WO2005036744A1 - 弾性境界波装置 - Google Patents
弾性境界波装置 Download PDFInfo
- Publication number
- WO2005036744A1 WO2005036744A1 PCT/JP2004/012815 JP2004012815W WO2005036744A1 WO 2005036744 A1 WO2005036744 A1 WO 2005036744A1 JP 2004012815 W JP2004012815 W JP 2004012815W WO 2005036744 A1 WO2005036744 A1 WO 2005036744A1
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- WO
- WIPO (PCT)
- Prior art keywords
- acoustic wave
- boundary acoustic
- wave device
- boundary
- electrode
- Prior art date
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Classifications
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- 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
- H03H9/0222—Details of interface-acoustic, boundary, pseudo-acoustic or Stonely wave devices
Definitions
- the present invention relates to a boundary acoustic wave device using a boundary acoustic wave propagating along a boundary between first and second medium layers having different sound speeds, and more particularly, to a boundary acoustic wave device having an improved electrode structure.
- a boundary acoustic wave device using a boundary acoustic wave propagating along a boundary between first and second medium layers having different sound speeds, and more particularly, to a boundary acoustic wave device having an improved electrode structure.
- a surface acoustic wave device using a surface acoustic wave such as a Rayleigh wave or a first leaky wave can be reduced in size and weight and does not require adjustment.
- surface acoustic wave devices are widely used for RF filters or IF filters for mobile phones, resonators for VCOs, VIF filters for televisions, and the like.
- a boundary acoustic wave device has been proposed as a device that does not require a package having a cavity as described above.
- FIG. 5 is a schematic partial cutaway front sectional view showing an example of a conventional boundary acoustic wave device.
- first and second medium layers 102 and 103 having different sound velocities are stacked.
- An IDT 104 as an electroacoustic transducer is arranged at a boundary A between the first and second medium layers 102 and 103. Further, reflectors (not shown) are arranged on both sides of the IDT 104 in the direction of propagation of the boundary acoustic wave.
- boundary acoustic wave device 101 a boundary acoustic wave is excited by applying an input signal to the IDT 104.
- the boundary acoustic wave is represented by a boundary acoustic wave device as schematically shown by arrow B in Fig. 5. Propagate the boundary A of the location 101.
- Non-Patent Document 1 shows an example of such a boundary acoustic wave device.
- an IDT is formed on a 126 ° rotation Y-plate X-propagation LiTaO substrate, and a Si ⁇ film is formed to a predetermined thickness on the LiTaO substrate so as to cover the IDT.
- a Si ⁇ film is formed to a predetermined thickness on the LiTaO substrate so as to cover the IDT.
- Non-Patent Document 1 states that if the thickness of the SiO film is 1. ⁇ (where ⁇ is the wavelength of the boundary acoustic wave), an electromechanical coupling coefficient of 2% can be obtained.
- Patent Document 1 discloses a boundary acoustic wave device having a structure in which an IDT made of A1 is formed on a LiTaO substrate that propagates a 126 ° rotating plate X propagation.
- the thickness of the electrode finger of the interdigital electrode is H
- the width of the electrode finger is L
- the interval between the electrode fingers is S
- a polycrystalline silicon oxide film constituting the second medium is formed on the IDT.
- the duty ratio L / (L + S) of the interdigital electrode is set to 0.5.
- Patent document 1 W098-52279
- Non-Special Noon Document 1 “Piezoelectric Acoustic Boundary Waves Propagating Long the Interface Between Si ⁇ 2 and LiTa03j IEEE Trans. Sonics and ultrason., VOL. SU-25, No. 6, 1978 IEEE
- the boundary acoustic wave device is strongly required to have a small frequency variation.
- the conventional boundary acoustic wave device could not sufficiently satisfy this requirement, and it was difficult to increase the yield rate.
- An object of the present invention is to provide good resonance characteristics and filter characteristics in view of the state of the art.
- Another object of the present invention is to provide a boundary acoustic wave device having small frequency variations.
- the present invention provides an elastic boundary including a first medium layer, a second medium layer, and an interdigital electrode and / or a reflector disposed at a boundary between the first and second medium layers.
- a boundary acoustic wave device characterized in that when the duty ratio of the interdigital electrode and / or the reflector is d, 0.33 ⁇ d ⁇ 0.49.
- the first medium layer is formed of LiNb. It is configured using a substrate mainly composed of o.
- the second medium layer is formed of SiO 2
- the duty ratio d of the interdigital electrode and Z or the reflector is greater than 0.33 and less than 0.49. Therefore, as will be apparent from a specific experimental example described later, it is possible to reduce the frequency variation during manufacturing.
- the present invention is characterized in that in the boundary acoustic wave device, the duty ratio is set in the specific range described above, thereby reducing the frequency variation at the time of manufacturing.
- FIG. 1 is a schematic plan view showing an electrode structure of a boundary acoustic wave device according to one embodiment of the present invention.
- FIG. 2 is a surface cross-sectional view showing a main part of the boundary acoustic wave device shown in FIG. 1.
- FIG. 3 is a diagram showing a change in a manufacturing deviation ⁇ of a resonance frequency when a duty ratio of an interdigital electrode and a reflector of a boundary acoustic wave device is changed.
- FIG. 4 is a diagram showing a change in a manufacturing deviation ⁇ of an anti-resonance frequency when a duty ratio of an interdigital electrode and a reflector of a boundary acoustic wave device is changed.
- FIG. 5 is a schematic partial cutaway front sectional view for explaining a conventional boundary acoustic wave device.
- FIG. 1 is a schematic sectional view showing an electrode structure of a boundary acoustic wave device according to one embodiment of the present invention.
- a rectangular plate-shaped LiNbO substrate 2 is used as the first medium layer.
- the LiNbO substrate 2 uses a 15 ° rotating Y-plate X-propagation LiNbO substrate.
- a rotating Y-plate X-propagating LiNbO substrate having another rotation angle may be used.
- FIG. 1 the illustration of the SiO film is omitted, and the SiO film 3 and the L
- the electrode structure arranged at the boundary with the 222 iNbO substrate 2 is shown. That is, LiNbO group
- the interdigital electrode 4 has a plurality of mutually interleaved electrode fingers 4a and 4b.
- the interdigital electrode 4 is weighted so that the crossing width changes in the direction of propagation of the surface acoustic wave as shown in the figure.
- interdigital electrode 4 is weighted by the cross width as described above is to suppress the transverse mode spurious.
- grating reflectors 5 and 5 are provided on both sides of the interdigital electrode 4 in the surface wave propagation direction.
- the reflectors 5, 6 have a structure in which a plurality of electrode fingers 5a, 6a are short-circuited at both ends.
- the duty ratio of the interdigital electrode 4 and the reflectors 5 and 6 is set to be larger than 0.33 and smaller than 0.49, the frequency variation at the time of manufacturing can be reduced. .
- the interdigital electrode 4 and the reflectors 5 and 6 were formed by the following thin film forming method. That is, a 0.001 ⁇ thick NiCr film was formed on the LiNbO substrate 2 as a base layer by evaporation.
- ⁇ indicates the arrangement of surface waves defined by the electrode finger period of the interdigital electrode 4.
- An Au film having a thickness of 0.6 ⁇ was formed on the NiCr film by the same vapor deposition method. Thereafter, patterning was performed by a lift-off method, and interdigital electrodes 4 and reflectors 5 and 6 were formed.
- the wavelength ⁇ of the interdigital electrode 4 was 3 ⁇ m.
- the number of electrode fingers in the interdigital electrode 4 was 50 pairs, the number of electrode fingers in the reflector was 50, and the aperture length A in the reflector was 30 ⁇ .
- the SiO film 3 is
- a film was formed by the Ron sputtering method.
- the temperature for film formation should be in the range of 200 ⁇ 50 ° C.
- the thickness of the film was 1.5 ⁇ .
- the SH type boundary acoustic wave is excited and confined between the reflectors 5 and 6, and the resonance characteristics of the SH type boundary acoustic wave are obtained. Can be.
- boundary acoustic wave device 1 a plurality of types of boundary acoustic wave devices were manufactured by varying the duty ratio of the interdigital electrode 4.
- a plurality of types of boundary acoustic wave devices prepared in this manner were taken out of each forty devices, and the frequency production deviation ⁇ of the resonance frequency and the antiresonance frequency was evaluated.
- the deviation ⁇ is the standard deviation assuming that the frequency variation has a normal distribution.
- FIG. 3 shows the relationship between the frequency production deviation of the resonance frequency and the duty ratio obtained as described above
- FIG. 4 shows the relationship between the frequency production deviation of the anti-resonance frequency and the duty ratio.
- the manufacturing deviation of the resonance frequency is ⁇ 2530 ppm, whereas the duty ratio is 0.49.
- the manufacturing deviation ⁇ is smaller than 2330 ppm.
- the production deviation ⁇ is further reduced to 2050 ppm or less.
- the manufacturing deviation ⁇ of the anti-resonance frequency is 2580 ppm, whereas it is smaller than the duty ratio force SO.5 and larger than 0.31. It can be seen that the manufacturing deviation ⁇ of the anti-resonance frequency is smaller than 2410 ppm in the range. In addition, du It can be seen that when the tee ratio is smaller than 0.44 and larger than 0.33, the production deviation ⁇ of the anti-resonance frequency is further improved to 1970 ppm or less.
- the boundary acoustic wave device 1 by making the duty ratio of the electrode larger than 0.33 and smaller than 0.49, the manufacturing deviation of the frequency can be effectively reduced, and the boundary acoustic wave device can be used. It can be seen that the non-defective rate of the device 1 can be greatly increased.
- the manufacturing variation of the frequency at the lower end of the pass band is determined by the manufacturing deviation ⁇ of the resonance frequency of the boundary acoustic wave resonator.
- the manufacturing deviation of the frequency at the upper end of the pass band is determined by the manufacturing deviation ⁇ of the antiresonant frequency. Therefore, when the boundary acoustic wave device 1 is used as a resonator for forming a ladder-type finoletor or the like, it is possible to effectively reduce the frequency variation of the filter.
- the IDT electrode 4 and the reflector 5 are used.
- the boundary acoustic wave device when the thickness of the SiO film is sufficiently large, the irregularities on the surface of the SiO film 3 are reduced. Also, even if such irregularities occur, the boundary acoustic wave Vibration energy is hardly distributed on the surface of the Si ⁇ film, and therefore is hardly affected by the irregularities.
- the electrode material forming the interdigital electrodes and the reflectors 5 and 6 is configured by laminating an Au film on a base layer made of NiCr.
- the electrode material is not limited to those mainly composed of Au, and metals and alloys such as Ag, Cu, Al, Fe, Ni, W, Ta, Pt, Mo, Cr, Ti, Zn ⁇ and ITO.
- an oxide conductor may be used.
- the material forming the first medium layer is not limited to the LiNbO substrate 2 but may be formed of another piezoelectric substrate such as a LiTaO substrate, a quartz substrate, and a langasite-based substrate. Further, the first medium layer may be made of glass or the like.
- the second medium layer is not limited to the Si film, but may be another material such as an A1 film, a SiN film, or a polycrystalline Si film. It does not need to be formed into a thin film.
- the boundary portion formed by the first and second medium layers is not particularly limited as long as the medium is filled in the interdigital electrode 4 and the space between the electrode fingers of the reflectors 5 and 6. It is not done.
- the interdigital electrode 4 and the reflectors 5 and 6 are provided in the boundary acoustic wave device 1, but the number of interdigital electrodes and the number of reflectors are not particularly limited. That is, a longitudinally-coupled boundary acoustic wave filter in which a plurality of interdigital electrodes are arranged between a pair of reflectors may be configured. , May be arranged in parallel or in cascade.
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP2005514537A JPWO2005036744A1 (ja) | 2003-10-10 | 2004-09-03 | 弾性境界波装置 |
Applications Claiming Priority (2)
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JP2003-352226 | 2003-10-10 | ||
JP2003352226 | 2003-10-10 |
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WO2005036744A1 true WO2005036744A1 (ja) | 2005-04-21 |
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PCT/JP2004/012815 WO2005036744A1 (ja) | 2003-10-10 | 2004-09-03 | 弾性境界波装置 |
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Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006319887A (ja) * | 2005-05-16 | 2006-11-24 | Murata Mfg Co Ltd | 弾性境界波装置 |
WO2008038459A1 (fr) * | 2006-09-25 | 2008-04-03 | Murata Manufacturing Co., Ltd. | Filtre d'onde acoustique limite |
US7471171B2 (en) * | 2006-02-28 | 2008-12-30 | Fujitsu Media Devices Limited | Elastic boundary wave device, resonator, and filter |
JP2009535869A (ja) * | 2006-04-28 | 2009-10-01 | エプコス アクチエンゲゼルシャフト | 電気音響部品 |
US7898145B2 (en) | 2006-09-25 | 2011-03-01 | Murata Manufacturing Co., Ltd. | Boundary acoustic wave device |
WO2012019904A1 (de) | 2010-08-12 | 2012-02-16 | Epcos Ag | Mit akustischen wellen arbeitendes bauelement mit reduziertem temperaturgang der frequenzlage und verfahren zur herstellung |
CN1989692B (zh) * | 2005-05-20 | 2012-04-25 | 株式会社村田制作所 | 弹性边界波装置 |
JP2012175315A (ja) * | 2011-02-21 | 2012-09-10 | Murata Mfg Co Ltd | 弾性表面波フィルタ装置 |
US9394163B2 (en) | 2010-04-14 | 2016-07-19 | Epcos Ag | Method for producing a dielectric layer on a component |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS5643817A (en) * | 1979-09-17 | 1981-04-22 | Hitachi Ltd | Surface elastic wave device |
JPS5830216A (ja) * | 1981-08-17 | 1983-02-22 | Hitachi Ltd | 弾性波装置 |
JPS5830217A (ja) * | 1981-08-17 | 1983-02-22 | Hitachi Ltd | 弾性波装置 |
JPS5883420A (ja) * | 1981-11-13 | 1983-05-19 | Hitachi Ltd | 弾性境界波装置 |
JPH05335879A (ja) * | 1992-05-28 | 1993-12-17 | Fujitsu Ltd | 弾性表面波素子 |
JPH08321743A (ja) * | 1995-05-25 | 1996-12-03 | Sanyo Electric Co Ltd | 弾性表面波フィルタ |
-
2004
- 2004-09-03 JP JP2005514537A patent/JPWO2005036744A1/ja active Pending
- 2004-09-03 WO PCT/JP2004/012815 patent/WO2005036744A1/ja active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5643817A (en) * | 1979-09-17 | 1981-04-22 | Hitachi Ltd | Surface elastic wave device |
JPS5830216A (ja) * | 1981-08-17 | 1983-02-22 | Hitachi Ltd | 弾性波装置 |
JPS5830217A (ja) * | 1981-08-17 | 1983-02-22 | Hitachi Ltd | 弾性波装置 |
JPS5883420A (ja) * | 1981-11-13 | 1983-05-19 | Hitachi Ltd | 弾性境界波装置 |
JPH05335879A (ja) * | 1992-05-28 | 1993-12-17 | Fujitsu Ltd | 弾性表面波素子 |
JPH08321743A (ja) * | 1995-05-25 | 1996-12-03 | Sanyo Electric Co Ltd | 弾性表面波フィルタ |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006319887A (ja) * | 2005-05-16 | 2006-11-24 | Murata Mfg Co Ltd | 弾性境界波装置 |
CN1989692B (zh) * | 2005-05-20 | 2012-04-25 | 株式会社村田制作所 | 弹性边界波装置 |
US7471171B2 (en) * | 2006-02-28 | 2008-12-30 | Fujitsu Media Devices Limited | Elastic boundary wave device, resonator, and filter |
JP2009535869A (ja) * | 2006-04-28 | 2009-10-01 | エプコス アクチエンゲゼルシャフト | 電気音響部品 |
EP2068443A4 (en) * | 2006-09-25 | 2011-08-03 | Murata Manufacturing Co | ACOUSTIC WAVE FILTER LIMIT |
JPWO2008038459A1 (ja) * | 2006-09-25 | 2010-01-28 | 株式会社村田製作所 | 弾性境界波フィルタ装置 |
US7808344B2 (en) | 2006-09-25 | 2010-10-05 | Murata Manufacturing Co., Ltd. | Boundary acoustic wave filter |
US7898145B2 (en) | 2006-09-25 | 2011-03-01 | Murata Manufacturing Co., Ltd. | Boundary acoustic wave device |
EP2068443A1 (en) * | 2006-09-25 | 2009-06-10 | Murata Manufacturing Co. Ltd. | Boundary acoustic wave filter |
WO2008038459A1 (fr) * | 2006-09-25 | 2008-04-03 | Murata Manufacturing Co., Ltd. | Filtre d'onde acoustique limite |
JP4947055B2 (ja) * | 2006-09-25 | 2012-06-06 | 株式会社村田製作所 | 弾性境界波装置 |
US9394163B2 (en) | 2010-04-14 | 2016-07-19 | Epcos Ag | Method for producing a dielectric layer on a component |
WO2012019904A1 (de) | 2010-08-12 | 2012-02-16 | Epcos Ag | Mit akustischen wellen arbeitendes bauelement mit reduziertem temperaturgang der frequenzlage und verfahren zur herstellung |
DE102010034121A1 (de) | 2010-08-12 | 2012-02-16 | Epcos Ag | Mit akustischen Wellen arbeitendes Bauelement mit reduziertem Temperaturgang der Frequenzlage und Verfahren zur Herstellung |
US9160303B2 (en) | 2010-08-12 | 2015-10-13 | Epcos Ag | Component working with acoustic waves having reduced temperature coefficient of frequencies and method for producing same |
JP2012175315A (ja) * | 2011-02-21 | 2012-09-10 | Murata Mfg Co Ltd | 弾性表面波フィルタ装置 |
Also Published As
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JPWO2005036744A1 (ja) | 2007-11-22 |
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