JP2006228447A - Manufacturing method for ferroelectric thin film - Google Patents
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Abstract
Description
本発明は、圧電特性を利用した圧電マイクロアクチュエータや圧電センサ、更に、焦電特性を利用した焦電センサ、分極特性を利用した不揮発メモリなどに用いる強誘電体薄膜の製造方法に関するものである。 The present invention relates to a method of manufacturing a ferroelectric thin film used for a piezoelectric microactuator or a piezoelectric sensor using piezoelectric characteristics, a pyroelectric sensor using pyroelectric characteristics, a nonvolatile memory using polarization characteristics, or the like.
強誘電体材料は、優れた強誘電特性、焦電特性、圧電特性、電気光学特性、そして高い誘電率を備えており、強誘電体不揮発性メモリ（次世代メモリ）、圧電センサ、圧電アクチュエータ、表面弾性波デバイス、赤外線センサ、ＤＲＡＭのキャパシタ、光偏光素子、など広い応用範囲を有している。そして、今日の電子デバイスなどの小型化、軽量化、省電力化が進む中、これらの機能をもった強誘電体薄膜材料の開発が活発に行われている。 Ferroelectric materials have excellent ferroelectric properties, pyroelectric properties, piezoelectric properties, electro-optic properties, and high dielectric constants. Ferroelectric nonvolatile memory (next-generation memory), piezoelectric sensors, piezoelectric actuators, It has a wide range of applications such as surface acoustic wave devices, infrared sensors, DRAM capacitors, and optical polarization elements. With the progress of miniaturization, weight reduction, and power saving of today's electronic devices, the development of ferroelectric thin film materials having these functions has been actively conducted.
強誘電体薄膜の成膜方法として、塗布法（スピンコート法、スプレー法）、スパッタリング法、有機金属化学気相堆積法（ＭＯＣＶＤ法；Ｍｅｔａｌ Ｏｒｇａｎｉｃ Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎｍｅｔｈｏｄ）、レーザーアブレーション法などがある。現在では、塗布法やスパッタリング法で実用化されつつあるが、特に塗布法は安価な膜を成膜する方法として利用されている。例えば、スピンコート法（ゾルゲル法、ＭＯＤ法（Ｍｅｔａｌ−Ｏｒｇａｎｉｃ Ｄｅｐｏｓｉｔｉｏｎｍｅｔｈｏｄ；有機金属分解法））を例に挙げると、以下に示すような特徴を持つ。
（１）多成分系であっても組成制御が再現性良くできる。
（２）大型の装置を使用しない極めて簡便な方法で、実験室レベルで成膜実験が可能である。
（３）組成検討や複数の金属イオンを検討する新材料の研究に向く。
（４）大面積で均一な膜が低コストで成膜できる。
As a method for forming a ferroelectric thin film, there are a coating method (spin coating method, spraying method), a sputtering method, a metal organic chemical vapor deposition method (MOCVD method), a laser ablation method, and the like. At present, the coating method and the sputtering method are being put into practical use, but the coating method is particularly used as a method for forming an inexpensive film. For example, when the spin coating method (sol-gel method, MOD method (Metal-Organic Deposition method)) is taken as an example, it has the following characteristics.
(1) The composition control can be performed with good reproducibility even in a multi-component system.
(2) A film forming experiment can be performed at a laboratory level by a very simple method without using a large apparatus.
(3) It is suitable for the study of new materials that examine the composition and multiple metal ions.
(4) A large area and uniform film can be formed at low cost.
従来、スピンコート法において、実質的に低温で結晶化が促進されることを目的として、強誘電体結晶の超微粉末を絶縁体用液体原料に混合し、これを基板上にスピンコート（５００ｒｐｍで１０秒＋２０００ｒｐｍで２０秒）で塗布し、４５０℃で仮焼きし、５００℃〜７００℃で本焼きし、基板上に強誘電体薄膜を成膜することが知られている（例えば、特許文献１参照）。 Conventionally, in a spin coating method, for the purpose of promoting crystallization at a substantially low temperature, an ultrafine powder of a ferroelectric crystal is mixed with a liquid material for an insulator, and this is spin-coated (500 rpm) on a substrate. For 10 seconds + 2000 rpm for 20 seconds), calcined at 450 ° C., and baked at 500 ° C. to 700 ° C. to form a ferroelectric thin film on the substrate (for example, patent) Reference 1).
また、ゾルゲル法によってＰＺＴ強誘電体膜７を形成するに際し、その膜厚を１０００Åとなるように制御すること、或いは、原料溶液の乾燥温度を１３０〜２００℃の範囲に特定し、特に、ゾルーゲル原料に含まれる安定剤の沸点よりも低くかつゾルーゲル原料に含まれる溶媒の沸点よりも高く設定する方法が知られている（例えば、特許文献２参照）。
しかしながら、上記特許文献１、２には焼成工程における昇温速度についての記載はない。 However, Patent Documents 1 and 2 do not describe the rate of temperature increase in the firing step.
強誘電体薄膜の圧電特性を利用して、インクジェット記録ヘッドなどの圧電素子への応用を考えた場合、１〜１０μｍ程度の薄膜が一般的に必要と言われている。しかし、塗布法である程度の膜厚、例えば１μｍ以上の強誘電体膜を成膜する場合、原料溶液の塗布と乾燥交互に１回、または複数回繰り返して４０〜１５０nmの薄膜を得、その薄膜を結晶化するという工程を、強誘電体薄膜の膜厚が１μｍ以上になるまで複数回繰り返すので、非常に時間がかかる。成膜時間を短縮しようとして、原料溶液の塗布と乾燥を交互に１回ずつ行って得られた薄膜の膜厚を厚くすると、その後の結晶化の過程で膜内にクラックが発生してしまう。現状では、塗布法でクラックレスの薄膜を厚膜化することは困難である。 When considering application to piezoelectric elements such as ink jet recording heads by utilizing the piezoelectric characteristics of ferroelectric thin films, it is generally said that a thin film of about 1 to 10 μm is necessary. However, when a ferroelectric film having a film thickness of, for example, 1 μm or more is formed by a coating method, a thin film having a thickness of 40 to 150 nm is obtained by repeating application of the raw material solution and drying alternately or a plurality of times. Since the process of crystallizing is repeated a plurality of times until the film thickness of the ferroelectric thin film reaches 1 μm or more, it takes a very long time. If the thickness of the thin film obtained by alternately applying and drying the raw material solution is increased once in an attempt to shorten the film formation time, cracks will occur in the film during the subsequent crystallization process. At present, it is difficult to thicken a crackless thin film by a coating method.
そこで、本発明の目的は、上記課題を解決し、スピンコート法、ＭＯＤ法などの塗布法において、焼成工程における昇温速度を適切にして、クラックを発生させずに強誘電体薄膜を膜厚１μｍ以上成膜することができる強誘電体薄膜の製造方法を提供することにある。 Accordingly, an object of the present invention is to solve the above-mentioned problems, and in a coating method such as a spin coating method or a MOD method, the temperature rise rate in the firing step is appropriate, and the ferroelectric thin film is formed without causing cracks. An object of the present invention is to provide a method for manufacturing a ferroelectric thin film capable of forming a film of 1 μm or more.
上記目的を達成するため、本発明は、次のように構成したものである。 In order to achieve the above object, the present invention is configured as follows.
請求項１の発明に係る強誘電体薄膜の製造方法は、基板上に任意量の強誘電体原料溶液を塗布し乾燥する工程を１回又は複数回行い、得られた薄膜を６００℃以上の加熱処理により焼成して薄膜を一度に結晶化する工程を含む塗布法による強誘電体薄膜の製造方法において、上記６００℃以上の加熱処理により焼成するときの加熱開始から６００℃に到達する間の昇温速度の平均を２．０℃／分以下に設定し、所望の厚さの強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする。 In the method of manufacturing a ferroelectric thin film according to the first aspect of the present invention, the step of applying an arbitrary amount of the ferroelectric raw material solution on the substrate and drying it is performed once or a plurality of times, and the obtained thin film is heated to 600 ° C. or more. In the method of manufacturing a ferroelectric thin film by a coating method including a step of crystallizing a thin film at a time by baking by heat treatment, while the temperature reaches 600 ° C. from the start of heating when baking is performed by heat treatment at 600 ° C. or higher. The average heating rate is set to 2.0 ° C./min or less, and the coating / drying step and the crystallization firing step are repeated until a ferroelectric thin film having a desired thickness is obtained.
請求項２の発明に係る強誘電体薄膜の製造方法は、基板上に任意量の強誘電体原料溶液を塗布し５００℃以下の熱処理により乾燥する工程を１回又は複数回行い、得られた薄膜を６００℃以上７００℃以下の加熱処理により焼成して薄膜を一度に結晶化する工程を含む塗布法による強誘電体薄膜の製造方法において、上記６００℃以上７００℃以下の加熱処理により焼成するときの加熱開始から少なくとも６００℃に到達する間の昇温速度の平均を２．０℃／分以下に設定し、所望の厚さの強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする。 The method for producing a ferroelectric thin film according to the invention of claim 2 was obtained by performing a step of applying an arbitrary amount of a ferroelectric raw material solution on a substrate and drying it by heat treatment at 500 ° C. or less once or a plurality of times. In the method of manufacturing a ferroelectric thin film by a coating method including a step of crystallizing the thin film at a time by baking the thin film by heat treatment at 600 ° C. or higher and 700 ° C. or lower, baking is performed by the heat treatment at 600 ° C. or higher and 700 ° C. or lower. When the average heating rate during reaching at least 600 ° C. from the start of heating is set to 2.0 ° C./min or less, until the ferroelectric thin film having a desired thickness is obtained, The firing step of crystallization is repeated.
この請求項２によれば、５００℃以下の熱処理温度で乾燥するため、結晶化を生じさせずに短時間で乾燥することができる。すなわち、乾燥時間の短縮ができる。また、焼成の温度としては、６００℃以上であれば結晶化が可能であり、また７００℃より高くなると、膜が荒れたり、基板上の電極が痛んだりするため、７００℃以下とすることが好ましい。よって本発明の請求項２の特徴に従い、６００℃以上７００℃以下の温度で加熱処理して焼成することにより、薄膜を一度に結晶化することができる。本発明の典型例は、強誘電体原料溶液の塗布と５００℃未満の熱処理（第一熱処理工程）を交互に１回、または複数回それぞれ行うことで得られる薄膜を、６００℃以上の温度、例えば７００℃で熱処理（第二熱処理工程）して結晶化する工程を繰り返し、強誘電体薄膜の膜厚が所望の厚さとなるようにするものである。 According to the second aspect, since the drying is performed at a heat treatment temperature of 500 ° C. or less, the drying can be performed in a short time without causing crystallization. That is, the drying time can be shortened. The firing temperature can be crystallized at 600 ° C. or higher. If the temperature is higher than 700 ° C., the film is roughened or the electrodes on the substrate are damaged. preferable. Therefore, according to the feature of claim 2 of the present invention, the thin film can be crystallized at a time by performing heat treatment and baking at a temperature of 600 ° C. or higher and 700 ° C. or lower. A typical example of the present invention is that a thin film obtained by alternately applying a ferroelectric raw material solution and a heat treatment (first heat treatment step) less than 500 ° C. once or a plurality of times, a temperature of 600 ° C. or higher, For example, a crystallization process by repeating heat treatment at 700 ° C. (second heat treatment process) is repeated so that the film thickness of the ferroelectric thin film becomes a desired thickness.
請求項３の発明は、請求項１又は２に記載の強誘電体薄膜の製造方法において、上記所望の厚さとして１μｍ以上の膜厚の強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする。 According to a third aspect of the present invention, in the method of manufacturing a ferroelectric thin film according to the first or second aspect, the coating / drying step is performed until a ferroelectric thin film having a thickness of 1 μm or more is obtained as the desired thickness. And repeating the crystallization firing step.
すなわち、この強誘電体薄膜の所望の厚さの代表例は、強誘電体原料溶液の塗布と５００℃以下の熱処理（第一熱処理工程）を交互に１回、もしくは複数回繰り返した後に、結晶化のための熱処理（第二熱処理工程）を６００℃以上で行って焼成する工程を繰り返し、成膜された強誘電体薄膜の膜厚が１μｍ以上になるようにするものである。 That is, a representative example of the desired thickness of the ferroelectric thin film is that after applying the ferroelectric raw material solution and heat treatment (first heat treatment step) at 500 ° C. or less alternately once or a plurality of times, The heat treatment (second heat treatment step) for forming the film is repeated at a temperature of 600 ° C. or higher, and the firing step is repeated so that the film thickness of the formed ferroelectric thin film becomes 1 μm or more.
請求項４の発明は、請求項１〜３のいずれかに記載の強誘電体薄膜の製造方法において、上記強誘電体原料溶液として、ＰＺＴ、ＰＬＺＴ、ＳＢＴ、ＢＩＴ、ＢＳＴ、ＬｉＮｂＯ3、ＳｒＢｉ2Ｎｂ2Ｏ9のいずれかを用いることを特徴とする。 According to a fourth aspect of the present invention, in the method for manufacturing a ferroelectric thin film according to any one of the first to third aspects, the ferroelectric raw material solution is PZT, PLZT, SBT, BIT, BST, LiNbO 3 , SrBi 2. Any one of Nb 2 O 9 is used.
＜発明の要点＞
塗布法は、任意量の原料溶液の塗布と乾燥を繰り返し行い、得られた薄膜の膜厚１６０〜６００nmを一気に結晶化する工程を繰り返す成膜方法である。そのため、塗布と乾燥を１回ずつ行って得られた薄膜の膜厚を厚くすると膜内にひずみが生じてクラックが発生しやすい。
<Key points of the invention>
The coating method is a film forming method in which an arbitrary amount of a raw material solution is repeatedly applied and dried, and a step of crystallizing the obtained thin film with a thickness of 160 to 600 nm at once is repeated. Therefore, when the thickness of the thin film obtained by performing coating and drying once is increased, distortion occurs in the film and cracks are likely to occur.
そこで本発明では、結晶化するときの昇温速度を遅くすることによって膜内のひずみを低減し、クラックフリーの強誘電体薄膜の膜厚１μｍ以上の厚膜を実現した。具体的には、原料溶液の塗布と乾燥を交互に一回、もしくは複数回繰り返して得られた薄膜を結晶化するときの昇温速度の平均を２．０℃／分以下にした。これを実現する方法として、ＲＴＡ(Ｒａｐｉｄ Ｔｈｅｒｍａｌ Ａｎｎｅａｌｉｎｇ)法などで昇温開始から６００℃に到達するまでの膜厚レートを２．０℃／分に設定して薄膜の結晶化を行った。 Accordingly, in the present invention, the strain in the film is reduced by slowing the temperature rising rate during crystallization, and a crack-free ferroelectric thin film having a thickness of 1 μm or more is realized. Specifically, the average of the heating rate when the thin film obtained by alternately applying the raw material solution and drying once or plural times was crystallized was set to 2.0 ° C./min or less. As a method for realizing this, the thin film was crystallized by setting the film thickness rate from the start of the temperature rise to 600 ° C. to 2.0 ° C./min by RTA (Rapid Thermal Annealing) method or the like.
本発明によれば、次のような優れた効果が得られる。 According to the present invention, the following excellent effects can be obtained.
本発明による強誘電体薄膜の製造方法では、６００℃以上の加熱処理、例えば６００℃〜７００℃の加熱処理により焼成するときの加熱開始から少なくとも６００℃に到達する間の昇温速度を、平均２．０℃／分以下に設定する。このため、所望の厚さ例えば１μｍ以上の膜厚の強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返した場合でも、クラックを発生させない。 In the method for producing a ferroelectric thin film according to the present invention, the temperature rising rate during at least 600 ° C. from the start of heating when baking is performed by heat treatment at 600 ° C. or higher, for example, 600 ° C. to 700 ° C., is averaged. Set to 2.0 ° C./min or less. For this reason, even when the coating / drying step and the crystallization firing step are repeated until a ferroelectric thin film having a desired thickness of, for example, 1 μm or more is obtained, no cracks are generated.
従って本発明によれば、スピンコート法、ＭＯＤ法などの塗布法において成膜した厚さ１μｍ以上の強誘電体薄膜の成膜時間を短縮し、クラックフリーの強誘電体薄膜を安価に成膜することができる。また、この強誘電体薄膜からデバイスを作製すると、塗布法を用いる為に大面積で均一な膜が安価に製造することができる。 Therefore, according to the present invention, the time required for forming a ferroelectric thin film having a thickness of 1 μm or more formed by a coating method such as spin coating or MOD is shortened, and a crack-free ferroelectric thin film is formed at low cost. can do. Further, when a device is produced from this ferroelectric thin film, a uniform film having a large area can be produced at low cost because the coating method is used.
以下、本発明の実施の形態を実施例に基づいて説明する。 Hereinafter, embodiments of the present invention will be described based on examples.
ここではチタン酸ジルコン酸鉛Ｐｂ（Ｚｒ、Ｔｉ）Ｏ3（通常ＰＺＴと言われている）の製造例について説明する。 Here, a production example of lead zirconate titanate Pb (Zr, Ti) O 3 (usually referred to as PZT) will be described.
この実施例のＰｂ（Ｚｒ、Ｔｉ）Ｏ3の製造に際しては、強誘電体原料溶液として以下に示す成分及び含有量のものを用いた。
・ＰｂＯが１１．５ｗｔ％
・ＺｒＯ2が５．２ｗｔ％
・ＴｉＯ2が４．８ｗｔ％
・１−プロパノールが３４．５ｗｔ％
・プロピレングリコールが４４．０ｗｔ％
In the production of Pb (Zr, Ti) O 3 of this example, the following components and contents were used as the ferroelectric raw material solution.
・ PbO is 11.5wt%
· ZrO 2 is 5.2wt%
・ TiO 2 is 4.8wt%
・ 1-4.5% by weight of 1-propanol
・ Propylene glycol is 44.0 wt%
ＰＺＴ圧電薄膜原料溶液（強誘電体原料溶液）を用いたスピンコート法によって、図２に示すようにＰｔ下部電極２付ＭｇＯ基板１上にＰＺＴ圧電薄膜３を成膜した。以下に実験の詳細を示す。 A PZT piezoelectric thin film 3 was formed on the MgO substrate 1 with the Pt lower electrode 2 by spin coating using a PZT piezoelectric thin film raw material solution (ferroelectric raw material solution) as shown in FIG. Details of the experiment are shown below.
スパッタリング法によって下部電極（白金、２００nm）２を成膜した基板１上に、原料溶液を０．１ｍｌ滴下し、スピンコーター（５００ｒｐｍ×３秒、３０００ｒｐｍ×１５秒）により均一に塗布（図１の塗布工程（ステップＳ１））した後、乾燥のために空気中で４００℃、５分間加熱した（図１の乾燥工程（ステップＳ２））。 0.1 ml of the raw material solution is dropped on the substrate 1 on which the lower electrode (platinum, 200 nm) 2 is formed by sputtering, and is uniformly applied by a spin coater (500 rpm × 3 seconds, 3000 rpm × 15 seconds) (FIG. 1). After the coating step (step S1)), the substrate was heated in air at 400 ° C. for 5 minutes for drying (drying step (step S2) in FIG. 1).
この塗布と乾燥を計４回繰り返して得られた薄膜を、結晶化のために加熱開始から昇温速度平均２．０℃／ｍｉｎで７００℃まで温度を上げ（図１の昇温工程（ステップＳ３））、空気中で１分間焼成して結晶化し（図１の焼成工程（ステップＳ４））、膜厚が１６０nmのＰＺＴ圧電薄膜を得た。 The temperature of the thin film obtained by repeating this coating and drying four times in total was increased from the start of heating to 700 ° C. at an average temperature increase rate of 2.0 ° C./min for crystallization (the temperature increasing step (step of FIG. 1)). S3)), and fired in air for 1 minute to crystallize (firing step in FIG. 1 (step S4)) to obtain a PZT piezoelectric thin film having a film thickness of 160 nm.
この塗布と乾燥を繰り返して得られた薄膜を結晶化するまでの工程（ステップＳ１〜Ｓ４）を７回繰り返し、所望の厚さとして膜厚１．１μｍのＰＺＴ圧電薄膜３を得た。その上に、スパッタリング法によって上部電極（白金、２００nm）４を成膜した。 The steps (steps S1 to S4) until the thin film obtained by repeating this coating and drying was crystallized 7 times to obtain a PZT piezoelectric thin film 3 having a desired thickness of 1.1 μm. An upper electrode (platinum, 200 nm) 4 was formed thereon by sputtering.
また、比較例として、従来技術を用いてＰＺＴ圧電薄膜を成膜した。原料溶液を０．１ｍｌ滴下し、スピンコーター（５００ｒｐｍ×３秒、３０００ｒｐｍ×１５秒）で均一に塗布した後、乾燥のために空気中で４００ｂ、５分間加熱した。この塗布と乾燥を計４回繰り返して得た薄膜を、結晶化のために空気中で７００℃、１分間焼成して、膜厚１６０ｍのＰＺＴ圧電薄膜を得た。 As a comparative example, a PZT piezoelectric thin film was formed using a conventional technique. 0.1 ml of the raw material solution was dropped and applied uniformly with a spin coater (500 rpm × 3 seconds, 3000 rpm × 15 seconds), and then heated in air for 400 b for 5 minutes for drying. A thin film obtained by repeating this coating and drying four times in total was baked in air at 700 ° C. for 1 minute for crystallization to obtain a 160-m thick PZT piezoelectric thin film.
この塗布と乾燥を繰り返して得られた薄膜を結晶化する工程を７回繰り返し、膜厚１．１μｍのＰＺＴ圧電薄膜を得た。 The process of crystallizing the thin film obtained by repeating this coating and drying was repeated seven times to obtain a PZT piezoelectric thin film having a thickness of 1.1 μm.
従来技術を用いて成膜したＰＺＴ圧電薄膜（以下、比較例ＰＺＴ−１とする）と本発明における製造方法で成膜したＰＺＴ圧電薄膜（以下、実施例ＰＺＴ−２とする）のクラック有無の確認、Ｘ線回折測定、分極特性測定を行った。 The presence or absence of cracks in the PZT piezoelectric thin film (hereinafter referred to as Comparative Example PZT-1) formed using the conventional technique and the PZT piezoelectric thin film (hereinafter referred to as Example PZT-2) formed by the manufacturing method of the present invention. Confirmation, X-ray diffraction measurement, and polarization characteristic measurement were performed.
比較例ＰＺＴ−１ではクラックの発生が確認できたのに対し、実施例ＰＺＴ−２ではクラック発生は確認できなかった。 In Comparative Example PZT-1, the occurrence of cracks could be confirmed, whereas in Example PZT-2, the occurrence of cracks could not be confirmed.
Ｘ線回折測定結果は、比較例ＰＺＴ−１がＰＺＴ（００１）方位やＰＺＴ（００２）方位の他にＰＺＴ（１１１）方位やＰＺＴ（１１０）方位などを示すピークが存在したのに対し、実施例ＰＺＴ−２ではＰＺＴ（００１）方位とＰＺＴ（００２）方位を示すピークしか存在しなかった。また、分膜特性測定結果は、比較例ＰＺＴ−１の分極値（２Ｐｒ）が７５μＣ／cm2を示したのに対し、実施例ＰＺＴ−２は１１０μＣ／cm2であった。 The X-ray diffraction measurement result shows that Comparative Example PZT-1 had peaks indicating the PZT (111) orientation and the PZT (110) orientation in addition to the PZT (001) orientation and the PZT (002) orientation. In Example PZT-2, only peaks indicating PZT (001) orientation and PZT (002) orientation were present. In addition, as a result of measuring the membrane properties, the polarization value (2Pr) of Comparative Example PZT-1 showed 75 μC / cm 2 , whereas Example PZT-2 was 110 μC / cm 2 .
次に最適条件について吟味した。 Next, the optimum conditions were examined.
表１に、加熱開始から６００℃まで温度を上げ、空気中で１分間結晶化を行う焼成工程において、その加熱開始から６００℃まで温度を上げる昇温速度の平均値を変えて成膜を行ったときの、ＰＺＴ圧電薄膜のクラックの発生の有無についてまとめた結果を示す。 In Table 1, in the firing step in which the temperature is increased from the start of heating to 600 ° C. and crystallization is performed in the air for 1 minute, film formation is performed by changing the average value of the temperature increase rate at which the temperature is increased from the start of heating to 600 ° C. The result of having put together about the presence or absence of generation | occurrence | production of the crack of a PZT piezoelectric thin film at the time is shown.
表１から分かるように、昇温速度の平均値を０．５、１、２、４、８、１６℃／ｍｉｎと変えたとき、昇温速度の平均値が０．５、１、２℃／ｍｉｎの場合はクラックの発生が見られなかった。昇温速度の平均値が４℃／ｍｉｎの場合にはクラックの発生が一部見られた。また、昇温速度の平均値が８、１６℃／ｍｉｎと高い場合にはいずれもクラックが発生した。 As can be seen from Table 1, when the average value of the heating rate is changed to 0.5, 1, 2, 4, 8, 16 ° C./min, the average value of the heating rate is 0.5, 1, 2 ° C. In the case of / min, no crack was observed. When the average value of the heating rate was 4 ° C./min, some cracks were observed. Further, cracks occurred in all cases where the average value of the heating rate was as high as 8 and 16 ° C./min.
よって、本発明の効果として、塗布と乾燥を交互に複数回繰り返して得られた薄膜を結晶化する工程を膜厚が１μｍ以上になるまで繰り返したとき、加熱開始から６００℃で結晶化したときの昇温速度の平均値が２．０℃／ｍｉｎ以下ではクラックが発生しないことが確認された。 Therefore, as an effect of the present invention, when the process of crystallizing a thin film obtained by alternately repeating coating and drying a plurality of times is repeated until the film thickness becomes 1 μm or more, when crystallizing at 600 ° C. from the start of heating It was confirmed that cracks did not occur at an average value of the heating rate of 2.0 ° C./min or less.
＜他の実施例、変形例＞
上記実施例１、２においては、そのＰＺＴ圧電薄膜の成膜方法において基板としてＭｇＯ基板を使用したが、本発明はそれに限定されるものではなく、ガラス基板、ＳｉＯ2／Ｓｉ基板などでも応用できるものである。
<Other embodiments and modifications>
In the above first and second embodiments have been using MgO as the substrate in the film forming method of the PZT piezoelectric thin film, the present invention is not limited thereto, the glass substrate can also be applied in such SiO 2 / Si substrate Is.
また、下部・上部両電極においても、その成膜方法はスパッタリング法に限定されるものではなく、ＥＢ蒸着法などでも応用できるものである。また、電極に使用した材料は白金（Ｐｔ）であったが、本発明はそれに限定されるものではなく、イリジウム（Ｉｒ）、ルテニウム（Ｒｕ）、タンタル（Ｔａ）、チタン（Ｔｉ）、アルミニウム（Ａｌ）、ニッケル（Ｎｉ）、金（Ａｕ）などの金属及び金属酸化物などでも応用できるものである。 Further, the film formation method for both the lower and upper electrodes is not limited to the sputtering method, but can also be applied by the EB vapor deposition method or the like. Moreover, although the material used for the electrode was platinum (Pt), the present invention is not limited thereto, and iridium (Ir), ruthenium (Ru), tantalum (Ta), titanium (Ti), aluminum ( The present invention can also be applied to metals such as Al), nickel (Ni), gold (Au), and metal oxides.
なお、本発明は強誘電体薄膜だけではなく、超伝導薄膜、磁性体薄膜、その他金属酸化物薄膜、等にも応用できるものである。 The present invention can be applied not only to a ferroelectric thin film but also to a superconducting thin film, a magnetic thin film, and other metal oxide thin films.
１ ＭｇＯ基板
２ Ｐｔ下部電極
３ ＰＺＴ圧電薄膜
４ Ｐｔ上部電極
1 MgO substrate 2 Pt lower electrode 3 PZT piezoelectric thin film 4 Pt upper electrode
Claims (4)
上記６００℃以上の加熱処理により焼成するときの加熱開始から６００℃に到達する間の昇温速度の平均を２．０℃／分以下に設定し、所望の厚さの強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする強誘電体薄膜の製造方法。 Including a step of applying an arbitrary amount of a ferroelectric raw material solution on a substrate and drying it once or a plurality of times, and baking the obtained thin film by heat treatment at 600 ° C. or more to crystallize the thin film at a time. In the manufacturing method of the ferroelectric thin film by the coating method,
The average rate of temperature rise from the start of heating to 600 ° C. when firing by the heat treatment at 600 ° C. or higher is set to 2.0 ° C./min or less to obtain a ferroelectric thin film having a desired thickness. The method for producing a ferroelectric thin film characterized in that the coating / drying step and the crystallization firing step are repeated until it is completed.
上記６００℃以上７００℃以下の加熱処理により焼成するときの加熱開始から少なくとも６００℃に到達する間の昇温速度の平均を２．０℃／分以下に設定し、所望の厚さの強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする強誘電体薄膜の製造方法。 A process of applying an arbitrary amount of a ferroelectric material solution on a substrate and drying it by heat treatment at 500 ° C. or less is performed once or a plurality of times, and the obtained thin film is baked by heat treatment at 600 ° C. or more and 700 ° C. or less. In a method for manufacturing a ferroelectric thin film by a coating method including a step of crystallizing at a time,
The average of the heating rate during the time of reaching 600 ° C. from the start of heating when firing by the heat treatment of 600 ° C. or more and 700 ° C. or less is set to 2.0 ° C./min or less, and a ferroelectric having a desired thickness A method for producing a ferroelectric thin film, comprising repeating the coating / drying step and the crystallization firing step until a thin body film is obtained.
上記所望の厚さとして１μｍ以上の膜厚の強誘電体薄膜が得られるまで、上記塗布・乾燥工程と結晶化の焼成工程を繰り返すことを特徴とする強誘電体薄膜の製造方法。 In the manufacturing method of the ferroelectric thin film according to claim 1 or 2,
A method for producing a ferroelectric thin film, characterized in that the coating / drying step and the crystallization firing step are repeated until a ferroelectric thin film having a thickness of 1 μm or more is obtained as the desired thickness.
上記強誘電体原料溶液として、ＰＺＴ、ＰＬＺＴ、ＳＢＴ、ＢＩＴ、ＢＳＴ、ＬｉＮｂＯ3、ＳｒＢｉ2Ｎｂ2Ｏ9のいずれかを用いることを特徴とする強誘電体薄膜の製造方法。 In the manufacturing method of the ferroelectric thin film in any one of Claims 1-3,
One of PZT, PLZT, SBT, BIT, BST, LiNbO 3 , and SrBi 2 Nb 2 O 9 is used as the ferroelectric raw material solution.
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| JP2007329188A (en) * | 2006-06-06 | 2007-12-20 | Tdk Corp | Thin-film dielectric element, and forming method of laminate therefor |
| JP2009177171A (en) * | 2007-12-28 | 2009-08-06 | Mitsubishi Materials Corp | Dielectric film, its manufacturing method and use |
| JP2011253768A (en) * | 2010-06-03 | 2011-12-15 | National Institute Of Advanced Industrial & Technology | Method of manufacturing oxide superconductor thin film |
| JP2014154610A (en) * | 2013-02-06 | 2014-08-25 | Ricoh Co Ltd | Thin film manufacturing method, electromechanical conversion element, liquid discharge head, and ink jet recording device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007329188A (en) * | 2006-06-06 | 2007-12-20 | Tdk Corp | Thin-film dielectric element, and forming method of laminate therefor |
| JP2009177171A (en) * | 2007-12-28 | 2009-08-06 | Mitsubishi Materials Corp | Dielectric film, its manufacturing method and use |
| JP2013153179A (en) * | 2007-12-28 | 2013-08-08 | Mitsubishi Materials Corp | Dielectric thin film without crack on surface thereof |
| JP2011253768A (en) * | 2010-06-03 | 2011-12-15 | National Institute Of Advanced Industrial & Technology | Method of manufacturing oxide superconductor thin film |
| JP2014154610A (en) * | 2013-02-06 | 2014-08-25 | Ricoh Co Ltd | Thin film manufacturing method, electromechanical conversion element, liquid discharge head, and ink jet recording device |
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