JP3478095B2 - Ferroelectric thin film element and method of manufacturing the same - Google Patents
Ferroelectric thin film element and method of manufacturing the sameInfo
- Publication number
- JP3478095B2 JP3478095B2 JP33073397A JP33073397A JP3478095B2 JP 3478095 B2 JP3478095 B2 JP 3478095B2 JP 33073397 A JP33073397 A JP 33073397A JP 33073397 A JP33073397 A JP 33073397A JP 3478095 B2 JP3478095 B2 JP 3478095B2
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- thin film
- ferroelectric
- ferroelectric layer
- mmol
- aqueous solution
- Prior art date
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水熱合成法を用い
た強誘電体薄膜の製造方法および強誘電体薄膜素子に関
する。これらの薄膜素子は、圧力センサ、加速度セン
サ、超音波センサ、赤外線センサ、圧電アクチュエータ
等、その他各種圧電、強誘電体素子の用途に使用するこ
とができる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ferroelectric thin film using a hydrothermal synthesis method and a ferroelectric thin film element. These thin film elements can be used for pressure sensors, acceleration sensors, ultrasonic sensors, infrared sensors, piezoelectric actuators, and other various piezoelectric and ferroelectric elements.
【０００２】[0002]
【従来の技術】チタン酸ジルコン酸鉛（以下ＰＺＴと記
載する）に代表される強誘電体薄膜は、スパッタリング
法、ゾルゲル法、ＣＶＤ法、水熱法等で形成することが
できる。強誘電体薄膜はフォトエッチング工程を用いた
パターンニングが可能で、バルクあるいはスクリーン印
刷成型品のように、切り出し、研磨、位置合わせ、張り
付け等をする必要がない。膜厚を厚くするためには、成
膜する堆積時間を増加させたり、成膜を複数回繰り返す
ことにより対応している。2. Description of the Related Art A ferroelectric thin film represented by lead zirconate titanate (hereinafter referred to as PZT) can be formed by a sputtering method, a sol-gel method, a CVD method, a hydrothermal method or the like. The ferroelectric thin film can be patterned by using a photo-etching process, and it is not necessary to cut out, polish, align, and attach the thin film unlike a bulk or screen printing molded product. To increase the film thickness, the deposition time for film formation is increased or the film formation is repeated a plurality of times.
【０００３】強誘電体薄膜の水熱法以外の製造方法は、
１μｍ以上の厚い膜、特に１〜５０μｍの中間的な厚さ
の膜を製造するには適さず、高温の熱処理を必要とした
り、非常に長時間を要したり、また厚膜化できてもクラ
ックが発生するなどの問題を有するため、歩留まりが悪
く、高コストとなっている。インクジェット記録装置、
圧力センサ、加速度センサ、超音波センサ等に圧電素子
として用いる場合、２〜数１０μｍ程度の厚膜が必要と
なる。水熱法は厚膜化が容易である上、結晶粒子が大き
く、優れた特性の圧電体、強誘電体薄膜素子を製造でき
る可能性がある。特に、結晶粒子が大きいほど圧電特性
が優れている傾向があり、結晶を成長させ、大きい結晶
粒子の薄膜を作製することが望まれる。ところが水熱法
で得られた強誘電体薄膜の表面は、好ましい結晶粒子の
大きさが数μｍ以上であるため、結晶粒子に起因する段
差が大きく、その上に断線なく電極を形成するのが困難
であった。A method of manufacturing a ferroelectric thin film other than the hydrothermal method is as follows:
It is not suitable for producing a thick film having a thickness of 1 μm or more, particularly a film having an intermediate thickness of 1 to 50 μm, and requires a high temperature heat treatment, takes a very long time, or can be made thicker. Since it has problems such as cracks, the yield is low and the cost is high. Inkjet recording device,
When used as a piezoelectric element in a pressure sensor, an acceleration sensor, an ultrasonic sensor, etc., a thick film of 2 to several tens of μm is required. In the hydrothermal method, it is easy to form a thick film, and since the crystal grains are large, there is a possibility that a piezoelectric or ferroelectric thin film element having excellent characteristics can be manufactured. In particular, the larger the crystal grains, the more excellent the piezoelectric characteristics tend to be. Therefore, it is desired to grow crystals to prepare a thin film of large crystal grains. However, on the surface of the ferroelectric thin film obtained by the hydrothermal method, since the preferable crystal grain size is several μm or more, the step due to the crystal grain is large, and it is not possible to form an electrode on it without disconnection. It was difficult.
【０００４】この問題を解決する方法として、特開平６
−１１２５４３公報には、水熱法により形成された第一
強誘電体層の上に、ゾルゲル法で第二強誘電体層を形成
することが記載されている。また、スパッタ法、ＣＶＤ
法では、長時間成膜しても素子の信頼性が得られないこ
とも記述されている。As a method for solving this problem, Japanese Unexamined Patent Publication No. Hei 6 (1994)
-112543 discloses that a second ferroelectric layer is formed by a sol-gel method on a first ferroelectric layer formed by a hydrothermal method. Also, sputtering method, CVD
It is also described in the method that the reliability of the device cannot be obtained even if the film is formed for a long time.
【０００５】しかしながら、ゾルゲル法では、原料が高
価であり、ペロブスカイト構造とするため成膜後５００
〜７００℃の酸素雰囲気でアニール処理する必要があ
る。このため、素子の製造に余分な工程が入るだけでな
く、基板上に形成した膜を高温で加熱するため、膜と基
板との間に応力が発生し、はがれやすくなり、素子の信
頼性が落ちるという問題がある。However, in the sol-gel method, the raw material is expensive, and the perovskite structure is used.
It is necessary to anneal in an oxygen atmosphere of up to 700 ° C. Therefore, not only an extra step is required for manufacturing the element, but also since the film formed on the substrate is heated at a high temperature, stress is generated between the film and the substrate, peeling easily occurs, and reliability of the element is reduced. There is a problem of falling.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、上記のよう
な問題点を解決するするもので、その目的とするところ
は、厚膜化が容易で、５００℃以上の高温での熱処理を
必要とせず、素子信頼性が高い、強誘電体薄膜の製造方
法と強誘電体素子を提供することにある。DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, and its object is to easily form a thick film and to require heat treatment at a high temperature of 500 ° C. or higher. Another object of the present invention is to provide a ferroelectric thin film manufacturing method and a ferroelectric device having high device reliability.
【０００７】[0007]
【課題を解決するための手段】本発明は、水熱合成する
原料溶液を０〜１００℃の範囲内で反応させ、平均粒子
径２０〜１０００ｎｍの微粒子を溶液内に生成させた
後、水熱合成することにより強誘電体膜上に表面粗さＲ
ｍａｘが２μｍ以下の強誘電体薄膜を形成することを特
徴とする強誘電体薄膜の製造方法に関する。According to the present invention, a raw material solution for hydrothermal synthesis is reacted in the range of 0 to 100 ° C. to generate fine particles having an average particle diameter of 20 to 1000 nm in the solution, and then hydrothermal synthesis is performed. By synthesizing the surface roughness R on the ferroelectric film
The present invention relates to a method of manufacturing a ferroelectric thin film, which comprises forming a ferroelectric thin film having a max of 2 μm or less.
【０００８】本発明は、Ｐｂ含有原料化合物が５０〜５
００ｍｍｏｌ／ｌ、Ｚｒ含有原料化合物が０〜５００ｍ
ｍｏｌ／ｌ、Ｔｉ含有原料化合物が０．００２〜５００
ｍｍｏｌ／ｌおよびＬａ含有原料化合物が０〜５０ｍｍ
ｏｌ／ｌの条件でアルカリ水溶液中０〜１００℃の温度
範囲内で反応させ、Ｐｂ、Ｌａ，ＺｒおよびＴｉのうち
少なくとも一つを含有する平均粒子径２０〜１０００ｎ
ｍの微粒子を生成させた後、水熱合成することにより強
誘電体層の上に表面粗さＲｍａｘが２μｍ以下の強誘電
体層を形成することを特徴とする強誘電体薄膜の製造方
法に関する。In the present invention, the Pb-containing starting compound is 50 to 5
00 mmol / l, the Zr-containing raw material compound is 0 to 500 m
mol / l, Ti-containing raw material compound is 0.002-500
mmol / l and La-containing raw material compound is 0 to 50 mm
The reaction is carried out in an alkaline aqueous solution at a temperature range of 0 to 100 ° C. under the condition of ol / l, and an average particle size of at least one of Pb, La, Zr and Ti is 20 to 1000 n
A method for producing a ferroelectric thin film, characterized in that a ferroelectric layer having a surface roughness R max of 2 μm or less is formed on the ferroelectric layer by hydrothermally synthesizing fine particles of m. Regarding
【０００９】さらに、本発明は、基板と、前記の方法で
製造された表面粗さＲｍａｘが２μｍ以下の強誘電体膜
と、その上に形成された電極とからなる強誘電体薄膜素
子に関する。Further, the present invention relates to a ferroelectric thin film element comprising a substrate, a ferroelectric film having a surface roughness R max of 2 μm or less manufactured by the above method, and an electrode formed thereon. .
【００１０】[0010]
【発明の実施の形態】強誘電体層の上に表面粗さＲ
ｍａｘが２μｍ以下の薄膜を形成する方法について、以
下説明する。なお、表面粗さＲｍａｘは、面の凸部の最
高点と凹部の最低点の差で定義する。BEST MODE FOR CARRYING OUT THE INVENTION Surface roughness R on a ferroelectric layer
A method for forming a thin film having a max of 2 μm or less will be described below. The surface roughness R max is defined as the difference between the highest point of the convex portion and the lowest point of the concave portion of the surface.
【００１１】本発明の表面粗さＲｍａｘが２μｍ以下の
薄膜は、水熱合成する原料溶液を０〜１００℃の温度範
囲内で反応させ、溶液中に平均粒子径２０〜１０００ｎ
ｍの微粒子を生成させ、その後、強誘電体膜を浸し、そ
の上に水熱合成で膜を形成することにより得られる。The thin film having a surface roughness R max of 2 μm or less according to the present invention is obtained by reacting a raw material solution for hydrothermal synthesis within a temperature range of 0 to 100 ° C. to have an average particle size of 20 to 1000 n.
It is obtained by forming fine particles of m, then dipping the ferroelectric film, and forming the film by hydrothermal synthesis on it.
【００１２】さらに、詳しくは、アルカリ濃度が１６６
〜８０６６ｍｍｏｌ／ｌ、Ｐｂ含有原料化合物が５０〜
５００ｍｍｏｌ／ｌ、Ｚｒ含有原料化合物が０〜５００
ｍｍｏｌ／ｌ、Ｔｉ含有原料化合物が０．００２〜５０
０ｍｍｏｌ／ｌおよびＬａ含有原料化合物が０〜５０ｍ
ｍｏｌ／ｌの条件でアルカリ水溶液中０〜１００℃の温
度範囲内で反応させ、Ｐｂ、Ｌａ，ＺｒおよびＴｉのう
ち少なくとも一つを含有する平均粒子径２０〜１０００
ｎｍの微粒子を生成させた後、この溶液に表面粗さの大
きい強誘電体層を形成した基板を浸し、水熱合成するこ
とにより、強誘電体層の上に表面粗さＲｍａｘが２μｍ
以下の強誘電体層を形成することができる。More specifically, the alkali concentration is 166.
˜8066 mmol / l, Pb-containing raw material compound is 50˜
500 mmol / l, the Zr-containing raw material compound is 0 to 500
mmol / l, the Ti-containing raw material compound is 0.002 to 50
0 mmol / l and La-containing raw material compound is 0 to 50 m
The reaction is carried out in a temperature range of 0 to 100 ° C. in an alkaline aqueous solution under the condition of mol / l, and an average particle size of at least one of Pb, La, Zr and Ti is 20 to 1000.
After generating fine particles of nm, the substrate on which the ferroelectric layer having a large surface roughness is formed is dipped in this solution and hydrothermally synthesized to obtain a surface roughness R max of 2 μm on the ferroelectric layer.
The following ferroelectric layers can be formed.
【００１３】本発明においてＰｂ１−ｘＬａｘ（Ｚｒｙ
Ｔｉ１−ｙ）１−ｘ／４Ｏ３（ただし、０≦ｘ＜１、０
≦ｙ＜１である。）膜を製造する場合に使用されるＰ
ｂ，Ｌａ，ＺｒおよびＴｉの構成元素を含有する原料化
合物としては、塩化物、オキシ塩化物、硝酸塩、アルコ
キシド、酢酸塩、水酸化物、酸化物等が好ましい。使用
されるアルカリ化合物としては、例えば、ＫＯＨ，Ｎａ
ＯＨ等のアルカリ金属の水酸化物をあげることができ
る。In the present invention, Pb 1-x La x (Zr y
Ti 1-y ) 1-x / 4 O 3 (where 0 ≦ x <1, 0
≦ y <1. ) P used when manufacturing a membrane
As the raw material compound containing the constituent elements of b, La, Zr and Ti, chloride, oxychloride, nitrate, alkoxide, acetate, hydroxide, oxide and the like are preferable. Examples of the alkaline compound used include KOH, Na
Examples thereof include hydroxides of alkali metals such as OH.
【００１４】最初の反応の温度は、オートクレーブを使
う必要のない１００℃以下である。また、室温で反応さ
せることもできるので、その場合、加熱を必要としない
という利点がある。高温で反応させると生成する粒子
が、粒径の大きい結晶粒子となり、本発明の効果が得ら
れない。低温では、反応が遅くなるので、０℃以下は好
ましくない。The temperature of the first reaction is below 100 ° C., which makes it unnecessary to use an autoclave. Further, since the reaction can be performed at room temperature, in that case, there is an advantage that heating is not required. When the reaction is carried out at a high temperature, the particles produced become crystal particles having a large particle size, and the effect of the present invention cannot be obtained. At low temperatures, the reaction becomes slow, so 0 ° C or lower is not preferable.
【００１５】得られる粒子としては、大部分が非晶質粒
子であるが、結晶質粒子を含むものもあり、平均粒子径
２０〜１０００ｎｍの微粒子あるいは針状粒子から構成
されている。平均粒子径がこの範囲外では、平坦な表面
を得るという本発明の効果は得られない。粒子の集合体
は、仕込み原料により異なるが、Ｐｂ１−ｘＬａｘ（Ｚ
ｒｙＴｉ１−ｙ）１−ｘ／４Ｏ３（ただし、０≦ｘ＜
１、０≦ｙ＜１である。）膜を形成する場合は、Ｐｂ、
Ｌａ，Ｚｒ、Ｔｉ、ＯおよびＨ、またはＰｂ、Ｚｒ、Ｔ
ｉ、ＯおよびＨ、またはＰｂ、Ｔｉ、ＯおよびＨを含ん
でいる。Most of the obtained particles are amorphous particles, but some include crystalline particles, and are composed of fine particles or acicular particles having an average particle diameter of 20 to 1000 nm. If the average particle diameter is outside this range, the effect of the present invention of obtaining a flat surface cannot be obtained. The aggregate of particles varies depending on the charged raw materials, but Pb 1-x La x (Z
r y Ti 1-y ) 1-x / 4 O 3 (where 0 ≦ x <
1, 0 ≦ y <1. ) When forming a film, Pb,
La, Zr, Ti, O and H, or Pb, Zr, T
i, O and H, or Pb, Ti, O and H.
【００１６】この微粒子を含んだ前記溶液に、強誘電体
層を形成した基板を浸し、通常１００〜２００℃の温度
範囲で水熱合成することにより、目的とする強誘電体膜
が得られる。The desired ferroelectric film is obtained by immersing the substrate on which the ferroelectric layer is formed in the solution containing the fine particles and performing hydrothermal synthesis in the temperature range of usually 100 to 200 ° C.
【００１７】上記の方法により、表面粗さの大きい強誘
電体層上に表面粗さの小さい強誘電体層を形成すること
ができ、必要に応じてこの方法を繰り返すことにより、
Ｒｍａｘが２μｍ以下の強誘電体薄膜が得られる。これ
により、５００℃以上の温度で加熱処理を必要としな
い、信頼性の高い強誘電体素子が得られる。By the above method, a ferroelectric layer having a small surface roughness can be formed on a ferroelectric layer having a large surface roughness, and by repeating this method as necessary,
A ferroelectric thin film having R max of 2 μm or less is obtained. This makes it possible to obtain a highly reliable ferroelectric element that does not require heat treatment at a temperature of 500 ° C. or higher.
【００１８】表面強誘電体層を形成する前の強誘電体層
は、一層とは限らず、何層でもよい。ただし、その中の
少なくとも一層は、圧電特性を上げるための層であるこ
とが好ましく、通常、平均粒径は大きい方が好ましく、
それにつれて、表面粗さも大きくなる。The ferroelectric layer before forming the surface ferroelectric layer is not limited to one layer and may be any number of layers. However, at least one of them is preferably a layer for improving piezoelectric properties, and generally, a larger average particle size is preferable,
Along with that, the surface roughness also increases.
【００１９】表面強誘電体層を形成する前の強誘電体層
の構成により、さまざまな素子が可能である。Various devices are possible depending on the structure of the ferroelectric layer before forming the surface ferroelectric layer.
【００２０】基板上の第一層が、圧電性を上げるための
平均粒子が大きい粒子からなる層であり、第二層で平坦
化する層を形成した強誘電体素子は、高い圧電性と信頼
性を兼ね備えた素子となる。The first layer on the substrate is a layer composed of particles having large average particles for increasing the piezoelectricity, and the ferroelectric element in which the flattening layer is formed by the second layer has high piezoelectricity and reliability. It becomes an element having both properties.
【００２１】また、第一層を１μｍ以下の細かい粒子で
構成し、その上に素子特性を出すための平均粒子径１〜
１０μｍの結晶粒子からなる第２層を形成し、その上に
本発明の方法で平坦化した表面粗さＲｍａｘが２μｍ以
下の第３層を形成した強誘電体素子では、基板と素子と
の密着度が上がり、さらに高い信頼性が得られる。The first layer is composed of fine particles of 1 μm or less, and an average particle size of 1 to 1 is provided on the first layer to obtain device characteristics.
In a ferroelectric device in which a second layer composed of 10 μm crystal grains is formed, and a third layer having a surface roughness R max of 2 μm or less flattened by the method of the present invention is formed thereon, Adhesion is improved and higher reliability is obtained.
【００２２】本発明で使用される基板は特に限定されな
いが、ＴｉあるいはＮｉ金属の他に、結晶核形成時に基
板と溶液中の金属イオンとの反応による結晶膜と基板と
の密着力を大きくするために結晶膜の構成元素を少なく
とも１つ以上含有するような基板が好ましい。また、結
晶膜を構成する元素でコーティングした基板を使用する
こともできる。The substrate used in the present invention is not particularly limited, but in addition to Ti or Ni metal, the adhesion between the crystal film and the substrate is increased by the reaction between the substrate and the metal ions in the solution during the formation of crystal nuclei. Therefore, a substrate containing at least one or more constituent elements of the crystal film is preferable. It is also possible to use a substrate coated with the element forming the crystal film.
【００２３】本発明で用いる電極は特に限定されない
が、コストや量産性を考慮し最適なものを選定する。例
えば、スパッタリング法によるＮｉ、無電解メッキ法に
よるＮｉ，焼付けタイプのＡｇなどがある。その他、蒸
着によるＡｌ，スパッタリング法によるｐｔあるいはＡ
ｕなども用いることができる。しかし、基板に樹脂を用
いる場合には、高温にできないので焼付けタイプのＡｇ
電極は使用できない。The electrode used in the present invention is not particularly limited, but an optimum electrode is selected in consideration of cost and mass productivity. For example, there are Ni by sputtering method, Ni by electroless plating method, baking type Ag, and the like. In addition, Al by vapor deposition, pt or A by sputtering method
u and the like can also be used. However, when resin is used for the substrate, it cannot be heated to a high temperature, so baking type Ag
No electrodes can be used.
【００２４】このようにして表面粗さＲｍａｘを２μｍ
におさえた強誘電体膜に形成した電極は、断線がなく、
再現良く形成できる。これにより、厚膜化が容易で、５
００℃以上の高温での熱処理を必要とせず、基板と強誘
電体との剥離がなく、素子信頼性が高く、高い圧電ひず
み定数と高いヤング率をもつ圧電体、強誘電体素子が提
供できる。In this way, the surface roughness R max is 2 μm.
The electrode formed on the ferroelectric film that has been kept under the condition that there is no disconnection,
Can be formed with good reproducibility. This makes it easy to increase the film thickness, and
It is possible to provide a piezoelectric element and a ferroelectric element that do not require heat treatment at a high temperature of 00 ° C. or higher, have no separation between the substrate and the ferroelectric, have high element reliability, have a high piezoelectric strain constant and a high Young's modulus. .
【００２５】さらに、水熱法では、層を厚くするほど表
面粗さが大きくなり、形成する膜厚に限度があったが、
本発明の平坦化の方法を応用すれば、結晶成長後に平坦
化した層を形成し、さらにその上に結晶を成長させ、ま
た平坦化するという操作を繰り返せば、表面粗さを犠牲
にすることなく、厚さの大きい膜を形成することができ
る。Further, in the hydrothermal method, the thicker the layer, the greater the surface roughness, and there was a limit to the film thickness to be formed.
If the flattening method of the present invention is applied, the surface roughness can be sacrificed by repeating the operation of forming a flattened layer after crystal growth, growing a crystal on the flattened layer, and flattening the layer. In addition, a thick film can be formed.
【実施例】以下、本発明の実施例を示す。EXAMPLES Examples of the present invention will be shown below.
【００２６】実施例１
まずＰｂ（ＮＯ３）２水溶液１６ｍｍｏｌ／ｌ、ＺｒＯ
Ｃｌ２水溶液１０ｍｍｏｌ／ｌ、ＴｉＣｌ４水溶液１０
ｍｍｏｌ／ｌおよびＫＯＨ水溶液３００ｍｍｏｌ／ｌの
混合溶液（溶液合計量７００ｍｌ）を用意した。次にシ
リコン基板上にチタン電極を形成し、用意した混合溶液
中に浸し、オートクレーブを用いて１８０℃で２時間水
熱処理することで１０μｍ厚の第一強誘電体層のＰＺＴ
薄膜を形成した。その後、純水中で超音波洗浄し、１０
０℃で１２時間乾燥させた。このようにして得られた第
一強誘電体層のＰＺＴ薄膜は平均粒子径５μｍのキュー
ビック状ＰＺＴ結晶粒子で構成されており、表面粗さＲ
ｍａｘは４μｍであった。このようにして得られた第一
強誘電体層のＰＺＴ薄膜の表面ＳＥＭ写真を図１に示し
た。Example 1 First, 16 mmol / l of Pb (NO 3 ) 2 aqueous solution, ZrO 2
Cl 2 aqueous solution 10 mmol / l, TiCl 4 aqueous solution 10
A mixed solution of mmol / l and 300 mmol / l KOH aqueous solution (total solution amount 700 ml) was prepared. Next, a titanium electrode is formed on a silicon substrate, immersed in a prepared mixed solution, and hydrothermally treated at 180 ° C. for 2 hours in an autoclave to form a PZT layer of the first ferroelectric layer having a thickness of 10 μm.
A thin film was formed. Then, ultrasonically wash in pure water, and
It was dried at 0 ° C. for 12 hours. The PZT thin film of the first ferroelectric layer thus obtained is composed of cubic PZT crystal particles having an average particle diameter of 5 μm and has a surface roughness R
max was 4 μm. The surface SEM photograph of the PZT thin film of the first ferroelectric layer thus obtained is shown in FIG.
【００２７】次に、Ｐｂ（ＮＯ３）２水溶液７７ｍｍｏ
ｌ／ｌ，ＺｒＯＣｌ２水溶液３０．８ｍｍｏｌ／ｌ、Ｔ
ｉＣｌ４水溶液３０．８ｍｍｏｌ／ｌおよびＫＯＨ水溶
液１３８８．９ｍｍｏｌ／ｌを室温で２４時間撹拌混合
した混合溶液（溶液合計量７００ｍｌ）を用意した。こ
の時、溶液中には、平均粒子径５０ｎｍの微粒子が生成
していた。次に前記シリコン上に第一強誘電体層のＰＺ
Ｔ薄膜を形成した基板を、用意した混合溶液中に浸し、
オートクレーブを用いて１３０℃で１２時間水熱処理す
ることで４μｍ厚の第二強誘電体層のＰＺＴ薄膜を形成
した。その後、純水中で超音波洗浄し、１００℃で１２
時間乾燥させた。このようにして得られた第二強誘電体
層のＰＺＴ薄膜は平均粒子径１．０μｍのＰＺＴ結晶粒
子で構成されており、表面粗さＲｍａｘも０．５μｍ以
下であった。またこのようにして得られた第二強誘電体
層のＰＺＴ薄膜は、第一強誘電体層の凹部には厚く、凸
部には薄く形成されていた。このようにして得られた第
二強誘電体層のＰＺＴ薄膜の表面ＳＥＭ写真を図２に示
した。Next, a Pb (NO 3 ) 2 aqueous solution of 77 mmo
l / l, ZrOCl 2 aqueous solution 30.8 mmol / l, T
A mixed solution (total solution amount 700 ml) was prepared by stirring and mixing an iCl 4 aqueous solution of 30.8 mmol / l and a KOH aqueous solution of 1388.9 mmol / l at room temperature for 24 hours. At this time, fine particles having an average particle diameter of 50 nm were formed in the solution. Next, PZ of the first ferroelectric layer on the silicon
The substrate on which the T thin film is formed is immersed in the prepared mixed solution,
A PZT thin film of a 4 μm-thick second ferroelectric layer was formed by hydrothermal treatment at 130 ° C. for 12 hours using an autoclave. Then, ultrasonically clean in pure water,
Allowed to dry for hours. The PZT thin film of the second ferroelectric layer thus obtained was composed of PZT crystal particles having an average particle diameter of 1.0 μm, and the surface roughness R max was 0.5 μm or less. Further, the PZT thin film of the second ferroelectric layer thus obtained was formed thick in the concave portion and thin in the convex portion of the first ferroelectric layer. A surface SEM photograph of the PZT thin film of the second ferroelectric layer thus obtained is shown in FIG.
【００２８】図３にこの強誘電体薄膜の内部構造を模式
的に示す。基板の上に水熱合成により成長させた結晶粒
子からなる第一強誘電体層１１を形成し、その表面を小
さい粒子で平坦にした表面粗さＲｍａｘが０．５μｍ以
下の第二強誘電体層１２を形成した構造となっている。FIG. 3 schematically shows the internal structure of this ferroelectric thin film. A second ferroelectric layer having a surface roughness R max of 0.5 μm or less in which a first ferroelectric layer 11 made of crystal particles grown by hydrothermal synthesis is formed on a substrate and the surface thereof is flattened with small particles. It has a structure in which the body layer 12 is formed.
【００２９】図４に本実施例の第一強誘電体層１１の表
面粗さと、第二強誘電体層１２の表面粗さを示した。図
４の縦軸は表面の粗さを示し、横軸は試料の測定長さを
示す。本発明の方法で表面層を形成することにより、表
面粗さが著しく改善されていることがわかる。FIG. 4 shows the surface roughness of the first ferroelectric layer 11 and the surface roughness of the second ferroelectric layer 12 of this embodiment. The vertical axis of FIG. 4 represents the surface roughness, and the horizontal axis represents the measured length of the sample. It can be seen that the surface roughness is remarkably improved by forming the surface layer by the method of the present invention.
【００３０】強誘電体薄膜上にアルミニウム電極を形成
し、物性を測定したところ比誘電率１０００、圧電定数
約１００ｐＣ／Ｎと優れた特性を示した。また、ヤング
率は６．０×１０１０Ｎ／ｍ２であった。また、表面電
極の断線不良は発生せず、基板との剥離もなかった。Ｐ
ＺＴ薄膜を王水に溶かし、ＩＰＣで化学分析したとこ
ろ、モル比は（Ｐｂ：Ｚｒ：Ｔｉ）＝（１：０．５０：
０．５０）であり、原料仕込み組成と同一であった。An aluminum electrode was formed on the ferroelectric thin film, and its physical properties were measured. As a result, excellent properties such as a relative dielectric constant of 1000 and a piezoelectric constant of about 100 pC / N were shown. The Young's modulus was 6.0 × 10 10 N / m 2 . In addition, the disconnection of the surface electrode did not occur and the substrate was not peeled off. P
When the ZT thin film was dissolved in aqua regia and chemically analyzed by IPC, the molar ratio was (Pb: Zr: Ti) = (1: 0.50:
0.50), which was the same as the composition charged in the raw materials.
【００３１】実施例２
Ｐｂ（ＮＯ３）２水溶液３０ｍｍｏｌ／ｌ、Ｌａ（ＣＨ
３ＣＯＯ）３水溶液１ｍｍｏｌ／ｌ、ＺｒＯＣｌ２水溶
液１６ｍｍｏｌ／ｌ、ＴｉＣｌ４水溶液９ｍｍｏｌ／ｌ
およびＫＯＨ水溶液１０００ｍｍｏｌ／ｌの混合溶液
（溶液合計量６４０ｍｌ）を用意した。次にシリコン基
板上にチタン電極を形成し、用意した混合溶液中に浸
し、オートクレーブを用いて１６０℃で３時間水熱処理
することで５μｍ厚の第一強誘電体層のランタン添加Ｐ
ＺＴ（以下ＰＬＺＴと記載する）薄膜を形成した。その
後、純水中で超音波洗浄し、１００℃で１２時間乾燥さ
せた。このようにして得られた第一強誘電体層のＰＬＺ
Ｔ薄膜は平均粒子径２μｍのキュービック状ＰＬＺＴ結
晶粒子で構成されており、表面粗さＲｍａｘは２μｍで
あった。Example 2 Pb (NO 3 ) 2 aqueous solution 30 mmol / l, La (CH
3 COO) 3 aqueous solution 1 mmol / l, ZrOCl 2 aqueous solution 16 mmol / l, TiCl 4 aqueous solution 9 mmol / l
And a mixed solution of KOH aqueous solution 1000 mmol / l (total solution amount 640 ml) was prepared. Next, a titanium electrode was formed on a silicon substrate, dipped in the prepared mixed solution, and hydrothermally treated at 160 ° C. for 3 hours in an autoclave to obtain a lanthanum-doped P of 5 μm thick first ferroelectric layer.
A ZT (hereinafter referred to as PLZT) thin film was formed. Then, it was ultrasonically cleaned in pure water and dried at 100 ° C. for 12 hours. PLZ of the first ferroelectric layer thus obtained
The T thin film was composed of cubic PLZT crystal particles having an average particle diameter of 2 μm and had a surface roughness R max of 2 μm.
【００３２】次に、Ｐｂ（ＮＯ３）２水溶液７７ｍｍｏ
ｌ／ｌ、ＺｒＯＣｌ２水溶液３０．８ｍｍｏｌ／ｌ、Ｌ
ａ（ＣＨ３ＣＯＯ）３水溶液２．４ｍｍｏｌ／ｌ、Ｔｉ
Ｃｌ４水溶液３０．８ｍｍｏｌ／ｌおよびＫＯＨ水溶液
１３８８．８ｍｍｏｌ／ｌを室温で２４時間撹拌混合し
た混合溶液（溶液合計量７００ｍｌ）を用意した。この
時、溶液中には、平均粒子径５０ｎｍの微粒子が生成し
ていた。次に前記シリコン上に第一強誘電体層のＰＬＺ
Ｔ薄膜を形成した基板を、用意した混合溶液中に浸し、
オートクレーブを用いて１３０℃で２時間水熱処理する
ことで２μｍ厚の第二強誘電体層のＰＬＺＴ薄膜を形成
した。その後、純水中で超音波洗浄し、１００℃で１２
時間乾燥させた。このようにして得られた第二強誘電体
層のＰＬＺＴ薄膜は平均粒子径０．２μｍのＰＬＺＴ結
晶粒子で構成されており、表面粗さＲｍａｘは０．５μ
ｍであった。またこのようにして得られた第二強誘電体
層のＰＬＺＴ薄膜は、第一強誘電体層の凹部には厚く、
凸部には薄く形成されていた。Next, a Pb (NO 3 ) 2 aqueous solution of 77 mmo
l / l, ZrOCl 2 aqueous solution 30.8 mmol / l, L
a (CH 3 COO) 3 aqueous 2.4 mmol / l, Ti
A mixed solution (total solution amount 700 ml) was prepared by stirring and mixing a Cl 4 aqueous solution of 30.8 mmol / l and a KOH aqueous solution of 1388.8 mmol / l at room temperature for 24 hours. At this time, fine particles having an average particle diameter of 50 nm were formed in the solution. Next, PLZ the first ferroelectric layer on the silicon.
The substrate on which the T thin film is formed is immersed in the prepared mixed solution,
A PLZT thin film of a 2 μm-thick second ferroelectric layer was formed by hydrothermal treatment at 130 ° C. for 2 hours using an autoclave. Then, ultrasonically clean in pure water,
Allowed to dry for hours. The PLZT thin film of the second ferroelectric layer thus obtained is composed of PLZT crystal particles having an average particle diameter of 0.2 μm and has a surface roughness R max of 0.5 μ.
It was m. The PLZT thin film of the second ferroelectric layer thus obtained is thick in the recess of the first ferroelectric layer,
The protrusion was thinly formed.
【００３３】強誘電体薄膜上にアルミニウム電極を形成
し、物性を測定したところ比誘電率９００、圧電定数約
９０ｐＣ／Ｎと優れた特性を示した。また、ヤング率は
５．８×１０１０Ｎ／ｍ２であった。また、表面電極の
断線不良は発生せず、基板との剥離もなかった。An aluminum electrode was formed on the ferroelectric thin film, and its physical properties were measured. As a result, excellent properties such as a relative dielectric constant of 900 and a piezoelectric constant of about 90 pC / N were shown. The Young's modulus was 5.8 × 10 10 N / m 2 . In addition, the disconnection of the surface electrode did not occur and the substrate was not peeled off.
【００３４】実施例３
まずＰｂ（ＮＯ３）２水溶液３２ｍｍｏｌ／ｌ、ＺｒＯ
Ｃｌ２水溶液２０ｍｍｏｌ／ｌ、ＴｉＣｌ４水溶液２０
ｍｍｏｌ／ｌおよびＫＯＨ水溶液８００ｍｍｏｌ／ｌの
混合溶液（溶液合計量７００ｍｌ）を用意した。次にシ
リコン基板上にチタン電極を形成し、用意した混合溶液
中に浸し、オートクレーブを用いて１８０℃で２時間水
熱処理することで２μｍ厚の第一強誘電体層のＰＺＴ薄
膜を形成した。その後、純水中で超音波洗浄し、１００
℃で１２時間乾燥させた。このようにして得られた第一
強誘電体層のＰＺＴ薄膜は平均粒子径０．５μｍのキュ
ービック状ＰＺＴ結晶粒子で構成されていた。このよう
にして得られた第一強誘電体層のＰＺＴ薄膜の表面ＳＥ
Ｍ写真を図５に示した。Example 3 First, 32 mmol / l of Pb (NO 3 ) 2 aqueous solution and ZrO 2
Cl 2 aqueous solution 20 mmol / l, TiCl 4 aqueous solution 20
A mixed solution of mmol / l and KOH aqueous solution 800 mmol / l (total solution amount 700 ml) was prepared. Next, a titanium electrode was formed on a silicon substrate, immersed in a prepared mixed solution, and hydrothermally treated at 180 ° C. for 2 hours using an autoclave to form a PZT thin film of a first ferroelectric layer having a thickness of 2 μm. After that, ultrasonically wash in pure water to 100
It was dried at ° C for 12 hours. The PZT thin film of the first ferroelectric layer thus obtained was composed of cubic PZT crystal particles having an average particle diameter of 0.5 μm. The surface SE of the PZT thin film of the first ferroelectric layer thus obtained
The M photograph is shown in FIG.
【００３５】次に、Ｐｂ（ＮＯ３）２水溶液１１．８２
ｍｍｏｌ／ｌ，ＺｒＯＣｌ２水溶液５．６３ｍｍｏｌ／
ｌ、ＴｉＣｌ４水溶液５．６３ｍｍｏｌ／ｌおよびＫＯ
Ｈ水溶液５８．２５ｍｍｏｌ／ｌの混合溶液（溶液合計
量７００ｍｌ）を用意した。前記シリコン上に第一強誘
電体層のＰＺＴ薄膜を形成した基板を、用意した混合溶
液中に浸し、オートクレーブを用いて１３０℃で１２時
間水熱処理することで１０μｍ厚の第二強誘電体層のＰ
ＺＴ薄膜を形成した。その後、純水中で超音波洗浄し、
１００℃で１２時間乾燥させた。このようにして得られ
た第二強誘電体層のＰＺＴ薄膜は平均粒子径５μｍのＰ
ＺＴ結晶粒子で構成されており、表面粗さＲｍａｘは
４．０μｍであった。このようにして得られた第二強誘
電体層のＰＺＴ薄膜の表面ＳＥＭ写真を図６に示した。Next, a Pb (NO 3 ) 2 aqueous solution 11.82 is used.
mmol / l, ZrOCl 2 aqueous solution 5.63 mmol /
l, TiCl 4 aqueous solution 5.63 mmol / l and KO
A mixed solution of 58.25 mmol / l H aqueous solution (total solution amount 700 ml) was prepared. The substrate on which the PZT thin film of the first ferroelectric layer was formed on silicon was dipped in the prepared mixed solution, and hydrothermally treated at 130 ° C. for 12 hours using an autoclave to obtain a second ferroelectric layer having a thickness of 10 μm. Of P
A ZT thin film was formed. Then, ultrasonically clean in pure water,
It was dried at 100 ° C. for 12 hours. The PZT thin film of the second ferroelectric layer thus obtained has a P average particle size of 5 μm.
It was composed of ZT crystal particles and had a surface roughness R max of 4.0 μm. A surface SEM photograph of the PZT thin film of the second ferroelectric layer thus obtained is shown in FIG.
【００３６】次に、Ｐｂ（ＮＯ３）２水溶液７７ｍｍｏ
ｌ／ｌ、ＺｒＯＣｌ２水溶液３０．８ｍｍｏｌ／ｌ、Ｔ
ｉＣｌ４水溶液３０．８ｍｍｏｌ／ｌおよびＫＯＨ水溶
液１３８８．８ｍｍｏｌ／ｌを室温で７２時間撹拌混合
した混合溶液（溶液合計量７００ｍｌ）を用意した。こ
の時、溶液中には、平均粒子径２００ｎｍの微粒子が生
成していた。前記シリコン上に第一強誘電体層のＰＺＴ
薄膜と第二強誘電体層のＰＺＴ薄膜を形成した基板を、
用意した混合溶液中に浸し、オートクレーブを用いて１
３０℃で１２時間水熱処理することで２μｍ厚の第三強
誘電体層のＰＺＴ薄膜を形成した。その後、純水中で超
音波洗浄し、１００℃で１２時間乾燥させた。このよう
にして得られた第三強誘電体層のＰＺＴ薄膜は平均粒子
径１．０μｍのＰＺＴ結晶粒子で構成されており、表面
粗さＲｍａｘは０．５μｍであった。またこのようにし
て得られた第三強誘電体層のＰＺＴ薄膜は、第二強誘電
体層の凹部には厚く、凸部には薄く形成されていた。こ
のようにして得られた第三強誘電体層のＰＺＴ薄膜の表
面ＳＥＭ写真を図７に示した。Next, a Pb (NO 3 ) 2 aqueous solution 77 mmo
l / l, ZrOCl 2 aqueous solution 30.8 mmol / l, T
A mixed solution (total amount of solution: 700 ml) was prepared by stirring and mixing an iCl 4 aqueous solution of 30.8 mmol / l and a KOH aqueous solution of 1388.8 mmol / l at room temperature for 72 hours. At this time, fine particles having an average particle diameter of 200 nm were formed in the solution. A first ferroelectric layer of PZT on the silicon
The substrate on which the thin film and the PZT thin film of the second ferroelectric layer are formed,
Immerse in the prepared mixed solution and use an autoclave 1
By hydrothermal treatment at 30 ° C. for 12 hours, a PZT thin film of the second ferroelectric layer having a thickness of 2 μm was formed. Then, it was ultrasonically cleaned in pure water and dried at 100 ° C. for 12 hours. The PZT thin film of the third ferroelectric layer thus obtained was composed of PZT crystal particles having an average particle diameter of 1.0 μm and had a surface roughness R max of 0.5 μm. Further, the PZT thin film of the third ferroelectric layer thus obtained was formed thick in the concave portions of the second ferroelectric layer and thin in the convex portions. The surface SEM photograph of the PZT thin film of the third ferroelectric layer thus obtained is shown in FIG.
【００３７】図８にこの強誘電体薄膜の内部構造を模式
的に示す。基板と、その上に形成された基板との密着度
を上げるための平均粒子径０．５μｍの細かい粒子から
なる第一強誘電体層２１と、その上に水熱合成により成
長させた平均粒子径５μｍの結晶粒子からなる第二強誘
電体層２２と、その表面を小さい粒子で平坦にした表面
粗さＲｍａｘが０．５μｍの第三強誘電体層２３を形成
した構造となっている。FIG. 8 schematically shows the internal structure of this ferroelectric thin film. A first ferroelectric layer 21 made of fine particles having an average particle diameter of 0.5 μm for increasing the degree of adhesion between the substrate and the substrate formed thereon, and the average particles grown thereon by hydrothermal synthesis. It has a structure in which a second ferroelectric layer 22 made of crystal particles having a diameter of 5 μm and a third ferroelectric layer 23 having a surface roughness R max of 0.5 μm, the surface of which is flattened with small particles, are formed. .
【００３８】図９に本実施例の第二強誘電体層２２の表
面粗さと、第三強誘電体層２３の表面粗さを示した。本
発明の方法で表面層を形成することにより、表面粗さが
著しく改善されていることがわかる。FIG. 9 shows the surface roughness of the second ferroelectric layer 22 and the surface roughness of the third ferroelectric layer 23 of this embodiment. It can be seen that the surface roughness is remarkably improved by forming the surface layer by the method of the present invention.
【００３９】強誘電体薄膜上にアルミニウム電極を形成
し、物性を測定したところ比誘電率１０００、圧電定数
約９０ｐＣ／Ｎと優れた特性を示した。また、ヤング率
は６．０×１０１０Ｎ／ｍ２であった。また、表面電極
の断線不良は発生せず、基板との剥離もなかった。ＰＺ
Ｔ薄膜を王水に溶かし、ＩＰＣで化学分析したところ、
モル比は（Ｐｂ：Ｚｒ：Ｔｉ）＝（１：０．５０：０．
５０）であり、原料仕込み組成と同一であった。An aluminum electrode was formed on the ferroelectric thin film, and its physical properties were measured. As a result, excellent properties such as a relative dielectric constant of 1000 and a piezoelectric constant of about 90 pC / N were shown. The Young's modulus was 6.0 × 10 10 N / m 2 . In addition, the disconnection of the surface electrode did not occur and the substrate was not peeled off. PZ
When the T thin film was dissolved in aqua regia and chemically analyzed by IPC,
The molar ratio is (Pb: Zr: Ti) = (1: 0.50: 0.
50), which was the same as the raw material charging composition.
【００４０】実施例４
まずＰｂ（ＮＯ３）２水溶液３０ｍｍｏｌ／ｌ、Ｌａ
（ＣＨ３ＣＯＯ）３水溶液１ｍｍｏｌ／ｌ、ＺｒＯＣｌ
２水溶液１６ｍｍｏｌ／ｌ、ＴｉＣｌ４水溶液９ｍｍｏ
ｌ／ｌおよびＫＯＨ水溶液１０００ｍｍｏｌ／ｌの混合
溶液（溶液合計量７００ｍｌ）を用意した。次にシリコ
ン基板上にチタン電極を形成し、用意した混合溶液中に
浸し、オートクレーブを用いて１６０℃で３時間水熱処
理することで２μｍ厚みの第一強誘電体層のランタン添
加ＰＺＴ（以下ＰＬＺＴと記載する）薄膜を形成した。
その後、純水中で超音波洗浄し、１００℃で１２時間乾
燥させた。このようにして得られた第一強誘電体層のＰ
ＬＺＴ薄膜は平均粒子径０．５μｍのキュービック状Ｐ
ＬＺＴ結晶粒子で構成されていた。Example 4 First, Pb (NO 3 ) 2 aqueous solution 30 mmol / l, La
(CH 3 COO) 3 aqueous solution 1 mmol / l, ZrOCl
2 aqueous solution 16 mmol / l, TiCl 4 aqueous solution 9 mmo
A mixed solution of 1 / l and 1000 mmol / l of KOH aqueous solution (total solution volume 700 ml) was prepared. Next, a titanium electrode is formed on a silicon substrate, immersed in the prepared mixed solution, and hydrothermally treated at 160 ° C. for 3 hours in an autoclave to form a lanthanum-added PZT (hereinafter PLZT) having a thickness of 2 μm in the first ferroelectric layer. A thin film was formed.
Then, it was ultrasonically cleaned in pure water and dried at 100 ° C. for 12 hours. The P of the first ferroelectric layer obtained in this way
The LZT thin film is a cubic P with an average particle size of 0.5 μm.
It was composed of LZT crystal grains.
【００４１】次にＰｂ（ＮＯ３）２水溶液１５．５２ｍ
ｍｏｌ／ｌ、Ｌａ（ＣＨ３ＣＯＯ）３水溶液０．４８ｍ
ｍｏｌ／ｌ、ＺｒＯＣｌ２水溶液８．３２ｍｍｏｌ／
ｌ、ＴｉＣｌ４水溶液７．６８ｍｍｏｌ／ｌおよびＫＯ
Ｈ水溶液２３００ｍｍｏｌ／ｌの混合溶液（溶液合計量
７００ｍｌ）を用意した。前記シリコン上に第一強誘電
体層のＰＬＺＴ薄膜を形成した基板を、用意した混合溶
液中に浸し、オートクレーブを用いて１４０℃で６時間
水熱処理することで１０μｍ厚の第二強誘電体層のＰＬ
ＺＴ薄膜を形成した。その後、純水中で超音波洗浄し、
１００℃で１２時間乾燥させた。このようにして得られ
た第二強誘電体層のＰＬＺＴ薄膜は平均粒子径１０μｍ
のＰＬＺＴ結晶粒子で構成されており、表面粗さＲ
ｍａｘは６μｍであった。Next, 15.52 m of Pb (NO 3 ) 2 aqueous solution
mol / l, La (CH 3 COO) 3 aqueous solution 0.48 m
mol / l, ZrOCl 2 aqueous solution 8.32 mmol /
l, TiCl 4 aqueous solution 7.68 mmol / l and KO
A mixed solution of H aqueous solution of 2300 mmol / l (total solution amount 700 ml) was prepared. The substrate on which the PLZT thin film of the first ferroelectric layer was formed on the silicon was dipped in the prepared mixed solution and hydrothermally treated at 140 ° C. for 6 hours using an autoclave to obtain a second ferroelectric layer having a thickness of 10 μm. PL
A ZT thin film was formed. Then, ultrasonically clean in pure water,
It was dried at 100 ° C. for 12 hours. The PLZT thin film of the second ferroelectric layer thus obtained has an average particle size of 10 μm.
Of PLZT crystal particles with a surface roughness R
max was 6 μm.
【００４２】次に、Ｐｂ（ＮＯ３）２水溶液７７ｍｍｏ
ｌ／ｌ、ＺｒＯＣｌ２水溶液３０．８ｍｍｏｌ／ｌ，Ｌ
ａ（ＣＨ３ＣＯＯ）３水溶液２．４ｍｍｏｌ／ｌ、Ｔｉ
Ｃｌ４水溶液３０．８ｍｍｏｌ／ｌおよびＫＯＨ水溶液
１３８８．８ｍｍｏｌ／ｌを室温で４８時間撹拌混合し
た混合溶液（溶液合計量７００ｍｌ）を用意した。この
時、溶液中には、平均粒子径１００ｎｍの微粒子が生成
していた。前記シリコン上に第一強誘電体層と第二強誘
電体層のＰＬＺＴ薄膜を形成した基板を、用意した混合
溶液中に浸し、オートクレーブを用いて１６０℃で２時
間水熱処理することで５μｍ厚の第三強誘電体層のＰＬ
ＺＴ薄膜を形成した。その後、純水中で超音波洗浄し、
１００℃で１２時間乾燥させた。このようにして得られ
た第三強誘電体層のＰＬＺＴ薄膜は平均粒子径０．５μ
ｍのＰＬＺＴ結晶粒子で構成されており、表面粗さＲ
ｍａｘは１．０μｍであった。またこのようにして得ら
れた第三強誘電体層のＰＬＺＴ薄膜は、第二強誘電体層
の凹部には厚く、凸部には薄く形成されていた。Next, a Pb (NO 3 ) 2 aqueous solution 77 mmo
l / l, ZrOCl 2 aqueous solution 30.8 mmol / l, L
a (CH 3 COO) 3 aqueous 2.4 mmol / l, Ti
A mixed solution (total amount of solution: 700 ml) was prepared by mixing 30.8 mmol / l of Cl 4 aqueous solution and 1388.8 mmol / l of KOH aqueous solution with stirring at room temperature for 48 hours. At this time, fine particles having an average particle diameter of 100 nm were formed in the solution. A substrate having a PLZT thin film of a first ferroelectric layer and a second ferroelectric layer formed on silicon is dipped in a prepared mixed solution and hydrothermally treated at 160 ° C. for 2 hours using an autoclave to have a thickness of 5 μm. PL of the third ferroelectric layer of
A ZT thin film was formed. Then, ultrasonically clean in pure water,
It was dried at 100 ° C. for 12 hours. The PLZT thin film of the third ferroelectric layer thus obtained has an average particle size of 0.5 μm.
m PLZT crystal particles and has a surface roughness R
max was 1.0 μm. Further, the PLZT thin film of the third ferroelectric layer thus obtained was formed thick in the concave portions of the second ferroelectric layer and thin in the convex portions.
【００４３】強誘電体薄膜上にアルミニウム電極を形成
し、物性を測定したところ比誘電率９００、圧電定数約
９０ｐＣ／Ｎと優れた特性を示した。また、ヤング率は
５．８×１０１０Ｎ／ｍ２であった。また、表面電極の
断線不良は発生せず、基板との剥離もなかった。An aluminum electrode was formed on the ferroelectric thin film, and its physical properties were measured. As a result, excellent properties such as a relative dielectric constant of 900 and a piezoelectric constant of about 90 pC / N were shown. The Young's modulus was 5.8 × 10 10 N / m 2 . In addition, the disconnection of the surface electrode did not occur and the substrate was not peeled off.
【００４４】実施例５
まずＰｂ（ＮＯ３）２水溶液２４ｍｍｏｌ／ｌ、Ｓｒ
（ＮＯ３）２水溶液６ｍｍｏｌ／ｌ、ＺｒＯＣｌ２水溶
液１２．５ｍｍｏｌ／ｌ，ＴｉＣｌ４水溶液１２．５ｍ
ｍｏｌ／ｌおよびＫＯＨ水溶液１０００ｍｍｏｌ／ｌの
混合溶液（溶液合計量７００ｍｌ）を用意した。次にシ
リコン基板上にチタン電極を形成し、用意した混合溶液
中に浸し、オートクレーブを用いて１４０℃で１時間水
熱処理することで０．５μｍ厚みの第一強誘電体層のス
トロンチウム添加ＰＺＴ（以下ＰＳＺＴと記載する）薄
膜を形成した。その後、純水中で超音波洗浄し、１００
℃で１２時間乾燥させた。Example 5 First, Pb (NO 3 ) 2 aqueous solution 24 mmol / l, Sr
(NO 3 ) 2 aqueous solution 6 mmol / l, ZrOCl 2 aqueous solution 12.5 mmol / l, TiCl 4 aqueous solution 12.5 m
A mixed solution of mol / l and KOH aqueous solution of 1000 mmol / l (total solution amount 700 ml) was prepared. Next, a titanium electrode is formed on a silicon substrate, immersed in a prepared mixed solution, and hydrothermally treated at 140 ° C. for 1 hour in an autoclave to form a strontium-containing PZT (0.5 μm thick strontium-containing first ferroelectric layer). A thin film (hereinafter referred to as PSZT) was formed. After that, ultrasonically wash in pure water to 100
It was dried at ° C for 12 hours.
【００４５】次にＰｂ（ＮＯ３）２水溶液１５．５２ｍ
ｍｏｌ／ｌ、Ｌａ（ＣＨ３ＣＯＯ）３水溶液０．４８ｍ
ｍｏｌ／ｌ、ＺｒＯＣｌ２水溶液８．３２ｍｍｏｌ／
ｌ、ＴｉＣｌ４水溶液７．６８ｍｍｏｌ／ｌおよびＫＯ
Ｈ水溶液２３００ｍｍｏｌ／ｌの混合溶液（溶液合計量
７００ｍｌ）を用意した。前記シリコン上に第一強誘電
体層のＰＬＺＴ薄膜を形成した基板を、用意した混合溶
液中に浸し、オートクレーブを用いて１４０℃で６時間
水熱処理することで１０μｍ厚の第二強誘電体層のＰＬ
ＺＴ薄膜を形成した。その後、純水中で超音波洗浄し、
１００℃で１２時間乾燥させた。このようにして得られ
た第二強誘電体層のＰＬＺＴ薄膜は平均粒子径１０μｍ
のＰＬＺＴ結晶粒子で構成されており、表面粗さＲ
ｍａｘは５．０μｍであった。またこのようにして得ら
れた第二強誘電体層のＰＬＺＴ薄膜は、第一強誘電体層
の凹部には厚く、凸部には薄く形成されていた。Next, 15.52 m of Pb (NO 3 ) 2 aqueous solution
mol / l, La (CH 3 COO) 3 aqueous solution 0.48 m
mol / l, ZrOCl 2 aqueous solution 8.32 mmol /
l, TiCl 4 aqueous solution 7.68 mmol / l and KO
A mixed solution of H aqueous solution of 2300 mmol / l (total solution amount 700 ml) was prepared. The substrate on which the PLZT thin film of the first ferroelectric layer was formed on the silicon was dipped in the prepared mixed solution and hydrothermally treated at 140 ° C. for 6 hours using an autoclave to obtain a second ferroelectric layer having a thickness of 10 μm. PL
A ZT thin film was formed. Then, ultrasonically clean in pure water,
It was dried at 100 ° C. for 12 hours. The PLZT thin film of the second ferroelectric layer thus obtained has an average particle size of 10 μm.
Of PLZT crystal particles with a surface roughness R
max was 5.0 μm. Further, the PLZT thin film of the second ferroelectric layer thus obtained was formed thick in the concave portion of the first ferroelectric layer and thin in the convex portion.
【００４６】次に、Ｐｂ（ＮＯ３）２水溶液７７ｍｍｏ
ｌ／ｌ，ＺｒＯＣｌ２水溶液３０．８ｍｍｏｌ／ｌ、Ｌ
ａ（ＣＨ３ＣＯＯ）３水溶液２．４ｍｍｏｌ／ｌ、Ｔｉ
Ｃｌ４水溶液３０．８ｍｍｏｌ／ｌおよびＫＯＨ水溶液
１３８８．８ｍｍｏｌ／ｌを室温で４８時間撹拌混合し
た混合溶液（溶液合計量７００ｍｌ）を用意した。この
時、溶液中には、平均粒子径１００ｎｍの微粒子が生成
していた。前記シリコン上に第一強誘電体層と第二強誘
電体層のＰＬＺＴ薄膜を形成した基板を、用意した混合
溶液中に浸し、オートクレーブを用いて１６０℃で２時
間水熱処理することで１０μｍ厚の第三強誘電体層のＰ
ＬＺＴ薄膜を形成した。その後、純水中で超音波洗浄
し、１００℃で１２時間乾燥させた。このようにして得
られた第三強誘電体層のＰＬＺＴ薄膜は平均粒子径０．
５μｍのＰＬＺＴ結晶粒子で構成されており、表面粗さ
Ｒｍａｘは１．０μｍであった。またこのようにして得
られた第三強誘電体層のＰＬＺＴ薄膜は、第二強誘電体
層の凹部には厚く、凸部には薄く形成されていた。Next, a Pb (NO 3 ) 2 aqueous solution 77 mmo
l / l, ZrOCl 2 aqueous solution 30.8 mmol / l, L
a (CH 3 COO) 3 aqueous 2.4 mmol / l, Ti
A mixed solution (total amount of solution: 700 ml) was prepared by mixing 30.8 mmol / l of Cl 4 aqueous solution and 1388.8 mmol / l of KOH aqueous solution with stirring at room temperature for 48 hours. At this time, fine particles having an average particle diameter of 100 nm were formed in the solution. A substrate having PLZT thin films of a first ferroelectric layer and a second ferroelectric layer formed on silicon is dipped in a prepared mixed solution and hydrothermally treated at 160 ° C. for 2 hours using an autoclave to obtain a thickness of 10 μm. Of the third ferroelectric layer of
An LZT thin film was formed. Then, it was ultrasonically cleaned in pure water and dried at 100 ° C. for 12 hours. The PLZT thin film of the third ferroelectric layer thus obtained had an average particle size of 0.
It was composed of 5 μm PLZT crystal particles and had a surface roughness R max of 1.0 μm. Further, the PLZT thin film of the third ferroelectric layer thus obtained was formed thick in the concave portions of the second ferroelectric layer and thin in the convex portions.
【００４７】強誘電体薄膜上にアルミニウム電極を形成
し、物性を測定したところ比誘電率９００、圧電定数約
９０ｐＣ／Ｎと優れた特性を示した。また、ヤング率は
５．９×１０１０Ｎ／ｍ２であった。また、表面電極の
断線不良は発生せず、基板との剥離もなかった。An aluminum electrode was formed on the ferroelectric thin film, and its physical properties were measured. As a result, excellent properties such as a relative dielectric constant of 900 and a piezoelectric constant of about 90 pC / N were shown. The Young's modulus was 5.9 × 10 10 N / m 2 . In addition, the disconnection of the surface electrode did not occur and the substrate was not peeled off.
【００４８】以上実施例を挙げて述べてきたが、本発明
は構成する強誘電体層の数や酸化物の組成比や原料の種
類になんら限定されるものではない。Although the embodiments have been described above, the present invention is not limited to the number of ferroelectric layers, the composition ratio of oxides, and the kinds of raw materials.
【００４９】[0049]
【発明の効果】以上述べたように結晶粒子の成長に伴っ
て増大する表面粗さは、本発明の方法で膜を形成するこ
とにより平坦化され、電極の断線不良が発生せず、５０
０℃以上での熱処理が不要で、素子信頼性が高い上、高
い圧電定数と高いヤング率をもつ強誘電体薄膜素子を提
供できる。また、容易なプロセスで作製することができ
るため、低コストで微細化が求められる高性能の圧電
体、強誘電体薄膜素子として広く応用することができ
る。As described above, the surface roughness, which increases with the growth of crystal grains, is flattened by forming the film by the method of the present invention, and the disconnection failure of the electrode does not occur.
It is possible to provide a ferroelectric thin film element having a high piezoelectric constant and a high Young's modulus, which does not require heat treatment at 0 ° C. or higher and has high element reliability. Further, since it can be manufactured by an easy process, it can be widely applied as a high-performance piezoelectric or ferroelectric thin film element that requires low cost and miniaturization.
【図１】実施例１の第一強誘電体層のＰＺＴ薄膜の表面
状態を示す図面に代わる写真図である。FIG. 1 is a photograph replacing a drawing showing a surface state of a PZT thin film of a first ferroelectric layer of Example 1.
【図２】実施例１の第二強誘電体層のＰＺＴ薄膜の表面
状態を示す図面に代わる写真図である。FIG. 2 is a photograph replacing a drawing showing a surface state of a PZT thin film of a second ferroelectric layer of Example 1.
【図３】実施例１の強誘電体薄膜の内部構造の概念を模
式的に表す断面図である。FIG. 3 is a cross-sectional view schematically showing the concept of the internal structure of the ferroelectric thin film of Example 1.
【図４】実施例１の第一強誘電体層および第二強誘電体
層の表面粗さを示す図である。。FIG. 4 is a diagram showing surface roughness of a first ferroelectric layer and a second ferroelectric layer of Example 1. .
【図５】実施例３の第一強誘電体層のＰＺＴ薄膜の表面
状態を示す図面に代わる写真図である。5 is a photograph replacing a drawing showing a surface state of a PZT thin film of a first ferroelectric layer of Example 3. FIG.
【図６】実施例３の第二強誘電体層のＰＺＴ薄膜の表面
状態を示す図面に代わる写真図である。6 is a photograph replacing a drawing showing a surface state of a PZT thin film of a second ferroelectric layer of Example 3. FIG.
【図７】実施例３の第三強誘電体層のＰＺＴ薄膜の表面
状態を示す図面に代わる写真図である。FIG. 7 is a photograph replacing a drawing showing a surface state of a PZT thin film of a third ferroelectric layer of Example 3.
【図８】実施例３の強誘電体薄膜の内部構造の概念を模
式的に表す断面図である。FIG. 8 is a sectional view schematically showing the concept of the internal structure of the ferroelectric thin film of Example 3.
【図９】実施例３の第二強誘電体層および第三強誘電体
層の表面粗さを示す図である。FIG. 9 is a diagram showing surface roughness of a second ferroelectric layer and a third ferroelectric layer of Example 3.
１１：水熱合成により成長させた結晶粒子からなる第一
強誘電体層
１２：表面粗さＲｍａｘが０．５μｍ以下の第二強誘電
体層
２１：基板との密着度をあげるための平均粒子径０．５
μｍの細かい粒子からなる第一強誘電体層
２２：水熱合成により成長させた平均粒子径５μｍの結
晶粒子からなる第二強誘電体層
２３：表面粗さＲｍａｘが０．５μｍの第三強誘電体層11: First ferroelectric layer 12 made of crystal particles grown by hydrothermal synthesis 12: Second ferroelectric layer 21 having a surface roughness R max of 0.5 μm or less 21: Average for increasing the degree of adhesion with a substrate Particle size 0.5
First ferroelectric layer 22 made of fine particles of μm: Second ferroelectric layer 23 made of crystal particles grown by hydrothermal synthesis and having an average particle diameter of 5 μm: Third ferroelectric layer having a surface roughness R max of 0.5 μm Ferroelectric layer
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｇ０１Ｐ 15/09 Ｇ０１Ｐ 15/09 Ｈ０１Ｌ 29/84 Ｈ０１Ｌ 29/84 Ｚ 41/187 41/18 １０１Ｄ 41/24 41/22 Ａ (56)参考文献 特開 平８−133736（ＪＰ，Ａ) 特開 平８−133737（ＪＰ，Ａ) 特開 平８−133738（ＪＰ，Ａ) 特開 平９−141201（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 2/312 H01L 21/314 H01L 21/316 H01L 21/318 C01G 25/00 G01H 11/08 G01J 1/02 G01L 1/16 G01P 15/09 H01L 29/84 H01L 41/187 H01L 41/24 ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI G01P 15/09 G01P 15/09 H01L 29/84 H01L 29/84 Z 41/187 41/18 101D 41/24 41/22 A ( 56) References JP-A-8-133736 (JP, A) JP-A-8-133737 (JP, A) JP-A-8-133738 (JP, A) JP-A-9-141201 (JP, A) (58) ) Fields surveyed (Int.Cl. 7 , DB name) H01L 2/312 H01L 21/314 H01L 21/316 H01L 21/318 C01G 25/00 G01H 11/08 G01J 1/02 G01L 1/16 G01P 15/09 H01L 29/84 H01L 41/187 H01L 41/24
Claims (3)
囲内で反応させ、平均粒子径２０〜１０００ｎｍの微粒
子を溶液内に生成させた後、水熱合成することにより強
誘電体膜上に表面粗さＲｍａｘが２μｍ以下の強誘電体
薄膜を形成することを特徴とする強誘電体薄膜の製造方
法。1. A ferroelectric film by reacting a raw material solution for hydrothermal synthesis within a range of 0 to 100 ° C. to generate fine particles having an average particle diameter of 20 to 1000 nm in the solution, and then performing hydrothermal synthesis. A method of manufacturing a ferroelectric thin film, comprising forming a ferroelectric thin film having a surface roughness R max of 2 μm or less on the top.
ｌ／ｌ、Ｚｒ含有原料化合物が０〜５００ｍｍｏｌ／
ｌ、Ｔｉ含有原料化合物が０．００２〜５００ｍｍｏｌ
／ｌおよびＬａ含有原料化合物が０〜５０ｍｍｏｌ／ｌ
の条件でアルカリ水溶液中０〜１００℃の温度範囲内で
反応させ、Ｐｂ、Ｌａ，ＺｒおよびＴｉのうち少なくと
も一つを含有する平均粒子径２０〜１０００ｎｍの微粒
子を生成させた後、水熱合成することにより強誘電体層
の上に表面粗さＲｍａｘが２μｍ以下の強誘電体層を形
成することを特徴とする強誘電体薄膜の製造方法。2. The Pb-containing starting compound is 50 to 500 mmo.
1 / l, the Zr-containing raw material compound is 0 to 500 mmol /
1, the Ti-containing raw material compound is 0.002-500 mmol
/ L and La-containing raw material compound is 0 to 50 mmol / l
Under a condition of 0 to 100 ° C. in an alkaline aqueous solution to produce fine particles having an average particle diameter of 20 to 1000 nm and containing at least one of Pb, La, Zr and Ti, and then performing hydrothermal synthesis. A ferroelectric thin film having a surface roughness R max of 2 μm or less is formed on the ferroelectric layer by the method described above.
造された表面粗さＲｍａｘが２μｍ以下の強誘電体膜
と、その上に形成された電極とからなる強誘電体薄膜素
子。3. A ferroelectric thin film element comprising a substrate, a ferroelectric film having a surface roughness R max of 2 μm or less manufactured by the method according to claim 1 or 2, and an electrode formed thereon. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33073397A JP3478095B2 (en) | 1997-10-27 | 1997-10-27 | Ferroelectric thin film element and method of manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33073397A JP3478095B2 (en) | 1997-10-27 | 1997-10-27 | Ferroelectric thin film element and method of manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11135495A JPH11135495A (en) | 1999-05-21 |
| JP3478095B2 true JP3478095B2 (en) | 2003-12-10 |
Family
ID=18235957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33073397A Expired - Fee Related JP3478095B2 (en) | 1997-10-27 | 1997-10-27 | Ferroelectric thin film element and method of manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3478095B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4186309B2 (en) * | 1999-05-24 | 2008-11-26 | 宇部興産株式会社 | Ceramic capacitor and manufacturing method thereof |
| JP4362581B2 (en) * | 2003-08-20 | 2009-11-11 | 独立行政法人産業技術総合研究所 | Manufacturing method of parallel plate capacitor |
| WO2019004372A1 (en) * | 2017-06-30 | 2019-01-03 | 国立研究開発法人産業技術総合研究所 | Metal oxide nanocrystalline film fixation substrate, metal oxide nanocrystal production method, and production method for metal oxide nanocrystalline film fixation substrate |
| CN111122022B (en) * | 2019-12-30 | 2023-08-15 | 浙江清华柔性电子技术研究院 | Functional film and preparation method thereof, flexible pressure sensor and preparation method thereof |
| CN111122021B (en) * | 2019-12-30 | 2023-08-15 | 浙江清华柔性电子技术研究院 | Flexible composite film and preparation method thereof, flexible pressure sensor and preparation method thereof |
-
1997
- 1997-10-27 JP JP33073397A patent/JP3478095B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11135495A (en) | 1999-05-21 |
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