JP6941981B2 - Piezoelectric thin film resonators, filters and multiplexers - Google Patents

Piezoelectric thin film resonators, filters and multiplexers Download PDF

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JP6941981B2
JP6941981B2 JP2017124887A JP2017124887A JP6941981B2 JP 6941981 B2 JP6941981 B2 JP 6941981B2 JP 2017124887 A JP2017124887 A JP 2017124887A JP 2017124887 A JP2017124887 A JP 2017124887A JP 6941981 B2 JP6941981 B2 JP 6941981B2
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耕平 伊藤
耕平 伊藤
英行 関根
英行 関根
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Taiyo Yuden Co Ltd
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本発明は、圧電薄膜共振器、フィルタおよびマルチプレクサに関し、例えば基板と下部電極との間に空隙が設けられた圧電薄膜共振器、フィルタおよびマルチプレクサに関する。 The present invention relates to piezoelectric thin film resonators, filters and multiplexers, for example, piezoelectric thin film resonators, filters and multiplexers in which a gap is provided between a substrate and a lower electrode.

圧電薄膜共振器は、例えば携帯電話等の無線機器のフィルタおよびデュプレクサとして用いられている。圧電薄膜共振器では、基板上に空隙を介し下部電極、圧電膜および上部電極が積層されている。基板と下部電極との間に空隙を形成する方法として、基板上に犠牲層を形成し犠牲層上に下部電極を形成する。その後、下部電極に形成された貫通孔を介し犠牲層にエッチング液を導入し、犠牲層を除去することで空隙を形成することが知られている(例えば特許文献1)。 Piezoelectric thin film resonators are used as filters and duplexers for wireless devices such as mobile phones. In the piezoelectric thin film resonator, a lower electrode, a piezoelectric film, and an upper electrode are laminated on a substrate via a gap. As a method of forming a gap between the substrate and the lower electrode, a sacrificial layer is formed on the substrate and a lower electrode is formed on the sacrificial layer. After that, it is known that an etching solution is introduced into the sacrificial layer through a through hole formed in the lower electrode to remove the sacrificial layer to form a void (for example, Patent Document 1).

特開2005−347898号公報Japanese Unexamined Patent Publication No. 2005-347988

エッチング液を導入するためには、下部電極に設けられた貫通孔の面積を大きくすることが好ましい。しかしながら、貫通孔を大きくするとチップ面積が大きくなる。 In order to introduce the etching solution, it is preferable to increase the area of the through hole provided in the lower electrode. However, increasing the through hole increases the chip area.

本発明は、上記課題に鑑みなされたものであり、圧電薄膜共振器を小型化することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to reduce the size of a piezoelectric thin film resonator.

本発明は、基板と、前記基板上に設けられた圧電膜と、前記圧電膜上に設けられた上部電極と、前記上部電極とで前記圧電膜の少なくとも一部を挟む共振領域を形成するように、前記基板と前記圧電膜との間に、前記基板との間に空隙を介し設けられ前記空隙とつながる第1貫通孔および第2貫通孔を前記共振領域外に有する下部電極と、を具備し、前記共振領域の外周のうち前記第1貫通孔に最も近い箇所における前記外周に沿った第1方向における前記第1貫通孔の第1幅は、前記第1方向に直交する第1直交方向における前記第1貫通孔の第2幅より大きく、前記外周のうち前記第2貫通孔に最も近い箇所における前記外周に沿った第2方向における前記第2貫通孔の第3幅は前記第1幅より小さく、前記第2方向に直交する第2直交方向における前記第2貫通孔の第4幅は前記第2幅より大きい圧電薄膜共振器である。 The present invention forms a resonance region in which at least a part of the piezoelectric film is sandwiched between the substrate, the piezoelectric film provided on the substrate, the upper electrode provided on the piezoelectric film, and the upper electrode. in, between the substrate and the piezoelectric film, provided through a gap between the substrate, a lower electrode having a first through-hole and the second through-hole leads the space outside the resonance region, the The first width of the first through hole in the first direction along the outer circumference at the portion of the outer circumference of the resonance region closest to the first through hole is the first orthogonality orthogonal to the first direction. The third width of the second through hole in the second direction along the outer circumference at a portion of the outer circumference closest to the second through hole, which is larger than the second width of the first through hole in the direction, is the first. The fourth width of the second through hole in the second orthogonal direction smaller than the width and orthogonal to the second direction is a piezoelectric thin film resonator larger than the second width.

上記構成において、前記第3幅と前記第4幅は等しい構成とすることができる。 In the above configuration, the third width and the fourth width can be equal to each other.

上記構成において、前記第1貫通孔および前記第2貫通孔は前記共振領域の中心を挟んで設けられている構成とすることができる。 In the above configuration, the first through hole and the second through hole may be provided with the center of the resonance region interposed therebetween.

上記構成において、前記共振領域は長手方向と短手方向を有し、前記第1貫通孔と前記第2貫通孔は前記長手方向に設けられている構成とすることができる。 In the above configuration, the resonance region has a longitudinal direction and a lateral direction, and the first through hole and the second through hole may be provided in the longitudinal direction.

上記構成において、前記第1貫通孔は前記共振領域に最も近い前記基板の端部と前記共振領域との間に設けられ、前記基板の端部と前記共振領域との間には、他の圧電薄膜共振器は設けられておらず、前記第2貫通孔と、前記第2貫通孔に対し前記共振領域と反対側の前記基板の端部と、の間には、他の圧電薄膜共振器が設けられている構成とすることができる。 In the above configuration, the first through hole is provided between the end of the substrate closest to the resonance region and the resonance region, and another piezoelectric is provided between the end of the substrate and the resonance region. A thin film resonator is not provided, and another piezoelectric thin film resonator is provided between the second through hole and the end portion of the substrate opposite to the resonance region with respect to the second through hole. It can be configured to be provided.

上記構成において、前記第1貫通孔は隣接する第1他の圧電薄膜共振器との間に設けられ、前記第1貫通孔と、前記第1他の圧電薄膜共振器が有する貫通孔のうち前記第1貫通孔に最も近い貫通孔と、の第1距離は、前記第2貫通孔と、前記第2貫通孔に最も近い第2他の圧電薄膜共振器が有する貫通孔のうち前記第2貫通孔に最も近い貫通孔と、の第2距離より短い構成とすることができる。
In the above structure, the first through-hole is found interposed between the first other piezoelectric thin-film resonators adjacent one of the the first through-hole, the first other through holes piezoelectric thin-film resonator has The first distance between the through hole closest to the first through hole is the second of the through holes of the second through hole and the second other piezoelectric thin film resonator closest to the second through hole. The configuration may be shorter than the second distance between the through hole closest to the through hole and the through hole.

上記構成において、前記第1貫通孔と前記第2貫通孔の面積は略同じである構成とすることができる。 In the above configuration, the areas of the first through hole and the second through hole can be substantially the same.

本発明は、上記圧電薄膜共振器を含むフィルタである。 The present invention is a filter including the piezoelectric thin film resonator.

本発明は、上記フィルタを含むマルチプレクサである。 The present invention is a multiplexer including the above filter.

本発明によれば、圧電薄膜共振器を小型化することができる。 According to the present invention, the piezoelectric thin film resonator can be miniaturized.

図1(a)は、実施例1における圧電薄膜共振器の平面図、図1(b)は、図1(a)のA−A断面図である。1 (a) is a plan view of the piezoelectric thin film resonator according to the first embodiment, and FIG. 1 (b) is a cross-sectional view taken along the line AA of FIG. 1 (a). 図2(a)から図2(d)は、実施例1に係る圧電薄膜共振器の製造方法を示す断面図である。2 (a) to 2 (d) are cross-sectional views showing a method of manufacturing the piezoelectric thin film resonator according to the first embodiment. 図3は、比較例1に係る圧電薄膜共振器の平面図である。FIG. 3 is a plan view of the piezoelectric thin film resonator according to Comparative Example 1. 図4(a)および図4(b)は、実施例2に係る圧電薄膜共振器の平面図である。4 (a) and 4 (b) are plan views of the piezoelectric thin film resonator according to the second embodiment. 図5は、実施例3に係るフィルタの平面図である。FIG. 5 is a plan view of the filter according to the third embodiment. 図6(a)および図6(b)は、図5の領域AおよびBの拡大図である。6 (a) and 6 (b) are enlarged views of regions A and B of FIG. 図7は、実施例4に係る圧電薄膜共振器の断面図である。FIG. 7 is a cross-sectional view of the piezoelectric thin film resonator according to the fourth embodiment. 図8は、実施例5に係るデュプレクサの回路図である。FIG. 8 is a circuit diagram of the duplexer according to the fifth embodiment.

以下、図面を参照し実施例について説明する。 Hereinafter, examples will be described with reference to the drawings.

図1(a)は、実施例1における圧電薄膜共振器の平面図、図1(b)は、図1(a)のA−A断面図である。共振領域50の長軸方向および短軸方向をX方向およびY方向、基板の法線方向をZ方向とすする。 1 (a) is a plan view of the piezoelectric thin film resonator according to the first embodiment, and FIG. 1 (b) is a cross-sectional view taken along the line AA of FIG. 1 (a). The major axis direction and the minor axis direction of the resonance region 50 are the X direction and the Y direction, and the normal direction of the substrate is the Z direction.

図1(a)および図1(b)に示すように、基板10上に、下部電極12が設けられている。基板10の平坦主面と下部電極12との間にドーム状の膨らみを有する空隙30が形成されている。ドーム状の膨らみとは、例えば空隙30の周辺では空隙30の高さが小さく、空隙30の内部ほど空隙30の高さが大きくなるような形状の膨らみである。 As shown in FIGS. 1A and 1B, a lower electrode 12 is provided on the substrate 10. A gap 30 having a dome-shaped bulge is formed between the flat main surface of the substrate 10 and the lower electrode 12. The dome-shaped bulge is, for example, a bulge having a shape in which the height of the void 30 is small around the void 30 and the height of the void 30 is increased toward the inside of the void 30.

下部電極12上に、圧電膜14が設けられている。圧電膜14上に上部電極16が設けられている。圧電膜14を挟み下部電極12と上部電極16とが対向する領域は共振領域50である。共振領域50の平面形状は、長軸52と短軸54を有する楕円形状である。長軸長はL1である。共振領域50は厚み縦振動モードの弾性波が共振する領域である。下部電極12上に配線26が設けられている。平面視において、共振領域50は空隙30に含まれている。 A piezoelectric film 14 is provided on the lower electrode 12. The upper electrode 16 is provided on the piezoelectric film 14. The region where the lower electrode 12 and the upper electrode 16 face each other with the piezoelectric film 14 interposed therebetween is the resonance region 50. The planar shape of the resonance region 50 is an elliptical shape having a major axis 52 and a minor axis 54. The major axis length is L1. The resonance region 50 is a region in which elastic waves in the thickness longitudinal vibration mode resonate. Wiring 26 is provided on the lower electrode 12. In a plan view, the resonance region 50 is included in the void 30.

空隙30は共振領域50の外まで設けられている。下部電極12は、共振領域50の外において空隙30につながる貫通孔35aを有している。貫通孔35aは共振領域50の長軸52の延長線上に共振領域50を挟み一対設けられている。貫通孔35aの平面形状は、共振領域50に沿った方向(Y方向)の幅R1がX方向の幅R2より大きい細長である。貫通孔35aは後述するように、犠牲層をエッチングするためのエッチング剤を導入するための導入路である。貫通孔35aを含む圧電薄膜共振器のX方向の長さはL0である。長さL0は長軸長L1と幅R2の2倍にその他の領域αを加えたL0=L1+2×R2+αである。 The gap 30 is provided to the outside of the resonance region 50. The lower electrode 12 has a through hole 35a connected to the gap 30 outside the resonance region 50. A pair of through holes 35a are provided on the extension line of the long axis 52 of the resonance region 50 with the resonance region 50 interposed therebetween. The planar shape of the through hole 35a is elongated in that the width R1 in the direction (Y direction) along the resonance region 50 is larger than the width R2 in the X direction. The through hole 35a is an introduction path for introducing an etching agent for etching the sacrificial layer, as will be described later. The length of the piezoelectric thin film resonator including the through hole 35a in the X direction is L0. The length L0 is L0 = L1 + 2 × R2 + α, which is twice the major axis length L1 and the width R2 plus the other region α.

基板10は、例えば膜厚が280μmのSi(シリコン)基板である。基板10としては、Si基板以外に、サファイア基板、スピネル基板、アルミナ基板、石英基板、ガラス基板、セラミック基板またはGaAs基板等を用いることができる。 The substrate 10 is, for example, a Si (silicon) substrate having a film thickness of 280 μm. As the substrate 10, in addition to the Si substrate, a sapphire substrate, a spinel substrate, an alumina substrate, a quartz substrate, a glass substrate, a ceramic substrate, a GaAs substrate, or the like can be used.

下部電極12は、例えば合計の膜厚が200nmであり、基板10側からCr(クロム)膜およびRu(ルテニウム)膜である。上部電極16は、例えば合計の膜厚が200nmであり、圧電膜14側からRu膜およびCr膜である。下部電極12および上部電極16としては、RuおよびCr以外にもAl(アルミニウム)、Ti(チタン)、Cu(銅)、Mo(モリブデン)、W(タングステン)、Ta(タンタル)、Pt(白金)、Rh(ロジウム)またはIr(イリジウム)等の単層膜またはこれらの積層膜を用いることができる。 The lower electrode 12 has, for example, a total film thickness of 200 nm, and is a Cr (chromium) film and a Ru (ruthenium) film from the substrate 10 side. The upper electrode 16 has, for example, a total film thickness of 200 nm, and is a Ru film and a Cr film from the piezoelectric film 14 side. In addition to Ru and Cr, the lower electrode 12 and the upper electrode 16 include Al (aluminum), Ti (titanium), Cu (copper), Mo (molybdenum), W (tungsten), Ta (tantalum), and Pt (platinum). , Rh (lodium) or Ir (iridium) or the like, or a laminated film thereof can be used.

圧電膜14は、例えば膜厚が1000nmの(002)方向を主軸とする窒化アルミニウム(AlN)を主成分とする窒化アルミニウム膜である。圧電膜14は、窒化アルミニウム以外にも、ZnO(酸化亜鉛)、PZT(チタン酸ジルコン酸鉛)、PbTiO3(チタン酸鉛)等を用いることができる。また、例えば、圧電膜14は、窒化アルミニウムを主成分とし、共振特性の向上または圧電性の向上のため他の元素を含んでもよい。例えば、添加元素として、Sc(スカンジウム)、2族または12族の元素と4族の元素との2つの元素、または2族または12族と5族との2つの元素を用いることにより、圧電膜14の圧電性が向上する。このため、圧電薄膜共振器の実効的電気機械結合係数を向上できる。2族の元素は、例えばCa(カルシウム)、Mg(マグネシウム)、Sr(ストロンチウム)であり12族元素は例えばZn(亜鉛)である。4族の元素は、例えばTi、Zr(ジルコニウム)またはHf(ハフニウム)である。5族の元素は、例えばTa、Nb(ニオブ)またはV(バナジウム)である。さらに、圧電膜14は、窒化アルミニウムを主成分とし、B(ボロン)を含んでもよい。 The piezoelectric film 14 is, for example, an aluminum nitride film containing aluminum nitride (AlN) as a main component having a film thickness of 1000 nm in the (002) direction as a main axis. In addition to aluminum nitride, ZnO (zinc oxide), PZT (lead zirconate titanate), PbTiO 3 (lead titanate) and the like can be used as the piezoelectric film 14. Further, for example, the piezoelectric film 14 may contain aluminum nitride as a main component and may contain other elements in order to improve the resonance characteristics or the piezoelectricity. For example, by using Sc (scandium), two elements of Group 2 or Group 12 and Group 4 elements, or two elements of Group 2 or Group 12 and Group 5, as the additive element, a piezoelectric film is used. The piezoelectricity of 14 is improved. Therefore, the effective electromechanical coupling coefficient of the piezoelectric thin film resonator can be improved. Group 2 elements are, for example, Ca (calcium), Mg (magnesium), Sr (strontium), and Group 12 elements are, for example, Zn (zinc). Group 4 elements are, for example, Ti, Zr (zirconium) or Hf (hafnium). Group 5 elements are, for example, Ta, Nb (niobium) or V (vanadium). Further, the piezoelectric film 14 contains aluminum nitride as a main component and may contain B (boron).

配線26は、例えば下部電極12側から膜厚が100nmのTi膜および膜厚が600nmのAu(金)膜である。配線26は、Cu(銅)膜およびAl(アルミニウム)膜等の低抵抗の膜が含まれればよい。空隙30の高さは例えば数10nmから数100nmである。貫通孔35aの幅R1およびR2は例えばそれぞれ16μmおよび4μmである。各層の膜厚は、所望の共振特性を得るため適宜設定することができる。 The wiring 26 is, for example, a Ti film having a film thickness of 100 nm and an Au (gold) film having a film thickness of 600 nm from the lower electrode 12 side. The wiring 26 may include a low resistance film such as a Cu (copper) film and an Al (aluminum) film. The height of the void 30 is, for example, several tens of nm to several hundred nm. The widths R1 and R2 of the through hole 35a are, for example, 16 μm and 4 μm, respectively. The film thickness of each layer can be appropriately set in order to obtain desired resonance characteristics.

[実施例1の製造方法]
図2(a)から図2(d)は、実施例1に係る圧電薄膜共振器の製造方法を示す断面図である。図2(a)に示すように、基板10上に、犠牲層38を例えばスパッタリング法、真空蒸着法またはCVD(Chemical Vapor Deposition)法を用い形成する。犠牲層38は、例えば膜厚が60nmのMgO(酸化マグネシウム)膜である。犠牲層38は、例えばZnO膜、Ge膜または酸化シリコン膜でもよい。犠牲層38の膜厚は例えば10nmから100nmでもよい。犠牲層38を例えばフォトリソグラフィ法およびエッチング法を用い所望の形状にパターニングする。犠牲層38は空隙30となる領域に設けられる。
[Manufacturing method of Example 1]
2 (a) to 2 (d) are cross-sectional views showing a method of manufacturing the piezoelectric thin film resonator according to the first embodiment. As shown in FIG. 2A, the sacrificial layer 38 is formed on the substrate 10 by using, for example, a sputtering method, a vacuum deposition method, or a CVD (Chemical Vapor Deposition) method. The sacrificial layer 38 is, for example, an MgO (magnesium oxide) film having a film thickness of 60 nm. The sacrificial layer 38 may be, for example, a ZnO film, a Ge film, or a silicon oxide film. The film thickness of the sacrificial layer 38 may be, for example, 10 nm to 100 nm. The sacrificial layer 38 is patterned into a desired shape using, for example, a photolithography method and an etching method. The sacrificial layer 38 is provided in a region that becomes a gap 30.

図2(b)に示すように、基板10上に犠牲層38を覆うように下部電極12を例えばスパッタリング法、真空蒸着法またはCVD法を用い形成する。下部電極12を例えばフォトリソグラフィ法およびエッチング法を用い所望の形状にパターニングする。これにより下部電極12に貫通孔35aが形成される。下部電極12は、リフトオフ法により形成してもよい。 As shown in FIG. 2B, the lower electrode 12 is formed on the substrate 10 so as to cover the sacrificial layer 38 by using, for example, a sputtering method, a vacuum vapor deposition method, or a CVD method. The lower electrode 12 is patterned into a desired shape by using, for example, a photolithography method and an etching method. As a result, a through hole 35a is formed in the lower electrode 12. The lower electrode 12 may be formed by a lift-off method.

図2(c)に示すように、基板10上に下部電極12を覆うように圧電膜14および上部電極16を例えばスパッタリング法、真空蒸着法またはCVD法を用い形成する。 As shown in FIG. 2C, the piezoelectric film 14 and the upper electrode 16 are formed on the substrate 10 so as to cover the lower electrode 12 by using, for example, a sputtering method, a vacuum deposition method, or a CVD method.

図2(d)に示すように、上部電極16および圧電膜14を例えばフォトリソグラフィ法およびエッチング法を用い所望の形状にパターニングする。上部電極16は、リフトオフ法により形成してもよい。下部電極12上に配線26を例えば真空蒸着法およびリフトオフ法を用い形成する。配線26は、スパッタリング法、真空蒸着法またはCVD法、並びにフォトリソグラフィ法およびエッチング法を用い形成してもよい。 As shown in FIG. 2D, the upper electrode 16 and the piezoelectric film 14 are patterned into a desired shape by using, for example, a photolithography method and an etching method. The upper electrode 16 may be formed by a lift-off method. The wiring 26 is formed on the lower electrode 12 by using, for example, a vacuum deposition method and a lift-off method. The wiring 26 may be formed by using a sputtering method, a vacuum vapor deposition method or a CVD method, and a photolithography method and an etching method.

貫通孔35aを介し、犠牲層38をエッチング液により除去する。下部電極12、圧電膜14および上部電極16の内部応力を圧縮応力としておくことで、下部電極12が基板10の反対側に基板10から離れるように膨れる。下部電極12と基板10との間にドーム状の膨らみを有する空隙30が形成される。犠牲層38がMgOの場合、犠牲層38のエッチング液として例えば硝酸系溶液を用いる。以上により、実施例1の圧電薄膜共振器が作製される。 The sacrificial layer 38 is removed by the etching solution through the through hole 35a. By setting the internal stresses of the lower electrode 12, the piezoelectric film 14, and the upper electrode 16 as compressive stresses, the lower electrode 12 swells on the opposite side of the substrate 10 so as to be separated from the substrate 10. A gap 30 having a dome-shaped bulge is formed between the lower electrode 12 and the substrate 10. When the sacrificial layer 38 is MgO, for example, a nitric acid-based solution is used as the etching solution for the sacrificial layer 38. As described above, the piezoelectric thin film resonator of Example 1 is manufactured.

[比較例1]
図3は、比較例1に係る圧電薄膜共振器の平面図である。図3に示すように、貫通孔35bの平面形状は円形であり、幅R1とR2とは略同じである。貫通孔35bの平面視の面積が小さくなると、貫通孔35bを介し犠牲層38にエッチング液が効率よく導入できない。また、フォトリソグラフィおよびエッチングが難しくなる。このため、貫通孔35bの面積は一定以上であることが好ましい。
[Comparative Example 1]
FIG. 3 is a plan view of the piezoelectric thin film resonator according to Comparative Example 1. As shown in FIG. 3, the planar shape of the through hole 35b is circular, and the widths R1 and R2 are substantially the same. When the area of the through hole 35b in a plan view becomes small, the etching solution cannot be efficiently introduced into the sacrificial layer 38 through the through hole 35b. It also makes photolithography and etching difficult. Therefore, the area of the through hole 35b is preferably equal to or larger than a certain area.

しかしながら、比較例1のように貫通孔35bを円形とすると、幅R2が大きくなる。このため、圧電薄膜共振器の長軸方向の長さL0=L1+2×R2+αが大きくなってしまう。 However, if the through hole 35b is circular as in Comparative Example 1, the width R2 becomes large. Therefore, the length L0 = L1 + 2 × R2 + α in the long axis direction of the piezoelectric thin film resonator becomes large.

[実施例1の効果]
実施例1によれば、貫通孔35a(第1貫通孔)は、X方向(共振領域50に沿う方向)の幅R1がY方向(沿う方向に交差する方向)の幅R2より大きい。これにより、貫通孔35aの面積が比較例1の貫通孔35bの面積とほぼ同じであっても幅R2を小さくできる。よって、圧電薄膜共振器のX方向の長さL0=L1+2×R2+αを比較例1より小さくできる。例えば実施例1および比較例1の幅R2をそれぞれ4μmおよび8μmとすると、L0を8μm小さくできる。よって、圧電薄膜共振器を小型化できる。また、比較例1と貫通孔35aの面積がほぼ同じであるため、犠牲層38のエッチング液を効率よく導入できる。
[Effect of Example 1]
According to the first embodiment, in the through hole 35a (first through hole), the width R1 in the X direction (direction along the resonance region 50) is larger than the width R2 in the Y direction (direction intersecting the along direction). As a result, the width R2 can be reduced even if the area of the through hole 35a is substantially the same as the area of the through hole 35b of Comparative Example 1. Therefore, the length L0 = L1 + 2 × R2 + α of the piezoelectric thin film resonator in the X direction can be made smaller than that of Comparative Example 1. For example, if the widths R2 of Example 1 and Comparative Example 1 are 4 μm and 8 μm, respectively, L0 can be reduced by 8 μm. Therefore, the piezoelectric thin film resonator can be miniaturized. Further, since the area of the through hole 35a is almost the same as that of Comparative Example 1, the etching solution of the sacrificial layer 38 can be efficiently introduced.

貫通孔35aの平面形状として外周は曲線の形状(円をつぶしたような形状)を例に説明したが、貫通孔35aは長方形等の多角形でもよい。貫通孔35aは共振領域50の外にあれば、貫通孔35aの位置はいずれでもよい。また、貫通孔35aの個数は1個でもよく3個以上でもよい。共振領域50の平面形状が楕円形状のように細長い場合、エッチング液を効率的に犠牲層38に導入するためには、貫通孔35aは長軸の延長線上に2個あることが好ましい。 As the planar shape of the through hole 35a, a curved shape (a shape like a crushed circle) is described as an example of the outer circumference, but the through hole 35a may be a polygon such as a rectangle. As long as the through hole 35a is outside the resonance region 50, the position of the through hole 35a may be arbitrary. Further, the number of through holes 35a may be one or three or more. When the planar shape of the resonance region 50 is elongated such as an elliptical shape, it is preferable that there are two through holes 35a on the extension line of the long axis in order to efficiently introduce the etching solution into the sacrificial layer 38.

図4(a)および図4(b)は、実施例2に係る圧電薄膜共振器の平面図である。図4(a)および図4(b)のように、2つの貫通孔35aおよび35bの形状が異なる。貫通孔35aの幅R1は貫通孔35bの幅R1より大きく、貫通孔35aの幅R2は貫通孔35bの幅R2より小さい。例えば、図4(a)では、貫通孔35aの幅R1およびR2はそれぞれ16μmおよび4μmである。図4(b)では、貫通孔35aの幅R1およびR2はそれぞれ32μmおよび2μmである。図4(a)および図4(b)では、貫通孔35aの幅R1およびR2はいずれも8μmである。その他の構成は実施例1と同じであり説明を省略する。 4 (a) and 4 (b) are plan views of the piezoelectric thin film resonator according to the second embodiment. As shown in FIGS. 4A and 4B, the shapes of the two through holes 35a and 35b are different. The width R1 of the through hole 35a is larger than the width R1 of the through hole 35b, and the width R2 of the through hole 35a is smaller than the width R2 of the through hole 35b. For example, in FIG. 4A, the widths R1 and R2 of the through hole 35a are 16 μm and 4 μm, respectively. In FIG. 4B, the widths R1 and R2 of the through hole 35a are 32 μm and 2 μm, respectively. In FIGS. 4A and 4B, the widths R1 and R2 of the through hole 35a are both 8 μm. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

図5は、実施例3に係るフィルタの平面図である。図6(a)および図6(b)は、図5の領域AおよびBの拡大図である。図5に示すように、基板10上に圧電薄膜共振器18、配線26およびパッド22が設けられている。圧電薄膜共振器18は実施例1、2および比較例1に係る圧電薄膜共振器である。配線26は圧電薄膜共振器18間を電気的に接続する。パッド22は、外部と接続するための端子であり、例えばバンプまたはボンディングワイヤ等が接合する。配線26およびパッド22は、例えば金膜、アルミニウム膜または銅膜等の金属層である。 FIG. 5 is a plan view of the filter according to the third embodiment. 6 (a) and 6 (b) are enlarged views of regions A and B of FIG. As shown in FIG. 5, a piezoelectric thin film resonator 18, a wiring 26, and a pad 22 are provided on the substrate 10. The piezoelectric thin film resonator 18 is the piezoelectric thin film resonator according to Examples 1 and 2 and Comparative Example 1. The wiring 26 electrically connects the piezoelectric thin film resonators 18. The pad 22 is a terminal for connecting to the outside, and for example, a bump, a bonding wire, or the like is bonded. The wiring 26 and the pad 22 are metal layers such as, for example, a gold film, an aluminum film, or a copper film.

圧電薄膜共振器18は、直列共振器S1からS4および並列共振器P1からP4を含む。パッド22は、入力端子In、出力端子Outおよびグランド端子Gndを含む。入力端子Inと出力端子Outとの間に直列共振器S1からS4が直列に、並列共振器P1からP4が並列に接続されている。直列共振器S4は直列に分割されている。 The piezoelectric thin film resonator 18 includes series resonators S1 to S4 and parallel resonators P1 to P4. The pad 22 includes an input terminal In, an output terminal Out, and a ground terminal Gnd. The series resonators S1 to S4 are connected in series, and the parallel resonators P1 to P4 are connected in parallel between the input terminal In and the output terminal Out. The series resonator S4 is divided in series.

図6(a)に示すように、隣接する直列共振器S3と並列共振器P3との間で貫通孔35aが近接する。貫通孔35aが円形の場合、直列共振器S3と並列共振器P3の貫通孔35aが一体となってしまう。この場合、犠牲層38の除去が安定化しない。貫通孔35aを近接させないためには直列共振器S3と並列共振器P3とを離すことになり、チップサイズが大きくなる。そこで、貫通孔35aの平面形状を円形でなく実施例1または2のように細長い形状とする。これにより、チップサイズを大きくすることなく、直列共振器S3と並列共振器P3の貫通孔35aが一体となることを抑制でき、チップ面積を小さくできる。 As shown in FIG. 6A, the through hole 35a is close to the adjacent series resonator S3 and the parallel resonator P3. When the through hole 35a is circular, the through hole 35a of the series resonator S3 and the parallel resonator P3 are integrated. In this case, the removal of the sacrificial layer 38 is not stabilized. In order to keep the through holes 35a away from each other, the series resonator S3 and the parallel resonator P3 are separated from each other, and the chip size becomes large. Therefore, the planar shape of the through hole 35a is not circular but elongated as in Example 1 or 2. As a result, it is possible to prevent the series resonator S3 and the through hole 35a of the parallel resonator P3 from being integrated without increasing the chip size, and the chip area can be reduced.

図6(b)に示すように、基板10(すなわちチップ)の端部にはスクライブライン11が設けられている。スクライブライン11はチップを個片化するときの切断領域である。直列共振器S2と並列共振器P3の貫通孔35aが基板10の端部に近接している。スクライブライン11から一定距離L3は、パターンの配置を許容しない領域である。パターンが基板10の端部に形成されると、パターン欠け等が生じる可能性があるため、このような配置を許可しない領域を設ける。比較例1のように円形の貫通孔35bの場合、スクライブライン11から距離L3を確保しようとすると、直列共振器S2と並列共振器P3をスクライブライン11から離すことになり、チップ面積が大きくなる。貫通孔35aを実施例1または2のように細長い形状とする。これにより、チップ面積を小さくできる。 As shown in FIG. 6B, a scribe line 11 is provided at the end of the substrate 10 (that is, a chip). The scribe line 11 is a cutting region when the chips are fragmented. The through hole 35a of the series resonator S2 and the parallel resonator P3 is close to the end of the substrate 10. The constant distance L3 from the scribe line 11 is an area where the arrangement of the pattern is not allowed. If the pattern is formed at the end of the substrate 10, the pattern may be chipped or the like. Therefore, a region that does not allow such arrangement is provided. In the case of the circular through hole 35b as in Comparative Example 1, when trying to secure the distance L3 from the scribe line 11, the series resonator S2 and the parallel resonator P3 are separated from the scribe line 11, and the chip area becomes large. .. The through hole 35a has an elongated shape as in Example 1 or 2. As a result, the chip area can be reduced.

細長い貫通孔35aの反対側の貫通孔は細長い貫通孔35aでもよいし、円形の貫通孔35bでもよい。 The through hole on the opposite side of the elongated through hole 35a may be an elongated through hole 35a or a circular through hole 35b.

実施例2のように、貫通孔35b(第2貫通孔)の幅R1は貫通孔35a(第1貫通孔)の幅R1より小さく、貫通孔35bの幅R2は貫通孔35aの幅R2より小さい。このように、貫通孔の形状を異ならせることで、貫通孔の形状を柔軟にすることができ、チップサイズを小さくできる。 As in the second embodiment, the width R1 of the through hole 35b (second through hole) is smaller than the width R1 of the through hole 35a (first through hole), and the width R2 of the through hole 35b is smaller than the width R2 of the through hole 35a. .. By making the shape of the through hole different in this way, the shape of the through hole can be made flexible and the chip size can be reduced.

貫通孔35aおよび35bは共振領域50の中心を挟んで設けられている。これにより、犠牲層38を効率よく除去できる。しかし、貫通孔の分圧電薄膜共振器が長くなる。よって、貫通孔の少なくとも一方を細長い貫通孔35aとすることが好ましい。なお、共振領域50の中心は幾何学的な中心でなくてもよい。 The through holes 35a and 35b are provided so as to sandwich the center of the resonance region 50. As a result, the sacrificial layer 38 can be efficiently removed. However, the piezoelectric thin film resonator becomes longer due to the through hole. Therefore, it is preferable that at least one of the through holes is an elongated through hole 35a. The center of the resonance region 50 does not have to be the geometric center.

特に、共振領域50は長手方向と短手方向を有し、貫通孔35aおよび35bが長手方向に設けられている。これにより、犠牲層38を効率よく除去できる。しかし、圧電薄膜共振器の長さL0が大きくなる。よって、貫通孔の少なくとも一方を貫通孔35aとすることが好ましい。共振領域50は楕円形状以外に長方形等の長手方向を有する形状であればよい。 In particular, the resonance region 50 has a longitudinal direction and a lateral direction, and through holes 35a and 35b are provided in the longitudinal direction. As a result, the sacrificial layer 38 can be efficiently removed. However, the length L0 of the piezoelectric thin film resonator becomes large. Therefore, it is preferable that at least one of the through holes is a through hole 35a. The resonance region 50 may have a shape having a longitudinal direction such as a rectangle in addition to the elliptical shape.

図6(a)のように、直列共振器S3の貫通孔35aは隣接する他の圧電薄膜共振器である並列共振器P3との間に設けられている。このように、圧電薄膜共振器の間に位置する貫通孔35aを細長くすることで、チップ面積を小さくできる。 As shown in FIG. 6A, the through hole 35a of the series resonator S3 is provided between the parallel resonator P3, which is another adjacent piezoelectric thin film resonator. In this way, the chip area can be reduced by elongated the through holes 35a located between the piezoelectric thin film resonators.

図6(b)のように、並列共振器P3の貫通孔35aは共振領域50に最も近い基板10の端部と共振領域50との間に設けられている。基板10の端部と共振領域50との間には、他の圧電薄膜共振器は設けられていない。このように、基板10の端部に近い貫通孔35aを細長くすることで、チップ面積を小さくできる。 As shown in FIG. 6B, the through hole 35a of the parallel resonator P3 is provided between the end portion of the substrate 10 closest to the resonance region 50 and the resonance region 50. No other piezoelectric thin film resonator is provided between the end of the substrate 10 and the resonance region 50. In this way, the chip area can be reduced by making the through hole 35a near the end of the substrate 10 elongated.

実施例3では、ラダー型フィルタを例に説明した。ラダー型フィルタの直列共振器および並列共振器の個数は適宜設定できる。実施例1から2およびその変形例の圧電薄膜共振器はラダー型フィルタ以外に適用してもよい。 In Example 3, a ladder type filter has been described as an example. The number of series resonators and parallel resonators of the ladder type filter can be set as appropriate. The piezoelectric thin film resonators of Examples 1 and 2 and their modifications may be applied to other than the ladder type filter.

実施例4は、空隙の構成を変えた例である。図7は、実施例4に係る圧電薄膜共振器の断面図である。図7に示すように、基板10の上面に窪みが形成されている。下部電極12は、基板10上に平坦に形成されている。これにより、空隙30が、基板10の窪みに形成されている。空隙30は共振領域50を含むように形成されている。その他の構成は、実施例1および2と同じであり説明を省略する。実施例4のように空隙30の形状は任意である。 Example 4 is an example in which the configuration of the void is changed. FIG. 7 is a cross-sectional view of the piezoelectric thin film resonator according to the fourth embodiment. As shown in FIG. 7, a recess is formed on the upper surface of the substrate 10. The lower electrode 12 is formed flat on the substrate 10. As a result, the gap 30 is formed in the recess of the substrate 10. The gap 30 is formed so as to include the resonance region 50. Other configurations are the same as those of the first and second embodiments, and the description thereof will be omitted. The shape of the void 30 is arbitrary as in the fourth embodiment.

実施例5はマルチプレクサの例である。図8は、実施例5に係るデュプレクサの回路図である。図5に示すように、共通端子Antと送信端子Txとの間に送信フィルタ40が接続されている。共通端子Antと受信端子Rxとの間に受信フィルタ42が接続されている。送信フィルタ40は、送信端子Txから入力された信号のうち送信帯域の信号を送信信号として共通端子Antに通過させ、他の周波数の信号を抑圧する。受信フィルタ42は、共通端子Antから入力された信号のうち受信帯域の信号を受信信号として受信端子Rxに通過させ、他の周波数の信号を抑圧する。送信フィルタ40および受信フィルタ42の少なくとも一方を実施例3のフィルタまたは実施例1、2および3の圧電薄膜共振器を含むフィルタとすることができる。 Example 5 is an example of a multiplexer. FIG. 8 is a circuit diagram of the duplexer according to the fifth embodiment. As shown in FIG. 5, a transmission filter 40 is connected between the common terminal Ant and the transmission terminal Tx. A reception filter 42 is connected between the common terminal Ant and the reception terminal Rx. The transmission filter 40 passes a signal in the transmission band among the signals input from the transmission terminal Tx to the common terminal Ant as a transmission signal, and suppresses signals of other frequencies. The reception filter 42 passes a signal in the reception band among the signals input from the common terminal Ant to the reception terminal Rx as a reception signal, and suppresses signals of other frequencies. At least one of the transmission filter 40 and the reception filter 42 can be a filter of Example 3 or a filter including the piezoelectric thin film resonators of Examples 1, 2 and 3.

マルチプレクサの例としてデュプレクサを説明したが、トリプレクサまたはクワッドプレクサでもよい。 Although the duplexer has been described as an example of the multiplexer, it may be a triplexer or a quadplexer.

以上、本発明の実施例について詳述したが、本発明はかかる特定の実施例に限定されるものではなく、特許請求の範囲に記載された本発明の要旨の範囲内において、種々の変形・変更が可能である。 Although the examples of the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and modifications are made within the scope of the gist of the present invention described in the claims. It can be changed.

10 基板
12 下部電極
14 圧電膜
16 上部電極
18 圧電薄膜共振器
22 パッド
26 配線
30 空隙
40 送信フィルタ
42 受信フィルタ
50 共振領域
10 Substrate 12 Lower electrode 14 Piezoelectric film 16 Upper electrode 18 Piezoelectric thin film resonator 22 Pad 26 Wiring 30 Void 40 Transmission filter 42 Reception filter 50 Resonance region

Claims (9)

基板と、
前記基板上に設けられた圧電膜と、
前記圧電膜上に設けられた上部電極と、
前記上部電極とで前記圧電膜の少なくとも一部を挟む共振領域を形成するように、前記基板と前記圧電膜との間に、前記基板との間に空隙を介し設けられ前記空隙とつながる第1貫通孔および第2貫通孔を前記共振領域外に有する下部電極と、
を具備し、
前記共振領域の外周のうち前記第1貫通孔に最も近い箇所における前記外周に沿った第1方向における前記第1貫通孔の第1幅は、前記第1方向に直交する第1直交方向における前記第1貫通孔の第2幅より大きく、
前記外周のうち前記第2貫通孔に最も近い箇所における前記外周に沿った第2方向における前記第2貫通孔の第3幅は前記第1幅より小さく、前記第2方向に直交する第2直交方向における前記第2貫通孔の第4幅は前記第2幅より大きい圧電薄膜共振器。
With the board
With the piezoelectric film provided on the substrate,
The upper electrode provided on the piezoelectric film and
To form at least a portion of the sandwich resonance region of the piezoelectric film and the upper electrode, between the substrate and the piezoelectric film, provided through a gap between the substrate, the leads and the air gap A lower electrode having a first through hole and a second through hole outside the resonance region,
Equipped with
The first width of the first through hole in the first direction along the outer circumference at the portion closest to the first through hole in the outer circumference of the resonance region is the said in the first orthogonal direction orthogonal to the first direction. Larger than the second width of the first through hole,
The third width of the second through hole in the second direction along the outer circumference at the portion of the outer circumference closest to the second through hole is smaller than the first width and is orthogonal to the second direction. A piezoelectric thin film resonator in which the fourth width of the second through hole in the direction is larger than the second width.
前記第3幅と前記第4幅は等しい請求項1記載の圧電薄膜共振器。 The piezoelectric thin film resonator according to claim 1, wherein the third width and the fourth width are equal. 前記第1貫通孔および前記第2貫通孔は前記共振領域の中心を挟んで設けられている請求項2記載の圧電薄膜共振器。 The piezoelectric thin film resonator according to claim 2, wherein the first through hole and the second through hole are provided with the center of the resonance region interposed therebetween. 前記共振領域は長手方向と短手方向を有し、前記第1貫通孔と前記第2貫通孔は前記長手方向に設けられている請求項3記載の圧電薄膜共振器。 The piezoelectric thin film resonator according to claim 3, wherein the resonance region has a longitudinal direction and a lateral direction, and the first through hole and the second through hole are provided in the longitudinal direction. 前記第1貫通孔は前記共振領域に最も近い前記基板の端部と前記共振領域との間に設けられ、
前記基板の端部と前記共振領域との間には、他の圧電薄膜共振器は設けられておらず、
前記第2貫通孔と、前記第2貫通孔に対し前記共振領域と反対側の前記基板の端部と、の間には、他の圧電薄膜共振器が設けられている請求項1から4のいずれか一項記載の圧電薄膜共振器。
The first through hole is provided between the edge of the substrate closest to the resonance region and the resonance region.
No other piezoelectric thin film resonator is provided between the edge of the substrate and the resonance region .
Said second through hole, the second through-hole with respect to the resonance region and the opposite side of the end portion of the substrate, between, claims 1 to 4 in which the other piezoelectric thin-film resonators are provided The piezoelectric thin film resonator according to any one item.
前記第1貫通孔は隣接する第1他の圧電薄膜共振器との間に設けられ、
前記第1貫通孔と、前記第1他の圧電薄膜共振器が有する貫通孔のうち前記第1貫通孔に最も近い貫通孔と、の第1距離は、前記第2貫通孔と、前記第2貫通孔に最も近い第2他の圧電薄膜共振器が有する貫通孔のうち前記第2貫通孔に最も近い貫通孔と、の第2距離より短い請求項1から4のいずれか一項記載の圧電薄膜共振器。
The first through hole et provided between the first other piezoelectric thin-film resonators adjacent is,
The first distance between the first through hole and the through hole closest to the first through hole among the through holes of the first and other piezoelectric thin film resonators is the second through hole and the second through hole. The piezoelectric according to any one of claims 1 to 4, which is shorter than the second distance between the through hole of the second other piezoelectric thin film resonator closest to the through hole and the through hole closest to the second through hole. Thin film resonator.
前記第1貫通孔と前記第2貫通孔の面積は略同じである請求項2から4のいずれか一項に記載の圧電薄膜共振器。 The piezoelectric thin film resonator according to any one of claims 2 to 4, wherein the areas of the first through hole and the second through hole are substantially the same. 請求項1から7のいずれか一項記載の圧電薄膜共振器を含むフィルタ。 A filter including the piezoelectric thin film resonator according to any one of claims 1 to 7. 請求項8記載のフィルタを含むマルチプレクサ。 A multiplexer containing the filter according to claim 8.
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