JP2008147833A - Piezoelectric thin film device - Google Patents

Piezoelectric thin film device Download PDF

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JP2008147833A
JP2008147833A JP2006330450A JP2006330450A JP2008147833A JP 2008147833 A JP2008147833 A JP 2008147833A JP 2006330450 A JP2006330450 A JP 2006330450A JP 2006330450 A JP2006330450 A JP 2006330450A JP 2008147833 A JP2008147833 A JP 2008147833A
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thin film
piezoelectric thin
piezoelectric
surface electrode
resonator
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JP5020612B2 (en
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Tomoyoshi Oi
知義 多井
Shoichiro Yamaguchi
省一郎 山口
Masahiro Sakai
正宏 坂井
Yukihisa Osugi
幸久 大杉
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NGK Insulators Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To suppress secondary resonance of a piezoelectric thin film resonator. <P>SOLUTION: A piezoelectric thin film resonator 1 has a cavity forming film 13 formed on the lower surface of a fixed region 912 of a vibration laminate 18 comprising a lower-surface electrode 14, a piezoelectric body thin film 15, and an upper-surface electrode 16 lamined therein and a support 17 comprising a support substrate 11, an adhesion layer 12, and the cavity forming film 13 laminated therein supports the vibration laminate 18 at an outer edge of a free vibration region 911. In the lower surface of the piezoelectric thin film 15, digged portions 156 making the piezoelectric body thin film 15 thin are formed. The digged portions 156 are formed at the outer edge of the free vibration region 911 along the outer hull of the free vibration region 911. The digged portions 156 make the piezoelectric body thin film 15 thin to reduce an extreme decrease in resonance frequency of a fixed region 912 supported by the support 17, thereby serving to suppress the secondary resonance of the piezoelectric thin film resonator 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、単数又は複数の圧電薄膜共振子を含む圧電薄膜デバイスに関する。   The present invention relates to a piezoelectric thin film device including one or more piezoelectric thin film resonators.

図２３は、従来の圧電薄膜共振子８の概略構成を示す断面図である。図２３に示すように、圧電薄膜共振子８は、圧電体薄膜８６の下面及び上面にそれぞれ下面電極８５及び上面電極８７を形成し、下面電極８５、圧電体薄膜８６及び上面電極８７を積層した振動積層体８４を基板８２及び下地膜８３で支持した構造を有している。圧電薄膜共振子８においては、振動の励振を阻害しないようにするため、自由振動領域８１の下方にキャビティ８０が形成されている（特許文献１）。   FIG. 23 is a cross-sectional view showing a schematic configuration of a conventional piezoelectric thin film resonator 8. As shown in FIG. 23, in the piezoelectric thin film resonator 8, a lower electrode 85 and an upper electrode 87 are formed on the lower surface and the upper surface of the piezoelectric thin film 86, respectively, and the lower electrode 85, the piezoelectric thin film 86, and the upper electrode 87 are stacked. The vibration laminate 84 is supported by a substrate 82 and a base film 83. In the piezoelectric thin film resonator 8, a cavity 80 is formed below the free vibration region 81 so as not to inhibit excitation of vibration (Patent Document 1).

特開２００２−３４４２７９号公報JP 2002-344279 A

しかし、従来の圧電薄膜共振子では、自由振動領域の外縁における振動積層体の支持に起因する副共振が問題となっていた。   However, in the conventional piezoelectric thin film resonator, the secondary resonance caused by the support of the vibration laminate at the outer edge of the free vibration region has been a problem.

本発明は、この問題を解決するためになされたもので、圧電薄膜共振子の副共振を抑制することを目的とする。   The present invention has been made to solve this problem, and an object thereof is to suppress sub-resonance of a piezoelectric thin film resonator.

上記課題を解決するため、請求項１の発明は、単数又は複数の圧電薄膜共振子を含む圧電薄膜デバイスであって、圧電体薄膜と、前記圧電体薄膜を挟んで対向する電極と、前記圧電体薄膜及び前記電極を積層した振動積層体を自由振動領域の外縁において支持する支持体とを備え、前記圧電体薄膜を薄肉化する掘り込みが前記自由振動領域の外縁に前記自由振動領域の外郭に沿って形成されている。   In order to solve the above-mentioned problems, the invention of claim 1 is a piezoelectric thin film device including one or a plurality of piezoelectric thin film resonators, wherein the piezoelectric thin film, electrodes facing each other with the piezoelectric thin film interposed therebetween, and the piezoelectric And a support for supporting the vibration laminated body in which the thin film and the electrode are laminated at the outer edge of the free vibration region, and a digging for thinning the piezoelectric thin film is formed on the outer edge of the free vibration region. It is formed along.

請求項２の発明は、前記掘り込みが前記自由振動領域を囲む請求項１に記載の圧電薄膜デバイスである。   The invention according to claim 2 is the piezoelectric thin film device according to claim 1, wherein the digging surrounds the free vibration region.

請求項３の発明は、前記掘り込みの深さが前記圧電体薄膜の膜厚の１％以上２０％以下である請求項１又は請求項２に記載の圧電薄膜デバイスである。   A third aspect of the invention is the piezoelectric thin film device according to the first or second aspect, wherein the digging depth is not less than 1% and not more than 20% of the film thickness of the piezoelectric thin film.

請求項４の発明は、前記掘り込みの幅が１μｍ以上１０μｍ以下である請求項１ないし請求項３のいずれかに記載の圧電薄膜デバイスである。   A fourth aspect of the present invention is the piezoelectric thin film device according to any one of the first to third aspects, wherein the digging width is 1 μm or more and 10 μm or less.

本発明によれば、支持体に支持されている自由振動領域の外縁の共振周波数の極端な低下を緩和することができ、圧電薄膜共振子の副共振を抑制することができる。   According to the present invention, it is possible to mitigate an extreme decrease in the resonance frequency of the outer edge of the free vibration region supported by the support, and it is possible to suppress the sub-resonance of the piezoelectric thin film resonator.

請求項２ないし請求項４の発明によれば、圧電薄膜共振子の副共振を特に効果的に抑制することができる。   According to the second to fourth aspects of the invention, the sub-resonance of the piezoelectric thin film resonator can be particularly effectively suppressed.

以下では、単独の圧電薄膜共振子（ＦＢＡＲ；Film Bulk Acoustic Resonator）を例として、本発明の圧電薄膜デバイスの望ましい実施形態について説明する。しかし、以下で説明する実施形態は、本発明の圧電薄膜デバイスが単独の圧電薄膜共振子のみに限定されることを意味するものではない。すなわち、本発明における圧電薄膜デバイスとは、一般的に言えば、単数又は複数の圧電薄膜共振子を含む圧電薄膜デバイス全般を意味しており、単一の圧電薄膜共振子を含む発振子及びトラップ等並びに複数の圧電薄膜共振子を含むフィルタ、デュプレクサ、トリプレクサ及びトラップ等を包含している。ここで、圧電薄膜共振子とは、支持なくしては自重に耐え得ない薄膜に圧電的に励振されるバルク弾性波による電気的な応答を利用した共振子である。   In the following, a preferred embodiment of the piezoelectric thin film device of the present invention will be described using a single piezoelectric thin film resonator (FBAR) as an example. However, the embodiments described below do not mean that the piezoelectric thin film device of the present invention is limited to a single piezoelectric thin film resonator. That is, the piezoelectric thin film device in the present invention generally means all piezoelectric thin film devices including one or a plurality of piezoelectric thin film resonators, and an oscillator and a trap including a single piezoelectric thin film resonator. And filters including a plurality of piezoelectric thin film resonators, duplexers, triplexers, traps, and the like. Here, the piezoelectric thin film resonator is a resonator using an electrical response by a bulk acoustic wave that is piezoelectrically excited by a thin film that cannot withstand its own weight without support.

＜１ 第１実施形態＞
図１、図２は、本発明の第１実施形態に係る圧電薄膜共振子１の概略構成を示す模式図であり、図１は、圧電薄膜共振子１の斜視図、図２は、図１のＩＩ−ＩＩの切断線における圧電薄膜共振子１の断面図となっている。図１には、説明の便宜上、左右方向をＸ軸方向、前後方向をＹ軸方向、上下方向をＺ軸方向とするＸＹＺ直交座標系が定義されている。圧電薄膜共振子１は、圧電体薄膜１５に励振される厚み縦振動による電気的な応答を利用した共振子となっている。 <1 First Embodiment>
1 and 2 are schematic views showing a schematic configuration of the piezoelectric thin film resonator 1 according to the first embodiment of the present invention. FIG. 1 is a perspective view of the piezoelectric thin film resonator 1, and FIG. It is sectional drawing of the piezoelectric thin film resonator 1 in the cutting line of II-II. For convenience of explanation, FIG. 1 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction. The piezoelectric thin film resonator 1 is a resonator using an electrical response due to thickness longitudinal vibration excited by the piezoelectric thin film 15.

図１、図２に示すように、圧電薄膜共振子１は、支持基板１１の上に、接着層１２、キャビティ形成膜１３、下面電極１４、圧電体薄膜１５及び上面電極１６（１６１，１６２）をこの順序で積層した構造を有している。圧電薄膜共振子１の製造にあたっては、単独で自重に耐え得る圧電体基板を除去加工することにより圧電体薄膜１５を得ているが、除去加工によって得られる圧電体薄膜１５は単独で自重に耐え得ない。このため、圧電薄膜共振子１の製造にあたっては、除去加工に先立って、キャビティ形成膜１３及び下面電極１４を形成した圧電体基板を支持基板１１にあらかじめ接着している。   As shown in FIGS. 1 and 2, the piezoelectric thin film resonator 1 includes an adhesive layer 12, a cavity forming film 13, a lower surface electrode 14, a piezoelectric thin film 15, and an upper surface electrode 16 (161, 162) on a support substrate 11. Are stacked in this order. When the piezoelectric thin film resonator 1 is manufactured, the piezoelectric thin film 15 is obtained by removing the piezoelectric substrate that can withstand its own weight. However, the piezoelectric thin film 15 obtained by the removing process can withstand its own weight. I don't get it. For this reason, when the piezoelectric thin film resonator 1 is manufactured, the piezoelectric substrate on which the cavity forming film 13 and the lower surface electrode 14 are formed is bonded to the support substrate 11 in advance prior to the removal processing.

＜１．１ 支持基板１１＞
支持基板１１は、圧電薄膜共振子１の製造途上で圧電体基板を除去加工するときに、キャビティ形成膜１３及び下面電極１４が下面に形成された圧電体基板を接着層１２を介して支持する役割を有している。加えて、支持基板１１は、圧電薄膜共振子１の製造後に、キャビティ形成膜１３及び下面電極１４が下面に形成され、上面電極１６が上面に形成された圧電体薄膜１５を接着層１２を介して支持する役割も有している。したがって、支持基板１１には、圧電体基板を除去加工するときに加わる力に耐え得ることと、圧電薄膜共振子１の製造後にも強度が低下しないこととが要請される。 <1.1 Support substrate 11>
The support substrate 11 supports the piezoelectric substrate on which the cavity forming film 13 and the lower electrode 14 are formed on the lower surface via the adhesive layer 12 when the piezoelectric substrate is removed during the manufacturing process of the piezoelectric thin film resonator 1. Have a role. In addition, after the piezoelectric thin film resonator 1 is manufactured, the support substrate 11 has the piezoelectric thin film 15 having the cavity forming film 13 and the lower surface electrode 14 formed on the lower surface and the upper surface electrode 16 formed on the upper surface via the adhesive layer 12. Have a supporting role. Accordingly, the support substrate 11 is required to be able to withstand the force applied when the piezoelectric substrate is removed, and not to decrease in strength even after the piezoelectric thin film resonator 1 is manufactured.

支持基板１１の材料及び厚さは、このような要請を満足するように、適宜選択することができる。ただし、支持基板１１の材料を、圧電体薄膜１５を構成する圧電材料と近い熱膨張率、より望ましくは、圧電体薄膜１５を構成する圧電材料と同じ熱膨張率を有する材料、例えば、圧電体薄膜１５を構成する圧電材料と同じ材料とすれば、圧電薄膜共振子１の製造途上において、熱膨張率の差に起因する反りや破損を抑制することができ、圧電薄膜共振子１の製造後において、熱膨張率の差に起因する特性変動や破損を抑制することができる。なお、熱膨張率に異方性がある材料を用いる場合、支持基板１１と圧電体薄膜１５とで各方向の熱膨張率がともに同じとなるように配慮することが望ましく、支持基板１１と圧電体薄膜１５とに同じ圧電材料を用いる場合、支持基板１１と圧電体薄膜１５とで結晶方位を一致させることが望ましい。   The material and thickness of the support substrate 11 can be appropriately selected so as to satisfy such requirements. However, the material of the support substrate 11 is a material having a thermal expansion coefficient close to that of the piezoelectric material constituting the piezoelectric thin film 15, more preferably a material having the same thermal expansion coefficient as the piezoelectric material constituting the piezoelectric thin film 15, for example, a piezoelectric body If the same material as the piezoelectric material constituting the thin film 15 is used, warping and breakage due to the difference in thermal expansion coefficient can be suppressed during the manufacturing of the piezoelectric thin film resonator 1. Thus, characteristic fluctuations and breakage due to the difference in thermal expansion coefficient can be suppressed. When a material having an anisotropic thermal expansion coefficient is used, it is desirable to consider that the thermal expansion coefficient in each direction is the same between the support substrate 11 and the piezoelectric thin film 15. When the same piezoelectric material is used for the body thin film 15, it is desirable that the crystal orientations of the support substrate 11 and the piezoelectric thin film 15 are matched.

＜１．２ 接着層１２＞
接着層１２は、圧電薄膜共振子１の製造途上で圧電体基板を除去加工するときに、キャビティ形成膜１３及び下面電極１４が下面に形成された圧電体基板を支持基板１１に接着固定する役割を有している。加えて、接着層１２は、圧電薄膜共振子１の製造後に、キャビティ形成膜１３及び下面電極１４が下面に形成され、上面電極１６が上面に形成された圧電体薄膜１５を支持基板１１に接着固定する役割も有している。したがって、接着層１２には、圧電体基板を除去加工するときに加わる力に耐え得ることと、圧電薄膜共振子１の製造後にも接着力が低下しないこととが要請される。 <1.2 Adhesive layer 12>
The adhesive layer 12 serves to bond and fix the piezoelectric substrate on which the cavity forming film 13 and the lower surface electrode 14 are formed on the lower surface to the support substrate 11 when the piezoelectric substrate is removed during the manufacturing of the piezoelectric thin film resonator 1. have. In addition, after the piezoelectric thin film resonator 1 is manufactured, the adhesive layer 12 bonds the piezoelectric thin film 15 having the cavity forming film 13 and the lower electrode 14 formed on the lower surface and the upper electrode 16 formed on the upper surface to the support substrate 11. It also has a fixing role. Therefore, the adhesive layer 12 is required to be able to withstand the force applied when the piezoelectric substrate is removed and that the adhesive force does not decrease even after the piezoelectric thin film resonator 1 is manufactured.

このような要請を満足する接着層１２の望ましい例としては、有機接着剤、望ましくは、充填効果を有し、接着対象が完全に平坦ではなくても十分な接着力を発揮するエポキシ接着剤（熱硬化性を利用するエポキシ樹脂の接着剤）やアクリル接着剤（光硬化性及び熱硬化性を併用するアクリル樹脂の接着剤）により形成された接着層１２を挙げることができる。このような樹脂を採用することにより、支持基板１１と圧電体基板との間に期待しない空隙が生じることを防止し、当該空隙により圧電体基板の除去加工時にクラック等が発生することを防止可能である。ただし、このことは、これ以外の接着層１２によって支持基板１１と圧電体薄膜１５とが接着固定されることを妨げるものではない。   Desirable examples of the adhesive layer 12 satisfying such requirements include an organic adhesive, preferably an epoxy adhesive having a filling effect and exhibiting sufficient adhesive force even if the object to be bonded is not completely flat ( Examples thereof include an adhesive layer 12 formed of an epoxy resin adhesive using thermosetting) and an acrylic adhesive (an acrylic resin adhesive using both photo-curing property and thermosetting property). By adopting such a resin, it is possible to prevent an unexpected gap from being formed between the support substrate 11 and the piezoelectric substrate, and to prevent a crack or the like from being generated due to the void during the removal processing of the piezoelectric substrate. It is. However, this does not prevent the support substrate 11 and the piezoelectric thin film 15 from being bonded and fixed by the other adhesive layer 12.

＜１．３ キャビティ形成膜１３＞
キャビティ形成膜１３は、絶縁材料を成膜することにより得られた絶縁体膜である。圧電薄膜共振子１では、下面電極１４、圧電体薄膜１５及び上面電極１６を積層した振動積層体１８の固定領域９１２の下面にキャビティ形成膜１３が形成され、支持基板１１、接着層１２及びキャビティ形成膜１３を積層した支持体１７が自由振動領域９１１の外縁において振動積層体１８を支持している。このようなスペーサしての役割を有するキャビティ形成膜１３により、振動積層体１８の自由振動領域９１１が支持基板１１と干渉しなくなり、自由振動領域９１１における振動の励振が阻害されることがなくなる。 <1.3 Cavity Formation Film 13>
The cavity forming film 13 is an insulator film obtained by forming an insulating material. In the piezoelectric thin film resonator 1, the cavity forming film 13 is formed on the lower surface of the fixed region 912 of the vibration laminate 18 in which the lower electrode 14, the piezoelectric thin film 15 and the upper electrode 16 are laminated, and the support substrate 11, the adhesive layer 12, and the cavity are formed. A support 17 on which the formation film 13 is laminated supports the vibration laminate 18 at the outer edge of the free vibration region 911. Due to the cavity forming film 13 serving as such a spacer, the free vibration region 911 of the vibration laminate 18 does not interfere with the support substrate 11, and vibration excitation in the free vibration region 911 is not hindered.

キャビティ形成膜１３を構成する絶縁材料は、特に制限されないが、二酸化ケイ素（SiO2）等の絶縁材料から選択することが望ましい。 The insulating material constituting the cavity forming film 13 is not particularly limited, but is preferably selected from insulating materials such as silicon dioxide (SiO 2 ).

＜１．４ 圧電体薄膜１５＞
圧電体薄膜１５は、圧電体基板を除去加工することにより得られる。より具体的には、圧電体薄膜１５は、単独で自重に耐え得る厚み（例えば、５０μｍ以上）を有する圧電体基板を、単独で自重に耐え得ない膜厚（例えば、１０μｍ以下）まで除去加工で薄肉化することにより得られる。 <1.4 Piezoelectric thin film 15>
The piezoelectric thin film 15 is obtained by removing the piezoelectric substrate. More specifically, the piezoelectric thin film 15 removes a piezoelectric substrate having a thickness (for example, 50 μm or more) that can withstand its own weight to a thickness (for example, 10 μm or less) that cannot withstand its own weight. It can be obtained by thinning.

圧電体薄膜１５を構成する圧電材料としては、所望の圧電特性を有する圧電材料を選択することができるが、水晶（SiO2）、ニオブ酸リチウム(LiNbO3）、タンタル酸リチウム（LiTaO3）、四ホウ酸リチウム（Li2B4O7）、酸化亜鉛（ZnO）、ニオブ酸カリウム（KNbO3）及びランガサイト（La3Ga3SiO14）等の粒界を含まない単結晶材料を選択することが望ましい。圧電体薄膜１５を構成する圧電材料として単結晶材料を用いることにより、圧電体薄膜１５の電気機械結合係数及び機械的品質係数を向上することができるからである。 As a piezoelectric material constituting the piezoelectric thin film 15, a piezoelectric material having desired piezoelectric characteristics can be selected, but quartz (SiO 2 ), lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ), Select single crystal materials that do not contain grain boundaries such as lithium tetraborate (Li 2 B 4 O 7 ), zinc oxide (ZnO), potassium niobate (KNbO 3 ) and langasite (La 3 Ga 3 SiO 14 ) It is desirable. This is because by using a single crystal material as the piezoelectric material constituting the piezoelectric thin film 15, the electromechanical coupling coefficient and the mechanical quality factor of the piezoelectric thin film 15 can be improved.

また、圧電体薄膜１５における結晶方位も、所望の圧電特性を有する結晶方位を選択することができる。ここで、圧電体薄膜１５における結晶方位は、圧電薄膜共振子１の共振周波数や反共振周波数の温度特性が良好となる結晶方位とすることが望ましく、周波数温度係数が「０」となる結晶方位とすることがさらに望ましい。   In addition, as the crystal orientation in the piezoelectric thin film 15, a crystal orientation having desired piezoelectric characteristics can be selected. Here, the crystal orientation in the piezoelectric thin film 15 is preferably a crystal orientation in which the temperature characteristics of the resonance frequency and antiresonance frequency of the piezoelectric thin film resonator 1 are favorable, and the crystal orientation in which the frequency temperature coefficient is “0”. Is more desirable.

圧電体基板の除去加工は、切削、研削及び研磨等の機械加工並びにエッチング等の化学加工等により行う。ここで、複数の除去加工方法を組み合わせ、加工速度が速い除去加工方法から、加工対象に生じる加工変質が小さい除去加工方法へと除去加工方法を段階的に切り替えながら圧電体基板を除去加工すれば、高い生産性を維持しつつ、圧電体薄膜１５の品質を向上し、圧電薄膜共振子１の特性を向上することができる。例えば、圧電体基板を固定砥粒に接触させて削る研削及び圧電体基板を遊離砥粒に接触させて削る研磨を順次行った後に、当該研磨によって圧電体基板に生じた加工変質層を仕上げ研磨により除去するようにすれば、圧電体基板を削る速度が早くなり、圧電薄膜共振子１の生産性を向上することができるとともに、圧電体薄膜１５の品質を向上することにより、圧電薄膜共振子１の特性を向上することができる。なお、圧電体基板の除去加工のより具体的な方法については、後述する実施例において説明する。   The removal processing of the piezoelectric substrate is performed by mechanical processing such as cutting, grinding and polishing, and chemical processing such as etching. Here, if a plurality of removal processing methods are combined and the piezoelectric substrate is removed while switching the removal processing method step by step from the removal processing method with a high processing speed to the removal processing method with a small process alteration occurring on the processing target. The quality of the piezoelectric thin film 15 can be improved and the characteristics of the piezoelectric thin film resonator 1 can be improved while maintaining high productivity. For example, after performing grinding in which a piezoelectric substrate is brought into contact with fixed abrasive grains and polishing in which a piezoelectric substrate is brought into contact with loose abrasive grains in order, a work-affected layer generated on the piezoelectric substrate by the polishing is finished and polished. If it removes by this, the speed at which the piezoelectric substrate is cut can be increased, the productivity of the piezoelectric thin film resonator 1 can be improved, and the quality of the piezoelectric thin film 15 can be improved. 1 characteristic can be improved. Note that a more specific method of removing the piezoelectric substrate will be described in an example described later.

このような圧電薄膜共振子１では、圧電体薄膜１５をスパッタリング等により成膜した場合と異なり、圧電体薄膜１５を構成する圧電材料や圧電体薄膜１５における結晶方位が下地の制約を受けないので、圧電体薄膜１５を構成する圧電材料や圧電体薄膜１５における結晶方位の選択の自由度が高くなっている。したがって、圧電薄膜共振子１では、所望の特性を実現することが容易になっている。   In such a piezoelectric thin film resonator 1, unlike the case where the piezoelectric thin film 15 is formed by sputtering or the like, the piezoelectric material constituting the piezoelectric thin film 15 and the crystal orientation in the piezoelectric thin film 15 are not restricted by the base. The degree of freedom in selecting the crystal orientation of the piezoelectric material constituting the piezoelectric thin film 15 and the piezoelectric thin film 15 is high. Therefore, the piezoelectric thin film resonator 1 can easily achieve desired characteristics.

この圧電体薄膜１５には、圧電体薄膜１５の上面と下面との間を貫通し、固定領域９１２において圧電体薄膜１５を挟んで対向する下面電極１４と上面電極１６２とを導通させるバイアホール１５５が形成されている。バイアホール１５５は、その内側面に成膜された導電体薄膜により下面電極１４と上面電極１６２とを短絡して直流的に導通させている。   The piezoelectric thin film 15 penetrates between the upper surface and the lower surface of the piezoelectric thin film 15, and a via hole 155 that connects the lower electrode 14 and the upper electrode 162 that face each other with the piezoelectric thin film 15 sandwiched in the fixed region 912. Is formed. The via hole 155 short-circuits the lower surface electrode 14 and the upper surface electrode 162 with a conductive thin film formed on the inner surface of the via hole 155 to make it conductive in a DC manner.

圧電体薄膜１５の下面には、圧電体薄膜１５を薄肉化する掘り込み（溝）１５６が形成されている。掘り込み１５６は、自由振動領域９１１の外縁に自由振動領域９１１の外郭に沿って形成されている。堀り込み１５６は、エッチング等により表面粗さや膜厚変動を超えて圧電体薄膜１５を薄肉化することにより形成する。掘り込み１５６は、キャビティ形成膜１３で埋められているが、キャビティ形成膜１３で埋めることなく空洞としてもよい。掘り込み１５６は、圧電体薄膜１５を薄肉化することにより、支持体１７に支持されている固定領域９１２の共振周波数の極端な低下を緩和し、圧電薄膜共振子１の副共振を抑制する役割を果たしている。換言すれば、掘り込み１５６は、自由振動領域９１１と固定領域９１２との境界が、横方向に伝播するバルク弾性波を全反射する固定端に近い状態となることを防止し、圧電薄膜共振子１の副共振を抑制する役割を果たしている。   A digging (groove) 156 for thinning the piezoelectric thin film 15 is formed on the lower surface of the piezoelectric thin film 15. The digging 156 is formed on the outer edge of the free vibration region 911 along the outline of the free vibration region 911. The digging 156 is formed by thinning the piezoelectric thin film 15 beyond the surface roughness and film thickness variation by etching or the like. The digging 156 is filled with the cavity forming film 13, but may be a cavity without being filled with the cavity forming film 13. The digging 156 reduces the resonance frequency of the fixed region 912 supported by the support 17 by reducing the thickness of the piezoelectric thin film 15 and suppresses the sub-resonance of the piezoelectric thin film resonator 1. Plays. In other words, the digging 156 prevents the boundary between the free vibration region 911 and the fixed region 912 from being close to the fixed end that totally reflects the bulk elastic wave propagating in the lateral direction, and the piezoelectric thin film resonator 1 plays the role of suppressing the secondary resonance.

係る役割を適切に果たすためには、掘り込み１５６の深さは、圧電体薄膜１５の膜厚の１％以上２０％以下であることが望ましく、１０％以上１５％以下がさらに望ましい。また、掘り込み１５６の幅は、１μｍ以上１０μｍ以下であることが望ましい。掘り込み１５６の深さ及び幅がこの範囲内であれば、副共振を特に効果的に抑制することができるからである。固定領域９１２に形成される掘り込み１５６による副共振の抑制には、自由振動領域９１１を加工する必要が無いので、自由振動領域９１１の機械的損傷に起因する主共振の共振特性の劣化を引き起こすことがないという利点もある。この点は、自由振動領域９１１の膜厚が薄く機械的損傷の影響を受けやすい圧電薄膜共振子１では、特に重要である。   In order to appropriately fulfill such a role, the depth of the digging 156 is preferably 1% or more and 20% or less of the film thickness of the piezoelectric thin film 15, and more preferably 10% or more and 15% or less. The width of the digging 156 is desirably 1 μm or more and 10 μm or less. This is because if the depth and width of the digging 156 are within this range, the sub-resonance can be particularly effectively suppressed. In order to suppress the sub-resonance due to the digging 156 formed in the fixed region 912, it is not necessary to process the free vibration region 911, which causes deterioration of the resonance characteristics of the main resonance due to mechanical damage in the free vibration region 911. There is also an advantage that there is nothing. This is particularly important in the piezoelectric thin film resonator 1 in which the free vibration region 911 is thin and easily affected by mechanical damage.

圧電体薄膜１５を上方から見た図３の平面図に示すように、掘り込み１５６は、自由振動領域９１１を囲むように形成することが最も望ましいが、途切れている部分があっても圧電薄膜共振子１の副共振を抑制する役割を果たすことは可能である。特に、自由振動領域９１１の形状が、長辺の長さが短辺の長さの２倍以上となる細長の矩形である場合には、自由振動領域９１１の長辺に沿ってのみ掘り込み１５６を形成しても、副共振の抑制効果をある程度得ることができる。   As shown in the plan view of FIG. 3 when the piezoelectric thin film 15 is viewed from above, the digging 156 is most preferably formed so as to surround the free vibration region 911. It is possible to play a role of suppressing the secondary resonance of the resonator 1. In particular, when the shape of the free vibration region 911 is an elongated rectangle whose long side is twice or more the length of the short side, the digging 156 is performed only along the long side of the free vibration region 911. Even if formed, a sub-resonance suppressing effect can be obtained to some extent.

＜１．５ 下面電極１４及び上面電極１６＞
下面電極１４及び上面電極１６は、それぞれ、圧電体薄膜１５の下面及び上面に導電材料を成膜することにより形成された導電体薄膜である。 <1.5 Lower electrode 14 and upper electrode 16>
The lower surface electrode 14 and the upper surface electrode 16 are conductor thin films formed by depositing a conductive material on the lower surface and the upper surface of the piezoelectric thin film 15, respectively.

下面電極１４及び上面電極１６を構成する導電材料は、特に制限されないが、アルミニウム（Al）、銀（Ag）、銅（Cu）、白金（Pt）、金（Au）、クロム（Cr）、ニッケル（Ni）、モリブデン（Mo）、タングステン(W)及びタンタル（Ta）等の金属から選択することが望ましい。もちろん、下面電極１４及び上面電極１６を構成する導電材料として合金を用いてもよい。また、複数種類の導電材料を重ねて成膜することにより、下面電極１４及び上面電極１６を形成してもよい。   The conductive material constituting the lower electrode 14 and the upper electrode 16 is not particularly limited, but aluminum (Al), silver (Ag), copper (Cu), platinum (Pt), gold (Au), chromium (Cr), nickel It is desirable to select from metals such as (Ni), molybdenum (Mo), tungsten (W) and tantalum (Ta). Of course, an alloy may be used as the conductive material constituting the lower electrode 14 and the upper electrode 16. Further, the lower electrode 14 and the upper electrode 16 may be formed by stacking a plurality of kinds of conductive materials.

図１、図２の他、下面電極１４及び上面電極１６を上方から見たパターンを示す図４の平面図に示すように、上面電極１６のうち、上面電極１６１は、対向領域９１３において、圧電体薄膜１５を挟んで下面電極１４と対向している。上面電極１６１は、対向領域９１３から左方へ引き出され、引き出された部分は、上面電極１６１へ励振信号を給電する給電部となっている。一方、下面電極１４は、対向領域９１３から右方へ引き出され、引き出された部分は、下面電極１４へ励振信号を給電する給電部となっている。   As shown in the plan view of FIG. 4 showing a pattern of the lower surface electrode 14 and the upper surface electrode 16 as viewed from above in addition to FIGS. 1 and 2, the upper surface electrode 161 of the upper surface electrode 16 is piezoelectric in the opposing region 913. It faces the lower electrode 14 with the body thin film 15 in between. The upper surface electrode 161 is drawn leftward from the facing region 913, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 161. On the other hand, the lower surface electrode 14 is drawn rightward from the facing region 913, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the lower surface electrode 14.

また、上面電極１６のうち、上面電極１６２は、固定領域９１２において、圧電体薄膜１５を挟んで下面電極１４の給電部と対向している。下面電極１４と上面電極１６２とはバイアホール１５５によって導通させられているので、圧電薄膜共振子１では、外部に露出した上面電極１６２を介して下面電極１４への励振信号の給電が行われる。   Further, among the upper surface electrodes 16, the upper surface electrode 162 is opposed to the power feeding portion of the lower surface electrode 14 with the piezoelectric thin film 15 interposed therebetween in the fixed region 912. Since the lower surface electrode 14 and the upper surface electrode 162 are electrically connected by the via hole 155, the piezoelectric thin film resonator 1 feeds an excitation signal to the lower surface electrode 14 through the upper surface electrode 162 exposed to the outside.

圧電薄膜共振子１では、圧電体薄膜１５の自由振動領域９１１の下面及び上面に下面電極１４及び上面電極１６が形成されているのみならず、圧電体薄膜１５の掘り込み１５６が形成された領域（以下では、「掘り込み領域」という）９１４の下面及び上面にも下面電極１４及び上面電極１６が形成されており、対向領域９１３が自由振動領域９１１を超えて固定領域９１２まで拡がっている。   In the piezoelectric thin film resonator 1, not only the lower surface electrode 14 and the upper surface electrode 16 are formed on the lower surface and the upper surface of the free vibration region 911 of the piezoelectric thin film 15, but also the region where the digging 156 of the piezoelectric thin film 15 is formed. The lower surface electrode 14 and the upper surface electrode 16 are also formed on the lower surface and the upper surface of 914 (hereinafter referred to as “digging region”), and the opposing region 913 extends beyond the free vibration region 911 to the fixed region 912.

圧電薄膜共振子１は、下面電極１６１の給電部と上面電極１６２との間に励振信号を印加することにより、厚み縦振動を自由振動領域９１１に閉じ込めた周波数上昇型のエネルギー閉じ込め共振子として用いることができる。なお、厚み縦振動に代えて、厚みすべり振動を利用することも許容される。   The piezoelectric thin film resonator 1 is used as a frequency increasing type energy confining resonator in which the longitudinal vibration is confined in the free vibration region 911 by applying an excitation signal between the power feeding portion of the lower surface electrode 161 and the upper surface electrode 162. be able to. In addition, it is allowed to use thickness shear vibration instead of thickness longitudinal vibration.

＜２ 第２実施形態＞
図５は、本発明の第２実施形態に係る圧電薄膜共振子２の概略構成を示す模式図であり、圧電薄膜共振子２の断面を示す断面図となっている。圧電薄膜共振子２も、圧電薄膜共振子１と同様に、支持基板２１の上に、接着層２２、キャビティ形成膜２３、下面電極２４、圧電体薄膜２５及び上面電極２６（２６１，２６２）をこの順序で積層した構造を有している。圧電薄膜共振子２の支持基板２１、接着層２２、キャビティ形成膜２３、下面電極２４、圧電体薄膜２５及び上面電極２６（２６１，２６２）は、それぞれ、圧電薄膜共振子１の支持基板１１、接着層１２、キャビティ形成膜１３、下面電極１４、圧電体薄膜１５及び上面電極１６（１６１，１６２）に相当し、圧電薄膜共振子１と同様に構成することができる。 <2 Second Embodiment>
FIG. 5 is a schematic diagram illustrating a schematic configuration of the piezoelectric thin film resonator 2 according to the second embodiment of the present invention, and is a cross-sectional view illustrating a cross section of the piezoelectric thin film resonator 2. Similarly to the piezoelectric thin film resonator 1, the piezoelectric thin film resonator 2 includes an adhesive layer 22, a cavity forming film 23, a lower surface electrode 24, a piezoelectric thin film 25, and an upper surface electrode 26 (261, 262) on the support substrate 21. It has a structure laminated in this order. The support substrate 21, the adhesive layer 22, the cavity forming film 23, the lower surface electrode 24, the piezoelectric thin film 25 and the upper surface electrode 26 (261, 262) of the piezoelectric thin film resonator 2 are respectively the support substrate 11 of the piezoelectric thin film resonator 1, It corresponds to the adhesive layer 12, the cavity forming film 13, the lower surface electrode 14, the piezoelectric thin film 15, and the upper surface electrode 16 (161, 162), and can be configured similarly to the piezoelectric thin film resonator 1.

圧電薄膜共振子２でも、圧電薄膜共振子１と同様に、下面電極２４、圧電体薄膜２５及び上面電極２６を積層した振動積層体２８の固定領域９２２の下面にキャビティ形成膜２３が形成され、支持基板２１、接着層２２及びキャビティ形成膜２３を積層した支持体２７が固定領域９２２において振動積層体２８を支持している。さらに、圧電体薄膜２５の下面にも、圧電体薄膜１５と同様に、圧電体薄膜２５を薄肉化する掘り込み２５６が形成されている。掘り込み２５６も、自由振動領域９２１の外縁に自由振動領域９２１の外郭に沿って形成されている。   In the piezoelectric thin film resonator 2, similarly to the piezoelectric thin film resonator 1, the cavity forming film 23 is formed on the lower surface of the fixed region 922 of the vibration laminate 28 in which the lower electrode 24, the piezoelectric thin film 25, and the upper electrode 26 are stacked. A support 27 in which the support substrate 21, the adhesive layer 22 and the cavity forming film 23 are stacked supports the vibration stack 28 in the fixed region 922. Further, similarly to the piezoelectric thin film 15, a dig 256 for reducing the thickness of the piezoelectric thin film 25 is formed on the lower surface of the piezoelectric thin film 25. The digging 256 is also formed on the outer edge of the free vibration region 921 along the outline of the free vibration region 921.

上面電極２６のうち、上面電極２６１は、対向領域９２３において、圧電体薄膜２５を挟んで下面電極２４と対向している。上面電極２６１は、対向領域９２３から左方へ引き出され、引き出された部分は、上面電極２６１へ励振信号を給電する給電部となっている。一方、下面電極２４は、対向領域９２３から右方へ引き出され、引き出された部分は、下面電極２４へ励振信号を給電する給電部となっている。   Among the upper surface electrodes 26, the upper surface electrode 261 is opposed to the lower surface electrode 24 across the piezoelectric thin film 25 in the opposed region 923. The upper surface electrode 261 is drawn leftward from the facing region 923, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 261. On the other hand, the lower surface electrode 24 is drawn rightward from the facing region 923, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the lower surface electrode 24.

また、上面電極２６のうち、上面電極２６２は、固定領域９２２において、圧電体薄膜２５を挟んで下面電極２４の給電部と対向している。下面電極２４と上面電極２６２とはバイアホール２５５によって導通させられているので、圧電薄膜共振子２では、外部に露出した上面電極２６２を介して下面電極２４への励振信号の給電が行われる。   Further, among the upper surface electrodes 26, the upper surface electrode 262 is opposed to the power feeding portion of the lower surface electrode 24 with the piezoelectric thin film 25 interposed therebetween in the fixed region 922. Since the lower surface electrode 24 and the upper surface electrode 262 are electrically connected by the via hole 255, the piezoelectric thin film resonator 2 supplies an excitation signal to the lower surface electrode 24 through the upper surface electrode 262 exposed to the outside.

ただし、圧電薄膜共振子２では、圧電薄膜共振子１と異なり、圧電体薄膜２５の自由振動領域９２１の一部（全部でもよい）の下面及び上面に下面電極２４及び上面電極２６が形成されているが、圧電体薄膜２５の掘り込み領域９２４の下面及び上面には下面電極２４及び上面電極２６が形成されておらず、対向領域９２３が自由振動領域９２１に収まっている。   However, in the piezoelectric thin film resonator 2, unlike the piezoelectric thin film resonator 1, the lower surface electrode 24 and the upper surface electrode 26 are formed on the lower surface and the upper surface of a part (or all) of the free vibration region 921 of the piezoelectric thin film 25. However, the lower surface electrode 24 and the upper surface electrode 26 are not formed on the lower surface and the upper surface of the digging region 924 of the piezoelectric thin film 25, and the opposing region 923 is contained in the free vibration region 921.

このような圧電薄膜共振子２も、上面電極２６１の給電部と上面電極２６２との間に励振信号を印加することにより、厚み縦振動を自由振動領域９２１に閉じ込めた周波数上昇型のエネルギー閉じ込め共振子として用いることができる。掘り込み２５６も、圧電体薄膜２５を薄肉化することにより、支持体２７に支持されている固定領域９２２の共振周波数の極端な低下を緩和し、圧電薄膜共振子２の副共振を抑制する役割を果たしている。   Such a piezoelectric thin film resonator 2 also has a frequency increasing type energy confinement resonance in which the longitudinal vibration is confined in the free vibration region 921 by applying an excitation signal between the power supply portion of the upper surface electrode 261 and the upper surface electrode 262. Can be used as a child. The digging 256 also reduces the resonance frequency of the fixed region 922 supported by the support 27 by reducing the thickness of the piezoelectric thin film 25 and suppresses the sub-resonance of the piezoelectric thin film resonator 2. Plays.

＜３ 第３実施形態＞
図６は、本発明の第３実施形態に係る圧電薄膜共振子３の概略構成を示す模式図であり、圧電薄膜共振子３の断面を示す断面図となっている。圧電薄膜共振子３も、圧電薄膜共振子１と同様に、支持基板３１の上に、接着層３２、キャビティ形成膜３３、下面電極３４、圧電体薄膜３５及び上面電極３６（３６１，３６２）をこの順序で積層した構造を有している。圧電薄膜共振子３の支持基板３１、接着層３２、キャビティ形成膜３３、下面電極３４、圧電体薄膜３５及び上面電極３６（３６１，３６２）は、それぞれ、圧電薄膜共振子１の支持基板１１、接着層１２、キャビティ形成膜１３、下面電極１４、圧電体薄膜１５及び上面電極１６（１６１，１６２）に相当し、圧電薄膜共振子１と同様に構成することができる。 <3 Third Embodiment>
FIG. 6 is a schematic diagram illustrating a schematic configuration of the piezoelectric thin film resonator 3 according to the third embodiment of the present invention, and is a cross-sectional view illustrating a cross section of the piezoelectric thin film resonator 3. Similarly to the piezoelectric thin film resonator 1, the piezoelectric thin film resonator 3 includes an adhesive layer 32, a cavity forming film 33, a lower surface electrode 34, a piezoelectric thin film 35, and an upper surface electrode 36 (361, 362) on a support substrate 31. It has a structure laminated in this order. The support substrate 31, the adhesive layer 32, the cavity forming film 33, the lower surface electrode 34, the piezoelectric thin film 35, and the upper surface electrodes 36 (361, 362) of the piezoelectric thin film resonator 3 are respectively the support substrate 11 of the piezoelectric thin film resonator 1, It corresponds to the adhesive layer 12, the cavity forming film 13, the lower surface electrode 14, the piezoelectric thin film 15, and the upper surface electrode 16 (161, 162), and can be configured similarly to the piezoelectric thin film resonator 1.

圧電薄膜共振子３でも、圧電薄膜共振子１と同様に、下面電極３４、圧電体薄膜３５及び上面電極３６を積層した振動積層体３８の固定領域９３２の下面にキャビティ形成膜３３が形成され、支持基板３１、接着層３２及びキャビティ形成膜３３を積層した支持体３７が固定領域９３２において振動積層体３８を支持している。   In the piezoelectric thin film resonator 3, similarly to the piezoelectric thin film resonator 1, the cavity forming film 33 is formed on the lower surface of the fixed region 932 of the vibration laminated body 38 in which the lower electrode 34, the piezoelectric thin film 35, and the upper electrode 36 are laminated, A support 37 in which the support substrate 31, the adhesive layer 32, and the cavity forming film 33 are stacked supports the vibration stack 38 in the fixed region 932.

上面電極３６のうち、上面電極３６１は、対向領域９３３において、圧電体薄膜３５を挟んで下面電極３４と対向している。上面電極３６１は、対向領域９３３から左方へ引き出され、引き出された部分は、上面電極３６１へ励振信号を給電する給電部となっている。一方、下面電極３４は、対向領域９３３から右方へ引き出され、引き出された部分は、下面電極３４へ励振信号を給電する給電部となっている。   Among the upper surface electrodes 36, the upper surface electrode 361 faces the lower surface electrode 34 with the piezoelectric thin film 35 interposed therebetween in the facing region 933. The upper surface electrode 361 is drawn leftward from the facing region 933, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 361. On the other hand, the lower surface electrode 34 is drawn rightward from the facing region 933, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the lower surface electrode 34.

また、上面電極３６のうち、上面電極３６２は、固定領域９３２において、圧電体薄膜３５を挟んで下面電極３４の給電部と対向している。下面電極３４と上面電極３６２とはバイアホール３５５によって導通させられているので、圧電薄膜共振子３では、外部に露出した上面電極３６２を介して下面電極３４への励振信号の給電が行われる。   Of the upper surface electrodes 36, the upper surface electrode 362 faces the power feeding portion of the lower surface electrode 34 with the piezoelectric thin film 35 interposed therebetween in the fixed region 932. Since the lower surface electrode 34 and the upper surface electrode 362 are electrically connected by the via hole 355, the piezoelectric thin film resonator 3 feeds an excitation signal to the lower surface electrode 34 through the upper surface electrode 362 exposed to the outside.

ただし、圧電薄膜共振子３では、圧電薄膜共振子１と異なり、圧電体薄膜３５の上面に、圧電体薄膜３５を薄肉化する掘り込み３５６が形成されている。掘り込み３５６は、自由振動領域９３１の外縁に自由振動領域９３１の外郭に沿って形成されている。掘り込み３５６は、キャビティ形成膜３３で埋められておらず、空洞となっている。   However, in the piezoelectric thin film resonator 3, unlike the piezoelectric thin film resonator 1, a digging 356 for thinning the piezoelectric thin film 35 is formed on the upper surface of the piezoelectric thin film 35. The digging 356 is formed on the outer edge of the free vibration region 931 along the outline of the free vibration region 931. The digging 356 is not filled with the cavity forming film 33 but is a cavity.

このような圧電薄膜共振子３も、上面電極３６１の給電部と上面電極３６２との間に励振信号を印加することにより、厚み縦振動を自由振動領域９３１に閉じ込めた周波数上昇型のエネルギー閉じ込め共振子として用いることができる。掘り込み３５６も、圧電体薄膜３５を薄肉化することにより、支持体３７に支持されている固定領域９３２の共振周波数の極端な低下を緩和し、圧電薄膜共振子３の副共振を抑制する役割を果たしている。   Such a piezoelectric thin film resonator 3 also has a frequency increasing type energy confinement resonance in which the longitudinal vibration is confined in the free vibration region 931 by applying an excitation signal between the feeding portion of the upper surface electrode 361 and the upper surface electrode 362. Can be used as a child. The digging 356 also reduces the resonance frequency of the fixed region 932 supported by the support 37 by reducing the thickness of the piezoelectric thin film 35 and suppresses the sub-resonance of the piezoelectric thin film resonator 3. Plays.

＜４ 第４実施形態＞
図７は、本発明の第４実施形態に係る圧電薄膜共振子４の概略構成を示す模式図であり、圧電薄膜共振子４の断面を示す断面図となっている。圧電薄膜共振子４も、圧電薄膜共振子１と同様に、支持基板４１の上に、接着層４２、キャビティ形成膜４３、下面電極４４、圧電体薄膜４５及び上面電極４６をこの順序で積層した構造を有している。圧電薄膜共振子４の支持基板４１、接着層４２、キャビティ形成膜４３、下面電極４４、圧電体薄膜４５及び上面電極４６（４６１，４６２）は、それぞれ、圧電薄膜共振子１の支持基板１１、接着層１２、キャビティ形成膜１３、下面電極１４、圧電体薄膜１５及び上面電極１６（１６１，１６２）に相当し、圧電薄膜共振子１と同様に構成することができる。 <4 Fourth Embodiment>
FIG. 7 is a schematic view showing a schematic configuration of the piezoelectric thin film resonator 4 according to the fourth embodiment of the present invention, and is a cross-sectional view showing a cross section of the piezoelectric thin film resonator 4. Similarly to the piezoelectric thin film resonator 1, the piezoelectric thin film resonator 4 has an adhesive layer 42, a cavity forming film 43, a lower surface electrode 44, a piezoelectric thin film 45, and an upper surface electrode 46 laminated in this order on a support substrate 41. It has a structure. The support substrate 41, the adhesive layer 42, the cavity forming film 43, the lower surface electrode 44, the piezoelectric thin film 45, and the upper surface electrodes 46 (461, 462) of the piezoelectric thin film resonator 4 are the support substrate 11, the piezoelectric thin film resonator 1, respectively. It corresponds to the adhesive layer 12, the cavity forming film 13, the lower surface electrode 14, the piezoelectric thin film 15, and the upper surface electrode 16 (161, 162), and can be configured similarly to the piezoelectric thin film resonator 1.

圧電薄膜共振子４でも、圧電薄膜共振子１と同様に、下面電極４４、圧電体薄膜４５及び上面電極４６を積層した振動積層体４８の固定領域９４２の下面にキャビティ形成膜４３が形成され、支持基板４１、接着層４２及びキャビティ形成膜４３を積層した支持体４７が固定領域９４２において振動積層体４８を支持している。さらに、圧電体薄膜４５の下面にも、圧電体薄膜１５と同様に、圧電体薄膜４５を薄肉化する掘り込み４５６が形成されている。圧電体薄膜４５の下面に形成された掘り込み４５６も、自由振動領域９４２の外縁に自由振動領域９４１の外郭に沿って形成されている。   In the piezoelectric thin film resonator 4, similarly to the piezoelectric thin film resonator 1, the cavity forming film 43 is formed on the lower surface of the fixed region 942 of the vibration laminate 48 in which the lower electrode 44, the piezoelectric thin film 45, and the upper electrode 46 are stacked. A support 47 in which the support substrate 41, the adhesive layer 42, and the cavity forming film 43 are stacked supports the vibration stack 48 in the fixed region 942. Further, a digging 456 for reducing the thickness of the piezoelectric thin film 45 is formed on the lower surface of the piezoelectric thin film 45 as well as the piezoelectric thin film 15. The digging 456 formed on the lower surface of the piezoelectric thin film 45 is also formed on the outer edge of the free vibration region 942 along the outline of the free vibration region 941.

上面電極４６のうち、上面電極４６１は、対向領域９４３において、圧電体薄膜４５を挟んで下面電極４４と対向している。上面電極４６１は、対向領域９４３から左方へ引き出され、引き出された部分は、上面電極４６１へ励振信号を給電する給電部となっている。一方、下面電極４４は、対向領域９４３から右方へ引き出され、引き出された部分は、下面電極４４へ励振信号を給電する給電部となっている。   Among the upper surface electrodes 46, the upper surface electrode 461 is opposed to the lower surface electrode 44 with the piezoelectric thin film 45 interposed therebetween in the facing region 943. The upper surface electrode 461 is drawn leftward from the facing region 943, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 461. On the other hand, the lower surface electrode 44 is drawn rightward from the facing region 943, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the lower surface electrode 44.

また、上面電極４６のうち、上面電極４６２は、固定領域９４２において、圧電体薄膜４５を挟んで下面電極４４の給電部と対向している。下面電極４４と上面電極４６２とはバイアホール４５５によって導通させられているので、圧電薄膜共振子４では、外部に露出した上面電極４６２を介して下面電極４４への励振信号の給電が行われる。   Further, among the upper surface electrodes 46, the upper surface electrode 462 is opposed to the power feeding portion of the lower surface electrode 44 with the piezoelectric thin film 45 interposed therebetween in the fixed region 942. Since the lower surface electrode 44 and the upper surface electrode 462 are electrically connected by the via hole 455, the piezoelectric thin film resonator 4 feeds an excitation signal to the lower surface electrode 44 through the upper surface electrode 462 exposed to the outside.

ただし、圧電薄膜共振子４では、圧電薄膜共振子４と異なり、圧電体薄膜４５の上面にも、圧電体薄膜４５を薄肉化する掘り込み４５６が形成されている。圧電体薄膜４５の上面に形成された掘り込み４５６も、自由振動領域９４２の外縁に自由振動領域９４１の外郭に沿って形成されている。   However, in the piezoelectric thin film resonator 4, unlike the piezoelectric thin film resonator 4, a digging 456 for reducing the thickness of the piezoelectric thin film 45 is also formed on the upper surface of the piezoelectric thin film 45. The digging 456 formed on the upper surface of the piezoelectric thin film 45 is also formed on the outer edge of the free vibration region 942 along the outline of the free vibration region 941.

このような圧電薄膜共振子４も、上面電極４６１の給電部と上面電極４６２との間に励振信号を印加することにより、厚み縦振動を自由振動領域に閉じ込めた周波数上昇型のエネルギー閉じ込め共振子として用いることができる。掘り込み４５６も、圧電体薄膜４５を薄肉化することにより、支持体４７に支持されている固定領域９４２の共振周波数の極端な低下を緩和し、圧電薄膜共振子４の副共振を抑制する役割を果たしている。   Such a piezoelectric thin film resonator 4 also has a frequency increasing type energy confinement resonator in which the longitudinal vibration is confined in the free vibration region by applying an excitation signal between the power supply portion of the upper surface electrode 461 and the upper surface electrode 462. Can be used as The digging 456 also serves to alleviate an extreme decrease in the resonance frequency of the fixed region 942 supported by the support 47 and to suppress sub-resonance of the piezoelectric thin film resonator 4 by thinning the piezoelectric thin film 45. Plays.

＜５ 第５実施形態＞
図８は、本発明の第５実施形態に係る圧電薄膜共振子５の概略構成を示す模式図であり、圧電薄膜共振子５の断面を示す断面図となっている。圧電薄膜共振子５も、圧電薄膜共振子１と同様に、支持基板５１の上に、接着層５２、キャビティ形成膜５３、下面電極５４、圧電体薄膜５５及び上面電極５６をこの順序で積層した構造を有している。圧電薄膜共振子５の支持基板５１、接着層５２、キャビティ形成膜５３、下面電極５４、圧電体薄膜５５及び上面電極２６（５６１，５６２）は、それぞれ、圧電薄膜共振子１の支持基板１１、接着層１２、キャビティ形成膜１３、下面電極１４、圧電体薄膜１５及び上面電極１６（１６１，１６２）に相当し、圧電薄膜共振子１と同様に構成することができる。 <5 Fifth Embodiment>
FIG. 8 is a schematic view showing a schematic configuration of the piezoelectric thin film resonator 5 according to the fifth embodiment of the present invention, and is a cross-sectional view showing a cross section of the piezoelectric thin film resonator 5. Similarly to the piezoelectric thin film resonator 1, the piezoelectric thin film resonator 5 has an adhesive layer 52, a cavity forming film 53, a lower surface electrode 54, a piezoelectric thin film 55, and an upper surface electrode 56 laminated in this order on the support substrate 51. It has a structure. The support substrate 51, the adhesive layer 52, the cavity forming film 53, the lower surface electrode 54, the piezoelectric thin film 55, and the upper surface electrodes 26 (561, 562) of the piezoelectric thin film resonator 5 are the support substrate 11 of the piezoelectric thin film resonator 1, respectively. It corresponds to the adhesive layer 12, the cavity forming film 13, the lower surface electrode 14, the piezoelectric thin film 15, and the upper surface electrode 16 (161, 162), and can be configured similarly to the piezoelectric thin film resonator 1.

圧電薄膜共振子５でも、圧電薄膜共振子１と同様に、下面電極５４、圧電体薄膜５５及び上面電極５６を積層した振動積層体５８の固定領域９５２の下面にキャビティ形成膜５３が形成され、支持基板５１、接着層５２及びキャビティ形成膜５３を積層した支持体５７が固定領域９５２において振動積層体５８を支持している。さらに、圧電体薄膜５５の下面にも、圧電体薄膜１５と同様に、圧電体薄膜５５を薄肉化する掘り込み５５６が形成されている。掘り込み５５６も、自由振動領域９５１の外縁に自由振動領域９５１の外郭に沿って形成されている。   In the piezoelectric thin film resonator 5, similarly to the piezoelectric thin film resonator 1, the cavity forming film 53 is formed on the lower surface of the fixed region 952 of the vibration laminate 58 in which the lower electrode 54, the piezoelectric thin film 55 and the upper electrode 56 are laminated, A support 57 in which the support substrate 51, the adhesive layer 52, and the cavity forming film 53 are stacked supports the vibration stack 58 in the fixed region 952. Further, a digging 556 for reducing the thickness of the piezoelectric thin film 55 is also formed on the lower surface of the piezoelectric thin film 55, similarly to the piezoelectric thin film 15. The digging 556 is also formed on the outer edge of the free vibration region 951 along the outline of the free vibration region 951.

上面電極５６のうち、上面電極５６１は、対向領域９５３において、圧電体薄膜５５を挟んで下面電極５４と対向している。上面電極５６１は、対向領域９５３から左方へ引き出され、引き出された部分は、上面電極５６１へ励振信号を給電する給電部となっている。一方、下面電極５４は、対向領域９５３から右方へ引き出され、引き出された部分は、下面電極５４へ励振信号を給電する給電部となっている。   Among the upper surface electrodes 56, the upper surface electrode 561 is opposed to the lower surface electrode 54 with the piezoelectric thin film 55 interposed therebetween in the facing region 953. The upper surface electrode 561 is drawn leftward from the facing region 953, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 561. On the other hand, the lower surface electrode 54 is drawn rightward from the facing region 953, and the drawn portion serves as a power feeding unit that feeds an excitation signal to the lower surface electrode 54.

また、上面電極５６のうち、上面電極５６２は、固定領域９５２において、圧電体薄膜５５を挟んで下面電極５４の給電部と対向している。下面電極５４と上面電極５６２とはバイアホール５５５によって導通させられているので、圧電薄膜共振子５では、外部に露出した上面電極５６２を介して下面電極５４への励振信号の給電が行われる。   Further, among the upper surface electrodes 56, the upper surface electrode 562 is opposed to the power feeding portion of the lower surface electrode 54 with the piezoelectric thin film 55 interposed therebetween in the fixed region 952. Since the lower surface electrode 54 and the upper surface electrode 562 are electrically connected by the via hole 555, the piezoelectric thin film resonator 5 feeds an excitation signal to the lower surface electrode 54 through the upper surface electrode 562 exposed to the outside.

ただし、圧電薄膜共振子１では、自由振動領域９１１と掘り込み領域９１４とが接しているのに対して、圧電薄膜共振子５では、自由振動領域９５１と掘り込み領域９５４とが約５μｍ離れている。なお、自由振動領域９５１と掘り込み領域９５４との距離Ｌは、必ずしも「約５μｍ」である必要はなく、１０μｍ以下であればよい。   However, in the piezoelectric thin film resonator 1, the free vibration region 911 and the digging region 914 are in contact with each other, whereas in the piezoelectric thin film resonator 5, the free vibration region 951 and the digging region 954 are separated from each other by about 5 μm. Yes. The distance L between the free vibration region 951 and the digging region 954 is not necessarily “about 5 μm”, and may be 10 μm or less.

このような圧電薄膜共振子５も、上面電極５６１の給電部と上面電極５６２との間に励振信号を印加することにより、厚み縦振動を自由振動領域９５１に閉じ込めた周波数上昇型のエネルギー閉じ込め共振子として用いることができる。掘り込み５５６も、圧電体薄膜５５を薄肉化することにより、支持体５７に支持されている固定領域９５２の共振周波数の極端な低下を緩和し、圧電薄膜共振子５の副共振を抑制する役割を果たしている。   Such a piezoelectric thin film resonator 5 also has a frequency increasing type energy confinement resonance in which the longitudinal vibration is confined in the free vibration region 951 by applying an excitation signal between the feeding portion of the upper surface electrode 561 and the upper surface electrode 562. Can be used as a child. The digging 556 also reduces the resonance frequency of the fixed region 952 supported by the support 57 by reducing the thickness of the piezoelectric thin film 55 and suppresses the sub-resonance of the piezoelectric thin film resonator 5. Plays.

＜６ その他＞
第１実施形態から第５実施形態で説明した掘り込み１５６，２５６，３５６，４５６，５５６の深さ及び幅を一定にすることは必須ではなく、掘り込み１５６，２５６，３５６，４５６，５５６の深さ及び幅が部分的に異なっていてもよい。 <6 Others>
It is not essential to make the depths and widths of the excavations 156, 256, 356, 456, and 556 described in the first to fifth embodiments constant, and the excavations 156, 256, 356, 456, and 556 The depth and width may be partially different.

以下では、本発明の第１実施形態に係る実施例と本発明の範囲外の比較例とについて説明する。   Hereinafter, examples according to the first embodiment of the present invention and comparative examples outside the scope of the present invention will be described.

＜実施例＞
実施例では、支持基板１１及び圧電体薄膜１５を構成する圧電材料としてニオブ酸リチウムの単結晶、接着層１２を構成する材料としてエポキシ接着剤、キャビティ形成膜１３を構成する絶縁材料として二酸化ケイ素、下面電極１４及び上面電極１６を構成する導電材料としてタングステンを用いて圧電薄膜共振子１を製造した。 <Example>
In the embodiment, a single crystal of lithium niobate is used as a piezoelectric material constituting the support substrate 11 and the piezoelectric thin film 15, an epoxy adhesive is used as a material constituting the adhesive layer 12, silicon dioxide is used as an insulating material constituting the cavity forming film 13, The piezoelectric thin film resonator 1 was manufactured using tungsten as a conductive material constituting the lower electrode 14 and the upper electrode 16.

実施例に係る圧電薄膜共振子１は、図９の断面図に示すように、製造原価の低減のために、多数の圧電薄膜共振子１を一体化したマザー基板１ｍを作製した後に、マザー基板１ｍをダイシングソーで切断して個々の圧電薄膜共振子１へ分離することによって製造されている。なお、図９には、３個の圧電薄膜共振子１がマザー基板１ｍに含まれる例が示されているが、マザー基板１ｍに含まれる圧電薄膜共振子１の数は、４個以上であってもよく、典型的に言えば、マザー基板１ｍには、数１００個〜数１０００個の圧電薄膜共振子１が含まれる。   As shown in the cross-sectional view of FIG. 9, the piezoelectric thin film resonator 1 according to the example is manufactured after a mother substrate 1 m in which a large number of piezoelectric thin film resonators 1 are integrated to reduce the manufacturing cost. 1 m is cut by a dicing saw and separated into individual piezoelectric thin film resonators 1. FIG. 9 shows an example in which three piezoelectric thin film resonators 1 are included in the mother substrate 1m. However, the number of piezoelectric thin film resonators 1 included in the mother substrate 1m is four or more. Typically, the mother substrate 1m includes several hundred to several thousand piezoelectric thin film resonators 1.

以下では、便宜上、マザー基板１ｍに含まれる１個の圧電薄膜共振子１に着目して説明を進めるが、マザー基板１ｍに含まれる他の圧電薄膜共振子１も着目した圧電薄膜共振子１と同時平行して製造されている。   In the following, for the sake of convenience, the description will be given focusing on one piezoelectric thin film resonator 1 included in the mother substrate 1m, but the piezoelectric thin film resonator 1 also focusing on other piezoelectric thin film resonators 1 included in the mother substrate 1m Manufactured in parallel.

続いて、図１０〜図１９の断面図を参照しながら、実施例に係る圧電薄膜共振子１の製造方法を説明する。   Then, the manufacturing method of the piezoelectric thin film resonator 1 which concerns on an Example is demonstrated, referring sectional drawing of FIGS.

圧電薄膜共振子１の製造にあたっては、最初に、厚み０．５ｍｍ、直径３インチのニオブ酸リチウム単結晶の円形ウエハ（４５度カットＹ板）を支持基板１１及び圧電体基板９１６として準備した。   In manufacturing the piezoelectric thin film resonator 1, first, a circular wafer (45-degree cut Y plate) of lithium niobate single crystal having a thickness of 0.5 mm and a diameter of 3 inches was prepared as the support substrate 11 and the piezoelectric substrate 916.

続いて、圧電体基板９１６の下面にクロム膜と金膜とをスパッタリングにより順次成膜し、得られた積層膜を一般的なフォトリソグラフィ技術を用いてパターニングすることにより、掘り込み領域９１４のみを露出させたエッチングマスク９１７を圧電体基板９１６の下面に形成した（図１０）。しかる後に、圧電体基板９１６を温度６０℃の１：１バッファードフッ酸水溶液でエッチングすることにより、深さ０．１μｍの掘り込み１５６が形成された圧電体基板９１６を得た（図１１）。   Subsequently, a chromium film and a gold film are sequentially formed on the lower surface of the piezoelectric substrate 916 by sputtering, and the obtained laminated film is patterned using a general photolithography technique, so that only the digging region 914 is formed. An exposed etching mask 917 was formed on the lower surface of the piezoelectric substrate 916 (FIG. 10). Thereafter, the piezoelectric substrate 916 was etched with a 1: 1 buffered hydrofluoric acid aqueous solution at a temperature of 60 ° C. to obtain a piezoelectric substrate 916 formed with a digging 156 having a depth of 0.1 μm (FIG. 11). .

さらに続いて、圧電体基板９１６の下面に膜厚１０００オングストロームのタングステン膜をスパッタリングにより成膜し、得られたタングステン膜を一般的なフォトリソグラフィ技術を用いてパターニングすることにより、図３に示すパターンを有する下面電極１４が形成された圧電体基板９１６を得た（図１２）。   Subsequently, a tungsten film having a thickness of 1000 angstroms is formed on the lower surface of the piezoelectric substrate 916 by sputtering, and the obtained tungsten film is patterned by using a general photolithography technique, whereby the pattern shown in FIG. A piezoelectric substrate 916 on which the lower electrode 14 having s was formed was obtained (FIG. 12).

そして、圧電体基板９１６の下面に膜厚０．５μｍの二酸化ケイ素膜をスパッタリングにより成膜し、得られた二酸化ケイ素膜を一般的なフォトリソグラフィ技術を用いてパターニングすることにより、固定領域９１２に成膜された二酸化ケイ素膜を残して、自由振動領域９１１に成膜された二酸化ケイ素膜を除去した(図１３)。これにより、圧電体基板９１６にキャビティ形成膜１３が形成されたことになる。   Then, a silicon dioxide film having a film thickness of 0.5 μm is formed on the lower surface of the piezoelectric substrate 916 by sputtering, and the obtained silicon dioxide film is patterned using a general photolithography technique, so that the fixed region 912 is formed. The silicon dioxide film formed in the free vibration region 911 was removed while leaving the formed silicon dioxide film (FIG. 13). As a result, the cavity forming film 13 is formed on the piezoelectric substrate 916.

ここで、支持基板１１の上面に接着層１２となるエポキシ接着剤を塗布し（図１４）、支持基板１１の上面と、下面電極１４及びキャビティ形成膜１３が形成された圧電体基板９１６の下面とを張り合わせた。そして、支持基板１１及び圧電体基板９１６に圧力を印加してプレス圧着を行い、接着層１２の膜厚を０．５μｍとした。しかる後に、張り合わせた支持基板１１及び圧電体基板９１６を２００℃の環境下で１時間放置してエポキシ接着剤を硬化させ、支持基板１１と圧電体基板９１６とを接着した（図１５）。これにより、圧電体基板９１６の自由振動領域９１１の下方に、深さ０．５μｍのキャビティが形成された。   Here, an epoxy adhesive serving as the adhesive layer 12 is applied to the upper surface of the support substrate 11 (FIG. 14), and the upper surface of the support substrate 11 and the lower surface of the piezoelectric substrate 916 on which the lower electrode 14 and the cavity forming film 13 are formed. And pasted together. Then, pressure was applied to the support substrate 11 and the piezoelectric substrate 916 to perform press-bonding, and the film thickness of the adhesive layer 12 was set to 0.5 μm. Thereafter, the bonded support substrate 11 and piezoelectric substrate 916 were allowed to stand in an environment of 200 ° C. for 1 hour to cure the epoxy adhesive, thereby bonding the support substrate 11 and the piezoelectric substrate 916 (FIG. 15). As a result, a cavity having a depth of 0.5 μm was formed below the free vibration region 911 of the piezoelectric substrate 916.

支持基板１１と圧電体基板９１６との接着が完了した後、圧電体基板９１６を支持基板１１に接着した状態を維持したまま、支持基板１１の下面を研磨治具に接着固定し、圧電体基板９１６の上面を固定砥粒の研削機で研削加工し、圧電体基板９１６の膜厚を５０μｍまで薄肉化した。さらに、圧電体基板９１６の上面をダイヤモンド砥粒で研磨加工し、圧電体基板９１６の膜厚を２μｍまで薄肉化した。最後に、ダイヤモンド砥粒による研磨加工で圧電体基板９１６に生じた加工変質層を除去するために、遊離砥粒及び不繊布系研磨パッドを使用して圧電体基板９１６の仕上げ研磨を行い、膜厚１μｍの圧電体薄膜１５を得た（図１６）。   After the bonding between the support substrate 11 and the piezoelectric substrate 916 is completed, the lower surface of the support substrate 11 is bonded and fixed to the polishing jig while maintaining the state where the piezoelectric substrate 916 is bonded to the support substrate 11. The upper surface of 916 was ground with a fixed abrasive grinder to reduce the thickness of the piezoelectric substrate 916 to 50 μm. Further, the upper surface of the piezoelectric substrate 916 was polished with diamond abrasive grains, and the thickness of the piezoelectric substrate 916 was reduced to 2 μm. Finally, in order to remove the work-affected layer generated on the piezoelectric substrate 916 by polishing with diamond abrasive grains, the piezoelectric substrate 916 is subjected to final polishing using loose abrasive grains and a non-woven cloth polishing pad, A piezoelectric thin film 15 having a thickness of 1 μm was obtained (FIG. 16).

次に、圧電体薄膜１５の上面を有機溶媒で洗浄し、圧電体薄膜１５の上面にクロム膜と金膜とをスパッタリングにより順次成膜し、得られた積層膜を一般的なフォトリソグラフィ技術を用いてパターニングすることにより、バイアホール１５５を形成すべき領域のみを露出させたエッチングマスク９１８を形成した（図１７）。しかる後に、圧電体薄膜１５を温度６０℃の１：１バッファードフッ酸水溶液でエッチングすることによりバイアホール１５５を形成し、下面電極１４を露出させた（図１８）。   Next, the upper surface of the piezoelectric thin film 15 is washed with an organic solvent, a chromium film and a gold film are sequentially formed on the upper surface of the piezoelectric thin film 15 by sputtering, and the obtained laminated film is subjected to a general photolithography technique. An etching mask 918 exposing only a region where the via hole 155 is to be formed was formed by using and patterning (FIG. 17). Thereafter, the piezoelectric thin film 15 was etched with a 1: 1 buffered hydrofluoric acid aqueous solution at a temperature of 60 ° C., thereby forming a via hole 155 and exposing the lower electrode 14 (FIG. 18).

そして、圧電体薄膜１５の上面に膜厚１０００オングストロームのタングステン膜をスパッタリングにより成膜し、得られたタングステン膜を一般的なフォトリソグラフィ技術を用いてパターニングすることにより、図３に示すパターンを有する上面電極１６を得た（図１９）。このとき、バイアホール１５５の内側面にもタングステン膜が形成されるので、下面電極１４と上面電極１６２との導通が確保される。   Then, a tungsten film having a film thickness of 1000 angstroms is formed on the upper surface of the piezoelectric thin film 15 by sputtering, and the obtained tungsten film is patterned using a general photolithography technique, thereby having the pattern shown in FIG. A top electrode 16 was obtained (FIG. 19). At this time, since a tungsten film is also formed on the inner side surface of the via hole 155, conduction between the lower surface electrode 14 and the upper surface electrode 162 is ensured.

このようにして得られた圧電薄膜共振子１の周波数（ｆ）−インピーダンス（Ｚ）特性を測定して、厚み縦振動モードの共振特性を評価したところ、図２１に示す波形が観察された。   When the frequency (f) -impedance (Z) characteristics of the piezoelectric thin film resonator 1 thus obtained were measured and the resonance characteristics in the thickness longitudinal vibration mode were evaluated, the waveform shown in FIG. 21 was observed.

＜比較例＞
図２０は、比較例に係る、掘り込み１５６が形成されていない圧電薄膜共振子７の概略構成を示す模式図であり、圧電薄膜共振子７の断面を示す断面図となっている。掘り込み１５６の形成を行わない点を除いて実施例に係る圧電薄膜共振子１と同様の製造手順で製造した圧電薄膜共振子７の周波数（ｆ）−インピーダンス（Ｚ）特性を測定して、厚み縦振動モードの共振特性を評価したところ、図２２に示す波形が観察された。 <Comparative example>
FIG. 20 is a schematic diagram illustrating a schematic configuration of the piezoelectric thin film resonator 7 in which the digging 156 is not formed according to the comparative example, and is a cross-sectional view illustrating a cross section of the piezoelectric thin film resonator 7. The frequency (f) -impedance (Z) characteristic of the piezoelectric thin film resonator 7 manufactured by the same manufacturing procedure as that of the piezoelectric thin film resonator 1 according to the example except that the digging 156 is not formed is measured. When the resonance characteristics of the thickness longitudinal vibration mode were evaluated, the waveform shown in FIG. 22 was observed.

＜実施例と比較例との対比＞
図２１と図２２との対比から明らかなように、掘り込み１５６を形成することにより、主共振の低周波側に重畳する副共振を抑制することができ、スプリアスの影響が小さい圧電薄膜共振子１を実現できている。このような副共振の抑制効果は、第２実施形態〜第５実施形態に係る圧電薄膜共振子２〜５でも得ることができる。 <Contrast between Example and Comparative Example>
As is clear from the comparison between FIG. 21 and FIG. 22, by forming the digging 156, the sub-resonance superimposed on the low-frequency side of the main resonance can be suppressed, and the piezoelectric thin film resonator having a small spurious effect. 1 is realized. Such a sub-resonance suppressing effect can also be obtained by the piezoelectric thin film resonators 2 to 5 according to the second to fifth embodiments.

本発明の第１実施形態に係る圧電薄膜共振子１の概略構成を示す斜視図である。1 is a perspective view showing a schematic configuration of a piezoelectric thin film resonator 1 according to a first embodiment of the present invention. 本発明の第１実施形態に係る圧電薄膜共振子１の概略構成を示す断面図である。1 is a cross-sectional view showing a schematic configuration of a piezoelectric thin film resonator 1 according to a first embodiment of the present invention. 圧電体薄膜１５を上方から見た平面図である。FIG. 3 is a plan view of a piezoelectric thin film 15 as viewed from above. 下面電極１４及び上面電極１６を上方から見たパターンを示す平面図である。It is a top view which shows the pattern which looked at the lower surface electrode 14 and the upper surface electrode 16 from upper direction. 本発明の第２実施形態に係る圧電薄膜共振子２の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the piezoelectric thin film resonator 2 which concerns on 2nd Embodiment of this invention. 本発明の第３実施形態に係る圧電薄膜共振子３の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the piezoelectric thin film resonator 3 which concerns on 3rd Embodiment of this invention. 本発明の第４実施形態に係る圧電薄膜共振子４の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the piezoelectric thin film resonator 4 which concerns on 4th Embodiment of this invention. 本発明の第５実施形態に係る圧電薄膜共振子５の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the piezoelectric thin film resonator 5 which concerns on 5th Embodiment of this invention. マザー基板１ｍを切断して個々の圧電薄膜共振子１へ分離する様子を示す断面図である。2 is a cross-sectional view showing a state in which a mother substrate 1m is cut and separated into individual piezoelectric thin film resonators 1. FIG. 圧電体基板９１６にエッチングマスク９１７を形成した状態を示す断面図である。10 is a cross-sectional view showing a state where an etching mask 917 is formed on a piezoelectric substrate 916. FIG. 圧電体基板９１６に掘り込み１５６を形成した状態を示す断面図である。6 is a cross-sectional view showing a state in which a digging 156 is formed in a piezoelectric substrate 916. FIG. 圧電体基板９１６に下面電極１４を形成した状態を示す断面図である。6 is a cross-sectional view showing a state in which a bottom electrode 14 is formed on a piezoelectric substrate 916. FIG. 圧電体基板９１６にキャビティ形成膜１３を形成した状態を示す断面図である。6 is a cross-sectional view showing a state where a cavity forming film 13 is formed on a piezoelectric substrate 916. FIG. 支持基板１１に接着層１２を塗布した状態を示す断面図である。2 is a cross-sectional view showing a state where an adhesive layer 12 is applied to a support substrate 11. FIG. 支持基板１１と圧電体基板９１６とを接着した状態を示す断面図である。FIG. 6 is a cross-sectional view showing a state where a support substrate 11 and a piezoelectric substrate 916 are bonded. 圧電体基板９１６を薄肉化して圧電体薄膜１５とした状態を示す断面図である。6 is a cross-sectional view showing a state in which a piezoelectric substrate 916 is thinned to form a piezoelectric thin film 15. FIG. 圧電体薄膜１５にエッチングマスク９１８を形成した状態を示す断面図である。6 is a cross-sectional view showing a state in which an etching mask 918 is formed on the piezoelectric thin film 15. FIG. 圧電体薄膜１５にバイアホール１５５を形成した状態を示す断面図である。6 is a cross-sectional view showing a state in which a via hole 155 is formed in the piezoelectric thin film 15. FIG. 圧電体薄膜１５に上面電極１６を形成した状態を示す断面図である。2 is a cross-sectional view showing a state in which an upper surface electrode 16 is formed on a piezoelectric thin film 15. FIG. 比較例に係る圧電薄膜共振子８の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the piezoelectric thin film resonator 8 which concerns on a comparative example. 実施例に係る圧電薄膜共振子１の周波数−インピーダンス特性を示す図である。It is a figure which shows the frequency-impedance characteristic of the piezoelectric thin film resonator 1 which concerns on an Example. 比較例に係る圧電薄膜共振子７の周波数−インピーダンス特性を示す図である。It is a figure which shows the frequency-impedance characteristic of the piezoelectric thin film resonator 7 which concerns on a comparative example. 従来の圧電薄膜共振子８の概略構成を示す断面図である。FIG. 6 is a cross-sectional view showing a schematic configuration of a conventional piezoelectric thin film resonator 8.

符号の説明Explanation of symbols

１，２，３，４，５ 圧電薄膜共振子
１１，２１，３１，４１，５１ 支持基板
１２，２２，３２，４２，５２ 接着層
１３，２３，３３，４３，５３ キャビティ形成膜
１４，２４，３４，４４，５４ 下面電極
１５，２５，３５，４５，５５ 圧電体薄膜
１６，２６，３６，４６，５６ 上面電極
１７，２７，３７，４７，５７ 支持体
１８，２８，３８，４８，５８ 振動積層体
１５６，２５６，３５６，４５６，５５６ 掘り込み
９１１，９２１，９３１，９４１，９５１ 自由振動領域 1, 2, 3, 4, 5 Piezoelectric thin film resonators 11, 21, 31, 41, 51 Support substrate 12, 22, 32, 42, 52 Adhesive layer 13, 23, 33, 43, 53 Cavity forming films 14, 24 , 34, 44, 54 Lower electrode 15, 25, 35, 45, 55 Piezoelectric thin film 16, 26, 36, 46, 56 Upper electrode 17, 27, 37, 47, 57 Support 18, 28, 38, 48, 58 vibration laminated body 156,256,356,456,556 digging 911, 921, 931, 941, 951 Free vibration region

Claims (4)

単数又は複数の圧電薄膜共振子を含む圧電薄膜デバイスであって、
圧電体薄膜と、
前記圧電体薄膜を挟んで対向する電極と、
前記圧電体薄膜及び前記電極を積層した振動積層体を自由振動領域の外縁において支持する支持体と、
を備え、
前記圧電体薄膜を薄肉化する掘り込みが前記自由振動領域の外縁に前記自由振動領域の外郭に沿って形成されている圧電薄膜デバイス。 A piezoelectric thin film device including one or more piezoelectric thin film resonators,
A piezoelectric thin film;
Electrodes facing each other across the piezoelectric thin film;
A support for supporting a vibration laminate in which the piezoelectric thin film and the electrode are laminated at an outer edge of a free vibration region;
With
A piezoelectric thin film device in which a digging for thinning the piezoelectric thin film is formed along an outer periphery of the free vibration region at an outer edge of the free vibration region. 前記掘り込みが前記自由振動領域を囲む請求項１に記載の圧電薄膜デバイス。   The piezoelectric thin film device according to claim 1, wherein the digging surrounds the free vibration region. 前記掘り込みの深さが前記圧電体薄膜の膜厚の１％以上２０％以下である請求項１又は請求項２に記載の圧電薄膜デバイス。   The piezoelectric thin film device according to claim 1 or 2, wherein a depth of the digging is 1% or more and 20% or less of a film thickness of the piezoelectric thin film. 前記掘り込みの幅が１μｍ以上１０μｍ以下である請求項１ないし請求項３のいずれかに記載の圧電薄膜デバイス。   4. The piezoelectric thin film device according to claim 1, wherein the digging width is 1 μm or more and 10 μm or less. 5.
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