JP2001064766A - Sputtering target for forming optical recording protective film, minimal in generation of particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize generation of particle by using a crystalline silicon dioxide powder as a silicon dioxide powder for producing a sputtering target composed of a zinc sulfide - silicon dioxide sintered compact. SOLUTION: The sputtering target is composed of a zinc sulfide - silicon dioxide sintered compact having a composition consisting of 10-30 mol.% silicon dioxide and the balance zinc sulfide and also having a structure where a silicon dioxide powder is uniformly dispersed in a zinc sulfide matrix. In this sputtering target, a crystalline silicon dioxide powder is used as the silicon dioxide powder. Quartz powder, cristobalite powder, or tridymite powder is preferred as the crystalline silicon dioxide powder, and it is further preferable for the purpose of improving the strength of the target to use the above crystalline silicon dioxide powders in a state of pulverized powder. It is desirable that the average particle size of these crystalline silicon dioxide powders is in the range of 3-7 μm, and a powder prepared by pulverizing cristobalite is most desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to formation of an optical recording protection film made of a zinc sulfide-silicon dioxide sintered body for forming a protection film of a phase change optical disk or the like in which information is recorded and erased by using a laser. The present invention relates to a sputtering target for use.

[0002]

2. Description of the Related Art Generally, an optical recording protective film is sputtered using a disk-shaped target made of a sintered body having a relative density of 90% or more obtained by sintering a mixed powder of silicon dioxide powder and zinc sulfide powder. It is known that the disc-shaped target composed of silicon dioxide and zinc sulfide has a purity of 99.999% by weight or more and a zinc sulfide powder of 99.999% by weight or more. It is also known that silicon powder is added to 10 to 30 mol%, mixed uniformly, and the resulting mixed powder is press-formed into a disk shape and then sintered to be manufactured. It is also known that the disk-shaped target produced by this method has a structure in which silicon dioxide powder is uniformly dispersed in a zinc sulfide base (see JP-A-6-65725). The purity: 9
Since 9.999% by weight or more of silicon dioxide powder must be inexpensive and high purity silicon dioxide powder, high purity amorphous fused silica powder which is relatively easy to produce is used. It is also known that the use of the amorphous fused silica powder, particularly when the amorphous fused silica powder obtained by pulverization is used, does not cause cracks in the target obtained by hot pressing (particularly, Kaihei 10-3
24968).

[0003]

Generally, when an optical recording protective film is formed using a sputtering target composed of these zinc sulfide-silicon dioxide sintered bodies, particles cannot be avoided, but a large amount of particles are generated. Then, the optical recording protection film becomes a defective product, which is not preferable. Therefore, research is being conducted every day to obtain a target with as few particles as possible.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
While conducting research to obtain a sputtering target for forming an optical recording protective film composed of a zinc sulfide-silicon dioxide sintered body with less generation of particles,
(A) Conventionally, an amorphous silicon dioxide powder such as a fused silica powder has been used as a silicon dioxide powder for producing a sputtering target for forming an optical recording protective film composed of a zinc sulfide-silicon dioxide sintered body. However, the number of generated particles is smaller in a sputtering target manufactured using a crystalline silicon dioxide powder than in an amorphous silicon dioxide powder. (B) The crystalline silicon dioxide powder is Specifically, it is preferably quartz powder, cristobalite powder or tridymite powder,
Research results have shown that these crystalline silicon dioxide powders are more preferably pulverized powders in order to improve the strength of the target.

[0005] The present invention has been made based on the results of such research, and (1) silicon dioxide: 10 to 30.
Mole%, the balance consisting of zinc sulfide,
In a sputtering target comprising a zinc sulfide-silicon dioxide sintered body having a structure in which silicon dioxide powder is uniformly dispersed in a zinc sulfide base, the silicon dioxide powder is a crystalline silicon dioxide powder, and optical recording protection with less generation of particles. The sputtering target for forming a film, (2) the crystalline silicon dioxide powder is any one of quartz, cristobalite and tridymite, and the sputtering target for forming an optical recording protective film with less generation of particles according to (1) above. (3) The sputtering target for forming an optical recording protective film with less generation of particles according to the above (1), wherein the crystalline silicon dioxide powder is a pulverized powder of any of quartz, cristobalite and tridymite. Have

The average particle size of the crystalline silicon dioxide powder obtained by grinding the quartz, cristobalite or tridymite is preferably in the range of 3 to 7 μm,
Among these, crystalline silicon dioxide powder obtained by pulverizing cristobalite is most preferred.

The sputtering target for forming an optical recording protection film according to the present invention is manufactured as follows. First, a commercially available zinc sulfide powder is prepared, and a commercially available zinc sulfide powder is used for removing gas contained in the commercially available zinc sulfide powder.
r Atmosphere, temperature: 650 ° C (heating rate: 2.2 ° C / m
in) Degassing heat treatment under the condition of holding for 1 hour, 10 to 30 mol% of crystalline silicon dioxide raw material powder is added to the zinc sulfide powder subjected to the degassing heat treatment, and these are uniformly mixed. The obtained mixed powder is manufactured by hot pressing in a disk shape. The hot pressing conditions at this time are as follows: Ar gas atmosphere, pressure: 300 to 400 kg.
f / cm ^2, temperature: 850 to 1100 ° C., carried out under the conditions of 5 to 7 hours retention, then, the cooling rate from the holding temperature to cool to room temperature at 1 to 3 ° C. / min.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For the purpose of degassing, a commercially available ZnS powder is heated in an Ar atmosphere at a heating rate of 2.2 ° C./min, and subjected to a heat treatment at 650 ° C. for 1 hour. A ZnS raw material powder was produced. Further, crushed quartz, cristobalite and tridymite having different average particle sizes shown in Table 1 were prepared by crushing quartz, cristobalite and tridymite. The quartz powder, cristobalite powder and tridymite powder were blended with the ZnS raw material powder in the proportions shown in Table 1, and the blended powder was put into a polypot together with ethanol, and wet-mixed for 1 hour to obtain a slurry. The ethanol was evaporated by drying the slurry of the mixed powder thus obtained, and after crushing lightly, the mixture was filled in a graphite mold of a hot press, and the temperature was 1000 ° C. and the pressure was 340 kgf / c in an Ar gas atmosphere.
By performing hot pressing under the conditions of m ² and holding for 6 hours, disk-shaped hot pressed bodies having the same composition as the composition shown in Table 1 were produced, and the surfaces of these disk-shaped hot pressed bodies were machined to have a diameter of 200 mm. The sputtering targets (hereinafter, referred to as the present invention targets) 1 to 9 of the present invention having a thickness of 5 mm for forming an optical recording medium protective film were prepared, and the densities and bending strengths of the targets 1 to 9 of the present invention were measured. The results are shown in Table 1.

Further, Z of the targets 1 to 9 of the present invention
With respect to the silicon dioxide powder dispersed in the nS substrate, the scanning speed was 2.4 g / min, and the step was 0.04 de by a Mac Science X-ray microanalyzer.
X-ray diffraction was performed under the conditions of g, divergence: 0.5 deg, and light reception: 0.15 mm. As a result, a strong peak was obtained, and it was confirmed that each of the powders was crystalline silicon dioxide powder.

Conventional Example For further comparison, a fused silica powder having an average particle diameter of 7 μm obtained by pulverizing the fused silica was prepared, and this fused silica powder was compared with the ZnS raw material powder prepared in the examples. A conventional sputtering target for forming a protective film for an optical recording medium (hereinafter, referred to as a conventional target) having the same composition as the composition in Table 1 was blended and mixed in the proportions shown in Table 1 in the same manner as in the examples. It was manufactured, the density and bending strength were measured, and the results are shown in Table 1. Further, when the silicon dioxide powder dispersed in the ZnS base was X-ray diffracted by a Mac Science X-ray microanalyzer in the same manner as in the example, From the broad peak obtained, it was confirmed that the silicon dioxide powder dispersed in the ZnS substrate was an amorphous silicon dioxide powder.

The targets 1 to 9 of the present invention and the conventional targets thus obtained were each put on a molybdenum cooling backing plate with a purity of 99.999% by weight.
And then set it 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 for 1 minute and 5 minutes under the conditions of 0 Kw (about 8.5 W / cm ² ), the number of generated particles was measured, and the results are shown in Table 1.

[0012]

[Table 1]

[0013]

According to the results shown in Table 1, the targets 1 to 9 of the present invention in which crystalline silicon dioxide powder was dispersed in zinc sulfide base had amorphous silicon dioxide powder dispersed in zinc sulfide base. It can be seen that the density and strength are superior to the conventional target, and the number of particles generated during sputtering is small.

Claims (3)

[Claims] 1. Zinc sulfide-silicon dioxide containing 10 to 30 mol% of silicon dioxide with the balance being zinc sulfide and having a structure in which silicon dioxide powder is uniformly dispersed in a zinc sulfide base In a sputtering target comprising a sintered body, the silicon dioxide powder is a crystalline silicon dioxide powder, and the sputtering target for forming an optical recording protective film with less generation of particles. 2. The sputtering target according to claim 1, wherein the crystalline silicon dioxide powder is any one of quartz, cristobalite and tridymite. . 3. The sputtering according to claim 1, wherein the crystalline silicon dioxide powder is a crushed powder selected from the group consisting of quartz, cristobalite, and tridymite. target.