JP2001064768A - Sputtering target for forming optical recording protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the deviation of the oxygen concentration of an optical recording protective film formed by the use of a target from the oxygen concentration of the target by providing a composition consisting of specific percentages of silicon dioxide and Si and the balance zinc chalcogenide. SOLUTION: The sputtering target for forming an optical recording protective film has a composition consisting of 10-30 mol.% silicon dioxide, 1-10 mol.% Si, and the balance zinc chalcogenide. Zinc sulfide is most suitably used as the zinc chalcogenide. By performing sputtering by the use of this target, no strong deviation of the composition ratio of oxygen contained in the resultant optical recording protective film from the composition ratio of oxygen contained in the target is brought about. Accordingly, the formation of inferior optical recording protective films can be minimized and yield can be improved, and the productive efficiency of an optical disk, etc., can be improved and also cost reduction can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-chalcogenide-silicon dioxide sintered body for forming an optical recording protection film such as a phase change type optical disk capable of recording and erasing information by using a laser. The present invention relates to a sputtering target for forming an optical recording protection film, and particularly to a sputtering target for forming an optical recording protection film having a very small difference in oxygen concentration between the target and an optical recording protection film formed using the target. is there.

[0002]

2. Description of the Related Art In general, an optical recording protective film is formed by sintering a mixed powder of silicon dioxide powder and zinc chalcogenide [generic name of zinc sulfide (ZnS), zinc selenide (ZnSe), and zinc telluride (ZnTe)]. It is known that it is formed by sputtering using a disk-shaped target made of a sintered body obtained by sintering, and is usually obtained by sintering a mixed powder consisting of silicon dioxide powder and zinc sulfide powder. It is formed by sputtering using a disk-shaped target made of a sintered body having a relative density of 90% or more. The disc-shaped target composed of silicon dioxide and zinc sulfide has a purity of 9
Purity: 9.99% by weight or more of zinc sulfide powder
9.999% by weight or more of silicon dioxide powder in 10 to 30
It is also known that the mixture is uniformly mixed, and the resulting mixed powder is press-formed into a disk shape and then sintered (see JP-A-6-65725).

When these targets are set in a sputtering apparatus held in an atmosphere of an inert gas such as argon and high-frequency power is applied, atoms and molecules of the sputtering gas are ionized and accelerated by an electric field near the target surface. It is also known that the target recording material collides with the target surface, repels and collides with the substrate, and an optical recording protective film having substantially the same composition as the target is formed.

[0004]

In recent years, the quality control of optical recording media has become more strict, and the quality control of the formed optical recording protection film has also been strictly checked. However, the composition of the optical recording protection film formed using the conventional sputtering target for forming an optical recording protection film may be greatly different from the composition of the target, especially the composition ratio of oxygen contained in the formed optical recording protection film. May greatly deviate from the composition ratio of oxygen in the target. In particular, the longer the sputtering time or the higher the output and the longer the sputtering time, the higher the oxygen content ratio of the optical recording protective film and the target tends to be, and under severe quality control, it may be defective. In some cases, the reliability of the target was impaired.

[0005]

Means for Solving the Problems Accordingly, the present inventors have:
Research has been conducted to obtain a target in which the composition ratio of oxygen in the formed optical recording protection film does not largely deviate from the composition ratio of oxygen in the target. Conventional silicon dioxide: 10 to 30 mol% is contained. , The remainder having a composition consisting of zinc chalcogenide,
i: A target having a composition in which 1 to 10 mol% is added has a composition ratio of oxygen contained in an optical recording protection film formed by sputtering using the composition greatly different from the composition ratio of oxygen contained in the target. The research result that there was no thing was obtained.

The present invention has been made based on the results of such research, and (1) silicon dioxide: 10 to 30.
Mol%, Si: 1 to 10 mol%, and the balance is characterized by a sputtering target for forming an optical recording protective film having a composition of zinc chalcogenide.

[0007] Most preferably, the zinc chalcogenide is zinc sulfide. Therefore, the present invention relates to (2) silicon dioxide: 10 to 30 mol%, Si: 1 to 10 mol%
And a sputtering target for forming an optical recording protective film having a composition comprising zinc sulfide as the remainder.

The sputtering target for forming an optical recording protective film according to the present invention is manufactured as follows. First, a commercially available zinc chalcogenide powder is prepared, and the commercially available zinc chalcogenide powder is removed in an Ar atmosphere at a temperature of 650 ° C. for the purpose of removing gas contained in the commercially available zinc chalcogenide powder.
(Temperature-raising rate: 2.2 ° C./min) Degassing heat treatment is performed for 1 hour, and the raw material powder of silicon dioxide is added to the chalcogenide zinc powder that has been subjected to the degassing heat treatment.
30 mol% and Si powder are added in an amount of 1 to 10 mol%, and they are mixed uniformly, and the obtained mixed powder is hot-pressed into a disc to produce a disc-shaped hot pressed body. The hot pressing conditions at this time are as follows: Ar gas atmosphere, pressure: 300 to 400 kgf / cm ² , temperature: 8
50 to 1100 ° C (preferably 850 to 900 ° C),
This is performed under the condition of holding for 5 to 7 hours, and then cooling is performed from this holding temperature to normal temperature at a cooling rate of 1 to 3 ° C./min.
The disk-shaped hot pressed body thus obtained is ground to a predetermined size to produce the sputtering target for forming an optical recording protective film of the present invention.

The reason that the amount of Si powder contained in the sputtering target for forming an optical recording protective film of the present invention is limited to 1 to 10 mol% is that the desired effect cannot be obtained if the amount of Si powder is less than 1 mol%. On the other hand, when the amount of the Si powder exceeds 10 mol%, the amount of zinc sulfide decreases, so that it does not function sufficiently as an optical recording protection film, so that thermal shock is easily applied to the substrate and the life of the substrate is increased. This is because it is not preferable because it shortens. The more preferred amount of the Si powder contained in the sputtering target for forming an optical recording protective film of the present invention is 5 to 7 mol%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION For the purpose of degassing, commercially available ZnS powder, ZnSe powder and ZnTe powder are heated at a rate of 2.2 ° C./min in an Ar atmosphere, respectively, at 650.
By performing a heat treatment at 1 ° C. for 1 hour, ZnS raw material powder, ZnSe raw material powder and ZnTe raw material powder were produced. Further, commercially available SiO ₂ raw material powder and Si raw material powder were prepared.

Example 1 A raw material powder of SiO _{2 and a} raw material of Si were mixed with a raw material powder of ZnS such that SiO ₂ : 20 mol%, Si: 6 mol%, and the balance: ZnS, and the mixed powder was mixed with ethanol. Put into a polypot, wet-mix for 1 hour to form a slurry, evaporate ethanol by drying the obtained slurry of the mixed powder, and then lightly crush, then fill in a graphite mold of hot press After performing hot pressing under the conditions of pressure: 250 kgf / cm ² and temperature: 950 ° C. for 3 hours in an Ar gas atmosphere, a disc-shaped hot pressed body is produced by cooling at a cooling rate of 2 ° C./min. Then, these disk-shaped hot pressed bodies are machined to form a sputtering film for forming a protective film of the optical recording medium of the present invention having a diameter of 200 mm and a thickness of 5 mm. Getto (hereinafter, referred to as the present invention target) was prepared 1.

Conventional Example 1 Further, for comparison, ZnS raw material powder was mixed with SiO ₂
The raw material powder was blended so that SiO ₂ : 20 mol% and the balance was ZnS, and a sputtering target for forming a conventional protective film for an optical recording medium (hereinafter referred to as a conventional target) was prepared using this blended powder in the same manner as in Example 1. 1 was produced.

The oxygen contents of the thus obtained target 1 of the present invention and the conventional target 1 were measured, and the results are shown in Table 1. Each of the target 1 of the present invention and the target 1 of the related art was 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 apparatus. Ar, ・ Sputter gas pressure: 5 × 10 ⁻³ Torr, ・ Sputter power: 13.56 MHz high frequency power 150
Sputtering was performed for 30 hours under the conditions of 0 Kw (about 8.5 W / cm ² ) to form a circular optical recording medium protective film having a radius of 60 mm on the substrate surface. 22.5 mm, 27.5 mm, 32.5 mm from the center of the substrate of the obtained optical recording medium protective film,
37.5mm, 42.5mm, 47.5mm, 52.5
The oxygen content was measured at mm and 57.5 mm apart, and the results are shown in Table 1. Further, the vertical axis represents the oxygen content of Table 1 and the oxygen content of the target,
The graph shown in FIG. 1 was created and the oxygen content at these locations was compared with the oxygen content of the target.

[0014]

[Table 1]

From the results shown in Table 1 and FIG. 1, the oxygen content of the obtained optical recording medium protective film of the target 1 of the present invention is very close to the oxygen content of the target. It can be seen that the deviation of the oxygen concentration from the optical recording protection film is extremely small.

Example 2 The SiO ₂ raw material powder and the Si raw material powder were added to the previously heat-treated ZnSe raw material powder by SiO ₂ : 20 mol%, S
i: 5 mol%, balance: ZnSe, and this powder mixture was put into a polypot together with ethanol.
The mixture was wet-mixed for 1 hour to form a slurry, and the obtained mixed powder slurry was dried to evaporate ethanol,
Thereafter, after crushing lightly, the mixture was filled into a graphite mold of a hot press, and a disk-shaped hot pressed body was prepared in an Ar gas atmosphere under the same conditions as in Example 1, and these disk-shaped hot pressed bodies were machined. And diameter: 200mm, thickness: 5
A target 2 of the present invention having a size of mm was produced.

Conventional Example 2 Further, for comparison, ZnSe raw material powder was compared with SiO
_TwoThe raw material powder is SiO _Two : 20 mol%, balance: ZnS
e and blended to obtain Example 2.
In the same manner as in the above, a conventional target 2 was produced.

The oxygen contents of the target 2 of the present invention and the conventional target 2 thus obtained were measured, and the results are shown in Table 2. The target 2 of the present invention and the target 2 of the related art were each 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 apparatus. Ar, ・ Sputter gas pressure: 5 × 10 ⁻³ Torr, ・ Sputter power: 13.56 MHz high frequency power 150
Sputtering was performed for 30 hours under the conditions of 0 Kw (about 8.5 W / cm ² ) to form a circular optical recording medium protective film having a radius of 60 mm on the substrate surface. 22.5 mm, 27.5 mm, 32.5 mm from the center of the substrate of the obtained optical recording medium protective film,
37.5mm, 42.5mm, 47.5mm, 52.5
The oxygen content was measured at a distance of 5 mm and 57.5 mm, and the results are shown in Table 2.

[0019]

[Table 2]

From the results shown in Table 2, the target 2 of the present invention has an oxygen content of the obtained optical recording medium protective film which is very close to the oxygen content of the target as compared with the conventional target 2. It can be seen that the deviation of the oxygen concentration from the film is extremely small.

Example 3 The SiO ₂ raw material powder and the Si raw material powder were added to the previously heat-treated ZnTe raw material powder by SiO ₂ : 20 mol%, S
i: 7 mol%, balance: ZnTe, and this powder mixture was put into a polypot together with ethanol.
The mixture was wet-mixed for 1 hour to form a slurry, and the obtained mixed powder slurry was dried to evaporate ethanol,
Thereafter, after crushing lightly, the mixture was filled into a graphite mold of a hot press, disk-shaped hot pressed bodies were produced in an Ar gas atmosphere under the same conditions as in Example 1, and these disk-shaped hot pressed bodies were machined. And diameter: 200mm, thickness: 5m
The target 3 of the present invention having a dimension of m was produced.

Conventional Example 3 Further, for comparison, ZnTe raw material powder was compared with SiO
_{(2) The} raw material powder was blended so that SiO ₂ : 20 mol% and the balance: ZnTe, and a conventional target 3 was produced in the same manner as in Example 3 using this blended powder.

The oxygen contents of the thus obtained target 3 of the present invention and conventional target 3 were measured, and the results are shown in Table 3. The target 3 of the present invention and the target 3 of the related art were each 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 apparatus. Ar, ・ Sputter gas pressure: 5 × 10 ⁻³ Torr, ・ Sputter power: 13.56 MHz high frequency power 150
Sputtering was performed for 30 hours under the conditions of 0 Kw (about 8.5 W / cm ² ) to form a circular optical recording medium protective film having a radius of 60 mm on the substrate surface. 22.5 mm, 27.5 mm, 32.5 mm from the center of the substrate of the obtained optical recording medium protective film,
37.5mm, 42.5mm, 47.5mm, 52.5
The oxygen content was measured at a distance of 5 mm and 57.5 mm. The results are shown in Table 3.

[0024]

[Table 3]

From the results shown in Table 3, the oxygen content of the obtained optical recording medium protective film of the target 2 of the present invention was very close to the oxygen content of the target as compared with the conventional target 2. It can be seen that the deviation of the oxygen concentration from the film is extremely small.

[0026]

As described above, the sputtering target for forming an optical recording medium protective film according to the present invention having a composition in which Si is added in an amount of 1 to 10 mol% is the same as the conventional sputtering target for forming an optical recording medium protective film. Since the composition ratio of oxygen in the formed optical recording protection film does not greatly deviate from the composition ratio of oxygen in the target, the formation of a defective optical recording medium protection film can be suppressed as much as possible, and the yield is improved. The optical disk production efficiency can be improved and the cost can be reduced, which can greatly contribute to the development of the optical media industry.

[Brief description of the drawings]

FIG. 1 is a graph comparing the amount of oxygen contained in an optical recording medium protective film formed by a target 1 of the present invention and the amount of oxygen contained in an optical recording medium protective film formed by a conventional target 1 with the amount of oxygen contained in a target.

Claims (2)

[Claims] 1. Silicon dioxide: 10 to 30 mol%, S
i: a sputtering target for forming an optical recording protective film, comprising: 1 to 10 mol%, with the balance being zinc chalcogenide. 2. The sputtering target according to claim 1, wherein the zinc chalcogenide is zinc sulfide.