TWI512113B - An alloy for a seed layer of a magnetic recording medium, and a sputtering target - Google Patents

Description

Alloy for seed layer of magnetic recording medium and sputtering target [Reciprocal reference of related applications]

The present invention claims the priority of Japanese Patent Application No. 2010-259713, filed on Nov. 22, 2010, and Japanese Patent Application No. 2011-94594, filed on Apr. 21, 2011. The description of the invention is incorporated by reference.

The present invention relates to a seed layer alloy and a sputtering target for a Ni-Fe-Co-based magnetic recording medium used as a seed layer in a perpendicular magnetic recording medium.

In recent years, magnetic recording media have progressed toward high recording densities due to significant advances in perpendicular magnetic recording and a large capacity of a drive. For example, a vertical recording method in which a high recording density can be further realized by an in-plane magnetic recording medium which has been widely used in the past has been put into practical use. Here, the perpendicular magnetic recording method means a method in which the easy magnetization axis is formed in a vertical direction with respect to a medium surface in a magnetic film of a perpendicular magnetic recording medium, and is suitable for a method of high-density recording.

In the perpendicular magnetic recording method, a recording medium having a magnetic recording film layer and a soft magnetic film layer having an improved recording density has been developed. In such a media structure, a film between a soft magnetic layer and a magnetic recording layer has been developed. Recording medium of the seed layer or the underlying film layer. A Ni-W-based alloy as disclosed in Japanese Laid-Open Patent Publication No. 2009-155722 (Patent Document 1) is proposed.

The Ni-W alloy described in Patent Document 1 is not added with a magnetic Group VIII, but is added with a non-magnetic element of Group IVa (Ti, Zr, Hf), Group Va (V, Nb, Ta), and Group VIa. (Cr, Mo, W), Group VIIa (Mn, Tc, Re), Group IIIb (B, Al, Ga, In, Tl), Group IVb (C, Si, Ge, Sn, Pb), resulting in non-magnetic . Here, one of the characteristics required for the seed layer, as the name suggests, is to control the orientation of the layer formed on the seed layer so that the easy magnetization axis of the magnetic film recording the magnetic information is oriented perpendicularly to the media surface, The seed layer itself has a separate fcc configuration, and the face parallel to the media face is oriented at the (111) face. Further, in order to increase the recording density, it is necessary to make the crystal grain size of the magnetic film as small as possible, and therefore it is desirable to have a smaller crystal grain size than the seed layer.

On the other hand, in recent years, as a method of improving the magnetic recording characteristics of a hard disk drive, a method of making the seed layer magnetic is discussed. However, as described above, the alloy for seed layer described in Patent Document 1 is non-magnetic, and it cannot be said as an alloy suitable for a seed layer having magnetic properties. Therefore, it has been demanded to develop an alloy for a seed layer having the properties required for the alloy for a seed layer as described above and having magnetic properties. Moreover, as for the large difference between the soft magnetic layer and the seed layer, an amorphous type which is useful for reducing noise is required in the soft magnetic layer, but the seed layer requires the effect of controlling the orientation of the layer formed on the seed layer, and requires It has high crystallinity opposite to amorphous amorphous type.

The present inventors have now found that the seed layer is made magnetic by adding Fe or Co having a magnetic Group VIII element, and the magnetic permeability can be improved by lowering the coercivity in the (111) plane direction.

Accordingly, an object of the present invention is to provide an alloy for a seed layer of a magnetic recording medium which has magnetic properties on a Ni-based intermediate layer over a soft magnetic underlayer film (SUL) and which can improve magnetic permeability, and a sputtering target using the same .

According to the same aspect of the present invention, there is provided an alloy which is an alloy for a seed layer of a magnetic recording medium, which comprises one or more selected from the group consisting of W, Mo, Ta, Cr, V and Nb. The M1 element accounts for 2 to 20 at% of the foregoing alloy, and one or two selected from the group consisting of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru The above M2 elements account for 0~10 at% of the above alloy, and the rest are Ni, Fe and Co, and are Ni:Fe:Co=98~20 with respect to at% of the total amount of Ni+Fe+Co: 0~50: 0~60 and the ratio of Fe+Co≧1.5.

According to another aspect of the present invention, there is provided an alloy which is an alloy for a seed layer of a magnetic recording medium, which comprises one or more selected from the group consisting of W, Mo, Ta, Cr, V and Nb. The element accounts for 2 to 20 at% of the foregoing alloy, and one or two selected from the group consisting of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru The above M2 element accounts for 0~10 at% of the above alloy, and the rest are Ni, Fe and Co, and is Ni:Fe:Co=98~20:2 with respect to at% of the total amount of Ni+Fe+Co. ~50:0~60 ratio.

According to another aspect of the present invention, there is provided a sputtering target which is composed of the above alloy.

According to another aspect of the present invention, a magnetic recording medium comprising a seed layer made of the above alloy is provided.

The invention is specifically described below. Unless otherwise stated, "%" in this specification means at%.

The seed layer of the magnetic recording medium of the present invention is made of an alloy containing one or more kinds of M1 elements selected from the group consisting of W, Mo, Ta, Cr, V and Nb, which accounts for 2 to 20 at% of the alloy. One or more kinds of M2 elements selected from the group consisting of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru account for 0 to 10 of the alloy. At%, the balance being at least two of Ni, Fe and Co, preferably consisting essentially of the elements and the unavoidable impurities, more preferably consisting of the elements and the unavoidable impurities (consisting of) . However, the respective amounts of Ni, Fe, and Co are (i) Ni:Fe:Co=98~20:0~50:0-60 and Fe+Co with respect to at% of the total amount of Ni+Fe+Co. The ratio of ≧1.5, or (ii) the ratio of Ni:Fe:Co=98~20:2~50:0~60.

In the alloy of the present invention, when the ratio of Ni, Fe and Co is represented by Ni:Fe:Co=α:β:γ, the atomic ratio α of Ni is 98 (more stringently 98.5) to 20, preferably 98 (more). Strictly 98.5)~60. When α exceeds 98.5, β+γ becomes less than 1.5 and the coercive force becomes high. When α is less than 20, the coercive force is also increased as described above.

Fe is an element which lowers the coercive force and is also an element which improves the film orientation. When Ni:Fe:Co=α:β:γ, the atomic ratio of Fe is 0 to 50, preferably 2~. 50%, better 10~40. When β exceeds 50, the coercive force becomes high.

Co is an element which reduces the coercive force in the (111) direction. When Ni:Fe:Co=α:β:γ, the atomic ratio γ of Co is 0 to 60, preferably 40 or less. When γ exceeds 60, the coercive force becomes high.

The alloy of the present invention contains 2 to 20 at%, preferably 5 to 15 at% of the total of one or more M1 elements selected from the group consisting of W, Mo, Ta, Cr, V and Nb. The M1 element is a bcc-based metal having a high melting point, and is added to the fcc alloy system by the range of the components specified in the present invention. Although the mechanism is not clear, the desired (111) surface of the seed layer can be improved. An element that is oriented and refines crystal grains. Therefore, when the amount of the M1 element is less than 2%, the effect is insufficient, and when it exceeds 20%, the compound is precipitated or amorphous. Since the alloy for the seed layer is required to be fcc single phase, the range of the amount of the M1 element is set as described above.

In particular, W and Mo have a higher orientation effect on the (111) plane. Therefore, one or two of W and Mo are preferably added, and any one or two or more of Cr, Ta, V, and Nb may be added. The reason for this is that the combination of Ni and a high melting point bcc metal makes it advantageous for the melting point of Mo or W to be higher than Cr. Further, the addition of Ta, V or Nb has an effect of improving the amorphous form as compared with W and Mo, and is disadvantageous for the formation of the fcc phase required for the seed layer. When Cr is added more than 5% as desired, it is advantageous in terms of orientation.

The alloy of the present invention contains 0 to 10 at%, preferably 1 to 10 at%, more preferably 5% of the alloy from Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P. One or two or more M2 elements selected from the group formed by C and Ru are used as arbitrary elements. The M2 element is an element that orients the (111) plane, and is an element that refines crystal grains. However, when the amount of the M2 element exceeds 10%, a compound may be produced or may be amorphous. Further, the total amount of M1 + M2 is preferably 25 at% or less, and more preferably 20 at% or less.

Example

The invention will be specifically described below by way of examples.

Generally, a seed layer in a perpendicular magnetic recording medium is sputtered with a sputtering target having the same composition as that of the composition, and is formed by film formation on a glass substrate. Here, the film formed by sputtering is rapidly cooled. The test material of the present invention uses a quenched ribbon produced by a single roll quenching device. It is easy to evaluate the influence of the composition on the characteristics of the film which is actually quenched by sputtering and is formed into a film by the liquid quenching ribbon.

[Preparation of quenched ribbon]

30 g of the raw material weighed according to the composition of Table 1 was decompressed in a water-cooled copper casting mold having a diameter of 10 mm and a length of 40 mm, and was subjected to arc dissolution in Ar to serve as a dissolved base material for the quenched ribbon. The production conditions of the quenched ribbon were set in a single roll on a quartz tank having a diameter of 15 mm, and the dissolved base material was set. The diameter of the melt metal discharge nozzle was set to 1 mm, the ambient pressure was 61 kPa, the spray differential pressure was 69 kPa, and the copper roll (diameter 300 mm). The rotation number was 3000 rpm, and the melt metal discharge was performed at a distance of 0.3 mm between the copper roll and the melt metal discharge nozzle. The discharge temperature was set just after the molten base material was melted and dropped. The quenched ribbon thus produced was used as a test material, and the following items were evaluated.

[Evaluation of coercive force]

Regarding the coercive force meter of the vibration sample type, the quenching tape was attached to the sample stage with a double-sided tape, and the coercive force of the quenched ribbon was measured by an initial application magnetic field of 144 kA/m. When the coercive force is 300 A/m or less, it is represented by ○, and when it exceeds 300 A/m and 500 A/m or less, it is represented by Δ, and when it exceeds 500 A/m, it is represented by ×.

[Evaluation of Saturation Magnetic Flux]

The saturation magnetic flux density of the quenched ribbon was measured in a VSM apparatus (vibration sample type magnetometer) by applying a magnetic field of 1200 kA/m. The weight of the test material was about 15 mg, and it was evaluated as ○ at 0.2 T or more, and was evaluated as × at less than 0.2 T.

[(111) plane orientation evaluation]

The seed layer formed by sputtering is an fcc structure. The seed layer is oriented (200) by quenching. Generally, if randomly oriented, the X-ray diffraction intensity I (200) of the (111) plane and the (200) plane is higher than I (111). Therefore, the directivity of the (111) plane of the quenched ribbon was evaluated by the following method.

A test piece was attached to the glass plate with a double-sided tape, and a diffraction pattern was obtained by an X-ray diffraction device. At this time, the test piece was attached so that the measurement surface became the contact surface of the copper roll of the quenched ribbon. The Cu-α line was used as an X-ray source and the scanning speed was 4°/min. The intensity ratio I(111)/I(200) of the X-ray intensity I(111) and the (200) plane X-ray intensity I(200) of the (111) plane of the refractive pattern is less than 0.7. It is written as ×, and 0.7 or more is recorded as ○. The person who produced the compound and the amorphous type were recorded as ×.

[Evaluation of crystal grains]

The crystal grain size of the quenched ribbon was measured in accordance with JIS G0551 "Microscope test method for steel and crystal grain size" in the direction of the roll of the microstructure of the quenched ribbon. When P/Lt is 1.0 or more, it is represented by ○, 0.5 or more, and less than 1.0 is Δ, and less than 0.5 is ×.

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

[Table 6]

[Table 7]

[Table 8]

As shown in Tables 1 to 8, No. 1 to 95 and 125 to 188 are examples of the invention, Nos. 96 to 124 and 189 to 193 are comparative examples, and No. 194 is a reference example.

Further, as described in the component compositions of Tables 1 to 8, for example, since No. 1 is W at 2 at%, (Ni2Fe) is 100% to 2% and is 98 at%, and when 98% is set to 1, Ni is Ni. For (100-2), Fe is a ratio of 2. And since it does not contain Co, its ratio is equivalent to zero. Similarly, in the case of No. 50, since W and In are 7 at%, (Ni50Fe) is 100%-7% and is 93 at%, and when 93 at% is 1, Ni is 100-50, and Fe is 50. The ratio, that is, Ni and Fe are in the same ratio at the ratio of at, and therefore means an average of 46.5% of each of 93%.

In Comparative Example No. 96, since it was only Ni, the coercive force was high, and the orientation and crystal grain size were inferior. In Comparative Example No. 97, since the M element was not contained, the orientation and the crystal grain size were inferior. In Comparative Example No. 98, since the Fe content was high, the coercive force was high. In Comparative Example No. 99, since the W content was low and the Al content was high, the coercive force was slightly increased and the orientation was poor. In Comparative Example No. 100, since the W content was high, the coercive force was difficult to measure, and the saturation magnetic flux density and the directivity were poor.

In Comparative Examples Nos. 101 and 102, since the W content was low and the contents of Zr and B were high, the orientation was poor. In Comparative Example No. 103, since the Ni content was low and the Fe content was high, the coercive force was high. In Comparative Example No. 104, since the Ni content was low and the Fe content was high, the coercive force was high. In Comparative Example No. 105, since the Cr content was low, the coercive force was high, and both the orientation and the crystal grain size were inferior. In Comparative Example No. 106, since the Cr content was high, all the characteristics were inferior. In Comparative Example No. 107, since the Mo content was low, the coercive force was high, and the orientation and crystal grain size were inferior.

In Comparative Example No. 108, since the Mo content was high, all the characteristics were inferior. In Comparative Example No. 109, since the Ta content was low, the coercive force was high, and the orientation and crystal grain size were inferior. In Comparative Example No. 110, since the Ta content was high, all the characteristics were inferior. In Comparative Example No. 111, since the V content was low, the coercive force was high, and the orientation and crystal grain size were inferior. In Comparative Example No. 112, since the V content was high, all the characteristics were inferior. In Comparative Example No. 113, since the Nb content was low, the coercive force was high, and the orientation and crystal grain size were inferior.

In Comparative Example No. 114, since the Nb content was high, all the characteristics were inferior. In Comparative Example No. 115, since the Ca content was high, the orientation and crystal grain size were inferior. In Comparative Example No. 116, since the In content was high, the orientation and crystal grain size were inferior. In Comparative Example No. 117, since the Si content was high, the orientation and the crystal grain size were inferior. In Comparative Example No. 118, since the Ge content was high, the orientation and crystal grain size were inferior. In Comparative Example No. 119, since the Ti content was high, the orientation and crystal grain size were inferior.

In Comparative Example No. 120, since the Hf content was high, the orientation and crystal grain size were inferior. In Comparative Example No. 121, since the Cu content was high, the orientation and the crystal grain size were inferior. In Comparative Example No. 122, since the P content was high, the orientation and the crystal grain size were inferior. In Comparative Example No. 123, since the C content was high, the orientation and the crystal grain size were inferior. In Comparative Example No. 124, since the Ru content was high, the orientation and crystal grain size were inferior.

In Comparative Example No. 189 of Table 8, since the content of Fe + Co was low, the coercive force was poor. In Comparative Example No. 190, since the content of Fe + Co was low, the coercive force was poor. No. 191 has a low coercive force due to a low content of Fe + Co. No. 192 has a low coercive force due to a low content of Fe + Co. No. 193 has a low coercive force due to a low content of Fe + Co. Although No. 194 was within the conditions of the present invention, since the amount of addition of Cr was 4.9 and did not exceed 5, the characteristics were slightly inferior. Therefore, as a reference example.

As described above, in the Ni-Fe-Co-M alloy, by being restricted to a certain content, it is found to have magnetic properties by being restricted in the region, and the magnetic permeability in the (111) direction becomes high by using Ni The seed layer imparts magnetic properties and exhibits an excellent effect of shortening the distance between the magnetic head and the soft magnetic underlayer film.

[Manufacture and evaluation of sputtering targets]

Next, an example of a method of manufacturing a sputtering target will be described. Inventive Example No. 2, No. 10, No. 14, No. 18, No. 25, and Table No. 35, No. 38, No. 43, and No. 51 of Table 3 of the weighing scale 1. No. 70, No. 79 of Table 4, No. 85, No. 89, No. 95, No. 102 of Table 5, No. 117, No. 118, No. 122, No. 128 of Table 6, Dissolved raw materials of components of No. 135, No. 144, No. 159, No. 170, No. 176 of Table 7, No. 188 of Table 8, No. 190 of Comparative Example No. 190, and Comparative Example No. 193 After being melted by induction heating in a refractory crucible of a decompressed Ar gas atmosphere, the nozzle was discharged from a nozzle having a diameter of 8 mm at the lower portion of the crucible, and was atomized by Ar gas. The gas atomized powder was used as a raw material powder, and it was filled in a capsule made of carbon steel and having a diameter of 250 mm and a length of 100 mm, and vacuum degassing and sealing was performed.

The powder-filled bombs described in No. 2, No. 10, No. 14, No. 18, No. 25, Table No. 51, and No. 70 of Table 1 have a molding temperature of 1000 ° C and a molding pressure of 147 MPa. HIP molding was carried out under the conditions of a molding time of 1 hour, and No. 35, No. 38, No. 43 of Table 2, No. 79, No. 85, No. 89, and No. 95 of Table 4 were formed at a molding temperature of 1100 ° C. HIP molding was carried out under the conditions of a molding pressure of 147 MPa and a molding time of 3 hours, and No. 102, No. 117, No. 118, No. 122, Table 6, No. 128, No. 135, No. 144 of Table 6, No. 159, No. 170, No. 176, Table No. 188, Comparative Example No. 190, and Comparative Example No. 193 of Table 7 were prepared at a molding temperature of 950 ° C, a molding pressure of 147 MPa, and a molding time of 5 hours. Perform HIP forming. The HIP body was processed into a disk shape having a diameter of 180 mm and a thickness of 7 mm by wire cutting, rotary disk processing, or surface polishing, and used as a sputtering target.

A sputtered film was formed on the glass substrate by using a sputtering target having a composition of these 27 types. The X-ray diffraction peaks are in the present invention examples No. 2, No. 10, No. 14, No. 18, No. 25, No. 35, No. 38, No. 43, No. 51, No. 70, No. 79, No. 85, No. 89, No. 95, No. 128, No. 135, No. 144, No. 159, No. 170, No. 176, No. 186 all saw good orientation. Comparative Examples No. 102, No. 117, No. 118, and No. 122 did not show good directivity.

Further, after measuring the magnetic properties in the same manner as the quenched ribbon, the present invention examples No. 2, No. 10, No. 14, No. 18, No. 25, No. 35, No. 38, No. 43, No. 51, No. 70, No. 79, No. 85, No. 89, No. 95, No. 128, No. 135, No. 144, No. 159, No. 170, No. 176, No. Good magnetic properties were observed in all of 186, and good magnetic properties were not observed in Comparative Example No. 189, Comparative Example No. 190, and Comparative Example No. 193. The X-ray diffraction pattern was also measured in the same manner as in the quenched ribbon, and evaluated as ○, Δ, and × in the same manner as the evaluation results of the quenched ribbon. In summary, it was confirmed that the evaluation result of the quenched ribbon was evaluated to be the same as that of the sputtering film formed by using the sputtering target.

Claims (12)

An alloy for a seed layer of a magnetic recording medium, comprising: one or two or more kinds of M1 elements selected from the group consisting of W, Mo, Ta, Cr, V, and Nb; 20 at%, one or two or more kinds of M2 elements selected from the group consisting of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru. 0~10 at%, the rest are Ni, Fe and Co, and are Ni:Fe:Co=98~20:0~50:0~60 with respect to at% of the total amount of Ni+Fe+Co The ratio of Fe+Co≧1.5. The alloy of claim 1 is only composed of 2 to 20 at% of the M1 element of the alloy, 0 to 10 at% of the M2 element of the alloy, the remainder of Ni, Fe and Co, and unavoidable impurities. . An alloy for a seed layer of a magnetic recording medium, comprising: one or two or more kinds of M1 elements selected from the group consisting of W, Mo, Ta, Cr, V, and Nb; 20 at%, one or two or more kinds of M2 elements selected from the group consisting of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru. 0~10 at%, the rest are Ni, Fe and Co, and are Ni:Fe:Co=98~20:2~50:0~60 with respect to at% of the total amount of Ni+Fe+Co proportion. The alloy of claim 3, which is composed of only 2 to 20 at% of the M1 element of the alloy, 0 to 10 at% of the M2 element of the alloy, the remainder of Ni, Fe and Co, and unavoidable impurities. . An alloy according to claim 1 or 2, which contains one or both of W and Mo. An alloy of claim 3 or 4, which contains one or both of W and Mo. An alloy of claim 1 or 2, which contains more than 5% of Cr. An alloy of claim 3 or 4, which contains more than 5% of Cr. An alloy of the first or second aspect of the patent application, which contains more than 0% and less than 10 at% of free Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C and Ru One or more of the selected groups are selected. An alloy of the third or fourth aspect of the patent application, which contains more than 0% and less than 10 at% of free Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C and Ru One or more of the selected groups are selected. A sputtering target comprising an alloy according to any one of claims 1 to 10. A magnetic recording medium having a seed layer, which is composed of an alloy according to any one of claims 1 to 10.