Showing papers on "Tungsten published in 1989"

Process for CVD deposition of tungsten layer on semiconductor wafer

Abstract: An improved process is disclosed for the deposition of a layer of tungsten on a semiconductor wafer in a vacuum chamber wherein the improvements comprise depositing tungsten on the semiconductor wafer in the presence of nitrogen gas to improve the reflectivity of the surface of the resulting layer of tungsten; maintaining the vacuum chamber at a pressure of from about 20 to 760 Torr to improve the deposition rate of the tungsten, as well as to improve the reflectivity of the tungsten surface; and, when needed, the additional step of forming a nucleation layer on the semiconductor layer prior to the step of depositing tungsten on the semiconductor wafer to improve the uniformity of the deposited tungsten layer.

Cobalt-bound tungsten carbide metal matrix composites and cutting tools formed therefrom

Abstract: Cobalt-bound tungsten carbide metal matrix composites having a unique microstructure are produced by consolidating partially sintered greenware under high pressures, e.g., 120,000 psi, at temperatures less than those used for conventional liquid phase sintering in a relatively short time, e.g., from less than one minute to less than about one hour. The composites have a binder phase which contains less than about 80 weight percent of the tungsten found in a composite prepared from the same or similar compositions via liquid phase sintering. These composites provide cutting tools with both toughness and wear resistance which exceed that of cutting tools made from the same or similar compositions via liquid phase sintering.

Visible light and infra-red cooking apparatus

Abstract: An oven using one or more quartz tungsten light bulbs capable of producing 1.5 kW of radiant energy of which a significant portion is light energy in the 0.4 to 0.7 μm wavelength range impinges high intensity visible light wave radiation directly onto a food item. Light sources can be positioned above and below the food item and the inner walls of the oven are preferably highly reflective to reflect light energy onto the food. The intensity of the visible light source is automatically controllable and can be varied throughout the cooking cycle.

Multiple metal coated superabrasive grit and methods for their manufacture

Abstract: Multiple metal coated diamond grit for improved retention in a tool matrix comprises a first layer coating of a metal carbide of a strong carbide former, preferably chromium, titanium or zirconium, chemically bonded to the diamond and a second metal coating of an oxidation resistant carbide former, preferably tungsten or tantalum, chemically bonded to the first metal layer. A third metal layer coating of an alloying metal, preferably nickel, can also be added. In accordance with the method of the present invention, the first layer metal can be applied by metal vapor deposition. The second layer metal can be applied by chemical vapor deposition. The third layer of an alloying metal can be applied by electroless or electrolytic plating.

Process for selective deposition of tungsten on semiconductor wafer

Abstract: An improved process for the selective deposition of tungsten on a masked semiconductor wafer is disclosed which comprises cleaning the surfaces of the wafer in an air-tight cleaning chamber, then transferring the cleaned wafer to a vacuum deposition chamber such as a CVD chamber for selective deposition of tungsten thereon without exposing the cleaned wafer to conditions which would recontaminate the cleaned wafer prior to said deposition, and then selectively depositing tungsten on the unmasked surfaces of the cleaned wafer.

Aspects of the oxygen atom transfer chemistry of tungsten

Abstract: The oxygen atom transfer chemistry of most elements that form stable metal-oxo compounds, among them tungsten, is unsystematically developped at present. Reported here are certain aspects of the oxo transfer chemistry of tungsten Schiff base and N,N-disubstituted dithiocarbamate (R 2 dtc) complexes, which are compared with the far more extensively examined chemistry of molybdenum with these ligands. A reproducible preparation of WO 2 (acac) 2 (4, acac=acetylacetonate(1−) is described

Process for making CMOS device with both P+ and N+ gates including refractory metal silicide and nitride interconnects

Abstract: A process for making CMOS device wherein the N-channel devices have n+ gates, and the P-channel devices have p+ gates. A TiN local interconnect system is used to connect the two types of gates, as well as providing connections to moat. A titanium nitride layer may be formed by depositing titanium metal everywhere, and then heating the integrated circuit structure in a nitrogen atmosphere. This process may also be used with other refractory metal nitride interconnect layers. In addition to titanium based thin film compositions, other metals can be substituted and used for direct-react silicidation and simultaneous formation of a conductive nitride to form local interconnects, including molybdenum, tungsten, vanadium, cobalt, and others.

Electrodeposition and Characterization of Three‐Dimensional Tungsten(VI, V)‐Oxide Films Containing Spherical Pt Microparticles

Abstract: Simultaneous reductive electrodeposition of metallic platinum and tungsten(VI, V)‐oxide aggregates was carried out by potential cycling in colloidal suspensions in . The nonstoichiometric centers in the reduced deposits were found to mediate chloroplatinate electroreduction. Scanning electron microscopy was used to examine the morphology and distribution of Pt in the W(VI, V)‐oxide supports. Auger electron spectrometry allowed detection of Pt, W, and C in films on graphite and was employed to characterize the elemental depth profiles. The spherical Pt microparticles were randomly dispersed in the oxide matrix. The size and density of the particles were dependent on the rate of potential scan during electrodeposition. The Pt spheres tended to be larger and denser when they were formed from more concentrated chloroplatinate solutions. Absorption spectroscopy coupled with electrochemistry showed evidence for the partial reduction of the tungsten oxide support at −0.3V vs. SCE. Cyclic voltammetric experiments indicated that the tungsten‐based redox transitions in the platinized oxide were essentially reversible and that their energetics were affected by dispersed Pt. The mutual metal‐support interactions apparently involve desorption and spillover of H from Pt. This process seems to be coupled with the absorption of hydrogen by and apparently favors the formation of hydrogen W‐bronzes. The long‐term stability of the coating and the durability of the immobilized Pt were apparent from diagnostic experiments that included sonication and prolonged cyclic oxidations and rereductions in .

Microdynamic release structure

Abstract: A selective chemical vapor deposition (CVD) tungsten process is used to fabricate three-dimensional tungsten cantilever beams on a substrate. Two beams form micromechanical tweezers that move in three dimensions by the application of potential differences between the beams, and between the beams and the silicon substrate. A high deposition rate selective tungsten CVD process is used to fabricate beams of greater than 3 micrometers thickness in patterned, CVD silicon dioxide trenches ion-implanted with silicon. Tweezers 200 micrometers in length with a cross section of 2.7 by 2.5 micrometers will close upon application of a voltage of less than 150 volts.

Method for selectively filling contacts or vias or various depths with CVD tungsten

Abstract: A method of making planarized metallization on a semiconductor substrate employing selective deposition.

Preparation of polycyclooctyne by ring-opening polymerization employing d0 tungsten and molybdenum alkylidyne complexes

Abstract: Addition de cyclooctyne a W 2 (O-t-Bu) 6 dans le toluene ou le dichloromethane. Temperatures de fusion (62±4 o C), de transition vitreuse (65 o C) et de degradation thermique (390 o C)

Plasma-nitridated self-aligned tungsten system for VLSI interconnections

Abstract: A process for forming a diffusion barrier on exposed silicon and polysilicon contacts of an integrated circuit including the step of chemically vapor depositing a layer of tungsten in a self-aligned manner on the exposed contact areas. The layer of tungsten is plasma nitridated to form a tungsten nitride layer and to partially form a tungsten silicide layer adjacent the contact areas. The formation of the tungsten silicide layer is completed by thermal annealing.

Selective chemical vapor deposition of tungsten for microdynamic structures

Abstract: A selective chemical vapor deposition (CVD) tungsten process is used to fabricate three-dimensional tungsten cantilever beams on a silicon substrate. Two beams form micromechanical tweezers that move in three dimensions by the application of potential differences between the beams, and between the beams and the silicon substrate. A high-deposition-rate selective tungsten CVD process is used to fabricate beams of greater than three microns thickness in patterned CVD SiO/sub 2/ trenches ion-implanted with silicon. Tweezer 200- mu m in length with a cross section of 2.7 mu m*2.5 mu m close with an applied voltage of less than 150 V. The magnitude of the deflection and the beam profile are compared to results obtained using simulations of the electric field and dynamic mechanical simulations of the tweezers. >

Sintering of Advanced Ceramics

Abstract: Topics covered in this book include: Sintering of silicon carbide with rare earth oxide additions; Hiping of alumina; and Liquid phase sintering of tungsten.

Method of manufacturing self-aligned conformal metallization of semiconductor wafer by selective metal deposition

Abstract: A method is disclosed for fabricating a semiconductor integrated circuit which includes the selective deposition of a metal, such as tungsten, into a contact opening formed in a dielectric layer, followed by the deposition of a thin silicon layer over the dielectric and metal-filled opening and the deposition of a second dielectric layer over the thin silicon layer. An opening or trench is formed in the upper second dielectric layer using the silicon as an etch stop, and a metal such as tungsten is selectively deposited to fill the trench wherever the exposed silicon is present. In one embodiment of the invention, prior to the filling of the trench, the exposed silicon is reacted with a blanket layer of a metal to form a metal silicide layer at the lower surface of the trench.

Ceramic substrate with metal filled via holes for hybrid microcircuits and method of making the same

Abstract: An as-fired alumina substrate for a hybrid microcircuit formed of GaAs dies operating at gigahertz frequencies has a large number of about 0.013" diameter via holes drilled on the surface thereof by use of a laser. A metal filling in each via hole is formed with about 85% sintered tungsten and 15% copper reflowed into the pores thereof to provide a composition that has a thermal coefficient of expansion that substantially matches that of the GaAs dies and the alumina substrate and also provides for hermetically sealing the via holes. The alumina substrate is further provided with a ground plane by which it is mounted on a metal block serving as a heat sink. The high frequency GaAs dies mounted on the via holes use the metal fillings therein to carry their internally generated heat to the heat sink and to provide low inductance ground paths for the microcircuit. A process for placing the metal filling in the via holes makes use of a stencil having the same large number of via holes thereon as the alumina substrate for first squeegeeing a tungsten paste with a predetermined amount of binder into the via holes of the substrate. After the tungsten is sintered, the stencil is then used to squeegee a copper paste on the top of the sintered tungsten in the via holes. The copper in the paste is then reflowed into the pores of the sintered tungsten.

Process for the production of curve glazing with a high transmittance in the visible spectral range and a high reflectance for thermal radiation

Abstract: A system of layers is built up on substrates of mineral glass in the following order: first layer: an oxide from the group, stannic oxide, silicon dioxide, aluminum oxide, tantalum oxide, zirconium oxide, or their mixed oxides; second layer: a metal from the group, tantalum, tungsten, nickel, iron; third layer: silver or a silver alloy containing at least 50 weight-percent of silver; fourth layer: a metal from the group, tantalum, tungsten, nickel, iron or their alloys; fifth layer: an oxide from the group, stannic oxide, silicon dioxide, aluminum oxide, tantalum oxide, zirconium oxide or their mixed oxides. After that, the substrate with all the coating layers is heated to the softening temperature of the glass in an oxidizing atmosphere and bent to the final shape.