A low-temperature (320–480 °C) metal-organic chemical vapor deposition (MOCVD) process was developed for the growth of ruthenium and ruthenium oxide thin films. The process used bis(ethylcyclopentadienyl)ruthenium [Ru(C5H4C2H5)2] and oxygen as, respectively, the ruthenium and oxygen sources. Systematic investigations of film formation mechanisms and associated rate limiting factors that control the nucleation and growth of the Ru and RuO2 phases led to the demonstration that the MOCVD process can be smoothly and reversibly modified to form either Ru or RuO2 through simple and straightforward modifications to the processing conditions–primarily oxygen flow and substrate temperature. In particular, films grown at low oxygen flows (50 sccm) exhibited a metallic Ru phase at processing temperatures below 480 °C. In contrast, films grown at high oxygen flow (300 sccm) were metallic Ru below 400 °C. Above 400 °C, a phase transition was observed from Ru to RuOx (0 < x < 2.0) to RuO2 as the processing temperature was gradually increased to 480 °C.
A low-temperature metallorganic chemical vapor deposition process has been developed for the growth of hafnium silicate thin films for advanced gate dielectric applications. In this process, a metallorganic hafnium precursor, tetrakis͑dimethylamino-͒hafnium, and a metallorganic silicon precursor, tris͑dimethylamino͒silicon, were employed, using O 2 as a co-reactant. Films were deposited at a substrate temperature in the range of 250-450°C. The films were subsequently annealed in oxygen and forming gas ambients to assess thermal stability. The resulting films were characterized by Auger electron spectroscopy to determine composition and X-ray diffraction to determine microstructure. Electrical test structures were fabricated with as-deposited and annealed hafnium silicate films, and C-V and J-V measurements were performed. As-deposited dielectric constant values ranging from 6.9 to 12.9 were achieved depending on processing conditions and resulting film composition. Leakage current density at flatband voltage minus 1 V for a 26 nm thick as-deposited film was measured to be 1.6 ϫ 10 −1 A/cm 2 and was shown to decrease following an O 2 anneal. The performance of these hafnium silicate films was also compared to hafnium oxide films deposited using the same Hf precursor and O 2 oxidizer approach.For future generations of complementary metal-oxide semiconductor ͑CMOS͒ devices, a new insulating material is required to replace SiO 2 , which suffers from high leakage current and reliability issues as the physical thickness scales below ϳ1.5 nm. 1 A number of high dielectric constant metal oxide materials such as HfO 2 , ZrO 2 , Y 2 O 3 , and La 2 O 3 are being considered for next generation gate dielectric applications. 2 However, these simple "unary" metal oxide materials have been shown to undergo thermally induced crystallization at typical post-dielectric deposition processing temperatures, which can be problematic due to the possibility of increased leakage current and dopant diffusion across the dielectric grain boundaries, 3 as well as threshold voltage instability as a result of charge trapping. 4,5 One approach to overcoming these difficulties is to incorporate a silicate phase material into the metal oxide matrix, which lowers the overall dielectric constant but results in an amorphous microstructure with enhanced phase stability and lower trap densities as compared to the simple metal oxide counterparts. Among all the pseudo-binary phases of the aforementioned metal oxides, hafnium silicate is currently one of the leading candidates for a replacement gate dielectric scheme, given the combination of attractive properties that HfO 2 possesses. These include a high dielectric constant ͑21-25͒, good thermodynamic stability on Si, 6 a large band gap ͑ϳ5.7 eV͒, and reasonable conduction band offset to Si ͑1.4 eV͒. 7 For the deposition of a multicomponent film, chemical vapor deposition ͑CVD͒ is an attractive process because film properties and stoichiometry can be tailored via simple changes to the processing paramet...
This study describes work carried out to date involving evaluation of the chemical, structural, and electrical performance of ruthenium (Ru) and ruthenium oxide (RuO2) films grown on SiO2 substrates employing metal organic chemical vapor deposition (MOCVD). Diethyl ruthenocene and oxygen were employed as reactant gases for this work, which was carried out using a 200mm wafer cluster tool. The films were characterized using cross-sectional scanning electron microscopy (CS-SEM), four-point resistance probe, x-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), x-ray diffraction (XRD), and energy dispersive spectrometry (EDS). Capacitance-voltage (C-V) measurements were also carried out to assess the work function of the deposited films. It was determined that both Ru and RuO2 phases possess near-bulk resistivity and low contamination levels. Importantly, it was observed that the film stoichiometry could be modulated by controlled changes of the processing conditions, and that pure Ru and RuO2 films can be deposited in an oxygen ambient. In order to assess thermal stability, the films were subsequently annealed in forming gas and oxygen ambients, and it was found that the film stability is dependent upon both the deposited phase and the annealing ambient. Results of PMOS gate electrode performance testing of CVD Ru films, has been carried out, and the results are similar to those previously reported for ruthenium-based films.
A low-temperature metalorganic chemical vapor deposition process was developed and optimized, using a design of experiments approach, for the growth of ultrathin aluminum oxide (Al2O3) as a potential gate dielectric in emerging semiconductor device applications. The process used the aluminum β-diketonate metalorganic precursor [aluminum(III) 2,4-pentanedionate] and water as, respectively, the metal and oxygen source reactants to grow Al2O3 films over a temperature range from 250 to 450 °C. The resulting films were analyzed by x-ray photoelectron spectroscopy, x-ray diffraction measurements, Rutherford backscattering spectrometry, nuclear-reaction analysis for hydrogen profiling, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The as-deposited Al2O3 phase was amorphous and dense and exhibited carbon and hydrogen incorporation of, respectively, 1 and 10 at.%. Postannealing at 600 °C led to a reduction in hydrogen concentration to 1 at.%, while maintaining an amorphous Al2O3 matrix.
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