WO2012023475A1

WO2012023475A1 - CrTi-BASED ALLOY AND SPUTTERING TARGET MATERIAL, PERPENDICULAR MAGNETIC RECORDING MEDIUM, AND PROCESSES FOR PRODUCING SAME

Info

Publication number: WO2012023475A1
Application number: PCT/JP2011/068290
Authority: WO
Inventors: 長谷川　浩之; 澤田　俊之
Original assignee: 山陽特殊製鋼株式会社
Priority date: 2010-08-17
Filing date: 2011-08-10
Publication date: 2012-02-23
Also published as: CN103119186B; CN103119186A; MY164775A; JP5734599B2; TW201221674A; TWI500791B; JP2012041585A

Abstract

The present invention provides: a CrTi-based alloy or sputtering target material which comprises 35 to 65at% of Ti with the balance consisting of Cr and unavoidable impurities; and processes for producing the same. The CrTi-based alloy or sputtering target material has an intensity ratio of [I(Cr₂Ti)/I(Cr)] of 0.50 or lower, wherein [I(Cr)] represents the X-ray diffraction intensity of Cr(110), and [I(Cr₂Ti)] represents the X-ray diffraction intensity of Cr₂Ti(311). According to the present invention, the content of compounds in a CrTi-based alloy or sputtering target material can be reduced, which makes it possible to suppress the generation of particles during sputtering and thus enhance the yield of sputtering film.

Description

CrTi-based alloy, sputtering target material, perpendicular magnetic recording medium, and production method thereof

Cross-reference of related applications

This application claims priority based on Japanese Patent Application No. 2010-182144 filed on Aug. 17, 2010, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a CrTi alloy, a sputtering target material, and a method for producing the same, in which the formation of a compound used for forming a thin film by sputtering is suppressed. The present invention also relates to a perpendicular magnetic recording medium manufactured using a CrTi-based alloy and a sputtering target material and a manufacturing method thereof.

Generally, a CrTi-based target is used as a base film of a perpendicular magnetic recording medium, and can be obtained by hot forming a pure Cr powder and a pure Ti powder. The CrTi target contains a lot of fragile compound phases, and the fragile compound phases generate particles during sputtering, and the particles adhere to the sputtered film, reducing the product yield. Therefore, it is necessary to reduce the compound in the CrTi target.

As a measure for reducing the compound in the CrTi target as described above, for example, as disclosed in Japanese Patent Publication No. 64-2659 (Patent Document 1), the molten metal is rapidly cooled to reduce the compound. . However, there is a problem that the CrTi target cannot be made into a molten metal by a material produced by powder metallurgy.

On the other hand, in the case of a normal powder sintered body, it is molded at a temperature of about 80% of the melting point. For example, as disclosed in Japanese Patent Laid-Open No. 2003-226963 (Patent Document 2) having a CrTi-based similar composition, it is molded at a temperature of 1200 ° C. or higher by hot pressing. Further, as disclosed in Japanese Patent Application Laid-Open No. 2002-212607 (Patent Document 3), molding is performed at a temperature of 1200 ° C. by an upset method. However, the higher the sintering temperature, the more the compound tends to increase.

These Patent Documents 2 and 3 both have a problem in that since the molding temperature is high, there are many compounds in the target, so that many particles are generated during sputtering and the product yield of the sputtered film is lowered.

Japanese Patent Publication No. 64-2659 JP 2003-226963 A JP 2002-212607 A

The present inventors have now obtained the knowledge that a CrTi-based alloy and a sputtering target material capable of reducing particles generated in a sputtered film can be provided by reducing the compounds in the sputtering target.

Therefore, an object of the present invention is to reduce the compounds in the CrTi-based alloy and the sputtering target material, and thereby suppress the generation of particles during sputtering and improve the product yield of the sputtered film.

According to one aspect of the present invention, there is provided a CrTi-based alloy containing 35 to 65 atomic% of Ti, the balance being Cr and inevitable impurities,
Strength of the CrTi alloy is 0.50 or less, Cr X-ray diffraction intensity of Cr ₂ Ti (311) with respect to the X-ray diffraction intensity [I (Cr)] of _{(110) [I (Cr 2} Ti)] A CrTi-based alloy is provided having a ratio [I (Cr ₂ Ti) / I (Cr)].

According to another aspect of the present invention, there is provided a sputtering target material comprising 35 to 65 atomic% of Ti, the balance being Cr and inevitable impurities,
Strength of the sputtering target material is 0.50 or less, Cr X-ray diffraction intensity of Cr ₂ Ti (311) with respect to the X-ray diffraction intensity [I (Cr)] of _{(110) [I (Cr 2} Ti)] A CrTi-based sputtering target material having a ratio [I (Cr ₂ Ti) / I (Cr)] is provided.

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

According to another aspect of the present invention, there is provided a method for producing the CrTi-based alloy or CrTi-based sputtering target material,
Preparing a raw material powder that provides the overall composition of the alloy;
There is provided a method comprising hot forming the raw powder at 800-1100 ° C.

According to another aspect of the present invention, there is provided a method for manufacturing the perpendicular magnetic recording medium,
Prepare a raw material powder that brings the overall composition of the base film,
The raw material powder is hot formed at 800 to 1100 ° C. to obtain a CrTi-based sputtering target material,
A method is provided comprising sputtering using the CrTi-based sputtering target material to form the underlayer.

Hereinafter, the present invention will be described in detail. The CrTi-based alloy according to the present invention, the CrTi-based sputtering target material, and the underlayer of the perpendicular magnetic recording medium are CrTi-based alloys containing 35 to 65 atomic percent of Ti (comprising), the balance being Cr and inevitable impurities, Preferably they consist essentially of these components, more preferably they consist only of these components. CrTi alloy and target material is 0.50 or less, Cr X-ray diffraction intensity [I (Cr ₂ Ti)] of X-ray diffraction intensity of the (110) Cr ₂ for [I (Cr)] Ti ( 311) Strength ratio [I (Cr ₂ Ti) / I (Cr)].

The underlayer of the CrTi alloy, the CrTi sputtering target material, and the perpendicular magnetic recording medium according to the present invention contains 35 to 65 atomic%, preferably 40 to 60 atomic% of Ti. When Ti is less than 35 atomic% or exceeds 65 atomic%, the film after sputtering does not become amorphous when the alloy is used as a sputtering target material.

The underlayer of the CrTi alloy, the CrTi sputtering target material, and the perpendicular magnetic recording medium according to the present invention has an X-ray diffraction of Cr ₂ Ti (311) with respect to the X-ray diffraction intensity [I (Cr)] of Cr (110). intensity [I (Cr ₂ Ti)] intensity ratio of _{[I (Cr 2 Ti) /} I (Cr)] is 0.50 or less, preferably 0.07 or less, more preferably 0.03 or less. When this intensity ratio is higher than 0.50, many particles are generated.

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

According to a preferred embodiment of the present invention, after the hot forming, the molded product is cooled at a cooling rate of 144 to 36000 ° C./hr from the hot forming temperature, whereby the effect of suppressing the formation of the compound can be further increased. In other words, the rapid cooling at the cooling rate maintains the CrTi solid solution in the high temperature phase to a low temperature and suppresses the solid solution from transforming into a compound. A preferable lower limit of the cooling rate is 500 ° C./hr or more.

In the perpendicular magnetic recording medium according to the present invention, as described above, the raw material powder is hot-formed at 800 to 1100 ° C., preferably 800 to 1050 ° C. to form a CrTi-based sputtering target material, and then the CrTi-based sputtering target material is used. Thus, it can be manufactured through sputtering to form a base film. The perpendicular magnetic recording medium manufacturing process other than the formation of the base film is not particularly limited as long as a conventionally used process is appropriately employed. According to a preferred aspect of the present invention, for the reasons described above, after hot forming, the target material is preferably cooled from the forming temperature at a cooling rate of 144 to 36000 ° C./hr prior to the sputtering. A preferable lower limit of the cooling rate is 500 ° C./hr or more.

Hereinafter, the present invention will be specifically described with reference to examples.

Pure Cr powder having a particle size of 250 μm or less and pure Ti powder having a particle size of 150 μm or less were blended in the Cr—Ti alloy composition shown in Table 1 and mixed. The obtained mixed powder was filled in a sealed can made of a steel material, and degassed and vacuum sealed at an ultimate vacuum of 10 ⁻¹ Pa or higher. Thereafter, in the case of HIP (hot isostatic pressing), after forming under conditions of heating temperature 800 to 1100 ° C., forming pressure 150 MPa, heating and holding time 1 hour, cooling rate to 300 ° C. under the conditions shown in Table 1 Is air-cooled (No. 3, 4, 5, 7, 11, 12, 13, 15, 16, 19, 21, 22, 23, 25, 29, 30, 31 and 33) or water-cooled (No. 8, 9, 17, 26, 27 and 34) to produce a molded body. On the other hand, in the case of the upset method, after molding under the conditions of a heating temperature of 800 to 1100 ° C., a molding pressure of 500 MPa, and a heating holding time of 1 hour, the cooling rate is controlled by air cooling or water cooling to 300 ° C. under the conditions shown in Table 1. A molded body was prepared. Next, the obtained molded body was machined to produce a target.

About the obtained target, the compound peak ratio [I (Cr ₂ Ti) / I (Cr)] was measured. This measurement was performed by X-ray diffraction under the condition that the X-ray source was Cu—Kα ray and the scan speed was 4 ° / min. In addition, for the evaluation of the particles, using the obtained target, a film was formed on an aluminum substrate having a diameter of 95 mm and a plate thickness of 1.75 mm by DC magnetron sputtering at an Ar gas pressure of 0.9 Pa, and the particles were subjected to an optical surface analyzer. Counted the number. These results were as shown in Table 1.

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

Comparative Example No. shown in Table 1 36, 38 and 40 were not evaluated because the density of the obtained powder compact was low because the molding temperature was low and the cooling rate was slow. Comparative Example No. Since 37, 39 and 41 all have a high molding temperature and a low cooling rate, the value of the X-ray diffraction intensity ratio is large and the number of particles is large. Comparative Example No. No. 42 was not evaluated because the density of the obtained powder compact was low because the molding temperature was low. Comparative Example No. No. 43 has a large X-ray diffraction intensity ratio and a large number of particles because the cooling rate after molding is slow.

Comparative Example No. No. 44 is not evaluated because the Ti content is low and the film after sputtering does not become amorphous. Comparative Example No. No. 45 is a comparative example No. 45 because of its high Ti content. Similar to 44, the film after sputtering is not evaluated because it does not become amorphous. On the other hand, No. which is an example of the present invention. Since 1 to 35 all satisfy the conditions of the present invention, it can be seen that the X-ray diffraction intensity can be suppressed to 0.5 or less and the number of particles is small.

As described above, the raw material powder according to the present invention is hot-molded in a temperature range of 800 to 1100 ° C., and if desired, after the hot molding, rapid cooling is performed at a cooling rate of 144 to 36000 ° C./hr from the molding temperature. It became possible to produce CrTi-based alloys and CrTi-based targets with a small amount of compound generation, and to improve the product yield of sputtered films.

Claims

A CrTi-based alloy containing 35 to 65 atomic percent of Ti, and the balance of Cr and inevitable impurities,
Strength of the CrTi alloy is 0.50 or less, Cr X-ray diffraction intensity of Cr 2 Ti (311) with respect to the X-ray diffraction intensity [I (Cr)] of (110) [I (Cr 2 Ti)] A CrTi-based alloy having a ratio [I (Cr 2 Ti) / I (Cr)].
The CrTi-based alloy according to claim 1, comprising only 35 to 65 atomic% of Ti, the balance Cr and unavoidable impurities.
A sputtering target material containing 35 to 65 atomic percent of Ti, the balance being Cr and inevitable impurities,
Strength of the sputtering target material is 0.50 or less, Cr X-ray diffraction intensity of Cr 2 Ti (311) with respect to the X-ray diffraction intensity [I (Cr)] of (110) [I (Cr 2 Ti)] A CrTi-based sputtering target material having a ratio [I (Cr 2 Ti) / I (Cr)].
The CrTi sputtering target material according to claim 3, comprising only 35 to 65 atomic% of Ti, the balance of Cr and inevitable impurities.
A perpendicular magnetic recording medium having a base film formed by sputtering using the CrTi-based sputtering target material according to claim 3.
A method for producing a CrTi-based alloy or a CrTi-based sputtering target material according to any one of claims 1 to 4,
Preparing a raw material powder that provides the overall composition of the alloy;
A method comprising hot forming the raw material powder at 800 to 1100 ° C.
The method according to claim 6, further comprising cooling the molded body from the molding temperature at a cooling rate of 144 to 36000 ° C / hr after the hot molding.
A method of manufacturing a perpendicular magnetic recording medium according to claim 5,
Prepare a raw material powder that brings the overall composition of the base film,
The raw material powder is hot-formed at 800 to 1100 ° C. to obtain a CrTi-based sputtering target material,
A method comprising sputtering using the CrTi-based sputtering target material to form the base film.
The method according to claim 8, further comprising cooling the target material from a molding temperature at a cooling rate of 144 to 36000 ° C / hr after the hot forming and prior to the sputtering.