JPS61113759A - Target for sputtering - Google Patents

Abstract

PURPOSE:To reduce the effective permeability of a plate having high permeability and high magnetic flux density by subjecting the plate to cold working such as cold rolling, surface machining or rough grinding so as to increase the coercive force or anisotropy. CONSTITUTION:Fe, Co or Ni having high permeability and high magnetic flux density is used as the material of a target for a prescribed magnetron sputtering gun. An alloy consisting of two or more among Fe, Co and Ni or an alloy contg. one or more among them may be used. A plate of the metal or alloy is subjected to cold working such as cold rolling, surface machining or rough grinding to deteriorate the soft magnetism of the plate and to prevent the transfer of the magnetic wall.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to magnetic recording media, shields for magnetic measuring instruments, etc.
The present invention relates to a sputtering target used when creating a thin film of a high magnetic permeability magnetic material used in the field of electronic equipment by a sputtering method.

Conventional technology Conventionally, magnetic materials with high magnetic permeability and high saturation magnetic flux density, such as permalloy (NiFe alloy) and sendust (Fe Si
A1 alloy) When forming thin films of pure iron, permendur (FeC0 alloy), etc. by sputtering method, general D
C(=RF bipolar sputtering had a slow film formation rate and was not suitable for practical use. As a solution to this problem, a magnetron sputtering method was developed, and it became possible to increase the film formation rate by about an order of magnitude compared to the conventional method.

However, in the magnetron sputtering method, as shown in the figure, the entire magnet 2 is placed below the target 1, and the film forming rate is increased by increasing the density of the plasma concentrated in the magnetic flux 3. For this reason, if the target 1 is made of a ferromagnetic material, especially a high magnetic flux density (B, A)', has a high magnetic permeability (μ) and a large plate thickness, the magnetic flux 3 will not be able to jump out onto the target 1, which will prevent sputtering. can't do it. Therefore, the high magnetic flux density BS and high magnetic permeability μ of target 1? Therefore, it was necessary to limit the thickness of the plate or reduce the total thickness of the plate to an extremely thin level.

Even if sputter discharge is possible by reducing the thickness of the target 1, if it is made of a material with high magnetic permeability, the magnetic flux 3 of the magnet 2 will be concentrated in one part, and this plasma cloud 4 will cause a part of the target 1 to be is rapidly eroded as shown in 5,
The life of target 1 ends when the erosion 5 reaches the back surface and holes are formed, resulting in a low utilization rate of target 1 and low production efficiency. It had problems that made it worse.

Therefore, the present invention reduces the effective magnetic permeability of a sputtering target made of a material with high magnetic flux density and high magnetic permeability, thereby slowing down the progress speed of the erosion depth, improving the effective utilization rate, and improving productivity. It is an object of the present invention to provide a sputtering target of a high permeability magnetic material that can achieve the following.

Means for Solving the Interstitial Point 1 The technical means of the present invention for solving the above problems is to improve the magnetic permeability of iron, cobalt, nickel, alloys of these metals, or alloys containing these metals. A sheet material having a high magnetic flux density is subjected to cold processing such as cold rolling, surface cutting, and rough polishing.

Effects The present invention can completely degrade the soft magnetism of the plate material with the above-mentioned configuration and obstruct domain wall movement, thereby reducing effective magnetic permeability by increasing coercive force, increasing anisotropy, and the like. On the other hand, the target is M8・μ・t=constant according to the ability of the lower magnet 2 (1
) The critical thickness is determined so that the following relationship holds true.

(However, MB: saturation magnetic flux density, μ: relative magnetic permeability, t: plate thickness) Therefore, if the magnetic flux density Ms is the same material, the magnetic permeability μ
The smaller t is, the larger the plate thickness t can be used. The magnitude of the magnetic permeability μ is also related to the spread of the plasma cloud in accordance with the spread of the magnetic flux, and as the magnetic permeability μ becomes smaller, the spatial spread of the plasma increases by 1.16'-
yt ``0 Erosion Area'' The island shape is also expanding. As a result, the depth of the eroded portion becomes shallower per unit power (including time) as the magnetic permeability μ decreases. Therefore, by completely reducing the effective magnetic permeability of the target as described above, the erosion can be made shallower.

Example Embodiments of the present invention will be described in detail below with reference to all the drawings.

78% Ni-Fe permalloy was used as the target 1 material for a given magnetron sputtering gun. Target 1 was produced by cutting this material into a flat plate using a standard milling cutter.

Comparing target 1 of this example with a conventional target obtained by hot rolling and slowly cooling the above material, the conventional target 1 has a saturation magnetic flux density of about 7600 Gauss, a magnetic permeability of 3000, and a 4Wn Whereas the plate thickness is the limit, the magnetic permeability of the target in this example drops to 760 (the coercive force increases to more than 10 Oe), and the plate thickness limit for use is 6.
．． It became 5 mm or more. As a result, when looking at the utilization rate 7 weight ratio until the service life of both targets 1, the conventional target 1 was 24%, while the target of this example increased to 36%.

As another example of the present invention, 78%Ni-Fe/:
- Malloy was heated to about 600°C with a burner, and then put into water and rapidly cooled. Then, since it was slightly warped, it was rolled again into a flat plate using a hammer. This embodiment and conventional target
As a result of using the target 1 formed with the same 4M plate thickness as the target 1, the usage efficiency of the target 1 of this example increased from 24% to 33% compared to the conventional target 1.

Further, in each of the above-mentioned Examples of the present invention, it was found that the erosion width of the target 1 after use was wider and the erosion depth was shallower than before treatment, and the effective utilization rate was increased.

The target material of the present invention is iron, cobalt, nickel, or an alloy of these metals.

Alternatively, materials with high magnetic permeability and magnetic flux density, such as alloys containing at least one kind of metal, are suitable.

Further, as the surface treatment of the target material, cold working treatments such as surface cutting, cold rolling, and rough polishing can be applied.

Effects of the Invention As is clear from the above explanation, according to the present invention, a plate material with high magnetic flux density and high magnetic permeability is subjected to cold processing, resulting in total deterioration of so-called soft magnetism and interference with domain wall movement. Magnetic permeability deteriorates due to increased coercive force, increased anisotropy, etc. As a result, when used as a magnetron target, it is possible to completely disperse the concentrated part of the magnetic flux, thus expanding the eroded part of the target to increase the erosion depth. It can be made shallower, and the efficiency of using the entire target can be improved. As the target usage time increases in this way,
This also reduces the number of times the vacuum chamber is fully opened, contributing to improved productivity of magnetic materials.

[Brief explanation of the drawing]

The figure is a top view of the magnetro/sputtering gun.
It is. 1... sputtering target, 2...
... Magnet, 3 ... Magnetic flux, 4 ... Plasma cloud, 6 ... Erosion part.

Claims (2)

[Claims] (1) A sputtering target characterized by having undergone cold processing such as cold rolling, surface cutting, and rough polishing on a plate material with high magnetic permeability and high magnetic flux density. (2) The plate material having high magnetic permeability and high magnetic flux density is iron, cobalt, nickel, an alloy of these metals, or an alloy containing these metals. Target for sputtering.