JP6401088B2

JP6401088B2 - Elastic wave device

Info

Publication number: JP6401088B2
Application number: JP2015055407A
Authority: JP
Inventors: 啓土門; 龍一岡村
Original assignee: Taiyo Yuden Co Ltd
Current assignee: Taiyo Yuden Co Ltd
Priority date: 2015-03-18
Filing date: 2015-03-18
Publication date: 2018-10-03
Anticipated expiration: 2035-03-18
Also published as: JP2016178387A

Description

本発明は、弾性波デバイスに関し、例えば圧電基板上に櫛型電極を備える弾性波デバイスに関する。 The present invention relates to an acoustic wave device, for example, an acoustic wave device including a comb-shaped electrode on a piezoelectric substrate.

弾性波を用いた弾性波デバイスとして、圧電基板上に１組の櫛型電極からなるＩＤＴ（Interdigital Transducer）を有する弾性表面波デバイスがある。弾性表面波デバイスは、移動体通信機器等に用いられている。 As an acoustic wave device using an acoustic wave, there is a surface acoustic wave device having an IDT (Interdigital Transducer) composed of a pair of comb-shaped electrodes on a piezoelectric substrate. Surface acoustic wave devices are used in mobile communication devices and the like.

１組の櫛型電極は、それぞれ複数の電極指と複数の電極指が共通に接続されたバスバーとを備えている。また、バスバーに複数のダミー電極指が共通に接続されることもある。電極指とバスバーとの間、または電極指とダミー電極指との間がギャップ領域である。特許文献１には、弾性波の交差領域からの漏洩を抑制するため、１組の櫛型電極のギャップ領域に絶縁膜体を埋め込むことが記載されている。また、特許文献２には、バスバーを電極指より厚くすることにより、弾性波の漏洩を抑制することが記載されている。 Each set of comb electrodes includes a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are connected in common. In addition, a plurality of dummy electrode fingers may be commonly connected to the bus bar. The gap region is between the electrode finger and the bus bar or between the electrode finger and the dummy electrode finger. Patent Document 1 describes that an insulating film body is embedded in a gap region of a pair of comb-shaped electrodes in order to suppress leakage from an intersecting region of elastic waves. Japanese Patent Application Laid-Open No. H10-228707 describes that elastic wave leakage is suppressed by making the bus bar thicker than the electrode fingers.

特開２００９−２７８４２９号公報JP 2009-278429 A 特開２００７−１１０３４２号公報JP 2007-110342 A

特許文献１および２によれば、弾性波の複数の電極指の先端からバスバー方向への漏洩を抑制し、損失を低減できる。しかしながら、特許文献１および２では、弾性波の漏洩の抑制は十分でなく、損失の低減も十分ではない。 According to Patent Documents 1 and 2, leakage of elastic waves from the tips of a plurality of electrode fingers in the bus bar direction can be suppressed, and loss can be reduced. However, in Patent Documents 1 and 2, suppression of elastic wave leakage is not sufficient, and loss reduction is not sufficient.

本発明は、上記課題に鑑みなされたものであり、弾性波の漏洩を抑制し、損失を低減することを目的とする。 This invention is made | formed in view of the said subject, and it aims at suppressing the leakage of an elastic wave and reducing a loss.

本発明は、圧電基板上に設けられ、それぞれ複数の電極指と前記複数の電極指が共通に接続されたバスバーとを含み、互いの前記複数の電極指と前記バスバーまたは前記バスバーに共通に接続された複数のダミー電極指とが向かい合って配置された１組の櫛型電極と、それぞれが、前記複数の電極指の先端と前記バスバーまたは前記複数のダミー電極指の先端との間に位置する複数の隙間の少なくとも一部を覆い、前記複数の電極指の配列方向に互いに離れて設けられた複数の第１付加膜と、平面視において前記バスバーおよび前記バスバーの外側の少なくとも一方に重なるように、前記配列方向に互いに離れて設けられた複数の第２付加膜と、を具備し、前記複数の第２付加膜の前記配列方向のピッチは、前記１組の櫛型電極のうち一方の櫛型電極の複数の電極指の前記配列方向のピッチと同じであることを特徴とする弾性波デバイスである。 The present invention includes a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are connected in common, each connected to the plurality of electrode fingers and the bus bar or the bus bar. A pair of comb-shaped electrodes arranged with the plurality of dummy electrode fingers facing each other, and each is positioned between the tips of the plurality of electrode fingers and the tips of the bus bar or the plurality of dummy electrode fingers A plurality of first additional films that cover at least a part of the plurality of gaps and are separated from each other in the arrangement direction of the plurality of electrode fingers, and overlap at least one of the bus bar and the outside of the bus bar in a plan view. , anda plurality of second additional film provided apart from each other in the array direction, the array direction of the pitch of the plurality of second additional film is of one of said pair of interdigital electrodes An elastic wave device, characterized in that it is the same as the arrangement direction of the pitch of the plurality of electrode fingers of the type electrodes.

上記構成において、前記１組の櫛型電極のうち一方の櫛型電極のバスバー側に設けられた複数の第２付加膜は、前記複数の電極指の延伸方向からみて前記一方の櫛型電極のバスバー側に設けられた複数の第１付加膜の間に少なくとも一部が重なるように設けられている構成とすることができる。 In the above-described configuration, the plurality of second additional films provided on the bus bar side of one comb-shaped electrode of the pair of comb-shaped electrodes are formed on the one comb-shaped electrode as viewed from the extending direction of the plurality of electrode fingers . It can be set as the structure provided so that at least one part may overlap between several 1st addition films | membranes provided in the bus-bar side .

上記構成において、前記複数の第２付加膜は、平面視において少なくとも前記バスバーに重なるように設けられている構成とすることができる。 In the above configuration, the plurality of second additional films may be provided so as to overlap at least the bus bar in a plan view.

上記構成において、前記１組の櫛型電極のうち一方の櫛型電極のバスバー側に設けられた複数の第２付加膜は、前記複数の電極指の延伸方向からみて前記一方の櫛型電極のバスバー側に設けられた複数の第１付加膜の間に少なくとも一部が重なり、平面視において少なくとも前記一方の櫛型電極のバスバーに重なるように設けられている構成とすることができる。 In the above-described configuration, the plurality of second additional films provided on the bus bar side of one comb-shaped electrode of the pair of comb-shaped electrodes are formed on the one comb-shaped electrode as viewed from the extending direction of the plurality of electrode fingers . at least partially overlap between the plurality of first additional film provided on the bus bar side, it can be configured to provided so as to overlap the bus bar of at least the one comb electrode in a plan view.

上記構成において、前記複数の第２付加膜は、前記複数の電極指の延伸方向に複数設けられている構成とすることができる。 The said structure WHEREIN: The said some 2nd addition film | membrane can be set as the structure provided with two or more in the extending | stretching direction of these electrode fingers.

上記構成において、前記延伸方向に設けられた複数の第２付加膜は、前記配列方向に互いにずれて設けられている構成とすることができる。 The said structure WHEREIN: The some 2nd additional film | membrane provided in the said extending | stretching direction can be set as the structure shifted | deviated mutually from the said sequence direction.

上記構成において、前記１組の櫛型電極の前記配列方向に設けられ、複数の電極指と前記複数の電極指が接続されたバスバーとを含む反射器を具備し、前記複数の第２付加膜は、平面視において前記反射器のバスバーおよび前記反射器のバスバーの外側の少なくとも一方に重なるように設けられている構成とすることができる。 In the above-described configuration, the reflector includes a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are connected, provided in the arrangement direction of the pair of comb-shaped electrodes, and the plurality of second additional films. Can be configured to overlap with at least one of the bus bar of the reflector and the outer side of the bus bar of the reflector in a plan view.

上記構成において、前記複数の第２付加膜は、平面視において、前記反射器の前記配列方向の最も外側の電極指および前記最も外側の電極指の外側の少なくとも一方に重なるように設けられている構成とすることができる。 In the above configuration, the plurality of second additional films are provided so as to overlap at least one of the outermost electrode finger in the arrangement direction of the reflector and the outer side of the outermost electrode finger in plan view. It can be configured.

本発明によれば、弾性波の漏洩を抑制し、損失を低減することができる。 According to the present invention, leakage of elastic waves can be suppressed and loss can be reduced.

図１（ａ）は、比較例１に係る弾性波デバイスの平面図、図１（ｂ）は、図１（ａ）のＡ−Ａ断面図、図１（ｃ）は、図１（ａ）のＢ−Ｂ断面図である。1A is a plan view of an acoustic wave device according to Comparative Example 1, FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 1C is FIG. It is BB sectional drawing of. 図２（ａ）は、実施例１に係る弾性波デバイスの平面図、図２（ｂ）は、図２（ａ）のＡ−Ａ断面図、図２（ｃ）は、図２（ａ）のＢ−Ｂ断面図である。2A is a plan view of the acoustic wave device according to the first embodiment, FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A, and FIG. 2C is FIG. 2A. It is BB sectional drawing of. 図３（ａ）は、実施例１の変形例１に係る弾性波デバイスの平面図、図３（ｂ）は、図３（ａ）のＡ−Ａ断面図、図３（ｃ）は、図３（ａ）のＢ−Ｂ断面図である。3A is a plan view of the acoustic wave device according to the first modification of the first embodiment, FIG. 3B is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. It is BB sectional drawing of 3 (a). 図４（ａ）は、実施例１の変形例２に係る弾性波デバイスの平面図、図４（ｂ）は、図４（ａ）のＡ−Ａ断面図、図４（ｃ）は、図４（ａ）のＢ−Ｂ断面図である。4A is a plan view of an acoustic wave device according to a second modification of the first embodiment, FIG. 4B is a cross-sectional view taken along the line AA in FIG. 4A, and FIG. It is BB sectional drawing of 4 (a). 図５（ａ）から図５（ｃ）は、それぞれ実施例１、実施例１の変形例３から４に係る弾性波デバイスの一部の平面図である。FIGS. 5A to 5C are plan views of a part of the acoustic wave device according to the first embodiment and the third to fourth modifications of the first embodiment, respectively. 図６（ａ）および図６（ｂ）は、実施例１に係る弾性波デバイスの一部の平面図である。FIG. 6A and FIG. 6B are plan views of a part of the acoustic wave device according to the first embodiment. 図７（ａ）および図７（ｂ）は、それぞれ実施例１の変形例５および６に係る弾性波デバイスの一部の平面図である。FIG. 7A and FIG. 7B are plan views of part of the acoustic wave device according to the fifth and sixth modifications of the first embodiment, respectively. 図８は、実施例２に係る弾性波デバイスの平面図である。FIG. 8 is a plan view of the acoustic wave device according to the second embodiment. 図９は、実施例２の変形例１に係る弾性波デバイスの平面図である。FIG. 9 is a plan view of the acoustic wave device according to the first modification of the second embodiment. 図１０は、実施例２の変形例２に係る弾性波デバイスの平面図である。FIG. 10 is a plan view of an acoustic wave device according to a second modification of the second embodiment. 図１１（ａ）から図１１（ｄ）は、実施例１、２およびその変形例における弾性波デバイスの製造方法を示す断面図（その１）である。FIG. 11A to FIG. 11D are cross-sectional views (No. 1) showing the method for manufacturing the acoustic wave device in Examples 1 and 2 and the modifications thereof. 図１２（ａ）から図１２（ｄ）は、実施例１、２およびその変形例における弾性波デバイスの製造方法を示す断面図（その２）である。FIG. 12A to FIG. 12D are cross-sectional views (part 2) showing the method for manufacturing the acoustic wave device in Examples 1 and 2 and the modifications thereof. 図１３は、実施例３に係る弾性波デバイスの平面図である。FIG. 13 is a plan view of the acoustic wave device according to the third embodiment. 図１４は、実施例４に係る弾性波デバイスの平面図である。FIG. 14 is a plan view of the acoustic wave device according to the fourth embodiment.

まず、比較例について説明する。図１（ａ）は、比較例１に係る弾性波デバイスの平面図、図１（ｂ）は、図１（ａ）のＡ−Ａ断面図、図１（ｃ）は、図１（ａ）のＢ−Ｂ断面図である。図１（ａ）においては、保護膜を透視して櫛型電極を示している。また、付加膜を透視し、櫛型電極を破線で示している。以下の平面図も同じである。図１（ａ）から図１（ｃ）に示すように、圧電基板１０上に金属膜３４からなる櫛型電極１８ａおよび１８ｂ、パッド２０ａおよび２０ｂ並びに反射器２６が形成されている。櫛型電極１８ａは、複数の電極指１２ａ、複数のダミー電極指１４ａおよびバスバー１６ａを備える。櫛型電極１８ｂは、複数の電極指１２ｂ、複数のダミー電極指１４ｂおよびバスバー１６ｂを備える。電極指１２ａおよびダミー電極指１４ａは、ほぼ互い違いに共通のバスバー１６ａに接続されている。電極指１２ｂおよびダミー電極指１４ｂは、ほぼ互い違いに共通のバスバー１６ｂに接続されている。バスバー１６ａは、パッド２０ａに接続されている。バスバー１６ｂは、パッド２０ｂに接続されている。電極指１２ａとダミー電極指１４ｂとはＹ方向に向かい合って配置されている。電極指１２ｂとダミー電極指１４ａとはＹ方向に向かい合って配置されている。金属膜３４を覆うように、圧電基板１０上に保護膜２８が形成されている。 First, a comparative example will be described. 1A is a plan view of an acoustic wave device according to Comparative Example 1, FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 1C is FIG. It is BB sectional drawing of. In FIG. 1A, the comb electrode is shown through the protective film. Further, the additional film is seen through, and the comb-shaped electrode is indicated by a broken line. The following plan views are the same. As shown in FIGS. 1A to 1C, comb electrodes 18 a and 18 b made of a metal film 34, pads 20 a and 20 b, and a reflector 26 are formed on the piezoelectric substrate 10. The comb electrode 18a includes a plurality of electrode fingers 12a, a plurality of dummy electrode fingers 14a, and a bus bar 16a. The comb electrode 18b includes a plurality of electrode fingers 12b, a plurality of dummy electrode fingers 14b, and a bus bar 16b. The electrode fingers 12a and the dummy electrode fingers 14a are connected to the common bus bar 16a almost alternately. The electrode fingers 12b and the dummy electrode fingers 14b are connected to the common bus bar 16b almost alternately. The bus bar 16a is connected to the pad 20a. The bus bar 16b is connected to the pad 20b. The electrode finger 12a and the dummy electrode finger 14b are disposed facing each other in the Y direction. The electrode finger 12b and the dummy electrode finger 14a are disposed facing each other in the Y direction. A protective film 28 is formed on the piezoelectric substrate 10 so as to cover the metal film 34.

電極指１２ａおよび１２ｂの配列方向をＸ方向、電極指１２ａおよび１２ｂの延伸方向をＹ方向とする。配列方向と延伸方向とは交差していれば直交していなくともよい。 The arrangement direction of the electrode fingers 12a and 12b is the X direction, and the extending direction of the electrode fingers 12a and 12b is the Y direction. The arrangement direction and the stretching direction do not have to be orthogonal as long as they intersect.

電極指１２ａの先端とダミー電極指１４ｂの先端のＹ方向の隙間、および、電極指１２ｂの先端とダミー電極指１４ａの先端のＹ方向の隙間は、ギャップ領域１５である。ギャップ領域１５は付加膜３０で覆われている。付加膜３０は、ギャップ領域１５より広く形成されている。例えば、付加膜３０は、ギャップ領域１５ごとに設けられている。 A gap in the Y direction between the tip of the electrode finger 12a and the tip of the dummy electrode finger 14b and a gap in the Y direction between the tip of the electrode finger 12b and the tip of the dummy electrode finger 14a are the gap region 15. The gap region 15 is covered with the additional film 30. The additional film 30 is formed wider than the gap region 15. For example, the additional film 30 is provided for each gap region 15.

櫛型電極１８ａおよび１８ｂが励振した弾性波は、主にＸ方向に伝播し、電極指１２ａと１２ｂとが交差する交差領域１１内に閉じ込められる。弾性波が交差領域１１からバスバー方向に漏洩すると、損失となる。付加膜３０は、電極指１２ａおよび１２ｂの先端から弾性波が漏洩することを抑制する。付加膜３０をＸ方向に連続に一体に設けると損失の改善効果は大きくない。そこで、複数の付加膜３０をＹ方向に離して設けることにより、バスバー方向への弾性波の漏洩を抑制し、損失を改善できる。 The elastic waves excited by the comb-shaped electrodes 18a and 18b propagate mainly in the X direction and are confined in the intersecting region 11 where the electrode fingers 12a and 12b intersect. If an elastic wave leaks from the intersection region 11 in the bus bar direction, a loss occurs. The additional film 30 suppresses leakage of elastic waves from the tips of the electrode fingers 12a and 12b. If the additional film 30 is integrally provided continuously in the X direction, the effect of improving the loss is not great. Therefore, by providing a plurality of additional films 30 apart in the Y direction, leakage of elastic waves in the bus bar direction can be suppressed and loss can be improved.

比較例では、ギャップ領域１５を介し交差領域１１からバスバー方向への弾性波の漏洩を抑制できる。しかしながら、矢印７０のように付加膜３０間を介した弾性波および矢印７２のように電極指１２ａおよび１２ｂの先端で散乱した弾性波がバスバー方向に漏洩する。 In the comparative example, leakage of elastic waves from the intersecting region 11 in the bus bar direction via the gap region 15 can be suppressed. However, an elastic wave passing through the additional film 30 as indicated by an arrow 70 and an elastic wave scattered at the tips of the electrode fingers 12a and 12b as indicated by an arrow 72 leak in the bus bar direction.

図２（ａ）は、実施例１に係る弾性波デバイスの平面図、図２（ｂ）は、図２（ａ）のＡ−Ａ断面図、図２（ｃ）は、図２（ａ）のＢ−Ｂ断面図である。図２（ａ）から図２（ｃ）に示すように、付加膜３０に加えバスバー１６ａおよび１６ｂ上に複数の付加膜３２が設けられている。 2A is a plan view of the acoustic wave device according to the first embodiment, FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A, and FIG. 2C is FIG. 2A. It is BB sectional drawing of. As shown in FIGS. 2A to 2C, in addition to the additional film 30, a plurality of additional films 32 are provided on the bus bars 16a and 16b.

圧電基板１０としては、例えばタンタル酸リチウム基板またはニオブ酸リチウム基板である。圧電基板１０は、サファイア基板等の支持基板上に貼り付けられた圧電基板でもよい。金属膜３４は、例えばアルミニウム膜または銅膜である。保護膜２８は、例えば酸化シリコン膜、窒化シリコン膜または酸化アルミニウム膜等の絶縁膜である。保護膜２８は設けられていなくてもよい。付加膜３０および３２は、例えば酸化アルミニウム膜、酸化シリコン膜または窒化シリコン膜等の絶縁膜である。付加膜３０および３２は、金属膜でもよい。製造工程簡略化の観点から、付加膜３０および３２は同時に形成されることが好ましい。このため、付加膜３０および３２は、同じ材料であり、同じ膜厚である。付加膜３０および３２は、異なる材料および膜厚でもよい。付加膜３２は、Ｙ方向からみて付加膜３０の間に設けられている。その他の構成は比較例と同じであり、説明を省略する。 The piezoelectric substrate 10 is, for example, a lithium tantalate substrate or a lithium niobate substrate. The piezoelectric substrate 10 may be a piezoelectric substrate attached on a support substrate such as a sapphire substrate. The metal film 34 is, for example, an aluminum film or a copper film. The protective film 28 is an insulating film such as a silicon oxide film, a silicon nitride film, or an aluminum oxide film. The protective film 28 may not be provided. The additional films 30 and 32 are insulating films such as an aluminum oxide film, a silicon oxide film, or a silicon nitride film. The additional films 30 and 32 may be metal films. From the viewpoint of simplifying the manufacturing process, the additional films 30 and 32 are preferably formed simultaneously. For this reason, the additional films 30 and 32 are made of the same material and have the same film thickness. The additional films 30 and 32 may be made of different materials and film thicknesses. The additional film 32 is provided between the additional films 30 when viewed from the Y direction. Other configurations are the same as those of the comparative example, and a description thereof is omitted.

実施例１によれば、複数の付加膜（第１付加膜）が、それぞれ複数の電極指１２ａおよび１２ｂの先端と複数のダミー電極指１４ａおよび１４ａの先端の間との隙間を覆う。複数の付加膜３０は、Ｘ方向に互いに離れて設けられている。これにより、比較例において説明したように、弾性波の交差領域１１からの漏洩を抑制できる。 According to the first embodiment, the plurality of additional films (first additional films) cover the gaps between the tips of the plurality of electrode fingers 12a and 12b and the tips of the plurality of dummy electrode fingers 14a and 14a, respectively. The plurality of additional films 30 are provided apart from each other in the X direction. Thereby, as demonstrated in the comparative example, the leak from the cross | intersection area | region 11 of an elastic wave can be suppressed.

さらに、複数の付加膜３２（第２付加膜）は、平面視においてバスバー１６ａおよび１６ｂに重なるように設けられている。これにより、矢印７０および７２の弾性波の漏洩を抑制できる。複数の付加膜３２がＸ方向に互いに離れて設けられていると複数の付加膜３２でそれぞれ散乱した弾性波が互いにキャンセルする。よって、弾性波の漏洩をより抑制できる。一方、付加膜３２がＸ方向に連続して一体として設けられていると、上記のような散乱による弾性波の相互のキャンセルがない。さらに、バスバー１６ａおよび１６ｂの音速が変化してしまう。よって、付加膜３２がＸ方向に連続して一体として設けられていると、伝搬する弾性波の閉じ込め効果が低下する。このように、複数の付加膜３２が、Ｘ方向に互いに離れて設けられていることにより、矢印７０および７２の弾性波の漏洩をより抑制できる。 Further, the plurality of additional films 32 (second additional films) are provided so as to overlap the bus bars 16a and 16b in a plan view. Thereby, the leakage of the elastic wave of the arrows 70 and 72 can be suppressed. If the plurality of additional films 32 are provided apart from each other in the X direction, the elastic waves scattered by the plurality of additional films 32 cancel each other. Therefore, leakage of elastic waves can be further suppressed. On the other hand, when the additional film 32 is provided continuously and integrally in the X direction, there is no mutual cancellation of elastic waves due to scattering as described above. Furthermore, the sound speed of the bus bars 16a and 16b changes. Therefore, if the additional film 32 is provided continuously and integrally in the X direction, the effect of confining the propagating elastic wave is reduced. As described above, since the plurality of additional films 32 are provided apart from each other in the X direction, leakage of elastic waves of the arrows 70 and 72 can be further suppressed.

図３（ａ）は、実施例１の変形例１に係る弾性波デバイスの平面図、図３（ｂ）は、図３（ａ）のＡ−Ａ断面図、図３（ｃ）は、図３（ａ）のＢ−Ｂ断面図である。図３（ａ）から図３（ｃ）に示すように、付加膜３２がバスバー１６ａおよび１６ｂ上からバスバーの外側まで形成されている。その他の構成は、実施例１と同じであり説明を省略する。 3A is a plan view of the acoustic wave device according to the first modification of the first embodiment, FIG. 3B is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. It is BB sectional drawing of 3 (a). As shown in FIGS. 3A to 3C, the additional film 32 is formed from above the bus bars 16a and 16b to the outside of the bus bar. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

図４（ａ）は、実施例１の変形例２に係る弾性波デバイスの平面図、図４（ｂ）は、図４（ａ）のＡ−Ａ断面図、図４（ｃ）は、図４（ａ）のＢ−Ｂ断面図である。図４（ａ）から図４（ｃ）に示すように、付加膜３２がバスバー１６ａおよび１６ｂの外側に形成されている。その他の構成は、実施例１と同じであり説明を省略する。 4A is a plan view of an acoustic wave device according to a second modification of the first embodiment, FIG. 4B is a cross-sectional view taken along the line AA in FIG. 4A, and FIG. It is BB sectional drawing of 4 (a). As shown in FIGS. 4A to 4C, the additional film 32 is formed outside the bus bars 16a and 16b. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

実施例１およびその変形例１、２のように、複数の付加膜３２は、平面視においてバスバー１６ａおよび１６ｂとバスバー１６ａおよび１６ｂの外側との少なくとも一方に重なるように形成されていればよい。交差領域１１から弾性波の漏洩を抑制するためには、付加膜３２は交差領域１１の近くに形成されることが好ましい。よって、付加膜３２は、平面視において少なくともバスバー１６ａおよび１６ｂに重なるように形成されていることが好ましい。一方、バスバー１６ａおよび１６ｂに付加膜３２が重なると、バスバー１６ａおよび１６ｂにおける弾性波の速度が変化してしまう。この観点からは、付加膜３２は、バスバー１６ａおよび１６ｂの外側に重なるように形成することが好ましい。ただ、交差領域１１の近くに付加膜３２を形成する観点から、図３（ａ）における付加膜３２とバスバー１６ａとの距離Ｌ１は、１０×λ程度以下であることが好ましい。λは交差領域１１の電極指１２ａおよび１２ｂのピッチである。 As in the first embodiment and the first and second modifications, the plurality of additional films 32 may be formed so as to overlap at least one of the bus bars 16a and 16b and the outside of the bus bars 16a and 16b in a plan view. In order to suppress leakage of elastic waves from the intersection region 11, the additional film 32 is preferably formed near the intersection region 11. Therefore, the additional film 32 is preferably formed so as to overlap at least the bus bars 16a and 16b in a plan view. On the other hand, when the additional film 32 overlaps the bus bars 16a and 16b, the velocity of the elastic wave in the bus bars 16a and 16b changes. From this point of view, the additional film 32 is preferably formed so as to overlap the outside of the bus bars 16a and 16b. However, from the viewpoint of forming the additional film 32 near the intersection region 11, the distance L1 between the additional film 32 and the bus bar 16a in FIG. 3A is preferably about 10 × λ or less. λ is the pitch of the electrode fingers 12 a and 12 b in the intersection region 11.

図５（ａ）から図５（ｃ）は、それぞれ実施例１、実施例１の変形例３から４に係る弾性波デバイスの一部の平面図である。図５（ａ）に示すように、実施例１では、付加膜３２は、Ｙ方向からみて付加膜３０の間に重なるように設けられている。図５（ｂ）に示すように、実施例１の変形例３では、付加膜３２はＹ方向からみて付加膜３０に重なるように設けられている。図５（ｃ）に示すように、実施例１の変形例４では、付加膜３２はＹ方向からみて付加膜３０の間の一部に重なり、かつ付加膜３０に一部重なるように設けられている。また、付加膜３２はＹ方向からみて隣接する電極指１２にまたがっている。 FIGS. 5A to 5C are plan views of a part of the acoustic wave device according to the first embodiment and the third to fourth modifications of the first embodiment, respectively. As shown in FIG. 5A, in Example 1, the additional film 32 is provided so as to overlap between the additional films 30 when viewed from the Y direction. As shown in FIG. 5B, in the third modification of the first embodiment, the additional film 32 is provided so as to overlap the additional film 30 when viewed from the Y direction. As shown in FIG. 5C, in Modification 4 of Example 1, the additional film 32 is provided so as to overlap a part between the additional films 30 and a part of the additional film 30 when viewed from the Y direction. ing. Further, the additional film 32 straddles the adjacent electrode fingers 12 as viewed from the Y direction.

交差領域１１からバスバー方向の弾性波の漏洩の抑制のため、実施例１および変形例３のように、付加膜３２は、Ｙ方向からみて付加膜３０の間に少なくとも一部が重なることが好ましい。Ｙ方向に対して斜め方向にも弾性波は漏洩するため、実施例１の変形例４のように、付加膜３２は、Ｙ方向からみて付加膜３０に重なっていてもよい。実施例１の変形例１および２においても実施例１の変形例３および４のいずれかの付加膜３２を用いることができる。 In order to suppress leakage of elastic waves from the intersecting region 11 in the bus bar direction, it is preferable that at least a part of the additional film 32 overlaps between the additional films 30 when viewed from the Y direction, as in the first embodiment and the third modification. . Since the elastic wave leaks also in the oblique direction with respect to the Y direction, the additional film 32 may overlap the additional film 30 as viewed from the Y direction as in the fourth modification of the first embodiment. In the first and second modifications of the first embodiment, any one of the additional films 32 of the third and fourth modifications of the first embodiment can be used.

図６（ａ）および図６（ｂ）は、実施例１に係る弾性波デバイスの一部の平面図である。図６（ａ）および図６（ｂ）に示すように、電極指１６のピッチをλとする。ギャップ領域１５のピッチは電極指１６のピッチと同じであるため、付加膜３０のＸ方向のピッチはλとなる。漏洩する弾性波を効率的に散乱させるため付加膜３２のピッチはλであることが好ましい。このように、複数の付加膜３２のＸ方向のピッチは、付加膜３０のＸ方向のピッチと同じであることが好ましい。 FIG. 6A and FIG. 6B are plan views of a part of the acoustic wave device according to the first embodiment. As shown in FIGS. 6A and 6B, the pitch of the electrode fingers 16 is λ. Since the pitch of the gap region 15 is the same as the pitch of the electrode fingers 16, the pitch of the additional film 30 in the X direction is λ. The pitch of the additional film 32 is preferably λ in order to efficiently scatter leaking elastic waves. Thus, the pitch in the X direction of the plurality of additional films 32 is preferably the same as the pitch in the X direction of the additional film 30.

付加膜３２のＸ方向の幅Ｗは任意である。しかしながら、電極指１６の幅より狭いと弾性波を散乱させにくくなる。また、微細パターンの形成は製造上難しくなる。例えば電極指１２の幅はほぼ１／４λである。よって、幅Ｗは１／５λ以上であることが好ましく、１／４λ以上がより好ましい。一方、電極指１６の幅が広いと弾性波を散乱させにくくなる。また、間隔の狭い付加膜３２の製造は難しい。よって、幅Ｗは４／５λ以上であることが好ましく、３／４λ以上がより好ましい。付加膜３２のＹ方向の幅は、例えばλから５λ程度である。 The width W in the X direction of the additional film 32 is arbitrary. However, if it is narrower than the width of the electrode finger 16, it is difficult to scatter the elastic wave. In addition, formation of a fine pattern becomes difficult in manufacturing. For example, the width of the electrode finger 12 is approximately 1 / 4λ. Therefore, the width W is preferably 1 / 5λ or more, and more preferably 1 / 4λ or more. On the other hand, when the width of the electrode finger 16 is wide, it is difficult to scatter the elastic wave. Further, it is difficult to manufacture the additional film 32 having a narrow interval. Therefore, the width W is preferably 4 / 5λ or more, and more preferably 3 / 4λ or more. The width of the additional film 32 in the Y direction is, for example, about λ to 5λ.

図７（ａ）および図７（ｂ）は、それぞれ実施例１の変形例５および６に係る弾性波デバイスの一部の平面図である。図７（ａ）に示すように、実施例１の変形例５では、付加膜３２ａから３２ｃがＹ方向に複数配列されている。付加膜３２ａから３２ｃはそれぞれ距離Ｌ２シフトして設けられている。 FIG. 7A and FIG. 7B are plan views of part of the acoustic wave device according to the fifth and sixth modifications of the first embodiment, respectively. As shown in FIG. 7A, in Modification 5 of Example 1, a plurality of additional films 32a to 32c are arranged in the Y direction. The additional films 32a to 32c are provided with a distance L2 shift.

実施例１の変形例５のように、複数の付加膜３２は、Ｙ方向に複数設けられていてもよい。さらに、Ｙ方向に設けられた複数の付加膜３２は、Ｘ方向に互いにずれて設けられている。これにより、付加膜３２ａの配列、付加膜３２ｂの配列および付加膜３２ｃの配列でそれぞれ弾性波を散乱させる。このため、弾性波の漏洩をより抑制できる。実施例１の変形例１から４においても、付加膜３２をＹ方向に複数設け、Ｘ方向に互いにずれて設けることもできる。 As in Modification 5 of Embodiment 1, a plurality of additional films 32 may be provided in the Y direction. Further, the plurality of additional films 32 provided in the Y direction are provided so as to be shifted from each other in the X direction. Thereby, elastic waves are scattered by the arrangement of the additional film 32a, the arrangement of the additional film 32b, and the arrangement of the additional film 32c. For this reason, leakage of elastic waves can be further suppressed. Also in the first to fourth modifications of the first embodiment, it is possible to provide a plurality of additional films 32 in the Y direction and to be shifted from each other in the X direction.

図７（ｂ）に示すように、実施例１の変形例６では、付加膜３０および３２が円形状または楕円形状である。その他の構成は実施例１と同じであり説明を省略する。このように、付加膜３０および３２の形状は矩形には限定されず、任意である。弾性波の散乱の観点からは、付加膜３０および３２は円形状または楕円形状が好ましい。このように、付加膜３０および／または３２の外周は曲線であることが好ましい。また、付加膜３０および３２の一方の形状が矩形で他方の形状が円形状または楕円形状でもよい。このように、付加膜３０と３２とで形状が異なっていてもよい。また、複数の付加膜３０内で形状が異なっていてもよいし、複数の付加膜３２内で形状が異なっていてもよい。実施例１の他の変形例においても、付加膜３０および３２の形状は変形例６と同様でもよい。 As shown in FIG. 7B, in the sixth modification of the first embodiment, the additional films 30 and 32 are circular or elliptical. Other configurations are the same as those of the first embodiment, and the description thereof is omitted. Thus, the shape of the additional films 30 and 32 is not limited to a rectangle, but is arbitrary. From the viewpoint of elastic wave scattering, the additional films 30 and 32 are preferably circular or elliptical. Thus, the outer periphery of the additional film 30 and / or 32 is preferably a curve. Further, one of the additional films 30 and 32 may be rectangular and the other may be circular or elliptical. As described above, the shapes of the additional films 30 and 32 may be different. Further, the shapes may be different in the plurality of additional films 30, and the shapes may be different in the plurality of additional films 32. Also in other modifications of the first embodiment, the shapes of the additional films 30 and 32 may be the same as those of the sixth modification.

実施例２は、反射器２６に付加膜３２を設けた例である。図８は、実施例２に係る弾性波デバイスの平面図である。図８に示すように、実施例２では、反射器２６のバスバー２４に重なるように複数の付加膜３２が形成されている。反射器２６の最も外側の電極指２２に重なるように複数の付加膜３２が形成されている。その他の構成は実施例１と同じであり説明を省略する。 The second embodiment is an example in which the additional film 32 is provided on the reflector 26. FIG. 8 is a plan view of the acoustic wave device according to the second embodiment. As shown in FIG. 8, in Example 2, a plurality of additional films 32 are formed so as to overlap the bus bar 24 of the reflector 26. A plurality of additional films 32 are formed so as to overlap the outermost electrode fingers 22 of the reflector 26. Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

図９は、実施例２の変形例１に係る弾性波デバイスの平面図である。図９に示すように、実施例２の変形例１では、反射器２６のバスバー２４からバスバーの外側に重なるように複数の付加膜３２が形成されている。反射器２６の最も外側の電極指２２から外側に重なるように複数の付加膜３２が形成されている。その他の構成は実施例１の変形例１と同じであり説明を省略する。 FIG. 9 is a plan view of the acoustic wave device according to the first modification of the second embodiment. As shown in FIG. 9, in the first modification of the second embodiment, a plurality of additional films 32 are formed so as to overlap from the bus bar 24 of the reflector 26 to the outside of the bus bar. A plurality of additional films 32 are formed so as to overlap the outermost electrode fingers 22 of the reflector 26. Other configurations are the same as those of the first modification of the first embodiment, and a description thereof will be omitted.

図１０は、実施例２の変形例２に係る弾性波デバイスの平面図である。図１０に示すように、実施例２の変形例２では、反射器２６のバスバーの外側に重なるように複数の付加膜３２が形成されている。反射器２６の最も外側の電極指２２の外側に重なるように複数の付加膜３２が形成されている。その他の構成は実施例１の変形例２と同じであり説明を省略する。 FIG. 10 is a plan view of an acoustic wave device according to a second modification of the second embodiment. As shown in FIG. 10, in the second modification of the second embodiment, a plurality of additional films 32 are formed so as to overlap the outside of the bus bar of the reflector 26. A plurality of additional films 32 are formed so as to overlap the outermost electrode finger 22 of the reflector 26. Other configurations are the same as those of the second modification of the first embodiment, and a description thereof will be omitted.

実施例２およびその変形例によれば、付加膜３２は、平面視において反射器２６のバスバー２４および反射器２６のバスバー２４の外側の少なくとも一方に重なるように設けられている。これにより、反射器２６からの弾性波の漏洩を抑制できる。弾性波の漏洩を抑制するためには、付加膜３２はＹ方向にみて電極指２２に重なるように設けられていることが好ましい。 According to the second embodiment and the modification thereof, the additional film 32 is provided so as to overlap at least one of the bus bar 24 of the reflector 26 and the outside of the bus bar 24 of the reflector 26 in a plan view. Thereby, the leakage of the elastic wave from the reflector 26 can be suppressed. In order to suppress leakage of elastic waves, the additional film 32 is preferably provided so as to overlap the electrode finger 22 as viewed in the Y direction.

また、付加膜３２は、平面視において、反射器２６のＸ方向の最も外側の電極指２２および最も外側の電極指２２の外側の少なくとも一方に重なるように設けられている。これにより、反射器２６からの弾性波の漏洩を抑制できる。実施例１の変形例３から６においても、反射器２６に付加膜３２を設けてもよい。 Further, the additional film 32 is provided so as to overlap with at least one of the outermost electrode finger 22 and the outermost electrode finger 22 in the X direction of the reflector 26 in plan view. Thereby, the leakage of the elastic wave from the reflector 26 can be suppressed. In the third to sixth modifications of the first embodiment, the reflector 26 may be provided with the additional film 32.

図１１（ａ）から図１２（ｄ）は、実施例１、２およびその変形例における弾性波デバイスの製造方法を示す断面図である。図１１（ａ）から図１１（ｄ）は、図２（ａ）のＡ−Ａ断面図に相当し、図１２（ａ）から図１２（ｄ）は、図２（ａ）のＢ−Ｂ断面図に相当する。 FIG. 11A to FIG. 12D are cross-sectional views showing a method for manufacturing an acoustic wave device in Examples 1 and 2 and its modifications. 11A to 11D correspond to the AA cross-sectional view of FIG. 2A, and FIGS. 12A to 12D are BB of FIG. 2A. It corresponds to a sectional view.

図１１（ａ）および図１２（ａ）に示すように、圧電基板１０上に、金属膜３４を形成する。金属膜３４から櫛型電極１８ａ、１８ｂおよび反射器２６を形成する。金属膜３４の形成は、スパッタリング法およびエッチング法、または真空蒸着法およびリフトオフ法を用いる。櫛型電極１８ａ、１８ｂおよび反射器２６を覆うように、圧電基板１０上に保護膜２８を形成する。保護膜２８の形成は、スパッタリング法またはＣＶＤ（Chemical Vapor Deposition）法を用いる。 As shown in FIGS. 11A and 12A, a metal film 34 is formed on the piezoelectric substrate 10. Comb electrodes 18 a and 18 b and reflector 26 are formed from metal film 34. The metal film 34 is formed by sputtering and etching, or vacuum deposition and lift-off. A protective film 28 is formed on the piezoelectric substrate 10 so as to cover the comb electrodes 18 a and 18 b and the reflector 26. The protective film 28 is formed by sputtering or CVD (Chemical Vapor Deposition).

図１１（ｂ）および図１２（ｂ）に示すように、保護膜２８上に開口５２を有するマスク層５０を形成する。マスク層５０は例えばフォトレジストである。図１１（ｃ）および図１２（ｃ）に示すように、付加膜３６を形成する。付加膜３６の形成は、真空中蒸着法またはスパッタリング法を用いる。 As shown in FIGS. 11B and 12B, a mask layer 50 having an opening 52 is formed on the protective film 28. The mask layer 50 is, for example, a photoresist. As shown in FIGS. 11C and 12C, the additional film 36 is formed. The additional film 36 is formed using a vacuum deposition method or a sputtering method.

図１１（ｄ）および図１２（ｄ）に示すように、マスク層５０を除去する。これにより、マスク層５０上の付加膜３６がリフトオフされる。これにより、図１１（ｄ）のように、電極指１２ｂの先端とダミー電極指１４ａの先端との隙間（ギャップ領域１５）に付加膜３０が埋め込まれる。図１２（ｄ）のように、バスバー１６ａ上に付加膜３２が形成される。 As shown in FIGS. 11D and 12D, the mask layer 50 is removed. As a result, the additional film 36 on the mask layer 50 is lifted off. Thereby, as shown in FIG. 11D, the additional film 30 is embedded in the gap (gap region 15) between the tip of the electrode finger 12b and the tip of the dummy electrode finger 14a. As shown in FIG. 12D, the additional film 32 is formed on the bus bar 16a.

図１１（ｃ）および図１２（ｃ）において、マスク層５０を除去するために、ＮＭＰ（Ｎメチルピロリドン）等の溶剤を用いる。溶剤は、マスク層５０の側面からマスク層５０に浸透する。付加膜３０および３２の面積は、例えば０．５μｍ×０．７５μｍ程度と小さい。このため、溶剤のマスク層５０への浸透しにくくなる。これにより、マスク層５０上の付加膜３６の剥離が難しい。特に、付加膜３６としてスパッタリング法を用い形成すると、マスク層５０の側面に付加膜３６が厚く形成されるため、付加膜３６の剥離が難しくなる。このため、マスク層５０の開口５２は多いほうが好ましい。 In FIG. 11C and FIG. 12C, a solvent such as NMP (N methylpyrrolidone) is used to remove the mask layer 50. The solvent penetrates into the mask layer 50 from the side surface of the mask layer 50. The areas of the additional films 30 and 32 are as small as, for example, about 0.5 μm × 0.75 μm. For this reason, it becomes difficult for the solvent to penetrate into the mask layer 50. This makes it difficult to peel off the additional film 36 on the mask layer 50. In particular, when the additional film 36 is formed using a sputtering method, the additional film 36 is formed thick on the side surface of the mask layer 50, so that it is difficult to peel off the additional film 36. For this reason, it is preferable that the mask layer 50 has a large number of openings 52.

図１３は、実施例３に係る弾性波デバイスの平面図である。図１３に示すように、圧電基板１０上の全体にわたり付加膜３２が形成されている。その他の構成は実施例１と同じであり説明を省略する。これにより、マスク層５０への溶剤の浸透が容易となり、リフトオフがより容易となる。付加膜３２は、パッド２０ａおよび２０ｂ上に形成されていてもよい。しかし、付加膜３２が絶縁体の場合、パッド２０ａおよび２０ｂ上に形成しないことが好ましい。実施例３のように、圧電基板１０上の全体にわたり付加膜３２を形成しても弾性波の漏洩を抑制できる。実施例１の変形例、実施例２およびその変形例において、付加膜３２を圧電基板１０上の全体に形成することもできる。 FIG. 13 is a plan view of the acoustic wave device according to the third embodiment. As shown in FIG. 13, the additional film 32 is formed over the entire piezoelectric substrate 10. Other configurations are the same as those of the first embodiment, and the description thereof is omitted. Thereby, the penetration of the solvent into the mask layer 50 becomes easy, and the lift-off becomes easier. The additional film 32 may be formed on the pads 20a and 20b. However, when the additional film 32 is an insulator, it is preferably not formed on the pads 20a and 20b. Even if the additional film 32 is formed over the entire piezoelectric substrate 10 as in the third embodiment, leakage of elastic waves can be suppressed. In the modification of the first embodiment, the second embodiment, and the modification thereof, the additional film 32 can be formed on the entire piezoelectric substrate 10.

図１４は、実施例４に係る弾性波デバイスの平面図である。図１３に示すように、櫛型電極１８ａおよび１８ｂはダミー電極指１４ａおよび１４ｂを備えていない。その他の構成は実施例１と同じであり説明を省略する。実施例４のように、櫛型電極１８ａおよび１８ｂはダミー電極指１４ａおよび１４ｂを備えなくてもよい。この場合、複数の付加膜３０は、複数の電極指１２ａおよび１２ｂの先端とバスバー１６ｂおよび１６ａとの複数の隙間の少なくとも一部を覆えばよい。実施例１の変形例、実施例２およびその変形例、実施例３において、櫛型電極１８ａおよび１８ｂはダミー電極指１４ａおよび１４ｂを備えなくてもよい。 FIG. 14 is a plan view of the acoustic wave device according to the fourth embodiment. As shown in FIG. 13, the comb-shaped electrodes 18a and 18b do not include the dummy electrode fingers 14a and 14b. Other configurations are the same as those of the first embodiment, and the description thereof is omitted. As in the fourth embodiment, the comb electrodes 18a and 18b may not include the dummy electrode fingers 14a and 14b. In this case, the plurality of additional films 30 may cover at least a part of the plurality of gaps between the tips of the plurality of electrode fingers 12a and 12b and the bus bars 16b and 16a. In the modified example of the first example, the second example and the modified example, and the third example, the comb-shaped electrodes 18a and 18b may not include the dummy electrode fingers 14a and 14b.

実施例１から４およびその変形例において、付加膜３０がギャップ領域１５である隙間の全てを覆う例を説明した。付加膜３０は、隙間の少なくとも一部を覆えばよい。また、複数の隙間のうち一部の隙間に付加膜３０が設けられていてもよい。 In Examples 1 to 4 and the modifications thereof, the example in which the additional film 30 covers the entire gap that is the gap region 15 has been described. The additional film 30 may cover at least a part of the gap. Further, the additional film 30 may be provided in some of the plurality of gaps.

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 embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

１０基板
１１交差領域
１２、１２ａ、１２ｂ、２２電極指
１４、１４ａ、１４ｂダミー電極指
１５ギャップ領域
１６、１６ａ、１６ｂ、２４バスバー
１８、１８ａ、１８ｂ櫛型電極
２０ａ、２０ｂバッド
２６反射器
２８保護膜
３０、３２付加膜
３４金属膜 10 Substrate 11 Crossing region 12, 12a, 12b, 22 Electrode finger 14, 14a, 14b Dummy electrode finger 15 Gap region 16, 16a, 16b, 24 Bus bar 18, 18a, 18b Comb electrode 20a, 20b Bad 26 Reflector 28 Protection 28 Film 30, 32 Additional film 34 Metal film

Claims

A plurality of electrode fingers provided on the piezoelectric substrate, each of which includes a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are commonly connected, and each of the plurality of electrode fingers and the bus bar or a plurality of bus bars commonly connected to the bus bar. A pair of comb-shaped electrodes arranged so that the dummy electrode fingers face each other;
Each covers at least a part of a plurality of gaps located between the tips of the plurality of electrode fingers and the tips of the bus bars or the plurality of dummy electrode fingers, and is separated from each other in the arrangement direction of the plurality of electrode fingers. A plurality of first additional films provided;
A plurality of second additional films provided apart from each other in the arrangement direction so as to overlap at least one of the bus bar and the outside of the bus bar in a plan view;
Equipped with,
The pitch in the arrangement direction of the plurality of second additional films is the same as the pitch in the arrangement direction of the plurality of electrode fingers of one comb electrode of the pair of comb electrodes. Wave device.

The set of the plurality of second additional film provided on the busbar side of one comb electrode of the comb electrode, when viewed from the extending direction of the plurality of electrode fingers provided on the bus bar side of the one comb electrode 2. The acoustic wave device according to claim 1, wherein at least a part of the plurality of first addition films is provided so as to overlap.

3. The acoustic wave device according to claim 1, wherein the plurality of second additional films are provided so as to overlap at least the bus bar in a plan view.

The set of the plurality of second additional film provided on the busbar side of one comb electrode of the comb electrode, when viewed from the extending direction of the plurality of electrode fingers provided on the bus bar side of the one comb electrode at least partially overlap between the plurality of first additional layer which is, acoustic wave device according to claim 1, characterized in that is provided so as to overlap the bus bar of at least the one comb electrode in a plan view .

It said plurality of second additional layer is an elastic wave device according to any one of claims 1 to 4, characterized in that is provided with a plurality in the extending direction of the plurality of electrode fingers.

6. The acoustic wave device according to claim 5 , wherein the plurality of second additional films provided in the extending direction are provided so as to be shifted from each other in the arrangement direction.

A reflector provided in the arrangement direction of the pair of comb-shaped electrodes, including a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are connected;
It said plurality of second additional layer is any one of claims 1, characterized in that are provided so as to overlap at least one of the outer bus bar of the bus bar and the reflector of the reflector in plan view 6 The acoustic wave device according to item.

The plurality of second additional films are provided so as to overlap at least one of the outermost electrode finger in the arrangement direction of the reflector and the outer side of the outermost electrode finger in plan view. The acoustic wave device according to claim 7.