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Strontium titanate (STO) is a dielectric with a cubic perovskite type structure and of increasing interest for microelectronics, especially in the metal-insulator-metal (MIM) capacitors due to its high dielectric constant. The dielectric constant of the STO films and consequently the performance of the MIM capacitors appear to be strongly influenced by the process conditions. In this work the authors report on the influence of various thermal treatments upon the crystallinity and morphology of strontium titanate crystals. The influence of spike, laser, or rapid thermal anneals on the morphology with respect to grain size and topography of the crystalline stoichiometric STO films is studied. Also, the use of a stack containing a Sr-rich STO (62% Sr) bottom seed layer and a stoichiometric STO top layer in combination with a thermal treatment was found to affect the microstructure of the STO film. A comparison of the electrical properties for various thermal treatments has been made. [ABSTRACT FROM AUTHOR]

The density of hafnium oxide films grown by atomic layer deposition for high-κ gate dielectric applications was investigated for films with thickness in the nanometer range. The density, measured by combining the film thickness from transmission electron microscopy with the amount of hafnium deposited from Rutherford backscattering, decreased with decreasing film thickness. The dielectric constant of hafnium oxide remained constant with decreasing film thickness, however. The main reason for the decrease in the measured density seemed not to be a decrease in the inherent material density. Instead, the relative importance of interface roughness in the density measurement increased with decreasing film thickness. [ABSTRACT FROM AUTHOR]

Ultrathin lanthanide (Nd, Pr, Eu, Sm) oxide films with functional dielectric properties down to 3.3 nm thickness were deposited by aqueous chemical solution deposition (CSD) onto hydrophilic SiO2/Si substrates. Precursor solutions were prepared from the oxides via an intermediate, solid Ln(III)citrate. A film heat treatment scheme was derived from thermogravimetric analysis of the precursor gels, showing complete decomposition by 600 °C. Crystalline phase formation in the films depended on the lanthanide, annealing temperature, and citric acid content in the precursor. Through variation of the precursor concentration and number of deposited layers, thickness series of uniform films were obtained down to ~3 nm. The film uniformity was demonstrated both by atomic force microscopy and cross-section transmission electron microscopy. The lanthanide oxide films possessed good dielectric properties. It was concluded that aqueous CSD allows deposition of uniform ultrathin films and may be useful for the evaluation of new high-k candidate materials. [ABSTRACT FROM AUTHOR]

Abstract: Scaling air-gap interconnects to 70nm pitch is demonstrated for the first time by combining air-gap technology (SiO2 etch-back and non-conformal CVD) and the double patterning approach. A capacitance reduction of 45% was measured on the air-gaps compared to the SiO2 reference. The reliability performance of the air-gaps was then evaluated and it was found that the structures exceeded 10years lifetime at 2MV/cm, almost matching the performance of SiO2 interconnects. Air-gaps could therefore make a promising low-RC solution for future technology nodes. [Copyright &y& Elsevier]

Abstract: Downscaling of the metal–insulator–metal capacitor (MIMCAP) for Dynamic Random Access Memory (DRAM) requires the introduction of high permittivity dielectrics. MIMCAP structures formed with RuO2/Ru as bottom electrode, rutile TiO2 as dielectric and TiN as top electrode are described. Ozone (O3) is needed as oxidant in the TiO2 atomic layer deposition (ALD) process in order to obtain the rutile phase (permittivity>80), while anatase TiO2 (permittivity ∼40) is obtained with H2O. As O3 etches the ruthenium substrate, an ultra-thin interlayer of TiO2 was first grown with H2O, followed by the thick TiO2 layer deposited with O3. In order to minimize the content of anatase in the TiO2 layer, responsible for a reduced dielectric constant, we investigate the effect of scaling down the thickness of the protective H2O based inter-layer on the equivalent oxide thickness (EOT) and leakage current density (J g). The four times reduction in thickness without affecting the integrity of the ruthenium substrate resulted in a significant decrease of both EOT and J g. [Copyright &y& Elsevier]