JP2000309865A - Ni-P ALLOY SPUTTERING TARGET AND ITS MANUFACTURE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress abnormal electric discharge during sputtering, to prevent the formation and mixing of particles into a formed film, and further to effectively reduce or prevent target crack, or the like, during sputtering. SOLUTION: This Ni-P alloy sputtering target has a composition consisting of 12-24at% P, <=100 wt.ppm oxygen, and the balance Ni with inevitable impurities. The sputtering target can be manufactured by melting an Ni-P alloy ground metal of <=10 wt.ppm oxygen content, atomizing the resultant molten alloy in an inert-gas atmosphere to form an Ni-P alloy atomized powder of <=100 μm average particle size, and then applying hot press(HP) or hot isostatic press(HIP) to the powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to abnormal discharge during sputtering and mixing of particles during film formation, which are particularly useful for forming a Ni-P alloy film as a base film of a magnetic film of a recording medium such as a hard disk. The present invention relates to a Ni-P alloy sputtering target that can effectively reduce or prevent cracking of the target during sputtering, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in order to improve the recording density, a magnetic recording medium such as a magnetic disk (hard disk) has been replaced by a thin film recording medium formed by a sputtering method or the like instead of a conventional coating type magnetic recording medium. It has become increasingly used. As is well known, the sputtering method irradiates charged particles toward a target, strikes out the particles from the target by the particle impact force, and applies this from a target material to a substrate such as glass or aluminum opposed to the target. This is a film formation method for forming a thin film containing a constituent material as a basic component. Since the target material collides with and deposits on the substrate surface in a high energy state during sputtering, a dense film having high adhesion strength to the substrate can be formed. On the other hand, since the target receives a large amount of impact of charged particles, the amount of heat input to the target gradually increases and accumulates. For this reason, a material having good thermal conductivity (backing plate) such as pure copper or a copper alloy is joined to the back surface of the target by brazing or the like, and the backing plate is cooled through an external cooling means, and the heat of the target is cooled. So that it absorbs.

Before forming a magnetic film such as a cobalt alloy on a substrate, a non-magnetic film is formed in order to improve magnetic and electric characteristics and to provide uniformity. Conventionally, a chromium film or the like has been proposed as such a base film.
Attention has been paid to the fact that a -P alloy film can provide a recording medium having higher quality magnetic properties. However, since P is easily oxidized, oxygen contained in the Ni—P alloy sputtering target becomes 3000 ppm or more, and when sputtering is performed using this, a large amount of oxygen is present in the base film. Such a large amount of oxygen causes a problem that the magnetic film cannot be epitaxially grown and the coercive force is reduced. For this reason, the sintering powder is subjected to a reduction treatment in advance to reduce the oxygen content in the Ni-P alloy sputtering target to 2000 ppm or less (840 to 1980).
ppm) (JP-A-6-13652).
No. 6, JP-A-6-25842).

[0004] Similarly, when a sintering method is adopted instead of the production of a Ni-P alloy target by a melt casting method, and a Ni-P alloy base (amorphous) film is formed by sputtering, the heat during the production process is reduced. In order to prevent the Ni-P alloy film from being crystallized under the influence, the Ni-P alloy target is made to contain a high melting point metal such as Ti, Zr, Hf, Cr, Mo or W, and further sintered. It has been proposed to use atomized powder in order to improve the uniformity of the raw material powder mixture (Japanese Patent Application Laid-Open No. 7-292463).

[0005] It has been recognized that a Ni-P alloy film is effective as a base film before forming a magnetic film on a substrate to improve magnetic and electrical characteristics and to provide uniformity. However, a satisfactory film is not always formed by the above improvement. In particular, when sputtering is performed using a Ni-P alloy target, an abnormal discharge phenomenon is observed during sputtering, and particles that are considered to be the main cause are generated,
This is to be mixed into the Ni-P alloy film. The mixing of the particles causes deterioration of characteristics of a magnetic medium such as a hard disk and causes a reduction in product yield. In addition, as described above, the target is cooled through the backing plate during sputtering, but there is a problem that warping or cracking occurs due to a difference in thermal expansion between the target and the backing plate. Recently, indirect cooling types that do not use a backing plate have become the mainstream of HD sputtering machines, and in this case, the problem of cracking of the target has become more serious. Cracking or deformation of the target makes the film unstable, leading to a serious problem of insufficient film formation.

[0006]

SUMMARY OF THE INVENTION The present inventors have developed a Ni-P alloy sputtering target which is useful for forming a target, particularly a Ni-P alloy film used as a base film of a magnetic film as a recording medium such as a hard disk. It is an object to suppress abnormal discharge during sputtering, prevent generation and mixing of particles during film formation, and further effectively reduce or prevent target cracking and the like during sputtering. .

[0007]

The present invention provides (1) P12
Ni-P alloy sputtering target characterized in that the content of oxygen is 100 wtppm or less, and the balance is composed of Ni and unavoidable impurities. (2) The oxygen content is 50 wtppm or less. (1) Ni-P alloy sputtering target according to (1), (3) a structure in which Ni and Ni ₃ P coexist in a 200 μm square area, and the cross-sectional area size of one Ni grain is 1
(1) The Ni-P alloy sputtering target according to the above (1) or (2), which has a uniform microstructure of ² or less, and (4) the content of Al, Si, Mg, and Mn as impurities is 10 wtppm or less, respectively. The Ni-P alloy sputtering target according to each of the above (1) to (3), (5) 5 MPam ^1/2
The Ni-P alloy sputtering target according to any one of (1) to (4), having the above-mentioned fracture toughness (SEVNB method) (6) Oxygen content of 10 wtp
pm or less is melted and atomized in an inert gas atmosphere to obtain a Ni-P alloy atomized powder having an average particle size of 100 μm or less, and then hot pressed (HP) or hot static Characterized by hydraulic pressing (HIP) processing, P12-24at%, oxygen content 100w
The present invention provides a method for producing a Ni-P alloy sputtering target which is not more than tppm, the balance being Ni and unavoidable impurities.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The abnormal discharge phenomenon during sputtering, the generation of particles which are considered to be the main cause thereof, and the cause of crack generation during sputtering are investigated.
It has been found that it is caused by a trace amount of oxide contained in the -P alloy sputtering target. Also, the problem of the strength of the target that causes cracking during sputtering,
It was found that the cause was due to the oxide locally present in the target and the internal pores. As shown in the above prior art, the oxygen contained in the Ni-P alloy sputtering target becomes 3000 ppm or more because P is easily oxidized, and in order to improve this, it is contained in the Ni-P alloy sputtering target. Oxygen content of 200
It has been proposed that the content be 0 ppm or less (840 to 1980 ppm).

However, it has been found that such a problem cannot be solved at all at such an oxygen level. Ni
Although the manufacturing method itself for making the -P alloy sputtering target low in oxygen is a difficult step that cannot be realized by a conventional ordinary sintering method, it is necessary to be aware of a defect in film formation caused by such oxygen. . Unfortunately, this has not been achieved in the prior art. That is, in the Ni-P alloy sputtering target composed of 12 to 24 at% and the balance of Ni, the problem was solved only when the oxygen content as an impurity was less than 100 wtppm. More desirably, the oxygen content is less than 50 wtppm. The lower limit of 12 at% of P requires non-magnetic property of film formation, and the content of P equal to or more than the lower limit is necessary to maintain the hardness and strength of the sputtering target and the film formation. However, the upper limit value exceeds P24at% adhesion strength is lowered to the substrate, if cause problems such as peeling by, also for example the upper limit P24at% of Ni-25 at% P in very brittle _Ni 3 P exceeds Since it is a single phase, there is a high possibility that a serious trouble will occur in sputtering film formation. From the above, the upper limit is P24
at%.

In the above prior art, the Ni-P alloy target contains a high melting point metal such as Ti, Zr, Hf, Cr, Mo, W, etc. to prevent crystallization of the Ni-P alloy film due to thermal influence during the manufacturing process. However, there is an example in which the component system is increased, so that the component control in the alloy manufacturing process becomes complicated, and it is easy to take in oxygen to generate oxides. There is also the problem of raising the overall oxygen level, which is not always a good idea. As shown in the present invention, the content of oxygen as an impurity is set to 100 wtppm or less, and particularly, the content of oxygen is set to 50 wtppm or less, thereby stabilizing a sputtering film formation using a Ni-P alloy target and forming an underlying film. The Ni-P alloy thin film has an excellent feature of having a uniform and dense structure.

Further, the Ni—P alloy sputtering target of the present invention has a structure in which Ni and Ni are contained within a 200 μm square area.
It is desirable to have a structure in which ₃ P coexists and a uniform fine structure in which the cross-sectional area size of one Ni grain is 15000 μm ² or less. This makes it possible to use a stable Ni-P film that can be used as a base film of a magnetic film as a recording medium such as a hard disk.
An alloy film is obtained. Furthermore, in order to maintain stable sputtering, the target needs to have an appropriate strength to prevent cracking, and preferably has a fracture toughness of 5 MPam ^1/2 or more. In addition, it is desirable that the impurity contents of Al, Si, Mg, and Mn that are mixed with the Ni-P alloy and easily form an oxide in the alloy at the same time as reducing oxygen as much as possible are 10 wtppm or less.
Conventionally, such oxides have been present in the target and have been overlooked. In particular, when they are localized, abnormal discharge of unknown cause occurs, causing the generation and cracking of particles. By reducing these, the occurrence of these defects was significantly reduced.

In the present invention, high-purity N with reduced oxygen is used.
The production of the i-P alloy sputtering target is based on the powder sintering method. First, Ni- with an oxygen content of 10 wtppm or less
A P alloy ingot is prepared and melted. Next, this high purity N
The i-P alloy melt is sprayed, rapidly cooled, and solidified in an atmosphere of an inert gas such as argon, helium, nitrogen gas, etc., so-called atomizing, and N 2 having an average particle diameter of 100 μm or less is used.
Produce i-P alloy atomized powder. The atomized powder of the present invention has a substantially spherical shape, and the specific surface area can be minimized. As a result, the uptake of oxygen can be suppressed, and even if the oxygen content increases, 40 wtp.
pm or less.

Next, using this atomized powder,
Press (HP) or hot isostatic press (HIP)
You. 750 ° C ~ 850 ° C for hot press (alloy
Has a melting point of 870 ° C.
100) to 300 kgf / cm ², 30 minutes to 5 hours
Under the conditions described below. Also, in the case of hot isostatic pressing,
750 to 850 ° C, 1000 to 1500 kgf /
cm²For 30 minutes to 5 hours. By this
And P12-24at%, oxygen content is 100wtpp
m or less, and the balance of Ni and inevitable impurities
An i-P alloy sputtering target material is obtained.
This is further cut into target shapes, ground and polished,
Perform normal processing such as bonding to the king plate,
Obtain a high-purity Ni-P alloy sputtering target.

[0014]

Embodiment 1 Next, a description will be given based on an embodiment of the present invention. The following embodiment is merely an example, and the present invention is not limited to this example. That is, the present invention includes other aspects or modifications included in the technical idea of the present invention. Dissolve a Ni-P alloy ingot having an oxygen content of 10 wtppm or less. Next, using the gas atomization method,
Atomized powder was obtained after the Ni-19atP alloy. The atomized powder is almost spherical and has an oxygen content of 30 wt.
ppm. The specific surface area of the raw material powder is 0.0
At 1 m ² / g, the apparent density was 5.2 g / cm ³ . Next, the atomized powder was filled in a mild steel capsule and then vacuum-sealed, at 830 ° C., 1500 kgf / cm ² ,
The hot isostatic pressing was performed under the condition of 2 hours.

The resulting Ni-19 at% P
Has a density of 99% or more and an oxygen content of 40 wt.
ppm. This sintered body has a uniform fine structure.
In the 200 μm square area, Ni and Ni ₃P coexists
And the cross-sectional area size of Ni particles is about 10,000μm²Within
It was good. Next, this Ni-P alloy sintered body
Sputtering using the target prepared from
P oxide amount (pcs / 500mm²), Fracture toughness (SEV
NB method), adjust the number of abnormal discharges, and the amount of generated particles
Solid. The amount of P oxide is about 100 mm²Polishing sump
This is the result of preparing five samples and confirming with EPMA. under
The same investigation was performed in the comparative examples described above. Table showing the above results
It is shown in FIG.

[0016]

[Table 1]

[0017]

Comparative Example 1 Next, Comparative Example 1 will be described. Dissolve a Ni-P alloy ingot having an oxygen content of less than 10 wtppm. Next, using a water atomizing method, Ni-19at
Atomized powder was obtained after the P alloy. Atomized powder cannot be produced in a sufficiently spherical shape, and the oxygen content is 1100 w
tppm. Further, the specific surface area of the raw material powder is 0.1.
In 04m ² / g, apparent density 4.0 g / cm ^3, average particle diameter was about 100 [mu] m. Next, this atomized powder was filled in a mild steel capsule and then vacuum sealed, and 830 °
C, hot isostatic pressing was performed under the conditions of 1500 kgf / cm ² and 2 hours. The Ni-19a obtained by this
The sintered body of t% P has a density of 99% or more and an oxygen content of 8%.
It was 60 wtppm. As in Example 1, this Ni
Sputtering is carried out using the target prepared from -P alloy sintered body, P oxide content (pieces / 500 mm ^2), the fracture toughness value, the number of abnormal discharge was examined generation of particles. The results are shown in Table 1 in comparison with the examples.

[0018]

Comparative Example 2 Next, Comparative Example 2 will be described. Dissolve a Ni-P alloy ingot having an oxygen content of less than 10 wtppm. Next, using a water atomizing method, Ni-19at
Atomized powder was obtained after the P alloy. Although the atomized powder was substantially spherical, the oxygen content was 210 wtppm. The specific surface area of this raw material powder was 0.01 m ² /
g, the apparent density is 4.8 g / cm ³ , and the average particle size is about 1
It was 00 μm. Next, this atomized powder was filled in a mild steel capsule and sealed in a vacuum.
Hot isostatic pressing was performed under conditions of gf / cm ² and 2 hours. The Ni-19at% P sintered body thus obtained has a density of 99% or more and an oxygen content of 220 wtpp.
m. In the same manner as in Example 1, sputtering was performed using a target manufactured from this Ni-P alloy sintered body, and the amount of P oxide (pieces / 500 mm ² ), the fracture toughness value, the number of abnormal discharges, and the amount of generated particles were determined. Examined. The results are similarly shown in Table 1 in comparison with the examples.

As is apparent from Table 1, the oxygen content is 30%.
In Example 1 in which the content was wt ppm, no P oxide was confirmed (absent), and the fracture toughness value was 5.0 MPam ^1/2 ,
No problematic abnormal discharge occurs and no particles are generated. On the other hand, the oxygen content of 860 wtp
pm in Comparative Example 1, 23 P oxides / 500 mm
² , the fracture toughness value is as low as 4.4 MPam ^1/2 ,
In addition, the occurrence of abnormal discharge and particles increases to a degree that causes a problem in production. Similarly, Comparative Example 2 which is less than Comparative Example 1 but still contains as much as 220 wtppm oxygen
In this case, there are 6 P oxides / 500 mm ² , the fracture toughness value is as low as 4.4 MPam ^1/2, and the occurrence of abnormal discharge and particles is so large as to be a problem in production.

As is clear from the above comparison, there is a difference in the amount of P oxide, the fracture toughness, the number of abnormal discharges, and the amount of particles in Examples and Comparative Examples, which depend on the oxygen content of the target. it is conceivable that. The number of abnormal discharges and the amount of particles are considered to depend particularly on the amount of P oxide. In order to avoid these, the oxygen content should be 100 wtppm or less, preferably 5 wtppm.
It is necessary to make it 0 wtppm or less. Furthermore, oxygen is contained in a large amount (1000 wtppm or more), and Al, Si,
In a Ni—P alloy target containing Mg and Mn, Al ₂ O ₃ , SiO ₂ , MgO, MnO, and the like are present in the target, which is a major problem in HD production. Fracture toughness is also improved by reducing oxygen. This is considered to be caused by the P oxide localized inside the target, and means that the localized portion of the P oxide is materially defective. Therefore, Ni-
Reducing the oxygen content of the P alloy target is extremely important in preventing cracking during target processing and sputtering.

[0021]

As described above, according to the present invention, the content of oxygen, which is an impurity in a Ni-P alloy sputtering target, is reduced to 10%.
0 wtppm or less, especially the oxygen content is 50 wtp
pm or less, Ni-P used especially as a base film of a magnetic film as a recording medium such as a hard disk.
It is useful for forming an alloy film, suppresses abnormal discharge during sputtering, prevents generation and mixing of particles during film formation, and effectively reduces or prevents target cracking and the like during sputtering. Can be. Also,
As a result, the coercive force of the magnetic film of the recording medium is improved, and an excellent effect of high fracture toughness is obtained.

Claims (6)

[Claims] 1. P12 to 24 at%, oxygen content is 10
A Ni-P alloy sputtering target, which is 0 wtppm or less, the balance being Ni and unavoidable impurities. 2. The Ni-P alloy sputtering target according to claim 1, wherein the oxygen content is 50 wtppm or less. 3. Ni and Ni ₃ in a 200 μm square area.
^2. A microstructure in which P has a coexisting structure and a uniform fine structure in which one Ni grain has a cross-sectional area size of 15000 μm ² or less.
Or the Ni-P alloy sputtering target according to 2. 4. Al, Si, Mg and Mn as impurities
The Ni-P alloy sputtering target according to any one of claims 1 to 3, wherein the content of each is 10 wtppm or less. 5. The Ni—P alloy sputtering target according to claim 1, which has a fracture toughness value of 5 MPam ^1/2 or more. 6. A Ni— alloy having an oxygen content of 10 wt ppm or less.
A P alloy ingot is melted and atomized in an inert gas atmosphere to obtain a Ni-P alloy atomized powder having an average particle diameter of 100 μm or less, and then hot pressed (HP) or hot isostatic press (HIP). P12 characterized by processing
A method for producing a Ni-P alloy sputtering target having a content of up to 24 at%, an oxygen content of not more than 100 wtppm, and a balance of Ni and unavoidable impurities.