JP2009249187A - Zinc oxide sintered compact, its producing method, sputtering target and electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode having low resistivity and high weather resistance, by using a zinc oxide sintered compact for a sputtering target. <P>SOLUTION: The change of the resistivity when the electrode is exposed under a humidity of 90% RH at 60°C is measured as the weather resistance of the electrode. Measured results in such three cases as (a) 200 nm film thickness, (b) 100 nm film thickness and (c) 100 nm film thickness without CeO<SB>2</SB>addition when a sputtering target similar to the sputtering target is used are shown in Fig.6. The initial value of the resistivity is around 6 to 7×10<SP>-4</SP>Ωcm, which is sufficiently small, and is increased gradually to 20 Ωcm or more after a lapse of 200 hours in (c) which is a case without CeO<SB>2</SB>addition. However, the increasing of the resistivity in (a) and (b) which are cases with CeO<SB>2</SB>addition is suppressed very much. Especially, a small resistivity of 10<SP>-3</SP>Ωcm or less is kept after a lapse of 1,000 hours in the case of 200 nm film thickness. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a zinc oxide sintered body used for a sputtering target or the like when zinc oxide to be a transparent electrode material is formed by a sputtering method, and a method for producing the same. The present invention also relates to an electrode formed using this sputtering target.

A liquid crystal display, a solar cell, and the like use an electrode that is conductive and transparent to light (transparent electrode). As materials having such properties, for example, oxide materials such as In ₂ O ₃ —SnO ₂ (ITO), ZnO—B ₂ O ₃ (BZO), and ZnO—Al ₂ O ₃ (AZO) are known. . Such a material is formed as a thin film on a liquid crystal display or solar cell by sputtering, and then patterned as an electrode to become a transparent electrode. In the sputtering method, in a sputtering apparatus, a substrate on which a thin film is to be formed (in this case, a liquid crystal display or the like) and a sputtering target (hereinafter referred to as a target) are arranged facing each other. A gas discharge is generated between them, ions generated by the gas discharge collide with the surface of the target, and atoms (particles) released by the impact are attached to the opposing substrate to form a thin film. The target is formed of a material that becomes a thin film (transparent electrode), and the characteristics of the transparent electrode reflect the characteristics of the target. In general, the target is very expensive, and the price accounts for a large proportion of the manufacturing cost of the liquid crystal display and solar cell. For this reason, in order to reduce the cost of liquid crystal displays and solar cells, the target is also required to be inexpensive.

ITO is tin (Sn) -doped indium oxide (In ₂ O ₃ ). When this is used, the light transmittance is 85% or more, and the specific resistance value is 1.0 × 10 ⁻⁴ Ω · cm. A transparent electrode of a certain degree has been obtained, and its characteristics are sufficient for use in liquid crystal displays and solar cells. However, since indium (In) as a main component of the raw material is expensive, the target is expensive. In particular, when forming a large-area liquid crystal display or a transparent electrode for a solar cell, a target having a large area of the same level is required, which causes high costs. For this reason, a transparent electrode made of a lower cost material and having equivalent characteristics has been desired.

BZO and AZO are materials in which boron (B) and aluminum (Al), which are n-type conductive additives, are added to zinc oxide (ZnO), which is a semiconductor, and are mainly composed of inexpensive zinc. It is superior to ITO in terms of low price. As a target of these materials, a sintered body is widely used because a large-area target can be easily obtained. A sintered body of BZO or AZO is obtained by blending raw material powder and sintering at a high temperature of 1000 ° C. or higher after molding. As the raw material powder, ZnO powder as a main component and B ₂ O ₃ powder or Al ₂ O ₃ powder as an additive component are used. Similarly, ZnO—Ga ₂ O ₃ (GZO) or the like is also known as a zinc oxide-based material to which Ga ₂ O ₃ is added.

When using a sintered body having such a composition as a target, if there are many vacancies in the sintered body, there is a problem that abnormal discharge occurs during sputtering. For this reason, in Patent Document 1, for example, when AZO is manufactured, a calcined powder containing ZnAl ₂ O ₄ is first manufactured, and this is mixed with the ZnO powder and fired again to reduce the number of pores. Techniques to do this are disclosed.

  Moreover, the transparent electrode actually obtained using these targets has a problem that it deteriorates due to humidity, that is, has poor weather resistance. For example, under a humidity of 60 ° C. or higher and 90% RH or higher, the resistivity rapidly increases after 200 hours even if the initial resistivity is low. Therefore, improving the weather resistance of these materials has become an important issue.

  For this reason, Patent Document 2 describes a technique for improving the weather resistance of an electrode by using an AZO sintered body whose composition and crystallinity are precisely controlled and optimized as a target. Patent Document 1 also discloses that it is effective to add Ga and In to AZO.

WO2008 / 018402 JP 2006-200016 A

  However, even when a transparent electrode was formed using the targets described in Patent Documents 1 and 2, the weather resistance was not sufficient. For example, in Patent Document 2, a transparent electrode having a resistance change (resistance increase rate) of several percent after 200 hours at 60 ° C. and 90% RH is obtained by the above technique. However, the film thickness is as thick as 300 nm. However, in general, when the film thickness is thin, the influence of the surface appears strongly, so the influence of weather resistance becomes more prominent, and the resistivity may exceed 10 times the initial value after 1000 hours under the same conditions. . Accordingly, it has been required to reduce the resistivity increase rate for a longer time, for example, 1000 hours, even at the same temperature and humidity even with a thinner film thickness. That is, a technique capable of obtaining a transparent electrode having a low initial resistivity and high weather resistance even when it is thinner than this is required, and the weather resistance is insufficient in the techniques described in Patent Documents 1 and 2. It was.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The gist of the invention described in claim 1 is a zinc oxide sintered body containing Al in ZnO, which is Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy. , Er, Tm, and Yb are added as an additive element, the Al addition amount is 0.1 to 10 wt% in terms of oxide, and the addition amount of the additive element is 0. 0 in terms of oxide. It exists in the range of 01-2 wt%, and exists in the zinc oxide sintered compact characterized by the above-mentioned.
The gist of the invention described in claim 2 is that the zinc oxide sintered body according to claim 1, wherein the ZnAl ₂ O ₄ phase and the oxide phase of the additive element are dispersed in the ZnO phase. Exist.
The gist of the invention of claim 3 is a zinc oxide sintered body containing Ga in ZnO, and is Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy. , Er, Tm, and Yb are added as additive elements, the Ga addition amount is 0.1 to 10 wt% in terms of oxide, and the additive element addition amount is 0.1 in terms of oxide. It exists in the range of 01-2 wt%, and exists in the zinc oxide sintered compact characterized by the above-mentioned.
The gist of the invention of claim 4 is that the ZnGa ₂ O ₄ phase and the oxide phase of the additive element are dispersed in the ZnO phase. Exist.
The gist of the invention described in claim 5 is a zinc oxide sintered body containing B in ZnO, which is Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy. , Er, Tm, and Yb are added as additive elements, the B addition amount is 0.1 to 10 wt% in terms of oxide, and the additive element addition amount is 0. 0 in terms of oxide. It exists in the range of 01-2 wt%, and exists in the zinc oxide sintered compact characterized by the above-mentioned.
The gist of the invention according to claim 6 is that the ZnB ₂ O ₄ phase and the oxide phase of the additive element are dispersed in the ZnO phase. Exist.
The gist of the invention described in claim 7 is a zinc oxide sintered body containing two or more of Al, Ga and B in ZnO, and Mg, Ca, Sr, Ba, La, Ce, Pr, Nd , Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb is added as an additive element, and the total amount of Al, Ga, and B in terms of oxide is 0.1 to 15 wt%, The additive amount of the additive element is in the range of 0.01 to 2 wt% in terms of oxide.
The gist of the invention described in claim 8 is that a composite oxide phase composed of two or more of ZnAl ₂ O ₄ phase, ZnGa ₂ O ₄ phase and ZnB ₂ O ₄ phase is dispersed in ZnO, and the additive element The zinc oxide sintered body according to claim 7, wherein the oxide phase is dispersed.
The gist of the invention of claim 9 is that ZnO contains at least one of Al, Ga, and B, and Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd. , Tb, Dy, Er, Tm, Yb, and a method for producing a zinc oxide sintered body to which one or more of these elements are added as additive elements, wherein any one or more of Al, Ga, and B are selected. A calcined powder manufacturing process in which a powder composed of an oxide and the first ZnO powder are blended, and calcined at a temperature in the range of 900 to 1300 ° C. to produce a calcined powder, the calcined powder, and the second ZnO And a main firing step of obtaining a zinc oxide sintered body by firing a compact formed by blending the powder and the oxide of the additive element, and manufacturing the zinc oxide sintered body, Lies in the way.
The gist of the invention according to claim 10 resides in the method for producing a zinc oxide sintered body according to claim 9, wherein the firing in the calcined powder production step is performed in a non-reducing atmosphere.
The gist of the invention described in claim 11 is that ZnO contains at least one of Al, Ga, and B, and Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, and Gd. , Tb, Dy, Er, Tm, Yb, a method for producing a zinc oxide sintered body in which one or more of them are added as additive elements, ZnAl ₂ O ₄ , ZnGa ₂ O ₄ , ZnB ₂ O ₄ A main firing step of obtaining a zinc oxide sintered body by firing a formed body formed by blending a powder mainly containing any one or more of the above, a ZnO powder, and an oxide of the additive element. In the manufacturing method of the zinc oxide sintered compact characterized by comprising.
The gist of the invention described in claim 12 resides in a sputtering target comprising the zinc oxide sintered body according to any one of claims 1 to 8.
The gist of the invention described in claim 13 resides in an electrode characterized in that the sputtering target according to claim 12 is used and formed to a thickness of 200 nm or less by a sputtering method.

  Since this invention is comprised as mentioned above, an electrode with low resistivity and high weather resistance can be obtained using this zinc oxide sintered compact for a sputtering target.

Inventors, _ZnO-Al 2 _O 3 as a target material for forming the transparent electrode _{(AZO), ZnO-Ga 2} O 3 (GZO), with respect to _{ZnO-B 2 O 3 (BZO} ) sintered body It has been found that the weather resistance can be improved by adding a specific impurity element.

  Hereinafter, the best mode for carrying out the present invention will be described.

The zinc oxide sintered body according to the embodiment of the present invention is a zinc oxide sintered body in which Al ₂ O ₃ , Ga ₂ O ₃ , or B ₂ O ₃ is added to ZnO, and improves weather resistance. As additive elements, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), One or more elements are added from among europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), erbium (Er), thulium (Tm), and ytterbium (Yb).

The zinc oxide sintered body according to the embodiment of the present invention is a zinc oxide sintered body (AZO) in which Al ₂ O ₃ is added to ZnO, and Ce is added as the additive element. Here, Ce is added in the form of its oxide, cerium oxide (CeO ₂ ).

Here, this AZO is manufactured by the manufacturing method described in Patent Document 1. That is, rather than blending and forming Al ₂ O ₃ powder and ZnO powder to obtain a sintered body, first, a calcined powder containing ZnAl ₂ O ₄ phase is produced, and this calcined powder and ZnO powder, CeO ₂ powders are blended, molded, and fired to form a zinc oxide sintered body.

In the calcined powder manufacturing process, first, the first ZnO powder and the Al ₂ O ₃ powder are blended and granulated, and then calcined in the air (calcined) to obtain a calcined powder. Next, the calcined powder is pulverized again to a desired particle size to produce a calcined powder. In this calcined powder, ZnAl ₂ O ₄ having a spinel structure, which is a composite compound of ZnO and Al ₂ O ₃ , is formed.

The 1st ZnO powder used here consists of ZnO of a wurtzite structure, and the BET specific surface area has preferable 2-30 m < ² > / g. The purity is preferably 99.9% or more.

The Al ₂ O ₃ powder is made of α-alumina type, β-alumina type, or θ-alumina type Al ₂ O ₃ , and the BET specific surface area is preferably ² to 100 m ² / g. In view of easy formation of ZnAl ₂ O ₄ , the α-alumina type is particularly preferable. The purity is preferably 99.9% or more.

The molar ratio of ZnO / Al ₂ O ₃ , which is the compounding ratio of the first ZnO powder and Al ₂ O ₃ powder, is preferably in the range of 1 to 200, particularly preferably 1 to 30. The powder after mixing is mixed with a ball mill, and after granulation, it is fired (pre-fired) at a temperature of 900 to 1300 ° C. to produce a calcined powder. This is the same as the technique described in Patent Document 1.

The pre-baking atmosphere is preferably a non-reducing atmosphere, and is preferably in the air or in an oxygen atmosphere. In the calcined powder, ZnAl ₂ O _4, which is a complex oxide having a spinel structure, is formed by a solid phase reaction of ZnO grains and Al ₂ O ₃ grains. The calcination time is preferably 1 to 5 hours. In the calcined powder, particles are bonded by sintering. This is again pulverized by a mechanical process such as a ball mill to obtain a calcined powder having a desired particle size (particle size). The BET specific surface area of the calcined powder is preferably ² to 30 m ² / g. In addition, as long as the BET specific surface area can be adjusted, a method other than the ball mill, for example, a method such as a vibration mill can be used in the same manner. When the calcined powder is in a fine powder state, this re-pulverization is unnecessary. The state of the calcined powder depends on the first ZnO powder / oxide powder ratio. In particular, when this ratio is large, the ZnO phase increases and the ZnO phase itself is further sintered to increase the size of the particles. Therefore, this particle size adjustment is necessary to make the BET specific surface area of the calcined powder within the above range. This is the same as the technique described in Patent Document 1.

In the main firing step, after obtaining the molded body obtained by blending and granulating the calcined powder obtained in the above step, the second ZnO powder, and the CeO ₂ powder, this is obtained in a non-reducing atmosphere, for example, The zinc oxide sintered body is produced by firing (main firing) in the air, in an oxygen atmosphere, or in an inert gas atmosphere such as nitrogen or argon. Here, this shape is formed into a desired shape, for example, the shape of a sputtering target.

Similar to the first ZnO powder, the second ZnO powder can be made of ZnO having a wurtzite structure and a BET specific surface area of ² to 30 cm ² / g. The purity is preferably 99.9% or more.

The CeO ₂ powder preferably has a BET specific surface area of ² to 30 m ² / g and a purity of 99.9% or more.

In blending the calcined powder, the second ZnO powder, and the CeO ₂ powder, it is preferable to add 1% by weight, for example, polyvinyl alcohol as a binder and perform mixing using a ball mill or the like. The slurry thus produced is dried and granulated and formed into a desired shape by a method such as pressing. The shape and size of the molded body are arbitrary, and as a target for a transparent electrode of a large-area liquid crystal display, a plate-like material having a size of, for example, 127 mm × 381 mm × 5 mm or more can be produced. By firing this molded body (main firing), a zinc oxide sintered body is obtained. The firing time is preferably 1 hour or longer. Incidentally, when the sintering temperature is of _{Al 2 O 3, Ga 2 O} 3 added to the (AZO, when the GZO), 1300 ° C. or higher 1600 ° C. or _less, B 2 _{O 3} when the addition (in the case of BZO) are 900 degreeC or more and 1400 degrees C or less are preferable.

When the calcined powder, the second ZnO powder, and the CeO ₂ powder are blended and mixed as described above, by adjusting the particle size of the pre-firing powder mixed with these, the compact can be fired (main firing). The state can be optimized. In this case, the BET specific surface area of the pre-firing powder is preferably 1 to 20 m ² / g.

By this manufacturing method, a dense zinc oxide sintered body without large pores and precipitates can be obtained. The reason for this is that, as described in Patent Document 1, the formation of vacancies is suppressed when the ZnAl ₂ O ₄ phase is formed in the main firing step.

Further, the Al concentration in this AZO sintered body is 0.1 to 10 wt% (wt%) in terms of oxide (Al ₂ O ₃ ), and the Ce concentration is 0.01 to ₂ wt in terms of oxide (CeO ₂ ). % Is preferable. In the electrode formed using this sintered body as a target, even when the film thickness is 200 nm or less, the initial resistivity is 10 ⁻³ Ω · cm or less, 1000 ° C. under a humidity of 90% RH at 60 ° C. The resistivity after time is suppressed to 10 times or less of the initial resistivity. That is, low resistivity and high weather resistance can be obtained.

The increase in resistivity of the electrode under high temperature and high humidity occurs when oxygen and water vapor in the atmosphere are combined with the film and the film is oxidized. Ce is present at the crystal grain boundary where Al, Ga, and B are substituted and dissolved in Zn to suppress the intrusion of oxygen and water vapor into the film, thereby improving the stability of the film and improving the weather resistance. Let However, when the addition amount of Ce becomes larger than the above range, the hole mobility is decreased, so that the initial resistivity is increased. In addition, when the Al addition amount is larger than the above range, the hole mobility is decreased due to the presence of Al that cannot be substituted and dissolved in Zn at the grain boundary, so that the initial resistivity increases.

FIG. 2 (a) is a photograph taken with an electron microscope after the cross section of this sintered body was mirror-polished when fired at 1500 ° C. with an Al concentration of 2 wt% and a Ce concentration of 2 wt%. As a result of analysis by SEM (Scanning Electron Microscope) -EDX (Energy Dispersive X-ray Analysis), the portion 1 occupying the majority in FIG. It was a dense structure. On the other hand, the scattered two portions were ZnAl ₂ O ₄ phase precipitates having a spinel structure. Further, the portion 3 of the precipitate that appears white in the figure was a CeO ₂ phase.

As a reference, FIG. 2B shows a similar observation result when CeO ₂ is not added. The dense ZnO phase 1 and the ZnAl ₂ O ₄ phase 2 dispersed therein are similarly formed. This result is as described in Patent Document 1.

From this result, it can be confirmed that the AZO sintered body of the present invention is a dense AZO sintered body in which the ZnAl ₂ O ₄ phase 2 and the CeO ₂ phase 3 are dispersed.

Note that the sinterability is affected by the addition concentration of Ce (CeO ₂ ). FIG. 3 shows the results of examining the CeO ₂ concentration dependence of the relative density of the sintered body when the Al ₂ O ₃ concentration is 2 wt% when the firing temperatures in the main firing step are 1400 ° C. and 1500 ° C. Here, the relative density is assumed when a desired element is present as an oxide in a predetermined amount of ZnO, and the density calculated using the theoretical density and addition amount of each oxide is defined as the theoretical density. The ratio of sintered body density is shown. When the firing temperature is 1400 ° C. and 1500 ° C., a sintered body having a high density of 98% or more is obtained, and when the firing temperature is 1500 ° C., a density as high as 99.5% is obtained. As described above, the sintering temperature can be in the range of 1300 to 1600 ° C.

Further, an X-ray diffraction pattern of AZO sintered by CeO ₂ added to FIG. Here, (a) shows the case where CeO _{2 is} not added, (b) shows the case where CeO ₂ is added at 0.5 wt%, and (c) shows the case where CeO ₂ is added at 2 wt%. In any case, the firing temperature in the main firing step is 1500 ° C. In the figure, although material name corresponding to each peak is described, a peak corresponding to the CeO ₂ is increased with increasing CeO ₂ composition, the other peaks (ZnO, ZnAl ₂ O ₄₎ Is not affected. Therefore, regardless of the presence or absence of CeO ₂ , this AZO sintered body has a dense structure similar to that described in Patent Document 1. The light transmittance did not depend on the CeO ₂ addition amount and was good in any case.

Next, this sintered body is actually set in a sputtering apparatus as a sputtering target, and by sputtering (sputtering method: DC magnetron, sputtering gas: Ar, gas pressure: 0.5 Pa, magnetic flux density: 1000 Gauss, time: 1 hour) Electrode deposition was performed on a Corning # 1737 glass substrate. FIG. 5 shows the film thickness dependence of the electrical resistivity of this electrode when Al ₂ O ₃ is 2 wt% and CeO ₂ is 0.5 wt%. Even with a film thickness of 200 nm or less, the resistivity can be 10 ⁻³ Ω · cm or less, and it can be preferably used as a transparent electrode.

Further, as the weather resistance of this electrode, a change in resistivity was measured when exposed to a humidity of 90% RH at 60 ° C. When using the same sputtering target as described above (a) when the film thickness is 200 nm, (b) when the film thickness is 100 nm, and (c) when there is no addition of CeO ₂ and the film thickness is 100 nm, The measurement results for the three types are shown in FIG. The initial value is about 6 to 7 × 10 ⁻⁴ Ω · cm, which is sufficiently small. However, when CeO ₂ is not added (c), the resistivity gradually increases, and after 200 hours, 20 Ω · It rises to more than cm. On the other hand, in the case of (a) and (b) to which CeO ₂ was added, the increase was greatly suppressed. Especially when the film thickness was 200 nm, it was 10 ⁻³ Ω · cm or less even after 1000 hours. A small resistivity is maintained.

From the above, it was confirmed that an electrode having high weather resistance can be obtained by using a sputtering target obtained by adding Ce (CeO ₂ ) to AZO. Similar effects can be obtained by adding Mg, Ca, Sr, Ba, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb instead of Ce. In addition to AZO, GZO and BZO, which are zinc oxides imparted with conductivity by adding Ga ₂ O ₃ and B ₂ O ₃ to ZnO, can be added by adding these elements. High weather resistance is obtained. In this case, instead of the ZnAl ₂ O ₄ phase, a ZnGa ₂ O ₄ phase and a ZnB ₂ O ₄ phase are formed. The same applies when Al, Ga, and B are mixed and added.

In the above embodiment, when manufacturing the zinc oxide ceramics, of using a calcined powder containing the ZnAl ₂ O _4, especially the method described in Patent Document 1, a dense sintered body is obtained Although used, it is not limited to this. It is clear that the same effect can be obtained even by using a method of mixing, forming and firing powders such as ZnO, Al ₂ O ₃ and CeO ₂ .

Similarly, a powder mainly composed of a composite compound such as ZnAl ₂ O ₄ produced by a process other than the calcined powder production process is mixed with ZnO powder, CeO ₂ powder, etc. in the main firing process, and then molded and fired. A method may be used. The mixing method and the molding method are also arbitrary.

  Examples of the present invention will be described below.

(Examples 1-16, Comparative Examples 1-4)
First, the above additive elements were added as oxides to zinc oxide (AZO) to which Al ₂ O ₃ was added, and sintered bodies (Examples 1 to 16) manufactured by the manufacturing method of FIG. 1 were sputtered. The electrode was formed in the same manner as described above. The initial resistivity of this electrode and the resistivity after 1000 hours had passed under the conditions of 60 ° C. and 90% RH were measured, and the rate of change (increase rate) was determined. Similarly, in Comparative Example 1, an electrode using AZO without the addition of the above additive elements, in Comparative Example 2, when the amount of CeO ₂ added is increased, and in Comparative Example 3, the Al composition is increased. It was measured. Al ₂ O ₃ addition amount, additive (oxide of additive element), addition amount, relative density of sintered body, electrode film thickness, initial resistivity, resistance after 200 hours in each example and comparative example The increase rate (times) is shown in Table 1.

In Examples 1 to 16 to which Mg, Ca, Sr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were added, the initial resistivity was 10 ⁻³ Ω. -It was cm or less, and the rate of change in resistivity after 1000 hours was as good as 10 or less. That is, a low resistivity and a small resistance change rate were obtained. In particular, although the film thickness is 200 nm or less, which is significantly thinner than that described in Patent Document 2, these favorable values are obtained.

On the other hand, in Comparative Example 1 in which the additive element was not added, the resistance change rate was large. In Comparative Example 2 where the CeO ₂ addition amount is as large as 4 wt% and Comparative Example 3 where the Al ₂ O ₃ addition amount is as large as 11%, although the resistance change rate is small, the initial resistivity exceeds 10 ⁻³ Ω · cm. It was.

From the above, the target is a sintered body in which the addition amount of Al ₂ O ₃ is 0.1 to 10 wt% and the addition amount of the additive element is 0.01 to ₂ wt% in terms of oxide. When an electrode having a thickness of 65 nm or more was formed, the initial resistivity could be 10 ⁻³ Ω · cm or less, and the change rate of the resistivity after 1000 hours could be 10 times or less.

(Examples 17 to 32, Comparative Examples 4 to 6)
The same measurement was performed on zinc oxide (GZO) to which Ga ₂ O ₃ was added. Further, in Comparative Example 4, measurement was performed with respect to an electrode using GZO without addition of the above additive elements, Comparative Example 5 with an increase in the amount of Dy ₂ O ₃ added, and Comparative Example 6 with a high Ga composition. . These results are shown in Table 2 in the same manner as described above.

In Examples 17 to 32 to which Mg, Ca, Sr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were added, the initial resistivity was 10 ⁻³ Ω. -It was cm or less, and the rate of change in resistivity after 1000 hours was as good as 10 times or less. That is, a low resistivity and a small resistance change rate were obtained.

On the other hand, in Comparative Example 4 in which the additive element was not added, the resistance change rate was large. In Comparative Example 5 where the Dy ₂ O ₃ addition amount is as large as 4 wt% and Comparative Example 6 where the Ga ₂ O ₃ addition amount is as large as 16.5%, although the resistance change rate is small, the initial resistivity is 10 ⁻³ Ω · cm. Exceeded.

From the above, the target is a sintered body in which the addition amount of Ga ₂ O ₃ is 0.1 to 10 wt% and the addition amount of the additive element is 0.01 to ₂ wt% in terms of oxide. When an electrode having a film thickness of 200 nm or less was used, the initial resistivity could be 10 ⁻³ Ω · cm or less, and the rate of change in resistivity after 1000 hours could be 10 times or less.

(Examples 33 to 48, Comparative Examples 7 to 9)
A similar measurement was performed on BZO to which B ₂ O ₃ was added. In Comparative Example 7, measurement was performed with respect to an electrode using BZO without addition of the above additive elements, Comparative Example 8 with an increased amount of CeO ₂ , and Comparative Example 9 with a higher B composition. These results are shown in Table 3 in the same manner as described above.

In Examples 33 to 48 to which Mg, Ca, Sr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were added, the initial resistivity was 10 ⁻³ Ω. -It was cm or less, and the rate of change in resistivity after 1000 hours was as good as 10 times or less. That is, a low resistivity and a small resistance change rate were obtained.

On the other hand, in Comparative Example 7 where the additive element was not added, the resistance change rate was large. In Comparative Example 8 where the CeO ₂ addition amount was as large as 4 wt% and Comparative Example 9 where the B ₂ O ₃ addition amount was as large as 11%, the resistance change rate was small, but the initial resistivity exceeded 10 ⁻³ Ω · cm.

From the above, the target is a sintered body in which the addition amount of B ₂ O ₃ is 0.1 to 10 wt% and the addition amount of the additive element is 0.01 to ₂ wt% in terms of oxide. When an electrode having a film thickness of 200 nm or less was used, the initial resistivity could be 10 ⁻³ Ω · cm or less, and the rate of change in resistivity after 1000 hours could be 10 times or less.

(Examples 49 to 57)
The same measurement was performed for a case where a plurality of Al ₂ O ₃ , Ga ₂ O ₃ , and B ₂ O ₃ were simultaneously added (Examples 49 to 57). These results are shown in Table 4 in the same manner as described above.

From this result, it was confirmed that even when Al, Ga, and B are mixed, the same effect can be obtained when the above additive element is added. In this case, the total of these oxide conversions is set to 0.1 to 15%, and a sintered body added in the range of 0.01 to 2 wt% of the above-described additive elements in terms of oxide is used as a target. When an electrode having a film thickness of 200 nm or less was formed, the initial resistivity was 10 ⁻³ Ω · cm or less, and the rate of change in resistivity after 1000 hours could be 10 times or less.

It is process drawing which shows the manufacturing method of the zinc oxide sintered compact of embodiment of this invention. Electron micrograph of a cross section of a zinc oxide sintered body (AZO) (a: CeO ₂ Yes addition, b: Additives None element) is. The results of measuring the CeO ₂ amount dependency of the relative density of the sintered body. Dependence of measured X-ray diffraction pattern on CeO ₂ addition amount (a: no addition, b: 0.5 wt%, c: 2 wt%). This is the film thickness dependence of the resistivity of an electrode formed using a sintered sputtering target to which 2 wt% of Al ₂ O _{3 and} 0.5 wt% of CeO ₂ are added. Results of measuring changes in resistivity of formed electrode under high temperature and high humidity (a: CeO ₂ 0.5 wt% added, film thickness 200 nm, b: CeO ₂ 0.5 wt% added, film thickness 100 nm, c : CeO ₂ not added, film thickness 100 nm).

Explanation of symbols

1 ZnO phase 2 ZnAl ₂ O ₄ phase 3 CeO ₂ phase

Claims (13)

A zinc oxide sintered body containing Al in ZnO,
One or more of Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb are added as additive elements. A zinc oxide sintered body characterized in that 0.1 to 10 wt% in terms of oxide and the amount of additive element added is in the range of 0.01 to 2 wt% in terms of oxide. _{2. The} zinc oxide sintered body according to claim 1, wherein a ZnAl ₂ O ₄ phase and an oxide phase of the additive element are dispersed in the ZnO phase. 3. A zinc oxide sintered body containing Ga in ZnO,
One or more of Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb are added as additive elements. A zinc oxide sintered body characterized in that 0.1 to 10 wt% in terms of oxide and the amount of additive element added is in the range of 0.01 to 2 wt% in terms of oxide. The zinc oxide sintered body according to claim 3, wherein a ZnGa ₂ O ₄ phase and an oxide phase of the additive element are dispersed in the ZnO phase. A zinc oxide sintered body containing B in ZnO,
One or more of Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb are added as additive elements. A zinc oxide sintered body characterized in that 0.1 to 10 wt% in terms of oxide and the amount of additive element added is in the range of 0.01 to 2 wt% in terms of oxide. The zinc oxide sintered body according to claim 5, wherein a ZnB ₂ O ₄ phase and an oxide phase of the additive element are dispersed in the ZnO phase. A zinc oxide sintered body containing two or more of Al, Ga and B in ZnO,
One or more of Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb are added as additive elements, and the Al, Ga, A zinc oxide sintered body characterized in that the total amount of B in terms of oxide is 0.1 to 15 wt%, and the amount of the additive element added is in the range of 0.01 to 2 wt% in terms of oxide. A composite oxide phase composed of two or more of ZnAl ₂ O ₄ phase, ZnGa ₂ O ₄ phase, and ZnB ₂ O ₄ phase is dispersed in ZnO, and the oxide phase of the additive element is dispersed The zinc oxide sintered body according to claim 7, wherein: ZnO contains at least one of Al, Ga, B and Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb A method for producing a zinc oxide sintered body in which one or more of them are added as additive elements,
A calcined powder in which a powder composed of one or more oxides of Al, Ga and B and a first ZnO powder are blended and fired at a temperature in the range of 900 to 1300 ° C. to produce a calcined powder. Powder manufacturing process;
A main firing step of obtaining a zinc oxide sintered body by firing a compact formed by blending the calcined powder, the second ZnO powder, and the oxide of the additive element;
The manufacturing method of the zinc oxide sintered compact characterized by comprising.   The method for producing a zinc oxide sintered body according to claim 9, wherein firing in the calcined powder production step is performed in a non-reducing atmosphere. ZnO contains at least one of Al, Ga, B and Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb A method for producing a zinc oxide sintered body in which one or more of them are added as additive elements,
A molded body in which a molded body is formed by blending a powder mainly containing any one or more of ZnAl ₂ O ₄ , ZnGa ₂ O ₄ , and ZnB ₂ O ₄ , a ZnO powder, and an oxide of the additive element. A method for producing a zinc oxide sintered body, comprising a main firing step of obtaining a zinc oxide sintered body by firing the material.   A sputtering target comprising the zinc oxide sintered body according to any one of claims 1 to 8.   An electrode formed using the sputtering target according to claim 12 to a thickness of 200 nm or less by a sputtering method.