JP5884001B1 - Oxide sintered body and sputtering target comprising the oxide sintered body - Google Patents
Oxide sintered body and sputtering target comprising the oxide sintered body Download PDFInfo
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- 238000005477 sputtering target Methods 0.000 title claims description 17
- 239000011701 zinc Substances 0.000 claims abstract description 60
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000001301 oxygen Substances 0.000 claims abstract description 35
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 35
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 21
- 229910052738 indium Inorganic materials 0.000 claims abstract description 21
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 8
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims abstract description 6
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims abstract description 6
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000002245 particle Substances 0.000 claims description 17
- 238000004544 sputter deposition Methods 0.000 abstract description 32
- 239000010408 film Substances 0.000 description 51
- 230000015572 biosynthetic process Effects 0.000 description 16
- 239000000843 powder Substances 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 13
- 238000000034 method Methods 0.000 description 13
- 238000004453 electron probe microanalysis Methods 0.000 description 12
- 238000005259 measurement Methods 0.000 description 11
- 239000011812 mixed powder Substances 0.000 description 11
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 238000009694 cold isostatic pressing Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000010409 thin film Substances 0.000 description 6
- 230000005355 Hall effect Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 5
- 229920002554 vinyl polymer Polymers 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 4
- 229910005191 Ga 2 O 3 Inorganic materials 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 239000011787 zinc oxide Substances 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000001513 hot isostatic pressing Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000007088 Archimedes method Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 229910007541 Zn O Inorganic materials 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 229910003437 indium oxide Inorganic materials 0.000 description 1
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000001552 radio frequency sputter deposition Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 238000003826 uniaxial pressing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
- C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/453—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
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- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3286—Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
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Abstract
インジウム(In)、ガリウム(Ga)、亜鉛(Zn)、酸素(O)及び不可避的不純物からなる酸化物焼結体であって、In、Ga及びZnの原子比でIn:Ga:Zn=1:1:1からなるIGZO(111)相と、IGZO(111)相よりもZnを多く含むIGZO相とを備え、IGZO(111)相よりもZnを多く含むIGZO相が面積比率で1〜10%であり、該酸化物焼結体のIn、Ga及びZnの原子数比が、In:Ga:Zn=1:1:(1.02〜1.10)からなることを特徴とする酸化物焼結体。所望のキャリア濃度を有する膜を得るために必要なスパッタ時の酸素濃度を低減することが可能なIGZO酸化物焼結体を提供することを課題とする。【選択図】図1An oxide sintered body composed of indium (In), gallium (Ga), zinc (Zn), oxygen (O), and inevitable impurities, wherein In: Ga: Zn = 1 at an atomic ratio of In, Ga, and Zn IGZO (111) phase composed of 1: 1, and an IGZO phase containing more Zn than the IGZO (111) phase, and the IGZO phase containing more Zn than the IGZO (111) phase has an area ratio of 1 to 10 The oxide is characterized in that the atomic ratio of In, Ga, and Zn in the oxide sintered body is In: Ga: Zn = 1: 1: (1.02-1.10). Sintered body. It is an object of the present invention to provide an IGZO oxide sintered body capable of reducing the oxygen concentration during sputtering necessary for obtaining a film having a desired carrier concentration. [Selection] Figure 1
Description
本発明は、インジウム(In)、ガリウム(Ga)、亜鉛(Zn)、酸素(O)、及び不可避的不純物からなる酸化物(「IGZO」と一般的に称呼されている。必要に応じて、この「IGZO」を用いて説明する)に関し、特に、IGZO焼結体及び該酸化物焼結体からなるスパッタリングターゲットに関する。 The present invention is generally referred to as oxide ("IGZO") consisting of indium (In), gallium (Ga), zinc (Zn), oxygen (O), and inevitable impurities. In particular, the present invention relates to an IGZO sintered body and a sputtering target made of the oxide sintered body.
従来、FPD(フラットパネルディスプレイ)において、そのバックプレーンのTFT(薄膜トランジスタ)に、α−Si(アモルファスシリコン)が用いられてきた。しかし、α−Siでは十分な電子移動度が得られず、近年では、α−Siよりも電子移動度が高いIn−Ga−Zn−O系酸化物(IGZO)を用いたTFTの研究開発が行われている。そして、IGZO−TFTを用いた次世代高機能フラットパネルディスプレイが一部実用化され、注目を集めている。 Conventionally, in an FPD (flat panel display), α-Si (amorphous silicon) has been used for a TFT (thin film transistor) of the backplane. However, sufficient electron mobility cannot be obtained with α-Si, and in recent years, research and development of TFTs using In—Ga—Zn—O-based oxides (IGZO), which have higher electron mobility than α-Si, have been conducted. Has been done. A part of next-generation high-functional flat panel displays using IGZO-TFTs has been put into practical use and attracting attention.
IGZO膜は、主として、IGZO焼結体から作製されるターゲットをスパッタリングして成膜される。IGZOスパッタリングターゲットとして、例えば、特許文献1には、In、Ga及びZnを含み、周囲よりもInの含有量が多い組織を生成させることで、高温での還元処理を行わなくても、比抵抗の低いターゲットを作製することができることが開示されている。また、特許文献2には、In、Ga、Znを所定の比率で含み、二種以上のホモロガス結晶が共存していることにより、スパッタリングが安定し、パーティクルの発生が低減できることが開示されている。 The IGZO film is mainly formed by sputtering a target made from an IGZO sintered body. As an IGZO sputtering target, for example, Patent Document 1 includes In, Ga, and Zn, and by generating a structure having a higher In content than the surroundings, a specific resistance can be obtained without performing a reduction treatment at a high temperature. It is disclosed that a low target can be produced. Patent Document 2 discloses that when two or more kinds of homologous crystals coexist in a predetermined ratio of In, Ga, and Zn, sputtering is stabilized and generation of particles can be reduced. .
ところで、このようなIGZO膜をTFTの活性層として用いる場合、膜の電気的特性に影響を及ぼす要因のひとつに膜中の酸素欠陥の量がある。この酸素欠陥量を制御するためにスパッタ成膜時にアルゴン等の不活性ガスに加えて酸素ガスを導入することが一般に行われている。酸素のスパッタリング効率はアルゴンよりも低く、スパッタ時に酸素ガスを導入するとスパッタされる原子の量が減少して、成膜レートが低下する。IGZO膜のスパッタ成膜においては、膜のキャリア濃度を所望の値に制御するためには多くの酸素を導入する必要があるため、成膜レートが低下して生産性が低下するという問題があった。 Incidentally, when such an IGZO film is used as an active layer of a TFT, one of the factors affecting the electrical characteristics of the film is the amount of oxygen defects in the film. In order to control the amount of oxygen defects, oxygen gas is generally introduced in addition to an inert gas such as argon during sputtering film formation. The sputtering efficiency of oxygen is lower than that of argon. When oxygen gas is introduced at the time of sputtering, the amount of sputtered atoms is reduced and the film formation rate is lowered. In sputter deposition of an IGZO film, it is necessary to introduce a large amount of oxygen in order to control the carrier concentration of the film to a desired value, which causes a problem that the deposition rate is lowered and productivity is lowered. It was.
本発明は、所望のキャリア濃度を有する膜を得るために必要なスパッタ時の酸素濃度を低減することが可能なIGZO酸化物焼結体を提供することを課題とする。該焼結体からなるスパッタリングターゲットは、スパッタリングレートを高めることができ、生産性を格段に向上させることができる。 An object of the present invention is to provide an IGZO oxide sintered body capable of reducing the oxygen concentration during sputtering necessary for obtaining a film having a desired carrier concentration. The sputtering target made of the sintered body can increase the sputtering rate and can significantly improve the productivity.
上記の課題を解決するために、本発明者らは鋭意研究を行った結果、IGZO焼結体においてZn(亜鉛)の含有量を増やすことで、膜のキャリア濃度を低下させることができ、その結果、スパッタ時の酸素濃度を低減することができるとの知見を得た。本発明者らは上記の知見に基づき、下記の発明を提供する。
1)インジウム(In)、ガリウム(Ga)、亜鉛(Zn)、酸素(O)及び不可避的不純物からなる酸化物焼結体であって、In、Ga及びZnの原子比でIn:Ga:Zn=1:1:1からなるIGZO(111)相と、IGZO(111)相よりもZnを多く含むIGZO相とを備え、IGZO(111)相よりもZnを多く含むIGZO相が面積比率で1〜10%であり、該酸化物焼結体のIn、Ga及びZnの原子数比が、In:Ga:Zn=1:1:(1.02〜1.10)からなることを特徴とする酸化物焼結体。
2)平均粒径が20μm以下であることを特徴とする上記1)記載の酸化物焼結体。
3)バルク抵抗が30mΩcm以下であることを特徴とする上記1)又は2)のいずれか一記載の酸化物焼結体。
4)焼結体密度が6.3g/cm3以上であることを特徴とする上記1)〜3)のいずれか一記載の酸化物焼結体。
5)上記1)〜4)のいずれか一に記載の酸化物焼結体から作製されるスパッタリングターゲット。In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, by increasing the content of Zn (zinc) in the IGZO sintered body, the carrier concentration of the film can be lowered, As a result, it was found that the oxygen concentration during sputtering can be reduced. Based on the above findings, the present inventors provide the following invention.
1) An oxide sintered body composed of indium (In), gallium (Ga), zinc (Zn), oxygen (O), and inevitable impurities, and the atomic ratio of In, Ga, and Zn is In: Ga: Zn. = 1: 1: 1 IGZO (111) phase and an IGZO phase containing more Zn than the IGZO (111) phase, and the area ratio of the IGZO phase containing more Zn than the IGZO (111) phase is 1 The atomic ratio of In, Ga, and Zn of the oxide sintered body is In: Ga: Zn = 1: 1: (1.02-1.10). Oxide sintered body.
2) The oxide sintered body according to 1) above, wherein the average particle size is 20 μm or less.
3) The oxide sintered body according to any one of 1) and 2) above, wherein the bulk resistance is 30 mΩcm or less.
4) The oxide sintered body according to any one of 1) to 3) above, wherein the sintered body density is 6.3 g / cm 3 or more.
5) A sputtering target produced from the oxide sintered body according to any one of 1) to 4) above.
本発明は、インジウム(In)、ガリウム(Ga)、亜鉛(Zn)、酸素(O)、及び不可避的不純物からなるIGZO系の酸化物焼結体において、Znを多く含むIGZO相を備えることにより、所望のキャリア濃度を有する薄膜を形成するために必要なスパッタ時の酸素濃度を低減することができるので、スパッタレートを向上することができるという優れた効果を有する。 The present invention provides an IGZO-based oxide sintered body composed of indium (In), gallium (Ga), zinc (Zn), oxygen (O), and unavoidable impurities, by including an IGZO phase containing a large amount of Zn. Since the oxygen concentration during sputtering necessary for forming a thin film having a desired carrier concentration can be reduced, the sputter rate can be improved.
本発明の酸化物焼結体は、インジウム(In)、ガリウム(Ga)、亜鉛(Zn)、酸素(O)及び不可避的不純物からなり、In、Ga及びZnの原子比でIn:Ga:Zn=1:1:1からなるIGZO(111)相と、IGZO(111)相よりもZnを多く含むIGZO相とを備え、IGZO(111)相よりもZnを多く含むIGZO相が面積比率で1〜10%であることを特徴とする。IGZO(111)相よりZnを多く含むIGZO相(ZnリッチIGZO相)を備えることで、所望のキャリア濃度を有する膜を得るために必要なスパッタ時の酸素濃度を低減することができるので、スパッタレート(成膜レート)を向上することができる。 The oxide sintered body of the present invention comprises indium (In), gallium (Ga), zinc (Zn), oxygen (O), and unavoidable impurities, and has an In: Ga: Zn atomic ratio of In, Ga, and Zn. = 1: 1: 1 IGZO (111) phase and an IGZO phase containing more Zn than the IGZO (111) phase, and the area ratio of the IGZO phase containing more Zn than the IGZO (111) phase is 1 -10%. By providing an IGZO phase (Zn-rich IGZO phase) containing more Zn than the IGZO (111) phase, the oxygen concentration during sputtering necessary for obtaining a film having a desired carrier concentration can be reduced. The rate (deposition rate) can be improved.
Znを多く含む、IGZO相が存在するIGZO焼結体を用いてスパッタ成膜すると、メカニズムは定かでないが、膜のキャリア濃度が低下する。このようなターゲットを用いることにより、所望のキャリア濃度を得るために導入していた酸素ガスの濃度を従来よりも低減することができるので、酸素濃度に起因したスパッタレートの低下を抑えることができる。なお、本発明の酸化物焼結体は、酸素ガス濃度を従来と同等にした場合には、キャリア濃度を低下することができるという効果を有するものであり、スパッタレートの低下が本発明の要件にならないことはいうまでもない。 When a sputter film is formed using an IGZO sintered body containing a large amount of Zn and containing an IGZO phase, the mechanism is not clear, but the carrier concentration of the film decreases. By using such a target, the concentration of oxygen gas introduced to obtain a desired carrier concentration can be reduced as compared with the conventional case, so that a reduction in sputtering rate due to the oxygen concentration can be suppressed. . The oxide sintered body of the present invention has an effect that the carrier concentration can be lowered when the oxygen gas concentration is made equal to the conventional one, and the reduction of the sputtering rate is a requirement of the present invention. Needless to say, it doesn't happen.
IGZO(111)相よりもZnを多く含むIGZO相(ZnリッチIGZO相)は、焼結体において面積比率で1〜10%とするのが好ましい。ZnリッチIGZO相の面積比率が1%未満であると、膜のキャリア濃度低下の効果が十分でなく、一方、ZnリッチIGZO相の面積比率が10%超であると、スパッタして成膜した膜のキャリア濃度が増加することがある。 The IGZO phase (Zn-rich IGZO phase) containing more Zn than the IGZO (111) phase is preferably 1 to 10% in terms of area ratio in the sintered body. When the area ratio of the Zn-rich IGZO phase is less than 1%, the effect of reducing the carrier concentration of the film is not sufficient, while when the area ratio of the Zn-rich IGZO phase is more than 10%, sputtering is performed to form a film. The carrier concentration of the film may increase.
また、本発明において、酸化物焼結体のIn、Ga及びZnの原子比は、In:Ga:Zn=1:1:(1.02〜1.10)であることが好ましい。これにより、Znリッチ相を効率的に生成することができ、膜のキャリア濃度を低下させることができる。Znの原子比が1.02未満であると、膜のキャリア濃度の低下の効果が小さくなる。一方、Znの原子比が1.10超であると、酸化物焼結体がIGZO(111)相単相の場合に比べて、膜のキャリア濃度は低いが、キャリア濃度が増加傾向に転じる。したがって、IGZO焼結体のIn、Ga、Znの原子比は上記数値範囲であることが好ましい。 In the present invention, the atomic ratio of In, Ga, and Zn in the oxide sintered body is preferably In: Ga: Zn = 1: 1: (1.02-1.10). Thereby, a Zn-rich phase can be generated efficiently, and the carrier concentration of the film can be reduced. When the atomic ratio of Zn is less than 1.02, the effect of lowering the carrier concentration of the film is reduced. On the other hand, when the atomic ratio of Zn exceeds 1.10, the carrier concentration of the film starts to increase although the carrier concentration of the film is lower than that in the case where the oxide sintered body is a single phase of IGZO (111) phase. Therefore, the atomic ratio of In, Ga, Zn in the IGZO sintered body is preferably in the above numerical range.
本発明の酸化物焼結体は、平均粒径が20μm以下であることが好ましい。平均粒径を小さくすることで機械的強度を高めることができる。平均粒径が20μm超であると、機械的強度が低下して、スパッタリング時に過度な電力が投入された場合、スパッタリングターゲット(焼結体)と該ターゲットをボンディングしているバッキングプレートの熱膨張差によって生じる応力により、焼結体に割れが発生する可能性がある。 The oxide sintered body of the present invention preferably has an average particle size of 20 μm or less. The mechanical strength can be increased by reducing the average particle size. If the average particle size exceeds 20 μm, the mechanical strength decreases, and if excessive power is applied during sputtering, the thermal expansion difference between the sputtering target (sintered body) and the backing plate bonding the target There is a possibility that cracks may occur in the sintered body due to the stress generated by.
また、本発明の酸化物焼結体は、バルク抵抗が30mΩcm以下であることが好ましい。バルク抵抗が低いとスパッタ中に異常放電が発生する可能性が低くなり、成膜中の膜に悪影響を及ぼすパーティクルの発生を抑制することができる。一方、バルク抵抗が30mΩcm超であると、DCスパッタが可能な場合であっても、長時間のスパッタ中には異常放電が発生することがあり、場合によってはDCでは放電が起こらず、装置的に高コストで、成膜レートも低下するRFスパッタを用いざるを得ないことがある。 The oxide sintered body of the present invention preferably has a bulk resistance of 30 mΩcm or less. If the bulk resistance is low, the possibility of abnormal discharge during sputtering is reduced, and generation of particles that adversely affect the film being formed can be suppressed. On the other hand, if the bulk resistance is more than 30 mΩcm, even if DC sputtering is possible, abnormal discharge may occur during long-time sputtering, and in some cases, no discharge occurs in DC, which is In addition, there is a case where it is necessary to use RF sputtering which is high in cost and reduces the film formation rate.
また、本発明の酸化物焼結体は、焼結体密度が6.3g/cm3以上であることが好ましい。本発明の酸化物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、焼結体の高密度化は、スパッタ膜の均一性を高め、また、スパッタリングの際にパーティクルの発生を著しく低減することができるという優れた効果を有する。The oxide sintered body of the present invention preferably has a sintered body density of 6.3 g / cm 3 or more. When the oxide sintered body of the present invention is used as a sputtering target, densification of the sintered body can increase the uniformity of the sputtered film and can significantly reduce the generation of particles during sputtering. Has an excellent effect.
本発明の酸化物焼結体の製造工程の代表例を示すと、次のようになる。
原料として、酸化インジウム(In2O3)、酸化ガリウム(Ga2O3)、及び酸化亜鉛(ZnO)を用意する。不純物による電気特性への悪影響を避けるため、純度4N以上の原料を用いることが望ましい。各々の原料を所定の組成比となるように秤量する。なお、これらの原料には不可避的に含有される不純物が含まれる。A typical example of the manufacturing process of the oxide sintered body of the present invention is as follows.
Indium oxide (In 2 O 3 ), gallium oxide (Ga 2 O 3 ), and zinc oxide (ZnO) are prepared as raw materials. In order to avoid an adverse effect on electrical characteristics due to impurities, it is desirable to use a raw material having a purity of 4N or higher. Each raw material is weighed so as to have a predetermined composition ratio. These raw materials contain impurities inevitably contained.
次に、酸化物焼結体が所定の組成比となるように、各原料を添加、混合する。このとき混合が不十分であると、ターゲット中の各成分が偏析して、スパッタリング中にアーキング等の異常放電の原因となったり、パーティクル発生の原因となったりするため、混合は十分に行うことが好ましい。さらに、混合粉を微粉砕、造粒することにより、混合粉の成形性及び焼結性を向上させ、高密度の焼結体を得ることができる。混合、粉砕の手段としては、例えば、市販のミキサーやボールミル、ビーズミル等を使用することができ、造粒の手段としては、例えば市販のスプレードライヤーを用いることができる。 Next, each raw material is added and mixed so that the oxide sintered body has a predetermined composition ratio. If mixing is inadequate at this time, each component in the target will segregate, causing abnormal discharge such as arcing during sputtering or particle generation. Is preferred. Furthermore, by finely pulverizing and granulating the mixed powder, the moldability and sinterability of the mixed powder can be improved, and a high-density sintered body can be obtained. As a means for mixing and grinding, for example, a commercially available mixer, a ball mill, a bead mill or the like can be used, and as a means for granulating, for example, a commercially available spray dryer can be used.
次に、混合粉末を金型に充填し、面圧400〜1000kgf/cm2、1〜3分保持の条件で一軸プレスして、成型体を得る。面圧400kgf/cm2未満であると十分な密度の成形体を得ることができない。また、過度な面圧を加えても成形体の密度はある一定の値以上は向上しにくくなること、及び一軸プレスでは原理的に成形体内に密度分布が生じやすく、焼結時の変形や割れの原因となることから、1000kgf/cm2以上の面圧は生産上特に必要とされない。Next, the mixed powder is filled in a mold and uniaxially pressed under conditions of a surface pressure of 400 to 1000 kgf / cm 2 and a hold of 1 to 3 minutes to obtain a molded body. If the surface pressure is less than 400 kgf / cm 2 , a molded body having a sufficient density cannot be obtained. In addition, it is difficult to improve the density of the molded body beyond a certain value even if excessive surface pressure is applied. In principle, density distribution tends to occur in the molded body with uniaxial pressing, and deformation and cracking during sintering Therefore, a surface pressure of 1000 kgf / cm 2 or more is not particularly required for production.
次に、この成型体をビニールで2重に真空パックし、圧力1500〜4000kgf/cm2、1〜3分保持の条件でCIP(冷間等方圧加圧法)を施す。圧力1500kgf/cm2未満であると、十分なCIPの効果を得ることができず、一方4000kgf/cm2以上の圧力を加えても、成形体の密度はある一定の値以上は向上しにくくなるため、4000kgf/cm2以上の面圧は生産上特に必要とされない。Next, this molded body is double-vacuum packed with vinyl and subjected to CIP (cold isostatic pressing) under the conditions of pressure 1500 to 4000 kgf / cm 2 and holding for 1 to 3 minutes. If the pressure is less than 1500 kgf / cm 2 , sufficient CIP effect cannot be obtained. On the other hand, even if a pressure of 4000 kgf / cm 2 or more is applied, the density of the molded body is hardly improved beyond a certain value. Therefore, a surface pressure of 4000 kgf / cm 2 or more is not particularly required for production.
次に、成形体を温度1300〜1500℃、保持時間5〜24時間,大気雰囲気又は酸素雰囲気で焼結を行い、焼結体を得る。焼結温度が1300℃よりも低いと十分な密度の焼結体を得ることができず、焼結温度が1500℃以上であると焼結体中の結晶粒のサイズが大きくなり過ぎて、焼結体の機械的強度を低下させる恐れがある。また保持時間が5時間未満であると十分な密度の焼結体を得ることができず、保持時間が24時間より長いと、生産コストの観点から好ましくない。 Next, the compact is sintered in an air atmosphere or an oxygen atmosphere at a temperature of 1300 to 1500 ° C. and a holding time of 5 to 24 hours to obtain a sintered body. When the sintering temperature is lower than 1300 ° C., a sintered body having a sufficient density cannot be obtained, and when the sintering temperature is 1500 ° C. or higher, the size of the crystal grains in the sintered body becomes too large and the sintered body is sintered. There is a risk of reducing the mechanical strength of the body. Further, if the holding time is less than 5 hours, a sintered body having a sufficient density cannot be obtained, and if the holding time is longer than 24 hours, it is not preferable from the viewpoint of production cost.
また成形・焼結工程においては、上述した方法以外にも、HP(ホットプレス)やHIP(熱間等方圧加圧法)を用いることができる。以上のようにして得られた焼結体は、研削、研磨などの機械加工によりターゲット形状とすることで、スパッタリングターゲットを作成することができる。 In the molding / sintering step, HP (hot press) and HIP (hot isostatic pressing) can be used in addition to the above-described method. The sintered body obtained as described above can be formed into a target shape by machining such as grinding and polishing, whereby a sputtering target can be prepared.
本発明の酸化物半導体膜の作製に際しては、上記のようにして得られたスパッタリングターゲットを、所定の条件でスパッタリングを実施して成膜し、必要に応じて、この膜を所定の温度でアニールすることで、酸化物半導体膜を得ることができる。また、本発明の薄膜トランジスタの作製に際しては、前記酸化物半導体膜を図1に示すようなゲート電極として用いることで、薄膜トランジスタを得ることができる。 In producing the oxide semiconductor film of the present invention, the sputtering target obtained as described above is formed by sputtering under predetermined conditions, and if necessary, this film is annealed at a predetermined temperature. Thus, an oxide semiconductor film can be obtained. In manufacturing the thin film transistor of the present invention, the thin film transistor can be obtained by using the oxide semiconductor film as a gate electrode as shown in FIG.
以下、実施例および比較例に基づいて説明する。なお、本実施例はあくまで一例であり、この例によって何ら制限されるものではない。すなわち、本発明は特許請求の範囲によってのみ制限されるものであり、本発明に含まれる実施例以外の種々の変形を包含するものである。 Hereinafter, description will be made based on Examples and Comparative Examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.
(実施例1)
In2O3粉、Ga2O3粉、ZnO粉を、焼結体の組成比がIn、Ga及びZnの原子比で1.00:1.00:1.02となるように秤量した後、これらの粉末を湿式で混合・微粉砕し、その後、スプレードライヤーで乾燥・造粒して、混合粉末を得た。次に、この混合粉末を面圧400〜1000kgf/cm2で一軸プレスして成形体を得た。次に得られた成形体をビニールで2重に真空パックし、1500〜4000kgf/cm2でCIP成型した後、酸素雰囲気中、温度1430℃で20時間焼結した。Example 1
After weighing In 2 O 3 powder, Ga 2 O 3 powder, and ZnO powder so that the composition ratio of the sintered body is 1.00: 1.00: 1.02 in terms of atomic ratio of In, Ga, and Zn These powders were mixed and finely pulverized by a wet process, and then dried and granulated with a spray dryer to obtain a mixed powder. Next, this mixed powder was uniaxially pressed at a surface pressure of 400 to 1000 kgf / cm 2 to obtain a molded body. Next, the obtained molded body was double vacuum packed with vinyl, CIP molded at 1500 to 4000 kgf / cm 2 , and then sintered in an oxygen atmosphere at a temperature of 1430 ° C. for 20 hours.
このようにして得られたIGZO焼結体のEPMAによる組織写真を図1に示す(図中、白い部分がZnリッチIGZO相に相当する)。EPMAの組織写真から実施例1の焼結体がIGZO(111)相とZnリッチIGZO相から構成されていることを確認した。また、組織写真からZnリッチIGZO相の面積を求め、この組織写真全体の面積との比率からZnリッチIGZO相の面積比率を算出した。その結果、ZnリッチIGZO相の面積比率1.7%であった。
また、焼結体の平均粒径は19.7μmであり、焼結体密度は6.3g/cm3と高密度のものが得られた。さらに、バルク抵抗は30.0mΩcmと低抵抗のものが得られた。以上の結果を表1に示す。なお、平均粒径はコード法により算出し、焼結体密度はアルキメデス法、バルク抵抗は四探針法により求めた。The structure photograph by EPMA of the IGZO sintered body thus obtained is shown in FIG. 1 (in the figure, the white portion corresponds to the Zn-rich IGZO phase). It was confirmed from the structure photograph of EPMA that the sintered body of Example 1 was composed of an IGZO (111) phase and a Zn-rich IGZO phase. Further, the area of the Zn-rich IGZO phase was determined from the structure photograph, and the area ratio of the Zn-rich IGZO phase was calculated from the ratio to the area of the entire structure photograph. As a result, the area ratio of the Zn-rich IGZO phase was 1.7%.
Moreover, the average particle diameter of the sintered body was 19.7 μm, and the sintered body density was as high as 6.3 g / cm 3 . Furthermore, the bulk resistance was as low as 30.0 mΩcm. The results are shown in Table 1. The average particle size was calculated by the code method, the sintered body density was determined by the Archimedes method, and the bulk resistance was determined by the four-probe method.
次に、焼結体を機械加工して、6インチのスパッタリングターゲットに仕上げ、このターゲットを使用してスパッタリングを行った。スパッタ条件は、成膜方法:DCマグネトロンスパッタリング、成膜温度:室温、成膜圧力:0.5Pa(O2+Ar)、投入パワー:2.74W/cm2とし、成膜時の酸素濃度を2vol%、6vol%、10vol%と変えて、それぞれ厚さ約4000Åの膜を成膜した。Next, the sintered body was machined to finish a 6-inch sputtering target, and sputtering was performed using this target. The sputtering conditions were film formation method: DC magnetron sputtering, film formation temperature: room temperature, film formation pressure: 0.5 Pa (O 2 + Ar), input power: 2.74 W / cm 2, and oxygen concentration during film formation was 2 vol. %, 6 vol%, and 10 vol%, respectively, and a film having a thickness of about 4000 mm was formed.
段差計による膜厚測定値と成膜時間からそれぞれの酸素濃度における成膜レートを算出した。その結果を表1及び図4に示す。表1に示すとおり、後述する比較例と比べて若干成膜レートが向上していることを確認した。
また、それぞれの膜について、大気中400℃で1時間アニールし、Hall効果測定により、キャリア濃度とHall移動度を測定した。その結果を表1及び図6に示す。表1に示すとおり、後述する比較例と比べていずれの酸素濃度においてもキャリア濃度が低下していることを確認した。なお、Hall効果の測定には、(株)東陽テクニカ製ResiTest8400を用いた。The film formation rate at each oxygen concentration was calculated from the film thickness measured by the step gauge and the film formation time. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the film formation rate was slightly improved as compared with Comparative Examples described later.
Each film was annealed in the atmosphere at 400 ° C. for 1 hour, and the carrier concentration and Hall mobility were measured by Hall effect measurement. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the carrier concentration was lowered at any oxygen concentration as compared with the comparative example described later. For measurement of the Hall effect, ResiTest 8400 manufactured by Toyo Corporation was used.
(実施例2)
In2O3粉、Ga2O3粉、ZnO粉を、焼結体の組成比がIn、Ga及びZnの原子比で1.00:1.00:1.05となるように秤量した後、これらの粉末を湿式で混合・微粉砕し、その後、スプレードライヤーで乾燥・造粒して、混合粉末を得た。次に、この混合粉末を面圧400〜1000kgf/cm2で一軸プレスして成形体を得た。次に得られた成形体をビニールで2重に真空パックし、1500〜4000kgf/cm2でCIP成型した後、酸素雰囲気中、温度1430℃で20時間焼結した。(Example 2)
After weighing In 2 O 3 powder, Ga 2 O 3 powder, and ZnO powder so that the composition ratio of the sintered body is 1.00: 1.00: 1.05 in terms of atomic ratio of In, Ga, and Zn These powders were mixed and finely pulverized by a wet process, and then dried and granulated with a spray dryer to obtain a mixed powder. Next, this mixed powder was uniaxially pressed at a surface pressure of 400 to 1000 kgf / cm 2 to obtain a molded body. Next, the obtained molded body was double vacuum packed with vinyl, CIP molded at 1500 to 4000 kgf / cm 2 , and then sintered in an oxygen atmosphere at a temperature of 1430 ° C. for 20 hours.
このようにして得られたIGZO焼結体のEPMAによる組織写真を図2に示す(図中、白い部分がZnリッチIGZO相に相当する)。EPMAの組織写真から実施例2の焼結体がIGZO(111)相とZnリッチIGZO相から構成されていることを確認した。また、実施例1と同様の方法で、ZnリッチIGZO相の面積比率を算出した結果、ZnリッチIGZO相の面積比率5.2%であった。
また、焼結体の平均粒径は14.9μmであり、焼結体密度は6.3g/cm3と高密度のものが得られた。さらに、バルク抵抗は23.0mΩcmと低抵抗のものが得られた。以上の結果を表1に示す。なお、平均粒径、焼結体密度、バルク抵抗の測定には、実施例1と同様の方法を用いた。The structure photograph by EPMA of the IGZO sintered body thus obtained is shown in FIG. 2 (in the figure, the white portion corresponds to the Zn-rich IGZO phase). It was confirmed from the structure photograph of EPMA that the sintered body of Example 2 was composed of an IGZO (111) phase and a Zn-rich IGZO phase. Moreover, as a result of calculating the area ratio of the Zn-rich IGZO phase by the same method as in Example 1, the area ratio of the Zn-rich IGZO phase was 5.2%.
Moreover, the average particle diameter of the sintered body was 14.9 μm, and the sintered body had a high density of 6.3 g / cm 3 . Furthermore, the bulk resistance was as low as 23.0 mΩcm. The results are shown in Table 1. In addition, the method similar to Example 1 was used for the measurement of an average particle diameter, a sintered compact density, and bulk resistance.
次に、焼結体を機械加工して、6インチのスパッタリングターゲットに仕上げ、このターゲットを使用してスパッタリングを行った。スパッタ条件は実施例1と同様の条件とした。そして、段差計による膜厚測定値と成膜時間からそれぞれの酸素濃度における成膜レートを算出した。その結果を表1及び図5に示す。表1に示すとおり、後述する比較例と比べて成膜レートが向上していることを確認した。
次に、それぞれの膜について、大気中400℃で1時間アニールし、Hall効果測定により、キャリア濃度とHall移動度を測定した。その結果を表1及び図6に示す。表1に示すとおり、後述する比較例と比べていずれの酸素濃度においてもキャリア濃度が低下していることを確認した。Next, the sintered body was machined to finish a 6-inch sputtering target, and sputtering was performed using this target. The sputtering conditions were the same as in Example 1. And the film-forming rate in each oxygen concentration was computed from the film-thickness measurement value by a level difference meter, and film-forming time. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the film formation rate was improved as compared with Comparative Examples described later.
Next, each film was annealed in the atmosphere at 400 ° C. for 1 hour, and the carrier concentration and Hall mobility were measured by Hall effect measurement. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the carrier concentration was lowered at any oxygen concentration as compared with the comparative example described later.
(実施例3)
In2O3粉、Ga2O3粉、ZnO粉を、焼結体の組成比がIn、Ga及びZnの原子比で1.00:1.00:1.10となるように秤量した後、これらの粉末を湿式で混合・微粉砕し、その後、スプレードライヤーで乾燥・造粒して、混合粉末を得た。次に、この混合粉末を面圧400〜1000kgf/cm2で一軸プレスして成形体を得た。次に得られた成形体をビニールで2重に真空パックし、1500〜4000kgf/cm2でCIP成型した後、酸素雰囲気中、温度1430℃で20時間焼結した。(Example 3)
After weighing In 2 O 3 powder, Ga 2 O 3 powder, and ZnO powder so that the composition ratio of the sintered body is 1.00: 1.00: 1.10 in terms of atomic ratio of In, Ga, and Zn These powders were mixed and finely pulverized by a wet process, and then dried and granulated with a spray dryer to obtain a mixed powder. Next, this mixed powder was uniaxially pressed at a surface pressure of 400 to 1000 kgf / cm 2 to obtain a molded body. Next, the obtained molded body was double vacuum packed with vinyl, CIP molded at 1500 to 4000 kgf / cm 2 , and then sintered in an oxygen atmosphere at a temperature of 1430 ° C. for 20 hours.
このようにして得られたIGZO焼結体のEPMAによる組織写真を図3に示す(図中、白い部分がZnリッチIGZO相に相当する)。EPMAの組織写真から実施例3の焼結体がIGZO(111)相とZnリッチIGZO相から構成されていることを確認した。また、実施例1と同様の方法で、ZnリッチIGZO相の面積比率を算出した結果、ZnリッチIGZO相の面積比率9.8%であった。
また、焼結体の平均粒径は8.9μmであり、焼結体密度は6.3g/cm3と高密度のものが得られた。さらに、バルク抵抗は21.0mΩcmと低抵抗のものが得られた。以上の結果を表1に示す。なお、平均粒径、焼結体密度、バルク抵抗の測定には、実施例1と同様の方法を用いた。The structure photograph by EPMA of the IGZO sintered body thus obtained is shown in FIG. 3 (in the figure, the white portion corresponds to the Zn-rich IGZO phase). From the structure photograph of EPMA, it was confirmed that the sintered body of Example 3 was composed of an IGZO (111) phase and a Zn-rich IGZO phase. Moreover, as a result of calculating the area ratio of the Zn-rich IGZO phase by the same method as in Example 1, the area ratio of the Zn-rich IGZO phase was 9.8%.
Moreover, the average particle diameter of the sintered body was 8.9 μm, and the sintered body density was as high as 6.3 g / cm 3 . Furthermore, the bulk resistance was as low as 21.0 mΩcm. The results are shown in Table 1. In addition, the method similar to Example 1 was used for the measurement of an average particle diameter, a sintered compact density, and bulk resistance.
次に、焼結体を機械加工して、6インチのスパッタリングターゲットに仕上げ、このターゲットを使用してスパッタリングを行った。スパッタ条件は実施例1と同様の条件とした。そして、段差計による膜厚測定値と成膜時間からそれぞれの酸素濃度における成膜レートを算出した。その結果を表1及び図5に示す。表1に示すとおり、後述する比較例と比べて成膜レートが向上していることを確認した。
次に、それぞれの膜について、大気中400℃で1時間アニールし、Hall効果測定により、キャリア濃度とHall移動度を測定した。その結果を表1及び図6に示す。表1に示すとおり、後述する比較例と比べていずれの酸素濃度においてもキャリア濃度が低下していることを確認した。Next, the sintered body was machined to finish a 6-inch sputtering target, and sputtering was performed using this target. The sputtering conditions were the same as in Example 1. And the film-forming rate in each oxygen concentration was computed from the film-thickness measurement value by a level difference meter, and film-forming time. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the film formation rate was improved as compared with Comparative Examples described later.
Next, each film was annealed in the atmosphere at 400 ° C. for 1 hour, and the carrier concentration and Hall mobility were measured by Hall effect measurement. The results are shown in Table 1 and FIG. As shown in Table 1, it was confirmed that the carrier concentration was lowered at any oxygen concentration as compared with the comparative example described later.
(比較例)
In2O3粉、Ga2O3粉、ZnO粉を、焼結体の組成比がIn、Ga及びZnの原子比で1.00:1.00:1.00となるように秤量した後、これらの粉末を湿式で混合・微粉砕し、その後、スプレードライヤーで乾燥・造粒して、混合粉末を得た。次に、この混合粉末を面圧400〜1000kgf/cm2で一軸プレスして成形体を得た。次に得られた成形体をビニールで2重に真空パックし、1500〜4000kgf/cm2でCIP成型した後、酸素雰囲気中、温度1430℃で20時間焼結した。
(Comparative example)
After weighing In 2 O 3 powder, Ga 2 O 3 powder, and ZnO powder so that the composition ratio of the sintered body is 1.00: 1.00: 1.00 as the atomic ratio of In, Ga, and Zn These powders were mixed and finely pulverized by a wet process, and then dried and granulated with a spray dryer to obtain a mixed powder. Next, this mixed powder was uniaxially pressed at a surface pressure of 400 to 1000 kgf / cm 2 to obtain a molded body. Next, the obtained molded body was double vacuum packed with vinyl, CIP molded at 1500 to 4000 kgf / cm 2 , and then sintered in an oxygen atmosphere at a temperature of 1430 ° C. for 20 hours.
このようにして得られたIGZO焼結体のEPMAによる組織写真を図4に示す(図中、白い部分がZnリッチIGZO相に相当する)。EPMAの組織写真から比較例の焼結体がIGZO(111)相のみから構成されていることを確認した。
また、焼結体の平均粒径は24.6μmであり、焼結体密度は6.3g/cm3であった。さらに、バルク抵抗は37.3mΩcmであった。以上の結果を表1に示す。なお、平均粒径、焼結体密度、バルク抵抗の測定には、実施例1と同様の方法を用いた。The structure photograph by EPMA of the IGZO sintered body thus obtained is shown in FIG. 4 (in the figure, the white portion corresponds to the Zn-rich IGZO phase). It confirmed that the sintered compact of the comparative example was comprised only from the IGZO (111) phase from the structure | tissue photograph of EPMA.
The average particle size of the sintered body was 24.6 μm, and the sintered body density was 6.3 g / cm 3 . Furthermore, the bulk resistance was 37.3 mΩcm. The results are shown in Table 1. In addition, the method similar to Example 1 was used for the measurement of an average particle diameter, a sintered compact density, and bulk resistance.
次に、焼結体を機械加工して、6インチのスパッタリングターゲットに仕上げ、このターゲットを使用してスパッタリングを行った。スパッタ条件は実施例1と同様の条件とした。そして、段差計による膜厚測定値と成膜時間からそれぞれの酸素濃度における成膜レートを算出した。その結果を表1及び図5に示す。表1に示すとおり、実施例に比べて成膜レートは低い結果となった。次に、それぞれの膜について、大気中400℃で1時間アニールし、Hall効果測定により、キャリア濃度とHall移動度を測定した。その結果を表1及び図6に示す。表1に示すとおり、実施例に比べてキャリア濃度が高い結果となった。 Next, the sintered body was machined to finish a 6-inch sputtering target, and sputtering was performed using this target. The sputtering conditions were the same as in Example 1. And the film-forming rate in each oxygen concentration was computed from the film-thickness measurement value by a level difference meter, and the film-forming time. The results are shown in Table 1 and FIG. As shown in Table 1, the film formation rate was lower than that of the example. Next, each film was annealed in the atmosphere at 400 ° C. for 1 hour, and the carrier concentration and Hall mobility were measured by Hall effect measurement. The results are shown in Table 1 and FIG. As shown in Table 1, the carrier concentration was higher than that of the example.
以上の結果から、実施例のZn組成1.02、1.05、1.10のいずれにおいても、比較例のZn組成1.00に比べてキャリア濃度の低下を確認できた。比較例ではキャリア濃度をあるレベル以下(例えば、1e+15cm−3以下)に下げるには酸素濃度を10%以上とする必要があるが、実施例1〜3では2%で十分であることが分かる。さらに、同じ酸素濃度で成膜した場合であっても、実施例の方が比較例よりもやや成膜レートが高いため、所望のキャリア濃度(一般的なTFTでは、膜のキャリア濃度は1e+15cm−3前後からそれ以下)の膜を得るために酸素を増やす必要がなく、高い成膜レートを維持することができる。From the above results, in any of the Zn compositions 1.02, 1.05, and 1.10 of the examples, a decrease in carrier concentration was confirmed as compared with the Zn composition 1.00 of the comparative example. In the comparative example, the oxygen concentration needs to be 10% or more to lower the carrier concentration below a certain level (for example, 1e +15 cm −3 or less), but in Examples 1 to 3, 2% is sufficient. I understand. Further, even when the film is formed at the same oxygen concentration, the film formation rate in the example is slightly higher than that in the comparative example, so that the desired carrier concentration (in a general TFT, the carrier concentration of the film is 1e +15 It is not necessary to increase oxygen in order to obtain a film of about 3 cm -3 or less, and a high film formation rate can be maintained.
本発明の酸化物焼結体は、スパッタリングターゲットとすることができ、このスパッタリングターゲットを使用してスパッタ成膜する場合、スパッタリング雰囲気中の酸素濃度を低減することができるので、スパッタレート(成膜レート)を向上することができる。したがって、このようなスパッタリングターゲットを用いることで、酸化物半導体膜及び薄膜トランジスタを、安定的に量産することができるという優れた効果を有する。本発明の酸化物半導体膜は、特にフラットパネルディスプレイやフレキシブルパネルディスプレイなどのバックプレーンにおけるTFTの活性層として有用である。
The oxide sintered body of the present invention can be used as a sputtering target. When sputtering film formation is performed using this sputtering target, the oxygen concentration in the sputtering atmosphere can be reduced. Rate) can be improved. Therefore, the use of such a sputtering target has an excellent effect that the oxide semiconductor film and the thin film transistor can be stably mass-produced. The oxide semiconductor film of the present invention is particularly useful as an active layer of a TFT in a backplane such as a flat panel display or a flexible panel display.
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