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Production of High Value Fluorine Gases for the Semiconductor Industry

Description: The chemistry to manufacture high purity GeF{sub 4} and WF{sub 6} for use in the semiconductor industry using Starmet's new fluorine extraction technology has been developed. Production of GeF{sub 4} was established using a tube-style reactor system where conversion yields as high as 98.1% were attained for the reaction between and GeO{sub 2}. Collection of the fluoride gas improved to 97.7% when the reactor sweep gas contained a small fraction of dry air (10-12 vol%) along with helium. The lab-synthesized product was shown to contain the least amount of infrared active and elemental impurities when compared with a reference material certified at 99.99% purity. Analysis of the ''as-produced'' gas using ICP-MS showed that uranium could not be detected at a detection limit of 0.019ppm-wt. A process to make WF{sub 6} from WO{sub 2}, and UF{sub 4}, produced a WOF{sub 4} intermediate, which proved difficult to convert to tungsten hexafluoride using titanium fluoride as a fluorinating agent.
Date: October 23, 2003
Creator: Bulko, J. B.
Partner: UNT Libraries Government Documents Department

REACTIONS OF MOLYBDENUM, TUNGSTEN AND URANIUM HEXAFLUORIDES WITH NITROGEN COMPOUNDS. III. NITROGEN DIOXIDE AND NITROGEN OXYHALIDES

Description: Reaction between gaseous nitrogen dioxide and gaseous uranium hexafluoride results in the formation of the nitrylium salt NO/sub 2/UF/sub 6/. Under similar conditions no reaction occurs between nitrogen dioxide and molybdenum and tungsten hexafluorides. Reaction between nitrosyl and nitryl fluorides and the three hexafluorides results in solid compounds of the composition NO/sub x/F x MF/sub 6/, where x is 1 or 2 and M represents Mo, W, or U. Reaction between gaseous or liquid nitrosyl chloride and molybdenum and uranium hexafluorides results in the formation of the nitrosylium salts NOMoF/sub 6/ and NOUF/sub 6/ and chlorine. Tungsten hexafluoride was found not to react with nitrosyl chloride. The conditions and stoichiometry of the reactions are described. The nitrylium salt, NO/sub 2/UF/sub 6/, is characterized, and some of its physical and chemical properties are described. The NO/sub x/F x MF/sub 6/ compounds are characterized, and some physical properties are described. Evidence for the presence of NO/sup +/ and MF/sup -//sub 7/ ions in these compounds is given. The nitrosylium salts, NOMoF/sub 6/ and NOUF/sub 6/, were characterized previously. (auth)
Date: January 27, 1961
Creator: Geichman, J.R.; Ogle, P.R. & Swaney, L.R.
Partner: UNT Libraries Government Documents Department

HEXAFLUORIDES OF MOLYBDENUM, TUNGSTEN AND URANIUM. II. REACTIONS WITH LIQUID AND GASEOUS DINITROGEN TETROXIDE

Description: Molybdenum and tungsten hexafluorides form the solids nitrosylium pentafluoroxymolybdate(VI) and -tungstate(VI), respectively. Uranium hexafluoride gives nitrosylium hexafluorouranate(V) STANOUF/sub 6/!, the same salt that it forms with nitric oxide. (auth)
Date: January 29, 1962
Creator: Geichman, J.R.; Smith, E.A.; Swaney, L.R. & Ogle, P.R.
Partner: UNT Libraries Government Documents Department

Uranyl fluoride luminescence in acidic aqueous solutions

Description: Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 {+-} 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO{sub 4} at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO{sub 2}F{sub 2}. Studies on the effect of added LiNO{sub 3} or Na{sub 2}WO{sub 4}{center_dot}2H{sub 2}O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF{sub 6} content of WF{sub 6} gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF{sub 6}.
Date: August 1, 1996
Creator: Beitz, J.V. & Williams, C.W.
Partner: UNT Libraries Government Documents Department

Chemical vapor deposition and characterization of tungsten boron alloy films

Description: A low pressure chemical vapor deposition (LPCVD) process for depositing W{sub X}B{sub (1-X)} films from WF{sub 6} and B{sub 2}H{sub 6} is described. The depositions were performed in a cold wall reactor on 6 in. Si wafers at 400C. During deposition, pressure was maintained at a fixed level in the range of 200 to 260 mTorr. Ratio of WF{sub 6}/B{sub 2}H{sub 6} was varied from 0.05 to 1.07. Carrier gas was either 100 sccm of Ar with a gas flow of 308 to 591 sccm, or 2000 sccm of Ar and 2000 sccm of H{sub 2} with the overall gas flow from 4213 to 4452 sccm. Two stable deposition regions were found separated by an unstable region that produced non-uniform films. The B-rich films produced in one of the stable deposition regions had W concentrations of 30 at.% and resistivities between 200 and 300 {mu}ohm{center_dot}cm. The W-rich films produced in the other stable deposition region had W concentrations of 80 at.% and resistivities of 100 {mu}ohm{center_dot}cm. As-deposited films had densities similar to bulk material of similar stoichiometry. Barrier properties of the films against diffusion of Cu to 700C in vacuum were measured by 4-point probe. Also, annealing was carried out to 900C in order to determine phases formed as the films crystallize. These studies indicate that W{sub X}B{sub (1-X)} films may be useful barriers in ULSI metallization applications.
Date: November 1, 1993
Creator: Smith, P. M.; Fleming, J. G.; Lujan, R. D.; Roherty-Osmun, E.; Reid, J. S.; Hochberg, A. K. et al.
Partner: UNT Libraries Government Documents Department

Heterogeneous reaction mechanisms and kinetics relevant to the CVD of semiconductor materials

Description: This report documents the state of the art in experimental and theoretical techniques for determining reaction mechanisms and chemical kinetics of heterogeneous reactions relevant to the chemical vapor deposition of semiconductor materials. It summarizes the most common ultra-high vacuum experimental techniques that are used and the types of rate information available from each. Several case studies of specific chemical systems relevant to the microelectronics industry are described. Theoretical methods for calculating heterogeneous reaction rate constants are also summarized.
Date: March 1, 1994
Creator: Creighton, J. R. & Coltrin, M. E.
Partner: UNT Libraries Government Documents Department

Sequential deposition etch techniques for the selective deposition of tungsten

Description: We report on the use of a deposition/etch approach to the loss of selectivity problem, using high activity fluorine chemistries in the etch step. Proof-of-concept experiments were initially performed in a hot wall system, the excellent results obtained lead us to prove out the concept in a commercially available cold wall Genus reactor. We observed that WF{sub 6} is ineffective as an etchant of W. The technique has been able to produce perfectly selective depositions 1 micron thick in both hot wall, and cold wall, systems. Sheet resistivity values and film morphology are good. 9 refs., 4 figs., 1 tab.
Date: January 1, 1991
Creator: Fleming, J.G.; Omstead, T.R. & Dominguez, F.
Partner: UNT Libraries Government Documents Department

Multiphoton ionization studies of WF{sub 6} and UF{sub 6}

Description: Multiphoton ionization of UF{sub 6} and WF{sub 6} has been studied from low ({approximately} 10{sup 5}) to high ({approximately}10{sup 16} W/cm{sup 2}) power density. The role of ``collective states`` in MPI is considered.
Date: July 1, 1993
Creator: Harkins, D. A.; Armstrong, D. P.; Compton, R. N. & Ding, Dajun
Partner: UNT Libraries Government Documents Department

Synthesis and characterization of graphite-metal fluoride intercalation compounds

Description: The compound C/sub x/AsF/sub 5/ was prepared and characterized by x-ray diffraction and x-ray absorption, which show the presence of As(III) and As(V), and the As-F bond distances are consistent with AsF/sub 3/ and AsF/sup -//sub 6/, C/sup +//sub 8/AsF/sup -//sub 6/ and C/sup +//sub 8/OsF/sup -//sub 6/ were synthesized. The C/sub x/AsF/sub 6/ and numerous standard arsenic-flourine compounds were studied by x-ray absorption. Magnetic susceptibility of C/sup +//sub 8/OsF/sup -//sub 6/ confirms the high degree of oxidation in this compound. X-ray absorption studies were begun to determine the species present within the graphite when BrF/sub 3/ or GeF/sub 4/ + F/sub 2/ are added. In the BrF/sub 3/ case, Br/sub 2/ is evolved and only Br(III) is present in the graphite. The binary phase diagram XeF/sub 2/:Xe/sup +//sub 5/AsF/sup -//sub 6/ was investigated by melting point determination and Raman spectroscopy. This mixture near 1.3:1 forms a kinetically stable glass at room temperature and is molten at 50/sup 0/C. Several new species or phases are observed in the Raman spectra. These species have been assigned tentative structures.
Date: April 1, 1981
Creator: McQuillan, B.W.
Partner: UNT Libraries Government Documents Department

The synthesis and structural characterization of novel transition metal fluorides

Description: High purity KMF{sub 6} and K{sub 2}MF{sub 6} salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF{sub 6}. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF{sub 4} is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF{sub 4} type cell are derived from X-ray powder data for ReF{sub 4} and OsF{sub 4}. Fluoride ion capture from KAgF{sub 4} provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF{sub 3} and redetermination of the AuF{sub 3} structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF{sub 3} is the mixed valence compound Ag{sup II}Ag{sub 2}{sup III}F{sub 8}. Several new salts containing the (Ag - F){sub n}{sup n+} chain cation are prepared. The first linear (Ag - F){sub n}{sup n+} chain is observed in AgF{sup +}BF{sub 4 {sup {minus}}} which crystallizes in a tetragonal unit. AgFAuF{sub 4} has a triclinic unit cell and is isostructural with CuFAuF{sub 4}. AgFAuF{sub 6} has an orthorhombic unit cell and appears to be isostructural with AgFAsF{sub 6}. A second mixed valence silver fluoride, Ag{sup II}Ag{sup III}F{sub 5}, is prepared, which magnetic measurements indicate is probably an AgF{sup +} salt. Magnetic data for all of the AgF{sup +} salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic AG(II) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(II) and O{sub 2} to O{sub 2}{sup +}. Reactions with C{sub 6}F{sub 6} and C{sub 3}F{sub 6} suggest an electron capture mechanism for cationic AG(II) oxidations.
Date: September 1, 1992
Creator: Casteel, W. J. Jr.
Partner: UNT Libraries Government Documents Department

Mechanisms of selectivity loss during tungsten CVD (chemical vapor deposition)

Description: The tungsten subfluoride mechanism as well as other proposed mechanisms of selectivity loss are reviewed. To further demonstrate the viability of the tungsten subfluoride mechanism, we have extended the measurement of the tungsten subfluoride production rate down to 450{degree}C. We also report results from some preliminary experiments designed to identify the selectivity loss mechanism when elemental silicon is available for reaction. Comments regarding the origins of the insulator effect and selectivity loss for silane reduction are offered. 23 refs., 2 figs.
Date: January 1, 1990
Creator: Creighton, J.R.
Partner: UNT Libraries Government Documents Department

Oxidizing behavior of some platinum metal fluorides. [Xe complexes with Pt, Pd fluorides; Chlorine-2 oxidation by transition metal hexafluorides]

Description: The previously known compounds Xe/sub 2/F/sub 3//sup +/PtF/sub 6//sup -/, XeF/sup +/PtF/sub 6//sup -/ and XeF/sub 2/.2PtF/sub 4/(XePt/sub 2/F/sub 10/) were prepared by the interaction of XeF/sub 2/ with PtF/sub 4/. The new compounds XeF/sub 2/.PdF/sub 4/ and XeF/sub 2/.2PdF/sub 4/(XePd/sub 2/F/sub 10/) were produced by interaction of XeF/sub 2/ with either PdF/sub 4/ or Pd/sub 2/F/sub 6/. A weight loss-versus-time curve indicated the presence of 4:1, 3:1 and 2:1 XeF/sub 2//PdF/sub 4/ complexes. The thermal decomposition of XeFPtF/sub 6/ or XePd/sub 2/F/sub 10/ yields highly pure XeF/sub 4/. Thus the interaction of XeF/sub 2/ with platinum fluorides (PtF/sub 4/ or PtF/sub 5/) or palladium fluorides (Pd/sub 2/F/sub 6/ or PdF/sub 4/) provides for the conversion of XeF/sub 2/ to XeF/sub 4/. The compound XePd/sub 2/F/sub 10/ is a close structural relative of XePt/sub 2/F/sub 10/, and spectroscopic evidence suggests that both are salts of XeF/sup +/ and a polymeric (M/sub 2/F/sub 9/)/sub x//sup x-/ ion. A Xe:PtF/sub 6/ material of approximately 1:1 stoichiometry has been prepared and compared with XePdF/sub 6/(XeF/sub 2/.PdF/sub 4/). The interaction of chlorine with the third-series transition metal hexafluorides has been investigated. Gravimetric and tensimetric evidence indicate that the initial product of the Cl/sub 2/ plus IrF/sub 6/ reaction is a solid of composition Cl/sub 2/IrF/sub 6/. Vibrational spectroscopic and other evidence indicates that this solid yields a sequence of products, of which Cl/sub 3//sup +/IrF/sub 6//sup -/, Cl/sub 3//sup +/Ir/sub 2/F/sub 11//sup -/ and Ir/sub 4/F/sub 20/ have been identified, the last being the ultimate solid product of the room temperature decomposition of the adduct. A new chlorine fluoride generated in the room temperature decomposition of Cl/sub 2/IrF/sub 6/ has been tentatively formulated as Cl/sub 3/F from infrared evidence.
Date: October 1, 1978
Creator: Graham, L.
Partner: UNT Libraries Government Documents Department

The synthesis and structural characterization of novel transition metal fluorides

Description: High purity KMF[sub 6] and K[sub 2]MF[sub 6] salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF[sub 6]. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF[sub 4] is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF[sub 4] type cell are derived from X-ray powder data for ReF[sub 4] and OsF[sub 4]. Fluoride ion capture from KAgF[sub 4] provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF[sub 3] and redetermination of the AuF[sub 3] structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF[sub 3] is the mixed valence compound Ag[sup II]Ag[sub 2][sup III]F[sub 8]. Several new salts containing the (Ag - F)[sub n][sup n+] chain cation are prepared. The first linear (Ag - F)[sub n][sup n+] chain is observed in AgF[sup +]BF[sub 4 [sup [minus]]] which crystallizes in a tetragonal unit. AgFAuF[sub 4] has a triclinic unit cell and is isostructural with CuFAuF[sub 4]. AgFAuF[sub 6] has an orthorhombic unit cell and appears to be isostructural with AgFAsF[sub 6]. A second mixed valence silver fluoride, Ag[sup II]Ag[sup III]F[sub 5], is prepared, which magnetic measurements indicate is probably an AgF[sup +] salt. Magnetic data for all of the AgF[sup +] salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic AG(II) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(II) and O[sub 2] to O[sub 2][sup +]. Reactions with C[sub 6]F[sub 6] and C[sub 3]F[sub 6] suggest an electron capture mechanism for cationic AG(II) oxidations.
Date: September 1, 1992
Creator: Casteel, W.J. Jr.
Partner: UNT Libraries Government Documents Department