TWI500791B - CrTi alloy and sputtering target material, vertical magnetic recording medium and their manufacturing method - Google Patents

Description

CrTi alloy and target for sputtering, perpendicular magnetic recording medium and manufacturing method thereof Cross-reference to related applications

The present application claims priority on the basis of Japanese Patent Application No. 2010-182144 filed on Jan. 17, 2010, which is incorporated herein by reference.

The present invention relates to a CrTi-based alloy, a target for sputtering, and a method for producing the same, which are used for forming a thin film by sputtering, thereby suppressing formation of a compound. Moreover, the present invention also relates to a perpendicular magnetic recording medium produced using a CrTi-based alloy and a target for sputtering, and a method for producing the same.

Generally, a CrTi-based target system is obtained by using a base film of a perpendicular magnetic recording medium by thermoforming a pure Cr powder and a pure Ti powder. The CrTi-based target contains a brittle compound phase, and the brittle compound phase during sputtering causes particles, and the particles adhere to the sputtering film to lower the product yield. Therefore, it is necessary to reduce the compound in the CrTi target.

For example, as disclosed in Japanese Patent Publication No. Sho 64-2659 (Patent Document 1), the molten metal is rapidly cooled to reduce the compound. However, the CrTi-based target has a problem that it cannot be a molten metal when it is produced by a powder metallurgy method.

On the other hand, in the case of a powder sintered body, it is usually formed at a temperature of about 80% of the melting point. For example, a CrTi-based composition is formed at a temperature of 1200 ° C or higher by hot pressing as disclosed in JP-A-2003-226963 (Patent Document 2). Further, as disclosed in JP-A-2002-212607 (Patent Document 3), it is formed by a top forging method at a temperature of 1200 °C. However, the higher the sintering temperature, the more the compound tends to increase.

In these Patent Documents 2 and 3, since the molding temperature is high and the compound in the target is present in a large amount, many particles are generated during sputtering, and there is a problem that the product yield of the sputtering film is lowered.

Prior art document patent document

Patent Document 1: Japanese Patent Publication No. 64-2659

Patent Document 2: JP-A-2003-226963

Patent Document 3: JP-A-2002-212607

The present inventors have acquired the knowledge that a CrTi-based alloy and a sputtering target which can reduce particles generated in a sputtering film can be provided by reducing a compound in a sputtering target.

Therefore, the object of the present invention is to reduce the compound in the CrTi-based alloy and the sputtering target, and thereby suppress the occurrence of particles during sputtering, thereby improving the product yield of the sputtering film.

According to an aspect of the present invention, there is provided a CrTi-based alloy which contains 35 to 65 atom% of Ti, and the balance is a CrTi-based alloy composed of Cr and inevitable impurities.

The CrTi-based alloy has an intensity ratio of an X-ray diffraction intensity [I(Cr ₂ Ti)] of Cr ₂ Ti (311) to an X-ray diffraction intensity [I(Cr)] of Cr (110). (Cr ₂ Ti)/I(Cr)].

According to another aspect of the present invention, there is provided a CrTi-based sputtering target comprising a sputtering target comprising 35 to 65 atom% of Ti and the balance being Cr and inevitable impurities.

The sputtering target has an intensity ratio of an X-ray diffraction intensity [I(Cr ₂ Ti)] of Cr ₂ Ti (311) to an X-ray diffraction intensity [I(Cr)] of Cr (110). I(Cr ₂ Ti)/I(Cr)].

According to still another aspect of the present invention, a perpendicular magnetic recording medium having a base film formed by sputtering using the CrTi-based sputtering target is provided.

According to still another aspect of the present invention, there is provided a method of producing a CrTi-based alloy or a CrTi-based sputtering target, which comprises the following steps:

Preparing a raw material powder having the entire composition of the foregoing alloy,

The raw material powder was thermoformed at 800 to 1100 °C.

According to still another aspect of the present invention, there is provided a method of manufacturing the foregoing perpendicular magnetic recording medium, the method comprising the following:

Preparing a raw material powder having the entire composition of the base film described above,

The raw material powder is thermoformed at 800 to 1100 ° C to form a CrTi-based sputtering target.

The base film is formed by sputtering using the CrTi-based sputtering target.

[Formation of the Invention]

Hereinafter, the present invention will be described in detail. The CrTi-based alloy, the CrTi-based sputtering target, and the base film of the perpendicular magnetic recording medium of the present invention contain a CrTi-based alloy containing 35 to 65 atom% of Ti and the balance being Cr and inevitable impurities. Preferably, the composition is essentially the same, and more preferably consists of only such components. The CrTi alloy and the target have an intensity ratio of X-ray diffraction intensity [I(Cr ₂ Ti)] to Cr (110) X-ray diffraction intensity [I(Cr)] of Cr ₂ Ti (311) of 0.50 or less [I(Cr ₂ Ti)/I(Cr)].

The CrTi-based alloy, the CrTi-based sputtering target, and the base film of the perpendicular magnetic recording medium of the present invention contain 35 to 65 atom% of Ti, preferably 40 to 60 atom%. When Ti is less than 35 atom% or more than 65 atom%, when an alloy is used as a sputtering target, the film after sputtering does not become amorphous.

In the CrTi-based alloy, the CrTi-based sputtering target, and the base film of the perpendicular magnetic recording medium of the present invention, the X-ray diffraction intensity [I(Cr ₂ Ti)] of Cr ₂ Ti (311) is applied to Cr (110). The intensity ratio [I(Cr ₂ Ti)/I(Cr)] of the X-ray diffraction intensity [I(Cr)] is 0.50 or less, preferably 0.07 or less, more preferably 0.03 or less. When the intensity ratio is higher than 0.50, many particles are produced.

The CrTi-based alloy and the CrTi-based sputtering target of the present invention can be produced by thermoforming the raw material powder at 800 to 1100 ° C, preferably at 800 to 1050 ° C. If it is less than 800 ° C, sufficient density cannot be obtained. On the other hand, when the temperature exceeds 1100 ° C, the X-ray diffraction intensity ratio becomes large, and many particles are generated during sputtering, and the particles adhere to the sputtering film to lower the product yield. The hot forming temperature is preferably 1000 ° C or less in the upsetting method, and more preferably 900 ° C or less in the HIP method.

According to a preferred embodiment of the present invention, after the hot forming, the formed body is cooled from the hot forming temperature at a cooling rate of 144 to 36,000 ° C / hr, and the effect of suppressing the formation of the compound can be further increased. That is, since the rapid cooling is performed at the above-described cooling rate, the CrTi solid solution in the high temperature phase can be maintained at a low temperature, and the metamorphosis of the solid solution to the compound can be suppressed. A preferred speed of the lower limit of the cooling rate is 500 ° C / hr or more.

The perpendicular magnetic recording medium of the present invention can be formed by thermally forming a raw material powder at 800 to 1100 ° C, preferably at 800 to 1050 ° C, to become a CrTi-based sputtering target, and then using a CrTi-based sputtering target. It is produced by sputtering to form a base film. The manufacturing procedure of the perpendicular magnetic recording medium other than the formation of the base film can be suitably carried out by a conventionally used step, and is not particularly limited. According to a preferred embodiment of the present invention, for the foregoing reasons, it is preferred that after the hot forming, the target is cooled from a forming temperature by a cooling rate of 144 to 36,000 ° C/hr before the sputtering, and the cooling rate is at that time. The preferred speed of the lower limit is 500 ° C / hr or more.

Example

Hereinafter, the present invention will be specifically described by way of examples.

The Cr-Ti alloy composition shown in Table 1 was mixed with a pure Cr powder having a particle size of 250 μm or less and a pure Ti powder having a particle size of 150 μm or less. The obtained mixed powder was filled in a sealed can made of a steel material, and reached a vacuum degree of 10 ^-1 Pa or more, and was deaerated and vacuum-sealed. Then, when it is HIP (heat isostatic pressing), it is formed under the conditions of a heating temperature of 800 to 1100 ° C, a molding pressure of 150 MPa, and a heating retention time of 1 hour, and then, under the conditions shown in Table 1, to 300 ° C. Up to now, by air cooling (No. 3, 4, 5, 7, 11, 12, 13, 15, 16, 19, 21, 22, 23, 25, 29, 30, 31, and 33) or water cooling (No. 8, 9, 17, 26, 27 and 34) to control the cooling rate to produce a shaped body. On the other hand, in the case of the upsetting method, after forming at a heating temperature of 800 to 1100 ° C, a molding pressure of 500 MPa, and a heating retention time of 1 hour, the conditions shown in Table 1 were taken up to 300 ° C. The cooling rate is controlled by air cooling or water cooling to produce a shaped body. Next, the obtained molded body is subjected to mechanical processing to produce a target.

The peak ratio of the compound [I(Cr ₂ Ti)/I(Cr)] was measured for the obtained target. The X-ray source of this measurement was a Cu-Kα line, and X-ray diffraction was performed at a scanning rate of 4°/min. Further, the evaluation of the particles was carried out by using a target obtained on an aluminum substrate having a diameter of 95 mm and a thickness of 1.75 mm by DC magnetron sputtering at an Ar gas pressure of 0.9 Pa, by means of an optical surface analyzer ( Optical Surface Analyzer) to calculate the number of particles. The results of these are shown in Table 1.

As shown in Table 1, No. 1 to 35 are examples of the present invention, and Nos. 36 to 45 are comparative examples.

In Comparative Examples Nos. 36, 38, and 40 shown in Table 1, since the molding temperature was low, the cooling rate was slow, and the density of the obtained powder molded body was low, and was not evaluated. In Comparative Examples Nos. 37, 39, and 41, since the molding temperature was high and the cooling rate was slow, the value of the X-ray diffraction intensity was large, and the number of particles was large. In Comparative Example No. 42, the density of the powder molded body obtained by the low molding temperature was low, and was not evaluated. In Comparative Example No. 43, since the cooling rate after molding was slow, the value of the X-ray diffraction intensity ratio was large, and the number of particles was large.

In Comparative Example No. 44, since the Ti content was low, the film system after sputtering did not become amorphous, and was not evaluated. In Comparative Example No. 45, since the Ti content was high, in the same manner as in Comparative Example No. 44, the film system after the sputtering was not made amorphous, and was not evaluated. On the other hand, it is understood that Nos. 1 to 35 of the present invention can satisfy the conditions of the present invention, and can suppress the X-ray diffraction intensity to 0.5 or less, and the number of particles is small.

As described above, the raw material powder of the present invention can be produced by thermoforming at a temperature of 800 to 1100 ° C and rapidly cooling at a cooling rate of 144 to 36,000 ° C / hr at the self-forming temperature after the hot forming. A CrTi-based alloy and a CrTi-based target having a small amount of compound formation can improve the product yield of the sputter film.

Claims (9)

A CrTi-based alloy containing a CrTi-based alloy composed of 35 to 65 atom% of Ti and a balance of Cr and an inevitable impurity, and the CrTi-based alloy has an X-ray of Cr ₂ Ti (311) of 0.50 or less. The intensity ratio [I(Cr ₂ Ti)/I(Cr)] of the diffraction intensity [I(Cr ₂ Ti)] to the X-ray diffraction intensity [I(Cr)] of Cr(110). For example, the CrTi-based alloy of the first application of the patent scope is composed of only 35 to 65 atom% of Ti, the remainder of Cr, and inevitable impurities. A target for CrTi sputtering, which contains 35 to 65 atom% of Ti, and the remainder is a sputtering target composed of Cr and inevitable impurities, and the sputtering target has a Cr ₂ Ti of 0.50 or less. The intensity ratio of the X-ray diffraction intensity [I(Cr ₂ Ti)] of (311) to the X-ray diffraction intensity [I(Cr)] of Cr(110) [I(Cr ₂ Ti)/I(Cr)] . The target for CrTi sputtering according to item 3 of the patent application is composed of only 35 to 65 atom% of Ti, the remaining part of Cr, and inevitable impurities. A perpendicular magnetic recording medium having a base film formed by sputtering using a target for CrTi-based sputtering as disclosed in claim 3 or 4. A method for producing a CrTi-based alloy or a CrTi-based sputtering target according to any one of claims 1 to 4, wherein the method comprises the following steps: preparing to have a composition of the alloy The raw material powder is thermoformed at 800 to 1100 °C. The method of claim 6, further comprising cooling the shaped body from a forming temperature of 144 to 36,000 ° C / hr after the thermoforming. A method of manufacturing a perpendicular magnetic recording medium according to claim 5, which comprises the steps of: preparing a raw material powder having a total composition of the base film, the raw material powder being 800 to 1100 °C is thermoformed to form a CrTi-based sputtering target, and the CrTi-based sputtering target is used for sputtering to form the underlying film. The method of claim 8, further comprising cooling the target from a forming temperature of 144 to 36,000 ° C / hr before the sputtering.