12039-88-2Relevant articles and documents
Tungsten Disilicide (WSi2): Synthesis, Characterization, and Prediction of New Crystal Structures
Lukovi?, Jelena,Zagorac, Dejan,Sch?n, J. Christian,Zagorac, Jelena,Jordanov, Dragana,Volkov-Husovi?, Tatjana,Matovi?, Branko
, p. 2088 - 2094 (2017)
Transition metal silicides have attracted great attention due to their potential applications in microelectronics, ceramics, and the aerospace industry. In this study, experimental and theoretical investigations of tungsten based silicides were performed.
PROPERTIES OF CHEMICAL VAPOR DEPOSITED TUNGSTEN SILICIDE FILMS USING REACTION OF WF6 AND Si2H6.
Shioya,Ikegami,Kobayashi,Maeda
, p. 1220 - 1224 (1987)
Tungsten silicide films were formed by the chemical vapor deposition method using the reaction WF//6 and Si//2H//6. The deposition rate, resistivity, composition, stress, crystal structure, and content of impurities were studied and compared with tungsten silicide films deposited by reaction of WF//6 and SiH//4. The tungsten silicide films made using Si//2H//6 have a higher deposition rate and higher Si concentration than those made by using SiH//4 at the same substrate temperature. For these reasons, the tungsten silicide films made by using Si//2H//6 were found to have a resistivity that is a little higher and, after annealing, a stress that is smaller than that made by SiH//4. Also, the resistance of tungsten silicide to peeling is larger than that of the film made by using SiH//4.
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.
CHANGES IN RESISTIVITY AND COMPOSITION OF CHEMICAL VAPOR DEPOSITED TUNGSTEN SILICIDE FILMS BY ANNEALING.
Shioya,Itoh,Kobayashi,Maeda
, p. 1475 - 1479 (1986)
Chemical vapor deposited (CVD) tungsten silicide films were formed by a cold wall reactor. These films were annealed in N//2 to investigate changes in resistivity, composition, thickness, and impurity. The change in resistivity after 1000 degree C annealing becomes larger as the film reaches the stoichiometric value. A composition change occurs in a film whose composition Si/W is more than 2. 6. Excess Si in the WSi//x films (x greater than 2. 6) is segregated in the boundary between WSi//x and poly-Si. A thickness change of about 15% occurs after 1000 degree C annealing at WSi//2//. //4 on SiO//2; this value is smaller than the calculated value. F and H, which are impurities in WSi//x films decrease gradually and diffuse into gate SiO//2 after 1000 degree C annealing.
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.
Chemical reactions, anisotropic grain growth and sintering mechanisms of self-reinforced ZrB2-SiC doped with WC
Zou, Ji,Sun, Shi-Kuan,Zhang, Guo-Jun,Kan, Yan-Mei,Wang, Pei-Ling,Ohji, Tatsuki
, p. 1575 - 1583 (2011)
Transmission electron microscopy study of pressureless sintered ZrB 2-20 vol% SiC composites with WC (5-10 vol%) additions was carried out in this work. Two independent chemical reactions in which the ZrO 2 impurities were removed from ZrB2 grain surface were confirmed. Three new formed phases, (W, Zr)ssB, (Zr, W) ssC, and (W, Zr)ssSi2, apart from the plate-like ZrB2 and SiC grains, were identified in the samples. Microstructure observations strongly suggest that the liquid phases in terms of (W, Zr)ssB and (W, Zr)ssSi2, appear in this system during the sintering process below 2200°C, and the former could well wet the ZrB2 grain boundaries. The mass transport process between ZrB2 and (W, Zr)ssB was also confirmed by scanning-transmission electron microscope analysis. The above results supports that the densification at 2200°C is assisted by liquid phase and the elongation of ZrB2 platelets resulted from the Ostwald ripening during the dissolution-diffusion-precipitation process.
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.
In situ barrier formation using rapid thermal annealing of a tungsten nitride/polycrystalline silicon structure
Lee, Byung Hak,Lee, Kee Sun,Sohn, Dong Kyun,Byun, Jeong Soo,Han, Chang Hee,Park, Ji-Soo,Han, Sang Beom,Park, Jin Woon
, p. 2538 - 2540 (2000)
This letter describes the use of rapid thermal annealing (RTA) to form a barrier layer applicable to the gate electrode in dynamic random access memory devices with a stacked structure [tungsten nitride (WNx)/polycrystalline Si (poly-Si)]. After RTA, the reactively sputtered amorphous WNx film on the poly-Si was transformed to a low-resistive α-phase W and nitrogen-segregated layer. Most of the nitrogen in the WNx film was dissipated and a relatively small amount of the nitrogen was segregated at the interface of the α-phase W and poly-Si. The segregated layer was estimated to be 2 nm thick and revealed a silicon nitride (Si-N) bonding status. More importantly, we found that this thin segregated layer successfully protected the formation of tungsten silicide, even after RTA at 1000°C for 2 min in a hydrogen environment.
High frequency induction heated synthesis and consolidation of nanostructured TaSi2-WSi2 composite
Shon, In-Jin,Kang, Hyun-Su
, p. 5471 - 5474 (2015)
A dense nanostructured TaSi2-WSi2 composite was simultaneously synthesized and sintered by the high frequency induction heating method within 2 minutes from mechanically activated powder of Ta, W and Si. A highly-dense TaSi2-WSi2 composite was produced under simultaneous application of a 80 MPa pressure and the induced current. The mechanical properties and microstructure were investigated.
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
