JP2006181887A - GaSb PHASE CHANGE TYPE RECORDING FILM EXCELLENT IN SHELF STABILITY OF RECORDING MARK AND SPUTTERING TARGET FOR FORMING THIS GaSb PHASE CHANGE TYPE RECORDING FILM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GaSb phase change type recording film which is used for various phase change type recording media such as CD and DVD and excellent in the shelf stability of a recording mark, and a sputtering target for forming the GaAs phase change type recording film. <P>SOLUTION: The phase change type recording film contains Ga of 4 to less than 20% and further one or two or more kinds out of In, Sn and Bi of 0.2 to less than 5% in total, and the residual part of the film consists of an Sb group alloy having a composition of Sb and inevitable impurities. The target contains Ga of 5 to less than 20% and further one or two or more kinds out of In, Sn and Bi of 0.2 to less than 5% in total, and its residual part consists of the Sb group alloy having the composition of Sb and the inevitable impurities. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a GaSb phase change recording film excellent in storage stability of recording marks used for various phase change recording media such as CD and DVD, and a sputtering target for forming the GaSb phase change recording film. It is about.

In general, a recording film used in a recording medium such as a CD or a DVD that records, reproduces, and erases information by using a reversible phase change between an amorphous phase and a crystalline phase caused by light beam irradiation includes Ga- An Sb binary eutectic phase change recording film may be used. Among them, a Ga-Sb binary phase change recording film having a Ga ₁₂ Sb ₈₈ eutectic composition has a high crystallization speed and can be used for high-speed recording. It is widely known that it is suitable. The Ga—Sb binary phase change recording film having this Ga ₁₂ Sb ₈₈ eutectic composition has a melting point: 588.0 ° C. and a crystallization temperature: 204.9 ° C., and this Ga ₁₂ Sb ₈₈ eutectic composition It is also known that a Ga—Sb binary phase change type recording film having the following is produced by sputtering using a target made of a sintered alloy having substantially the same component composition as the film (for example, Non-patent document 1).
“PCOS2002” High-Density & High-Speed Phase Speed Change Recording Technologies for the City of East 1st East page.

In recent years, recording media such as CDs and DVDs are often exposed to high-temperature environments such as being mounted on automobiles. When exposed to such high-temperature environments, the conventional eutectic crystals of Ga ₁₂ Sb ₈₈ are used. A Ga—Sb binary phase change recording film having a composition is relatively unstable because it is in an amorphous state, so that the storage stability of a recording mark (amorphous state) becomes unstable. There was a drawback.

Therefore, the inventors of the present invention have a GaSb phase change type that can maintain an amorphous state more stably than a Ga—Sb binary phase change type recording film having a conventional eutectic composition of Ga ₁₂ Sb _88. Research was conducted to obtain a recording film. as a result,
(A) In a normal GaSb eutectic phase change recording film, one or more of In, Sn, and Bi are combined in a total amount of less than 0.2 to 5% (hereinafter,% indicates atomic%). The GaSb eutectic phase change type recording film containing bismuth can stably maintain an amorphous state as compared with the conventional GaSb eutectic type phase change type recording film, and thus can stably store the recording mark. ,
(B) A GaSb eutectic phase change recording film containing one or more of In, Sn, and Bi described in (a) above in a total amount of less than 0.2 to 5% is obtained by using this GaSb. Research results such as being able to be obtained by sputtering using a target having almost the same component composition as the system phase change recording film were obtained.

The present invention has been made based on such research results,
(1) Ga: contains 4 to less than 20%, and further contains one or more of In, Sn and Bi in a total of less than 0.2 to 5%, the balance being Sb and inevitable impurities A GaSb phase change recording film excellent in storage stability of a recording mark made of an Sb-based alloy having a composition;
(2) Ga: 5 to 20%, further containing one or more of In, Sn and Bi in total less than 0.2 to 5%, with the balance being Sb and inevitable impurities A sputtering target for forming a GaSb-based phase change recording film excellent in the storage stability of the recording mark according to the above (1), which is made of an Sb-based alloy having the above.

  The reason why the component composition of the GaSb phase change recording film excellent in storage stability of the recording mark of the present invention is limited as described above will be described.

(A) Ga
The reason why Ga contained in the GaSb phase change recording film having excellent storage stability of the recording mark of the present invention is limited to 4 to less than 20% is that the crystallization temperature is lowered when the Ga content is less than 4%. This is not preferable because the mark stability is deteriorated too much. On the other hand, if the Ga content is 20% or more, the crystallization temperature becomes too high and crystallization becomes difficult, which is not preferable. Ga contained in a target for forming a GaSb phase change recording film excellent in storage stability of a recording mark containing 4 to less than 20% of Ga of the present invention by sputtering is less than 5 to 20%.

(B) In, Sn and Bi
Even if one or more of In, Sn, and Bi are added in a total amount of less than 0.2%, the effect of stabilizing and stabilizing the amorphous state is diminished. This is not preferable because the activation energy to the crystal becomes too high and crystallization becomes difficult. Therefore, one or more of In, Sn and Bi contained in the GaSb phase change recording film of the present invention is determined to be 0.2 to less than 5% in total. The amount of In, Sn and Bi contained in the target for forming the GaSb phase change recording film excellent in storage stability of the recording mark of the present invention by sputtering is one or more of these components. Is in the range of less than 0.2 to 5%.

  The target for forming the GaSb-based phase change recording film of the present invention is obtained by dissolving an alloy having almost the same component composition as that of the GaSb-based phase change recording film of the present invention in an Ar gas atmosphere, It can be produced by preparing an alloy ingot by pouring out into a mold, grinding them in an inert gas atmosphere to produce an alloy powder, and vacuum hot pressing the alloy powder. The vacuum hot press is performed under the conditions of pressure: 146 to 155 MPa, temperature: 370 to 430 ° C., holding for 1 to 2 hours, and then cooling rate: 1 to 1 when the temperature of the mold is lowered to 270 to 300 ° C. 3 ° C./min. More preferably, it is carried out by cooling to room temperature.

  It is possible to form a GaSb-based phase change recording film excellent in storage stability of the recording mark of the present invention by inserting the sputtering target thus prepared into a normal sputtering apparatus and sputtering under normal conditions. it can.

  The recording medium using the GaSb phase change recording film of the present invention does not lose its record even when exposed to a high temperature environment for a long period of time, and can stably store the record for a long period of time. Can greatly contribute to the development of

Example One or more of Ga, Sb and In, Sn and Bi were melted in an Ar gas atmosphere to produce a molten alloy, and the molten alloy was cast to produce an alloy ingot. By pulverizing the ingot in an Ar atmosphere, an alloy powder having a particle size of 250 μm or less was produced.
These alloy powders are hot-pressed by vacuum hot pressing at a temperature of 400 ° C. and a pressure of 146 MPa, and these hot-pressed bodies are ground using a cemented carbide tool at a lathe speed of 200 rpm. The present invention targets 1 to 14, comparative targets 1 to 7 and conventional target 1 having the component composition shown in Table 1 in the shape of a disk having a diameter of 76.2 mm and a thickness of 3 mm were prepared.

The following measurements were performed using these inventive targets 1 to 14, comparative targets 1 to 7, and conventional target 1.
(A) Amorphous film preservation test Inventive targets 1-14, comparative targets 1-7, and conventional target 1 are each soldered to a copper cooling backing plate with an indium brazing material having a purity of 99.999% by weight. Was placed in a direct current magnetron sputtering apparatus, and the distance between the target and the glass substrate was set to 70 mm, and then vacuuming was performed until the ultimate vacuum was 2 × 10 ⁻³ Pa or less. Pressure: Ar gas is supplied until it reaches 5 × 10 ⁻¹ Pa,
-Substrate temperature: room temperature,
-Input power: 150W
Sputtering is performed under the following conditions: GaSb phase change recording films of the present invention which are amorphous films having a thickness of 20 nm on the surface of a glass substrate: 1 to 14, comparative GaSb phase change recording films 1 to 7 and conventional A GaSb phase change recording film 1 was formed. Further, the present GaSb phase change recording films 1 to 14 formed on the surface of the glass substrate: 1 to 14, the comparative GaSb phase change recording films 1 to 7 and the conventional GaSb phase change recording film 1 are further provided with a normal one. A sample having a structure of glass substrate / phase change recording film / protective film was produced by forming a ZnS-SiO ₂ protective film having a thickness of 20 nm under the conditions. These samples were held in a vacuum maintained at a temperature of 170 ° C. for 0 to 960 hours shown in Tables 2 to 3, and the reflectivity after each time was measured. The results are shown in Tables 2 to 3.

(B) Evaluation of amorphous preservation by measurement of activation energy when crystallizing from amorphous The present targets 1 to 14, comparative targets 1 to 7 and conventional target 1 are each in a copper cooling backing plate with a purity of 99.999. Soldered with a weight percent indium brazing material, charged in a direct current magnetron sputtering apparatus, and sputtered to produce tens of mg of the present GaSb phase change recording film: 1 to 14, comparative GaSb phase change Amorphous film consisting of mold recording films 1 to 7 and a conventional GaSb phase change recording film 1 is formed on a polycarbonate substrate. This GaSb phase change recording film of the present invention: 1 to 14, comparative GaSb phase change type Each of the amorphous films made of the recording films 1 to 7 and the conventional GaSb phase change recording film 1 is made of a polycrystal. -Peeled from the bonate substrate and processed into powder. The resulting GaSb phase change recording films of the present invention: 1 to 14, the heating rate of the powder comprising the comparative GaSb phase change recording films 1 to 7 and the conventional GaSb phase change recording film 1: 5 K / min, The crystallization temperatures at 10 K / min and 15 K / min are measured with a DTA (differential differential thermal analyzer), and the following activation energy calculation formula: d [LN (αTp ² )] / D (1 / Tp) = − E / R (where α is the rate of temperature rise, Tp is the crystallization temperature, R is the gas constant, and E is the activation energy). The results are shown in Tables 2-3. In this case, the larger the activation energy of amorphous → crystalline, the better the storage stability of amorphous.

  From the results shown in Tables 1 to 3, the GaSb phase change recording films of the present invention obtained by sputtering using the targets 1 to 14 of the present invention: 1 to 14 were sputtered using the target 1 of the prior art. Compared to the obtained conventional GaSb-based phase change recording film 1, the reflectance does not increase greatly even if it is kept at 170 ° C. for a long time. Therefore, the quality change of the amorphous film is small, and the stability is excellent. It can be seen that since the chemical energy is large, the amorphous storage stability is excellent. However, the comparative GaSb phase change recording films 1 to 7 obtained by sputtering using the comparative targets 1 to 7 having the component composition deviating from the conditions of the present invention are too low in activation energy and stored in an amorphous state. It can be seen that it is not preferable as a phase change recording film because it has poor properties, or the activation energy is too high and it is difficult to crystallize.

Claims (2)

In atomic% (hereinafter,% indicates atomic%) Ga: 4 to less than 20%, and further one or more of In, Sn and Bi are added in total to less than 0.2 to 5% A GaSb-based phase change recording film excellent in storage stability of a recording mark, characterized by comprising an Sb-based alloy having a composition of Sb and inevitable impurities. In atomic% (hereinafter,% indicates atomic%) Ga: less than 5 to 20%, and in addition, one or more of In, Sn and Bi are added in total to be less than 0.2 to 5% The sputtering for forming a GaSb-based phase change recording film excellent in storage stability of a recording mark according to claim 1, further comprising a Sb-based alloy having a composition of Sb and inevitable impurities. target.