TWI512126B - A sputtering target and a method for producing the same, and a film produced by using the same - Google Patents

Description

Sputtering target, method of manufacturing the same, and film produced using the same

The present invention relates to a sputtering target for producing a Ni-W-Cr alloy interlayer film in a perpendicular magnetic recording medium, a method for producing the same, and a film produced using the same.

In recent years, advances in magnetic recording technology have been remarkable, and in order to increase the capacity of drivers, the high recording density of magnetic recording media has progressed. However, in the magnetic recording medium of the in-plane magnetic recording method which has been widely used in the past, in order to achieve high recording density, it is required to refine the recording bit and to record a high coercive force like a recording bit. Therefore, in order to solve such problems and to increase the recording density, a vertical magnetic recording method has been reviewed.

The perpendicular magnetic recording method refers to a method in which the magnetization is easily aligned in the vertical direction with respect to the medium surface in the magnetic film of the perpendicular magnetic recording medium, and is suitable for a method of high recording density. Next, in the perpendicular magnetic recording method, a multilayer recording medium having a magnetic recording film layer, a soft magnetic film layer, and an intermediate layer for improving recording sensitivity has been developed. In the magnetic recording film layer, a CoCrPt-SiO ₂ -based alloy or the like is generally used, and a Co-Zr-Nb-based alloy or the like is used as the soft magnetic film layer. The soft magnetic layer has an action of reflowing a recording magnetic field from a magnetic magnetic head, and has an effect of improving recording and reproducing efficiency. Here, the intermediate layer referred to herein generally means a layer provided for the purpose of refining crystal grains of the magnetic recording film layer or imparting anisotropy to the crystal orientation.

Various Ni-based alloys, Ta-based alloys, Pd-based alloys, and Ru-based alloys have been proposed in the intermediate layer, and Ni-W-based alloys have been widely used in recent years. The intermediate layer controls the structure of the magnetic recording film layer to be one of the functions, and therefore has crystallinity, and the refinement of the crystal grains is extremely important. An example of a Ru intermediate layer has been proposed as disclosed in Japanese Laid-Open Patent Publication No. 2007-179598 (Patent Document 1).

Further, in the Ni-W alloy, the lattice constant of the film is preferably in the range of 3.53 to 3.61 (×10 ^-10 m).

However, when a perpendicular magnetic recording medium is produced by using a Ni-W film as an intermediate layer, good recording characteristics are obtained, but in order to achieve higher recording density, it is necessary to make the recording bit fine, and therefore, in the magnetic recording film. At the time of film formation, it is necessary to refine the crystal grains of the Ni-W-based intermediate layer as a base. In the research of the above, it has been found that it is effective to add B or the like in the miniaturization, but the crystallinity is deteriorated with the miniaturization, which causes a problem in maintaining the alignment property of the magnetic recording film.

The present inventors have found that by adding Cr to the Ni-W-based alloy, it is possible to refine the crystal grains of the intermediate layer while maintaining the crystallinity.

In view of the above, it is an object of the present invention to provide an intermediate layer film for use in a perpendicular magnetic recording medium in which a crystal grain of an intermediate layer is remarkably refined while adding Cr to a Ni-W-based alloy while maintaining crystallinity. A sputtering target, a method for producing the same, and a film produced using the same.

According to the present invention, there is provided a sputtering target which is used as a sputtering target for manufacturing an interlayer film in a perpendicular magnetic recording medium, characterized in that the sputtering target is made of a Ni-W-Cr alloy. It contains 1 to 20% of W, 1 to 20% of Cr, and the residue is Ni in at%.

Further, according to the present invention, there is provided a method for producing a sputtering target, which is a method for producing a sputtering target for an interlayer film used in a perpendicular magnetic recording medium, characterized in that the method comprises: preparing for At%, a material containing 1 to 20% of W, 1 to 20% of Cr, and a raw material powder composed of an alloy of Ni-W-Cr alloy of residual Ni; and curing of the raw material powder engineering.

Further, according to the present invention, there is provided a Ni-W-Cr alloy thin film produced by using the above-described sputtering target or the above method.

The invention is described in detail below.

The sputtering target of the present invention is used in the manufacture of an interlayer film in a perpendicular magnetic recording medium. The sputtering target is made of a Ni-W-Cr alloy and contains 1 to 20% of W and 1 to 20% of Cr in at%, and the residue is Ni.

The sputtering target of the present invention contains 1 to 20 at% of W, preferably 3 to 10 at%. If the amount of W is less than 1%, the lattice constant of the sputtered film is less than 3.53 (×10 ^-10 m), and if it exceeds 20%, the lattice constant exceeds 3.61 (×10 ^-10 m), neither ideal.

The sputtering target of the present invention contains 1 to 20 at% of Cr, preferably 3 to 10 at%. When the total amount of Cr is less than 1%, the effect of refining the crystal grains of the sputtered film is not obtained, and if it exceeds 20%, the effect of refining the crystal grains is saturated, and the effect of the alignment control is small.

The method for producing a sputtering target according to the present invention comprises: preparing, in at%, containing 1 to 20% of W, 1 to 20% of Cr, and the residue Ni is formed of a Ni-W-Cr alloy. The engineering of the raw material powder of the alloy composition; and the engineering of solidifying and forming the raw material powder.

It is preferred to use an alloy powder as a raw material powder. The reason is as follows. Ni, Cr, and W are alloys in which the three elements are likely to be uniform components, and in the melting method in which the cooling rate is small, the crystal grains become large, so that abnormal discharge occurs during sputtering, and a large amount of particles are generated. Bad situation. On the other hand, when the raw material powder is produced by the gas atomization method, since the crystal grains are finely solidified, the crystal grains are fine, and the sputtering target which is solidified by using the sputtering target material is preferably small in the amount of fine particles.

The curing temperature is preferably from 800 to 1,250 °C. When the molding is performed at 800 ° C or higher, the sintering can be sufficiently performed, and the relative density of the sputtering target can be increased. Further, when it is molded at a temperature of 1,250 ° C or lower, it is possible to effectively prevent the expansion of the billet during heating, and it is possible to manufacture it more stably.

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples.

The Ni-W-Cr alloy powder shown in Table 1 was produced by gas atomization. In the powder, one or two or more kinds of pure metal powders of Ni, W and Cr are mixed as a raw material powder so as to have a predetermined composition. Using the raw material powder, the powder-filled billet which is degassed and sealed in the SC barrel is solidified and formed by HIP method and upset at 750 to 1350 ° C, and Ni-W- is produced by mechanical processing. Sputter target of Cr alloy. In addition, a Ni-W-Cr alloy sputtering target was also produced by a casting method. The details of these projects are as follows.

First, 25 kg of the molten base material was inductively melted in Ar using alumina crucible, and discharged at 1700 ° C from a liquid discharge nozzle having a diameter of 5 mm at the bottom of the crucible, and atomized by spraying Ar gas of a spray pressure of 0.7 Mpa. . One or two or more kinds of pure metal powders of Ni, W, and Cr which are produced or sold in the market are mixed by the same gas atomization as needed for the adjustment of the components. The produced and mixed Ni-W-Cr alloy powder was degassed and sealed in an SC can having an outer diameter of 205 mm, an inner diameter of 190 mm, and a length of 300 mm. The degree of vacuum arrival at degassing was about 1.3 x 10 ^-2 Pa.

The powder-filled blank was subjected to HIP molding at 900 to 1350 ° C and 147 MPa. At the same time, the above-mentioned powder-filled billet was heated to 750 to 1200 ° C, and then placed in a restrictive type container having a diameter of 215 mm, and formed at a pressure of 500 MPa. The solidified molded body produced by the above method was processed into a disk shape having a diameter of 76.2 mm and a thickness of 3 mm by wire cutting, lathe processing, and surface polishing, and a copper backing plate was welded to form a sputtering target.

On the other hand, in the casting method, 100 kg of the molten base material was vacuum-melted, cast into a mold having a diameter of 210 mm, and cut into a diameter of 200 mm and a length of 100 mm by a lathe, and hot forged at 850 ° C to a height of 50 mm. The subsequent method of producing the sputtering target is carried out in the same manner as the above-described HIP or forging material.

The evaluation items and methods of the manufactured sputtering target are as follows.

The expansion of the blank during solidification molding was evaluated by the appearance of the HIP material after the HIP. Further, regarding the forging and coarse material, the appearance when the billet was heated was evaluated. The results are expressed as follows: no expansion: ○, there is expansion: ×.

The relative density of the sputtering target was measured by the size and weight of a disk having a diameter of 76.2 mm and a thickness of 3 mm which were produced by the above method, and the ratio of the calculated density calculated from the composition was set to a relative density.

The number of particles of the sputtered film was sputtered on a Si substrate having a diameter of 63.5 mm, and the obtained sputtered film was evaluated. The sputtering conditions were set to an Ar pressure of 0.5 Pa and a DC power of 500 W. Further, the film formation thickness was formed to be 500 nm. The number of particles generated at this time was measured. Here, the number of the particles in Table 1 is represented by a relative value in which the number of particles of No. 1 is 100.

The lattice constant of the sputtered film is obtained by X-ray diffraction of the sputtered film, and the lattice constant is calculated from the diffraction peak. The X-ray was diffracted, and the width of the peak intensity of the (111) plane was measured to be half the angle, and the crystallinity was evaluated. Here, the crystallinity constant in Table 1 is represented by a relative value in which the crystallinity of No. 1 is 100, and the smaller value is more crystalline.

Further, the crystal grain size of the sputter film was also confirmed. The crystal grain size of the sputtered film was observed by TEM of the cross section of the sputtered film, and the diameter of the circle of a considerable area was taken as the crystal grain size by image analysis. In addition, the crystal grain size in Table 1 is represented by the relative value of the crystal grain size of No. 1 as 100, and the crystal grain size is finer as the numerical value is smaller.

Nos. 1 to 17 shown in Table 1 are examples of the invention, Nos. 18 to 21 are comparative examples, and Nos. 22 and 23 are reference examples.

As shown in Table 1, Comparative Example No. 18 did not contain W as a component, and thus the lattice constant was slightly lower. In Comparative Example No. 19, the W content as a component composition was high, and therefore the lattice constant was slightly higher. Comparative Example No. 20 did not contain Cr as a component, and thus the crystal grain size was coarse. In Comparative Example No. 21, since the Cr content as a component composition was high, the relative value of the particle constant was high and the crystallinity was low.

In Reference Example No. 22, since the curing temperature was low, the relative density was low. In Reference Example No. 23, since the solidification molding temperature was high, the billet after HIP was swollen, and it was difficult to process the sputtering target having a practically usable density, so that it was difficult to carry out investigation. On the other hand, in the examples of the present invention, Nos. 1 to 17 all conform to the conditions of the present invention, and therefore it is understood that each of the properties is excellent.

As described above, Cr is added to a conventional Ni-W binary component, whereby a film of fine crystal grains can be produced, and crystallinity can be maintained. Therefore, if the film is used as an intermediate layer to produce a perpendicular magnetic recording medium, good recording characteristics can be obtained.

Claims (7)

A sputtering target is a sputtering target used for manufacturing an interlayer film in a perpendicular magnetic recording medium, characterized in that the sputtering target is made of Ni-W-Cr alloy, which is in at% It contains 1 to 20% of W, 1 to 4% of Cr, and the residue is Ni. For example, in the sputtering target of claim 1, wherein the powder of the alloy composition is solidified and formed. The sputtering target according to the second aspect of the invention, wherein the curing molding is performed at 800 ° C or higher and 1250 ° C or lower. A Ni-W-Cr alloy film produced by using a sputtering target according to any one of claims 1 to 3. A method for producing a sputtering target, which is a method for producing a sputtering target for an interlayer film used in a perpendicular magnetic recording medium, characterized in that the method comprises: preparing for at%, containing 1~ 20% of W, 1-4% of Cr, and the work of the raw material powder composed of the alloy of the Ni-W-Cr alloy of the residual Ni; and the process of solidifying and forming the raw material powder. The method for producing a sputtering target according to the fifth aspect of the invention, wherein the curing molding is performed at 800 ° C or higher and 1250 ° C or lower. A Ni-W-Cr alloy film characterized by using a sputtering target manufactured by the method of claim 5 or 6 of the patent application scope Manufacturing.