U.S. patent application number 10/540638 was filed with the patent office on 2006-02-23 for nickel alloy sputtering target.
This patent application is currently assigned to Nikko Materials Co., Ltd. Invention is credited to Yasuhiro Yamakoshi.
Application Number | 20060037680 10/540638 |
Document ID | / |
Family ID | 32708970 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060037680 |
Kind Code |
A1 |
Yamakoshi; Yasuhiro |
February 23, 2006 |
Nickel alloy sputtering target
Abstract
A nickel alloy sputtering target containing 0.5 to 10 at % of
tantalum in nickel, in which inevitable impurities excluding gas
components are 100 wtppm or less. Provided is a nickel alloy
sputtering target, and the manufacturing technology thereof,
enabling the formation of a thermally stable silicide (NiSi) film,
unlikely to cause the coagulation of films or excessive formation
of silicides, having few generation of particles upon forming the
sputtered film, having favorable uniformity and superior in the
plastic workability to the target, and which is particularly
effective for the manufacture of a gate electrode material (thin
film).
Inventors: |
Yamakoshi; Yasuhiro;
(Ibaraki, JP) |
Correspondence
Address: |
HOWSON AND HOWSON;ONE SPRING HOUSE CORPORATION CENTER
BOX 457
321 NORRISTOWN ROAD
SPRING HOUSE
PA
19477
US
|
Assignee: |
Nikko Materials Co., Ltd
10-1, Toranomon 2-chome Minato-ku
Tokyo
JP
105-8407
|
Family ID: |
32708970 |
Appl. No.: |
10/540638 |
Filed: |
October 6, 2003 |
PCT Filed: |
October 6, 2003 |
PCT NO: |
PCT/JP03/12777 |
371 Date: |
June 23, 2005 |
Current U.S.
Class: |
148/675 ;
420/441 |
Current CPC
Class: |
C23C 14/3414 20130101;
C22C 19/03 20130101 |
Class at
Publication: |
148/675 ;
420/441 |
International
Class: |
C22C 19/03 20060101
C22C019/03 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 10, 2003 |
JP |
2003-004685 |
Claims
1: A nickel-tantalum alloy sputtering target for gate electrode
material containing 0.5 to 10 at % of tantalum and residual
nickel.
2: A nickel-tantalum alloy sputtering target for gate electrode
material containing 1 to 5 at % of tantalum and residual
nickel.
3-10. (canceled)
11: A nickel-tantalum alloy sputtering target according to claim 1,
wherein inevitable impurities in the target, excluding gas
components, are 100 wtppm or less.
12: A nickel-tantalum alloy sputtering target according to claim 1,
wherein inevitable impurities in the target, excluding gas
components, are 10 wtppm or less.
13: A nickel-tantalum alloy sputtering target according to claim 1,
wherein oxygen content in the target is 50 wtppm or less, and
wherein nitrogen, hydrogen and carbon contents in the target are
each 10 wtppm or less.
14: A nickel-tantalum alloy sputtering target according to claim 1,
wherein oxygen content in the target is 10 wtppm or less.
15: A nickel-tantalum alloy sputtering target according to claim 1,
wherein an initial magnetic permeability of in-plane direction of
the target is 50 or more.
16: A nickel-tantalum alloy sputtering target according to claim 1,
wherein a maximum magnetic permeability on an initial magnetization
curve of in-plane direction of the target is 100 or more.
17: A nickel-tantalum alloy sputtering target according to claim 1,
wherein an average crystal grain size of the target is 80 .mu.m or
less.
18: A nickel-tantalum alloy sputtering target according to claim 2,
wherein inevitable impurities in the target, excluding gas
components, are 100 wtppm or less.
19: A nickel-tantalum alloy sputtering target according to claim 2,
wherein inevitable impurities in the target, excluding gas
components, are 10 wtppm or less.
20: A nickel-tantalum alloy sputtering target according to claim
19, wherein oxygen content in the target is 50 wtppm or less, and
wherein nitrogen, hydrogen and carbon contents in the target are
each 10 wtppm or less.
21: A nickel-tantalum alloy sputtering target according to claim
20, wherein oxygen content in the target is 10 wtppm or less.
22: A nickel-tantalum alloy sputtering target according to claim
21, wherein an initial magnetic permeability of in-plane direction
of the target is 50 or more.
23: A nickel-tantalum alloy sputtering target according to claim
22, wherein a maximum magnetic permeability on an initial
magnetization curve of in-plane direction of the target is 100 or
more.
24: A nickel-tantalum alloy sputtering target according to claim
23, wherein an average crystal grain size of the target is 80 .mu.m
or less.
25: A method of manufacturing a nickel-tantalum alloy sputtering
target, comprising the steps of producing a target containing 0.5
to 10 at % of tantalum and residual nickel, and subjecting the
target to a final heat treatment at a recrystallization temperature
of up to 950.degree. C.
26: A method according to claim 25, wherein said target is produced
containing 1 to 5 at % of tantalum and residual nickel.
27: A method according to claim 26, wherein inevitable impurities
in the target, excluding gas components, are 100 wtppm or less.
28: A method according to claim 27, wherein oxygen content in the
target is 50 wtppm or less, and wherein nitrogen, hydrogen and
carbon contents in the target are each 10 wtppm or less.
Description
TECHNICAL FIELD
[0001] The present invention relates to a nickel alloy sputtering
target enabling the formation of a thermally stable silicide (NiSi)
film, having favorable plastic workability to the target, and which
is particularly effective in the manufacture of a gate electrode
material (thin film), as well as to the manufacturing method
thereof.
BACKGROUND ART
[0002] In recent years, the use of NiSi film in the salicide
process as the gate electrode material is attracting attention.
Nickel, in comparison to cobalt, is characterized in that it is
capable of forming a silicide film with less consumption of silicon
during the salicide process. Further, NiSi, as with a cobalt
silicide film, is characterized in that the increase of fine wire
resistance pursuant to the miniaturization of wiring is unlikely to
occur.
[0003] In light of the above, nickel is being used instead of the
expensive cobalt as the gate electrode material.
[0004] Nevertheless, in the case of NiSi, it can easily make a
phase transition to the more stable NiSi.sub.2, and there is a
problem of the boundary roughness becoming aggravated and highly
resistive. Moreover, there are other problems in that the film is
easily coagulated and excessive formation of suicides may
occur.
[0005] Conventionally, as technology of using a nickel silicide
film or the like, there is technology of capping and annealing a
metal compound film such as TiN on a Ni or Co film to prevent the
formation of an insulation film by reacting with oxygen at the time
of forming the silicide film. Here, TiN is used in order to prevent
the formation of an irregular insulation film by the reaction of
oxygen and Ni.
[0006] When the irregularity is small, since the length from the
NiSi film to the connection of the source/drain diffusion layer
will be long, it is said that the connection leak can be
suppressed. In addition, TiC, TiW, TiB, WB.sub.2, WC, BN, AlN,
Mg.sub.3N.sub.2, CaN, Ge.sub.3N.sub.4, TaN, TbNi.sub.2, VB.sub.2,
VC, ZrN, ZrB and the like are also disclosed as the cap film (c.f.
Japanese Patent Laid-Open Publication No. H7-38104).
[0007] Further, with conventional technology, problems have been
indicated in that NiSi is easily oxidized even within the silicide
material, large irregularities are formed on the boundary area of
the NiSi film and Si substrate, and a connection leak will
occur.
[0008] Here, a proposal has been made for sputtering a TiN film on
the Ni film as a cap film, and subjecting this to heat treatment so
as to nitride the surface of the NiSi film. This aims to prevent
the NiSi from oxidizing, and suppress the formation of
irregularities.
[0009] Nevertheless, since the nitride film on the NiSi formed by
accumulating TiN on Ni is thin, there is a problem in that it is
difficult to maintain the barrier properties for a long period of
time.
[0010] Thus, a proposal has been made of forming the silicide film
under a mixed gas (2.5 to 10%) atmosphere with nitrogen gas added
thereto so as to make the roughness of the silicide film 40 nm or
less, and the grain size 200 nm or more. Here, it is desirable to
cap one among Ti, W, TiNx and WNx on Ni.
[0011] Here, it is also described that Ni may be sputtered with
argon gas only without containing nitrogen gas, subsequently
sputtering the cap film of TiN, and thereafter injecting N ion in
Ni film in order to add N in the Ni film (c.f. Japanese Patent
Laid-Open Publication No. H9-153616).
[0012] Further, as conventional technology, a semiconductor device
and the manufacturing method are disclosed, and the combination of
primary metals: Co, Ni, Pt or Pd and secondary metals: Ti, Zr, Hf,
V, Nb, Ta or Cr is described. In the Examples, the Co--Ti
combination is used.
[0013] Cobalt has a lower capability of reducing the silicon oxide
film in comparison to titanium, and the silicide reaction will be
inhibited if there is natural oxide film existing on the silicon
substrate or polysilicon film surface upon accumulating cobalt.
Further, the heat resistance properties are inferior to a titanium
silicide film, and problems have been indicated in that the heat
upon accumulating the silicon oxide film as the interlayer film
after the completion of the salicide process causes the coagulation
of the cobalt disilicide (CoSi.sub.2) film and the resistance to
increase (c.f. Japanese Patent Laid-Open Publication No. H11-204791
(U.S. Pat. No. 5,989,988)).
[0014] Further, as conventional technology, there is a disclosure
of a "manufacturing method of a semiconductor device", and
technology is described for where a layer of an amorphous alloy
with a metal selected from a group consisting of titanium Ti,
zirconium Zr, tantalum Ta, molybdenum Mo, niobium Nb, hafnium Hf,
and tungsten W is deposited on a surface as a layer containing
cobalt Co or nickel N in order to prevent the short-circuit caused
by the overgrowth upon forming salicide. Here, although there are
Examples that show a cobalt content of 50 to 75 at % and Ni40Zr60,
the alloy content is large for making an amorphous layer (c.f.
Japanese Patent Laid-Open Publication No. H5-94966).
[0015] As described above, all of the disclosed conventional
technology relate to the deposition process, and do not relate to a
sputtering target.
[0016] Further, with the conventional high purity nickel, the
purity was roughly up to 4N excluding gas components, and the
oxygen was high at roughly 100 ppm.
[0017] As a result of manufacturing a nickel alloy target based on
this kind of conventional nickel, plastic workability was inferior
and it was not possible to manufacture a high quality target. Also,
there was a problem in that numerous particles were generated
during sputtering, and the uniformity was inferior.
DISCLOSURE OF THE INVENTION
[0018] An object of the present invention is to provide a nickel
alloy sputtering target, and the manufacturing technology thereof,
enabling the formation of a thermally stable silicide (NiSi) film,
unlikely to cause the coagulation of films or excessive formation
of silicides, having few generation of particles upon forming the
sputtered film, having favorable uniformity and superior in the
plastic workability to the target, and which is particularly
effective for the manufacture of a gate electrode material (thin
film).
[0019] In order to achieve the foregoing object, the present
inventors discovered that a target enabling the formation of a
thermally stable silicide (NiSi) film, having few generation of
particles during sputtering, having favorable uniformity and
superior in plastic workability by adding specific metal elements
to high purity nickel.
[0020] Based on the foregoing discovery, the present invention
provides: [0021] 1. A nickel alloy sputtering target containing 0.5
to 10 at % of tantalum in nickel; [0022] 2. A nickel alloy
sputtering target containing 1 to 5 at % of tantalum in nickel;
[0023] 3. A nickel alloy sputtering target according to paragraph 1
or paragraph 2 above, wherein inevitable impurities excluding gas
components are 100 wtppm or less; [0024] 4. A nickel alloy
sputtering target according to paragraph 1 or paragraph 2 above,
wherein inevitable impurities excluding gas components are 10 wtppm
or less; [0025] 5. A nickel alloy sputtering target according to
any one of paragraphs 1 to 4 above, wherein oxygen is 50 wtppm or
less, and nitrogen, hydrogen and carbon are respectively 10 wtppm
or less; [0026] 6. A nickel alloy sputtering target according to
any one of paragraphs 1 to 5 above, wherein oxygen is 10 wtppm or
less; [0027] 7. A nickel alloy sputtering target according to any
one of paragraphs 1 to 6 above, wherein the initial magnetic
permeability of in-plane direction of the target is 50 or more;
[0028] 8. A nickel alloy sputtering target according to any one of
paragraphs 1 to 7 above, wherein the maximum magnetic permeability
on the initial magnetization curve of the in-plane direction of the
target is 100 or more; [0029] 9. A nickel alloy sputtering target
according to any one of paragraphs 1 to 8 above, wherein the
average crystal grain size of the target is 80 .mu.m or less; and
[0030] 10. A manufacturing method of a nickel alloy sputtering
target according to any one of paragraphs 1 to 9 above, wherein
final heat treatment is performed at a recrystallization
temperature of up to 950.degree. C.
BEST MODE FOR CARRYING OUT THE INVENTION
[0031] The target of the present invention is made to be a high
purity nickel alloy ingot by performing electrolytic refining to
rough Ni (up to roughly 4N), removing the metal impurity
components, and further refining this with EB melting in order to
obtain a high purity nickel ingot. Then, this ingot and high purity
tantalum are subject to vacuum melting to prepare a high purity
nickel alloy ingot.
[0032] Upon performing vacuum melting, the cold crucible melting
method employing a water-cooled copper crucible is suitable. This
alloy ingot is cast, rolled and subject to other processes to form
a plate shape, and ultimately subject to heat treatment at a
recrystallization temperature about 500.degree. C. to 950.degree.
C. to prepare a target. The analytical values of this
representative high purity nickel target are shown in Table 1.
TABLE-US-00001 TABLE 1 Element (wtppm) Element (wtppm) Li <0.001
Ag <0.01 Be <0.001 Cd <0.01 B 0.02 In <0.05 F <0.01
Sn 0.2 Na <0.01 Sb <0.01 Mg 0.57 Te <0.01 Al 0.14 I
<0.01 Si 2.7 Cs <0.01 P <0.01 Ba <0.005 S 0.02 La
<0.005 Cl <0.01 Ce <0.005 K <0.01 Pr <0.005 Ca
<0.01 Nd <0.005 Sc <0.001 Sm <0.005 Ti 0.24 Eu
<0.005 V 0.01 Gd <0.005 Cr 0.02 Tb <0.005 Mn 0.12 Dy
<0.005 Fe 1 Ho <0.005 Co 0.66 Er <0.005 Ni Matrix Tm
<0.005 Cu 0.13 Yb <0.005 Zn <0.01 Lu <0.005 Ga <0.01
Hf <0.01 Ge <0.05 Ta 10.01 As <0.01 W 0.02 Se <0.01 Re
<0.01 Br <0.05 Os <0.01 Rb <0.005 Ir <0.01 Sr
<0.005 Pt 0.07 Y <0.005 Au <0.01 Zr <0.01 Hg <0.01
Nb 0.2 Tl <0.01 Mo 0.03 Pb 0.04 Ru <0.01 Bi <0.005 Rh
<0.01 Th <0.0001 Pd <0.01 U <0.0001 H <10 C <10 N
<10 O <10 Note: Pursuant to GDMS analysis excluding H, C, N,
O and Ta Note: Ta is wt % Note: < means less than measuring
limit
[0033] The additive amount of tantalum is 0.5 to 10 at %, more
preferably 1 to 5 at %. If the additive amount is too small, the
thermal stability of the nickel alloy layer cannot be improved. If
the additive amount is too great, the film resistance will become
so large that it will be inappropriate, and there is a problem in
that the amount of intermetallic compounds will increase and make
the plastic processing difficult, and the generation of particles
during sputtering will also increase.
[0034] As a result of performing sputtering with the tantalum-added
nickel alloy of the present invention, heating this sputtered film
under a nitrogen atmosphere, and thereafter measuring the
temperature of change in the crystal structure with the XRD
diffraction method, the phase change temperature of 50 to
90.degree. C. improved due to the addition of tantalum, and
apparent thermal stability could be confirmed.
[0035] In order to reduce the generation of particles during
sputtering and to improve the uniformity, it is desirable to make
the inevitable impurities excluding gas components 100 wtppm or
less, and more preferably 10 wtppm or less.
[0036] Further, since gas components will also cause the increase
in the generation of particles, it is desirable to make the content
of oxygen 50 wtppm or less, more preferably 10 wtppm or less, and
the contents of nitrogen, hydrogen and carbon respectively 10 wtppm
or less.
[0037] It is important to make the initial magnetic permeability of
the target 50 or more (preferably around 100), and the maximum
magnetic permeability 100 or more with respect to the sputtering
characteristics.
[0038] Final heat treatment is performed at a recrystallization
temperature about 500.degree. C. to 950.degree. C. to form a
substantial recrystallization texture. If the heat treatment
temperature is less than 500.degree. C., sufficient
recrystallization texture cannot be obtained. Further, the
permeability and maximum magnetic permeability cannot be
improved.
[0039] In the target of the present invention, although the slight
existence of non-recrystallization will not affect the
characteristics, a significant amount of such existence is not
preferable. It is desirable that the average crystal grain size of
the target is 80 .mu.m or less.
[0040] A final heat treatment exceeding 950.degree. C. is not
preferable as this will enlarge the average crystal grain size.
When the average crystal grain size is enlarged, the variation of
the crystal grain size will increase, and the uniformity will
deteriorate.
EXAMPLES AND COMPARATIVE EXAMPLES
[0041] The present invention is now described with reference to the
Examples and Comparative 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.
Example 1-1 to Example 3-2
[0042] Rough Ni (up to roughly 4N) was subject to electrolytic
refining, metal impurity components were removed, this was further
refined with EB melting in order to obtain a high purity nickel
ingot, and this ingot and high purity tantalum were subject to
vacuum melting in order to manufacture a high purity nickel alloy
ingot. Upon performing vacuum melting, the cold crucible melting
method employing a water-cooled copper crucible was used.
[0043] This alloy ingot was cast, rolled and subject to other
processes to form a plate shape, and ultimately subject to heat
treatment at a recrystallization temperature about 500.degree. C.
to 950.degree. C. to prepare a target.
[0044] The manufacturing conditions of the target; namely, the Ta
amount, purity, oxygen content, and heat treatment temperature
conditions, as well as the characteristics of the target and
deposition; namely, the initial magnetic permeability, maximum
magnetic permeability, average crystal grain size, variation of the
crystal grain size, particle amount, and uniformity are shown in
Table 2.
[0045] As shown in Table 2, Example 1 series has a Ta amount of
1.68 at %, Example 2 series has a Ta amount of 3.48 at %, and
Example 3 series has a Ta amount of 7.50 at %. TABLE-US-00002 TABLE
2 Initial Maximum Heat Treatment Magnetic Magnetic Particles Ta
Volume Oxygen Conditions Permea- Permea- Average Grain Variation
(0.3 .mu.m or Uniformity (at %) Purity (wtppm) (.degree. C.)
.times. 1 hr bility bility Size (.mu.m) (%) more/in.sup.2) (%, 3
.sigma.) Example 1-1 1.68 5N 35 500 62 103 Non-recrystal- -- 23 8
lization Found Example 1-2 1.68 5N 25 600 103 142 Non-recrystal- --
18 11 lization Found Example 1-3 1.68 5N <10 650 121 165 17.3
9.6 15 7 Comparative 1.68 3N5 80 650 118 161 7.1 8.2 113 5 Example
1-1 Comparative 1.68 4N 75 650 115 167 8.5 7.6 103 3 Example 1-2
Comparative 1.68 5N <10 300 18 47 No Recrystal- -- 20 7 Example
1-3 lization Comparative 1.68 5N <10 450 23 63 Non-recrystal- --
18 18 Example 1-4 lization Found Comparative 1.68 5N <10 1000
141 189 244 57 15 14 Example 1-5 Example 2-1 3.48 5N <10 750 67
118 Non-recrystal- -- 17 11 lization Found Example 2-2 3.48 5N
<10 800 102 156 12.7 18 9 6 Example 2-3 3.48 5N <10 850 112
163 53.2 21 12 13 Example 2-4 3.48 5N <10 930 121 165 73.4 27 15
11 Comparative 3.48 3N5 <10 300 11 29 No Recrystal- -- 47 8
Example 2-1 lization Comparative 3.48 4N <10 650 16 59
Non-recrystal- -- 55 21 Example 2-2 lization Found Comparative 3.48
5N <10 1050 125 166 153 43 16 23 Example 2-3 Comparative 3.48 5N
<10 1150 124 172 146 51 19 27 Example 2-4 Example 3-1 7.50 5N
<10 900 67 123 46 11 37 15 Example 3-2 7.50 5N <10 950 75 131
68 19 42 13 Comparative 7.50 5N <10 600 13 41 Non-recrystal- --
43 26 Example 3-1 lization Found Comparative 7.50 5N <10 1250 81
135 213 33 51 21 Example 3-2
[0046] Examples 1-1 to 1-3, Examples 2-1 to 2-4 and Examples 3-1 to
3-2 in which the Ta amount, purity, oxygen content, and heat
treatment temperature conditions are within the scope of the
present invention had an initial magnetic permeability of 50 or
more, a maximum magnetic permeability of 100 or more, an average
crystal grain size of 80 .mu.m or less, the variation of the
crystal grain size was small, the particle amount (0.3 .mu.m or
more/in.sup.2) was also small, and the uniformity (%, 3 .sigma.)
was also a small value.
[0047] As a result of performing sputtering with the tantalum-added
nickel alloy of the present Examples, heating this sputtered film
under a nitrogen atmosphere, and thereafter measuring the
temperature of change in the crystal structure with the XRD
diffraction method, the phase change temperature of 50 to
90.degree. C. improved due to the addition of tantalum, and
apparent thermal stability could be confirmed.
[0048] Incidentally, since the heat treatment temperature was
slightly low in Example 1-1, Example 1-2 and Example 2-1, there
were some non-recrystallized textures, but since the existence
thereof was small, the characteristics were not affected.
Comparative Example 1-1 to 3-2
[0049] The manufacture process was the same as the foregoing
Examples, and the additive amount of Ta was also the same, but the
conditions of purity, oxygen content and heat treatment temperature
were changed as shown in Table 2 upon manufacturing the target. The
characteristics of the target and deposition; namely, the initial
magnetic permeability, maximum magnetic permeability, average
crystal grain size, variation of the crystal grain size, particle
amount, and uniformity were measured and observed.
[0050] Incidentally, as with the Examples, Comparative Example 1
series has a Ta amount of 1.68 at %, Comparative Example 2 series
has a Ta amount of 3.48 at %, and Comparative Example 3 series has
a Ta amount of 7.50 at %.
[0051] As a result, Comparative Examples 1-1 and 1-2 has
significant amounts of oxygen, and, since the purity is low, there
was a problem in that many particles were generated. Since the heat
treatment temperature is too low in Comparative Examples 1-3 and
1-4, the initial magnetic permeability and maximum magnetic
permeability could not be improved, and this could not be
recrystallized, or large amounts of non-recrystallized textures
existed.
[0052] Since the final heat treatment temperature was too high in
Comparative Example 1-5, the average crystal grain size enlarged,
the variation increased, and the uniformity deteriorated.
[0053] Since the purity was low and the heat treatment temperature
was too low in Comparative Example 2-1 and Comparative Example 2-2,
the initial magnetic permeability and maximum magnetic permeability
could not be improved, and this could not be recrystallized, or
large amounts of non-recrystallized textures existed. Numerous
particles were also generated.
[0054] Since the final heat treatment temperature was too high in
Comparative Examples 2-3 and 2-4, the average crystal grain size
enlarged, the variation increased, and the uniformity
deteriorated.
[0055] Since the heat treatment temperature was low in Comparative
Example 3-1, the initial magnetic permeability and maximum magnetic
permeability could not be improved. Large amounts of
non-recrystallized textures existed, and numerous particles were
also generated.
[0056] Since the final heat treatment temperature was too high in
Comparative Example 3-2, the average crystal grain size enlarged,
the variation increased, and the uniformity deteriorated.
Effect of the Invention
[0057] As described above, a nickel alloy sputtering target
containing a prescribed amount of tantalum in nickel yields a
superior effect in that it enables the formation of a thermally
stable silicide (NiSi) film, is unlikely to cause the coagulation
of films or excessive formation of suicides, has few generation of
particles upon forming the sputtered film, has favorable uniformity
and is superior in the plastic workability to the target, and is
particularly effective for the manufacture of a gate electrode
material (thin film).
* * * * *