JPH0891986A - Production of single crystal substrate product - Google Patents
Production of single crystal substrate productInfo
- Publication number
- JPH0891986A JPH0891986A JP22208794A JP22208794A JPH0891986A JP H0891986 A JPH0891986 A JP H0891986A JP 22208794 A JP22208794 A JP 22208794A JP 22208794 A JP22208794 A JP 22208794A JP H0891986 A JPH0891986 A JP H0891986A
- Authority
- JP
- Japan
- Prior art keywords
- film
- single crystal
- substrate
- temperature
- crystal substrate
- 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.)
- Granted
Links
- 239000000758 substrate Substances 0.000 title claims abstract description 110
- 239000013078 crystal Substances 0.000 title claims abstract description 86
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 239000007791 liquid phase Substances 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 35
- 239000006104 solid solution Substances 0.000 claims description 33
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 14
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 4
- 229910052744 lithium Inorganic materials 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 239000010408 film Substances 0.000 description 116
- 239000000155 melt Substances 0.000 description 24
- 230000003287 optical effect Effects 0.000 description 18
- 230000015572 biosynthetic process Effects 0.000 description 15
- 239000000203 mixture Substances 0.000 description 15
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 11
- 239000010409 thin film Substances 0.000 description 11
- 238000005530 etching Methods 0.000 description 10
- 239000007790 solid phase Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 7
- 229910018068 Li 2 O Inorganic materials 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 230000002269 spontaneous effect Effects 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 230000005684 electric field Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、強誘電性単結晶基板を
備えた単結晶基板品の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a single crystal substrate product having a ferroelectric single crystal substrate.
【０００２】[0002]
【従来の技術】ニオブ酸リチウム（ＬｉＮｂＯ3 ) 単結
晶、タンタル酸リチウム（ＬｉＴａＯ3 ）単結晶が、オ
プトエレクトロニクス用材料として期待されている。液
相エピタキシャル法は、引き上げ法に比べて、低温で単
結晶膜を作成することができるので、結晶性の良い高品
質の薄膜を形成する方法として期待されている。例え
ば、「Journal of Crystal Growth 」４６（１９７９
年）の第３１４頁〜３２２頁の記載によれば、タンタル
酸リチウム単結晶基板上に液相エピタキシャル法によっ
てニオブ酸リチウム─タンタル酸リチウム固溶体膜を作
成している。「Applied Physics Letters 」 Vol.26 N
o.1 (1975)の第８〜１０頁の記載によれば、タンタル酸
リチウム単結晶基板上に液相エピタキシャル法によって
ニオブ酸リチウム単結晶薄膜を形成している。2. Description of the Related Art Lithium niobate (LiNbO 3 ) single crystal and lithium tantalate (LiTaO 3 ) single crystal are expected as materials for optoelectronics. Since the liquid phase epitaxial method can form a single crystal film at a lower temperature than the pulling method, it is expected as a method of forming a high quality thin film having good crystallinity. For example, “Journal of Crystal Growth” 46 (1979)
, Pp. 314 to 322, a lithium niobate-lithium tantalate solid solution film is formed on a lithium tantalate single crystal substrate by a liquid phase epitaxial method. "Applied Physics Letters" Vol.26 N
According to the description on pages 8 to 10 of o.1 (1975), a lithium niobate single crystal thin film is formed on a lithium tantalate single crystal substrate by a liquid phase epitaxial method.
【０００３】液相エピタキシャル法における成膜方法の
概略を説明する。まず、例えばニオブ酸リチウム（溶
質）とＬｉＶＯ3 （溶融媒体）とを仕込んで混合する。
この溶融体の仕込み組成に対応する飽和温度をＴ0 とす
る。この溶融体の温度を、飽和温度Ｔ0 よりも高温Ｔ1
で保持し、ニオブ酸リチウムとＬｉＶＯ3 とを均一に溶
融させる。次いで、溶融体の温度を、飽和温度Ｔ0 より
も低い温度まで冷却して、溶融体を過冷却状態とする。
過冷却状態の溶融体に対して、基板を接触させる。特
に、液相エピタキシャル法によって、単結晶基板よりも
高い屈折率を有する単結晶膜を形成し、この単結晶膜を
光導波路とする、光導波路基板の製造方法が、高品質光
導波路デバイスの製造方法として注目されている。An outline of a film forming method in the liquid phase epitaxial method will be described. First, for example, lithium niobate (solute) and LiVO 3 (melting medium) are charged and mixed.
The saturation temperature corresponding to the composition of the melt charged is T 0 . The temperature of the melt is higher than the saturation temperature T 0 by T 1
Hold, and lithium niobate and LiVO 3 are uniformly melted. Next, the temperature of the melt is cooled to a temperature lower than the saturation temperature T 0 to bring the melt into a supercooled state.
The substrate is brought into contact with the melt in the supercooled state. In particular, a method for manufacturing an optical waveguide substrate, in which a single crystal film having a higher refractive index than that of the single crystal substrate is formed by a liquid phase epitaxial method and the single crystal film is used as an optical waveguide, is a method for manufacturing a high-quality optical waveguide device. It is attracting attention as a method.
【０００４】しかし、前記した従来技術においては、い
ずれもタンタル酸リチウム単結晶基板を使用している
が、タンタル酸リチウム単結晶は、キュリー温度が約６
００℃であり、液相エピタキシャル法における成膜温度
は、７００℃以上である。従って、単分域化処理された
単結晶基板を使用しても、成膜を終えた後には基板が多
分域化してしまい、同時に膜の方も多分域化してしまう
ので、高品質の膜を作成することが困難であった。しか
も、このように多分域化した薄膜を光デバイスとして使
用するためには、再度単分域化処理を行う必要がある
が、この単分域化処理の段階で薄膜の結晶性にダメージ
を与えてしまう。However, in the above-mentioned conventional techniques, the lithium tantalate single crystal substrate is used in all cases, but the lithium tantalate single crystal has a Curie temperature of about 6.
The temperature is 00 ° C., and the film formation temperature in the liquid phase epitaxial method is 700 ° C. or higher. Therefore, even if a single-crystal substrate subjected to single-domain processing is used, the substrate becomes multi-domain after film formation, and at the same time, the film also becomes multi-domain, so that a high-quality film is obtained. It was difficult to create. Moreover, in order to use such a multi-domain thin film as an optical device, it is necessary to perform the single-domain processing again, but at the stage of this single-domain processing, the crystallinity of the thin film is damaged. Will end up.
【０００５】最近、液相エピタキシャル法により、５ｍ
ｏｌ％のＭｇＯをドープしたＬｉＮｂＯ3 基板の上に、
Ｌｉ2 Ｏ3 ─Ｂ2 Ｏ3 系溶融媒体を使用してＬｉＮｂＯ
3 膜を形成する方法が開示された（「Journal of Cryst
al Growth 」１３２（１９９３年）第４８〜６０頁）。Recently, by liquid phase epitaxial method,
On a LiNbO 3 substrate doped with ol% MgO,
Li 2 O 3 --B 2 O 3 based melt medium
A method for forming three films was disclosed (see "Journal of Cryst
al Growth "132 (1993) 48-60).
【０００６】[0006]
【発明が解決しようとする課題】こうした方法によれ
ば、ＬｉＮｂＯ3 単結晶基板のキュリー温度は約１２０
０℃であり、成膜温度においても基板の結晶性が十分に
安定しており、多分域化することはないので、この点で
は有利なはずであった。しかし、この方法によっても、
単結晶膜の多分域化という問題は、解決することはでき
ないことが判明してきた。即ち、ＬｉＮｂＯ3 基板上に
ＬｉＮｂＯ3薄膜を形成するわけであるが、基板におい
ては単分域状態が保持されるものの、形成されてくる薄
膜中においては、ドメインが不安定になったり、また多
分域化することがわかった。この結果、やはり薄膜中に
おける結晶性が不安定になって高品質の単結晶膜を形成
することが難しく、また結局は膜の単分域化処理が必要
となる。According to such a method, the Curie temperature of the LiNbO 3 single crystal substrate is about 120.
Since it was 0 ° C., the crystallinity of the substrate was sufficiently stable even at the film forming temperature, and it probably did not become a region, it should have been advantageous in this respect. However, this method also
It has been found that the problem of multi-domain single crystal film cannot be solved. That is, a LiNbO 3 thin film is formed on a LiNbO 3 substrate. Although a single domain state is maintained on the substrate, the domain becomes unstable in the formed thin film, and maybe the thin film is formed. It turned out that it would become regionalized. As a result, the crystallinity in the thin film becomes unstable, and it is difficult to form a high-quality single crystal film, and eventually the film needs to be divided into single domains.
【０００７】本発明の課題は、単分域状態にある強誘電
性単結晶基板上に強誘電性単結晶膜を液相エピタキシャ
ル法によって形成するのに際して、成膜後においても、
強誘電性単結晶基板の単分域状態を維持するのと共に、
単分域状態の単結晶膜を形成できるようにすることであ
る。An object of the present invention is to form a ferroelectric single crystal film on a ferroelectric single crystal substrate in a single domain state by a liquid phase epitaxial method, even after the film formation.
While maintaining the single domain state of the ferroelectric single crystal substrate,
The purpose is to be able to form a single crystal film in a single domain state.
【０００８】[0008]
【課題を解決するための手段】本発明は、強誘電性単結
晶基板とこの上に形成された強誘電性単結晶膜とを備え
ている単結晶基板品を製造する方法であって、強誘電性
単結晶基板上に強誘電性単結晶膜を液相エピタキシャル
法によって形成するのに際して、強誘電性単結晶基板の
キュリー温度が液相エピタキシャル法における成膜温度
よりも高く、この成膜温度が、強誘電性単結晶膜のキュ
リー温度以上であることを特徴とする。The present invention is a method for producing a single crystal substrate product comprising a ferroelectric single crystal substrate and a ferroelectric single crystal film formed thereon, the method comprising the steps of: When the ferroelectric single crystal film is formed on the dielectric single crystal substrate by the liquid phase epitaxial method, the Curie temperature of the ferroelectric single crystal substrate is higher than the film forming temperature in the liquid phase epitaxial method. Is higher than the Curie temperature of the ferroelectric single crystal film.
【０００９】[0009]
【作用】前記したように、ＬｉＮｂＯ3 基板上にＬｉＮ
ｂＯ3 薄膜を形成した場合にも、基板においては単分域
状態が保持されるものの、形成されてくる薄膜中におい
ては、ドメインが不安定になったり、また多分域化する
ことが判明している。本発明者は、この点について更に
検討した。As described above, as described above, LiNbO 3 substrate is coated with LiN
Even when a bO 3 thin film is formed, it has been found that the domain is unstable in the formed thin film and the domain is multiparted in the formed thin film, although the single domain state is maintained in the substrate. There is. The present inventor further examined this point.
【００１０】前記した文献によれば、Ｌｉ2 Ｏ3 ─Ｂ2
Ｏ3 系およびＬｉ2 Ｏ3─Ｖ2 Ｏ5 系のいずれの溶融媒
体においても、ドメインの不安定性が見られる。これ
は、膜と基板との間に生ずる自発分極の相違によって引
き起こされる内部自己分極場によるものと、説明されて
いる。基板の自発分極は一定である。しかし、成膜温度
が変化すると、膜の方の自発分極も変化する。膜と基板
との自発分極が相違すると、内部電界が引き起こされ
る。この内部電界の作用によって、ドメインが反転した
り、不安定になるものと推定されている。According to the documents mentioned above, Li 2 O 3 --B 2
Also in O 3 system and Li 2 O 3 ─V 2 O 5 system either molten media, instability domain is observed. This is explained to be due to an internal self-polarizing field caused by the difference in spontaneous polarization between the film and the substrate. The spontaneous polarization of the substrate is constant. However, when the film forming temperature changes, the spontaneous polarization of the film also changes. The difference in spontaneous polarization between the film and the substrate causes an internal electric field. It is presumed that the domain is inverted or becomes unstable due to the action of this internal electric field.
【００１１】本発明者は、こうした系について検討した
が、やはり単分域状態の膜を安定して得ることはできな
かった。The present inventor examined such a system, but was still unable to stably obtain a single domain membrane.
【００１２】そこで、強誘電性単結晶基板の方はＬｉＮ
ｂＯ3 基板を使用して、液相エピタキシャルの際におけ
る基板のドメインの反転を防止しつつ、膜の組成を、タ
ンタル酸リチウムまたはニオブ酸リチウム─タンタル酸
リチウム固溶体に変更してみた。これは、従来は、溶解
度の関係から困難であるとされてきた組み合わせであ
る。Therefore, the ferroelectric single crystal substrate is LiN
Using a bO 3 substrate, the composition of the film was changed to lithium tantalate or lithium niobate-lithium tantalate solid solution while preventing domain inversion of the substrate during liquid phase epitaxial growth. This is a combination that has hitherto been difficult due to the solubility.
【００１３】この結果、意外にも、ニオブ酸リチウム単
結晶基板上に、相当に広い組成範囲で上記の固溶体膜を
作成できることがわかった。そして、この結果、単分域
状態の単結晶膜を安定して形成できることが判明した。
更に、膜の組成を選択して、強誘電性単結晶の成膜温度
を、強誘電性単結晶膜のキュリー温度以上とすること
で、単分域状態の単結晶膜を安定して形成できることを
発見し、本発明に到達した。As a result, it was surprisingly found that the above solid solution film can be formed on a lithium niobate single crystal substrate in a considerably wide composition range. As a result, it has been found that a single crystal film in a single domain state can be stably formed.
Further, by selecting the composition of the film and setting the film formation temperature of the ferroelectric single crystal to the Curie temperature of the ferroelectric single crystal film or higher, the single crystal film in the single domain state can be stably formed. And has reached the present invention.
【００１４】[0014]
【実施例】膜の組成については、ニオブ酸リチウム─タ
ンタル酸リチウム固溶体が一層好ましい。この際、Ｌｉ
Ｎｂ1-x Ｔａx Ｏ3 の組成式において、ｘが０．８以下
であるものが、作成し易さの点で更に好ましい。また、
ｘは０．１以上であるものが、膜と基板とのキュリー温
度の差を確保するために、好ましい。EXAMPLE Regarding the composition of the film, lithium niobate-lithium tantalate solid solution is more preferable. At this time, Li
In the composition formula of Nb 1-x Ta x O 3 , those in which x is 0.8 or less are more preferable from the viewpoint of easy production. Also,
It is preferable that x is 0.1 or more in order to secure the difference in Curie temperature between the film and the substrate.
【００１５】強誘電性単結晶基板のキュリー温度は、成
膜温度よりも１０℃以上高いことが好ましい。実際の成
膜過程においては、成膜装置内の対流等によって温度の
ゆらぎがあるため、この温度差が１０℃未満であると、
製品の歩留りが低下してくるからである。また、同様の
理由から、成膜温度が、強誘電性単結晶膜のキュリー温
度よりも１０℃以上高いことが好ましい。基板を接触さ
せるための溶融体は、主としてＬｉ2 Ｏ、Ｖ2 Ｏ5 、Ｎ
ｂ2 Ｏ5およびＴａ2 Ｏ5 からなる。Ｌｉ2 Ｏの仕込み
量は、Ｖ2 Ｏ5 、Ｎｂ2 Ｏ5 およびＴａ2 Ｏ5 の仕込み
量の合計（モル数）にほぼ等しくなるように調合する。The Curie temperature of the ferroelectric single crystal substrate is preferably higher than the film forming temperature by 10 ° C. or more. In the actual film forming process, there is temperature fluctuation due to convection in the film forming apparatus, so if the temperature difference is less than 10 ° C.,
This is because the product yield will decrease. For the same reason, the film forming temperature is preferably higher than the Curie temperature of the ferroelectric single crystal film by 10 ° C. or more. The melt for contacting the substrate is mainly Li 2 O, V 2 O 5 , N
It consists of b 2 O 5 and Ta 2 O 5 . The amount of Li 2 O charged is adjusted so as to be substantially equal to the total (number of moles) of V 2 O 5 , Nb 2 O 5 and Ta 2 O 5 .
【００１６】本発明の単結晶基板品は、各種の光部品の
基材として広範に使用できるものである。こうした光部
品としては、例えば、光通信等で用いる光外部変調器、
光スイッチ、光増幅器、光ピックアップ等で用いるＳＨ
Ｇ素子、光計測装置に用いる光ファイバージャイロ用の
光集積回路等を挙げることができる。The single crystal substrate product of the present invention can be widely used as a base material for various optical components. Examples of such optical components include, for example, an optical external modulator used in optical communication,
SH used in optical switches, optical amplifiers, optical pickups, etc.
Examples include G elements, optical integrated circuits for optical fiber gyros used in optical measuring devices, and the like.
【００１７】なお、本発明で形成する単結晶膜中に、ド
ープ成分として、マグネシウム、ネオジム、ユーロピウ
ム、亜鉛、チタンおよびバナジウムからなる群より選ば
れた一種以上の元素を添加することも可能である。It is also possible to add, as a doping component, one or more elements selected from the group consisting of magnesium, neodymium, europium, zinc, titanium and vanadium into the single crystal film formed in the present invention. .
【００１８】以下、更に具体的な実験結果について述べ
る。各実施例、比較例で使用した基板は、光学グレード
のＺカットのニオブ酸リチウム単結晶基板である。この
基板のキュリー温度は約１１５０℃であった。また、こ
の基板のＸ線ロッキングカーブの半値幅は、成膜前の段
階においては、いずれも６．８〜６．９秒であった。こ
れを、成膜後の基板および膜の結晶性の基準とした。Hereinafter, more specific experimental results will be described. The substrate used in each example and comparative example is an optical grade Z-cut lithium niobate single crystal substrate. The Curie temperature of this substrate was about 1150 ° C. Further, the half width of the X-ray rocking curve of this substrate was 6.8 to 6.9 seconds before the film formation. This was used as a reference for the crystallinity of the substrate and film after film formation.
【００１９】また、ここで、Ｘ線ロッキングカーブの半
値幅について説明する。単結晶基板及び固溶体膜の結晶
性は、Ｘ線ロッキングカーブの半値幅によって評価する
ことができる。一般に、この半値幅が小さいほど、単結
晶の結晶性が良好であると判断できる。この値そのもの
は、Ｘ線測定装置において使用する基準結晶等によって
変動するので、絶対値を特定することはできない。The full width at half maximum of the X-ray rocking curve will be described. The crystallinity of the single crystal substrate and the solid solution film can be evaluated by the half width of the X-ray rocking curve. In general, it can be judged that the smaller the half width is, the better the crystallinity of the single crystal is. This value itself varies depending on the reference crystal or the like used in the X-ray measuring apparatus, and therefore the absolute value cannot be specified.
【００２０】しかし、液相エピタキシャル法により作製
される固溶体膜の結晶性は、単結晶基板の結晶性の影響
を強く受ける。従って、作製した固溶体膜の結晶性の優
劣を判断するには、使用した基板のＸ線ロッキングカー
ブの半値幅を基準にしなければならない。特に、光学グ
レードのニオブ酸リチウム単結晶基板は、現在引き上げ
法によって作成されているので、固溶体膜のＸ線ロッキ
ングカーブの半値幅が、光学グレードのニオブ酸リチウ
ム単結晶基板のそれよりも小さいことが好ましい。However, the crystallinity of the solid solution film produced by the liquid phase epitaxial method is strongly influenced by the crystallinity of the single crystal substrate. Therefore, in order to judge the superiority or inferiority of the crystallinity of the produced solid solution film, the half width of the X-ray rocking curve of the substrate used must be used as a reference. In particular, since the optical grade lithium niobate single crystal substrate is currently prepared by the pulling method, the full width at half maximum of the X-ray rocking curve of the solid solution film must be smaller than that of the optical grade lithium niobate single crystal substrate. Is preferred.
【００２１】Ｘ線ロッキングカーブの半値幅の測定は、
二結晶法により、（００12）面の反射を用いて行った。
入射Ｘ線としてはＣｕＫα１を使用し、モノクロメータ
としては、ＧａＡｓ単結晶の（４２２）面を用いた。The full width at half maximum of the X-ray rocking curve is measured by
The double crystal method was used with reflection of the (001 2) plane.
CuKα1 was used as the incident X-ray, and the (422) plane of GaAs single crystal was used as the monochromator.
【００２２】（実施例１）ＬｉＮｂＯ3 ─ＬｉＴａＯ3
─ＬｉＶＯ3 擬三元系の溶融体を使用して、ニオブ酸リ
チウム単結晶基板上に膜を形成した。溶融体を、十分に
高い温度（１２００°Ｃ）で３時間以上攪拌し、十分均
一な液相の状態とした。その後、溶融体を保持温度１０
２０℃まで冷却した後、１２時間以上保持し、過飽和分
の固溶体が核発生して固相が析出するまで待った。この
とき、溶融体の液相部分は、保持温度１０２０℃におけ
る飽和状態であり、溶融体内は、液相部分と、固溶体か
らなる固相部分とが共存した状態である。Example 1 LiNbO 3 --LiTaO 3
A film was formed on a lithium niobate single crystal substrate using a LiVO 3 pseudo-ternary melt. The melt was stirred at a sufficiently high temperature (1200 ° C) for 3 hours or more to obtain a sufficiently homogeneous liquid phase. Then, the melt is held at a holding temperature of 10
After cooling to 20 ° C., the temperature was maintained for 12 hours or more, and waited until a supersaturated solid solution was nucleated and a solid phase was precipitated. At this time, the liquid phase part of the melt is in a saturated state at a holding temperature of 1020 ° C., and the melt phase is a state in which the liquid phase part and the solid phase part made of a solid solution coexist.
【００２３】その後、溶融体の温度を、１０２０℃から
過冷却度２０℃だけ低い成膜温度１０００℃まで冷却
し、ただちに前記基板を、前記の液相部分に接触させ、
固溶体からなる膜を形成した。Then, the temperature of the melt is cooled from 1020 ° C. to a film forming temperature of 1000 ° C., which is lower by a supercooling degree of 20 ° C., and the substrate is immediately brought into contact with the liquid phase portion,
A film of solid solution was formed.
【００２４】得られた固溶体膜は、ＬｉＮｂ0.6 Ｔａ
0.4 Ｏ3 の組成を有していた。このキュリー温度は９４
０℃であった。The obtained solid solution film was LiNb 0.6 Ta.
It had a composition of 0.4 O 3 . This Curie temperature is 94
It was 0 ° C.
【００２５】作成した膜と基板との分域構造を、エッチ
ングによって確認した。エッチング技術によって分域構
造をチェックできることは、知られている。なぜなら、
−Ｚおよび−Ｙ端面が深いエッチングパターンを示して
おり、＋Ｚおよび＋Ｙ端面は、ほとんどエッチングパタ
ーンを示さないからである。基板および膜の表面を光学
研磨し、ＨＦ１に対して硝酸２を配合したエッチング液
を使用し、１１０℃で１分間エッチングした。この表面
を微分干渉顕微鏡によって観察した。The domain structure between the formed film and the substrate was confirmed by etching. It is known that the domain structure can be checked by etching techniques. Because
This is because the -Z and -Y end faces show a deep etching pattern, and the + Z and + Y end faces hardly show an etching pattern. The surfaces of the substrate and the film were optically polished, and etching was performed at 110 ° C. for 1 minute using an etching solution in which nitric acid 2 was mixed with HF1. The surface was observed by a differential interference microscope.
【００２６】この結果、膜および基板の双方ともに、単
分域構造であることが判明した。As a result, it was found that both the film and the substrate had a single domain structure.
【００２７】また、成膜後の基板の前記半値幅を測定し
たが、６．８秒であった。更に、基板上に形成した固溶
体膜の前記半値幅を測定したが、５．６秒であった。The full width at half maximum of the substrate after film formation was measured and found to be 6.8 seconds. Further, the full width at half maximum of the solid solution film formed on the substrate was measured and found to be 5.6 seconds.
【００２８】このように、本発明の方法によれば、単結
晶基板については、成膜前と比較して、単結晶基板の結
晶性の劣化はまったく見られないことが分かる。また、
基板の単分域状態も良好に保持されている。しかも、こ
うした光学グレードの基板の方よりも結晶性が良好であ
る単結晶膜を形成することができた。しかも、注目すべ
きことに、この単結晶膜は、単分域状態の膜として形成
されていた。As described above, according to the method of the present invention, it can be seen that the single crystal substrate does not show any deterioration in crystallinity as compared with that before film formation. Also,
The single domain state of the substrate is also well maintained. Moreover, it was possible to form a single crystal film having better crystallinity than the optical grade substrate. Notably, this single crystal film was formed as a single domain film.
【００２９】（実施例２）ＬｉＮｂＯ3 ─ＬｉＴａＯ3
─ＬｉＶＯ3 擬三元系の溶融体を使用して、ニオブ酸リ
チウム単結晶基板上に膜を形成した。溶融体を１２００
°Ｃで３時間以上攪拌し、十分均一な液相の状態とし
た。溶融体を保持温度１０７０℃まで冷却した後、１２
時間以上保持し、過飽和分の固溶体が核発生して固相が
析出するまで待った。このとき、溶融体の液相部分は、
１０７０℃における飽和状態であり、溶融体内は、液相
部分と、固溶体からなる固相部分とが共存した状態であ
る。Example 2 LiNbO 3 --LiTaO 3
A film was formed on a lithium niobate single crystal substrate using a LiVO 3 pseudo-ternary melt. 1200 melt
The mixture was stirred at 0 ° C. for 3 hours or more to obtain a sufficiently uniform liquid phase. After cooling the melt to a holding temperature of 1070 ° C., 12
The temperature was maintained for at least the time and waited until the supersaturated solid solution was nucleated and the solid phase was precipitated. At this time, the liquid phase portion of the melt is
It is in a saturated state at 1070 ° C. and is in a state in which a liquid phase portion and a solid phase portion made of a solid solution coexist in the melt.
【００３０】その後、溶融体の温度を、１０７０℃から
過冷却度２０℃だけ低い成膜温度１０５０℃まで冷却
し、ただちに前記基板を、前記の液相部分に接触させ、
固溶体からなる膜を形成した。得られた固溶体膜は、Ｌ
ｉＮｂ0.5 Ｔａ0.5Ｏ3 の組成を有していた。このキュ
リー温度は約８８０℃であった。Thereafter, the temperature of the melt is cooled from 1070 ° C. to a film forming temperature of 1050 ° C. which is lower by a supercooling degree of 20 ° C., and immediately the substrate is brought into contact with the liquid phase portion,
A film of solid solution was formed. The solid solution film obtained was L
It had a composition of iNb 0.5 Ta 0.5 O 3 . The Curie temperature was about 880 ° C.
【００３１】基板および膜の表面を光学研磨し、ＨＦ１
に対して硝酸２を配合したエッチング液を使用し、１１
０℃で１分間エッチングした。この表面を微分干渉顕微
鏡によって観察した。この結果、膜および基板の双方と
もに、単分域構造であることが判明した。The surfaces of the substrate and the film are optically polished to remove HF1.
Using an etching solution containing 2 nitric acid,
Etched at 0 ° C. for 1 minute. The surface was observed by a differential interference microscope. As a result, it was found that both the film and the substrate had a single domain structure.
【００３２】また、成膜後の基板の前記半値幅を測定し
たが、６．８秒であった。更に、基板上に形成した固溶
体膜の前記半値幅を測定したが、５．８秒であった。The full width at half maximum of the substrate after film formation was measured and found to be 6.8 seconds. Further, the full width at half maximum of the solid solution film formed on the substrate was measured and found to be 5.8 seconds.
【００３３】このように、本発明の方法によれば、単結
晶基板については、成膜前と比較して、単結晶基板の結
晶性の劣化はまったく見られず、基板の単分域状態も良
好に保持されている。しかも、こうした光学グレードの
基板の方よりも結晶性が良好である単結晶膜を形成する
ことができ、かつこの単結晶膜は、単分域状態の膜とし
て形成されていた。As described above, according to the method of the present invention, with respect to the single crystal substrate, deterioration of the crystallinity of the single crystal substrate is not observed at all, and the single domain state of the substrate is also observed. It is held well. Moreover, it is possible to form a single crystal film having better crystallinity than the optical grade substrate, and the single crystal film is formed as a single domain film.
【００３４】（比較例１）ＬｉＮｂＯ3 ─ＬｉＴａＯ3
─ＬｉＶＯ3 擬三元系の溶融体を使用して、ニオブ酸リ
チウム単結晶基板上に膜を形成した。溶融体を１３００
°Ｃで３時間以上攪拌し、十分均一な液相の状態とし
た。溶融体を保持温度１１９０℃まで冷却した後、１２
時間以上保持し、過飽和分の固溶体が核発生して固相が
析出するまで待った。このとき、溶融体の液相部分は、
１１９０℃における飽和状態であり、溶融体内は、液相
部分と、固溶体からなる固相部分とが共存した状態であ
る。Comparative Example 1 LiNbO 3 --LiTaO 3
A film was formed on a lithium niobate single crystal substrate using a LiVO 3 pseudo-ternary melt. Melt 1300
The mixture was stirred at 0 ° C. for 3 hours or more to obtain a sufficiently uniform liquid phase. After cooling the melt to a holding temperature of 1190 ° C, 12
The temperature was maintained for at least the time and waited until the supersaturated solid solution nucleated and the solid phase was precipitated. At this time, the liquid phase portion of the melt is
It is in a saturated state at 1190 ° C. and is in a state in which a liquid phase portion and a solid phase portion made of a solid solution coexist in the melt.
【００３５】その後、溶融体の温度を、成膜温度１１７
０℃まで冷却し、ただちに前記基板を液相部分に接触さ
せ、固溶体からなる膜を形成した。得られた固溶体膜
は、ＬｉＮｂ0.3 Ｔａ0.7 Ｏ3 の組成を有していた。こ
のキュリー温度は約７７０℃であった。Thereafter, the temperature of the melt is set to the film forming temperature 117.
After cooling to 0 ° C., the substrate was immediately brought into contact with the liquid phase portion to form a film made of a solid solution. The obtained solid solution film had a composition of LiNb 0.3 Ta 0.7 O 3 . The Curie temperature was about 770 ° C.
【００３６】基板および膜の表面を光学研磨し、ＨＦ１
に対して硝酸２を配合したエッチング液を使用し、１１
０℃で１分間エッチングした。この表面を微分干渉顕微
鏡によって観察した。この結果、膜および基板の双方と
もに、多分域構造になっていることが判明した。The surfaces of the substrate and the film are optically polished to remove HF1.
Using an etching solution containing 2 nitric acid,
Etched at 0 ° C. for 1 minute. The surface was observed by a differential interference microscope. As a result, it was found that both the film and the substrate had a multidomain structure.
【００３７】また、成膜後の基板の前記半値幅を測定し
たが、７．３秒であり、成膜前と比較すると劣化が見ら
れた。また、基板上に形成した固溶体膜の前記半値幅を
測定したが、７．３秒であり、基板とほぼ同じ程度の結
晶性であった。このように、基板および膜が多分域状態
となるだけでなく、基板が多分域化するのに伴って基板
の結晶性も劣化し、膜の方もその影響を受けている事が
分かる。The full width at half maximum of the substrate after film formation was measured and found to be 7.3 seconds, which was inferior to that before film formation. Further, the half-value width of the solid solution film formed on the substrate was measured, and it was 7.3 seconds, and the crystallinity was almost the same as that of the substrate. As described above, it is understood that not only the substrate and the film are in the multi-domain state, but also the crystallinity of the substrate is deteriorated as the substrate is multi-domained, and the film is also affected by the multi-domain.
【００３８】次に，この基板および膜を単分域化処理し
た後、それぞれの前記半値幅を測定した。この結果、基
板の前記半値幅は７．４秒となり、僅かに低下が見られ
た。しかし、膜の前記半値幅は２０．５秒と顕著に低下
した。このように、膜の単分域化処理によって、膜の結
晶性が大きく劣化することが判明した。Next, after subjecting the substrate and the film to single-domain processing, the respective half widths were measured. As a result, the full width at half maximum of the substrate was 7.4 seconds, which was slightly decreased. However, the full width at half maximum of the film was significantly reduced to 20.5 seconds. As described above, it was found that the crystallinity of the film was significantly deteriorated by the single-domain treatment of the film.
【００３９】（比較例２）ＬｉＮｂＯ3 ─ＬｉＴａＯ3
─ＬｉＶＯ3 擬三元系の溶融体を使用して、ニオブ酸リ
チウム単結晶基板上に膜を形成した。溶融体を１３００
°Ｃで３時間以上攪拌し、十分均一な液相の状態とし
た。溶融体を保持温度１１８０℃まで冷却した後、１２
時間以上保持し、過飽和分の固溶体が核発生して固相が
析出するまで待った。このとき、溶融体内は、液相部分
と、固溶体からなる固相部分とが共存した状態である。Comparative Example 2 LiNbO 3 --LiTaO 3
A film was formed on a lithium niobate single crystal substrate using a LiVO 3 pseudo-ternary melt. Melt 1300
The mixture was stirred at 0 ° C. for 3 hours or more to obtain a sufficiently uniform liquid phase. After cooling the melt to a holding temperature of 1180 ° C., 12
The temperature was maintained for at least the time and waited until the supersaturated solid solution was nucleated and the solid phase was precipitated. At this time, in the melt, a liquid phase portion and a solid phase portion made of a solid solution coexist.
【００４０】その後、溶融体の温度を、成膜温度１１６
０℃まで冷却し、ただちに前記基板を液相部分に接触さ
せ、固溶体からなる膜を形成した。得られた固溶体膜
は、ＬｉＮｂ0.5 Ｔａ0.5 Ｏ3 の組成を有していた。こ
のキュリー温度は約８８０℃であった。Thereafter, the temperature of the melt is set to the film forming temperature 116.
After cooling to 0 ° C., the substrate was immediately brought into contact with the liquid phase portion to form a film made of a solid solution. The obtained solid solution film had a composition of LiNb 0.5 Ta 0.5 O 3 . The Curie temperature was about 880 ° C.
【００４１】基板および膜の表面を光学研磨し、ＨＦ１
に対して硝酸２を配合したエッチング液を使用し、１１
０℃で１分間エッチングした。この表面を微分干渉顕微
鏡によって観察した。この結果、膜および基板の双方と
もに、多分域構造になっていることが判明した。The surfaces of the substrate and the film are optically polished to remove HF1.
Using an etching solution containing 2 nitric acid,
Etched at 0 ° C. for 1 minute. The surface was observed by a differential interference microscope. As a result, it was found that both the film and the substrate had a multidomain structure.
【００４２】また、成膜後の基板の前記半値幅を測定し
たが、７．１秒であり、成膜前と比較すると劣化が見ら
れた。また、基板上に形成した固溶体膜の前記半値幅を
測定したが、７．１秒であり、基板とほぼ同じ程度の結
晶性であった。The full width at half maximum of the substrate after film formation was measured and found to be 7.1 seconds, which was deteriorated as compared with that before film formation. Moreover, the half-value width of the solid solution film formed on the substrate was measured, and it was 7.1 seconds, and the crystallinity was almost the same as that of the substrate.
【００４３】次に，この基板および膜を単分域化処理し
た後、それぞれの前記半値幅を測定した。この結果、基
板の前記半値幅は７．４秒となり、低下が見られた。し
かし、膜の前記半値幅は２２．３秒と顕著に低下した。
このように、膜の単分域化処理によって、膜の結晶性が
大きく劣化することが判明した。Next, after subjecting the substrate and the film to single-domain processing, the respective half widths were measured. As a result, the full width at half maximum of the substrate was 7.4 seconds, which was a decrease. However, the full width at half maximum of the film was remarkably reduced to 22.3 seconds.
As described above, it was found that the crystallinity of the film was significantly deteriorated by the single-domain treatment of the film.
【００４４】（比較例３）ＬｉＮｂＯ3 ─ＬｉＴａＯ3
─ＬｉＶＯ3 擬三元系の溶融体を使用して、ニオブ酸リ
チウム単結晶基板上に膜を形成した。溶融体を１２００
°Ｃで３時間以上攪拌し、十分均一な液相の状態とし
た。溶融体を保持温度８９０℃まで冷却した後、１２時
間以上保持し、過飽和分の固溶体が核発生して固相が析
出するまで待った。(Comparative Example 3) LiNbO 3 --LiTaO 3
A film was formed on a lithium niobate single crystal substrate using a LiVO 3 pseudo-ternary melt. 1200 melt
The mixture was stirred at 0 ° C. for 3 hours or more to obtain a sufficiently uniform liquid phase. After the melt was cooled to a holding temperature of 890 ° C., it was held for 12 hours or more, and waited until a supersaturated solid solution was nucleated and a solid phase was precipitated.
【００４５】その後、溶融体の温度を、成膜温度８８０
℃まで冷却し、ただちに前記基板を液相部分に接触さ
せ、固溶体からなる膜を形成した。得られた固溶体膜
は、ＬｉＮｂ0.88Ｔａ0.12Ｏ3 の組成を有していた。こ
のキュリー温度は、成膜温度よりも高い、約１０８０℃
であった。Thereafter, the temperature of the melt is set to the film forming temperature 880.
After cooling to 0 ° C., the substrate was immediately brought into contact with the liquid phase portion to form a film made of a solid solution. The obtained solid solution film had a composition of LiNb 0.88 Ta 0.12 O 3 . This Curie temperature is higher than the film forming temperature, about 1080 ° C.
Met.
【００４６】基板および膜の表面を光学研磨し、ＨＦ１
に対して硝酸２を配合したエッチング液を使用し、１１
０℃で１分間エッチングした。この表面を微分干渉顕微
鏡によって観察した。この結果、基板の方は単分域構造
が維持されていたが、膜の方は多分域構造になっている
ことが判明した。The surfaces of the substrate and the film are optically polished to remove HF1.
Using an etching solution containing 2 nitric acid,
Etched at 0 ° C. for 1 minute. The surface was observed by a differential interference microscope. As a result, it was revealed that the substrate had a single domain structure, while the film had a multidomain structure.
【００４７】また、成膜後の基板の前記半値幅を測定し
たが、６．８秒であり、成膜前と同じであった。また、
基板上に形成した固溶体膜の前記半値幅を測定したが、
１８．４秒であり、基板に比べて結晶性が顕著に劣化し
ていることが判明した。The full width at half maximum of the substrate after film formation was measured and found to be 6.8 seconds, which was the same as before film formation. Also,
The full width at half maximum of the solid solution film formed on the substrate was measured,
It was 18.4 seconds, and it was found that the crystallinity was significantly deteriorated as compared with the substrate.
【００４８】次に，この基板および膜を単分域化処理し
た後、それぞれの前記半値幅を測定した。この結果、基
板の前記半値幅は７．５秒となり、低下が見られた。し
かし、膜の前記半値幅は２２．８秒と、一層劣化が進行
した。Next, after subjecting the substrate and the film to single-domain processing, the respective half widths were measured. As a result, the full width at half maximum of the substrate was 7.5 seconds, which was a decrease. However, the full width at half maximum of the film was 22.8 seconds, and the deterioration further progressed.
【００４９】[0049]
【発明の効果】以上述べてきたように、本発明によれ
ば、単分域状態にある強誘電性単結晶基板上に強誘電性
単結晶膜を液相エピタキシャル法によって形成するのに
際して、成膜後においても、強誘電性単結晶基板の単分
域状態を維持するのと共に、単分域状態の単結晶膜を形
成できる。この結果、強誘電性単結晶基板および膜の単
分域化処理をする必要がないので、良好な結晶性を有す
る基板および膜を得ることができる。As described above, according to the present invention, when the ferroelectric single crystal film is formed on the ferroelectric single crystal substrate in the single domain state by the liquid phase epitaxial method, Even after the film is formed, the single domain state of the ferroelectric single crystal substrate can be maintained, and the single crystal film in the single domain state can be formed. As a result, it is not necessary to subject the ferroelectric single crystal substrate and the film to single-domain processing, so that the substrate and the film having good crystallinity can be obtained.
Claims (2)
強誘電性単結晶膜とを備えている単結晶基板品を製造す
る方法であって、前記強誘電性単結晶基板上に前記強誘
電性単結晶膜を液相エピタキシャル法によって形成する
のに際して、前記強誘電性単結晶基板のキュリー温度が
液相エピタキシャル法における成膜温度よりも高く、こ
の成膜温度が、前記強誘電性単結晶膜のキュリー温度以
上であることを特徴とする、単結晶基板品の製造方法。1. A method of manufacturing a single crystal substrate product comprising a ferroelectric single crystal substrate and a ferroelectric single crystal film formed on the ferroelectric single crystal substrate, comprising: When forming the ferroelectric single crystal film by the liquid phase epitaxial method, the Curie temperature of the ferroelectric single crystal substrate is higher than the film forming temperature in the liquid phase epitaxial method, and this film forming temperature is the ferroelectric film. A method of manufacturing a single crystal substrate product, characterized in that the temperature is not less than the Curie temperature of the crystalline single crystal film.
ムからなり、前記強誘電性単結晶膜がタンタル酸リチウ
ムまたはニオブ酸リチウム─タンタル酸リチウム固溶体
からなっていることを特徴とする、請求項１記載の単結
晶基板品の製造方法。2. The ferroelectric single crystal substrate is made of lithium niobate, and the ferroelectric single crystal film is made of lithium tantalate or lithium niobate-lithium tantalate solid solution. Item 1. A method for manufacturing a single crystal substrate product according to Item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22208794A JP3388901B2 (en) | 1994-09-16 | 1994-09-16 | Manufacturing method for single crystal substrate products |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22208794A JP3388901B2 (en) | 1994-09-16 | 1994-09-16 | Manufacturing method for single crystal substrate products |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0891986A true JPH0891986A (en) | 1996-04-09 |
| JP3388901B2 JP3388901B2 (en) | 2003-03-24 |
Family
ID=16776929
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22208794A Expired - Fee Related JP3388901B2 (en) | 1994-09-16 | 1994-09-16 | Manufacturing method for single crystal substrate products |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3388901B2 (en) |
-
1994
- 1994-09-16 JP JP22208794A patent/JP3388901B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3388901B2 (en) | 2003-03-24 |
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