Decomposition of Sr(tmhd)2 and Ba(tmhd)2 was investigated by thermogravimetric analysis, in-situ FTIR, and mass spectrometry. Both compounds decomposed following 3 steps: 1) decomposition of the ligands, 2) simultaneous vaporization and partial decomposition of metal-organics, and 3) decomposition of the vaporized metal-organics which existed as the oligomeric species.

The Sr source decomposed at lower temperatures and in a narrower temperature range than the Ba source. Also, the gaseous oligomeric species from the Sr source decomposed relatively quickly while the corresponding species from the Ba source decomposed slowly over a long period. Such a difference between the two compounds is due to different bond energies between the metal atom and the ligands, as indicated by our FTIR results.

A versatile control system, which uses standard commercial software and hardware has been developed and applied to control oxide (and carbide) MOCVD and CVD systems. The control system is implemented within a personal computer platform. The system operates in the real time Microsoft WindowsTM environment utilizing the full advantage of the sophisticated graphical user interfaces, dynamic data exchange, networking, and multitasking capabilities. We have used two different sets of commercial software to control and monitor system hardware. The first software set is INTOUCHTM, a Man-Machine interface software from WONDERWARETM in conjunction with Microsoft ExcelTM and I/O interface software. The second software set is LABVIEWTM, which is primarily a data acquisition control system from National Instruments, combined with Visual BasicTM. Both systems include a friendly interactive real-time windows-based user interface, an advanced process entry and recording spread sheet interface, alarm and security management systems, data display and recording, maintenance routines, and complete networking and remote operation capabilities. In addition, the configurations provide a flexible hardware interface that can directly interface to I/O cards in the PC's bus, as well as to most industrial Programmable Logic Controllers, various types of process controllers, I/O devices and other forms of hardware. Most importantly, the system can interface with any in-situ process monitor or higher level intelligent process control systems in order to optimize the process. Modules may be activated or deactivated as needed (even as part of the process). These systems have been used for home-built systems, as well as to retrofit a modified Spire SPI-MOCVDTM 500XT system. General process interaction and results will be discussed.

Er-doped BaTiO3 thin films have been investigated as a candidate for an optically active waveguide medium. Epitaxial layers were prepared by metal-organic chemical vapor deposition at low pressure. The properties of the characteristic Er3+ luminescence transition at 0.8 eV have been investigated for epitaxial Er doped BaTiO3 thin films for various Er concentrations. The photoluminescent intensity was found to increase by a factor greater than 500 when the doping level was increased from 1 × 1020 cm−3 to 2.2 × 1021cm−3, indicating that concentration quenching was not significant at the highest doping levels. A complex emission spectra was observed and was attributed to the multi-site substitution of Er in BaTiO3. Transient decay measurements revealed a 7 ms radiative lifetime for the 0.80 eV transition that was independent of concentration.

SrTiO3 thin films were prepared on Si(p-type 100) and Pt/SiO2/Si substrates using ECR plasma (or without ECR plasma) assisted MOCVD. Sr(TMI-D)2 and Ti-isopropoxide were used as Sr and Ti metal organic sources, respectively. Perovskite SrTiO3 films were obtained at relatively low temperature of 500°C (using ECR oxygen plasma. Experimental results indicated that higher deposition temperature and ECR oxygen plasma increase the crystallinity, the dielectric constant and the leakage current density. The dielectric constant and the dielectric loss were 222 and 0.04, respectively, for 1234 Å thin SrTiO3 film (Sr/(Sr+Ti)=0.5). The leakage current density was 3.78 × 10−7 A/cm2 at 1.0V, and the dielectric breakdown field was 0.57MV/cm. SEM analyses showed that SrTiO3 films have a uniform and fine grain structure. In terms of step coverage, a lateral step coverage of 50% at 0.8 μm step (the aspect ratio was 1) was obtained with the thickness uniformity of ± 0.5% and the composition uniformity of ±1.2% at 4′′ wafer.

For the first time, layered oxide thin films of SrBi2Ta2O9 (SBT) with very good ferroelectric properties have been prepared by direct-liquid-injection MOCVD technique. The SBT films were deposited onto both Pt/Ti/SiO2/Si wafers and single-crystal sapphire substrates to measure their phase formation, microstructure and ferroelectric properties. Crystalline SBT phase had been observed at temperatures as low as 500°C. With increasing deposition temperature above 500°C, the grain size of SBT thin films was increased from 0.01 μ m to 0.2 μm. The films were found to be dense and homogenous. Typically, SBT thin films of 200 nm thick with grain size about 0. 1μm have 2Pr around 10 μC/cm2 at 5V, Ec 55.7 kV/cm, and dielectric constant around 100. The leakage 9 2 currents were as low as 8 × 10−9 A/cm2 at 150 kV/cm. The films also showed fatigue-free characteristics: no fatigue was observed up to 1.4 × 1010 switching cycles. This development of MOCVD technique for good quality SBT films make their integration into high density nonvolatile memories relatively easy.

Ferroelectric Bi2 SrTa2 O9 thin films were successfully prepared by liquid delivery MOCVD, and structural and electrical properties were investigated. As-deposited films showed sharp distinct peaks, which were indexed assuming a fluorite-type structure. These precursors were transformed to bismuth-layered structures by annealing at 800 °C in flowing oxygen. Reasonable ferroelectric properties were observed in a film with 170 nm-thickness. Remanent polarization and coercive field were estimated to be 5.2 μC/cm2 and 52 kV/cm, respectively, at 5V.

We present the results of an investigation of the microstructural properties of layered-structure perovskite SrBi2Ta2O9 films grown by Flash-MOCVD, conventional CVD, and MOD. The films grown by Flash-MOCVD on Pt electrode layers, were polycrystalline and showed acceptable ferroelectric properties and low leakage. TEM showed that the individual crystallites were of high quality and, on average about 300nm in diameter. TEM also gave some indications of a disordered phase interspersed amongst the crystallites.

A complete, high-resolution set of XPS spectra gathered from these films confirmed that the basic perovskite structures were predominately single phased but that they were, in all cases, accompanied by a significant amount of mobil clusters of Bi metal. We speculate that this Bi metal corresponds to the disordered phase seen by TEM and show that appropriate ozone annealing is able to remove all evidence of it.

Lead titanate (PT) is ferroelectric in its tetragonal phase (c/a=1.06). The domain formation is coupled to the relaxation of internal stress generated by a combination of lattice mismatch, transformation strain and differential thermal stress. The mechanism of domain formation in an epitaxially grown PT film is related to the substrate type and the growth temperature. In this study, PT films have been deposited on MgO(001) in a coldwall, horizontal metal organic chemical vapor deposition (MOCVD) system. The structure of domains and their evolution have been measured as a function of temperature by the x-ray diffraction method using a hot stage. Domain structure changes were observed by θ−2θ scans, ω scans, as well as in-plane φ scans. Effect of film stress on the ferroelectric transition temperature is discussed. Reproducibility of domain formation as a result of temperature cycling both below and above Tc is assessed.

LPCVD thin films of lithium cobalt oxide (LiCoO2) were grown using tertbutyllithium (t-BuLi) and cyclopentadienyl cobalt dicarbonyl (CoCp(CO)2) as precursors in a cold-walled vertical reactor. Deposition rates were found to be as high as 25 A/s. Lithium to cobalt ratios (Li/Co) in the films were found to increase with increasing Ar carrier gas flow rates in the t-BuLi line while they were found to decrease with increasing system pressure. Electrochemical measurements show typical film open circuit voltages (OCV) for as-prepared films to be between 3.30 and 3.60 V vs. Li. Atomic Force Microscopy shows a striated, crystalline film formed at substrate temperatures (Ts) as low as 400 C with grain sizes as large as 200 nm in length.

We have investigated the dielectric behavior of polycrystalline (Ba,Sr)TiO3 thin films deposited by liquid-source metalorganic chemical vapor deposition. The time-domain polarization current, the frequency dependence of the permittivity, and the dielectric loss for these CVD films are all described by a single set of parameters via the phenomenology of Curie - von Schweidler behavior. No change in the general form of the permittivity is found out to 1.5 GHz, suggesting that this description of the response is valid into the frequency range of interest for many applications. Low-frequency dispersion is found to be controllable, leading to films with very low dissipation factors and almost frequency-independent dielectric response. Finally, a non-zero intercept of the inverse of capacitance versus film thickness suggests the existence of a series interfacial capacitance, arising from either microstructural inhomogeneity or energy barriers to carrier transport at the film-electrode interfaces.

Films of lead lanthanum titanate were deposited using metal-organic chemical vapor deposition (MOCVD) at temperatures between 500 and 550°C in a hot-wall reactor. The precursors used were Pb(THD)2, La(THD)3, and Ti(THD)2(I-OPr)2where THD = 2,2,6,6-tetramethyl-3,5-heptanedionate, O2C11H19, and I-OPr = isopropoxide, OC3H7. The three precursors were delivered to the reactor using a single solution containing all three precursors dissolved in tetraglyme and the precursor solution was volatilized at 225°C. Films were deposited on Si and Si/Ti/Pt substrates, and characterized using Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction(XRD). Films deposited at 550°C had a composition which was close to that of the precursor solution while films deposited at 500°C were deficient in lanthanum. Even at 500°C, the desired perovskite phase is readily observed by XRD. Subsequent rapid thermal processing of the film deposited at 500°C showed an increase in the intensity of the X-ray lines, but did not change the width of these lines, implying that grain sizes had remained unchanged.

The quantitative detection of gas concentrations in mixed atmospheres is becoming increasingly important in manufacturing processing, environmental monitoring, and medical diagnostics. Several conductive oxides, such as SnO2, ZnO, and TiO2, are well known to exhibit changes in resistivity when exposed to various gases at temperatures ranging from 200–500°C. Current discrete devices based on resistive changes such as the Taguchi sensor, however, suffer from certain performance problems, including poor gas detection specificity. Integrated arrays of sensors, fabricated using planar technology, offer a promising solution to these problems, as well as other benefits such as low power consumption and low cost.

In this paper, we report the results of using Metalorganic Chemical Vapor Deposition (MOCVD) to fabricate thin films of SnO2 on microhotplate arrays. The studied arrays contain 4 micromachined, suspended elements, each having an integrated resistive heater that produces a rapid thermal rise time ∼3 msec. By separately heating individual elements, we can take advantage of the thermally selective nature of the MOCVD process to limit deposition to these areas, resulting in a maskless deposition process. In addition, these array elements have surface electrical contacts that permit the measurement of the resistance of the thin films during deposition, as well as when they are operated in a gas sensing mode. In situ growth measurements will be reported.

Tin oxide (SnO2) thin films were deposited on polycrystalline alumina (A12O3) substrates using metal organic chemical vapor deposition (MOCVD) technique at the growth temperature of 600°C. X-ray diffraction, scanning electron microscopy, and Auger electron spectroscopy were applied for the microstructure characterization of the films. The films were subjected to sensing tests under 1% H2 environment by monitoring changes in the electrical resistance of the films at elevated temperatures. There is a trend to exhibit sensor temperature characteristic in the deposited thin films which show a local maximum in the electrical resistance curve as a function of ambient temperature. The local maximum occurred at a relatively higher temperature than found in bulk sintered ceramics.

Future high-performance integrated circuits and electronic packaging technology require the integration of many passive components, including high storage capacitors, on the systems. Because of the low melting temperature metal lines and polymer dielectrics in these electronic systems, one cannot employ most of the existing high temperature deposition techniques to grow thin film components. In this paper, we will report our recent work on the room temperature deposition of amorphous ceramic thin films, including BaxTi 2−xOy and SiOx, using the newly developed partially ionized beam technique. This technique utilizes a small percent (<3%) of selfions derived from the depositing materials to bombard the surface growth front during deposition. It is shown that a dramatic control of the density (and therefore the leakage current) and uniformity of the film can be achieved using this deposition technique without post annealing. Al or Cu was used as the electrodes in our multilayer MIM (metal-insulator-metal) test structure. As deposited thin film capacitors with a capacitance ranging from 25 to 100 nF/cm 2 have been fabricated with tan δ <0.01, leakage current of <l.μA/cm2 at 0.5 MV/cm, and breakdown field strength of several MV/cm. These ceramic capacitors do not show any dispersion up to 1 GHz.

MOCVD of oxides can be achieved through deposition reaction schemes such as oxidation, thermal pyrolysis, plasma assisted pyrolysis, radiation-assisted pyrolysis or any combinations of these free-radical processes. Chemically mild and clean reaction schemes such as the hydrolysis-polycondensation and the hydrolysis-assisted pyrolysis reactions are found favorable for stoichiometric depositions using alkoxide complex precursors. We review the various reaction schemes and try to point out comparatively the advantages and disadvantages of each. Experiments in the deposition of lithium tantalate from alkoxide complex precursors are presented. Low deposition temperature, high deposition rate and autostoichiometry capabilities are demonstrated in the experiments.

High temperature superconducting Yba2Cu3O7−x films were grown by liquid delivery metal-organic chemical vapor deposition (LDMOCVD) on silver-coated stainless steel substrates. The films are c-axis oriented, and exhibit a very low surface resistance of 110 μΩ at 77 K and 3 GHz. A two-step LDMOCVD method for growth of oriented (200) CeO2 films on amorphous substrates was also developed. Films of CeO2 for YBCO buffer layers were grown on fused silica (SiO2), polycrystalline alumina (Al2O3), and sapphire (A12O3). A highly c-axis oriented film of YBCO was grown on a fused silica substrate with a CeO2 buffer layer.