The  invention relates to an improved process for the forming and etching of tungsten containing film on a semiconductor wafer.Refractory metals such as chemical vapor deposited tungsten have been identified as suitable interconnect material for VLSI/ULSI applications. Chemical vapor deposited tungsten is finding applications in the area of gate and interconnect technology due to its electromigration resistance, excellent step coverage, and because its thermal expansion is similar to that of silicon. Chemical vapor deposited tungsten also withstands higher process temperatures and does not form hillock as will aluminum.

This invention  described an useful embodiment of a process for etching of a tungsten film which comprises the steps of: removing tungsten from unmasked areas of a workpiece using a first etchant that removes tungsten at a greater rate than it removes photoresist; and removing tungsten from unmasked areas of the workpiece using a second etchant that removes tungsten at a greater rate than it removes silicon dioxide.

The invention is directed to a process for purifying tungsten hexafluoride to produce a pure material useful in applications such as the electronics industry in which the impurities level is required to be reduced as much as possible to avoid adverse effects. The steps are as follows:

a) evaporating tungsten hexafluoride from said non-volatile impurities dissolved in said liquid tungsten hexafluoride, b) condensing the evaporated tungsten hexafluoride, c) freezing the condensed tungsten hexafluoride to solid tungsten hexafluoride, d) evacuating volatile impurities from said solid tungsten hexafluoride, e) thawing said solid tungsten hexafluoride to liquid tungsten hexafluoride to release volatile impurities trapped in said solid tungsten hexafluoride to the gas phase, f) heating the thawed tungsten hexafluoride to a temperature above the boiling point of tungsten hexafluoride under pressure in a closed container whereby volatile impurities dissolved in the thawed tungsten hexafluoride are removed and collected above the thawed tungsten hexafluoride and heating the thawed tungsten hexafluoride, g) venting the volatile impurities collected above the thawed tungsten hexafluoride into an evacuated space. 

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A method of forming a composite tungsten film on a substrate is described. The composite tungsten film comprises sequentially deposited tungsten nucleation layers and tungsten bulk layers. Each of the tungsten nucleation layers and the tungsten bulk layers have a thickness less than about 300 Å. The tungsten nucleation layers and the tungsten bulk layers are formed one over the other until a desired thickness for the composite tungsten film is achieved. The resulting composite tungsten film exhibits good film morphology. The tungsten nucleation layers may be formed using a cyclical deposition process by alternately adsorbing a tungsten-containing precursor and a reducing gas on the substrate. The tungsten bulk layers may be formed using a chemical vapor deposition (CVD) process by thermally decomposing a tungsten-containing precursor.

A method of filling an opening in an insulating layer of an integrated circuit. First a tungsten-silicide layer is deposited over the opening. Next a tungsten layer is deposited onto the tungsten-silicide layer such that the opening is substantially filed with tungsten. The tungsten and tungsten-silicide layer are then chemically-mechanically polished back until the insulating layer is substantially revealed.

The present invention relates to a new tungsten-based catalyst on a zirconia and/or titanium dioxide support. At the present time, there is no tungsten/zirconia catalyst which has a high content of tungsten and no additive and which is active after calcination at a temperature less than or in the order of 700° C., or even 600° C.

Various authors indeed propose that the strong acid sites correspond to the formation of micro fields of tungsten trioxide (WO3). This hypothesis allows several experimental observations to be reconciled: the increase in activity with the percentage of tungsten (20% above the most active), the need to heat the solid to a temperature where sintering begins to become evident, as well as the observation in the Raman spectrum of lines which correspond to the clusters of WO3.  In some cases, the isolated atoms of tungsten are in a deformed octahedral environment and that there is no tetrahedral tungsten in the case of a tungsten/zirconia solid. 

It can be determined from this that current tungsten/zirconia catalysts substantially comprise octahedral tungsten, probably owing to the process of preparation thereof which is based on the use of metatungstates which decompose into WO42− ions only at a very basic pH at which the zirconia does not fix anions. 

This invention relates to metallization used in semiconductor devices.alternatives to aluminum have been sought for at least portions of the metallization. One commonly contemplated alternative metal is low pressure chemical vapor deposition (LPCVD) tungsten. LPCVD tungsten is a desirable alternative because it has a conformal step coverage. LPCVD tungsten also offers advantages for use as interconnects. Besides having conformal step coverage, it has high electromigration resistance, resistance to hillock formation and high temperature stability. Although many methods of depositing LPCVD tungsten have been proposed, they are all included within two generic categories which are conveniently termed selective and blanket.

Hardide Coatings Limited, which has developed a revolutionary tungsten carbide-based coating for chrome replacement programmes, has entered into a three year coatings approval test programme with Airbus and has confidence tests being performed at seven further key aerospace industry manufacturers.

The precision coating, which made its Farnborough debut in 2006, provides excellent wear resistance against abrasion, erosion and corrosion on components made from ferrous and nickel-based alloys. It coats internal surfaces and offers significant technical and environmental advantages over hard chrome and HVOF. Independent ASTM G65 testing has shown that Hardide wears out 40 times slower than abrasion resistant AR-500, 12 times slower than hard chrome and four times slower than thermal spray tungsten carbide.

The current primary market for the coating is the oil and gas exploration and production industry where Hardide-coated components are in widespread use in extreme downhole and drilling applications around the world. The coating is also in service in the valve, power, chemical and food manufacturing industries.

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