JP2005105393A - Method for forming ferroelectric thin film - Google Patents
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Abstract
Description
本発明は、強誘電体薄膜の形成方法、詳しくは強誘電体薄膜の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、焦電性を利用した焦電センサ、分極特性を利用した不揮発性メモリの作製に有用な強誘電体薄膜の形成方法に関わるものである。 The present invention relates to a method for forming a ferroelectric thin film, more specifically, a piezoelectric microactuator or a piezoelectric sensor using the piezoelectric characteristics of the ferroelectric thin film, a pyroelectric sensor using pyroelectricity, and a non-volatile using polarization characteristics. The present invention relates to a method of forming a ferroelectric thin film useful for manufacturing a memory.
現在、圧電特性に優れるＰｂ（Ｚｒ、Ｔｉ）Ｏ3（通常、ＰＺＴと言われている。）等の強誘電体が、バルクセラミックスの形状で圧電アクチュエータとして広く応用されているが、最近、圧電マイクロアクチュエータへの応用展開を目指して、強誘電体の薄膜化が強く求められている。強誘電体を薄膜化すると、印加する電圧値に対する変位量が大きくなるため、低電圧で駆動する変位量の大きいアクチュエータができるようになるからである。 At present, ferroelectrics such as Pb (Zr, Ti) O 3 (usually referred to as PZT) having excellent piezoelectric characteristics are widely applied as piezoelectric actuators in the form of bulk ceramics. Aiming to develop applications for microactuators, there is a strong demand for thinner ferroelectrics. This is because if the ferroelectric material is thinned, the amount of displacement with respect to the voltage value to be applied increases, so that an actuator with a large amount of displacement driven at a low voltage can be obtained.
しかしながら、強誘電体を薄くしすぎるとアクチュエータの動作に必要な力が得られなくなる。基材の種類や厚さにも依存するが、一般的に、圧電マイクロアクチュエータには、２〜１０μｍの厚さの薄膜が実用的に有利であると言われている。 However, if the ferroelectric is made too thin, the force necessary for the operation of the actuator cannot be obtained. Although it depends on the type and thickness of the substrate, it is generally said that a thin film having a thickness of 2 to 10 μm is practically advantageous for the piezoelectric microactuator.
これまでは、焼結されたバルク材を機械加工する方法や、スクリーン印刷法で薄膜を形成する方法が主に検討されてきた。しかしながら、バルク材の機械加工の場合、加工中やハンドリング中の破損の問題や基材への接着時のバラツキの問題があり、１００μｍ以下の微細加工は実用的には困難であった。また、スクリーン印刷法は、十分な膜密度を有する膜が得られないため、膜厚を薄くすると絶縁破壊を起こしやすくなる等の問題があり、実用化できていない。 Until now, methods of machining a sintered bulk material and methods of forming a thin film by screen printing have been mainly studied. However, in the case of machining a bulk material, there is a problem of breakage during processing or handling and a problem of variation at the time of adhesion to a base material, and microfabrication of 100 μm or less is practically difficult. In addition, since the screen printing method cannot obtain a film having a sufficient film density, there is a problem that a dielectric breakdown tends to occur when the film thickness is reduced, and it has not been put into practical use.
そこで最近は、薄膜成長技術として実績があるスパッタリング法、ゾルゲル法、ＭＯＣＶＤ法（化学気相堆積法）、ＰＬＤ法（パルスレーザ堆積法）等の方法での強誘電体薄膜の形成が盛んに研究されるようになってきた。 Therefore, recently, active research has been conducted on the formation of ferroelectric thin films by methods such as sputtering, sol-gel, MOCVD (chemical vapor deposition), and PLD (pulsed laser deposition), which have proven results as thin film growth technologies. It has come to be.
例えば、調整したゾルを塗布し、乾燥、脱脂、焼成（焼成温度５５０℃〜７５０℃）の工程を行い初期層を形成した後、この初期層の上に、同様に調整したゾルを塗布し、乾燥、脱脂、焼成（焼成温度５５０℃〜７５０℃）の工程を行い後期層を形成する強誘電体薄膜の形成方法が知られている（例えば、特許文献１参照）。 For example, after applying an adjusted sol, drying, degreasing, and firing (calcination temperature: 550 ° C. to 750 ° C.) to form an initial layer, an initial adjustment layer is applied on the initial layer, A method for forming a ferroelectric thin film is known in which drying, degreasing, and firing (firing temperature: 550 ° C. to 750 ° C.) are performed to form a late layer (see, for example, Patent Document 1).
近い将来は、まず、ゾルゲル法やスパッタリング法で実用化が進むと思われるが、将来的には、膜質の良さ、成膜の高速性、複雑な形状への対応性の面から考えると、ＭＯＣＶＤ法が圧電マイクロアクチュエータの応用に広く用いられるようになると予想されている。 In the near future, sol-gel method and sputtering method will be put to practical use first, but in the future, considering the good film quality, high speed of film formation, and compatibility with complex shapes, MOCVD The method is expected to be widely used in piezoelectric microactuator applications.
現在、強誘電体薄膜のＭＯＣＶＤ法による成長は、有機金属原料の蒸気圧を使って原料を供給するバブリング法か、溶媒に溶かした有機金属原料を液体供給装置で供給するＬＤＳ（Ｌｉｑｕｉｄ Ｄｅｌｉｖｅｒｙ Ｓｙｓｔｅｍ）法のどちらかを使って原料を供給し、リアクタで６００℃程度に加熱することで原料を分解し、基材上に薄膜を成長させている。現状、他の薄膜形成方法よりも結晶粒サイズが小さくて均一であり、優れた絶縁破壊特性を有する良質な薄膜が形成できている。
前記の通り、圧電アクチュエータに用いるためには強誘電体薄膜の膜厚は２μｍ以上であることが望まれる。それゆえ、薄膜の成長は成長速度が高いことが望まれる。ＬＤＳ法で原料供給を行うＭＯＣＶＤ法では、有機金属原料の蒸気圧に依らず原料を供給できるので、高いレートでの安定した原料供給が可能であり、成長速度を著しく大きくできる。 As described above, the thickness of the ferroelectric thin film is desirably 2 μm or more in order to be used for a piezoelectric actuator. Therefore, the growth rate of the thin film is desired to be high. In the MOCVD method in which the raw material is supplied by the LDS method, the raw material can be supplied regardless of the vapor pressure of the organic metal raw material, so that the raw material can be stably supplied at a high rate and the growth rate can be remarkably increased.
しかしながら、成長速度を高くすると、強誘電体薄膜の結晶粒のサイズが不均一でしかも大きくなってしまうという問題がある。このような薄膜では、絶縁破壊が起こりやすくなり、良好な圧電特性が得られなくなる。成長速度を低くすると、強誘電体薄膜の結晶粒のサイズは均一で小さくできるが、成長に長い時間がかかるため実用的ではない。 However, when the growth rate is increased, there is a problem that the size of the crystal grains of the ferroelectric thin film is nonuniform and large. In such a thin film, dielectric breakdown tends to occur, and good piezoelectric characteristics cannot be obtained. If the growth rate is lowered, the crystal grain size of the ferroelectric thin film can be made uniform and small, but it is not practical because it takes a long time to grow.
そこで、本発明の目的は、上記課題を解決し、結晶粒のサイズが小さくて均一な良質の強誘電体薄膜を、ＭＯＣＶＤ法を用いて短時間（高い成長速度）で成長する方法を提供することにある。 Accordingly, an object of the present invention is to solve the above problems and provide a method for growing a high-quality ferroelectric thin film having a small crystal grain size and a uniform quality in a short time (high growth rate) using the MOCVD method. There is.
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形成方法は、主として、不揮発性メモリ、圧電素子、焦電素子用として用いられる強誘電体薄膜をＭＯＣＶＤ法で成長する際に、強誘電体薄膜の膜厚が１０nm以下の時点で、有機金属原料の供給を中断することで薄膜成長を５秒以上中断させ、その後、再び有機金属原料の供給を行いＭＯＣＶＤ法で成長させる工程を有することを特徴とする。
The method for forming a ferroelectric thin film according to the invention of
請求項２の発明に係る強誘電体薄膜の形成方法は、主として、不揮発性メモリ、圧電素子、焦電素子用として用いられる強誘電体薄膜をＭＯＣＶＤ法で成長する際に、少なくとも成長開始から膜厚１０nmまでの成長途中に、有機金属原料の供給を中断し再供給することで成長と５秒以上の成長中断を繰り返す工程を有することを特徴とする。 According to a second aspect of the present invention, there is provided a method for forming a ferroelectric thin film, which is a film formed at least from the start of growth when a ferroelectric thin film used for a nonvolatile memory, a piezoelectric element, or a pyroelectric element is grown by MOCVD. It is characterized by having a step of repeating the growth and the interruption of growth for 5 seconds or more by interrupting and resupplying the organometallic raw material during the growth to a thickness of 10 nm.
請求項３の発明は、請求項１記載の強誘電体薄膜の形成方法において、上記膜厚１０nmまでの成長を行った後、成長速度を高め、最終的な所定膜厚（例えば２μｍ程度）まで高速成長することを特徴とする。 According to a third aspect of the present invention, in the method for forming a ferroelectric thin film according to the first aspect, after the growth up to the film thickness of 10 nm, the growth rate is increased to a final predetermined film thickness (for example, about 2 μm). It is characterized by high-speed growth.
請求項４の発明は、請求項３記載の強誘電体薄膜の形成方法において、上記高速成長の過程中に、徐々に成長速度を高くする過程を含ませることを特徴とする。 According to a fourth aspect of the present invention, in the method for forming a ferroelectric thin film according to the third aspect, the process of gradually increasing the growth rate is included in the high-speed growth process.
請求項５の発明は、請求項１〜４のいずれかに記載の強誘電体薄膜の形成方法において、上記強誘電体薄膜が、ＰＺＴ、ＰＬＺＴ、ＳＢＴ、ＢＩＴ、ＢＳＴ、ＬｉＮｂＯ3、ＳｒＢｉ2Ｎｂ2Ｏ9のいずれかであることを特徴とする。 A fifth aspect of the present invention is the method for forming a ferroelectric thin film according to any one of the first to fourth aspects, wherein the ferroelectric thin film is PZT, PLZT, SBT, BIT, BST, LiNbO 3 , SrBi 2 Nb. It is any one of 2 O 9 .
本発明によれば、ＭＯＣＶＤ法で強誘電体薄膜を成長する際、成長初期の成長膜厚１０nm以下の時点で、一度、有機金属原料の供給を止めることで任意時間成長を中断するか、又は、この少なくとも成長開始から膜厚１０nmまでの成長途中に、有機金属原料の供給を中断し再供給することで成長と５秒以上の成長中断を繰り返す工程を含ませる。この成長中断の間に、それまでに成長された強誘電体薄膜の結晶化が進み、結晶粒が均一で小さい良質な薄膜になる。その良質になった薄膜上に再び強誘電体薄膜をＭＯＣＶＤ法で成長すると、下地の良質な結晶性を引き継ぎ、良質な薄膜が形成できる。この時、中断後の再成長において成長速度を高くしても、下地の良質な結晶性を引き継ぐために良質な薄膜が成長できる。 According to the present invention, when a ferroelectric thin film is grown by the MOCVD method, the growth is interrupted for an arbitrary time by stopping the supply of the organometallic raw material once at the initial growth thickness of 10 nm or less, or In the middle of the growth from the start of the growth to the film thickness of 10 nm, a step of repeating the growth and the interruption of growth for 5 seconds or more by interrupting the supply of the organic metal raw material and supplying it again is included. While this growth is interrupted, crystallization of the ferroelectric thin film grown so far proceeds, and a high-quality thin film with uniform and small crystal grains is obtained. When a ferroelectric thin film is grown again on the thin film with the good quality by the MOCVD method, the good quality thin film can be formed by taking over the good crystallinity of the base. At this time, even if the growth rate is increased in the regrowth after the interruption, a good quality thin film can be grown in order to take over the good crystallinity of the base.
従って、本発明によれば、結晶粒のサイズが小さくて均一な良質の強誘電体薄膜を、ＭＯＣＶＤ法を用いて短時間（高い成長速度）で成長することができる。 Therefore, according to the present invention, a high-quality ferroelectric thin film having a small crystal grain size and uniform quality can be grown in a short time (high growth rate) using the MOCVD method.
以下、本発明を図示の実施の形態に基づいて説明する。 Hereinafter, the present invention will be described based on the illustrated embodiments.
図１に、本発明の実施形態に係る強誘電体薄膜（ＰＺＴ薄膜）の形成方法を示す。 FIG. 1 shows a method for forming a ferroelectric thin film (PZT thin film) according to an embodiment of the present invention.
ＭＯＣＶＤ法を用いて、まず、成長開始から膜厚１０nmまでのＰＺＴ薄膜の成長（初期成長）を、通常の成長速度、例えば１．０nm／ｓｅｃにて行う。ただし、膜厚が１０nm以下の任意の厚さまで成長した時点（図１（ａ））で、有機金属原料の供給を中断し、薄膜成長を５秒以上中断させる（図１（ｂ））。このように膜厚１０nmまでの初期成長途中に５秒以上の成長中断を１回又は複数回置くことで、成長中断の間に、それまでに成長された強誘電体薄膜の結晶化が進み、結晶粒が均一で小さい良質な薄膜となる。 First, growth (initial growth) of a PZT thin film from the start of growth to a film thickness of 10 nm is performed at a normal growth rate, for example, 1.0 nm / sec. However, when the film thickness grows to an arbitrary thickness of 10 nm or less (FIG. 1 (a)), the supply of the organometallic raw material is interrupted, and the thin film growth is interrupted for 5 seconds or longer (FIG. 1 (b)). Thus, by placing one or more growth interruptions of 5 seconds or more during the initial growth up to a film thickness of 10 nm, the crystallization of the ferroelectric thin film grown so far proceeds during the growth interruption, It becomes a high-quality thin film with uniform and small crystal grains.
その後、成長を再開し（図１（ｃ））、最終の所定膜厚２μｍになるまで成長する（図１（ｅ））。下地の良質な結晶性を引き継ぎ、逐次良質な薄膜が形成される。 Thereafter, the growth is resumed (FIG. 1C), and the growth is continued until the final predetermined film thickness is 2 μm (FIG. 1E). Successive high-quality thin films are formed by taking over the high-quality crystallinity of the base.
本発明では、上記成長の中断、再開の後、上記膜厚１０nmまでの成長を行った後の任意の時点、例えば膜厚がある程度の厚さに達した時点で、成長速度を通常の成長速度１．０nm／ｓｅｃよりも高速にしてもよい（図１（ｄ））。このように成長速度を高めても、同様に下地の良質な結晶性を引き継いで行くため、良質な薄膜が形成される。また短時間で良質な薄膜が形成できる。 In the present invention, after the growth is interrupted and resumed, the growth rate is changed to a normal growth rate at an arbitrary time after the growth to the film thickness of 10 nm, for example, when the film thickness reaches a certain thickness. The speed may be higher than 1.0 nm / sec (FIG. 1 (d)). Even if the growth rate is increased in this way, the high-quality thin film is formed because the high-quality crystallinity of the base is similarly taken over. In addition, a good quality thin film can be formed in a short time.
＜実施例１（ヒステリシス測定、絶縁破壊特性の比較）＞
本発明の実施例１としての強誘電体薄膜を形成すると共に、比較例として従来技術の強誘電体薄膜を形成した。そして、本発明を用いた場合と、従来技術を用いた場合で、強誘電体薄膜のヒステリシス測定、絶縁破壊特性を比較した。
<Example 1 (hysteresis measurement, comparison of dielectric breakdown characteristics)>
A ferroelectric thin film as Example 1 of the present invention was formed, and a conventional ferroelectric thin film was formed as a comparative example. The hysteresis measurement and dielectric breakdown characteristics of the ferroelectric thin film were compared between the case of using the present invention and the case of using the prior art.
基材には表面に酸化膜（ＳｉＯ2）が付いているＳｉ（１００）基板を用い、その上にＥＢ蒸着法で密着層Ｔｉ（５０nm）と下部電極Ｐｔ（１００nm）を順に２試料形成した。その上に、一方（比較例）では、従来技術の通りのＭＯＣＶＤ法を用いて成長中断無しで２μｍのＰＺＴ薄膜を成長し、もう一方（比較例）では、本発明を用いて、膜厚５nmのＰＺＴ薄膜を成長したところで、有機金属原料の供給を止めることで１５分間の成長中断を入れ、その後、成長を再開して、厚さ２μｍになるまで成長した。 A Si (100) substrate having an oxide film (SiO 2 ) on the surface was used as a base material, and two samples of an adhesion layer Ti (50 nm) and a lower electrode Pt (100 nm) were formed on the substrate by EB evaporation. . On the one hand (comparative example), a 2 μm thick PZT thin film is grown without interruption of growth using the MOCVD method as in the prior art, and on the other hand (comparative example), the present invention is used to form a film thickness of 5 nm. When the PZT thin film was grown, the supply of the organic metal raw material was stopped to interrupt the growth for 15 minutes, and then the growth was resumed until the thickness reached 2 μm.
強誘電体薄膜（ＰＺＴ薄膜）の成長に用いたＭＯＣＶＤ装置の構成を図２に示す。 The structure of the MOCVD apparatus used for the growth of the ferroelectric thin film (PZT thin film) is shown in FIG.
原料供給方法としては、高い成長速度での成長が実現できる液体原料供給システム（ＬＤＳ）を用いた。有機金属原料としては、Ｐｂ（ｄｐｍ）2、Ｚｒ（ｄｐｍ）4、Ｔｉ（ｄｐｍ）2（ＯｉＰｒ）を使用し、それらを溶媒であるＴＨＦ（テトラヒドロフラン）に溶かし込み、有機金属シリンダー１に入れた。
As a raw material supply method, a liquid raw material supply system (LDS) capable of realizing growth at a high growth rate was used. Pb (dpm) 2 , Zr (dpm) 4 , Ti (dpm) 2 (OiPr) were used as the organic metal raw material, and these were dissolved in THF (tetrahydrofuran) as a solvent and put in the
原料を供給する際は、液体ＭＦＣ（マスフローコントローラ）２で一定量の原料を気化器３に送り込み、気化器３で３００℃の温度で一気に気化し、そのままリアクタ４に供給した。また別ルートから酸素Ｏ2を供給した。リアクタ４では基材（基板）５をヒータ６で５５０℃に加熱し、原料を熱分解させることで、基材５上にＰＺＴ薄膜を成長させた。 When supplying the raw material, a fixed amount of the raw material was sent to the vaporizer 3 by the liquid MFC (mass flow controller) 2, vaporized at a temperature of 300 ° C. at the vaporizer 3, and supplied to the reactor 4 as it was. In addition, oxygen O 2 was supplied from another route. In the reactor 4, the base material (substrate) 5 was heated to 550 ° C. with the heater 6, and the PZT thin film was grown on the base material 5 by thermally decomposing the raw material.
成長時の排気は、ロータリーポンプ７で行い、リアクタ４内の圧力が１０Ｔｏｒｒになるように調整した。
Exhaust during growth was performed by the
ＭＯＣＶＤの成長条件は、実施例１及び比較例の両方とも全く同じであり、基板温度５５０℃、リアクタ圧力１０Ｔｏｒｒで行った。 The growth conditions for MOCVD were exactly the same for both Example 1 and Comparative Example, and were performed at a substrate temperature of 550 ° C. and a reactor pressure of 10 Torr.
その後、強誘電体薄膜上に上部電極Ｐｔ（１００nm）をＥＢ（電子ビーム）蒸着法で形成し、ＲＩＥ（反応性イオンエッチング）で上部電極を５mm角の形状に加工した。 Thereafter, an upper electrode Pt (100 nm) was formed on the ferroelectric thin film by EB (electron beam) vapor deposition, and the upper electrode was processed into a 5 mm square shape by RIE (reactive ion etching).
ヒステリシスループを測定した結果を図３に示す。印加電界は２００ｋＶ／cmで行った。従来技術で作製したＰＺＴ薄膜（比較例）では残留分極２Ｐｒが６０μＣ／cm2であるのに対して、本発明を用いたＰＺＴ薄膜（実施例１）では２Ｐｒが７５μＣ／cm2であり、本発明により残留分極が向上していることが分かる。 The result of measuring the hysteresis loop is shown in FIG. The applied electric field was 200 kV / cm. In the PZT thin film (comparative example) produced by the prior art, the remanent polarization 2Pr is 60 μC / cm 2 , whereas in the PZT thin film using the present invention (Example 1), 2Pr is 75 μC / cm 2 , It can be seen that the invention improves the remanent polarization.
また、同じ試料を用いて絶縁破壊特性を測定した結果を図４に示す。従来技術で作製したＰＺＴ薄膜では絶縁破壊電界が６５０ｋＶ／cm2であるのに対して、本発明を用いたＰＺＴ薄膜では絶縁破壊電圧が９００ｋＶ／cm2であり、本発明によって絶縁破壊電圧が向上したことが分かる。参考までに、ＰＺＴの膜厚は異なるが、スクリーン印刷法で作製したＰＺＴ薄膜とバルク材の機械加工で作製したＰＺＴ薄膜の一般的な絶縁破壊電圧も図４に記載した。スクリーン印刷法やバルク機械加工品と比べると、本発明を用いたＰＺＴ薄膜は、格段に大きな絶縁破壊特性を有していることが分かる。 Moreover, the result of having measured the dielectric breakdown characteristic using the same sample is shown in FIG. The PZT thin film produced by the prior art has a dielectric breakdown electric field of 650 kV / cm 2 , whereas the PZT thin film using the present invention has a dielectric breakdown voltage of 900 kV / cm 2 , and the dielectric breakdown voltage is improved by the present invention. I understand that. For reference, although the film thickness of PZT is different, the general breakdown voltage of the PZT thin film produced by the screen printing method and the PZT thin film produced by machining the bulk material is also shown in FIG. It can be seen that the PZT thin film using the present invention has much larger dielectric breakdown characteristics than the screen printing method and the bulk machined product.
＜実施例２＞
次に、実施例２として、片持ち針構造圧電アクチュエータを作成し、その特性を比較した。
<Example 2>
Next, as Example 2, a cantilever needle-type piezoelectric actuator was prepared, and its characteristics were compared.
実施例１と同様の方法で、基材／Ｔｉ密着層／Ｐｔ下部電極／ＰＺＴ薄膜／Ｐｔ上部電極を、従来技術と本発明の方法の両方で作製した。それらを、ＲＩＥ（エッチングガス＝ＳＦ6／Ａｒ／Ｏ2）とウエットエッチング（水酸化テトラメチルアンモニウム）を用いて、片持ち針構造の圧電マイクロアクチュエータを作製した。 In the same manner as in Example 1, a substrate / Ti adhesion layer / Pt lower electrode / PZT thin film / Pt upper electrode were produced by both the conventional technique and the method of the present invention. Using them, RIE (etching gas = SF 6 / Ar / O 2 ) and wet etching (tetramethylammonium hydroxide) were used to fabricate a piezoelectric microactuator with a cantilever needle structure.
この圧電マイクロアクチュエータの圧電特性を、強誘電体テスターとレーザドップラー干渉計を用いて測定した。その結果から、それぞれのＰＺＴ薄膜の圧電定数（-ｄ31）を算出した。圧電定数（-ｄ31）は、従来技術品では１００ｐｍ／Ｖであるのに対して、本発明品では１４０ｐｍ／Ｖであった。本発明によって、従来技術に比べて大幅に圧電特性が向上していることが確認できた。 The piezoelectric characteristics of the piezoelectric microactuator were measured using a ferroelectric tester and a laser Doppler interferometer. From the result, the piezoelectric constant (−d 31 ) of each PZT thin film was calculated. The piezoelectric constant (−d 31 ) was 100 pm / V in the prior art product, whereas it was 140 pm / V in the product of the present invention. It was confirmed that the piezoelectric characteristics were greatly improved by the present invention compared to the prior art.
１ 有機金属シリンダー
２ 液体ＭＦＣ
３ 気化器
４ リアクタ
５ 基材
６ ヒータ
７ ロータリーポンプ
1
3 Vaporizer 4 Reactor 5 Base Material 6
Claims (5)
上記膜厚１０nmまでの成長を行った後、成長速度を高め、最終的な所定膜厚まで高速成長することを特徴とする強誘電体薄膜の形成方法。 In the formation method of the ferroelectric thin film of Claim 1,
A method for forming a ferroelectric thin film, characterized in that after the film is grown to a thickness of 10 nm, the growth rate is increased and the film is grown at a high speed to a final predetermined film thickness.
上記高速成長の過程中に、徐々に成長速度を高くする過程を含ませることを特徴とする強誘電体薄膜の形成方法。 In the formation method of the ferroelectric thin film of Claim 3,
A method for forming a ferroelectric thin film, comprising the step of gradually increasing the growth rate in the high-speed growth process.
上記強誘電体薄膜が、ＰＺＴ、ＰＬＺＴ、ＳＢＴ、ＢＩＴ、ＢＳＴ、ＬｉＮｂＯ3、ＳｒＢｉ2Ｎｂ2Ｏ9のいずれかであることを特徴とする強誘電体薄膜の形成方法。 In the formation method of the ferroelectric thin film in any one of Claims 1-4,
A method for forming a ferroelectric thin film, wherein the ferroelectric thin film is any one of PZT, PLZT, SBT, BIT, BST, LiNbO 3 and SrBi 2 Nb 2 O 9 .
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