U.S. patent application number 13/482482 was filed with the patent office on 2012-09-13 for method for consolidating and diffusion-bonding powder metallurgy sputtering target.
Invention is credited to Darryl Draper, Chi-Fung Lo.
Application Number | 20120228131 13/482482 |
Document ID | / |
Family ID | 39432856 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120228131 |
Kind Code |
A1 |
Lo; Chi-Fung ; et
al. |
September 13, 2012 |
METHOD FOR CONSOLIDATING AND DIFFUSION-BONDING POWDER METALLURGY
SPUTTERING TARGET
Abstract
Methods for manufacturing sputtering target assemblies and
assemblies thereof are provided, particularly targets made of
powders. Powders are adhered to a backing plate by use of a vacuum
hot press, the powder preferably contacted by non-planar surfaces,
and is compressed with at least about 95% density and substantially
simultaneously diffusion-bonded to the backing plate.
Inventors: |
Lo; Chi-Fung; (Fort Lee,
NJ) ; Draper; Darryl; (Congers, NY) |
Family ID: |
39432856 |
Appl. No.: |
13/482482 |
Filed: |
May 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11644816 |
Dec 22, 2006 |
8206646 |
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13482482 |
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Current U.S.
Class: |
204/298.13 ;
100/35; 204/298.12 |
Current CPC
Class: |
C23C 14/3414 20130101;
B22F 7/08 20130101; H01J 37/3426 20130101; H01J 37/34 20130101;
B22F 3/14 20130101 |
Class at
Publication: |
204/298.13 ;
204/298.12; 100/35 |
International
Class: |
C23C 14/34 20060101
C23C014/34; B30B 13/00 20060101 B30B013/00; C23C 14/14 20060101
C23C014/14 |
Claims
1. An assembly for making a sputter target comprising the steps of:
a compression means having an upper portion surface and a lower
portion surface; a backing plate having a first and second backing
plate surface, said second surface in contact with the lower
portion surface of the compression means; a powder layer having a
first and second surface, said second powder layer surface in
contact with the first surface of the backing plate, and said first
powder layer surface in contact with the upper portion surface of
the compression means, and said powder layer compressed to a
density; and wherein at least one powder layer surface is
non-planar.
2. The assembly of claim 1, wherein the first surface of the powder
layer is substantially concave.
3. The assembly of claim 1, wherein the powder comprises a material
selected from a group consisting of copper-containing material and
titanium-containing material.
4. The assembly of claim 1, wherein the powder comprises a material
selected from the group consisting of: copper, copper alloys,
titanium and titanium alloys.
5. The assembly of claim 4, wherein the copper alloy is selected
from the group consisting of: copper-chromium; copper-titanium;
copper-nickel, and combinations thereof
6. The assembly of claim 4, wherein the titanium alloy is selected
from the group consisting of: titanium-tungsten; titanium-copper;
titanium-iron; titanium-nickel; titanium-aluminum; and combinations
thereof.
7. The assembly of claim 1, wherein the backing plate is made from
a material selected from the group consisting of: copper, copper
alloys, stainless steel, titanium, molybdenum, tungsten, and
combinations thereof
8. The assembly of claim 1, wherein the preferred powder size is
from about 40 .mu.m to about 150 .mu.m.
9. The assembly of claim 1, wherein at least one of the surfaces
selected from the group consisting of: the surface of the upper
portion of the compression means; the first surface of the backing
plate; the second surface of the backing plate; the surface of the
lower portion of the compression means, are non-planar.
10. The assembly of claim 1, wherein the first and second surfaces
of the backing plate are non-planar.
11. The assembly of claim 1, wherein the surface of the upper
portion surface of the compression means is non-planar.
12. The assembly of claim 1, wherein the at least one surface of
the backing plate is roughened with a means having a grit measure
of from about 100 .mu.in to about 300 .mu.in Ra.
13. The assembly of claim 1, wherein the compression means is a
vacuum hot press.
14. A sputter target made according to a process comprising the
steps of: providing a powder layer having a first and second
surface; providing a backing plate having a first and second
surface; providing a compression means having an upper portion
surface and a lower portion surface; positioning the first surface
of the backing plate against the lower portion surface of the
compression means; positioning the first surface of the powder
layer against the second surface of the backing plate; positioning
the upper portion surface of the compression means against the
second surface of the powder layer to a non-planar orientation,
wherein the surface of the upper portion of the compression means
is convex; compressing the powder and backing plate to press the
powder to a density of at least about 95%; diffusion-bonding the
powder to the backing plate to achieve a target assembly; and
controlling the target assembly to be warped toward a direction
opposite to the second surface of the backing plate during cooling,
whereby the target assembly attains a planar orientation.
15. A sputter target made according to a process comprising the
steps of: providing a powder layer having a first and second
surface; providing a backing plate having a first and second
surface; providing a compression means having an upper portion
surface and a lower portion surface; positioning the first surface
of the backing plate against the lower portion surface of the
compression means; positioning the first surface of the powder
layer against the second surface of the backing plate; positioning
the upper portion surface of the compression means against the
second surface of the powder layer to a non-planar orientation;
compressing the arrangement to press the powder to a density of at
least about 95%; diffusion-bonding the powder to the backing plate
to achieve a target assembly; and wherein the surface of the upper
portion of the compression means is convex and the second surface
of the backing plate is concave; and controlling the target
assembly to be warped toward a direction opposite to the second
surface of the backing plate during cooling, whereby the target
assembly attains a planar orientation.
Description
RELATED APPLICATIONS
[0001] This application is a division of, and claims priority from,
U.S. patent application Ser. No. 11/644,816, filed Dec. 22, 2006,
the content of which is hereby incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention is generally directed to methods of
manufacturing sputtering target assemblies. More specifically, the
present invention is directed to the manufacture of sputter target
assemblies having non-planar surfaces using powdered layers to
facilitate bonding to a back plate.
BACKGROUND OF THE INVENTION
[0003] Sputtering is a known means for depositing thin films onto a
substrate, such as those especially useful in the manufacture of
semi-conductor devices, including integrated circuits. In such
known sputtering systems, the material that is deposited onto a
substrate is removed from a sputter target by bombarding the target
with ions. However, the process imparts thermal energy to the
target. In order to prevent the target from overheating, the target
is often mounted to a backing plate to dissipate heat. Thus, it is
important that a good thermal bond is present between the target
and the backing plate.
[0004] Since the target and backing plate are often formed from
different materials, they often have different rates of thermal
expansion, resulting in the target potentially bowing or otherwise
becoming dimensionally unstable upon cooling. As a result, such
assemblies must undergo a time-consuming flattening and reshaping
procedure to orient the target assembly into its desired, planar
orientation. Unfortunately, such flattening procedures often
introduce torsional, or other stresses on the assembly areas,
including the bonding layer between the target and the backing
plate, often leading to assembly failure.
[0005] Known methods for diffusion-bonding in the manufacture of
sputter target assemblies use hot iso-static press (HIP) methods to
bond solid target blanks to backing plates with or without bond
media. The bond media can be metal foils or interlayer coated on
the target or backing plate bond surface by plating, sputtering or
other coating techniques.
[0006] U.S. Pat. No. 5,397,050 provides a method to use HIP
processing to consolidate a W--Ti powder to form a target while
bonding the powder composition to the titanium backing plate to
form an inter-diffusion type bond between the target and the
backing plate. In this art, the powder and the backing plate are
placed in a metal can. By applying HIP, the powder is compacted and
inter-diffused to the backing plate. After HIP, the assembly is
flattened in a separate flattening step by a platen press prior to
machining
[0007] U.S. Pat. No. 5,836,506 describes the bonding of a target to
a backing plate by controlling the roughness of bond surface
between 120 Ra to 150 Ra, and drilling a plurality of holes in one
of the bond surfaces. A pressure of 30 MPa (4.35 ksi) to 140 MPa
(20 ksi) and 450.degree. C. to 550.degree. C. is applied for
targets bonded to Al or Al alloy backing plates, 742.degree. C. to
947.degree. C. for targets bond to Cu or Cu alloy backing plates,
982.degree. C. to 1232.degree. C. for targets bond to steel backing
plates or 1182.degree. C. to 1472.degree. C. for targets bond to Ti
or Ti alloy backing plates.
[0008] U.S. Pat. No. 5,230,459 describes a method for forming a
target to a backing plate with a plurality of grooves in one of the
bond side by machining, normally the grooves are on the target
side. The assembly is heated and pressed under vacuum, inert or
reduction environment. When bonding a Ti target to an Al backing
plate, bonding is taught as occurring at 550.degree. C. to
625.degree. C. and under 2 ksi to 15 ksi by HIP. For bonding target
to Cu backing plate, the bond temperature is taught as being less
than the melting point of Cu or Cu alloys.
[0009] U.S. Pat. No. 6,749,103 provides a method for bonding a
target to a backing plate followed by an annealing at a temperature
of from 200.degree. C. to 482.degree. C. A plurality of salient
portions, M-shaped ridges or projections are machined into a bond
surface, depending on whether the target or backing plate is the
harder surface. The projection from the harder metal penetrates
into the softer metal by cold pressing at pressures of about 50
tons to 5000 tons. After the low temperature pressure
consolidation, the assembly is subjected to 200.degree. C. to
482.degree. C. to ensure adequate adhesion of the pressure
consolidated surfaces.
[0010] U.S. Pat. No. 5,693,203 describes a bonding method for a
target to a backing plate using at least one insert as the bond
medium. The insert is made of a soft material such as Al and Al
alloys, Cu and Cu alloys, Ag and Ag alloys, or Ni and Ni alloys.
The insert thickness is 10 .mu.m or thicker, and can be foil or a
sheet and coating film provided by plating, vapor deposition, or
sputtering. The target, backing plate and insert are degreased and
rinsed with an organic solvent like acetone. The bonding is
performed at temperatures of 150.degree. C. to 350.degree. C. and
pressure at 1.0-15 kg/mm.sup.2 (1.42-21.3 ksi), preferably of
150.degree. C.-250.degree. C. and 3-10 kg/mm.sup.2 (4.26-14.2 ksi).
The insert is applied when using Al and Al alloys, Cu and Cu
alloys, and stainless steels as the backing plates. The targets are
bonded at a temperature of 150.degree. C.-550.degree. C. with 1
kg/mm.sup.2 minimum. The examples presented disclose that pressure
of 7.5 kg/mm.sup.2-8 kg/mm.sup.2 (10.65-11.36 ksi) is applied for W
target and Ti target bonded with Ti backing plate at 500.degree.
C.
[0011] U.S. Pat. No. 6,071,389 describes a method of diffusion
bonding a cobalt target to an aluminum or copper backing plate by
means of a titanium interlayer. The Ti interlayer is provided as a
foil, but may be also be formed on a mating surface of either the
target or the backing plate by electroplating, sputtering,
electro-less plating, or plasma spraying. The target may be
machined with grooves defining salient points prior to providing
the interlayer. The bonding is performed at 600.degree. C. with 100
MPa (14.5 ksi) pressure for three hours. The assembly may be made
via vacuum-hot-press, but preferably by hot-isostatic-pressing.
SUMMARY OF THE INVENTION
[0012] This invention provides methods for manufacturing a
sputtering target assembly, particularly targets comprising
powders. Pressing a powder layer to a backing plate by vacuum hot
press, the powder layer is consolidated with at least about 95%
density and substantially simultaneously diffusion-bonded to the
backing plate. Embodiments of the present invention preferably
applied to the consolidation temperature of the target material are
about equal to or lower than the melting point of the backing
plate, such as Cu or Cu alloy target material bonded to Cu, Cu
alloy, Ti, stainless steel or Mo backing plate, Ti or Ti alloy
target material bonded to Ti or Mo backing plate.
[0013] According to additional embodiments, the present invention
relates to methods for manufacturing a sputtering target assembly
and target assemblies thereof, the assemblies comprising a powder
layer provided to a backing plate and pressing the powder layer to
the backing plate using a compression means, such as, for example,
a vacuum hot press, sufficient to press the powder layer to a
density of at least about 95%; while substantially simultaneously
diffusion-bonding the powder to the backing plate to achieve a
target assembly, and wherein, prior to compression, at least one of
the backing plate surfaces and/or the compression means surfaces is
non-planar, rendering at least one surface of the powder layer,
preferably non-planar prior to compression.
[0014] The targets made by the methods of the present invention
have at least three times higher bond strength than the
conventional solder-bonded products. In addition, the maximum
working temperature of the solders used for bonding targets to
backings is less than 200.degree. C. The new invention bonds target
material directly to backing plate, that allows the working
temperature as high as half of the melting point of the target or
backing plate. Therefore, much higher sputtering power can be
applied, resulting in a higher throughput of film deposition.
[0015] In addition, the convex-concave design of the assemblies of
the present invention eliminates the flattening process that is
conventionally required. This simplifies the manufacturing process
and avoids the possibility of cracking the brittle powder
targets.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Other objects, features, embodiments and advantages will
occur to those skilled in the art from the following description of
preferred embodiments and the accompanying drawings, in which:
[0017] FIG. 1 is a schematic representation of one embodiment of
the present invention;
[0018] FIG. 2 is a schematic representation of a further embodiment
of the present invention;
[0019] FIG. 3 is a schematic representation of an embodiment of the
present invention;
[0020] FIG. 4 is a cross-sectional micro-photograph showing a
sputtering target assembly of the present invention; and
[0021] FIG. 5 is a cross-sectional micro-photograph showing a
sputtering target assembly of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 shows a target manufacturing process and assembly 10
with the powder layer 12 positioned on a planar metal backing plate
14 surrounded by a graphite mold 16 and two flat graphite punches
18, 19 on bottom and top, respectively. By applying a uni-axial
compressive stress under an elevated temperature and vacuum or
inert gas environment, the powder layer is consolidated and bonded
to the metal backing plate. This design may generate warp after the
assembly cools down to room temperature due to difference in
thermal expansion between target and backing plate.
[0023] FIG. 2 shows an embodiment of a target manufacturing process
and assembly 20 of the present invention, with the powder layer
positioned on a metal backing plate 22 with pre-dished, or concave
surface on the side contacting the powder 24. The assembly is
surrounded by a graphite mold 16 and two graphite punches 26, 28 on
top and at bottom, respectively, with a convex surface 29 on the
top punch contacting the powder 24. By applying a uni-axial
compressive stress under an elevated temperature and vacuum or
inert environment, the powder is consolidated and bonded to the
metal backing plate. The creation of a concavity on the backing
plate and a convex surface on a punch surface serves to
significantly minimize the warp of target. The compressive stress
is applied to the target assembly by any suitable compressive
means, but is preferably a vacuum-hot-press.
[0024] FIG. 3 shows an embodiment of a target manufacturing process
and assembly 30 of the present invention, with the powder layer 32
positioned on a metal backing plate 34 having a concave surface 36
on the side contacting the powder layer 32 and convex surface 38 on
the side contacting the bottom punch 40. The assembly is surrounded
by a graphite mold 42 and two graphite punches 44, 40 on top and
bottom, respectively, with a convex surface 46 on the top punch
contacting the powder layer 32, and concave surface on the bottom
punch 40 contacting the backing plate 34. By applying a uni-axial
compressive stress under an elevated temperature and vacuum or
inert environment, the powder is consolidated or compressed and
bonded to the metal backing plate. This design serves to minimize
the warp of the bonded target assembly.
[0025] The required radius of the backing plate and/or the top
punch, and the concavity (or "convexness") is determined by the
coefficient of thermal expansion, mechanical strength, dimension of
the target and backing plate, in addition to the bonding
temperature. The optimum radius, however, is determined by trial
and error, such that an acceptable radius can be obtained.
[0026] In one embodiment, the present invention provides an
improved method for manufacturing a sputtering target assembly,
particularly targets made of powders. By pressing a powder to a
backing plate by vacuum hot press, the powder layer is consolidated
with at least about 95% density, while effecting substantially
simultaneous diffusion-bonding to the backing plate. Embodiments of
the present invention are preferably applied to the consolidation
temperature of the target material are about equal to or lower than
the melting point of the backing plate, such as, for example, Cu or
Cu alloy target material bonded to Cu, Cu alloy, Ti, stainless
steel or Mo backing plate, Ti or Ti alloy target material bonded to
Ti or Mo backing plate, etc. In addition, depending on the
thickness ratio between target and backing plate, and the
difference in thermal expansion between the target and backing
plate, desired shapes (e.g. concave-convex) may be prepared on the
backing plate and/or on the punches. The purpose and desirability
of a concave-convex design is to minimize the possible warp of the
target assembly, especially of the target, after cooling. As
discussed herein, the warp is thought to be caused by the
difference in thermal expansion between the target and backing
plate during cooling of bonding process. According to embodiments
of the present invention, by proper design of the concave-convex
orientation, during cooling, the assembly is controlled to be
warped toward the direction substantially opposite to the concave
orientation. Thus, the original concave-convex shape at high
temperature becomes substantially planar after cooling to room
temperature. As a result, substantial improvement in uniformity of
the target thickness is obtained, without an additional, flattening
process prior to machining, as is required according to known
processes. The backing plate thickness may be thicker that that of
the target. As a result, bond assemblies tend to warp toward the
backing plate. Therefore, if the concave-convex design is applied
to the pressing, it is more likely that the concave surface is on
the backing plate and the convex is on the punch facing the powder
bed. Elimination of the flattening step, or process, is especially
important for the poor ductility target materials, such as, for
example, W--Ti alloys, etc.
[0027] Embodiments of the present invention provide a layer made
from consolidated, or compressed powder to form a target blank with
a density of at least about 95% of the theoretical density, while
substantially simultaneously, diffusion bonding the powder to the
backing plate. In contrast to known processes, according to
embodiments of the present invention, a two-in-one process is
provided and performed, preferably by vacuum-hot-pressing. Compared
to the known methods using HIP, embodiments of the present
invention not only reduce the manufacturing processing time but
also greatly reduce the manufacturing cost. In addition, a
concave-convex design, existing on the backing plate and the
graphite punch, reduces warp of the bond assembly, and especially
of the finished target blank, after cooling. These preferred
designs serve to eliminate the otherwise required, conventional
flattening processes of the bond assembly. Additionally, minimizing
warp of the target assembly provides a significantly improved
uniformity of the target thickness, without flattening, prior to
machining, leading to greater finished product uniformity.
[0028] Further, embodiments of the present invention have
significant advantages over known methods. For example, it has now
been determined that use of a vacuum-hot-press (VHP) provides lower
cost and shorter lead-time as opposed to hot-iso-static-press (HIP)
processes. Using the VHP methods of the present invention, the
powder and backing plate are pressed in a vacuum chamber under
uni-axial pressure. By comparison, using HIP processes, the powder
and backing plate need to be capsulized in a metal can followed by
evacuation and sealing prior to being pressed in a vessel under
high pressure Ar gas.
[0029] Therefore, according to embodiments of the present
invention, the concave-convex designs on the punch and backing
plate surfaces facing the powder bed minimize warp of the bond
assembly, as a result of eliminating the flattening process, and
serves to avoid the possibility of finished assembly failure due to
cracking or other damage, for example, of the poor ductility W--Ti
and other targets during flattening. The improved manufacturing
processes of the present invention yield greater assembly
uniformity without sacrificing desired and required target assembly
properties.
[0030] Embodiments of the present invention are suitably applied to
many sputtering target bond assemblies by vacuum hot pressing. For
example, processes of the present invention preferably may be used
with mixed powder of Ti--W diffusion bonded to Ti at temperatures
of from about 1100.degree. C. to about 1400.degree. C., preferably
from about 1200.degree. C. to about 1300.degree. C. and most
preferably about 1250.degree. C. Mixed powder of Cu--Cr diffusion
bonds to Cu backing plate at temperatures of from about 900.degree.
C. to about 1050.degree. C., preferably from about 950.degree. C.
to about 1010.degree. C. and most preferably about 1000.degree. C.
Preferred powder size is less than about 150 .mu.m and greater than
about 40 .mu.m, more preferably from about 100 .mu.m to about 40
.mu.m. Additionally, the processes of the present invention
optionally roughen the bond surface of the backing plate from about
100 .mu.in to about 300 .mu.in, and preferably about 200 .mu.in Ra
by grit, as embodiments of the present invention contemplate
blasting or other surface roughening methods. Pressing pressures of
from about 0.5 ksi to about 6.0 ksi are preferred, more preferably
from about 1.0 ksi to about 6.0 ksi, and most preferably about 2
ksi, using a preferred holding time of from about 1 hour to about 8
hours, more preferably from about 2 hours to about 8 hours, and
most preferably about 5 hours, under a vacuum of about 10E-5
Ton.
[0031] Non-limiting preferred embodiments of the present invention
are presented in the following Examples, which are provided for
illustrative purposes only.
EXAMPLES
Example 1
[0032] A 4 inch diameter.times.0.5 inch thick Cu blank was
grit-blasted at one surface by SiC to generate 200 .mu.in Ra
roughness prior to being placed into a 4 inch diameter graphite
mold with the grit-blasted surface facing upward. An amount of
about 400 grams Cu--50 wt% Cr mixed powder is placed on the top of
the Cu blank and pressed at 2 ksi and 1000.degree. C. under 10E-5
Ton vacuum for 5 hours. The pressed assembly showed that 100% bond
and 96% target density were achieved. A tensile test as described
in U.S. Pat. No. 6,092,427 (and incorporated by reference herein as
if made a part of the present disclosure) was used, and the test
piece was fractured at the target side at 980 pounds of pressure.
At that stage no separation was observed at the bond interface. By
applying the same aforementioned tensile test method to the
conventional In--30Sn solder-bonded Cu--50%Cr target/Cu backing
plate, only 320 pounds was required to separate the In/30Sn
solder-bonded Cu--50%Cr target/Cu backing plate bond assembly at
the bond interface. FIG. 4 is a cross-sectional micro-photograph
showing a target assembly of the present invention having a Cu--50
wt% Cr diffusion bond to Cu backing plate sample which was made by
pressing the 50 wt% Cu/50 Cr mixed powder to a Cu blank at
1000.degree. C/2ksi for 5 hours.
Example 2
[0033] A 4 inch diameter.times.0.5 inch thick commercial Ti blank
was grit-blasted at one surface by SiC to generate 150 .mu.in Ra
roughness prior to being placed into a 4 inch diameter graphite
mold with the grit-blasted surface facing upward. An amount of
about 740 grams W--10 wt% Ti mixed powder was loaded on the top of
the Ti blank and pressed at 2 ksi and 1250.degree. C. under 10E-5
Torr vacuum for 5 hours. The pressed assembly showed that 100% bond
and 100% target density were achieved. Using the testing method
disclosed above in Example 1, the test piece was fractured at the
target side at 800 pounds. At that stage, no separation was
observed at the bond interface. By applying the same tensile test
method to the conventional In--30Sn solder-bonded W--10%Ti
target/Ti backing plate, only 320 pounds was required to separate
the In/30Sn solder-bonded W--10%Ti target/Cu backing plate bond
assembly at the bond interface. FIG. 5 is a cross-sectional
micro-photograph showing a target assembly of the present invention
having a W--10 wt% Ti diffusion bond to Ti backing plate by
pressing is shown. The 90 wt% W/10 wt% Ti mixed powder is pressed
to a Ti blank at 1250.degree. C/2ksi for 5 hours.
Example 3
[0034] An 18 inch diameter.times.0.5 inch thick commercial Ti blank
was machined on the bond surface to have radius prior to being
grit-blasted by SiC to generate 150 .mu.in Ra roughness. This blank
was then placed to an 18 inch diameter graphite mold with the
dished surface facing up. An amount of about 25,000 grams of
W.times.10 wt% Ti mixed powder was loaded on the top of the Ti
blank and pressing at 2 ksi and 1250.degree. C. under 10E-5 Torr
vacuum for 5 hours. The pressed assembly showed that 100% bond and
100% target density were achieved. In addition, comparing to the
known pressed assembly with greater than 0.1 inch warp by flat
pressing, warp of the bond assembly using the concave design was
less than 0.03 inch. Therefore, no flattening is required prior to
machining to the final dimension of sputtering target.
[0035] Embodiments of the present invention are suitable to be
applied to the following sputtering target bond assemblies by
vacuum hot pressing. The following conditions are particularly
preferred in use with the following compound combinations,
including the use of mixed powders of Ti--X (Ti--W, Ti--Cu, Ti--Fe,
Ti--Ni, Ti--Al, etc.) for the target materials in combination with
Ti or Mo backing plates subjected to a temperature range of from
about 1100.degree. C. to about 1300.degree. C.
[0036] Alternate preferred conditions and compound combinations
include mixed powders of Cu--X (Cu--Cr, Cu--Ti, Cu--Ni, and
combinations thereof, etc.) as target materials, and backing plates
made from Cu, Cu alloys, stainless steel, Ti, Mo, and combinations
thereof, at pressing temperatures in the range of from about
900.degree. C. to about 1050.degree. C. Additionally, Ru powder may
be used as the target material with Mo or W used as the backing
plate, with a processing temperature range of from about
1700.degree. C. to about 2000.degree. C.
[0037] Preferred powder size is less than about 100 .mu.m and
greater than about 40 .mu.m. The bond surface of the backing plate
is optionally roughened with a means having a grit range of from
about 100.mu. to about 300.mu. Ra by grit, and it is understood
that blasting or other surface roughening methods may be employed,
with preferred minimum pressing pressure of about 0.5 ksi minimum,
at preferred minimum holding time of about 3 hours at a minimum
preferred vacuum of about 10E-4 Torr.
[0038] While the invention has been described in detail with
reference to specific embodiments thereof, it will be apparent to
one skilled in the field that various changes, modifications and
substitutions can be made, and equivalents employed without
departing from, and are intended to be included within, the scope
of the claims.
* * * * *