This contribution reports the in situ growth of transparent, conducting GaxIn2-xO3 and ZnkIn2Ok+3 films by MOCVD (metal-organic chemical vapor deposition) techniques using In(dpm)3, Ga(dpm)3, and Zn(dpm)2 (dpm = dipivaloylmethanate) as volatile precursors. In the former series, film microstructure in the x = 0.4 – 1.0 range is predominantly cubic with 25° C electrical conductivities as high as 1300 S/cm (n-type; carrier density = 1.2 × 1020 cm−3, mobility = 68 cm2/Vs) and optical transparency in the visible region greater than that of ITO. In the latter series, films in the composition range K = 0.16 – 3.60 were studied; the microstructural systematics are rather complex. Electrical conductivities (25° C) as high as 1000 S/cm (n-type; carrier density = 3.7 × 1020 cm−3, mobility = 18.6 cm2/Vs) for K = 0.66 were measured. The optical transparency window is significantly broader than that of ITO.

The MOCVD technique is being used increasingly for the deposition of electronic ceramics such as Pb(Zr,Ti)O3, Ta2O5 and TiO2. For the mil potential of MOCVD to be realised, it is sometimes necessary to modify existing precursors so that process parameters in the MOCVD process are optimised. In this paper we describe our approach to “molecular design” and discuss how the substitution of simple alkoxide groups by β-diketonates or donor-functionalised ligands can result in precursors with improved physical properties and optimum MOCVD characteristics.

Ferroelectric oxide epitaxial thin films are potentially important for a variety of guided-wave electro-optic and non-linear optical applications. Metalorganic chemical vapor deposition has been used to synthesize epitaxial thin films of a number of ferroelectric oxides. The films now have sufficient optical quality to enable the fabrication of waveguide devices including electro-optic modulators and optical amplifiers for 1.54 microns.

Liquid delivery, metal-organic chemical vapor deposition (MOCVD) was used to deposit high quality, A-site deficient crystalline films of LaxCayMnO3 where x + y < 1. The properties of the deposited thin-films are strongly dependent upon the film stoichiometry and display magnetoresistance repsonses at or above room temperature. Using Ca doped A-site deficient thin-films, we can shift the metal to insulator transition (Te) in a controlled manner to temperatures that are useful for commercial applications. Further, these films exhibit useful magnetoresistance at room temperature in relatively small applied magnetic fields.

The microstructural and luminescence properties of europium doped yttrium oxide (Y2O3:Eu) thin films deposited by metallorganic chemical vapor deposition are presented in this work. It was found that surface morphology, crystallinity and photoluminescent emission properties are strongly dependent on substrate temperature during deposition. The depositions were carried out in a stainless steel chamber using yttrium and europium 2,2,6,6,-tetramethyl–3,5-heptanedionates as volatile precursors and O2 as the reactant gas. Post-annealing increased the crystallite size and decreased the lattice parameter, resulting in an increased photoluminescent emission intensity.

Crystalline titanium dioxide films were deposited on silicon (100) at temperatures as low as 184°C using the volatile molecular precursor, tetranitratotitanium(IV). Deposition rates in a low pressure chemical vapor deposition (LPCVD) reactor operated at 230 – 500°C with a precursor vessel temperature at 22°C were typically 4 nm/min. The effect of deposition temperature and annealing conditions on morphology are shown. Following post-deposition annealing in oxygen and hydrogen, Pt/TiO2/Si/Al capacitors were fabricated and exhibited dielectric constants in the range of 19 – 30 and leakage current densities as low as 10−8 Amp/cm2.

Adherent, polycrystalline films containing mixtures of SrRuO3, Sr2gRuO4 and RuO2 were deposited on silicon and alumina substrates by hot wall chemical vapor deposition from bis(2, 4-dimethylpentadienyl) ruthenium and Sr(thd)2 between 650 and 700°C. The as-deposited mixed phase films, which contained polycrystalline phases of RuO2 and amorphous phases of the mixed oxide exhibited resistivities between 6.5 and 20 mΩcm. Rims were annealed at 1000°C under oxygen/argon ambient. The annealed films exhibited higher resistivities than their as-deposited counterparts and a substrate dependence of phases present was observed. The decrease in conductivity upon annealing for films on both substrates is attributed to the formation of volatile ruthenium oxides. The higher conductivity of post-annealed samples on alumina (compared to samples prepared and annealed on Si) is attributed to Sr uptake by the substrate and thus a suppression of Sr2RuO4 formation.

MOCVD is a useful method for the deposition of thin films of lead zirconium titanate, PZT, because of its good step coverage and control of composition. Results are herein presented on a number of novel compounds which are potential MOCVD precursors. The compounds studied include Pb(tmhd)2, Zr(OBu')4 and Ti(OPr')4. Another commonly utilized precursor Zr(tmhd)4, is not ideal, in that it is a high melting point solid, and hence requires high substrate temperatures. We have sought to modify Zr precursors through chemical methods and have synthesized a number of novel, more volatile, and less intrinsically thermally stable MOCVD precursors. Full chemical characterization of the Zr precursors (NMR, IR, MS, CHN, TGA/DSC, Single Crystal X-ray diffraction) has been undertaken. We also present structural results on some related lead precursors.

New precursors have been found for chemical vapor deposition (CVD) of many metal oxides. Each precursor is a mixture formed by randomly attaching a selected set of organic groups, such as the isomers of the butyl group, to a metal 2,4-pentanedionate (also known as acetylacetonate) in place of the methyl groups of the 2,4-pentanedionate ligand. Most of these new mixed metal beta-diketonates are liquids at room temperature, whereas the corresponding metal 2,4-pentanedionates are solids. In the cases where they were solids or viscous liquids, small amounts of organic solvents were added to reduce the viscosity. We have so far prepared mixed beta-diketonate precursors for barium, strontium, calcium, magnesium, aluminum, indium, tin, lead, bismuth, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, manganese, iron, ruthenium, cobalt, nickel, copper, zinc, yttrium, lanthanum and cerium.

Liquid sources are much more convenient for CVD than solid sources. These liquid mixtures or solutions were vaporized by ultrasonically nebulizing the liquid into a flow of hot nitrogen carrier gas preheated to 150–250 °C. These vapor mixtures were mixed with air or oxygen and flowed over substrates heated typically to 350–450 °C. Films of the corresponding metal oxide (or carbonate, in the case of barium, strontium and calcium) were deposited on substrates of silicon or glass. Gas pressures from 20–760 Torr were used.

Because a common set of ligands is used for each of these metal precursors, they can be mixed as liquids or vapors without any precipitation due to ligand exchange reactions. To demonstrate their use in forming mixed metal oxides, we have prepared films of ferroelectric barium titanate. This method should be applicable to other mixed metal oxides of current interest, such as high dielectric constant strontium titanate, ferroelectric bismuth strontium tantalate, superconducting yttrium barium copper oxide, refractory yttrium zirconium oxide, second-harmonic generating barium borate, metallic lanthanum strontium cobalt oxide and magnetoresistive lanthanum strontium manganate.

We successfully deposited LiAlO2 films on Si substrates at 400–600 °C by single source chemical vapor deposition using a heterometallic compound, Li(O'Pr)2Al(CH3)2, which contains Li, Al, and O at the same 1:1:2 ratio as LiAlO2. Li(O'Pr)2Al(CH3)2 is sufficiently volatile to be vapor-transported at 50 °C. Elastic recoil detection and Rutherford backscattering spectroscopy analyses of a deposited film indicate that the film is stoichiometric (Li:Al:O = 1.0:1.0:2.0) and contains a few atomic percent hydrogen (5 %) and carbon (2 %). Depth profile analysis of X-ray photoelectron spectroscopy also confirms the 1:1 ratio of metal contents in the films. As-deposited films were amorphous, however, crystallized to β- or γ-LiA1O2 after annealing at 950 °C.

Thin films of polycrystalline RuO2 were deposited from bis(2,4-dimethylpentadienyl) ruthenium, (η5-2, 4-Me2C5H5)2Ru (1) and ruthenocene (2) on quartz and silicon substrates between 200 and 500°C under Ar/O2 or O2. Films deposited from 1 were more adherent than those grown from 2 under the same conditions, however, none of the films were particularly adherent when O2 was used as a carrier gas. SEM revealed a columnar structure for both precursors with grain size ranging from 0.15 – 1 5μ. Crystallinity increased after annealing the films to 800°C. Resistivity decreased as the annealing temperature increased.

New strontium (host lattice constituent) and cerium (doping element) precursor sources have been developed and evaluated for deposition of blue color emitting SrS:Ce thin films by ALE (Atomic Layer Epitaxy). In the case of strontium, the monomeric derivative [Sr(hfac)2]*triglyme has been synthesized and structurally characterized, whereas, for cerium, the utilization of its homoleptic tris amide derivative Ce{N[Si(CH3)3]2}3 has led to a blue color emitting SrS:Ce. In a further effort, emission characteristics of SrS:Ce doped with the β-diketonate-related Ce(tmhd)4 derivative have been weighed against data obtained employing the cerium tris amide composition.

Titanium nitride and ternary alloys thereof are of significant interest due to their hardness, chemical resistance, and good electrical conductivity. We report the synthesis, structure, and properties of several new precursors to titanium nitride that are based upon hydrazine-derived ligands. Application of these complexes in titanium nitride film depositions is overviewed. Film properties and characterization are presented. We also describe a new process for the preparation of titanium aluminum nitride films, and focus on how the presence of small amounts of aluminum change the properties of the material.

Films of silicon nitride are widely used in semiconductor technologies for very large scale integration (VLSI), thin film transistor (TFT), and solar cell applications. Current production technologies for silicon nitride use low pressure chemical vapor deposition (LPCVD) at temperatures > 700 °C or plasma enhanced chemical vapor deposition (PECVD) at temperatures below 450 °C. In this report, successful deposition of silicon nitride films by the low temperature thermal atmospheric pressure chemical vapor deposition (APCVD) method is described. Using a novel precursor tetraiodosilane (SiI4), deposition of silicon nitride has been achieved at temperature as low as 400 °C. Data pertaining to the dependence of film properties on deposition temperature are presented, along with a evaluation of the deposition rate, composition, chemical structure, and conformality of the resulting films.

Volatile antimony precursors were synthesized for the low temperature chemical vapor deposition (CVD) of antimony thin films. The molecules synthesized include tris (trifluoromethyl)stibine, Sb(CF3)3, Lewis base adducts of Sb(CF3)3, and antimony trihydride (stibine), SbH3. Isotopie substitution of stibine with deuterium leads to a more thermally stable, carbon-free antimony source. Similarly, deuterium substitution of trimethylsilylmethyl antimony dihydride leads to a stabilized liquid antimony precursor. The molecules were characterized using FTIR, NMR and DSC / TGA. Pure antimony films were deposited at temperatures below 300 °C with growth rates approaching 170 Å / min using a low pressure hot-wall CVD reactor. The films were characterized using XRD, EDS, SEM and AFM.

Boron nitride thin films were prepared on Si(100) substrate by CVD. Triethylboron and ammonia were employed as precursors and various operating parameters such as reactor pressure, temperature, feed rates of gases were varied to investigate their effects on deposition rate and film characteristics. Total gas pressure in the reactor was varied from atmospheric to I torr. Deposition temperature was in the range 850 – 1,050 °C. Deposition rate increased with partial pressure of TEB but decreased with total pressure in the reactor. Deposited films were examined with SEM, FTIR, XPS, AES, XRD. Prepared films were BN of turbostratic structure.

The kinetics of trimethylindium pyrolysis are investigated in a flow reactor equipped with a molecular-beam mass-spectrometric sampling system. Data are analyzed using a new computational approach that accounts for heat and mass transport in the reactor. The measured activation energy, 46.2 kcal mol−1, is in good agreement with previously reported values.

We report here growth of highly transparent nano-crystallinc diamond films on quartz substrates by microwave plasma enhanced CVD. Optical transmittancc of greater than 84% beyond 700 nm has been obtained for films as thick as 1 μm. Such high optical transparency of these films is primarily attributed to the high smoothness of their surface (average roughness of about 60–65 À) as well as the high content of sp3 bonded carbon therein. The effects of methane fraction in the source gas, substrate temperature and grain size of the diamond powder used for substrate pretreatment on the structural and optical properties of these films arc also studied.

Several volatile, low molecular weight, linear and cyclic carbosilanes containing a 1:1 Si:C ratio were studied as single-source CVD precursors to SiC. A comparison of methylsilane, 1,3-disilacyclobutane, 1,3-disila-n-butane, and 1,3,5-trisilacyclohexane in terms of both their pyrolysis chemistry (decomposition onset temperatures and gaseous by-products) and resulting film characterization (growth rate, stoichiometry, crystallinity and morphology) is presented. Polycrystalline β-SiC films were deposited by LPCVD on Si (100) substrates at temperatures ranging from 800°C to 1100°C by using each of these single-source precursors.

Magnesium-doped semiconductors have existing and anticipated applications in the fabrication of blue and green light-emitting diodes, blue and green laser diodes, and in microelectronics devices. At present, the area is limited by the precursor characteristics of bis(cyclopentadienyl)magnesium and substituted derivatives. We will describe our efforts to identify new magnesium source compounds that are potentially superior to magnesocenes and can be used in chemical vapor deposition processes. Monomeric three- and four-coordinate amides have been synthesized and totally characterized. These complexes are low-melting solids and are significantly more volatile than magnesocene derivatives. We will also describe the synthesis and characterization of several other classes of volatile magnesium compounds that might be useful in chemical vapor deposition processes.