KR102473261B1 - Sputtering target and process for manufacturing same - Google Patents

Abstract

A basic composition in which the content of Al is 0.2 to 3.0 mol% in terms of Al ₂ O ₃ , the content of Mg and/or Si is 1 to 27 mol% in terms of MgO and/or SiO ₂ , and the remainder is the content of Zn in terms of ZnO , a sputtering target characterized by further containing 0.1 to 20 wt% of a metal that forms a low-melting oxide having a melting point of 1000°C or less in terms of oxide weight. Provided is a target for forming an optical thin film having no sulfur, low bulk resistance, enabling DC sputtering, and a low refractive index, and a method for manufacturing the same. Since the target itself is high-density, there is little abnormal discharge, and stable sputtering is possible. In addition, since the thin film formed by sputtering has high transmittance and is composed of a non-sulfide system, it is useful for forming a thin film for an optical information recording medium in which deterioration of the adjacent reflective layer and recording layer is less likely to occur. Throughput is greatly improved by improving the characteristics of an optical information recording medium, reducing equipment cost, and improving film formation speed.

Description

Sputtering target and its manufacturing method {SPUTTERING TARGET AND PROCESS FOR MANUFACTURING SAME}

The present invention relates to a target for forming an optical thin film having no sulfur, low bulk resistance, enabling DC sputtering and having a low refractive index, and a manufacturing method thereof.

Conventionally, ZnS-SiO ₂ , which is generally used mainly for protective layers of phase change type optical information recording media, has excellent properties in terms of optical characteristics, thermal characteristics, adhesion to a recording layer, and the like, and is widely used. However, today's rewritable optical disc represented by Blu-Ray is strongly required to increase the number of rewrites, increase capacity, and record at high speed.

One of the causes of deterioration in the number of rewrites and the like of the optical information recording medium is diffusion of a sulfur component from ZnS-SiO ₂ to the recording layer material arranged so as to be sandwiched between the protective layers ZnS-SiO ₂ . In addition, pure Ag or Ag alloy having high reflectivity and high thermal conductivity has been used for the reflective layer material for high-capacity and high-speed recording, and such a reflective layer is also disposed to be in contact with the protective layer material, ZnS-SiO ₂ .

Therefore, in this case as well, diffusion of sulfur from ZnS-SiO ₂ causes corrosion and degradation of the pure Ag or Ag alloy reflective layer material, which causes deterioration of characteristics such as reflectance of the optical information recording medium.

As a countermeasure against the diffusion of these sulfur components, a structure in which an intermediate layer containing nitride or carbide as a main component is formed between the reflective layer and the protective layer, and between the recording layer and the protective layer is also being implemented. However, this causes an increase in the number of laminated layers, resulting in a decrease in throughput and an increase in cost. In order to solve the above problems, a material system having optical properties equal to or better than ZnS-SiO ₂ and amorphous stability by replacing the protective layer material with an oxide-only material that does not contain sulfides has been studied.

Moreover, since a ceramic target, such as ZnS- _SiO2 , has a high bulk resistance value, it cannot form a film with a DC sputtering apparatus, and a high frequency sputtering (RF) apparatus is normally used.

However, this high-frequency sputtering (RF) device has many drawbacks such as high cost of the device itself, low sputtering efficiency, high power consumption, complicated control, and slow film formation speed. In addition, when high power is applied to increase the film formation speed, there is a problem that the substrate temperature rises and deformation of the polycarbonate substrate occurs. Moreover, since the film thickness of ZnS- _SiO2 is thick, the throughput fall and cost increase also pose a problem.

From the above points, as a target capable of DC sputtering, a proposal for a sintered body target in which an element having a valence higher than positive 3 is added to ZnO alone has been proposed (see Patent Document 1, for example). However, in this case, it is considered that it is not possible to achieve both low bulk resistance and low refractive index.

In addition, as a transparent conductive film and a sintered body for producing the same, a manufacturing method using a high-frequency or direct current magnetron sputtering method in which various groups II, III, and IV elements are combined has been proposed (see Patent Document 2). However, it is considered that the purpose of this technique is not aimed at reducing the resistance of the target, and that it is not possible to achieve both low bulk resistance and low refractive index.

In addition, a ZnO sputtering target under the condition that at least one of the elements to be added is dissolved in ZnO has been proposed (see Patent Document 3). Since the solid solution of the additive element is a condition, there is a problem in that there is a limitation in the composition of the components, and thus in the optical characteristics.

From the above, the present applicant was able to solve the above problems at once by implementing the invention of the content shown in Patent Document 4 below. That is, by providing a sputtering target having a low refractive index and low bulk resistance composed of Al ₂ O ₃ : 0.2 to 3.0 at%, MgO and/or SiO ₂ : 1 to 27 at%, balance ZnO, the target and film formation Characteristics could be greatly improved. However, a problem arose here.

For the target, high density is required in order to perform stable sputtering. However, in the above component system, when the sintering temperature is raised for densification, it is difficult to densify due to decomposition (evaporation) of ZnO. Therefore, low-temperature sintering and densification were required.

Japanese Unexamined Patent Publication No. 2-149459 Japanese Unexamined Patent Publication No. 8-264022 Japanese Unexamined Patent Publication No. 11-322332 Japanese Patent Publication No. 4828529

The present invention maintains the characteristics of Patent Literature 4, that is, does not contain sulfur, has low bulk resistance, enables DC sputtering by appropriate selection of materials, and has a low refractive index target for forming an optical thin film, and a method for manufacturing the same. Along with providing, it is to provide a high-density sputtering target. In addition, it has excellent adhesion to the recording layer and mechanical properties, and also has high transmittance, and since it is composed of a non-sulfide system, the deterioration of the adjacent reflective layer and recording layer is less likely to occur (particularly used as a protective film). ) To provide a sputtering target useful for the formation of and a manufacturing method thereof. Thus, it is aimed at improving the characteristics of the optical information recording medium, reducing the equipment cost, and significantly improving the throughput by improving the film formation speed.

In order to solve the above problems, the inventors of the present invention conducted intensive research and, as a result, obtained the knowledge that high density is possible by adding a metal that forms a low melting point oxide to the above Patent Document 4. In addition, optical properties and amorphous stability equivalent to those of ZnS-SiO ₂ are ensured, high-speed film formation by DC (direct current) sputtering is possible, and RF sputtering can be performed as needed, improving the characteristics of optical information recording media. , it was found that productivity can be improved.

Based on this knowledge, the present invention,

1) Contains a metal that forms a low-melting oxide with respect to a basic composition consisting of zinc (Zn), aluminum (Al), magnesium (Mg) and/or silicon (Si) three or four elements, and oxygen (O) As a target, the content of Al is 0.2 to 3.0 mol% in terms of Al ₂ O ₃ , the content of Mg and/or Si is 1 to 27 mol% in terms of MgO and/or SiO ₂ , and the remainder is the content of Zn in terms of ZnO A sputtering target characterized by further containing, in terms of oxide weight, 0.1 to 20 wt% of a metal that forms a low melting point oxide having a melting point of 1000°C or less relative to the basic composition consisting of;

2) The sputtering target according to 1) above, characterized in that the content of a metal forming a low-melting oxide is 0.1 to 10 wt% in terms of oxide;

3) a low-melting oxide selected from B ₂ O ₃ , P ₂ O ₅ , K ₂ O, V ₂ O ₅ , Sb ₂ O ₃ , TeO ₂ , Ti ₂ O ₃ , PbO, Bi ₂ O ₃ , MoO ₃ The sputtering target according to 1) or 2) above, characterized in that it is one or more materials;

4) The sputtering target according to any one of 1) to 3) above, wherein the content of Mg and/or Si is 10 to 27 mol% in terms of MgO and/or SiO ₂ ;

5) The sputtering target according to any one of 1) to 4) above, characterized in that the relative density is 98% or more;

6) The sputtering target according to any one of 1) to 5) above, wherein the target has a bulk resistance of 10 Ω cm or less;

7) The above 1) to 6, characterized in that they are used for an optical thin film forming a protective layer, a reflective layer or a transflective layer of an optical information recording medium, an electrode for an organic EL TV, a touch panel electrode, and a sheet layer of a hard disk. ) The sputtering target according to any one of the above;

8) Raw material powders for basic sintering such that Al ₂ O ₃ powder is 0.2 to 3.0 mol%, MgO and/or SiO ₂ powder is 1 to 27 mol%, and the balance is ZnO powder, and the total amount thereof is 100 mol% A sputtering target characterized by further adding 0.1 to 20 wt% of a low-melting oxide powder having a melting point of 1000 ° C. or less to the raw material for sintering, and hot-pressing the raw material for sintering at a temperature higher than 800 ° C. and lower than 1150 ° C. manufacturing method,

9) The method for producing a sputtering target according to 8) above, characterized in that the relative density is 98% or more;

10) The method for producing a sputtering target according to any one of 8) to 9) above, characterized in that the bulk resistance is 10 Ω cm or less;

The sputtering target comprising the above can easily obtain a target having a relative density of 98% or more and having a bulk resistance of 10 Ω·cm or less. And, it is useful as a target for forming thin films used for optical thin films forming protective layers, reflective layers or transflective layers of optical information recording media, organic EL TVs, electrodes for touch panels, and sheet layers of hard disks. .

This invention further provides the thin film shown below formed into a film using the said target.

11) Containing a metal that forms a low-melting oxide with respect to a basic composition consisting of three or four elements of zinc (Zn), aluminum (Al), magnesium (Mg) and/or silicon (Si), and oxygen (O) A thin film having an Al content of 0.2 to 3.0 mol% in terms of Al ₂ O ₃ , a content of Mg and/or Si of 1 to 27 mol% in terms of MgO and/or SiO ₂ , and the balance of Zn in terms of ZnO A thin film characterized by further containing, in terms of oxide weight, 0.1 to 20 wt% of a metal that forms a low melting point oxide having a melting point of 1000°C or less relative to the basic composition consisting of;

12) The thin film according to 11) above, characterized in that the content of a metal forming a low-melting oxide is 0.1 to 10 wt% in terms of oxide;

13) The low-melting oxide is selected from B ₂ O ₃ , P ₂ O ₅ , K ₂ O, V ₂ O ₅ , Sb ₂ O ₃ , TeO ₂ , Ti ₂ O ₃ , PbO, Bi ₂ O ₃ , MoO ₃ The thin film according to 11) or 12) above, characterized in that it is one or more types;

14) The thin film according to any one of 11) to 13), wherein the content of Mg and/or Si is 10 to 27 mol% in terms of MgO and/or SiO ₂ ;

15) The thin film according to any one of 11) to 14) above, characterized in that the refractive index (wavelength 550 nm) is 2 or less;

16) The thin film according to any one of 11) to 15) above, characterized in that the extinction coefficient (λ = 450 nm) is less than 0.01;

17) The above 11) to 16 characterized by being used for an optical thin film forming a protective layer, a reflective layer or a transflective layer of an optical information recording medium, an organic EL TV, an electrode for a touch panel, and a sheet layer of a hard disk. ) provides the thin film according to any one of the above.

As described above, by replacing the protective layer material ZnS-SiO ₂ with an oxide-only material that does not contain sulfide, deterioration due to sulfur to the adjacent reflective layer, recording layer, etc. is suppressed, and is equivalent to or equivalent to ZnS-SiO ₂ High-speed film formation becomes possible by providing more optical characteristics and reducing the bulk resistance value. In addition, since a high-density sputtering target can be provided, the occurrence of abnormal discharge can be reduced and stable sputtering is possible. In addition, it is possible to provide a sputtering target useful for a thin film for an optical information recording medium (particularly used as a protective film, a reflective layer, or a semi-permeable film layer) having excellent adhesion to a recording layer, excellent mechanical properties, and high transmittance. As described above, there are excellent effects of improving the characteristics of the optical information recording medium, reducing equipment cost, and greatly improving the throughput by increasing the film formation speed.

1 is a diagram showing vapor pressure curves of Al ₂ O ₃ , MgO, SiO ₂ , and ZnO.
Fig. 2 is a diagram showing the results of thermodynamic simulation of the behavior of ZnO in fabrication in a hot press (HP).
Fig. 3 is a graph showing the lowering of the shrinkage temperature when 0.5 wt% and 1.0 wt% of B ₂ O ₃ are added as low-melting point oxides, as compared to those without addition.

The sputtering target of the present invention is a low-melting oxide with respect to a basic composition consisting of three elements or four elements of zinc (Zn), aluminum (Al), magnesium (Mg) and/or silicon (Si), and oxygen (O). As a target containing a metal to be formed, the content of Al is 0.2 to 3.0 mol% in terms of Al ₂ O ₃ , the content of Mg and/or Si is 1 to 27 mol% in terms of MgO and/or SiO ₂ , and the balance is Zn A sputtering target characterized by containing 0.1 to 20 wt% in terms of oxide weight of a metal that further forms a low-melting oxide having a melting point of 1000° C. or less with respect to the basic composition consisting of the ZnO content of It has a refractive index.

That is, in ZnO, at least one of Al ₂ O ₃ that imparts conductivity, MgO and SiO ₂ that adjust the refractive index, and a low melting point oxide having a melting point of 1000°C or less are dispersed.

In the present invention, the content of the metal in the sintered body is defined in terms of each oxide, but each metal in the sintered body is partially or entirely present as a composite oxide. In addition, in the component analysis of the sintered compact used normally, each content is measured as a metal rather than an oxide.

With respect to the ZnO-Al ₂ O ₃ -MgO-SiO ₂ system target (ZnO main component) described in Patent Literature 4, high density is required in order to perform stable sputtering. As a method of increasing the density, increasing the sintering temperature can be considered, but in this system, since the vapor pressure of ZnO is high (see Fig. 1), it is difficult to increase the density due to the decomposition (evaporation) of ZnO.

In addition, in production by hot press, there arises a problem that reduction of ZnO occurs due to contact with carbon under high temperature and erodes the die.

Regarding fabrication in a hot press (HP), according to the results of thermodynamic simulation of ZnO behavior (see Fig. 2), reduction of ZnO occurs at 1100 ° C. even under pressure under conditions where carbon coexists. It is necessary to lower than 1100 ℃.

As a method of low-temperature sintering and high-density, addition of a low melting point oxide was studied, and setting the sintering temperature to less than 1100°C was studied. As a result, it was found that the addition of an oxide having a melting point of 1000°C or less was effective.

As this low-melting oxide, it is particularly selected from B ₂ O ₃ , P ₂ O ₅ , K ₂ O, V ₂ O ₅ , Sb ₂ O ₃ , TeO ₂ , Ti ₂ O ₃ , PbO, Bi ₂ O ₃ , MoO ₃ Addition of materials is effective.

Table 1 shows the melting points of these low melting point oxides. Among these, since B ₂ O ₃ is not toxic, it is particularly effective in terms of handling. This made it possible to increase the density of the target, prevent abnormal discharge, and achieve stable sputtering.

The sintering temperature can be effectively reduced by adding the metal that forms the low-melting oxide in an amount of 0.1 wt% or more and 20.0 wt% or less in terms of oxide weight. Further preferably, it is 0.1 wt% or more and 10.0 wt% or less, so that the sintering temperature can be lowered without significantly impairing the properties of the base material, and more preferably, 0.1 wt% or more and 5.0 wt% or less, in this range The sintering temperature can be lowered without changing the properties of the base material.

The actions and effects of other component compositions (materials) are the same as those in Patent Document 4, but will be described again. That is, when Al ₂ O ₃ is less than 0.2 mol%, the bulk resistance value increases, and the object of the present invention cannot be achieved. In addition, when Al ₂ O ₃ exceeds 3.0 mol%, bulk resistance increases and DC sputtering becomes impossible, which is undesirable. Therefore, it is set within the above range.

MgO and SiO ₂ can be added alone or in combination, respectively, and can achieve the object of the present invention. When the content of MgO and/or SiO ₂ is less than 1 mol%, refractive index reduction cannot be achieved, and when the content exceeds 27 mol%, the bulk resistance value increases and the film formation speed significantly decreases, which is not preferable. Therefore, it is good to set it as the composition range of the said component.

Moreover, it is more preferable that MgO and/or _SiO2 be 10-27 mol%. This is because, compared to the case where MgO and/or SiO ₂ is 1 to 10 mol%, when about 10 to 27 mol% is added, the transmittance is further improved and the refractive index can be reduced.

The sputtering target of the present invention is useful for industrially producing an optical thin film for an optical disk having a refractive index of 2.00 or less (550 nm) and a low refractive index. In particular, it can be used as a target for forming a protective layer, a reflective layer or a semi-transmissive layer of an optical information recording medium.

Along with the increase in the capacity of optical information recording media, write-once and rewritable DVDs that support multi-layer recording have appeared. In the case of such a multi-layered structure, the reflective layer of the first layer located in the middle between the first and second layers needs to have transparency in order to irradiate the write/read output light to the second layer. When an Ag alloy is used as this semi-permeable layer, sulfurization due to reaction with ZnS-SiO ₂ used as a protective layer becomes a problem.

As such a semi-transmissive layer without the problem of yellowing, a semi-transmissive layer obtained by alternately laminating a high refractive index layer and a low refractive index layer to have arbitrary optical characteristics can be obtained. The target of the present invention can also be suitably used as a low refractive index layer constituting a transflective layer other than the above protective layer. And, the bulk resistance of the target can achieve 10 Ω·cm or less. The reduction of the bulk resistance value enables high-speed film formation by DC sputtering. Depending on the material selection, RF sputtering is required, but even in that case, the film formation speed can be improved. As a result of the above, the sputter film formation speed and the optical properties (refractive index and transmittance) are in an optimal range. A range deviating from the numerical range tends to deteriorate the above characteristics.

When attempting to form a low-refractive-index film for optical adjustment, since most of the low-refractive-index material is not conductive, DC sputtering cannot be performed, and there is a problem that the film formation rate is slow. On the other hand, in general conductive transparent film materials such as ITO and AZO, although DC sputtering is possible, the refractive index becomes as high as 2.0 or more. Therefore, it can be said that one of the features of the present invention is that it has a refractive index of 2.0 or less and can perform DC sputtering.

Since the volume resistivity of the sputtering target needs to be capable of DC sputtering, the upper limit is 10 Ωcm capable of DC sputtering, but there is no particular problem with a low level. In addition, the volume resistivity of the thin film formed by sputtering using this target is in the range of 1×10 ³ Ω·cm to 1×10 ⁹ Ω·cm.

The extinction coefficient (λ = 450 nm) of a film obtained by sputtering the sputtering target of the present invention is preferably less than 0.01, although it varies depending on the film configuration and film thickness at the time of use. When a transparent film is required, it can be said that zero is ideal. The present invention is particularly aimed at the short wavelength side in the visible light region. An oxide film generally has difficulty in suppressing absorption on the short wavelength side in the visible light region, has absorption on the short wavelength side, and tends to become a yellowish film (for example, IZO is a yellowish film).

In the production of the sputtering target of the present invention, 0.2 to 3.0 mol% of Al ₂ O ₃ powder as a raw material, 1 to 27 mol% of MgO and/or SiO ₂ powder, and the remainder being ZnO powder, these are 100 mol% The base raw material powder is adjusted so that 0.1 to 20 wt% of a low melting point oxide powder having a melting point of 1000°C or less is further added thereto to obtain a raw material for sintering. Next, this mixed powder is hot pressed at more than 800°C and less than 1150°C.

As a result, with respect to the basic composition consisting of 0.2 to 3.0 mol% of Al ₂ O ₃ , 1 to 27 mol% of MgO and/or SiO ₂ , and the remainder ZnO (composition of 100 mol%), the melting point is further lower than 1000°C. A sputtering target containing 0.1 to 20 wt% of a metal that forms a melting point oxide in terms of oxide weight can be obtained.

And, by this sintering, the relative density can be made 98% or more, and the bulk resistance of the target can be made 10 Ω·cm or less.

In addition, Al ₂ O ₃ powder and ZnO powder as raw materials are mixed in advance and temporarily fired in advance, and then MgO and/or SiO ₂ powder is added to the temporarily sintered Al ₂ O ₃ -ZnO powder (AZO powder). It is also possible to sinter by mixing powders of low melting point oxides.

This is because when simply adding MgO and/or SiO ₂ powder, Al ₂ O ₃ reacts with MgO and/or SiO ₂ to easily form spinel, and the bulk resistance value tends to increase. Therefore, in order to achieve lower bulk resistance of the sintered body, it is preferable to sinter using temporarily sintered Al ₂ O ₃ -ZnO powder (AZO powder).

In addition, Al ₂ O ₃ powder and ZnO powder as raw materials are mixed in advance and temporarily fired beforehand to obtain AZO powder, and MgO powder and SiO ₂ powder as raw materials are equally mixed and temporarily fired, and then the temporary It is recommended to mix the calcined Al ₂ O ₃ -ZnO powder (AZO powder) with the MgO-SiO ₂ temporarily calcined powder and the low melting point oxide powder and sinter them. This is because spinelization can be further suppressed and low bulk resistance can be achieved.

In addition, since the sputtering target of the present invention can achieve a relative density of 98% or more as described above, it has an excellent effect of improving the uniformity of the sputtering film and suppressing the generation of particles during sputtering.

Using the sputtering target described above, it is possible to provide an optical information recording medium that forms a part of the optical information recording medium structure as at least a thin film. Further, using the above sputtering target, it is possible to produce an optical information recording medium that forms part of the structure of the optical information recording medium as at least a thin film and is disposed adjacent to the recording layer or the reflective layer.

According to the present invention, by using zinc oxide as a target as a main component in this way, conductivity can be maintained, and thus a thin film can be formed by direct current sputtering (DC sputtering). Compared to RF sputtering, DC sputtering is excellent in that the film formation speed is high and the sputtering efficiency is good, and the throughput can be remarkably improved.

In addition, the DC sputtering device has advantages of low price, easy control, and low power consumption. Since the film thickness of the protective film itself can also be reduced, productivity improvement and substrate heating prevention effects can be further exhibited. Further, in the present invention, there are cases where it is necessary to perform RF sputtering depending on the manufacturing conditions and material selection, but even in that case, the film formation speed can be improved.

In addition, the thin film formed using the sputtering target of the present invention forms a part of the structure of the optical information recording medium and is disposed adjacent to the recording layer or the reflective layer. As described above, since ZnS is not used, S There is a remarkable effect that there is no contamination by the protective layer, there is no diffusion of the sulfur component to the recording layer material arranged so as to be sandwiched between the protective layers, and the deterioration of the recording layer due to this is eliminated.

In addition, pure Ag or Ag alloys having high reflectivity and high thermal conductivity have been used for the reflective layer material for high capacity and high-speed recording, but diffusion of sulfur components into the adjacent reflective layer is also eliminated, and the reflective layer material is also subject to corrosion deterioration. Thus, it has an excellent effect that the cause of deterioration of characteristics such as reflectance of the optical information recording medium is eliminated.

In addition, by using the sputtering target of the present invention, there are remarkable effects that productivity is improved, a material having excellent quality can be obtained, and an optical recording medium having an optical disk protective film can be stably manufactured at low cost.

The density improvement of the sputtering target of the present invention reduces the number of pores, refines the crystal grains, and makes the sputtering surface of the target uniform and smooth, thereby reducing particles and nodules during sputtering, and also reducing the life of the target. It has a remarkable effect that the temperature can be increased, and the quality variation is small, and the mass productivity can be improved.

Example

Hereinafter, it demonstrates based on Examples and Comparative Examples. Note that this embodiment is only an example and is not limited by this example at all. That is, the present invention is limited only by the claims, and includes various modifications other than the examples included in the present invention.

(Example 1)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and B ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared. Next, these powders were prepared at the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, and SiO ₂ powder: 2.2 mol%, totaling 100 mol%. It was set as % and it was set as the basic raw material. Then, B ₂ O ₃ powder: 1.0 wt% was further blended here to obtain a raw material for sintering. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered compact target reached 99.6%, and the bulk resistance became 3.5 × 10 ^-3 Ω·cm (3.5 mΩ·cm).

In addition, the density displayed in this specification means a relative density. Each relative density is obtained by measuring the density of the target, which is a composite oxide produced, with respect to the theoretical density of the target calculated from the density of the raw material, and obtaining the relative density from each density. Since it is not a simple mixture of raw materials, as shown in Table 2, there are examples in which the relative density exceeds 100%.

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.8 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.943, the volume resistivity: 2 × 10 ⁵ Ω·cm, and the extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Comparative Example 1)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder was prepared. Next, these powders were prepared at the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1150°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, and SiO ₂ powder: 2.2 mol%. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered compact target was 97.6%, which was lower than in Example 1. The bulk resistance was 2.0 × 10 ^-3 Ω·cm.

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. Although the film formation rate was able to achieve 2.2 Å/sec, abnormal discharge and particle generation occurred during sputtering, and stable DC sputtering could not be performed. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.948, the volume resistivity: 1 × 10 ⁵ Ω·cm, and the extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Comparative Example 2)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder was prepared. Next, these powders were prepared at the compounding ratio shown in Table 2, mixed, and then hot pressed (HP) at a temperature of 1050°C (lower than Comparative Example 1). The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, SiO ₂ powder: 2.2 mol%, and Comparative Example 1 and did the same After sintering, this sintered body was finished into a target shape by machining. The density of the sintered compact target was 90.9%, lower than Example 1, and lower than Comparative Example 1. The bulk resistance was 3.0 × 10 ^-3 Ω·cm.

DC sputtering was attempted under the same conditions as in Comparative Example 1 using the above finished 6-inch φ size target, but was stopped because stable DC sputtering could not be performed. Table 2 shows these conditions and results collectively.

(Example 2)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and B ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared.

Next, these powders were prepared at the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the mixing ratio of the raw materials is ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, SiO ₂ powder: 2.2 mol%, and the total is 100 mol%. It was set as % and it was set as the basic raw material. Then, B ₂ O ₃ powder: 0.5 wt% was further blended here to obtain a raw material for sintering.

The blending ratio of the B ₂ O ₃ powder was lower than in Example 1. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 99.5%, and the bulk resistance became 2.9 × 10 ^-3 Ω·cm (2.9 mΩ·cm). The density was slightly lower than that of Example 1.

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.6 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.945, the volume resistivity: 2 × 10 ⁵ Ω·cm, and the extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Example 3)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and B ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared.

Next, these powders were prepared in the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the mixing ratio of raw materials is ZnO powder: 89.3 mol%, MgO powder: 9.2 mol%, Al ₂ O ₃ powder: 0.7 mol%, SiO ₂ powder: 0.8 mol%, and the total is 100 mol%. It was set as % and it was set as the basic raw material. Then, B ₂ O ₃ powder: 1.0 wt% was further blended here to obtain a raw material for sintering. The blending ratio of the B ₂ O ₃ powder was the same as in Example 1.

The mixing ratio of other raw materials was changed. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 101.6%, and the bulk resistance became 2.2 × 10 ^-3 Ω·cm (2.2 mΩ·cm). Density was further improved than Example 1.

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film of 1500 angstroms in thickness was formed. A film formation rate of 3.0 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.973, volume resistivity: 3 × 10 ³ Ω·cm, and extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Example 4)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and B ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared. Next, these powders were prepared in the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the compounding ratio of the raw materials is ZnO powder: 68.9 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.1 mol%, SiO ₂ powder: 5.4 mol%, total 100 mol%. was used as the basic raw material. Then, B ₂ O ₃ powder: 1.0 wt% was further blended here to obtain a raw material for sintering. The blending ratio of the B ₂ O ₃ powder was the same as in Example 1.

The mixing ratio of other raw materials was changed. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 101.6%, and the bulk resistance became 3.3 × 10 ^-3 Ω·cm (3.3 mΩ·cm). Density was further improved than Examples 1 and 2.

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.9 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.899, the volume resistivity: 1 × 10 ⁶ Ω·cm, and the extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Example 5)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and Bi ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared.

Next, these powders were prepared in the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the mixing ratio of the raw materials is ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, SiO ₂ powder: 2.2 mol%, and the total is 100 mol%. It was set as % and it was set as the basic raw material. Then, Bi ₂ O ₃ powder: 1.0 mol% was further blended here to obtain a raw material for sintering. The mixing ratio of the Bi ₂ O ₃ powder was the same as in Example 1. A difference from Example 1 is that Bi ₂ O ₃ powder was used instead of B ₂ O ₃ powder.

After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target was 98.5%, and the bulk resistance was 2.3 × 10 ^-3 Ω·cm (2.3 mΩ·cm).

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.8 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength 550 nm) of the film-forming sample was 1.953, volume resistivity: 5 × 10 ⁵ Ω·cm, and extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Example 6)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, SiO ₂ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N of B ₂ O ₃ powder was prepared. Next, these powders were prepared in the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 80.5 mol%, Al ₂ O ₃ powder: 2.5 mol%, and SiO ₂ powder: 17.0 mol%, and the total was 100 mol% as the basic raw material. . Then, B ₂ O ₃ powder: 1.5 wt% was further blended as an additive to obtain a raw material for sintering. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 99.6%, and the bulk resistance became 1.3 × 10 ^-3 Ω·cm (1.3 mΩ·cm).

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.4 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.84, volume resistivity: 6 × 10 ⁴ Ω·cm, and extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Example 7)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N B ₂ O ₃ powder was prepared. Next, these powders were prepared in the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1050°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 79.9 mol%, MgO powder: 17.6 mol%, and Al ₂ O ₃ powder: 2.5 mol%, and the total was 100 mol% as the basic raw material. Then, B ₂ O ₃ powder: 1.5 wt% was further blended here to obtain a raw material for sintering. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 99.4%, and the bulk resistance became 2.1 × 10 ^-3 Ω·cm (2.1 mΩ·cm).

Sputtering was performed using the above finished 6-inch φ size target. The sputtering conditions were DC sputtering, sputtering power of 500 W, Ar-2% O ₂ mixed gas pressure of 0.5 Pa, and a film thickness of 1500 Å was formed. A film formation rate of 2.6 Å/sec was achieved, stable DC sputtering was possible, and good sputtering properties were obtained. The refractive index (wavelength of 550 nm) of the film-forming sample was 1.95, the volume resistivity: 7 × 10 ⁴ Ω·cm, and the extinction coefficient (λ = 450 nm): <0.01. Table 2 shows these conditions and results collectively.

(Comparative Example 3)

ZnO powder with an average particle size of 5 μm or less equivalent to 4 N, MgO powder with an average particle size of 5 μm or less equivalent to 4 N, Al ₂ O ₃ powder with an average particle size of 5 μm or less equivalent to 4 N, and an average particle size of 5 μm or less equivalent to 4 N SiO ₂ powder and B ₂ O ₃ powder having an average particle diameter of 5 μm or less corresponding to 4 N were prepared. Next, these powders were prepared at the compounding ratio shown in Table 2, and hot-pressed (HP) was performed at a temperature of 1000°C after mixing this. The pressure of the hot press was 220 kg/cm 2 .

As shown in Table 2, the proportions of the raw materials were ZnO powder: 72.0 mol%, MgO powder: 24.6 mol%, Al ₂ O ₃ powder: 1.2 mol%, and SiO ₂ powder: 2.2 mol%, totaling 100 mol%. It was set as % and it was set as the basic raw material. Then, B ₂ O ₃ powder: 0.5 wt% was further blended here to obtain a raw material for sintering. After sintering, this sintered body was finished into a target shape by machining. The density of the sintered target reached 99.6%, and the bulk resistance was 3.2 × 10 ^-3 Ω·cm (3.2 mΩ·cm).

DC sputtering was attempted under the same conditions as in Comparative Example 1 using the above finished 6-inch φ size target, but was stopped because stable DC sputtering could not be performed. Table 2 shows these conditions and results collectively.

(Overview of Comprehensive Evaluation by Examples and Comparative Examples)

As is clear from the above Comparative Example 1, the density was as low as 97.6% in hot pressing at 1150°C and 220 kg/cm 2 without addition of the low melting point oxide. Even at this temperature, reduction of ZnO occurs, indicating that low-temperature sintering is required.

As shown in Comparative Example 2, as a result of performing HP at 1050°C and 220 kg/cm 2 for the same raw material, the density was further lowered to 90.9%.

As shown in the above examples, when B ₂ O ₃ was added as a low melting point oxide, a decrease in shrinkage temperature was confirmed at 0.5 wt% and 1.0 wt% addition (see FIG. 3 ).

As shown in Example 1 and Example 2, with respect to B ₂ O ₃ addition of 0.5 and 1.0 wt%, the density became 99.6 and 99.5%, respectively, and high density in low-temperature sintering was achieved. Also for the bulk resistance value, it was 2.0 to 4.0 mΩ·cm and became 10 mΩ·cm or less, and DC sputtering was possible.

As a result of further lowering the temperature, H/P was performed at 1000°C with 0.5 wt% of B ₂ O ₃ addition as shown in Comparative Example 3. As a result, the density was 93.4% and densification was not achieved. In addition, also in the case where the composition of ZnO-Al ₂ O ₃ -MgO-SiO ₂ was changed, as shown in Examples 3 and 4, it was confirmed that low-temperature sintering and high density were possible by adding B ₂ O ₃ . All of them were able to obtain bulk resistance values that did not cause problems with DC sputtering.

In contrast to the above, the evaluation results are for the cases where B ₂ O ₃ is added as a low-melting point oxide and the case where it is not added, but even when Bi ₂ O ₃ is used as a low-melting point oxide, as shown in Example 5, B ₂ The same effect as with O ₃ addition was obtained.

Although not shown in the examples, even when materials of Sb ₂ O ₃ , P ₂ O ₅ , K ₂ O, V ₂ O ₅ , TeO ₂ , Ti ₂ O ₃ , PbO, or MoO ₃ are used, they are low melting point oxides. Therefore, it is presumed to have the same effect.

In addition, although the case where the low-melting-point oxide was added alone was described above, the same effect was obtained even when these oxides were added in combination.

Further, a major feature of the present invention is that the target bulk resistance value is reduced, conductivity is provided, and stable DC sputtering is made possible by increasing the relative density to 98% or more. And, there is a remarkable effect that the controllability of sputtering, which is a characteristic of this DC sputtering, can be made easy, and the film formation rate can be increased to improve the sputtering efficiency. RF sputtering is performed as needed, but even in that case, an improvement in film formation speed is observed.

In addition, it is possible to reduce particles (dust) and nodules generated during sputtering during film formation, to improve mass productivity with little variation in quality, and to stably manufacture optical recording media having an optical disc protective film at low cost. It has a remarkable effect. Therefore, the present invention is very useful for optical thin films.

Since the thin film formed using the sputtering target of the present invention forms part of the structure of the optical information recording medium and does not use ZnS, diffusion of sulfur into the recording layer material is eliminated, thereby deteriorating the recording layer. There is a remarkable effect of disappearing.

In addition, when adjacent pure Ag or Ag alloy having high reflectivity and high thermal conductivity is used for the reflective layer, diffusion of the sulfur component into the reflective layer is also eliminated, and the cause of corrosion deterioration of the reflective layer and deterioration of properties is eliminated. have

In addition, as a semi-transmissive layer without the problem of yellowing, a high-refractive-index layer and a low-refractive-index layer may be laminated alternately to provide a semi-transmissive layer having arbitrary optical characteristics. The target of the present invention is also useful as a low refractive index layer constituting a semi-transmissive layer. Further, application to organic EL TV applications, electrodes for touch panels, sheet layers of hard disks, and the like is also possible.

Claims (4)

delete Raw material powders for basic sintering were adjusted so that the total amount of Al ₂ O ₃ powder was 0.2 to 3.0 mol%, the powder of at least one of MgO and SiO ₂ was 10 to 27 mol%, and the balance was ZnO powder, and the total amount thereof was 100 mol% 0.5 to 1.5 wt% of a low-melting oxide powder having a melting point of 1000 ° C or less is further added thereto to obtain a raw material for sintering, the low-melting oxide is B ₂ O ₃ , and the raw material for sintering is 1050 ° C. or higher and less than 1100 ° C. A method for producing a sputtering target characterized in that the target has a relative density of 99.4% or more and a bulk resistance of the target of 10 mΩ cm or less. delete delete

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