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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1063
`Exhibit 1063, Page 1
`
`

`

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`U.S. Patent ee
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`Jan. 4, 2000
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`
`Sheet 1 of 3
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`6,010,583
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`
`
`Ex. 1063, Page 2
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`Ex. 1063, Page 2
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`

`

`U.S. Patent
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`Jan. 4, 2000
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`Sheet 2 of 3
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`6,010,583
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`Ex. 1063, Page 3
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`Ex. 1063, Page 3
`
`

`

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`Sheet 3 of 3
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`6,010,583
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`
`Jan. 4, 2000
`
`U.S. Patent
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`
`
`Ex. 1063, Page 4
`
`Ex. 1063, Page 4
`
`

`

`6,010,583
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`10
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`1
`METHOD OF MAKING UNREACTED
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`METAL/ALUMINUM SPUTTER TARGET
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`FIELD OF THE INVENTION
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`This invention relates generally to sputtering targets, and
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`more specifically to methods of making high performance,
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`high density sputtering targets composed of aluminum and
`a non-aluminum metal.
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`BACKGROUND OF THE INVENTION
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`Sputtering targets are used in the formation of semicon-
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`ductor substrates as a source of material to be deposited on
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`the substrates. In some applications layers of alloys com-
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`posed of one or more metals are deposited onto the surface
`15
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`of a substrate to improve performance and characteristics of
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`individual products. For example, magnetron sputtering is a
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`widely used method to deposit thin layers of aluminum and
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`non-aluminum metal alloys onto flat and patterned sub-
`strates. The fabricated substrates are then used in the manu-
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`facture of products such as integrated circuits, memory
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`storage devices, magnetic recording or reproducing
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`apparatus, and ink-jet heads.
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`Metals to be deposited on a semiconductor substrate are
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`removedfrom the sputtering target by a plasma. The quality
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`of the resultant semiconductor substrate depends on the
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`quality of the sputtering target supplying the material, which
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`in turn depends on the quality of its fabrication. The fabri-
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`cation of the sputtering target, in particular the target com-
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`position and structure,
`is important in achieving a high
`30
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`performance, high density substrate.
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`Improperly fabricated sputtering targets have several
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`undesirable features such as low density, the presence of
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`intermetallic compounds, and a non-uniform composition.
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`Low density sputtering targets are undesirable because they
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`cause outgassing during pumpdown,whereair trapped in the
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`target either increases the time for the desired level of
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`vacuum to be reached, or prevents the necessary vacuum
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`from being reachedat all, thus reducing uptimeofthe target.
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`Additionally, impurities in the air trapped in the target can
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`contaminate the film. Intermetallic compoundsare brittle
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`and mayresult in sputtering target failure during fabrication
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`or operation. A non-uniform composition of the sputtering
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`target 1s undesirable because it reduces the substrate yield,
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`since the non-uniform composition is reproduced on the film
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`coating the substrate.
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`One method of solving the problem of improperly fabri-
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`cated or nonhomogeneoussputtering targets, and hence the
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`problem of reduced substrate yield, has been to use separate
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`targets as sources for the aluminum and the non-aluminum
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`metal. This method, however,
`is inefficient
`in that
`the
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`sputtering targets must be mechanically rotated to average
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`out the composition from each metal. Additionally, mechani-
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`cal rotation has only been used when the non-aluminum
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`metal was tantalum,thus its applicability to non-aluminum
`metals other than tantalum is unknown.
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`It would be advantageousto fabricate a sputtering target
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`that is a homogeneous composition of an unreacted alumi-
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`num and non-aluminum metal and that contains greater than
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`about 2% to 5% by weight of aluminum. This would be
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`sufficient to allow formation of an aluminum layer around
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`the non-aluminum metal. Therefore, a high quality, high
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`performance, substantially uniform sputtering target, and an
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`efficient method of fabricating such a target, is needed.
`SUMMARYOF THE INVENTION
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`To this end, the present invention provides a method of
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`making a high performance, high density sputter target
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`40
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`2
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`composed of a homogeneous mixture of aluminum and a
`non-aluminum metal.
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`The present
`invention also provides a sputter target
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`formed by the method of the invention. Such a sputter target
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`has high performance, high purity, and is a composition,
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`structure and density that is substantially uniform across the
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`body of the sputter target.
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`The present invention also provides a high performance,
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`high density sputter target that is a hot pressed evacuated
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`machined cylinder of a cold pressed blend of a non-
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`aluminum metal powder and an aluminum powder.
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`According to one embodiment, a non-aluminum reactive
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`metal such astitanium, tantalum, niobium, zirconium, iron
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`or nickel, is fabricated into a powderby a hydride-dehydride
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`process. In alternative embodiments,
`the powder may be
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`fabricated by a sodium reduction process or an inert gas
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`atomization process. The non-aluminum reactive metal
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`powder may have a spheroidal, angular, or granular mor-
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`phology. The non-aluminum metal powder is preferably
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`between about 6 wm and about 300 ym, and is most
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`preferably between about 6 wm and about 45 wm. An
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`aluminum metal body is also fabricated into a powder by a
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`mechanical comminution process or an inert-gas atomiza-
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`tion process. The aluminum powder, which may have a
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`spheroidal morphology,is preferably less than about 300 um
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`and is most preferably less than about 45 um.
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`The non-aluminum and aluminum powders are blended
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`with 1" longx0.5" wide cylinders of pure aluminum for at
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`least 2 hours. A solvent such as alcohol or acetone, or a
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`binder such as stearic acid or stearates may be addedto the
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`powders to enhance blending. The blend is subjected to cold
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`pressing in either a uniaxial, biaxial or hydrostatic direction.
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`In a preferred embodiment, the blended powders are sub-
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`jected to cold isostatic pressing at a pressure of about 30 ksi
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`to form a blank. The blanks are machined into a right
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`cylinder, then the cylinder is subjected to hot pressing under
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`a vacuum. Hotpressing is preferably performedat at least
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`about 107° torr at a temperature less than 0.9 times the
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`melting temperature in degrees Kelvin of aluminum (0.9 T,,
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`of aluminum) and at a pressure of at least about 5 ksi.
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`In an alternative embodiment, a non-aluminum reactive
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`metal powder is blended with an aluminum powder. The
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`blend is subjected to cold pressing and is then assembled
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`into a mosaic. The mosaic is subjected to either hot isostatic
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`pressing, vacuum hot pressing, inert gas hot pressing, or
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`pressure-less sintering at a temperature below 0.9 T,, of
`aluminum.
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`The unreacted non-aluminum metal/aluminum sputtertar-
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`get formedis a high performance, high density sputtertarget.
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`It has a substantially uniform composition, structure and
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`density across the body of the target and a non-aluminum
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`metal average particle size of about 30 um.
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`Byvirtue of the foregoing,there is thus provided a sputter
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`target of aluminum and a non-aluminum reactive metal
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`containing greater than about 2% to 5% by weight of
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`aluminum and a method of making such a sputter target.
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`These and other objects and advantages of the present
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`invention shall be made apparent from the accompanying
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`description thereof.
`BRIEF DESCRIPTION OF THE FIGURES
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`FIGS. 1A, 1B, and 1C are a series of photomicrographs
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`showing a sputter target made by an early unrefined method
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`of the present invention.
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`FIGS. 2A, 2B, and 2C are a series of photomicrographs
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`showing a sputter target made by the method of the present
`invention.
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`Ex. 1063, Page 5
`
`Ex. 1063, Page 5
`
`

`

`6,010,583
`
`
`
`
`3
`DETAILED DESCRIPTION
`
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`With reference to FIGS. 1A, 1B, and 1C and FIGS. 2A,
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`2B and 2C,a high performance, high purity sputter target is
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`formed by the method of the present invention. The sputter
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`target is composed ofa substantially homogeneous mixture
`of an aluminum and a non-aluminum metal. As shown in
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`FIG. 1A,an early unrefined method of the present invention
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`produced a sputter target with macroscopic segregation of
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`the aluminum particles 20, resulting in aluminum agglom-
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`erate 30. The agglomerates 30 are an irregularly-shaped
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`collection ofat least about fourto five aluminum particles 20
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`with an aggregate size of at least about 50 zm. As shown in
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`FIG. 1B,
`the early unrefined method produced a sputter
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`target showing microsegregation of aluminum powder par-
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`ticles 20 of about 100—200 um in diameter. As shown in FIG.
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`1C, the early unrefined method produced a sputter target
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`having a microstructure which showed an interfacial reac-
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`tion layer 40 between the aluminum 20 and the non-
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`aluminum metal 60 particles.
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`The methodof the present invention is an improvement of
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`the early, unrefined process. The method of the present
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`invention, as shown in FIG. 2A, produces a sputter target
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`with no macroscopic segregation of the aluminum particles
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`20 into agglomerates 30 as shown in FIG. 1A. As shown in
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`FIG. 2B, there are only traces of microsegregation of prior
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`aluminum powderparticles 20 of about 10-30 um in diam-
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`eter. Additionally, in the method of the present invention and
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`as shownin FIG. 2C,no interfacial reaction layer 40, as seen
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`in FIG. 1C, is evident between the aluminum 20 and the
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`non-aluminum metal 60 particles.
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`Generally, the sputter target of the present invention is
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`formed from a hot pressed evacuated machined cylinder of
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`a cold pressed blend of an aluminum powder and a non-
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`aluminum reactive metal powder. Fabrication of an alumi-
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`num body to a powder preferably occurs by an inert gas
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`atomization process in which a metal is first melted and
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`allowed to pour through a nozzle to form a freely falling
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`stream. The stream is impacted by a high-pressure, high
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`velocity jet of an inert gas such as nitrogen, argon, or helium
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`to generate a force sufficient
`to break the molten metal
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`stream to a spray. Fabrication to a powder may also occur by
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`other processes known to one skilled in the art such as a
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`mechanical comminution process. The morphology of the
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`powder may be substantially spheroidal, angular (defined as
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`having a substantially needle-like shape), or granular
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`(defined has having a substantially grain-like shape).
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`A non-aluminum second metal body is similarly
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`fabricated, preferably by a hydride-dehydride process. In
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`other embodiments an inert-gas atomization process, or any
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`other process knownto one skilled in the art, may be used
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`to fabricate the metal body to a powder. The morphology of
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`the powder may be substantially spheroidal, angular
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`(defined as having a substantially needle-like shape), or
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`granular (defined as having a substantially grain-like shape).
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`The second non-aluminum metal may be any non-aluminum
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`that
`metal
`is known to react with aluminum,
`typically
`
`
`
`
`
`
`titanium, tantalum, niobium, zirconium,iron or nickel.
`
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`In a preferred embodiment,
`the aluminum and non-
`
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`aluminum metal powders thus formedare less than about 45
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`yum in diameter, although coarser powders up to about 300
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`jum in diameter may be used. The use of powders less than
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`about 45 um in diameter results in only traces of microseg-
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`regation of the powderparticles 20, as shown in FIG. 2B.
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`The powders may have a spheroidal, angular, or granular
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`morphology. A capacitor-grade powder, that is, a powder
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`with a very high specific surface area and a particle size
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`formed by a sodium reduction process,
`is preferably
`avoided.
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`4
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`The fabricated aluminum and non-aluminum metal pow-
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`ders are blended for at least two hours. Blending for this
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`period prevents the macroscopic segregation of aluminum
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`into agglomerates 30 in a sputter target, as shown in FIG.
`
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`1A.In one embodiment, the powders are added to a polypro-
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`pylene jar containing 1" long by 0.5" wide cylinders of pure
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`aluminum to ensure homogeneous blending. The jar size
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`may vary depending upon the particular powder batch size.
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`A lubricating agent may also be added to the powders to
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`facilitate blending and prevent clumping of the aluminum
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`and non-aluminum metals. The lubricating agent may be a
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`solvent such as an alcohol,
`for example, methanol, or
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`acetone. The lubricating agent may also be a binder such as
`stearic acid or stearates.
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`The blended aluminum and non-aluminum powderis then
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`subjected to cold pressing. The blended powder may be
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`loaded into a bag madeofnatural rubber,latex, butyl, nitrile,
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`polyurethane, polyvinyl chloride, neoprene orsilicone, and
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`the bag sealed before pressing. Alternatively, the blended
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`powder may be pressed without bagging by pouring the
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`blended powder into a mold and applying pressure directly
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`to the mold. The blended poweris then subjected to cold
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`isostatic pressing (CIP), defined as pressing without added
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`heat (that is, pressing at room temperature) and applying
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`pressure. Pressing may be either uniaxial, biaxial or hydro-
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`static and is performed at a pressure of about 30 ksi.
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`The pressed powder blend is a blank, which is an inter-
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`mediate form of the blend which is not a powder butis not
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`yet in a final shape. The blank is machined into a right
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`cylinder, that is, a cylinder having a basethat is perpendicu-
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`lar to the side of the cylinder. Machining can occur by any
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`standard method known to one skilled in the art, but is
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`preferably performed by a lathe. The machined cylinder is
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`loaded into a can having dimensionsthat are substantially
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`close to that of the starting cylinder. The can is preferably
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`made of steel, but may be made of another metal, for
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`example zircon. The can composition depends upon the
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`melting temperature and the reactivity of the metal of the can
`with the non-aluminum metal. The can is heated to about
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`400° C., subjected to a vacuum of about 10-° torr, and
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`sealed. The sealed can is subjected to hotisostatic pressing
`
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`(HIP). Hotisostatic pressing in either a uniaxial, biaxial, or
`
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`hydrostatic direction occurs at a temperature below 0.9 T,,,
`
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`of aluminum (the melting temperature in degrees Kelvin of
`
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`
`aluminum) and at a pressure of about 5 ksi.
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`In an alternate embodiment, blanks as small as around 0.5
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`inch in diameter may be formed. The aluminum and non-
`
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`aluminum metal powders are fabricated and blended as
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`previously described. The blended powders are pressed,
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`preferably using either cold pressing or cold isostatic
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`pressing, and then assembled into a mosaic. The mosaic, an
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`assembly of a few, typically four to five, pieces that when
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`aggregated make up a shape,
`is then subjected to hot
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`pressing. Hot pressing, by either hot
`isostatic pressing,
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`vacuum hot pressing,inert gas hot pressing, or pressure-less
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`sintering, occurs at a temperature below 0.9 T,, of alumi-
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`num. The mosaic then forms a one piece unreacted non-
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`aluminum metal/aluminum sputtertarget.
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`The resulting sputter target formed by the method of the
`
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`
`
`present invention contains greater than about 2% to about
`
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`
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`5% by weight of aluminum. As shownin FIGS. 2A and 2B,
`
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`the sputter target is substantially free of aluminum agglom-
`
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`erates 30, as seen in FIG. 1A. As shown in FIG. 2C, the
`
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`resulting sputter target also has no interfacial reaction layer
`
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`40, which is characterized by the presence of a third com-
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`ponent other than an aluminum 20 and non-aluminum metal
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`60. The third component that forms the interfacial reaction
`
`Ex. 1063, Page 6
`
`Ex. 1063, Page 6
`
`

`

`
`5
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`layer 40 may be formed bythe reaction of the aluminum 20
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`with the non-aluminum 60 particles, or may be formed by
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`the reaction of oxygen with either the aluminum 20 or
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`non-aluminum metal 60 particles, or may result from the
`reaction of either the aluminum 20 or non-aluminum metal
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`60 particles with any impurity that may be present, such as
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`an impurity in the solvent or binder. The reactive sputter
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`target is also substantially free of voids, has a substantially
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`uniform body, and has a density of at least 99% as deter-
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`mined by the Archimedes method, known to one skilled in
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`the art, with a purity greater than 99.95% by weight. The
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`amounts of impurities are as follows:
`
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`6
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`claims to such detail. Additional advantages and modifica-
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`tions will readily appear to those skilled in the art. For
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`example, hammer forging may be used instead of pressing.
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`As another example, the blended powder may be poured into
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`a mold, and pressure and temperature may be applied
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`directly to the mold without using a bag or can to contain the
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`powder. The inventionin its broader aspects is therefore not
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`limited to the specific details, representative apparatus and
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`methods, and illustrative examples shown and described.
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`Accordingly, departures may be made from such details
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`without departing from the spirit or scope of applicants’
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`general inventive concept.
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`Having described the invention, what is claimedis:
`
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`1. A method of making a high performance high density
`
`
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`sputter target comprising:
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`blending a powder of substantially pure non-aluminum
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`metal capable of reacting with aluminum and a powder
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`of substantially pure aluminum metal to form a uniform
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`mixture of the powders of the metals, then
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`cold pressing the blended powders, then
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`machining the blended cold pressed powders into a
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`cylinder, and then
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`compacting the machined cylinder to high density by a
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`process consisting essentially of isostatically pressing
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`the cylinder under vacuum at a temperature of at least
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`about 400° C. to obtain a high density target material
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`consisting of a homogeneous mixture containing essen-
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`tially no macroscopic segregation of aluminum, con-
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`taining at most only traces of microsegregation of
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`One hundred and fifty grams of an aluminum powderof
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`aluminum, and containing essentially no intermetallic
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`approximately 45 um and 99.99% purity, and 1000 grams of
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`compoundsof the metals.
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`a tantalum powder of approximately 45 wm and 99.95%
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`2. The method of claim 1, wherein the non-aluminum
`
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`purity, were used to fabricate a sputter target composed of 50
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`metal is selected from the group consisting of tantalum,
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`atomic percent of aluminum and 50 atomic percent of
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`titanium, niobium, zirconium, iron and nickel.
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`tantalum that is 13 percent by weight of aluminum. The
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`3. The method of claim 1, further comprising obtaining
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`mass-median particle size was 20-25 um in diameter. The
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`the powder of substantially pure non-aluminum metal by
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`powders wereloaded into a polypropylene jar under an inert
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`fabricating a non-aluminum metal body.
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`gas such as argon and tumbled for two hours to blend the
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`4. The method of claim 3, wherein fabricating is by a
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`powders. Pure aluminum cylinders, 1" longx0.5" wide, were
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`method selected from the group consisting of a hydride-
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`included in the jar during blending to eliminate the possi-
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`dehydride process and an inert gas atomization process.
`
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`bility of nonhomogeneity during blending. The blended
`
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`5. The method of claim 3, wherein fabricating is to a
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`powderwasloaded into a bag whose size was substantially
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`morphology selected from the group consisting of
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`the same as the cylinder, then the bag was vacuum-sealed.
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`spheroidal, angular, and granular.
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`The bag was subjected to cold isostatic pressing under a
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`6. The method of claim 1, wherein the powder of sub-
`
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`
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`pressure of about 30 ksi to achieve a density greater than
`
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`
`stantially pure non-aluminum metal is between about 6 wm
`
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`80% of theoretical. The cold isostatic pressed blank was
`
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`and about 300 um.
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`machined using a lathe into a right cylinder, loaded into a
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`7. The method of claim 1, wherein the powder of sub-
`
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`steel can, vacuum sealed, and subjected to hot
`isostatic
`
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`
`
`stantially pure non-aluminum metal is between about 6 wm
`
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`
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`pressing at 550° C. underapressure of at least 5 ksi to reach
`
`
`
`and about 45 um.
`
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`
`
`greater than 99% of theoretical density.
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`8. The method of claim 1, further comprising obtaining
`
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`The density of the resulting sputter target, as measured by
`the powder of substantially pure aluminum metal by fabri-
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`
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`the Archimedes method, was 9.80 g/cc at the edge, 9.83 g/cc
`cating an aluminum metal body.
`
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`at the mid-region, and 9.81 g/cc at the center, translating to
`9. The method of claim 8, wherein fabricating is by a
`
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`a percent of theoretical of 99.0% at the edge, 99.2% at the
`method selected from the group consisting of a hydride-
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`
`
`mid-region, and 99.1% at the center. The theoretical density
`dehydride process and an inert-gas atomization process.
`
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`
`
`is calculated to be 9.95 g/cc by the Rule of Mixtures, as
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`
`
`10. The method of claim 1, wherein the powder of
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`
`
`knownto one skilled in the art, for a 50—50 atomic mix of
`
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`
`
`substantially pure aluminum metal has a spheroidal mor-
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`
`
`
`aluminum and tantalum,that is, a mixture of 13 percent by
`phology.
`
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`
`
`
`weight of aluminum and 87 percent by weight of tantalum.
`
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`
`
`11. The method of claim 1, wherein the powder of
`
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`The resulting target was substantially free of aluminum
`substantially pure aluminum metal is less than about 300
`
`
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`
`
`ym.
`agglomerates 30 and had nointerfacial reaction layer 40. No
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`
`
`voids were detected when the target was viewed under
`
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`
`
`12. The method of claim 1, wherein the powder of
`
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`
`
`
`scanning electron microscopy.
`substantially pure aluminum metalis less than about 45 um.
`
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`
`
`While the present invention has been illustrated by a
`13. The method of claim 1, wherein the powders are
`
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`
`
`
`
`
`
`description of embodiments and an example, and while the
`blended with cylinders of pure aluminum forat least 2 hours.
`
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`
`
`illustrative embodiments and example have been described
`14. The method of claim 1, wherein the blending step
`
`
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`
`
`in considerable detail, it is not the intention of the inventors
`includes blending with a substance selected from the group
`
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`
`
`to restrict or in any way limit the scope of the appended
`consisting of a solvent, a binder, and mixtures thereof.
`
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`
`
`The product thus formed is not limited by compositions and
`
`
`
`
`
`
`
`
`does not use any sintering, reactive sintering, or reactive
`
`
`
`hot-pressing as a method of manufacture.
`EXAMPLE
`
`
`
`
`25
`
`
`
`30
`
`35
`
`
`
`40
`
`
`
`45
`
`
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`50
`
`
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`55
`
`
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`60
`
`
`
`65
`
`
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`
`
`6,010,583
`
`10
`
`15
`
`
`
`20
`
`Calcium < 20 ppm
`
`
`Copper <20 ppm
`
`
`
`Iron < 35 ppm
`
`
`Magnesium < 25 ppm
`
`
`Manganese < 50 ppm
`
`
`Nickel < 20 ppm
`
`
`Niobium < 30 ppm
`
`
`Tungsten < 60 ppm
`
`
`Titanium < 50 ppm
`
`
`
`Chromium < 50 ppm
`
`
`Cobalt < 50 ppm
`
`
`Potassium < 200 ppm
`
`
`
`Lithium < 50 ppm
`
`
`Molybdenum < 35 ppm
`
`Sodium < 200 ppm
`
`
`
`Silicon < 50 ppm
`
`
`Strontium < 20 ppm
`
`
`
`
`
`
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`
`
`Ex. 1063, Page 7
`
`Ex. 1063, Page 7
`
`

`

`6,010,583
`
`
`
`10
`
`
`
`15
`
`20
`
`
`7
`
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`
`
`
`
`is
`15. The method of claim 14, wherein the solvent
`
`
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`
`
`
`selected from the group consisting of alcohols or acetone.
`
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`
`
`16. The method of claim 14, wherein the binderis selected
`
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`
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`
`
`from the group consisting of stearic acid or stearates.
`
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`17. The method of claim 1, wherein the cold pressing step
`
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`includescold isostatic pressing at a pressure of about 30 ksi.
`
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`18. The method of claim 1, wherein the cold pressing step
`
`
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`
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`includescold pressing in a direction selected from the group
`
`
`
`
`consisting of uniaxial, biaxial or hydrostatic.
`
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`19. The method of claim 1, wherein the isostatic pressing
`
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`
`
`step includespressing under a vacuum ofat least about 10-*
`torr.
`
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`20. The method of claim 1, wherein the isostatic pressing
`
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`step includes pressing at a temperature less than 0.9 T,, of
`
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`aluminum andat a pressure of at least about 5 ksi.
`
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`21. Amethod of making a high performance, high density
`
`
`
`sputter target, comprising:
`
`
`
`
`
`
`blending a powderof substantially pure aluminum having
`
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`
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`an average particle size less than about 45 wm with a
`
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`
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`powderof substantially pure tantalum having an aver-
`
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`
`
`age particle size of less than about 45 wm for at least
`
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`
`
`
`two hours to form a uniform mixture of the powders of
`
`
`
`the metals, then
`
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`
`
`cold isostatic pressing the blended powdersat a pressure
`
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`
`
`of about 30 ksi to form a blank, then
`
`
`
`
`
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`
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`machining the blank into a right cylinder, and then
`
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`hotisostatic pressing the machined cylinder at a tempera-
`
`
`
`
`
`
`ture of about 550° C. and a pressure of about 5 ksi to
`30
`
`
`
`
`
`
`
`obtain a high density target material consisting of a
`
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`
`
`
`
`homogeneous mixture containing essentially no mac-
`
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`
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`roscopic segregation of aluminum, containing at most
`
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`
`
`only traces of microsegregation of aluminum, and
`
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`
`
`containing essentially no intermetallic compounds of
`the metals.
`
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`
`
`
`
`22. A method of making a high performance, high density
`
`
`
`sputter target, comprising:
`
`
`
`25
`
`35
`
`
`
`
`8
`
`
`
`
`blending a powder of substantially pure non-aluminum
`
`
`
`
`
`
`metal capable of reacting with aluminum and a powder
`
`
`
`
`
`
`of substantially pure aluminum metal to form a uniform
`
`
`
`
`
`
`mixture of the powders of the metals, then
`
`
`
`
`
`
`cold pressing the blended powders by a methodselected
`
`
`
`
`
`
`
`
`from the group consisting of cold pressing and cold
`
`
`isostatic pressing,
`
`
`
`
`
`
`
`assembling a mosaic of the cold pressed powders, and
`
`
`
`
`
`isostatically pressing the mosaic by a method selected
`
`
`
`
`from the group consisting of
`
`
`
`hot isostatic pressing,
`
`
`
`
`vacuum hot pressing, and
`
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`
`
`inert gas hot pressing
`
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`
`
`
`
`at a temperature below 0.9 T,, of aluminum to obtain a high
`
`
`
`
`
`density target material consisting of a homogeneous mixture
`
`
`
`
`
`containing essentially no macroscopic segregation of
`
`
`
`
`
`aluminum, containing at most only traces of microsegrega-
`
`
`
`
`
`tion of aluminum, and containing essentially no intermetal-
`
`
`
`
`lic compoundsof the metals.
`
`
`
`
`
`
`23. A method of making a high performance, high density
`
`
`
`sputter target, comprising:
`
`
`
`
`
`blending a powder of substantially pure non-aluminum
`
`
`
`
`
`
`
`metal capable of reacting with aluminum and a powder
`
`
`
`
`
`
`
`of pure aluminum metal to form a uniform mixture of
`
`
`
`
`the powders of the metals,
`
`
`
`
`
`cold pressing the blended powders,
`
`
`
`
`
`
`
`machining the blended cold pressed powders into a
`
`
`cylinder, and
`
`
`
`
`
`
`
`hot pressing the cylinder un