12039-88-2Relevant articles and documents
Antonov, V. N.,Antonov, Vl. N.,Jepsen, O.,Andersen, O. K.,Borghesi, A.,et. al.
, (1991)
Fei, G. T.,Liu, L.,Ding, X. Z.,Zhang, L. D.,Zheng, Q. Q.
, p. 280 - 282 (1995)
Composition of tungsten silicide films deposited by dichlorosilane reduction of tungsten hexafluoride
Hara,Miyamoto,Hagiwara,Bromley,Harshbarger
, p. 2955 - 2959 (1990)
The composition profile of tungsten silicide (WSix) films deposited by low-pressure chemical vapor deposition employing dichlorosilane (DCS) reduction of tungsten hexafluoride (WF6) is studied. Diffusion is the reaction rate-limiting process at chuck temperatures above 550°C and uniform in-depth composition profiles can be obtained. Below 550°C, however, the in-depth composition profile is not uniform for the surface reaction rate-limiting process. Tungsten-rich layers with a Si composition, x, of 1.5, are initially deposited due to the reduction of WF6 by the Si surface. This layer is amorphous or microcrystalline. Thereafter, the silicon content of the film increases with increasing thickness and a uniform composition profile is obtained as determined by the DCS/WF6 flow rate ratio in the chemical reaction. Chemical vapor-deposited tungsten silicide (WSix) films have been extensively used as polycide gate and interconnections for very large-scale integrated circuits.
Dense WSi2 and WSi2-20 vol.% ZrO2 composite synthesized by pressure-assisted field-activated combustion
Shon,Rho,Kim,Munir
, p. 120 - 126 (2001)
The simultaneous synthesis and consolidation of WSi2 and WSi2-20 vol.% ZrO2 from elemental powders of W, Si, and ZrO2 additive was investigated. The synthesis was carried out under the combined effect of an electric field and uniaxial pressure. The final density of the products increased nearly linearly with the applied pressure in the range 10 to 60 MPa. Highly dense WSi2 and WSi2-20 vol.% ZrO2 with relative densities of up to 98.0% were produced with the application of a 60 MPa pressure and a 3000 A DC current. The percentages of the total shrinkage occurring before and during the synthesis reaction were 17.5 and 82.5% for the case of WSi2, and 25.8 and 74.2% for the case of WSi2-20 vol.% ZrO2, respectively. The respective Vickers microhardness values for these materials were 8.2 and 10.6 GPa. From indentation crack measurements, the fracture toughness values for WSi2 and WSi2-20 vol.% ZrO2 were calculated to be 3.2 and 9.4 MPa m1/2, respectively.
WSix FORMATION IN W-Si MULTILAYERS.
Eicher,Bruce
, p. 868 - 871 (1987)
The formation of WSi//x phases from multiple thin layers of W and Si was investigated. Tungsten and silicon thin films of approximately 5 nm thickness were deposited sequentially onto GaAs substrates by dc magnetron sputtering from elemental targets. The total film thickness was approximately 300 nm. The multilayered structure was subjected to rapid thermal annealing at 900 degree C. The extent of the reaction, the grain size, and the crystal structure of the silicides were determined using transmission electron microscopy and X-ray diffraction. Schottky contacts were of good quality for x less than equivalent to 0. 52, with a barrier height ( PHI ) of 0. 7 V and an ideality factor (n) of 1. 15. Schottky contacts with higher silicon concentrations were poor. The WSi//x (x equals 0. 52) Schottky contact has been successfully incorporated into a self-aligned-gate field-effect transistor.
Trincat, F.,Regolini, J. L.,Mercier, J.,Bensahel, D.
, p. 3291 - 3293 (1991)
Tungsten silicide films deposited by SiH2Cl2-WF6 chemical reaction
Hara,Miyamoto,Yokoyama
, p. 1177 - 1180 (1989)
This paper studies tungsten silicide films deposited by the SiH2Cl2 (DCS)-WF6 chemical reaction. The deposition rat was held at around 1500 angstrom/min at temperatures above 500°C. However, the deposition rate decreased r
Determination of the standard free energies of formation for tungsten silicides by EMF measurements using lithium silicate liquid electrolyte
Fujiwara, Hiroyasu,Ueda, Yukitomi,Awasthi, Alok,Krishnamurthy, Nagaiyar,Garg, Sheo Parkash
, p. 307 - 312 (2005)
EMF measurements on silicon concentration cell were carried out using lithium silicate electrolyte in the temperature range 1300-1500 K. Using the EMF-temperature relations obtained, the standard free energies of formation for W5Si3 and WSi2 have been calculated as functions of temperature: ΔG0(W5Si3) (kJ mol-1) = -128.6 - 0.0132 (T (K)) ± 0.42 and ΔG 0(WSi2) (kJ mol-1) = -98.5 + 0.0095 (T (K)) ± 0.15, respectively. Combining the results with thermodynamic data, the standard enthalpies of formation for silicides at 298 K have been obtained as ΔH0(W5Si3, 298) (kJ mol-1) = -133 ± 25 and ΔH0(WSi2, 298) (kJ mol -1) = -82 ± 6, respectively. A new eutectoid reaction W 5Si3 ? W + WSi2 occurring around 700 K is suggested in W-Si binary system. Published by Elsevier B.V.
(Mo,W)5Si3-(Mo,W)Si2 eutectics: Properties and application in composite materials
Gnesin,Gurzhiyants,Borisenko
, p. 701 - 709 (2003)
Experimental data are presented on (Mo,W)5Si3 and (Mo,W)Si2 solid solutions and are analyzed using the known phase diagrams of the binary systems Mo-Si and W-Si. It is shown that, with increasing tungsten content, the melting temperature of the (Mo,W)5Si 3-(Mo,W)Si2 eutectic rises. Surprisingly, the alloys with W:Mo atomic ratios close to unity are found to contain, along with the suicide solid solutions, molybdenum disilicide almost free of tungsten. The mean room-temperature hardness of the eutectic alloys varies nonmonotonically with tungsten content and shows maxima at ?33 and ?75 at. % W. The surface texture is found to have a significant effect on the rate of high-temperature gas corrosion. The possibility of compositional control (variations in the W:Mo and (Mo,W)5Si3:(Mo,W)Si2 ratios) over the thermal expansion of the alloys is analyzed. Data are presented on the temperature-dependent resistivity of SiC-matrix composites.
