JP2001076955A - Magnetic sputtering target and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deformation on an erosion shape by setting a maximum value and a minimum value within a specific range of an intermediate value regarding a magnetic characteristic of any one of a maximum permeability, a coercivity, and a squareness ratio on an initial magnetization curve, in a sputtering plane of a target. SOLUTION: In a magnetic target for magnetron sputtering, in a sputtering plate of a target, a maximum value and a minimum value of any one of a maximum permeability, a coercivity, and a squareness ratio on an initial magnetization curve are set within ±15% of an intermediate value. When the value is beyond the range, deformation appears on an erosion shape. Further, upon manufacturing ingot target, a predetermined magnetic material is dissolved and casted into an ingot, and undergoes hot casting or rolling. Furthermore, the material undergoes cold working and is formed into a plate, a target shape, and so on. Additionally, with hot and cold cross rolling, upsetting casting and the like, it is possible to achieve a target which is small in magnetic anisotropy in the sputtering plane and has isotropic deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sputtering target having a small magnetic anisotropy in a sputtering surface of a target and a small distortion of an erosion shape, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a method of forming a magnetic film on a magnetic recording medium for a hard disk, a magnetic head, an LSI chip, and the like,
Sputtering is widely used. In the sputtering method, a substrate serving as an anode and a target serving as a cathode are opposed to each other, and an electric field is generated by applying a high voltage between the substrate and the target under an inert gas atmosphere. The electrons and the inert gas collide to form a plasma, and the cations in the plasma collide with the target surface and strike out the target constituent atoms, and the ejected atoms adhere to the opposing substrate surface to form a film. It is based on the principle of being performed.

At present, most of the sputtering uses a method called magnetron sputtering. The magnetron sputtering method is a method in which a magnet is set on the back side of a target and sputtering is performed by generating a magnetic field on the target surface in a direction perpendicular to the electric field. In such an orthogonal electromagnetic field space, plasma is stabilized and densified. And the sputter rate can be increased.

In general, a magnetic thin film such as a ferromagnetic material or a ferrimagnetic material is formed on a substrate by using such a magnetron sputtering method. Magnetron sputtering captures electrons in a magnetic field and efficiently ionizes the sputter gas. However, when the target has magnetization, the target itself affects the magnetic field near the sputter surface due to the magnetic characteristics. When a target having a non-uniform magnetic property (having magnetic anisotropy) in the sputtering surface is used, the deepest portion of the erosion portion is distorted, and a predetermined film thickness distribution cannot be obtained. A target having magnetic anisotropy is likely to be generated particularly by a target rolled in one direction.

[0005] In particular, the rolled target material naturally has non-isotropic distortion. That is, the texture becomes a texture in which the crystal grains are extended in one direction. For this reason, when viewed three-dimensionally, it is often the case that anisotropy occurs in the magnetic properties even within the rolling plane. When a disk-shaped target is cut out from such a rolled plate to produce a target, a portion where an essentially circular erosion progresses has a shape extended in one direction. Originally, when a film was formed on a circular substrate, it was originally expected to form a circular erosion, so that a uniform film thickness on the circular substrate could not be achieved. Since the thickness of the film affects the magnetic properties, the uniformity of the film thickness is important, but the problem of this point has not been sufficiently solved.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems or disadvantages, and has an object to effectively reduce magnetic anisotropy due to working, to reduce distortion of an erosion shape, and to achieve stable operation. And a method for manufacturing the same.

[0007]

In order to solve the above-mentioned problems, the present inventor has focused on the manufacturing process of a sputtering target, and can easily reduce the magnetic anisotropy of a thin film by improving the processing process. It has been found that a magnetic thin film with good reproducibility and high quality can be obtained under stable manufacturing conditions. The present invention is based on this finding, the maximum value and the minimum value of any one of the magnetic properties of the maximum magnetic permeability, coercive force, squareness ratio on the initial magnetization curve within the sputtering surface of one target are:
The magnetic anisotropy is reduced by cross-rolling the magnetic target for magnetron sputtering and the target material for 2 sputtering, which is characterized by being within ± 15% of the intermediate value, to make isotropic strain. A magnetron in which the maximum value and the minimum value of any of the magnetic properties of the maximum magnetic permeability, coercive force, and squareness ratio on the initial magnetization curve in the sputtering surface of the target are within ± 15% of the intermediate value. A method of manufacturing a magnetic target for sputtering.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetron sputtering target of the present invention can be applied to a target for forming a magnetic thin film such as a ferromagnetic material or a ferrimagnetic material on a substrate, and is specified by the type of magnetic material (composition). Can be used extensively without The magnetron sputtering magnetic target of the present invention has a maximum permeability and a maximum coercivity on the initial magnetization curve, a maximum value and a minimum value of any one of the magnetic properties of the squareness ratio on the sputtering surface of the target, and an intermediate value between them. Is within ± 15%. If the value is out of the range of the numerical value, distortion of the erosion shape occurs.

For example, in the production of a smelting target, first, a predetermined magnetic material is cast into a melted block (ingot), which is hot forged or rolled, and then cold worked to form a flat plate or the like. Into a target shape that can be set in a magnetron sputtering apparatus.

[0010] Further, if the above-mentioned hot and cold, or in some cases, cold working is performed by, for example, cross rolling or upsetting forging, a target having an isotropic strain can be obtained. In this case, the cross-rolling is exclusively rolling in directions perpendicular to each other, but it can be rolling in directions other than right-angle, that is, multi-directional rolling. In addition, rolling can be performed by repeating this cross rolling. The term "cross rolling" as used in the present invention includes all of these.
In addition, although the anisotropy is further improved in the multi-direction cross rolling, the two-direction rolling is often sufficient as described above. As a result, a structure having a substantially uniform strain can be obtained, the magnetic anisotropy is reduced, the maximum magnetic permeability on the initial magnetization curve in the sputtering surface of the target,
A magnetic target for magnetron sputtering can be obtained in which the maximum value and the minimum value of any of the magnetic properties of the coercive force and the squareness ratio are within ± 15% of the intermediate value.

[0011]

Examples and comparative examples are described below based on examples and comparative examples. This embodiment is merely an example, and the present invention is not limited to this example. That is, the present invention is limited only by the claims, and includes various modifications other than the examples included in the technical idea of the present invention.

(Example) Using Ni and Fe having a purity of 99.99% or more as raw materials, a Ni-Fe alloy was vacuum-melted using a vacuum induction melting furnace. The composition of the melted product is Ni-20wt% F
e. After melting and casting the Ni—Fe alloy, the obtained ingot (170 × 200 × 30 t) was soaked (held at 1100 ° C. for 2 hours), and then hot rolled to 12 t. After hot rolling, rolling was performed at room temperature in two directions perpendicular to each other with a reduction in area of 43% in each direction. Samples were cut out from these hot-rolled sheets and used as magnetic targets.

(Comparative Example) As in Example, the purity was 99.9.
Using 9% or more of Ni and Fe as raw materials, a Ni-Fe alloy was vacuum-melted using a vacuum induction melting furnace. The composition of the melt is N
i-20 wt% Fe. After melting and casting the Ni—Fe alloy, the obtained ingot (170 × 200 × 30) was obtained.
t) was soaked (maintained at 1100 ° C. for 2 hours) and then hot-rolled to 12t. After hot rolling, unidirectional rolling was performed at room temperature with a reduction in area of 43%. Then, samples were cut out from these heat-treated plates to obtain disk-shaped magnetic targets.

Next, in order to measure the maximum magnetic permeability, coercive force and squareness of the sputtered thin films of Examples and Comparative Examples,
A film is formed on a disk-shaped substrate under the following sputtering conditions, and B
-H meter with 4πI coil, maximum magnetic field 100
The maximum magnetic permeability, coercive force and squareness were measured at 0 Oe. (Magnetron sputtering conditions) Deposition power 500 W / 3 inch diameter Ar pressure 0. Pa film thickness 25 nm Substrate temperature 280 ° C. The results are shown in Table 1.

[0015]

[Table 1]

In Table 1, the maximum value of the maximum magnetic permeability (μ) is 105 and the minimum value is 59.2 in the comparative example, and there are variations, whereas in the embodiment of the present invention, the maximum value is 231. The minimum value is 220, which is excellent in uniformity.
As for the coercive force, the maximum value was 1 in the comparative example.
While 4.0 Oe and the minimum value are 10.2 Oe, the maximum value is 5.0 Oe and the minimum value is 3.4 O in the embodiment of the present invention.
e, which is excellent in uniformity. Further, as for the squareness ratio, the maximum value was 0.0097 and the minimum value was 0.00 in the comparative example.
In contrast to 15, the maximum value is 0.0006 and the minimum value is 0 in the embodiment of the present invention, and the anisotropy of the magnetic properties is extremely small. Then, in the embodiment of the present invention, the maximum magnetic permeability on the initial magnetization curve in the sputtering surface of the target,
The condition that the maximum value and the minimum value of any of the magnetic properties of the coercive force and the squareness ratio are within ± 15% of the intermediate value is satisfied.

Next, the erosion shape of the disk-shaped target after the magnetron sputtering was measured. (Ideally a perfect circular erosion shape.) The results are shown in Table 2. As shown in Table 2, in the comparative example, the ratio of minor axis / major axis was 0.954. In contrast, the embodiment has the same ratio of 1. In the example, the erosion type anisotropy was reduced, which means that a uniform film was formed. In the present embodiment, the Ni-20 wt% Fe target, Ni-17 wt% Fe, and Ni-19 at% P have been described, but it has been confirmed that the same effect can be obtained with magnetic targets other than the above examples.

[0018]

[Table 2]

[0019]

According to the magnetic target for magnetron sputtering of the present invention, the target material for sputtering is subjected to cross-rolling so that distortion is isotropic,
As a result, the maximum value and the minimum value of any of the magnetic properties of the maximum magnetic permeability, coercive force, and squareness ratio on the initial magnetization curve in the sputter surface are within ± 15% of an intermediate value thereof, thereby forming the erosion shape. The magnetic sputtering target has a small distortion and can be stably manufactured, and has excellent characteristics to obtain a method for manufacturing the same.

Claims (2)

[Claims] 1. The maximum and minimum values of any one of the maximum magnetic permeability, coercive force, and squareness ratio on the initial magnetization curve within the sputtering surface of the target are within ± 15% of the intermediate value. A magnetic target for magnetron sputtering, characterized in that: 2. The method according to claim 1, wherein the target material for sputtering is cross-rolled to reduce isotropic anisotropy, thereby reducing magnetic anisotropy. A method for producing a magnetron sputtering target having a maximum value and a minimum value of any one of magnetic properties of a magnetic susceptibility, a coercive force, and a squareness ratio within ± 15% of an intermediate value thereof.