KR101991150B1

KR101991150B1 - Cobalt sputtering target and production method therefor

Info

Publication number: KR101991150B1
Application number: KR1020157029694A
Authority: KR
Inventors: 겐타로 하라다; 가즈시게 다카하시
Original assignee: 제이엑스금속주식회사
Priority date: 2013-03-27
Filing date: 2014-03-25
Publication date: 2019-06-19
Also published as: KR20150130552A; TWI600783B; TW201447001A; KR20170095410A; JPWO2014157187A1; JP6084683B2; WO2014157187A1; SG11201506950WA

Abstract

The purity is 99.99% or more, the in-plane permeability in the sputter plane is 5 or more and 10 or less, and the standard deviation of the in-plane magnetic permeability in the sputter plane is 3 or less. The permeability in the direction parallel to the sputter surface is lowered and the permeability in the perpendicular direction with respect to the sputter surface is increased to improve the sputter efficiency and the unevenness of the in-plane permeability in the sputter surface is suppressed to improve the uniformity of the film A cobalt sputtering target and a method of manufacturing the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cobalt sputtering target,

An object of the present invention is to reduce the permeability in a direction parallel to a sputter surface and increase the permeability in a direction perpendicular to the sputter surface to improve the sputter efficiency and to improve the permeability of the sputter surface in the in- To a cobalt sputtering target capable of improving the uniformity of a film formed by suppressing a deviation, and a method of manufacturing the same.

The sputtering method is a well-known technique as a means for forming a thin film. The basic principle is that a voltage is applied between a substrate (anode side) on which a thin film is formed and a target (cathode side) composed of a thin film forming material opposed thereto with a slight distance therebetween in a lean gas such as argon, Argon gas is plasmaized, argon ions in a plasma generated thereon collide with a target, which is a cathode material, and the energy of the target causes the target material to fly out to the outside, To form a thin film.

The thin film formed by sputtering a cobalt target is used as an electrode or wiring of a VLSI. Particularly, since cobalt of high purity is required for such cobalt, cobalt having a purity of 99.99 wt% or more is used. In general, when a cobalt target is sputtered, a magnetron sputtering method is used.

The cobalt target is produced by dissolving and casting refined cobalt in a high purity and then subjecting the ingot to hot working (forging, hot rolling) at a high temperature and then subjecting the ingot to a warm treatment, a cold working, a low temperature treatment, After the machining, the target is finished by the final machining. However, since cobalt is a ferromagnetic material and has a strong magnetic anisotropy due to a crystal structure or texture of the processed structure, there is a problem that it is difficult to form a uniform film even by using the magnetron sputtering method as described above.

In addition, when cobalt is hot-worked and then processed into a plate-shaped target, the magnetic permeability in the direction parallel to the target surface is high and conversely, the magnetic permeability in the direction perpendicular to the sputter surface is significantly reduced. In such a case, since the leakage magnetic flux in the direction perpendicular to the sputtering plane is reduced, the sputtering efficiency is remarkably deteriorated. In some cases, sputtering becomes difficult and deposition becomes impossible. This is strongly influenced by the crystal structure of cobalt. The hot-rolled target is a face-centered cubic grating (FCC). When the target is highly remained, the surface of the target is strongly oriented on the (100) plane, This is a cause of remarkably reducing the permeability in the perpendicular direction.

In the manufacturing process of the cobalt target, the texture of the face-centered cubic lattice (FCC) produced by the hot working is transformed into the processed martensite to form a dense hexagonal lattice (HCP), and the (002) face of the cobalt By strongly orienting, it is possible to increase the permeability in the perpendicular direction to the sputter surface. In the past, various studies have been made on the production of cobalt targets in such knowledge.

For example, Patent Document 1 discloses a method in which a cobalt ingot is produced by hot forging and hot rolling, cold rolling in biaxial directions and heat treatment at 420 to 600 占 폚 are repeated, It is described that the deviation of the magnetic flux is made within ± 5%. This is intended to reduce the abrupt erosion of the target and to equalize the film thickness of the film. Further, in Patent Document 2, it is proposed to lower the blank of the target at a cryogenic temperature at a temperature of -50 占 폚 or less in order to achieve uniformity of PTFE of nickel or cobalt target of 99.99 wt%.

In Patent Document 3, the cobalt ingot is subjected to hot working at 1050 to 1250 占 폚, followed by hot working at 380 to 415 占 폚, and if necessary, heat treatment at the same temperature (375 to 422 占 폚) (002) plane of cobalt is strongly oriented on the sputtering surface by transforming the texture of the face-centered cubic lattice (FCC) into a processed hexagonal lattice (HCP) by processing the organic martensite to increase the permeability in the vertical direction with respect to the sputter face Has been proposed.

In Patent Document 4, cobalt is cast and then hot worked at 1000 占 폚 to give 65% deformation. Next, this is cooled to room temperature at a low speed of 15 占 폚 / minute or less, 20% cold working to produce a low permeability cobalt sputtering target. It is also disclosed in Patent Document 5 that the hot forming treatment is carried out in a temperature range of 750 to 900 占 폚 and then the cold forming treatment is carried out at a temperature of 300 to 422 占 폚 in producing a high purity cobalt sputtering target .

In Patent Document 6, a high-purity cobalt ingot is hot-worked at 1100 to 1200 ° C and then subjected to cold working as required, followed by tempering at 450 ° C or less (more specifically, at temperatures of 400 ° C and 450 ° C) Thereby lowering the permeability in the direction parallel to the sputter face to 12 or less and setting the permeability in the direction perpendicular to the sputter face to 36 or more. In this patent document 6, it is disclosed that the thickness of the target can be set to a thickness of 3.0 mm or more, and furthermore, a thickness of 6.36 mm to more than a conventional one.

In the above-described conventional technique, although it is disclosed that the permeability in a direction parallel to the sputter surface (hereinafter referred to as " in-plane permeability ") is lowered and the permeability in the perpendicular direction to the sputter surface is increased, There is a problem in that the stability is insufficient. In addition, the production process is complicated, and the productivity is also inferior. Patent Document 6 is produced by the present applicant (changed from JX J. Nikkonisseki Kinzoku Co., Ltd. under the name of JX ENERGY CO., LTD.), And is effective in many respects. However, the specific example of the temperature condition at the time of warm- , With some drawbacks. The present invention further improves these.

Japanese Patent Application Laid-Open No. 2007-297679 Japanese Patent Publication No. 2005-528525 Japanese Patent Application Laid-Open No. 2003-306751 Japanese Laid-Open Patent Publication No. 2001-200356 Japanese Patent Application Laid-Open No. 2001-514325 Japanese Patent Application Laid-Open No. 9-272970

The present invention reduces the permeability in a direction parallel to the sputter surface (hereinafter referred to as " in-plane permeability " if necessary) and improves the sputter efficiency by increasing the permeability in the perpendicular direction to the sputter surface, It is another object of the present invention to provide a cobalt sputtering target capable of improving the uniformity of a film formed by suppressing the variation of the in-plane magnetic permeability in the sputter face, and a manufacturing method thereof.

In view of the above problems, the present invention provides the following.

1) A cobalt sputtering target characterized in that the purity is 99.99% or more, the in-plane permeability in the sputter face is 5 or more and 10 or less, and the variation of the in-plane permeability in the sputter face is 3 or less.

2) The maximum value of the X-ray diffraction peak intensity ratio {I ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ And the cobalt sputtering target according to the above 1).

3) Cobalt having a purity of 99.99% or more is melted and cast to obtain an ingot. The ingot is heated in a furnace in which the temperature distribution in the furnace is maintained at a temperature within a range of 1000 ° C. to 1200 ° C. and within a temperature range of ± 10 ° C., Forged or hot rolled, and then heated in a furnace in which the temperature distribution in the furnace is kept constant within a temperature range of 300 ° C or more and 400 ° C or less within ± 10 ° C, followed by warm rolling, Wherein the cobalt sputtering target is a cobalt sputtering target.

The present invention reduces the "in-plane magnetic permeability" of the sputter surface and increases the permeability in the perpendicular direction to the sputter surface to improve the sputter efficiency and suppress the variation of the in-plane magnetic permeability within the sputter surface, Can be improved.

1 is a view for explaining sampling positions for examining characteristics of a target.

The present invention is particularly effective for a cobalt sputtering target having a purity of 99.99% or more. It goes without saying that cobalt having a purity of 99.99% or more is preferable, though it can be applied at a purity of less than that, although fluctuations are caused by affecting the permeability when the impurities increase.

In order to lower the in-plane magnetic permeability in the target manufacturing process, hot rolling (cold forging or rolling) is performed as shown in the above-mentioned conventional techniques, followed by warm rolling or cold rolling and, if necessary, heat treatment. In this case, however, the permeability changes very sensitively depending on the processing temperature and the temperature of the heat treatment, so strict adjustment is necessary.

Cobalt has a texture of a face-centered cubic (FCC) structure at 422 ° C or higher, and a structure of a dense hexagonal lattice (HCP) structure at a temperature below 422 ° C. Therefore, it is difficult to lower the in-plane magnetic permeability by expressing the texture of the (002) plane of the dense hexagonal lattice (HCP) structure of cobalt at the warm rolling above this temperature.

In this respect, the cobalt sputtering target of the present invention is obtained by first dissolving and casting cobalt having a purity of 99.99% or more and casting it as an ingot. The temperature is in the range of 1000 ° C. to 1200 ° C., And then heated or hot-rolled in a furnace in which the temperature distribution in the furnace is maintained at a temperature within a range from 300 DEG C to 400 DEG C and within a temperature range of +/- 10 DEG C Followed by warm rolling. And has a structure of a face-centered cubic (FCC) structure in the state of hot forging or hot-rolling at a temperature of 1000 ° C or more and 1200 ° C or less.

This is further subjected to warm rolling at a temperature of 300 DEG C or more and 400 DEG C or less to transform the processed organic martensite into a dense hexagonal lattice (HCP). Then, this is further processed by machining. This makes it possible to set the permeability (in-plane permeability) in the direction parallel to the sputter face to 5 or more and 10 or less.

The permeability is greatly influenced by the heating temperature during processing, and if there is a temperature variation at that time, the permeability greatly fluctuates within the sputter plane. Therefore, it is particularly important to strictly control the temperature distribution in the furnace during heating before hot or warm rolling to within 占 0 ° C. This makes it possible to reduce the deviation (standard deviation) of the in-plane magnetic permeability in the sputter surface of the cobalt target. In addition, by adjusting the roll gap of the rolling mill to be ± 2 mm or less, the uniformity of the in-plane magnetic permeability can be increased.

The cobalt sputtering target of the present invention can strictly control the permeability by specifying the crystal orientation of the sputter surface. That is, by setting the maximum value of the X-ray diffraction peak intensity ratio {I ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I _{(004) in the} sputter plane to 1 or less, It is possible to stably provide a target with a low investment ratio. In addition, the X-ray diffraction peak intensity of the face _{(100) I (100),} (110) an X-ray diffraction peak intensity of the plane _{I (110), (200)} X -ray I ₍₂₀₀₎ diffraction peak intensity of the face, The X-ray diffraction peak intensity of the (002) plane is I ₍₀₀₂₎ , and the X-ray diffraction peak intensity of the (004) plane is I ₍₀₀₄₎ .

Example

Next, specific examples (experimental examples) will be described. In this case, an example of comparison is also shown. This embodiment is an example in which the present invention is carried out under specific conditions in order to facilitate understanding, though it is within the range defined by the present invention. Therefore, it is needless to say that the invention is not limited to the following examples, and modifications based on the technical idea of the present invention are possible. The present invention includes all of these.

(Example 1)

The cobalt used in this test is electron beam dissolved cobalt having a purity of 99.998%. The molten ingot was hot-rolled at 1100 ° C from 26.8 t to 11.7 t. It was also warm-rolled at 400 ° C to 6 t. Then, the rolled cobalt plate material was machined into a sputtering shape to produce a cobalt sputtering target.

With respect to the cobalt sputtering target produced as described above, the permeability in the parallel direction to the rolled surface (that is, the surface to be the sputter surface) was measured at nine points in the plane as shown in Fig. The results are shown in Table 1. As shown in Table 1, the average in-plane permeability was 8.9 and the standard deviation of permeability was 1.6. The permeability was measured using a sample of 5 mm x 5 mm x 20 mm for each point.

(100) plane, (110) plane, (200) plane, (002) plane and (004) plane at nine points in the plane shown in Fig. 1, ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ } was calculated by measuring the X-ray diffraction intensity of the surface. As a result, as shown in Table 1, the average value was 0.24 and the maximum value was 0.35. The conditions of the X-ray diffraction apparatus were as follows.

Sailor: CuKα

Tube voltage: 40 kV

Tube current: 40 ㎃

Scattering slit: 0.63 mm

Receiving slit: 0.15 mm

The cobalt sputtering target was solid-phase bonded to the backing plate, inserted into the sputter chamber, and sputtered in an argon gas atmosphere to form a cobalt film on the substrate. Then, the film thickness was measured at 49 points in the plane on the substrate. As a result, the uniformity (standard deviation / average value x 100) of the film thickness was 1.16%.

(Example 2)

The cobalt used in this test is electron beam dissolved cobalt having a purity of 99.998%. The molten ingot was hot-rolled at 1100 ° C from 26.8 t to 11.7 t. It was also warm-rolled at 350 ° C to 6 t. Then, the rolled cobalt plate material was machined into a sputtering shape to produce a cobalt sputtering target.

With respect to the cobalt sputtering target produced as described above, the permeability in the parallel direction to the rolled surface (that is, the surface to be the sputter surface) was measured at nine points in the plane as shown in Fig. The results are shown in Table 1. As shown in Table 1, the average in-plane permeability was 6.8 and the standard deviation of permeability was 2.1.

(100) plane, (110) plane, (200) plane, (002) plane and (004) plane at nine points in the plane shown in Fig. 1, ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ } was calculated by measuring the X-ray diffraction intensity of the surface. As a result, as shown in Table 1, the average value was 0.32 and the maximum value was 0.42.

The cobalt sputtering target was solid-phase bonded to the backing plate, inserted into the sputter chamber, and sputtered in an argon gas atmosphere to form a cobalt film on the substrate. Then, the film thickness was measured at 49 points in the plane on the substrate. As a result, the uniformity (standard deviation / average value x 100) of the film thickness was 1.18%.

(Example 3)

The cobalt used in this test is electron beam dissolved cobalt having a purity of 99.998%. The molten ingot was hot-rolled at 1100 ° C from 26.8 t to 11.7 t. It was also warm-rolled at 310 DEG C to 6 t. Then, the rolled cobalt plate material was machined into a sputtering shape to produce a cobalt sputtering target.

With respect to the cobalt sputtering target produced as described above, the permeability in the parallel direction to the rolled surface (that is, the surface to be the sputter surface) was measured at nine points in the plane as shown in Fig. The results are shown in Table 1. As shown in Table 1, the average of the in-plane magnetic permeability was 5.4 and the standard deviation of the magnetic permeability was 2.9.

(100) plane, (110) plane, (200) plane, (002) plane and (004) plane at nine points in the plane shown in Fig. 1, ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ } was calculated by measuring the X-ray diffraction intensity of the surface. As a result, as shown in Table 1, the average value was 0.65 and the maximum value was 0.48.

The cobalt sputtering target was solid-phase bonded to the backing plate, inserted into the sputter chamber, and sputtered in an argon gas atmosphere to form a cobalt film on the substrate. Then, the film thickness was measured at 49 points in the plane on the substrate. As a result, the uniformity (standard deviation / average value x 100) of the film thickness was 1.21%.

(Comparative Example 1)

The cobalt used in this test is electron beam dissolved cobalt having a purity of 99.998%. The molten ingot was hot-rolled at 1100 ° C from 26.8 t to 11.7 t. It was also warm-rolled at 290 ° C until 6 t. Then, the rolled cobalt plate material was machined into a sputtering shape to produce a cobalt sputtering target.

With respect to the cobalt sputtering target produced as described above, the permeability in the parallel direction to the rolled surface (that is, the surface to be the sputter surface) was measured at nine points in the plane as shown in Fig. The results are shown in Table 1. As shown in Table 1, the average of the in-plane magnetic permeability was 4.3 and the standard deviation of the magnetic permeability was 4.2.

(100) plane, (110) plane, (200) plane, (002) plane and (004) plane at nine points in the plane shown in Fig. 1, ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ } was calculated by measuring the X-ray diffraction intensity of the surface. As a result, as shown in Table 1, the average value was 0.89 and the maximum value was 1.35.

The cobalt sputtering target was solid-phase bonded to the backing plate, inserted into the sputter chamber, and sputtered in an argon gas atmosphere to form a cobalt film on the substrate. Then, the film thickness was measured at 49 points in the plane on the substrate. As a result, the uniformity (standard deviation / average value x 100) of the film thickness was 2.52%.

(Comparative Example 2)

The cobalt used in this test is electron beam dissolved cobalt having a purity of 99.998%. The molten ingot was hot-rolled at 1100 ° C from 26.8 t to 11.7 t. It was also warm-rolled at 350 ° C to 6 t. However, since the temperature control in the rolling furnace was not strictly carried out, the temperature distribution in the furnace at the time of heating before the hot rolling and the warm rolling was respectively ± 20 ° C and ± 10 ° C. Then, the rolled cobalt plate material was machined into a sputtering shape to produce a cobalt sputtering target.

With respect to the cobalt sputtering target produced as described above, the permeability in the parallel direction to the rolled surface (that is, the surface to be the sputter surface) was measured at nine points in the plane as shown in Fig. The results are shown in Table 1. As shown in Table 1, the average in-plane permeability was 6.4 and the standard deviation of permeability was 4.5.

(100) plane, (110) plane, (200) plane, (002) plane and (004) plane at nine points in the plane shown in Fig. 1, ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ } was calculated by measuring the X-ray diffraction intensity of the surface. As a result, as shown in Table 1, the average value was 0.33 and the maximum value was 1.41.

The cobalt sputtering target was solid-phase bonded to the backing plate, inserted into the sputter chamber, and sputtered in an argon gas atmosphere to form a cobalt film on the substrate. Then, the film thickness was measured at 49 points in the plane on the substrate. As a result, the uniformity (standard deviation / average value x 100) of the film thickness was 2.87%.

Industrial availability

The in-plane magnetic permeability of the sputter face is increased, the permeability in the direction perpendicular to the sputter face is increased to improve the sputter efficiency, and the unevenness of the in-plane magnetic permeability in the sputter face is suppressed, Therefore, it is useful as a cobalt sputtering target for forming an electrode of VLSI or a wiring film.

Claims

In purity greater than 99%, the sputtering in-plane permeability in the plane is 5 or more 10 or less, and the standard deviation of the in-plane magnetic permeability is less than 3 in in the sputter face, the sputter X-ray diffraction peak intensity ratio {I in the plane _{( 100)} + I ₍₁₁₀₎ + I ₍₂₀₀₎ } / {I ₍₀₀₂₎ + I ₍₀₀₄₎ is 1 or less.

delete

Cobalt having a purity of 99.99% or more is melted and cast to obtain an ingot. The ingot is heated in a furnace in which the temperature distribution in the furnace is maintained at a temperature within the range of 1000 占 폚 to 1200 占 폚 and the temperature distribution in the furnace is kept constant within 占 0 占 폚, Rolled and then heated in a furnace maintained at a temperature range of 300 ° C to 400 ° C and a temperature distribution in the furnace kept constant within ± 10 ° C, followed by hot rolling, and further machined Wherein the cobalt sputtering target is a cobalt sputtering target.