JP5402841B2 - Surface acoustic wave device - Google Patents

Surface acoustic wave device Download PDF

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JP5402841B2
JP5402841B2 JP2010134733A JP2010134733A JP5402841B2 JP 5402841 B2 JP5402841 B2 JP 5402841B2 JP 2010134733 A JP2010134733 A JP 2010134733A JP 2010134733 A JP2010134733 A JP 2010134733A JP 5402841 B2 JP5402841 B2 JP 5402841B2
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film
conductive film
insulating film
acoustic wave
surface acoustic
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JP2012004613A (en
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亮 大坪
正宏 福島
努 高井
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Murata Manufacturing Co Ltd
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Description

本発明は弾性表面波デバイスに関し、詳しくは、弾性表面波を励振する櫛形電極（ＩＤＴ；Interdigital Transducer）の周囲が絶縁膜で覆われた弾性表面波デバイスに関する。   The present invention relates to a surface acoustic wave device, and more particularly, to a surface acoustic wave device in which the periphery of an interdigital transducer (IDT) that excites a surface acoustic wave is covered with an insulating film.

圧電性を有する圧電基板の表面にＩＤＴが形成され、ＩＤＴによって励振された弾性表面波を利用する弾性表面波デバイスにおいて、温度特性の補償などために、ＩＤＴを絶縁膜で被覆する構成が知られている。   In a surface acoustic wave device using a surface acoustic wave excited by IDT and having an IDT formed on the surface of a piezoelectric substrate having piezoelectricity, a configuration in which IDT is covered with an insulating film is known to compensate for temperature characteristics. ing.

例えば図７の断面図に示すように、圧電基板２上に、複数層１０２ａ〜１０２ｄからなる第１の導電膜１０２によりＩＤＴ１２３を形成し、ＩＤＴ１２３を絶縁膜１２４で被覆するとともに、第１の導電膜１０２により形成された第１の配線パターン１０３に、導電性を有する層間接続膜１０６を介して、複数層１０４ａ〜１０４ｃからなる第２の導電膜１０４を接続する。第２の導電膜１０４により、電極パッド１０９等を含む第２の配線パターン１０５を形成し、バンプ１３２を介して実装する。（例えば、特許文献１参照）   For example, as shown in the cross-sectional view of FIG. 7, the IDT 123 is formed on the piezoelectric substrate 2 by the first conductive film 102 including a plurality of layers 102 a to 102 d, the IDT 123 is covered with the insulating film 124, and the first conductive A second conductive film 104 composed of a plurality of layers 104 a to 104 c is connected to the first wiring pattern 103 formed of the film 102 through an interlayer connection film 106 having conductivity. A second wiring pattern 105 including the electrode pads 109 and the like is formed by the second conductive film 104 and mounted via the bumps 132. (For example, see Patent Document 1)

国際公開第２００９／０１６９０６号International Publication No. 2009/016906

樹脂パッケージ品など、弾性表面波デバイスが気密封止されない場合、第１の導電膜により形成されたＩＤＴと絶縁膜との間の隙間に湿気が浸入し、浸入した湿気が結露したり、結露によりＩＤＴが腐食したりすると、弾性表面波の音速が変化する。そのため、耐湿試験での電気特性が変化し、不良と判定されることがある。   When a surface acoustic wave device such as a resin package product is not hermetically sealed, moisture enters the gap between the IDT formed by the first conductive film and the insulating film. When the IDT corrodes, the sound velocity of the surface acoustic wave changes. For this reason, the electrical characteristics in the moisture resistance test may change and may be determined as defective.

絶縁膜による被覆を広げ、第１の導電膜のみならず第２の導電膜も絶縁膜によってできるだけ被覆するようにしても、層間の隙間からの湿気の浸入を遮断できない場合がある。   Even if the insulating film is widened so that not only the first conductive film but also the second conductive film is covered with the insulating film as much as possible, intrusion of moisture from the gaps between the layers may not be blocked.

本発明は、かかる実情に鑑み、耐湿性が向上し、耐湿試験での電気特性の変化を防止することができる弾性表面波デバイスを提供しようとするものである。   In view of such circumstances, the present invention is intended to provide a surface acoustic wave device that has improved moisture resistance and can prevent changes in electrical characteristics in a moisture resistance test.

本発明は、上記課題を解決するために、以下のように構成した弾性表面波デバイスを提供する。   In order to solve the above-described problems, the present invention provides a surface acoustic wave device configured as follows.

弾性表面波デバイスは、（ａ）圧電基板と、（ｂ）前記圧電基板の主面にＩＤＴを形成する第１の導電膜と、（ｃ）前記第１の導電膜に隣接し、かつ前記第１の導電膜の周囲を取り囲むように、前記圧電基板の前記主面に形成された第１の絶縁膜と、（ｄ）前記圧電基板の前記主面と前記第１の絶縁膜と前記第１の導電膜とに接合されるように形成された第２の導電膜と、（ｅ）前記第１の絶縁膜に接合され、前記第１の導電膜を覆うように形成された第２の絶縁膜とを備えたタイプのものである。前記第１の導電膜と前記第１の絶縁膜との境界部分と前記第２の導電膜とが交差する領域及びその近傍領域において、前記第２の導電膜と前記第１の導電膜との間及び前記第２の導電膜と前記第１の絶縁膜との間に延在するように形成された目張り膜を備える。   The surface acoustic wave device includes: (a) a piezoelectric substrate; (b) a first conductive film that forms an IDT on a main surface of the piezoelectric substrate; and (c) adjacent to the first conductive film and the first conductive film. A first insulating film formed on the main surface of the piezoelectric substrate so as to surround the periphery of the one conductive film; (d) the main surface of the piezoelectric substrate, the first insulating film, and the first A second conductive film formed to be bonded to the first conductive film; and (e) a second insulating film formed to be bonded to the first insulating film and cover the first conductive film. It is of a type provided with a membrane. In the region where the boundary portion between the first conductive film and the first insulating film intersects the second conductive film and in the vicinity thereof, the second conductive film and the first conductive film And a weathering film formed to extend between the second conductive film and the first insulating film.

上記構成において、第１の導電膜と第１の絶縁膜との境界部分と、第２の導電膜と第１の絶縁膜との界面は、目張り膜によって離され、直接は接続されない。目張り膜を設けると、外部からの湿気が、圧電基板の主面と第２の導電膜との界面の隙間から、第２の導電膜と第１の絶縁膜との界面の隙間に浸入しても目張り膜で遮断し、外部からの湿気が、第１の導電膜と第１の絶縁膜との境界部分には達しないようにすることができる。これにより、耐湿性が向上し、耐湿試験での電気特性の変化を防止することができる。   In the above configuration, the boundary portion between the first conductive film and the first insulating film and the interface between the second conductive film and the first insulating film are separated by the weathering film and are not directly connected. When the weathering film is provided, moisture from the outside enters the gap at the interface between the second conductive film and the first insulating film from the gap at the interface between the main surface of the piezoelectric substrate and the second conductive film. Further, it is possible to prevent the moisture from the outside from reaching the boundary portion between the first conductive film and the first insulating film. Thereby, moisture resistance improves and the change of the electrical property in a moisture resistance test can be prevented.

好ましくは、前記目張り膜は、層間接続膜である。前記層間接続膜は、（ｉ）前記第１の導電膜に接合された、導電性を有する本体部と、（ii）該本体部から、前記第１の導電膜と前記第１の絶縁膜との境界部分を越えて、前記第１の絶縁膜上に膨出した、導電性を有する膨出部とを有する。   Preferably, the weathering film is an interlayer connection film. The interlayer connection film includes: (i) a conductive main body joined to the first conductive film; and (ii) from the main body, the first conductive film and the first insulating film. And a bulging portion having conductivity which bulges on the first insulating film beyond the boundary portion.

この場合、層間接続膜の本体部に膨出部を追加するだけ目張り膜を形成できるため、製造コストを上げることなく、耐湿試験での電気特性の変化を防止することができる。   In this case, since the cover film can be formed by adding the bulging portion to the main body of the interlayer connection film, it is possible to prevent changes in electrical characteristics in the moisture resistance test without increasing the manufacturing cost.

本発明によれば、耐湿性が向上し、耐湿試験での電気特性の変化を防止することができる。   According to the present invention, moisture resistance is improved, and changes in electrical characteristics in a moisture resistance test can be prevented.

弾性表面波デバイスの（ａ）平面図、（ｂ）断面図である。（実施例１）It is (a) top view and (b) sectional view of a surface acoustic wave device. Example 1 弾性表面波デバイスの製造工程を示す断面図である。（実施例１）It is sectional drawing which shows the manufacturing process of a surface acoustic wave device. Example 1 弾性表面波デバイスの製造工程を示す断面図である。（実施例１）It is sectional drawing which shows the manufacturing process of a surface acoustic wave device. Example 1 弾性表面波デバイスの（ａ）平面図、（ｂ）断面図である。（実施例２）It is (a) top view and (b) sectional view of a surface acoustic wave device. (Example 2) 弾性表面波デバイスの（ａ）平面図、（ｂ）断面図である。（実施例３）It is (a) top view and (b) sectional view of a surface acoustic wave device. (Example 3) 弾性表面波デバイスの（ａ）平面図、（ｂ）断面図である。（比較例）It is (a) top view and (b) sectional view of a surface acoustic wave device. (Comparative example) 弾性表面波デバイスの断面図である。（従来例）It is sectional drawing of a surface acoustic wave device. (Conventional example)

以下、本発明の実施の形態について、図１〜図６を参照しながら説明する。   Embodiments of the present invention will be described below with reference to FIGS.

＜実施例１＞ 実施例１の弾性表面波デバイス１０について、図１〜図３を参照しながら説明する。   Example 1 A surface acoustic wave device 10 of Example 1 will be described with reference to FIGS.

図１（ａ）は、実施例１の弾性表面波デバイス１０の平面図である。図１（ｂ）は、図１（ａ）の線Ａ−Ａに沿って切断した断面図である。図１（ａ）において右側の部分は、絶縁膜１６，１８を取り除いた状態を示している。   FIG. 1A is a plan view of the surface acoustic wave device 10 according to the first embodiment. FIG.1 (b) is sectional drawing cut | disconnected along line AA of Fig.1 (a). The right part in FIG. 1A shows a state where the insulating films 16 and 18 are removed.

図１に示すように、実施例１の弾性表面波デバイス１０は、圧電基板１２の主面１２ａに、１層又は２層以上の金属膜からなる第１の導電膜によりＩＤＴ２０が形成されている。ＩＤＴ２０は、バスバー２２と、バスバー２２に接続された複数本の電極指２４とからなる。図１（ａ）では一方のＩＤＴ２０のみを図示しているが、一方のＩＤＴ２０のそれぞれの電極指２４と、不図示の他方のＩＤＴの電極指とが、それぞれ互いに間挿し合うように構成されている。   As shown in FIG. 1, in the surface acoustic wave device 10 according to the first embodiment, an IDT 20 is formed on a main surface 12a of a piezoelectric substrate 12 by a first conductive film made of one or more metal films. . The IDT 20 includes a bus bar 22 and a plurality of electrode fingers 24 connected to the bus bar 22. Although only one IDT 20 is illustrated in FIG. 1A, each electrode finger 24 of one IDT 20 and another electrode finger of the other IDT (not shown) are configured to be inserted into each other. Yes.

圧電基板１２の主面１２ａには、ＩＤＴ２０に隣接し、かつＩＤＴ２０の周囲を取り囲むように、第１の絶縁膜１４が形成されている。ＩＤＴ２０と第１の絶縁膜１４との間の境界部分には、隙間２１が形成されている。なお、隙間２１は誇張して図示している。   A first insulating film 14 is formed on the main surface 12 a of the piezoelectric substrate 12 so as to be adjacent to the IDT 20 and surround the IDT 20. A gap 21 is formed at a boundary portion between the IDT 20 and the first insulating film 14. Note that the gap 21 is exaggerated.

ＩＤＴ２０のバスバー２２と第１の絶縁膜１４の上には、ＩＤＴ２０と第１の絶縁膜１４との間の境界部分の隙間２１を跨ぐように、層間接続膜２６が形成されている。   An interlayer connection film 26 is formed on the bus bar 22 of the IDT 20 and the first insulating film 14 so as to straddle the gap 21 at the boundary between the IDT 20 and the first insulating film 14.

さらに、１層又は２層以上の金属膜からなる第２の導電膜２８が、圧電基板１２の主面１２ａと、第１の絶縁膜１４と、層間接続膜２６の上に形成され、圧電基板１２の主面１２ａと、第１の絶縁膜１４と、層間接続膜２６とに接合されている。   Further, a second conductive film 28 made of one or more metal films is formed on the main surface 12 a of the piezoelectric substrate 12, the first insulating film 14, and the interlayer connection film 26. 12 main surfaces 12 a, the first insulating film 14, and the interlayer connection film 26.

また、第１の絶縁膜１４と、ＩＤＴ２０と、第２の導電膜２８の上に、ＩＤＴ２０を覆うように、第２の絶縁膜１６が形成されている。第２の絶縁膜１６は、第１の絶縁膜１４と、ＩＤＴ２０と、第２の導電膜２８とに接合されている。第２の絶縁膜１６の上には、第３の絶縁膜１８が形成されている。第３の絶縁膜１８は、第１の絶縁膜１４及び第２の絶縁膜１６が圧電基板１２の主面１２ａ上に露出しないように、第１の絶縁膜１４と第２の絶縁膜１６とを完全に覆うように形成され、第３の絶縁膜１８の外周縁近傍部分は、圧電基板１２の主面１２ａに接合されている。   Further, the second insulating film 16 is formed on the first insulating film 14, the IDT 20, and the second conductive film 28 so as to cover the IDT 20. The second insulating film 16 is bonded to the first insulating film 14, the IDT 20, and the second conductive film 28. A third insulating film 18 is formed on the second insulating film 16. The third insulating film 18 includes the first insulating film 14 and the second insulating film 16 so that the first insulating film 14 and the second insulating film 16 are not exposed on the main surface 12 a of the piezoelectric substrate 12. The third insulating film 18 is joined to the main surface 12a of the piezoelectric substrate 12 at a portion near the outer peripheral edge thereof.

層間接続膜２６は、ＩＤＴ２０のバスバー２２上に形成された本体部２６ｐと、本体部２６ｐから、ＩＤＴ２０と第１の絶縁膜１４との境界部分を越えて、第１の絶縁膜１４上に膨出した膨出部２６ｑとを有する。第２の導電膜２８は、層間接続膜２６の本体部２６ｐ及び膨出部２６ｑに接合されており、ＩＤＴ２０のバスバー２２と第２の導電膜２８とは層間接続膜２６を介して接続されている。   The interlayer connection film 26 swells on the first insulating film 14 from the main body portion 26p formed on the bus bar 22 of the IDT 20 and beyond the boundary portion between the IDT 20 and the first insulating film 14 from the main body portion 26p. And a protruding bulge portion 26q. The second conductive film 28 is joined to the main body portion 26p and the bulging portion 26q of the interlayer connection film 26, and the bus bar 22 of the IDT 20 and the second conductive film 28 are connected via the interlayer connection film 26. Yes.

層間接続膜２６は、ＩＤＴ２０と第１の絶縁膜１４との境界部分と第２の導電膜２８とが交差する領域及びその近傍領域に延在している部分を含み、目張り膜として機能する。   The interlayer connection film 26 includes a portion where the boundary portion between the IDT 20 and the first insulating film 14 and the second conductive film 28 intersect and a portion extending in the vicinity thereof, and functions as a weathering film.

すなわち、層間接続膜２６が介在するため、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１と、第２の導電膜２８と第１の絶縁膜１４との界面とは、直接には接続されていない。そのため、矢印３０，３１で示すように、外部からの湿気が、圧電基板１２の主面１２ａと第２の導電膜２８との界面の隙間から、第２の導電膜２８と第１の絶縁膜１４との界面の隙間に浸入しても、層間接続膜２６で遮断され、外部からの湿気は、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１には達しない。その結果、耐湿性が向上し、弾性表面波デバイス１０の耐湿試験において、電気特性の変化を防止することができる。   That is, since the interlayer connection film 26 is interposed, the gap 21 at the boundary between the IDT 20 and the first insulating film 14 and the interface between the second conductive film 28 and the first insulating film 14 are directly Not connected. Therefore, as indicated by arrows 30 and 31, moisture from the outside flows from the gap at the interface between the main surface 12 a of the piezoelectric substrate 12 and the second conductive film 28 and the second conductive film 28 and the first insulating film. Even if it penetrates into the gap at the interface with 14, it is blocked by the interlayer connection film 26, and moisture from the outside does not reach the gap 21 at the boundary between the IDT 20 and the first insulating film 14. As a result, moisture resistance is improved, and changes in electrical characteristics can be prevented in the moisture resistance test of the surface acoustic wave device 10.

層間接続膜２６に、第１の絶縁膜１４とＩＤＴ２０との境界部分の隙間２１を跨ぐ部分を追加するだけでよいので、製造コストを上げることなく、耐湿試験での電気特性の変化を防止することができる。   Since it is only necessary to add to the interlayer connection film 26 a portion straddling the gap 21 at the boundary portion between the first insulating film 14 and the IDT 20, it is possible to prevent a change in electrical characteristics in the moisture resistance test without increasing the manufacturing cost. be able to.

次に、実施例１の弾性表面波デバイス１０の製造工程の一例について、図２及び図３の断面図を参照しながら説明する。   Next, an example of the manufacturing process of the surface acoustic wave device 10 of Example 1 will be described with reference to the cross-sectional views of FIGS.

まず、図２（１）に示すように、ニオブ酸リチウム（ＬｉＮｂＯ３）の圧電基板１２の主面１２ａに、スパッタリングによりＳｉＯ２膜１４ｓを成膜する。 First, as shown in FIG. 2A, a SiO 2 film 14s is formed on the main surface 12a of the lithium niobate (LiNbO 3 ) piezoelectric substrate 12 by sputtering.

次いで、図２（２）に示すように、ＳｉＯ２膜１４ｓ上にレジストを塗布し、露光することにより、所定パターンのマスク５０を形成する。 Next, as shown in FIG. 2B, a resist 50 is applied onto the SiO 2 film 14s and exposed to form a mask 50 having a predetermined pattern.

次いで、図２（３）に示すように、マスク５０を介して、ＳｉＯ２膜１４ｔをドライエッチングする。 Next, as shown in FIG. 2 (3), the SiO 2 film 14 t is dry-etched through the mask 50.

次いで、Ｔｉ、Ａｌ、合金などの１層又は２層以上の金属膜をスパッタリングにより成膜した後、マスク５０とマスク５０の上に形成された金属膜を除去して、図２（４）に示すように、ＳｉＯ２膜１４ｔに埋め込まれたＩＤＴ２０を形成する。このとき、ＳｉＯ２膜１４ｔのエッチング面に金属膜を完全に密着させることは困難であり、ＳｉＯ２膜１４ｔとＩＤＴ２０との境界部分に、隙間が形成される。 Next, after one or more metal films such as Ti, Al, and alloy are formed by sputtering, the mask 50 and the metal film formed on the mask 50 are removed, and FIG. As shown, the IDT 20 embedded in the SiO 2 film 14t is formed. In this case, it is difficult to completely close contact with the metal film on the etched surface of the SiO 2 film 14t, at the boundary between SiO 2 film 14t and IDT 20, a gap is formed.

次いで、ＳｉＯ２膜１４ｔを所定形状にエッチングし、図２（５）に示すように、第１の絶縁膜１４を形成する。 Next, the SiO 2 film 14t is etched into a predetermined shape to form the first insulating film 14 as shown in FIG.

次いで、所定の形状の１層又は２層以上の金属膜を形成することにより、図２（６）に示すように、ＩＤＴ２０のバスバー２２上に、層間接続膜２６を形成する。例えば、層間接続膜２６として、密着性の優れたＴｉ膜、又はＴｉ／Ａｌ／Ｔｉ膜を形成する。   Next, an interlayer connection film 26 is formed on the bus bar 22 of the IDT 20, as shown in FIG. For example, a Ti film having excellent adhesion or a Ti / Al / Ti film is formed as the interlayer connection film 26.

なお、図２及び図３では図示していないが、層間接続膜２６は、第１の絶縁膜１４の上にも形成し、層間接続膜２６が、ＩＤＴ２０と第１の絶縁膜１４との境界部分と第２の導電膜２８とが交差する領域及びその近傍領域に延在するように形成する。   Although not shown in FIGS. 2 and 3, the interlayer connection film 26 is also formed on the first insulating film 14, and the interlayer connection film 26 is a boundary between the IDT 20 and the first insulating film 14. The portion and the second conductive film 28 are formed so as to extend in a region where the portion intersects with the second conductive film 28 and in the vicinity thereof.

次いで、Ｔｉ、Ａｌ、合金などの、所定の形状の１層又は２層以上の金属膜を形成することにより、図２（７）に示すように、第２の導電膜２８を形成する。   Next, a second conductive film 28 is formed as shown in FIG. 2 (7) by forming one or more metal films of a predetermined shape such as Ti, Al, and alloy.

次いで、図３（８）に示すように、ＳｉＯ２膜１６ｓを成膜する。 Next, as shown in FIG. 3 (8), a SiO 2 film 16s is formed.

次いで、図３（９）に示すように、ＳｉＮ膜１８ｓを成膜する。   Next, as shown in FIG. 3 (9), a SiN film 18s is formed.

次いで、ＳｉＯ２膜１６ｓとＳｉＮ膜１８ｓをエッチングして、図３（１０）に示すように、ＳｉＯ２膜１６ｓから第２の絶縁膜１６を形成し、ＳｉＮ膜１８ｓから第３の絶縁膜１８を形成する。 Next, the SiO 2 film 16 s and the SiN film 18 s are etched to form the second insulating film 16 from the SiO 2 film 16 s and from the SiN film 18 s to the third insulating film 18 as shown in FIG. Form.

次いで、図３（１１）において矢印５２で示すように、必要に応じて、第３の絶縁膜１８を加工し、周波数特性を調整する。   Next, as shown by an arrow 52 in FIG. 3 (11), the third insulating film 18 is processed as necessary to adjust the frequency characteristics.

次いで、図３（１２）に示すように、第２の導電膜２８の上に、Ａｕでバンプ２９を形成する。   Next, as shown in FIG. 3 (12), bumps 29 are formed of Au on the second conductive film 28.

＜実施例２＞ 実施例２の弾性表面波デバイス１０ａについて、図４を参照しながら説明する。   Example 2 A surface acoustic wave device 10a of Example 2 will be described with reference to FIG.

実施例２の弾性表面波デバイス１０ａは、実施例１の弾性表面波デバイス１０と略同様に構成されている。以下では、実施例１と同様の構成部分には同じ符号を用い、実施例１との相違点を中心に説明する。   The surface acoustic wave device 10a according to the second embodiment is configured in substantially the same manner as the surface acoustic wave device 10 according to the first embodiment. In the following description, the same reference numerals are used for the same components as in the first embodiment, and differences from the first embodiment will be mainly described.

図４は、実施例４の弾性表面波デバイス１０ａの平面図である。図４において右側の部分は、絶縁膜１６，１８を取り除いた状態を示している。   FIG. 4 is a plan view of the surface acoustic wave device 10a according to the fourth embodiment. In FIG. 4, the right part shows a state in which the insulating films 16 and 18 are removed.

図４に示すように、ＩＤＴ２０のバスバー２２と第２の導電膜２８との間に介在する層間接続膜２６ａは、ＩＤＴ２０のバスバー２２上にのみ形成されている。この層間接続膜２６ａとは別に、ＩＤＴ２０と第１の絶縁膜１４との間の境界部分の隙間２１を跨ぐように目張り膜２７が形成され、間張り膜２７の上に第２の導電膜２８が延在している。   As shown in FIG. 4, the interlayer connection film 26 a interposed between the bus bar 22 of the IDT 20 and the second conductive film 28 is formed only on the bus bar 22 of the IDT 20. Apart from the interlayer connection film 26 a, a weathering film 27 is formed so as to straddle the gap 21 at the boundary between the IDT 20 and the first insulating film 14, and the second conductive film 28 is formed on the interlayer film 27. Is extended.

目張り膜２７を設けると、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１と、第２の導電膜２８と第１の絶縁膜１４との界面とは、直接接続されていない。そのため、矢印３０で示すように、外部からの湿気が、圧電基板１２の主面１２ａと第２の導電膜２８との界面の隙間から、第２の導電膜２８と第１の絶縁膜１４との界面の隙間に浸入しても、目張り膜２７で遮断され、外部からの湿気は、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１には達しない。その結果、耐湿性が向上し、弾性表面波デバイス１０ａの耐湿試験において、電気特性の変化を防止することができる。   When the weathering film 27 is provided, the gap 21 at the boundary between the IDT 20 and the first insulating film 14 and the interface between the second conductive film 28 and the first insulating film 14 are not directly connected. Therefore, as indicated by an arrow 30, moisture from the outside passes through the gap between the interface between the main surface 12 a of the piezoelectric substrate 12 and the second conductive film 28 and the second conductive film 28 and the first insulating film 14. Even if it penetrates into the gap at the interface between the IDT 20 and the first insulating film 14, the moisture from the outside does not reach the gap 21 at the boundary between the IDT 20 and the first insulating film 14. As a result, the moisture resistance is improved, and a change in electrical characteristics can be prevented in the moisture resistance test of the surface acoustic wave device 10a.

目張り膜２７は、層間接続膜２６ａと同じ材料で形成しても、層間接続膜２６ａとは異なる材料で形成してもよい。また、絶縁材料を用いて形成してもよい。例えば、ポリイミドなどの不溶性の樹脂材料を用いて目張り膜２７を形成する。   The weathering film 27 may be formed of the same material as the interlayer connection film 26a or may be formed of a material different from that of the interlayer connection film 26a. Alternatively, an insulating material may be used. For example, the weathering film 27 is formed using an insoluble resin material such as polyimide.

目張り膜２７は自由に材料を選択することができるので、第１の絶縁膜１４や第２の導電膜２８とは界面に隙間ができにくい材料を用いて、より耐湿性を向上させることができる。   Since the material for the weathering film 27 can be freely selected, moisture resistance can be further improved by using a material in which a gap is not easily formed at the interface with the first insulating film 14 or the second conductive film 28. .

＜実施例３＞ 実施例３の弾性表面波デバイス１０ｂについて、図５を参照しながら説明する。   Example 3 A surface acoustic wave device 10b of Example 3 will be described with reference to FIG.

図５は、実施例３の弾性表面波デバイス１０ｂの平面図である。図５において右側の部分は、絶縁膜１６，１８を取り除いた状態を示している。   FIG. 5 is a plan view of the surface acoustic wave device 10b according to the third embodiment. The right part in FIG. 5 shows a state where the insulating films 16 and 18 are removed.

実施例３の弾性表面波デバイス１０ｂは、実施例２と同様に、ＩＤＴ２０と第１の絶縁膜１４との間の境界部分の隙間２１を跨ぐように、目張り膜２７が形成され、目張り膜２７の上に第２の導電膜２８が延在している。   In the surface acoustic wave device 10b according to the third embodiment, as in the second embodiment, the skin film 27 is formed so as to straddle the gap 21 at the boundary between the IDT 20 and the first insulating film 14, and the skin film 27 A second conductive film 28 extends on the top.

実施例３の弾性表面波デバイス１０ｂは、実施例１及び実施例２とは異なり、ＩＤＴ２０のバスバー２２と第２の導電膜２８とは、層間接続膜を介することなく、直接接続さている。   In the surface acoustic wave device 10b according to the third embodiment, unlike the first and second embodiments, the bus bar 22 of the IDT 20 and the second conductive film 28 are directly connected without an interlayer connection film interposed therebetween.

弾性表面波デバイス１０ｂには目張り膜２７が設けられているため、実施例２と同様に、耐湿性が向上し、弾性表面波デバイス１０ｂの耐湿試験において、電気特性の変化を防止することができる。また、目張り膜２７は自由に材料を選択することができるので、第１の絶縁膜１４や第２の導電膜２８とは界面に隙間ができにくい材料を用いて、より耐湿性を向上させることができる。   Since the surface acoustic wave device 10b is provided with the cover film 27, the moisture resistance is improved as in the second embodiment, and a change in electrical characteristics can be prevented in the moisture resistance test of the surface acoustic wave device 10b. . Further, since the material for the weather cover film 27 can be freely selected, the moisture resistance is further improved by using a material in which a gap is not easily formed at the interface with the first insulating film 14 or the second conductive film 28. Can do.

＜比較例＞ 比較例の弾性表面波デバイス１０ｘについて、図６を参照しながら説明する。   <Comparative Example> A surface acoustic wave device 10x of a comparative example will be described with reference to FIG.

図６は、比較例の弾性表面波デバイス１０ｘの平面図である。図６において右側の部分は、絶縁膜１６，１８を取り除いた状態を示している。   FIG. 6 is a plan view of a surface acoustic wave device 10x of a comparative example. In FIG. 6, the right part shows a state in which the insulating films 16 and 18 are removed.

図６に示すように、層間接続膜２６ｘは、ＩＤＴ２０のバスバー２２上のみに形成され、本体部のみを有しており、膨出部は形成されていない。第２の導電膜２８とＩＤＴ２０と第１の絶縁膜１４との境界部分とが交差する領域及びその近傍には、目張り膜が形成されていない。   As shown in FIG. 6, the interlayer connection film 26x is formed only on the bus bar 22 of the IDT 20, has only a main body portion, and has no bulging portion. No weathering film is formed in a region where the boundary between the second conductive film 28, the IDT 20, and the first insulating film 14 intersects and in the vicinity thereof.

比較例の弾性表面波デバイス１０ｘは、図６において矢印３０で示すように、外部からの湿気が、圧電基板１２の主面１２ａと第２の導電膜２８との界面の隙間から浸入すると、第２の導電膜２８と第１の絶縁膜１４との界面を経て、矢印３２，３４で示すように、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１に浸入し、ＩＤＴ２０の電極指２４に達する。   In the surface acoustic wave device 10x of the comparative example, as shown by an arrow 30 in FIG. 6, when moisture from the outside enters through a gap at the interface between the main surface 12a of the piezoelectric substrate 12 and the second conductive film 28, 2 enters the gap 21 at the boundary between the IDT 20 and the first insulating film 14 and passes through the interface between the second conductive film 28 and the first insulating film 14, as indicated by arrows 32 and 34. Reach 24.

浸入した湿気が電極指２４の近傍で結露したり、結露によりＩＤＴ２０の電極指２４が腐食したりすると、弾性表面波の音速が変化するため、耐湿試験での電気特性が変化する。   When the infiltrated moisture condenses in the vicinity of the electrode finger 24 or the electrode finger 24 of the IDT 20 corrodes due to dew condensation, the sound speed of the surface acoustic wave changes, and the electrical characteristics in the moisture resistance test change.

これに対し、実施例１〜３のように層間接続膜２６や目張り膜２７を設けると、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１と、第２の導電膜２８と第１の絶縁膜１４との界面とが、直接、接続されないため、ＩＤＴ２０と第１の絶縁膜１４との境界部分の隙間２１への湿気の浸入を遮断することができるため、耐湿性が向上し、耐湿試験での電気特性の変化を防止することができる。   On the other hand, when the interlayer connection film 26 and the cover film 27 are provided as in the first to third embodiments, the gap 21 at the boundary between the IDT 20 and the first insulating film 14, the second conductive film 28, and the first conductive film 28 are provided. Since the interface with the insulating film 14 is not directly connected, moisture intrusion into the gap 21 at the boundary portion between the IDT 20 and the first insulating film 14 can be blocked, thereby improving moisture resistance. It is possible to prevent changes in electrical characteristics in the moisture resistance test.

＜まとめ＞ 以上のように、ＩＤＴ２０と第１の絶縁膜１４との間の境界部分を跨ぐように、層間接続膜２６又は目張り膜２７を設けることにより、耐湿性が向上し、耐湿試験での電気特性の変化を防止することができる。   <Summary> As described above, by providing the interlayer connection film 26 or the cover film 27 so as to straddle the boundary portion between the IDT 20 and the first insulating film 14, the moisture resistance is improved, and the moisture resistance test is performed. Changes in electrical characteristics can be prevented.

なお、本発明は、上記実施の形態に限定されるものではなく、種々変更を加えて実施することが可能である。   The present invention is not limited to the above embodiment, and can be implemented with various modifications.

１０，１０ａ，１０ｂ，１０ｘ 弾性表面波デバイス
１２ 圧電基板
１２ａ 主面
１４ 第１の絶縁膜
１６ 第２の絶縁膜
１８ 第３の絶縁膜
２０ ＩＤＴ（第１の導電膜）
２１ 隙間
２２ バスバー
２４ 電極指
２６ 層間接続膜（目張り膜）
２７ 目張り膜
２８ 第２の導電膜
２９ バンプ 10, 10a, 10b, 10x Surface acoustic wave device 12 Piezoelectric substrate 12a Main surface 14 First insulating film 16 Second insulating film 18 Third insulating film 20 IDT (first conductive film)
21 Gap 22 Bus bar 24 Electrode finger 26 Interlayer connection film (stripping film)
27 Covering film 28 Second conductive film 29 Bump

Claims (2)

圧電基板と、
前記圧電基板の主面にＩＤＴを形成する第１の導電膜と、
前記第１の導電膜に隣接し、かつ前記第１の導電膜の周囲を取り囲むように、前記圧電基板の前記主面に形成された第１の絶縁膜と、
前記圧電基板の前記主面と前記第１の絶縁膜と前記第１の導電膜とに接合されるように形成された第２の導電膜と、
前記第１の絶縁膜に接合され、前記第１の導電膜を覆うように形成された第２の絶縁膜と、
を備えた弾性表面波デバイスにおいて、
前記第１の導電膜と前記第１の絶縁膜との境界部分と前記第２の導電膜とが交差する領域及びその近傍領域において、前記第２の導電膜と前記第１の導電膜との間及び前記第２の導電膜と前記第１の絶縁膜との間に延在するように形成された目張り膜を備えたことを特徴とする、弾性表面波デバイス。 A piezoelectric substrate;
A first conductive film for forming IDT on a main surface of the piezoelectric substrate;
A first insulating film formed on the main surface of the piezoelectric substrate so as to be adjacent to the first conductive film and surround the periphery of the first conductive film;
A second conductive film formed so as to be bonded to the main surface of the piezoelectric substrate, the first insulating film, and the first conductive film;
A second insulating film bonded to the first insulating film and formed to cover the first conductive film;
In a surface acoustic wave device comprising:
In the region where the boundary portion between the first conductive film and the first insulating film intersects the second conductive film and in the vicinity thereof, the second conductive film and the first conductive film A surface acoustic wave device comprising a weather strip formed to extend between and between the second conductive film and the first insulating film. 前記目張り膜は、
前記第１の導電膜に接合された、導電性を有する本体部と、該本体部から、前記第１の導電膜と前記第１の絶縁膜との境界部分を越えて、前記第１の絶縁膜上に膨出した、導電性を有する膨出部とを有する層間接続膜であることを特徴とする、請求項１に記載の弾性表面波デバイス。 The weather membrane is
A main body having conductivity, joined to the first conductive film, and the first insulation from the main body beyond the boundary between the first conductive film and the first insulating film 2. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is an interlayer connection film having a conductive bulge portion that bulges on the film.
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