JP3468136B2 - Sputtering target for forming optical recording medium protective film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protection of an optical recording medium composed of a zinc chalcogenide-silicon dioxide sintered body for forming a protective film for a phase change type optical disc for recording and erasing information using a laser. The present invention relates to a sputtering target for forming a film, and particularly to a sputtering target for forming a protective film for an optical recording medium in which cracks do not occur even when high-power sputtering is performed.

[0002]

2. Description of the Related Art Purity: 99.99 as a sputtering target for forming a protective film for a phase change type optical disk for recording and erasing information by using a laser.
9% by weight or more of silicon dioxide and purity: 99.999% by weight or more of zinc chalcogenide, 90% relative density
It is known to use a sputtering target composed of the above-described sintered body (see Japanese Patent Laid-Open No. 6-65725). This conventional sputtering target for forming a protective film for an optical recording medium has a purity of 99.999% by weight or more, and a chalcogenide zinc powder of which purity is 99.999% by weight or more, and silicon dioxide powder: 10 to 30 mol% is uniformly added. It is also known to produce the mixed powder by mixing it with, and then sintering after pressurizing.

[0003]

In recent years, in order to improve the manufacturing efficiency of an optical recording medium, high power sputtering is performed by using a large-sized sputtering target for forming a protective film for an optical recording medium to efficiently protect the optical recording medium at high speed. By forming a film, an attempt is made to improve the production efficiency of optical disks and reduce costs. However, when high-power sputtering was performed using a large-scale sputtering target for forming a protective film for an optical recording medium made of a conventional zinc chalcogenide-silicon dioxide sintered body, the target cracked (hereinafter, the target cracked during sputtering. This phenomenon is called “spatter cracking”), and therefore high-power sputtering could not be performed. In addition, since the conventional sputtering target for forming an optical recording medium protective film made of a zinc chalcogenide-silicon dioxide sintered body lacks the strength (flexural strength) against bending stress, there is a limit in increasing the size of the target. was there.

[0004]

Therefore, the present inventors have
As a result of research to obtain a large-scale sputtering target for forming a protective film for an optical recording medium, which has high bending strength and is free from spatter cracks even when performing high-power sputtering, (a) zinc chalcogenide-silicon dioxide sintered body The flexural strength of a target made of and the occurrence of sputter cracks during high-power sputtering are greatly affected by the morphology and shape of the silicon dioxide powder dispersed in the zinc chalcogenide matrix, and the conventional optical recording medium protective film. The silicon dioxide powder dispersed in the zinc chalcogenide substrate of the sputtering target for formation was a silicon dioxide powder in a crystalline state. However, if this silicon dioxide powder was replaced with an amorphous silicon dioxide powder, high-power sputtering was performed. Sputter cracking does not occur even if performed, and it has a higher bending strength than before. (B) The amorphous silicon dioxide powder dispersed in the zinc chalcogenide substrate has a specific surface area value of 5
0-140 m ² / g and average particle size: 0.0006-
They have found that 0.096 μm ultrafine amorphous silicon dioxide powder is more preferable.

The present invention has been made on the basis of such findings, and has a specific surface area value of 50 to 140 m ² / g and an average particle diameter of 0.000 in a zinc chalcogenide matrix.
A sputtering target for forming a protective film for an optical recording medium, which has a structure in which ultrafine amorphous silicon dioxide powder having a particle size of 6 to 0.096 μm is dispersed in an amount of 10 to 30 mol%.

In the present invention, the zinc chalcogenide is zinc sulfide (ZnS), zinc selenide (ZnSe) or zinc telluride (ZnTe), of which zinc sulfide (ZnS) is most preferable.

The sputtering target for forming a protective film for an optical recording medium of the present invention has a specific surface area of 50 to 50 with respect to a commercially available zinc chalcogenide powder having an average particle size of 4 to 6 μm and a purity of 99.999% by weight or more. Purity with 140 m ² / g (more preferably 70-120 m ² / g):
It is preferable to add 10 to 30 mol% of amorphous silicon dioxide powder in an amount of 99.999% by weight or more, and uniformly mix these powders to obtain a mixed powder, which is then hot-pressed.

Since the finer the amorphous silicon dioxide powder is, the easier it is to make it. Therefore, it is preferable to use ultrafine amorphous silicon dioxide powder having an average particle diameter of 0.0006 to 0.096 μm. It is more preferable to use ultrafine amorphous silicon dioxide powder having an average particle diameter of 0.005 to 0.05 μm.

The hot press is carried out in a vacuum or Ar gas atmosphere, pressure: 150-300 kgf / cm ² , temperature: 850-950 ° C. (preferably 900-950).
C)) and hold for 3 to 5 hours. From this holding temperature, cooling rate:
It is carried out under the condition that the amorphous silicon dioxide powder is not crystallized by cooling to room temperature at 1 to 3 ° C./min.

The sputtering target for forming a protective film for an optical recording medium according to the present invention, which is composed of the hot-press sintered body manufactured as described above, can be increased in diameter from a large bending strength and can be further subjected to high power sputtering. The film formation efficiency can be further improved because the target is less likely to be cracked even if it is performed. The amorphous silicon dioxide powder dispersed in the zinc chalcogenide matrix of the sputtering target for forming an optical recording medium protective film of the present invention is
The specific surface area value and the average particle diameter of the amorphous silicon dioxide powder added as the raw material powder are the same. This can be confirmed by the SEM (scanning electron microscope) or the TEM (transmission electron microscope) having a higher resolution than the structure of the sputtering target for forming an optical recording medium protective film of the present invention.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Example 1 Commercially available ZnS powder having a purity of 99.999% by weight or more for the purpose of removing the gas contained in the ZnS powder was heated in an Ar atmosphere at a heating rate of 2.2 ° C./min. Heat 650
Purity: 9 by performing heat treatment for 1 hour at ℃
Zn having 9.999% by weight or more and an average particle size: 4 μm
S raw material powder was produced. Further, ultrafine amorphous SiO ₂ powder of Rheoroseal having the average particle diameter and the specific surface area value shown in Table 1 and a purity of 99.999% by weight or more was prepared. These ZnS raw material powder and ultrafine amorphous SiO ₂
The powders were blended in the proportions shown in Table 1, the blended powders were put into a polypot together with ethanol, and wet-mixed for 1 hour to form a slurry, and the resulting mixed powder slurry was dried to prepare ethanol. After evaporating and then crushing lightly, it was filled in a graphite mold of hot press, and pressure was 250 kgf / c in Ar gas atmosphere.
m ² , hot-pressed by maintaining the temperature and time shown in Table 1, then cooled at the cooling rate shown in Table 1 to prepare a hot-pressed body, and the hot-pressed body was machined to obtain a diameter : 200 mm, thickness: 5 mm, ultrafine amorphous S in ZnS matrix
Disc-shaped sputtering targets for forming an optical recording medium protective film of the present invention (hereinafter referred to as the present invention targets) 1 to 7 having a structure in which iO ₂ powder was dispersed were prepared.

Further, for comparison, average particle diameter: 12 μ
m, specific surface area value: 7.5 m ² / g and purity: 99.9
A crystalline SiO ₂ powder having 99% by weight or more is prepared, and the crystalline SiO ₂ powder is blended and mixed in a ratio shown in Table 1 with respect to the ZnS raw material powder to prepare a mixed powder. Is filled in a hot press graphite mold,
Pressure in Ar gas atmosphere: 250 kgf / c
m ² , hot-pressed by maintaining the temperature and time shown in Table 1, then cooled at the cooling rate shown in Table 1 to prepare a hot-pressed body, and the hot-pressed body was machined to obtain a diameter A disk-shaped conventional sputtering target for forming a protective film for an optical recording medium (hereinafter referred to as a conventional target) 1 having a size of 200 mm and a thickness of 5 mm and having a structure in which crystalline SiO ₂ powder is dispersed in a ZnS matrix. It was made.

The ultrafine amorphous Si uniformly dispersed in the ZnS matrix of the targets 1 to 7 of the present invention thus obtained
The average particle diameter, specific surface area value and dispersion amount of the O ₂ powder were the same as the average particle diameter, specific surface area value and blending amount of the ultrafine amorphous SiO ₂ powder shown in Table 1 before hot pressing.
Further, the average particle diameter, specific surface area value and dispersion amount of the crystalline SiO ₂ powder uniformly dispersed in the ZnS matrix of the conventional target 1 are the average particle diameter and specific surface area of the crystalline SiO ₂ powder shown in Table 1 before hot pressing. The value and the blending amount were the same.
This could be confirmed by SEM (scanning electron microscope).

The bending strength of each of the targets 1 to 7 of the present invention and the conventional target 1 was measured. The results are shown in Table 1. The targets were placed on a cooling backing plate made of molybdenum, and the purity was 99.999% by weight. Soldered with iridium brazing material, set in a high frequency magnetron sputtering device, sputter gas: Ar, sputter gas pressure: 5 × 10 -3 Torr, sputter power: 13.56 MHz high frequency power 150
Sputtering was performed under the conditions of 0 Kw (about 8.5 W / cm ² ), and it was visually observed whether spatter cracking occurred on the target. The results are shown in Table 1.

[0015]

[Table 1]

From the results shown in Table 1, it can be seen that the targets 1 to 7 of the present invention have higher bending strength than the conventional target 1, and spatter cracking does not occur even when high-power high-frequency magnetron sputtering is performed. .

Example 2 A commercially available ZnSe powder having a purity of 99.999% by weight or more was used for the purpose of removing the gas contained in the ZnSe powder.
Heating in an atmosphere at a heating rate of 2.2 ° C./min to 65
Purity: 9 by heat treatment at 0 ° C. for 1 hour
Zn having 9.999% by weight or more and an average particle size: 4 μm
Se raw material powder was produced. Further, it has the average particle size and the specific surface area value shown in Table 2, and the purity is 99.999% by weight.
The ultrafine amorphous SiO ₂ powder of Rheoroseal having the above was prepared. These ZnSe raw material powders and amorphous SiO ₂ powders were blended in the proportions shown in Table 2, and the blended powders were placed in a polypot with ethanol and wet-mixed for 1 hour to form a slurry. Ethanol was evaporated by drying the slurry of No. 1, then lightly crushed, and then charged into a hot press graphite mold, and the pressure was 250 kgf / c in an Ar gas atmosphere.
m ² , hot-pressed by holding the temperature and time shown in Table 2, then cooled at the cooling rate shown in Table 2 to prepare a hot-pressed body, and the hot-pressed body was machined to obtain a diameter : Amorphous SiO having a dimension of 200 mm and a thickness of 5 mm in the ZnSe matrix
Disc-shaped targets 8 to 14 of the present invention having a structure in which ₂ powders were dispersed were prepared.

Further, for comparison, average particle size: 10 μ
m, specific surface area value: 8.0 m ² / g and purity: 99.9
Crystalline SiO ₂ powder having 99% by weight or more was prepared, and this crystalline SiO ₂ powder was used for the ZnSe raw material powder in Table 2
Are mixed and mixed in the proportions shown in Table 1 and the obtained mixed powder is filled in a graphite mold of hot press, and the pressure is 250 kgf / cm ² in Ar gas atmosphere, and the temperature and the time shown in Table 2 are maintained. Hot press,
Then prepare a hot pressed body by cooling at a cooling rate shown in Table 2, the diameter by machining the hot pressed body: 200 mm, thickness: crystalline SiO ₂ in the ZnSe in the matrix has a dimension of 5mm A disk-shaped conventional target 2 having a structure in which powder is dispersed was prepared.

The average particle size, specific surface area value and dispersion amount of the ultrafine amorphous SiO ₂ powder uniformly dispersed in the ZnSe matrix of the targets 8 to 14 of the present invention thus obtained are as follows:
Ultrafine amorphous SiO ₂ shown in Table 2 before hot pressing
It was the same as the average particle size, specific surface area value and blending amount of the powder. Further, the average particle size, specific surface area value and dispersion amount of the crystalline SiO ₂ powder uniformly dispersed in the ZnSe matrix of the conventional target 2 are shown in Table 2 before hot pressing.
The average particle size, specific surface area value and blending amount of the _two powders were the same. This could be confirmed by SEM (scanning electron microscope).

The bending strength of each of the targets 8 to 14 of the present invention and the conventional target 2 was measured, and the results are shown in Table 2. After that, these targets were put on a cooling backing plate made of molybdenum and had a purity of 99.999% by weight. Soldered with iridium brazing material, set in a high-frequency magnetron sputtering apparatus, sputtered under the same conditions as in Example 1, and visually observed whether spatter cracking occurred in the target. Is shown in Table 2.

[0021]

[Table 2]

From the results shown in Table 2, it is understood that the targets 8 to 14 of the present invention have higher bending strength than the conventional target 2, and spatter cracking does not occur even when high-power high-frequency magnetron sputtering is performed. .

Example 3 A ZnTe raw material powder having a commercial purity of 99.999% by weight or more was heated at a heating rate of 2.2 ° C./min in an Ar atmosphere for the purpose of removing the gas contained in the ZnTe powder.
A ZnTe powder having a purity of 99.999% by weight or more and an average particle size of 6 μm was produced by performing heat treatment at 650 ° C. for 1 hour. Further, ultrafine amorphous SiO ₂ powder of Rheoroseal having the average particle diameter and the specific surface area value shown in Table 3 and a purity of 99.999% by weight or more was prepared. These ZnTe powders and amorphous SiO ₂ powders were blended in the proportions shown in Table 3, and the blended powders were placed in a polypot together with ethanol and wet mixed for 1 hour to form a slurry. Evaporating the ethanol by drying the slurry, then
After lightly crushing, fill the hot press graphite mold,
Pressure in Ar gas atmosphere: 250 kgf / c
m ² , hot-pressed by maintaining the temperature and time shown in Table 3, then cooled at the cooling rate shown in Table 3 to prepare a hot-pressed body, and the hot-pressed body was machined to obtain a diameter : Amorphous SiO having a dimension of 200 mm and a thickness of 5 mm in the ZnTe matrix
Disc-shaped targets 14 to 21 of the present invention having a structure in which _two powders were dispersed were prepared.

Further, for comparison, average particle diameter: 10 μ
m, specific surface area value: 8.0 m ² / g and purity: 99.9
Crystalline SiO ₂ powder having 99% by weight or more was prepared, and this crystalline SiO ₂ powder was blended and mixed at a ratio shown in Table 3 to the ZnTe powder, and the obtained mixed powder was hot-pressed into graphite. The hot-pressed body was hot-pressed by filling the mold and holding it in an Ar gas atmosphere at a pressure of 250 kgf / cm ² and the temperature and time shown in Table 3 and then cooling it at the cooling rate shown in Table 3. A conventional disk-shaped target 3 having a diameter of 200 mm and a thickness of 5 mm and having a structure in which crystalline SiO ₂ powder is dispersed in a ZnTe matrix is prepared by machining this hot-pressed body. did.

The average particle size, specific surface area and dispersion amount of the ultrafine amorphous SiO ₂ powder uniformly dispersed in the ZnTe matrix of the targets 14 to 21 of the present invention thus obtained are shown in Table 3 before hot pressing. Ultrafine amorphous Si shown in
It was the same as the average particle size, specific surface area value and blending amount of the O ₂ powder. Further, the average particle diameter, specific surface area value and dispersion amount of the crystalline SiO ₂ powder uniformly dispersed in the ZnTe matrix of the conventional target 2 are the crystalline S shown in Table 3 before hot pressing.
It was the same as the average particle size, specific surface area value and blending amount of the iO ₂ powder. This could be confirmed by SEM (scanning electron microscope).

The bending strengths of the targets 14 to 21 of the present invention and the conventional target 3 were measured, and the results are shown in Table 3.
After that, these targets were soldered to a cooling backing plate made of molybdenum with an iridium brazing material having a purity of 99.999% by weight, and this was set in a high frequency magnetron sputtering device under the same conditions as in Example 1. Sputtering was performed, and it was visually observed whether spatter cracking occurred on the target. The results are shown in Table 3.

[0027]

[Table 3]

From the results shown in Table 3, it can be seen that the targets 14 to 21 of the present invention have higher bending strength than the conventional target 3 and that spatter cracking does not occur even when high-power high-frequency magnetron sputtering is performed. .

[0029]

As described above, the sputtering target for forming a protective film for an optical recording medium of the present invention, in which amorphous silicon dioxide powder is dispersed in a zinc chalcogenide substrate, has a higher bending strength than conventional ones. Can be formed into a large size, and spatter cracks do not occur even when high-power sputtering is performed, so it is possible to form a protective film for phase-change type optical disks, etc. more efficiently than before, thus improving the production efficiency of optical disks. In addition, it is possible to reduce costs and make a great contribution to the development of the optical media industry.

The present invention is not limited to the above embodiment, but an optical recording in which crystalline silicon dioxide powder other than amorphous silicon dioxide powder is partially dispersed in the zinc chalcogenide matrix. A sputtering target for forming a medium protective film is also included in the scope of the present invention, in which case the amount of crystalline silicon dioxide powder dispersed must not be greater than the amount of amorphous silicon dioxide powder dispersed. .

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Claims (2)

(57) [Claims] 1. A zinc chalcogenide substrate having a specific surface area value of 50 to 140 m ² / g and an average particle size of 0.000.
A sputtering target for forming an optical recording medium protective film, having a structure in which ultrafine amorphous silicon dioxide powder having a particle size of 6 to 0.096 μm is dispersed in an amount of 10 to 30 mol%. 2. The sputtering target for forming an optical recording medium protective film according to claim 1, wherein the zinc chalcogenide is zinc sulfide, zinc selenide, or zinc telluride.