JP6961925B2 - Oxide sputtering target - Google Patents

Description

The present invention relates to an oxide sputtering target for forming a transparent oxide film as a base material in a laminated reflective electrode film used as an anode of, for example, an organic electroluminescence (EL) display.

The organic EL display has an anode, an organic EL light emitting layer, and a cathode laminated on a substrate, and holes are injected from the anode into the organic EL light emitting layer, and electrons are injected into the organic EL light emitting layer from the cathode, and holes are formed in the organic EL light emitting layer. Visible light is emitted by recombining with electrons. In a top-emission organic EL display that extracts visible light from the cathode side to the outside, not only the visible light emitted directly from the organic EL light emitting layer to the cathode side but also the visible light emitted to the anode side is reflected by the anode. Brightness is improved by taking out on the cathode side. As the anode, a laminated reflective electrode film having a laminated structure in which an ITO film / metal film / ITO film is laminated is generally used. As the metal film, an Ag film made of Ag or an Ag alloy is used.

However, the laminated reflective electrode film composed of the ITO film / Ag film / ITO film has a problem that the reflectance of blue light near the wavelength (432.8 nm) is low. If a laminated reflective electrode film having a low reflectance of blue light is used for the organic EL display, the brightness of blue is lowered. Further, if the input power is increased in order to increase the brightness of blue, the blue light emitting material is liable to deteriorate and the life may be shortened.

Further, in an organic EL display, it is necessary to form the anode in a specific wiring pattern. In a laminated reflective electrode film composed of an ITO film / Ag film / ITO film, the ITO film needs to be an amorphous film in order to perform batch etching with a mixed solution of hydrogen peroxide solution, phosphoric acid, nitric acid, and acetic acid. was there. In order to form an amorphous ITO film, sputtering in an atmosphere containing water vapor or water is required.

On the other hand, a transparent oxide film formed by using an oxide sputtering target containing ZnO as a main component has high light transmittance for a wide range of visible light, and the oxide film and the Ag film are laminated. The reflective electrode film has a higher transmittance of blue light than a laminated reflective electrode film composed of an ITO film / Ag film / ITO film. Further, the oxide sputtering target containing ZnO as a main component can form an oxide film that can be batch-etched with the Ag film by sputtering in a normal atmosphere (mainly Ar gas) that does not contain water vapor or water. Further, since Zn oxide, which is cheaper than In, is used as the main component, the raw material cost is lower than that of ITO.

Oxide sputtering targets containing ZnO as a main component are described in the following documents.
Patent Document 1 discloses a sputtering target made of ZnO in which gallium oxide is doped with 5 to 40 wt%.
Patent Document 2 describes a sputtering target containing 60 to 87 mol% of ZnO and 10 to 25 mol% of Ga ₂ O _3, and further containing at least one oxide selected from _{TiO 2} and SnO _2. It is disclosed.
Patent Document 3 discloses a sputtering target containing ZnO as a main component, containing both Ti and Ga elements, and containing both elements in the range of Ti 1.1 at% or more or Ga 4.5 at% or more. ..

Japanese Unexamined Patent Publication No. 2014-5538 Japanese Unexamined Patent Publication No. 2016-98396 JP-A-2010-70796

The anode used in the top-emission organic EL display has a high reflectance of visible light, enables batch etching, and has a work function so that holes can be efficiently injected into the organic EL light emitting layer. High is desired. A low work function of the anode requires higher power to carry out hole transport. When a high electric power is applied, the life of the organic EL display is shortened and the luminous efficiency is also lowered. However, the oxide film formed by using the conventional oxide sputtering target containing ZnO as a main component may have a low work function for use as an anode of an organic EL display. Further, the oxide film containing ZnO as a main component has a problem that the environmental resistance (resistance to a high temperature and high humidity environment) is lower than that of the ITO film, and the function of protecting the Ag film is insufficient.

The present invention has been made in view of the above-mentioned circumstances, and when laminated with an Ag film made of Ag or an Ag alloy, it has high reflectance and work function, high conductivity, and excellent environmental resistance. Another object of the present invention is to provide an oxide sputtering target capable of stably forming an oxide capable of batch etching with an Ag film.

In order to solve the above problems, the oxide sputtering target of the present invention contains ZnO as a main component, and Ga is 10.0 atomic% or more and 20.0 atomic% or less, and Y is 0. 1 atomic% or more and 10.0 atomic% or less , Ti is 0 . It is characterized by containing an oxide in an amount of 5 atomic% or more and 10.0 atomic% or less and having a relative density of 91.3% or more.

Since the oxide sputtering target of the present invention contains ZnO as a main component, an oxide film capable of batch etching with an Ag film can be formed.
Further, since Ga is contained in an amount of 10.0 atomic% or more and 20.0 atomic% or less, it has high conductivity, excellent environmental resistance, and high adhesion to the Ag film, and when laminated with the Ag film. It is possible to form an oxide film having a high reflectance.
Further, since Y is contained in an amount of 0.1 atomic% or more and 10.0 atomic% or less, an oxide film having a high work function can be formed.

Furthermore , Ti is set to 0 . Since it contains 5 atomic% or more, an oxide film having excellent environmental resistance and alkali resistance can be formed. Since the amount of Ti is 10.0 atomic% or less, the occurrence of abnormal discharge during sputtering can be suppressed, and the oxide film can be stably formed.

Here, in the oxide sputtering target of the present invention, further, with respect to the total amount of metal components, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al. , In, Si, Ge, Pb, Bi and at least one additive element selected from the group consisting of elements of the lanthanoid series, in a total amount of 0.01 atomic% or more and 10.0 atomic% or less. You may.
In this case, an oxide film having further improved environmental resistance and further improved conductivity can be formed.

According to the present invention, when laminated with an Ag film, an oxide film having high reflectance and work function, excellent environmental resistance, and capable of batch etching with the Ag film can be stably formed. It becomes possible to provide an oxide sputtering target.

The oxide sputtering target according to the embodiment of the present invention will be described in detail below.
The oxide sputtering target of the present embodiment is used, for example, when forming a transparent oxide film as a base material in a laminated reflective electrode film used as an anode of an organic EL display.

(First Embodiment)
The oxide sputtering target according to the first embodiment of the present invention is composed of an oxide containing ZnO as a main component. This oxide has Ga of 10.0 atomic% or more and 20.0 atomic% or less, Y of 0.1 atomic% or more and 10.0 atomic% or less, and Sn or Ti of at least one kind with respect to the total amount of metal components. Alternatively, it is contained in an amount of 0.5 atomic% or more and 10.0 atomic% or less in total of the two types, and the balance is Zn and unavoidable impurities. Hereinafter, the reason why the content ratio of the metal component element in the oxide constituting the oxide sputtering target of the present embodiment is defined as described above will be described.

(Ga)
Since Ga is an element that acts as a dopant of ZnO (zinc oxide) by adding an appropriate amount and has an effect of reducing electrical resistance, the conductivity of the oxide sputtering target is improved by adding an appropriate amount of Ga. In addition, it is possible to form a highly conductive oxide film. Further, since Ga is an element having an action effect of improving the wettability with respect to the Ag film, by adding Ga, an oxide film having a high adhesion to the Ag film can be formed. Therefore, the laminated reflective film in which the oxide film and the Ag film are laminated has high reflectance, and even when used in a high temperature and high humidity environment, the invasion of water into the Ag film is suppressed. Environmental resistance is improved. Further, since Ga is an element having an action effect of improving alkali resistance, the addition of Ga deteriorates the masking material used in the etching treatment with respect to the alkali treatment liquid used for peeling off the masking material. It is possible to form an oxide film in which Therefore, the laminated reflective film in which the oxide film and the Ag film are laminated has excellent workability by etching treatment.
Here, if the Ga content is less than 10.0 atomic%, the conductivity of the formed oxide film may decrease. In addition, the film-formed oxide film may have low adhesion to the Ag film and alkali resistance, and the laminated reflective film in which the oxide film and the Ag film are laminated has reduced environmental resistance and alkali resistance. There is a risk. On the other hand, when the Ga content exceeds 20.0 atomic%, the conductivity of the target is rather lowered, which may make DC sputtering difficult. In addition, the electrical resistance of the deposited oxide film increases, which may result in an insulating film.
For this reason, in the present embodiment, the Ga content is set within the range of 10.0 atomic% or more and 20.0 atomic% or less.

(Y)
Since Y has an effect of improving the work function of the oxide film, it is possible to form an oxide film having a high work function by adding an appropriate amount of Y. Further, since Y is an element having an effect of improving the density of the target, the density of the oxide sputtering target containing an appropriate amount of Y becomes high.
Here, if the Y content is less than 0.1 atomic%, it may be difficult to form an oxide film having a high work function. On the other hand, when the Y content exceeds 10.0 atomic%, the electric resistance of the formed oxide film becomes high, and there is a possibility that the film becomes an insulating film.
For this reason, in the present embodiment, the Y content is set within the range of 0.1 atomic% or more and 10.0 atomic% or less.

(At least one or two types of Sn or Ti)
Since Sn and Ti have an action effect of improving the environmental resistance and alkali resistance of the oxide film, an oxide film having high environmental resistance and alkali resistance is formed by adding an appropriate amount of Sn or Ti. It becomes possible.
Here, when the Sn or Ti content is less than 0.5 atomic%, it may be difficult to form an oxide film having improved environmental resistance and alkali resistance. On the other hand, when the Sn or Ti content exceeds 10.0 atomic%, abnormal discharge may easily occur.
For this reason, in the present embodiment, the Sn or Ti content is set within the range of 0.5 atomic% or more and 10.0 atomic% or less in total for at least one type or two types.

(Zn)
Since the oxide sputtering target of the present embodiment contains ZnO as a main component, it has a high dissolution rate in an acid generally used as an etching solution such as a hydrogen peroxide solution, a mixed solution of phosphoric acid, nitric acid, and acetic acid, and Ag. An oxide film that can be batch-etched with the film can be formed.
In the oxide sputtering target of the present embodiment, the Zn content with respect to the total metal component amount is 60 atomic% or more.

(Inevitable impurities)
Inevitable impurities are elements derived from raw materials or inevitably mixed in during the manufacturing process, and refer to elements that do not affect the above-mentioned effects of the invention. In the oxide sputtering target of the present embodiment, the content of unavoidable impurities is generally 100 mass ppm or less in total.

(Manufacturing method of oxide sputtering target)
Next, a method for manufacturing the oxide sputtering target according to the present embodiment will be described.
As raw material powders, gallium oxide (Ga ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), titanium oxide (TIO ₂ ), and tin oxide (SnO ₂ ) powders are prepared. The raw material powder preferably has a purity of 99.9% by mass or more.

Each of the prepared raw material powders is selected and weighed so that the content ratio of the metal element is within the above range. The weighed oxide powder is mixed by a mixing device to obtain a mixed powder. As the mixing device, a mixing device having a crushing function such as a ball mill device is preferable. By using a mixing device having a pulverizing function, the raw material powder can be mixed while being refined, so that a mixed powder having a uniform composition can be obtained. The mixing may be performed wet or dry.

Next, the obtained mixed powder is molded into a desired shape. As a molding method of the molded product, a pressure molding method such as a uniaxial press or a cold hydrostatic press (CIP) can be used.

Next, the molded product is fired and sintered to obtain a sintered body. The firing is preferably performed in an air atmosphere or an oxygen atmosphere. By firing in an air atmosphere or an oxygen atmosphere, the effect of improving the density of the target by Y is likely to be exhibited, atmospheric pressure sintering becomes possible, and productivity is improved. In addition, oxygen deficiency of the oxide is less likely to occur, and a sintered body having a uniform composition and high density can be obtained.

Then, the obtained sintered body is cut or ground to be processed into an oxide sputtering target having a predetermined shape.

(Second embodiment)
The oxide sputtering target of the second embodiment further comprises Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al with respect to the total amount of metal components. , In, Si, Ge, Pb, Bi and at least one additive element selected from the group consisting of elements of the lanthanoid series, in a total amount of 0.01 atomic% or more and 10.0 atomic% or less. That is, in the oxide sputtering target of the second embodiment, Ga is 10.0 atomic% or more and 20.0 atomic% or less, and Y is 0.1 atomic% or more and 10.0 atoms with respect to the total amount of metal components. % Or less, at least one or two types of Sn or Ti in total of 0.5 atomic% or more and 10.0 atomic% or less, and the above additive elements in total of 0.01 atomic% or more and 10.0 atomic% or less. It is contained in an amount, and the balance is Zn and unavoidable impurities. In the oxide sputtering target of the present embodiment, the Zn content with respect to the total metal component amount is 50 atomic% or more.

Additive elements such as Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al, In, Si, Ge, Pb, Bi and lanthanoid series are the oxide film. Since it has an action effect of improving environmental resistance, it is possible to form an oxide film having high environmental resistance by adding an appropriate amount of these elements. Further, the above-mentioned additive element is an element having a valence of trivalent or higher, and acts as a dopant of ZnO to lower the resistance value of the oxide film to form a reflective laminated film with an Ag film. It has the effect of stabilizing the resistance value of the reflective laminated film.
Here, when the content of the additive element is less than 0.01 atomic%, it may be difficult to form an oxide film having improved environmental resistance. On the other hand, when the content of the additive element exceeds 10.0 atomic%, the transparency of visible light of the formed oxide film is lowered, and when it is formed as a laminated film with an Ag film, it is reflected and laminated. The reflectance of visible light on the film may be low.
For this reason, in the present embodiment, the total content of the additive elements is set within the range of 0.01 atomic% or more and 10.0 atomic% or less.

The oxide sputtering target of the present embodiment is obtained by mixing the oxide powder of the additive element with the raw material powders such as the _{Ga 2} O ₃ powder, the Y ₂ O ₃ powder, the TiO ₂ powder, and the SnO _{2 powder described above.} It can be produced by molding the resulting mixed powder into a predetermined shape and then sintering it. The oxide of the additive element is preferably an oxide having a valence of trivalent or higher as the additive element. When the valence of the additive element is trivalent or higher, the effect of ZnO as a dopant can be exhibited.

According to the oxide sputtering target of the present embodiment having the above configuration, since ZnO is the main component, an oxide film capable of batch etching with the Ag film can be formed. Further, since Ga is contained in an amount of 10.0 atomic% or more and 20.0 atomic% or less, it has high conductivity, excellent environmental resistance, and high adhesion to the Ag film, and when laminated with the Ag film. It is possible to form an oxide film having a high reflectance.

Further, since Y is contained in an amount of 0.1 atomic% or more and 10.0 atomic% or less, an oxide film having a high work function can be formed when laminated with an Ag film. Furthermore, since at least one or two types of Sn or Ti are contained in a total of 0.5 atomic% or more, an oxide film having excellent environmental resistance and alkali resistance can be formed. Since the total amount of at least one or two types of Sn or Ti is 10.0 atomic% or less, the occurrence of abnormal discharge during sputtering can be suppressed, and the formation of the oxide film is stable. It can be carried out.

Furthermore, with respect to the total amount of metal components, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al, In, Si, Ge, Pb, Bi and lanthanoids. When at least one additive element selected from the group consisting of a series of elements is contained in a total amount of 0.01 atomic% or more and 10.0 atomic% or less, the environmental resistance is further improved, and further. An oxide film with improved conductivity can be formed.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the invention.
For example, in the present embodiment, the oxide sputtering target has been described as being used for forming a transparent oxide film as a base material in a laminated reflective electrode film used as an anode of an organic EL display. It may be used when producing a transparent oxide film used for other uses such as a resistance film.

Further, in the present embodiment, an oxide sputtering target containing at least one or two kinds of Ga, Y, Sn or Ti, and the balance being Zn and unavoidable impurities, and these metal elements, and Zr. , Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al, In, Si, Ge, Pb, Bi and at least one selected from the group consisting of elements of the lanthanoid series. Although the oxide sputtering target containing the additive element of the above has been described, an additive element other than the above may be further added. However, in this case, the Zn content with respect to the total metal component amount needs to be 50 atomic% or more.

The results of the evaluation test for evaluating the action and effect of the oxide sputtering target according to the present invention will be described below. Examples 8, 9, and 10 of the present invention in Table 1 below are reference examples.

<Manufacturing of oxide sputtering target>
As raw material powders, gallium oxide _{(Ga 2 O} 3), yttrium oxide _{(Y 2 O} 3), titanium oxide _(TiO 2), tin oxide _(SnO 2), molybdenum oxide _(MoO 2), iron oxide _(Fe 2 _{O 3} ), Niobide oxide (Nb ₂ O ₅ ), and zirconium oxide (ZrO ₂ ) powders were prepared.
As the raw material powders, those having a purity of 99.9% by mass or more were prepared. Each of the prepared raw material powders was weighed so as to have the atomic ratio shown in Table 1.

_{The weighed raw material powder was put into a resin pot together with 4 times the amount of ZrO 2} balls (containing 5 mmφ and 10 mmφ in the same weight ratio) and a solvent with respect to the total mass of the raw material powder, and used with a ball mill device. Wet mixing was performed under the conditions of 85 rpm and 48 hours. Alcohol was used as the solvent. After wet mixing, the raw material powder was taken out from the resin pot and dried to obtain a mixed powder.

The obtained mixed powder was filled in a mold and pressed for 1 minute at a pressure of 175 MPa using a cold hydrostatic press (CIP) to obtain a molded product. The obtained molded product was put into a firing furnace, heated to 1450 ° C. at 10 ° C./sec in an atmospheric atmosphere, heated under the condition that the temperature was maintained for 3 hours, and then naturally cooled. A 150 mm × 200 mm × 7 mmt sintered body was obtained. The obtained sintered body was machined to produce a 126 mm × 178 mm × 6 mmt oxide sputtering target.

<Evaluation of oxide sputtering target>
The composition, relative density, abnormal discharge test, and specific resistance of the oxide sputtering targets produced in the examples of the present invention and the comparative examples were measured by the following methods. The results are shown in Table 1.

(composition)
The metal content of the mixed powder before molding was measured by ICP analysis, and the measured content of the metal element was converted into atomic%. It was confirmed in advance that the composition of the mixed powder and the composition of the target produced using the mixed powder match under the above-mentioned production conditions of the oxide sputtering target.

(Relative density)
The measured density of the oxide sputtering target was calculated from the dimensions of the oxide sputtering target measured with a caliper and the weight measured with an electronic balance. Next, the theoretical density of the oxide sputtering target was calculated from the mass% content and density of each oxide contained in the oxide sputtering target. For example, in the case of an oxide sputtering target containing Ga, Y and Ti, _{the mass% content of Ga 2} O ₃ is C1, the density is ρ1, _{the mass% content of Y 2} O ₃ is C2, and the density is ρ2. Assuming that the mass% content of TiO ₂ is C3 and the density is ρ3, the mass% content of ZnO is C4, and the density is ρ4, the theoretical density can be calculated from the following formula.
Theoretical density = 1 / [C1 / 100ρ1 + C2 / 100ρ2 + C3 / 100ρ3 + C4 / 100ρ4]

Then, the relative density was calculated from the above measured density and the theoretical density by the following formula.
Relative density (%) = measured density / theoretical density x 100

(Abnormal discharge test)
The oxide sputtering target was soldered to a backing plate made of Cu and mounted on a DC magnetron sputtering apparatus. Next, after exhausting to 1 × 10 ^-4 Pa, sputtering was performed under the conditions of Ar gas pressure: 0.3 Pa, input power: DC 500 W, and target-board distance: 70 mm. The number of abnormal discharges during spatter was measured as the number of abnormal discharges for one hour from the start of discharge by the arc count function of a DC power supply (model number: RPDG-50A) manufactured by MKS Instruments.

(Specific resistance)
The resistivity of the oxide sputtering target was measured by the four-probe method using the resistivity measuring instrument Loresta GP manufactured by Mitsubishi Chemical Corporation.

<Oxide film formation and oxide film evaluation>
Using the oxide sputtering targets of the examples of the present invention and the comparative examples, an oxide film having a thickness of 500 nm was formed on a glass substrate. The oxide film was formed by a DC magnetron sputtering apparatus. The spattering conditions were the same as in the abnormal discharge test described above.
The transmittance of the obtained oxide film was measured by the following method. The results are shown in Table 1.

(Transmittance)
Using a spectrophotometer (Hitachi spectrophotometer U-4100), the transmittance of the oxide film in the visible light region with a wavelength of 400 to 800 nm was measured, and the average value was calculated.

<Formation of laminated reflective film and evaluation of laminated reflective film>
A laminated reflective film having a three-layer structure having an oxide film of 10 nm / Ag—Cu alloy film of 100 nm / oxide film of 10 nm was formed on a glass substrate. The oxide film was formed by a DC magnetron sputtering apparatus using the oxide sputtering targets of the examples of the present invention and the comparative example. The Ag-Cu alloy film was formed by a DC magnetron sputtering apparatus using an Ag-0.5 at% Cu alloy sputtering target. The spattering conditions were the same as in the abnormal discharge test described above.
The sheet resistance, reflectance, work function, environmental resistance, etching resistance, and alkali resistance of the obtained laminated reflective film were measured by the following methods. The results are shown in Table 1.

(Sheet resistance)
The sheet resistance on the surface of the laminated reflective film was measured by the four-probe method using the resistance measuring instrument Loresta GP manufactured by Mitsubishi Chemical Corporation.

(Reflectance)
The reflectance of the laminated reflective film was measured with a spectrophotometer (Hitachi spectrophotometer U-4100). The average value of the reflectance of light having a wavelength of 400-450 nm near the blue wavelength was calculated.

(Work function)
The work function of the surface of the laminated reflective film was measured with an atmospheric photoelectron spectrometer AC-2 manufactured by RIKEN Keiki. The higher the work function, the more preferable it is to be used as an anode of an organic EL display. Since the work function and the resistance value on the surface of the laminated film are in a proportional relationship, the laminated film having an excessively high work function may be an insulating film.

(Environment resistance)
It was left for 100 hours in a high temperature and high humidity environment with a temperature of 85 ° C. and a humidity of 85%. The reflectance of the laminated reflective film after being left to stand was measured by the above method. Then, the rate of change in reflectance before and after leaving in a high-temperature and high-humidity environment was calculated by the following formula to evaluate the environmental resistance. The smaller the rate of change in reflectance, the better the environmental resistance.
Rate of change of reflectance = (reflectance after leaving-reflectance before leaving) / reflectance before leaving x 100

(Etching property)
After patterning the reflective laminated film by photolithography, wet etching was performed with an etching solution (phosphoricular acetic acid: Kanto Chemical SEA series) to form a comb-shaped pattern having a wiring width of 30 μm. The obtained comb-shaped pattern was observed by SEM, and the wiring width between the Ag—Cu alloy film and the oxide film was measured. Then, the volatility of the wiring width between the Ag—Cu alloy film and the oxide film was calculated by the following formula, and the etching property was evaluated. The smaller the fluctuation rate of the wiring width, the closer the dissolution rate of the Ag—Cu alloy film and the oxide film to the etching solution.
Fluctuation rate of wiring width = (wiring width of Ag-Cu alloy film-wiring width of oxide film) / wiring width of Ag-Cu alloy film x 100

(Alkali resistance)
The reflective laminate was immersed in a 5% NaOH aqueous solution at 40 ° C. for 10 minutes. The film thickness of the reflective laminated film before and after immersion in the NaOH aqueous solution was measured. Then, the rate of change in film thickness was calculated from the following formula to evaluate the alkali resistance. The smaller the rate of change in film thickness, the more difficult it is to dissolve in alkali, which means that the alkali resistance is excellent.
Rate of change in film thickness = (film thickness before immersion-film thickness after immersion) / (film thickness before immersion) x 100

In Comparative Example 1 in which the Ga content was less than 10.0 atomic%, the environmental resistance and alkali resistance of the laminated reflective film of the oxide film / Ag—Cu alloy film / oxide film became low. rice field.
In Comparative Example 2 in which the Ga content exceeded 20.0 atomic%, film formation by DC sputtering was not possible.

In Comparative Example 3 in which the Y content was less than 0.1 atomic%, the work function when the laminated reflective film was used was low. Generally, a laminated reflective film made of ITO 10 nm / Ag 100 nm / ITO 10 nm used as an anode of an organic EL display has a work function in the range of 4.6 to 4.8 eV. Therefore, if the laminated reflective film obtained in Comparative Example 3 is used as an anode of an organic EL display, the performance may deteriorate.
In Comparative Example 4 in which the Y content exceeded 10.0 atomic%, film formation by DC sputtering was not possible.

In Comparative Examples 5 and 7 in which the total content of at least one or two Sn or Ti was less than 0.5 atomic%, the environmental resistance and alkali resistance of the laminated reflective film were low.
In Comparative Examples 6 and 8 in which the total content of at least one or two Sn or Ti exceeded 10.0 atomic%, the number of abnormal discharges generated during sputtering increased.
In Comparative Example 9 in which the total content of the added element (Zr) exceeded 10.0 atomic%, the transmittance in the visible light region when the oxide film was formed as a single layer was reduced, and when the laminated reflective film was used. The anti-reflectance of blue light was reduced.

On the other hand, in Examples 1 to 14 of the present invention, the specific resistance of the oxide target was low and the transmittance of visible light was high. Further, the laminated reflective film has low sheet resistance, high reflectance and work function of blue light, and excellent environmental resistance, etching resistance, and alkali resistance.
Generally, a laminated reflective film made of ITO 10 nm / Ag 100 nm / ITO 10 nm, which is used as an anode of an organic EL display, has an average reflectance of about 79 to 80% for short wavelength light (blue light) having a wavelength of 400 to 450 nm. Become. On the other hand, in Examples 1 to 14 of the present invention, the reflectance of blue light is increased by about 2 to 4%, so that the effect on the life of the blue light emitting material of the organic EL display is large.

From the results of the above evaluation tests, according to the example of the present invention, an oxide film having high reflectance and work function when laminated with an Ag film, excellent environmental resistance, and capable of batch etching with an Ag film can be obtained. It was confirmed that it is possible to provide an oxide sputtering target capable of stably forming a film.

Claims (2)

ZnO is the main component, Ga is 10.0 atomic% or more and 20.0 atomic% or less, Y is 0.1 atomic% or more and 10.0 atomic% or less , and Ti is 0 . An oxide sputtering target comprising an oxide containing 5 atomic% or more and 10.0 atomic% or less and having a relative density of 91.3% or more. Furthermore, with respect to the total amount of metal components, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, B, Al, In, Si, Ge, Pb, Bi and lanthanoid series. The oxide sputtering according to claim 1, wherein at least one additive element selected from the group consisting of the above-mentioned elements is contained in an amount of 0.01 atomic% or more and 10.0 atomic% or less in total. target.