JPS63199844A - Chromium alloy for target of sputtering and its production - Google Patents

Abstract

PURPOSE:To produce a Cr alloy for the target of sputtering at lower production cost by dissolving and casting the alloy formed by incorporating a specific ratio of Fe into Cr to make an ingot and finishing the ingot by mechanical working. CONSTITUTION:The alloy contg. 3.0-30.0wt.% Fe and the balance consisting of Cr is dissolved and cast in an inert gas to produce the ingot. Said ingot is then finished by the mechanical working to make it the Cr alloy for the target of sputtering. The toughness of the alloy is improved as well as the lowering of the melting point of Cr, and the production cost is lowered by the above-mentioned manner.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a chromium alloy used as a sputtering target and a method for producing the same, and particularly relates to a chromium alloy that reduces production costs by adding iron to chromium. This article relates to alloys and their manufacturing methods.

(Prior Art) Recently, sputtering has been used in various fields as a technique for producing thin films used in magnetic recording media and the like. The above sputtering is usually carried out using a sputtering apparatus, an example of which is shown in FIG. That is, there is a target 1, an aluminum substrate 2, and a copper plate 3 inside it.
, magnets 4a, 4b, Ar gas is introduced into the vacuum container 5 to cause a glow discharge, and the Ar cations obtained by the discharge are made to collide with the target, which is the ○ pole, and the kinetic energy causes the target to Sputtering is performed by evaporating metal atoms in a vacuum and depositing them on a substrate, which is the pole.

Various materials such as pure metals, alloys, and ceramics are used as the target depending on the purpose of the thin film to be obtained, and chromium thin films have recently been attracting attention in particular for use as underlayers in magnetic recording media. That is, in a magnetic recording medium having a cobalt or cobalt alloy magnetic thin film on an aluminum substrate, when chromium is sputtered as a cobalt or cobalt alloy underlayer, the (110) plane of the chromium crystal (body-centered cubic lattice) grows parallel to the substrate. By sputtering cobalt or a cobalt alloy as a magnetic material onto this surface, epitaxial growth occurs such that the C axis, which is the axis of easy magnetization of cobalt or cobalt alloy (close-packed hexagonal lattice), is parallel to the substrate surface. Magnetic properties within the substrate plane of the magnetic recording medium are improved.

The sputtering using the chromium target further includes:
It is used in various applications such as heat ray shielding in building window glass, extending the life of razor blades, metalizing plastics for decorative items such as toys and interior decoration, and greatly contributes to improving the surface properties of materials. are doing.

As a chromium target for sputtering,
Conventionally, pure chromium produced using a powder sintering method was used.

[Problem that the invention seeks to solve]

As mentioned above, chromium for sputtering targets is widely used for various purposes and contributes greatly to improving the magnetic properties and surface properties of materials, but pure chromium, which has been used conventionally, Due to its high melting point and brittleness,
It is prone to cracking during melting and casting, and hot working is difficult, so conventionally it has been manufactured using a powder sintering method. Therefore, the target itself is expensive, and it has been desired to develop a low-cost ROM target.

[Means for solving problems]

The present invention was made in view of the above points, and its purpose is to lower the melting point of chromium and improve its toughness, thereby making it possible to manufacture a chromium target by melting and casting. The goal is to reduce costs. That is, the present invention uses 3.0 to 30.0 wt of iron.
%, the balance being chromium, and a method for producing the same.

[Effect]

The present inventor searched for various additive elements that could lower the melting point of chromium and increase its toughness without significantly changing the crystal structure of chromium, and found that iron was the best.

That is, by adding iron to chromium, the melting point of chromium is lowered and its toughness is increased, so that cracks do not occur during melting and casting, making it possible to obtain a sound ingot.

Furthermore, since the toughness of chromium is increased, hot plastic working of the ingot produced by the above-mentioned melting and casting process can be easily carried out. Furthermore, by using a Cr-Fe alloy in which iron is added to chromium, the toughness of the target material can be increased, and even if the sputtering speed is increased, the target will not crack, thus greatly increasing the productivity of magnetic recording media. can be improved. Also, iron has the same body-centered cubic lattice as chromium at room temperature, and the lattice constants are almost the same, so Cr-Fe
When sputtering a cobalt-based material onto an alloy substrate, epitaxial growth is not inhibited so that the C-axis of cobalt is parallel to the substrate surface, which is almost equivalent to sputtering a cobalt-based material onto pure chromium. magnetic properties can be obtained.

In the present invention, the amount of iron added to the Cr-Fe alloy for targets is limited to within the range of 3.0 to 30.0 wt% because
If it is less than 3.0 wt%, the melting point will be insufficiently lowered and the toughness will be increased insufficiently, making it difficult to obtain a sound ingot during demolding or casting. This is because when used as a geological formation, the chromium alloy becomes magnetic and causes noise.

The Cr--Fe alloy of the present invention needs to be melted in an inert gas such as Ar to prevent oxidation of chromium and iron, but casting can be carried out using an ordinary water-cooled mold. Further, the Cr-Fe alloy of the present invention can be subjected to hot plastic working by rolling, forging, etc., but cracks may occur during hot rolling, so it is recommended to cover the alloy with a steel plate, such as a stainless steel plate, before rolling. is desirable.

[Example 1] Examples of the present invention will be described below.

As shown in Table 1, iron was added to chromium in an amount of 0 to 35 wt%, and after high-frequency melting in Ar gas at 0.65 atm, the product was cast into an iron mold, 15 mm thick, 220 mm thick, and 220 mm long. Obtained an ingot. Table 1 shows the results of measuring the total length of cracks observed on the surface of these ingots. Next, these ingots are machined to
A disk having a thickness of 6ffi11 and a diameter of 200 mm was finished, and it was set in a magnetron sputtering apparatus shown in FIG. 1 and used as a target. In Figure 1, l is the target, 2 is the aluminum substrate, 3 is the rope plate, 4
as 4b is a magnet, and 5 is a vacuum container. Diameter 5, 2
After mirror-polishing a 5-inch aluminum substrate 2, N1-P electroless plating was applied as a first base layer, and the Cr-Fe alloy target 1 was used as a second base layer on top of the plate. ．． I was sputtering. The highest sputtering speed at which sputtering could be performed without cracking the target is also listed in Table 1.

Then, on the chromium alloy base layer, 30 at% of Co was added.
A magnetic recording medium was obtained by sputtering N + -7,5 at% Cr alloy with O, 1 m, and then sputtering C as a protective film with O, aS-. Table 1 also shows the results of measuring the relocation force of the magnetic recording medium at 2.5 KHz on the outermost track.

Table 1 As is clear from Table 1, 3.0 to 30.0 wt of iron is
Inventive example Nα in which a Cr-Fe alloy containing % was melted and cast.
Nos. 1 to 7 are comparative examples in which Cr-Fe alloys were melted and cast, which hardly caused cracks in the ingot during melting and casting, but the amounts of pure chromium and iron added were smaller than the claimed range of the present invention.
No. 9 has large cracks in the ingot.

In addition, in the present invention examples Nα1 to 7 in which a Cr-Fe alloy containing 3.0 to 30.0 wt% iron was used as a target, in the comparative example Nα8 in which a pure chromium casting was used, and in the powder sintering method from pure chromium, Sou 11, whose target was manufactured by
Compared to the conventional example, the sputtering speed on the aluminum substrate is significantly faster. In addition, the above Nα1 to 7
shows a reproduction output that is almost the same as Nα11 made by sputtering pure chromium, and its magnetic properties are also almost the same as those of the conventional example. On the other hand, Comparative Example Nα10, in which the amount of iron added is smaller than the claimed range of the present invention, has a sputtering rate not higher than that of conventional example N Compared to Nα11, the sputtering speed is faster, but the reproduction output is lower.

[Example 2] Adding 5% and 25% iron to chromium and adding 5% and 25% iron to 0.5 atm A
After high-frequency melting in r gas, the ingot was cast into a graphite water-cooled mold to form an ingot with a diameter of 200+ma and a length of 700aI, and no cracks were observed on the surface of the ingot.

In addition, the above ingot was machined to a thickness of 6III11.
When a disk with a diameter of 200M was finished and used as a target by setting it in a magnetron sputtering device in the same manner as in Example 1, the sputtering speed was higher than when using a conventional pure chromium target (sintered crystal powder). It was fast, and the playback output was about the same as before.

[Example 3] Adding 3% and 20% iron to chromium and adding 3% and 20% iron to 0.5 atm A
After high-frequency melting in r gas, it was cast into a graphite water-cooled mold to form an ingot with a thickness of 10 hw and a width of 25011111% and a length of 700 m. No cracks were observed on the surface of the ingot. Next, the ingot was covered with a stainless steel plate having a thickness of 1 rm, homogenized annealed at 950° C. for 24 hours, and then hot rolled to a low thickness.

When the above-mentioned hot-rolled sheet was milled by about 0.31 mm on one side and the coating layer of the stainless steel sheet was removed, no defects such as cracks were observed on the surface of the hot-rolled sheet.

The hot-rolled plate was cut into pieces 200 m wide and 200 g long, set in a magnetron sputtering device in the same manner as in Example 1, and used as a target. The sputtering speed was faster than in the conventional case, and the reproduction output was about the same as that of the conventional method.

〔Effect of the invention〕

By adding iron to chromium as described above, it becomes possible to manufacture a chromium target by melting and casting, and the manufacturing cost of the chromium target can be reduced.

Furthermore, by using a Cr--Fe alloy in which iron is added to chromium, the sputtering speed when sputtering chromium can be significantly increased, and the productivity of magnetic recording media and the like is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetron sputtering apparatus used in the present invention. l...Target 2...Aluminum substrate 3.
...Copper plate 4a...Magnet 4b...Magnet 5.
・・Vacuum container

Claims (3)

[Claims] (1) A chromium alloy for use in sputtering targets, characterized by comprising 3.0 to 30.0 wt% iron and the balance chromium. (2) An alloy having an alloy composition of 3.0 to 30.0 wt% iron and the balance chromium, characterized by producing an ingot by melting and casting in an inert gas, and finishing the ingot by machining. A method for producing a chromium alloy for sputtering targets. (3) An alloy with an alloy composition of 3.0 to 30.0 wt% iron and the balance chromium, characterized by producing an ingot by melting and casting in an inert gas, and subjecting the ingot to hot plastic working. A method for producing a chromium alloy for sputtering targets.