JP5337224B2 - Oxide sintered body, sputtering target, and manufacturing method thereof - Google Patents

Oxide sintered body, sputtering target, and manufacturing method thereof Download PDF

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JP5337224B2
JP5337224B2 JP2011242891A JP2011242891A JP5337224B2 JP 5337224 B2 JP5337224 B2 JP 5337224B2 JP 2011242891 A JP2011242891 A JP 2011242891A JP 2011242891 A JP2011242891 A JP 2011242891A JP 5337224 B2 JP5337224 B2 JP 5337224B2
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oxide
sintered body
sintering
zno
oxide sintered
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JP2013095655A (en
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英雄 畠
幸樹 田尾
守賀 金丸
旭 南部
祐紀 岩崎
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Kobelco Research Institute Inc
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Description

本発明は、液晶ディスプレイや有機ＥＬディスプレイなどの表示装置に用いられる薄膜トランジスタ（ＴＦＴ）の酸化物半導体薄膜をスパッタリング法で成膜するときに用いられる酸化物焼結体およびスパッタリングターゲット、並びにその製造方法に関するものである。   The present invention relates to an oxide sintered body and a sputtering target used when a thin film transistor (TFT) oxide semiconductor thin film used in a display device such as a liquid crystal display or an organic EL display is formed by a sputtering method, and a method for manufacturing the oxide sintered body. It is about.

ＴＦＴに用いられるアモルファス（非晶質）酸化物半導体は、汎用のアモルファスシリコン（ａ−Ｓｉ）に比べて高いキャリア移動度を有し、光学バンドギャップが大きく、低温で成膜できるため、大型・高解像度・高速駆動が要求される次世代ディスプレイや、耐熱性の低い樹脂基板などへの適用が期待されている。これらの用途に好適な酸化物半導体の組成として、例えばＩｎ含有の非晶質酸化物半導体［Ｉｎ−Ｇａ−Ｚｎ−Ｏ、Ｉｎ−Ｚｎ−Ｏ、Ｉｎ−Ｓｎ−Ｏ（ＩＴＯ）など］が提案されている。   Amorphous (amorphous) oxide semiconductors used for TFTs have higher carrier mobility than general-purpose amorphous silicon (a-Si), a large optical band gap, and can be formed at low temperatures. It is expected to be applied to next-generation displays that require high resolution and high-speed driving, and resin substrates with low heat resistance. As an oxide semiconductor composition suitable for these uses, for example, an In-containing amorphous oxide semiconductor [In-Ga-Zn-O, In-Zn-O, In-Sn-O (ITO), etc.] is proposed. Has been.

上記酸化物半導体（膜）の形成に当たっては、当該膜と同じ材料のスパッタリングターゲットをスパッタリングするスパッタリング法が好適に用いられている。スパッタリング法では、製品である薄膜の特性の安定化、製造の効率化のために、スパッタリング中の異常放電の防止、ターゲットの割れ防止などが重要であり、様々な技術が提案されている。   In forming the oxide semiconductor (film), a sputtering method is preferably used in which a sputtering target made of the same material as the film is sputtered. In the sputtering method, prevention of abnormal discharge during sputtering and prevention of cracking of the target are important in order to stabilize the characteristics of the thin film as a product and increase the efficiency of production, and various techniques have been proposed.

例えば特許文献１には、ＩＴＯターゲットについて、結晶粒の平均粒径を微細化することによって異常放電を抑制する技術が提案されている。   For example, Patent Document 1 proposes a technique for suppressing abnormal discharge for an ITO target by reducing the average grain size of crystal grains.

また特許文献２には、ＩＴＯターゲットについて、焼結密度を高めると共に、結晶粒径を微細化することによって、スパッタリング中のターゲット板の割れを防止する技術が提案されている。   Patent Document 2 proposes a technique for preventing cracking of the target plate during sputtering by increasing the sintering density and reducing the crystal grain size for the ITO target.

更に特許文献３には、Ｉｎ−Ｚｎ−Ｏ系の複合酸化物を焼結後に還元雰囲気中でアニーリング処理することによって、ターゲット材料の導電率を向上させ、スパッタリング中の異常放電やターゲットの割れを抑制する技術が提案されている。   Furthermore, in Patent Document 3, the In-Zn-O-based composite oxide is annealed in a reducing atmosphere after sintering, thereby improving the electrical conductivity of the target material, thereby preventing abnormal discharge and sputtering of the target during sputtering. Suppression techniques have been proposed.

近年の表示装置の高性能化に伴って、酸化物半導体薄膜の特性の向上や特性の安定化が要求されていると共に、表示装置の生産を一層効率化することが求められている。そのため、表示装置用酸化物半導体膜の製造に用いられるスパッタリングターゲットおよびその素材である酸化物焼結体は、導電性に優れ、且つ高い相対密度を有することが望まれている。また上記スパッタリングターゲットを用いて得られる酸化物半導体膜は、高いキャリア移動度を有することが望まれている。更に生産性や製造コストなどを考慮すると、スパッタリング工程での異常放電（アーキング）をより一層抑制することも重要であり、そのためにはターゲット材料およびその素材となる酸化物焼結体の改善が求められている。   Along with the recent improvement in performance of display devices, there is a demand for improvement and stabilization of characteristics of oxide semiconductor thin films, and there is a demand for more efficient production of display devices. Therefore, it is desired that a sputtering target used for manufacturing an oxide semiconductor film for a display device and an oxide sintered body that is a material thereof have excellent conductivity and a high relative density. An oxide semiconductor film obtained using the above sputtering target is desired to have high carrier mobility. Furthermore, considering productivity and manufacturing costs, it is also important to further suppress abnormal discharge (arcing) in the sputtering process. To that end, improvement of the target material and the oxide sintered body that is the material is required. It has been.

特開平７−２４３０３６号公報Japanese Patent Laid-Open No. 7-243036 特開平５−３１１４２８号公報JP-A-5-311428 特許第３７４６０９４号公報Japanese Patent No. 3746094

本発明は上記事情に鑑みてなされたものであり、その目的は、表示装置用酸化物半導体膜の製造に好適に用いられる酸化物焼結体およびスパッタリングターゲットであって、導電性に優れている（低い比抵抗）と共に、高い相対密度を兼ね備えており、高いキャリア移動度を有する酸化物半導体膜を、異常放電を抑制しつつ安定して成膜可能な酸化物焼結体およびスパッタリングターゲット、並びにその製造方法を提供することにある。   This invention is made | formed in view of the said situation, The objective is the oxide sintered compact suitably used for manufacture of the oxide semiconductor film for display apparatuses, and a sputtering target, Comprising: It is excellent in electroconductivity. (Low resistivity) and high relative density and oxide semiconductor film and sputtering target capable of stably forming an oxide semiconductor film having high carrier mobility while suppressing abnormal discharge, and It is in providing the manufacturing method.

上記課題を解決し得た本発明の酸化物焼結体は、酸化亜鉛と；酸化インジウムと；Ｔｉ、Ｍｇ、Ａｌ、およびＮｂよりなる群から選択される少なくとも１種の金属の酸化物と、を混合および焼結して得られる酸化物焼結体であって、前記酸化物焼結体をＸ線回折したとき、ＺｎmＩｎ2Ｏ3+m（ｍは５〜７の整数）相を主相とし、Ｉｎ2Ｏ3、及びＺｎＯの各結晶相を含むと共に、相対密度８５％以上、比抵抗０．１Ω・ｃｍ以下であるところに要旨を有するものである。 The oxide sintered body of the present invention that can solve the above-mentioned problems includes zinc oxide; indium oxide; an oxide of at least one metal selected from the group consisting of Ti, Mg, Al, and Nb; When the oxide sintered body is subjected to X-ray diffraction, a Zn m In 2 O 3 + m (m is an integer of 5 to 7) phase is obtained. The main phase includes crystal phases of In 2 O 3 and ZnO, and has a gist in that the relative density is 85% or more and the specific resistance is 0.1 Ω · cm or less.

本発明の好ましい実施形態において、前記酸化物焼結体に含まれる金属元素の含有量（原子％）をそれぞれ、［Ｚｎ］、［Ｉｎ］、［Ｔｉ］、［Ｍｇ］、［Ａｌ］、［Ｎｂ］としたとき、［Ｚｎ］に対する［Ｉｎ］の比、［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］に対する［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］の比は、それぞれ下式を満足するものである。
０．２７≦［Ｉｎ］／［Ｚｎ］≦０．４５
（［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）／（［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）≦０．１ In a preferred embodiment of the present invention, the content (atomic%) of the metal element contained in the oxide sintered body is set to [Zn], [In], [Ti], [Mg], [Al], [Al, Nb], the ratio of [In] to [Zn], [Zn] + [In] + [Ti] + [Mg] + [Al] + [Ti] + [Mg] + [Al ] + [Nb] ratios satisfy the following expressions, respectively.
0.27 ≦ [In] / [Zn] ≦ 0.45
([Ti] + [Mg] + [Al] + [Nb]) / ([Zn] + [In] + [Ti] + [Mg] + [Al] + [Nb])) ≦ 0.1

また本発明の好ましい実施形態において、前記酸化物焼結体に含まれる前記ＺｎmＩｎ2Ｏ3+m、前記Ｉｎ2Ｏ3、及び前記ＺｎＯの合計に対する各結晶相の体積比は、それぞれ下式を満足するものである。
ＺｎmＩｎ2Ｏ3+m／（ＺｎmＩｎ2Ｏ3+m＋Ｉｎ2Ｏ3＋ＺｎＯ）≧０．７５
０．００５≦Ｉｎ2Ｏ3／（ＺｎmＩｎ2Ｏ3+m＋Ｉｎ2Ｏ3＋ＺｎＯ）≦０．１５
０．００５≦ＺｎＯ／（ＺｎmＩｎ2Ｏ3+m＋Ｉｎ2Ｏ3＋ＺｎＯ）≦０．２０
（但し、ＺｎmＩｎ2Ｏ3+mはＺｎ5Ｉｎ2Ｏ8、Ｚｎ6Ｉｎ2Ｏ9、Ｚｎ7Ｉｎ2Ｏ10の合計である。） In a preferred embodiment of the present invention, the volume ratio of each crystal phase with respect to the total of Zn m In 2 O 3 + m , In 2 O 3 , and ZnO contained in the oxide sintered body is as follows: The expression is satisfied.
Zn m In 2 O 3 + m / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≧ 0.75
0.005 ≦ In 2 O 3 / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≦ 0.15
0.005 ≦ ZnO / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≦ 0.20
(However, Zn m In 2 O 3 + m is the total of Zn 5 In 2 O 8 , Zn 6 In 2 O 9 , and Zn 7 In 2 O 10. )

また、上記課題を解決し得た本発明のスパッタリングターゲットは、上記のいずれかに記載の酸化物焼結体を用いて得られるスパッタリングターゲットである。   Moreover, the sputtering target of this invention which could solve the said subject is a sputtering target obtained using the oxide sintered compact in any one of said.

また、上記課題を解決し得た本発明に係る前記酸化物焼結体の好ましい製造方法は、酸化亜鉛と；酸化インジウムと；Ｔｉ、Ｍｇ、Ａｌ、およびＮｂよりなる群から選択される少なくとも１種の金属の酸化物とを混合し、黒鉛型にセットした後、焼結温度９５０〜１０５０℃、該温度域での保持時間０．１〜５時間で焼結する第一の焼結工程と、前記第一の焼結工程後、焼結温度１１００〜１２００℃、該温度域での保持時間０．１〜５時間で焼結する第二の焼結工程とを包含すると共に、前記第一の焼結工程と前記第二の焼結工程を、加圧圧力１００〜５００ｋｇｆ／ｃｍ2で行うことに要旨を有する。 Moreover, the preferable manufacturing method of the said oxide sintered compact which concerns on this invention which could solve the said subject is at least 1 selected from the group which consists of zinc oxide, indium oxide, Ti, Mg, Al, and Nb. A first sintering step of mixing a seed metal oxide and setting it in a graphite mold, followed by sintering at a sintering temperature of 950 to 1050 ° C. and a holding time of 0.1 to 5 hours in the temperature range; And a second sintering step of sintering at a sintering temperature of 1100 to 1200 ° C. and a holding time in the temperature range of 0.1 to 5 hours after the first sintering step. The present invention is summarized in that the sintering step and the second sintering step are performed at a pressure of 100 to 500 kgf / cm 2 .

本発明によれば、低い比抵抗と、高い相対密度を有する酸化物焼結体およびスパッタリングターゲットが得られる。また本発明のスパッタリングターゲットを用いれば、キャリア移動度の高い酸化物半導体膜を、異常放電等を抑制して安定して成膜できるため、生産性が向上する。   According to the present invention, an oxide sintered body and a sputtering target having a low specific resistance and a high relative density can be obtained. In addition, when the sputtering target of the present invention is used, an oxide semiconductor film with high carrier mobility can be stably formed while suppressing abnormal discharge or the like, so that productivity is improved.

また本発明の製造方法によれば、上記特性を有する酸化物焼結体を製造できる。   Moreover, according to the manufacturing method of this invention, the oxide sintered compact which has the said characteristic can be manufactured.

図１は、本発明の酸化物焼結体およびスパッタリングターゲットを製造するための基本的な工程を示す図である。FIG. 1 is a diagram showing a basic process for producing an oxide sintered body and a sputtering target of the present invention. 図２は、本発明の製造方法に用いられる焼結工程（第一の焼結工程と第二の焼結工程）の一例を示すグラフである。FIG. 2 is a graph showing an example of a sintering process (first sintering process and second sintering process) used in the production method of the present invention.

本発明者らは、酸化亜鉛と酸化インジウムとを含む酸化物焼結体について、スパッタリング中の異常放電を抑制することで長時間の安定した成膜が可能であり、しかもキャリア移動度が高い酸化物半導体膜を成膜するのに適したスパッタリングターゲット用酸化物焼結体を提供するため、検討を重ねてきた。   The present inventors have made it possible to stably form a film for a long time by suppressing abnormal discharge during sputtering for an oxide sintered body containing zinc oxide and indium oxide, and have high carrier mobility. In order to provide an oxide sintered body for a sputtering target suitable for forming a physical semiconductor film, studies have been made repeatedly.

その結果、酸化亜鉛と；酸化インジウムと；Ｔｉ、Ｍｇ、Ａｌ、およびＮｂよりなる群から選択される少なくとも１種の金属（以下、Ｍ金属という）の酸化物の各粉末と、を混合および焼結して得られる酸化物焼結体であって、上記酸化物焼結体をＸ線回折したとき、ＺｎmＩｎ2Ｏ3+m（ｍは５〜７の整数）相を主相とし、Ｉｎ2Ｏ3、及びＺｎＯの各結晶相を含むような構成としたときに所期の目的が達成されることを見出した。 As a result, zinc oxide; indium oxide; and powders of oxides of at least one metal selected from the group consisting of Ti, Mg, Al, and Nb (hereinafter referred to as M metal) are mixed and sintered. An oxide sintered body obtained by sintering, and when the oxide sintered body is X-ray diffracted, the main phase is a Zn m In 2 O 3 + m (m is an integer of 5 to 7) phase, It has been found that the intended purpose can be achieved when the structure includes each crystal phase of In 2 O 3 and ZnO.

詳細には、上記酸化物焼結体をＸ線回折したときの相構成について、（ア）ＺｎとＩｎは、これらが結合したＺｎmＩｎ2Ｏ3+m（ｍは５〜７の整数）相（主相）、およびＩｎ2Ｏ3、ＺｎＯとして存在し、このような相構成としたときに異常放電を大幅に抑制できること、（イ）Ｍ金属はキャリア移動度の向上に有用な効果を発揮すること（ウ）相対密度と比抵抗を制御することによってスパッタリング中の異常放電の発生の抑制効果を一層向上できること、を突き止めた。（エ）そして、このような相構成を有する酸化物焼結体を得るためには、所定の焼結条件で焼結を行えばよいこと、を見出し、本発明に至った。 Specifically, regarding the phase structure when the oxide sintered body is subjected to X-ray diffraction, (a) Zn and In are Zn m In 2 O 3 + m in which they are bonded (m is an integer of 5 to 7). It exists as a phase (main phase), In 2 O 3 , and ZnO, and when such a phase configuration is adopted, abnormal discharge can be greatly suppressed, and (b) M metal has a useful effect in improving carrier mobility. It has been found that the effect of suppressing the occurrence of abnormal discharge during sputtering can be further improved by controlling the relative density and specific resistance. (D) Then, in order to obtain an oxide sintered body having such a phase structure, it was found that the sintering should be performed under predetermined sintering conditions, and the present invention has been achieved.

まず、本発明に係る酸化物焼結体の構成について、詳しく説明する。上述したように本発明の酸化物焼結体は、上記酸化物焼結体をＸ線回折したとき、ＺｎmＩｎ2Ｏ3+m（ｍは５〜７の整数）相を主相とし、Ｉｎ2Ｏ3、及びＺｎＯの各結晶相を含む酸化物焼結体としたところに特徴がある。 First, the structure of the oxide sintered body according to the present invention will be described in detail. As described above, the oxide sintered body of the present invention has a Zn m In 2 O 3 + m (m is an integer of 5 to 7) phase as a main phase when the oxide sintered body is subjected to X-ray diffraction. It is characterized in that it is an oxide sintered body containing crystal phases of In 2 O 3 and ZnO.

本発明におけるＸ線回折条件は、以下のとおりである。
分析装置：理学電機製「Ｘ線回折装置ＲＩＮＴ−１５００」
分析条件
ターゲット：Ｃｕ
単色化：モノクロメートを使用（Ｋα）
ターゲット出力：４０ｋＶ−２００ｍＡ
（連続測定）θ／２θ走査
スリット：発散１／２°、散乱１／２°、受光０．１５ｍｍ
モノクロメータ受光スリット：０．６ｍｍ
走査速度：２°／ｍｉｎ
サンプリング幅：０．０２°
測定角度（２θ）：５〜９０° The X-ray diffraction conditions in the present invention are as follows.
Analysis device: “X-ray diffractometer RINT-1500” manufactured by Rigaku Corporation
Analysis conditions Target: Cu
Monochromatic: Uses a monochrome mate (Kα)
Target output: 40kV-200mA
(Continuous measurement) θ / 2θ scanning Slit: Divergence 1/2 °, Scattering 1/2 °, Received light 0.15 mm
Monochromator light receiving slit: 0.6mm
Scanning speed: 2 ° / min
Sampling width: 0.02 °
Measurement angle (2θ): 5 to 90 °

この測定で得られた回折ピークについて、ＩＣＤＤ（International Center for Diffraction Data)カードの２０−１４４０、２０−１４４１、０６−０４１６、３６−１４５１に記載されている結晶構造を有する結晶相（それぞれ、Ｚｎ5Ｉｎ2Ｏ8、Ｚｎ7Ｉｎ2Ｏ10、Ｉｎ2Ｏ3、ＺｎＯに対応）を特定する。またＺｎ6Ｉｎ2Ｏ9は、下記参考文献（１）、（２）に記載されている結晶構造を有する結晶相を特定する。
参考文献（１）M.Nakamura, N.Kimizuka and T.Mohri: J. Solid State Chem. 86(1990) 16-40
参考文献（２）M.Nakamura, N.Kimizuka, T.Mohri and M.Isobe: J. Solid State Chem. 105(1993) 535-549 With respect to the diffraction peaks obtained by this measurement, crystal phases having a crystal structure described in ICDD (International Center for Diffraction Data) cards 20-1440, 20-1441, 06-0416, 36-1451 (respectively Zn 5 In 2 O 8 , Zn 7 In 2 O 10 , In 2 O 3 , and ZnO). Zn 6 In 2 O 9 specifies a crystal phase having a crystal structure described in the following references (1) and (2).
References (1) M. Nakamura, N. Kimizuka and T. Mohri: J. Solid State Chem. 86 (1990) 16-40
Reference (2) M. Nakamura, N. Kimizuka, T. Mohri and M. Isobe: J. Solid State Chem. 105 (1993) 535-549

次に上記Ｘ線回折によって検出される本発明を特定する化合物について詳しく説明する。   Next, the compound that identifies the present invention detected by the X-ray diffraction will be described in detail.

（ＺｎmＩｎ2Ｏ3+m化合物について）
ＺｎmＩｎ2Ｏ3+m化合物（相）は、本発明の酸化物焼結体を構成する酸化亜鉛と酸化インジウムが結合して形成されるものである。この化合物の結晶構造は六方晶であり、酸化物焼結体のキャリア移動度向上に大きく寄与する。 (About Zn m In 2 O 3 + m compounds)
The Zn m In 2 O 3 + m compound (phase) is formed by combining zinc oxide and indium oxide constituting the oxide sintered body of the present invention. The crystal structure of this compound is a hexagonal crystal and greatly contributes to the improvement in carrier mobility of the oxide sintered body.

ＺｎmＩｎ2Ｏ3+m化合物におけるｍは５(Ｚｎ5Ｉｎ2Ｏ8)、６(Ｚｎ6Ｉｎ2Ｏ9)、７(Ｚｎ7Ｉｎ2Ｏ10)の少なくともいずれか一つである。ｍが４以下、あるいは８以上の整数であると酸化物半導体膜の半導体特性が劣化し、キャリア移動度が低下するため望ましくない。なお、これらはＺｎ、Ｉｎ、およびＭ金属との複合酸化物の結晶であるため、ｍは整数となる。 M in the Zn m In 2 O 3 + m compound is at least one of 5 (Zn 5 In 2 O 8 ), 6 (Zn 6 In 2 O 9 ), and 7 (Zn 7 In 2 O 10 ). If m is an integer of 4 or less or an integer of 8 or more, the semiconductor characteristics of the oxide semiconductor film are deteriorated and carrier mobility is lowered, which is not desirable. Since these are crystals of complex oxides of Zn, In, and M metal, m is an integer.

本発明では、上記ＺｎmＩｎ2Ｏ3+m化合物を主相として含んでいる。ここで「主相」とは、ＺｎmＩｎ2Ｏ3+m（Ｚｎ5Ｉｎ2Ｏ8(ｍ＝５)、Ｚｎ6Ｉｎ2Ｏ9(ｍ＝６)、Ｚｎ7Ｉｎ2Ｏ10(ｍ＝７)の合計）が上記Ｘ線回折によって検出される全化合物中、最も比率の多い化合物を意味している。 In the present invention, it includes the Zn m In 2 O 3 + m compound as a main phase. Here, “main phase” means Zn m In 2 O 3 + m (Zn 5 In 2 O 8 (m = 5), Zn 6 In 2 O 9 (m = 6), Zn 7 In 2 O 10 (m = Sum of 7) means the compound with the highest ratio among all the compounds detected by the X-ray diffraction.

また本発明の酸化物焼結体は、Ｉｎ2Ｏ3、及びＺｎＯの各結晶相（化合物）を必須的に含んでいる。酸化物焼結体にＩｎ2Ｏ3、及びＺｎＯを含有させることによって異常放電を抑制できる。そのメカニズムの詳細は不明であるが、複合酸化物（ＺｎmＩｎ2Ｏ3+m）だけではなく、単独金属元素の酸化物（Ｉｎ2Ｏ3、及びＺｎＯ）も含有させることによって、局部的な導電率、または熱伝導率が向上し、異常放電が抑制されると推察される。 In addition, the oxide sintered body of the present invention essentially contains each crystal phase (compound) of In 2 O 3 and ZnO. Abnormal discharge can be suppressed by including In 2 O 3 and ZnO in the oxide sintered body. Although the details of the mechanism are unknown, not only the complex oxide (Zn m In 2 O 3 + m ) but also the oxides of single metal elements (In 2 O 3 and ZnO) can be included locally. It is presumed that the electrical conductivity or thermal conductivity is improved and abnormal discharge is suppressed.

本発明の上記各結晶相には、後記するＭ金属が固溶している場合も含まれ、更にＩｎ2Ｏ3、およびＺｎＯには、Ｍ金属に加えてＺｎやＩｎが固溶している場合も含まれる。 Each crystal phase of the present invention includes a case where M metal described later is in solid solution, and In 2 O 3 and ZnO, Zn and In are dissolved in addition to M metal. Cases are also included.

本発明に用いられるＭ金属は、スパッタリングによって形成した膜のキャリア移動度の向上に有用な元素である。Ｍ金属は、Ｔｉ、Ｍｇ、ＡｌおよびＮｂよりなる群から選択され、単独で用いてもよいし、２種以上を併用してもよい。このうち半導体特性の観点から好ましいＭ金属は、Ｔｉ、Ｍｇ、Ａｌである。   M metal used in the present invention is an element useful for improving the carrier mobility of a film formed by sputtering. The M metal is selected from the group consisting of Ti, Mg, Al and Nb, and may be used alone or in combination of two or more. Among these, preferable M metals from the viewpoint of semiconductor characteristics are Ti, Mg, and Al.

Ｍ金属は酸化亜鉛と酸化インジウムのみからなる酸化物焼結体のキャリア移動度向上に大きく寄与する元素として選択された元素である。Ｍ金属を含有しない場合に比べ、本発明で規定するＭ金属を、好ましくは後記する所定の比率で含有する酸化物焼結体を用いることにより、キャリア移動度が向上する。   M metal is an element selected as an element that greatly contributes to improving the carrier mobility of an oxide sintered body composed of only zinc oxide and indium oxide. Compared with the case where no M metal is contained, carrier mobility is improved by using an oxide sintered body containing the M metal specified in the present invention, preferably in a predetermined ratio described later.

なお、キャリア移動度向上効果を発現させる上でＭ金属は、少なくともその一部（好ましくはその大部分）が上記結晶相に固溶していることが望ましいが、本発明のキャリア移動度向上効果を阻害しない限り、Ｍ金属の一部は酸化物として存在していてもよい（例えば５体積％以下）。   In order to exhibit the effect of improving the carrier mobility, it is desirable that at least a part (preferably most) of the M metal is dissolved in the crystal phase. As long as this is not inhibited, part of the M metal may be present as an oxide (for example, 5% by volume or less).

次に、本発明の酸化物焼結体に含まれる金属元素の含有量（原子％）について説明する。酸化物焼結体に含まれる金属元素の含有量（原子％）をそれぞれ、［Ｚｎ］、［Ｉｎ］、［Ｔｉ］、［Ｍｇ］、［Ａｌ］、［Ｎｂ］としたとき、［Ｚｎ］に対する［Ｉｎ］の比、［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］に対する［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］の比を下記特定の範囲内とすることが上記所望の効果を得る観点からは望ましい。ここで、［Ｔｉ］、［Ｍｇ］、［Ａｌ］、［Ｎｂ］はＭ金属の１種であり、各焼結体において例えばＴｉを含まない場合は［Ｔｉ］＝０として算出される。   Next, the content (atomic%) of the metal element contained in the oxide sintered body of the present invention will be described. When the content (atomic%) of the metal element contained in the oxide sintered body is [Zn], [In], [Ti], [Mg], [Al], and [Nb], [Zn] [In] ratio to [Zn] + [In] + [Ti] + [Mg] + [Al] + [Nb] [Ti] + [Mg] + [Al] + [Nb] A specific range is desirable from the viewpoint of obtaining the desired effect. Here, [Ti], [Mg], [Al], and [Nb] are one kind of M metal, and when each sintered body does not contain Ti, for example, [Ti] = 0 is calculated.

［Ｚｎ］に対する［Ｉｎ］の比（［Ｉｎ］／［Ｚｎ］；以下、比率（１）という。）は、好ましくは０．２７以上、より好ましくは０．２８以上であって、好ましくは０．４５以下、より好ましくは０．４０以下である。比率（１）が小さくなると、[ＺｎmＩｎ2Ｏ3+m］がｍ≦４の複合酸化物（Ｚｎ4Ｉｎ2Ｏ7など）が生成するようになり、抵抗率が高くなってキャリア移動度が低下する。一方、比率（１）が大きくなると、[ＺｎmＩｎ2Ｏ3+m］がｍ≧８の複合酸化物（Ｚｎ8Ｉｎ2Ｏ11など）が生成するようになり、キャリア移動度が低下する。 The ratio of [In] to [Zn] ([In] / [Zn]; hereinafter referred to as the ratio (1)) is preferably 0.27 or more, more preferably 0.28 or more, and preferably 0. .45 or less, more preferably 0.40 or less. When the ratio (1) is decreased, a complex oxide (Zn 4 In 2 O 7 etc.) with [Zn m In 2 O 3 + m ] of m ≦ 4 is generated, and the resistivity is increased and carrier movement is increased. The degree decreases. On the other hand, when the ratio (1) increases, a complex oxide (Zn 8 In 2 O 11 or the like) having [Zn m In 2 O 3 + m ] of m ≧ 8 is generated, and the carrier mobility is lowered. .

また［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］に対する［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］の比(（［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）／（［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）；以下、比率（２）という)は、好ましくは０．１以下、より好ましくは０．０５以下である。比率（２）が大きくなると、Ｍ金属がＩｎやＺｎと複合酸化物を生成して薄膜の半導体特性が劣化し、キャリア移動度が低下するからである。なお、比率（２）の下限については特に限定されないが、薄膜半導体特性の安定化の観点からは好ましくは０．００１以上、より好ましくは０．００５以上である。   The ratio of [Ti] + [Mg] + [Al] + [Nb] to [Zn] + [In] + [Ti] + [Mg] + [Al] + [Nb] (([Ti] + [Mg ] + [Al] + [Nb]) / ([Zn] + [In] + [Ti] + [Mg] + [Al] + [Nb]); hereinafter referred to as the ratio (2)) is preferably 0. .1 or less, more preferably 0.05 or less. This is because when the ratio (2) increases, the M metal generates a composite oxide with In and Zn, the semiconductor characteristics of the thin film deteriorate, and the carrier mobility decreases. The lower limit of the ratio (2) is not particularly limited, but is preferably 0.001 or more, more preferably 0.005 or more from the viewpoint of stabilizing the thin film semiconductor characteristics.

次に酸化物焼結体に含まれるＺｎmＩｎ2Ｏ3+m（但し［ＺｎmＩｎ2Ｏ3+m］は［Ｚｎ5Ｉｎ2Ｏ8］、［Ｚｎ6Ｉｎ2Ｏ9］、［Ｚｎ7Ｉｎ2Ｏ10］の合計、以下同じ）、Ｉｎ2Ｏ3、及びＺｎＯの合計に対する各結晶相の体積比について説明する。以下では、［ＺｎmＩｎ2Ｏ3+m］＋［Ｉｎ2Ｏ3］＋［ＺｎＯ］の合計に対するＺｎmＩｎ2Ｏ3+mの比、Ｉｎ2Ｏ3比、ＺｎＯ比を夫々、［ＺｎmＩｎ2Ｏ3+m］比、［Ｉｎ2Ｏ3］比、［ＺｎＯ］比と呼ぶ。これらの比率を適切に制御することで、スパッタリング時の異常放電をより一層抑制することができる。 Next, Zn m In 2 O 3 + m (where [Zn m In 2 O 3 + m ] is [Zn 5 In 2 O 8 ], [Zn 6 In 2 O 9 ], [ The volume ratio of each crystal phase to the total of Zn 7 In 2 O 10 ], the same applies hereinafter), In 2 O 3 , and ZnO will be described. In the following, the ratio of Zn m In 2 O 3 + m , In 2 O 3 ratio, and ZnO ratio to the sum of [Zn m In 2 O 3 + m ] + [In 2 O 3 ] + [ZnO] are respectively set to [ They are called Zn m In 2 O 3 + m ] ratio, [In 2 O 3 ] ratio, and [ZnO] ratio. By appropriately controlling these ratios, abnormal discharge during sputtering can be further suppressed.

まず、［ＺｎmＩｎ2Ｏ3+m］比は０．７５以上とすることが好ましい。［ＺｎmＩｎ2Ｏ3+m］比を０．７５以上とすることで、より一層異常放電を抑制できる。より好ましい下限は０．８以上、更に好ましくは０．８５以上である。［ＺｎmＩｎ2Ｏ3+m］比の上限は特に限定されず、後記Ｉｎ2Ｏ3とＺｎＯを含む範囲で決定すればよい。 First, the [Zn m In 2 O 3 + m ] ratio is preferably set to 0.75 or more. By setting the [Zn m In 2 O 3 + m ] ratio to 0.75 or more, abnormal discharge can be further suppressed. A more preferable lower limit is 0.8 or more, and further preferably 0.85 or more. The upper limit of the [Zn m In 2 O 3 + m ] ratio is not particularly limited, and may be determined within a range including In 2 O 3 and ZnO described later.

［Ｉｎ2Ｏ3］比は、０．００５〜０．１５であることが好ましい。［Ｉｎ2Ｏ3］比が０．００５未満の場合、異常放電抑制効果が十分に得られないことがある。一方、［Ｉｎ2Ｏ3］比が０．１５を超えると、異常放電発生回数が多くなるため望ましくない。［Ｉｎ2Ｏ3］比はより好ましくは０．０１以上、更に好ましくは０．０３以上であって、より好ましくは０．１３以下、更に好ましくは０．１以下である。 The [In 2 O 3 ] ratio is preferably 0.005 to 0.15. When the [In 2 O 3 ] ratio is less than 0.005, the abnormal discharge suppressing effect may not be sufficiently obtained. On the other hand, if the [In 2 O 3 ] ratio exceeds 0.15, the number of abnormal discharges is increased, which is not desirable. The [In 2 O 3 ] ratio is more preferably 0.01 or more, further preferably 0.03 or more, more preferably 0.13 or less, still more preferably 0.1 or less.

また、［ＺｎＯ］比は、０．００５〜０．２０であることが好ましい。［ＺｎＯ］比が０．００５未満の場合、異常放電抑制効果が十分に得られないことがある。一方、［ＺｎＯ］比が０．２０を超えると、異常放電発生回数が多くなるため望ましくない。［ＺｎＯ］比はより好ましくは０．０１以上、更に好ましくは０．０３以上であって、より好ましくは０．１５以下、更に好ましくは０．１３以下である。   The [ZnO] ratio is preferably 0.005 to 0.20. When the [ZnO] ratio is less than 0.005, the abnormal discharge suppressing effect may not be sufficiently obtained. On the other hand, if the [ZnO] ratio exceeds 0.20, the number of abnormal discharges is increased, which is not desirable. The [ZnO] ratio is more preferably 0.01 or more, still more preferably 0.03 or more, more preferably 0.15 or less, still more preferably 0.13 or less.

本発明の酸化物焼結体の結晶相は、実質的にＺｎmＩｎ2Ｏ3+m、Ｉｎ2Ｏ3、及びＺｎＯで構成されていることが望ましく、他の含み得る結晶相としては製造上不可避的に生成されるＺｎ2ＴｉＯ4、ＩｎＮｂＯ4などを５体積％程度の割合で含んでいてもよい趣旨である。なお、不可避的に生成する結晶相の割合は、ＸＲＤによって測定することができる。 The crystal phase of the oxide sintered body of the present invention is preferably substantially composed of Zn m In 2 O 3 + m , In 2 O 3 , and ZnO. Other possible crystal phases are manufactured. In addition, Zn 2 TiO 4 , InNbO 4 and the like that are inevitably generated may be included at a ratio of about 5% by volume. In addition, the ratio of the crystal phase produced | generated unavoidable can be measured by XRD.

本発明の酸化物焼結体、更には当該酸化物焼結体を用いて得られるスパッタリングターゲットは、相対密度８５％以上、比抵抗０．１Ω・ｃｍ以下であるところに特徴がある。   The oxide sintered body of the present invention and the sputtering target obtained using the oxide sintered body are characterized in that the relative density is 85% or more and the specific resistance is 0.1 Ω · cm or less.

（相対密度８５％以上）
本発明の酸化物焼結体は、相対密度が非常に高く、好ましくは８５％以上であり、より好ましくは９５％以上である。高い相対密度は、スパッタリング中でのノジュールの発生を防止し得るだけでなく、安定した放電をターゲットライフまで連続して維持するなどの利点をもたらす。 (Relative density 85% or more)
The oxide sintered body of the present invention has a very high relative density, preferably 85% or more, and more preferably 95% or more. A high relative density not only can prevent the generation of nodules during sputtering, but also provides advantages such as maintaining a stable discharge continuously to the target life.

（比抵抗０．１Ω・ｃｍ以下）
本発明の酸化物焼結体は、比抵抗が小さく、０．１Ω・ｃｍ以下であり、好ましくは０．０１Ω・ｃｍ以下である。これにより、一層スパッタリング中での異常放電を抑制した成膜が可能となり、スパッタリングターゲットを用いた物理蒸着（スパッタリング法）を表示装置の生産ラインで効率よく行うことができる。 (Specific resistance 0.1Ω ・ cm or less)
The oxide sintered body of the present invention has a small specific resistance and is 0.1 Ω · cm or less, preferably 0.01 Ω · cm or less. Thereby, the film formation in which the abnormal discharge during the sputtering is suppressed becomes possible, and the physical vapor deposition (sputtering method) using the sputtering target can be efficiently performed on the production line of the display device.

次に、本発明の酸化物焼結体を製造する方法について説明する。   Next, a method for producing the oxide sintered body of the present invention will be described.

本発明の酸化物焼結体は、酸化亜鉛と；酸化インジウムと；Ｍ金属の酸化物の各粉末を混合および焼結して得られるものであり、またスパッタリングターゲットは酸化物焼結体を加工することにより製造できる。図１には、酸化物の粉末を（ａ）混合・粉砕→（ｂ）乾燥・造粒→（ｃ）予備成形→（ｄ）脱脂→（ｅ）ホットプレスして得られた酸化物焼結体を、（ｆ）加工→（ｇ）ボンディングしてスパッタリングターゲットを得るまでの基本工程を示している。上記工程のうち本発明では、以下に詳述するように焼結条件（（ｅ）ホットプレス）を適切に制御したところに特徴があり、それ以外の工程は特に限定されず、通常用いられる工程を適宜選択することができる。以下、各工程を説明するが、本発明はこれに限定する趣旨ではない。   The oxide sintered body of the present invention is obtained by mixing and sintering zinc oxide, indium oxide, and M metal oxide powders, and the sputtering target is obtained by processing the oxide sintered body. Can be manufactured. In FIG. 1, oxide powder obtained by (a) mixing / pulverization → (b) drying / granulation → (c) preforming → (d) degreasing → (e) hot pressing The basic process until the sputtering target is obtained by bonding the body to (f) processing → (g) is shown. Among the above steps, the present invention is characterized in that the sintering conditions ((e) hot press) are appropriately controlled as described in detail below, and the other steps are not particularly limited, and are usually used steps. Can be appropriately selected. Hereinafter, although each process is demonstrated, this invention is not the meaning limited to this.

まず、酸化亜鉛粉末、酸化インジウム粉末、およびＭ金属の酸化物の粉末を所定の割合に配合し、混合・粉砕する。用いられる各原料粉末の純度はそれぞれ、約９９．９９％以上が好ましい。微量の不純物元素が存在すると、酸化物半導体膜の半導体特性を損なう恐れがあるためである。各原料粉末の配合割合は、比率が上述した範囲内となるように制御することが好ましい。   First, zinc oxide powder, indium oxide powder, and M metal oxide powder are mixed in a predetermined ratio, and mixed and pulverized. The purity of each raw material powder used is preferably about 99.99% or more. This is because the presence of a trace amount of impurity elements may impair the semiconductor characteristics of the oxide semiconductor film. The blending ratio of each raw material powder is preferably controlled so that the ratio is within the above-described range.

（ａ）混合・粉砕は、ポットミルを使い、原料粉末を水と共に投入して行うことが好ましい。これらの工程に用いられるボールやビーズは、例えばナイロン、アルミナ、ジルコニアなどの材質のものが好ましく用いられる。この際、均一に混合する目的で分散剤や、後の成形工程の容易性を確保するためにバインダーを混合してもよい。   (A) The mixing / pulverization is preferably carried out by using a pot mill and adding the raw material powder together with water. The balls and beads used in these steps are preferably made of materials such as nylon, alumina, zirconia, and the like. At this time, a dispersant or a binder may be mixed in order to ensure the ease of the subsequent molding process for the purpose of uniform mixing.

次に、上記工程で得られた混合粉末について例えばスプレードライヤなどで（ｂ）乾燥・造粒を行うことが好ましい。   Next, it is preferable to perform (b) drying and granulation of the mixed powder obtained in the above step using, for example, a spray dryer.

乾燥・造粒後、（ｃ）予備成形をする。成形に当たっては、乾燥・造粒後の粉末を所定寸法の金型に充填し、金型プレスで予備成形する。この予備成形は、ホットプレス工程で所定の型にセットする際のハンドリング性を向上させる目的で行われるため、０．５〜１．０ｔｏｎｆ／ｃｍ2程度の加圧力を加えて成形体とすればよい。 After drying and granulation, (c) preforming is performed. In the molding, the powder after drying and granulation is filled in a mold having a predetermined size, and preformed by a mold press. This pre-molding is performed for the purpose of improving the handleability when set in a predetermined mold in the hot press process. Therefore, if a pressing force of about 0.5 to 1.0 tonf / cm 2 is applied to form a molded body. Good.

なお、混合粉末に分散剤やバインダーを添加した場合には、分散剤やバインダーを除去するために予備成形後の成形体を加熱して（ｄ）脱脂を行うことが望ましい。加熱条件は脱脂目的が達成できれば特に限定されないが、例えば大気中、おおむね５００℃程度で、５時間程度保持すればよい。   In addition, when a dispersing agent and a binder are added to mixed powder, in order to remove a dispersing agent and a binder, it is desirable to heat the molded object after preforming and (d) degrease. The heating conditions are not particularly limited as long as the purpose of degreasing can be achieved. For example, the heating conditions may be maintained at about 500 ° C. in the atmosphere for about 5 hours.

脱脂後、所望の形状の黒鉛型に成形体をセットして（ｅ）ホットプレスにて焼結を行う。黒鉛型は還元性材料であり、セットした成形体を還元性雰囲気中で焼結できるため、効率よく還元が進行して比抵抗を低くすることができる。   After degreasing, the molded body is set in a graphite mold having a desired shape, and (e) sintering is performed by hot pressing. The graphite mold is a reducing material, and since the set molded body can be sintered in a reducing atmosphere, the reduction proceeds efficiently and the specific resistance can be lowered.

本発明では焼結を２段階の加熱工程にわけて行うことによって（図２）、所望の結晶相構成とし、相対密度を高めることができる。詳細な機構は明らかではないが、第一の焼結工程で焼結体の緻密化と還元が進行し、第二の焼結工程で更に還元が進行すると共に原料酸化物の固溶反応が進んで所望の複合酸化物（ＺｎmＩｎ2Ｏ3+m（ｍ＝５、６、７））が生成すると考えられる。また焼結を２段階の工程に分けて行うことで、焼結体の緻密化と複合酸化物生成を夫々最適な条件で実施できるため、所望の結晶相を有する酸化物焼結体が高い相対密度で得られると推定される。 In the present invention, sintering is performed in two heating steps (FIG. 2), so that the desired crystal phase structure can be obtained and the relative density can be increased. Although the detailed mechanism is not clear, densification and reduction of the sintered body proceed in the first sintering step, further reduction proceeds in the second sintering step, and solid solution reaction of the raw material oxide proceeds. Thus, it is considered that a desired composite oxide (Zn m In 2 O 3 + m (m = 5, 6, 7)) is formed. In addition, by performing the sintering in two steps, the sintered body can be densified and the composite oxide can be produced under optimum conditions, so that the oxide sintered body having a desired crystal phase has a high relative Estimated to be obtained in density.

第一の焼結工程の条件は、焼結温度：９５０〜１０５０℃、該温度での保持時間：０．１〜５時間で焼結を行う。焼結温度が９５０℃未満、あるいは１０５０℃を超えると、所望の相対密度を達成できない。好ましい焼結温度は９７５℃以上、１０４０℃以下である。また焼結時間が短すぎると十分に緻密化することができず、所望の相対密度を達成できない。したがって焼結時間は０．１時間以上、好ましくは０．５時間以上、より好ましくは１．０時間以上である。なお、焼結時間を長くすれば、相対密度も高くできるが、生産性が悪化することから、５時間以下、好ましくは４時間以下、より好ましくは３時間以下である。   The first sintering step includes sintering at a sintering temperature of 950 to 1050 ° C. and a holding time at the temperature of 0.1 to 5 hours. If the sintering temperature is less than 950 ° C. or exceeds 1050 ° C., the desired relative density cannot be achieved. A preferable sintering temperature is 975 ° C. or higher and 1040 ° C. or lower. If the sintering time is too short, it cannot be sufficiently densified and the desired relative density cannot be achieved. Accordingly, the sintering time is 0.1 hour or longer, preferably 0.5 hour or longer, more preferably 1.0 hour or longer. If the sintering time is lengthened, the relative density can be increased, but the productivity is deteriorated, so that it is 5 hours or less, preferably 4 hours or less, more preferably 3 hours or less.

第二の焼結工程の条件は、焼結温度１１００〜１２００℃、該温度での保持時間：０．１〜５時間で焼結を行う。焼結温度が低いと所望の複合酸化物を生成できなかったり、生成量が少なくなる。したがって焼結温度は１１００℃以上、好ましくは１１２５℃以上とする。一方、焼結温度が高すぎると複合酸化物への固溶反応が過大に進行して所望の酸化亜鉛、酸化インジウム量が確保できなくなる。したがって焼結温度は１２００℃以下、好ましくは１１５０℃以下とする。また焼結時間が短すぎると、十分な量の複合酸化物を確保できなくなる。したがって焼結時間は０．１時間以上、好ましくは０．５時間以上、より好ましくは１．０時間以上とする。一方、焼結時間が長すぎると上記固溶反応の過大進行により酸化亜鉛量等が確保できなくなる。したがって焼結時間は５時間以下、好ましくは４時間以下、より好ましくは３時間以下とする。   The conditions for the second sintering step are sintering at a sintering temperature of 1100 to 1200 ° C. and a holding time at the temperature: 0.1 to 5 hours. If the sintering temperature is low, a desired composite oxide cannot be produced or the amount produced is reduced. Therefore, the sintering temperature is 1100 ° C. or higher, preferably 1125 ° C. or higher. On the other hand, if the sintering temperature is too high, the solid solution reaction in the composite oxide proceeds excessively, making it impossible to ensure the desired amounts of zinc oxide and indium oxide. Accordingly, the sintering temperature is 1200 ° C. or lower, preferably 1150 ° C. or lower. If the sintering time is too short, a sufficient amount of complex oxide cannot be secured. Therefore, the sintering time is 0.1 hour or longer, preferably 0.5 hour or longer, more preferably 1.0 hour or longer. On the other hand, if the sintering time is too long, the amount of zinc oxide and the like cannot be ensured due to excessive progress of the solid solution reaction. Therefore, the sintering time is 5 hours or less, preferably 4 hours or less, more preferably 3 hours or less.

上記２段階の焼結工程においてホットプレス時の加圧条件は、第一の焼結工程、第二の焼結工程共に、１００〜５００ｋｇｆ／ｃｍ2程度の圧力を加える。圧力が低すぎると緻密化が十分に進まないことがある。一方、圧力が高すぎると黒鉛型が破損する恐れがあり、また緻密化促進効果が飽和すると共にプレス設備の大型化が必要となる。好ましい加圧条件は１５０ｋｇｆ／ｃｍ2以上、４００ｋｇｆ／ｃｍ2以下である。なお、加圧条件は第一の焼結工程と第二の焼結工程で同一あるいは異なる圧力としてもよいが、生産性の観点から同一圧力で行うことが望ましい。 In the above two-stage sintering process, the pressurizing condition at the time of hot pressing applies a pressure of about 100 to 500 kgf / cm 2 in both the first sintering process and the second sintering process. If the pressure is too low, densification may not proceed sufficiently. On the other hand, if the pressure is too high, the graphite mold may be damaged, the densification promoting effect is saturated, and the press equipment must be enlarged. Preferred pressure conditions are 150 kgf / cm 2 or more and 400 kgf / cm 2 or less. The pressurizing condition may be the same or different pressure in the first sintering step and the second sintering step, but it is desirable to carry out at the same pressure from the viewpoint of productivity.

昇温速度は特に限定されず、例えば第一の焼結工程の温度域までの昇温速度は１０〜２０℃／分程度であり、第一の焼結工程後、第二の焼結工程の温度域までの昇温速度は２〜１０℃／分程度でよい。   The rate of temperature increase is not particularly limited. For example, the rate of temperature increase up to the temperature range of the first sintering step is about 10 to 20 ° C./min, and after the first sintering step, The heating rate up to the temperature range may be about 2 to 10 ° C./min.

焼結工程では、Ｈ2、メタン、ＣＯ等の還元性ガス、Ａｒ、Ｎ2などの不活性ガス雰囲気で行うことが望ましい。特に黒鉛型を使用する本発明では、黒鉛の酸化、消失を抑制するために、焼結雰囲気を不活性ガス雰囲気とすることが好ましい。雰囲気制御方法は特に限定されず、例えば炉内にＡｒガスやＮ2ガスを導入することによって雰囲気を調整すればよい。また雰囲気ガスの圧力は、蒸気圧の高い酸化亜鉛の蒸発を抑制するために大気圧とすることが望ましい。 The sintering process is desirably performed in a reducing gas such as H 2 , methane, and CO, and in an inert gas atmosphere such as Ar and N 2 . Particularly in the present invention using a graphite mold, the sintering atmosphere is preferably an inert gas atmosphere in order to suppress oxidation and disappearance of graphite. The atmosphere control method is not particularly limited. For example, the atmosphere may be adjusted by introducing Ar gas or N 2 gas into the furnace. The pressure of the atmospheric gas is preferably atmospheric pressure in order to suppress evaporation of zinc oxide having a high vapor pressure.

上記のようにして酸化物焼結体を得た後、常法により、（ｆ）加工→（ｇ）ボンディングを行なうと本発明のスパッタリングターゲットが得られる。このようにして得られるスパッタリングターゲットの相対密度および比抵抗も、酸化物焼結体と同様、非常に良好なものであり、好ましい相対密度はおおむね８５％以上であり、好ましい比抵抗はおおむね０．１Ω・ｃｍ以下である。   After obtaining the oxide sintered body as described above, the sputtering target of the present invention is obtained by performing (f) processing → (g) bonding by a conventional method. The relative density and specific resistance of the sputtering target obtained in this way are also very good as in the case of the oxide sintered body, the preferable relative density is about 85% or more, and the preferable specific resistance is about 0. 0. 1 Ω · cm or less.

以下、実施例を挙げて本発明をより具体的に説明するが、本発明は、下記実施例に限定されず、本発明の趣旨に適合し得る範囲で適切に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に含まれる。   EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and may be implemented with appropriate modifications within a scope that can meet the gist of the present invention. These are all possible and are within the scope of the present invention.

酸化亜鉛粉末（純度９９．９９％）、酸化インジウム粉末（純度９９．９９％）、および酸化チタン、酸化マグネシウム、酸化アルミニウム、酸化ニオブの各粉末（純度９９．９９％）を表２に示す比率で配合し、水と分散剤（ポリカルボン酸アンモニウム）を加えてナイロンボールミルで２０時間混合した。次に、上記工程で得られた混合粉末について乾燥、造粒を行った。   The ratio shown in Table 2 for zinc oxide powder (purity 99.99%), indium oxide powder (purity 99.99%), and titanium oxide, magnesium oxide, aluminum oxide, and niobium oxide powders (purity 99.99%) Then, water and a dispersant (ammonium polycarboxylate) were added and mixed for 20 hours in a nylon ball mill. Next, the mixed powder obtained in the above step was dried and granulated.

このようにして得られた粉末を金型プレスにて予備成形した後（成形圧力：１．０ｔｏｎｆ／ｃｍ2、成形体サイズ：φ１１０×ｔ１３ｍｍ、ｔは厚み）、大気雰囲気下で５００℃に昇温（昇温速度：１℃／ｍｉｎ）し、該温度で５時間保持して脱脂した。得られた成形体を黒鉛型にセットし、表３に示す条件（Ａ〜Ｆ）でホットプレスを行った。プレス圧力は第一の焼結工程、および第二の焼結工程共に一定とした。この際、ホットプレス炉内にはＮ2ガスを導入し、Ｎ2雰囲気下で焼結した。得られた焼結体を機械加工してφ１００×ｔ５ｍｍに仕上げ、Ｃｕ製バッキングプレートにボンディングし、スパッタリングターゲットを作製した。 After the powder thus obtained was preformed by a mold press (molding pressure: 1.0 tonf / cm 2 , compact size: φ110 × t13 mm, t is thickness), the temperature was raised to 500 ° C. in an air atmosphere. The mixture was warmed (temperature rising rate: 1 ° C./min), held at that temperature for 5 hours for degreasing. The obtained molded body was set in a graphite mold and hot pressed under the conditions shown in Table 3 (A to F). The pressing pressure was constant for both the first sintering process and the second sintering process. At this time, N 2 gas was introduced into the hot press furnace and sintered in an N 2 atmosphere. The obtained sintered body was machined to finish φ100 × t5 mm, and bonded to a Cu backing plate to produce a sputtering target.

このようにして得られたスパッタリングターゲットをスパッタリング装置に取り付け、ＤＣ（直流）マグネトロンスパッタリングを行なった。スパッタリング条件は、ＤＣスパッタリングパワー１５０Ｗ、Ａｒ／０．１体積％Ｏ2雰囲気、圧力０．８ｍＴｏｒｒとした。さらにこの条件で成膜した薄膜を使用して、チャネル長１０μｍ、チャネル幅１００μｍの薄膜トランジスタを作成した。 The sputtering target thus obtained was attached to a sputtering apparatus, and DC (direct current) magnetron sputtering was performed. The sputtering conditions were a DC sputtering power of 150 W, an Ar / 0.1 volume% O 2 atmosphere, and a pressure of 0.8 mTorr. Further, a thin film transistor having a channel length of 10 μm and a channel width of 100 μm was formed using the thin film formed under these conditions.

（相対密度の測定）
相対密度は、スパッタリング後、ターゲットをバッキングプレートから取り外して鏡面研磨し、反射電子顕微鏡（ＳＥＭ）で観察して気孔率を測定して求めた。具体的にはＳＥＭ観察（１０００倍）して写真撮影し、５０μｍ角の領域における気孔占有面積率を測定して気孔率とした。異なる任意の２０視野を観察し、その平均値を当該試料の平均気孔率とした。１００％から気孔率を引いた値を焼結体の相対密度（％）とした。相対密度は８５％以上を合格と評価した。 (Measurement of relative density)
The relative density was determined by removing the target from the backing plate, mirror polishing after sputtering, and observing with a reflection electron microscope (SEM) and measuring the porosity. Specifically, a SEM observation (1000 times) was taken to take a photograph, and the pore occupation area ratio in a 50 μm square region was measured to obtain the porosity. 20 different visual fields were observed, and the average value was taken as the average porosity of the sample. The value obtained by subtracting the porosity from 100% was taken as the relative density (%) of the sintered body. A relative density of 85% or more was evaluated as acceptable.

（比抵抗の測定）
焼結体の比抵抗は、上記製作したスパッタリングターゲットについて四端子法により測定した。比抵抗は０．１Ω・ｃｍ以下を合格と評価した。 (Measurement of specific resistance)
The specific resistance of the sintered body was measured by the four-terminal method for the produced sputtering target. The specific resistance was evaluated to be 0.1 Ω · cm or less.

（結晶相の比率）
各結晶相の比率は、スパッタリング後、ターゲットをバッキングプレートから取り外して１０ｍｍ角の試験片を切出し、Ｘ線回折で回折線の強度を測定して求めた。 (Crystal phase ratio)
The ratio of each crystal phase was determined by removing the target from the backing plate after sputtering, cutting out a 10 mm square test piece, and measuring the intensity of the diffraction line by X-ray diffraction.

分析装置：理学電機製「Ｘ線回折装置ＲＩＮＴ−１５００」
分析条件：
ターゲット：Ｃｕ
単色化：モノクロメートを使用（Ｋα）
ターゲット出力：４０ｋＶ−２００ｍＡ
（連続測定）θ／２θ走査
スリット：発散１／２°、散乱１／２°、受光０．１５ｍｍ
モノクロメータ受光スリット：０．６ｍｍ
走査速度：２°／ｍｉｎ
サンプリング幅：０．０２°
測定角度（２θ）：５〜９０° Analysis device: “X-ray diffractometer RINT-1500” manufactured by Rigaku Corporation
Analysis conditions:
Target: Cu
Monochromatic: Uses a monochrome mate (Kα)
Target output: 40kV-200mA
(Continuous measurement) θ / 2θ scanning Slit: Divergence 1/2 °, Scattering 1/2 °, Received light 0.15 mm
Monochromator light receiving slit: 0.6mm
Scanning speed: 2 ° / min
Sampling width: 0.02 °
Measurement angle (2θ): 5 to 90 °

この測定で得られた回折ピークについて、ＩＣＤＤ（International Center for Diffraction Data)カードに基づいて表１に示す各結晶相のピークを同定し、回折ピークの高さを測定した。なおＺｎ6Ｉｎ2Ｏ9については、ＩＣＤＤカードに記載がないため、上記参考文献（１）、（２）に示される結晶構造に基づき、結晶構造因子計算により理論回折強度を求め、測定するピークを決定した。これらのピークは、当該結晶相で回折強度が十分に高く、他の結晶相のピークとの重複がなるべく少ないピークを選択した。各結晶相の指定ピークでのピーク高さの測定値をそれぞれＩ（ＺｎmＩｎ2Ｏ3+m）、Ｉ（Ｉｎ2Ｏ3）、Ｉ（ＺｎＯ）とし（「Ｉ」は測定値であることを表す意味）、下式によって［ＺｎmＩｎ2Ｏ3+m］（表４中、「Ｐ１」）、［Ｉｎ2Ｏ3］（表４中、「Ｐ２」）、［ＺｎＯ］（表４中、「Ｐ３」）の体積比率を求めた。
［ＺｎmＩｎ2Ｏ3+m］＝Ｉ（ＺｎmＩｎ2Ｏ3+m）／（Ｉ（ＺｎmＩｎ2Ｏ3+m）＋Ｉ（Ｉｎ2Ｏ3）＋Ｉ（ＺｎＯ））
［Ｉｎ2Ｏ3］＝Ｉ（Ｉｎ2Ｏ3）／（Ｉ（ＺｎmＩｎ2Ｏ3+m）＋Ｉ（Ｉｎ2Ｏ3）＋Ｉ（ＺｎＯ））
［ＺｎＯ］＝Ｉ（ＺｎＯ）／（Ｉ（ＺｎmＩｎ2Ｏ3+m）＋Ｉ（Ｉｎ2Ｏ3）＋Ｉ（ＺｎＯ）） About the diffraction peak obtained by this measurement, the peak of each crystal phase shown in Table 1 was identified based on an ICDD (International Center for Diffraction Data) card, and the height of the diffraction peak was measured. Since Zn 6 In 2 O 9 is not described in the ICDD card, the peak obtained by calculating the theoretical diffraction intensity by crystal structure factor calculation based on the crystal structure shown in the above references (1) and (2) and measuring it. It was determined. These peaks were selected so that the diffraction intensity of the crystal phase was sufficiently high and the overlap with the peaks of other crystal phases was as small as possible. The measured values of the peak height at the designated peak of each crystal phase are I (Zn m In 2 O 3 + m ), I (In 2 O 3 ), and I (ZnO), respectively (“I” is the measured value) [Zn m In 2 O 3 + m ] (“P1” in Table 4), [In 2 O 3 ] (“P2” in Table 4), [ZnO] (Table 4, the volume ratio of “P3”) was determined.
[Zn m In 2 O 3 + m] = I (Zn m In 2 O 3 + m) / (I (Zn m In 2 O 3 + m) + I (In 2 O 3) + I (ZnO))
[In 2 O 3 ] = I (In 2 O 3 ) / (I (Zn m In 2 O 3 + m ) + I (In 2 O 3 ) + I (ZnO))
[ZnO] = I (ZnO) / (I (Zn m In 2 O 3 + m) + I (In 2 O 3) + I (ZnO))

結晶相の比率は［ＺｎmＩｎ2Ｏ3+m］は０．７５以上、［Ｉｎ2Ｏ3］は０．００５〜０．１５、［ＺｎＯ］は０．００５〜０．２０を合格と評価した。 As for the ratio of the crystal phase, [Zn m In 2 O 3 + m ] is 0.75 or more, [In 2 O 3 ] is 0.005 to 0.15, and [ZnO] is 0.005 to 0.20. evaluated.

（異常放電）
異常放電は、スパッタリング中の異常放電の回数を測定して評価した。具体的には、１分間のスパッタリングを１００回繰り返し、スパッタリング後に取り出したターゲットを目視で観察し、異常放電の痕跡の個数を数えることで求めた。異常放電は、異常放電回数が２回以下を合格と評価した。 (Abnormal discharge)
Abnormal discharge was evaluated by measuring the number of abnormal discharges during sputtering. Specifically, sputtering for 1 minute was repeated 100 times, the target taken out after sputtering was observed visually, and the number of traces of abnormal discharge was counted. Abnormal discharge evaluated that the number of abnormal discharges was 2 or less.

（キャリア移動度）
キャリア移動度は、上記のスパッタリング条件で成膜した薄膜を用いて作成したチャネル長１０μｍ、チャネル幅１００μｍの薄膜トランジスタの移動度を測定した。キャリア移動度は１５ｃｍ2／Ｖｓ以上を合格と評価した。 (Carrier mobility)
The carrier mobility was measured by measuring the mobility of a thin film transistor having a channel length of 10 μm and a channel width of 100 μm formed using a thin film formed under the above sputtering conditions. Carrier mobility evaluated 15 cm < 2 > / Vs or more as the pass.

結果を表４に示す。   The results are shown in Table 4.

Figure 0005337224
Figure 0005337224

Figure 0005337224
Figure 0005337224

Figure 0005337224
Figure 0005337224

Figure 0005337224
Figure 0005337224

本発明の好ましい組成、製造条件を満足するＮｏ．１〜５、９〜１１は異常放電が抑制されていると共に、高いキャリア移動度を示した。すなわち、スパッタリングを行なったところ、異常放電の発生は２回以下であり、安定して放電することが確認された。また、このようにして得られたスパッタリングターゲットの相対密度および比抵抗も良好な結果が得られた。上記薄膜のキャリア移動度も１５ｃｍ2／Ｖｓ以上の高いキャリア移動度が得られた。 No. satisfying the preferred composition and production conditions of the present invention. 1-5 and 9-11 showed high carrier mobility while suppressing abnormal discharge. That is, when sputtering was performed, the occurrence of abnormal discharge was 2 times or less, and it was confirmed that the discharge was stably performed. Moreover, the relative density and specific resistance of the sputtering target thus obtained were also good. The carrier mobility of the thin film was also as high as 15 cm 2 / Vs or higher.

一方、本発明の好ましい組成を満足しないＮｏ．６〜８、及び好ましい製造条件を満足しないＮｏ．１２〜１４については、異常放電が多く発生したり、キャリア移動度が低いなど所望の効果を得ることができなかった。   On the other hand, No. which does not satisfy the preferred composition of the present invention. No. 6-8, and No. that does not satisfy the preferred production conditions. For Nos. 12 to 14, it was impossible to obtain desired effects such as occurrence of many abnormal discharges and low carrier mobility.

具体的には、Ｎｏ．６〜８の組成は、いずれもＩｎとＺｎの比率（［Ｉｎ］／［Ｚｎ］）が、本願規定を外れていた。酸化物焼結体には、Ｚｎ4Ｉｎ2Ｏ7（ｍ＝４）、Ｚｎ8Ｉｎ2Ｏ11（ｍ＝８）が検出された。Ｎｏ．６〜８はキャリア移動度が低かった。なお、Ｎｏ．６のＺｎ4Ｉｎ2Ｏ7の体積比は０．８５であった。Ｎｏ．７のＺｎ8Ｉｎ2Ｏ11の体積比は０．８２であった。Ｎｏ．８のＺｎ4Ｉｎ2Ｏ7の体積比は０．８４であった。 Specifically, no. In the compositions of 6 to 8, the ratio of In to Zn ([In] / [Zn]) was not within the scope of the present application. Zn 4 In 2 O 7 (m = 4) and Zn 8 In 2 O 11 (m = 8) were detected in the oxide sintered body. No. 6-8 had low carrier mobility. In addition, No. The volume ratio of Zn 4 In 2 O 7 of 6 was 0.85. No. The volume ratio of Zn 8 In 2 O 11 of 7 was 0.82. No. The volume ratio of Zn 4 In 2 O 7 of 8 was 0.84.

Ｎｏ．１２、１３はいずれも第一の焼結工程における温度が本発明の規定を外れる例であり、焼結体の相対密度が低く、異常放電の回数が多かった。Ｎｏ．１４は、第二の焼結工程における温度が本発明の規定を外れ、結晶相はＩｎ2Ｏ3を含まず、ほぼＺｎ7Ｉｎ2Ｏ10のみとなっている例であり、異常放電の回数が多かった。 No. Nos. 12 and 13 are examples in which the temperature in the first sintering step deviates from the definition of the present invention. The relative density of the sintered body was low and the number of abnormal discharges was large. No. No. 14 is an example in which the temperature in the second sintering step deviates from the definition of the present invention, the crystal phase does not contain In 2 O 3 and is almost only Zn 7 In 2 O 10 , and the number of abnormal discharges There were many.

Claims (3)

酸化亜鉛と；酸化インジウムと；Ｔｉ、Ｍｇ、Ａｌ、およびＮｂよりなる群から選択される少なくとも１種の金属の酸化物と、を混合および焼結して得られる酸化物焼結体であって、
前記酸化物焼結体をＸ線回折したとき、ＺｎmＩｎ2Ｏ3+m（ｍは５〜７の整数）相を主相とし、Ｉｎ2Ｏ3、及びＺｎＯの各結晶相を含むと共に、相対密度８５％以上、比抵抗０．１Ω・ｃｍ以下であり、
前記酸化物焼結体に含まれる金属元素の含有量（原子％）をそれぞれ、［Ｚｎ］、［Ｉｎ］、［Ｔｉ］、［Ｍｇ］、［Ａｌ］、および［Ｎｂ］としたとき、［Ｚｎ］に対する［Ｉｎ］の比、［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］に対する［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］の比は、それぞれ下式を満足し、
前記酸化物焼結体に含まれる前記Ｚｎ m Ｉｎ 2 Ｏ 3+m 、前記Ｉｎ 2 Ｏ 3 、及び前記ＺｎＯの合計に対する各結晶相の体積比は、下式を満足することを特徴とする酸化物焼結体。
０．２７≦［Ｉｎ］／［Ｚｎ］≦０．４５
（［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）／（［Ｚｎ］＋［Ｉｎ］＋［Ｔｉ］＋［Ｍｇ］＋［Ａｌ］＋［Ｎｂ］）≦０．１
Ｚｎ m Ｉｎ 2 Ｏ 3+m ／（Ｚｎ m Ｉｎ 2 Ｏ 3+m ＋Ｉｎ 2 Ｏ 3 ＋ＺｎＯ）≧０．７５
０．００５≦Ｉｎ 2 Ｏ 3 ／（Ｚｎ m Ｉｎ 2 Ｏ 3+m ＋Ｉｎ 2 Ｏ 3 ＋ＺｎＯ）≦０．１５
０．００５≦ＺｎＯ／（Ｚｎ m Ｉｎ 2 Ｏ 3+m ＋Ｉｎ 2 Ｏ 3 ＋ＺｎＯ）≦０．２０
（但し、Ｚｎ m Ｉｎ 2 Ｏ 3+m はＺｎ 5 Ｉｎ 2 Ｏ 8 、Ｚｎ 6 Ｉｎ 2 Ｏ 9 、Ｚｎ 7 Ｉｎ 2 Ｏ 10 の合計である。） An oxide sintered body obtained by mixing and sintering zinc oxide; indium oxide; and an oxide of at least one metal selected from the group consisting of Ti, Mg, Al, and Nb. ,
When the oxide sintered body is subjected to X-ray diffraction, the main phase is a Zn m In 2 O 3 + m (m is an integer of 5 to 7) phase, and each crystal phase of In 2 O 3 and ZnO is included. a relative density of 85% or more state, and are less resistivity 0.1 [Omega · cm,
When the content (atomic%) of the metal element contained in the oxide sintered body is [Zn], [In], [Ti], [Mg], [Al], and [Nb], [ [In] to [Zn], [Ti] + [In] + [Ti] + [Mg] + [Al] + [Nb] to [Ti] + [Mg] + [Al] + [Nb] Satisfy the following formulas,
The volume ratio of each crystal phase to the sum of the Zn m In 2 O 3 + m , In 2 O 3 , and ZnO contained in the oxide sintered body satisfies the following formula: Sintered product.
0.27 ≦ [In] / [Zn] ≦ 0.45
([Ti] + [Mg] + [Al] + [Nb]) / ([Zn] + [In] + [Ti] + [Mg] + [Al] + [Nb])) ≦ 0.1
Zn m In 2 O 3 + m / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≧ 0.75
0.005 ≦ In 2 O 3 / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≦ 0.15
0.005 ≦ ZnO / (Zn m In 2 O 3 + m + In 2 O 3 + ZnO) ≦ 0.20
(However, Zn m In 2 O 3 + m is the total of Zn 5 In 2 O 8 , Zn 6 In 2 O 9 , and Zn 7 In 2 O 10. ) 請求項１に記載の酸化物焼結体を用いて得られるスパッタリングターゲット。 A sputtering target obtained using the oxide sintered body according to claim 1 . 請求項１に記載の酸化物焼結体の製造方法であって、
酸化亜鉛と；酸化インジウムと；Ｔｉ、Ｍｇ、Ａｌ、およびＮｂよりなる群から選択される少なくとも１種の金属の酸化物とを混合し、黒鉛型にセットした後、焼結温度９５０〜１０５０℃、該温度域での保持時間０．１〜５時間で焼結する第一の焼結工程と、
前記第一の焼結工程後、焼結温度１１００〜１２００℃、該温度域での保持時間０．１〜５時間で焼結する第二の焼結工程とを包含すると共に、
前記第一の焼結工程と前記第二の焼結工程を、加圧圧力１００〜５００ｋｇｆ／ｃｍ2で行うことを特徴とする酸化物焼結体の製造方法。 A method for producing the oxide sintered body according to claim 1 ,
Zinc oxide, indium oxide, and an oxide of at least one metal selected from the group consisting of Ti, Mg, Al, and Nb are mixed and set in a graphite mold, and then sintered at 950 to 1050 ° C. A first sintering step of sintering in a holding time of 0.1 to 5 hours in the temperature range;
After the first sintering step, including a sintering temperature of 1100 to 1200 ° C., a second sintering step of sintering at a holding time in the temperature range of 0.1 to 5 hours,
A method for producing an oxide sintered body, wherein the first sintering step and the second sintering step are performed at a pressure of 100 to 500 kgf / cm 2 .
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