U.S. patent application number 11/070339 was filed with the patent office on 2005-10-20 for sputter target material and method of producing the same.
This patent application is currently assigned to HITACHI METALS, LTD. Invention is credited to Fukui, Tsuyoshi, Inoue, Keisuke, Iwasaki, Katsunori, Saitoh, Kazuya, Taniguchi, Shigeru, Uemura, Norio.
Application Number | 20050230244 11/070339 |
Document ID | / |
Family ID | 35049407 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050230244 |
Kind Code |
A1 |
Inoue, Keisuke ; et
al. |
October 20, 2005 |
Sputter target material and method of producing the same
Abstract
A sputter target material which is of a sintered material,
wherein the sputter target material consists of 0.5 to 50 atomic %
in total of at least one metal element (M) selected from the group
of Ti, Zr, V, Nb and Cr, and the balance of Mo and unavoidable
impurities, and has a microstructure seen at a perpendicular cross
section to a sputtering surface, in which microstructure oxide
particles exist near a boundary of each island of the metal element
(M), and wherein the maximum area of the island, which is defined
by connecting the oxide particles with linear lines so as to form a
closed zone, is not more than 1.0 mm.sup.2.
Inventors: |
Inoue, Keisuke; (Yasugi,
JP) ; Fukui, Tsuyoshi; (Nanbu, JP) ;
Taniguchi, Shigeru; (Taipei, TW) ; Uemura, Norio;
(Yonago, JP) ; Iwasaki, Katsunori; (Yasugi,
JP) ; Saitoh, Kazuya; (Yasugi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
HITACHI METALS, LTD
|
Family ID: |
35049407 |
Appl. No.: |
11/070339 |
Filed: |
March 3, 2005 |
Current U.S.
Class: |
204/298.13 ;
204/298.12; 419/48; 419/49 |
Current CPC
Class: |
B22F 2998/10 20130101;
C22C 1/045 20130101; B22F 1/0096 20130101; B22F 3/14 20130101; B22F
1/0003 20130101; B22F 2998/10 20130101; C23C 14/3414 20130101 |
Class at
Publication: |
204/298.13 ;
204/298.12; 419/049; 419/048 |
International
Class: |
C23C 014/32; B22F
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2004 |
JP |
2004-102899 |
Apr 16, 2004 |
JP |
2004-121955 |
Claims
1. A sputter target material which is of a sintered material,
wherein the sputter target material consists of 0.5 to 50 atomic %
in total of at least one metal element (M) selected from the group
of Ti, Zr, V, Nb and Cr, and the balance of Mo and unavoidable
impurities, and has a microstructure seen at a perpendicular cross
section to a sputtering surface, in which microstructure oxide
particles exist near a boundary of each island of the metal element
(M), and wherein the maximum area of the island, which is defined
by connecting the oxide particles with linear lines so as to form a
closed zone, is not more than 1.0 mm.sup.2.
2. A sputter target material according to claim 1, wherein the
metal element (M) is Nb.
3. A sputter target material according to claim 1, wherein the
sputter target material has a sputtering surface area of 1 m.sup.2
or more.
4. A sputter target material according to claim 1, wherein the
sputtering surface of the sputter target material has a rectangular
shape, and each side length of the rectangular shape is not less
than 1 m.
5. A method of producing a sputter target material, which comprises
the steps of: blending raw powders of Mo and at least one metal
element (M) selected from the group consisting of Ti, Zr, V, Nb and
Cr; compressing the blended raw powders to form a green compact;
pulverizing the green compact to produce a secondary powder having
an average particle size of not more than 5.0 mm; filling the
secondary powder into a pressurizing container; and sintering the
secondary powder as contained in the pressurizing container under
pressure, whereby obtaining the sputter target material, wherein
the sputter target has a microstructure seen at a perpendicular
cross section to a sputtering surface, in which microstructure
oxide particles exist near a boundary of each island of the metal
element (M), and wherein the maximum area of the island, which is
defined by connecting the oxide particles with linear lines so as
to form a closed zone, is not more than 1.0 mm.sup.2.
6. A method according to claim 5, which comprises a further step of
subjecting the sputter target material as sintered to plastic
working.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a sputter target material,
more particularly to a sputter target material used for forming Mo
alloy thin films which are used as electrical wiring, electrodes
and so on in flat panel display devices, and a method of producing
the same.
DESCRIPTION OF THE RELATED ART
[0002] Presently, films of a refractory metal, e.g. Mo, which have
low electrical resistance, are broadly used for thin film
electrodes and thin film wiring in liquid crystal displays (herein
referred to as LCDs) which are one type of flat panel display
devices. Since these thin-film electrodes, thin-film wiring, etc.
are required to have heat-resistance and corrosive resistance
properties during producing the thin film, there is a tendency to
favorably use Mo alloys containing additive Cr or W, for
example.
[0003] In general, when the Mo alloys are used to form wiring, the
sputtering method is carried out with utilization of a target
material having the same chemical composition as the wiring
material. With regard to the sputter target material of the Mo
alloy, there have been various proposals including preferred
chemical compositions and methods how to reduce impurities in the
target material.
[0004] For example, JP-A-09-059768 teaches a Mo--Cr alloy, which
contains 1 to 5 wt % Cr, as a sputter target material.
[0005] WO 95-16797 teaches a Mo--W alloy, which contains 20 to 70
atomic % W, as a sputter target material.
[0006] JP-A-2002-327264 teaches a Mo alloy, which contains 2 to 50
atomic % of Nb and/or V, as a sputter target material.
[0007] With regard to Mo having a high melting point, since it is
difficult to produce a sputter target material therefrom by the
melting/casting process, the powder sintering method is generally
used for producing such material.
[0008] A sputter target material of a Mo alloy is produced by
sintering a blend powder consisting of a Mo powder and a powder of
an additive element(s). According to this method, particles of the
additive element(s) in the blend powder are liable to agglomerate
with one another. Thus, there arises a problem that a segregation
of alloy components occurs after sintering resulting in that a thin
film formed from the sintered material by sputtering has not a
uniform distribution of component elements. Another problem is that
when the sintered material is subjected to plastic working, defects
such as cracking are liable to occur due to the segregation of
component elements.
[0009] Taking account of the above problems in the prior art, an
object of the present invention is to provide a Mo alloy sputter
target material according to which a component segregation is
restrained thereby improving the component uniformity of thin films
formed from the Mo alloy sputter target material by sputtering.
BRIEF SUMMARY OF THE INVENTION
[0010] The present inventors carried out various researches on the
above problems, and found a solution of the process that a powder
blend consisting of powders of Mo and an additive metal element(s)
M is prepared, the powder blend is compressed to produce a green
compact, and the green compact of the powder is sintered to obtain
a sintered product whereby making the additive metal element M,
which is capable of fixing oxygen in the Mo matrix, to be quite
finely dispersed in the Mo matrix, the sintered product having a
metal structure in which oxygen in the Mo matrix is fixed around
the element M. It was found also that the sintered product is
improved in plastic workability by such oxygen fixing around the
metal element M.
[0011] According to a first aspect of the present invention, there
is provided a sputter target material which is of a sintered
material, wherein the sputter target material consists of 0.5 to 50
atomic % in total of at least one metal element (M) selected from
the group of Ti, Zr, V, Nb and Cr, and the balance of Mo and
unavoidable impurities, and has a microstructure seen at a
perpendicular cross section to a sputtering surface, in which
microstructure oxide particles exist near a boundary of each island
of the metal element (M), and wherein the maximum area of the
island, which is defined by connecting the oxide particles with
linear lines so as to form a closed zone, is not more than 1.0
mm.sup.2. Preferably, the metal element (M) is Nb. The area of the
sputtering surface of the sputter target material is preferably not
less than 1 m.sup.2.
[0012] One embodiment of the sputter target material has a
rectangular sputtering surface each side length of which is
preferably not less than 1 m.
[0013] According to a second aspect of the present invention, there
is provided a method of producing a sputter target material, which
comprises the steps of:
[0014] blending raw powders of Mo and at least one metal element
(M) selected from the group consisting of Ti, Zr, V, Nb and Cr;
[0015] compressing the blended raw powders to form a green
compact;
[0016] pulverizing the green compact to produce a secondary powder
having an average particle size of not more than 5.0 mm;
[0017] filling the secondary powder into a pressurizing container;
and
[0018] sintering the secondary powder as contained in the
pressurizing container under pressure, whereby obtaining the
sputter target material,
[0019] wherein the sputter target has a microstructure seen at a
perpendicular cross section to a sputtering surface, in which
microstructure oxide particles exist near a boundary of each island
of the metal element (M), and wherein the maximum area of the
island, which is defined by connecting the oxide particles with
linear lines so as to form a closed zone, is not more than 1.0
mm.sup.2.
[0020] Preferably, the sintered material is subjected to plastic
working.
[0021] According to the invention Mo alloy sputter target material,
a component segregation in the Mo alloy sputter target material is
restrained, it is possible to improve the component uniformity of
thin films formed from the Mo alloy sputter target material by
sputtering, and the Mo alloy sputter target material has improved
plastic workability.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0022] FIG. 1 is a photograph taken by a scanning electron
microscope (SEM), which shows a sectional view of the
microstructure of an Mo--Cr alloy as an invention sputter target
material;
[0023] FIG. 2 is a schematic illustration of the microstructure
shown in FIG. 1;
[0024] FIG. 3 is a schematic illustration showing the sampling
positions of test pieces in the Example;
[0025] FIG. 4 is a photograph (magnification: 500 times) showing a
microstructure of Invention Specimen No. 4 of the sputter target
material, which was taken by an SEM;
[0026] FIG. 5 is a sketch of the Nb islands color-mapped with an
EPMA in the same field as FIG. 4;
[0027] FIG. 6 is a photograph (magnification: 1500 times) showing a
microstructure of Invention Specimen No. 14 of the sputter target
material in Example 2, which was taken by an SEM; and
[0028] FIG. 7 is a sketch of the Nb island color-mapped with an
EPMA in the same field as FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
[0029] A key aspect of the invention resides in finding the
microstructure of the Mo alloy sputter target material which
consists of 0.5 to 50 atomic % in total of at least one metal
element (M) selected from the group of Ti, Zr, V, Nb and Cr, and
the balance of Mo and unavoidable impurities, and which has a
restrained component segregation, wherein the sputter target
material has a microstructure seen at a perpendicular cross section
to a sputtering surface, in which microstructure oxide particles
exist near a boundary of each island of the metal element (M), and
wherein the maximum area of the island, which is defined by
connecting the oxide particles with linear lines so as to form a
closed zone, is not more than 1.0 mm. According to such a
microstructure, the Mo alloy sputter target material has improved
plastic workability.
[0030] Herein below there will be described details of the metal
structure and reasons why the defined feature of the invention is
preferred.
[0031] The invention sputter target material has a microstructure,
in which islands of the metal element M (e.g. Cr) are dispersed in
the Mo matrix, as can be seen in the microscopic photograph of a
sectional view of a Mo--Cr alloy shown in FIG. 1. Referring to FIG.
2 showing schematically the microstructure of FIG. 1, details
thereof will be described. In the invention sputter target
material, there are formed oxide particles 3 within and around each
island 2 of the metal element M in the Mo matrix 1. The island area
of the metal element M defined by connecting the oxide particles 3,
existing near a boundary of each island 2 of the metal element M
with linear lines so as to form a closed zone, as shown in FIG. 2,
means an area 4 surrounded by line segments connecting the centers
of the oxides 3 existing around each island of the metal element
M.
[0032] The at least one metal element M selected from the group
consisting of Ti, Zr, V, Nb and Cr is of a preferable additive to
the Mo alloy because the corrosion resistance property of Mo can be
improved by the additive. The respective metal element M is liable
to form an oxide(s) because of a lower energy level of oxide
formation than Mo. Therefore, when producing a Mo alloy target
material from a Mo powder and a powder of the metal element M by
the powder metallurgical method, oxygen (as a solute or a
precipitate including oxides) existing in the Mo matrix is fixed
around each island of the metal element(s) M as an oxide(s). It is
believed that the plastic workability of the Mo matrix itself is
improved by such a movement of oxygen from the Mo matrix, and that
the plastic workability of an entire sintered material is also
improved because of fine dispersion of islands of the metal(s) M of
which oxide(s) is fixed within or around the metal element(s)
M.
[0033] In the invention, it is desirable from the viewpoint of
restraining the segregation of components and the good plastic
workability to make the area of each island of the metal element(s)
M smaller, which area is defined by connecting oxide particles
existing near a boundary of each of the islands of the metal
element(s) M, observed in the sectional microstructure of the
target material with linear lines to form a closed zone. The
present inventors considered the optimal area size of the islands
of the metal element(s) M from the viewpoint of plastic workability
of the sputter target material and characteristics of thin films
formed from the sputter target material by sputtering, and
concluded that the area should be even at the largest not more than
1.0 mm.sup.2, preferably not more than 0.1 mm.sup.2.
[0034] The reason why the content of the metal element(s) M is set
to be 0.5 to 50 atomic % is that, if the lower limit were less than
0.5 atomic %, the effect of the metal element(s) M, which is of
oxygen absorption from Mo, becomes extremely small, and in the case
of the element(s) M content exceeding 50 atomic %, the inherent
characteristics of Mo is deprived.
[0035] Now, there will be described below a preferable method of
producing the invention sputter target material.
[0036] As stated above, the invention sputter target material is
characterized in that the element(s) M absorbs oxygen adhered on
particles of the Mo raw powder. Since the raw powder of the metal
element(s) M differ from Mo in powder characteristics including
specific gravity, shape and particle size, it is impossible to
realize a uniform dispersion of the powder blend by merely blending
the both powders. This means that a degree of dispersion uniformity
of the powder blend is important in the view point of making the
most of characteristics of the Mo alloy containing an additive
metal element(s) M.
[0037] With regard to blending the raw powders of Mo and the metal
element(s) M, in order to realize a uniform dispersion the metal
element(s) M, it is very important to rely on the process which
comprises blending raw powders of Mo and the metal element(s) M by
means of a usual blender such as a V-type blender or a cross rotary
mixer, compressing the powder blend, for example, by the cold
isostatic pressing method (CIP) to form a green compact, and
pulverizing the green compact to produce a secondary powder. This
is because, while the green compact produced by compressing (e.g.
the CIP method) has a component uniformity reflecting the state of
the raw powder blend, when pulverizing the green compact, the
compressed powder is separated and finely dispersed thereby
improving the component uniformity of the secondary powder. The
particle size of the secondary powder is also important in the view
point of a dispersion effect. If an average particle size of the
secondary powder exceeds 5 mm, the dispersion effect by
re-pulverizing is small. Therefore, the average particle size of
the secondary powder is preferably not more than 5 mm, more
preferably not more than 3 mm, and desirably not more than 1
mm.
[0038] The secondary powder is subjected to the following process
to obtain a target material having a desired size:
[0039] (1) the secondary powder is filled in a pressurizing
container;
[0040] (2) the pressurizing container is sealed after deaerating
the secondary powder therein;
[0041] (3) the filled powder is subjected to sintering under
pressure as contained in the container to obtain a sintered body;
and
[0042] (4) the sintered body is subjected to machining or plastic
working (e.g. hot rolling) to obtain the target material.
[0043] By the sintering method with use of the secondary powder, it
is possible to realize a uniform dispersion of components in the
secondary powder prior to sintering under pressure thereby enabling
the target material to have the metal element(s) M finely dispersed
in the Mo matrix, whereby enabling the area of each island of the
metal element(s) M in the Mo matrix to be not more than 1.0
mm.sup.2.
[0044] The metal elements M to be contained in the invention
sputter target material are preferably V, Nb and Cr, because, when
the sputter target material is used for forming of thin-film wiring
and thin-film electrodes in LCDs and so on, the thin-film can have
a low electric resistance and corrosion resistance property. Among
them, Nb is particularly preferable because of its low electrical
resistance. While additive Zr and Ti increase the electric
resistance of Mo as compared with V, Nb and Cr, since they are
considerably effective in improving the corrosion resistance
property, they are preferably used in forming a barrier film for a
primary conductive film in LCDs and so on.
[0045] Recently, in response to the trend toward larger size panels
of LCDs, the sputter target material used in the thin-film wiring
and the thin-film electrodes in LCDs is also required to have a
large sputtering surface area of not less than 1 m.sup.2 or each
side length of not less than 1 m.
[0046] In order to produce such a large area or a long size target
material, there is one idea of subjecting the sintered product to
plastic working. In view of this, since a sputter target material
having the invention metal structure has excellent plastic
workability and an excellent component uniformity at the sputtering
surface, it is highly suitable for producing those having not less
than 1 m.sup.2 of a sputtering surface or each side length of not
less than 1 m.
[0047] Also, preferably a sputter target material having the
invention metal structure has characteristics that, when an entire
length of the sputter target material is defined by the maximum
length of a longest linear line which can be drawn across the
sputtering surface, and when the sputter target material is
examined at each 50 mm length portion along the entire length, a
relative density is not less than 98% in every portion, and a
variation of content rates of the metal element(s) M is not more
than 20%. The variation of content rates of the metal element(s) M
means a difference between the maximum and the minimum content
rates of the metal element(s) M with regard to a nominal chemical
composition of the invention sputter target material. Specifically,
the variation can be evaluated by a value which is obtained by
dividing the maximum difference of the content rates of the metal
element(s) M, examined at each 50 mm length portion as mentioned
above, by a nominal content rate of the metal element(s) M in the
invention sputter target material. The reason why the variation of
content rates of the metal element(s) M is preferably set to be not
more than 20% is that the smaller the variation, the more uniformly
the metal element(s) M is dispersed whereby expectable to form a
deposition film with uniform film characteristics when sputtering.
If the variation exceeds 20%, the component variation of the metal
element(s) M among the examined 50 mm length portions as mentioned
above is larger, whereby occurring local differences in
concentration of the metal element(s) M in a deposition film formed
by sputtering resulting in a difference in film characteristics
thereby adversely affecting etching property of the film.
EXAMPLE 1
[0048] There were prepared a Mo powder having an average particle
size of 6 .mu.m, a Nb powder having an average particle size of 100
.mu.m, a Cr powder having an average particle size of 100 .mu.m, a
Ti powder having an average particle size of 100 .mu.m, a Zr powder
having an average particle size of 100 .mu.m, and a V (vanadium)
powder having an average particle size of 100 .mu.m.
[0049] Invention Specimen Nos. 1 to 6 target materials shown in
Table 1 were produced by the following process.
[0050] (1) In order to produce each of the specimens, given amounts
in atomic % of the Mo powder and any one of the additive element
powder were checkweighed.
[0051] (2) The checkweighed powders were blended for 10 minutes
with utilization of a V-type blender to obtain a raw material
powder.
[0052] (3) The raw material powder was compressed by a CIP machine
to form a green compact.
[0053] (4) The green compact was pulverized with utilization of a
jaw crusher and a disc mill to produce a secondary powder.
[0054] (5) The secondary powder was blended in a V-type blender for
10 minutes and subsequently filled into a pressurizing container
which is made of low carbon steel and has an inner space dimension
of a thickness of 100 mm, a width of 1250 mm and a height of 1450
mm. After filling the secondary powder into the pressurizing
container, a top lid with a deaerating port was welded to the
pressurizing container in order to close an inlet opening
thereof.
[0055] (6) The pressurizing container filled with the secondary
powder was subjected to a deaerating process under vacuum at a
temperature of 450.degree. C. and subsequently the deaerating port
was sealed.
[0056] (7) The secondary powder was sintered under pressure
together with the pressurizing container by means of a HIP machine.
Operational conditions of the HIP machine were of a temperature of
1250.degree. C., a pressure of 120 MPa and an operation time of 5
hours.
[0057] (8) The thus obtained sintered body was sliced and machined
to produce a sputter target material having a rectangular shape of
which dimension is of a thickness of 16 mm, a width of 980 mm and a
length of 1150 mm.
[0058] Comparative Specimen Nos. 7 and 8 target materials shown in
Table 1 were produced by the following process.
[0059] (1) In order to produce each of the specimens, given amounts
in atomic % of the Mo powder and the Nb powder were
checkweighed.
[0060] (2) The checkweighed powders were blended for 10 minutes
with utilization of a V-type blender to obtain a raw material
powder.
[0061] (3) The raw material powder was filled, without compression
working, into a pressurizing container which is made of low carbon
steel and has the same inner space dimension as mentioned above.
After filling the raw material powder into the pressurizing
container, a top lid with a deaerating port was welded to the
pressurizing container in order to close an inlet opening
thereof.
[0062] (4) The pressurizing container filled with the raw material
powder was subjected to a deaerating process under vacuum at a
temperature of 450.degree. C. and subsequently the deaerating port
was sealed.
[0063] (5) The filled powder was sintered under pressure together
with the pressurizing container by means of a HIP machine.
Operational conditions of the HIP machine were of a temperature of
1250.degree. C., a pressure of 120 MPa and an operation time of 5
hours.
[0064] (6) The thus obtained sintered body was sliced and machined
to produce a sputter target material having a rectangular shape of
which dimension is of a thickness of 16 mm, a width of 890 mm and a
length of 980 mm.
[0065] Test pieces were taken from each of the above specimens,
each of which has a section perpendicular to the sputtering
surface, the sectional surface having a size of 6.times.10 mm. The
test pieces were taken from five positions at the ends 7 of
diagonal lines and the center 8 of a sputter target material 5 as
shown in FIG. 3 which is a view of a sputtering surface 6. A
microstructure of the respective test piece was observed by means
of a scanning electro microscope (SEM).
[0066] With regard to the observation of the microstructure by
means of the SEM, observing the overall sputtering surface of the
respective test piece and selecting an island of the metal element
M having the maximum area which is defined by connecting the oxide
particles, existing near a boundary of the island of the metal
element M with linear lines so as to form a closed zone, the
selected island is determined as the representative island of the
metal element M of the pertinent test piece. A photograph was taken
of the microstructure around the representative island of the metal
element M in the respective test piece. With utilization of the
photograph, the area of the representative island of the metal
element M was determined by measuring the area of the above closed
zone and also by the image analysis method with utilization of a
binary image of the island. The maximum area value in the area
values of the five test pieces taken from the respective specimen
is shown in Table 1 as the representative value. Further, a
relative density of the respective specimen was determined by the
Archimedes method, which is shown in Table 1.
1 TABLE 1 Average particle size Average of raw material particle
Area of powder size of the Island of Chemical Metal secondary metal
Relative Specimen composition Mo element M powder (*1) element M
density No. (atomic %) (.mu.m) (.mu.m) (mm) (mm.sup.2) (%) Remarks
1 70Mo--30Ti 6 100 1.0 0.007 98.9 Invention Specimen 2
91.5Mo--8.4Zr 6 100 1.0 0.005 99.2 Invention Specimen 3
91.5Mo--8.4V 6 100 1.0 0.003 99.3 Invention specimen 4 95Mo--5Nb 6
100 1.0 0.002 99.6 Invention specimen 5 91.5Mo--1.5Nb 6 100 1.0
0.009 99.6 Invention specimen 6 95.5Mo--4.5Cr 6 100 1.0 0.005 99.4
Invention specimen 7 95Mo--5Nb 6 100 not prepared 3.15 99.5
Comparative (*2) specimen 8 99.8Mo--0.2Nb 6 100 not prepared 1.87
99.5 Comparative (*2) specimen *Note 1: The secondary powder was
produced by pulverizing a green compact of a raw material powder,
which green compact was produced by the CIP method. *Note 2: In
specimen Nos. 7 and 8, no secondary powder was prepared.
[0067] FIG. 4 shows a photograph (magnification: 500 times) of the
microstructure of Invention Specimen No. 4 sputter target material,
which was taken by an SEM (Scanning Electron Microscope). FIG. 5
shows a sketch of Nb islands color-mapped with utilization of an
Electron Probe Micro-Analyzer (EPMA) in the same field of view as
FIG. 4. From FIGS. 4 and 5, it can be confirmed that five Nb
islands exist in the center region of the drawings. Further, it can
be seen from FIG. 4 that there exist oxide particles, distinguished
by those black color, around the respective Nb island, and that the
maximum area of any one of the Nb islands is not more than 1.0
mm.sup.2, which maximum area is defined by connecting the oxide
particles, existing around the island of the metal element M with
linear lines so as to form a closed zone. It was also confirmed
from the EPMA color map that the black particles existing around
the Nb islands in FIG. 4 were of oxides.
[0068] As shown in Table 1, it is appreciated that with regard to
the sputter target materials of Invention Specimen Nos. 1 to 6, the
island area of the metal element M is not more than 1.0 mm.sup.2,
respectively, which area is defined by connecting the oxide
particles, existing near a boundary of the island of the metal
element M with linear lines so as to form a closed zone.
[0069] On the other hand, with regard to the sputter target
materials of Comparative Specimen Nos. 7 and 8, it was confirmed
that there is a difference in the distribution of the metal element
M from one region to another of the material, and that the island
area of the metal element M is more than 1.0 mm.sup.2,
respectively, which area is defined by connecting the oxide
particles, existing near a boundary of the island of the metal
element M with linear lines so as to form a closed zone.
EXAMPLE 2
[0070] Sintered bodies, having the same chemical compositions and
the same sizes as those produced in Example 1, respectively, were
produced by the same manner as the case of Example 1, and
subsequently subjected to hot rolling. The hot rolling after the
HIP process was carried out for the respective sintered body, as
contained in the pressurizing container without removing the
container from the sintered body, such that a working process of
heating up to a temperature of 1150.degree. C. and rolling under a
reduction ratio of not more than 50% was repeated five times. An
aimed rolling reduction ratio was 25%. After hot rolling, the
respective work was sliced and machined to obtain a sputter target
material having a rectangular form and a measurement of a thickness
of 10 mm, a width of 1130 mm and a length of 1200 mm. As in the
case of Example 1, five test pieces were taken from each of the
specimen sputtering target materials, each of which has a section
perpendicular to the sputtering surface, the sectional surface
having a size of 6.times.10 mm. A microstructure of the respective
test piece was observed by means of a scanning electro microscope
(SEM). An area value of an island of the metal element M was
measured with regard to the respective test piece, which area is
defined by connecting the oxide particles, existing around the
island of the metal element M with linear lines so as to form a
closed zone. The measurement area values are shown in Table 2.
Further, a relative density of the respective sputter target
material was determined by the Archimedes method, which is also
shown in Table 2. With regard to respective Comparative Specimen
Nos. 17 and 18, no sputter target material can be produced, since
cracks occurred on a peripheral surface of the sintered body during
hot rolling.
2 TABLE 2 Average particle size of raw Average particle Area of
material powder size of the Island of Chemical Metal secondary
powder metal Relative Specimen composition Mo element M (*1)
element M Hot density No. (atomic %) (.mu.m) (.mu.m) (mm)
(mm.sup.2) rolling (%) Remarks 11 70Mo--30Ti 6 100 1.0 0.006 Yes
99.1 Invention Specimen 12 91.5Mo--8.4Zr 6 100 1.0 0.003 Yes 99.3
Invention Specimen 13 91.5Mo--8.4V 6 100 1.0 0.005 Yes 99.5
Invention specimen 14 95Mo--5Nb 6 100 1.0 0.002 Yes 99.7 Invention
specimen 15 91.5Mo--1.5Nb 6 100 1.0 0.004 Yes 99.7 Invention
specimen 16 95.5Mo--4.5Cr 6 100 1.0 0.006 Yes 99.6 Invention
specimen 17 95Mo--5Nb 6 100 not prepared -- No -- Comparative (*2)
(cracks specimen occurred) 18 99.8Mo--0.2Nb 6 100 not prepared --
No -- Comparative (*2) (cracks specimen occurred) *Note 1: The
secondary powder was produced by pulverizing a green compact of a
raw-material powder, which green compact was produced by the CIP
method. *Note 2: In specimen Nos. 17 and 18, no secondary powder
was prepared.
[0071] FIG. 6 shows a photograph (magnification: 1500 times) of the
microstructure of Invention Specimen No. 14 sputter target
material, which was taken by an SEM (Scanning Electron Microscope).
FIG. 7 shows a sketch of Nb islands color-mapped with utilization
of an Electron Probe Micro-Analyzer (EPMA) in the same field of
view as FIG. 6. From FIGS. 6 and 7, it can be confirmed that a Nb
island exist in the center region of the drawings. Further, it can
be seen from FIG. 6 that there exist oxide particles, distinguished
by those black color, around the Nb island, and that the maximum
area of the Nb island is not more than 1.0 mm.sup.2, which maximum
area is defined by connecting the oxide particles, existing around
the island of the metal element M with linear lines so as to form a
closed zone. It was also confirmed from the EPMA color map that the
black particles existing around the Nb island in FIG. 6 were of
oxides.
[0072] As shown in Table 2, the respective Invention Specimen could
be rolled to provide a given form, of which maximum area of the Nb
island is not more than 1.0 mm.sup.2, the maximum area being
defined by connecting the oxide particles, existing near a boundary
of the island of the metal element M with linear lines so as to
form a closed zone. Further, Invention Specimen Nos. 11-16 have a
satisfactory relative density, respectively.
* * * * *