JPH03232798A - Method for forming garnet thin film - Google Patents
Method for forming garnet thin filmInfo
- Publication number
- JPH03232798A JPH03232798A JP2584990A JP2584990A JPH03232798A JP H03232798 A JPH03232798 A JP H03232798A JP 2584990 A JP2584990 A JP 2584990A JP 2584990 A JP2584990 A JP 2584990A JP H03232798 A JPH03232798 A JP H03232798A
- Authority
- JP
- Japan
- Prior art keywords
- garnet
- film
- buffer layer
- thin film
- single crystal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000002223 garnet Substances 0.000 title claims abstract description 44
- 239000010409 thin film Substances 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 16
- 239000000758 substrate Substances 0.000 claims abstract description 16
- 239000013078 crystal Substances 0.000 claims abstract description 12
- 238000000151 deposition Methods 0.000 claims abstract description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 16
- 239000010408 film Substances 0.000 abstract description 38
- 238000004544 sputter deposition Methods 0.000 abstract description 12
- 239000000203 mixture Substances 0.000 abstract description 8
- 230000008021 deposition Effects 0.000 abstract 1
- 239000008246 gaseous mixture Substances 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 abstract 1
- 239000000463 material Substances 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 23
- 230000003287 optical effect Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 239000002356 single layer Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000012761 high-performance material Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 150000002910 rare earth metals Chemical group 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- VVTSZOCINPYFDP-UHFFFAOYSA-N [O].[Ar] Chemical compound [O].[Ar] VVTSZOCINPYFDP-UHFFFAOYSA-N 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明はガーネット薄膜の形成方法、さらに詳細には高
度光通信や情報処理に不可欠な光アイソレータや光サー
キュレータや光メモリ−、あるいは空間光変調器に用い
られる高品質なガーネット薄膜の新規な形成方法に関す
るものである。Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for forming a garnet thin film, and more specifically to optical isolators, optical circulators, optical memories, or spatial light modulators essential for advanced optical communications and information processing. The present invention relates to a novel method for forming high-quality garnet thin films used in
（従来の技術）
現在、光アイソレータや光サーキュレータに用いられる
鉄基ガーネット薄膜（−最大
Ｒ３Ｆｅ５Ｏ１２で表され、通常Ｒは希土類や、Ｂｉ等
）は、液相エピタキシャル（ＬＰＥ）法やスパッタ法を
用いて形成されている。(Prior art) Currently, iron-based garnet thin films (-maximum R3Fe5O12, usually R is a rare earth, Bi, etc.) used in optical isolators and optical circulators are produced using liquid phase epitaxial (LPE) method or sputtering method. It is formed by
このガーネット薄膜は、通常、ファラデー回転を利用し
、光を膜面に垂直に透過あるいは膜面内に導波させて用
いるなめ、必要とされる膜厚も１μｍ以下から数百μｍ
までと幅広く、その範囲で膜表面における光散乱を防止
するため、膜表面平滑な良質膜の形成が望まれている。This garnet thin film is usually used by transmitting light perpendicularly to the film surface or by guiding it within the film surface using Faraday rotation, and the required film thickness ranges from less than 1 μm to several hundred μm.
In order to prevent light scattering on the film surface over a wide range of ranges, it is desired to form a high-quality film with a smooth film surface.
一方、その磁気光学的な性能を向上させるために、Ｂｉ
等の元素をガーネット中の希土類元素と置換する試みも
行なわれているが、Ｂｉを高濃度置換するためには、非
熱平衡的形成法であるスパッタ法が有力とされている。On the other hand, in order to improve its magneto-optical performance, Bi
Attempts have been made to replace rare earth elements in garnet with elements such as Bi, but in order to replace Bi at a high concentration, sputtering, which is a non-thermal equilibrium formation method, is considered to be effective.
（発明の解決する問題点）
しかしながら、スパッタ法は、高濃度Ｂｉ置換を実現す
るには確かに適しているが、表面平滑性に優れた良質の
ガーネット薄膜を、高濃度Ｂｉ置換された状態で再現性
よく形成するには問題があった。(Problems to be Solved by the Invention) However, although the sputtering method is certainly suitable for realizing high-concentration Bi substitution, it cannot produce a high-quality garnet thin film with excellent surface smoothness in a high-concentration Bi-substituted state. There was a problem in forming it with good reproducibility.
本発明は、上述の問題点に鑑みなされたものであり、表
面平滑性に優れた良質のガーネット薄膜を再現性よく提
供することを目的とする。The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a high-quality garnet thin film with excellent surface smoothness with good reproducibility.
（問題を解決するための手段）
かかる目的を達成するために、本発明の形成方法は、ス
パッタ法によってガーネット薄膜を形成する際、ガーネ
ット単結晶基板上に、あらかじめ薄くバッファ層を堆積
させ、その上にガーネット薄膜を形成することを特徴と
し、そのバッファ層がガーネットからなり、その形成温
度が、その上に堆積されるガーネット膜形成時の温度よ
り高いことを特徴とする。(Means for solving the problem) In order to achieve the above object, the formation method of the present invention involves depositing a thin buffer layer on a garnet single crystal substrate in advance when forming a garnet thin film by sputtering, and depositing a thin buffer layer on the garnet single crystal substrate. It is characterized in that a garnet thin film is formed thereon, the buffer layer is made of garnet, and its formation temperature is higher than the temperature at which the garnet film is formed to be deposited thereon.
（作用）
本発明による形成法によれば、高濃度Ｂｉ置換ガーネッ
ト等の高性能材料薄膜でも、スパッタ法を用いて、再現
性よく表面平滑性に優れた状態で形成できるという利点
がある。(Function) The forming method according to the present invention has the advantage that even a thin film of a high-performance material such as high-concentration Bi-substituted garnet can be formed with good reproducibility and excellent surface smoothness using a sputtering method.
この結果、膜面に垂直に入射した透過光の散乱損失、お
よび光導波時の散乱損失を低減できる効果もある。As a result, it is possible to reduce the scattering loss of transmitted light incident perpendicularly to the film surface and the scattering loss during optical waveguide.
（発明の詳細な説明） 本発明をさらに詳しく説明する。(Detailed description of the invention) The present invention will be explained in more detail.
本発明においては、ガーネット単結晶基板上に、バッフ
ァ層を形成し、さらにガーネット薄膜を形成する。In the present invention, a buffer layer is formed on a garnet single crystal substrate, and a garnet thin film is further formed.
本発明に使用されるガーネット単結晶基板は、本発明に
おいて基本的に限定されるものではない。The garnet single crystal substrate used in the present invention is not fundamentally limited in the present invention.
例えば、後述の実施例１に示したＮ ＧＯ（１１１）基
板１本実施例３でも示した
ＳＧＧ（Ｓｍ３Ｇａ５０ｔ２）やＧＧＧ（Ｇｄ３Ｇａ５
０１２）、あるいはそれらに他の元素を添加した基板で
あっても同様な効果が得られる。For example, one NGO (111) substrate shown in Example 1, described later, SGG (Sm3Ga50t2) or GGG (Gd3Ga5) shown in Example 3,
012) or a substrate to which other elements are added can also produce similar effects.
バッファ層およびガーネット薄膜は本発明において基本
的に限定されるものではない、以下の実施例においては
、実施例１のＢｉ完全置換組成の場合を特に詳細に説明
したが、Ｂｉが入っていないガーネット膜、あるいは本
実施例６に示したような希土類サイトにＹ以外のＧｄ、
Ｃｅ等が入ったガーネット膜、あるいは鉄サイトをＡＩ
、Ｇａ等他の元素で置換したガーネット膜の形成におい
ても同様に形成方法が有効である。The buffer layer and the garnet thin film are not fundamentally limited in the present invention.In the following examples, the case of the Bi-completely substituted composition of Example 1 is explained in detail, but the garnet without Bi is used. Gd other than Y in the film or the rare earth site as shown in Example 6,
AI garnet film containing Ce etc. or iron site
The same formation method is also effective for forming garnet films substituted with other elements such as , Ga, etc.
一般にバッファ層の形成温度と、上地のガーネット薄膜
の形成温度の差は、好ましくは５０〜２５０℃である。Generally, the difference between the formation temperature of the buffer layer and the formation temperature of the overlying garnet thin film is preferably 50 to 250°C.
５０℃未満であると、バッファ層を設けた効果が発揮し
にくく、一方２５０℃を越えると、かえって膜表面が荒
れる恐れがあるからである。If the temperature is less than 50°C, the effect of providing the buffer layer will be difficult to exhibit, while if it exceeds 250°C, the film surface may become rougher.
しかも、そのバッファ層の膜厚としては、１〜１１００
ｎの範囲にあることが望ましい、それがｌｎｍ未満では
、単層膜と同じく再現性、表面平滑性に問題があった。Moreover, the thickness of the buffer layer is 1 to 1100.
It is desirable that n be in the range; if it is less than 1 nm, there will be problems in reproducibility and surface smoothness as with a single layer film.
同様に、それが１１００ｎをこえると、単層膜と同じく
表面平滑性が悪化するためである。Similarly, if it exceeds 1100n, the surface smoothness deteriorates as in a single layer film.
しかもその形成法は、ここで特に説明したＥＣＲスパッ
タ法に限らず、ｒｆ２極スパッタ法や、本実施例８に示
したマグネトロンスパッタ法等の通常のスパッタ法で形
成する場合でも有効である。Furthermore, the formation method is not limited to the ECR sputtering method specifically explained here, but is also effective when forming by ordinary sputtering methods such as the RF two-pole sputtering method and the magnetron sputtering method shown in Example 8.
（実施例） 第１表に本発明の実施例をまとめて示した。(Example) Table 1 summarizes examples of the present invention.
以下、実施例１を例にとり、詳細に説明する。Hereinafter, a detailed explanation will be given using Example 1 as an example.
真空槽をあらかじめ、ｌＸｌ０”Ｔｏｒｒ以下に排気し
た後、アルゴン−酸素混合ガスを真空槽に導入しガス圧
を３Ｘ１０’Ｔｏｒｒに設定する。After the vacuum chamber is previously evacuated to below 1X10'' Torr, argon-oxygen mixed gas is introduced into the vacuum chamber and the gas pressure is set at 3X10'' Torr.
Ｂ１４Ｆｅ５０ｔ２の組成をもつ焼結体をターゲ ット
として、ＥＣＲスパッタ装置を用いて膜の形成を行なう
。A film is formed using an ECR sputtering device, targeting a sintered body having a composition of B14Fe50t2.
ガーネット単結晶基板として、化学洗浄した２インチ径
の（１１１）面ＮＧＧ
（Ｎｄ３Ｇｄ５０ｘ２） を用い、真空中で酸素プラ
ズマクリーニング処理を施した後、まず基板温度を５５
０℃に設定し、２ｎｍの厚さに第１層を形成する。As a garnet single crystal substrate, a chemically cleaned (111)-plane NGG (Nd3Gd50x2) with a diameter of 2 inches was used, and after oxygen plasma cleaning treatment was performed in a vacuum, the substrate temperature was first lowered to 55%.
The temperature is set to 0° C., and a first layer is formed to a thickness of 2 nm.
次に、この層をバッファ層として、基板温度を４００℃
に設定した後、このバッファ層上に連続して８００ｎｍ
の厚さに同じガーネット膜を形成した。Next, using this layer as a buffer layer, the substrate temperature was raised to 400°C.
800 nm continuously on this buffer layer.
A garnet film with the same thickness was formed.
このようにして得られた膜は、はぼ、
Ｂｉ３Ｆｅ５Ｏ１２の化学量論組成（Ｂｉ完全置換組成
）を持つガーネット単結晶であった。第１図にこの成長
法により得られたガーネット薄膜の模式図を示す。The film thus obtained was a garnet single crystal having a stoichiometric composition (Bi complete substitution composition) of Bi3Fe5O12. FIG. 1 shows a schematic diagram of a garnet thin film obtained by this growth method.
この図より明らかなようにガーネット単結晶基板（ＮＧ
Ｏ）１状にバッファ層
（Ｂｉ３Ｆｅ５Ｏ１２） ２が設けられ、このバラ
ファ層２上にさらにガーネット膜
（Ｂｉ３Ｆｅ５Ｏ１２） が形成された構造になっ
ている。As is clear from this figure, garnet single crystal substrate (NG
O) A buffer layer (Bi3Fe5O12) 2 is provided in the shape of
The structure is such that a garnet film (Bi3Fe5O12) is further formed on the F layer 2.
ing.
一方、単純にＮＧＯ（１１１）基板上に形成した場合で
も、単結晶膜が得られるが（比較例１）、先に説明した
実施例１の膜は、この比較例１の単層膜に比べてはるか
に平滑な表面モホロジーを有している。第２図はバッフ
ァ層の有無による膜表面モホロジーの差異を示した１２
０００倍の顕微鏡写真である。（ａ）が実施例１の膜に
、（ｂ）が比較例１の単層膜に相当している。On the other hand, even when simply formed on an NGO (111) substrate, a single crystal film can be obtained (Comparative Example 1); and has a much smoother surface morphology. Figure 2 shows the difference in film surface morphology depending on the presence or absence of a buffer layer12
This is a micrograph at a magnification of 1,000 times. (a) corresponds to the film of Example 1, and (b) corresponds to the single-layer film of Comparative Example 1.
この第２図の顕微鏡写真より明らかなように、本発明の
表面モホロジーは従来のものに比較して良好な特性を示
すことがわかった。As is clear from the micrograph in FIG. 2, the surface morphology of the present invention was found to exhibit better characteristics than the conventional one.
この膜の面内に波長１．５５μｍの光を導波させた場合
、散乱損失は３５ｄＢ／ｃｍとなり、導波型の磁気光学
的性能指数（ファラデー回転角／損失）は約１１００ｄ
ｅ／ｄＢとなった。バッファ層を持たない単層膜は、散
乱損失が大きすぎて光は全く導波できなかった。このよ
うに、バッファ層の設定によって、表面平滑性の高い良
質なガーネット薄膜が得られるようになった。When light with a wavelength of 1.55 μm is guided within the plane of this film, the scattering loss is 35 dB/cm, and the magneto-optical figure of merit (Faraday rotation angle/loss) of the waveguide type is approximately 1100 d.
It became e/dB. In a single-layer film without a buffer layer, the scattering loss was so large that light could not be guided at all. In this way, by setting the buffer layer, it became possible to obtain a high-quality garnet thin film with high surface smoothness.
このようなバッファ層による膜表面平滑化の効果は、先
のＢｉ完全置換膜を形成する場合、膜形成温度３６０℃
から６００℃の範囲の膜において認められた。ただしバ
ッファ層の形成温度は膜形成温度よりもより高いことが
必要であった。The effect of smoothing the film surface by such a buffer layer is due to the film formation temperature of 360°C when forming the above-mentioned Bi complete replacement film.
It was observed in membranes at temperatures ranging from to 600°C. However, the formation temperature of the buffer layer needed to be higher than the film formation temperature.
−ｉにバッファ層の形成温度が高い程、その上に形成す
る膜の表面平滑性が向上する０例えば、４００℃で先の
Ｂｉ完全置換膜を形成する場合、バッファ層の形成温度
は４５０℃から６５０℃の間に設定した方が好ましい、
形成温度が４５０℃未満では、バッファ層の効果がなく
、４５０℃以上６５０℃以下では高温であるほど表面平
滑性が向上し、６５０℃を越える温度ではかえって膜表
面が荒れるためである。-i: The higher the formation temperature of the buffer layer, the better the surface smoothness of the film formed thereon0. For example, when forming the above-mentioned Bi complete replacement film at 400°C, the buffer layer formation temperature is 450°C. It is preferable to set the temperature between 650℃ and 650℃.
This is because if the formation temperature is less than 450°C, the buffer layer has no effect, and if the temperature is 450°C or higher and 650°C or lower, the higher the temperature, the better the surface smoothness will be, and if the temperature exceeds 650°C, the film surface will become rougher.
（以下余白）
（発明の効果）
以上説明したように、本発明による形成方法によれば、
高濃度Ｂｉ置換ガーネット等の高性能材料薄膜でも、ス
パッタ法を用いて、再現性よく表面平滑性に優れた状態
で形成できるという利点がある。(The following is a blank space) (Effects of the invention) As explained above, according to the forming method according to the present invention,
Even thin films of high-performance materials such as high-concentration Bi-substituted garnet have the advantage that they can be formed with good reproducibility and excellent surface smoothness using the sputtering method.
この結果、膜面に垂直に入射した透過光の散乱損失、お
よび光導波時の散乱損失を低減できる効果もある。As a result, it is possible to reduce the scattering loss of transmitted light incident perpendicularly to the film surface and the scattering loss during optical waveguide.
第１図は本実施例１に対応した形成法により得られたガ
ーネット薄膜の構造模式図、第２図はバッファ層の有無
による膜表面モホロジーの差異であり、（ａ）が実施例
１のバッファ層がある場合の膜の１２０００倍顕微鏡写
真、（ｂ）が比較例１の単層膜の
１２０００倍顕微鏡写真である。FIG. 1 is a structural schematic diagram of a garnet thin film obtained by the formation method corresponding to Example 1, and FIG. 2 shows the difference in film surface morphology depending on the presence or absence of a buffer layer. A 12,000x microscopic photograph of the film with layers is shown, and (b) is a 12,000x microscopic photograph of the single layer film of Comparative Example 1.
Claims (2)
層を堆積させ、その上にガーネット薄膜を形成すること
を特徴とするガーネット薄膜の形成方法。(1) A method for forming a garnet thin film, which comprises depositing a buffer layer in advance on a garnet single crystal substrate, and forming a garnet thin film thereon.
温度が、その上に堆積されるガーネット薄膜の形成温度
より高いことを特徴とする特許請求の範囲第１項記載の
ガーネット薄膜の形成方法。(2) The method for forming a garnet thin film according to claim 1, wherein the buffer layer is made of garnet and the formation temperature thereof is higher than the formation temperature of the garnet thin film deposited thereon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2584990A JPH03232798A (en) | 1990-02-05 | 1990-02-05 | Method for forming garnet thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2584990A JPH03232798A (en) | 1990-02-05 | 1990-02-05 | Method for forming garnet thin film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03232798A true JPH03232798A (en) | 1991-10-16 |
Family
ID=12177291
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2584990A Pending JPH03232798A (en) | 1990-02-05 | 1990-02-05 | Method for forming garnet thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03232798A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004067813A1 (en) * | 2003-01-29 | 2004-08-12 | Tdk Corporation | Substrate for forming magnetic garnet single-crystal film, optical device and process for producing the same |
| WO2004070091A1 (en) * | 2003-02-04 | 2004-08-19 | Tdk Corporation | Substrate for forming magnetic garnet single-crystal film, process for producing the same, optical device and process for producing the same |
-
1990
- 1990-02-05 JP JP2584990A patent/JPH03232798A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004067813A1 (en) * | 2003-01-29 | 2004-08-12 | Tdk Corporation | Substrate for forming magnetic garnet single-crystal film, optical device and process for producing the same |
| WO2004070091A1 (en) * | 2003-02-04 | 2004-08-19 | Tdk Corporation | Substrate for forming magnetic garnet single-crystal film, process for producing the same, optical device and process for producing the same |
| EP1595979A1 (en) * | 2003-02-04 | 2005-11-16 | TDK Corporation | Substrate for forming magnetic garnet single-crystal film, process for producing the same, optical device and process for producing the same |
| EP1595979A4 (en) * | 2003-02-04 | 2012-05-09 | Tdk Corp | Substrate for forming magnetic garnet single-crystal film, process for producing the same, optical device and process for producing the same |
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