JP2012031491A - Sputtering target for forming transparent conductive film, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target for forming a transparent conductive film with higher conductivity, and to provide a method for manufacturing the same.SOLUTION: A method for producing a sputtering target for forming a transparent conductive film includes: a step for blending an oxide of Al, an oxide of Mg, an oxide of Ga, and an oxide of Zn, wherein the content ratio of metal component elements is 0.5-8 atom% Al, 5-30 atom% Mg, 0.01-0.15 atom% Ga, and the balance Zn, and pulverizing and mixing the oxides to produce a mixed powder; and a step for heating and sintering the mixed powder while being pressurized in a vacuum or an inert gas atmosphere.

Description

  The present invention relates to a sputtering target for forming a transparent conductive film used for a liquid crystal display device, an organic electroluminescence display device, an antistatic conductive film coating, a gas sensor, a solar cell, and the like, and a method of manufacturing the same.

Conventionally, a transparent conductive film made of an Al-Mg-Zn-based oxide has been known as a kind of transparent conductive film used for liquid crystal display devices, electroluminescence display devices, antistatic conductive film coatings, gas sensors, solar cells, and the like. Yes. In particular, an Al—Mg—Zn-based oxide film represented by Zn _1-X Mg _X O doped with Al can be intentionally controlled with a band gap of 3.5 to 3.97 eV depending on the amount of Mg added. Application as a transparent conductive film for solar cells and UV light devices is expected.

International Publication No. 2006/129410

APPLIED PHYSICS LETTERS, Vol. 85, no. 8, p. 1374 to 1376

The following problems remain in the conventional technology.
That is, in the sputtering target made of the Al—Mg—Zn-based oxide described in the conventional patent document 1, a bulk resistance of 30 to 60 × 10 ⁻³ Ω · cm is obtained, but the deposition rate is higher. In order to perform stable DC sputtering, higher conductivity is required.

  This invention is made | formed in view of the above-mentioned subject, and it aims at providing the sputtering target for transparent conductive films which has still higher electroconductivity, and its manufacturing method.

The electric resistance of a general Al-doped zinc oxide dense sintered body (for example, a sintered body of ZnO added with _{2 to 3} wt% of Al ₂ O ₃ ) is 4 to 8 × 10 ⁻⁴ Ω · cm, The electric resistance of the Al—Mg—Zn-based oxide target in the example described in Patent Document 1 is 30 to 60 × 10 ⁻³ Ω · cm, which is nearly 100 times higher. One of the main causes of the deterioration of the conductivity of the Al—Mg—Zn-based oxide target by the inventors of the present application is a decrease in carriers in the sintered body due to the reaction between Al ₂ O ₃ and MgO. I found out.

In order to suppress the reaction between Al ₂ O ₃ and MgO, Patent Document 1 proposes a method in which a mixed powder of Al ₂ O ₃ and ZnO is calcined, reacted to some extent first, and then sintered with MgO at a high temperature. ing. However, in order to make the reaction between Al ₂ O ₃ and ZnO sufficiently, the temperature of calcination must be increased, while the mixture of Al ₂ O ₃ and ZnO calcined at high temperature is mixed with MgO. However, when the main sintering is performed, the temperature at which the sintering can be performed densely becomes higher. When sintered at this high sintering temperature, the reaction between MgO and Al ₂ O ₃ and the reaction between MgO and ZnO become intense, and even if Al ₂ O ₃ and ZnO are calcined, the sintered body loses its conductivity. .

  The present invention employs the following configuration in order to solve the above problems. That is, according to the method for manufacturing a sputtering target for a transparent conductive film of the present invention, an Al oxide, a Mg oxide, a Ga oxide, and a Zn oxide have a metal component element content ratio of Al: 0. The process which mix | blends so that it may consist of 5-8 atomic%, Mg: 5-30 atomic%, Ga: 0.01-0.15 atomic%, remainder: Zn, and pulverize-mixes the said oxide, and produces mixed powder. And heating and sintering the mixed powder while applying pressure in a vacuum or an inert gas atmosphere.

Moreover, as for the sputtering target for transparent conductive films of this invention, the content rate of a metal component element is Al: 0.5-8 atomic%, Mg: 5-30 atomic%, Ga: 0.01-0.15 atomic%. The balance is an oxide target made of Zn, and has a volume resistance of 1 × 10 ⁻² Ω · cm or less.

In this method of manufacturing a sputtering target for a transparent conductive film, a mixed powder in which Al oxide, Mg oxide, Ga oxide, and Zn oxide are mixed in the above content ratio is pressure-sintered. Promotes diffusion of Al into Zn oxide as a diffusion aid, and an Al—Mg—Ga—Zn-based oxide sputtering target with further improved conductivity can be obtained. That is, an Al—Mg—Ga—Zn-based oxide sputtering target having a volume resistance of 1 × 10 ⁻² Ω · cm or less is obtained.

According to the research result of the inventors of the present invention, Ga has a faster diffusion rate in ZnO than Al, and with the diffusion of Ga, substitution of Al ions to Zn ²⁺ sites in the ZnO crystal becomes active. Therefore, sintering proceeds at a relatively low temperature, and a high-density sintered body can be obtained at a temperature lower than that of Patent Document 1. On the other hand, since the reaction between Ga ions and MgO was not confirmed, the reaction between Al ₂ O ₃ and MgO and the reaction between MgO and ZnO due to the addition of Ga were not promoted. That is, by adding Ga, the sintering temperature of Al ₂ O ₃ and ZnO is lowered, and a dense sintered body can be obtained even at a relatively low temperature. Compared to the conventional relatively high sintering temperature, the reaction between Al ₂ O ₃ and MgO and the reaction between MgO and ZnO are suppressed, and the conductivity of the sintered body can be ensured.

Furthermore, in the present invention, pressure sintering such as hot pressing is performed to lower the sintering temperature, thereby realizing high density and high conductivity of the target. That is, by performing pressure sintering, the densification temperature is lowered, a high-density sintered body suitable for sputtering is manufactured at a relatively low sintering temperature, and Al ₂ O ₃ and MgO produced during sintering at a high temperature are produced. And the reaction between MgO and ZnO were suppressed.
In other words, by simultaneously using the sintering enhancement effect by Ga addition, the densification temperature reduction effect and the densification temperature reduction effect by pressure sintering such as hot pressing, etc., high density and high conductivity suitable for sputtering are obtained. Realize the target you have.

Here, the reason for limiting the content ratio of the metal component element of the present invention as described above is as follows.
Al:
Al is added because it has a function of improving the carrier density of the transparent conductive film obtained by sputtering and imparting conductivity to the film, but if the content is less than 0.5 atomic%, the conductivity improving effect is added. On the other hand, if the Al content exceeds 8 atomic%, the sinterability of the target deteriorates, which is not preferable. Therefore, the content ratio of Al in all the metal component elements contained in this sputtering target is set to Al: 0.5 to 8 atomic%.

Mg:
Mg is effective in adjusting the band gap of the transparent conductive film obtained by sputtering and improving the transparency with respect to light having a short wavelength and the transparency with respect to light having a near infrared wavelength. When the Mg content is less than 5 atomic%, the transmittance in the short wavelength region is reduced. On the other hand, when the Mg content exceeds 30 atomic%, the conductivity of the transparent conductive film is significantly reduced. Therefore, the content ratio of Mg in all metal component elements was determined to be Mg: 5 to 30 atomic%.

Ga:
By containing 0.01 atomic% or more of Ga as a metal component element in the transparent conductive film, high conductivity can be obtained while maintaining the band gap without impairing the transparency of the film. When the Ga content is less than 0.01 atomic%, the function of Al as a diffusion aid for Zn oxide cannot be sufficiently obtained. On the other hand, when the Ga content exceeds 0.15 atomic%, Since the crystal grains of the target after the sintering tend to abnormally grow, the strength as a sintered body is reduced and the target is easily cracked during sputtering, the Ga content ratio in the total metal component elements contained in the transparent conductive film Was determined as Ga: 0.01 to 0.15 atomic%.

The present invention has the following effects.
That is, according to the method for manufacturing a sputtering target for a transparent conductive film according to the present invention, a mixed powder in which Al oxide, Mg oxide, Ga oxide, and Zn oxide are mixed in the above content ratio is added. Since pressure sintering is performed, Ga acts as a diffusion aid, promotes diffusion of Al into Zn oxide, and an Al—Mg—Ga—Zn-based oxide sputtering target with further improved conductivity can be obtained.
Therefore, since the sputtering target for transparent conductive film produced by the production method of the present invention has high conductivity, stable DC sputtering is possible, and a transparent conductive film excellent in transparency and conductivity is formed. Can be membrane.

In the Example of the sputtering target for transparent conductive films which concerns on this invention, and its manufacturing method, it is an image which shows element distribution mapping by EPMA about the produced sintered compact.

Hereinafter, an embodiment of a sputtering target for a transparent conductive film and a method for producing the same according to the present invention will be described.
The manufacturing method of the sputtering target for transparent conductive films of this embodiment has Al oxide, Mg oxide, Ga oxide, and Zn oxide, and the content rate of a metal component element is Al: 0.5. ~ 8 atomic%, Mg: 5-30 atomic%, Ga: 0.01-0.15 atomic%, the balance: a step of preparing a mixed powder by pulverizing and mixing the oxides, and Zn And heating and sintering the mixed powder while applying pressure in a vacuum or an inert gas atmosphere.

If described in detail an example of the above process, for example, first as a raw material powder, a commercially available _Al 2 _{O 3} powder having a purity of 99.9% or higher and an average particle diameter of 0.05 to 1 [mu] m, MgO powder, _Ga 2 _{O 3} Powder and ZnO powder are weighed and blended so as to have a predetermined composition. Raw material powder having an average particle size of less than 0.05 μm has good sinterability, but the density of the green compact by pressurization is low, the shrinkage rate during sintering is large, and cracks may occur. Raw material powder exceeding 1 μm has a high density of green compacts by pressurization, but has poor sinterability. Therefore, raw material powder having an average particle size of 0.05 to 1 μm is preferable for obtaining a high-density sintered body at a low sintering temperature. These powders are charged into a ball mill pot together with alcohol as a mixing aid, and wet-mixed preferably using a zirconia ball having a diameter of 5 mm for 24 hours or more. The obtained mixed powder was vacuum-dried at 80 ° C. for 5 hours.

The prepared mixed powder is filled into a graphite mold and hot-pressed in vacuum at a temperature rising temperature of 10 ° C./min, a maximum temperature of 1000 to 1350 ° C., and a pressure of 150 to 500 kgf / cm ^2. The sputtering target for transparent conductive film formation is produced by making this sintered body into a predetermined shape by machining. Further, a method of heating and pressing while passing an electric current through the sintered body (plasma pressure sintering method) is more preferable because it has an effect of further lowering the sintering temperature and shortening the sintering time. In the sputtering target for forming a transparent conductive film thus produced, the content ratio of the metal component elements is Al: 0.5 to 8 atomic%, Mg: 5 to 30 atomic%, Ga: 0.00. It is an oxide sputtering target composed of 01 to 0.15 atomic% and the balance Zn. Moreover, this sputtering target for transparent conductive film formation has favorable electroconductivity whose volume resistance is 1 * 10 ^<-2 > ohm * cm or less, ie, 0.0001-0.01 ohm * cm.

Preferred sputtering conditions for performing sputtering are, for example, as follows.
First, the relative density of the sputtering target is preferably 90% or more. When the relative density is less than 90%, the film formation rate is lowered and the film quality of the obtained film is lowered. The relative density of the sputtering target is more preferably 95% or more, and still more preferably 97% or more.
Note that the purity of the sputtering target is preferably 99% or more. If the purity is less than 99%, the conductivity and chemical stability of the resulting film are reduced due to impurities. Furthermore, the purity of the sputtering target is more preferably 99.9% or more, and further preferably 99.99% or more.

  Further, in performing DC sputtering using the above-described sputtering target, first, a film-forming substrate (hereinafter referred to as “film-forming substrate”) and a sputtering target are mounted in a vacuum chamber of the sputtering apparatus, and the apparatus, the substrate is formed. It is desirable to remove moisture adsorbed on the film substrate, sputtering target, or the like.

The removal of the water can be performed, for example, by evacuating until the ultimate vacuum pressure of the vacuum chamber is 5 × 10 ⁻⁴ Pa or less (low pressure of 5 × 10 ⁻⁴ Pa or less). Heating is preferably performed during evacuation, and this heating makes it possible to more reliably remove moisture and shorten the time for evacuation. The ultimate vacuum pressure at this time is more than 5 × 10 -4 ^Pa (the pressure higher than 5 × 10 -4 ^Pa), apparatus, film formation substrate, removal of moisture adsorbed on the sputtering target or the like becomes insufficient Since it is easy, the denseness of the obtained film is lowered, which affects the conductivity and moisture resistance of the film. Note that the exhaust system of the sputtering apparatus to be used preferably has a trap or getter for removing moisture by using a cryopump.

After performing the above-described evacuation, a transparent conductive film is formed. The sputtering gas pressure during film formation is preferably 1 × 10 ⁻² to 2 × 10 ⁰ Pa. The sputtering gas pressure is decreased discharge stability of 1 × ¹⁰ -2 less than Pa (1 × ¹⁰ -2 lower pressure than Pa) at the time of film formation, 1 × more than ¹⁰ 0 Pa (1 × ¹⁰ 0 pressure than Pa is High), it becomes difficult to increase the voltage applied to the sputtering target. The sputtering gas pressure during film formation is more preferably 0.1 to 1 Pa.

Moreover, it is preferable that the direct-current power output during film formation is 1 W / cm ² or more and 10 W / cm ² or less using a flat target. When this output exceeds 10 W / cm ² , the denseness of the resulting film decreases. The output during film formation is more preferably 3 to 8 W / cm ² . Moreover, it is preferable that the sputtering voltage at the time of film-forming shall be 200-500V.

As the atmospheric gas during the film formation, a sufficient highly transparent film is usually obtained only with argon gas (Ar gas), but a mixed gas of argon gas (Ar gas) and oxygen gas (O ₂ gas) is used. It is also possible. The mixing ratio of Ar gas and O ₂ gas varies depending on the oxidation state of the sputtering target to be used, the vacuum state at the time of film formation, and the output, but when the volume concentration of O ₂ gas in the atmospheric gas exceeds 5%, The conductivity of the resulting film tends to decrease. Therefore, the volume concentration of O ₂ gas in the atmospheric gas during film formation is preferably 5% or less, and more preferably 3% or less.
Note that the purity of the atmospheric gas is preferably 99.991% or more, more preferably 99.995% or more, and particularly preferably 99.999% or more.

  The substrate temperature at the time of film formation can be appropriately selected within the range of room temperature to the heat resistant temperature of the film formed substrate, but if the substrate temperature exceeds 200 ° C., it can be used because many resin substrates exceed the heat resistant temperature. The type of substrate is strongly limited. Further, if the substrate temperature is less than 50 ° C., the denseness of the resulting film is lowered, so that the substrate temperature during film formation is preferably 50 to 200 ° C., more preferably 80 to 200 ° C., 100 It is especially preferable to set it to -200 degreeC.

The film formation substrate can be appropriately selected depending on the intended use of the transparent conductive film, and there is no particular limitation such as a glass substrate, a metal substrate, a heat-resistant resin substrate, a solar cell (in the process of production), and the like. Specific examples of the glass substrate include glass substrates made of soda lime glass, lead glass, borosilicate glass, high oxalate glass, non-alkali glass, etc., and SiO ₂ , SiO _x (1 ≦ x <2), TiO _x (1 ≦ x ≦ 2), etc. are coated.

  Specific examples of the metal substrate include metal foils such as stainless steel foil, copper foil, and aluminum foil, as well as metal plates and metal sheets having the same quality as the metal foil. Specific examples of the heat-resistant resin substrate include a polyester resin such as polyethylene terephthalate, a polycarbonate resin, a polyarylate resin, a polyethersulfone resin, an amorphous polyolefin resin, a polystyrene resin, an acrylic resin, and the like. Examples thereof include a molded body, a film, a sheet, and the like made of a resin having a temperature equal to or higher than ° C., and a gas barrier layer, a solvent resistant layer, a hard coat layer, and the like formed on these surfaces.

Thus, in the manufacturing method of the sputtering target for transparent conductive films of this embodiment, the mixed powder which mix | blended Al oxide, Mg oxide, Ga oxide, and Zn oxide in the said content rate is pressurized. Since sintering is performed, Ga can promote diffusion of Al into Zn oxide as a diffusion aid, and an Al—Mg—Ga—Zn-based oxide sputtering target with further improved conductivity can be obtained. That is, an Al—Mg—Ga—Zn-based oxide sputtering target having a volume resistance of 1 × 10 ⁻² Ω · cm or less is obtained.
Further, in this embodiment, Ga is added and pressure sintering such as hot pressing is performed. Therefore, sintering enhancement by adding Ga, the effect of reducing the densification temperature, and sintering promotion by pressure sintering such as hot pressing are performed. In addition, by utilizing the effect of reducing the densification temperature at the same time, a high density and high electrical conductivity target suitable for sputtering can be obtained by the synergistic effect.

  Based on the said embodiment, the Example at the time of actually manufacturing the sputtering target for transparent conductive films is demonstrated below.

As raw material powders of examples of the present invention, Al ₂ O ₃ raw material powder having a purity of 99.9% or more and an average particle diameter of 0.4 μm, MgO raw material powder having a purity of 99.9% or more and an average particle diameter of 1 μm, purity of 99.9% The Ga ₂ O ₃ raw material powder having an average particle diameter of 0.3 μm and the ZnO raw material powder having a purity of 99.9% or more and an average particle diameter of 0.4 μm were weighed and blended so as to have the predetermined composition shown in Table 1. The blended powder is put into a polyethylene pot, ball milled using zirconia balls with a diameter of 3 mm, mixed and pulverized (note that the solvent used in the ball mill is ethanol, and the dispersant and other auxiliaries are The slurry that reached the target average particle size (0.3 μm) was vacuum-dried at 80 ° C. for 5 hours in a vacuum dryer. Sieving using a 500 μm sieve mesh was performed to granulate the mixed powder to an average particle size of 500 μm or less.

The dried mixed powder is filled into a graphite mold and hot-pressed in vacuum at a temperature rising temperature of 10 ° C./min, a maximum temperature of 1000 to 1350 ° C., and a pressure of 150 to 500 kgf / cm ² , thereby obtaining a diameter of 165 × A sintered body having a thickness of 9 mm was prepared, and thereafter, a sputtering target for forming a transparent conductive film having a diameter of 152.4 × thickness of 6 mm (Examples 1 to 6) was prepared by machining.
Furthermore, as a comparative example, a target was prepared by a method similar to the above using a composition in which the added amount of Al, Ga, and Mg exceeded the range (Comparative Examples 1 to 5).

  For comparison, a transparent conductive film forming sputtering target (conventional examples 1 to 4 in Table 1) was produced by the same production method as in Patent Document 1.

First, as a raw material powder of a conventional example, an Al ₂ O ₃ raw material powder having a purity of 99.9% or more and an average particle diameter of 0.4 μm, an MgO raw material powder having a purity of 99.9% or more and an average particle diameter of 1 μm, and a purity of 99.9% or more ZnO raw material powder having an average particle size of 0.4 μm was weighed so as to have a predetermined composition. Among the weighed raw material powders, Al ₂ O ₃ and ZnO were blended, the blended powder was put into a polyethylene pot, and ball milling was performed for 8 hours using zirconia balls having a diameter of 3 mm, followed by mixing and grinding ( The solvent used for the ball mill is ethanol, and no dispersant or other auxiliary agent is added). Then, after vacuum-drying at 80 degreeC with a vacuum dryer for 5 hours, sieving using a 500 micrometers sieve was performed, and the average particle diameter of mixed powder was 500 micrometers or less.

Next, this granulated mixed powder is calcined in the atmosphere at 1000 ° C. for 3 hours to prepare a calcined powder of Al ₂ O ₃ and ZnO, and the above-mentioned MgO raw material powder is further added to the calcined powder. Was added, and ball milling was performed for 8 hours using zirconia balls having a diameter of 3 mm, followed by mixing and pulverization (note that the solvent used in the ball mill was ethanol, and no dispersant or other auxiliary agent was added). Then, after vacuum-drying at 80 degreeC with a vacuum dryer for 5 hours, sieving using a 500 micrometers sieve was performed, and the average particle diameter of mixed powder was granulated to 500 micrometers or less.

Next, the granulated mixed powder is calcined at 1000 ° C. for 3 hours to prepare a calcined powder of Al ₂ O ₃ , ZnO and MgO, and a ball mill is used for 24 hours using zirconia balls having a diameter of 3 mm. (The solvent used in the ball mill is ethanol, and no dispersant or other auxiliary agent is added). Thereafter, the calcined powder was vacuum-dried at 80 ° C. for 5 hours in a vacuum dryer, and then sieved using a 500 μm sieve mesh to granulate the mixed powder to an average particle size of 500 μm or less. .

Next, the granulated calcined powder is pressure-molded with a die press having a pressure of 500 kgf / cm ² and further fired in an oxygen atmosphere at 1400 ° C. for 5 hours to produce a sintered body. Then, the transparent conductive film formation sputtering target (conventional examples 1-4) of the same size as the Example of this invention was produced by machining.

Thus, the theoretical density ratios of the respective sintered bodies produced by the production methods of the conventional example, the examples of the present invention, and the comparative examples were calculated and listed in Table 1. The theoretical density ratio was calculated as follows: theoretical density ratio% = (volume density of sintered body / theoretical density) × 100
Density weight% / MgO of the theoretical density = 1 / (weight of raw material _{Al 2 O 3% / Al 2} O 3 of the weight of the density + raw material _{Ga 2 O 3% / Ga 2} O 3 of density + raw material MgO + Wt% of ZnO in raw material / ZnO density)

Furthermore, the specific resistance of the target was measured using a Mitsubishi Chemical resistance measuring instrument Lorestar. As a result of the measurement, the sintered bodies according to the conventional examples 1 to 4 had a high specific resistance and could not be measured, and were not electrically conductive. On the other hand, the sintered bodies according to the examples 1 to 6 of the present invention had a maximum of 7 Good conductivity of × 10 ⁻³ Ω · cm was obtained. In Patent Document 1, it is described that a bulk resistance of 30 to 60 × 10 ⁻³ Ω · cm was obtained. However, as a result of additional tests as described above, the sintered bodies according to Conventional Examples 1 to 4 are conductive. Could not get. Even if the sintered body according to the conventional example has a specific resistance as described in Patent Document 1, the sintered body according to the example of the present invention has a specific resistance that is lower by one digit or more than the conventional example. I understand that.

Thus, in the manufacturing method of the embodiment of the present invention, Ga promotes diffusion of Al into Zn oxide as a diffusion aid, and Al ³⁺ dissolves in Zn ²⁺ to further improve conductivity. An Al—Mg—Ga—Zn-based oxide sputtering target is considered to be obtained.
In addition, the image which shows element distribution mapping by EPMA (electron beam microanalyzer) measurement about the sintered compact produced by the manufacturing method of the Example of this invention in FIG. 1 is shown. This EPMA image also shows that Al is dispersed in the structure.

  Next, the targets of the conventional example, the examples of the present invention, and the comparative example were evaluated using a direct current sputtering method. That is, it was tested whether each target can be sputtered using a DC sputtering power source (RPG-50 manufactured by MKS).

  The sputtering gas during sputtering was Ar only, the gas pressure during sputtering was 0.6 Pa, the distance between the substrate and the target was 70 mm, and the substrate temperature was room temperature. The electric power supplied to each target (φ152.4) is 1200 W. Furthermore, continuous discharge was performed at 1200 W for 30 minutes, the number of abnormal discharges during 30 minutes of continuous sputtering was measured using an abnormal discharge counter provided in the power source, and the presence or absence of target cracking due to sputtering was visually confirmed. Thereafter, a 300 nm film was formed on a glass substrate (Corning 1737 #), and the electric resistance of the film was measured using a four probe method (Mitsubishi Chemical Resistance Tester Lorestar). All results are shown in Table 2.

  From the experimental results shown in Table 2, the targets of Conventional Examples 1 to 4 could not be DC sputtered because of their high electrical resistance. On the other hand, in Comparative Example 1, since the amount of Al added was small, the target resistance was high and DC sputtering could not be performed as well. In Comparative Example 2, since the amount of Al added was large, the sinterability of the target was reduced, the target density was low, the abnormal discharge during sputtering was large, and the electrical resistance of the film was high. In Comparative Example 3, since the content of Mg was large, the resistance of the target was high, and abnormal discharge during sputtering increased. Furthermore, it can be seen that the electrical resistance of the film is also high.

  In Comparative Example 4, since Ga was excessively added, crystal grains of the target grew during sintering, the strength as a bulk decreased, and cracks occurred in the target in DC continuous sputtering, which caused a dramatic increase in abnormal discharge. did. In Comparative Example 5, Ga was not added, and the effect of promoting the sintering of Ga was not obtained. Therefore, the density of the target was low, and cracking occurred during sputtering.

From the above comparison results, in the manufacturing method according to the example of the present invention, Ga promotes diffusion of Al into Zn oxide as a diffusion aid, and Al ³⁺ dissolves in Zn ²⁺ so that conductivity is improved. Further improved Al—Mg—Ga—Zn-based oxide sputtering target has significantly less occurrence of abnormal discharge during long-time sputtering, and is further excellent in spatter crack resistance.

  The technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.

  As mentioned above, since the manufacturing method of the sputtering target for transparent conductive films of this invention can produce the sputtering target for transparent conductive films which has high electroconductivity, for example, the transparent conductive films for solar cells, organic EL, etc. are high. It is expected as a method for producing a sputtering target capable of DC sputtering stably at a deposition rate.

Claims (2)

The content ratio of the metal component element is an oxide target composed of Al: 0.5 to 8 atom%, Mg: 5 to 30 atom%, Ga: 0.01 to 0.15 atom%, and the balance: Zn,
A sputtering target for a transparent conductive film, wherein the volume resistance is 1 × 10 ⁻² Ω · cm or less. Al oxide, Mg oxide, Ga oxide, and Zn oxide have a metal component element content ratio of Al: 0.5 to 8 atomic%, Mg: 5 to 30 atomic%, Ga: 0.01-0.15 atomic%, the balance: blended to consist of Zn, pulverize and mix the oxide to produce a mixed powder;
And heating and sintering the mixed powder while applying pressure in a vacuum or an inert gas atmosphere. A method for producing a sputtering target for a transparent conductive film, comprising: