WO2012132877A1 - 弾性波素子およびそれを用いた弾性波装置 - Google Patents
弾性波素子およびそれを用いた弾性波装置 Download PDFInfo
- Publication number
- WO2012132877A1 WO2012132877A1 PCT/JP2012/056408 JP2012056408W WO2012132877A1 WO 2012132877 A1 WO2012132877 A1 WO 2012132877A1 JP 2012056408 W JP2012056408 W JP 2012056408W WO 2012132877 A1 WO2012132877 A1 WO 2012132877A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- bus bar
- electrodes
- auxiliary
- dummy
- Prior art date
Links
- 239000000758 substrate Substances 0.000 claims description 48
- 239000011241 protective layer Substances 0.000 claims description 47
- 239000000463 material Substances 0.000 claims description 30
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 10
- 238000010897 surface acoustic wave method Methods 0.000 description 133
- 239000010408 film Substances 0.000 description 31
- 230000004048 modification Effects 0.000 description 20
- 238000012986 modification Methods 0.000 description 20
- 238000000034 method Methods 0.000 description 15
- 230000008859 change Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 14
- 239000010410 layer Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 244000126211 Hericium coralloides Species 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 239000010409 thin film Substances 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 230000001629 suppression Effects 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 239000011810 insulating material Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000005530 etching Methods 0.000 description 4
- 230000001902 propagating effect Effects 0.000 description 4
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 229910000679 solder Inorganic materials 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- 229910018182 Al—Cu Inorganic materials 0.000 description 1
- -1 Ba x Sr 1-x O 3 Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/10—Mounting in enclosures
- H03H9/1064—Mounting in enclosures for surface acoustic wave [SAW] devices
- H03H9/1085—Mounting in enclosures for surface acoustic wave [SAW] devices the enclosure being defined by a non-uniform sealing mass covering the non-active sides of the BAW device
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14517—Means for weighting
- H03H9/1452—Means for weighting by finger overlap length, apodisation
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14538—Formation
- H03H9/14541—Multilayer finger or busbar electrode
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14544—Transducers of particular shape or position
- H03H9/14547—Fan shaped; Tilted; Shifted; Slanted; Tapered; Arched; Stepped finger transducers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14544—Transducers of particular shape or position
- H03H9/14576—Transducers whereby only the last fingers have different characteristics with respect to the other fingers, e.g. different shape, thickness or material, split finger
- H03H9/14579—Transducers whereby only the last fingers have different characteristics with respect to the other fingers, e.g. different shape, thickness or material, split finger the last fingers having a different shape
Definitions
- the present invention relates to an elastic wave element such as a surface acoustic wave (SAW) element and an elastic wave device using the same.
- SAW surface acoustic wave
- An acoustic wave device having a piezoelectric substrate and an IDT (InterDigital Transducer) electrode (excitation electrode) provided on the main surface of the piezoelectric substrate is known (for example, Patent Document 1 or 2).
- the IDT electrode has a pair of comb electrodes.
- Each comb electrode has a bus bar extending in the SAW propagation direction and a plurality of electrode fingers extending from the bus bar in a direction orthogonal to the SAW propagation direction and arranged in the SAW propagation direction.
- the pair of comb electrodes are arranged so that a plurality of electrode fingers mesh (intersect).
- each comb-tooth electrode of Patent Documents 1 and 2 has a dummy electrode that extends in the SAW propagation direction from the bus bar and whose tip faces the tip of the electrode finger of the other comb-tooth electrode via a gap. .
- Patent Document 1 discloses that the tip of the dummy electrode is thickened. According to Patent Document 1, such a configuration suppresses SAW reflection and scattering around the gap between the tip of the electrode finger and the tip of the dummy electrode, and improves the resonance characteristics and filter characteristics of the acoustic wave device.
- FIG. 15 of Patent Document 2 discloses that the tip of a dummy electrode is connected to the electrode electrode adjacent to the dummy electrode in the SAW propagation direction. According to Patent Document 2, such a configuration reduces the speed of sound in the outer region of the intersecting range of the electrode fingers, confines the SAW in the intersecting range, and improves the characteristics of the acoustic wave device.
- the technique of Patent Document 1 since the tip of the dummy electrode is thickened, the gap between the tip of the dummy electrode and the tip of the electrode finger is reduced, and there is a high possibility that the dummy electrode and the electrode finger are short-circuited. Yes.
- the technique of Patent Document 2 does not focus on the propagation loss of elastic waves in the gap between the tip of the dummy electrode and the tip of the electrode finger, and does not have a shape that suitably suppresses such propagation loss. .
- an acoustic wave device and an acoustic wave device that can reduce the propagation loss of the acoustic wave while suppressing a short circuit between the dummy electrode and the electrode finger.
- An elastic wave device includes a piezoelectric substrate and an IDT electrode positioned on an upper surface of the piezoelectric substrate, and the IDT electrodes face each other in a direction orthogonal to the propagation direction of the elastic wave.
- a plurality of second electrode fingers that extend and are arranged in the propagation direction, and that extend from the first bus bar toward the second bus bar and that are arranged in the propagation direction.
- a plurality of first dummy electrodes whose tips are opposed to the tips of the plurality of second electrode fingers via a gap; tips extending from the second bus bar toward the first bus bar and arranged in the propagation direction; A plurality of second dummy electrodes facing the tips of the plurality of first electrode fingers via a gap; a plurality of first auxiliary electrodes projecting laterally from the tip side portions of the plurality of first dummy electrodes; A plurality of second auxiliary electrodes projecting laterally from tip side portions of the plurality of second dummy electrodes, wherein at least some of the first auxiliary electrodes of the plurality of first auxiliary electrodes are 2
- the edge part on the bus bar side is located closer to the second bus bar side toward the front end side, and the second auxiliary electrode of at least a part of the plurality of second auxiliary electrodes has the edge part on the first bus bar side closer to the front end side. Located on the first bus bar side.
- the acoustic wave device of one embodiment of the present invention includes a piezoelectric substrate and an IDT electrode positioned on the upper surface of the piezoelectric substrate, and the IDT electrodes are opposed to each other in a direction orthogonal to the propagation direction of the acoustic wave.
- One bus bar and a second bus bar a plurality of first electrode fingers extending from the first bus bar toward the second bus bar and arranged in the propagation direction, and extending from the second bus bar toward the first bus bar
- a plurality of first dummy electrodes whose tips are opposed to the tips of the plurality of second electrode fingers via a gap, the tips extending from the second bus bar toward the first bus bar, and arranged in the propagation direction.
- a plurality of second dummy electrodes opposed to the tips of the plurality of first electrode fingers via a gap in front A plurality of second dummy electrodes opposed to the tips of the plurality of first electrode fingers via a gap; a first auxiliary electrode projecting obliquely with respect to the propagation direction from a tip side portion of the plurality of first dummy electrodes; And a second auxiliary electrode protruding obliquely with respect to the propagation direction from the tip side portion of the plurality of second dummy electrodes.
- the elastic wave device includes any one of the elastic wave elements described above and a circuit board on which the elastic wave element is mounted.
- FIG. 1A is a plan view of a SAW element according to an embodiment of the present invention
- FIG. 1B is an enlarged view of a region Ib in FIG. It is sectional drawing in the II-II line
- 3 (a) to 3 (e) are cross-sectional views corresponding to FIG. 2 for explaining a method of manufacturing a SAW element. It is sectional drawing which shows the example of the SAW apparatus to which the SAW element of FIG. 1 is applied.
- FIG. 5A to FIG. 5D are enlarged plan views showing modifications of the auxiliary electrode. It is a top view which shows the modification of a bus bar.
- FIGS. 7A and 7B are diagrams for explaining a method for evaluating SAW propagation loss.
- FIGS. 9A to 9C are views showing the influence of the dimensions of the auxiliary electrode on the SAW propagation loss.
- FIG. 10A and FIG. 10B are enlarged plan views showing other modified examples of the auxiliary electrode. It is an enlarged plan view which shows the other modification of an auxiliary electrode.
- a surface acoustic wave element hereinafter also referred to as a SAW element
- a surface acoustic wave device hereinafter also referred to as a SAW apparatus
- FIG.1 (a) is a top view of the principal part of the SAW element 1 which concerns on embodiment of this invention.
- FIG. 1B is an enlarged view of the region Ib in FIG.
- FIG. 2 is a cross-sectional view taken along line II-II in FIG.
- the SAW element 1 may have either direction upward or downward, but for the sake of convenience, the orthogonal coordinate system xyz is defined below, and the positive side in the z direction is defined as the upper surface. , Terms such as the lower surface will be used.
- the SAW element 1 includes a substrate 3, an IDT electrode 5 and a reflector 7 provided on the upper surface 3a of the substrate 3, an additional film 9 (FIG. 2) provided on the IDT electrode 5 and the reflector 7, and an upper surface 3a. And a protective layer 11 (FIG. 2) covering the additional film 9 from above.
- the SAW element 1 may have wiring for inputting / outputting signals to / from the IDT electrode 5.
- the substrate 3 is constituted by a piezoelectric substrate.
- the substrate 3 is composed of a single crystal substrate having piezoelectricity such as a lithium tantalate (LiTaO 3 ) single crystal, a lithium niobate (LiNbO 3 ) single crystal, or the like. More preferably, the substrate 3 is constituted by a 128 ° ⁇ 10 ° YX cut LiNbO 3 substrate.
- the planar shape and various dimensions of the substrate 3 may be set as appropriate.
- the thickness (z direction) of the substrate 3 is 0.2 mm to 0.5 mm.
- the IDT electrode 5 includes a first comb electrode 13A and a second comb electrode 13B.
- the first comb-tooth electrode 13A and the second comb-tooth electrode 13B are simply referred to as a comb-tooth electrode 13 and may not be distinguished from each other.
- first and “A” may be attached like “first bus bar 21A”, and the configuration related to the second comb-teeth electrode 13B.
- “Second” and “B” may be added, as in “second bus bar 21B”, etc., and “first”, “second”, “A”, and “B” may be omitted. There is.
- Each comb electrode 13 includes a bus bar 21 (FIG. 1A) extending in the SAW propagation direction (x direction), and a plurality of electrode fingers 23 extending from the bus bar 21 in a direction orthogonal to the propagation direction (y direction). have.
- the pair of comb electrodes 13 are arranged so that the plurality of electrode fingers 23 mesh with each other (intersect).
- Each comb electrode 13 includes a plurality of dummy electrodes 25 extending from the bus bar 21 in a direction (y direction) perpendicular to the SAW propagation direction between the plurality of electrode fingers 23, and from the tip side portion of the dummy electrode 25.
- a plurality of auxiliary electrodes 27 extending laterally.
- the bus bar 21 is, for example, formed in a long shape extending with a substantially constant width, and is disposed in parallel with the SAW propagation direction.
- the pair of bus bars 21 oppose each other in a direction orthogonal to the SAW propagation direction.
- the plurality of electrode fingers 23 are arranged at substantially constant intervals in the SAW propagation direction.
- the plurality of electrode fingers 23 of the pair of comb-teeth electrodes 13 have a pitch (repetition interval) p (FIG. 2, for example, a distance between the centers of the electrode fingers 23) of, for example, a SAW wavelength ⁇ at a frequency to be resonated. It is provided so as to be equivalent to a half wavelength.
- the wavelength ⁇ (2p) is, for example, 1.5 ⁇ m to 6 ⁇ m.
- the width w1 (FIG. 2) of each electrode finger 23 is appropriately set according to the electrical characteristics required for the SAW element 1, and is, for example, 0.4p to 0.6p with respect to the pitch p.
- the lengths (positions of the tips in the y direction) of the plurality of electrode fingers 23 change in the SAW propagation direction. Accordingly, the width W (the length in the direction (y direction) perpendicular to the SAW propagation direction) indicated by the dotted line (the line connecting the tips of the plurality of electrode fingers 23) in FIG. (Crossing width) changes in the SAW propagation direction (x direction). That is, the IDT electrode 5 is apodized. By applying such apodization, generation of so-called transverse mode spurious is suppressed.
- the plurality of dummy electrodes 25 are arranged at substantially constant intervals (pitch p) together with the plurality of electrode fingers 23 in each comb electrode 13.
- the tip of the dummy electrode 25 of one comb-tooth electrode 13 is opposed to the tip of the electrode finger 23 of the other comb-tooth electrode 13 via a predetermined gap s1 (FIG. 1B).
- the size of the gap s1 (y direction; hereinafter, this size may also be expressed by the sign of s1) is substantially constant in the plurality of dummy electrodes 25.
- the position (length) of the tip of the dummy electrode 25 changes in the SAW propagation direction, corresponding to the fact that the intersection width W changes in the SAW propagation direction.
- the width of the dummy electrode 25 is equal to the width w1 of the electrode finger 23, and the size of the gap s1 is from ⁇ / 8 to ⁇ / It is about 2 (p).
- the plurality of auxiliary electrodes 27 protrude from the side edges of the tips of the plurality of dummy electrodes 25.
- dummy electrodes 25 in which electrode fingers 23 extending from the same bus bar 21 as the self are located on both sides in this embodiment, dummy electrodes 25 other than the dummy electrode 25 located at the end of the IDT electrode 5
- the auxiliary electrode 27 protrudes from the side edge portions on both sides.
- the tip of the auxiliary electrode 27 is connected to the side edge of the electrode finger 23 adjacent to the dummy electrode 25 extending from the same bus bar 21 as the dummy electrode 25 at the base of the auxiliary electrode 27. That is, the auxiliary electrode 27 connects the dummy electrode 25 and the electrode finger 23 that are to have the same potential.
- the auxiliary electrode 27 extends, for example, so as to be positioned closer to the bus bar 21 side of the other comb-shaped electrode 13 on the tip side (side connected to the electrode finger 23). That is, the first auxiliary electrode 27A extends so as to be located closer to the second bus bar 21B toward the distal end side, and the second auxiliary electrode 27B is inclined so as to be located closer to the first bus bar 21A closer to the distal end side. It extends.
- the first auxiliary electrode extends so as to be inclined toward the second bus bar 21B side toward the distal end side, and the edge portion 27a and the edge portion 27b of the second auxiliary electrode 27B extend toward the first bus bar toward the distal end side. It extends so as to be located on the 21A side.
- the width w2 of the auxiliary electrode 27, the angle ⁇ with respect to the direction orthogonal to the SAW propagation direction (y direction), and the connection position with respect to the dummy electrode 25 may be appropriately set.
- the connection position is defined by, for example, the distance d between the intersection position of the center line of the auxiliary electrode 27 and the center line of the dummy electrode 25 and the tip of the dummy electrode 25.
- the width w2 is, for example, equivalent to the width w1 of the electrode finger 23 and the dummy electrode 25, the angle ⁇ is, for example, about 45 degrees, and the distance d is, for example, 0.20 ⁇ ⁇ 0.40 ⁇ .
- FIG. 1A is a schematic diagram, and actually, a plurality of pairs of comb electrodes having more electrode fingers 23 and the like may be provided. Further, a ladder-type SAW filter in which a plurality of IDT electrodes 5 are connected in a series connection or a parallel connection may be configured, or a dual mode SAW resonance in which a plurality of IDT electrodes 5 are arranged along the x direction. A filter or the like may be configured.
- the IDT electrode 5 is made of, for example, metal.
- the metal include Al or an alloy containing Al as a main component (Al alloy).
- the Al alloy is, for example, an Al—Cu alloy.
- the IDT electrode 5 may be composed of a plurality of metal layers. Various dimensions of the IDT electrode 5 are appropriately set according to electrical characteristics required for the SAW element 1. As an example, the thickness e (FIG. 2) of the IDT electrode 5 is 100 nm to 300 nm.
- the IDT electrode 5 may be directly disposed on the upper surface 3a of the substrate 3 or may be disposed on the upper surface 3a of the substrate 3 via another member.
- Another member is made of, for example, Ti, Cr, or an alloy thereof.
- the thickness of the other member has a thickness that does not substantially affect the electrical characteristics of the IDT electrode 5 (for example, Ti In this case, the thickness is set to 5% of the thickness of the IDT electrode 5).
- the SAW element 1 When a voltage is applied to the substrate 3 by the IDT electrode 5, SAW propagating in the x direction along the upper surface 3a is induced near the upper surface 3a of the substrate 3. The SAW is reflected at the boundary between the electrode finger 23 and the non-arranged region of the electrode finger 23. And the standing wave which makes the pitch of the electrode finger 23 a half wavelength is formed. The standing wave is converted into an electric signal having the same frequency as that of the standing wave, and is taken out by the electrode finger 23. In this way, the SAW element 1 functions as a resonator or a filter.
- the reflector 7 is formed in a lattice shape having a pitch substantially equal to the pitch p of the electrode fingers 23 of the IDT electrode 5.
- the reflector 7 is formed of the same material as the IDT electrode 5 and has a thickness equivalent to that of the IDT electrode 5.
- the protective layer 11 is provided over substantially the entire upper surface 3a of the substrate 3, covers the IDT electrode 5 and the reflector 7 on which the additional film 9 is provided, and also covers the IDT electrode 5 and the reflective surface of the upper surface 3a.
- the part exposed from the vessel 7 is covered.
- the thickness T (FIG. 2) from the upper surface 3 a of the protective layer 11 is set to be larger than the thickness e of the IDT electrode 5 and the reflector 7.
- the thickness T is 200 nm to 700 nm, which is 100 nm or more thicker than the thickness e.
- the thickness T is 0.2 ⁇ to 0.5 ⁇ with respect to the wavelength ⁇ of the SAW from another viewpoint.
- the protective layer 11 is made of an insulating material.
- the protective layer 11 is made of a material such as SiO 2 that increases the propagation speed of the elastic wave when the temperature rises, thereby suppressing a change in electrical characteristics due to a change in the temperature of the SAW element 1. Can do. Specifically, it is as follows.
- the protective layer 11 When the temperature of the substrate 3 rises, the SAW propagation speed on the substrate 3 decreases, and the pitch p increases due to thermal expansion of the substrate 3. As a result, the resonance frequency is lowered and the desired characteristics may not be obtained.
- the protective layer 11 when the protective layer 11 is provided, the elastic wave propagates not only in the substrate 3 but also in the protective layer 11. Since the protective layer 11 is formed of a material (SiO 2 ) that increases the propagation speed of elastic waves when the temperature rises, the entire SAW propagating through the substrate 3 and the protective layer 11 has a speed due to the temperature rise. The change of is suppressed.
- the protective layer 11 also contributes to protecting the IDT electrode 5 from corrosion and the like.
- the surface of the protective layer 11 be free from large irregularities. Since the propagation speed of the SAW propagating on the substrate 3 is affected by the unevenness on the surface of the protective layer 11, and if there is a large unevenness on the surface of the protective layer 11, the resonance frequency of each manufactured SAW element 1 is increased. Large variations will occur. Therefore, if the surface of the protective layer 11 is made flat, the resonance frequency of each acoustic wave element is stabilized. Specifically, it is desirable that the flatness of the surface of the protective layer 11 is 1% or less of the wavelength of SAW propagating on the substrate 3.
- the additional film 9 is for improving the electrical characteristics of the IDT electrode 5 and the reflector 7.
- the additional film 9 is provided over the entire upper surfaces of the IDT electrode 5 and the reflector 7, for example.
- the additional film 9 has a substantially rectangular cross-sectional shape, for example, orthogonal to the longitudinal direction (y direction) of the electrode finger 23.
- the cross-sectional shape of the additional film 9 may be a trapezoid or a dome shape.
- the thickness t (FIG. 2) of the additional film 9 may be appropriately set within a range in which the additional film 9 does not expose the protective layer 11.
- the thickness of the additional film 9 is 0.01 ⁇ to 0.4 ⁇ with respect to the wavelength ⁇ of the SAW.
- the material constituting the additional film 9 is a material having an acoustic impedance different from that of the material constituting the IDT electrode 5, the reflector 7, and the protective layer 11.
- the difference in acoustic impedance is preferably a certain amount or more, for example, 15 MRayl or more, more preferably 20 MRayl or more.
- the IDT electrode 5 is made of Al (acoustic impedance: 13.5 MRayl) and the protective layer 11 is made of SiO 2 (12.2 MRayl), WC (102. 5 MRayl), TiN (56.0 MRayl), TaSiO 2 (40.6 MRayl), Ta 2 O 5 (33.8 MRayl), W 5 Si 2 (67.4 MRayl).
- the acoustic impedance is close, so that the boundary between the electrode finger 23 and the non-arranged region of the electrode finger 23 is acoustic. And the reflection coefficient at the boundary decreases. As a result, the reflected wave of SAW cannot be obtained sufficiently and desired characteristics may not be obtained.
- the additional film 9 formed of a material having an acoustic impedance different from that of the material of the IDT electrode 5 and the protective layer 11 is provided on the upper surface of the IDT electrode 5, so that the electrode finger 23 and the electrode finger 23 are not disposed. The reflection coefficient at the boundary is increased, and desired characteristics are easily obtained.
- the material of the additional film 9 has an elastic wave propagation speed slower than the materials of the IDT electrode 5, the reflector 7, and the protective layer 11. Due to the slow propagation speed, the vibration distribution tends to concentrate on the additional film 9, and the reflection coefficient at the boundary between the electrode finger 23 and the non-arranged position of the electrode finger 23 is effectively increased.
- IDT electrode 5 Al (propagation speed: 5020m / s) is constituted by, in the case where the protective layer 11 is constituted by SiO 2 (5560m / s) is, TaSiO 2 (4438m / S), Ta 2 O 5 (4352 m / s), and W 5 Si 2 (4465 m / s).
- the protective layer 11 is constituted by SiO 2 (5560m / s) is, TaSiO 2 (4438m / S), Ta 2 O 5 (4352 m / s), and W 5 Si 2 (4465 m / s).
- a material having a higher acoustic impedance than a material such as the IDT electrode 5 has a higher degree of freedom in selecting a material having a higher acoustic impedance than a material having a lower acoustic impedance than the material such as the IDT electrode 5. I think that the.
- FIG. 3 (a) to 3 (e) are cross-sectional views corresponding to FIG. 2 for each manufacturing process for explaining the outline of the method for manufacturing the SAW element 1.
- FIG. The manufacturing process proceeds in order from FIG. 3A to FIG.
- the various layers change in shape and the like with the progress of the process, but common symbols may be used before and after the change.
- the conductive layer 15 to be the IDT electrode 5 and the reflector 7 and the additional layer 17 to be the additional film 9 are formed.
- the conductive layer 15 is formed on the upper surface 3a by a thin film forming method such as a sputtering method, a vapor deposition method, or a CVD (Chemical Vapor Deposition) method.
- the additional layer 17 is formed by the same thin film forming method.
- a resist layer 19 is formed as a mask for etching the additional layer 17 and the conductive layer 15 as shown in FIG.
- a negative or positive photosensitive resin thin film is formed by an appropriate thin film forming method, and a part of the thin film is removed at a non-arranged position of the IDT electrode 5 and the reflector 7 by a photolithography method or the like. Is done.
- the additional layer 17 and the conductive layer 15 are etched by an appropriate etching method such as RIE (Reactive Ion Etching). Thereby, the IDT electrode 5 and the reflector 7 provided with the additional film 9 are formed. Thereafter, as shown in FIG. 3D, the resist layer 19 is removed by using an appropriate chemical solution.
- RIE Reactive Ion Etching
- the thin film used as the protective layer 11 is formed by appropriate thin film formation methods, such as sputtering method or CVD method. At this time, unevenness is formed on the surface of the thin film to be the protective layer 11 due to the thickness of the IDT electrode 5 and the like. Then, if necessary, the surface is flattened by chemical mechanical polishing or the like, and a protective layer 11 is formed as shown in FIG. Note that a part of the protective layer 11 may be removed by a photolithography method or the like in order to expose a pad 39 (FIG. 4) described later or the like before or after planarization.
- FIG. 4 is a cross-sectional view showing an example of a SAW device 51 to which the above-described SAW element 1 is applied.
- the SAW device 51 constitutes, for example, a filter or a duplexer.
- the SAW device 51 includes a SAW element 31 and a circuit board 53 on which the SAW element 31 is mounted.
- the SAW element 31 is configured as, for example, a so-called wafer level package SAW element.
- the SAW element 31 includes the above-described SAW element 1, a cover 33 that covers the SAW element 1 side of the substrate 3, a terminal 35 that penetrates the cover 33, and a back surface portion 37 that covers the opposite side of the substrate 3 from the SAW element 1. have.
- the cover 33 is made of resin or the like, and a vibration space 33a for facilitating SAW propagation is formed above the IDT electrode 5 and the reflector 7 (on the positive side in the z direction).
- a wiring 38 connected to the IDT electrode 5 and a pad 39 connected to the wiring 38 are formed on the upper surface 3 a of the substrate 3.
- the terminal 35 is formed on the pad 39 and is electrically connected to the IDT electrode 5.
- the back surface portion 37 includes a back electrode for discharging the charge charged on the surface of the substrate 3 due to a temperature change or the like, and a protective layer covering the back electrode.
- the circuit board 53 is constituted by, for example, a so-called rigid printed wiring board.
- a mounting pad 55 is formed on the mounting surface 53 a of the circuit board 53.
- the SAW element 31 is arranged with the cover 33 side facing the mounting surface 53a.
- the terminals 35 and the mounting pads 55 are bonded by solder 57. Thereafter, the SAW element 31 is sealed with a sealing resin 59.
- the SAW element 1 includes the substrate 3 and the IDT electrode 5 located on the upper surface 3 a of the substrate 3.
- the IDT electrode 5 extends from the first bus bar 21A and the second bus bar 21B to each other in the direction orthogonal to the SAW propagation direction (y direction), and from the first bus bar 21A toward the second bus bar 21B.
- An electrode finger 23B and a plurality of first dummy electrodes that extend from the first bus bar 21A toward the second bus bar 21B, are arranged in the x direction, and have tips that oppose the tips of the plurality of second electrode fingers 23B via gaps s1.
- the edge 27a on the second bus bar 21B side is positioned closer to the second bus bar 21B toward the distal end side, and the plurality of second auxiliary electrodes 27B are on the edge on the first bus bar 21A side.
- the portion 27a is located closer to the first bus bar 21A side toward the distal end side.
- each auxiliary electrode 27 has a gap s1 between the electrode finger 23 and the dummy electrode 25 while ensuring a distance from the tip of the electrode finger 23 having a different potential from that of the auxiliary electrode 27 (the comb tooth electrode 13 to which the auxiliary electrode 27 belongs is different). It can be reduced in the SAW propagation direction (x direction). As a result, the electrode finger 23 and the dummy electrode 25 having different potentials are suppressed from being short-circuited (for example, the first electrode finger 23A and the second dummy electrode 25B), and the SAW diverges in the gap s1 to cause the SAW. Is prevented from occurring.
- the positions of the tips of the plurality of first electrode fingers 23A, the plurality of second electrode fingers 23B, the plurality of first dummy electrodes 25A, and the plurality of second dummy electrodes 25B in the y direction are in the propagation direction (x direction).
- the apodized electrode changes with respect to.
- At least a part of the plurality of first dummy electrodes 25A has the first electrode fingers 23A located on both sides thereof, and a pair of first auxiliary electrodes 27A project from the tip side portion to both sides of the side.
- the edge portion 27a on the second bus bar 21B side is located closer to the second bus bar 21B side toward the distal end side. The same applies to the second comb electrode 13B side.
- the two auxiliary electrodes 27 are arranged so as to sandwich the gap s1, and it is preferable to diverge both the excited SAW and the reflected SAW from the bidirectional SAW in the propagation direction, from another viewpoint. Can be suppressed. In addition, it is easy to secure the area of the auxiliary electrode 27 around the gap s1, and also from this point, the SAW divergence suppressing effect is improved.
- the tips of the plurality of first auxiliary electrodes 27A are connected to the plurality of first electrode fingers 23A, and the tips of the plurality of second auxiliary electrodes 27B are connected to the plurality of second electrode fingers 23B.
- the potentials of the electrode finger 23, the dummy electrode 25, and the auxiliary electrode 27 that should have the same potential are relatively stable, and the electrical characteristics of the IDT electrode 5 are stabilized. Further, even if the dummy electrode 25 or the electrode finger 23 is missing at the root due to a problem in the process, the dummy electrode 25 or the electrode finger 23 is electrically connected to the adjacent electrode finger 23 or the dummy electrode 25 via the auxiliary electrode 27. Connection is maintained. For this reason, an improvement in yield is expected.
- the tip of the dummy electrode 25 and the dummy electrode are outside the intersection range R1. 25 the gap between the electrode fingers 23 arranged in parallel with 25 is closed over (almost) the entire SAW propagation direction, so that it is expected that the divergence of the SAW to the outside of the intersection range R1 is suppressed.
- the SAW element 1 further includes a protective layer 11 that covers the IDT electrode 5 and the upper surface 3a of the substrate 3 and is made of SiO 2 in which the thickness T from the upper surface 3a of the substrate 3 is larger than the thickness e of the IDT electrode 5.
- a protective layer 11 that covers the IDT electrode 5 and the upper surface 3a of the substrate 3 and is made of SiO 2 in which the thickness T from the upper surface 3a of the substrate 3 is larger than the thickness e of the IDT electrode 5.
- the protective layer 11 having the same acoustic impedance as the IDT electrode 5 is present in the gap s1.
- the SAW divergence in the gap s1 is suppressed, the divergence suppression effect is added to the divergence suppression effect by the auxiliary electrode 27, and the SAW propagation loss is further suppressed.
- the protective layer 11 can contribute to suppression of SAW divergence, the auxiliary electrode 27 can be made smaller, and as a result, the distance between the electrode finger 23 and the dummy electrode 25 that should have different potentials is secured. can do.
- the SAW element 1 is located on the upper surface of the IDT electrode 5 and is covered with a protective layer 11.
- the SAW element 1 is made of a material having a larger acoustic impedance and a lower propagation speed of elastic waves than the material of the IDT electrode 5 and the material of the protective layer 11.
- the additional film 9 is further provided.
- the disadvantages related to the reflection coefficient of the protective layer 11 can be compensated.
- the SAW divergence suppressing effect in the gap s1 by the protective layer 11 is reduced. Therefore, the effect of suppressing divergence by the auxiliary electrode 27 becomes significant.
- a SAW element having excellent temperature characteristics, a sufficient SAW reflection coefficient, and excellent SAW propagation loss suppression can be obtained.
- (Modification) 5 (a) to 5 (d) are diagrams corresponding to FIG. 1 (b) showing a modification of the planar shape of the auxiliary electrode.
- the shapes of the second auxiliary electrodes 27B, 127B, and 227B on the second bus bar 21B side are shown, but the shape of the first auxiliary electrode on the first bus bar 21A side is also the second auxiliary electrode. It is the same as the shape of the electrode.
- the auxiliary electrode 127 is not connected to the electrode finger 23 whose tip should be at the same potential. Even in this case, similarly to the auxiliary electrode 27 of the embodiment, it is possible to suppress the divergence of the SAW in the gap s1 while suppressing a short circuit with the electrode finger 23 that should have a different potential.
- the auxiliary electrode 27 similar to that of the embodiment is provided only on one side of the dummy electrode 25. Even in this case, similarly to the embodiment, it is possible to suppress the divergence of the SAW in the gap s1 while suppressing a short circuit with the electrode fingers 23 that should have different potentials.
- auxiliary electrodes 27 and 227 are provided.
- Each of the auxiliary electrodes 27 and 227 (the edge on the side of the intersection range R1 (see FIG. 1A)) is along a line connecting the tip of the dummy electrode 25 with respect to the SAW propagation direction (x direction). It extends incline toward the side, and preferably extends along a line connecting the tips of the dummy electrodes 25.
- each dummy electrode 25 has an auxiliary electrode 27 on one side and an auxiliary electrode 227 on the other side according to the shape of the intersection range R1 (according to the position in the x direction) (see FIG. 5 (c), auxiliary electrodes 27 are provided on both lateral sides, and auxiliary electrodes 227 are provided on both lateral sides.
- the auxiliary electrode 227 shown in FIG. 5C is provided only on one side of the dummy electrode 25.
- SAW divergence is achieved by enlarging the electrode area in the vicinity of the gap s1 while securing a distance from the tip of the electrode finger 23 that should have a different potential and suppressing a short circuit. Can be suppressed.
- the modification of FIG. 5B can be regarded as the auxiliary electrode 227 omitted in the modification of FIG. 5C in the range shown in FIG. 5B.
- the auxiliary electrode 27 can be regarded as being omitted from the modification shown in FIG. 5C within the range shown in FIG. That is, in the modified examples of FIG. 5B to FIG. 5D, in the apodized electrode, the auxiliary electrode is inclined to the side along the line connecting the tip of the dummy electrode 25 with respect to the SAW propagation direction. It can be grasped by the same concept.
- FIG. 6 is a plan view similar to FIG. 1A showing a modification of the planar shape of the bus bar.
- the bus bar 321 extends such that the edge 321a on the crossing range R1 side is inclined toward the side where the edge of the crossing range R1 is inclined.
- the edge part 321a and the edge part of the crossing range R1 may be parallel, and may not be parallel.
- the SAW element 1 was manufactured by setting various shapes and dimensions of the auxiliary electrode. Then, the electrical characteristics were examined to evaluate the SAW propagation loss.
- FIG. 7A and FIG. 7B are diagrams for explaining an evaluation method of SAW propagation loss.
- FIG. 7A is a diagram illustrating impedance characteristics of the SAW element 1 as a resonator.
- the horizontal axis indicates the frequency f (MHz), and the vertical axis indicates the absolute value
- the solid line Lz is the absolute value of the impedance
- FIG. 7B is a diagram showing the relationship between the maximum phase ⁇ max and the SAW propagation loss LS.
- the horizontal axis represents the propagation loss LS (dB / ⁇ m)
- the vertical axis represents the maximum phase ⁇ max.
- the loss of the resonator As shown in this figure, the smaller the loss of the resonator, the larger the maximum phase ⁇ max. Therefore, the loss of the resonator can be evaluated by examining the maximum phase ⁇ max. In the ideal state with no loss, the maximum phase ⁇ max is 90 (deg.).
- the phase ⁇ changes gently with respect to the change in the frequency f in the vicinity of the maximum phase ⁇ max, while the absolute value
- auxiliary electrode 27 (Influence of auxiliary electrode shape) Comparative Examples 1 to 3 (C1 to C3) and Examples 1 to 3 (E1 to E3) having different auxiliary electrode shapes were set, and SAW propagation loss was evaluated.
- the auxiliary electrode 27 is provided for all dummy electrodes.
- FIG. 8 is a diagram showing the conditions and evaluation results.
- the horizontal axis indicates C1 to C3 and E1 to E3
- the vertical axis indicates the improvement amount d ⁇ max of the maximum phase ⁇ max of each comparative example and example with reference to the maximum phase ⁇ max of C1. .
- Comparative Example 1 (C1) is one in which no auxiliary electrode is provided.
- the tip of the dummy electrode is formed in a circular shape.
- auxiliary electrodes 27 positioned closer to the intersection range R1 toward the distal end are provided on both sides of the dummy electrode.
- Comparative Example 3 (C3) is provided with an auxiliary electrode parallel to the SAW propagation direction.
- the auxiliary electrode 227 located on the side opposite to the intersection range R1 is provided on the one side of the dummy electrode toward the tip side. Is.
- auxiliary electrodes 27 and 227 are provided on both sides of the dummy electrode along a line connecting the tips of the dummy electrodes, as in the modification shown in FIG. 5C. It is.
- Example 1 has a greater effect of suppressing a reduction in propagation loss of SAW than any of Comparative Examples and Examples.
- Example 3 the short-circuit between the electrode finger and the dummy electrode, which should have a different potential, is suppressed as compared with Comparative Example 2 while obtaining the SAW propagation loss reduction suppressing effect equivalent to that of Comparative Example 2.
- the maximum phase of the auxiliary electrode 27 is considered to be improved in proportion to the number of dummy electrodes having the auxiliary electrode 27. Considering these two things and the result of Example 1 in which the auxiliary electrode 27 is provided for all dummy electrodes, if the auxiliary electrode 27 is provided at least 10% of all the dummy electrodes, the value due to measurement variation It is considered that the above effects can be obtained.
- auxiliary electrode dimensions (Influence of auxiliary electrode dimensions) Similarly to the embodiment, the SAW propagation loss was evaluated by changing various dimensions of the resonator in which the auxiliary electrode 27 positioned on the crossing range R1 side toward the tip end side was provided on both sides of the dummy electrode. .
- FIG. 9A shows the change of the maximum phase ⁇ max when the angle ⁇ (FIG. 1B) with respect to the direction orthogonal to the SAW propagation direction of the auxiliary electrode 27 is changed.
- the horizontal axis represents the angle ⁇ (deg.)
- the vertical axis represents the maximum phase ⁇ max (deg.).
- the angle ⁇ is based on the center line of the auxiliary electrode 27.
- a width w2 of the auxiliary electrode 27 (FIG. 1B): 0.5 ⁇ m
- Connection position of the auxiliary electrode 27 (distance d, FIG. 1B): 0.75 ⁇ m
- the angle ⁇ is a little larger than 90 °, the benefit of suppressing propagation loss can be obtained.
- a significant difference (effect) is confirmed when the angle ⁇ is 60 ° compared to when the angle ⁇ is 90 °.
- the distance s2 (FIG. 1 (b)) between the auxiliary electrode 27 and the electrode finger 23, which should have different potentials, may be short-circuited.
- the distance s2 between the auxiliary electrode 27 and the electrode finger 23 that should have different potentials is expressed by, for example, s1 ⁇ sin ⁇ , assuming that the edge 27a of the auxiliary electrode 27 coincides with the tip edge of the dummy electrode 25. Assuming that s1 is about 0.2 ⁇ , since s2 is about 0.1 ⁇ , it is unlikely that a short circuit will occur, so sin ⁇ may be 0.5 or more. That is, ⁇ may be 30 ° or more.
- the angle ⁇ is preferably not less than 30 ° and not more than 60 °, and assuming that the conditions such as s1, d, w2, etc. change, more preferably, the angle ⁇ is about 45 ° near the center. is there.
- FIG. 9B shows a change in the maximum phase ⁇ max when the width w2 of the auxiliary electrode 27 is changed.
- the horizontal axis indicates the width w2 ( ⁇ m), and the vertical axis indicates the maximum phase ⁇ max (deg.).
- the width w2 is preferably 0.25 ⁇ to 0.5 ⁇ , and in another aspect, 0.50 ⁇ m to 1 ⁇ m.
- FIG. 9C shows the change of the maximum phase ⁇ max when the connection position (distance d) of the auxiliary electrode 27 is changed.
- the horizontal axis represents the distance d ( ⁇ m), and the vertical axis represents the maximum phase ⁇ max (deg.).
- the preferable range of the distance d is 0.25 ⁇ or more and 0.38 ⁇ or less, and in another aspect, 0.50 ⁇ m or more and 0.75 ⁇ m or less.
- the present invention is not limited to the above embodiment, and may be implemented in various modes.
- the acoustic wave element is not limited to a SAW element (in the narrow sense).
- it may be a so-called boundary acoustic wave element (however, included in a broad sense SAW element) in which the thickness of the protective layer (11) is relatively large (for example, 0.5 ⁇ to 2 ⁇ ).
- the boundary acoustic wave element it is not necessary to form the vibration space (33a), and thus the cover 33 and the like are also unnecessary.
- the acoustic wave element is not limited to a wafer level package.
- the SAW element does not have the cover 33 and the terminal 35, and the pad 39 on the upper surface 3 a of the substrate 3 and the mounting pad 55 of the circuit board 53 may be directly bonded by the solder 57.
- a vibration space may be formed by a gap between the SAW element 1 (protective layer 11) and the mounting surface 53a of the circuit board 53.
- the acoustic wave element of the wafer level package may have various configurations such that the terminals 39 are not provided and the pads 39 are in contact with the solder balls arranged on the mounting pads 55.
- the IDT electrode is not limited to an apodized electrode whose crossing width changes in the propagation direction of the elastic wave, and may have a constant crossing width. Even in this case, it is possible to suppress the propagation loss due to the SAW diverging at the interval s1.
- the first electrode fingers and the second electrode fingers may not be alternately arranged over the entire propagation direction of the elastic wave, and in some cases, the first electrode fingers or the second electrode fingers are elastic waves. They may be adjacent to each other with a half wavelength.
- the shape of the auxiliary electrode is not limited to that illustrated in the embodiment and the modification.
- the edge portion (27a) on the crossing range (R1) side is located closer to the crossing range side toward the tip side
- the auxiliary electrode 427 has an edge 427a on the crossing range side (first electrode finger 23A side) positioned on the crossing range side toward the tip side, but on the opposite side.
- the side edge 427b may be parallel to the SAW propagation direction.
- the edge part (427b etc.) on the opposite side to the intersection range may be located on the opposite side of the intersection range toward the tip side.
- the edge (427a or the like) on the crossing range side and the edge (427b or the like) on the opposite side may not be parallel to each other. That is, the distance between the edges may be longer toward the tip side, the distance from each other may be shorter toward the tip side, and the distance from each other may be longer or shorter at both the root and the tip. May be.
- the tips of the electrode fingers 23 and the like are formed in a rectangular shape having corners, but the corners may be rounded.
- the corner of the tip of the electrode finger 523 may be rounded (beveled by a curve).
- the entire edge of the tip of the electrode finger 523 has a projecting curved shape (example in FIG. 10B).
- the corners intersecting with the edges may also be rounded.
- the edge portion 527a extends in a concave shape with the electrode finger 523 side being concave.
- the edge portion 527a of the auxiliary electrode 527 and the entire tip edge portion of the dummy electrode 525 are curved with the tip side of the electrode finger 523 being concave.
- the shape including the curve as shown in FIG. 10B may be formed with a pattern including a curve in the photomask with the intention of forming the curve from the beginning, or a combination of straight lines in the photomask.
- a pattern (including a corner) made of the above may be formed, and the corner may be rounded or a straight line near the corner may be curved by adjusting the etching conditions.
- the position of the leading edge of the dummy electrode and the edge of the auxiliary electrode protruding from the dummy electrode on the crossing range side may not coincide with each other in the direction orthogonal to the SAW propagation direction.
- the edge portion 27 a of the auxiliary electrode 27 may be shifted to the root side of the dummy electrode 25 with respect to the tip edge portion of the dummy electrode 25.
- the tip of the dummy electrode 25 may protrude from the edge 27 a of the auxiliary electrode 27.
- the edge 27a of the auxiliary electrode 27 closes at least a part of the gap s1 when viewed in the SAW propagation direction. The same effect as the embodiment is achieved.
- Embodiments and modifications may be combined as appropriate.
- the modification examples shown in FIGS. 5B and 5D may be mixed in one IDT electrode, and the chamfering shown in FIG.
- the present invention may be applied to the modification shown in FIG.
- the protective layer 11 and the additional film 9 are not essential requirements, and the protective layer is provided only for the purpose of preventing corrosion and may be thinner than the thickness of the electrode finger.
- the upper surface of the protective layer 11 may have irregularities so as to be convex at the position of the electrode fingers. In this case, the reflection coefficient at the electrode fingers and their non-arranged positions can be increased. As described with reference to FIG. 3 (e), the unevenness may be formed due to the thickness of the electrode finger when the protective layer is formed, or the surface of the protective layer may be formed on the electrode finger. It may be formed by etching in the region between.
- the additional film is preferably provided over the entire surface of the electrode.
- the additional film may be provided only on a part of the electrode, such as provided only on the electrode finger. Further, the additional film may be provided only in a part on the center side when viewed in the longitudinal direction of the electrode finger. Further, the additional film may be provided not only on the upper surface of the electrode but also on the side surface.
- the material of the additional film may be a conductive material or an insulating material. Specifically, conductive materials such as tungsten (W), iridium (Ir), tantalum (Ta), copper (Cu), Ba x Sr 1-x O 3 , Pb x Zn 1-x O 3 , ZnO 3, etc. These insulating materials can be mentioned as materials for the additional film.
- the additional film By forming the additional film with an insulating material, it is possible to suppress the corrosion of the electrode and stabilize the electrical characteristics of the acoustic wave device, compared to the case where the additional film is formed of a metal material. This is because a pinhole may be formed in the protective layer made of SiO 2 , and when this pinhole is formed, moisture will penetrate to the electrode portion through this, but the electrode is placed on the electrode. This is because if a metal film made of a material different from the material is disposed, corrosion due to the battery effect between different metals occurs due to the infiltrated moisture. Therefore, if the additional film is formed of an insulating material such as Ta 2 O 5 , the battery effect is hardly generated between the electrode and the additional film. Therefore, a highly reliable acoustic wave element in which corrosion of the electrode is suppressed is obtained. be able to.
- the material of the electrode is not limited to Al and alloys containing Al as a main component.
- the material of the protective layer is not limited to SiO 2, and may be silicon oxide other than SiO 2 , for example.
- SAW element elastic wave element
- Substrate piezoelectric substrate
- IDT electrode electrode
- Additional film 11 ... Protective layer
- 21 21 ... Busbar
- Electrode finger 25 ... Dummy electrode, 27 ... Auxiliary electrode, 51 ... SAW device (surface acoustic wave device), 53 ... Circuit board
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
図1(a)は本発明の実施形態に係るSAW素子1の要部の平面図である。図1(b)は図1(a)の領域Ibの拡大図である。図2は図1(b)のII-II線における断面図である。
図4は、上述したSAW素子1を適用したSAW装置51の例を示す断面図である。
図5(a)~図5(d)は、補助電極の平面形状の変形例を示す図1(b)に対応する図である。なお、これらの図においては、第2バスバー21B側の第2補助電極27B、127B、および227Bの形状が示されているが、第1バスバー21A側の第1補助電極の形状も、第2補助電極の形状と同様である。
補助電極の形状および寸法を種々設定して、SAW素子1を作製した。そして、その電気特性を調べてSAWの伝搬損失を評価した。
以下の比較例および実施例において、共通する条件は以下のとおりである。
SAWの波長λ:2μm
交差幅Wの最大値:30λ
電極指の数:300本(150対)
ダミー電極の数:300本
図7(a)および図7(b)は、SAWの伝搬損失の評価方法を説明する図である。
補助電極の形状を互いに異ならせた比較例1~3(C1~C3)および実施例1~3(E1~E3)を設定し、SAWの伝搬損失の評価を行った。なお、実施1~3において、補助電極27はすべてのダミー電極に対して設けた。
実施形態と同様に、先端側ほど交差範囲R1側に位置する補助電極27がダミー電極の側方両側に設けられた共振子について、各種寸法を変化させて、SAWの伝搬損失の評価を行った。
補助電極27の幅w2(図1(b)):0.5μm
補助電極27の接続位置(距離d、図1(b)):0.75μm
補助電極27の角度α:45°
補助電極27の接続位置(距離d):0.75μm
補助電極27の角度α:45°
補助電極27の幅w2:0.5μm
Claims (10)
- 圧電基板と、
該圧電基板の上面に位置するIDT電極と、
を備え、
該IDT電極は、
弾性波の伝搬方向に直交する方向において互いに対向する第1バスバーおよび第2バスバーと、
前記第1バスバーから前記第2バスバーに向かって延び、前記伝搬方向に配列された複数の第1電極指と、
前記第2バスバーから前記第1バスバーに向かって延び、前記伝搬方向に配列された、前記複数の第1電極指と互いに交差する複数の第2電極指と、
前記第1バスバーから前記第2バスバーに向かって延び、前記伝搬方向に配列された、先端が前記複数の第2電極指の先端と間隙を介して対向する複数の第1ダミー電極と、
前記第2バスバーから前記第1バスバーに向かって延び、前記伝搬方向に配列された、先端が前記複数の第1電極指の先端と間隙を介して対向する複数の第2ダミー電極と、
前記複数の第1ダミー電極の先端側部分からその側方へ突出する複数の第1補助電極と、
前記複数の第2ダミー電極の先端側部分からその側方へ突出する複数の第2補助電極と、
を有し、
前記複数の第1補助電極の少なくとも一部の第1補助電極は、前記第2バスバー側の縁部が先端側ほど前記第2バスバー側に位置し、
前記複数の第2補助電極の少なくとも一部の第2補助電極は、前記第1バスバー側の縁部が先端側ほど前記第1バスバー側に位置する
弾性波素子。 - 前記IDT電極は、前記複数の第1電極指と前記複数の第2電極指との交差幅が前記伝搬方向において変化するアポダイズ電極である
請求項1に記載の弾性波素子。 - 前記複数の第1ダミー電極の少なくとも一部の第1ダミー電極は、両隣に前記第1電極指が位置し、先端側部分からその側方両側に1対の前記第1補助電極が突出し、
該1対の第1補助電極は、いずれも前記第2バスバー側の縁部が先端側ほど前記第2バスバー側に位置し、
前記複数の第2ダミー電極の少なくとも一部の第2ダミー電極は、両隣に前記第2電極指が位置し、先端側部分からその側方両側に1対の前記第2補助電極が突出し、
該1対の第2補助電極は、いずれも前記第1バスバー側の縁部が先端側ほど前記第1バスバー側に位置している
請求項1または2に記載の弾性波素子。 - 前記複数の第1ダミー電極の少なくとも一部の第1ダミー電極は、両隣に前記第1電極指が位置し、先端側部分からその側方両側に1対の前記第1補助電極が突出し、
該1対の第1補助電極は、いずれも前記第2バスバー側の縁部が前記伝搬方向に対して前記複数の第1ダミー電極の先端を結んだ線に沿う側に傾斜して延び、
前記複数の第2ダミー電極の少なくとも一部の第2ダミー電極は、両隣に前記第2電極指が位置し、先端側部分からその側方両側に1対の前記第2補助電極が突出し、
該1対の第2補助電極は、いずれも前記第1バスバー側の縁部が前記伝搬方向に対して前記複数の第2ダミー電極の先端を結んだ線に沿う側に傾斜して延びている
請求項2に記載の弾性波素子。 - 前記複数の第1補助電極は、先端が前記複数の第1電極指に接続されているとともに、前記複数の第1補助電極の第2バスバー側の縁部と前記第1ダミー電極の先端縁部とが交差する角部および前記複数の第1補助電極の第2バスバー側の縁部と該第1補助電極に隣接する第1電極指の縁部とが交差する角部は、それぞれ丸みを帯びるように面取りされており、
前記複数の第2補助電極は、先端が前記複数の第2電極指に接続されているとともに、
前記複数の第2補助電極の第1バスバー側の縁部と前記第2ダミー電極の先端縁部とが交差する角部および前記複数の第2補助電極の第1バスバー側の縁部と該第2補助電極に隣接する第2電極指の縁部とが交差する角部は、それぞれ丸みを帯びるように面取りされている
請求項3または4に記載の弾性波素子。 - 前記複数の第1補助電極は、先端が前記複数の第1電極指に接続され、
前記複数の第2補助電極は、先端が前記複数の第2電極指に接続されている
請求項1~4のいずれか1項に記載の弾性波素子。 - 前記IDT電極および前記圧電基板の上面を覆っている、前記圧電基板の上面からの厚みが前記IDT電極の厚みよりも大きいSiO2からなる保護層をさらに備え、
前記IDT電極は、Alを主成分とする材料からなる
請求項1~6のいずれか1項に記載の弾性波素子。 - 前記IDT電極の上面に位置し、前記保護層に覆われた、前記IDT電極の材料および前記保護層の材料に比較して音響インピーダンスが大きくかつ弾性波の伝搬速度が遅い材料を主成分とする付加膜をさらに備える
請求項7に記載の弾性波素子。 - 圧電基板と、
該圧電基板の上面に位置するIDT電極と、
を備え、
該IDT電極は、
弾性波の伝搬方向に直交する方向において互いに対向する第1バスバーおよび第2バスバーと、
前記第1バスバーから前記第2バスバーに向かって延び、前記伝搬方向に配列された複数の第1電極指と、
前記第2バスバーから前記第1バスバーに向かって延び、前記伝搬方向に配列された、前記複数の第1電極指と互いに交差する複数の第2電極指と、
前記第1バスバーから前記第2バスバーに向かって延び、前記伝搬方向に配列された、先端が前記複数の第2電極指の先端と間隙を介して対向する複数の第1ダミー電極と、
前記第2バスバーから前記第1バスバーに向かって延び、前記伝搬方向に配列された、先端が前記複数の第1電極指の先端と間隙を介して対向する複数の第2ダミー電極と、
前記複数の第1ダミー電極の先端側部分から前記伝搬方向に対して斜めに突出する第1補助電極と、
前記複数の第2ダミー電極の先端側部分から前記伝搬方向に対して斜めに突出する第2補助電極と、
を有する弾性波素子。 - 請求項1乃至9のいずれか1項に記載の弾性波素子と、
該弾性波素子が実装される回路基板と、
を備える弾性波装置。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/008,292 US9350320B2 (en) | 2011-03-28 | 2012-03-13 | Acoustic wave element and acoustic wave device using same |
CN201280009241.1A CN103384961B (zh) | 2011-03-28 | 2012-03-13 | 弹性波元件以及使用其的弹性波装置 |
JP2013507357A JP5833102B2 (ja) | 2011-03-28 | 2012-03-13 | 弾性波素子およびそれを用いた弾性波装置 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011-070063 | 2011-03-28 | ||
JP2011070063 | 2011-03-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012132877A1 true WO2012132877A1 (ja) | 2012-10-04 |
Family
ID=46930614
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2012/056408 WO2012132877A1 (ja) | 2011-03-28 | 2012-03-13 | 弾性波素子およびそれを用いた弾性波装置 |
Country Status (4)
Country | Link |
---|---|
US (1) | US9350320B2 (ja) |
JP (1) | JP5833102B2 (ja) |
CN (1) | CN103384961B (ja) |
WO (1) | WO2012132877A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015198897A1 (ja) * | 2014-06-23 | 2015-12-30 | 株式会社村田製作所 | 弾性波装置 |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106165294B (zh) * | 2014-05-07 | 2019-01-11 | 株式会社村田制作所 | 声表面波装置 |
JP6441590B2 (ja) * | 2014-05-23 | 2018-12-19 | 太陽誘電株式会社 | 弾性波デバイス |
JP5861809B1 (ja) * | 2014-05-26 | 2016-02-16 | 株式会社村田製作所 | 弾性波装置 |
CN104331205B (zh) * | 2014-11-25 | 2018-10-30 | 上海天马微电子有限公司 | 触控显示装置和电子设备 |
JP6365435B2 (ja) * | 2015-06-24 | 2018-08-01 | 株式会社村田製作所 | 弾性波装置 |
JP2018078419A (ja) * | 2016-11-08 | 2018-05-17 | 株式会社村田製作所 | 弾性波装置、高周波フロントエンド回路及び通信装置 |
DE102018102891A1 (de) * | 2017-02-13 | 2018-08-16 | Murata Manufacturing Co., Ltd. | Multiplexierer, Übertragungsvorrichtung und Empfangsvorrichtung |
JP7188402B2 (ja) * | 2020-01-31 | 2022-12-13 | 株式会社村田製作所 | 弾性波フィルタ |
US11621695B2 (en) | 2020-10-02 | 2023-04-04 | RF360 Europe GmbH | Cascaded surface acoustic wave devices with apodized interdigital transducers |
US20220311417A1 (en) * | 2021-03-29 | 2022-09-29 | Resonant Inc. | Transversely-excited film bulk acoustic resonators with busbar side edges that form angles with a perimeter of the cavity |
US20230133161A1 (en) * | 2021-10-29 | 2023-05-04 | Qorvo Us, Inc. | Surface acoustic wave (saw) structures with transverse mode suppression |
US20240097646A1 (en) * | 2022-09-21 | 2024-03-21 | RF360 Europe GmbH | Electroacoustic resonator |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04122114A (ja) * | 1990-09-13 | 1992-04-22 | Hitachi Ltd | 弾性表面波装置およびその作製方法およびそれを用いた通信装置 |
JPH0631222U (ja) * | 1992-09-25 | 1994-04-22 | 国際電気株式会社 | 弾性表面波共振子 |
JPH10224177A (ja) * | 1997-02-07 | 1998-08-21 | Seiko Epson Corp | 横多重モードフィルタ |
JP2004343259A (ja) * | 2003-05-13 | 2004-12-02 | Matsushita Electric Ind Co Ltd | 弾性表面波フィルタ |
JP2006186435A (ja) * | 2004-12-24 | 2006-07-13 | Kyocera Corp | 弾性表面波装置 |
JP2006246510A (ja) * | 2006-04-05 | 2006-09-14 | Murata Mfg Co Ltd | 表面波装置 |
JP2007096527A (ja) * | 2005-09-27 | 2007-04-12 | Epson Toyocom Corp | 弾性表面波デバイス |
WO2008035525A1 (fr) * | 2006-09-22 | 2008-03-27 | Murata Manufacturing Co., Ltd. | Dispositif de filtre d'ondes acoustiques de surface de type à résonateur à couplage longitudinal |
WO2008126614A1 (ja) * | 2007-03-27 | 2008-10-23 | Murata Manufacturing Co., Ltd. | 弾性波素子 |
JP2008306773A (ja) * | 2001-10-29 | 2008-12-18 | Panasonic Corp | 弾性表面波フィルタ素子 |
JP2009213174A (ja) * | 2009-06-22 | 2009-09-17 | Kyocera Corp | 弾性表面波装置、および実装構造体 |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4160963A (en) * | 1977-07-21 | 1979-07-10 | Texas Instruments Incorporated | Plural supply path acoustic surface wave device |
US7761705B2 (en) * | 2004-09-17 | 2010-07-20 | At&T Intellectual Property I, L.P. | Detection of encrypted packet streams |
EP1883259B1 (en) * | 2006-07-28 | 2009-09-30 | Research In Motion Limited | Apparatus and associated method for facilitating radio sub-system selection in a packet radio communication system |
JP4465625B2 (ja) | 2006-09-29 | 2010-05-19 | Tdk株式会社 | 弾性表面波フィルタおよび弾性表面波共振器 |
EP2202882A4 (en) * | 2007-10-18 | 2011-12-21 | Murata Manufacturing Co | ACOUSTIC SURFACE WAVE RESONATOR AND SCALE TYPE FILTER |
US7939987B1 (en) * | 2008-10-23 | 2011-05-10 | Triquint Semiconductor, Inc. | Acoustic wave device employing reflective elements for confining elastic energy |
US7939989B2 (en) * | 2009-09-22 | 2011-05-10 | Triquint Semiconductor, Inc. | Piston mode acoustic wave device and method providing a high coupling factor |
-
2012
- 2012-03-13 US US14/008,292 patent/US9350320B2/en active Active
- 2012-03-13 JP JP2013507357A patent/JP5833102B2/ja active Active
- 2012-03-13 WO PCT/JP2012/056408 patent/WO2012132877A1/ja active Application Filing
- 2012-03-13 CN CN201280009241.1A patent/CN103384961B/zh active Active
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04122114A (ja) * | 1990-09-13 | 1992-04-22 | Hitachi Ltd | 弾性表面波装置およびその作製方法およびそれを用いた通信装置 |
JPH0631222U (ja) * | 1992-09-25 | 1994-04-22 | 国際電気株式会社 | 弾性表面波共振子 |
JPH10224177A (ja) * | 1997-02-07 | 1998-08-21 | Seiko Epson Corp | 横多重モードフィルタ |
JP2008306773A (ja) * | 2001-10-29 | 2008-12-18 | Panasonic Corp | 弾性表面波フィルタ素子 |
JP2004343259A (ja) * | 2003-05-13 | 2004-12-02 | Matsushita Electric Ind Co Ltd | 弾性表面波フィルタ |
JP2006186435A (ja) * | 2004-12-24 | 2006-07-13 | Kyocera Corp | 弾性表面波装置 |
JP2007096527A (ja) * | 2005-09-27 | 2007-04-12 | Epson Toyocom Corp | 弾性表面波デバイス |
JP2006246510A (ja) * | 2006-04-05 | 2006-09-14 | Murata Mfg Co Ltd | 表面波装置 |
WO2008035525A1 (fr) * | 2006-09-22 | 2008-03-27 | Murata Manufacturing Co., Ltd. | Dispositif de filtre d'ondes acoustiques de surface de type à résonateur à couplage longitudinal |
WO2008126614A1 (ja) * | 2007-03-27 | 2008-10-23 | Murata Manufacturing Co., Ltd. | 弾性波素子 |
JP2009213174A (ja) * | 2009-06-22 | 2009-09-17 | Kyocera Corp | 弾性表面波装置、および実装構造体 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015198897A1 (ja) * | 2014-06-23 | 2015-12-30 | 株式会社村田製作所 | 弾性波装置 |
JPWO2015198897A1 (ja) * | 2014-06-23 | 2017-04-20 | 株式会社村田製作所 | 弾性波装置 |
US10454449B2 (en) | 2014-06-23 | 2019-10-22 | Murata Manufacturing Co., Ltd. | Elastic wave device |
Also Published As
Publication number | Publication date |
---|---|
US9350320B2 (en) | 2016-05-24 |
US20140015624A1 (en) | 2014-01-16 |
JPWO2012132877A1 (ja) | 2014-07-28 |
CN103384961A (zh) | 2013-11-06 |
JP5833102B2 (ja) | 2015-12-16 |
CN103384961B (zh) | 2016-05-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5833102B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP5931868B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP5562441B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP6747604B2 (ja) | 弾性波装置 | |
JP6352971B2 (ja) | 弾性波素子、フィルタ素子および通信装置 | |
KR102205855B1 (ko) | 탄성파 장치 | |
WO2012102131A1 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
WO2020116528A1 (ja) | 弾性波装置 | |
JP5815383B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP5083469B2 (ja) | 弾性表面波装置 | |
JP6756722B2 (ja) | 弾性波素子および弾性波装置 | |
JP5859355B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP6767497B2 (ja) | 弾性波素子 | |
JP5751887B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
JP5872196B2 (ja) | 弾性波素子およびそれを用いた弾性波装置 | |
WO2021002382A1 (ja) | 弾性波装置 | |
JP5882842B2 (ja) | 弾性表面波素子および弾性表面波装置 | |
WO2021177340A1 (ja) | 弾性波装置 | |
JP2008103953A (ja) | 弾性表面波素子片 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 12764480 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2013507357 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 14008292 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 12764480 Country of ref document: EP Kind code of ref document: A1 |