`
`(cid:44)(cid:49)(cid:55)(cid:40)(cid:47) EXHIBIT 10(cid:25)(cid:28)
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 1 {)I' 9
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`US 2001!!)047838 A1
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`Ffiflflfl HR 27—
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`US 200120047838 A1
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`12.3. 57 37
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`FRJER HR?"
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`.300
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`200
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`GRAIN SIZE
`(microns)
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`1’00
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`0
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`60
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`80 90 95
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`99
`ROLLING REDUCTION (2')
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`300
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`GRAIN SIZE
`(microns)
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`100
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`60
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`80 90 95
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`ROLLING REDUCTION (z)
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`135.5: 57 5
`PRIME—$7 HR?-
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`Patent Application Publication
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`US 2tm1/01l47838 A1
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`£4: E CZ.”
`PRIME HR?"
`
`(r) CAST wear
`
`(2) PRELIMINARY
`THERMOMECHAMCAL
`PROCESSING
`
`
`
`
`(3) DEFORM MASS
`BY ECAE
`
`(4) SHAPE MASS INTO
`AT LEAST A PORTION OF
`A SPUFERING TARGET
`
`(5} MOUNT THE
`SHAPED MASS TO
`A BACKING PLATE
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`£34193
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`Dec. 6, 2001 Sheet 6 of 9
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`US 2001!!)047838 A1
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`200
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`GRAIN SIZE
`(microns)
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`100
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`ECAE (passes)
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`147. H 1.2
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`ECAE (passes)
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`E .1 g .47 E
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`.300
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`200
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`GRAIN SIZE
`(microns)
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`I00
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 9 of 9
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`US 2001!!)047838 A1
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`Z
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`O
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`190
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`US 2001f004?838 A1
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`Dec. 6, 2001
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`METHODS OF‘ FORMING
`ALUMINUM-COMPRISING PHYSICAL VAPOR
`DEPOSITION TARGETS; SPU'ITERED FILMS;
`AND TARGET CONSTRUCTIONS
`
`RELATED APPLICATION DATA
`
`[0001] This application claims priority to US. provisional
`application Ser. No. 6t];l93,354, which was filed Mar. 28,
`200E}.
`
`TECHNICAL Fl ELD
`
`[0002] The invention pertains to methods of forming alu-
`minum-comprising physical vapor deposition targets, and to
`target constructions. In particular applications, the invention
`pertains to methods of utilizing equal channel angular extru-
`sion (ECAE) to deform an aluminum—comprising mass in
`forming a physical vapor deposition (PUD) target for use in
`the manufacture of flat panel displays (FPDs), such as, for
`example, liquid crystal displays {LCDs).
`
`BACKGROUND OF THE INVENTION
`
`I’VD is a technology by which thin metallic anchor
`[0003]
`ceramic layers can be sputter~deposited onto a substrate.
`Sputtered materials come from a target, which serves gen—
`erally as a cathode in a standard radio-frequency (RF) andr'or
`direct current (DC) sputtering apparatus. For example, 1WD
`is widely used in the semiconductor industry to produce
`integrated circuits.
`
`[0004} A relatively new application for sputtering tech—
`nologies is fabrication of FPDs, such as, forexamplc, LCDs.
`The LCD market has experienced rapid growth. This trend
`may accelerate in the next few years due to the diversified
`applications of LCle in, for example the markets of laptop
`personal computers (PCs),
`l’C monitors, mobile devices,
`cellular phones and LCD televisions.
`
`[0005} Aluminum can be a particularly useful metal in
`forming LCDs, and it accordingly can be desired to form
`aluminum-comprising physical vapor deposition targets.
`The targets can contain a small content (less than or equal to
`about 100 parts per million (ppm)) of doping elements. The
`aluminum, with or without small additions of dopants, is
`generally desired to be deposited to form a layer of about
`300 nm which constitutes the reflecting electrode of LCD
`devices. Several factors are important in sputter deposition
`ofa uniform layer of aluminum having desired properties for
`LCD devices. Such factors including: sputtering rate; thin
`film uniformity; and microstructure.
`Improvements are
`desired in the metallurgy of LCD aluminum targets to
`improve the above-discussed factors.
`
`[0006] LCD targets are quite large in size, a typical size
`lacing 860x910x19 mm“, and are expected to become bigger
`in the future. Such massive dimensions present challenges to
`the development oflooling and processing for fabrication of
`suitable alu minum-com prising targets.
`
`[0007] Various works demonstrate that three fundamental
`factors ot‘ a target can influence sputtering performance. The
`first factor is the grain sire of the material, i.e. the smallest
`constitutive part of a polycrystalline meta] possessing a
`continuous crystal lattice. Grain size ranges are usually from
`several millimeters to a few tenths of microns; depending on
`metal nature, composition, and processing history.
`It
`is
`
`liner and more homogeneous grain sizes
`believed that
`improve thin film uniformity, sputtering yield and deposition
`rate, while reducing arcing. The second factor is target
`texture. The continuous crystal
`lattice of each grain is
`oriented in a specific way relative to the plane of target
`surface. The sum ot‘ all
`the particular grain orientations
`defines the overall target orientation. When no particular
`target orientation dominates, the texture is considered to be
`a random structure. Like grain size, crystallographic texture
`can strongly depend on the preliminary thermomechanieal
`treatment, as well as on the nature and composition of a
`given metal. Crystallographic textures can influence thin
`film uniformity and sputtering rate. The third factor is the
`size and distribution of structural components, such as
`second phase precipitates and particles, and casting defects
`(such as, for example, voids or pores). These structural
`components are usually not desired and can be sources for
`arcing as well as contamination of thin films.
`
`In order to improve the manufacture of LCD tar-
`[0008]
`gets it would be desirable to accomplish one or ntore of the
`following relative to aluminum-based target materials: (1)10
`achieve predominate and uniform grain sizes within the
`target materials of less than 100 Jhm; (2) to have the target
`materials consist of (or consist essentially oi) high purity
`aluminum (i.e. aluminum ofat least 99.99% (4N) purity, and
`preferably at
`least 99.99996 (SN) purity, with the percentv
`ages being atomic percentages); (3) to keep oxygen content
`within the target materials low; and (4} to achieve large
`target sizes utilizing the target materials.
`
`[0009] The thermomechanical processes ('I‘Ml’) used tra-
`ditionally to fabricate LCD targets can generally only
`achieve grain sizes larger than 200 gm] for 5N A1 with or
`without dopants. Such TMP processes involve the different
`steps of casting, heat
`treatment.
`forming by rolling or
`forging, annealing and final fabrication of the LCD target.
`Because forging and rolling operations change the shape of
`billets by reducing their thickness, practically attainable
`strains in today’s 'I‘MP processes are restricted. Further.
`rolling and forging operations generally produce non-uni-
`form straining throughout a billet.
`
`[0010] The optimal method for refining the structure of
`high purity aluminum alloys
`(such as,
`for example,
`99.9995% aluminum) would be intensive plastic deforma-
`tion sufficient to initiate and complete self-recrystallization
`at room temperature immediately after cold working.
`
`[0011] High pttrity aluminum is typically provided as a
`cast ingot with coarse dendrite structures (FIG. 1 illustrates
`a typical structure of as-cast 99.99959? aluminum}. Forging
`andt'or rolling operations are utilized to deform the cast
`ingots into target blanks. Flat panel display target blanks are
`optimally to be in the form of large thin plates. The total
`strains which can he obtained for any combination of forging
`andror rolling operations can be expressed as e-(l—ht
`l-ID]*IUU%; where H0 is an ingot length, and h is a target
`blank thickness. Calculations show that possible thickness
`reductions for conventional processes range from about 85%
`to about 92%, depending on target blank size to thickness
`ratio. The thickness reduction defines the strain induced in a
`material. I'Iigher thickness reductions indicate more strain,
`and accordingly can indicate smaller grain sizes. The con-
`ventional reductions of 85% to 92% can provide static
`recrystallization of high purity aluminum (for instance,
`
`Page 11 of 19
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`US 2001f004?838 A1
`
`Dec. 6, 2001
`
`aluminum having a purity 0199999596 or greater) but they
`are not suflicient
`to develop the fine and uniform grain
`structure desired for flat panel display target materials. For
`example, an average grain size after 95% rolling reduction
`is about 150 microns (such is shown in FIG. 2). Such grain
`size is larger than that which would optimally be desired for
`a flat panel display. Further,
`the structures achieved by
`conventional processes are not stable. Specifically, if the
`structures are heated to a temperature of 150° C. or greater
`(which is a typical temperature for sputtering operations),
`the average grain size of the structures can grow to 280
`microns or more (see FIG. 3). Such behavior occurs even
`after intensive forging or to] ling.
`
`[0012] FIG. 4 summarizes results obtained for a prior art
`high purity aluminum material. Specifically, FIG. 4 shows
`a curve 10 comprising a relationship between a percentage
`of rolling reduction and grain size (in microns). Asolid part
`of curve 10 shows an effect of rolling reduction on a
`99.999596 aluminum material which is self-recrystallized at
`room temperature. As can be seen, even a high rolling
`reduction of 95% results in an average grain size of about
`160 microns (point 12), which is a relatively coarse and
`non-uniform structure. Annealing at 150° C.
`for
`1 hour
`significantly increases the grain size to 270 microns (point
`14). An increase of reduction to 99% can reduce the grain
`size to 110 microns (point 16 of FIG. 4),but heating to 150°
`C. for 1 hour increases the average grain size to 170 microns
`[point 18 of FIG. 4).
`
`[0013] Attempts have been made to stabilize: recrystallized
`high purity aluminum structures by adding low amounts of
`different doping elements (such as silicon, titanium and
`scandium) to the materials. Adilficulty that occurs when the
`doping elements are incorporated is that full self-recrystal-
`lization can generally not be obtained for an entirely of the
`material, and instead partial recrystallization is observed
`along grain boundaries and triple joints. For example, the
`structure of a material comprising 99.999596 aluminum with
`30 ppm Si doping is only partly recrystallired after rolling
`with a high reduction of 95% (see FIG. 6) in contrast to the
`fully recrystallized structure formed after similar rolling of
`a pure material (see FIG. 2). Accordingly, additional anneal-
`ing of the rolled material at a temperature of 150° C‘. for
`about 1 hour is typically desired to obtain a fully recrystal-
`lized doped structure. Such results in coarse and non—
`uniform grains (see FIG. 7).
`
`[0014] FIG. 5 illustrates data obtained for 99.999593
`aluminum with a 30 ppm silicon dopant. The curve 20 of
`FIG. 5 conforms to experimental data 019999959: alumi—
`num with 30 ppm silicon after rolling with different reduc—
`tions. A dashed part of the curve 20 corresponds to partial
`self—recrystallization after rolling, while a solid part of the
`curve corresponds to full self-recrystallization. The full
`self-recrystallizat ion is attained afier intensive reductions of
`more than 97%, which are practically not available in
`commercial target fabrication processes. The point 22 shows
`the average grain size achieved for the as-deforrned material
`as being about 250 microns, and the point 24 shows that the
`grain size reduces to about 180 microns after the material is
`annealed at 150° C. for 1 hour. The points 22 and 24 of FIG.
`5 correspond to the structures ot‘ FIGS. 6 and 7.
`
`line grain size and stable microstructures desired in high
`purity aluminum target materials for utilization in flat panel
`display technologies. For instance, a difliculty exists in that
`conventional defonnation techniques are not generally
`capable of forming thermally stable grain sizes of less than
`150 microns for both doped and non—doped conditions ot‘
`high purity metals. Also, particular processing environments
`can create further problems associated with conventional
`meta l-treatmenl processes. Specifically, there is a motivation
`to use cold deformation as much as possible to refine
`structure, which can remove advantages of hot processing of
`cast materials for healing pores and voids. and for eliminat-
`ing other casting defects. Such defects are difficult, if not
`impossible,
`to remove by cold deformation, and some of
`them can even be enlarged during cold deformation. Accord—
`ingly,
`it would be desirable to develop methodologies in
`which casting defects can be removed, and yet which
`achieve desired small grain sires and stable microstructures.
`
`SUMMARY OF THE lNVEN'l'ION
`
`In one aspect, the invention includes a method of
`[0016]
`forming an aluminum-comprising physical vapor deposition
`target. An aluminum—comprising mass is deformed lay equal
`channel angular extrusion, with the mass being at
`least
`99.99% aluminum and further comprising less than or equal
`to about 1,000 ppm of one or more dopant materials com-
`prising elements selected l‘rom the group consisting ofAc,
`Ag, As, 13, Ba, Be, Bi, C, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu,
`Fe, Ga, Gd, Ge, 111, I10, In, Ir, La, Lu, Mg, Mn, Mo, N, Nb,
`Nd, Ni, 0, Os, P, Pb, Pd, Pm, Po, Pr, Pt, Pu, Ra, Rf, Rh, Ru,
`S, Sb, Sc, Se. Si, Sm, Sn, Sr, Ta, ‘11), Te, ’l‘i, ‘l‘l, Tm, V, W,
`Y, Yb, Zn and Zr. Alter the aluminum—comprising mass is
`deformed, the mass is shaped into at least a portion of a
`sputtering target. The sputtering target can ultimately be
`formed to be either a monolithic or mosaic sputtering target.
`
`the invention encompasses a
`In another aspect,
`[0017]
`method of forming an aluminum-comprising physical vapor
`deposition target which is suitable for sputtering aluminum—
`comprising material to form an LCD device. An aluminum~
`comprising mass is deformed by equal channel angular
`extrusion. After the mass is deformed, i1 is shaped into at
`least a portion of a physical vapor deposition target. The
`physical vapor deposition target has an average grain size of
`less than or equal to 45 microns.
`
`In yet another aspect, the invention encompasses a
`[0018]
`physical vapor deposition target consisting essentially of
`aluminum and less than or equal to 1,000 ppm of one or
`more dopant materials comprising elements selected from
`the group consisting ofAc, Ag, As, [5, Ba, Be, Bi, (7, Ca, (Yd,
`Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, lIf, Ho, In, Ir,
`l.a, Lu, Mg, Mn, Mo, N, Nb, Nd, Ni, 0, Os, P, Pb, Pd, l’m,
`Po, I-‘r, Pt, Pu, Ra, Rf, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr,
`'l‘a, ‘l'h, Te, Ti, '11, 'l‘m, V, W, Y, Yb, Zn and 2:. The physical
`vapor deposition target has an average grain size of less than
`or equal to 100 microns.
`
`BRIEF DESCRIPTION OF THE. DRAWINGS
`
`invention are
`the
`Preferred embodiments of
`[0019]
`described below with reference to the following accompa-
`nying drawings.
`
`[0015] For the reasons discussed above, cenventional
`metal-treatment procedures are incapable of developing the
`
`[0020] FIG. I is an optical micrograph of a cast structure
`of 99.9995% aluminum (magnified 50 times).
`
`Page 12 of 19
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`
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`US 2001f004?838 A1
`
`Dec. 6, 2001
`
`LL}
`
`[0021] FIG. 2 is an optical micrograph of 99999596
`aluminum showing a self—recrystaltiaed structure after 95%
`cold rolling reduction (magnilied 50 times).
`
`[0022] FIG. 3 is an optical micrograph of 99.999596
`aluminum illustrating a structure achieved after 95% cold
`rolling reduction and annealing at 150° C.
`for
`1 hour
`{magnified 50 times).
`
`[0023] FIG. 4 is a graph illustrating an elIect of prior art
`rolling reduction processes on grain sine of 99.9995% alu-
`minum which is self-recrystallized at room temperature.
`
`[0024] FIG. 5 is a graph illustrating the effect of prior art
`rolling reduction on grain size of a material comprising
`99.999596 aluminum with 30 ppm Si, with such material
`being partly self-recrystallired at room temperature.
`
`[0025] FIG. 6 is an optical micrograph of 99.999592;
`aluminum plus 30 ppm Si after 90% cold rolling redtlction
`[magnified 50 times).
`
`[0026] FIG. 7 is an optical micrograph of 99.999596
`aluminum plus 30 ppm Si alter 90% cold rolling reduction
`and annealing at 150° C. for 1 hour (magniilied 50 times).
`
`[0027] FIG. 8 shows a flow chart diagram of a method
`encompassed by the present invention.
`
`[0028] FIG. 9 is an optical micrograph showing the struc-
`ture 01.99.999.593 aluminum after 2 passes through an equal
`channel angular extrusion (ECAE) device (magnified 50
`times).
`
`[0029] FIG. 10 is an optical micrograph of 99.999596
`aluminum after 6 passes through an ECAE device (magni-
`lied 50 times).
`
`[0030] FIG. 11 is a graph illustrating the effect of ECAE
`on grain size of 99.999592: aluminum which is self-recrys-
`tallized at room temperature.
`
`[0031] FIG. 12 is a graph illustrating the effect of ECAE
`passes on grain size of a material comprising 99.999596
`aluminum and 30 ppm Si. The graph illustrates the grain size
`after self-recrystallization of the material at room tempera-
`ture.
`
`[0032] FIG. 13 is an optical micrograph showing the
`structure of a material comprising 99.999596 aluminum and
`30 ppm Si after 6 passes through an ECAE device (magni-
`fied 100 times).
`
`[0033] FIG. 14 is an optical micrograph showing the
`structure of a material comprising 99.999593: aluminum and
`30 ppm Si after 6 passes through an ECAE device, 85% cold
`rolling reduction, and annealing at 150° C. for 16 hours
`[magnified 100 times).
`
`[0034] FIGS. 15A and 153 show optical micrographs of
`a material comprising aluminum and 10 ppm Sc after 6
`ECAE passes via route D [i.e., a route corresponding to
`billet rotation of 909 into a same direction after each pass
`through an ECAE device). FIG. 15A shows the material in
`the as-det'ormed state and FIG. 15]] shows material after
`85% rolling reduction in thickness.
`
`[0035] FIG. 16 is a diagrammatic top~view ofa tiled target
`assembly composed of nine billets.
`
`[0036] FIG. 17 is a diagrammatic cross—sectional side—
`view of the target assembly of FIG. 16 shown along the line
`17-17.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`[0037] A deformation technique known as equal channel
`angular extrusion (ECAE) is used with advantage for the
`manufacture of physical vapor deposition targets, and in
`particular aspects of the invention is utilized for the first time
`in the manufacture of FPD and LCD targets. The E'CAE
`technique was developed by V. M. Sega], and is described in
`US. Pat. Nos. 5,400,633; 5,513,512; 5,600,989; and 5,590,
`390. The disclosure of the aforementioned patents is
`expressly incorporated herein by reference.
`
`[0038] The general principle of ECAE is to utilize two
`intersecting channels of approximately identical eross~sec-
`tion and extrude a billet through the channels to induce
`deformations within the billet. The intersecting channels are
`preferably exactly identical in cross-section to the extent that
`“exactly identical" can he measured and fabricated into an
`ECAE apparatus. However, the term "approximately iden-
`tical” is utilized herein to indicate that
`the cross—sections
`may be close to exactly identical, instead of exactly identi-
`cal, due to, for example, limitations in fabrication technol-
`ogy utilized to form the intersecting channels.
`
`[0039] An ECAE apparatus induces plastic deformation in
`a material passed through the apparatus. Plastic deformation
`is realized by simple shear, layer after layer, in a thin zone
`at a crossing plane of the intersecting channels of the
`apparatus. A useful feature of ECAE is that the billet shape
`and dimensions remain substantially unchanged during pro-
`cessing (with term “substantially unchanged” indicating that
`the dimensions remain unchanged to the extent
`that
`the
`intersecting channels have exactly identical cross—sections,
`and further indicating that the channels may not have exactly
`identical cross-sections).
`
`[0940] The ECAE technique can have numerous advan—
`tages. Such advantages can include: strictly uniform and
`homogeneous straining; high deformation per pass; high
`accumulated strains achieved with multiple passes; {liflcrent
`deformation routes. (i.e., changing of billet orientation at
`each pass of mu ltipie passes can enable creation of various
`textures and microstructures); and low load and pressure.
`
`[0041] ECAE can enable a decrease in the grain site: of
`high purity aluminum and aluminum alloys used for the
`manufacture of LCDs by at least a factor of three compared
`to conventional practices.
`
`[0042] Various aspects of the present invention are sig-
`nificantly different
`from previous ECAE applications.
`Among the differences is that the present invention encom-
`passes utilization of ECAE to deform high purity materials
`(such as, for example, aluminum having a purity of greater
`than 99.999595 as desired for FPD targets), in contrast to the
`metals and alloys that have previously been treated by
`ECAE. High purity metals are typically not heat treatable.
`and ordinary processing steps like homogeniaing, solution-
`izing and aging can be difficult, if not impossible, to satis—
`factorily apply with high purity metals. Further, the addition
`of low concentrations of dopants (i.e., the addition of less
`than 100 ppm of dopants) doesn’t eliminate the difficulties
`
`Page 13 of 19
`Page 13 of 19
`
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`
`US 2001f004?838 A1
`
`Dec. 6, 2001
`
`encountered in working with high purity metals. However,
`the present invention recognizes that a method for control—
`ling strttcture of single-phase high purity materials is a
`thermo—mechanical treatment by deformation, annealing and
`recrystallization. Also, as high purity metals are generally
`not stable and cannot be refined by dynamic recrystallization
`in the same manner as alloys, the present invention recog-
`nizes that static recrystallization can be a more appropriate
`methodology for annealing of high purity metals than
`dynamic recrystallization. When utilizing static recrystalli-
`zation annealing of materials, it is preferred that the static
`recrystallization be conducted at
`the lowest
`temperature
`which will provide a fine grain size. If strain is increased to
`a high level within a material, such can reduce a static
`recrystallization temperature, with high strains leading to
`materials which can be statically recrystallized at room
`temperature. Thus, selllrecrystallizalion of the materials can
`occur immediately after a cold working process. Such can be
`an optimal mechanism for inducing desired grain sizes,
`textures, and other microstructures within high purity metal
`physical vapor deposition target structures.
`
`In one aspect, the present invention utilises ECAE
`[0043]
`to form a physical vapor deposition target for LCD appli-
`cations. The target comprises a body of aluminum with a
`purity greater than or equal to 99.99% [4N). The aluminum
`can be doped with less than or equal to about 1000 ppm of
`dopant materials. The dopant materiaLs are not considered
`impurities relative to the doped aluminum, and accordingly
`the dopant concentrations are not considered in determining
`the purity of the aluminum. In other words,
`the percent
`purity of the aluminum does not factor in any dopant
`concentrations.
`
`[0044] An exemplary target can comprise a body of alu-
`minum having a purity greater than or equal to 99.999590. A
`total amount of dopant material within the aluminum is
`typically between 5 ppm and 1,000 ppm, and more prefer-
`ably hetween 10 ppm and 100 ppm. The amount of doping
`should be at least the minimal amount assuring the stability
`of material microstruct'ures during sputtering, and less than
`the minimum amount hindering the completion of full
`dynamic recrystallization during equal channel angular
`extrusion.
`
`[0045] The dopant materials can, for example, comprise
`one or more elements selected from the group consisting of
`Ge, Group IIA elements, Group llIA elements, Group VIA
`elements, (.lroup VA elements, Group "18 elements, Group
`IVH elements, Group VII-l elements, Group VIII elements,
`and Rare Earth elements. Alternatively, the dopant materials
`can comprise one or more of Ac, Ag, As, 8, Ba, Be, Bi. (2,
`Ca, Cd, Ce, Co, Cr, Cu, Dy, llr, Eu, Fe, Ga, Gd, Ge, Hf, 110,
`In, Ir, La, Lu, Mg, Mn, Mo, N, Nb, Nd, Ni, 0, 0s, 1’, Pt), Pd,
`Pm, Po, Pr, Pt, Pu, Ra, Rf, Rh, Ru, S, Sb, Sc, Se, Si, Srn, Sn,
`Sr, Ta, Tb, Te, TI, TI, 'I‘m, V, W, Y, Yb, Zn and Zr.
`
`[0046] The elements of the dopant materials can be in
`eitherelemental orcompound form within the materials. The
`dopant materials can be considered to comprise two different
`groups of materials. The first group comprises dopant mate—
`rials having elfectivcly no room temperature solid solubility
`relative to an aluminum matrix, and having no intermediate
`compounds. Such first type of dopant materials are Be, Ge
`and Si. The second type of dopant materials have effectively
`no room temperature solid solubility in aluminum, and are
`
`not toxic, refractory or precious metals, and further possess
`relatively high melting temperatures. The second type of
`materials include various elements selected from the Group
`”A elements;
`the Group lIIB elements;
`the Group IVE
`elements;
`the Group VIB elements;
`the Group VIII ele-
`ments; the Group IttAeIements; the Group VAelements; the
`Group VIA elements, and the Rare Earth elements {i.e., the
`lanthanides).
`
`[0047] The dopant materials can be in the form of pre—
`cipitates or solid solutions within the aluminumvmalerial
`matrix. Preferably. the target is composed of aluminum with
`purity greater than or equal to 99.99% (4N), and with one or
`more dopant materials comprising elements selected from
`the group consisting of Si, Sc, Ti, and 1H.
`
`[0048] The present invention can provide a physical vapor
`deposition target for LCD applications comprising a body of
`aluminum with purity greater than or equal to 99.99% (4N),
`alone or doped with less than 1000 ppm of dissimilar
`elements selected from a group consisting ofone or more of
`Ac, Ag, As, B, Ba, Be, Bi, (1, Ca, (.‘d, Ce, Co, Cr. Cu, Dy,
`Er, Eu, Fe, Ga, Gd, Ge, I'If, IIo, In, Ir, La, Lu, Mg, Mn, Mo,
`N, Nb, Nd, Ni, 0, Os, P, Pb, Pd, Pm, Po, Pr, Pt, Pu, Ra, Rf,
`Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, TI, Tm,
`V, W, Y, Yb, Zn and Zr. Further the target can consist of
`aluminum and one or more of the listed dissimilar elements,
`or can consist essentially of aluminum and the one or more
`of the listed dissimilar elements.
`
`[0049] The LCD target can be made of a body of Al with
`purity greater than 99.99% (4N), alone or doped with less
`100 ppm of one or more dissimilar elements listed above,
`and the total doping content of any element listed above can
`be higher than the solubility limit of this element at the
`temperature at which ECAE is performed.
`
`[0050] Particularly preferred materials for LCD targets
`consist of Al and less than 100 ppm of Si; Al and less than
`100 ppm of Se; Al and less than 100 ppm of Ti; or Al and
`less than 100 ppm of Hf.
`
`[0051] A preferred LCD target possesses: a substantially
`homogeneous
`composition
`throughout;
`a
`substantial
`absence of pores, voids, inclusions and any other casting
`defects; a predominate and controlled grain size of less than
`about 50 micrometers; and a substantially uniform structure
`and controlled texture throughout. Very line and uniform
`precipitates with average grain diameters of less than 0.5
`micrometers can also be present in a preferred target micro—
`structure.
`
`[0052] LCD physical vapor deposition targets of the
`present invention can be formed from a cast ingot compris-
`ing, consisting of, or consisting essentially of aluminum.
`The aluminum material can be extruded through a die
`possessing two contiguous channels of equal cross section
`intersecting each other at a certain angle. the ingot material
`can also be subjected to annealing andr’or processing with
`conventional target—l’onning pmcesses such as rolling, cross-
`rolling or forging, and ultimately fabricated into a physical
`vapor deposition target shape. The extrusion step can be
`repeated several
`times via dilfcrent deformation routes
`before final annealing, conventional processing and fabri—
`cation steps to produce very fine and uniform grain sizes
`within a processed material, as well as to control texture
`strength and orientation within the material.
`
`Page 14 of 19
`Page 14 of 19
`
`
`
`US 2001f004?838 A1
`
`Dec. 6, 2001
`
`Prt‘tcesses of the present invention can be applied to
`[0053]
`large flat panel display monolithic targets, or targets com—
`prised of two or more segments.
`
`[0054] Particular embodiments of the present invention
`pertain to formation of aluminum-comprising physical
`vapor deposition targets, such as, for example, formation of
`aluminum—comprising physical vapor deposition targets
`suitable for liquid crystal display (LCD) applications. FIG.
`8 shows a flow—chart diagra m of an exemplary process of the
`present invention. In a first step, an aluminum-comprising
`cast
`ingot
`is formed, and in a second step the ingot
`is
`subjected to thermo-mechanical processing. The material
`resulting from the thermo-mechanical processing is an alu-
`minum-comprising mass. The mass
`is
`subsequently
`deformed by equal channel angular extrusion (ECAE). Such
`deformation can be accomplished by one or more passes
`through an ECAE apparatus. Exemplary ECAE apparatuses
`are described in U.S. Pat. Nos. 5,400,633; 5,513,513; 5,600,
`989; and 5,590,390. The aluminummeomprising mass can
`consist of alu minum, or can consist essentially of aluminum.
`The mass preferably comprises at least 99.99% aluminum.
`The mass can further comprise less than or equal to about
`100 parts per million (ppm) oione or more dopant materials
`comprising elements selected from the group consisting of
`Ac, Ag, As, B, Ba, Be, Bi, C, Ca, Cd, Ce, Co, Cr, Cu, Dy,
`Er, Eu, Fe, Ga, Gd, Ge, IIf, 110, In, Ir, La, Lu, Mg, Mn, Mo,
`N, Nb, Nd, Ni, 0, Os, P, Pb, Pd, Pm, Po, Pr, Pl, Pu, Ra, Rf,
`Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm,
`V, W, Y, Yb, Zn and Zr. The aluminum-comprising mass can
`consist of aluminum with less than or equal to about 100
`ppm of one or more of the dopant materials described above,
`or consist essentially of aluminum with less than or equal to
`about 100 ppm of one or more of the dopant materials
`described above.
`
`[0055} ECAE is utilived in methodology of the present
`invention for addressing problems found during formation
`of PVD targets of high—purity materials. ECAE is a process
`which utilizes a simple shear deformation mode, which is
`different from a dominant deformation mode achieved by
`uniaxial compression of forging or rolling. In high purity
`metals, the intensive simple shear of ECAIE can manifest
`itself by developing very thin and long shear bands. The
`strains achieved inside these bands can be many times larger
`than the strains achieved outside the bands. The shear bands
`occur along a crossing plane of the channels utilized during
`ECAE. If a processing speed is sulficiently low to eliminate
`adiabatic heating and flow localization at the macro—scale,
`shear bands in pure metals can have a thickness of only a few
`microns with a near regular spacing between each other of
`a few tenths ofa micron. The bands can be observed after a
`single ECAE pass. HoWever, if the number of ECAE passes
`increases the spacing between shear bands can reduce to a
`stable size. The actual size can vary depending on the
`material being subjected to ECAE, and the purity of such
`material. Astrain inside of the shear bands can be equivalent
`to very high reductions (specifically, reductions of about
`99.99% or more), and static recrystallization is immediately
`developed in the bands. The static recrystallization can lead
`to new line grains growing in spacing between the bands.
`
`[0056] FIGS. 9 and 10 show fully recrystallized struc—
`turcs of 99.9995% aluminum after ECAE with 2 passes and
`6 passes,
`respectively. The grains within the material
`attained a stable size after 6 passes. Experiments have shown
`
`that processing with a route corresponding to billet rotation
`of 90° into a same direction after each pass can provide the
`most uniform and equiaxial recrystallized structures for high
`purity materials. Such route is defined as route “1)” in
`accordance with the standard definitions that have been
`utilized to described ECAE processing in previous publica—
`tions.
`
`II shows a curve 30 demonstrating the
`[0057] FIG.
`change manifested in grain size ol’ :1 hig