JP2624727B2 - Method for producing Co-Ni-Cr alloy target material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to, for example, the production of a Co—Ni—Cr alloy target material used for producing a magnetic recording medium such as a hard disk by a sputtering method, in particular, a magnetron sputtering apparatus. It is about the method.

[Conventional technology]

In general, in the magnetron sputtering method, a magnet is set on the back side of a target, and the magnetic field converges the plasma on the target surface at a high density, thereby greatly increasing the sputtering rate.

When this magnetron sputtering method uses a ferromagnetic material such as a Co-Ni-Cr alloy as a target material,
The magnetic flux generated from the magnet set on the back side of the target material is absorbed by the target, which is almost ferromagnetic, and there is little or no portion where the plasma is confined. Therefore, in this case, sputtering is performed only from a very limited narrow portion of the target material, so that sputtering efficiency is deteriorated and the target material is locally consumed.

Therefore, when a ferromagnetic material is used as a target material,
The target material may be magnetically saturated by using a magnet having a strong magnetic force so that the remaining magnetic flux must be leaked from the surface of the target material. However, even in this case, when the thickness of the target material is small, the target material is likely to be magnetically saturated, and there is no problem. No sputtering is performed.

[Problems to be solved by the invention]

Conventionally, a Co-Ni-Cr alloy target material is generally subjected to strain relief annealing of an ingot melted and cast in a vacuum induction furnace or a forged / rolled material obtained by hot working the ingot. After finishing, it was finished to predetermined dimensions by machining.

The target material manufactured from the ingot that is not subjected to the hot working tends to have a non-uniform etching property at the time of sputtering, and is particularly unsuitable for a large-scale target for mass production.
Further, the crystal grains also change as the sputtering progresses, and there is a problem that the sputtering speed varies over time. What solved a considerable part of these problems was a target material subjected to strain relief annealing after hot working such as forging and rolling.

However, even with such a target material, when the plate thickness is large as described above, the target material is hard to be magnetically saturated, and good sputtering cannot be performed.

An object of the present invention is to provide a method for producing a Co—Ni—Cr alloy target material that can perform good sputtering even when the plate thickness is large.

[Means for solving the problem]

As described above, in order to perform good sputtering by the magnetron sputtering method, it is necessary to generate a magnetic field due to a leakage magnetic flux on the surface of the target material, and for that purpose, measures such as using a strong magnet have been taken. ,
When the plate thickness is large, the target material is hardly saturated, and a sufficient magnetic field for performing good sputtering cannot be obtained.

In view of the above, the present inventor considers a state in which the magnetic flux hardly passes through the target material (passes only through the target material), in other words, the maximum magnetic permeability of the target material (hereinafter, μm
The present invention was completed by studying how to make the magnetic flux leak from the surface of the target material by reducing the magnetic field of the target material, thereby securing a magnetic field.

That is, in the present invention, after the above-described hot working and strain relief annealing, cold working is performed at a working rate of 10 to 70%, and then 600
C characterized by strain relief annealing in the temperature range of ~ 900 ° C
This is a method for producing an o-Ni-Cr alloy target material.

Cold working in the present invention has the effect of reducing μm. That is, μm is reduced by increasing the internal energy in the material, but cold working is performed to introduce internal strain in the target material, increase internal defects, and reduce μm. It is.

The larger the cold working ratio, the smaller the μm after cold working. However, the subsequent strain relief annealing reduces the internal strain due to the recovery phenomenon, so that μm increases. This recovery phenomenon is more likely to occur as the heat treatment temperature is higher, or at the same heat treatment temperature, as the number of defects introduced into the material is larger. Therefore, in order to obtain a desired low μm even after the strain relief annealing, it is necessary to set a certain upper limit for the cold working ratio. In the present invention, taking the above into consideration, the upper limit of the cold working rate is set to 70%, while the working rate is set to 10%.
If it is less than 10%, the effect of reducing μm cannot be sufficiently obtained.

 Next, the strain relief annealing will be described.

The fact that μm can be reduced by cold working is as described above, and it is needless to say that it is desirable to provide the target material as it is in cold working. However, in the state of cold working, deformation occurs when machining is performed to the desired shape and dimensions of the target material. Therefore, in the present invention, the strain relief annealing is performed after the cold working. If the temperature range is less than 500 ° C., the effect of removing strain is not sufficient, while if it exceeds 900 ° C., as described above, the internal strain recovery phenomenon becomes remarkable, so that the temperature range is 500 to 900 ° C. Note that the holding time of the heat treatment may be sufficient as long as the material is substantially soaked, and is arbitrarily selected according to the size of the target material. Cooling after heating may be performed by slow cooling, and furnace cooling or air cooling outside the furnace is employed.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

Example 1 30m / m x 200m / m x 400m of 62.5Co-30Ni-7.5Cr in atomic%
/ m sheet bar was manufactured by forging. This is 1130
After heating to 15 ° C. and hot rolling to 15 m / m × 400 m / m × 400 m / m, heat treatment was performed at 1130 ° C. × 15 minutes for straightening.

This is divided into four equal parts, and the area reduction rate is 10%, 30%, 50%, 70%,
Cold rolling was performed at room temperature until it reached 80%.

This as-cold-rolled material and its material are 600 ℃ × 1Hr
Grain size and hardness (Hv) of post-furnace cooled material
Is as shown in Table 1.

Further, the rings for μm measurement were machined from Nos. 1 to 4 in Table 1 and their characteristics were examined. The results are shown in FIG.

From FIG. 1, it is understood that the maximum magnetic permeability (μm) can be controlled to be low if the working ratio is in the range of 10 to 70%. In order to restrict the maximum magnetic permeability (μm) to a low value, a low processing rate should be selected in consideration of the strain relief annealing, but in this case, as shown in Table 1, there is an adverse effect on the sputtering characteristics. This is disadvantageous in that the crystal grains considered to be slightly coarser. Therefore, it is desirable to select a processing rate in consideration of this point as needed.

Example 2 A material subjected to hot rolling and heat treatment in the same manner as in Example 1 was cold-rolled at a working ratio of 50%, and heat-treated at various temperatures shown in Table 1.

Table 2 also shows the results of measurement of μm as in Example 1.

As heat treatment temperature increases, μm increases, 900 ° C
If it exceeds, the result is contrary to the object of the present invention.

〔The invention's effect〕

As described above, according to the present invention, the maximum magnetic permeability (μ
m) can be regulated low, so that even when the thickness of the Co—Ni—Cr alloy target material is increased, a magnetic field due to the leakage magnetic flux is ensured and good sputtering can be performed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the cold work rate after 600 ° C. × 1 Hr strain relief annealing and the maximum magnetic permeability.

Claims (1)

(57) [Claims] 1. Co-Ni characterized by performing strain relief annealing after hot working, then performing cold working at a working ratio of 10 to 70%, and then performing strain relief annealing at a temperature of 500 to 900 ° C. -A method for producing a Cr-based alloy target material.