(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2001/0047838A1
`Segal et al.
`(43) Pub. Date:
`Dec. 6, 2001
`
`US 20010047838A1
`
`(54) METHODS OF FORMING
`ALUMINUM-COMPRISING PHYSICAL
`WAPOR DEPOSITION TARGETS;
`SPUTTERED FILMS; AND TARGET
`CONSTRUCTIONS
`(76) Inventors: Vladimir M. Segal, Veradale, WA
`(US); Jianxing Li, Spokane, WA (US);
`Frank Alford, Veradale, WA (US);
`Stephane Ferrasse, Veradale, WA (US)
`Correspondence Address:
`Shannon Morris
`Honeywell International Inc.
`Box 22.45
`101 Columbia Road
`Morristown, NJ 07962 (US)
`(21) Appl. No.:
`09/783,377
`(22) Filed:
`Feb. 13, 2001
`Related U.S. Application Data
`(63) Non-provisional of provisional application No.
`60/193,354, filed on Mar. 28, 2000.
`
`Publication Classification
`
`(51) Int. Cl. ........................... C22C 21/00; B21C 23/00
`
`(52) U.S. Cl. ............................ 148/437; 72/256; 148/438:
`148/439; 148/440
`
`(57)
`
`ABSTRACT
`
`The invention includes a method of forming an aluminum
`comprising physical vapor deposition target. An aluminum
`comprising mass is deformed by equal channel angular
`extrusion. The mass is at least 99.99% aluminum and further
`comprises less than or equal to about 1,000 ppm of one 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, Hf, Ho, In, Ir,
`La, Lu, Mg,Mn, Mo, N, Nb, Nd, Ni, O, 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, T1, Tm, V, W, Y, Yb., Zn and Zr. After the
`aluminum-comprising mass is deformed, the mass is shaped
`into at least a portion of a Sputtering target. The invention
`also encompasses a physical vapor deposition target con
`Sisting 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 of Ac, Ag, AS,
`B, Ba, Be, Bi, C, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga.,
`Gd, Ge, Hf, Ho, In, Ir, La, Lu, Mg, Mn, Mo, N, Nb, Nd, Ni,
`O, 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. Additionally, the invention encompasses thin
`films.
`
`(1) CAST INGOT
`
`(2) PRELIMINARY
`THERMOMECHANICAL
`PROCESSING
`
`(3) DEFORM MASS
`BY ECAE
`
`(4) SHAPE MASS INTO
`AT LEAST A PORTION OF
`A SPUTTERING TARGET
`
`(5) MOUNT THE
`SHAPED MASS TO
`A BACKING PLATE
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
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`Page 1 of 19
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`APPLIED MATERIALS EXHIBIT 1069
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 1 of 9
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`US 2001/0047838A1
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`US 2001/0047838A1
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 3 of 9
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`US 2001/0047838A1
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`2OO
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`GRAIN SIZE
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`Page 4 of 19
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 4 of 9
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`US 2001/0047838A1
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`(1) CAST INGOT
`
`(2) PRELIMINARY
`THERMOMECHANICAL
`PROCESSING
`
`(3) DEFORM MASS
`BY ECAE
`
`
`
`(4) SHAPE MASS INTO
`AT LEAST A PORTION OF
`A SPUTTERING TARGET
`
`(5) MOUNT THE
`SHAPED MASS TO
`A BACKING PLATE
`A z z7 A
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 5 of 9
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 6 of 9
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`US 2001/0047838A1
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`3OO
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`2OO
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`GRAIN SIZE
`(microns)
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`Page 7 of 19
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`Patent Application Publication
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`Patent Application Publication
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`Dec. 6, 2001 Sheet 9 of 9
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`210
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`US 2001/0047838A1
`
`Dec. 6, 2001
`
`METHODS OF FORMING
`ALUMNUM-COMPRISING PHYSICAL VAPOR
`DEPOSITION TARGETS; SPUTTERED FILMS;
`AND TARGET CONSTRUCTIONS
`
`RELATED APPLICATION DATA
`0001. This application claims priority to U.S. provisional
`application Ser. No. 60/193,354, which was filed Mar. 28,
`2OOO.
`
`TECHNICAL FIELD
`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 (PVD) target for use in
`the manufacture of flat panel displays (FPDs), such as, for
`example, liquid crystal displays (LCDs).
`
`BACKGROUND OF THE INVENTION
`0003 PVD is a technology by which thin metallic and/or
`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) and/or
`direct current (DC) sputtering apparatus. For example, PVD
`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, for example, LCDs.
`The LCD market has experienced rapid growth. This trend
`may accelerate in the next few years due to the diversified
`applications of LCDS in, for example the markets of laptop
`personal computers (PCs), PC 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
`of a 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
`being 860x910x19mm, and are expected to become bigger
`in the future. Such massive dimensions present challenges to
`the development of tooling and processing for fabrication of
`Suitable aluminum-comprising targets.
`0007 Various works demonstrate that three fundamental
`factors of a target can influence Sputtering performance. The
`first factor is the grain size of the material, i.e. the Smallest
`constitutive part of a polycrystalline metal 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
`
`believed that finer and more homogeneous grain sizes
`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 of 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 thermomechanical
`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.
`0008. In order to improve the manufacture of LCD tar
`gets it would be desirable to accomplish one or more of the
`following relative to aluminum-based target materials: (1) to
`achieve predominate and uniform grain sizes within the
`target materials of less than 100 um; (2) to have the target
`materials consist of (or consist essentially of) high purity
`aluminum (i.e. aluminum of at least 99.99% (4N) purity, and
`preferably at least 99.999% (5N) purity, with the percent
`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 (TMP) used tra
`ditionally to fabricate LCD targets can generally only
`achieve grain sizes larger than 200 um for 5N Al 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 TMP 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 purity aluminum is typically provided as a
`cast ingot with coarse dendrite structures (FIG. 1 illustrates
`a typical structure of as-cast 99.9995% aluminum). Forging
`and/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 be obtained for any combination of forging
`and/or rolling operations can be expressed as e=(1-h/
`Ho)* 100%, where Ho 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. Higher 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 2001/0047838A1
`
`Dec. 6, 2001
`
`aluminum having a purity of 99.9995% or greater) but they
`are not Sufficient 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 rolling.
`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). A Solid part
`of curve 10 shows an effect of rolling reduction on a
`99.9995% 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. A difficulty that occurs when the
`doping elements are incorporated is that full Self-recrystal
`lization can generally not be obtained for an entirety of the
`material, and instead partial recrystallization is observed
`along grain boundaries and triple joints. For example, the
`structure of a material comprising 99.9995% aluminum with
`30 ppm Si doping is only partly recrystallized 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 99.9995%
`aluminum with a 30 ppm silicon dopant. The curve 20 of
`FIG. 5 conforms to experimental data of 99.9995% 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-recrystallization is attained after 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-deformed 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 of FIGS. 6 and 7.
`0.015
`For the reasons discussed above, conventional
`metal-treatment procedures are incapable of developing the
`
`fine grain size and Stable microstructures desired in high
`purity aluminum target materials for utilization in flat panel
`display technologies. For instance, a difficulty exists in that
`conventional deformation techniques are not generally
`capable of forming thermally Stable grain sizes of less than
`150 microns for both doped and non-doped conditions of
`high purity metals. Also, particular processing environments
`can create further problems associated with conventional
`metal-treatment 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 sizes and Stable microStructures.
`
`SUMMARY OF THE INVENTION
`0016. In one aspect, the invention includes a method of
`forming an aluminum-comprising physical vapor deposition
`target. An aluminum-comprising mass is deformed by 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 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, Hf, Ho, 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, T1, Tm, V, W,
`Y, Yb., Zn and Zr. After 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.
`0017. In another aspect, the invention encompasses a
`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, it 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.
`0018. In yet another aspect, the invention encompasses a
`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 of Ac, Ag, AS, B, Ba, Be, Bi, C, Ca, Cd,
`Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, 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, T1, Tm, V, W, Y, Yb, Zn and Zr. The physical
`Vapor deposition target has an average grain size of less than
`or equal to 100 microns.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0019 Preferred embodiments of the invention are
`described below with reference to the following accompa
`nying drawings.
`0020 FIG. 1 is an optical micrograph of a cast structure
`of 99.9995% aluminum (magnified 50 times).
`
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`

`US 2001/0047838A1
`
`Dec. 6, 2001
`
`0021 FIG. 2 is an optical micrograph of 99.9995%
`aluminum showing a self-recrystallized structure after 95%
`cold rolling reduction (magnified 50 times).
`0022 FIG. 3 is an optical micrograph of 99.9995%
`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 effect of prior art
`rolling reduction processes on grain size 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
`99.9995% aluminum with 30 ppm Si, with such material
`being partly Self-recrystallized at room temperature.
`0025 FIG. 6 is an optical micrograph of 99.9995%
`aluminum plus 30 ppm Si after 90% cold rolling reduction
`(magnified 50 times).
`0026 FIG. 7 is an optical micrograph of 99.9995%
`aluminum plus 30 ppm Si after 90% cold rolling reduction
`and annealing at 150° C. for 1 hour (magnified 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 of 99.9995% aluminum after 2 passes through an equal
`channel angular extrusion (ECAE) device (magnified 50
`times).
`0029 FIG. 10 is an optical micrograph of 99.9995%
`aluminum after 6 passes through an ECAE device (magni
`fied 50 times).
`0030 FIG. 11 is a graph illustrating the effect of ECAE
`on grain size of 99.9995% 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 99.9995%
`aluminum and 30 ppm Si. The graph illustrates the grain size
`after Self-recrystallization of the material at room tempera
`ture.
`FIG. 13 is an optical micrograph showing the
`0.032
`structure of a material comprising 99.9995% aluminum and
`30 ppm Si after 6 passes through an ECAE device (magni
`fied 100 times).
`0.033
`FIG. 14 is an optical micrograph showing the
`structure of a material comprising 99.9995% 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 15B 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 90 into a same direction after each pass
`through an ECAE device). FIG. 15A shows the material in
`the as-deformed State and FIG. 15B shows material after
`85% rolling reduction in thickness.
`0.035
`FIG. 16 is a diagrammatic top-view of a 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 ECAE
`technique was developed by V. M. Segal, and is described in
`U.S. 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 croSS-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 be 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).
`0040. 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; different
`deformation routes, (i.e., changing of billet orientation at
`each pass of multiple passes can enable creation of various
`textures and microstructures); and low load and pressure.
`0041 ECAE can enable a decrease in the grain size 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 99.9995% 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 homogenizing, 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
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`

`US 2001/0047838A1
`
`Dec. 6, 2001
`
`encountered in working with high purity metals. However,
`the present invention recognizes that a method for control
`ling Structure 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, Self-recrystallization 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.
`0043. In one aspect, the present invention utilizes ECAE
`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 99.9995%. A
`total amount of dopant material within the aluminum is
`typically between 5 ppm and 1,000 ppm, and more prefer
`ably between 10 ppm and 100 ppm. The amount of doping
`should be at least the minimal amount assuring the Stability
`of material microStructures during Sputtering, and less than
`the minimum amount hindering the completion of full
`dynamic recrystallization during equal channel angular
`extrusion.
`004.5 The dopant materials can, for example, comprise
`one or more elements Selected from the group consisting of
`Ge, Group IIA elements, Group IIIA elements, Group VIA
`elements, Group VA elements, Group IIIB elements, Group
`IVB elements, Group VIB elements, Group VIII elements,
`and Rare Earth elements. Alternatively, the dopant materials
`can comprise one or more of Ac, Ag, AS, B, Ba, Be, Bi, C,
`Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho,
`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.
`0046) The elements of the dopant materials can be in
`either elemental or compound 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 effectively 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
`IIA elements; the Group IIIB elements; the Group IVB
`elements; the Group VIB elements; the Group VIII ele
`ments; the Group IIIA elements; the Group VA elements; 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 aluminum-material
`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 Hf.
`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 of one or more of
`Ac, Ag, AS, B, Ba, Be, Bi, C, Ca, Cd, Ce, Co, Cr, Cu, Dy,
`Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, 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 Sc; 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 fine 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 and/or processing with
`conventional target-forming processes 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 different 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
`
`

`

`US 2001/0047838A1
`
`Dec. 6, 2001
`
`Processes of the present invention can be applied to
`0.053
`large flat panel display monolithic targets, or targets com
`prised of two or more Segments.
`0.054
`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 diagram 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; 5,513,512; 5,600,
`989; and 5,590,390. The aluminum-comprising mass can
`consist of aluminum, 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) of one 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, Hf, Ho, In, Ir, La, Lu, Mg, Mn, Mo,
`N, Nb, Nd, Ni, 0, Os, P, Pb, Pd, Pm, Po, Pr, Pt, Pu, R