WO2014054361A1 - Zinc oxide-based sintered compact, zinc oxide-based sputtering target consisting of this sintered compact, and zinc oxide-based thin film obtained by sputtering this target - Google Patents

Description

Zinc oxide-based sintered body, zinc oxide-based sputtering target comprising the sintered body, and zinc oxide-based thin film obtained by sputtering the target

The present invention relates to a zinc oxide-based sintered body containing zinc oxide as a main component, a zinc oxide-based sputtering target composed of the sintered body, and a zinc oxide-based thin film obtained by sputtering the target.

In recent years, high-density recording optical disc technology, which is a rewritable high-density optical information recording medium without requiring a magnetic head, has been developed and rapidly commercialized. In particular, CD-RW appeared in 1977 as a rewritable CD and is the most popular phase change optical disk at present. The CD-RW is rewritten about 1000 times.
Also, DVD-RW has been developed and commercialized for DVD use, but the layer structure of this disc is basically the same as or similar to CD-RW. The number of rewrites is about 1000 to 10,000.
These are used to record, reproduce, and append information by causing optical changes such as transmittance and reflectance of the recording material by irradiating with a light beam. is there.

In general, a phase change optical disk used for CD-RW, DVD-RW, or the like is formed on both sides of a recording thin film layer such as Ag-In-Sb-Te system or Ge-Sb-Te system with a high level of ZnS / SiO ₂ or the like. It has a four-layer structure sandwiched between protective layers of melting point dielectrics and further provided with a reflective film of silver, silver alloy, or aluminum alloy. In order to increase the number of repetitions, an interface layer is added between the memory layer and the protective layer as necessary.
The reflective layer and the protective layer are required to have an optical function to increase the difference in reflectance between the amorphous portion and the crystalline portion of the recording layer, and also have a moisture resistance of the recording thin film and a function to prevent deformation due to heat. A function called thermal condition control is required (see Non-Patent Document 1).

Recently, a single-sided dual-layer optical recording medium has been proposed in order to enable high-capacity and high-density recording (see Patent Document 1). In this Patent Document 1, there are a first information layer formed on the substrate 1 and a second information layer formed on the substrate 2 from the incident direction of the laser light, and these information layers are mutually connected via an intermediate layer. They are attached to face each other.
In this case, the first information layer is composed of a recording layer and a first metal reflective layer, and the second information layer is a first protective layer,
It consists of a second protective layer, a recording layer, and a second metal reflective layer. In addition to this, layers such as a hard coat layer and a heat diffusion layer for protecting from scratches, dirt and the like may be arbitrarily formed. Various materials have been proposed for these protective layers, recording layers, reflective layers, and the like.

The protective layer made of a high-melting-point dielectric is resistant to repeated thermal stresses caused by heating and cooling, and further prevents these thermal effects from affecting the reflective film and other parts. Thin, low reflectivity and toughness that does not change is required. In this sense, the dielectric protective layer has an important role. Needless to say, the recording layer, the reflective layer, the interference film layer, and the like also function in the optical recording medium such as the CD, DVD, Blu-ray (registered trademark) described above. Just as important is the argument.

These thin films having a multilayer structure are usually formed by a sputtering method. In this sputtering method, a substrate composed of a positive electrode and a negative electrode is opposed to a target, and an electric field is generated by applying a high voltage between the substrate and the target in an inert gas atmosphere. Electrons that have been ionized and an inert gas collide to form a plasma. The cations in the plasma collide with the target (negative electrode) surface and knock out target constituent atoms, and the substrate that the ejected atoms face. This is based on the principle that a film is formed on the surface.

Conventionally, since the protective layer is required to have transparency in the visible light range, heat resistance, and the like, a thin film of about 500 to 2000 mm is formed by sputtering using a ceramic target such as ZnS—SiO ₂ . These materials are formed using a high frequency sputtering (RF) apparatus or a magnetron sputtering apparatus.
However, since ZnS—SiO ₂ is an insulating material, it requires an expensive RF power source, and since the ZnS—SiO ₂ film contains sulfide, it corrodes the adjacent metal layer (especially Ag alloy reflective layer). In addition, there is a problem that it is not suitable for high-speed recording because of its low thermal conductivity.

The inventors have developed a sputtering target using a homologous compound based on zinc oxide (see Patent Document 2) and a sputtering target based on tin oxide (see Patent Document 3). Although it has the same characteristics as ZnS—SiO ₂ without being included, a material having high thermal conductivity has not been obtained. Further, the sintered body based on zinc oxide has a problem that it is easily cracked during the manufacturing process or sputtering.

JP 2006-79710 A JP 2009-062618 A JP 2005-154820 A

Technical magazine "Optical" Vol. 26, No. 1, pages 9 to 15

An object is to obtain a zinc oxide-based thin film having electrical conductivity and high thermal permeability, a zinc oxide-based sintered body suitable for manufacturing the thin film, and a zinc oxide-based sputtering target composed of the sintered body.

The present inventors have intensively studied to solve the above problems, and as a result, by selecting a metal as a zinc oxide-based material and adding it to zinc oxide, the crystallinity is not improved by heating film formation. In both cases, it was found that an oxide thin film having a high thermal permeability can be obtained, and that a sintered body that is difficult to break during the manufacturing process or sputtering is obtained.

The phonons and conduction electrons are responsible for heat conduction, but materials with high insulating properties such as alumina have almost no conduction electrons, so only phonons contribute. In addition, since a film obtained by sputtering film formation at a normal temperature is poor in crystallinity, conduction through phonons is generally low.

In such a situation, the present inventors pay attention to a zinc oxide-based thin film that is easily crystallized even by sputtering at room temperature. By adding a dopant, the conductive electrons are increased, and a metal having a higher thermal conductivity is added. A method of increasing the heat penetration rate (thermal conductivity) by adding was considered. Therefore, a metal having a thermal conductivity of 80 W / mK or more and a melting point higher than the sintering temperature of zinc oxide (about 1000 ° C.) is desirable. Furthermore, by adding powder whose average particle size range is adjusted to 0.5 to 50 μm, part or all of the added metal can be dispersed and retained uniformly as a metal in the sintered body. It was found that by adding carbon powder, the oxidized layer on the surface of the added metal was reduced and removed, and the zinc oxide was also slightly reduced, thereby lowering the bulk resistivity of the sintered body and making the sintered body resistant to cracking. It was.
In addition, the residual confirmation of the added metal M is performed by a simple quantitative analysis of EPMA. Usually, the determination is made based on the presence of 95% by mass or more of the metal M and the amount of oxygen in the range of 3% by mass or less in the vicinity of the center of the metal M particles in the sintered body.

This application provides the following invention based on said knowledge.
1) containing zinc oxide (ZnO) as a main component, containing gallium (Ga), aluminum (Al) or boron (B) as an n-type dopant with respect to zinc oxide, containing 10 to 300 wtppm of carbon, and , Cobalt (Co), nickel (Ni), iron (Fe), copper (Cu), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tungsten (W), iridium (Ir), gold (Au) Containing at least one metal element M selected from the group consisting of zinc, n-type dopant, and all metal elements constituting the zinc oxide-based sintered body. Zinc oxide-based sintered body in which the concentration of metal M with respect to is adjusted to 0.05 to 25.0 atomic%.

2) When the n-type dopant is gallium (Ga), the zinc concentration based on the total number of atoms of zinc, Ga and oxygen is 1 to 7 atomic%. body.
3) The oxidation according to 1) above, wherein when the n-type dopant is aluminum (Al), the Al concentration relative to the total number of atoms of zinc, Al and oxygen is 0.5 to 3.5 atomic%. Zinc-based sintered body.
4) The oxidation according to 1) above, wherein when the n-type dopant is boron (B), the B concentration with respect to the total number of atoms of zinc, B and oxygen is 0.5 to 5.5 atomic%. Zinc-based sintered body.

5) The zinc oxide-based sintered body according to any one of 1) to 4) above, wherein the average particle diameter of the metal M is adjusted to a range of 1 to 10 μm.
6) A sputtering target comprising the zinc oxide-based sintered body according to any one of 1) to 5) above.
7) A thin film obtained by sputtering a sputtering target comprising the zinc oxide-based sintered body described in 6) above.
8) The thin film according to 7) above, wherein the thermal permeability of the film is 1600 (J / sec ^0.5 m ² K) or more.

In the present invention, an appropriate concentration of a metal having a thermal conductivity of 80 W / mK or more and a melting point higher than the sintering temperature of zinc oxide (about 1000 ° C.) is added to a zinc oxide thin film to which an n-type dopant is added. This has the effect of dramatically increasing the heat permeability of the zinc oxide thin film, and enables high heat permeability with a transparent or translucent oxide.
Thereby, it is possible to provide a thin film having a high thermal permeability that cannot be realized by a material system including a conventional zinc oxide system.

A sintered body containing zinc oxide (ZnO) as a main component, containing an element serving as an n-type dopant with respect to zinc oxide, and containing 10 to 300 wtppm of carbon with respect to the total amount of the sintered body. The rate of 80 W / mK or more, containing a metal M having a melting point higher than the sintering temperature of zinc oxide (about 1000 ° C.), the zinc constituting the zinc oxide thin film, the n-type dopant, and the metal M with respect to all metal elements A zinc oxide-based thin film forming sputtering target having a concentration of 0.05 to 25.0 atomic% is provided.

As the n-type dopant of the target, gallium (Ga) can be used, and the concentration with respect to the total number of atoms of zinc, Ga and oxygen is preferably 1 to 7 atomic%. Aluminum (Al) or boron (B) can be used as the n-type dopant.
In this case, the concentration with respect to the total number of atoms of zinc, Al and oxygen is 0.5 to 3.5 atomic%, and the B concentration with respect to the total number of atoms of zinc, B and oxygen is 0.5 to 5.5 atomic%. To do. As the metal M, cobalt (Co), nickel (Ni), iron (Fe) or copper (Cu), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tungsten (W), iridium (Ir), Gold (Au) is preferred, and one or more elements selected from these can be used.
When forming a zinc oxide-based thin film, an integrated sputtering target having the same composition as that of the zinc oxide-based thin film is formed, and by sputtering this, the components of the target are reflected in the resulting film, and almost the same component composition It is possible to form a zinc oxide-based thin film.

Further, it contains zinc oxide powder, oxide powder of an element that becomes an n-type dopant with respect to zinc oxide, and carbon powder in an amount of 10 to 300 wtppm, a thermal conductivity of 80 W / mK or more, and a zinc oxide sintering temperature ( The metal M powder having a melting point higher than about 1000 ° C. is adjusted so that the concentration of the metal M with respect to the zinc, n-type dopant, and all metal elements constituting the zinc oxide thin film is 0.05 to 25.0 atomic%. Provided is a method for producing a sputtering target for forming a zinc oxide-based thin film by weighing each raw material powder, mixing them, and then pressure sintering to form a sintered body.

In this method of manufacturing a sputtering target for forming a zinc oxide-based thin film, the n-type dopant is gallium (Ga), and oxidation is performed so that the Ga concentration with respect to the total number of atoms of zinc, Ga and oxygen is 1 to 7 atomic%. A mixture of gallium powder can be used.
For this n-type dopant, aluminum (Al) is used, and aluminum oxide powder is mixed so that the Al concentration is 0.5 to 3.5 atomic% with respect to the total number of atoms of zinc, Al and oxygen. Can do. Similarly, boron oxide powder can be mixed using boron (B) so that the B concentration with respect to the total number of atoms of zinc, B, and oxygen is 0.5 to 5.5 atomic%.

Carbon powder can be added in an amount of 10 to several thousand wtppm with respect to the total amount, but considering that it is used for oxide reduction during powder adjustment or sintering, the amount of residual carbon in the sintered body is 10%. Adjust to ˜300 wtppm. Further, as the metal M, cobalt (Co) powder, nickel (Ni) powder, iron (Fe) powder, copper (Cu) powder, molybdenum (Mo) powder, ruthenium (Ru) powder, rhodium (Rh) powder, tungsten (W ) One or more powders selected from powder, iridium (Ir) powder, and gold (Au) powder can be used.

In the thin film of the present invention, by adding an n-type dopant to zinc oxide, electrons supplied from the dopant contribute to thermal conduction, so that the thermal conductivity increases. However, the n-type dopant at that time is a candidate. This is an element having a trivalent or tetravalent valence having a valence higher than that of zinc because it needs to enter the lattice position of zinc and emit electrons. From the viewpoint of the impurity level of the element, Ga and Al are most appropriate.

When Ga is used, if the concentration with respect to the total number of atoms of zinc, Ga and oxygen is less than 1 atomic%, the concentration of electrons emitted from the dopant will not be sufficiently high. Few. However, if it exceeds 7 atomic%, it remains neutral without being ionized and does not emit electrons, but is present in zinc oxide and scatters phonons and conduction electrons, resulting in a low thermal permeability. Accordingly, an appropriate value of the Ga concentration as the n-type dopant is in the range of 1 to 7 atomic% with respect to the total number of zinc, Ga and oxygen atoms. For the same reason, the appropriate value of the Al concentration as the n-type dopant is in the range of 0.5 to 3.5 atomic%, and the appropriate value of the B concentration is in the range of 0.5 to 5.5 atomic%. Appropriate values for the content of these Ga, Al, and B n-type dopants have been confirmed by a number of experimental values.

Further, when the metal M added to improve the thermal permeability is less than 0.05 atomic% with respect to the total number of atoms of zinc, n-type dopant and metal M constituting the zinc oxide thin film, If the thermal penetrability improvement effect decreases, conversely, if it exceeds 25.0 atomic%, penetration into the grain boundary also occurs, disturbing the crystallinity of zinc oxide and reducing the thermal permeability. I will invite you.

Further, the metal M to be added is different from zinc oxide in that it has conductivity but not transparency. Therefore, when it is added at a high concentration, the transmittance is reduced and the transparency is deteriorated. Therefore, the concentration of the metal M to be added is suitably in the range of 0.05 to 25.0 atomic% with respect to the total number of atoms of zinc, n-type dopant, and metal M constituting the zinc oxide thin film. The appropriate value of the content of the metal M to be added has been confirmed by many experiments.

A physical vapor deposition method can be used to produce the zinc oxide-based thin film of the present invention. Physical vapor deposition methods include vapor deposition, reactive plasma vapor deposition, sputtering, and laser ablation. However, it is possible to form a relatively uniform film over a large area, and there is little deviation between the target composition and film composition. The sputtering method is suitable in that it is excellent in the above.
The target in the sputtering method can be an integrated target, but the final composition of the film can be achieved by combining mosaic targets, or by sputtering each of zinc oxide, n-type dopant, and metal targets independently. The predetermined range can also be set.

Next, the present invention will be described based on examples. The following examples are for ease of understanding, and the present invention is not limited by these examples. That is, modifications and other embodiments based on the technical idea of the present invention are naturally included in the present invention.

(Example 1)
Each raw material powder of zinc oxide having an average particle diameter of 5 μm, gallium oxide (Ga ₂ O ₃ ), and Cu as the additive metal M (average particle diameter of 10 μm) was 94.9: 5.0: 0.1 (wt%). The carbon powder having an average particle diameter of 1 μm was further added so as to be 150 wtppm with respect to the total amount, and mixed for about 10 hours by a dry ball mill.

Next, 1000 g of the raw material mixed in a die having a diameter of 170 mm is filled, and while flowing argon (Ar) gas, the temperature is increased from room temperature at 5 ° C / min. After reaching 1000 ° C, 30 minutes After maintaining as it was, the pressure was increased to 300 kgf / cm ² over 30 minutes.
Thereafter, 1000 ° C, after the state of the pressure 300 kgf / cm ² and held for 2 hours, stop the heating of the furnace, it went down to a pressure over ^{300kgf / cm 2 ~ 0kgf / cm} 2 to 30 minutes. The target taken out from the furnace was processed into a disk shape having a diameter of 152 mm and a thickness of 5 mm to obtain a sputtering target.

The resulting target had no problems such as cracking, and its components were analyzed. As a result, part of the carbon was reduced during sintering to 50 wtppm, and the concentration of metal M (Cu) with respect to all metal atoms was 0.1 atomic%. The Ga concentration based on the total number of atoms of zinc, Ga and oxygen was 2.2 atomic%. In addition, 95% by mass or more of metal M (Cu) is present near the center of the metal M (Cu) particles in the sintered body, and oxygen is 3% by mass or less. Residue was confirmed.
A part of the target, a sample of 10 mmΦ × 1 mmt, was processed and the thermal conductivity was measured by the laser flash method, which was 42 W / mK. Moreover, it was 500 microhm * cm when the resistivity of the target surface was measured by the 4-terminal method.

Using the obtained target of Corning # 1737 glass with a diameter of 4 inches and a thickness of 0.7 mm as a substrate, an Ar atmosphere of 0.5 Pa, an Ar flow rate of 50 sccm, and a sputtering power of 500 W, the film formation time was adjusted to be about 1000 nm. Then, sputter film formation was performed. Further, a 100 nm film of Mo was formed on the sample under the same conditions. The obtained film was adjusted to about 10 mm square, and the thermal permeability was measured with a thermophysical microscope. As a result, it was 1700 (J / s ^0.5 m ² K). The results are shown in Table 1.

(Example 2)
Each raw material powder of zinc oxide having an average particle diameter of 5 μm, aluminum oxide (Al ₂ O ₃ ), and Co (average particle diameter of 10 μm) as an additive metal M was weighed to be 94: 1: 5 (wt%), Further, carbon powder having an average particle diameter of 1 μm was added to 500 wtppm with respect to the total amount, and mixed for about 10 hours by a dry ball mill.

Next, 1000 g of the raw material mixed in a die having a diameter of 170 mm is filled, and while flowing argon (Ar) gas, the temperature is increased from room temperature at 5 ° C / min. After reaching 1000 ° C, 30 minutes After maintaining as it was, the pressure was increased to 300 kgf / cm ² over 30 minutes.
Thereafter, 1000 ° C, after the state of the pressure 300 kgf / cm ² and held for 2 hours, stop the heating of the furnace, it went down to a pressure over ^{300kgf / cm 2 ~ 0kgf / cm} 2 to 30 minutes. The target taken out from the furnace was processed into a disk shape having a diameter of 152 mm and a thickness of 5 mm to obtain a sputtering target.

The resulting target had no problems such as cracking, and its components were analyzed. As a result, part of the carbon was reduced during sintering to 280 wtppm, and the concentration of metal M (Co) with respect to all metal atoms was 6.7 atomic%. The Al concentration with respect to the total number of atoms of zinc, Al, and oxygen was 0.8 atomic%. In the same manner as in Example 1, it was confirmed that the additive metal M (Co) remained.
A part of the target, a sample of 10 mmΦ × 1 mmt, was processed and the thermal conductivity was measured by a laser flash method, which was 45 W / mK. Moreover, it was 400 microhm * cm when the resistivity of the target surface was measured by the 4-terminal method.

Using the obtained target of Corning # 1737 glass with a diameter of 4 inches and a thickness of 0.7 mm as a substrate, an Ar atmosphere of 0.5 Pa, an Ar flow rate of 50 sccm, and a sputtering power of 500 W, the film formation time was adjusted to be about 1000 nm. Then, sputter film formation was performed. Further, a 100 nm film of Mo was formed on the sample under the same conditions. The obtained film was adjusted to about 10 mm square, and the thermal permeability was measured with a thermophysical microscope. As a result, it was 2000 (J / s ^0.5 m ² K). The results are shown in Table 1.

(Example 3)
Each raw material powder of zinc oxide having an average particle diameter of 5 μm, gallium oxide (Ga ₂ O ₃ ), and Ni (average particle diameter of 10 μm) as the additive metal M was weighed so as to be 77: 4: 19 (wt%), Further, a carbon powder having an average particle diameter of 1 μm was added so as to be 100 wtppm with respect to the total amount, and mixed with a dry ball mill for about 10 hours.

Next, 1000 g of the raw material mixed in a die having a diameter of 170 mm is filled, and while flowing argon (Ar) gas, the temperature is increased from room temperature at 5 ° C / min. After reaching 1000 ° C, 30 minutes After maintaining as it was, the pressure was increased to 300 kgf / cm ² over 30 minutes.
Thereafter, 1000 ° C, after the state of the pressure 300 kgf / cm ² and held for 2 hours, stop the heating of the furnace, it went down to a pressure over ^{300kgf / cm 2 ~ 0kgf / cm} 2 to 30 minutes. The target taken out from the furnace was processed into a disk shape having a diameter of 152 mm and a thickness of 5 mm to obtain a sputtering target.

The resulting target has no problems such as cracking, and its components were analyzed. The carbon was 30 wtppm, the concentration of metal M (Ni) with respect to all metal atoms was 24.7 atomic%, and the total number of atoms of zinc, Ga and oxygen. The Ga concentration relative to was 2.1 atomic%. As in Example 1, the residual additive metal M (Ni) was confirmed.
A part of the target, a sample of 10 mmΦ × 1 mmt, was processed and the thermal conductivity was measured by the laser flash method, which was 55 W / mK. Moreover, it was 200 microhm * cm when the resistivity of the target surface was measured by the 4-terminal method.

Using the obtained target of Corning # 1737 glass with a diameter of 4 inches and a thickness of 0.7 mm as a substrate, an Ar atmosphere of 0.5 Pa, an Ar flow rate of 50 sccm, and a sputtering power of 500 W, the film formation time was adjusted to be about 1000 nm. Then, sputter film formation was performed. Further, a 100 nm film of Mo was formed on the sample under the same conditions. The obtained film was adjusted to about 10 mm square, and the thermal permeability was measured with a thermophysical microscope. As a result, it was 2500 (J / s ^0.5 m ² K). The results are shown in Table 1.

Example 4
Each raw material powder of zinc oxide having an average particle diameter of 5 μm, boron oxide (B ₂ O ₃ ) and Co (average particle diameter of 10 μm) as an additive metal M was weighed so as to be 95: 2: 3 (wt%), Further, carbon powder having an average particle diameter of 1 μm was added to 150 wtppm with respect to the total amount, and mixed for about 10 hours by a dry ball mill.

Next, 1000 g of the raw material mixed in a die having a diameter of 170 mm is filled, and while flowing argon (Ar) gas, the temperature is increased from room temperature at 5 ° C / min. After reaching 1000 ° C, 30 minutes After maintaining as it was, the pressure was increased to 300 kgf / cm ² over 30 minutes.
Thereafter, 1000 ° C, after the state of the pressure 300 kgf / cm ² and held for 2 hours, stop the heating of the furnace, it went down to a pressure over ^{300kgf / cm 2 ~ 0kgf / cm} 2 to 30 minutes. The target taken out from the furnace was processed into a disk shape having a diameter of 152 mm and a thickness of 5 mm to obtain a sputtering target.

The resulting target had no problems such as cracking, and its components were analyzed. As a result, part of the carbon was reduced to 50 wtppm during sintering, and the concentration of metal M (Co) with respect to all metal atoms was 4.0 atomic%. The B concentration relative to the total number of atoms of zinc, B and oxygen was 2.3 atomic%. In the same manner as in Example 1, it was confirmed that the additive metal M (Co) remained.
A part of the target, a 10 mmΦ × 1 mmt sample, was processed and the thermal conductivity was measured by the laser flash method, which was 43 W / mK. Moreover, it was 600 microhm * cm when the resistivity of the target surface was measured by the 4-terminal method.

Using the obtained target of Corning # 1737 glass with a diameter of 4 inches and a thickness of 0.7 mm as a substrate, an Ar atmosphere of 0.5 Pa, an Ar flow rate of 50 sccm, and a sputtering power of 500 W, the film formation time was adjusted to be about 1000 nm. Then, sputter film formation was performed. Further, a 100 nm film of Mo was formed on the sample under the same conditions. The obtained film was adjusted to about 10 mm square, and the thermal permeability was measured with a thermophysical microscope. As a result, it was 1900 (J / s ^0.5 m ² K). The results are shown in Table 1.

(Comparative Example 1)
Each raw material powder of zinc oxide having an average particle size of 5 μm and aluminum oxide (Al ₂ O ₃ ) (average particle size of 10 μm) is weighed to 99: 1 (wt%) and mixed for about 10 hours in a dry ball mill. did. In this case, metal M was not added.

Next, 1000 g of the raw material mixed in a die having a diameter of 170 mm is filled, and while flowing argon (Ar) gas, the temperature is increased from room temperature at 5 ° C / min. After reaching 1000 ° C, 30 minutes After maintaining as it was, the pressure was increased to 300 kgf / cm ² over 30 minutes.
Thereafter, 1000 ° C, after the state of the pressure 300 kgf / cm ² and held for 2 hours, stop the heating of the furnace, it went down to a pressure over ^{300kgf / cm 2 ~ 0kgf / cm} 2 to 30 minutes. The target taken out from the furnace was processed into a disk shape having a diameter of 152 mm and a thickness of 5 mm to obtain a sputtering target.

When the components were analyzed, the concentration of metal M with respect to all metal atoms was 0 atomic%, and the Al concentration with respect to the total number of atoms of zinc, Al, and oxygen was 0.8 atomic%.
A part of the target, a sample of 10 mmΦ × 1 mmt, was processed and the thermal conductivity was measured by the laser flash method. As a result, it was 40 W / mK, which was lower than that of the example. Moreover, it was 500 microhm * cm when the resistivity of the target surface was measured by the 4-terminal method.

Using the obtained target of Corning # 1737 glass with a diameter of 4 inches and a thickness of 0.7 mm as a substrate, an Ar atmosphere of 0.5 Pa, an Ar flow rate of 50 sccm, and a sputtering power of 500 W, the film formation time was adjusted to be about 1000 nm. Then, sputter film formation was performed. Further, a 100 nm film of Mo was formed on the sample under the same conditions. When the obtained film was adjusted to about 10 mm square and the thermal permeability was measured with a thermophysical microscope, it was 1400 (J / s ^0.5 m ² K), which was lower than in the examples. The results are shown in Table 1.

As described above, regardless of whether the n-type dopant is Ga, Al, or B, the metal (M) defined in the present invention is added in a predetermined concentration range, so that the zinc oxide thin film The heat penetration rate could be improved. This is one of the major features of the present invention. In addition, about the other metal element M prescribed | regulated by the claim of this application, although an Example is not specifically shown, it confirmed that the effect similar to the said Example was exhibited.
In addition, Examples 1 to 4 are based on experimental data of typical component compositions, but the same as Examples 1 to 4 within the range of the component compositions specified in the claims of the present application. A number of experiments have confirmed that the effect is obtained.

As described above, according to the present invention, an optical recording medium, in which a transparent and high thermal permeability thin film that could not be realized by a conventional method can be realized by sputtering deposition of a zinc oxide-based target, It is very useful as a heat storage material for magnetic recording media and transparent conductors.

Claims (8)

It contains zinc oxide (ZnO) as a main component, contains gallium (Ga), aluminum (Al), or boron (B) as an n-type dopant with respect to zinc oxide, contains 10 to 300 wtppm of carbon, and cobalt (Co), nickel (Ni), iron (Fe), copper (Cu), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tungsten (W), iridium (Ir), gold (Au) The metal M contains at least one or all of the metal elements M, and the metal M remains in the sintered body as at least a part or all of the metal, and the zinc, the n-type dopant, and the metal for all metal elements constituting the zinc oxide-based sintered body A zinc oxide-based sintered body in which the concentration of M is adjusted to 0.05 to 25.0 atomic%. The zinc oxide-based sintered body according to claim 1, wherein when the n-type dopant is gallium (Ga), the Ga concentration relative to the total number of atoms of zinc, Ga and oxygen is 1 to 7 atomic%. 2. The zinc oxide system according to claim 1, wherein when the n-type dopant is aluminum (Al), the Al concentration with respect to the total number of atoms of zinc, Al and oxygen is 0.5 to 3.5 atomic%. Sintered body. 2. The zinc oxide system according to claim 1, wherein when the n-type dopant is boron (B), the B concentration with respect to the total number of atoms of zinc, B and oxygen is 0.5 to 5.5 atomic%. Sintered body. The zinc oxide-based sintered body according to any one of claims 1 to 4, wherein the average particle diameter of the metal M is adjusted to a range of 1 to 10 µm. A sputtering target comprising the zinc oxide-based sintered body according to any one of claims 1 to 5. A thin film obtained by sputtering a sputtering target comprising the zinc oxide-based sintered body according to claim 6. The thin film according to claim 7, wherein the thermal permeability of the film is 1600 (J / sec ^0.5 m ² K) or more.