WO2014097860A1 - Cu-BASED ALLOY FOR MAGNETIC RECORDING, SPUTTERING TARGET MATERIAL, AND PERPENDICULAR MAGNETIC RECORDING MEDIUM USING SAME - Google Patents

Abstract

Provided is a Cu-based alloy for magnetic recording, which contains, in at%, (A) 1-23.4% of one or more elements selected from the group consisting of Cr, Mo and W, (B) 0-5% of one or more elements selected from the group consisting of Al, Si, Zn, Mn and Ni, and (C) 0-1% of one or more elements selected from the group consisting of Y, La, Ce, Nb, Sm, Gd, Tb and Dy, with the balance made up of Cu and unavoidable impurities. The alloy of the present invention has a high thermal conductivity and a high hardness at the same time, and is thus capable of providing a sputtering target that is suitable for the production of a thermally assisted magnetic recording medium and of providing a thermally assisted magnetic recording medium having a high impact resistance.

Description

Cu-based magnetic recording alloy, sputtering target material, and perpendicular magnetic recording medium using the same

The present invention relates to a Cu-based alloy and a sputtering target material used for a heat sink layer in a heat-assisted magnetic recording medium, and a perpendicular magnetic recording medium using the same.

In recent years, the progress of perpendicular magnetic recording has been remarkable, and the recording density of magnetic recording media has been increased to increase the capacity of the drive. Actually, a perpendicular magnetic recording system capable of realizing a higher recording density than the in-plane magnetic recording medium that has been widely used 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. . Further, a method of assisting recording by applying heat by applying a perpendicular magnetic recording method has been studied.

As the recording density of the magnetic recording medium increases, the volume of the magnetic recording medium per bit decreases. For this reason, the problem of recording demagnetization becomes obvious due to thermal disturbance, and a magnetic recording film (CoPt, FePt, etc.) having a higher magnetocrystalline anisotropy constant (Ku) is required. On the other hand, these high crystal magnetic anisotropy materials cannot be recorded with a recordable magnetic field of a current recording head. Therefore, in the heat-assisted recording method, by utilizing the fact that the magnetism of the recording material decreases with temperature, the target area is heated only with recording using laser light or near-field light, thereby enabling magnetic recording.

The heat-assisted recording method is a recording method that combines magnetic recording technology and optical recording technology. The recording magnetic part is held by the heat of laser light irradiation on a high holding force medium that cannot be recorded by ordinary magnetic recording. After recording with the force lowered locally, it is cooled to room temperature and stored with a larger holding force.

In the heat-assisted recording method, it is desirable to cool immediately after heating during recording. For this reason, in order to promote thermal diffusion, a heat sink film having high thermal conductivity is required between the underlayer and the recording film. Documents disclosing such a heat-assisted recording type magnetic recording medium include, for example, Japanese Patent Application Laid-Open No. 2008-210426 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2011-150783 (Patent Document 2). These documents include a heat sink layer containing Cu, Ag, Au, W, Si, or Mo as a thermal diffusion control film (Patent Document 1) and a heat sink layer containing Nb, Bi, or Cu using Ag as a parent phase (Patent Document). 2) is disclosed.

JP 2008-210426 A JP 2011-150783 A

However, the use of these materials has the following problems. That is, when Cu, Ag, or Au is used as the parent phase, the thermal conductivity is sufficiently high, but the hardness of the thin film is low. On the other hand, when W, Si, or Mo is used as the parent phase, the thin film has high hardness but low thermal conductivity. The heat sink film is a relatively thick film in the film structure of the magnetic recording medium, and the hardness of the heat sink film determines the hardness of the entire film structure. For this reason, the heat sink layer needs to have high hardness in order to ensure the impact resistance of the media.

In order to provide a perpendicular magnetic recording medium having high hardness while maintaining the heat conductivity of the heat sink layer, the present inventors have recently increased the strength while maintaining the heat conductivity of the heat sink layer. The Cu-type alloy which can be raised was discovered.

Therefore, an object of the present invention is to provide a Cu-based magnetic recording alloy having both high thermal conductivity and high hardness, and thereby it is possible to provide a sputtering target suitable for manufacturing a heat-assisted magnetic recording medium (especially a heat sink layer). It is to do. By increasing the hardness of the heat sink layer, it is possible to provide a heat-assisted magnetic recording medium with high impact resistance. Thus, there has never been a technical idea to increase the hardness while maintaining the original heat conductivity of the heat sink layer for this application, and this idea is the most characteristic technical idea in the present invention.

According to one aspect of the invention, at%,
(A) 1 to 23.4% of one or more selected from the group consisting of Cr, Mo and W,
(B) 0 to 5% of one or more selected from the group consisting of Al, Si, Zn, Mn and Ni,
(C) 1 to 2% of one or more selected from the group consisting of Y, La, Ce, Nb, Sm, Gd, Tb and Dy
There is provided a Cu-based magnetic recording alloy that contains the remainder Cu and inevitable impurities.

According to another aspect of the present invention, there is provided a sputtering target material comprising an alloy according to the above aspect of the present invention.

According to another aspect of the present invention, there is provided a perpendicular magnetic recording medium including a heat sink layer made of an alloy according to the above aspect of the present invention.

The Cu-based magnetic recording alloy of the present invention will be specifically described below. Unless otherwise specified, content (%) means at%.

The Cu-based magnetic recording alloy of the present invention is at%, (A) 1 to 23.4% of one or more selected from the group consisting of Cr, Mo and W, and (B) Al, Si. , Zn, Mn, and Ni selected from the group consisting of 0 to 5%, or selected from the group consisting of (C) Y, La, Ce, Nb, Sm, Gd, Tb, and Dy 1 type or 2 types or more containing 0 to 1%, consisting of remaining Cu and inevitable impurities (comprising), typically 1 type or 2 types or more selected from the group (A) 23.4%, one or more selected from the group (B) is 0 to 5%, one or more selected from the group (C) is 0 to 1%, the remaining Cu and It consists essentially of inevitable impurities (consisting essentially of) or consists only of (consisting of).

The alloy of the present invention contains, as an optional component, 1 to 23.4%, preferably 5 to 23.%, of one or more selected from the group consisting of Cr, Mo and W (hereinafter referred to as group A element). It contains 4%, more preferably 5 to 17.5%. The Group 6 elements Cr, Mo and W are hardly dissolved in Cu and do not produce a compound. Therefore, in the thin film, pure Cr, pure Mo and / or pure are finely contained in the pure Cu matrix. A structure in which W is deposited is obtained. As a result, it is possible to increase the hardness by precipitation strengthening while maintaining good thermal conductivity of pure Cu. However, when the addition amount is less than 1%, the effect of improving the hardness is not observed. Moreover, when the addition amount exceeds 23.4%, the volume of the precipitated phase is large and the thermal conductivity is greatly reduced. In order to further increase the effect of improving the hardness, the content is preferably 5 to 23.4%.

The alloy of the present invention may contain, as an optional component, less than 5% of one or more selected from the group consisting of Al, Si, Zn, Mn and Ni (hereinafter referred to as B group element), The content is preferably 0.2 to 5%, more preferably 0.2 to 3.5%, and still more preferably 0.2 to 3.0%. The group B element dissolves in Cu and increases the hardness of the Cu matrix, while the rate of decrease in thermal conductivity is greater than that of the Cr, Mo, and W elements described above. Therefore, the preferable addition amount is set in the range of 0.2 to 5%. When the addition amount exceeds 5%, the thermal conductivity is greatly lowered, and the characteristics required for the heat sink layer cannot be obtained. Therefore, an addition amount of 3.5% or less is preferable as a range in which the balance between hardness and thermal conductivity is good.

The alloy of the present invention contains, as an optional component, less than 1% of one or more selected from the group consisting of Y, La, Ce, Nb, Sm, Gd, Tb and Dy (hereinafter referred to as C group element) It may be contained in an amount of preferably 0.1 to 1%, more preferably 0.1 to 0.5%. The group C element is an element that does not dissolve in Cu but forms a compound with Cu, and when added, has an effect of refining the structure, thereby improving the hardness of the film. The conductivity decreases. Therefore, the preferable addition amount is set in the range of 0.1 to 1%. When the addition amount exceeds 1%, the thermal conductivity is greatly reduced, and the characteristics required for the heat sink layer cannot be obtained.

Hereinafter, the present invention will be specifically described with reference to examples.

Usually, a seed layer in a perpendicular magnetic recording medium is obtained by sputtering a sputtering target material having the same component as that of the seed layer and forming a film on a glass substrate or the like. Here, the thin film formed by sputtering is rapidly cooled. On the other hand, 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 effects of various properties due to the components of the ribbon actually formed by sputtering using the liquid quenching ribbon.

Preparation conditions of quenching ribbons 20 g of raw materials weighed for each component shown in Tables 1 and 2 were depressurized with a water-cooled copper mold having a diameter of about 40 mm and arc-melted in Ar to form a quenching ribbon melting base material. . This molten base material is set in a quartz tube with a diameter of 15 mm by a single roll method, the inner diameter of the tap nozzle is 1 mm, the atmospheric pressure is 61 kPa, the spray differential pressure is 69 kPa, and the rotational speed of the copper roll (diameter 300 mm) is set. The hot water was discharged at 3000 rpm and the gap between the copper roll and the hot water nozzle at 0.3 mm. The hot water temperature was the temperature immediately after each molten base material was melted. The quenched ribbon thus produced was used as a test material and evaluated according to the following items.

Thermal conductivity of quenched ribbon The thermal conductivity was evaluated by calculating the specific resistance obtained by measuring the quenched ribbon by the four-terminal method. About thermal conductivity, comparative example No. shown in Table 1 is shown. When the value of 1 pure Cu is 1, the evaluation is less than 0.5 as x, 0.5 to less than 0.6 as Δ, 0.6 to less than 0.8 as ○, and 0.8 or more as ◎. did. These results are shown in Tables 1 and 2.

Hardness of quenching ribbon The quenching ribbon was vertically filled with resin and polished, and measured with a Vickers hardness meter. The measurement load was 25 g and n = 10 average was evaluated. Comparative Example No. 1 shown in Table 1 When the value of pure Cu of 1 is 1, 1.0 or less is evaluated as x, 1.0 to 1.5 is evaluated as Δ, 1.5 to 2.5 is evaluated as ○, and 2.5 is evaluated as ◎. did. These results are shown in Tables 1 and 2 together.

As shown in Tables 1 and 2, no. Nos. 2 to 6, 8 to 11, 13 to 21, 23 to 25, and 27 to 67 are examples of the present invention. 1, 7, 12, 22, 26 and 68 to 70 are comparative examples.

Comparative Example No. Since 1 is Cu alone, the hardness is inferior. Comparative Example No. No. 7 is inferior in thermal conductivity because the Cr content of the (A) group element is high. Comparative Example No. No. 12 is inferior in thermal conductivity because the Mo content of the (A) group element is high. Comparative Example No. No. 22 is inferior in thermal conductivity because the total content of Cr, Mo, W of group (A) elements is high.

Comparative Example No. No. 26 is inferior in thermal conductivity due to the high content of Al of the (B) group element. Comparative Example No. No. 68 is inferior in thermal conductivity because of the high Y content of the (C) group element. Since comparative example No69 has higher content of Y of (C) group element, thermal conductivity is bad. Since comparative example No70 has high content of Nd of (C) group element, thermal conductivity is bad.

On the other hand, No. which is the present invention. Since 2 to 6, 8 to 11, 13 to 21, 23 to 25, and 27 to 67 all satisfy the conditions of the present invention, it is possible to obtain high thermal conductivity and increase hardness and resistance. An alloy having excellent impact properties can be provided. However, no. In the case of 2, since the Cr content of the group (A) element is low, the hardness is slightly inferior, but there is no problem in impact resistance.

As described above, according to the present invention, a Cu-based magnetic recording alloy and a sputtering target material that have both particularly high thermal conductivity and high strength, improve the hardness of the heat sink layer, and are excellent in impact resistance. A perpendicular magnetic recording medium using the same can be obtained.

Claims (10)

1. at%
   (A) 1 to 23.4% of one or more selected from the group consisting of Cr, Mo and W,
   (B) 0 to 5% of one or more selected from the group consisting of Al, Si, Zn, Mn and Ni,
   (C) 1 to 2% of one or more selected from the group consisting of Y, La, Ce, Nb, Sm, Gd, Tb and Dy
   Cu-based magnetic recording alloy comprising the balance Cu and inevitable impurities.
2. 1 to 23.4% of one or more selected from the group (A), 0 to 5% of one or more selected from the group (B), (C) The alloy according to claim 1, consisting essentially of 0 to 1% of one or more selected from the group consisting of the balance Cu and unavoidable impurities.
3. The alloy according to claim 1 or 2, containing 5 to 23.4% of one or more selected from the group (A).
4. The alloy according to claim 1 or 2, containing 0.2 to 5% of one or more selected from the group (B).
5. The alloy according to claim 1 or 2, containing 0.2 to 3.5% of one or more selected from the group (B).
6. The alloy according to claim 1 or 2, containing 0.1 to 1% of one or more selected from the group (C).
7. The alloy according to claim 1 or 2, containing 0.1 to 0.5% of one or more selected from the group (C).
8. 0.2 to 5% of one or more selected from the group (B) is contained in an amount of 0.2 to 5%, and one or more selected from the group (C) is 0.1 to 1 The alloy according to claim 1 or 2, wherein the alloy is contained in%.
9. A sputtering target material comprising the alloy according to any one of claims 1 to 8.
10. A perpendicular magnetic recording medium comprising a heat sink layer made of the alloy according to any one of claims 1 to 8.