CN100495910C - Elastic surface-wave device - Google Patents
Elastic surface-wave device Download PDFInfo
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- CN100495910C CN100495910C CNB2003101044441A CN200310104444A CN100495910C CN 100495910 C CN100495910 C CN 100495910C CN B2003101044441 A CNB2003101044441 A CN B2003101044441A CN 200310104444 A CN200310104444 A CN 200310104444A CN 100495910 C CN100495910 C CN 100495910C
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- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 38
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 38
- 238000007747 plating Methods 0.000 claims description 76
- 239000010453 quartz Substances 0.000 claims description 40
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 40
- 239000004411 aluminium Substances 0.000 claims description 36
- 238000010897 surface acoustic wave method Methods 0.000 claims description 33
- 230000008878 coupling Effects 0.000 abstract description 28
- 238000010168 coupling process Methods 0.000 abstract description 28
- 238000005859 coupling reaction Methods 0.000 abstract description 28
- 229910052751 metal Inorganic materials 0.000 abstract description 8
- 239000002184 metal Substances 0.000 abstract description 8
- 239000011248 coating agent Substances 0.000 abstract 1
- 238000000576 coating method Methods 0.000 abstract 1
- 239000013078 crystal Substances 0.000 abstract 1
- 235000012431 wafers Nutrition 0.000 description 38
- 238000006073 displacement reaction Methods 0.000 description 8
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 6
- 150000002739 metals Chemical class 0.000 description 6
- 229910052715 tantalum Inorganic materials 0.000 description 6
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 6
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 6
- 229910052721 tungsten Inorganic materials 0.000 description 6
- 239000010937 tungsten Substances 0.000 description 6
- 239000010931 gold Substances 0.000 description 5
- 229910052737 gold Inorganic materials 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 238000003780 insertion Methods 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
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Abstract
Utilizing surface wave device in SH type with its electrode made from aluminum, which is difficult to induce deviation of frequency characteristic caused by deviation of film thick of electrode, the invention provides elastic surface wave device with large electromechanical coupling factor k2 and large reflection coefficient. An electrode constituted from aluminum is formed on crystal base plate with Eulerian angle being as 0 degree, 90-150 degree, 90 minus or plus 5 degree. Normalized film thick H/ lambda is in region 0.04-0.18. The electrode possesses fork finger electrode and reflector, and their metal coating ratio is in region 0.53-0.37.
Description
Technical field
The present invention relates to a kind of surface acoustic wave apparatus of the SH of utilization type list ground roll, in more detail, relate to a kind of surface acoustic wave apparatus that on quartz wafer, forms the electrode that constitutes by aluminium.
Background technology
All the time, be well known that to cut at ST on the quartz wafer that (cut) X carries and form electrode that constitutes by aluminium and the surface acoustic wave apparatus that utilizes surface wave.Yet in this surface acoustic wave apparatus, electromechanical coupling factor is little, and reflection coefficient is little, and then inserts the loss increase.Also have, used in formation under the situation of the SAW resonator of reflector or resonator type acoustic surface wave filter, owing to must use the more reflector of index electrode amount, so the miniaturization difficulty.
On the other hand, in following patent documentation 1, disclosed to cut on the quartz wafer that 90 ° of X carry and formed the electrode that constitutes by tantalum, tungsten or gold etc., and utilized the surface acoustic wave apparatus of SH type list ground roll at ST.Yet, owing to form electrode, diminish so can not get the centre frequency deviation that the deviation by electrode width or electrode thickness causes by bigger metals of quality such as tantalum, tungsten or gold.
In following patent documentation 2, disclosed to cut on the quartz wafer that 90 ° of X carry and formed the electrode that constitutes by aluminium, and utilized the surface acoustic wave apparatus of SH type list ground roll at ST., represented that the wavelength X with surface wave by making the electrode that is made of aluminium is 0.025～0.135 by standardized thickness (H/ λ) here, and reached the enlarger electric coupling coefficient and improve the aim of inserting the loss purpose.
(patent documentation 1)
The spy opens the 2000-323956 communique
(patent documentation 2)
The spy opens the 2002-330051 communique
(non-patent literature 1)
W.RICHARD SMITH and WILLIAM F.PEDLER " basic harmonic frequency Analysis of circuit model " IEEE Transaction onMicrowave Theory and Techniques with interdigital frequency converter of any plating and polarity sequence, Vol.MTT-23, No.11, in November, 1975.
Yet, in above-mentioned patent documentation 2 to the plating of interdigital electrode and reflector than not mentioning.
And, in this manual, so-called plating than refer to width that width that electrode refers to refers to respect to electrode and electrode refer between the ratio of summation in gap.
According to non-patent literature 1, know in interdigital electrode, plating than be under 0.5 the situation electromechanical coupling factor for maximum.Therefore, making the plating ratio of interdigital electrode mostly is 0.5.Yet,, can not obtain big reflection coefficient if making the plating ratio of interdigital electrode is 0.5.
Summary of the invention
The object of the present invention is to provide a kind of shortcoming of eliminating above-mentioned prior art, cut the electrode that 90 ° of X carry the aluminium that forms the less advantage of the frequency departure that caused by the thickness deviation with electrode on the quartz wafers to constitute at ST, and utilized the surface acoustic wave apparatus of SH type list ground roll, a kind of surface acoustic wave apparatus that can obtain big electromechanical coupling factor and big reflection coefficient is provided.
Surface acoustic wave apparatus of the present invention possesses: ST cuts that 90 ° of directions Xs are carried and Euler (Euler) angle is the quartz wafer of (0 °, 90 °～150 °, 90 ° ± 5 °); Be formed on the above-mentioned quartz wafer, and by the electrode of thickness H/ λ in 0.04～0.18 scope of the standard of wavelengthization of surface wave, this electrode is provided with to have the interdigital electrode that many electrodes refer to and has the reflector that many electrodes refer to, the plating of above-mentioned interdigital electrode and reflector is than in 0.53～0.87 scope.
In certain specific situation of surface acoustic wave apparatus of the present invention, the standardization thickness of above-mentioned interdigital electrode and reflector and plating ratio are in the scope of each combination shown in the table 3.
(table 3)
The Eulerian angles of quartz wafer (0 °, 90 °～150 °, 90 ° ± 5 °)
| Standardization thickness H/ λ | The scope of plating ratio |
| 0.04≦H/λ≦0.06 | 0.53～0.85 |
| 0.06<H/λ≦0.08 | 0.55～0.80 |
| 0.08<H/λ≦0.1 | 0.55～0.82 |
| 0.1<H/λ≦0.12 | 0.55～0.83 |
| 0.12<H/λ≦0.15 | 0.55～0.85 |
| 0.16<H/λ≦0.18 | 0.55～0.87 |
In the situation of the further qualification of surface acoustic wave apparatus of the present invention, the plating of above-mentioned interdigital electrode and reflector is than in 0.56～0.83 scope.
In surface acoustic wave apparatus of the present invention, more preferably, the standardization thickness of above-mentioned interdigital electrode and reflector and plating ratio are in the scope of each combination shown in the table 4.
(table 4)
| Standardization thickness H/ λ | The scope of plating ratio |
| 0.04≦H/λ≦0.06 | 0.56～0.80 |
| 0.06<H/λ≦0.1 | 0.57～0.82 |
| 0.1<H/λ≦0.15 | 0.58～0.82 |
| 0.15<H/λ≦0.18 | 0.58～0.83 |
Description of drawings
Fig. 1 is the schematic perspective view of the surface acoustic wave apparatus of one embodiment of the present invention.
Fig. 2 is the partial cutoff elevation cross-sectional view of surface acoustic wave apparatus shown in Figure 1.
Fig. 3 is the figure of relation that is illustrated in the displacement of the Eulerian angles θ that forms on the quartz wafer of Eulerian angles (0 °, θ, 90 °) under electrode and the feed surface ripple situation and various surface waves.
Fig. 4 is the figure of the relation of the ST that is illustrated in Eulerian angles (0 °, 127 °, the 90 °) velocity of sound of cutting the standardization thickness H/ λ of the electrode under the situation that forms the electrode that is made of various metals on the quartz wafer and surface wave.
Fig. 5 is the figure of the relation of the ST that is illustrated in Eulerian angles (0 °, 127 °, the 90 °) electromechanical coupling factor of cutting the standardization thickness H/ λ of the electrode under the situation that forms the electrode that is made of various metals on the quartz wafer and surface wave.
Fig. 6 is the figure that the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) cuts the relation of the reflection coefficient that the standardization thickness H/ λ that forms the reflector under the situation that causes the different reflector of thickness because of various metals are different on the quartz wafer and every electrode refer to.
Fig. 7 is that the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) cuts on the quartz wafer plating under the situation of the reflector that constitutes than the aluminium that forms by all thickness with various platings than the figure of the relation of the reflection coefficient that refers to every electrode.
Fig. 8 be the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) cut on the quartz wafer under the situation of the interdigital electrode that constitutes than the aluminium that forms by all thickness with various platings plating than and the figure of the relation of velocity of sound.
Among the figure: 1-Surface Wave Device, 2-quartz wafer, 3,4-interdigital electrode, 5,6-reflector.
Embodiment
Below, by the specific embodiment of reference description of drawings surface acoustic wave apparatus of the present invention, clear and definite the present invention.
Fig. 1 is the schematic perspective view of the surface acoustic wave apparatus of one embodiment of the invention, and Fig. 2 is schematic partial cutoff elevation cross-sectional view.
Surface acoustic wave apparatus 1 has ST and cuts quartz wafer 2.Quartz wafer 2 is that ST cuts that 90 ° of X carry and Eulerian angles are the quartz wafer of (0 °, 90 °～150 °, 90 ° ± 5 °).On quartz wafer 2, be formed with IDT (interdigital electrode) 3,4 and reflector 5,6.IDT3,4 and reflector 5,6 constitute by aluminium, with the wavelength of surface wave by standardized thickness H/ λ in 0.04～0.18 scope, and the plating that electrode refers to is than in 0.53～0.87 scope.
In the surface acoustic wave apparatus 1 of present embodiment because IDT3,4 and reflector 5,6 constitute by aluminium, compare with the situation of using big quality electrode materials such as tantalum, tungsten, gold, can reduce the frequency departure that the thickness deviation by electrode is caused.In addition, since the standardization thickness H/ λ that makes electrode in above-mentioned specific scope, so can obtain big electromechanical coupling factor k
2Therefore, can realize improvement broadband and the insertion loss.
In addition, owing to make plating than in the scope of above-mentioned particular range,, can reduce the radical that the electrode of reflector 5,6 refers to so can obtain big reflection coefficient.
Have again, than being under the situation of 0.56～0.83 scope, can reduce the thickness correlation that velocity of sound changes, can reduce the frequency departure of the Surface Wave Device that the standardization thickness by electrode causes according to these at the plating that makes electrode.
Below, according to specific embodiment, illustrate surface acoustic wave apparatus 1 and have above-mentioned action effect.
Fig. 3 is the figure that the ST that is illustrated in Eulerian angles (0 °, θ, 90 °) cuts the relation of the displacement of the surface wave of carrying on the quartz wafer and Eulerian angles θ.U1 among Fig. 3 represents the displacement of the direction parallel with the direction of advance of elastic surface wave, U2 represents the displacement of vertical with the direction of advance of elastic surface wave and parallel with substrate surface direction, and U3 represents the displacement of vertical with the direction of advance of elastic surface wave and vertical with substrate surface direction (depth direction of substrate).Therefore, U1 is equivalent to compressional wave (P ripple), and U2 is equivalent to the SH ripple, and U3 is equivalent to the SV ripple.
Value when the longitudinal axis of Fig. 3 represents that maximum with displacement is as 1.0 and with each displacement standardization.
Can understand that from Fig. 3 the θ in (0 °, θ, 90 °) is the quartz wafer by using 90 °～150 °, the displacement composition of the surface wave of conveying is nearly all obtained for the SH ripple.Therefore, in the present embodiment, cut quartz wafer as ST, wish using Eulerian angles is the quartz wafer of (0 °, 90 °～150 °, 90 °).In addition, not necessarily 90 ° of the ψ of Eulerian angles if 90 ° ± 5 ° scope is identical with situation shown in Figure 3, also can make the SH ripple successfully carry.Therefore, in the above-described embodiment, can use Eulerian angles is the quartz wafer of (0 °, 90 °～150 °, 90 ° ± 5 °).
Fig. 4 is illustrated in ST to cut on the quartz wafer, with the edge direction vertical with directions X is that Eulerian angles are (0 °, 127 °, 90 °) direction carry the mode of a kind of LSAW (leakage elastic surface wave) that belongs to the SH ripple to form the figure of the relation of the standardization thickness H/ λ of the electrode under the situation of the electrode that constitutes by various metals and surperficial wave propagation velocity.
Fig. 5 is illustrated on the quartz wafer identical with the situation of Fig. 4, is identically formed the figure of the relation of the standardization thickness H/ λ of the electrode under the situation of the electrode that is made of various metals and electromechanical coupling factor with the situation of Fig. 4,
Know that from Fig. 4 and Fig. 5 obtain in the field of big electromechanical coupling factor, velocity of sound is big with respect to the thickness correlation of the standardization thickness H/ λ of electrode when the metal tantalum big by quality, tungsten or gold form electrode.Relative therewith, constituting by aluminium under the situation of electrode, can reduce the thickness correlation of velocity of sound, reduce the velocity of sound deviation that the standardization thickness H/ λ of electrode is caused.In addition, know, forming by aluminium under the situation of electrode that standardization thickness H/ λ promptly in the scope of more sufficient thickness of electrode, can obtain big electromechanical coupling factor k in 0.025～0.135 scope from Fig. 5
2
ST cuts on the quartz wafer that X carries { be expressed as (0 °, ST, 0 °) with Eulerian angles, 0 ° of meaning of the latter is that X carries } and utilizes under the situation of R wave electromechanical coupling factor k
2Be 0.0013.Relative therewith, in the SH of Fig. 5 ripple, when forming electrode by aluminium, standardization thickness H/ λ in 0.013～0.20 scope, electromechanical coupling factor k
2Bigger than 0.0013.Therefore, if make the standardization thickness H/ λ of the electrode that constitutes by aluminium in 0.013～0.20 scope, then in the Surface Wave Device that has utilized SH type list ground roll, can obtain than using ST to cut electromechanical coupling factor k under quartz wafer that X carries and the situation of the utilizing R wave
2=0.0013 big electromechanical coupling factor.
In addition, the standardization thickness H/ of the electrode that is made of aluminium λ=0.06 o'clock, electromechanical coupling factor was 0.027, can approximately is the size of the twice of the electromechanical coupling factor when utilizing R wave.
, in surface acoustic wave apparatus, electromechanical coupling factor is greatly important.As mentioned above, electromechanical coupling factor is big more, can reach more to enlarge bandwidth and reduce the purpose of inserting loss.Cut the quartz wafer that X carries and utilize in the surface acoustic wave apparatus of R wave at existing use ST, because electromechanical coupling factor k
2Be 0.0013, less, so passband is narrow.Therefore, in order to enlarge passband, necessary additional inductor L etc.
Relative therewith, in the surface acoustic wave apparatus of present embodiment, the standardization thickness H/ λ by the electrode selecting to be made of aluminium can obtain big electromechanical coupling factor k
2, can reach the purpose that enlarges bandwidth and reduce the insertion loss.Particularly, in surface acoustic wave apparatus, wish electromechanical coupling factor k
2On the basis that enlarges bandwidth is more than 0.002, can reach the purpose of effective expansion bandwidth thus.Therefore, according to Fig. 5, in order to make electromechanical coupling factor k
2Be more than 0.002, the standardization thickness H/ λ that can make the electrode that is made of aluminium is in 0.025～0.135 scope.
On the other hand, if the thickness of electrode is thin excessively, then produce STW (SURFACETRANSVERSE WAVE), this STW becomes parasitic situation at document IvanD.Acramov, Mei Suohai and Liu Wen " vertical mode of surface transverse wave two-port acoustic resonator ", Proceeding of 1996 IEEE INTERNATIONAL FREQUENCYCONTROL SYMPOSIUM, 1996, Vol.1 sets forth among the pp.252-260.In the document, having recorded and narrated being formed with on the quartz wafer by H/ λ is that STW is energized under the situation of the electrode that constitutes of the aluminium of 0.00105～0.0325 thickness.And, be called as SSBW along the SH bulk wave of piezoelectric substrate surface transport, particularly will groove that the SSBW that carries on the quartz wafer is being provided with on the substrate surface or with on be collected be called STW.
Yet present inventor one experimentizes, and just confirms that the standardization thickness H/ λ of the electrode that is made of aluminium is more than 0.04, and STW can not be energized.
Therefore, in the present embodiment, in order to obtain big electromechanical coupling factor k
2The time, suppress to become the excitation of parasitic STW, the standardization thickness H/ λ that makes electrode 0.04 or above scope in.From with electromechanical coupling factor k
2The situation map of seeing 5 is known, wishes that the standardization thickness H/ λ of electrode is bigger than 0.05.
Fig. 6 is the figure of the relation of the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) the standardization thickness H/ λ that cuts reflection coefficient that every electrode forming the reflector under the situation with grating type reflector that many electrodes refer on the quartz wafer refers to and reflector.The result of the reflector that expression is made of tantalum, tungsten, gold and aluminium in Fig. 6.And, the reflection coefficient absolute value representation.
Know from Fig. 6, compare with the situation of using tantalum, tungsten or gold, under the situation of using aluminium, identical thickness but reflection coefficient is little.Yet, constituting by aluminium under the situation of reflector, if standardization thickness thickening reflection coefficient increases.In addition, standardization thickness H/ λ=0.02 o'clock, SH wave reflection coefficient was 0.018, and the reflection coefficient of R wave is 0.012.Therefore, to utilize the reflection coefficient under the SH ripple situation approximately be 1.5 times the value of utilizing under the R wave situation for the thickness H/ λ of the reflector that is made of aluminium=0.02 o'clock.
Using ST to cut quartz wafer and utilizing in the elastic surface wave resonator or resonator type acoustic surface wave filter of R wave, because reflection coefficient is little, so need the IDT both sides that 300 reflectors that refer to top electrode are arranged.Relative therewith, in the surface acoustic wave apparatus 1 that constitutes according to above-mentioned execution mode, utilize the surface wave of SH type, and the reflection coefficient under thickness H/ λ=0.062 situation of the electrode that is made of aluminium is about 3 times of the reflection coefficient with 300 reflectors that refer to top electrode that utilizes under the R wave situation.Therefore, the radical that refers to of the electrode of reflector 5,6 is just passable about 100.Thus, can reach the miniaturization largely of reflector.
Have again, under the situation of the surface wave that utilizes the SH type, the standardization thickness H/ λ of the electrode that constitutes by aluminium=0.097 o'clock, the above-mentioned reflection coefficient of reflector is about 3.3 times of reflection coefficient of the reflector with 300 Surface Wave Devices that refer to and utilize R wave with top electrode, and the radical that the electrode in the reflector refers to is just passable about 90.Therefore, further the miniaturization reflector can provide very small-sized surface resonator or resonator type surface wave filter.
Fig. 7 is that the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) cuts on the quartz wafer with various thickness and changes the figure of multiple plating than the variation that forms the reflection coefficient under the reflector situation that is made of aluminium.
Know that from Fig. 7 though according to the difference of thickness H/ λ, some differences are arranged, the standardization thickness H/ λ of aluminium is in 0.04～0.18 scope, the plating ratio is 0.65～0.7 o'clock reflection coefficient maximum.In general, as shown in non-patent literature 1, consider that making the plating ratio is 0.5, obtains big electromechanical coupling factor thus.Therefore, made the plating ratio of interdigital electrode or reflector is 0.5 in the past.
Yet, in having Surface Wave Devices such as the surface resonator of reflector, resonator type surface wave filter or step surface wave filter, wish the plating ratio, than Fig. 7 more near about 0.65～0.7.
In following table 5, the standardization thickness H/ λ of the electrode that expression is made of aluminium and the preferable range of the combination of plating ratio.In table 5, expression can obtain than plating than the scope of plating ratio that is 0.5 o'clock the big reflection coefficient more than 1.05 times of reflection coefficient.Therefore, the scope of plating ratio comprises that the plating that can obtain the maximum reflection coefficient compares and the value of front and back.
For example, if the standardization thickness H/ λ of aluminium electrode is under 0.08 the situation, be that 0.5 o'clock reflection coefficient is 0.25 relative with the plating ratio, the plating ratio be 0.55 and 0.82 o'clock reflection coefficient be 0.265.The plating ratio is that 0.65 o'clock reflection coefficient is 0.27.Therefore, plating is compared than the reflection coefficient that is 0.5 with plating than the reflection coefficient that is 0.55 and 0.82, is more than 1.05 times.The plating ratio be 0.65 o'clock be 1.08 times.In addition, reflection coefficient is big more, can reduce the radical that the electrode of reflector refers to more, can miniaturization.For example, the standardization thickness H/ λ of the electrode that is made of aluminium is that the radical that the electrode of the SH ripple under 0.097 the situation refers to can reduce to 90, also can reduce to 83.
(table 5)
The Eulerian angles of quartz wafer (0 °, 90 °～150 °, 90 ° ± 5 °)
| Standardization thickness (H/ λ) | The scope of plating ratio |
| 0.04≦H/λ≦0.06 | 0.53～0.85 |
| 0.06<H/λ≦0.08 | 0.55～0.80 |
| 0.08<H/λ≦0.1 | 0.55～0.82 |
| 0.1<H/λ≦0.12 | 0.55～0.83 |
| 0.12<H/λ≦0.15 | 0.55～0.85 |
| 0.16<H/λ≦0.18 | 0.55～0.87 |
Fig. 8 is that the ST that is illustrated in Eulerian angles (0 °, 127 °, 90 °) cuts on the quartz wafer figure that forms the variation of the velocity of sound under the situation of interdigital electrode of all thickness that is made of aluminium in the mode that becomes various plating ratios.
Know that from Fig. 8 the standardization thickness H/ λ of aluminium is in 0.04～0.18 scope, plating is than in 0.65～0.7 scope, and the deviation of velocity of sound is minimum.
As mentioned above, in existing surface acoustic wave apparatus,, be 0.5 so make the plating ratio owing to consider that the plating ratio of interdigital electrode is 0.5 o'clock electromechanical coupling factor maximum.Relative therewith, know that from Fig. 8 the plating ratio is at 0.5 o'clock, the variation of the velocity of sound that the thickness difference of the interdigital electrode that is made of aluminium causes is big.
Relative therewith, in following table 6, be illustrated in the scope of each electrode thickness, than plating than the velocity of sound deviation (variation) that is at 0.5 o'clock, the scope of the plating ratio that the deviation of velocity of sound reduces.That is, in table 6 expression with respect to plating than the velocity of sound deviation that is at 0.5 o'clock, the correlation of the plating of velocity of sound ratio is about the scope of the plating ratio below 1/4.Therefore, the scope of plating ratio comprises that the plating of the deviation minimum of velocity of sound compares and the value of front and back.
For example, if the standardization thickness H/ λ of aluminium electrode is under 0.08 the situation, to be median with plating than 0.5, the deviation that the plating ratio departs from the velocity of sound of (variation) ± 0.05 o'clock is ± 35m/s.On the other hand, be median with plating than 0.675, the deviation that the plating ratio departs from the velocity of sound of (variation) ± 0.05 o'clock is reduced to ± 3m/s.The correlation of the plating ratio of velocity of sound approximately is reduced to 1/12.Therefore, plating is compared than the situation that is 0.5 with plating than the situation that is 0.675, and the correlation of the plating ratio of velocity of sound approximately becomes 1/12 below 1/4.
That is, in the combination range of the thickness H/ of the electrode shown in the following table 6 λ and plating ratio, can significantly reduce the frequency departure of the surface acoustic wave apparatus that deviation caused of electrode thickness.
(table 6)
| Standardization thickness (H/ λ) | The scope of plating ratio |
| 0.04≦H/λ≦0.06 | 0.56～0.80 |
| 0.06<H/λ≦0.1 | 0.57～0.82 |
| 0.1<H/λ≦0.15 | 0.58～0.82 |
| 0.15<H/λ≦0.18 | 0.58～0.83 |
Know from the result of above-mentioned Fig. 3～Fig. 8, { Eulerian angles are (0 ° to cut 90 ° of X conveyings at ST, 90 °～150 °, 90 ° ± 5 °) } quartz wafer on form the electrode that constitutes by aluminium in the mode in standardization thickness H/ λ=0.04～0.18 scope, by the scope that makes the plating ratio is 0.53～0.87 scope, can obtain electromechanical coupling factor k
2And can obtain big reflection coefficient, and then can reduce the frequency departure that the electrode thickness deviation of surface acoustic wave apparatus causes.In addition, if make plating than the scope that is 0.56～0.83, the frequency departure that the thickness deviation of electrode can be caused is reduced to below 1/4 thus.
(invention effect)
In surface acoustic wave apparatus of the present invention, it is (0 ° in Eulerian angles, 90 °～150 °, 90 ° ± 5 °) quartz wafer on possess consisted of by aluminium and with the wavelength of surface wave by the electrode of standardized thickness H/ λ in 0.04～0.18 scope, this electrode has interdigital electrode and reflector, because the plating that makes interdigital electrode and reflector is than the scope that is 0.53～0.87, so the frequency departure minimizing that a kind of thickness deviation causes can be provided and have large electromechanical coupling factor and the surface acoustic wave apparatus of large reflectance factor. Therefore, in the surface acoustic wave apparatus of utilization with the SH type of reflector, can reach the purpose that enlarges bandwidth, reduces insertion loss and miniaturization.
Particularly, in the situation of plating ratio in the scope of each combination shown in the table 5, reflectance factor can be significantly improved, the miniaturization of more advancing one deck can be reached.
In addition, plating is than in the situation in 0.56～0.83 scope, can further reduce the deviation of the characteristic that the thickness of electrode causes.
Have again, in the situation of plating ratio in the scope of each combination shown in the table 6, can more effectively reduce the frequency departure that electrode thickness deviation causes.
Claims (2)
1. surface acoustic wave apparatus possesses: ST cuts that 90 ° of directions Xs are carried and Eulerian angles are the quartz wafer of (0 °, 90 °～150 °, 90 ° ± 5 °); With the electrode that is formed on the above-mentioned quartz wafer and is made of aluminium, this electrode has and has interdigital electrode that many electrodes refer to and referred to it is characterized in that the reflector that constitutes by many electrodes:
The standardization thickness H/ λ and the plating ratio of above-mentioned interdigital electrode and reflector, satisfy following relational expression:
When standardization thickness H/ λ was 0.04 ≦ H/ λ ≦ 0.06, the scope of plating ratio was 0.53～0.85;
When standardization thickness H/ λ was 0.06＜H/ λ ≦ 0.08, the scope of plating ratio was 0.55～0.80;
When standardization thickness H/ λ was 0.08＜H/ λ ≦ 0.1, the scope of plating ratio was 0.55～0.82;
When standardization thickness H/ λ was 0.1＜H/ λ ≦ 0.12, the scope of plating ratio was 0.55～0.83;
When standardization thickness H/ λ was 0.12＜H/ λ ≦ 0.15, the scope of plating ratio was 0.55～0.85;
When standardization thickness H/ λ was 0.16＜H/ λ ≦ 0.18, the scope of plating ratio was 0.55～0.87;
Wherein, standardization thickness H/ λ is by the standardized thickness of the wavelength X of surface wave.
2. surface acoustic wave apparatus according to claim 1 is characterized in that: the standardization thickness H/ λ and the plating ratio of above-mentioned interdigital electrode and reflector, satisfy following relational expression:
When standardization thickness H/ λ was 0.04 ≦ H/ λ ≦ 0.06, the scope of plating ratio was 0.56～0.80;
When standardization thickness H/ λ was 0.06＜H/ λ ≦ 0.1, the scope of plating ratio was 0.57～0.82;
When standardization thickness H/ λ was 0.1＜H/ λ ≦ 0.15, the scope of plating ratio was 0.58～0.82;
When standardization thickness H/ λ was 0.15＜H/ λ ≦ 0.18, the scope of plating ratio was 0.58～0.83.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101044441A CN100495910C (en) | 2003-10-29 | 2003-10-29 | Elastic surface-wave device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101044441A CN100495910C (en) | 2003-10-29 | 2003-10-29 | Elastic surface-wave device |
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| CN1612473A CN1612473A (en) | 2005-05-04 |
| CN100495910C true CN100495910C (en) | 2009-06-03 |
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| CNB2003101044441A Expired - Lifetime CN100495910C (en) | 2003-10-29 | 2003-10-29 | Elastic surface-wave device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP2099129A4 (en) * | 2006-12-27 | 2014-03-26 | Murata Manufacturing Co | Surface acoustic wave device |
| CN112655150B (en) * | 2018-09-07 | 2024-02-09 | 株式会社村田制作所 | Elastic wave device, high-frequency front-end circuit, and communication device |
| CN112217490B (en) * | 2020-10-22 | 2021-09-14 | 展讯通信（上海）有限公司 | Laminated temperature compensation type surface acoustic wave resonator and packaging method |
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