JP2012128933A - Alloy for seed layer of magnetic recording medium, and sputtering target material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy for a seed layer of an Ni-Fe-Co-based magnetic recording medium used as a seed layer for a perpendicular magnetic recording medium, and a sputtering target material.SOLUTION: There are provided the alloy for the seed layer of the magnetic recording medium characterized in being an Ni-Fe-Co-M alloy, in Ni:Fe:Co=98-20:0-50:0-60 as an at% ratio of Ni, F, and Co and Fe+Co≥2, and in containing one kind or two or more kind among W, Mo, Ta, Cr, V, and Nb as M elements by 2-20 at%; and the sputtering target material.

Description

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

  In recent years, the progress of perpendicular magnetic recording has been remarkable, and in order to increase the capacity of the drive, the recording density of the magnetic recording medium has been increased. A realizable perpendicular magnetic recording system has been put into practical use. Here, the perpendicular magnetic recording method is a method suitable for high recording density, in which the easy axis of magnetization is oriented perpendicularly to the medium surface in the magnetic film of the perpendicular magnetic recording medium. .

  In the perpendicular magnetic recording system, a recording medium having a magnetic recording film layer and a soft magnetic film layer with an increased recording density has been developed, and in such a medium structure, a space between the soft magnetic layer and the magnetic recording layer has been developed. In addition, a recording medium on which a seed layer and a base film layer are formed has been developed. As a seed layer for the perpendicular magnetic recording system, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-155722 (Patent Document 1), a Ni—W alloy has been proposed.

The Ni-W alloy described in Patent Document 1 is a nonmagnetic element group IVa (Ti, Zr, Hf), group Va (V, Nb, Ta), VIa without adding a group VIII having magnetism. Group (Cr, Mo, W), Group VIIa (Mn, Tc, Re), Group IIIb (B, Al, Ga, In, Tl), Group IVb (C, Si, Ge, Sn, Pb) As a result, it was non-magnetic. One of the characteristics required for the seed layer is, as the name suggests, the orientation of the layer formed on the seed layer is controlled, and the easy axis of the magnetic film for recording magnetic information is Therefore, the seed layer itself has a single fcc structure and a plane parallel to the medium surface is oriented in the (111) plane. In order to improve the recording density, it is necessary to make the crystal grain size of the magnetic film as small as possible. For this purpose, it is desirable that the crystal grain size of the seed layer is smaller.
JP 2009-155722 A

  On the other hand, in recent years, as a technique for improving the magnetic recording characteristics of a hard disk drive, a method of imparting magnetism to a seed layer has been studied. However, as described above, the seed layer alloy described in Patent Document 1 is non-magnetic and cannot be said to be suitable as a seed layer alloy having magnetism. Therefore, as described above, there has been a demand for the development of a seed layer alloy having the characteristics required for a seed layer alloy and having magnetism. As a major difference between the soft magnetic layer and the seed layer, the soft magnetic layer is required to be amorphous to reduce noise, but the seed layer has an effect of controlling the orientation of the layer formed on the seed layer. It is required and has high crystallinity as opposed to amorphous which is amorphous.

  In order to sufficiently achieve the above requirements, the inventors have made extensive developments, and as a result, by adding Fe, Co, which is a group VIII element having magnetism, the seed layer is made magnetic, and By reducing the coercive force in the (111) plane direction, it was found that the magnetic permeability was increased, and the present invention was completed.

The gist of the invention is that
(1) Ni—Fe—Co—M alloy, in which the ratio of Ni, Fe, Co is at%, Ni: Fe: Co = 98-20: 0-50: 0-60, Fe + Co ≧ 1.5 And an alloy for a seed layer of a magnetic recording medium, containing 2 to 20 at% of one or more of W, Mo, Ta, Cr, V, and Nb as M elements.

  (2) Ni—Fe—Co—M alloy, the ratio of Ni, Fe, Co is at%, Ni: Fe: Co = 98-20: 2-50: 0-60, and M An alloy for a seed layer of a magnetic recording medium, containing 2 to 20 at% of one or more of W, Mo, Ta, Cr, V, and Nb as elements.

(3) An alloy for a seed layer of a magnetic recording medium, comprising one or two of W and Mo among the M elements described in (1) or (2).
(4) An alloy for a seed layer of a magnetic recording medium, comprising more than 5% of Cr among the M elements according to any one of (1) to (3).
(5) In addition to the M element described in any one of (1) to (4), Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C An alloy for a seed layer of a magnetic recording medium, containing one or more of Ru, 0 to 10 at%.

(6) A sputtering target material comprising the seed layer alloy for a magnetic recording medium according to any one of (1) to (5).
(7) A magnetic recording medium using the seed layer alloy according to any one of (1) to (5).

  As described above, the Ni-based intermediate layer on the soft magnetic underlayer (SUL) is made magnetic by adding Fe and Co, which are Group VIII elements having magnetism, to the Ni-M alloy. Another object of the present invention is to provide an alloy for a seed layer of a magnetic recording medium and a sputtering target material using the same, which can increase the magnetic permeability by reducing the coercive force in the (111) plane direction.

The reason for limiting the invention according to the present invention will be described below.
In the Ni—Fe—Co—M alloy according to the present invention, when Ni: Fe: Co = α: β: γ, which is the ratio of Ni, Fe, and Co, α: 98.5-20. The reason for setting it to 98.5 or less is that when β + γ is less than 1.5, the coercive force is high. Moreover, if it is 20 or more, if it is less than 20, the coercive force is increased as described above. Therefore, the range was set to 98.5-20. Preferably it is set to 98.5-60.

at ratio β: 0 to 50
Fe is an element that reduces the coercive force and also improves the orientation of the film. However, since coercive force will become high when it exceeds 50, the range was made into 0-50. Preferably it is 2 to 50%, more preferably 10 to 40.
at ratio γ: 0 to 60
Co is an element that reduces the coercivity in the (111) direction. However, if the value exceeds 60, the coercive force increases, so the upper limit is set to 60. Preferably it is 40 or less.

  In the Ni—Fe—Co—M alloy, when W, Mo, Ta, Cr, V, and Nb are hereinafter referred to as M1 elements, these M1 elements are bcc metals having a high melting point. Although the mechanism is not clear by adding to the Ni-Fe-Co system which is fcc within the specified component range, the orientation to the (111) plane required for the seed layer is improved, and the crystal grains are added. Element to be refined. One or two or more of W, Mo, Ta, Cr, V, and Nb is 2% to 20% in terms of at%. However, if it is less than 2%, the effect is not sufficient, and if it exceeds 20%, the compound precipitates or becomes amorphous. Since the seed layer alloy is required to be an fcc single phase, its range is set to 2 to 20%. Preferably it is 5 to 15%.

  Further, W and Mo are highly effective for the orientation of the (111) plane, and desirably one or two of W and Mo are essential, and Cr, Ta, V, and Nb may be added thereto. The reason for this is a combination of Ni and a high melting point bcc metal. Mo and W are advantageous because they have a higher melting point than Cr. Further, the addition of Ta, V, and Nb also acts to enhance the amorphous property by adding them compared to W and Mo, and is disadvantageous for the fcc phase formation required for the seed layer. When Cr is desirably added in excess of 5%, it is advantageous in terms of orientation.

  Furthermore, when Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru are hereinafter referred to as M2 elements, the M2 elements orient the (111) plane. It is an element and an element that refines crystal grains. One or two or more of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Ru are used in an amount of 0% to 10%. However, if it exceeds 10%, a compound is formed or becomes amorphous, so the upper limit is made 10%. Preferably it is 5%. M1 + M2 is preferably 25 at% or less, more preferably 20 at% or less.

Hereinafter, the present invention will be specifically described with reference to examples.
Usually, the seed layer in a perpendicular magnetic recording medium can be formed on a glass substrate or the like by sputtering a sputtering target material having the same component as that of the seed layer. Here, the thin film formed by sputtering is rapidly cooled. As a test material in the present invention, a quenched ribbon manufactured by a single roll type quenching apparatus is used. This is a simple evaluation of the influence of the components on various properties of a thin film formed by quenching by sputtering in a simple manner using a liquid quenching ribbon.

  The conditions for preparation of the quenched ribbon are as follows: 30 g of raw materials weighed in the components shown in Table 1 are decompressed with a water-cooled copper mold having a diameter of about 10 and a length of about 40 mm, arc-melted in Ar, and the quenched ribbon is melted. It was. The conditions for preparing the quenching ribbon are as follows. This molten base material is set in a quartz can having a diameter of 15 mm by a single roll method, the tap nozzle diameter is 1 mm, the atmospheric pressure is 61 kPa, the spray differential pressure is 69 kPa, the copper roll (diameter is 300 mm). The hot water was discharged at a rotation speed of 3000 rpm and a gap of 0.3 mm between the copper roll and the hot water nozzle. The hot water temperature was set immediately after each molten base material was melted. The following items were evaluated using the thus prepared quenched ribbon as a test material.

  For the evaluation of the coercive force of the rapidly cooled ribbon, a vibration sample type coercive force meter was used, and a quenching ribbon was attached to the sample stage with double-sided tape, and the initial applied magnetic field was 144 kA / m. A coercive force of 300 A / m or less was evaluated as ◯, a coercive force exceeding 300 A / m and 500 A / m or less as Δ, and a coercive force exceeding 500 A / m as x.

  As the evaluation of the saturation magnetic flux density of the quenched ribbon, it was measured with an applied magnetic field of 1200 kA / m with a VSM apparatus (vibrating sample magnetometer). The weight of the test material was about 15 mg, and 0.2 T or more was evaluated as O, and less than 0.2 T was evaluated as X.

  For evaluating the (111) plane orientation of the quenched ribbon, the seed layer formed by sputtering has an fcc structure. The seed layer is rapidly cooled to orient (200). Usually, if random orientation is performed, the X-ray diffraction intensity of the (111) plane and the (200) plane will be higher for I (200) than I (111). Therefore, the orientation of the (111) plane was evaluated by the following method.

  The test material was attached to a glass plate with a double-sided tape, and a diffraction pattern was obtained with an X-ray diffractometer. At this time, the test material was affixed so that a measurement surface might become a copper roll contact surface of a rapidly cooled ribbon. The X-ray source was Cu-α ray and measured at a scan speed of 4 ° / min. I (111) / I (200), which is the intensity ratio between the intensity I (111) of the X-ray diffracted by the (111) plane of this diffraction pattern and the intensity I (200) of the (200) plane, is 0.7. Those with less than were marked with x, and those with 0.7 or more were marked with ◯. Moreover, what produced a compound and what made it amorphous were set to x.

  The crystal grain size of the quenched ribbon was evaluated in the roll direction of the cross-sectional microstructure image of the quenched ribbon in accordance with JIS G0551 “Microscopic test method for steel and crystal grain size”. When P / Lt is 1.0 or more, ○, 0.5 or more, less than 1.0 is Δ, and less than 0.5 is ×.

表１〜８に示すように、Ｎｏ．１〜９５、１２５〜１８８は本発明例であり、Ｎｏ．９６〜１２４、１８９〜１９４は比較例である。

As shown in Tables 1-8, no. 1-95 and 125-188 are examples of the present invention. Reference numerals 96 to 124 and 189 to 194 are comparative examples.

  In addition, it describes in the component composition shown to Tables 1-8, for example, No. Since 1 is W at 2 at%, (Ni 2 Fe) is 100% -2% and 98 at%, and when 98% is 1, Ni is (100-2) and Fe is a ratio of 2. . Further, since Co is not included, the ratio corresponds to zero. Similarly, no. If it is 50, since it is 7 at% in total for W and In, (Ni50Fe) is 93% at 100% -7%. When 93 at% is 1, Ni is a ratio of 100-50 and Fe is 50. In other words, since Ni and Fe have the same ratio in terms of at ratio, this means that they are 46.5 at%, which is half of 93 at%.

  Comparative Example No. Since 96 is Ni alone, it has a high coercive force and is inferior in orientation and crystal grain size. Comparative Example No. 97 is inferior in orientation and crystal grain size because there is no M element. Comparative Example No. No. 98 has a high coercive force due to its high Fe content. Comparative Example No. No. 99 has a low W content and a high Al content, so the coercive force is slightly high and the orientation is poor. Comparative Example No. Since 100 has a high W content, it is difficult to measure the coercive force, and the saturation magnetic flux density and orientation are inferior.

  Comparative Example No. Since 101 and 102 have low W content and high Zr and B content, the orientation is inferior. Comparative Example No. Since No. 103 has a low Ni content and a high Fe content, the coercive force is high. Comparative Example No. No. 104 has a low Ni content and a high Fe content, so the coercive force is high. Comparative Example No. Since No. 105 has a low Cr content, the coercive force is high, and the orientation and crystal grain size are inferior. Comparative Example No. No. 106 is inferior in all properties due to the high Cr content. Comparative Example No. No. 107 has a low Mo content, and thus has a high coercive force and is inferior in orientation and crystal grain size.

  Comparative Example No. No. 108 is inferior in all properties because of its high Mo content. Comparative Example No. Since No. 109 has a low Ta content, the coercive force is high, and the orientation and crystal grain size are inferior. Comparative Example No. No. 110 is inferior in all properties because of the high Ta content. Comparative Example No. 111 has a low coercive force due to a low content of V, and is inferior in orientation and crystal grain size. Comparative Example No. No. 112 is inferior in all characteristics because of high V content. Comparative Example No. Since No. 113 has a low Nb content, the coercive force is high, and the orientation and crystal grain size are inferior.

  Comparative Example No. No. 114 is inferior in all properties because of the high Nb content. Comparative Example No. No. 115 is inferior in configuration and crystal grain size because of high Ca content. Comparative Example No. 116 is inferior in configuration and crystal grain size because of its high In content. Comparative Example No. 117 is inferior in configuration and crystal grain size because of high Si content. Comparative Example No. No. 118 is inferior in configuration and crystal grain size because of the high Ge content. Comparative Example No. 119 is inferior in configuration and crystal grain size because of the high Ti content.

  Comparative Example No. No. 120 is inferior in configuration and crystal grain size because of high Hf content. Comparative Example No. No. 121 is inferior in configuration and crystal grain size because of high Cu content. Comparative Example No. Since 122 has a high P content, the configuration and crystal grain size are inferior. Comparative Example No. Since 123 has a high C content, the configuration and the crystal grain size are inferior. Comparative Example No. No. 124 is inferior in configuration and crystal grain size because of the high Ru content.

  Comparative Example No. 189 is inferior in coercive force due to the low content of Fe + Co. Comparative Example No. Since 190 has a low content of Fe + Co, the coercive force is inferior. No. Since 191 has a low content of Fe + Co, the coercive force is inferior. No. Since 192 has a low content of Fe + Co, the coercive force is inferior. No. Since 193 has a low content of Fe + Co, the coercive force is inferior. No. Although 194 is within the conditions of the present invention, since the Cr addition amount does not exceed 4.9 and 5, the characteristics are slightly inferior. Therefore, it was set as a comparative example.

  As described above, in the Ni-Fe-Co-M alloy, by restricting to a certain content, by restricting to this region, it has magnetism and increases the magnetic permeability in the (111) direction. Thus, by providing magnetism to the Ni-based seed layer, there is an excellent effect that the distance between the magnetic head and the soft magnetic underlayer can be shortened.

  Next, the example of the manufacturing method of sputtering target material is shown. Invention Example No. 1 in Table 1 2, no. 10, no. 14, no. 18, no. 25 and No. 2 in Table 2. 35, no. 38, no. 43, No. 3 in Table 3. 51, no. 70, No. 4 in Table 4. 79, no. 85, no. 89, no. 95, No. 5 in Table 5. 102, no. 117, no. 118, No. 122, No. 1 in Table 6. 128, no. 135, no. 144, No. 7 in Table 7. 159, no. 170, No. 176, No. 8 in Table 8. 188, Comparative Example No. 190, Comparative Example No. The melted raw materials weighed in the component composition shown in 193 were induction-heated and melted in a refractory crucible in a reduced pressure Ar gas atmosphere, and then discharged from a nozzle with a diameter of 8 mm at the bottom of the crucible and atomized with Ar gas. This gas atomized powder was used as a raw material powder, filled into a carbon steel capsule having a diameter of 250 mm and a length of 100 mm, and vacuum deaerated and sealed.

  The powder filled bullets were prepared as No. 1 in Table 1. 2, no. 10, no. 14, no. 18, no. 25, No. 3 in Table 3. 51, no. 70, a molding temperature of 1000 ° C., a molding pressure of 147 MPa, a molding time of 1 hour, No. 35, no. 38, no. 43, No. 4 in Table 4. 79, no. 85, no. 89, no. No. 95 is a molding temperature of 1100 ° C., a molding pressure of 147 MPa, a molding time of 3 hours, No. 5 in Table 5. 102, no. 117, no. 118, no. 122, no. 128, no. 135, no. 144, No. 7 in Table 7. 159, no. 170, No. 176, No. 8 in Table 8. 188, Comparative Example No. 190, Comparative Example No. No. 193 was HIP molded under conditions of a molding temperature of 950 ° C., a molding pressure of 147 MPa, and a molding time of 5 hours. This HIP body was processed into a disk shape having a diameter of 180 mm and a thickness of 7 mm by wire cutting, lathe processing, and planar polishing to obtain a sputtering target material.

  Sputtering films were formed on glass substrates using sputtering target materials for these 27 kinds of component compositions. The X-ray diffraction pattern is shown in Example No. of the present invention. 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. No. 186 shows good orientation in any case, and Comparative Example No. 102, no. 117, no. 118, no. No good orientation was observed in 122.

Further, when the magnetic properties were measured in the same manner as the quenched ribbon, the present invention example 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. No. 186 shows good magnetic properties. 189, Comparative Example No. 190, Comparative Example No. In 193, good magnetic properties were not observed. The X-ray diffraction pattern was also measured in the same manner as the quenched ribbon, and was the same as the results evaluated with the quenched ribbon, ○, Δ, ×. In summary, it was confirmed that the results of the evaluation with the quenched ribbon and the evaluation of the sputtered film formed using the sputtering target material had the same tendency.

Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (7)

Ni-Fe-Co-M alloy, the ratio of Ni, Fe, Co is at%, Ni: Fe: Co = 98-20: 0-50: 0-60, Fe + Co ≧ 1.5, An alloy for a seed layer of a magnetic recording medium, comprising 2 to 20 at% of one or more of W, Mo, Ta, Cr, V, and Nb as M element. Ni-Fe-Co-M alloy, the ratio of Ni, Fe, Co is at%, Ni: Fe: Co = 98-20: 2-50: 0-60, and W as the M element , Mo, Ta, Cr, V, Nb, containing 2 to 20 at% of one or more of the following: an alloy for a seed layer of a magnetic recording medium. 3. An alloy for a seed layer of a magnetic recording medium comprising one or two of W and Mo among the M elements according to claim 1. An alloy for a seed layer of a magnetic recording medium, comprising more than 5% of Cr among the M element according to any one of claims 1 to 3. In addition to the M element according to any one of claims 1 to 4, one kind of Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, Ru, or An alloy for a seed layer of a magnetic recording medium, containing 2 to 10 at% of two or more. The sputtering target material formed using the alloy for seed layers of the magnetic-recording medium of any one of Claims 1-5. A magnetic recording medium using the seed layer alloy according to claim 1.