JP5585046B2 - Composite oxide sintered body, target and oxide transparent conductive film - Google Patents

Description

  The present invention relates to a composite oxide sintered body mainly composed of zinc oxide, a sputtering target comprising the same, and an oxide transparent conductive film obtained using the same.

  Oxide transparent conductive film has high transmittance and high conductivity in the visible light region, is used for electrodes of various light receiving elements such as liquid crystal display elements and solar cells, and is also a heat ray for automobiles and building materials. It is widely used in reflective heating elements for anti-fogging, such as reflective films and antistatic films, and frozen showcases. As one of such oxide transparent conductive films, a zinc oxide film obtained by adding an element such as aluminum oxide, gallium oxide, or boron oxide to zinc oxide is used. In particular, a zinc oxide-based film to which aluminum oxide is added is excellent in light transmittance in the infrared region, and thus is suitably used in applications that place importance on light transmittance, such as solar cells.

  As a method for forming such a transparent oxide conductive film, a sputtering method using a sputtering target is often adopted because it can be formed in a large film with a uniform film thickness. However, this sputtering method has problems such as a decrease in operating rate of the sputtering apparatus due to an abnormal discharge phenomenon during sputtering and a decrease in product yield due to the influence of generated particles.

As a means for suppressing the abnormal discharge phenomenon that occurs during sputtering, for example, Patent Document 1 was selected from the group consisting of 3 to 7 atomic% Al, B, Ga, In, Ge, Si, Sn, and Ti. A ZnO-based sintered body containing 0.3 to 3 atomic% of one or more third elements is disclosed. Patent Document 2 discloses (1) B, In, Al, Ga, Ge, Sn, Si, and A ZnO phase in which at least one selected from the group consisting of Ti is dissolved in an amount of 0.2 to 14 atomic% is a main constituent phase of the structure, (2) the sintered density is 4.5 g / cm ³ or more, (3 A ZnO-based sintered body having a volume resistivity of 1 kΩcm or less and (4) an average crystal grain size of 2 to 20 μm is disclosed. Patent Document 3 discloses a zinc oxide sintered body containing ZnO with at least one additive element selected from the group consisting of Al, Ga, In, Ti, Si, Ge, and Sn. Each of the precipitates including a composite oxide phase and a plurality of pores formed around the precipitates, and the ratio of the precipitates having an equivalent circle diameter of 3 μm or more in the precipitates is 20% or less. In addition, a zinc oxide sintered body is disclosed in which the ratio of holes having an equivalent circle diameter of 3 μm or more among the holes is 50% or less. Patent Document 4 obtains a target capable of forming a film having environmental resistance that can withstand practical use by containing zinc oxide as a main component, including both elements of Ti and Ga, and having a specific composition. It is disclosed that it is possible.

  However, control of additive element composition of Patent Document 1, additive element composition of Patent Document 2, constituent phase in sintered body, sintering density, volume resistivity, control of average crystal grain size, additive element composition of Patent Document 3 In addition, the occurrence of abnormal discharge phenomenon during sputtering cannot be completely avoided by simply controlling the constituent phases in the sintered body and its particle size and pore size, resulting in a decrease in yield due to scattered particles. For this reason, there is a problem that a reduction in productivity is unavoidable, and further suppression of abnormal discharge phenomenon is required. Further, it is desired that the environmental resistance (durability) of a film formed from a zinc oxide target having a specific composition containing both elements of Ti and Ga disclosed in Patent Document 4 is further improved.

  On the other hand, as a thin film containing such an element, Patent Document 5 discloses a zinc oxide-based transparent conductive film containing aluminum and titanium. However, it is based on the chip-on film formation method using the DC magnetron sputtering method, and a part of the elements constituting the thin film is made into a chip shape and placed on the target for sputtering, so the thin film is inferior in homogeneity. Etc. have occurred.

  Furthermore, in order to improve the light transmittance in the infrared region, a zinc oxide film in which the amount of aluminum oxide added is reduced or a zinc oxide film that does not contain aluminum oxide as an additive increases the light transmittance in the infrared region. Although it is known to be very excellent, the durability was poor.

Japanese Patent Laid-Open No. 11-236219 JP-A-11-322332 JP 2008-063214 A Japanese Patent No. 429581 Japanese Patent Laid-Open No. 9-045140

  An object of this invention is to provide the sputtering target which can fully suppress generation | occurrence | production of an abnormal discharge phenomenon, and the manufacturing method of the film | membrane using such a sputtering target. Moreover, it aims at providing the complex oxide sintered compact which can be used as such a sputtering target.

  In view of such a background, as a result of intensive studies, the present inventors have used a sputtering target as a method for forming a transparent oxide conductive film in that a film can be formed with a uniform film thickness over a large area. In the sputtering method, by using a complex oxide sintered body having a specific composition and structure as a sputtering target, the generation of abnormal discharge phenomenon during film formation by sputtering is controlled to suppress the decrease in yield due to particles. A composite oxide sintered body capable of obtaining a film having excellent light transmittance and durability in a region, a sputtering target, and an oxide transparent conductive film obtained by using the same were obtained. It came to be completed.

That is, the present invention is a composite oxide sintered body mainly composed of zinc, element M (M is aluminum and / or gallium), titanium and oxygen, and the atomic ratio of the elements constituting the sintered body is:
(M + Ti) / (Zn + M + Ti) = 0.004 to 0.06
M / (Zn + M + Ti) = 0.002 to 0.058
Ti / (Zn + M + Ti) = 0.002 to 0.058
The sintered body mainly contains zinc oxide and has a hexagonal wurtzite structure having an average particle diameter of 20 μm or less, and ZnTiO ₃ containing element M and titanium and having an average particle diameter of 5 μm or less Particles having a type-like structure and / or a Zn ₂ Ti ₃ O ₈ type-like structure,
A composite oxide sintered body characterized by comprising:

  Moreover, this invention consists of the above-mentioned complex oxide sintered compact, It is a sputtering target characterized by the above-mentioned.

  Furthermore, this invention is a manufacturing method of an oxide transparent conductive film characterized by using the above-mentioned sputtering target.

Further, in the present invention, an oxide transparent conductive film mainly composed of zinc, element M (M is aluminum and / or gallium), titanium, and oxygen has an atomic ratio of the elements constituting the film,
(M + Ti) / (Zn + M + Ti) = 0.004 to 0.06
M / (Zn + M + Ti) = 0.002 to 0.058
Ti / (Zn + M + Ti) = 0.002 to 0.058
And a diffraction peak detected in the range of 2Θ = 30-40 ° of an X-ray diffraction pattern using Cu as a radiation source is attributed to a hexagonal wurtzite structure (100) plane, (002) plane And a diffraction peak of at least one of the (101) planes, the oxide transparent conductive film. Hereinafter, the present invention will be described in detail.

(Composite oxide sintered body)
The atomic ratio of the elements of the composite oxide sintered body of the present invention is as described above, but by setting it within this range, abnormal discharge during sputtering can be reduced. In particular, (M + Ti) / (Zn + M + Ti) is preferably 0.005 to 0.055, and more preferably 0.01 to 0.05. M / (Zn + M + Ti) is preferably 0.003 to 0.04. Further, Ti / (Zn + M + Ti) is preferably 0.003 to 0.04.

  In the present invention, inevitable mixing of trace amounts of impurities does not matter.

  In addition, the abnormal discharge during sputtering can be reduced by setting the average particle size of the particles that mainly comprise zinc oxide and have a hexagonal wurtzite structure constituting the composite oxide sintered body of the present invention to 20 μm or less. It becomes possible to suppress damage to the target during sputtering. The average particle size is preferably 10 μm or less. The lower limit is usually 0.001 μm. In order to obtain a composite oxide sintered body having an average particle size of less than 0.001 μm, for example, a raw material powder having an average primary particle size of less than 0.001 μm is used. When such a raw material powder is used, it becomes very difficult to mold, and the production efficiency tends to decrease. Here, the particle mainly containing zinc oxide and having a hexagonal wurtzite structure is a substance showing a diffraction pattern attributed to the hexagonal wurtzite structure of zinc oxide in an X-ray diffraction test.

On the other hand, the average particle size of the particles containing the element M and titanium and having a ZnTiO ₃ type-like structure and / or Zn ₂ Ti ₃ O ₈ type-like structure is 5 μm or less. Thereby, it becomes possible to suppress abnormal discharge during sputtering. When the average particle size is 3 μm or less, abnormal discharge during sputtering is further suppressed, which is more preferable. The lower limit is usually 0.001 μm. In order to obtain a composite oxide sintered body having an average particle size of less than 0.001 μm, for example, a raw material powder having an average primary particle size of less than 0.001 μm is used. When such a raw material powder is used, it becomes very difficult to mold, and the production efficiency tends to decrease.
Here, the particles containing the element M and titanium and having a ZnTiO ₃ type-like structure and / or a Zn ₂ Ti ₃ O ₈ type-like structure are ZnTiO ₃ type-like structures and / or Zn ₂ Ti _{3 in} an X-ray diffraction test. It is a substance showing a diffraction pattern attributed to an O ₈ type similar structure.

In addition, the measuring method of the average particle diameter of the particle | grains in complex oxide in this invention is performed as follows. That is, after cutting the composite oxide sintered body of the present invention into an appropriate size, the observation surface is polished, and then chemical etching is performed with a dilute acetic acid solution to clarify the grain boundaries. While taking this sample using an X-ray microanalyzer (EPMA), scanning electron microscope / energy dispersive X-ray analysis (SEM / EDS), X-ray diffraction (XRD), etc., an observation photograph of the polished surface of the sintered body is taken. Check the composition of each particle. The average particle diameters of the particles having a hexagonal wurtzite structure and the ZnTiO ₃ type similar structure and / or the Zn ₂ Ti ₃ O ₈ type similar structure are all required to obtain a long diameter of 500 or more of the particles in the observed photograph. The arithmetic average was taken as the average particle size.

Particles having ZnTiO ₃ type similar structure and / or Zn ₂ Ti ₃ O ₈ type similar structure containing element M and titanium, particles having ZnTiO ₃ type similar structure and particles having Zn ₂ Ti ₃ O ₈ type similar structure Although the ratio of is not particularly limited, it is preferable that particles having at least a ZnTiO ₃ type similar structure exist. Thereby, it is possible to further suppress abnormal discharge during sputtering. Further, when the X-ray diffraction intensities of the main peak (311) plane of the particles having a ZnTiO ₃ type-like structure and the particles having a Zn ₂ Ti ₃ O ₈ type-like structure are respectively A _x and A _y ,
_{A x / (A x + A} y) = 0.05~1
Is even more preferable. Thereby, it is possible to further suppress abnormal discharge during sputtering.

Here, the presence of particles having a ZnTiO ₃ type-like structure and particles having a Zn ₂ Ti ₃ O ₈ type-like structure can be confirmed as follows. That is, a particle having a ZnTiO ₃ type similar structure is a diffraction peak detected in the range of 2Θ = 30-40 ° of XRD using Cu as a radiation source, PDF (Powder of International Center for Diffraction Data). (Diffraction File) # 00-039-0190 (RDB) ZnTiO ₃ peak pattern or similar peak pattern (shifted peak pattern) (210) plane, (211) plane, (220) plane, (300) plane , (310) plane, (311) plane, and (320) plane can be indexed. On the other hand, a particle having a Zn ₂ Ti ₃ O ₈ type similar structure is a peak pattern of Zn ₂ Ti ₃ O ₈ of PDF # 00-038-0500 of ICDD or a peak pattern similar to it (shifted peak pattern) ( 220) plane, (311) plane, and (222) plane can be indexed.

Also, since the main peak (311) plane of the ZnTiO ₃ type similar structure and the main peak (311) plane of the Zn ₂ Ti ₃ O ₈ type similar structure are diffracted at very close angles and are difficult to confirm individually, Using the peak of the (210) plane of a ZnTiO ₃ type similar structure that is easy to confirm and its relative intensity in ICDD, A _x and A _y are determined as follows. That is, the sum of the diffraction intensities of the main peak (311) planes of the particles having a ZnTiO ₃ type-like structure and the particles having a Zn ₂ Ti ₃ O ₈ type-like structure is I _{(x + y)} , and the ZnTiO ₃ type-like structure (210) If the diffraction intensity of the surface is I _{x (210)} , it can be calculated by the following equation.
A _x = I _{x (210)} × (100/45)
_{A y = I (x + y} ) -A x
The particles having a Zn ₂ Ti ₃ O ₈ type similar structure may contain particles having a similar structure with a Zn ₂ TiO ₄ type.

  The composite oxide sintered body of the present invention preferably has no element M oxide particles and no titanium oxide particles. Thereby, it is possible to further suppress abnormal discharge during sputtering.

  Here, the oxide of the element M refers to aluminum oxide and / or gallium oxide. Moreover, the fact that the oxide particles and titanium oxide particles of the element M are not included means that a diffraction pattern attributed to the oxide particles and titanium oxide particles of the element M is not confirmed by XRD.

  The element M is aluminum and / or gallium, but it is preferable that aluminum is present at least in the sintered body of the present invention. The reason for this is that aluminum has good handleability and inexpensive raw materials, has no problem in productivity, and has a light transmittance and durability in the infrared region of the film obtained when the sintered body is used as a target. This is because the performance can be further improved.

In particular, the atomic ratio of aluminum to gallium is
Al / (Al + Ga) = 0.005-1
It is more preferable that Thereby, it becomes possible to further improve the light transmittance and durability of the film obtained when the sintered body is used as a target.

  The relative density of the composite oxide sintered body of the present invention is preferably 80% or more. By using such a relative density, a film obtained when the sintered body is used as a target exhibits a high light transmittance in the infrared region, and an oxide transparent conductive film excellent in durability is obtained. In addition, the abnormal discharge phenomenon during sputtering can be suppressed, and stable film formation can be achieved without causing damage to the target during sputtering.

The relative density of the composite oxide sintered body of the present invention is calculated as follows. That is, Zn, Al, Ga, and Ti in the composite oxide sintered body are converted into ZnO, Al ₂ O ₃ , Ga ₂ O _3, and TiO ₂ , respectively, and the weight ratio is obtained. The weight ratios are a (%), b (%), c (%), and d (%), respectively. Next, each of the true density ^{_{ZnO: 5.68g / cm 3, Al}} 2 O 3: 3.99g / cm 3, Ga 2 O 3: 5.88g / cm 3, TiO 2: a 4.2 g / cm ³ The theoretical density A (g / cm ³ ) is calculated as follows.
A = (a + b + c + d) / ((a / 5.68) + (b / 3.99) + (c / 5.88) + (d / 4.2))
The sintered density B (g / cm ³ ) of the composite oxide sintered body is measured by Archimedes method in accordance with JIS-R1634-1998.

The relative density (%) is obtained by the following equation as a relative value of the sintered density B (g / cm ³ ) with respect to the theoretical density A (g / cm ³ ) obtained mathematically.
Relative density (%) = (B / A) × 100
Next, a method for producing the composite oxide sintered body of the present invention will be described. The method for producing a composite oxide sintered body according to the present invention includes (1) a step of adjusting a molding powder by mixing a zinc compound powder and other compound powder so as to have a predetermined atomic ratio, (2) A step of forming the molding powder to produce a molded body, and (3) a step of firing the molded body to produce a sintered body.

(1) Powder adjustment process The raw material powder of each element is not particularly limited. For example, metal oxide powder, metal hydroxide powder, metal salt powder such as chloride, nitrate, carbonate, metal alkoxide, etc. Although it is possible to use, metal oxide powder is preferable in consideration of handling properties. In the present invention, when a powder other than the metal oxide powder is used, the same effect can be obtained even if the powder is subjected to a heat treatment in an oxidizing atmosphere such as the air in advance and used as the metal oxide powder. Since operations such as treatment are involved in the process and become complicated, it is preferable to use a metal oxide powder as the raw material powder.

  Hereinafter, the case where metal oxide powder is used as the raw material powder will be mainly described. The finer the particle size of the metal oxide powder of the raw material powder, the better the homogeneity and sinterability of the mixed state. Therefore, normally, a powder having a primary particle diameter of 10 μm or less is preferably used, and a powder having a particle diameter of 1 μm or less is particularly preferably used. As the powder of elements other than zinc, it is preferable to use an oxide powder having a primary particle size smaller than the primary particle size of the zinc oxide powder. If the primary particle diameter of the zinc oxide powder is smaller or equivalent, the homogeneity of the mixed state may be inferior.

  Regarding the average particle size, it is preferable that the average particle size of the zinc oxide powder is larger than the average particle size of the metal oxide powder other than zinc. Thereby, raw material powder can be mixed homogeneously and the complex oxide sintered compact of this invention which consists of particle | grains which have a fine average particle diameter can be obtained.

Further, the BET specific surface area of the zinc oxide powder and the metal oxide powder other than zinc is preferably 3 to ²⁰ m ² / g in view of handling properties, thereby obtaining the composite oxide sintered body of the present invention. Becomes easy. If BET value is less powder than ^3m 2 / g, BET value by performing the pulverization treatment is preferably used after a powder of 3 to 20 m ² / g. It is also possible to use a powder having a BET value larger than 20 m ² / g. However, since the powder becomes bulky, it is preferable to perform a powder compaction process or the like in advance in order to improve handleability.

The specific surface area diameters determined from the BET specific surface _{areas of} the zinc oxide powder and metal oxide powders other than zinc (that is, oxide powders of aluminum, gallium, and titanium) are D _bz , D _ba , D _bg , and D _bt , respectively. The values of D _sz / D _bz , D _sa / D _ba , D _sg / D _bg , and D _st / D _bt when the average particle diameter of each powder is D _sz , D _sa , D _sg , D _st It is preferable that each is 1 or more and less than 50. Due to such powder characteristics, the composite oxide sintered body of the present invention can be suitably obtained. Here, the specific surface area diameter can be obtained by the following equation assuming that the primary particles of each powder are spherical. In the formula, S represents a BET specific surface area (unit: m ² / g).
D _bz = 6 / (S × 5.68)
D _ba = 6 / (S × 3.99)
D _bg = 6 / (S × 5.88)
D _bt = 6 / (S × 4.2)
In addition, the average particle diameter of each powder was measured with a liquid module in distilled water using COULTER LS130 (manufactured by COULTER ELECTRONICS). Measurements are volume based.

  The mixing method of these powders is not particularly limited, but dry, wet media agitation type mills using media such as zirconia, alumina, nylon resin, and balls and beads, medialess container rotary mixing, mechanical agitation types Examples of the mixing method include mixing. Specific examples include a ball mill, a bead mill, an attritor, a vibration mill, a planetary mill, a jet mill, a V-type mixer, a paddle mixer, and a twin-shaft planetary agitation mixer.

  In addition, the pulverization is performed simultaneously with the mixing of the powder. The finer the particle size of the powder after the pulverization is, the more preferable, especially when the wet method is used. Since it can do, it is much more preferable. At this time, when a ball mill, a bead mill, an attritor, a vibration mill, a planetary mill, a jet mill or the like is performed by a wet method, the pulverized slurry needs to be dried. This drying method is not particularly limited, and examples thereof include filtration drying, fluidized bed drying, and spray drying.

  In addition, when mixing powder other than an oxide, it is preferable to calcine at 500-1200 degreeC after mixing, and to grind and use the obtained calcined powder. Thereby, breakage, such as a crack at the time of shaping | molding and baking at the next shaping | molding process, a chip | tip, can be suppressed further.

  The purity of each raw material powder is usually 99% or higher, preferably 99.9% or higher, more preferably 99.99% or higher. This is because if the purity is low, impurities may adversely affect the characteristics of the transparent conductive film formed by the sputtering target using the composite oxide sintered body of the present invention.

Since the blending of these raw materials is reflected in the atomic ratio of the elements constituting the obtained composite oxide sintered body, the atomic ratio of zinc, element M, and titanium is
(M + Ti) / (Zn + M + Ti) = 0.004 to 0.06
M / (Zn + M + Ti) = 0.002 to 0.058
Ti / (Zn + M + Ti) = 0.002 to 0.058
The raw materials are mixed so that

  The mixed powder thus obtained (or calcined mixed powder if calcined) is preferably granulated before molding. Thereby, it becomes possible to improve the fluidity | liquidity at the time of shaping | molding, and it is excellent in productivity. Although the granulation method is not particularly limited, spray drying granulation, tumbling granulation and the like can be exemplified, and it is usually used as a granulated powder having an average particle size of several μm to 1000 μm.

(2) Molding step The molding method is not particularly limited as long as the metal oxide mixed powder (or calcined mixed powder if calcined) can be molded into a target shape. Examples thereof include a press molding method, a cast molding method, and an injection molding method. The molding pressure is not particularly limited as long as a molded body that does not generate cracks and can be handled is obtained, but at a relatively high molding pressure, for example, in the case of press molding, 500 kg / cm ^{2 to} 3.0 ton. When molded at / cm ² , the composite oxide sintered body of the present invention is easily obtained without the element M oxide particles and titanium oxide particles, and with a relative density of 80% or more. Further, it is preferable to increase the molding density as much as possible. Therefore, it is also possible to use a method such as cold isostatic pressing (CIP) molding. In the molding treatment, molding aids such as polyvinyl alcohol, acrylic polymer, methyl cellulose, waxes, oleic acid and the like may be used.

(3) Firing step Next, the obtained molded body is fired at 600 to 1500 ° C. By firing in this temperature range, it is possible to obtain a composite oxide sintered body composed of particles having a fine average particle diameter. In particular, the firing temperature is more preferably in the range of 800 to 1400 ° C. from the viewpoint that the volatilization disappearance unique to the zinc oxide-based composite oxide is suppressed and the sintered density can be increased. Further, when the firing temperature is 800 to 1400 ° C., it is easy to obtain those in which the oxide particles of element M and titanium oxide particles are not present, and it is easy to obtain those having a relative density of 80% or more.

  When a molding aid is used during molding, it is preferable to add a degreasing step before firing from the viewpoint of preventing breakage such as cracks during heating.

  According to the present invention, by controlling the average particle size of the particles constituting the composite oxide sintered body as described above, a high sintered density can be obtained, and an abnormal discharge phenomenon during sputtering when used as a target. Can be remarkably suppressed.

  The firing time is not particularly limited, but is usually 1 to 48 hours, although depending on the balance with the firing temperature. Preferably it is 3 to 24 hours. This is to ensure the homogeneity in the composite oxide sintered body of the present invention, and it is possible to ensure the homogeneity even if it is maintained for a longer time than 24 hours, but the influence on the productivity is considered. Then 24 hours or less is sufficient. Further, in order to obtain a composite oxide sintered body composed of particles having a fine average particle diameter, it is particularly preferably 3 to 10 hours.

  The rate of temperature increase is not particularly limited, but is more preferably 50 ° C./h or less in the temperature range of 800 ° C. or higher. This is to ensure homogeneity in the composite oxide sintered body of the present invention.

  Although the firing atmosphere is not particularly limited, for example, the atmosphere, oxygen, inert gas atmosphere, and the like are appropriately selected, but an atmosphere having a lower oxygen concentration than the atmosphere is more preferable. This is because oxygen defects are easily introduced into the composite oxide sintered body of the present invention, and therefore, the resistivity of the composite oxide sintered body is reduced and abnormal discharge can be further reduced. is there. Moreover, the pressure at the time of baking is not specifically limited, In addition to a normal pressure, baking in a pressurization and pressure reduction state is also possible. Firing by a hot isostatic pressure (HIP) method is also possible.

  In addition, (2) shaping | molding process and (3) baking process can also be performed simultaneously. That is, it can be produced by a hot press method in which the powder adjusted in the powder adjustment step is filled in a mold and fired, or a method in which the powder is melted and sprayed at a high temperature to obtain a predetermined shape. .

(Sputtering target)
The sputtering target of the present invention is characterized by comprising the above complex oxide sintered body. An oxide transparent conductive film formed by sputtering using such a sputtering target has low resistivity, excellent light transmittance not only in the visible light region but also in the infrared region, and also excellent durability. Further, such a sputtering target has excellent discharge characteristics during film formation, and abnormal film formation is suppressed and stable film formation is possible.

  In the present invention, the composite oxide sintered body may be used as it is as a sputtering target, or the composite oxide sintered body may be processed into a predetermined shape and used as a sputtering target.

  In the sputtering target, the surface roughness of the sputtering surface is preferably 3 μm or less, more preferably 2 μm or less, in terms of centerline average roughness (Ra). As a result, the number of abnormal discharges during film formation can be further suppressed, and stable film formation is possible. The centerline average roughness can be adjusted by a method of machining the sputtering surface of the composite oxide sintered body with a grindstone or the like having a different count, a method of spraying with a sandblast, or the like. The center line average roughness can be determined by, for example, evaluating the measurement surface with a surface texture measuring device.

(Oxide transparent conductive film)
The oxide transparent conductive film of the present invention can be produced, for example, by sputtering using the above sputtering target.

  The oxide transparent conductive film of the present invention is such that the atomic ratio of the elements constituting the film has a specific value as described above, and by setting this range, the resistivity is low, not only in the visible light range. Even in the infrared region, the film has excellent light transmittance and excellent durability.

  In particular, (M + Ti) / (Zn + M + Ti) is preferably 0.005 to 0.055, and more preferably 0.01 to 0.05. M / (Zn + M + Ti) is preferably 0.003 to 0.04. Further, Ti / (Zn + M + Ti) is preferably 0.003 to 0.04.

  In addition, in the oxide transparent conductive film of this invention, inevitable mixing of a trace amount of impurities does not ask | require.

  Further, in the transparent oxide conductive film of the present invention, the diffraction peak detected in the XRD range of 2Θ = 30-40 ° with Cu as the radiation source is attributed to the hexagonal wurtzite structure (100) plane. , A diffraction peak of at least one of the (002) plane and the (101) plane, which has a low resistivity, excellent light transmittance not only in the visible light region but also in the infrared region, and durability. Excellent film.

  In the transparent oxide conductive film of the present invention, the diffraction peak of element M oxide phase and titanium oxide phase does not exist in the diffraction peak detected in the range of 2Θ = 30-40 ° of XRD using Cu as a radiation source. It is preferable. Such a film is obtained by sputtering using the target of the present invention. By setting it as such a film | membrane, it becomes a film | membrane which is low in resistivity, is excellent in light transmittance not only in the visible light region but also in the infrared region, and is excellent in durability.

The oxide transparent conductive film of the present invention has a (100) plane attributed to a hexagonal wurtzite structure at a diffraction peak detected in the range of 2Θ = 30-40 ° of XRD using Cu as a radiation source, When the integrated intensities of diffraction peaks on the (002) plane and (101) plane are I ₍₁₀₀₎ , I ₍₀₀₂₎ and I ₍₁₀₁₎ , respectively.
I ₍₀₀₂₎ / (I ₍₁₀₀₎ + I ₍₀₀₂₎ + I ₍₁₀₁₎ ) ≧ 0.9
It is more preferable that Below this range, resistance increases and durability may deteriorate, which is not preferable. The upper limit of this range is 1, indicating that only the diffraction peak of the (002) plane is observed in X-ray. Such a film has an atomic ratio of elements constituting the film of (M + Ti) / (Zn + M + Ti) = 0.005 to 0.055.
Specifically, it can be obtained by sputtering using a target made of a sintered body having such an atomic ratio of elements.

  As a sputtering method for producing the oxide transparent conductive film of the present invention, a DC sputtering method, an RF sputtering method, an AC sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, an ion beam sputtering method, or the like is appropriately selected. Among these, the DC magnetron sputtering method and the RF magnetron sputtering method are preferable because they can be uniformly formed in a large area and can be formed at high speed.

  Although the temperature of the base material used at the time of sputtering is not specifically limited, it is influenced by the heat resistance of the base material. For example, when alkali-free glass is used as a base material, it is usually preferably 250 ° C. or lower, and when a resin film is used as a base material, 150 ° C. or lower is usually preferable. Of course, when using a substrate having excellent heat resistance such as quartz, ceramics, metal, etc., it is possible to form a film at a temperature higher than that.

  As the atmospheric gas during sputtering, an inert gas, for example, an argon gas is usually used. If necessary, oxygen gas, nitrogen gas, hydrogen gas or the like may be used.

The complex oxide sintered body of the present invention can be used as a sputtering target. And the oxide transparent conductive film of this invention can be manufactured, suppressing the abnormal discharge during sputtering by sputtering using the target. The transparent oxide conductive film of the present invention is a film that is excellent not only in the visible light region but also in the infrared region and has excellent durability. For this reason, for example, by using it for a solar cell, solar energy in the infrared region, which has been impossible in the past, can be used with high efficiency, and a solar cell with high photoelectric conversion efficiency can be provided. it can. The solar cell referred to here is a silicon solar cell using single crystal silicon, polycrystalline silicon, amorphous silicon, a compound solar cell such as CuInSe ₂ , Cu (In, Ga) Se ₂ , GaAs, CdTe, Furthermore, the solar cell using oxide transparent conductive films, such as a dye-sensitized solar cell, can be illustrated.

  The present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited thereto.

The physical properties of the raw material powder used are as follows.
Zinc oxide powder: purity 99.8%, BET specific surface area 4 m ² / g, average particle diameter D _sz 2.4 μm.
Aluminum oxide powder: purity 99.99%, BET specific surface area 14 m ² / g, average particle diameter D _sa 1.6 μm.
Gallium oxide powder: purity 99.99%, BET specific surface area 8 m ² / g, average particle diameter D _sg 1.8 μm.
Titanium oxide powder: purity 99.9%, BET specific surface area 6.5 m ² / g, average particle diameter D _st 2.2 μm.

The raw material powder was evaluated as follows.
(BET specific surface area)
MONOSORB (manufactured by QUANTACHROME, USA) was used, and measurement was performed by the BET one-point method.
(Average particle size of powder)
Using COULTER LS130 (manufactured by COULTER ELECTRONICS), it was measured with distilled water in a liquid module. Measurements are volume based.

Example 1
After the zinc oxide powder, aluminum oxide powder and titanium oxide powder are mixed, pulverized and dried in a wet bead mill so that the ratio of the number of atoms of zinc, aluminum and titanium is the value described in the table, a mold having a diameter of 150 mm And uniaxially molded at 300 kg / cm ² and then CIP molded at 3.0 ton / cm ² . The obtained molded body was fired under the conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1100 ° C., a holding time of 3 hours and in nitrogen to obtain a composite oxide sintered body.
(Example 2)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the values described in the table, and the firing temperature was 1200 ° C.
(Example 3)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table, and the firing temperature was 1400 ° C.

Example 4
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table, and the firing temperature was 1300 ° C.
(Example 5)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the values described in the table, and the firing temperature was 1200 ° C.
(Example 6)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the values described in the table, and the firing temperature was 1300 ° C. in the air. .
(Example 7)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table, and the firing temperature was 1400 ° C.

(Examples 8 to 10)
Zinc oxide powder, aluminum oxide powder, gallium oxide powder and titanium oxide powder are mixed in a wet bead mill, pulverized and dried so that the ratio of the number of atoms of zinc, aluminum, gallium and titanium is the value shown in the table. A mold having a diameter of 150 mm was filled, uniaxially molded at 300 kg / cm ² , and then CIP molded at 3.0 ton / cm ² . The obtained molded body was fired under the conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1200 ° C., a holding time of 3 hours, and nitrogen to obtain a composite oxide sintered body.

(Example 11)
A zinc oxide powder, a gallium oxide powder and a titanium oxide powder are mixed, pulverized and dried by a wet bead mill so that the ratio of the number of atoms of zinc, gallium and titanium is the value shown in the table, and then a mold having a diameter of 150 mm And uniaxially molded at 300 kg / cm ² and then CIP molded at 3.0 ton / cm ² . The obtained molded body was fired under the conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1200 ° C., a holding time of 3 hours, and nitrogen to obtain a composite oxide sintered body.
(Example 12)
A composite oxide sintered body was obtained in the same manner as in Example 11 except that the ratio of the number of atoms of zinc, gallium, and titanium was the values described in the table, and the firing temperature was 1300 ° C.
(Example 13)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table and the firing temperature was 1200 ° C.

(Example 14)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the values described in the table, and the firing temperature was 1200 ° C. and in the air. .
(Examples 15 and 16)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table and the firing temperature was 1200 ° C.
(Example 17)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was set to the values shown in the table, and the firing temperature was 1000 ° C.
(Example 18)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the value described in the table.

(Comparative Example 1)
The zinc oxide powder was mixed and pulverized with a wet bead mill, dried, filled into a 150 mm diameter mold, uniaxially molded at 300 kg / cm ² , and then CIP molded at 3.0 ton / cm ² . The obtained molded body was fired under the conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1100 ° C., a holding time of 3 hours and in nitrogen to obtain a composite oxide sintered body.
(Comparative Examples 2 to 4)
Zinc oxide powder and aluminum oxide powder were mixed, pulverized and dried in a wet bead mill so that the ratio of the number of atoms of zinc and aluminum would be the value shown in the table, and then filled into a 150 mm diameter mold, 300 kg / Uniaxial molding was performed at cm ² , and then CIP molding was performed at 3.0 ton / cm ² . The obtained molded body was fired under the conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1300 ° C., a holding time of 3 hours, and nitrogen to obtain a composite oxide sintered body.

(Comparative Example 5)
The zinc oxide powder and the titanium oxide powder were mixed, pulverized and dried by a wet bead mill so that the ratio of the number of atoms of zinc and titanium was as shown in the table, and then filled in a mold having a diameter of 150 mm. Uniaxial molding was performed at cm ² , and then CIP molding was performed at 3.0 ton / cm ² . The obtained molded body was fired under conditions of a temperature rising rate of 50 ° C./h, a temperature falling rate of 100 ° C./h, a firing temperature of 1400 ° C., a holding time of 3 hours in nitrogen, and a composite oxide sintered body was obtained.
(Comparative Examples 6-7)
A composite oxide sintered body was obtained in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was the values described in the table, and the firing temperature was 1400 ° C.
(Comparative Example 8)
A composite oxide sintered body was prepared in the same manner as in Example 1 except that the ratio of the number of atoms of zinc, aluminum, and titanium was as shown in the table, and the firing temperature was 1500 ° C. and the holding time was 8 hours. Obtained.

Evaluation of Composite Oxide Sintered Body Properties of the obtained composite oxide sintered body were evaluated as follows.
(Relative density of composite oxide sintered body)
The relative density of the composite oxide sintered body was determined as described above.
(Average particle size of composite oxide sintered body)
The average particle diameter of particles having a particle and ZnTiO ₃ type similar structure having a hexagonal wurtzite structure of the composite oxide sintered body and / or Zn ₂ Ti ₃ O ₈ type similar structure, as described above Asked. However, an observation photograph was obtained using a scanning electron microscope, and the average particle diameter was determined from 500 particles.
(X-ray diffraction test)
The measurement conditions are as follows.
-X-ray source: CuKα
・ Power: 40kV, 40mA
-Scanning speed: 1 ° / min.

Preparation of target The obtained complex oxide sintered body is processed into a 4 inch φ size, and the surface to be the sputtering surface of the target is a center line average by using a surface grinder and a diamond grindstone, and changing the number of the grindstone. The roughness was adjusted to produce a target.
(Surface roughness of the sputtering surface of the target)
The sputtering surface of the sputtering target was used as the measurement surface, and evaluation was performed with a surface texture measuring device (SV-3100, manufactured by Mitutoyo Corporation) to determine the centerline average roughness.

(Evaluation of target discharge characteristics)
The number of abnormal discharges that occurred per hour under the following sputtering conditions was calculated.
Sputtering conditions and equipment: DC magnetron sputtering equipment (manufactured by ULVAC)
Magnetic field strength: 1000 Gauss (directly above the target, horizontal component)
・ Substrate temperature: Room temperature (about 25 ℃)
・ Achieved vacuum: 5 × 10 ⁻⁵ Pa
・ Sputtering gas: Argon ・ Sputtering gas pressure: 0.5 Pa
・ DC power: 300W
Sputtering time: 30 hours.

Production of Transparent Oxide Conductive Film Using the produced sputtering target, a film was formed by the DC magnetron sputtering method under the following conditions to obtain an oxide transparent conductive film.
Sputtering conditions and equipment: DC magnetron sputtering equipment (manufactured by ULVAC)
Magnetic field strength: 1000 Gauss (directly above the target, horizontal component)
-Substrate temperature: 200 ° C
・ Achieved vacuum: 5 × 10 ⁻⁵ Pa
・ Sputtering gas: Argon ・ Sputtering gas pressure: 0.5 Pa
・ DC power: 300W
-Film thickness: 1000 nm
-Substrate used: Alkali-free glass (Corning # 1737 glass), thickness 0.7 mm.

The properties of the obtained thin film were measured as follows.
(Thin film composition)
Quantification was performed by ICP emission spectroscopy using an ICP emission spectrometer (Seiko Instruments Inc.).
(X-ray diffraction test)
The measurement conditions are as follows.
-X-ray source: CuKα
・ Power: 40kV, 40mA
-Scanning speed: 1 ° / min.

(Thin film transmittance)
The light transmittance including the substrate is measured in the wavelength range of 240 nm to 2600 nm using a spectrophotometer U-4100 (manufactured by Hitachi, Ltd.), and the average value of the transmittance from the wavelength of 400 nm to 800 nm is measured as the transmittance in the visible light range, The average value of the transmittance from a wavelength of 800 nm to 1200 nm was defined as the transmittance in the infrared region.
(Durability of thin film)
The thin film sample was continuously exposed to an environment at a temperature of 85 ° C. and a relative humidity of 85%, and the change in resistivity was observed. At this time, when the resistivity before and after the test was A and B, respectively, the value of (B−A) / A was obtained in% units and used as an index of durability. Usually, this value tends to increase with the test time, and the smaller the value, the better the durability.
(Resistivity of thin film)
The resistivity of the thin film was measured using HL5500 (manufactured by Nippon Bio-Rad Laboratories).

  The results are shown in Tables 1-3.

表中、○は「回折ピーク有」、×は「回折ピーク無」をそれぞれ示す。

In the table, ◯ indicates “with diffraction peak” and × indicates “without diffraction peak”.

Claims (7)

In a composite oxide sintered body mainly composed of zinc, element M (M is aluminum and / or gallium), titanium and oxygen, the atomic ratio of the elements constituting the sintered body is
(M + Ti) / (Zn + M + Ti) = 0.004 to 0.06
M / (Zn + M + Ti) = 0.002 to 0.058
Ti / (Zn + M + Ti) = 0.002 to 0.058
The sintered body is a particle having a hexagonal wurtzite structure having an average particle diameter of 20 μm or less, and a ZnTiO ₃ type similar structure and / or Zn ₂ Ti ₃ O ₈ type having an average particle diameter of 5 μm or less. Particles having a similar structure,
A composite oxide sintered body having a relative density of 80% or more . The composite oxide sintered body according to claim 1, wherein the oxide particles and titanium oxide particles of the element M are not present in the sintered body. Characterized by comprising the composite oxide sintered body according to claim 1 or 2, the sputtering target. The sputtering target according to claim 3 , wherein the center line average roughness Ra of the sputtering surface is 3 μm or less. The manufacturing method of the oxide transparent conductive film characterized by using the sputtering target of Claim 3 or 4 . In an oxide transparent conductive film mainly composed of zinc, element M (M is aluminum and / or gallium), titanium and oxygen, the atomic ratio of the elements constituting the film is
(M + Ti) / (Zn + M + Ti) = 0.004 to 0.06
M / (Zn + M + Ti) = 0.002 to 0.058
Ti / (Zn + M + Ti) = 0.002 to 0.058
And a diffraction peak detected in the range of 2Θ = 30-40 ° of an X-ray diffraction pattern using Cu as a radiation source is attributed to a hexagonal wurtzite structure (100) plane, (002) plane , and (101) Ri diffraction peak der of at least one side of the face, in the diffraction peaks attributed to the hexagonal wurtzite type structure (100) plane, (002) plane, the diffraction peak of the (101) plane When the integrated intensities are I ₍₁₀₀₎ , I ₍₀₀₂₎ and I ₍₁₀₁₎ respectively,
I ₍₀₀₂₎ / (I ₍₁₀₀₎ + I ₍₀₀₂₎ + I ₍₁₀₁₎ ) ≧ 0.9
An oxide transparent conductive film, characterized in that A diffraction peak detected the Cu in the range of 2 [Theta] = 30 to 40 ° in X-ray diffraction pattern of a radiation source, there is no diffraction peak of the oxide phase and titanium oxide phases of the elements M, claim 6 Oxide transparent conductive film.