JP4076265B2 - Zinc oxide sintered compact sputtering target and manufacturing method thereof - Google Patents
Zinc oxide sintered compact sputtering target and manufacturing method thereof Download PDFInfo
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- JP4076265B2 JP4076265B2 JP08731498A JP8731498A JP4076265B2 JP 4076265 B2 JP4076265 B2 JP 4076265B2 JP 08731498 A JP08731498 A JP 08731498A JP 8731498 A JP8731498 A JP 8731498A JP 4076265 B2 JP4076265 B2 JP 4076265B2
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- zinc oxide
- sputtering target
- sintered body
- oxide sintered
- heat treatment
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Description
【０００１】
【発明の属する技術分野】
本発明は、導電性金属酸化物焼結体、特に酸化亜鉛焼結体スパッタリングターゲットおよびその製造方法に関する。
【０００２】
【従来の技術】
最近、太陽電池やディスプレイ機器の透明電極や帯電防止用の導電性コーティングとして透明導電性金属酸化物薄膜の需要が増大している。この導電性金属酸化物の透明導電性薄膜は、主に金属酸化物の焼結体をスパッタリングターゲットとして用いたスパッタリング法で形成されている。また、金属酸化物材料としては、ＩＴＯ（酸化インジュウム・酸化錫）や酸化亜鉛が使用されている。
【０００３】
酸化亜鉛（ＺｎＯ）は、安価であり、かつ化学的にも安定しており、透明性、導電性の点でも優れているため透明導電膜材料として適当である。しかし、酸化亜鉛の焼結体は、平面研磨などの加工を施すと、研磨面の電気抵抗が高くなるという問題点を有している。
【０００４】
一般的に表面の電気抵抗が高く、内部の抵抗が低い焼結体をスパッタリングターゲットとして使用した場合、スパッタリング初期において、スパッタリング面に抵抗の高い部分（まだスパッタリングされていない所）と、抵抗の低い部分（表面が少しスパッタリングされた所）が混在するためスパッタリングが安定せず、良質の膜を得ることができない。また、バッキングプレートとの電気的接触も悪く、スパッタリングが安定しない恐れがある。このため、これらの問題点を取り除くことが望まれている。
【０００５】
【発明が解決しようとする課題】
本発明は、酸化亜鉛の焼結体を研磨加工した際に増大する表面の電気抵抗を効果的に低下させた酸化亜鉛スパッタリングターゲットを提供することを目的としている。
【０００６】
【課題を解決するための手段】
本発明者らは、酸化亜鉛焼結体からなるスパッタリングターゲット材に研磨などの加工処理を施した際に生ずる研磨面の表面の電気抵抗の増加を是正するためには、このターゲット材に適当な温度で熱処理を施すと効果があることを見い出し、本発明を完成するに至った。
【０００７】
本発明は、下記の事項をその特徴としている。
（１） 酸化亜鉛焼結体からなるスパッタリングターゲットであって、その表面のシート抵抗が３．００×１０4 Ω／□以下であることを特徴とする酸化亜鉛スパッタリングターゲット。
（２） 酸化亜鉛焼結体からなるスパッタリングターゲットであって、４００〜１４００℃の温度で３０分〜５時間熱処理され、その表面のシート抵抗が３．００×１０4 Ω／□以下であることを特徴とする酸化亜鉛スパッタリングターゲット。
（３） 酸化亜鉛（ＺｎＯ）粉末を成型し、次いで焼成し、得られた酸化亜鉛焼結体スパッタリングターゲット材の表面を研磨加工し、しかる後この材料を熱処理することを特徴とする酸化亜鉛スパッタリングターゲットの製造方法。
（４） 研磨加工した酸化亜鉛焼結体スパッタリングターゲット材の熱処理が、４００〜１４００℃の温度で３０分〜５時間である前記（３）に記載の製造方法。
【０００８】
以下に、本発明を詳細に説明する。
まず、本発明の酸化亜鉛焼結体スパッタリングターゲット材の熱処理条件について述べる。
【０００９】
熱処理温度が４００℃未満では酸化亜鉛焼結体の表面の電気抵抗を低下させる効果が十分でなく、１４００℃より高温では酸化亜鉛焼結体が多少変形してしまう。スパッタリングターゲット材として所定の形状から変形したものを使用すると、バッキングプレート（平面形状のもの）とうまく張り合わせることが出来なかったり、スパッタリングにおいてアースシールドなどからの距離が一定にならないので異常放電の原因となり、スパッタリングターゲット材として好ましくない。
【００１０】
また、熱処理時間が３０分未満では酸化亜鉛焼結体の表面の電気抵抗を低下させる効果が十分でなく、５時間より長時間では酸化亜鉛焼結体が変形してしまう恐れがある。そこで、熱処理温度を４００〜１４００℃とし、保持時間を３０分〜５時間とした。
【００１１】
熱処理を行う雰囲気としては、大気中、真空中、不活性ガス中等の雰囲気が適用できる。
【００１２】
本発明においてシート抵抗とは、Loresta HP MGP-T410 （三菱化学株式会社製）のシート抵抗測定モードを用いて測定した値である。
【００１３】
酸化亜鉛焼結体を研磨加工すると、表面の電気抵抗が増大する理由は定かではないが、酸化亜鉛焼結体の表面にひずみが形成され、このひずみが表面の電気抵抗を増大させる原因であると推定される。この表面に形成されたひずみは、熱処理することにより取り除くことができ、その結果、表面の電気抵抗が低減されると考えられる。従って、本発明は純粋な酸化亜鉛焼結体だけでなく、酸化亜鉛を主成分とする焼結体スパッタリングターゲット材全般（ただし、酸化アルミニウムを含有するものを除く）に効果があるものと考えられる。また、表面に形成されたひずみを化学的に溶かすなどの方法も有効であると考えられるが、溶解に酸などを用いる場合には、焼結体に用いた酸が残留する恐れがあり、そのような酸の残留した焼結体をスパッタリングターゲットに用いると膜質に悪影響があるので好ましくない。
【００１４】
【発明の実施の形態】
以下に、本発明を実施例によりさらに説明する。
酸化亜鉛の粉末にプレス助剤としてＰＶＡ（ポリビニルアルコール）を添加した後、５００kgf ／cm2 の圧力でプレス成型し、大気雰囲気中で１３５０℃で３時間保持し、酸化亜鉛焼結体を得た。得られた酸化亜鉛焼結体をφ１０１．６×５mm厚のサイズで切り出し、表面を研磨加工し、これを各温度で熱処理した。熱処理条件は、各熱処理温度まで１００℃／時間で昇温し、３時間保持した後、常温まで１００℃／時間で降温した。
【００１５】
酸化亜鉛の焼結体の表面抵抗をLoresta HP MGP-T410 （三菱化学株式会社製）シート抵抗測定モードを用いて測定し、その後、ＤＣスパッタ法にて製膜試験を行った。表１に酸化亜鉛焼結体の熱処理温度におけるシート抵抗、焼結体の変形度およびＤＣスパッタ法による製膜状態を示す。
なお、表１に示す熱処理による焼結体の変形において、○は０．１mm未満の変形を表し、×は０．１mm以上の変形を表す。また、同じくＤＣスパッタリング法による製膜状態において、○はＤＣスパッタリング可能、△はＤＣスパッタリング不安定、×はＤＣスパッタリング不可を示す。
【００１６】
【表１】
また、図１に酸化亜鉛焼結体の熱処理温度とシート抵抗の関係を示す。
【００１８】
表１、図１に示すシート抵抗の測定結果から分かるように、研磨加工された酸化亜鉛焼結体の熱処理温度が４００℃以上になるとシート抵抗値は未熱処理の酸化亜鉛焼結体の約１／１０まで低下し、熱処理の効果が現れていることが分かる。さらに、熱処理の温度が高いほど、シート抵抗値は小さくなり、その効果が大きくなることが分かる。
【００１９】
また、未加工の焼結体のシート抵抗は５．６５Ω／□であり、処理温度が高くなるほど、この未加工時のシート抵抗値に近づいていくことから、研磨加工によるひずみが緩和されていることが分かる。１４５０℃の熱処理ではシート抵抗が５．６５Ω／□以下であるが、これは、１４５０℃の熱処理により酸化亜鉛焼結体の結晶粒が成長し、酸化亜鉛焼結体自体の抵抗が下がるためであると考えられる。
【００２０】
また、４００℃〜１４５０℃の温度で３０分〜５時間の熱処理を施し、表面抵抗を下げた酸化亜鉛焼結体をさらに研磨加工を施すと、再びシート抵抗は１０5 Ω／□オーダーまで増大する。
【００２１】
また、ＤＣスパッタ法による成膜試験においても、シート抵抗が３．００×１０4 Ω／□以下であれば良好に成膜できることが分かる。
【００２２】
【発明の効果】
本発明によれば、研磨加工した酸化亜鉛焼結体スパッタリングターゲット材を熱処理することによりその表面の電気抵抗を低下させることが可能となるので、スパッタリングが安定し、良質の膜を得ることができる。
【図面の簡単な説明】
【図１】本発明の酸化亜鉛焼結体のシート抵抗と熱処理温度との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive metal oxide sintered body, in particular, a zinc oxide sintered body sputtering target and a method for producing the same.
[0002]
[Prior art]
Recently, there is an increasing demand for transparent conductive metal oxide thin films as transparent electrodes for solar cells and display devices and conductive coatings for preventing static electricity. This conductive metal oxide transparent conductive thin film is mainly formed by a sputtering method using a sintered metal oxide as a sputtering target. In addition, ITO (indium oxide / tin oxide) or zinc oxide is used as the metal oxide material.
[0003]
Zinc oxide (ZnO) is suitable as a transparent conductive film material because it is inexpensive, chemically stable, and excellent in transparency and conductivity. However, the sintered body of zinc oxide has a problem that the electrical resistance of the polished surface becomes high when processing such as planar polishing is performed.
[0004]
In general, when a sintered body having a high surface electrical resistance and a low internal resistance is used as a sputtering target, at the initial stage of sputtering, a portion having a high resistance on the sputtering surface (a portion not yet sputtered) and a low resistance are used. Since the portion (where the surface is slightly sputtered) is mixed, sputtering is not stable, and a high-quality film cannot be obtained. In addition, electrical contact with the backing plate is poor, and sputtering may not be stable. For this reason, it is desired to remove these problems.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a zinc oxide sputtering target that effectively reduces the electrical resistance of the surface that increases when a sintered body of zinc oxide is polished.
[0006]
[Means for Solving the Problems]
In order to correct the increase in the electrical resistance of the surface of the polishing surface that occurs when the sputtering target material made of a zinc oxide sintered body is subjected to processing such as polishing, the present inventors are suitable for this target material. It has been found that there is an effect when heat treatment is performed at a temperature, and the present invention has been completed.
[0007]
The present invention has the following features.
(1) A zinc oxide sputtering target comprising a zinc oxide sintered body and having a surface sheet resistance of 3.00 × 10 4 Ω / □ or less.
(2) A sputtering target composed of a zinc oxide sintered body, heat-treated at a temperature of 400 to 1400 ° C. for 30 minutes to 5 hours, and having a surface sheet resistance of 3.00 × 10 4 Ω / □ or less. A zinc oxide sputtering target.
(3) Zinc oxide sputtering characterized in that zinc oxide (ZnO) powder is molded, then fired, the surface of the obtained zinc oxide sintered compact sputtering target material is polished, and then the material is heat-treated. Target manufacturing method.
(4) The manufacturing method according to (3), wherein the heat treatment of the polished zinc oxide sintered sputtering target material is performed at a temperature of 400 to 1400 ° C. for 30 minutes to 5 hours.
[0008]
The present invention is described in detail below.
First, heat treatment conditions for the zinc oxide sintered sputtering target material of the present invention will be described.
[0009]
If the heat treatment temperature is less than 400 ° C., the effect of reducing the electrical resistance of the surface of the zinc oxide sintered body is not sufficient, and if it is higher than 1400 ° C., the zinc oxide sintered body is somewhat deformed. If a material deformed from the specified shape is used as the sputtering target material, it will not adhere well to the backing plate (planar shape), or the distance from the ground shield will not be constant during sputtering, causing abnormal discharge. Therefore, it is not preferable as a sputtering target material.
[0010]
In addition, if the heat treatment time is less than 30 minutes, the effect of reducing the electrical resistance of the surface of the zinc oxide sintered body is not sufficient, and if it is longer than 5 hours, the zinc oxide sintered body may be deformed. Therefore, the heat treatment temperature was 400 to 1400 ° C., and the holding time was 30 minutes to 5 hours.
[0011]
As an atmosphere for the heat treatment, an atmosphere such as air, vacuum, or inert gas can be applied.
[0012]
In the present invention, the sheet resistance is a value measured using the sheet resistance measurement mode of Loresta HP MGP-T410 (manufactured by Mitsubishi Chemical Corporation).
[0013]
Although the reason why the electrical resistance of the surface increases when the zinc oxide sintered body is polished is not clear, strain is formed on the surface of the zinc oxide sintered body, and this strain increases the electrical resistance of the surface. It is estimated to be. The strain formed on the surface can be removed by heat treatment, and as a result, the electrical resistance of the surface is considered to be reduced. Therefore, the present invention is considered to be effective not only for pure zinc oxide sintered bodies but also for all sintered sputtering target materials mainly containing zinc oxide (except for those containing aluminum oxide). . In addition, it is considered effective to chemically dissolve the strain formed on the surface. However, when acid or the like is used for dissolution, there is a risk that the acid used in the sintered body may remain. Use of a sintered body having such an acid remaining as a sputtering target is not preferable because the film quality is adversely affected.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention is further illustrated by examples.
After adding PVA (polyvinyl alcohol) as a pressing aid to the zinc oxide powder, it was press-molded at a pressure of 500 kgf / cm 2 and held at 1350 ° C. for 3 hours in an air atmosphere to obtain a zinc oxide sintered body. . The obtained zinc oxide sintered body was cut out in a size of φ101.6 × 5 mm, the surface was polished, and this was heat-treated at each temperature. The heat treatment condition was that the temperature was raised to 100 ° C./hour up to each heat treatment temperature, held for 3 hours, and then lowered to room temperature at 100 ° C./hour.
[0015]
The surface resistance of the sintered body of zinc oxide was measured using a Loresta HP MGP-T410 (Mitsubishi Chemical Corporation) sheet resistance measurement mode, and then a film formation test was performed by a DC sputtering method. Table 1 shows the sheet resistance at the heat treatment temperature of the zinc oxide sintered body, the degree of deformation of the sintered body, and the state of film formation by the DC sputtering method.
In addition, in the deformation | transformation of the sintered compact by the heat processing shown in Table 1, (circle) represents a deformation | transformation of less than 0.1 mm and x represents a deformation | transformation of 0.1 mm or more. Similarly, in the film formation state by the DC sputtering method, ◯ indicates that DC sputtering is possible, Δ indicates that DC sputtering is unstable, and × indicates that DC sputtering is not possible.
[0016]
[Table 1]
FIG. 1 shows the relationship between the heat treatment temperature of the zinc oxide sintered body and the sheet resistance.
[0018]
As can be seen from the measurement results of the sheet resistance shown in Table 1 and FIG. 1, when the heat treatment temperature of the polished zinc oxide sintered body is 400 ° C. or higher, the sheet resistance value is about 1 of that of the unheated zinc oxide sintered body. It can be seen that the effect of heat treatment appears. Further, it can be seen that the higher the temperature of the heat treatment, the smaller the sheet resistance value and the greater the effect.
[0019]
Further, the sheet resistance of the green sintered body is 5.65Ω / □, and the higher the processing temperature, the closer to the sheet resistance value at the time of the green processing, so that the strain due to the polishing is alleviated. I understand that. In the heat treatment at 1450 ° C., the sheet resistance is 5.65Ω / □ or less, because the crystal grain of the zinc oxide sintered body grows by the heat treatment at 1450 ° C. and the resistance of the zinc oxide sintered body itself decreases. It is believed that there is.
[0020]
Further, when a zinc oxide sintered body having a reduced surface resistance is subjected to a heat treatment at a temperature of 400 ° C. to 1450 ° C. for 30 minutes to 5 hours and further subjected to polishing, the sheet resistance again increases to the order of 10 5 Ω / □. To do.
[0021]
Also in the film formation test by the DC sputtering method, it can be seen that the film can be satisfactorily formed if the sheet resistance is 3.00 × 10 4 Ω / □ or less.
[0022]
【The invention's effect】
According to the present invention, it is possible to reduce the surface electrical resistance by heat-treating a polished zinc oxide sintered sputtering target material, so that sputtering is stable and a high-quality film can be obtained. .
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between sheet resistance and heat treatment temperature of a zinc oxide sintered body of the present invention.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08731498A JP4076265B2 (en) | 1998-03-31 | 1998-03-31 | Zinc oxide sintered compact sputtering target and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08731498A JP4076265B2 (en) | 1998-03-31 | 1998-03-31 | Zinc oxide sintered compact sputtering target and manufacturing method thereof |
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| Publication Number | Publication Date |
|---|---|
| JPH11279755A JPH11279755A (en) | 1999-10-12 |
| JP4076265B2 true JP4076265B2 (en) | 2008-04-16 |
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| KR100888146B1 (en) * | 2003-09-30 | 2009-03-13 | 닛코킨조쿠 가부시키가이샤 | High purity zinc oxide powder and method for production thereof, and high purity zinc oxide target and thin film of high purity zinc oxide |
| WO2011058882A1 (en) * | 2009-11-13 | 2011-05-19 | Semiconductor Energy Laboratory Co., Ltd. | Sputtering target and manufacturing method thereof, and transistor |
| JP5549918B2 (en) * | 2009-11-25 | 2014-07-16 | 三菱マテリアル株式会社 | Zn sputtering target for DC sputtering and manufacturing method thereof |
| JP6058562B2 (en) * | 2012-01-30 | 2017-01-11 | 日本碍子株式会社 | Zinc oxide sputtering target and method for producing the same |
| DE102014118487A1 (en) * | 2014-12-12 | 2016-06-16 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for depositing a transparent multi-layer system with scratch-resistant properties |
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| JPH11279755A (en) | 1999-10-12 |
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