U.S. patent application number 10/492310 was filed with the patent office on 2004-12-09 for sputtering target and production method therefor.
Invention is credited to Hukushima, Atsushi.
Application Number | 20040245099 10/492310 |
Document ID | / |
Family ID | 19169846 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040245099 |
Kind Code |
A1 |
Hukushima, Atsushi |
December 9, 2004 |
Sputtering target and production method therefor
Abstract
Provided is a sputtering target manufactured by die forging,
characterized in that an average crystal grain size D at a portion
where an average crystal grain size is the largest and an average
crystal grain size d at a portion where an average crystal grain
size is the smallest are related as 1.0<D/d<2.0. Further
provided is a method capable of constantly manufacturing a
sputtering target excellent in characteristics by improving and
elaborating forging and heat treatment processes to render a
crystal size fine and uniform, and a sputtering target excellent in
quality obtained by this method.
Inventors: |
Hukushima, Atsushi;
(Ibaraki, JP) |
Correspondence
Address: |
Howson & Howson
Spring House Corporate Center
PO Box 457
Spring House
PA
19477
US
|
Family ID: |
19169846 |
Appl. No.: |
10/492310 |
Filed: |
April 12, 2004 |
PCT Filed: |
July 30, 2002 |
PCT NO: |
PCT/JP02/07715 |
Current U.S.
Class: |
204/298.12 ;
117/7 |
Current CPC
Class: |
C23C 14/3414 20130101;
C22F 1/08 20130101; C22F 1/183 20130101 |
Class at
Publication: |
204/298.12 ;
117/007 |
International
Class: |
C30B 001/00; C30B
003/00; C30B 005/00; C30B 028/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 2001 |
JP |
2001-358713 |
Claims
1: A sputtering target manufactured by die forging and having at
least one three-dimensional stereoscopic hat or dome shaped
structure in diametrical cross-section with an opening diameter and
a depth, a ratio of said opening diameter and said depth being 1:3
or less, and an average crystal grain size D at a portion of said
target where an average crystal grain size is largest and an
average grain size d at a portion of said target where an average
crystal grain size is smallest being related as
1.0<D/d<2.0.
2: A sputtering target, comprising a hexagonal sputtering target
manufactured by die forging and having a three-dimensional
stereoscopic structure such as a hat or dome shape with an opening
diameter and a depth, a ratio of said opening diameter and said
depth being 1:3 or less, and said target having an erosion face
with a total intensity ratio of a (002) face, and a (103) face,
(014) face and (015) face within a 30.degree. angle thereof is of
30% or more, and variation being within .+-.10% of an average
value.
3. (canceled).
4: A method of manufacturing a sputtering target, comprising the
steps of performing hot or cold kneading and straightening
annealing to an ingot or billet material; adjusting crystal grains
of the material by performing cold preforming and recrystallization
annealing; thereafter performing die forging; and after said die
forging step, performing straightening or recrystallization
annealing.
5: A method according to claim 4, wherein said sputtering target is
a hexagonal sputtering target and has an erosion face with a total
intensity ratio of a (002) face, and a (103) face, (014) face and
(015) face within a 30.degree. angle thereof of 30% or more, and
variation is within .+-.10% of an average value.
6-16 (canceled).
17: A sputtering target according to claim 1, wherein said target
is made of a material selected from a group consisting of copper,
titanium, aluminum, nickel, cobalt, tantalum, and alloys
thereof.
18: A sputtering target according to claim 2, wherein said
sputtering target is made of titanium.
19: A method according to claim 5, wherein said sputtering target
is made of titanium.
20: A method according to claim 4, wherein a total absolute value
of true strain in said hot or cold kneading is 4 or more.
21: A method according to claim 20, wherein said material has a
melting point of Tm, and said die forging step is performed at a
temperature of 0.5 Tm or less.
22: A method according to claim 21, wherein said recrystallization
annealing step performed after said cold preforming step and said
straightening or recrystallization annealing step performed after
said die forging step are performed at a temperature of 0.6 Tm or
less.
23: A method according to claim 22, wherein said cold preforming
step is performed at a processing ratio of 20 to 90%.
24: A method according to claim 4, wherein said material has a
melting point of Tm and said die forging step is performed at a
temperature of 0.5 Tm or less.
25: A method according to claim 4, wherein said material has a
melting point of Tm and said recrystallization annealing step
performed after said cold preforming is performed at a temperature
of 0.6 Tm or less.
26: A method according to claim 4, wherein said material has a
melting point of Tm and said straightening or recrystallization
annealing step performed after said die forging step is performed
at a temperature of 0.6 Tm or less.
27: A method according to claim 4, wherein said cold preforming
step is performed at a processing ratio of 20 to 90%.
28: A method according to claim 4, wherein, as a result of
performing recrystallization annealing after cold preforming, an
average crystal grain size D.sub.0 at a portion of said target
where an average crystal grain size is largest and an average grain
size d.sub.0 at a portion of said target where an average crystal
grain size is smallest are related as
1.0<D.sub.0/d.sub.0<1.5.
29: A method according to claim 4, wherein, as a result of
performing recrystallization annealing after cold preforming, a
grain size of said material is 200% or less of an ultimate average
crystal grain size of said target.
30: A method according to claim 4, wherein, as a result of
performing straightening or recrystallization annealing after die
forging, an average crystal grain size of said target is in a range
of 1 to 500 .mu.m.
31: A method according to claim 4, wherein an average crystal grain
size D at a portion of said target where an average crystal grain
size is largest and an average grain size d at a portion where an
average crystal grain size is smallest are related as
1.0<D/d<2.0.
32: A method according to claim 4, wherein said target is made of a
material selected from a group consisting of copper, titanium,
aluminum, nickel, cobalt, tantalum, and alloys thereof.
Description
TECHNICAL FIELD
[0001] The present invention pertains to a sputtering target having
a complex three-dimensional (stereoscopic) structure formed by die
forging, and the manufacturing method thereof.
BACKGROUND ART
[0002] In recent years, the sputtering method for forming a film
from materials such as metal or ceramics has been used in numerous
fields such as electronics, corrosion resistant materials and
ornaments, catalysts, as well as in the manufacture of
cutting/grinding materials and abrasion resistant materials.
[0003] Although the sputtering method itself is a well-known method
in the foregoing fields, recently, particularly in the electronics
field, a sputtering target suitable for forming films of complex
shapes and forming circuits is in demand. For instance, a target
having a three-dimensional (stereoscopic) structure in which the
cross section is of a hat shape or dome shape, or a combination
thereof is now being used.
[0004] Generally, a target having this kind of three-dimensional
structure is manufactured by performing hot forging to an ingot or
billet formed by dissolving and casting metal, thereafter
performing annealing thereto, and further performing die forging
thereto. In this kind of manufacturing procedure, the hot forging
performed to the ingot or billet will destroy the cast structure,
disperse or eliminate the pores and segregations, and, by further
annealing this, recrystallization will occur, and the precision and
strength of the structure can be improved to a certain degree.
[0005] Next, this forged, recrystallized and annealed material is
formed into a target shape having a prescribed three-dimensional
structure via die forging, and, thereafter, recrystallization
annealing and straightening annealing are performed thereto and
surface treatment is ultimately performed thereto in order to
manufacture the target.
[0006] With this type of target manufacturing method, although
there is no particular problem upon manufacturing an ordinary flat
target, with a target having a three-dimensional (stereoscopic)
structure in which the cross section is of a hat shape or dome
shape, or the combination thereof, since there are portions that
will be strongly subject to plastic deformation and portions that
will hardly be subject to plastic deformation during die forging,
there are cases where abnormal differences occur in the size of the
crystal grains during the recrystallization annealing and
straightening annealing thereafter.
[0007] For instance, although portions facing the forging direction
will merely be subject to compressive force, portions along the
forging direction; that is, the sidewall of the three-dimensional
structure will be subject to harsh, strong processing.
[0008] As described above, the grain size of the recrystallized
grains upon annealing will significantly differ at portions that
are strongly subject to plastic deformation and portions that are
weakly subject to plastic deformation. In other words, crystals
become fine grains at portions that are strongly subject to plastic
deformation, and crystals become coarse grains at portions that are
weakly subject to plastic deformation. Further, the boundary area
of such portions that are strongly and weakly subject to plastic
deformation will become a crystal structure in which the fine
grains and coarse grains exist at random, or in which the fine
grains and coarse grains change in a phased manner.
[0009] Generally, upon performing sputtering, finer the crystals of
the target, more even the deposition, and a film having even and
stable characteristics, with few generation of arcing or particles,
can be obtained.
[0010] Therefore, the existence of the foregoing coarse crystal
grains and irregular crystal grains that generate during die
forging or the annealing to be performed thereafter will increase
the generation of arcing and particles, and there is a significant
problem in that the quality of the sputtering film will
deteriorate. Needless to say, it is not possible to consider using
a stamp-forged product in which strain remains therein, and this
will further deteriorate the quality.
[0011] In light of the above, there is a problem in that a
sputtering target having a three-dimensional structure manufactured
by die forging would deteriorate the film property pursuant to the
crystal grains becoming coarse and uneven.
DISCLOSURE OF THE INVENTION
[0012] In order to overcome the foregoing problems, an object of
the present invention is to provide a method capable of constantly
manufacturing a sputtering target excellent in characteristics by
improving and elaborating forging and heat treatment processes to
render a crystal size fine and uniform, and a sputtering target
excellent in quality obtained by this method.
[0013] The present invention provides:
[0014] 1. A sputtering target manufactured by die forging, wherein
the average crystal grain size D at a portion where an average
crystal grain size is the largest and an average grain size d at a
portion where an average crystal grain size is the smallest are
related as 1.0<D/d<2.0;
[0015] 2. A hexagonal sputtering target of titanium or the like
manufactured by die forging, wherein, in the erosion face of the
target, the total intensity ratio of the (002) face, and the (103)
face, (014) face and (015) face within a 30.degree. angle thereof
is 30% or more, and the variation is within .+-.10% of the average
value.
[0016] 3. A sputtering target manufactured by die forging according
to paragraph 1 or paragraph 2 above, wherein the ratio of the
opening diameter and depth of one or more hat shapes or dome shapes
appearing in the diametrical cross section is 1:3 or less;
[0017] 4. A manufacturing method of a sputtering target by die
forging, comprising the steps of performing hot kneading or cold
kneading and straightening annealing to an ingot or billet
material; adjusting the crystal grains by performing cold
preforming and recrystallization
[0018] annealing; and thereafter performing die forging;
[0019] 5. A manufacturing method of a hexagonal sputtering target
of titanium or the like manufactured by die forging according to
paragraph 4 above, wherein, in the erosion face of the target, the
total intensity ratio of the (002) face, and the (103) face, (014)
face and (015) face within a 30.degree. angle thereof is 30% or
more, and the variation is within .+-.10% of the average value.
[0020] 6. A manufacturing method of a sputtering. target according
to paragraph 4 or paragraph 5 above, wherein the total absolute
value of the true strain in hot kneading or cold kneading is 4 or
more;
[0021] 7. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 6 above, wherein, when the melting
point of the material is Tm, die forging is performed at 0.5 Tm or
less;
[0022] 8. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 7 above, wherein straightening
annealing or recrystallization annealing is performed after die
forging;
[0023] 9. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 8 above, wherein, when the melting
point of the material is Tm, recrystallization annealing after the
cold preforming is performed at 0.6 Tm or less;
[0024] 10. A manufacturing method of a sputtering target according
to paragraph 8 or paragraph 9 above, wherein, when the melting
point of the material is Tm, straightening annealing or
recrystallization annealing is performed at 0.6Tm or less after die
forging;
[0025] 11. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 10 above, wherein cold preforming at
a processing ratio of 20 to 90% is performed; 12. A manufacturing
method of a sputtering target according to any one of paragraphs 4
to 11 above, wherein, as a result of performing recrystallization
annealing after cold preforming, the average crystal grain size
D.sub.0 at a portion where an average crystal grain size is the
largest and an average grain size d.sub.0 at a portion where an
average crystal grain size is the smallest are 10 related as
1.0<D.sub.0/d.sub.0<1.5;
[0026] 13. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 12 above, wherein, as a result of
performing recrystallization annealing after cold preforming, the
grain size is made to be 200% or less of the ultimate average
crystal grain size.
[0027] 14. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 13 above, wherein, as a result of
performing crystal homogenization annealing or straightening
annealing after die forging, the average crystal grain size is made
to be in a range of 1 to 500 .mu.m;
[0028] 15. A manufacturing method of a sputtering target according
to any one of paragraphs 4 to 13 above, wherein the average crystal
grain size D at a portion where an average crystal grain size is
the largest and an average grain size d at a portion where an
average crystal grain size is the smallest are related as
1.0<D/d<2.0; and
[0029] 16. A sputtering target and manufacturing thereof according
to any one of paragraphs 1 to 15 above, wherein the target material
is copper, titanium, aluminum, nickel, cobalt, tantalum, or the
alloys thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is an explanatory diagram showing the structure of a
target stamp forged into a hat shaped target;
[0031] FIG. 2 is an explanatory diagram showing the structure of a
target stamp forged into a shape in which the cross section thereof
appears to be a connection of two hat shaped targets; and
[0032] FIG. 3 is a diagram showing the measurement position of the
face orientation.
BEST MODE FOR CARRYING OUT THE INVENTION
[0033] The sputtering target of the present invention is
manufactured with the following steps. specifically, foremost, a
metal material such as copper, titanium, aluminum, nickel, cobalt,
tantalum, or the alloys thereof is dissolved and cast to
manufacture an ingot or billet. Next, his ingot or billet is
subject to hot forging or cold forging and straightening
annealing.
[0034] As a result of this forging, it is possible to destroy this
cast structure and disperse or eliminate the pores or segregations.
Annealing is further performed thereto for realizing
recrystallization, and the hot forging or cold forging and
recrystallization annealing processes are able to improve the
fineness and strength of the structure.
[0035] As the foregoing hot and cold forging, it is preferable to
perform knead forging (kneading), and the repetition of hot or cold
forging is effective in improving the characteristics. Further,
although the recrystallization temperature will differ depending on
the metal, the optimum temperature is determined in consideration
of the amount of strain, as well as temperature and time.
[0036] In the foregoing hot kneading or cold kneading, it is
desirable that the total absolute value of the true strain is 4 or
more. This condition is particularly effective when forging
tantalum.
[0037] Next, cold preforming is performed. When the melting point
of the material is Tm, this cold performing is controlled to be 0.3
Tm or less, preferably 0.2 Tm or less.
[0038] Further, although the degree of processing will differ
depending on the ultimately demanded crystal grain size, it is
preferable that the degree of processing is 20% or more. It is
particularly preferable to perform processing at a processing ratio
of 50 to 90%. Thereby, intense processing strain can be yielded in
the material.
[0039] As described above, the reason for performing cold
preforming is to introduce a larger processing strain, and to
maintain a fixed temperature of the material during the preforming
step as much as possible. As a result, the stain to be introduced
can be enlarged sufficiently, and be made uniform.
[0040] After performing cold preforming, the crystal grain size is
adjusted by performing recrystallization annealing. When the
melting point of the material is Tm, it is desirable that this
recrystallization annealing after the cold preforming is performed
at 0.6 Tm or less, preferably 0.4 Tm or less.
[0041] As a result, the average crystal grain size D.sub.0 at a
portion where an average crystal grain size is the largest and an
average grain size d.sub.0 at a portion where an average crystal
grain size is the smallest will be related as
1.0<D.sub.0/d.sub.0<1.5.
[0042] Cold preforming is an important step in the present
invention, and, with this, it is possible to obtain a target having
fine and uniform crystals in the final step.
[0043] Next, this cold preformed material having fine and uniform
crystals is subject to die forging. Here, spinning processing is
included in the die forging. In other words, spinning processing
shall be included in every die forging described in this
specification.
[0044] Further, after die forging, crystal homogenization annealing
or straightening annealing is performed in order to make the
average crystal grain size to be within a range of 1 to 500
.mu.m.
[0045] In this die forging, there will be portions that are
strongly subject to the foregoing strain, and portions that are
hardly subject to such strain. Nevertheless, with the portions
weakly subject to the strain, since the crystal grains have been
adjusted to be fine in the prior cold preforming step, there will
not be a significant difference in the crystal grain size in
comparison with the other portions strongly subject to the
strain.
[0046] According to the above, as a result of performing crystal
homogenization annealing or straightening annealing after die
forging, the internal strain can be eliminated, and a target having
an overall approximately uniform crystal grain size can be
obtained. And, a sputtering target in which the average crystal
grain size D at a portion where an average crystal grain size is
the largest and an average grain size d at a portion where an
average crystal grain size is the smallest will be related as
1.0<D/d<2.0 can be obtained.
[0047] Moreover, with a hexagonal sputtering target of titanium in
particular, it is possible to obtain a sputtering target wherein,
in the erosion face of the target, the total intensity ratio of the
(002) face, and the (103) face, (014) face and (015) face within a
30.degree. angle against such (002) face is 30% or more, and the
variation is within .+-.10% of the average value. This type of face
orientation centered around the (002) face is effective in
realizing uniform sputtering, and yields evenness in the
deposition.
EXAMPLES AND COMPARATIVE EXAMPLES
[0048] The present invention is now explained in detail with
reference to the Examples. These Examples are merely illustrative,
and the present invention shall in no way be limited thereby. In
other words, the present invention shall only be limited by the
scope of claim for a patent, and shall include the various
modifications other than the Examples of this invention.
[0049] Although the following Examples and Comparative Examples are
exemplified taking pure copper and pure titanium as examples,
similar results were obtained with aluminum, nickel, cobalt,
tantalum, and the alloys thereof.
EXAMPLE 1
[0050] A copper (6N) material was dissolved and cast to prepare an
ingot. Next, this ingot was subject to hot kneading at 800.degree.
C. This hot kneading destroyed the cast structure, as well as
dispersed and eliminated pores and segregations, and a forged
product having a uniform structure was obtained thereby.
[0051] Next, using this hot kneaded material, preforming was
performed at room temperature and a processing ratio of 50%. After
performing this preforming step, recrystallization annealing was
performed at 300.degree. C. for 2 hours in order to adjust the
crystal grains. As a result, it was possible to adjust the average
crystal grain size to be a fine and uniform crystal grain size of
85 .mu.m.
[0052] The preformed material having this kind of fine and uniform
crystals was stamp forged into a hat shaped target. Die forging was
performed at 280.degree. C. After die forging, crystal grain
homogenization annealing and straightening annealing were performed
at 300.degree. C. for 2 hours.
[0053] FIG. 1 is a cross section of the hat shaped target prepared
in the foregoing step. Symbol C in FIG. 1 represents the hat
ceiling portion, A and E represent the flange portion, B and D
represent the side portion, and all of these portions are on the
target side (side subject to erosion upon sputtering).
[0054] The average grain size was respectively A: 91 .mu.m, B: 86
.mu.m, C: 112 .mu.m, D: 79 .mu.m and E: 92 .mu.m, and it was
possible to prepare a target having a uniform grain size in which
the ratio D/d of an average crystal grain size D at a portion where
an average crystal grain size is the largest and an average grain
size d at a portion where an average crystal grain size is the
smallest realizes D/d=1.46.
[0055] The foregoing results are shown together with the following
Comparative Examples in Table 1.
[0056] In die forging, as described above, there will be portions
that are strongly subject to the strain and portions that are
hardly subject to the strain. In the present method, the portions
strongly subject to the strain during die forging will generate
recrystallization and grain growth in the subsequent crystal grain
homogenization annealing step. Thus, appropriate crystal grain
homogenization annealing conditions were established so as to align
the grain size at the foregoing step to the grain size after the
cold preforming and recrystallization annealing steps.
[0057] Moreover, in portions that are not strongly subject to the
strain, the crystal grain size has been adjusted to be fine in the
prior cold preforming and recrystallization annealing steps. Thus,
so as long as the annealing of the present invention is performed,
it is possible to avoid significant differences in the crystal
grain size in portions strongly subject to strain and portions
weakly subject to strain without having to encounter considerable
grain growth.
[0058] The X-ray diffraction intensity ratio I (111)/I(200) of the
(111) face and (200) face in the erosion face of the copper, hat
shaped target was sought. Further, the measured portions are the
respective measurement positions depicted in FIG. 3. Further,
similar to the case of Example 2 described later, the orientation
intensity ratio in a case of comparing this with a random
orientation is also shown.
[0059] As a result of measurement, with position a: 2.6, position
b: 2.7, position c: 2.9, position d: 2.5, position e 2.6, and
position f: 2.5, the positions oriented toward (111) greater than
random orientation I*(111)/I*(200)=2.08, and significant variations
in the orientation could not be seen in any of the positions. As a
result, it is evident that the uniformity of the target was
retained thereby.
COMPARATIVE EXAMPLE 1
[0060] Similar to Example 1, a copper (6N) material was dissolved
and cast to prepare an ingot. Next, this ingot was subject to cold
kneading, cold preforming was performed at a processing ratio of
50%, and recrystallization annealing was further performed at
300.degree. C. for 2 hours. This preformed material was similarly
stamp forged into a hat shaped target at 400.degree. C.
[0061] After die forging, crystal grain homogenization annealing
and straightening annealing were performed at 425.degree. C. The
average crystal grain size of portions A to E at such time is
similarly shown in Table 1.
[0062] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0063] The average grain size was respectively A: 344 .mu.m, B: 184
.mu.m, C: 211 .mu.m, D: 192 .mu.m and E: 379 .mu.m, and coarse on
the whole. Thus, obtained was a target having uneven grain sizes in
which the ratio D/d of an average crystal grain size D at a portion
where an average crystal grain size is the largest and an average
grain size d at a portion where an average crystal grain size is
the smallest became D/d=2.06.
[0064] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of the die forging
temperature and annealing temperature after such die forging being
too high.
COMPARATIVE EXAMPLE 2
[0065] Similar to Example 1, a copper (6N) material was dissolved
and cast to prepare an ingot. Next, this ingot was subject to
preforming with hot forging at 750.degree. C. As with Example 1,
this preformed material was stamp forged into a hat shaped target
at 280.degree. C., and, after such die forging, crystal grain
homogenization annealing and straightening annealing were performed
at 300.degree. C. for 2 hours. The average crystal grain size of
portions A to E at such time is similarly shown in Table 1. Here,
the recrystallization annealing subsequent to the preforming step
was not performed.
[0066] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0067] The average grain size was respectively A: 724 .mu.m, B: 235
.mu.m, C: 257 .mu.m, D: 244 .mu.m and E: 773 .mu.m, and even more
coarse on the whole. Thus, obtained was a target having further
uneven grain sizes in which the ratio D/d of an average crystal
grain size D at a portion where an average crystal grain size is
the largest and an average grain size d at a portion where an
average crystal grain size is the smallest became D/d=3.29.
[0068] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of insufficient
processing since cold preforming was not performed, and because
recrystallization annealing subsequent to preforming was not
performed.
COMPARATIVE EXAMPLE 3
[0069] Similar to Example 1, a copper (6N) material was dissolved
and cast to prepare an ingot. Next, this ingot was subject to
preforming with hot forging at 750.degree. C. This preformed
material was similarly stamp forged into a hat shaped target at
650.degree. C., and, after such die forging, crystal grain
homogenization annealing and straightening annealing were performed
at 700.degree. C. for 2 hours. The average crystal grain size of
portions A to E at such time is similarly shown in Table 1. Here,
the recrystallization annealing subsequent to the preforming step
was not performed.
[0070] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0071] The average grain size was respectively A: 2755 .mu.m, B:
654 .mu.m, C: 775 .mu.m, D: 688 .mu.m and E: 2911 .mu.m, and
abnormally coarse on the whole. Thus, obtained was a target having
significant uneven grain sizes in which the ratio D/d of an average
crystal grain size D at a portion where an average crystal grain
size is the largest and an average grain size d at a portion where
an average crystal grain size is the smallest became D/d=4.45.
[0072] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of insufficient
processing since cold preforming was not performed, and because the
die forging temperature was too high.
COMPARATIVE EXAMPLE 4
[0073] Similar to Example 1, a copper (6N) material was dissolved
and cast to prepare an ingot. Next, this ingot was subject to
preforming with hot forging at 400.degree. C. As with Example 1,
this preformed material was stamp forged into a hat shaped target
at 280.degree. C., and, after such die forging, crystal grain
homogenization annealing and straightening annealing were performed
at 300.degree. C. for 2 hours. The average crystal grain size of
portions A to E at such time is similarly shown in Table 1. Here,
the recrystallization annealing subsequent to the preforming step
was not performed.
[0074] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0075] The average grain size was respectively A: 121 .mu.m, B: 88
.mu.m, C: 308 .mu.m, D: 105 .mu.m and E: 122 .mu.m, and relatively
fine on the whole. Nevertheless, center portion C became coarse,
and obtained was a target having uneven grain sizes in which the
ratio D/d of an average crystal grain size D at a portion where an
average crystal grain size is the largest and an average grain size
d at a portion where an average crystal grain size is the smallest
became D/d=3.50.
[0076] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of insufficient
processing since cold preforming was not performed.
1TABLE 1 Die Average Crystal Grain Size (.mu.m) Preforming
Recrystallization forging Annealing A B C D E D/d Example 1 Cold
300.degree. C. 280.degree. C. 300.degree. C. 91 86 112 79 92 1.42
Comparative Cold 300.degree. C. 400.degree. C. 425.degree. C. 344
184 211 192 379 2.06 Example 1 Comparative 750.degree. C. --
280.degree. C. 300.degree. C. 724 235 257 244 773 3.29 Example 2
Comparative 750.degree. C. -- 650.degree. C. 700.degree. C. 2755
654 775 688 2911 4.45 Example 3 Comparative 400.degree. C. --
280.degree. C. 300.degree. C. 121 88 308 105 122 3.50 Example 4
EXAMPLE 2
[0077] A titanium (4N5) material was dissolved and cast to prepare
an ingot. Next, this ingot was subject to cylindrical forging at
650.degree. C. to prepare a billet. Here, the total absolute value
of the true strain was 4.
[0078] Next, using this billet, preforming was performed at room
temperature and a processing ratio of 50%. After performing this
preforming step, recrystallization annealing was performed at
500.degree. C. for 2 hours in order to adjust the crystal grains.
As a result, it was possible to adjust the average crystal grain
size to be a fine and uniform crystal grain size of 35 .mu.m.
[0079] The cold preformed material having this kind of fine and
uniform crystals was stamp forged into a hat shaped target. Die
forging was performed at 450.degree. C. After die forging, crystal
grain homogenization annealing and straightening annealing were
performed at 500 .degree. C. for2 hours.
[0080] Since the cross section of the hat shaped target prepared in
the foregoing step is the same as FIG. 1, the following explanation
will be made with reference to FIG. 1. Symbol C in FIG. 1
represents the hat ceiling portion, A and E represent the flange
portion, B and D represent the side portion, and all of these
portions are on the target side (side subject to erosion upon
sputtering).
[0081] The average grain size was respectively A: 37 .mu.m, B: 31
.mu.m, C: 34 .mu.m, D: 29 .mu.m and E: 39 .mu.m, and it was
possible to prepare a target having a uniform grain size in which
the ratio D/d of an average crystal grain size D at a portion where
an average crystal grain size is the largest and an average grain
size d at a portion where an average crystal grain size is the
smallest realizes D/d=1.35.
[0082] The foregoing results are shown together with the following
Comparative Examples in Table 2.
[0083] Moreover, the total intensity ratio of the (002) face in the
erosion face of the hat shaped target, and the (103) face, (014)
face and (015) face within a 30.degree. angle thereof was sought
(here, this shall be the (002) face orientation rate). Further, the
measured portions are the respective measurement positions depicted
in FIG. 3 described later.
[0084] The intensity ratio was sought as follows. I(hkl) is the
intensity of the diffraction peak of the (hkl) face sought with
X-ray diffraction. I*(hkl) is the relative intensity (meaning the
intensity when the orientation is entirely random) of the JCPDS
(Joint Committee of Diffraction Standard) card. Therefore,
I(hkl)/I*(hkl) shows the normalized orientation intensity of the
(hkl) face in comparison to the random orientation.
[0085] .SIGMA.[I(hkl)/I*(hkl)] is the total normalized intensity
ratio. Therefore, the (002) face orientation rate can be calculated
with
[I(002)/I*(002)+I(103)/I*(103)+I(014)/I*(014)+I(015)/I*(015)]/.SIGMA.[I(h-
kl)/I * (hkl)].
[0086] From the above, as a result of measuring the face
orientation in the measurement position b of FIG. 3, intensity
ratio 6.3% of the (002) face, intensity ratio 9.9% of the (103)
face, intensity ratio 8.2% of the (014) face, and intensity ratio
7.3% of the (015) face were obtained, and the total intensity ratio
was 34.3%.
[0087] Similarly, results of the total intensity ratio measured
respectively at the positions of a, b (as indicated above), c, d,
e, f and g of the hat shaped target illustrated in FIG. 3 were as
follows: position a: 34.3%, position b (as indicated above): 34.3%,
position c: 44.0%, position d: 43.2%, position e: 44.9%, position
f: 37.1% and position g: 43.3%. From the above, the total intensity
ratio of the (002) face, and the (103) face, (014) face and (015)
face within a 30.degree. angle against this (002) face at the
respective positions was 40.+-.10%, and a favorable target having
minimal variations in the orientation and superior evenness was
obtained thereby.
COMPARATIVE EXAMPLE 5
[0088] As with Example 2, a cylindrical forged billet was used to
perform cold preforming at a processing ratio of 50%. This
preformed material was stamp forged into a target at 700.degree.
C., and, after die forging, crystal grain homogenization annealing
and straightening annealing were performed at 750.degree. C. The
average crystal grain size of portions A to E at such time is
similarly shown in Table 2.
[0089] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0090] The average grain size was respectively A: 346 .mu.m, B: 140
.mu.m, C: 199 .mu.m, D: 156 .mu.m and E: 325 .mu.m, and coarse on
the whole. Thus, obtained was a target having uneven grain sizes in
which the ratio D/d of an average crystal grain size D at a portion
where an average crystal grain size is the largest and an average
grain size d at a portion where an average crystal grain size is
the smallest became D/d=2.47.
[0091] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of the die forging
temperature and recrystallization annealing temperature after such
die forging being too high.
COMPARATIVE EXAMPLE 6
[0092] As with Example 2, a cylindrical forged billet was used to
perform hot preforming at 500.degree. C. As with Comparative
Example 2, this preformed material was stamp forged into a hat
shaped target at 450.degree. C., and, after die forging, crystal
grain homogenization annealing and straightening annealing were
performed at 500.degree. C. The average crystal grain size of
portions A to E at such time is similarly shown in Table 2. Here,
the recrystallization annealing subsequent to the preforming step
was not performed.
[0093] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0094] The average grain size was respectively A: 124 .mu.m, B: 45
.mu.m, C: 66 .mu.m, D: 53 .mu.m and E: 133 .mu.m, and relatively
fine on the whole. Nevertheless, flange portions A and E became
coarse, and obtained was a target having uneven grain sizes in
which the ratio D/d of an average crystal grain size D at a portion
where an average crystal grain size is the largest and an average
grain size d at a portion where an average crystal grain size is
the smallest became D/d=2.96.
[0095] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of insufficient
processing since cold preforming was not performed, and because
recrystallization annealing subsequent to cold preforming was not
performed.
COMPARATIVE EXAMPLE 7
[0096] As with the Examples, a cylindrical forged billet was used
to perform hot preforming at 750.degree. C. This preformed material
was stamp forged into a hat shaped target at 450.degree. C., and,
after die forging, crystal grain homogenization annealing and
straightening annealing were performed at 500.degree. C. The
average crystal grain size of portions A to E at such time is
similarly shown in Table 2. Here, the recrystallization annealing
subsequent to the preforming step was not performed.
[0097] Similarly, symbol C represents the hat ceiling portion, A
and E represent the flange portion, B and D represent the side
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0098] The average grain size was respectively A: 156 .mu.m, B: 56
.mu.m, C: 87 .mu.m, D: 61 .mu.m and E: 177 .mu.m, and was coarser
than Comparative Example 6. Thus, obtained was a target having
uneven grain sizes in which the ratio D/d of an average crystal
grain size D at a portion where an average crystal grain size is
the largest and an average grain size d at a portion where an
average crystal grain size is the smallest became D/d=2.90.
[0099] The enlargement of the average grain size and unevenness of
the grain size could be considered a result of insufficient
processing since cold preforming was not performed, and because
recrystallization annealing subsequent to cold preforming was not
performed.
2TABLE 2 Die Average Crystal Grain Size (.mu.m) Preforming
Recrystallization forging Annealing A B C D E D/d Example 2 Cold
500.degree. C. 450.degree. C. 500.degree. C. 37 31 34 29 39 1.35
Comparative Cold 500.degree. C. 700.degree. C. 750.degree. C. 346
140 199 156 325 2.47 Example 5 Comparative 500.degree. C. --
450.degree. C. 500.degree. C. 124 45 66 53 133 2.96 Example 6
Comparative 750.degree. C. -- 450.degree. C. 500.degree. C. 156 56
87 61 177 2.90 Example 7
EXAMPLE 3
[0100] A copper (6N) material was dissolved and cast to prepare an
ingot. Next, this ingot was subject to hot kneading at 800.degree.
C. This hot kneading destroyed the cast structure, as well as
dispersed and eliminated pores and segregations, and a forged
product having a uniform structure was obtained thereby.
[0101] Next, using this hot kneaded material, preforming was
performed at room temperature and a processing ratio of 50%. After
performing this preforming step, recrystallization annealing was
performed at 300.degree. C. for 2 hours in order to adjust the
crystal grains. As a result, it was possible to adjust the average
crystal grain size to be a fine and uniform crystal grain size of
85 .mu.m.
[0102] The preformed material having this kind of fine and uniform
crystals was stamp forged into a target shape in which the cross
section thereof appears to be a connection of two hat shaped
targets. Die forging was performed at 280.degree. C. After die
forging, crystal grain homogenization annealing and straightening
annealing were performed at 300.degree. C. for 2 hours.
[0103] FIG. 2 is a cross section of the target prepared in the
foregoing step. Symbol C in FIG. 2 represents the hat ceiling
portion, A represents the flange portion, B and D represent the
side portion, E represents the hat connection portion, and all of
these portions are on the target side (side subject to erosion upon
sputtering).
[0104] The average grain size was respectively A: 100 .mu.m, B: 94
.mu.m, C: 118 .mu.m, D: 96 .mu.m and E: 92 .mu.m, and it was
possible to prepare a target having a uniform grain size in which
the ratio D/d of an average crystal grain size D at a portion where
an average crystal grain size is the largest and an average grain
size d at a portion where an average crystal grain size is the
smallest realizes D/d=1.28.
[0105] The foregoing results are shown together with the following
the Comparative Example in Table 3.
3TABLE 3 Die Average Crystal Grain Size (.mu.m) Preforming
Recrystallization forging Annealing A B C D E D/d Example 3 Cold
300.degree. C. 280.degree. C. 300.degree. C. 100 94 118 96 92 1.28
Comparative 400.degree. C. -- 280.degree. C. 300.degree. C. 127 123
278 101 113 2.46 Example 8
COMPARATIVE EXAMPLE 8
[0106] Similar to Example 3, a copper (6N) ingot was prepared. This
ingot was then subject to preforming via hot forging at 400.degree.
C. Similar to Example 4, this preformed material was stamp forged
into a target shape in which the cross section thereof appears to
be a connection of two hat shaped targets. After die forging,
crystal grain homogenization annealing and straightening annealing
were performed at 300.degree. C.
[0107] The average crystal grain size of portions A to E at such
time is similarly shown in Table 3. Here, the recrystallization
annealing subsequent to the preforming step was not performed.
[0108] Similarly, symbol C represents the hat ceiling portion, A
represents the flange portion, B and D represent the side portion,
E represents the hat connection portion, and all of these portions
are on the target side (side subject to erosion upon
sputtering).
[0109] The average grain size was respectively A: 127 .mu.m, B: 123
.mu.m, C: 278 .mu.m, D: 101 .mu.m and E: 113 .mu.m, and relatively
fine on the whole. Nevertheless, center portion C became coarse,
and obtained was a target having uneven grain sizes in which the
ratio D/d of an average crystal grain size D at a portion where an
average crystal grain size is the largest and an average grain size
d at a portion where an average crystal grain size is the smallest
became D/d=2.46. The enlargement of the average grain size and
unevenness of the grain size could be considered a result of
insufficient processing since cold preforming was not
performed.
EXAMPLE 4
[0110] A tantalum (5N) material was dissolved and EB cast to
prepare an ingot. Next, this ingot was repeatedly subject to
kneading at room temperature and straightening annealing at
1200.degree. C., and a billet in which the total absolute value of
the true strain is 8 was prepared.
[0111] Next, using this billet, rolling preforming was performed at
room temperature and a processing ratio of 70%. After performing
this preforming step, recrystallization annealing was performed at
900.degree. C. for 2 hours in order to adjust the crystal grains.
As a result, it was possible to adjust the average crystal grain
size to be a fine and uniform crystal grain size of 75 .mu.m.
[0112] The preformed material having this kind of fine and uniform
crystals was subject to spinning processing so as to form a target
shape in which the cross section thereof appears to be a connection
of two hat shaped targets. Spinning processing was performed at
room temperature. Thereafter, crystal grain homogenization
annealing and straightening annealing were performed at 925.degree.
C. for 2 hours.
[0113] Since the cross section of the connected hat shaped target
prepared in the foregoing step is the same as FIG. 2, the following
explanation will be based on FIG. 1. Symbol C in FIG. 1 represents
the hat ceiling portion, A represents the flange portion, B and D
represent the side portion, E represents the hat connection
portion, and all of these portions are on the target side (side
subject to erosion upon sputtering).
[0114] The average grain size was respectively A: 87 .mu.m, B: 76
.mu.m, C: 71 82 m, D: 82 .mu.m and E: 80 .mu.m, and it was possible
to prepare a target having a uniform grain size in which the ratio
D/d of an average crystal grain size D at a portion where an
average crystal grain size is the largest and an average grain size
d at a portion where an average crystal grain size is the smallest
realizes D/d=1.23.
[0115] The foregoing results are shown together with the following
Comparative Examples in Table 4.
4TABLE 4 Knead Average Forging Crystal Grain Size (.mu.m) Ratio
Preforming Recrystallization Die forging Annealing A B C D E D/d
Example 4 8 Cold 900.degree. C. Room 925.degree. C. 87 76 71 82 80
1.23 Temperature Comparative Less Cold 900.degree. C. Room
925.degree. C. 89 147 78 72 88 2.04 Example 9 than 4
Temperature
COMPARATIVE EXAMPLE 9
[0116] Similar to Example 4, a tantalum (5N) material was dissolved
and EB cast to prepare an ingot. Next, this ingot was subject to
forging at room temperature so as to prepare billet. Here, the
total absolute value of the true strain was 4 or less.
[0117] Next, using this billet, rolling preforming was performed at
room temperature and a processing ratio of 70%. After performing
this preforming step, recrystallization annealing was performed at
900.degree. C for 2 hours, but the average crystal grain size
varied depending on the location, and was between 80 to 150
.mu.m.
[0118] The cold rolled, preformed material was subject to spinning
processing so as to form a target shape in which the cross section
thereof appears to be a connection of two hat shaped targets.
Spinning processing was performed at room temperature. Thereafter,
crystal grain homogenization annealing and straightening annealing
were performed at 925.degree. C. for 2 hours.
[0119] Similarly, symbol C represents the hat ceiling portion, A
represents the flange portion, B and D represent the side portion,
E represents the hat connection portion, and all of these portions
are on the target side (side subject to erosion upon
sputtering).
[0120] The average grain size was respectively A: 89 .mu.m, B: 147
.mu.m, C: 78 .mu.m, D: 72 .mu.m and E: 88 .mu.m, and only one side;
namely, sidewall B became coarse, and obtained was a target having
uneven grain sizes in which the ratio D/d of an average crystal
grain size D at a portion where an average crystal grain size is
the largest and an average grain size d at a portion where an
average crystal grain size is the smallest became D/d=2.04.
[0121] The partial enlargement of the crystal grain size could be
considered a result of insufficient kneading at the time of knead
forging. As a result, the cast primary crystals could not be
completely destroyed, and the target was formed into its final
shape while retaining the distribution of the primary crystals.
EFFECT OF THE INVENTION
[0122] The present invention provides a manufacturing method of a
sputtering target having a three-dimensional structure by die
forging, and is characterized in that an average crystal grain size
D at a portion where an average crystal grain size is the largest
and an average crystal grain size d at a portion where an average
crystal grain size is the smallest are related as
1.0<D/d<2.0. As a result, a superior effect is yielded in
that it is possible to suppress the generation of arcing and
particles during sputtering, and obtain a film having uniform and
stable characteristics.
* * * * *