JPH0356013B2 - - Google Patents
Info
- Publication number
- JPH0356013B2 JPH0356013B2 JP56127057A JP12705781A JPH0356013B2 JP H0356013 B2 JPH0356013 B2 JP H0356013B2 JP 56127057 A JP56127057 A JP 56127057A JP 12705781 A JP12705781 A JP 12705781A JP H0356013 B2 JPH0356013 B2 JP H0356013B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- piezoelectric
- thickness
- order
- electromechanical coupling
- 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.)
- Expired - Lifetime
Links
- 239000010409 thin film Substances 0.000 claims description 180
- 239000000463 material Substances 0.000 claims description 18
- 229910010272 inorganic material Inorganic materials 0.000 claims description 8
- 239000011147 inorganic material Substances 0.000 claims description 8
- 230000008878 coupling Effects 0.000 description 34
- 238000010168 coupling process Methods 0.000 description 34
- 238000005859 coupling reaction Methods 0.000 description 34
- 239000000758 substrate Substances 0.000 description 27
- 229910052710 silicon Inorganic materials 0.000 description 24
- 239000010703 silicon Substances 0.000 description 24
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 23
- 229910004298 SiO 2 Inorganic materials 0.000 description 16
- 238000005530 etching Methods 0.000 description 14
- 230000004044 response Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 5
- 238000004544 sputter deposition Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 239000010931 gold Substances 0.000 description 4
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 229910004613 CdTe Inorganic materials 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- -1 Furthermore Substances 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000007733 ion plating Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/174—Membranes
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Description
【発明の詳細な説明】
本発明は圧電薄膜を用いたVHF、UHF用高調
波圧電振動子に関し、特に薄膜部材と、圧電薄膜
との組合せからなる複合構造の振動部位を有する
薄膜圧電振動子に関するものである。薄膜圧電振
動子は、基本的には圧電性薄板の両側に電極を備
えた構造をしており、電極形状を変えることによ
り、フイルタや発振器等にも利用でき、応用範囲
の広い素子である。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a harmonic piezoelectric vibrator for VHF and UHF using a piezoelectric thin film, and more particularly to a thin film piezoelectric vibrator having a vibrating part of a composite structure consisting of a combination of a thin film member and a piezoelectric thin film. It is something. A thin film piezoelectric vibrator basically has a structure with electrodes on both sides of a piezoelectric thin plate, and by changing the shape of the electrodes, it can be used for filters, oscillators, etc., making it a device with a wide range of applications.
一般に数十ＭHz以上のような高い周波数で使用
される圧電振動子は、振動モードとして板面が厚
さに比して十分広い圧電性薄板の厚み振動を使用
する。 Generally, piezoelectric vibrators used at high frequencies, such as several tens of MHz or more, use thickness vibration of a piezoelectric thin plate whose surface is sufficiently wide compared to its thickness as a vibration mode.
厚み振動の共振周波数は圧電性薄板の厚さに反
比例するので高い周波数で使用するためには厚さ
を薄くしなければならない。しかし、厚さが40ミ
クロン程度以下になると圧電材料であるバルク結
晶やセラミツクの平行平面研磨加工が非常に難し
くなり、したがつてこれらの材料を用いて基本共
振周波数で50MHz以上の厚み振動圧電振動子を量
産することは困難である。これに対して、バルク
結晶或いはセラミツク等の比較的厚い板面の厚み
振動の奇数次の高調波を使用すれば、同じ厚みで
基本波の３倍、５倍……等の共振周波数が得ら
れ、これはオーバートーン振動子として発振器な
どに使われている。しかし第ｎ次の高調波を用い
た場合の電気機械結合係数k2 oは基本波の電気機械
結合係数k1 2の１／n2倍となり、このとき共振周
波数と反共振周波数の間隔との共振周波数との比
は、ほぼk1 2／2n2となる。したがつて高調波を使
つたのでは電気機械結合係数の減少に伴つてフイ
ルタの比帯域及び発振器の制御範囲が狭くなりす
ぎる結果を招き、これまた実用に適さないことが
多くなる。 Since the resonant frequency of thickness vibration is inversely proportional to the thickness of the piezoelectric thin plate, the thickness must be reduced in order to use it at a high frequency. However, when the thickness becomes less than about 40 microns, parallel plane polishing of bulk crystals and ceramics, which are piezoelectric materials, becomes extremely difficult. It is difficult to mass produce children. On the other hand, if you use odd-order harmonics of the thickness vibration of a relatively thick plate such as bulk crystal or ceramic, you can obtain a resonance frequency that is 3 times, 5 times, etc. of the fundamental wave with the same thickness. , which is used as an overtone oscillator in oscillators, etc. However, when using the n-th harmonic, the electromechanical coupling coefficient k 2 o is 1/n 2 times the electromechanical coupling coefficient k 1 2 of the fundamental wave, and in this case, the interval between the resonant frequency and the anti-resonant frequency is The ratio to the resonance frequency is approximately k 1 2 /2n 2 . Therefore, if harmonics are used, as the electromechanical coupling coefficient decreases, the fractional band of the filter and the control range of the oscillator become too narrow, and this is often not suitable for practical use.
高調波を用いる他の方法は、基板の上に圧電薄
膜を作成し圧電薄膜の厚さが半波長であるような
共振モードに於いて基板を高次振動させるもので
あり、この場合基板の厚さが基板内を伝播する音
波を半波長の整数倍に等しいときに電気機械結合
係数は最大値を持つが、この値は共振モードが高
次になるに従つてやはり減少する。この方法に於
いても基板を薄くすることは非常に困難であり、
例えば50ミクロン程度の基板を作製できたとして
も50MHzの周波数では３〜５次以上の共振モード
を用いることになり、電気機械結合係数が小さく
なるため基板の厚さを音波の半波長の整数倍に一
致させたとしてもフイルタの比帯域幅及び発振器
の制御範囲は狭くなり実用に適さない。 Another method using harmonics is to create a piezoelectric thin film on a substrate and cause the substrate to vibrate at a higher order in a resonant mode where the thickness of the piezoelectric thin film is half a wavelength. The electromechanical coupling coefficient has a maximum value when the acoustic wave propagating in the substrate is equal to an integer multiple of half the wavelength, but this value also decreases as the resonance mode becomes higher order. Even with this method, it is extremely difficult to make the substrate thinner.
For example, even if a substrate of about 50 microns can be fabricated, at a frequency of 50 MHz, 3rd to 5th or higher resonance modes will be used, and the electromechanical coupling coefficient will be small, so the thickness of the substrate should be an integer multiple of the half wavelength of the sound wave. Even if it is made to match, the fractional bandwidth of the filter and the control range of the oscillator will become narrow, making it unsuitable for practical use.
上記のような方法の欠点を改善した圧電振動子
を得る方法として、シリコン基板上に蒸着等によ
つて電極（金、アルミニウム等）圧電薄膜
（CdS、又はCdTe）電極（金、アルミニウム等）
の順で形成し、この振動部分に対応する部分の基
板をエツチングによつて除去することにより振動
部分はその上下面に電極を有する圧電薄膜からな
り、外縁部を基板によつて支持された構造の薄膜
圧電振動子が公知である。（特公昭46−25579）こ
の振動子は振動部分が薄いため50MHz以上の高い
周波数においても基本振動あるいは低次の高調波
振動を使用することができ、したがつて広い比帯
域のフイルターを実現することができる。しかし
この薄膜圧電振動子は圧電薄膜としてCdSあるい
はCdTeを用いているため音響的クオリテイフア
クター（Ｑ）が小さく、温度係数が大きく、また
振動部分が薄いため機械的強度が小さいという欠
点を有している。また現在圧電材料として薄膜化
が可能なZnOを用いても前記の欠点はあまり改善
されない。上記の特公昭46−25579においてはシ
リコン基板上にSiO2薄膜を形成しその上に電極、
圧電薄膜電極の順で形成し、この振動部分に対応
する部分の基板をエツチングによつて除去し、振
動部分がSiO2薄膜とその上下面に電極を有する
圧電薄膜からなり、外縁部を基板によつて支持さ
れた構造の薄膜圧電振動子も開示されている。
SiO2薄膜を形成した効果はこのSiO2薄膜の部分
でエツチングを止める効果の他に、当該振動子の
機械的強度を高め、振動子特性の温度係数を小さ
くする効果を有する。この振動子について第１
図、第２図を用いてさらに詳しく説明する。 As a method of obtaining a piezoelectric vibrator that improves the drawbacks of the above methods, electrodes (gold, aluminum, etc.), piezoelectric thin films (CdS, or CdTe), electrodes (gold, aluminum, etc.) are deposited on a silicon substrate by vapor deposition, etc.
By etching away the part of the substrate corresponding to the vibrating part, a structure is formed in which the vibrating part is made of a piezoelectric thin film having electrodes on its upper and lower surfaces, and the outer edge is supported by the substrate. A thin film piezoelectric vibrator is known. (Special Publication No. 46-25579) Since the vibrating part of this vibrator is thin, it is possible to use fundamental vibration or low-order harmonic vibration even at high frequencies of 50 MHz or higher, thus realizing a filter with a wide specific band. be able to. However, since this thin film piezoelectric vibrator uses CdS or CdTe as the piezoelectric thin film, it has the disadvantages of a small acoustic quality factor (Q), a large temperature coefficient, and a low mechanical strength because the vibrating part is thin. ing. Further, even if ZnO, which can be made into a thin film, is used as a piezoelectric material at present, the above-mentioned drawbacks cannot be improved much. In the above-mentioned Japanese Patent Publication No. 46-25579, a SiO 2 thin film is formed on a silicon substrate, and electrodes and
A piezoelectric thin film electrode is formed in this order, and the part of the substrate corresponding to this vibrating part is removed by etching. A thin film piezoelectric vibrator of a supported structure is also disclosed.
The effect of forming the SiO 2 thin film is not only to stop etching at this SiO 2 thin film portion, but also to increase the mechanical strength of the vibrator and to reduce the temperature coefficient of the vibrator characteristics. About this vibrator
This will be explained in more detail with reference to FIGS.
この薄膜圧電振動子の構造を第１図に示す。第
１図に於いて１１は基板、１２はエツチングによ
つて基板に形成した空孔である。１３は薄膜、１
４は圧電薄膜、１５，１６は圧電薄膜の両面に対
向して設けた電極である。第１図の構造の薄膜圧
電振動子の電気機械結合係数k2は薄膜１３の厚さ
t′と圧電薄膜１４の厚さｔの比によつて変化す
る。たとえば圧電薄膜１４としてZnO薄膜を用
い、薄膜１３としてSiO2薄膜を用いた場合、k2
を理論式から求めるとk2は薄膜１３の厚さt′と圧
電薄膜１４の厚さの比t′／ｔにしたがつて第２図
のように変化する。第２図に於いて横軸は厚さの
比t′／ｔ縦軸は電気機械結合係数k2であり、曲線
に記した数字は振動の次数を示す。第２図から予
想されるように、第１図の構造の薄膜圧電振動子
では基本振動を用いる場合、圧電薄膜１４に対し
て薄膜１３の厚さが十分薄いたとえばt′／ｔ＜0.2
であるような範囲で大きな電気機械結合係数が得
られ、したがつて比帯域幅の広いフイルタ或いは
制御範囲の広い発振器として利用できる。しかし
第３次或いは第４次の高調波振動も比較的大きな
電気機械結合係数を有することが第２図から予想
され、したがつて高周波側に第３次或いは第４次
の高調波共振に伴う不要応答が生じるという欠点
がある。一方、第１図の構造で圧電薄膜１４に対
して薄膜１３の厚さt′をt′／ｔ＜0.2のように大き
くすることは振動子部分の機械的強度を高める上
で有利であるが、第２図からわかるように薄膜１
３の厚さt′の増大に伴つて基本振動の電気機械結
合係数は減少し、さらに第２次の高調波振動の電
気機械係数が増大する。したがつて、薄膜１３の
厚さが厚い場合には、フイルタの比帯域幅が狭く
なる、或いは発振器の制御範囲が狭くなるという
欠点を有すると同時に、高周波側に第２次の高調
波共振に伴う不要応答が生じるという欠点を有す
る。 The structure of this thin film piezoelectric vibrator is shown in FIG. In FIG. 1, 11 is a substrate, and 12 is a hole formed in the substrate by etching. 13 is a thin film, 1
4 is a piezoelectric thin film, and 15 and 16 are electrodes provided oppositely on both sides of the piezoelectric thin film. The electromechanical coupling coefficient k 2 of the thin film piezoelectric vibrator with the structure shown in FIG. 1 is the thickness of the thin film 13.
It changes depending on the ratio between t' and the thickness t of the piezoelectric thin film 14. For example, if a ZnO thin film is used as the piezoelectric thin film 14 and a SiO 2 thin film is used as the thin film 13, k 2
When obtained from a theoretical formula, k 2 changes as shown in FIG. 2 according to the ratio t'/t of the thickness t' of the thin film 13 and the thickness of the piezoelectric thin film 14. In FIG. 2, the horizontal axis is the thickness ratio t'/t, the vertical axis is the electromechanical coupling coefficient k2 , and the numbers written on the curves indicate the order of vibration. As expected from FIG. 2, when fundamental vibration is used in the thin film piezoelectric vibrator having the structure shown in FIG.
A large electromechanical coupling coefficient can be obtained in the range where , and therefore it can be used as a filter with a wide fractional bandwidth or an oscillator with a wide control range. However, it is expected from Figure 2 that the 3rd or 4th harmonic vibration also has a relatively large electromechanical coupling coefficient. This has the disadvantage that unnecessary responses occur. On the other hand, in the structure shown in FIG. 1, increasing the thickness t' of the thin film 13 relative to the piezoelectric thin film 14 such that t'/t<0.2 is advantageous in increasing the mechanical strength of the vibrator portion. , as can be seen from Figure 2, thin film 1
As the thickness t' of 3 increases, the electromechanical coupling coefficient of the fundamental vibration decreases, and the electromechanical coefficient of the second harmonic vibration increases. Therefore, when the thickness of the thin film 13 is thick, it has the disadvantage that the filter's fractional bandwidth becomes narrow or the control range of the oscillator becomes narrow, and at the same time, it causes second harmonic resonance on the high frequency side. This method has the disadvantage that unnecessary responses occur.
本発明の目的は上記のような従来の薄膜圧電振
動子の欠点を除き、基本振動の電気機械結合係数
が大きく、高次振動の電気機械結合係数が極めて
小さい薄膜圧電振動子を実現することであり、本
発明の薄膜圧電振動子を用いれば高周波側に不要
応答がなく、広い比帯域幅を有するフイルタ或い
は制御範囲の広い発振器が実現できる。本発明の
薄膜圧電振動子の最たる特徴は振動部位が無機材
料の薄膜部材−電極−圧電電極−電極−無機材料
の薄膜部材から成る多層構造を有する点にある。 The purpose of the present invention is to eliminate the drawbacks of the conventional thin-film piezoelectric vibrators as described above, and to realize a thin-film piezoelectric vibrator that has a large electromechanical coupling coefficient for fundamental vibrations and an extremely small electromechanical coupling coefficient for higher-order vibrations. If the thin film piezoelectric vibrator of the present invention is used, a filter with a wide fractional bandwidth or an oscillator with a wide control range can be realized without unnecessary responses on the high frequency side. The most distinctive feature of the thin film piezoelectric vibrator of the present invention is that the vibrating portion has a multilayer structure consisting of a thin film member made of an inorganic material, an electrode, a piezoelectric electrode, an electrode, and a thin film member made of an inorganic material.
以下に本発明を詳細に説明する。第３図は本発
明の薄膜圧電振動子の基本的な構造を示す図であ
る。第３図において３１はシリコン、水晶などか
らなる基板であり、３２はエツチングによつて基
板に形成した空孔である。３３，３４は薄膜部
材、３５は圧電薄膜、３６，３７は圧電薄膜と上
下の薄膜部材との界面に設けた電極である。基板
３１に用いる材料としてはエツチングで空孔を形
成することが可能な材料であればどのような材料
でも良い。望ましい材料の一つとして表面が
（100）面であるようなシリコンがある。このよう
なシリコンは、たとえばKOH、エチレンジアミ
ンのようなエツチング液を使用すれば、（100）面
のエツチング速度に比較して（111）面のエツチ
ング速度が非常に小さいというエツチングの異方
性を示すことにより面方向へのエツチングの拡が
りが極めて小さく、したがつて精度良く空孔の寸
法を制御できる利点がある。圧電薄膜３５として
はZnO、CdS、AlNなどの結晶系が六方晶系の圧
電材料やPbTiO3、PZT、BaTiO3などの種々の
圧電材料を使用することができる。なかでもZnO
はスパツタリング法、CVD法、イオン・プレー
テイング法などによつてＣ軸が基板面に対して垂
直に配向し、かつ高い抵抗率の薄膜を再現性良く
作製でき、しかも厚みたて振動モードのエネルギ
ー閉じ込めが可能であるため最適な材料といえよ
う。薄膜部材としては絶縁体、シリコンなどの半
導体、あるいは金属の薄膜など、どのような材料
を使用しても、本発明の目的が達成される。中で
も第３図３３，３４の薄膜部材として共にSiO2
薄膜を使用すると一般に圧電薄膜の弾性定数が負
の温度系数を有するのに対し、SiO2の弾性定数
は正の温度係数を有することが知られており、し
たがつて温度依存性の小さい薄膜圧電振動子が実
現できる。またシリコンは機械的強度が高く、音
響的クオリテイ・フアクタ（Ｑ）が大きいところ
から、特に振動部位の厚さの薄いことが要求され
る。300MHz以上のような高い周波数に於いても
シリコン薄膜を薄膜部材として用いれば振動部位
の機械的強度を高めることができる。また特に損
失の小さいフイルタ或いは共振の尖鋭度の大きな
共振子が要求される場合にも薄膜部材にシリコン
薄膜を用いればその大きな音響的クオリテイ・フ
アクタ（Ｑ）により要求を実現することができ
る。この場合には第３図３３の薄膜部材としてシ
リコン薄膜を使用し、薄膜部材３４としては
SiO2薄膜を使用するのが温度特性の観点からも
望ましい。ただしこの薄膜部材の材料としては
SiO2やSiに限らず他の絶縁材料や半導体材料、
さらには金属材料も使用可能である。 The present invention will be explained in detail below. FIG. 3 is a diagram showing the basic structure of the thin film piezoelectric vibrator of the present invention. In FIG. 3, 31 is a substrate made of silicon, crystal, etc., and 32 is a hole formed in the substrate by etching. 33 and 34 are thin film members, 35 is a piezoelectric thin film, and 36 and 37 are electrodes provided at the interfaces between the piezoelectric thin film and the upper and lower thin film members. Any material may be used for the substrate 31 as long as it can form holes by etching. One of the desirable materials is silicon, which has a (100) surface. Such silicon exhibits etching anisotropy in that when an etching solution such as KOH or ethylenediamine is used, the etching rate of the (111) plane is much lower than that of the (100) plane. This has the advantage that the spread of etching in the planar direction is extremely small, and therefore the size of the holes can be controlled with high precision. As the piezoelectric thin film 35, various piezoelectric materials such as hexagonal piezoelectric materials such as ZnO, CdS, and AlN, and PbTiO 3 , PZT, and BaTiO 3 can be used. Among them, ZnO
By sputtering, CVD, ion plating, etc., thin films with high resistivity and C-axis oriented perpendicular to the substrate surface can be fabricated with good reproducibility, and the energy of the thick vibration mode is low. It can be said to be the most suitable material because it can be confined. The object of the present invention can be achieved no matter what material is used as the thin film member, such as an insulator, a semiconductor such as silicon, or a metal thin film. Among them, both SiO 2 are used as the thin film members in Fig. 3 33 and 34.
When using a thin film, it is known that the elastic constant of a piezoelectric thin film generally has a negative temperature coefficient, whereas the elastic constant of SiO 2 has a positive temperature coefficient. A vibrator can be realized. Furthermore, since silicon has high mechanical strength and a large acoustic quality factor (Q), it is particularly required that the thickness of the vibrating portion be thin. Even at high frequencies such as 300 MHz or higher, the mechanical strength of the vibrating part can be increased by using a silicon thin film as a thin film member. Furthermore, even when a filter with particularly low loss or a resonator with high resonance sharpness is required, the requirements can be realized by using a silicon thin film as the thin film member due to its large acoustic quality factor (Q). In this case, a silicon thin film is used as the thin film member shown in FIG.
It is also desirable to use a SiO 2 thin film from the viewpoint of temperature characteristics. However, the material for this thin film member is
Not limited to SiO 2 and Si, other insulating materials and semiconductor materials,
Furthermore, metal materials can also be used.
次に圧電薄膜の上下に形成された薄膜を有する
本発明の薄膜圧電振動子において電気機械結合係
数k2と該薄膜の厚さの関係を第４〜６図を用いて
説明する。 Next, the relationship between the electromechanical coupling coefficient k2 and the thickness of the thin film in the thin film piezoelectric vibrator of the present invention having thin films formed above and below the piezoelectric thin film will be explained using FIGS. 4 to 6.
第４図は第３図の構造において圧電薄膜３５が
厚さｔのZnO薄膜であり薄膜部材３３，３４が共
にSiO2薄膜であつてこの２つの薄膜の合計の厚
さがｔ／２に等しい場合について、薄膜部材３３
の厚さt33と薄膜部材３４の厚さt34との比t34／t33
を変化させた場合の電気機械結合係数k2の変化を
理論式から求めたものである。第４図に於いて曲
線に付した数字は振動の次数を示す。t34／t33＝
０は前述の従来例で片面だけに薄膜部材を有する
構造の場合に対応する。第４図から明らかなよう
に薄膜部材３４の厚さが増大するに伴つて基本振
動の電気機械結合係数が急速に増大し、偶数次の
高次振動の電気機械結合係数は逆に急速に減少し
てゆく。 FIG. 4 shows the structure of FIG. 3 in which the piezoelectric thin film 35 is a ZnO thin film with a thickness of t, the thin film members 33 and 34 are both SiO 2 thin films, and the total thickness of these two thin films is equal to t/2. In this case, the thin film member 33
The ratio between the thickness t 33 and the thickness t 34 of the thin film member 34 is t 34 /t 33
The change in the electromechanical coupling coefficient k 2 when changing is calculated from a theoretical formula. The numbers attached to the curves in FIG. 4 indicate the order of vibration. t 34 / t 33 =
0 corresponds to the case of the structure having a thin film member on only one side in the conventional example described above. As is clear from FIG. 4, as the thickness of the thin film member 34 increases, the electromechanical coupling coefficient for fundamental vibrations increases rapidly, and on the contrary, the electromechanical coupling coefficient for even-order higher-order vibrations rapidly decreases. I will do it.
すなわち従来の構造に比べ圧電薄膜の上下に薄
膜を形成し、これらの薄膜の厚さをしだいに等し
くなるように変化させてゆくと振動子の特性は大
きく改善されてゆく。特に両面の薄膜部材の厚さ
が等しくなつたときに基本振動の電気機械結合係
数が最大となり、また偶数次の高次振動は完全に
抑圧され、最適な振動子特性が得られる。薄膜部
材３３と薄膜部材３４が異なる材料からなる場合
にも第４図と同様の変化を示すがこのときには、
それぞれの薄膜部材の厚さがそれぞれの薄膜での
音速に対して等しい比を有するような厚さの比に
おいて基本振動の電気機械結合係数が最大とな
り、かつ偶数次の高次振動が完全に抑圧される。
例えば薄膜部材３３が音速8430ｍ／ｓのシリコン
薄膜であり、薄膜部材３４が音速5960ｍ／ｓの
SiO2薄膜であれば厚さの比t34／t33が0.71に等し
いときに基本振動を電気機械結合係数が最大とな
り、かつ偶数次の高次振動が完全に抑圧される。 That is, compared to the conventional structure, by forming thin films above and below the piezoelectric thin film and gradually changing the thickness of these thin films so that they are equal, the characteristics of the vibrator are greatly improved. In particular, when the thicknesses of the thin film members on both sides are equal, the electromechanical coupling coefficient of fundamental vibrations becomes maximum, and even-order higher-order vibrations are completely suppressed, resulting in optimal vibrator characteristics. Even when the thin film member 33 and the thin film member 34 are made of different materials, changes similar to those shown in FIG. 4 are shown, but in this case,
At a thickness ratio where the thickness of each thin film member has an equal ratio to the sound velocity in each thin film, the electromechanical coupling coefficient of fundamental vibration becomes maximum, and even-order higher-order vibrations are completely suppressed. be done.
For example, the thin film member 33 is a silicon thin film with a sound speed of 8430 m/s, and the thin film member 34 has a sound speed of 5960 m/s.
In the case of a SiO 2 thin film, when the thickness ratio t 34 /t 33 is equal to 0.71, the electromechanical coupling coefficient for fundamental vibrations becomes maximum, and even higher-order vibrations are completely suppressed.
次に当該薄膜の厚さが等しいとき、あるいは薄
膜材料が異なる場合においてそれぞれの厚さが音
速に対して等しい比を有するような厚さの比であ
る場合について説明する。 Next, a case will be described in which the thicknesses of the thin films are the same, or when the thin films are made of different materials, the thickness ratio is such that each thickness has an equal ratio to the speed of sound.
第５図は第３図の薄膜部材３３，３４が等しい
厚さの同一の材料からなるか、あるいは異なる材
料からなりそれぞれの薄膜部材の厚さの比がそれ
ぞれの薄膜での音速の比に等しい比を有するよう
に形成された場合の振動部位に於ける厚みたて振
動の応力分布を示した図であり、Ａ，Ｂ，Ｃ，Ｄ
はそれぞれ基本振動、２次、３次、４次の高次振
動についての応力分布イ，ロ，ハ，ニである。第
５図において４１は圧電薄膜、４２，４３は薄膜
部材、４４，４５は電極である。薄膜部材４２，
４３のそれぞれの外側で応力は零であり、応力が
零の点の左右で応力の向きは逆である。第５図Ｂ
及びＤからわかるようにこのような多層構造では
第２次、第４次のような偶数の次の高次振動に於
いて圧電薄膜中すなわち電極の間の応力の積分は
零となり、したがつて偶数次の高次振動は励振さ
れない。また第５図Ａからわかるようにこのよう
な多層構造では基本振動に於いて圧電薄膜が応力
最大の付近に位置しているため、従来のような圧
電薄膜の一方の面だけに薄膜部材を有する構造に
比べさらには両面の薄膜の厚さが異なる場合に比
べても大きな電気機械結合係数が得られる。第５
図では薄膜部材４２，４３が等しい厚さの同一の
材料からなるか、あるいは異なる材料からなりそ
れぞれの薄膜部材の厚さの比がそれぞれの薄膜で
の音速の比に等しい比を有する場合を示したが、
第４図に示したように薄膜部材の厚さについて上
記のように限定しない場合でも薄膜部材の厚さが
比較的近い範囲では第３図のごとく多層構造とす
ることにより、第１図に示した従来の構造に比べ
て偶数次の高次振動を抑制し、基本振動の電気機
械係合係数が大きな薄膜圧電圧電振動子が得られ
る。 FIG. 5 shows whether the thin film members 33 and 34 in FIG. 3 are made of the same material with the same thickness, or are made of different materials, and the ratio of the thickness of each thin film member is equal to the ratio of the speed of sound in each thin film. It is a diagram showing the stress distribution of the thickness vertical vibration in the vibrating part when it is formed to have a ratio of A, B, C, D.
are stress distributions A, B, C, and D for fundamental vibration, second-order, third-order, and fourth-order higher-order vibrations, respectively. In FIG. 5, 41 is a piezoelectric thin film, 42 and 43 are thin film members, and 44 and 45 are electrodes. thin film member 42,
The stress is zero outside each of the points 43, and the direction of the stress is opposite on the left and right of the point where the stress is zero. Figure 5B
As can be seen from and D, in such a multilayer structure, the integral of stress in the piezoelectric thin film, that is, between the electrodes, becomes zero in even-numbered higher-order vibrations such as the second and fourth orders, and therefore, Even higher order vibrations are not excited. In addition, as can be seen from Figure 5A, in such a multilayer structure, the piezoelectric thin film is located near the maximum stress in fundamental vibrations, so it is difficult to have a thin film member on only one side of the piezoelectric thin film like in the past. A large electromechanical coupling coefficient can be obtained compared to the structure, and even compared to the case where the thickness of the thin films on both sides is different. Fifth
The figure shows the case where the thin film members 42 and 43 are made of the same material with the same thickness, or are made of different materials, and the ratio of the thicknesses of the respective thin film members is equal to the ratio of the sound speeds in the respective thin films. However,
As shown in FIG. 4, even if the thickness of the thin film member is not limited as described above, as long as the thickness of the thin film member is relatively close, the multilayer structure shown in FIG. A thin-film piezoelectric vibrator can be obtained which suppresses even-order high-order vibrations and has a large electromechanical engagement coefficient of fundamental vibrations compared to conventional structures.
次に第６図は上記のような本発明の原理及び特
徴をより詳しく説明するために第３図の構造の薄
膜圧電振動子について、一例として薄膜３３及び
３４が等しい厚さを有するSiO2であつて、圧電
薄膜３５がZnOである場合の電気機械結合係数k2
を理論式から求めたものである。第６図において
横軸は薄膜３３及び３４の厚さの和t′と圧電薄膜
３５の厚さｔとの比、縦軸は電気機械結合係数k2
であり曲線に記した数字は振動の次数を示す。第
６図から明らかなように、第３図の構造の薄膜圧
電振動子においては第２次、第４次などの偶数次
の高次振動はまつたく励振されていないばかりで
なく、たとえばt′／ｔ＞0.2のように圧電薄膜の上
下の薄膜を厚くした場合の基本振動の電気機械結
合係数k2は従来の構造では第２図のように急速に
減少するの対し、第３図の構造では非常にゆるや
かに減少するという特長を有する。圧電薄膜の上
下の薄膜の厚さをたとえばt′／ｔ＞0.2のように厚
くすることは特に振動子の厚さが薄いことが要求
される300MHz以上の周波数において振動子の機
械的強度を高める点で有利であり、また特にシリ
コン膜を用いるとさらに振動子の音響的なクオリ
テイ・フアクタＱを大きくする点で有利である
が、本発明による第３図の構造の薄膜圧電振動子
では上記のような特長を有する結果、圧電薄膜の
上下の薄膜の厚さを厚くした場合でも基本振動の
電気機械結合係数が大きく、高次振動による不要
応答の小さい薄膜圧電振動子が実現できる。また
圧電薄膜の上下の薄膜が薄い場合にも、従来の構
造では第４次の高次振動が強く励振されるのに対
し、本発明による第３図の構造においては第４次
の高次振動は完全に抑制される。特に第６図にお
いてt′／ｔ〜0.33付近では第３次、第５次の高次
振動の電気機械結合係数は共に小さく、かつ基本
振動の電気機械結合係数は最大となる。したがつ
て圧電薄膜の上下の薄膜が薄い場合にも基本振動
の電気機械結合係数が大きく、高次振動による不
要応答の小さい薄膜圧電振動子が実現できる。 Next, FIG. 6 shows a thin film piezoelectric vibrator having the structure shown in FIG. 3, in order to explain the principle and features of the present invention in more detail as described above . Electromechanical coupling coefficient k 2 when the piezoelectric thin film 35 is ZnO
was obtained from the theoretical formula. In FIG. 6, the horizontal axis is the ratio of the sum t' of the thicknesses of the thin films 33 and 34 to the thickness t of the piezoelectric thin film 35, and the vertical axis is the electromechanical coupling coefficient k 2
The numbers written on the curve indicate the order of vibration. As is clear from FIG. 6, in the thin film piezoelectric vibrator having the structure shown in FIG. When the thin films above and below the piezoelectric thin film are thickened such that /t > 0.2, the electromechanical coupling coefficient k 2 of the fundamental vibration rapidly decreases as shown in Fig. 2 in the conventional structure, but in the structure shown in Fig. 3. It has the characteristic that it decreases very slowly. Increasing the thickness of the thin films above and below the piezoelectric thin film, for example, t'/t > 0.2, increases the mechanical strength of the vibrator especially at frequencies above 300 MHz, where a thin vibrator is required. In particular, the use of a silicon film is advantageous in that it further increases the acoustic quality factor Q of the vibrator. However, the thin film piezoelectric vibrator having the structure shown in FIG. As a result of these features, even when the thickness of the thin films above and below the piezoelectric thin film is increased, it is possible to realize a thin film piezoelectric vibrator that has a large electromechanical coupling coefficient for fundamental vibrations and has small unnecessary responses due to higher-order vibrations. Furthermore, even when the thin films above and below the piezoelectric thin film are thin, fourth-order high-order vibrations are strongly excited in the conventional structure, whereas in the structure shown in FIG. 3 according to the present invention, fourth-order high-order vibrations is completely suppressed. Particularly in the vicinity of t'/t~0.33 in FIG. 6, the electromechanical coupling coefficients of the third and fifth higher-order vibrations are both small, and the electromechanical coupling coefficient of the fundamental vibration is maximum. Therefore, even when the thin films above and below the piezoelectric thin film are thin, it is possible to realize a thin film piezoelectric vibrator that has a large electromechanical coupling coefficient for fundamental vibrations and a small unnecessary response due to higher order vibrations.
以上のように、本発明に従えば基本振動の電気
機械結合係数が大きく、高次振動による不要応答
の小さい薄膜圧電振動子が実現でき、したがつて
本発明の薄膜圧電振動子を用いることにより高周
波側の不要応答が小さく、広い比帯域幅のフイル
タ及び制御範囲の広い発振器を提供することがで
きる。 As described above, according to the present invention, it is possible to realize a thin film piezoelectric vibrator with a large electromechanical coupling coefficient for fundamental vibrations and a small unnecessary response due to higher order vibrations. Therefore, by using the thin film piezoelectric vibrator of the present invention, It is possible to provide a filter with a small unnecessary response on the high frequency side, a wide fractional bandwidth, and an oscillator with a wide control range.
以下実施例に従つて本発明を具体的に説明す
る。 The present invention will be specifically described below with reference to Examples.
実施例 １
表面が（100）面であるようなシリコン基板に
スパツタ法を用いて0.75μｍのSiO2薄膜を形成し
た。SiO2薄膜上にCrを下地としてAuを蒸着した
後、フオトリグラフイにより部分電極を形成し、
次にスパツタリング法を用いて5μｍのZnO薄膜を
形成した。さらにZnO薄膜の上にリフトオフによ
つてAlの部分電極を形成した後、スパツタリン
グ法を用いて0.75μｍのSiO2薄膜を形成した。次
にシリコン基板の裏面に形成したSi3N4薄膜をマ
スクとした振動部位にあたるシリコン基板をエチ
レンジアミン、ピロカエコール及び水からなるエ
ツチング液を用いてエツチングし、空孔を形成し
た。上記の工程によつて第３図の構造の薄膜圧電
振動子を製造した。この薄膜圧電振動子のインピ
ーダンス特性は第７図のようであり、インピーダ
ンス特性から求めた基本振動の電気機械結合係数
k2は第６図の値に一致し、0.08であつた。また第
５図からわかるように、偶数次の高次振動は励振
されず、第３次及び第５次の高次振動が非常に小
さく励振されるのみであつた。Example 1 A 0.75 μm SiO 2 thin film was formed on a silicon substrate having a (100) surface by sputtering. After depositing Au on the SiO 2 thin film using Cr as the base, partial electrodes were formed by photolithography.
Next, a 5 μm thick ZnO thin film was formed using a sputtering method. Furthermore, after forming a partial electrode of Al on the ZnO thin film by lift-off, a 0.75 μm SiO 2 thin film was formed using a sputtering method. Next, using the Si 3 N 4 thin film formed on the back surface of the silicon substrate as a mask, the silicon substrate corresponding to the vibration site was etched using an etching solution consisting of ethylenediamine, pirocaechol, and water to form holes. A thin film piezoelectric vibrator having the structure shown in FIG. 3 was manufactured by the above steps. The impedance characteristics of this thin film piezoelectric vibrator are shown in Figure 7, and the electromechanical coupling coefficient of fundamental vibration determined from the impedance characteristics.
k 2 was 0.08, matching the value in Figure 6. Further, as can be seen from FIG. 5, even-numbered higher-order vibrations were not excited, and third- and fifth-order higher-order vibrations were only excited to a very small extent.
実施例 ２
表面が（100）面であるようなシリコン基板に
ホウ素を1020／cmの濃度にドープしたシリコン薄
膜を21.2μｍの厚さにエピタキシヤル成長させた。
このシリコン薄膜の上に実施例１と同様の工程で
Au／Cr電極、厚さ5μｍのZnO薄膜、Al電極を順
に形成し、さらにスパツタリング法を用いて1.5μ
ｍのSiO2薄膜を形成した。シリコン、SiO2の音
速はそれぞれ8430ｍ／ｓ、5960ｍ／ｓであり、し
たがつてシリコン薄膜の厚さに対するSiO2薄膜
の厚さの比は音速の比0.71に等しい。次にシリコ
ン基板の裏面に形成したSi3N4薄膜をマスクとし
て振動部位にあたるシリコン基板をエチレンジア
ミン、ピロカテコール及び水からなるエツチング
液によつて除去し空孔を形成した。上記のような
工程によつて第３図の構造の薄膜圧電振動子を製
造した。この薄膜圧電振動子のインピーダンス特
性は第８図のようであり、インピーダンス特性か
ら求めた基本振動の電気機械結合係数k2は第６図
の値に一致し、0.077であつた。また第８図から
わかるように偶数次の高次振動はまつたく例振さ
れず、第５次の高次振動が小さく例振され、第３
次の高次金銅は例振されるが極めて小さい。Example 2 A silicon thin film doped with boron at a concentration of 10 20 /cm was epitaxially grown on a silicon substrate having a (100) surface to a thickness of 21.2 μm.
On this silicon thin film, the same process as in Example 1 was applied.
Au/Cr electrodes, 5 μm thick ZnO thin film, and Al electrodes were formed in this order, and then sputtering was used to form a 5 μm thick ZnO thin film.
A SiO 2 thin film of m was formed. The sound speeds of silicon and SiO 2 are 8430 m/s and 5960 m/s, respectively, so the ratio of the thickness of the SiO 2 thin film to the thickness of the silicon thin film is equal to the ratio of the sound speed of 0.71. Next, using the Si 3 N 4 thin film formed on the back surface of the silicon substrate as a mask, the silicon substrate corresponding to the vibration site was removed using an etching solution consisting of ethylenediamine, pyrocatechol, and water to form holes. A thin film piezoelectric vibrator having the structure shown in FIG. 3 was manufactured through the steps described above. The impedance characteristics of this thin film piezoelectric vibrator are as shown in FIG. 8, and the electromechanical coupling coefficient k 2 of fundamental vibration determined from the impedance characteristics was 0.077, which corresponded to the value shown in FIG. 6. Furthermore, as can be seen from Figure 8, the even-numbered higher-order vibrations are not immediately instantiated, the fifth-order higher-order vibrations are slightly instantiated, and the third
The next higher-order gold-bronze is an example, but it is extremely small.
以上のように本発明に従えば、基本振動の電気
機械結合係数が大きく高次振動による不要応答が
小さいという実用極めて重要な特長を有する薄膜
圧電振動子が実現でき、したがつて本発明の薄膜
圧電振動子を使用することにより高周波側での高
次振動による不要応答が小さく、広い比帯域幅の
フイルタ及び制御範囲の広い発振器を提供でき
る。 As described above, according to the present invention, it is possible to realize a thin film piezoelectric vibrator having extremely important practical features such as a large electromechanical coupling coefficient of fundamental vibrations and a small unnecessary response due to higher order vibrations. By using a piezoelectric vibrator, unnecessary responses due to high-order vibrations on the high frequency side are small, and a filter with a wide fractional bandwidth and an oscillator with a wide control range can be provided.
第１図は従来の薄膜圧電振動子の構造を示す断
面図であり、１１はシリコン、水晶などからなる
基板、１２はエツチングによつて基板に形成した
空孔、１３は薄膜部材、１４は圧電薄膜、１５，
１６は対向する電極である。第２図は第１図の構
造の薄膜圧電振動子の電気機械結合係数k2の理論
曲線を示す図である。図中の曲線に記した数字は
振動の次数を示す。第３図は本発明の薄膜圧電振
動子の構造を示す断面図であり、３１はシリコ
ン、水晶などからなる基板、３２はエツチングに
よつて基板に形成した空孔、３３及び３４は薄膜
部材、３５は圧電薄膜、３６，３７は対向する電
極である。第４図は第３図の構造の薄膜圧電振動
子について薄膜部材３４の厚さt34と薄膜部材３
３の厚さt33の比t34／t33に対する電気機械結合係
数k2の変化を示す図である。図中の曲線に記した
数字は振動の次数を示す。第５図は本発明の薄膜
圧電振動子の振動部位における応力分布した図で
ある。図中のＡ，Ｂ，Ｃ，Ｄにおいてイ，ロ，
ハ，ニはそれぞれ基本振動、第２次、第３次、第
４次の振動の応力分布である。図において４１は
圧電薄膜、４２，４３は薄膜部材、４４，４５は
電極である。第６図は本発明の薄膜圧電振動子の
電気機械結合係数k2の理論曲線を示す図。図中の
曲線に記した数字は振動の次数を示す。第７図、
第８図はそれぞれ本発明の実施例１、実施例２の
薄膜圧電振動子のインピーダンス特性を示した図
である。横軸はＭHz単位で表わした周波数であ
り、縦軸はデシベル単位で表わしたインピーダン
スの相対値である。
FIG. 1 is a cross-sectional view showing the structure of a conventional thin film piezoelectric vibrator, in which 11 is a substrate made of silicon, crystal, etc., 12 is a hole formed in the substrate by etching, 13 is a thin film member, and 14 is a piezoelectric thin film, 15,
16 is an opposing electrode. FIG. 2 is a diagram showing a theoretical curve of the electromechanical coupling coefficient k 2 of the thin film piezoelectric vibrator having the structure shown in FIG. The numbers written on the curves in the figure indicate the order of vibration. FIG. 3 is a sectional view showing the structure of the thin film piezoelectric vibrator of the present invention, in which 31 is a substrate made of silicon, crystal, etc., 32 is a hole formed in the substrate by etching, 33 and 34 are thin film members, 35 is a piezoelectric thin film, and 36 and 37 are opposing electrodes. FIG. 4 shows the thickness t 34 of the thin film member 34 and the thin film member 3 for the thin film piezoelectric vibrator having the structure shown in FIG.
3 is a diagram showing the change in the electromechanical coupling coefficient k 2 with respect to the ratio t 34 /t 33 of the thickness t 33 of No. 3. FIG. The numbers written on the curves in the figure indicate the order of vibration. FIG. 5 is a diagram showing the stress distribution at the vibration site of the thin film piezoelectric vibrator of the present invention. A, B, B in A, B, C, D in the figure.
C and D are stress distributions of fundamental vibration, second-order, third-order, and fourth-order vibration, respectively. In the figure, 41 is a piezoelectric thin film, 42 and 43 are thin film members, and 44 and 45 are electrodes. FIG. 6 is a diagram showing a theoretical curve of the electromechanical coupling coefficient k 2 of the thin film piezoelectric vibrator of the present invention. The numbers written on the curves in the figure indicate the order of vibration. Figure 7,
FIG. 8 is a diagram showing the impedance characteristics of the thin film piezoelectric vibrators of Example 1 and Example 2 of the present invention, respectively. The horizontal axis is the frequency expressed in MHz, and the vertical axis is the relative value of impedance expressed in decibels.
Claims (1)
極、圧電薄膜、電極、無機材料の薄膜部材の順で
形成されている多層構造を有する薄膜圧電振動子
であつて、圧電薄膜をはさんでその上下に形成す
る該無機材料の薄膜部材は等しい厚さを有する同
一の材料からなり、これら薄膜部材の厚さの合計
が圧電薄膜の厚さの0.2倍より大きいことを特徴
とする薄膜圧電振動子。 ２ 無機材料の薄膜部材とこの薄膜部材の上に電
極、圧電薄膜、電極、無機材料の薄膜部材の順で
形成されている多層構造を有する薄膜圧電振動子
であつて、圧電薄膜をはさんでその上下に形成す
る該無機材料の薄膜部材はそれぞれ異なる材料か
らなり、しかも上下の該薄膜部材の厚さの比はそ
れぞれの薄膜部材の中の音速の比に等しいことを
特徴とする薄膜圧電振動子。[Scope of Claims] 1. A thin film piezoelectric vibrator having a multilayer structure including a thin film member made of an inorganic material, an electrode, a piezoelectric thin film, an electrode, and a thin film member made of an inorganic material formed on the thin film member in this order, The thin film members of the inorganic material formed above and below the piezoelectric thin film are made of the same material and have the same thickness, and the total thickness of these thin film members is greater than 0.2 times the thickness of the piezoelectric thin film. Characteristic thin film piezoelectric vibrator. 2. A thin film piezoelectric vibrator having a multilayer structure in which a thin film member made of an inorganic material, an electrode, a piezoelectric thin film, an electrode, and a thin film member made of an inorganic material are formed in this order on the thin film member, with the piezoelectric thin film sandwiched therebetween. Thin film piezoelectric vibration characterized in that the thin film members of the inorganic material formed on the upper and lower sides are respectively made of different materials, and the ratio of the thicknesses of the upper and lower thin film members is equal to the ratio of sound velocities in the respective thin film members. Child.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12705781A JPS5829211A (en) | 1981-08-13 | 1981-08-13 | Thin film piezoelectric oscillator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12705781A JPS5829211A (en) | 1981-08-13 | 1981-08-13 | Thin film piezoelectric oscillator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5829211A JPS5829211A (en) | 1983-02-21 |
| JPH0356013B2 true JPH0356013B2 (en) | 1991-08-27 |
Family
ID=14950523
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12705781A Granted JPS5829211A (en) | 1981-08-13 | 1981-08-13 | Thin film piezoelectric oscillator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5829211A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6068711A (en) * | 1983-09-26 | 1985-04-19 | Toshiba Corp | Piezoelectric thin film resonator |
| JPS60189307A (en) * | 1984-03-09 | 1985-09-26 | Toshiba Corp | Piezoelectric thin film resonator and its manufacture |
| US6515402B2 (en) * | 2001-01-24 | 2003-02-04 | Koninklijke Philips Electronics N.V. | Array of ultrasound transducers |
| JP2004147246A (en) * | 2002-10-28 | 2004-05-20 | Matsushita Electric Ind Co Ltd | Piezoelectric vibrator, filter using the same and method of adjusting piezoelectric vibrator |
| JP4978210B2 (en) * | 2007-01-25 | 2012-07-18 | セイコーエプソン株式会社 | Manufacturing method of bulk acoustic vibrator |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4928795A (en) * | 1972-07-14 | 1974-03-14 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5140771Y2 (en) * | 1971-10-08 | 1976-10-05 | ||
| JPS5399976U (en) * | 1977-01-17 | 1978-08-12 |
-
1981
- 1981-08-13 JP JP12705781A patent/JPS5829211A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4928795A (en) * | 1972-07-14 | 1974-03-14 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5829211A (en) | 1983-02-21 |
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