Ru films were produced by atomic layer deposition (ALD) with an alternating supply of bis(ethylcyclopentadienyl)ruthenium (Ru(EtCp) 2 ) and ozone at deposition temperatures of 225-275 • C. Ozone acted as an effective reactant for Ru(EtCp) 2 . The Ru film thicknesses formed during one cycle were saturated at relatively high values of 0.09-0.12 nm/cycle depending on the deposition temperatures, and their resistivities were about 16 μ cm. Moreover, a reduced nucleation delay was found for Ru ALD using ozone when compared to Ru ALD using oxygen gas. The amount of oxygen impurity incorporated into the Ru films was less than 1 at%, as determined by Auger electron spectroscopy. The interfacial adhesion property between Ru films prepared via ALD using ozone (ozone-Ru) and ZrO 2 was good and 80% step coverage was achieved on a 3-D structure with a very high aspect ratio of 16:1, making them suitable for use as a top electrode material.As the minimum feature size of semiconductor devices decreases, the dimensions of the memory cells also decrease. To maintain the required cell capacitance (25-30 fF/cell) in dynamic random access memory (DRAM) with design rules of 45 nm or less, high-k dielectric materials, such as ZrO 2 , TiO 2 , Ta 2 O 5 , SrTiO 3 , and (Ba,Sr)TiO 3 , have been extensively investigated. [1][2][3][4][5][6][7][8][9] For this application to be successful, the choice of a suitable capacitor electrode material is very important. The capacitor electrode material should not react with oxygen. Moreover, a compatible etching process, good morphological stability, and reliable adhesion properties are also required when applying such materials in electronic devices. The noble metals, such as Pt and Ru, are preferentially considered for use as electrode materials. 6-12 In addition to high work functions, these noble metals have sufficiently low resistivities that ultrathin films can be employed. Furthermore, these noble metals are able to minimize the device's leakage current, and they appear to have better chemical compatibility with the dielectrics than more conventional capacitor electrode materials such as TiN. In particular, Ru, which has a work function of 4.7 eV and a bulk resistivity of 7.1 μ cm, is preferred from a device integration perspective, as it can be dry etched relatively easily, unlike Pt. 13,14 Moreover, Ru is chemically stable toward oxygen and can block the diffusion of oxygen during the fabrication and annealing of dielectrics by forming conductive oxide films of RuO 2 . 15,16 Even though memory is fabricated with high-permittivity dielectrics, it is obvious that complicated three-dimensional (3-D) structures are indispensable for achieving the required cell capacitance in high-density memory. 17, 18 Therefore, good conformal deposition is required from the thin film deposition method used to construct the capacitor electrode. Of the various deposition methods, atomic layer deposition (ALD) is currently under widespread development, because it enables conformal deposition for complicated 3-D st...

The authors investigated the modified atomic layer deposition (ALD) of RuO2 films using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] at a deposition temperature of 265°C. Oxygen gas diluted with argon was supplied throughout all of the ALD steps. The growth rate of the modified ALD RuO2 was about 1.4Å∕cycle, which is higher than that of conventional Ru ALD due to the increase in the amount of Ru(EtCp)2 adsorption per cycle, as well as the difference in the unit cell volumes of Ru and RuO2. The film thickness increased linearly with the number of cycles, and the incubation cycle in the initial stage was negligible.

NewZrO 2 /Al 2 O 3 /ZrO 2 (ZAZ) dielectric film was theoretically designed and successfully demonstrated to be applicable to 45nm DRAM devices. ZAZ dielectric film is a combined structure from tetragonal ZrO 2 and amorphous Al 2 O 3 . Thus prepared ZAZ TIT capacitors showed very small Tox.eq value of 6.3Å and low leakage current less than 1fA/cell. It was also confirmed that ZAZ TIT capacitor was thermally robust during backend full thermal process by applying it to the final DRAM product in mass production.

with ±OD and ±OH, and the consequent release of both CDH 3 and CH 4 . In the next step, the water displaces the alkoxide radical, favoring isopropanol formation. Unlike in the first step, all the isopropanol formed showed deuterated oxydril because only D 2 O is present in the gaseous phase. This can be deduced from the complete disappearance of the 1091 cm ±1 vibration (d O±H), and the appearance of the band at 897 cm ±1 (d O±D). Finally, the surface is ready to interact with a further precursor molecule.The same behavior is observed both in presence and the absence of oxygen as the reacting gas, definitely suggesting a quite marginal role for oxygen in the decomposition pathway.In conclusion, by using aluminum dimethylisopropoxide as the precursor, varying the reaction conditions (such as temperature and total pressure) and, most important, by using water vapor as the reacting gas, we obtained high density, transparent aluminum oxide films with extremely smooth surface texture, at growth temperatures as low as 180 C, and a growth rate of up to about 150 nm min ±1 . A reaction mechanism has been proposed for the precursor decomposition, stressing the important role of water vapor in the decomposition process.

Various processes based on atomic layer deposition (ALD) have been reported for growing Ti-based thin films such as TiN and TiO2. To improve the uniformity and conformity of thin films grown via ALD, fundamental understanding of the precursor–substrate surface reactions is required. Herein, we present a density functional theory (DFT) study of the initial nucleation process of some titanium halide precursors (TiCl4, TiBr4, and TiI4) on Si surfaces having –OH or –NH2 functional groups. We consider the most favorable adsorption site in the reaction between the precursor and functional group of the surface, based on the thermodynamics and kinetics of the reaction. Sequential dissociation reaction mechanisms of halide ligands were systematically investigated. The exothermicity of the dissociative adsorption was found to be in the order of: TiI4 > TiBr4 > TiCl4. In addition, the precursors were observed to be more exothermic and show higher reaction rate constant when adsorbed on the –OH–terminated surface than on the –NH2–terminated surface. These observations reveal the selectivity of deposition by surface functional groups.