CN116169977A

CN116169977A - Elastic wave device and module comprising same

Info

Publication number: CN116169977A
Application number: CN202211478990.0A
Authority: CN
Inventors: 廉京日; 中村浩; 塩井伸一
Original assignee: Sanyan Japan Technology Co ltd
Current assignee: Sanyan Japan Technology Co ltd
Priority date: 2021-11-25
Filing date: 2022-11-23
Publication date: 2023-05-26
Also published as: JP2023078039A; JP7370542B2

Abstract

An elastic wave device comprises a piezoelectric substrate, a plurality of IDT electrodes formed on the piezoelectric substrate and comprising a plurality of electrode fingers and bus bars, a plurality of bridge stages formed on the piezoelectric substrate, and a main beam formed on the bridge stages, wherein the main beam and at least one IDT electrode are intersected in a three-dimensional way. Thus, an elastic wave device which is more compact and has excellent characteristics can be provided.

Description

Elastic wave device and module comprising same

Technical Field

The present invention relates to an elastic wave device.

Background

In recent years, with the progress of technology, smartphones and the like representing mobile communication terminals have been remarkably miniaturized and lightweight.

An elastic wave device capable of being miniaturized is used for a filter used in the mobile communication terminal.

In addition, in the mobile communication system, there is a rapid increase in demand for a communication system capable of simultaneously receiving and transmitting, such as a duplexer.

According to the above, a multi-mode resonator having an unbalanced-balanced conversion function, which is a filter at the receiving end of the duplexer, is used.

In addition, with the change of the mobile communication system, the requirements for the specifications of the diplexer are becoming more and more stringent.

In other words, an elastic wave device such as a duplexer that is smaller than the conventional device and has more excellent characteristics is required.

Patent document 1 (japanese patent application laid-open No. 2014-120841) exemplifies a technique concerning an elastic wave device.

Disclosure of Invention

[ problem to be solved by the invention ]

However, the technique illustrated in patent document 1 cannot provide an elastic wave device which is sufficiently miniaturized and has excellent characteristics.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an elastic wave device which is further miniaturized and has excellent characteristics.

[ means for solving the problems ]

The elastic wave device comprises a piezoelectric substrate, a plurality of IDT electrodes formed on the piezoelectric substrate and comprising a plurality of electrode fingers and bus bars, a plurality of bridge stages formed on the piezoelectric substrate, and a main beam formed on the bridge stages, wherein the main beam and at least one IDT electrode are intersected in a three-dimensional way.

In one aspect of the present invention, the main beam is formed of an insulator.

In one aspect of the present invention, at least a portion of the abutment is formed of an insulator.

In one aspect of the present invention, at least a portion of the bridge land is formed on the bus bar.

In one embodiment of the present invention, the elastic wave device further includes reflectors provided at both ends of the IDT electrode, and at least a part of the bridge is formed in a region adjacent to one side of the reflectors opposite to the IDT electrode.

In one aspect of the present invention, the elastic wave device further includes a wiring pattern for electrically connecting the IDT electrodes to each other, and a metal layer formed on the main beam, wherein the metal layer is electrically connected to at least a portion of the wiring pattern.

In one aspect of the present invention, the elastic wave device further includes a metal layer formed on the main beam, the metal layer having a ground potential.

In one aspect of the present invention, the main beam covers a region where two adjacent IDT electrodes are formed, with a space therebetween.

In one embodiment of the present invention, the plurality of IDT electrodes form a transmitting filter and a receiving filter including a multi-modal resonator, and the main beam covers a formation region of the plurality of IDT electrodes forming the multi-modal resonator with a space therebetween.

In one aspect of the present invention, the reception filter includes a plurality of the multimode resonators, the main beam covers all of the IDT electrodes constituting the multimode resonators, a metal layer is formed on the main beam to cover all of the IDT electrodes constituting the multimode resonators, and the metal layer has a ground potential.

In one aspect of the present invention, the area ratio of the formation region of the transmission filter to the device chip is at least twice the area ratio of the formation region of the reception filter to the device chip.

In one embodiment of the present invention, the piezoelectric substrate is bonded to a support substrate made of sapphire, silicon, alumina, spinel, crystal, or glass.

The module of the invention comprises the elastic wave device.

Effects of the invention

According to the present invention, an elastic wave device which is more compact and has excellent characteristics can be provided.

Drawings

Fig. 1 is a cross-sectional view of an elastic wave device of a first embodiment.

Fig. 2 is a schematic diagram of the structure of a device chip.

Fig. 3 is a detailed schematic diagram within the dashed box a of fig. 2.

Fig. 4 is a schematic view of a section along the broken line B of fig. 3.

Fig. 5A is a schematic diagram of the design area of the comparative example.

Fig. 5B is a schematic view of the design area of the first embodiment.

Fig. 6 is a schematic diagram of the pass characteristics of the receiving filters of the first embodiment and the comparative example.

Fig. 7 is a schematic diagram of the pass characteristics of the wide band of the receiving filters of the first embodiment and the comparative example.

Fig. 8 is a schematic diagram of the isolation characteristics of the first embodiment and the comparative example.

Fig. 9 is an exemplary plan view of the elastic wave element as a surface acoustic wave resonator.

Fig. 10 is a cross-sectional view of a module of the second embodiment.

Detailed Description

Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

(first embodiment)

Fig. 1 is a cross-sectional view of an elastic wave device 1 of a first embodiment.

As shown in fig. 1, the acoustic wave device 1 of the first embodiment includes a wiring board 3 and a device chip 5 mounted on the wiring board 3.

In the first embodiment, a transmission filter Tx and a reception filter Rx are formed on the device chip 5. The elastic wave device 1 of the first embodiment is a Duplexer (duplex) of a Band 12 (Band 12).

Of course, as an application object of the present invention, the device chip 5 may be an elastic wave device formed of a band-pass filter, or may be a quad (quadriplex). Also, a diplexer may be formed with two device chips.

The wiring board 3 may be, for example, a multilayer board made of resin, or a low temperature co-fired ceramic (LTCC, low Temperature Co-wireless Ceramics) multilayer board made of a plurality of dielectric layers. The wiring board 3 includes a plurality of external connection terminals 31.

The device chip 5 is provided with a band-pass filter which allows an electric signal of a desired frequency band to pass therethrough. More specifically, the device chip 5 is provided with a reception filter Rx including a multi-mode resonator.

And, a ladder filter is formed on the device chip 5. In the first embodiment, the ladder filter is a transmission filter Tx.

The device chip 5 is a single crystal such as lithium tantalate, lithium niobate, or crystal, or a substrate made of piezoelectric ceramics.

The device chip 5 may be a substrate in which a piezoelectric substrate and a support substrate are bonded. The support substrate is, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a crystal substrate, a glass substrate, or a silicon substrate.

A plurality of electrode pads 9 are formed on the wiring substrate 3. The electrode pads 9 are for example copper or an alloy comprising copper. The thickness of the electrode pad 9 is, for example, 10 μm to 20 μm.

The sealing portion 17 covers the device chip 5. The sealing portion 17 may be formed of an insulator such as a synthetic resin, or a metal may be used.

The synthetic resin is, for example, an epoxy resin, and polyimide may be used, but is not limited thereto. Preferably, the sealing part 17 may be formed using an epoxy resin through a low temperature hardening process.

The device chip 5 is mounted on the wiring substrate 3 by flip-chip bonding via bumps 15.

For example, gold bumps may be used for the bumps 15. The height of the bump 15 is, for example, 20 μm to 50 μm.

The electrode pads 9 are electrically connected to the device chip 5 by means of the bumps 15.

Fig. 2 is a schematic diagram of the structure of the device chip 5.

As shown in fig. 2, an elastic wave element 52 and a wiring pattern 54 are formed on the device chip 5.

A plurality of the elastic wave elements 52 are formed on the device chip 5, wherein a part of the elastic wave elements 52 have a multi-modal resonator (not shown in fig. 2). The elastic wave element 52 may have IDT electrodes. The elastic wave element 52 has a reflector adjacent to the IDT electrode.

The wiring pattern 54 electrically connects the IDT electrodes to each other, and includes a portion having only a first metal layer and a portion including the first metal layer and a second metal layer.

The main beams 62 cover the multi-modal resonator (not shown in fig. 2).

The main beam 62 is disposed on the bridge 60 (not shown in fig. 2, refer to fig. 3) and stereoscopically intersects the multi-modal resonator with a predetermined space therebetween.

The main beams 62 may be formed of polyimide, for example. The main beam 62 may be, for example, an insulator having a film thickness of 1000 nm.

The main beams 62 may be formed of a metal layer. In the case where the main beam 62 is formed of a metal layer, it is desirable to secure a space to such an extent that electrical interference with the elastic wave element 52 does not adversely affect the characteristics of the elastic wave device 1.

In the case where the main beam 62 is formed of a metal layer, the main beam 62 may have a ground potential. Therefore, it is possible to strengthen the ground, reduce the Insertion Loss (Insertion Loss), improve the attenuation characteristics of the broadband domain, and improve the isolation characteristics of the broadband domain.

In the case where the main beam 62 is formed of an insulator, a metal layer may be formed on the main beam 62. The metal layer formed on the main beam 62 may have a ground potential.

Therefore, the grounding can be enhanced, the Insertion Loss (Insertion Loss) can be reduced, the attenuation characteristic of the broadband domain can be improved, and the isolation characteristic of the broadband domain can be improved.

The wiring pattern 54 has a three-dimensional wiring portion 58. The three-dimensional wiring portion 58 is wired such that the first metal layer and/or the second metal layer and the metal layer formed on the insulator intersect each other three-dimensionally with the insulator interposed therebetween. For example, polyimide may be used as the insulator. The insulator is, for example, a thin film with a thickness of 1000 nm.

The elastic wave element 52 and the wiring pattern 54 may be made of a suitable metal or alloy such as silver, aluminum, copper, titanium, palladium, or the like. The pattern of the metal may be a multilayer metal structure formed by stacking a plurality of metal layers. The thickness of the elastic wave element 52 and the wiring pattern 54 may be, for example, 150nm to 8000nm.

The wiring pattern 54 includes a wiring constituted by an antenna pad ANT, an input pad TxIn for transmitting a signal, an output pad RxOut for receiving a signal, and a ground pad GND. The wiring pattern 54 is electrically connected to the elastic wave element 52.

As shown in fig. 2, by forming a plurality of the elastic wave elements 52, a band-pass filter can be constituted. The band pass filter is designed to pass only an electric signal of a desired frequency band among electric signals inputted from the antenna pad ANT or the input pad TxIn of the transmission signal.

An electric signal inputted from the antenna pad ANT or the input pad TxIn of the transmission signal passes through a band pass filter, and an electric signal of a desired frequency band is outputted from the antenna pad ANT or the output pad RxOut of the reception signal.

The electric signal outputted from the antenna pad ANT or the output pad RxOut of the reception signal is outputted from the external connection terminal 31 of the wiring substrate 3 via the bump 15 and the electrode pad 9.

Fig. 3 is a detailed schematic diagram within the dashed box a of fig. 2.

As shown in fig. 3, four elastic wave elements 52 are formed on the device chip 5. The IDT electrodes of any three of the four elastic wave elements 52 are connected to each other to form a multi-modal resonator.

As shown in fig. 3, the device chip 5 is provided with a plurality of bridge 60. The bridge 60 may be formed of polyimide, for example. The bridge 60 may be, for example, an insulator having a film thickness of 1000 nm.

In the case where the bridge 60 is formed of an insulator, the bridge 60 may be formed on the wiring pattern 54 or the bus bar.

The elastic wave element 52 includes a reflector, and as shown in fig. 3, a part of the bridge 60 is formed in a region adjacent to a side of the reflector opposite to the IDT electrode.

In addition, as shown in fig. 3, in order to explain the position of the bridge 60, although the main beam 62 and the metal layer provided on the main beam 62 are omitted, all IDT electrodes of the four multi-modal resonators in the acoustic wave device 1 of the first embodiment are covered by the main beam 62 and arranged to intersect three-dimensionally.

All IDT electrodes of the four multimode resonators are covered with the metal layer provided on the main beam 62 as a ground potential.

The metal layer may also be provided on the entire surface of the main beam 62 to strengthen the ground.

The main beam 62 may also be provided with microstrip lines (Micro Strip lines) and form an inductive element. Comb electrodes may also be provided on the main beams 62 and form capacitive elements. Also, a combination of the above configurations is also possible.

Fig. 4 is a schematic view of a section along the broken line B of fig. 3.

As shown in fig. 4, the elastic wave element 52 and the wiring pattern 54 (first metal layer 541) are formed on the device chip 5.

The bridge 60 is formed on the first metal layer 541. The bridge 60 is polyimide with a thickness of 1000 nm.

The bridge 60 has the main beam 62 formed thereon. The main beams 62 are polyimide with a thickness of 1000 nm.

The main beam 62 has a metal layer M formed thereon. The metal layer M has a thickness of 4000nm and has a ground potential.

And, the metal layer M is formed simultaneously with the second metal layer 542. The second metal layer 542 is formed on a region of the first metal layer 541 of the wiring pattern 54 where the main beam 62 is not formed, and constitutes a part of the wiring pattern 54.

Fig. 5A is a schematic view of the design area of the comparative example, and fig. 5B is a schematic view of the design area of the first embodiment.

Fig. 5A shows a duplexer of a comparative example. The duplexer of the comparative example does not have a bridge abutment, a main beam, and a metal layer formed on the main beam and having a ground potential. In the duplexer of the comparative example, the device chip is the same in size and basic design as the elastic wave device of the first embodiment, and is optimally designed on the premise of not having a bridge abutment, a main beam, and a metal layer formed on the main beam and having a ground potential.

The region RxDA (a) surrounded by a dotted line in fig. 5A shows the region of the reception filter optimally designed in the duplexer of the comparative example. The area of the region RxDA (a) is 487136.2 μm ² 。

Fig. 5B shows the duplexer of the first embodiment. The region RxDA (B) encircled by the dotted line in fig. 5B shows the region of the reception filter optimally designed in the duplexer of the first embodiment. The area of the region RxDA (b) is 446246.2 μm ² 。

The area of the design area of the reception filter of the duplexer in the first embodiment is reduced by about 8.4% as compared with the comparative example.

Thereby, in the duplexer of the first embodiment, the area ratio of the formation region of the transmission filter in the entire region of the device chip 5 is twice or more the area ratio of the formation region of the reception filter in the entire region of the device chip 5.

By expanding the design area of the transmission filter, an elastic wave device with further improved electrical resistance can be provided.

In addition, the characteristics are improved and the elastic wave device is miniaturized compared with the prior art.

As shown in fig. 6, the waveform indicated by the solid line shows the pass characteristics of the receiving filter of the elastic wave device of the first embodiment.

The waveform indicated by the broken line shows the pass characteristics of the receiving filter of the elastic wave device of the comparative example. The elastic wave device of the comparative example is the same as that of the comparative example in fig. 5A.

As shown in fig. 6, in the passband characteristics of the reception filter, the first embodiment is superior to the comparative example.

As shown in fig. 7, waveforms indicated by solid lines show the passing characteristics of the wide band of the receiving filter of the elastic wave device of the first embodiment.

The waveform indicated by the broken line shows the pass characteristics of the wide band of the receiving filter of the elastic wave device of the comparative example. The elastic wave device of the comparative example is the same as that of the comparative example in fig. 5A.

As shown in fig. 7, the first embodiment is superior to the comparative example in attenuation characteristics of the passing characteristics of the wide band.

As shown in fig. 8, the waveform indicated by the solid line shows the isolation characteristic of the elastic wave device of the first embodiment.

Further, the waveform indicated by the broken line shows the isolation characteristic of the elastic wave device of the comparative example. The elastic wave device of the comparative example is the same as that of the comparative example in fig. 5A.

As shown in fig. 8, in the isolation characteristic, the first embodiment is superior to the comparative example.

In other words, according to the present invention, an elastic wave device which is more miniaturized and has excellent characteristics can be provided.

Fig. 9 is an exemplary plan view of the elastic wave element 52 as a surface acoustic wave resonator.

As shown in fig. 9, the device chip 5 is provided with a reflector 52b and a IDT (Interdigital Transducer) a capable of exciting a surface acoustic wave. The IDT 52a has a pair of comb electrodes 52c disposed opposite to each other.

The comb-shaped electrode 52c has a plurality of electrode fingers 52d and a plurality of bus bars 52e connecting the electrode fingers 52 d. The reflectors 52b are disposed on both sides of the IDT 52 a.

The IDT 52a and the reflectors 52b are formed of an alloy of aluminum and copper, for example. The IDT 52a and the reflectors 52b are thin films having a thickness of 150nm to 400nm, for example.

The IDT 52a and the reflectors 52b may be made of other metals, for example, suitable metals such as titanium, palladium, and silver, or alloys containing the metals, or may be made of these alloys.

The IDT 52a and the reflector 52b may be formed of a multilayer metal film structure in which a plurality of metal layers are laminated.

The elastic wave element 52 can obtain a desired characteristic of a band-pass filter, and can be suitably applied to a multi-mode filter or a ladder filter.

(second embodiment)

Next, a second embodiment of the present invention is explained.

Fig. 10 is a cross-sectional view of the module 100 of the second embodiment.

As shown in fig. 10, the elastic wave device 1 is provided on the main surface of the wiring board 130.

The elastic wave device 1 may employ, for example, the duplexer described in the first embodiment or the second embodiment.

The wiring board 130 includes a plurality of external connection terminals 131. The external connection terminal 131 is mounted to a main board of a predetermined mobile communication terminal.

An inductor 111 is provided on the main surface of the wiring board 130 to achieve impedance matching. The inductor 111 may be an integrated passive device (Integrated Passive Device, IPD).

The module 100 seals a plurality of electronic components including the acoustic wave device 1 by a sealing portion 117.

An integrated circuit component IC is provided inside the wiring board 130. The integrated circuit component IC includes a switching circuit and a low noise amplifier, which are not shown in the figure.

Other structures are omitted because they are repeated with the contents of the first embodiment and the second embodiment.

According to the embodiment of the present invention, an elastic wave device having a smaller size and excellent characteristics can be provided.

It should be noted that, of course, the present invention is not limited to the above-described embodiments, but includes all embodiments capable of achieving the object of the present invention.

Also, while at least one embodiment has been described above, it is to be appreciated various alterations, modifications, or improvements will readily occur to those skilled in the art.

Such alterations, modifications, or improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention.

It is to be understood that the aspects of the method or apparatus described herein are not limited in their implementation to the constructions and arrangements of parts described in the foregoing description or shown in the drawings.

The methods and apparatus may be practiced or carried out in other embodiments.

The examples are given for illustration only and are not intended to be limiting.

Further, the descriptions or words used herein are merely for illustration, and are not necessarily limiting.

The use of "including," "comprising," "having," "containing," and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

The use of the word "or any term that is described using" or "may be interpreted as meaning one, more than one, or all of the described terms.

Any terms such as front, back, left, right, top, bottom, upper, lower, longitudinal, and transverse are used for convenience of description and do not limit the position or spatial arrangement of any one of the constituent elements of the present invention. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. An elastic wave device, comprising a piezoelectric substrate, a plurality of IDT electrodes formed on the piezoelectric substrate and including a plurality of electrode fingers and bus bars, a plurality of bridge stages formed on the piezoelectric substrate, and a main beam formed on the bridge stages, characterized in that: the main beam is stereoscopically intersected with at least one IDT electrode.

2. The elastic wave device according to claim 1, wherein: the main beam is formed of an insulator.

3. The elastic wave device according to claim 1, wherein: at least a portion of the bridge abutment is formed of an insulator.

4. The elastic wave device according to claim 1, wherein: at least a portion of the bridge land is formed on the bus bar.

5. The elastic wave device according to claim 1, wherein: the elastic wave device further includes reflectors provided at both ends of the IDT electrode, and at least a part of the bridge is formed in a region adjacent to a side of the reflectors opposite to the IDT electrode.

6. The elastic wave device according to claim 1, wherein: the elastic wave device further comprises a wiring pattern for electrically connecting the IDT electrodes to each other, and a metal layer formed on the main beam, wherein the metal layer is electrically connected to at least a part of the wiring pattern.

7. The elastic wave device according to claim 1, wherein: the elastic wave device also includes a metal layer formed on the main beam, the metal layer having a ground potential.

8. The elastic wave device according to claim 1, wherein: the main beam covers the area where two adjacent IDT electrodes are formed with a space therebetween.

9. The elastic wave device according to claim 1, wherein: the plurality of IDT electrodes form a transmit filter and a receive filter including a multi-modal resonator, and the main beam covers a formation region of the plurality of IDT electrodes forming the multi-modal resonator with a space therebetween.

10. The elastic wave device according to claim 9, wherein: the reception filter includes a plurality of the multimode resonators, the main beam covers all of the IDT electrodes constituting the multimode resonators, a metal layer is formed on the main beam to cover all of the IDT electrodes constituting the multimode resonators, and the metal layer has a ground potential.

11. The elastic wave device according to claim 9, wherein: the area ratio of the forming area of the transmitting filter in the device chip is more than twice the area ratio of the forming area of the receiving filter in the device chip.

12. The elastic wave device according to claim 1, wherein: the piezoelectric substrate is bonded to a support substrate formed of sapphire, silicon, alumina, spinel, crystal, or glass.

13. A module comprising the elastic wave device of any one of claims 1 to 12.