited on the nitrided polysilicon surface using penta-ethoxy-tantalum [Ta(OC~Hs)~] and oxygen (09) gas mixture at 470~ The films are annealed at 600-900~ in dry 02. Densification of the as-deposited film by annealing in dry O2 is indispensable to the formation of highly reliable ultrathin tantalum oxide capacitors. During this densification, CH4 and H20 desorb from the as-deposited film, and the film crystallizes into an orthorhombic structure. The RTN treatment allows a reduction of the SiO2 equivalent thickness (t~q) of the capacitor dielectric layer and results in superior leakage and reliability characteristics.

SrTiO3 thin films were prepared on Si and Pt/TaO x /Si substrates by Sr(DPM)2/Ti(i-OC3H7)4/O2/Ar chemical vapor deposition (CVD), using a simple vaporizing-and-transport source delivery system. A thickness uniformity of ±5.6% and a composition uniformity of ±2.7% were obtained. The dielectric constant was 210 for 110 nm thick SrTiO3 films (Sr/(Sr+Ti)=0.5) annealed at 600°C for 2 hours. An SiO2 equivalent thickness of 1.1 nm was obtained for 40 nm thick SrTiO3 films, and leakage current densities were 6×10-8 A/cm2 at 1.0 V and 5×10-7 A/cm2 at 1.65 V. The structural and electrical properties were affected by the film composition.

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SrTiQ and (Ba, Sr)TiO3 thin films were fabricated on Si and Pt/TaOx/Si substrates by chemical vapor deposition (CVD) using Sr(DPM)2, Ba(DPM)2, Ti(O-i-C3HT)4, and O2 where DPM is dipivaloylmethanate or formally 2,2,6,6-tetramethyl-3,5-heptanedionate. The deposition system was operated in both thermal CVD mode and electron cyclotron resonance (ECR) plasma CVD Mode. Variations in individual Sr and Ti deposition rates with differing deposition conditions were investigated. The SrTiO3 and (Ba, Sr)TiQ films were characterized with a view to discussing the step-coverage, crystal structure, and electrical properties. The step-coverage over the 300 nm wide SiQ lines, with 500 nm height and 500 nm spacing, was 30 to 40 %. The 40 to 100 nm SrTiO3 films~ through the p ostdeposition annealing process, showed dielectric constants > 140 with a leakage current density level <10-' A/cm ~ at 1 V. The prospects for applying the CVD (Ba, Sr)TiO3 films to giga-bit dynamic random access memory storage capacitors are discussed.To maintain sufficient storage capacitance in the future ultralarge scale integrated circuit (ULSI) for use in the 1 Gbit dynamic random access memory (DRAM) and beyond, high permittivity materials are expected to be used as the capacitor dielectrics. (Ba, Sr)TiOa is one dielectric material which has been investigated for this application. 1 Typical deposition methods for this dielectric are RF-magnetron sputtering, 2 and ion-beam sputtering 3 techniques. However, the permittivity of (Ba, Sr)TiOa films is not large enough for application to the I Gbit DRAM with a planar type storage capacitor. Thus, the eonformal nature of thin films fabricated by the CVD technique has attracted special attention for use in side areas of the bottom electrodes in DRAM capacitors to increase the storage capacitance. Figure 1 represents a diagram for CVD system. 4 (Ba, Sr)TiO3 thin films were deposited on Si and Pt/TaOx/ Si 5 substrates, using a source combination of Ba(DPM)2, Sr(DPM)2, Ti(O-i-C3HT)4, and 02. DPM is dipivaloylmethanate (CH(CO . C(CH3)~)~), or formally 2,2,6,6-tetramethyl-3,5-heptanedionate (thd) (CH3-C(CHD2-COCHCO-C(CH3)2-CH3). Vapor from the liquid source (Ti source) and sublimation from the powder sources (Sr and Ba sources) were transported individually with Ar carrier flows and mixed before the reaction chamber. The system was operated in both thermal CVD mode and ECR plasma CVD mode. In the thermal CVD mode, O2 was mixed with the metal source compounds and the reactant vapors were injected toward a rotating substrate of Si or Pt/TaOJSi * Electrochemical Society Active Member. Experimental(preannealed sputtered Pt(50 nm)/Ta(50nm)/Si), 4 in. diam. The vapors with Ar carrier flows were evacuated through the mechanical booster pump. In the ECR-CVD mode, O~ was introduced into the reaction chamber separately through the ECR plasma generator. This 02 plasma was mixed with the metal source compounds in the reaction chamber. The vapors with Ar carrier flows were evacuated through the turbomolecular pump.CVD conditio...