JP2006303932A - Surface acoustic wave element, and surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave element and a surface acoustic wave device which can be downsized. <P>SOLUTION: The device is provided with a piezoelectric substrate 10, an IDT (Interdigital Transducer) electrode 11 in which many electrode fingers 12, 13 are respectively and alternately concatenated to a pair of power feeding conductors 14, 15 which are formed on a surface of the piezoelectric substrate 10, and face each other, and reflectors 20, 21 which are arranged in both sides of the IDT electrode 11. in which many reflection fingers 22, 24 are concatenated with facing power feeding conductors 23, 25. A SAW (Surface Acoustic Wave) resonator element 1 is arranged so that the respective power feeding conductors 14, 15 and conducting conductor pads 30, 31 in the IDT electrode 11 are arranged in one side of the power feeding conductor 15. At least another power feeding conductor 14 of the IDT electrode 11 and the power feeding conductor 23 of the other adjoining reflector 20 are connected, and a conductor pad 30 extended and established in a width direction of the power feeding conductor 23 of the reflector 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface acoustic wave element using surface acoustic wave (SAW) and a surface acoustic wave device including the surface acoustic wave element.

  2. Description of the Related Art Conventionally, surface acoustic wave devices that use surface acoustic waves that are provided with IDT (Interdigital Transducer) electrodes and reflectors in which electrode fingers are alternately arranged on the surface of a piezoelectric substrate and that are excited by IDT electrodes have been widely used in various electronic devices in use. In recent years, with the spread of portable electronic devices, there is a demand for further downsizing of surface acoustic wave devices including surface acoustic wave elements.

  In the conventional surface acoustic wave element, as shown in Patent Document 1 (FIGS. 1 and 4), the extraction electrodes are arranged on the feeding conductor side of the IDT electrode so that the electrode fingers of the IDT electrode are independent from each other. . Further, as shown in Patent Document 2 (FIG. 5), a configuration in which extraction electrodes are arranged in the lateral direction of the electrode fingers is also considered.

Japanese Patent Laying-Open No. 2004-304622 (FIGS. 1 and 4) Japanese Patent Laid-Open No. 8-213874 (FIG. 5)

  In considering the miniaturization of the surface acoustic wave device, it is necessary to consider the miniaturization of the surface acoustic wave element provided in the surface acoustic wave device. In Patent Document 1, there are spaces for arranging the extraction electrodes on both sides, and there is a limit to downsizing the surface acoustic wave element. In Patent Document 2, the length of the surface acoustic wave element in the lateral direction varies depending on the design frequency depending on the pitch between the electrode fingers. When the frequency is low (for example, 300 MHz), it is larger than that of the high frequency (for example, 800 MHz). When the surface acoustic wave device having a predetermined size is designed, there is a problem that the degree of freedom in design is hindered. For this reason, the surface acoustic wave element cannot be downsized, and it is difficult to downsize the surface acoustic wave device.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface acoustic wave element and a surface acoustic wave device that can be miniaturized.

  In order to solve the above problems, a surface acoustic wave device according to the present invention includes an IDT in which a plurality of electrode fingers are alternately connected to a piezoelectric substrate and a pair of opposing feed conductors formed on the surface of the piezoelectric substrate. An electrode and a reflector disposed on both sides of the IDT electrode and having a large number of reflecting fingers connected to opposing power supply conductors, and a conductive pad connected to each of the power supply conductors in the IDT electrode is one power supply. A surface acoustic wave element disposed on a conductor side, wherein at least the other power supply conductor of the IDT electrode is connected to a power supply conductor of one reflector adjacent thereto, and the conductive pad is connected to the power supply conductor of the reflector. It is provided by extending in the width direction.

  According to this configuration, one reflector can be used as an extraction electrode from the other feeding conductor in the IDT electrode. In addition, the conductive pads that are electrically connected to the respective power supply conductors can be arranged on one power supply conductor side, and more space is provided compared to the configuration in which the conductive pads are provided on both sides of each power supply conductor as in the conventional configuration. The surface acoustic wave element can be reduced in size.

  The surface acoustic wave device of the present invention is preferably a one-port type provided with one IDT electrode.

  According to this configuration, a miniaturized 1-port surface acoustic wave element can be obtained.

  The surface acoustic wave device of the present invention may be a two-port type including two IDT electrodes.

  According to this configuration, a downsized two-port surface acoustic wave element can be obtained.

  In the surface acoustic wave device of the present invention, it is preferable that a metal joint is further provided at least along the entire periphery of the piezoelectric substrate.

  According to this configuration, for example, the surface acoustic wave element and the insulating substrate are bonded and sealed at the metal joint portion, and the conductive surface is connected to the upper surface of the insulating substrate, thereby forming the elastic surface. It is possible to obtain a downsized surface acoustic wave device having a mounting area of the same size as the wave element.

  A surface acoustic wave device according to the present invention includes the surface acoustic wave element.

  According to this configuration, since the surface acoustic wave element is miniaturized, the surface acoustic wave device can be miniaturized.

  The surface acoustic wave device of the present invention includes a surface acoustic wave element having a metal joint provided along the entire periphery of the piezoelectric substrate, and an insulating substrate, and the surface acoustic wave is provided on the insulating substrate. A through hole provided at a position corresponding to the conductive pad of the element, a metal joint provided along the entire periphery of the lower surface of the insulating substrate, and provided around the opening of the through hole on the lower surface of the insulating substrate. A connection electrode; and an external electrode provided around the opening of the through hole on the upper surface of the insulating substrate, wherein the surface acoustic wave element and the insulating substrate are bonded to the metal of the surface acoustic wave element. The surface acoustic wave element and the insulating substrate are bonded to each other and the metal bonding portion of the insulating substrate and the conductive pad of the surface acoustic wave element and the connection electrode of the insulating substrate are bonded. The IDT in a space defined between It is integrally joined so as to seal the electrode hermetically, and the IDT electrode and the external electrode, it is desirable that are electrically connected by a conductive material formed in the through-hole.

  According to this configuration, a surface acoustic wave device having the same mounting area as the surface acoustic wave element can be obtained, and a surface acoustic wave device that is downsized and thin can be obtained.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
(First embodiment)

FIG. 1 is a schematic plan view showing a configuration of an embodiment of a surface acoustic wave element to which the present invention is applied. In the present embodiment, a SAW resonator element will be described as an example of a surface acoustic wave element.
The SAW resonator element 1 is a one-port SAW resonator element, and is provided on an IDT electrode 11 formed of a conductive metal material such as an Al film on a piezoelectric substrate 10 such as quartz, and on both sides of the IDT electrode 11. Reflectors 20 and 21 are provided.
A large number of IDT electrodes 11 are arranged so that one electrode finger 13 and the other electrode finger 12 are alternately meshed, one electrode finger 13 is connected to one power supply conductor 15, and the other electrode finger 12 is connected to the other power supply. It is connected to the conductor 14. In this way, the IDT electrode 11 has a structure in which the electrode fingers 12 and 13 are alternately connected to the power supply conductors 14 and 15 that face each other in parallel.

  Further, the reflectors 20 and 21 are arranged so as to sandwich the IDT electrode from both sides in the propagation direction of the surface acoustic wave excited by the IDT electrode 11. The reflectors 20 and 21 include a large number of reflecting fingers 22 and 24, and the reflecting fingers 22 and 24 are connected to power supply conductors 23 and 25 that face each other in parallel.

Further, the other power supply conductor 14 in the IDT electrode 11 is connected to the power supply conductor 23 of the reflector 20, and is extended in the width direction of the one power supply conductor 23 to form a conductive pad 30.
In addition, one power supply conductor 15 in the IDT electrode 11 is connected to a power supply conductor 25 of the reflector 21 and is extended in the width direction of the one power supply conductor 25 to form a conductive pad 31.
The conductive pad 30 and the conductive pad 31 are arranged on the IDT electrode 11 on the side where one power supply conductor 15 is formed.

  The SAW resonator element 1 having such a configuration reflects the surface acoustic wave propagating from the IDT electrode 11 to the outside by the left and right reflectors 20 and 21 in the figure, and confines the surface wave energy in the IDT electrode 11. As a result, resonance characteristics with less loss can be obtained.

As described above, the SAW resonator element 1 as the surface acoustic wave element according to the present embodiment has the conductive pad 30 and the conductive pad 31 arranged on the feeding conductor 15 side of the IDT electrode 11, and has a conventional configuration. In addition, the space can be reduced and the size of the SAW resonator element 1 can be reduced as compared with the configuration in which the conductive pads are provided on the respective feeding conductors 14 and 15 side.
(Second Embodiment)

Moreover, although the 1-port SAW resonator element has been described in the above embodiment, the invention can also be implemented in a 2-port SAW resonator element.
FIG. 2 is a schematic plan view showing the configuration of a two-port SAW resonator element as a second embodiment to which the present invention is applied.

The SAW resonator element 2 includes two IDT electrodes 50 and 55 formed on the piezoelectric substrate 10 and reflectors 60 and 61 provided on both sides of the IDT electrodes 50 and 55.
A large number of IDT electrodes 50 are arranged so that one electrode finger 52 and the other electrode finger 51 are alternately meshed, one electrode finger 52 is connected to one power supply conductor 54, and the other electrode finger 51 is connected to the other power supply. The conductor 53 is connected.
Similarly, a large number of IDT electrodes 55 are arranged so that one electrode finger 57 and the other electrode finger 56 are alternately meshed, one electrode finger 57 is connected to one power supply conductor 59, and the other electrode finger 56 is connected to the other electrode finger 56. The power supply conductor 58 is connected.

  The reflectors 60 and 61 are arranged so as to sandwich the IDT electrodes 50 and 55 in the direction in which the surface acoustic waves excited by the IDT electrodes 50 and 55 propagate. The reflectors 60 and 61 include a large number of reflecting fingers 62 and 64, and the reflecting fingers 62 and 64 are connected to power supply conductors 63 and 65 that face each other substantially in parallel.

Further, the other power supply conductor 53 in the IDT electrode 50 is connected to the power supply conductor 63 of the reflector 60 and is extended in the width direction of the one power supply conductor 63 to form a conductive pad 70.
The other power supply conductor 58 in the IDT electrode 55 is connected to the power supply conductor 65 of the reflector 61, and is extended in the width direction of the one power supply conductor 65 to form a conductive pad 73.
A conductive pad 71 extending in the width direction is formed from one power supply conductor 54 of the IDT electrode 50, and a conductive pad 72 extending in the width direction is formed from one power supply conductor 59 of the IDT electrode 55. Has been.
Thus, the conduction pads 70, 71, 72, 73 are arranged on the side where the feed conductors 54, 59 are formed. The conductive pads 70 and 72 are input / output pads, and the conductive pads 71 and 73 are configured as ground pads.

As described above, in the SAW resonator element 2 as the surface acoustic wave element in the present embodiment, the conductive pads 70, 71, 72, and 73 are arranged on one side, respectively, as in the conventional configuration. Compared to the configuration in which the conductive pads are provided on both sides of the power supply conductor, the space can be reduced, and the SAW resonator element 2 can be downsized.
(Modification)

  Next, a modified example of the surface acoustic wave element suitable for further downsizing the surface acoustic wave device will be described.

FIG. 3 and FIG. 4 are schematic plan views showing the configuration of a modification of the surface acoustic wave element.
FIG. 3 shows a 1-port SAW resonator element, and FIG. 4 shows a 2-port SAW resonator element. In these drawings, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

The SAW resonator element 3 in FIG. 3 has the following configuration added to the SAW resonator element 1 described in FIG. That is, the metal bonding portion 35 formed over the entire circumference and the extraction pads 32 and 33 are provided on the conduction pad 30 and the conduction pad 31 in the peripheral portion of the piezoelectric substrate 10.
Further, the SAW resonator element 4 in FIG. 4 has the following configuration added to the SAW resonator element 2 described in FIG. That is, the metal joint 78 formed on the entire periphery of the piezoelectric substrate 10, the conductive pad 70, the conductive pad 71, the conductive pad 72, and the conductive pad 73 are connected to the extraction electrodes 74, 75, 76, and 77, respectively. And are provided.
The metal joint portions 35 and 78 and the extraction electrodes 32, 33, 74, 75, 76, and 77 are formed of a Cr / Au film or a Cr / Ni / Au film.

The SAW resonator elements 3 and 4 having the above-described configuration and, for example, an insulating substrate are bonded and sealed at a metal joint portion, and are configured to be electrically connected from the extraction electrode to the upper surface of the insulating substrate. A SAW resonator as a surface wave device can be obtained.
In addition, it is also possible to directly draw out the terminal from the conductive pad without providing the extraction electrodes 32, 33, 74, 75, 76, 77.

  As described above, by using the SAW resonator elements 3 and 4, the SAW resonator having the same mounting area as the SAW resonator element can be obtained, and the SAW resonator element can be downsized. Can be fully enjoyed.

The piezoelectric substrate 10 described in the above embodiment can use a piezoelectric material such as lithium tantalate or lithium niobate in addition to quartz.
(Third embodiment)

Next, an embodiment of a surface acoustic wave device will be described.
FIG. 5 shows a configuration of a SAW resonator as a surface acoustic wave device. FIG. 5A is a schematic plan view of the SAW resonator, and FIG. 5B is a schematic cross-sectional view taken along the line AA of FIG.

In the present embodiment, the SAW resonator element 3 described with reference to FIG. 3 is used as the SAW resonator element of the SAW resonator 5.
The SAW resonator 5 has a structure in which the SAW resonator element 3 and a glass substrate 100 as an insulating substrate are directly joined. The glass substrate 100 has a tapered through hole 101 formed from the upper surface to the lower surface. The through holes 101 are arranged corresponding to the extraction electrodes 32 and 33 of the SAW resonator element 3, respectively. On the lower surface of the glass substrate 100, a connection electrode 102 having a shape corresponding to the extraction electrodes 32 and 33 is formed on the opening periphery of the through hole 101. Furthermore, a metal joint 103 is provided on the lower surface of the glass substrate 100 over the entire periphery.

The inner peripheral surface of the through-hole 101 and the connection electrode 102 continuous thereto is covered with a metal film 104. In addition, on the upper surface of the glass substrate 100, an external electrode 105 is formed on the opening periphery of the through hole 101. The external electrode 105 is electrically connected to the connection electrode 102 through the metal film 104 in the adjacent through hole 101.
In the SAW resonator element 3 and the glass substrate 100, the metal joint portion 35 and the metal joint portion 103, and the extraction electrodes 32 and 33 and the connection electrode 102 are integrally joined by thermocompression bonding, and the SAW resonator element 3 and the glass substrate 100 are joined together. The IDT electrode 11 and the reflectors 20 and 21 are hermetically sealed in a space defined by 100.

Each electrode finger of the IDT electrode 11 is electrically connected to the external electrode 105 through the extraction electrodes 32 and 33 and the connection electrode 102 joined thereto. The through hole 101 is filled with a sealing material 106 made of a conductive material, thereby ensuring conduction between the extraction electrodes 32 and 33 and the connection electrode 102 and the external electrode 105.
As the material of the sealing material 106, AuSn, AuGe, a solder material, or the like can be used.

Thus, by using the SAW resonator element 3 described above, a miniaturized SAW resonator 5 having the same mounting area as the SAW resonator element 3 can be obtained. Further, if the thickness of the SAW resonator element 3 and the glass substrate 100 is made thin, the SAW resonator element 3 having a reduced height can be provided.
Further, the mounting structure of the surface acoustic wave element as the surface acoustic wave device is not limited to the above structure, and various mounting structures can be used, and the surface acoustic wave element is miniaturized. Can be realized.

  As described above, the preferred embodiments of the present invention have been described by using the SAW resonator as an example of the surface acoustic wave element and the surface acoustic wave device, but the present invention can also be implemented in a SAW filter.

FIG. 2 is a schematic plan view showing a configuration of a SAW resonator element in the first embodiment. FIG. 5 is a schematic plan view showing a configuration of a SAW resonator element according to a second embodiment. The schematic plan view which shows the structure of the modification in 1st Embodiment. The schematic plan view which shows the structure of the modification in 2nd Embodiment. It is a block diagram of the surface acoustic wave apparatus in 3rd Embodiment, (a) is a schematic plan view of a SAW resonator, (b) is an AA schematic sectional drawing of the same figure (a).

Explanation of symbols

1, 2, 3, 4 ... SAW resonator element as a surface acoustic wave element, 5 ... SAW resonator as a surface acoustic wave device, 10 ... piezoelectric substrate, 11 ... IDT electrode, 12 ... other electrode finger, 13 ... One electrode finger, 14 ... the other feeding conductor, 15 ... one feeding conductor, 20, 21 ... reflector, 22, 24 ... reflecting finger, 23, 25 ... feeding conductor of the reflector, 30, 31 ... conduction pad, 32, 33 ... Extraction electrode, 35 ... Metal joint, 50, 55 ... IDT electrode, 51 ... Other electrode finger, 52 ... One electrode finger, 53 ... Other feeding conductor, 54 ... One feeding conductor, 56 ... The other electrode finger, 57... One electrode finger, 58... The other feeding conductor, 59... The one feeding conductor, 60 and 61 .. reflector, 62 and 64. 70, 71, 72, 73 ... conductive pads, 100 ... insulating substrate And glass substrates of, 101 ... through hole, 102 ... connection electrodes, 103 ... the metal bonding portion, 104 ... metal film, 105 ... external electrode, 106 ... sealing material.

Claims (6)

A piezoelectric substrate;
An IDT electrode in which a number of electrode fingers are alternately connected to a pair of opposing feed conductors formed on the surface of the piezoelectric substrate;
A reflector disposed on both sides of the IDT electrode and having a number of reflective fingers connected to opposing power supply conductors, and a conductive pad electrically connected to each of the power supply conductors in the IDT electrode is provided on one power supply conductor side. A surface acoustic wave device arranged,
At least the other feeding conductor of the IDT electrode is connected to the feeding conductor of one reflector adjacent thereto, and the conduction pad is provided to extend in the width direction of the feeding conductor of the reflector. A surface acoustic wave device.   2. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is a one-port type including one IDT electrode.   2. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is a two-port type including two IDT electrodes. The surface acoustic wave device according to any one of claims 1 to 3,
A surface acoustic wave device further comprising a metal joint at least along the entire periphery of the piezoelectric substrate.   A surface acoustic wave device comprising the surface acoustic wave element according to claim 1. The surface acoustic wave element according to claim 4 and an insulating substrate,
A through hole provided in the insulating substrate at a position corresponding to the conductive pad of the surface acoustic wave element; a metal joint provided along the entire periphery of the lower surface of the insulating substrate; and a lower surface of the insulating substrate A connection electrode provided around the opening of the through hole, and an external electrode provided around the opening of the through hole on the upper surface of the insulating substrate,
The surface acoustic wave element and the insulating substrate join the metal joint portion of the surface acoustic wave element and the metal joint portion of the insulating substrate, and the conduction pad of the surface acoustic wave element and the insulating property By joining the connection electrodes of the substrate, the IDT electrodes are integrally joined so as to be hermetically sealed in a space defined between the surface acoustic wave element and the insulating substrate,
The surface acoustic wave device, wherein the IDT electrode and the external electrode are electrically connected by a conductive material formed in the through hole.

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