JPH0530763A - Actuator - Google Patents
ActuatorInfo
- Publication number
- JPH0530763A JPH0530763A JP3205658A JP20565891A JPH0530763A JP H0530763 A JPH0530763 A JP H0530763A JP 3205658 A JP3205658 A JP 3205658A JP 20565891 A JP20565891 A JP 20565891A JP H0530763 A JPH0530763 A JP H0530763A
- Authority
- JP
- Japan
- Prior art keywords
- film
- actuator
- elastic body
- thin film
- amorphous
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、アモルファス強誘電体
膜を用いたアクチュエータの素子構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element structure of an actuator using an amorphous ferroelectric film.
【０００２】[0002]
【従来の技術およびその問題点】従来の超音波振動子を
利用したアクチュエータの基本的な構成および動作は次
のようになっている。このアクチュエータは、例えば、
圧電素子のような電圧の印加により機械的歪みを生ずる
素子と弾性体を組み合わせた超音波振動子を備えている
と共に弾性体の表面に生じる進行波によって可動体を動
かすようになっている。この種のアクチュエータは、電
磁力を用いたアクチュエータに比べると、小型・軽量化
をはかりやすく、可動体の微小変位駆動もでき、また、
不用磁界が発生しないなどの特徴があるが、従来は弾性
体に組み合わされる圧電素子が、セラミックス材で形成
されていて、しかも、この圧電素子は接着剤を使って弾
性体と接合されるようになっていたため、弾性体に圧電
素子を接着するという工程が必要になり、接着の過程で
セラミック材の圧電素子が破損して歩止まりが悪くった
り、均一な接着ができなくて最終的にできあがった超音
波振動子の特性が不安定となったり、振動子同士の特性
のバラツキも大きくなってしまうという問題があった。2. Description of the Related Art The basic structure and operation of a conventional actuator using an ultrasonic vibrator are as follows. This actuator is, for example,
An ultrasonic transducer, which is a combination of an elastic body and an element such as a piezoelectric element that generates mechanical strain when a voltage is applied, is provided and the movable body is moved by a traveling wave generated on the surface of the elastic body. Compared to actuators that use electromagnetic force, this type of actuator is easier to reduce in size and weight, and can also drive minute displacements of movable bodies.
Although there is a feature that an unnecessary magnetic field does not occur, conventionally, a piezoelectric element combined with an elastic body is formed of a ceramic material, and this piezoelectric element is bonded to the elastic body using an adhesive. Therefore, a step of bonding the piezoelectric element to the elastic body was required, and the piezoelectric element of the ceramic material was damaged during the bonding process and the yield was bad, and uniform bonding could not be done and finally it was completed. There are problems that the characteristics of the ultrasonic vibrator become unstable and that the characteristics of the vibrators vary greatly.
【０００３】このため、弾性体の表面上に各種のスパッ
タ法やＣＶＤ法等の薄膜形成法を用いてZnO 、PZT 等の
多結晶あるいは単結晶圧電膜を直接形成することによ
り、接着剤を全く使わずに高い密着力の結合を行い、ア
クチュエータの性能を安定させると共に製造の歩止まり
も向上させる方法がとられた。しかし結晶性圧電体膜を
用いた従来の方法では、多結晶圧電体膜を用いた場合は
粒界の存在により、機械的疲労破壊や粒界による弾性波
の散乱等の問題があり、耐久性や性能の点で課題が残っ
ていた。これに対し粒界のない単結晶圧電体膜を用いる
方策が考えられるが、単結晶膜の製作にはバイアススパ
ッタ法や原子層エピタキシャル法あるいは分子線エピタ
キシャル法を用いる必要があるために製膜に多大の時
間、コストを必要とする。Therefore, by directly forming a polycrystalline or single crystal piezoelectric film of ZnO, PZT or the like on the surface of the elastic body by using various thin film forming methods such as the sputtering method and the CVD method, the adhesive is completely removed. A method was adopted in which high adhesive force bonding was performed without using it to stabilize the performance of the actuator and improve the manufacturing yield. However, in the conventional method using a crystalline piezoelectric film, when a polycrystalline piezoelectric film is used, there are problems such as mechanical fatigue fracture and scattering of elastic waves due to grain boundaries due to the existence of grain boundaries, and durability There was a problem in terms of performance and performance. On the other hand, it is possible to use a single crystal piezoelectric film without grain boundaries, but it is necessary to use the bias sputtering method, atomic layer epitaxial method, or molecular beam epitaxial method for manufacturing the single crystal film. It requires a great deal of time and cost.
【０００４】すなわち、従来圧電性薄膜として用いられ
ているZnO 圧電薄膜については、塩嵜 忠監修：新圧電
材料の製造と応用( シーエムシー:1987 年)33 頁によれ
ばＣ軸配向多結晶圧電薄膜であればガラス基板上に作成
できるが、ZnO 単結晶圧電薄膜を得るためにはマグネト
ロンスパッタ法を用いてAl2O3(0112) 基板上に堆積させ
ることが必要であることが述べられている。このように
単結晶圧電薄膜を得るためには特別な基板を用いる必要
があり、多大なコストを必要とする。このため圧電薄膜
を用いたデバイスの実用化は困難であった。That is, regarding the ZnO piezoelectric thin film which has been conventionally used as the piezoelectric thin film, according to Tadashi Shiozaki: Production and Application of New Piezoelectric Material (CMC: 1987) p. Although thin films can be created on glass substrates, it was stated that it is necessary to deposit them on Al 2 O 3 (0112) substrates using magnetron sputtering in order to obtain ZnO single crystal piezoelectric thin films. There is. As described above, it is necessary to use a special substrate to obtain the single crystal piezoelectric thin film, which requires a great cost. Therefore, it has been difficult to put a device using a piezoelectric thin film into practical use.
【０００５】さらに強誘電体PZT については、特開昭62
-30695号公報に示されているように、スパッタリング法
によりＣ軸配向多結晶PZT 薄膜を得るために製膜中下地
温度を600 ℃に保持し、さらに単結晶膜の成長を促すた
めに(100)MgO単結晶基板上に(100) 配向したPt薄膜を下
地として必要とする。また現在薄膜化の検討が盛んにな
されている強誘電体PbTiO3については、JapaneseJourna
l of Applied Physics Vol.24(1985)Supplement 24-2,p
p.404-406によれば、RFスパッタリング法によりPbTiO3
強誘電性多結晶薄膜を形成するためには製膜後520 ℃以
上の温度で薄膜に熱処理を施すことが必要であり、Jour
nal of Vacuum Science and TechnologyVol.A8(3)(199
0)pp.1382-1390によればPbTiO3単結晶強誘電体膜を得る
ためには、RFマグネトロンスパッタリング法による製膜
において製膜中下地温度を550 〜600 ℃に保持し、さら
に、単結晶膜の成長を促すために(100)MgO単結晶基板上
に(100) 配向したPt薄膜を下地として必要とする。この
ように強誘電体薄膜を得るためには、基板として特別な
ものが必要でありまた高温プロセスも必要であるため、
多大なコストを必要とし強誘電体薄膜を用いたデバイス
の実用化は困難であった。Further, regarding the ferroelectric substance PZT, Japanese Patent Laid-Open No. 62-62242
As disclosed in Japanese Patent Publication No. -30695, in order to obtain a C-axis oriented polycrystalline PZT thin film by a sputtering method, the underlayer temperature is kept at 600 ° C. during film formation, and in order to promote the growth of a single crystal film (100 ) A (100) -oriented Pt thin film is required as an underlayer on a MgO single crystal substrate. Regarding the ferroelectric PbTiO 3, which is currently being actively studied for thinning, Japanese Journal
l of Applied Physics Vol.24 (1985) Supplement 24-2, p
According to p.404-406, PbTiO 3 is formed by the RF sputtering method.
In order to form a ferroelectric polycrystalline thin film, it is necessary to subject the thin film to a heat treatment at a temperature of 520 ° C or higher after film formation.
nal of Vacuum Science and Technology Vol.A8 (3) (199
According to (0) pp.1382-1390, in order to obtain a PbTiO 3 single crystal ferroelectric film, the base temperature during film formation is maintained at 550 to 600 ° C. during film formation by the RF magnetron sputtering method, and further, the single crystal A (100) -oriented Pt thin film on a (100) MgO single crystal substrate is required as an underlayer to promote film growth. In order to obtain a ferroelectric thin film in this way, a special substrate is required and a high temperature process is also required.
It is difficult to put the device using the ferroelectric thin film into practical use because it requires a great deal of cost.
【０００６】[0006]
【発明の目的】本発明は、かかる従来技術の課題を解決
し、粒界がないため機械的強度が高く耐久性に優れた強
誘電体膜を用いたアクチュエータを、低温プロセスで提
供することを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art and to provide an actuator using a ferroelectric film having high mechanical strength and excellent durability because there are no grain boundaries in a low temperature process. To aim.
【０００７】[0007]
【問題を解決するための手段】上記問題を解決するため
に、本発明は電圧の印加により機械的歪みを生ずる素子
と弾性体を組み合わせた超音波振動子を備えているとと
もに前記弾性体の表面に接触する可動体を備えていて、
前記弾性体の表面に発生する進行波によって前記可動体
を動かすようにしたアクチュエータにおいて、前記素子
としてアモルファス構造を有する強誘電体薄膜を形成す
る手段をとる。本発明におけるアモルファス強誘電体膜
は、真空蒸着法、スパッタリング法などの製膜手段を用
いて基板上に、基板温度を５００℃以下に保持しながら
非晶質の薄膜として作製し、作製したそのままの状態
か、あるいは５００℃以下の温度で熱処理を施すことに
よって得られる。このようにして得られるアモルファス
強誘電体膜は、圧電性と同時に強誘電性を呈する。この
ようなアモルファス強誘電体膜としては、前記製法によ
り得られるものであれば、特に制限はないが、例えば、
Fe2O3-Bi2O3-ABO3（ペロブスカイト型化合物）を主成分
とした三元酸化物系薄膜が挙げられる。ABO3はPbTiO3,
PbZrO3, BaTiO3などの強誘電性、反強誘電性を示すペロ
ブスカイト型化合物である。In order to solve the above problems, the present invention is provided with an ultrasonic transducer in which an element that causes mechanical strain due to the application of a voltage and an elastic body are combined, and the surface of the elastic body is provided. It has a movable body that contacts
In an actuator configured to move the movable body by a traveling wave generated on the surface of the elastic body, means for forming a ferroelectric thin film having an amorphous structure as the element is adopted. The amorphous ferroelectric film according to the present invention is formed as an amorphous thin film on a substrate by using a film forming means such as a vacuum vapor deposition method or a sputtering method, while keeping the substrate temperature at 500 ° C. or lower. Or by performing heat treatment at a temperature of 500 ° C. or lower. The amorphous ferroelectric film obtained in this manner exhibits ferroelectricity as well as piezoelectricity. Such an amorphous ferroelectric film is not particularly limited as long as it is obtained by the above-mentioned manufacturing method, for example,
An example is a ternary oxide thin film containing Fe 2 O 3 -Bi 2 O 3 -ABO 3 (perovskite type compound) as a main component. ABO 3 is PbTiO 3 ,
It is a perovskite type compound showing ferroelectricity and antiferroelectricity such as PbZrO 3 and BaTiO 3 .
【０００８】[0008]
【実施例】以下、実施例により本発明を記述する。図１
(a) および(b) は本発明の一実施例を示す圧電薄膜共振
子のそれぞれ正面および底面から見た図を示すものであ
る。即ち、例えばアルミニウムのような導電性の弾性体
１上に、Fe2O3-Bi2O3-PbTiO3系薄膜などRFスパッタリン
グ法等により形成したアモルファス強誘電体膜２を形成
し、そのあと、該アモルファス強誘電体膜２の表面上
に、アルミニウム等の電極３を真空蒸着等の手段を用い
て形成する。このようにして作られた超音波振動子の上
にアルミニウムで形成されている可動体４を載置し、電
極３に高周波電圧を印加して、可動体４が弾性体１上を
移動することを確認した。なお、アモルファス強誘電体
膜２はFe2O3-Bi2O3-PbTiO3系薄膜のみならず、PbTiO3に
かえてPbZrO3、BaTiO3などの種々の強誘電性、反強誘電
性ペロブスカイト材料を用いてもよい。また、弾性体１
はアルミニウムに限られるものではなく、動作中に弾性
限度内の機械的ひずみが生じるものであればよいが、振
動損失の少ない金属を用いることが好ましい。さらに電
極３も円周方向分割に限られるものではなく、半径方向
分割等の他の電極構造も用いることができる。EXAMPLES The present invention will be described below with reference to examples. Figure 1
(a) And (b) is the figure which looked at the piezoelectric thin film resonator which shows one Example of this invention from the front and the bottom, respectively. That is, for example, an amorphous ferroelectric film 2 such as a Fe 2 O 3 —Bi 2 O 3 —PbTiO 3 thin film formed by an RF sputtering method or the like is formed on a conductive elastic body 1 such as aluminum. An electrode 3 made of aluminum or the like is formed on the surface of the amorphous ferroelectric film 2 by using a method such as vacuum deposition. The movable body 4 made of aluminum is placed on the ultrasonic transducer thus manufactured, and a high frequency voltage is applied to the electrode 3 so that the movable body 4 moves on the elastic body 1. It was confirmed. The amorphous ferroelectric film 2 is not limited to Fe 2 O 3 -Bi 2 O 3 -PbTiO 3 based thin film, but may be PbTiO 3 instead of various ferroelectric or antiferroelectric perovskites such as PbZrO 3 and BaTiO 3. Materials may be used. Also, the elastic body 1
Is not limited to aluminum as long as mechanical strain within the elastic limit is generated during operation, but it is preferable to use a metal having a small vibration loss. Further, the electrode 3 is not limited to the circumferential division, but other electrode structures such as radial division can be used.
【０００９】本例に引用したアモルファス強誘電体薄膜
は以下に述べる方法で作製した。すなわち、薄膜作製に
はRFマグネトロンスパッタリング装置を用い、スパッタ
ガスはAr:O2=7:3 の混合ガスとした。スパッタリング中
は基体を固定している銅製のアノードを水冷し、製膜中
の基板温度を20〜25℃に維持した。このようにして作製
した薄膜は製膜後熱処理を施すことなく圧電性を示すア
モルファス強誘電体膜となった。このアモルファス強誘
電体膜はアモルファスゆえに結晶粒界が存在しないた
め、素子の微細化が可能であり、また多結晶強誘電体膜
あるいは多結晶圧電膜の場合に生じる粒界からの機械的
疲労破壊や粒界による弾性波の散乱を回避できる等の優
れた特長を有しており、このアモルファス強誘電体膜を
用いることにより、製膜時には低い基板温度で、また製
膜後も500 ℃以上の高温での熱処理を施すことなしに、
さらに特に基板を指定せずに、安価な作製条件で耐久性
に優れたアクチュエータを形成できた。The amorphous ferroelectric thin film cited in this example was prepared by the method described below. That is, an RF magnetron sputtering apparatus was used for thin film production, and the sputtering gas was a mixed gas of Ar: O 2 = 7: 3. During sputtering, the copper anode fixing the substrate was water-cooled and the substrate temperature during film formation was maintained at 20 to 25 ° C. The thin film thus manufactured became an amorphous ferroelectric film exhibiting piezoelectricity without heat treatment after film formation. Since this amorphous ferroelectric film does not have crystal grain boundaries because it is amorphous, it is possible to miniaturize the device, and mechanical fatigue fracture from the grain boundaries that occurs in the case of polycrystalline ferroelectric film or polycrystalline piezoelectric film. It has excellent features such as the prevention of scattering of elastic waves due to grain boundaries and grain boundaries.By using this amorphous ferroelectric film, the substrate temperature is low during film formation, and even after film formation, the temperature is 500 ° C or higher. Without heat treatment at high temperature
Furthermore, it was possible to form an actuator with excellent durability under inexpensive manufacturing conditions without specifying a substrate.
【００１０】[0010]
【発明の効果】以上の説明により明らかなように、本発
明により粒界がなく弾性波の散乱もなくまた耐久性に優
れた、さらに低温プロセスで作製可能なアクチュエータ
を提供できる。As is apparent from the above description, the present invention can provide an actuator which has no grain boundaries, does not scatter elastic waves, and has excellent durability and which can be manufactured by a low temperature process.
【図１】図１は、本発明の一実施例を説明する圧電薄膜
共振子の正面図(a)および底面図(b) である。FIG. 1 is a front view (a) and a bottom view (b) of a piezoelectric thin film resonator for explaining an embodiment of the present invention.
１ 弾性体 ２ アモルファス強誘電体膜 ３ 電極 ４ 可動体 1 elastic body 2 Amorphous ferroelectric film 3 electrodes 4 movable body
フロントページの続き (72)発明者 二井 裕之 山口県宇部市大字小串1978番地の５ 宇部 興産株式会社無機材料研究所内Continued front page (72) Inventor Hiroyuki Nii 5 Ube, 1978, Kogushi, Obu, Ube City, Yamaguchi Prefecture Kosan Inorganic Materials Research Center
Claims (3)
と弾性体を組み合わせた超音波振動子を備えているとと
もに前記弾性体の表面に接触する可動体を備えていて、
前記弾性体の表面に発生する進行波によって前記可動体
を動かすようにしたアクチュエータにおいて、前記素子
が前記弾性体の表面にアモルファス強誘電体膜を堆積形
成して成ることを特徴とするアクチュエータ。1. An ultrasonic vibrator comprising an element and an elastic body that generate mechanical strain upon application of a voltage, and a movable body that comes into contact with the surface of the elastic body.
An actuator in which the movable body is moved by a traveling wave generated on the surface of the elastic body, wherein the element is formed by depositing an amorphous ferroelectric film on the surface of the elastic body.
用いて基板上に、基板温度を５００℃以下に保持しなが
ら非晶質の薄膜として作製し、作製したそのままの状態
か、あるいは５００℃以下の温度で熱処理することによ
って得られたものであることを特徴とする請求項１のア
クチュエータ。2. An amorphous ferroelectric film is formed as an amorphous thin film on a substrate by using a film forming means while keeping the substrate temperature at 500 ° C. or lower, and the as-prepared state or 500 The actuator according to claim 1, which is obtained by heat treatment at a temperature of ℃ or less.
3-ABO3（ペロブスカイト型化合物）を主成分とした三元
酸化物系薄膜からなることを特徴とする請求項１のアク
チュエータ。3. The amorphous ferroelectric film is Fe 2 O 3 -Bi 2 O.
The actuator according to claim 1, wherein the actuator comprises a ternary oxide thin film containing 3- ABO 3 (perovskite type compound) as a main component.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3205658A JPH0530763A (en) | 1991-07-23 | 1991-07-23 | Actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3205658A JPH0530763A (en) | 1991-07-23 | 1991-07-23 | Actuator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0530763A true JPH0530763A (en) | 1993-02-05 |
Family
ID=16510546
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3205658A Pending JPH0530763A (en) | 1991-07-23 | 1991-07-23 | Actuator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0530763A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6998763B2 (en) | 2001-08-31 | 2006-02-14 | Ngk Insulators, Ltd. | Ceramic device |
| JP3904240B2 (en) * | 1996-11-29 | 2007-04-11 | 日本碍子株式会社 | Ceramic element |
| US7726783B2 (en) | 2007-03-16 | 2010-06-01 | Fujifilm Corporation | Liquid discharge apparatus |
-
1991
- 1991-07-23 JP JP3205658A patent/JPH0530763A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3904240B2 (en) * | 1996-11-29 | 2007-04-11 | 日本碍子株式会社 | Ceramic element |
| US6998763B2 (en) | 2001-08-31 | 2006-02-14 | Ngk Insulators, Ltd. | Ceramic device |
| US7726783B2 (en) | 2007-03-16 | 2010-06-01 | Fujifilm Corporation | Liquid discharge apparatus |
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