JP3368764B2 - Sputtering target for optical recording protective film formation with less generation of particles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target made of a zinc sulfide-silicon dioxide sintered body for forming a protective film used for an optical medium such as an optical disc for recording and erasing information by using a light beam. In particular, the present invention relates to a sputtering target in which particles are rarely generated during sputtering.

[0002]

2. Description of the Related Art As a sputtering target for forming a protective film used in optical media such as optical disks for recording and erasing information using a light beam, purity: 99.999% by weight or more of silicon dioxide and purity: 9
A sputtering target composed of a sintered body having a zinc sulfide content of 9.999% by weight or more and a relative density of 90% or more is known (see JP-A-6-65725). This conventional sputtering target for forming an optical recording protective film is added to a zinc sulfide powder having a purity of 99.999% by weight or more and a silicon dioxide powder having a purity of 99.999% by weight: 20 mol% and uniformly mixed. It is also known that the mixed powder obtained is pressed and then sintered.

Further, in general, zinc sulfide has two crystal types, an α-type crystal and a β-type crystal, and the α-type crystal has a hexagonal wurtzite structure and is stable at high temperatures, while the β-type crystal. Is known to have a zinc blende type structure and be stable at room temperature, and the transition temperature of α-type crystals and β-type crystals is 1020 ° C.

[0004]

In recent years, the demands on the performance of the optical recording protective film have become more and more strict, and particularly the demands for suppressing the particles generated during the sputtering have become strict, and the film forming rate or the uniformity of the film thickness is somewhat sacrificed. However, although a target with few particles generated during sputtering is required, a target with few particles generated during sputtering has not been obtained yet.

[0005]

Therefore, the present inventors have
As a result of research to obtain a target in which few particles are generated during sputtering, (a) Purity: 99.
Silicon dioxide of 999% by weight or more: 10 to 30 mol%
In a sputtering target made of a sintered body having a composition of zinc sulfide having a purity of 99.999% by weight or more, the crystal form of the zinc sulfide has a great influence on particle generation during sputtering.
When the mixing ratio (α / β) of α-type crystals and β-type crystals of zinc sulfide is within the range of 0.95 <α / β <100, particle generation during sputtering is suppressed and the value of α / β is It is more preferable to be in the range of 1.0 ≦ α / β ≦ 50. (B) The crystal grain size of the α-type crystal and β-type crystal of zinc sulfide contained in the sputtering target is large for particle generation during sputtering. Influence, α
It is preferable that the maximum crystal grain size and the average crystal grain size of the β-type crystal and the β-type crystal are finer, and the maximum crystal grain size is 15
It is preferable that the average crystal grain size is 10 μm or less and (c) the zinc sulfide powder having a purity of 99.999% by weight or more, and the silicon dioxide powder having a purity of 99.999% by weight or more: 10 30 mol% is added, and further 10 to 1000 ppm of aluminum oxide powder is added,
The sputtering target obtained by hot pressing the mixed powder obtained by mixing these has improved mechanical strength due to improved sinterability, and cracks do not occur during sputtering. It was.

The present invention has been made on the basis of such findings, and (1) Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol% is contained, and the rest is purity: 99.999. In a sputtering target composed of a sintered body having a composition of zinc sulfide of not less than wt% and a relative density of 90%, the zinc sulfide has a mixture ratio of α-type crystals and β-type crystals (α / β) of 0. 95 <
α / β <100 (preferably 1.0 ≦ α / β ≦ 50)
Within the range of (2) Purity: 99.
999% by weight or more of silicon dioxide: 10 to 30 mol
%, Aluminum oxide: 10 to 1000 ppm, the balance consisting of zinc sulfide having a purity of 99.999% by weight or more, and a sputtering target made of a sintered body having a relative density: 90% or more, Zinc sulfide has a mixture ratio (α / β) of α-type crystals and β-type crystals of 0.95 <α / β <100 (preferably 1.0 ≦ α /
a sputtering target for forming an optical recording protective film in the range of β ≦ 50) with less particle generation, (3) α-type zinc sulfide contained in the sputtering targets for forming an optical recording protective film of (1) and (2) above Crystal and β
The present invention is characterized by a sputtering target for forming an optical recording protective film, which has a maximum crystal grain size of 15 μm or less and an average crystal grain size of 10 μm or less and has a small amount of particles.

In the sputtering target for forming an optical recording protective film of the present invention, 10-30 mol% of silicon dioxide powder having a purity of 99.999% by weight or more is added to zinc sulfide having a purity of 99.999% by weight or more after heat treatment. Then, it is manufactured by hot pressing the mixed powder obtained by uniformly mixing these. In order to further improve sinterability and mechanical strength, aluminum oxide powder is added to 1
Add 0 to 1000 ppm.

The amount of aluminum oxide contained in the sputtering target for forming an optical recording protective film of the present invention is set to 10 to 10.
The reason why the amount of aluminum oxide is limited to 1000 ppm is that when the amount of aluminum oxide added is less than 10 ppm, sufficient mechanical strength cannot be obtained because the sinterability is not sufficiently improved.
If the content exceeds m, it is not preferable because the quality of the obtained optical recording protective film deteriorates. The more preferable range of the amount of aluminum oxide contained in the sputtering target for forming an optical recording protective film of the present invention is 15
It is 0 to 400 ppm.

In order to control the mixture ratio (α / β) of α-type crystals and β-type crystals of zinc sulfide to be within the range of 0.95 <α / β <100, zinc sulfide powder should be 910 to 1100.
6 to at a temperature of ℃ (preferably 1050 to 1100 ℃)
After holding for 10 hours, heat treatment of cooling from the holding temperature to 200 ° C at a cooling rate of 2 to 5 ° C / min was performed, and the sintering conditions were Ar gas atmosphere, pressure: 150 to 200 kg.
f / cm ² , temperature: 1100 to 1150 ° C (preferably 1120 to 1150 ° C), after holding for 6 to 12 hours, the holding temperature to 200 ° C is 2 to 5 ° C / min.
It can be obtained by cooling to 100 ° C. or lower at a cooling rate within the range and taking out. The thus-obtained optical recording protective film forming sputtering target of the present invention can be applied to any sputtering apparatus, but particularly when used as a target of a single wafer type sputtering apparatus,
The number of particles generated during sputtering is particularly small, which is effective.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Grain size: 4 ± 1μ as raw material powder
ZnS powder having m and a purity of 99.999% by weight or more,
An SiO ₂ elementary powder having an average particle size of 10 μm and a purity of 99.999% by weight or more and an Al ₂ O ₃ powder having an average particle size of 1 μm and a purity of 99.99% by weight or more are prepared.
The ZnS powder was heat-treated under the conditions shown in Table 1 in an Ar gas atmosphere to produce ZnS powders AH. However, the ZnS powder H is a powder that is not heat-treated.

[0011]

[Table 1]

Example 1 This heat treated ZnS powders AG and Z not heat treated
Table 2 shows the prepared SiO ₂ powder for nS powder H.
Are mixed in a ratio shown in Table 1 and stirred and mixed in a ball mill for 20 hours, and the obtained mixed powder is filled in a graphite mold for hot pressing under the conditions of pressure, temperature and holding time shown in Table 2 in an argon atmosphere. By hot pressing, the composition, relative density, α / β and maximum crystal grain size and average crystal grain size of β type crystal of zinc sulfide shown in Table 3 were obtained, and further diameter: 125 mm, Thickness: Disc-shaped targets 1 to 12 of the present invention having a size of 5 mm, comparative target 1 and conventional target were manufactured.

The α / β of zinc sulfide of the targets 1 to 12 of the present invention, the comparative target 1 and the conventional target are the first peak values (100) obtained by X-ray diffraction.
[alpha] and (111) [beta] are measured to obtain the ratio, while the crystal grain sizes of the targets 1 to 12 of the present invention, the comparative target 1 and the conventional target are the same after the cross section of the sintered body is polished with diamond paste. , And measured by a scanning electron microscope.

These targets 1 to 12 of the present invention, the comparative target 1 and the conventional target were soldered to a cooling backing plate made of copper, which was set in a single-wafer type high frequency magnetron sputtering apparatus as shown in FIG. , Sputter gas: Ar, sputter gas pressure:
Sputtering was performed under the conditions of 5 × 10 ⁻³ Torr, sputtering time: 1 minute and 5 minutes, and power: 600 W, and the number of particles was measured with a particle counter after 1 minute of sputtering and 5 minutes of sputtering. Is shown in Table 3.

In FIG. 1, 1 is a target and 2 is a target.
Is a backing plate, 3 is a substrate electrode, 4 is a substrate, 5 is a gate valve, 6 is a sputter chamber, 7 is a transfer chamber, 8 is a storage chamber, and 9 is sputter particles. In the single-wafer sputtering apparatus, the pre-transfer substrate 4-1 is stored in the transfer chamber 7, and the pre-transfer substrate 4-1 is stored.
Through the gate valve 5 to the substrate electrode 3 one by one,
After depositing the sputtered particles 9 to form a sputtered film,
It is stored in the storage chamber 8.

[0016]

[Table 2]

[0017]

[Table 3]

From the results shown in Tables 2 and 3, 600 W
It can be seen that the targets 1 to 12 of the present invention generate a smaller amount of particles than the comparative target 1 and the conventional target when the film formation rate is increased and sputtering is performed at a high output of 1.

Example 2 For the heat-treated ZnS powders A to G and the non-heat-treated ZnS powder H shown in Table 1, SiO ₂ powder and A were used.
l ₂ O ₃ powder was blended in a ratio shown in Table 4 and hot-pressed under an argon atmosphere under the conditions of pressure, temperature and time holding shown in Table 4 to obtain the component composition and relative density shown in Table 5. , Α / β and zinc sulfide α-type crystals and β-type crystals having the maximum and average crystal grain sizes, the disc-shaped targets 13 to 22 of the present invention having a diameter of 125 mm and a thickness of 5 mm. Was manufactured.

These targets 13 to 22 of the present invention were soldered to a cooling backing plate made of copper, and this was set in a single-wafer type high frequency magnetron sputtering apparatus in the same manner as in Example 1, and sputtering gas: Ar, sputtering. Gas pressure: 5 × 10 ⁻³ Torr, sputtering time:
Sputtering was performed for 1 minute and 5 minutes at a power of 600 W, the number of particles was measured with a particle counter after 1 minute of sputtering and after 5 minutes of sputtering, and the target was checked for cracks after sputtering was completed. The results are shown in Table 5.

[0021]

[Table 4]

[0022]

[Table 5]

From the results shown in Tables 4 to 5, Al ₂ O
_The target 13 of the present invention containing ₃ to 10 to 1000 ppm
In No. 22, when the high output of 600 W is applied and the film formation rate is increased to perform the sputtering, Table 2 produced in Example 1
It can also be seen that, compared to the comparative target 1 and the conventional target shown in Table 3, the amount of particles generated is small and cracks do not occur even when sputtering is completed, and therefore the film formation rate can be increased.

[0024]

As described above, the sputtering target for forming an optical recording protective film according to the present invention is used for forming an optical recording protective film in which few particles are generated and cracks do not occur even when high-power sputtering is performed. Since the sputtering target can be provided, it can greatly contribute to the development of the optical media industry.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a single-wafer sputtering apparatus suitable for using the sputtering target for forming an optical recording protective film of the present invention.

[Explanation of symbols]

1 target 2 backing plate 3 substrate electrodes 4 substrates 5 gate valve 6 Sputter chamber 7 Transport chamber 8 storage chambers 9 Sputtered particles

Continuation of the front page (56) References JP-A-4-136164 (JP, A) JP-A-6-101032 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 14 / 00-14/58 G11B 7/26

Claims (3)

(57) [Claims] 1. Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol% is contained, and the remainder is purity: 9
In a sputtering target composed of a sintered body having a composition of 9.999% by weight or more of zinc sulfide and a relative density of 90% or more, the zinc sulfide has a mixed ratio of α-type crystals and β-type crystals (α /
β) is within a range of 0.95 <α / β <100, and a sputtering target for forming an optical recording protective film with little particle generation. 2. Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol%, aluminum oxide: 10
~ 1000 ppm, balance 99.999
Composition consisting of more than wt% zinc sulfide and relative density:
A sputtering target comprising a sintered body having 90% or more, wherein the zinc sulfide has a mixture ratio of α-type crystals and β-type crystals (α /
β) is within a range of 0.95 <α / β <100, and a sputtering target for forming an optical recording protective film with little particle generation. 3. The maximum crystal grain size of the α-type crystal and β-type crystal of zinc sulfide is 15 μm or less and the average crystal grain size is 1.
The sputtering target for forming an optical recording protective film according to claim 1 or 2, which has a particle size of 0 μm or less.