JP3679574B2 - Manufacturing method of ultra-thin niobium and copper single crystal multilayer film - Google Patents
Manufacturing method of ultra-thin niobium and copper single crystal multilayer film Download PDFInfo
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- JP3679574B2 JP3679574B2 JP28855297A JP28855297A JP3679574B2 JP 3679574 B2 JP3679574 B2 JP 3679574B2 JP 28855297 A JP28855297 A JP 28855297A JP 28855297 A JP28855297 A JP 28855297A JP 3679574 B2 JP3679574 B2 JP 3679574B2
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- single crystal
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Description
【０００１】
【発明の属する技術分野】
本発明は、一層あたり５ｎｍ〜１μｍの膜厚でＮｂ層、Ｃｕ層を単結晶で積層し多層膜化する方法に関するものである。
【０００２】
【従来の技術】
真空蒸着によって蒸着中の真空度、基板温度、蒸着速度等を制御することによりサファイア基板上に単結晶Ｎｂ膜を成長させることが知られている。Ｃｕ−Ｎｂ系は、お互いほとんど溶け合わないため、金属多層膜のモデル材料として物性研究に用いられてきた。このＣｕーＮｂ系の金属多層膜は、多層膜スパッター蒸着法や電子ビーム蒸着法により製作されているが、その構造は多結晶である。しかし、従来、金属多層膜の構造および膜厚を正確に計測する方法がないので、厚さ１００ｎｍ以下の制御された薄膜を製造することは困難であった。
【０００３】
【発明が解決しようとする課題】
ナノメータ（ｎｍ）領域の膜厚から成る多層膜材料の物性の研究において、各層の界面の平滑性、膜の結晶構造が多層膜材料の物性に大きく影響する。本発明の課題は、膜厚の制御された高品質な単結晶層から成るＣｕーＮｂ系の多層膜を製造することにある。
【０００４】
【課題を解決しようとするための手段】
本発明は、大きな面積の金属単結晶多層膜を作製する手段として、電子ビーム蒸着法によりサファイア単結晶基板の上に面積の大きいＮｂ単結晶膜を成膜し、その上にＣｕおよびＮｂを蒸着中の基板温度、蒸着速度を制御し、単結晶で積層して多層膜を製作するものである。サファイア基板は、耐熱性、化学的安定性に優れ、１５００℃程度の高温での蒸着ができるため、その基板上に結晶性の高い単結晶膜が製造できる。蒸着は超高真空下で行うため多層膜への不純物の混入を極めて少なく抑えられた。本発明は、膜厚をイオンビーム解析法により０．ｌｎｍの精度で計測できる方法を開発したので、厚さの制御された薄膜の製造が可能となった。
【０００５】
【発明の実施の形態】
超高真空下で電子ビーム蒸着法によりサファイア基板上に基板温度、蒸着速度を制御しＮｂ単結晶の成膜を行った。さらにＮｂ膜上にＣｕの単結晶膜の積層を行った。製作した多層膜は低速電子回折、Ｘ線回折、ラザフオード後方散乱法を用いて構造解析を行った。
【０００６】
即ち、本発明は、１．０×ｌ０-6ｔｏｒｒより低い高真空下で、電子ビーム蒸着法により、サファイア基板上に薄膜の蒸着速度を０．０５〜１ｎｍ／秒に制御し、厚さが５ｎｍ（ナノメータ）から１μｍの範囲に制御されたニオブ（Ｎｂ）と鋼（Ｃｕ）の単結晶多層膜を製造するものである。
【０００７】
基板温度としては、蒸着により、サファイア基板上にＮｂ単結晶薄膜を形成させる場合の基板温度は５００℃〜９００℃に制御され、又Ｃｕ単結晶上にＮｂ単結晶膜を形成させる場合のＣｕ基板温度は４５０℃〜８００℃に制御され、更に又Ｎｂ単結晶上にＣｕ単結晶を形成させる場合のＮｂ基板温度は、３０℃〜５００℃に制御される。以下、本発明を実施例に基づいて説明する。
【０００８】
【実施例１】
基板導入室、成長室、分析室の３つの真空容器から構成される電子ビーム蒸着装置を用いてＮｂーＣｕ系単結晶多層膜の製造を行った。モリブデン製の基板ホルダーに取り付けた大きさ１０ｍｍ×１０ｍｍのサファイア単結晶基板
【数１】
【０００９】
蒸着後に基板温度を１時間かけてを２００℃まで下げ１５分間保持した後に真空度８×１０-9ｔｏｒｒで基板温度２００℃、蒸着速度０．ｌｎｍ／秒で５００秒間で５０ｎｍの膜厚のＣｕ膜を蒸着した。その後、基板温度を１５分間で５００℃まで上げ１０分間保持した後に真空度４×１０-8ｔｏｒｒで基板温度５００℃、蒸着速度０．１ｎｍ／秒で５００秒間の蒸着で膜厚５０ｎｍのＮｂ膜の蒸着を行った。
【００１０】
その後、基板温度を１時間で室温まで下げた。この試料を分析室に移動し低速電子回折測定を行った。電子の回折スポットの対称性から最表面のＮｂ膜の結晶面方位はＮｂ（１１０）面であることを確認した。この各層の厚さが５０ｎｍのＮｂ／Ｃｕ／Ｎｂ多層膜の結晶性を２．７ＭｅＶ4Ｈｅイオンを用いたラザフオード後方散乱・チャネリグ法により評価した。最表面のＮｂ層は完全結晶に対して８９％の結晶性の単結晶であることを確認した。
【００１１】
以上の成膜条件で厚さ５０ｎｍのＮｂ膜だけの場合の結晶性、および各層が５０ｎｍから成る２層膜（Ｃｕ／Ｎｂ／基板）のＣｕ膜の結晶性は、完全結晶に対してそれぞれ９９．５％および９５％の単結晶であることを確認した。以上の試料をＸ線回折法（θ‐２θ）により結晶面方位を調べた結果、Ｃｕ（１１１）面およびＮｂ（１１０）面の成長が確認できた。
【００１２】
【実施例２】
実施例１と同様の条件で基板温度の条件を６００℃、７００℃、８００℃として厚さ１０ｎｍのＮｂ膜をサファイア単結晶基板上に作製し、実施例１と同様にＮｂ膜の結晶性を評価した。基板温度が７００℃、８００℃で蒸着した試料の結晶性は完全結晶に対して９９．５％の結晶性であること確認した。６００℃の試料は７００℃の試料に比べて結晶性が２３％低下していた。
【００１３】
実施例１と同様の条件で、厚さ５０ｎｍのＮｂ膜をサファイア単結晶基板上に作製し、その上に室温（３０℃）、１００℃、２００℃の基板温度条件で蒸着速度０．１ｎｍ／秒で５００秒間蒸着し、厚さ５０ｎｍのＣｕ膜を作製した。実施例１と同様な評価を行った結果、Ｃｕ層の結晶性は完全結晶に対して６９％（室温）、８０％（１００℃）、９０％（２００℃）であることを確認した。
【００１４】
実施例１と同様の条件で、サファイア単結晶基板上にＮｂ：５０ｎｍの蒸着膜、Ｃｕ：５０ｎｍの蒸着膜を作製し、その上に室温（３０℃）、４００℃、６００℃の基板温度条件で蒸着速度０．１ｎｍ／秒で５００秒間蒸着し、５０ｎｍの膜厚のＮｂ膜を作製した。実施例１と同様な評価を行った結果、最表面のＮｂ層の結晶性は完全結晶に対して１８％（室温）、５４％（４００℃）、９１％（６００℃）であることを確認した。
【００１５】
【発明の効果】
本発明により得られた、単結晶で積層した ＣｕーＮｂ系多層膜は、金属人工格子等の新しい材料や多層膜ミラー等の光学材料の開発に用いられる。また、本発明においては、電子ビーム蒸着法を用いているため蒸着基板をマスキングすることによりあらゆる形状の単結晶多層膜の製造できる。更にまた、この高品位なＮｂ単結晶膜の上には、Ｃｕを含めた他の金属元素のエピタキシャル膜を形成することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a multilayer film by laminating a Nb layer and a Cu layer with a single crystal at a film thickness of 5 nm to 1 μm per layer.
[0002]
[Prior art]
It is known to grow a single crystal Nb film on a sapphire substrate by controlling the degree of vacuum during deposition, the substrate temperature, the deposition rate, and the like by vacuum deposition. Since Cu—Nb systems hardly dissolve each other, they have been used for physical property studies as model materials for metal multilayer films. This Cu—Nb-based metal multilayer film is manufactured by a multilayer film sputtering deposition method or an electron beam deposition method, but its structure is polycrystalline. However, conventionally, since there is no method for accurately measuring the structure and film thickness of the metal multilayer film, it has been difficult to produce a controlled thin film having a thickness of 100 nm or less.
[0003]
[Problems to be solved by the invention]
In the study of physical properties of a multilayer film material having a film thickness in the nanometer (nm) region, the smoothness of the interface of each layer and the crystal structure of the film greatly affect the physical properties of the multilayer film material. An object of the present invention is to produce a Cu—Nb-based multilayer film composed of a high-quality single crystal layer with a controlled film thickness.
[0004]
[Means for solving problems]
In the present invention, as a means for producing a metal single crystal multilayer film having a large area, an Nb single crystal film having a large area is formed on a sapphire single crystal substrate by electron beam evaporation, and Cu and Nb are vapor-deposited thereon. The substrate temperature and vapor deposition rate are controlled, and a multilayer film is manufactured by laminating single crystals. Since the sapphire substrate is excellent in heat resistance and chemical stability and can be deposited at a high temperature of about 1500 ° C., a single crystal film having high crystallinity can be manufactured on the substrate. Vapor deposition was performed under ultra-high vacuum, so that contamination of impurities into the multilayer film was extremely reduced. In the present invention, the film thickness is reduced to 0.1 by the ion beam analysis method. Since a method capable of measuring with an accuracy of 1 nm was developed, it was possible to manufacture a thin film with a controlled thickness.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An Nb single crystal was formed on the sapphire substrate by controlling the substrate temperature and the deposition rate under an ultrahigh vacuum by an electron beam deposition method. Further, a Cu single crystal film was stacked on the Nb film. The fabricated multilayer film was subjected to structural analysis using low-energy electron diffraction, X-ray diffraction, and Razaford backscattering.
[0006]
That is, the present invention controls the deposition rate of a thin film on a sapphire substrate to 0.05 to 1 nm / second by an electron beam deposition method under a high vacuum lower than 1.0 × 10 −6 torr, A single crystal multilayer film of niobium (Nb) and steel (Cu) controlled in the range of 5 nm (nanometer) to 1 μm is manufactured.
[0007]
As the substrate temperature, the substrate temperature when the Nb single crystal thin film is formed on the sapphire substrate by vapor deposition is controlled to 500 ° C. to 900 ° C., and the Cu substrate when the Nb single crystal film is formed on the Cu single crystal. The temperature is controlled to 450 ° C. to 800 ° C., and the Nb substrate temperature when forming a Cu single crystal on the Nb single crystal is controlled to 30 ° C. to 500 ° C. Hereinafter, the present invention will be described based on examples.
[0008]
[Example 1]
An Nb—Cu-based single crystal multilayer film was manufactured using an electron beam evaporation apparatus composed of three vacuum vessels, ie, a substrate introduction chamber, a growth chamber, and an analysis chamber. 10 mm x 10 mm sapphire single crystal substrate attached to a molybdenum substrate holder
[0009]
After the deposition, the substrate temperature is lowered to 200 ° C. over 1 hour and held for 15 minutes, and then the substrate temperature is 200 ° C. at a degree of vacuum of 8 × 10 −9 torr, the deposition rate is 0. A Cu film having a thickness of 50 nm was deposited at a rate of 1 nm / second for 500 seconds. Thereafter, the substrate temperature is raised to 500 ° C. over 15 minutes and held for 10 minutes, and then the Nb film having a film thickness of 50 nm is deposited by vapor deposition for 500 seconds at a substrate temperature of 500 ° C. and a deposition rate of 0.1 nm / second at a vacuum degree of 4 × 10 −8 torr. The vapor deposition was performed.
[0010]
Thereafter, the substrate temperature was lowered to room temperature in 1 hour. The sample was moved to the analysis chamber and low-energy electron diffraction measurement was performed. From the symmetry of the electron diffraction spot, it was confirmed that the crystal plane orientation of the outermost Nb film was the Nb (110) plane. The crystallinity of the Nb / Cu / Nb multilayer film having a thickness of 50 nm for each layer was evaluated by the Razaford backscattering and channeling method using 2.7 MeV 4 He ions. The outermost Nb layer was confirmed to be 89% crystalline single crystal with respect to the complete crystal.
[0011]
The crystallinity in the case of only the Nb film having a thickness of 50 nm under the above-described film formation conditions and the crystallinity of the Cu film of the two-layer film (Cu / Nb / substrate) each having a thickness of 50 nm are 99% with respect to the complete crystal. .5% and 95% single crystals were confirmed. As a result of examining the crystal plane orientation of the above sample by the X-ray diffraction method (θ-2θ), growth of the Cu (111) plane and the Nb (110) plane could be confirmed.
[0012]
[Example 2]
A Nb film having a thickness of 10 nm was formed on a sapphire single crystal substrate under the same conditions as in Example 1 and the substrate temperature conditions were 600 ° C., 700 ° C., and 800 ° C. The crystallinity of the Nb film was changed as in Example 1. evaluated. It was confirmed that the crystallinity of the sample deposited at substrate temperatures of 700 ° C. and 800 ° C. was 99.5% of the complete crystal. The 600 ° C. sample had 23% lower crystallinity than the 700 ° C. sample.
[0013]
A Nb film having a thickness of 50 nm is formed on a sapphire single crystal substrate under the same conditions as in Example 1, and a deposition rate of 0.1 nm / min is obtained on the substrate temperature conditions of room temperature (30 ° C.) , 100 ° C., and 200 ° C. Vapor deposition was performed for 500 seconds to produce a Cu film having a thickness of 50 nm. As a result of performing the same evaluation as in Example 1, it was confirmed that the crystallinity of the Cu layer was 69% (room temperature), 80% (100 ° C.), and 90% (200 ° C.) with respect to the complete crystal.
[0014]
Under the same conditions as in Example 1, an Nb: 50 nm vapor deposition film and a Cu: 50 nm vapor deposition film were produced on a sapphire single crystal substrate, and substrate temperature conditions of room temperature (30 ° C.) , 400 ° C., and 600 ° C. were formed thereon. Was deposited for 500 seconds at a deposition rate of 0.1 nm / second to produce a Nb film with a thickness of 50 nm. As a result of performing the same evaluation as in Example 1, it was confirmed that the crystallinity of the outermost Nb layer was 18% (room temperature), 54% (400 ° C.), and 91% (600 ° C.) with respect to the complete crystal. did.
[0015]
【The invention's effect】
The Cu—Nb-based multilayer film obtained by the present invention and laminated with a single crystal is used for the development of new materials such as metal artificial lattices and optical materials such as multilayer mirrors. In the present invention, since the electron beam evaporation method is used, single crystal multilayer films of any shape can be manufactured by masking the evaporation substrate. Furthermore, an epitaxial film of other metal elements including Cu can be formed on the high-quality Nb single crystal film.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28855297A JP3679574B2 (en) | 1997-10-21 | 1997-10-21 | Manufacturing method of ultra-thin niobium and copper single crystal multilayer film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28855297A JP3679574B2 (en) | 1997-10-21 | 1997-10-21 | Manufacturing method of ultra-thin niobium and copper single crystal multilayer film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11116379A JPH11116379A (en) | 1999-04-27 |
| JP3679574B2 true JP3679574B2 (en) | 2005-08-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28855297A Expired - Fee Related JP3679574B2 (en) | 1997-10-21 | 1997-10-21 | Manufacturing method of ultra-thin niobium and copper single crystal multilayer film |
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| JP (1) | JP3679574B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4761090B2 (en) * | 2000-08-14 | 2011-08-31 | 独立行政法人 日本原子力研究開発機構 | Method for producing epitaxial multilayer film for soft X-ray mirror |
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| Publication number | Publication date |
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| JPH11116379A (en) | 1999-04-27 |
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