Chemical Vapor Deposition Of Transistion Metals

Coatings of Group IIA metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula (I) wherein M is a transition metal of Group VB, VIB, VIIB or VIII, R₁ is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, R₂ is a hydrogen or lower alkyl or alkenyl radical, n is the valence of M and is an integer from 2 to 4, and p is an integer from 0 to (n-1), is contacted with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula I is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as manganese telluride can be deposited from a manganese compound of formula I and a heat decomposable tellurium compound under nonoxidizing conditions.Georgia Tech Research Corporatio

Chemical etching and organometallic chemical vapor deposition on varied geometries of GaAs

Results of micron-spaced geometries produced by wet chemical etching and subsequent OMCVD growth on various GaAs surfaces are presented. The polar lattice increases the complexity of the process. The slow-etch planes defined by anisotropic etching are not always the same as the growth facets produced during MOCVD deposition, especially for deposition on higher-order planes produced by the hex groove etching

Atomic layer deposition of aluminum phosphate based on the plasma polymerization of trimethyl phosphate

Aluminum phosphate thin films were deposited by plasma-assisted atomic layer deposition (ALD) using a sequence of trimethyl phosphate (TMP, Me3PO4) plasma, O-2 plasma, and trimethylaluminum (TMA, Me3Al) exposures. In situ characterization was performed, including spectroscopic ellipsometry, optical emission spectroscopy, mass spectrometry and FTIR. In the investigated temperature region between 50 and 320 degrees C, nucleation delays were absent and linear growth was observed, with the growth per cycle (GPC) being strongly dependent on temperature. The plasma polymerization of TMP was found to play an important role in this process, resulting in CVD-like behavior at low temperatures and ALD-like behavior at high temperatures. Films grown at 320 degrees C had a GPC value of 0.37 nm/cycle and consisted of amorphous aluminum pyrophosphate (Al4P6O21). They could be crystallized to triclinic AlPO4 (tridymite) by annealing to 900 degrees C, as evidenced by high-temperature XRD measurements. The use of a TMP plasma might open up the possibility of depositing many other metal phosphates by combining it with appropriate organometallic precursors

Organometallic chemical vapor deposition of copper oxide thin films

Copper oxide thin films were prepared by organometallic chemical vapor deposition (OMCVD or MOCVD) technique. This MOCVD process uses copper acetylacetonate (Cu(acac)[subscript]2) as the copper precursor. Spectroscopic (X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and infrared spectroscopy (IR)) and diffraction (X-ray diffraction (XRD)) methods were employed to analyze the chemical composition and oxidation state of copper in these films. According to spectroscopic results, the composition of these MOCVD film primarily depends on the deposition temperature and partial pressures of the reactants. As indicated by XPS and XRD results, Cu[subscript]2O films were prepared at 360°C, with an oxygen partial pressure of 150 torr and copper precursor partial pressure of 0.20 torr. CuO films were grown at temperatures above 420°C, with an oxygen pressure of 190 torr and precursor pressure of 0.20 torr. By using water vapor instead of oxygen as the co-reactant, Cu films were deposited at temperatures above 380°C, with a water vapor pressure of 15 torr and precursor pressure of 0.20 torr. To examine the specific mechanism of precursor decomposition, a molecular vibrational spectroscopic technique, Fourier Transform Infrared spectroscopy (FTIR), was employed to investigate the vapor phase product distribution in the MOCVD effluent stream. Based on FTIR results, a kinetic model was proposed. This model suggests that steric effect from chelating ligands and bond strength sequence in the precursor molecule are the principle factors determining the decomposition products of Cu(acac)[subscript]2 in the MOCVD reactor. Differential scanning calorimetry (DSC) was used to study the pyrolysis pattern of Cu(acac)[subscript]2. Particularly, the impacts of oxygen concentration, carrier gas molecular weight, and heating rate on the pyrolysis of this precursor were studied. From DSC results, it seems that Cu(acac)[subscript]2 undergoes a single-step, exothermic reaction in the ambient with oxygen gas present. In DSC pattern, the exothermic peak height also increased as oxygen concentration increased. The activation energy for the exothermic step was derived by Kissinger equation as 20 kcal/mol. Based on experimental results of deposition, FTIR, and DSC, it seems that a deposition temperature above a critical value is necessary to initiate the decomposition of Cu(acac)[subscript]2 and oxygen can assist this reaction by accelerating the reaction rate

Optical fiber fabrication using novel gas-phase deposition technique

We report a highly versatile chemical-in-crucible preform fabrication technique suitable for gas-phase deposition of doped optical fibers. Aluminosilicate and ytterbium-doped phosphosilicate fibers are presented demonstrating the technique and its potential for realizing complex fiber designs that are suitable for the next generation of high-power fiber devices. The results show aluminum-doped fiber with numerical aperture of 0.28 and ytterbium-doped fiber with a measured slope efficiency of 84% with respect to pump launch power

Solvent free method for intense vaporization of solid molecular and inorganic compounds

New tools have been developed for vaporization of solid precursors to meet the demands of high feed rate for CVD, ALD and other deposition processes