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Tungsten metal vias

With a tungsten pentacarbonyl catalyst, the calculated mechanisms are summarized in Scheme 4.15 [26]. Coordination of the 4-pentyn-l-ol substrate to the pentacarbonyl tungsten leads to the formation of the 7i-alkyne-W(CO)5 adduct Wl. This coordination process was calculated to be exothermic by 24.3 kcal mol. The cydoisomerization leading to a five-membered-ring exo product starts with the 7i-complex Wl via a one-step process with a barrier of 46.5 kcal mol (path a of Scheme 4.15). The barrier calculated here is comparable with that calculated for the catalyst-free process. From Wl to W3, the tungsten metal center does not play a significant role in the isomerization process. [Pg.144]

In a third class of 7t-cyclopentadienyl complexes, compounds of type LVIII are bound to a transition metal via the lone pair at the germanium atom. The first compounds in this series, the pentacarbonyl-[chloro(pentamethylcyclopentadienyl)germylene]chromium(0) (LIXa) and -tungsten(O) (LIXb) were synthesized by alkylation of the ylide complexes (CO)5M—GeCl2 THF according to Eq. (22) (201). Nucleophilic substitution reactions of LIXb lead to the alkyl- and amino-substituted complexes LIXc-e [Eq. (23)] (202). [Pg.264]

With more stringent requirements on alignment tolerances and planarization in multilevel designs, it is important to fill in the contact and via holes with metal to maintain acceptable step coverage. The step coverage by sputtered aluminum rapidly decreases with increasing aspect ratio. Instead of the sputtered aluminum, tungsten metal has been widely used to fill in the contacts and vias by the CVD technique. [Pg.647]

In the future, the continued scale-down in ULSI features will need more stringent requirements with respect to the electrical conductivity of materials for the contacts and vias. Copper has higher electrical conductivity than aluminum. The future demand for tungsten hexafluoride will be affected by the improvement in tungsten metallization and the progress in the technology of copper metallization. [Pg.648]

Oxidizers For metal CMP, most of the chemical reactions are electrochemical in nature. Oxidizers react with metal surfaces to raise the oxidation state of the metal via a reduction-oxidation reaction, resulting in either dissolution of the metal or the formation of a surface film on the metal. For both tungsten and copper, polish rate has been shown to be proportional to the rate of these reduction-oxidation reactions (see Chapters 6 and 7). [Pg.40]

Figure 3-4. A cross-section of a double-layer metal with capping layer, barrier layer, and tungsten-filled via holes [250]. Figure 3-4. A cross-section of a double-layer metal with capping layer, barrier layer, and tungsten-filled via holes [250].
First, a thin barrier layer of titanium is deposited by PVD on the wafer to line the bottom and the inside walls of the via-1 holes. The titanium serves to improve the adhesion of the tungsten plug to the ILD-1 oxide. Next, titanium nitride (TiN) is immediately deposited over the titanium as a diffusion barrier for the tungsten metal. Then, tungsten metal is deposited by CVD to fill the via-1 holes and coat the entire wafer. Finally, the tungsten is polished down to the upper surface of... [Pg.783]

Further experiments have dealt with the generation of more stable tungsten silanols via ligand exchange at the metal and the reactivity of the iron-substituted silanol 5 in controlled condensation reactions. [Pg.488]

The high cost of noble metal catalysts limited their commercial application. Advanced catalysts of both low cost and high catalytic activity, such as WO3 [62] and Mn304 [63], are studied. Yao et al. [62] prepared a carbon paper electrode coated with supported tungsten trioxide via an impregnation method, which resulted in improved electrocatalytic activity towards both VO /V02 and redox reactions. As shown in Figure 9.23a,... [Pg.371]

Isothiazole and its 4- and 5-methyl derivatives react with chromium and tungsten hexacar-bonyls under the influence of light to give pentacarbonylmetal compounds, the metal being coordinated via the nitrogen atom (72JOM(44)325, 75MI41702). [Pg.153]

Hydrogen reduction has a major advantage in that the reaction generally takes place at lower temperature than the equivalent decomposition reaction. It is used extensively in the deposition of transition metals from their halides, particularly the metals of Groups Va, (vanadium, niobium, and tantalum) and Via (chromium, molybdenum, and tungsten). The halide reduction of Group IVa metals (titanium, zirconium, and hafnium) is more difficult because their halides are more stable. [Pg.70]

Borides of Group Via. As with the borides of Group Va, the incorporation of free metal in the Group Via borides is difficult to avoid. Both tungsten and molybdenum borides are obtained at high temperature by the hydrogen reduction of the mixed bromides.Bonding appears a more effective method to form these borides in thin layers (see Sec. 2.2 above). [Pg.326]

Interconnect. Three-dimensional structures require interconnections between the various levels. This is achieved by small, high aspect-ratio holes that provide electrical contact. These holes include the contact fills which connect the semiconductor silicon area of the device to the first-level metal, and the via holes which connect the first level metal to the second and subsequent metal levels (see Fig. 13.1). The interconnect presents a major fabrication challenge since these high-aspect holes, which may be as small as 0.25 im across, must be completely filled with a diffusion barrier material (such as CVD titanium nitride) and a conductor metal such as CVD tungsten. The ability to fill the interconnects is a major factor in selecting a thin-film deposition process. [Pg.349]

The application of ly transition metal carbides as effective substitutes for the more expensive noble metals in a variety of reactions has hem demonstrated in several studies [ 1 -2]. Conventional pr aration route via high temperature (>1200K) oxide carburization using methane is, however, poorly understood. This study deals with the synthesis of supported tungsten carbide nanoparticles via the relatively low-tempoatine propane carburization of the precursor metal sulphide, hi order to optimize the carbide catalyst propertira at the molecular level, we have undertaken a detailed examination of hotii solid-state carburization conditions and gas phase kinetics so as to understand the connectivity between plmse kinetic parametera and catalytically-important intrinsic attributes of the nanoparticle catalyst system. [Pg.781]


See other pages where Tungsten metal vias is mentioned: [Pg.130]    [Pg.325]    [Pg.1632]    [Pg.5]    [Pg.646]    [Pg.449]    [Pg.4983]    [Pg.182]    [Pg.73]    [Pg.119]    [Pg.110]    [Pg.215]    [Pg.2]    [Pg.1143]    [Pg.4982]    [Pg.1379]    [Pg.282]    [Pg.137]    [Pg.313]    [Pg.502]    [Pg.1017]    [Pg.145]    [Pg.108]    [Pg.783]    [Pg.325]    [Pg.325]    [Pg.28]    [Pg.81]    [Pg.86]    [Pg.212]    [Pg.47]   
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