JP4423976B2 - Thin film surface acoustic wave devices - Google Patents

Description

  The present invention relates to a thin film surface acoustic wave device, and more particularly to a wiring structure of a thin film surface acoustic wave device.

  In general, surface acoustic wave devices that form resonators, filters, and the like are used for communication equipment and various signal processing. As such a surface acoustic wave device, a thin film surface acoustic wave device in which a piezoelectric thin film such as a ZnO thin film is formed on a substrate such as a silicon substrate is known (for example, see Non-Patent Document 1 below). In a conventional thin film surface acoustic wave device, an IDT (interdigital converter, for example, comb-like electrode) and a reflector are formed on a piezoelectric thin film, and a bus bar for connecting these IDTs and reflectors to each other Wiring for connecting the bus bar to the bonding pad is provided. In a normal surface acoustic wave device, a device chip is disposed in a sealed state inside a casing, and a bonding pad formed on the device chip and an external terminal provided on the casing are conductively connected by a conductive wire. It has become.

In particular, a general semiconductor integrated circuit forms various semiconductor elements and wirings by monolithically forming various semiconductor elements on the surface region of a silicon substrate or by forming a thin film structure on the silicon substrate. Usually, in communication circuits and various signal processing circuits, many parts are configured as semiconductor integrated circuits. For example, the above-described surface acoustic wave device is formed on a silicon substrate on which a semiconductor integrated circuit is configured. It is considered that the configuration is an important point in promoting the miniaturization of the communication circuit and the signal processing circuit. For this reason, conventionally, surface acoustic wave devices formed on a silicon substrate constituting a semiconductor integrated circuit have been proposed (for example, see Patent Documents 1 and 2 below).
Tsutsuo Sanro and 4 others “Thin Film Surface Acoustic Wave Devices” Matsushita Technical Report Vol.22 No.6 Dec 1976 P.905-923 JP-A-6-125226 JP 2000-151451 A

  However, as described above, in a surface acoustic wave device formed on a conductive substrate such as a silicon substrate or a substrate having a conductive film on the surface, the surface acoustic wave element structure is not between the substrate and the conductive film. There is a problem that the parasitic capacitance is increased, and the resonator and filter characteristics are deteriorated by the parasitic capacitance.

  Therefore, the present invention solves the above-mentioned problems, and the problem is that by reducing the parasitic capacitance generated between the substrate and the conductive film disposed under the piezoelectric thin film, the resonator characteristics and the filter are reduced. An object of the present invention is to provide a thin film surface acoustic wave device capable of improving characteristics.

  In view of such circumstances, the thin film surface acoustic wave device of the present invention is a thin film surface acoustic wave device having a substrate, a piezoelectric thin film disposed on the substrate, and an electrode formed on the surface of the piezoelectric thin film. In addition, at least a part of the wiring layer conductively connected to the electrode is disposed in a region overlapping the electrode in a plan view.

  According to the present invention, at least a part of the wiring layer conductively connected to the electrode is disposed in a region overlapping with the electrode in a plane, so that the electrode formed on the surface of the piezoelectric thin film and the conductive connection therewith It is possible to reduce the planar occupation area of the wiring layer thus formed, and it is possible to reduce the parasitic capacitance generated between the electrode and the wiring layer and the substrate or the conductive film disposed below the electrode and the wiring layer. . Therefore, the characteristics of the thin film surface acoustic wave device can be improved. Specifically, the insertion loss and impedance of the thin film surface acoustic wave device can be reduced.

  Here, the electrode according to the present invention may be formed on the surface of the piezoelectric thin film. That is, an electrode may be formed on the surface of the piezoelectric thin film opposite to the substrate, and an electrode may be formed on the surface of the piezoelectric thin film on the substrate side. Examples of the electrode include an excitation electrode for generating surface acoustic waves and a detection electrode for detecting surface acoustic waves. Usually, these electrodes are preferably comb-like electrodes constituting an IDT (interdigital converter). Moreover, the reflective electrode which comprises the reflector for reflecting a surface acoustic wave may be sufficient.

  In the present invention, the region is configured on the opposite side of the surface of the piezoelectric thin film on which the electrode is formed, and the electrode is electrically connected to the wiring layer through a through hole formed in the piezoelectric thin film. It is preferable that they are connected. According to this, it can be configured such that at least a part of the wiring layer is arranged in a region overlapping the electrode in a plane on the side opposite to the electrode of the piezoelectric thin film. In this case, for example, when the electrode is formed on the surface of the piezoelectric thin film opposite to the substrate, the wiring layer is formed on the substrate side of the piezoelectric thin film. When the electrode is formed on the substrate side, a wiring layer is formed on the opposite side of the piezoelectric thin film from the substrate.

  In this case, it is preferable that the region is provided in an insulating layer formed between the substrate and the piezoelectric thin film. In this case, since the wiring layer is provided inside the insulating layer, nonuniformity of the electric field distribution of the piezoelectric thin film caused by the wiring layer can be reduced. Further, when the substrate is made of a conductive material or a semiconductor material, it is possible to ensure insulation from the substrate. A specific structure in which the wiring layer is arranged inside the insulating layer includes a structure in which a wiring layer is formed on a lower insulating layer and another upper insulating layer is formed on the wiring layer.

  In the present invention, a surface insulating layer in contact with the surface of the piezoelectric thin film on which the electrode is formed is configured, the region is configured on the opposite side of the surface insulating layer from the piezoelectric thin film, and the electrode includes the electrode It is preferable that the wiring layer is conductively connected through a through hole formed in the surface insulating layer. According to this, the wiring layer is formed on the surface opposite to the piezoelectric thin film of the surface insulating layer in contact with the electrode forming surface of the piezoelectric thin film, and the electrode is connected to the electrode through the through hole formed in the surface insulating layer. By forming a conductively connected wiring layer on the insulating layer, at least a part of the wiring layer can be disposed so as to overlap the electrode.

  In the present invention, the substrate is preferably a silicon substrate. According to this, since a semiconductor integrated circuit or the like can be appropriately formed on the silicon substrate, a circuit structure such as a semiconductor integrated circuit and a thin film surface acoustic wave device can be integrally formed. In this case, as described above, it is desirable to form the piezoelectric thin film, the electrode, and the wiring layer on the silicon substrate via the insulating layer.

  In the present invention, it is preferable that a conductive film is formed on at least the entire effective region of the surface acoustic wave device on the side opposite to the surface on which the electrodes of the piezoelectric thin film are formed. According to this, since the potential gradient on the surface opposite to the surface on which the surface acoustic wave of the surface acoustic wave device propagates can be reduced, the electromechanical coupling coefficient is a high value even with a thin piezoelectric film that is easy to form. Therefore, the propagation characteristics of the surface acoustic wave device can be improved.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a schematic longitudinal sectional view showing a schematic structure of a thin film surface acoustic wave device 100 according to a first embodiment of the present invention, and FIG. 2 is a schematic plan view of the thin film surface acoustic wave device 100. The thin film surface acoustic wave device 100 includes a metal such as SiO ₂ , PSG (phosphorus doped glass), TiO ₂ , and Ta ₂ O ₅ on a substrate 101 formed of a silicon substrate, a glass substrate, a quartz substrate, a ceramic substrate, or the like. An insulating layer 102 made of oxide, silicon nitride such as Si ₃ N ₄ , synthetic resin such as acrylic resin, or the like is formed. The insulating layer 102 is used to insulate between the substrate and the upper conductor when the substrate 101 is a conductor substrate or a semiconductor substrate.

  Even if the substrate 101 is a silicon substrate, it may be a conductor or a semiconductor and has a certain degree of conductivity and may have an insulating property such as an intrinsic semiconductor. In particular, the insulating layer 102 is required. In the latter case, the insulating layer 102 is not always necessary. Furthermore, an insulator such as a glass substrate, a quartz substrate, or a ceramic substrate can be used as the substrate 101. Even in such a case, the insulating layer 102 is not necessary. Even when the insulating substrate 101 is used, if a conductive film such as a wiring pattern is formed on the surface thereof, the insulating layer 102 is necessary to ensure insulation from the upper layer. There is a case. As this insulating layer 102, it is possible to use an insulating layer for surface coating on a silicon substrate on which a semiconductor integrated circuit is formed as it is.

  On the insulating layer 102, wiring layers 107Ax, 107Ay, 107B, 108x, and 108y are partially formed. These wiring layers are made of aluminum, aluminum alloy, Cu, Cu alloy, Au, Au alloy, Cr, Cr alloy, or the like.

  An insulating layer 103 is formed on the wiring layer. The insulating layer 103 can also be made of the same material as the insulating layer 102. Although the insulating layer 103 can be omitted, it is preferable to provide the insulating layer 103 in order to relax the potential distribution on the lower surface of the piezoelectric thin film 104 described later. When the insulating layer 103 is not present, the wiring layers 107Ax, 107Ay, and 107B are on the lower surface of the piezoelectric thin film 104 described later, that is, on the side opposite to the surface on which electrodes 105Ax, 105Ay, and 105B described later are formed. It will be in contact with the surface.

Surface acoustic waves such as ZnO, AlN, PZT (Pb—Zr—Ti), CdS, ZnS, Bi—Pb—O, LiNbO ₃ , TaNbO ₃ , and KNbO ₃ can be excited on the insulating layer 103. A piezoelectric thin film 104 composed of various piezoelectric bodies is formed. The piezoelectric thin film 104 may be formed over the entire surface of the substrate 101, but is preferably formed on a part of the substrate 101 as in the illustrated example. This is because the substrate 101 may have an area necessary for forming other circuit structures such as a semiconductor integrated circuit, whereas the piezoelectric thin film 104 is necessary for forming a surface acoustic wave device. This is because a minimum area is sufficient, and in the case of the present embodiment, the connection terminals of the surface acoustic wave device are formed in a region away from the piezoelectric thin film.

  The piezoelectric thin film 104 has an appropriate thickness according to its material and crystallinity. For example, the thickness is generally about 0.1 to 5 μm, and particularly preferably about 0.5 to 1.5 μm. If the piezoelectric thin film 104 is too thin, the surface acoustic wave propagation mode is easily affected by the lower layer, and the surface of the piezoelectric thin film (upper surface in the illustrated example) may have insufficient crystallinity. Usually, it is desirable that the thickness of the piezoelectric thin film be one or more wavelengths of the excited surface acoustic wave. Conversely, if the piezoelectric thin film is too thick, the manufacturing process takes time and the manufacturing cost increases, so that the merit of the thin film surface acoustic wave device is reduced.

  Electrodes 105Ax, 105Ay, and 105B are formed on the surface (upper surface) of the piezoelectric thin film 104. Electrode 105Ax. 105Ay is an excitation electrode for exciting the surface acoustic wave. Each of the electrodes 105Ax and 105Ay is provided in a comb-like shape, and the electrodes 105Ax and 105Ay are alternately arranged at a constant interval in the propagation direction of the surface acoustic wave (the left-right direction in the drawing). The electrode 105B is a reflective electrode for constituting a reflector. A reflector (a so-called grating reflector) is configured by arranging a plurality of electrodes 105B at the predetermined intervals in the propagation direction. These reflectors are respectively arranged on both sides in the propagation direction of the arrangement region of the electrodes 105Ax and 105Ay.

  In the present embodiment, the electrodes 105Ax, 105Ay, 105B are formed on the upper surface of the piezoelectric thin film 104, but the electrodes may be formed on the lower surface of the piezoelectric thin film 104. In this case, the surface acoustic wave propagates on the lower surface of the piezoelectric thin film 104.

  Through holes 104 a and 104 b are formed in the piezoelectric thin film 104. Conductive materials 106Ax and 106Ay are disposed inside the through-hole 104a, and these conductive materials also penetrate the insulating layer 103 and are conductively connected to the wiring layers 107Ax and 107Ay. The wiring layer 107Ax is conductively connected to the wiring layer 108x, and the wiring layer 107Ay is conductively connected to the wiring layer 108y. A conductive material 106B is disposed inside the through hole 104b, and these conductive materials also penetrate the insulating layer 103 and are conductively connected to the wiring layer 107B. Further, the wiring layer 108x is conductively connected to the connection terminal (conductive pad) 109x exposed on the insulating layer 103, and the wiring layer 108y is conductively connected to the connection terminal (conductive pad) 109y exposed on the insulating layer 103. Yes.

  At least a part of the wiring layers 107Ax, 107Ay, and 107B is disposed so as to overlap the electrodes 105Ax, 105Ay, and 105B in a plane. In the case of the present embodiment, the wiring layers 107Ax, 107Ay, 107B are configured so that regions that do not overlap with the electrodes 105Ax, 105Ay, 105B in a plane are as small as possible. The wiring layers 107Ax, 107Ay, and 107B are formed so as to conductively connect the plurality of conductive materials that are conductively connected to a plurality of electrodes, respectively, and are conductively connected to the common conductive layers 108x and 108y. It is also formed to do. In this embodiment, the portions where the plurality of electrodes 105Ax, 105Ay, and 105B are electrically connected to each other are the wiring layers 107Ax, 107Ay, and 107B disposed below the piezoelectric thin film 104. Such a portion may be formed on the upper surface of the piezoelectric thin film 104.

  In the above-described embodiment, the electrodes 105Ax, 105Ay, and 105B are formed on the surface of the piezoelectric thin film 104 opposite to the substrate 101. On the contrary, the electrodes are disposed on the bottom surface of the piezoelectric thin film 104 (substrate The wiring layer is formed on the upper surface of the piezoelectric thin film or on an insulating layer formed on the upper surface of the piezoelectric thin film, and through a through hole formed in the piezoelectric thin film. It can be configured to be conductively connected to the electrode. Even in this case, at least a part of the electrode and the wiring layer is configured to overlap each other in a plane.

  FIG. 3 is a schematic longitudinal sectional view showing a surface acoustic wave device 200 according to a modification of the above embodiment. In this modification, the insulating layer 203, the piezoelectric thin film 204, the electrodes 205Ax, 205Ay, and 205B, the conductive materials 206Ax, 206Ay, and 206B, the wiring layers 207Ax, 207Ay, 208x, and 208y, and the connection terminals 209x and 209y are as described in the first embodiment. Since it is the same as that of a form, these description is abbreviate | omitted.

  In this surface acoustic wave device 200, a substantial surface acoustic wave propagation region (electrodes 205 Ax and 205 Ay of the surface acoustic wave device formed on the upper layer between the substrate 201 and the insulating layer 202, and electrodes on both sides thereof is provided. The conductive film 211 is provided so as to cover the entire region overlapping with the device effective region, which is a region between the reflector 205B and the device effective region. The conductive film 211 is directly formed on the surface of the substrate 201 when the substrate 201 is an insulating substrate. When the substrate 201 is a conductive substrate or a wiring pattern or the like is formed on the surface of the substrate 201, an insulating film (not shown) is formed on the substrate 201 and then the insulating film is formed on the insulating film. Formed. The conductive film 211 is preferably conductively connected to a constant potential (for example, ground potential). The conductive film 211 relaxes the potential distribution at the bottom of the structural portion of the surface acoustic wave device that is above it, so that the propagation characteristics of the surface acoustic wave can be improved.

  FIG. 4 is an equivalent circuit diagram of the surface acoustic wave device according to the embodiment. The equivalent circuit of the thin film surface acoustic wave device 100 includes a series circuit of an electrostatic capacitance Ca, an inductance La, and a resistor Ra between connection terminals 109x and 109y, and a parallel capacitance (short capacitance) connected in parallel with the series circuit. ) Cs. Here, the series circuit portion is a portion that provides the input / output characteristics of the surface acoustic wave device via the surface acoustic wave, and the parallel capacitance Cs corresponds to the stationary component of the capacitance between the electrodes 105Ax and 105Ay. It is. The above components are the same as the equivalent circuit of a normal surface acoustic wave device. However, in the thin film surface acoustic wave device of this embodiment, the electrodes 105Ax and 105Ay and the substrate 101 are further in parallel with the circuit configuration described above. There is a parasitic capacitance Co that is a capacitance between the two. The parasitic capacitance Co is generated between the electrodes 105Ax and 105Ay, the wiring layers 107Ax, 107Ay, 108x, and 108y and the connection terminals 109x and 109y and the wiring pattern formed on the substrate 101 itself or on the surface or inside thereof. Therefore, if the area of the electrode and the wiring layer is reduced, the parasitic capacitance Co can be reduced as a result, and more electric energy distributed to the capacitors Co, Cs, and Ca is distributed to Cs and Ca. Become so. As a result, the insertion loss and impedance of the thin film surface acoustic wave device 100 can be reduced.

  FIG. 5 is a graph schematically showing the frequency dependence of the insertion loss and impedance of the thin film surface acoustic wave device 100 of the present embodiment. Here, the illustrated solid line indicates the insertion loss of the present embodiment, the illustrated alternate long and two short dashes line indicates the impedance of the present embodiment, and the illustrated dotted line indicates the insertion loss and impedance of the thin film surface acoustic wave device having a conventional structure. Since the total occupied area of the electrode and the wiring layer can be reduced by configuring the electrode and the wiring layer so as to overlap each other in a planar manner as described above, as a result, the parasitic capacitance Co is reduced. Therefore, in this embodiment, the insertion loss is reduced as compared with the conventional structure, and the impedance is also reduced.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG. In this embodiment, the first embodiment and the modification have substantially the same cross-sectional structure, but the first embodiment and the modification are thin film surface acoustic wave devices having a resonator structure. The second embodiment is a transversal type thin film surface acoustic wave device 300 constituting a surface acoustic wave filter having an excitation electrode pair and a detection electrode pair.

  In this thin film surface acoustic wave device 300, insulating layers 302 and 303 similar to the above are laminated on a substrate 301, a piezoelectric thin film 304 is formed thereon, and a wiring layer 307Ax is formed on the insulating layer 302. 307Ay are formed, and the wiring layer is connected to the electrodes 305Ax, 305Ay, 305Bx, 305By and the wiring layers 308Ax, 308Ay, 308Bx on the piezoelectric thin film 304 via the conductive materials 306Ax, 306Ay in the through holes of the piezoelectric thin film 304. The second embodiment is the same as the first embodiment in that the wiring layers 308Ax, 308Ay, 308Bx, and 308By are conductively connected to the connection terminals 309Ax, 309Ay, 309Bx, and 309By on the insulating layer 303 while being conductively connected to 308By.

  In the present embodiment, surface acoustic waves are excited by the electrodes 305Ax and 305Ay constituting the pair of excitation electrode pairs, and this is propagated on the surface of the piezoelectric thin film 304 by the electrodes 305Bx and 305By constituting the pair of detection electrode pairs. It is different from the first embodiment in that it is configured to be detected.

  Also in this embodiment, the electrodes 305Ax, 305Ay, 305Bx, and 305By formed on the surface of the piezoelectric thin film 304, and the wiring layers 307Ax, 307Ay, 307Bx, and 307By formed on the opposite surface of the piezoelectric thin film 304 are used. Since at least a part of the thin film surface acoustic wave device 300 can be reduced in plane area, the parasitic capacitance can be reduced. The performance as a thin film surface acoustic wave device can be improved.

[Third Embodiment]
Next, a thin film surface acoustic wave device 400 according to a third embodiment of the present invention will be described with reference to FIG. In this embodiment, an insulating layer 402 is formed on a substrate 401, and a conductive film 411 formed over the entire effective region of the device, which is a surface acoustic wave propagation region, is formed on the insulating layer 402. A piezoelectric thin film 404 is formed on the conductive film 411, and a surface insulating layer 403 is formed on the piezoelectric thin film 404. On the surface of the piezoelectric thin film 404, electrodes 405Ax, 405Ay, and 405B similar to those in the first embodiment are formed.

  Through holes 403a and 403b are formed in the surface insulating layer 403, conductive materials 406Ax, 406Ay, and 406B are disposed in the through holes 403a and 403b, and the wiring layers 407Ax and 407Ax are formed on the surface of the surface insulating layer 403. 407Ay and 407B are formed. The wiring layer 407Ax is conductively connected to the electrode 405Ax through the conductive material 406Ax, the wiring layer 407Ay is conductively connected to the electrode 405Ay through the conductive material 406Ay, and the wiring layer 407B is connected to the electrode 405B. Conductive connection is made.

The surface insulating layer 403 is made of an insulator such as SiO ₂ or TiO ₂ . The surface insulating layer 403 is preferably formed to a thickness of about 0.1 to 0.5 μm so as not to disturb the excitation of the surface acoustic wave on the surface of the piezoelectric thin film 404. In particular, the thickness of the surface insulating layer 403 is preferably less than half that of the piezoelectric thin film 404. The surface insulating layer 403 is provided to ensure insulation other than the conductive connection between the electrode and the wiring layer, and as a surface protecting insulating film for the piezoelectric thin film 404, and It can also function as an insulating film for compensating temperature characteristics of the surface acoustic wave device.

  Also in the present embodiment, since the wiring layers 407Ax, 407Ay, 407B and at least a part of the electrodes 405Ax, 405Ay, 405B overlap in a plane, the total of the planar occupation areas of the electrodes and the wiring layers can be reduced. As a result, the parasitic capacitance can be reduced, so that the performance as a surface acoustic wave device can be improved.

  In the case of this embodiment, the wiring layers 407Ax and 407Ay are used as they are as connection terminals (conductive pads), so that the area occupied by the electrodes and the wiring layers can be further reduced, thereby further reducing the parasitic capacitance. Can do. In addition, the conductive film 411 of the present embodiment equalizes the surface opposite to the electrode formation surface of the piezoelectric thin film 404 in the same manner as in the above-described modification, and thereby the characteristics of the surface acoustic wave device. Can be improved.

[Production method]
Finally, the manufacturing method of the first embodiment will be described with reference to FIG. First, as shown in FIG. 8A, the insulating layer 102 is formed on the surface of the substrate 101. The insulating layer 102 may be directly formed by a CVD method or the like, or a liquid or pasty base material may be applied by a spin coating method, a roll coating method, a printing method, or the like, and cured by a heat treatment or the like. Good. Next, a conductor film such as aluminum is formed on the insulating layer 102 by using a vapor deposition method, a sputtering method, or the like, and this is patterned by a photolithography method or the like to form the wiring layers 107Ax, 107Ay, 107B, 108x, and 108y. To do.

  Next, as shown in FIG. 8B, an insulating layer 103 is formed on the wiring layer. This insulating layer 103 can be formed by a method similar to that of the insulating layer 102. Next, a piezoelectric thin film 104 is formed on the insulating layer 103. The piezoelectric thin film 104 can be formed by a CVD method such as an MOCVD method (CVD method using an organic metal raw material) or a sputtering method such as an RF sputtering method (applied by applying an RF high frequency electric field).

Further, as shown in FIG. 8C, through holes 104a, 104b, 103a, 103b, and 103c are formed in the piezoelectric thin film 104 and the insulating layer 103. Each through hole can be easily formed using a dry etching method. In particular, in order to form a through hole having a high aspect ratio, it is preferable to use a Deep-RIE (reactive ion etching) method. In this method, dry etching is performed while alternately supplying an etching gas (for example, SF ₆ ) and a prepolymer gas (for example, C ₄ H ₈ ) for forming a polymer film covering the inner surface of the hole formed by the etching. Is the law.

  Thereafter, the conductive material 106Ax, 106Ay, 106B shown in FIG. 1 is disposed in the above-described through holes by filling the conductive paste using a printing method or the like, or using an electroless plating method, and then vapor deposition. The electrodes 105Ax, 105Ay, 105B and the connection terminals 109x, 109y shown in FIG. 1 are formed using a method, a sputtering method, a photolithography method, or the like.

  In each of the embodiments described above, the parasitic capacitance Co is reduced by changing the electrode area S according to the general formula Co = ε × S / d (ε is the dielectric constant, S is the electrode area, and d is the electrode interval). It may be reduced or the electrode interval d may be increased. In this embodiment, the parasitic capacitance is reduced by reducing the substantial electrode area S, but conversely, the electrode interval d acting in the direction of increasing the parasitic capacitance is also substantially reduced. However, since the dielectric constant of the piezoelectric body is generally several times to several tens of times higher than the dielectric constant of dielectrics other than the piezoelectric body, in this embodiment, a portion where no piezoelectric body is interposed is generated in the parasitic capacitance Co. (In other words, the dielectric constant is substantially reduced) also has the effect of reducing the capacitance. Therefore, in the parasitic capacitance Co, the capacitance reduction effect that the dielectric constant is substantially reduced and the capacitance reduction effect due to the substantial reduction in the electrode area S are substantially reduced in the electrode spacing d (for example, some conductors (for example, If the capacitance increase effect due to the fact that the wiring layer) is close to the substrate) is exceeded, as a result, the parasitic capacitance Co is reduced.

  Note that the thin film surface acoustic wave device of the present invention is not limited to the illustrated examples described above, and it is needless to say that various modifications can be made without departing from the gist of the present invention. For example, the IDT (interdigital electrode) of the above embodiment is drawn as a single electrode structure, but various electrode structures such as those having a double (split) electrode structure can be used. Further, in the above embodiment, the description has been given as having a one-terminal pair resonator structure or a transversal filter structure, but various schematic surface acoustic wave device structures such as a two-terminal pair resonator structure are employed. can do.

1 is a schematic longitudinal sectional view of a first embodiment according to the present invention. 1 is a schematic plan view of a first embodiment. The schematic longitudinal cross-sectional view of a modification. FIG. 3 is an equivalent circuit diagram of the first embodiment. The graph which shows the frequency characteristic of the insertion loss and impedance of 1st Embodiment. The schematic plan view of 2nd Embodiment. The schematic longitudinal cross-sectional view of 3rd Embodiment. Schematic process sectional drawing (a)-(c) which shows the manufacturing method of 1st Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Thin film surface acoustic wave device, 101 ... Board | substrate, 102 ... Insulating layer, 103 ... Insulating layer, 104 ... Piezoelectric thin film, 105Ax, 105Ay, 105B ... Electrode, 105a, 105b ... Through-hole, 106Ax, 106Ay, 106B ... Conductive 107Ax, 107Ay, 107B, 108x, 108y ... wiring layer, 109x, 109y ... connection terminal, 403 ... surface insulating layer

Claims (3)

A substrate, a piezoelectric thin film disposed on the substrate, the thin film surface acoustic wave device having the above formed on the surface of the piezoelectric thin film electrodes,
At least a part of the wiring layer conductively connected to the electrode is disposed in a region overlapping the electrode in a plane ,
The region is provided inside an insulating layer formed between the substrate and the piezoelectric thin film,
The thin film surface acoustic wave device , wherein the electrode is conductively connected to the wiring layer through a through hole formed in the piezoelectric thin film . The thin film surface acoustic wave device according to claim 1, wherein the substrate is a silicon substrate. In opposite to the surface on which the electrodes of the piezoelectric thin film is formed, according to claim 1 or claim 2, characterized in that the conductive film on the entire effective area of at least the surface acoustic wave device is formed Thin film surface acoustic wave devices.

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