JP2012224903A - Oxide sputtering target, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide sputtering target for forming a protective film of an optical recording medium, which can be manufactured through a simplified step without inducing any cracking or elution of In and can achieve high density, and to provide a method for manufacturing the same.SOLUTION: The oxide sputtering target comprises ZrO, InOand ZnO and has a structure in which the ZrOphase is surrounded by a phase containing a multiple oxide phase comprising oxides of In and Zn. Furthermore, based on the total amount of metal components excluding unavoidable impurities, when the atom ratio of Zr is A% and the atom ratio of In and Zn is the remainder, the composition thereof preferably satisfies the relations: 0<A≤47.6 and 0.22≤In (atom ratio)/Zn (atom ratio)≤4.68.

Description

  The present invention relates to an oxide sputtering target for forming a protective film of an optical recording medium and a method for manufacturing the same.

  In recent years, with the improvement of the picture quality of photographs and moving images, digital data when recording on an optical recording medium or the like has increased, and there has been a demand for an increase in the capacity of the recording medium. Blu-ray Disc (registered trademark) having a capacity of 50 GB depending on the system is on the market. The Blu-ray Disc (registered trademark) is desired to have a higher capacity in the future, and research on increasing the capacity by increasing the number of recording layers has been actively conducted.

As a material for the dielectric protective film constituting the Blu-ray Disc (registered trademark), Zr is a main component, and one of In, Si, Cr, Al, Ce, Ti, Sn, Ga, and La is used. An oxide-based material containing two or more types and oxygen has been proposed (see Patent Document 1).
Further, as a sputtering target material for forming such a film, it has excellent crack resistance in which 90% or more of Zr in the above composition is a composite oxide phase of Zr and In and is dispersed in the target substrate. A sputtering target for forming a protective film for a ZrO ₂ —In ₂ O ₃ optical recording medium has been proposed (see Patent Document 2).

JP 2005-56545 A JP 2009-62585 A

The following problems remain in the conventional technology.
High productivity is required for a material for forming a protective film for an inexpensive optical recording medium using an organic dye in the recording layer. However, in the conventional sputtering target, ZrO ₂ is used to prevent cracking during use. And In ₂ O ₃ are pulverized and mixed, dried, fired and crushed, and after adding other oxides, many processes such as pulverized and mixed, dried, molded and fired are required, resulting in poor productivity. There was a problem.
In addition, when the conventional sputtering target is manufactured by a hot press for the purpose of easily manufacturing the above-mentioned conventional sputtering target, if ZrO ₂ is hot pressed at a high temperature, the volume is expanded and cracked due to the phase transition of ZrO ₂ during cooling. And there is a problem that In elutes, and a high-density sputtering target cannot be obtained. In addition, the sputtering target produced at a temperature at which In does not elute has a high specific resistance, and there is a problem that cracking occurs or particles are generated during sputtering.

  The present invention has been made in view of the above-mentioned problems, and can be used for forming a protective film for an optical recording medium without cracking or elution of In during hot press production, simplifying the production process, and high-density oxidation. An object of the present invention is to provide a sputtering target and a manufacturing method thereof.

The inventors of the present invention have made researches on a ZrO ₂ —In ₂ O ₃ -based sputtering target, and by adding ZnO (zinc oxide) to the raw material, there is no cracking or In elution during production by a hot press. It has been found that a high-density sputtering target can be produced by pressure sintering such as hot pressing.

Therefore, the present invention has been obtained from the above findings, and the following configuration has been adopted in order to solve the above problems. That is, the oxide sputtering target of the present invention contains ZrO ₂ , In ₂ O ₃ and ZnO, and the periphery of the ZrO ₂ phase is surrounded by a phase including a complex oxide phase composed of an oxide of In and Zn. It is characterized by having an organization.

This oxide sputtering target contains ZrO ₂ , In ₂ O ₃ and ZnO, and has a structure in which the periphery of the ZrO ₂ phase is surrounded by a phase including a composite oxide phase composed of an oxide of In and Zn. The specific resistance is lowered and the density is increased.

Further, the oxide sputtering target of the present invention has an atomic ratio with respect to the total amount of metal components excluding inevitable impurities, Zr: A%, In and Zn: the balance, and the composition of these components is 0 <A ≦ 47.6 and 0.22 ≦ In (atomic ratio) / Zn (atomic ratio) ≦ 4.68 are satisfied.
This oxide sputtering target contains ZrO ₂ , In ₂ O ₃ and ZnO, and the component composition of Zr, In, Zn satisfies the above relationship, and therefore can be manufactured by pressure sintering such as hot pressing. In addition to excellent productivity, the target has a low specific resistance and a high density, and it is possible to reduce the generation of cracks and particles during sputtering. Moreover, since the specific resistance of the target is reduced, not only RF sputtering but also DC sputtering is possible. In the case of DC sputtering, the deposition rate is high, and oxygen vacancy can be prevented and the transparency of the film can be maintained by performing it in an oxygen atmosphere. Even when compared with a conventional film in which SiO ₂ is added to ZrO ₂ , In ₂ O ₃ as described in Patent Document 1, a film having an equivalent refractive index and extinction coefficient can be obtained.

Here, the reason for limiting the content ratio of the metal component element of the present invention as described above is as follows.
Zr:
When Zr exceeds 47.6 atomic% in terms of the atomic ratio with respect to the total amount of metal components excluding inevitable impurities, the specific resistance of the sputtering target increases and DC sputtering becomes difficult. In order to sufficiently obtain the effect (preservation characteristics as a protective film) by adding ZrO ₂ as described in paragraph No. [0085] of Patent Document 1, Zr should be 6.1 atomic% or more. preferable.
In (atomic ratio) / Zn (atomic ratio):
If In / Zn exceeds 4.68, metal In may elute during sintering. If it is less than 0.22, the sputtered film may crystallize as described in “Semiconductor FPD World 2010.2 pp. 38-40”. When the sputtered film is crystallized, water vapor or the like passes through the crystal grain boundary as a path, and the function as a protective film may be reduced.

The manufacturing method of the oxide sputtering target of the present invention is a method of manufacturing the above-described oxide sputtering target of the present invention, and a mixed powder is prepared by mixing ZrO ₂ powder, In ₂ O ₃ powder, and ZnO powder. And a step of pressure-sintering the mixed powder.
Further, the method of manufacturing an oxide sputtering target of the present invention is a method of producing an oxide sputtering target of the present invention, by mixing the In ₂ O ₃ powder and ZnO powder, calcining the mixed powder A step of producing a primary mixed powder, a step of mixing the primary mixed powder and ZrO ₂ powder to produce a secondary mixed powder, and a step of pressure-sintering the secondary mixed powder. It is characterized by.

That is, in these oxide sputtering target manufacturing methods, since ZrO ₂ powder, In ₂ O ₃ powder, and ZnO powder are used, In ₂ O ₃ and ZnO partially react to stabilize In ₂ O _3. As a result, ZrO ₂ remains as it is without reacting with other metal oxides, so that a structure in which at least a phase composed of In oxide and Zn oxide surrounds the ZrO ₂ phase is obtained. It is done. As described above, the oxide sputtering target having a structure in which an oxide having a semiconductor property forms a conductive path is likely to have a low specific resistance and can be subjected to DC sputtering.

The present invention has the following effects.
That is, according to the oxide sputtering target according to the present invention, ZrO ₂ , In ₂ O ₃ and ZnO are contained, and the ZrO ₂ phase is a phase including a complex oxide phase composed of an oxide of In and Zn. It has an enclosed structure, especially contains ZrO ₂ , In ₂ O ₃ and ZnO, and the composition of Zr, In and Zn satisfies the above relationship, so it can be manufactured by pressure sintering such as hot pressing. Thus, the productivity is excellent, the specific resistance is low, the density is high, and the generation of cracks and particles during sputtering can be reduced.
In addition, according to the method of manufacturing an oxide sputtering target according to the present invention, In ₂ O ₃ and ZnO partially react with each other by using ZrO ₂ powder, In ₂ O ₃ powder, and ZnO powder. ₂ O ₃ is stabilized and difficult to dissolve, and ZrO ₂ remains as it is without reacting with other metal oxides, so that a phase composed of at least an In oxide and a Zn oxide is formed around the ZrO ₂ phase. Enclosed tissue is obtained.
Therefore, by using the oxide sputtering target of the present invention, it is possible to stably form a film having a high transparency and a high refractive index at a high film formation speed by direct current magnetron sputtering, and optical recording with a high recording capacity. It is suitable as a sputtering target for producing a dielectric protective film constituting a medium.

It is a graph which shows the X-ray-diffraction (XRD) result of the produced sputtering target in the Example of the oxide sputtering target which concerns on this invention, and its manufacturing method. In the Example of the oxide sputtering target which concerns on this invention, and its manufacturing method, it is an element distribution image of each element which measured the cross-sectional structure | tissue of the produced sputtering target by EPMA.

  Hereinafter, an embodiment of an oxide sputtering target and a method for producing the same according to the present invention will be described.

The oxide sputtering target of this embodiment is a sputtering target for producing a dielectric protective film constituting an optical recording medium having a high recording capacity, and contains ZrO ₂ , In ₂ O ₃ and ZnO, and contains ZrO _2. The periphery of the phase has a structure surrounded by a phase including a composite oxide phase composed of an oxide of In and Zn.
Moreover, the oxide sputtering target of this embodiment contains ZrO ₂ , In ₂ O ₃ and ZnO, and has an atomic ratio with respect to the total amount of metal components excluding inevitable impurities, Zr: A%, In and Zn: Therefore, these component compositions satisfy the relationship of 0 <A ≦ 47.6, 0.22 ≦ In (atomic ratio) / Zn (atomic ratio) ≦ 4.68.

The method of manufacturing the oxide sputtering target of this embodiment includes a step of mixing a ZrO ₂ powder, an In ₂ O ₃ powder, and a ZnO powder to produce a mixed powder, and a step of pressure-sintering the mixed powder. And have.

An example of this production method will be described in detail. First, raw material powders of zirconium oxide (chemical formula: ZrO ₂ ), indium oxide (chemical formula: In ₂ O ₃ ), and zinc oxide (chemical formula: ZnO) are contained in a predetermined ratio of contained metals. Weigh so that The raw material zirconium oxide may be partially stabilized zirconia (for example, zirconium oxide produced by adding 5 to 10 wt% of Y ₂ O ₃ or CaO).

The weighed raw material powder and 3 times its amount (weight ratio) of zirconia balls (diameter 5 mm) are put in a plastic container and wet mixed in a ball mill apparatus for 18 hours. In addition, alcohol is used for the solvent in this case, for example. Next, the obtained mixed powder is dried and then passed through, for example, a sieve having an opening of 500 μm to form a raw material powder for forming a sintered body, filled in a graphite mold, and then 800 to 1200 ° C., preferably 950 to 1100. Hot pressing is performed in a vacuum or an inert gas atmosphere at a pressure of 200 to 400 kgf / cm ² at 2 ° C. for 2 to 9 hours to obtain a sputtering target.

In addition, another method of manufacturing the oxide sputtering target of the present embodiment includes a step of mixing In ₂ O ₃ powder and ZnO powder, calcining the mixed powder to produce a primary mixed powder, and the primary a step of preparing a secondary mixed powder mixing powder and a ZrO ₂ powder were mixed, and has a step of pressure sintering the secondary mixed powder, a.

  If an example of this manufacturing method is explained in full detail, first, each raw material powder of an indium oxide and a zinc oxide will be measured so that a containing metal may become a predetermined ratio. The weighed raw material powder and 3 times its amount (weight ratio) of zirconia balls (diameter 5 mm) are put in a plastic container and wet mixed in a ball mill apparatus for 18 hours. In addition, alcohol is used for the solvent in this case, for example. Next, after drying the obtained mixed powder, for example, it is passed through a sieve having an opening of 500 μm and fired at 950 to 1100 ° C. for 2 to 20 hours in the air or in an oxygen atmosphere. To do.

Furthermore, zirconium oxide is added to the obtained primary mixed powder so as to have a predetermined atomic ratio, and this mixed powder and a zirconia ball (diameter: 5 mm) of 5 times its weight (weight ratio) are put in a plastic container and placed in a ball mill apparatus. For 24 hours to obtain a secondary mixed powder. In addition, alcohol is used for the solvent in this case, for example. After the obtained secondary mixed powder is dried, for example, it is passed through a sieve having an opening of 500 μm to form a raw material powder for forming a sintered body, filled in a graphite mold, and then 800 to 1200 ° C., preferably 950 to 1100 ° C. For 2 to 9 hours at a pressure of 200 to 400 kgf / cm ^{2 in} a vacuum or an inert gas atmosphere to obtain a sputtering target.

Thus, in the oxide sputtering target of the present embodiment, ZrO ₂ , In ₂ O ₃ and ZnO are contained, and the periphery of the ZrO ₂ phase is surrounded by a phase including a complex oxide phase composed of an oxide of In and Zn. As a result, the resistivity decreases and the density increases.
In particular, it contains ZrO ₂ , In ₂ O ₃ and ZnO, and since the component composition of Zr, In, Zn satisfies the above relationship, it can be manufactured by pressure sintering such as hot pressing, and is excellent in productivity. In addition, the specific resistance is low and the density is high, and the generation of cracks and particles can be reduced. In addition, since the specific resistance is low, not only RF sputtering but also DC sputtering is possible. In the case of DC sputtering, the film formation rate is high, and sputtering is performed in an atmosphere in which oxygen is mixed during sputtering, whereby oxygen deficiency can be prevented and the transparency of the film can be maintained. In addition, a film having a refractive index and extinction coefficient equivalent to those obtained when conventional SiO ₂ is added can be obtained.

Further, in the method of manufacturing an oxide sputtering target of the present embodiment, since the use of the ZrO ₂ powder and In ₂ O ₃ powder and ZnO powder, partially reacted and the In and Zn In melts stabilized In addition to being difficult, Zr remains as it is without reacting with other metals, thereby obtaining a structure in which the ZrO ₂ phase is surrounded by at least a phase composed of In oxide and Zn oxide.

The result of having evaluated about the Example of the oxide sputtering target actually produced based on the said this embodiment and its manufacturing method is demonstrated.
[Example 1]
Each raw material powder of zirconium oxide (purity: 3N, average particle size: 10 μm), indium oxide (purity: 3N, average particle size: 6 μm), and zinc oxide (purity: 3N, average particle size: 1.4 μm) was converted into Zr. Is 0.6 atomic% and In / Zn is 2.5 (atomic ratio).
The weighed raw material powder and 3 times its amount (weight ratio) of zirconia balls (diameter 5 mm) are put in a plastic container and wet mixed in a ball mill apparatus for 18 hours. In addition, alcohol was used for the solvent in this case. Next, the obtained mixed powder was dried, passed through a sieve having an opening of 500 μm, used as a raw material powder for forming a sintered body, filled in a graphite mold, and then 350 kgf / cm ² at 1050 ° C. for 3 hours. A vacuum hot press was performed at a pressure of 1 to obtain a sputtering target of Example 1.

[Example 2]
The raw material powder was the same as in Example 1, and weighed so that Zr was 6.1 atomic% and In / Zn was 4.68 (atomic ratio). Each step after the weighing was performed in the same manner as in Example 1, and the sputtering target of Example 2 was produced.
[Example 3]
The raw material powder was the same as in Example 1, and weighed so that Zr was 47.6 atomic% and In / Zn was 0.22 (atomic ratio). Each step after weighing was performed in the same manner as in Example 1, and the sputtering target of Example 3 was produced.
[Example 4]
The same raw material powder as in Example 1, and each raw material powder of indium oxide and zinc oxide was weighed so that In / Zn was 0.22 (atomic ratio). The weighed raw material powder and 3 times its amount (weight ratio) of zirconia balls (diameter 5 mm) are put in a plastic container and wet mixed in a ball mill apparatus for 18 hours. In addition, alcohol was used for the solvent in this case. Next, the obtained mixed powder is dried, passed through a sieve having an opening of 500 μm, used as a raw material powder for forming a sintered body, filled in a graphite mold, and then at 1100 ° C. for 3 hours in the air. Firing was performed to obtain a primary mixed powder of calcined powder.

Further, zirconium oxide is added to the obtained primary mixed powder so as to be 47.6 atomic%, and this mixed powder and its five times amount (weight ratio) zirconia balls (diameter 5 mm) are put in a plastic container, and a ball mill The mixture was wet mixed for 24 hours to form a secondary mixed powder. In addition, alcohol was used for the solvent in this case. The obtained secondary mixed powder was dried, sieved through a sieve of 500 μm, and vacuum hot pressed at 1050 ° C. for 3 hours at a pressure of 350 kgf / cm ² to obtain a sputtering target of Example 4.

[Comparative Example 1]
The same raw material powder as in Example 1, and each raw material powder of indium oxide and zinc oxide was weighed so that In / Zn was 0.15 (atomic ratio). Each step after the weighing was performed in the same manner as in Example 1, and a sputtering target of Comparative Example 1 was produced.

[Comparative Example 2]
The raw material powder was the same as in Example 1, and weighed so that Zr was 49.0 atomic% and In / Zn was 4.9 (atomic ratio). Each step after the weighing was performed in the same manner as in Example 1, and a sputtering target of Comparative Example 2 was produced.

[Conventional example]
Each raw material powder of zirconium oxide (purity: 3N, average particle size: 10 μm), indium oxide (purity: 3N, average particle size: 6 μm), and silicon oxide (purity: 4N, average particle size: 0.2 μm) was converted into Zr. Was 16.9 atomic% and In / Si was 3.03 (atomic ratio). Each process after the weighing was performed in the same manner as in Example 1 to produce a sputtering target of a conventional example.

<Evaluation>
About the sputtering target of each Example and the comparative example, the presence or absence of the metal elution after hot pressing was confirmed, and the relative density was calculated | required.
The relative density was calculated by machining the sintered body to a predetermined size, measuring the weight, obtaining the bulk density, and dividing by the theoretical density. The theoretical density was determined as follows.

  The presence or absence of metal elution was confirmed by whether or not a metal diffraction peak was observed as a result of X-ray diffraction measurement. The measurement conditions of X-ray diffraction are as follows.

Preparation of sample: The sample was wet-polished with SiC-Paper (grit 180) and dried, and then used as a measurement sample.
Equipment: Rigaku Electric (RINT-Ultima / PC)
Tube: Cu
Tube voltage: 40 kV
Tube current: 40 mA
Scanning range (2θ): 5 ° to 90 °
Slit size: Divergence (DS) 2/3 degree, Scattering (SS) 2/3 degree, Light reception (RS) 0.8mm
Measurement step width: 0.02 degrees at 2θ Scan speed: 2 degrees per minute Sample stage rotation speed: 30 rpm
The evaluation results are shown in Table 1. Moreover, the X-ray-diffraction measurement result of the sputtering target of Example 1 is shown in FIG.

From Table 1, it can be seen that in Example 1 containing ZnO, a high-density sputtering target without metal elution is obtained. Further, as shown in FIG. 1, the sputtering target of Example, a diffraction peak attributable to ZrO ₂ was confirmed.

<EPMA analysis>
The structure of the sputtering target of Example 1 was observed with an EPMA (field emission electron beam probe) using a reflected electron image (CP) and an element distribution image showing the composition distribution of each element. The reflected electron image and element distribution image are shown in FIG.
The element distribution image by EPMA is originally a color image, but is described after being converted into a black and white image, and thus a light and dark portion (relatively white portion) is a portion where the concentration of the predetermined element is high. .
From these images, it can be seen that the sputtering target of Example 1 has the structure in which ZrO ₂ remains as it is and the periphery is surrounded by a phase composed of In oxide and Zn oxide.

<Specific resistance measurement>
The specific resistance of the sputtering target was measured using a resistance measuring instrument Loresta GP manufactured by Mitsubishi Chemical.

The technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment and the above examples, pressure sintering is performed by hot pressing, but as another method, a HIP method (hot isostatic pressing method) or the like may be employed.

Claims (4)

Containing ZrO ₂ , In ₂ O ₃ and ZnO,
An oxide sputtering target characterized in that the ZrO ₂ phase has a structure surrounded by a phase including a composite oxide phase composed of an oxide of In and Zn. In the oxide sputtering target according to claim 1,
In the atomic ratio to the total metal component amount excluding inevitable impurities, Zr: A%, In and Zn: the balance, the composition of these components is
0 <A ≦ 47.6,
0.22 ≦ In (atomic ratio) / Zn (atomic ratio) ≦ 4.68,
An oxide sputtering target characterized by satisfying the relationship: A method for producing the oxide sputtering target according to claim 1, comprising:
Mixing ZrO ₂ powder, In ₂ O ₃ powder and ZnO powder to produce a mixed powder;
And a step of pressure-sintering the mixed powder. A method for producing an oxide sputtering target. A method for producing the oxide sputtering target according to claim 1, comprising:
A step of mixing In ₂ O ₃ powder and ZnO powder and calcining this mixed powder to produce a primary mixed powder;
Mixing the primary mixed powder and ZrO ₂ powder to produce a secondary mixed powder;
And a step of pressure-sintering the secondary mixed powder. A method for producing an oxide sputtering target.