JP3368765B2 - 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 0.001 <α / β <0.3, generation of particles during sputtering is suppressed, and α / β The value is more preferably in the range of 0.03 ≦ α / β ≦ 0.25. (B) The crystal grain sizes of the α-type crystal and β-type crystal of zinc sulfide contained in the sputtering target are those at the time of sputtering. The maximum crystal grain size and the average crystal grain size of the α-type crystal and the β-type crystal are preferably finer, which has a great influence on particle generation, and the maximum crystal grain size is 15 μm or less and the average crystal grain size is 10 μm or less. Preferably, (c) purity: 99.999% by weight
Purity: 99.999% by weight based on the above zinc sulfide powder
The above silicon dioxide powder: 10 to 30 mol% is added,
Further, 10 to 1000 ppm of aluminum oxide powder is added, and the sputtering target obtained by hot pressing the mixed powder obtained by mixing these has improved sinterability and thus improved mechanical strength, We have obtained the knowledge that cracking does not occur during sputtering.

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. 001
<Α / β <0.3 (preferably 0.03 ≦ α / β ≦
0.25), a sputtering target for forming an optical recording protective film with less particle generation, (2) Purity: 99.999% by weight or more of silicon dioxide: 10 to 3
0 mol%, aluminum oxide: 10 to 1000 ppm
A sputtering target comprising a sintered body having a composition comprising zinc sulfide having a purity of 99.999% by weight or more, and a relative density of 90% or more, containing
The zinc sulfide has a mixture ratio of α-type crystals and β-type crystals (α /
β) is 0.001 <α / β <0.3 (preferably 0.
03 ≦ α / β ≦ 0.25), which includes a sputtering target for forming an optical recording protective film with less particle generation, and (3) a sputtering target for forming an optical recording protective film according to (1) and (2) above. Zinc sulfide α
The characteristic feature of the sputtering target for forming an optical recording protective film is that the maximum crystal grain size of the p-type crystal and the β-type crystal is 15 μm or less and the average crystal grain size is 10 μm or less.

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.

Mixing ratio of α-type crystals and β-type crystals of zinc sulfide
(Α / β) within the range of 0.001 <α / β <0.3
To adjust so that 500-900 zinc sulfide powder
5-10 at a temperature of ℃ (preferably 650-850 ℃)
Cooling rate from holding temperature to 200 ℃ after holding for a long time
Is heat-treated by cooling at 2 to 10 ° C / min and then baked.
The binding conditions are vacuum or Ar gas atmosphere, pressure: 200-
250 kgf / cm ², Temperature: 800 to 1050 ° C (favorable
Preferably, hold at 850 to 950 ° C.) for 6 to 10 hours,
From this holding temperature to 200 ° C, the range is 1 to 5 ° C / min.
At the cooling rate in the enclosure, cool it to 100 ° C or less and take it out.
It is obtained by Of the invention thus obtained
How about a sputtering target for forming an optical recording protective film?
It can also be applied to a sputtering device, but especially for batch
When used as a target for a sputtering system,
The number of particles generated during sputtering is particularly small
Eliminates and 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 powders were heat-treated under the conditions shown in Table 1 in an Ar gas atmosphere to prepare ZnS powders AJ. However, ZnS powder J is a powder that is not heat-treated.

[0011]

[Table 1]

Example 1 This heat-treated ZnS powders A to I and non-heat-treated Z
Table 2 shows the prepared SiO ₂ powder for nS powder J.
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 9 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 9 of the present invention, the comparative target 1 and the conventional target are the first peak value (100) α obtained by X-ray diffraction.
And (111) β are measured to obtain the ratio, while the crystal grain sizes of the targets 1 to 9 of the present invention, the comparative target 1 and the conventional target are as follows, after the cross section of the sintered body is polished with diamond paste: It was determined by measuring with a scanning electron microscope.

The targets 1 to 9 of the present invention, the comparative target 1 and the conventional target were soldered to a cooling backing plate made of copper, and this was set in a batch type high frequency magnetron sputtering apparatus as shown in FIG. Sputtering gas: Ar, Sputtering gas pressure:
Sputtering was performed under the conditions of 5 × 10 ⁻³ Torr, sputtering time: 1 minute and 5 minutes, power: 600 W, thickness: 1
A 50 nm SiO ₂ film was deposited on a laminated silicon substrate, and the number of particles was measured with a particle counter after 1 minute of sputtering and after 5 minutes of sputtering, and the results are shown in Table 3.

In FIG. 1, 1 is a target and 2 is a target.
Is a backing plate, 3 is a substrate holder, 4 is a substrate, 5
Is a sputtering chamber, 6 is a substrate electrode, and 7 is sputtered particles. In the batch type sputtering apparatus, while rotating the substrate electrode 6 and rotating the substrate holder 3, the sputtered particles 9 are deposited on the substrate 4 to form a sputtered film.

[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 9 of the present invention generate a smaller amount of particles than the comparative target 1 and the conventional target when the sputtering is performed at a high output by increasing the film forming speed.

Example 2 For the heat-treated ZnS powders A to I and the non-heat-treated ZnS powder J 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. , 10/18 of the present invention in the form of a disk having the maximum and average crystal grain sizes of α-type and β-type crystals of α, β and zinc sulfide, and having a diameter of 125 mm and a thickness of 5 mm. Was manufactured.

These targets 10 to 18 of the present invention were soldered to a copper cooling plate, which was set in a batch type high frequency magnetron sputtering apparatus in exactly the same manner as in Example 1, and sputtering gas: Ar, sputtering gas pressure:
Sputtering is performed under the conditions of 5 × 10 ⁻³ Torr, sputtering time: 1 minute and 5 minutes, and power: 600 W. After 1 minute of sputtering and 5 minutes of sputtering, the number of particles is measured with a particle counter, and sputtering is completed. Check for the presence of subsequent cracks and see Table 5 for the results.
It was shown to.

[0021]

[Table 4]

[0022]

[Table 5]

From the results shown in Tables 4 to 5, Al ₂ O
₃ of the present invention target 10 comprising 10~1000ppm
No. 18 was produced in Example 1 when the film formation speed was increased by applying a high output of 600 W and sputtering was performed.
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 batch type 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 holder 4 substrates 5 Sputter chamber 6 substrate electrodes 7 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 in the range of 0.001 <α / β <0.3, and a sputtering target for forming an optical recording protective film with few particles is produced. 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 in the range of 0.001 <α / β <0.3, and a sputtering target for forming an optical recording protective film with few particles is produced. 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.