CN1016032B

CN1016032B - Surface acoustic wave device

Info

Publication number: CN1016032B
Application number: CN 90102098
Authority: CN
Inventors: 家木英治; 樱井敦; 木村辛司
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 1989-04-14
Filing date: 1990-04-14
Publication date: 1992-03-25
Also published as: CN1046420A

Abstract

Interdigital transducers (3, 4) and reflectors (5, 6) are formed on a piezoelectric substrate (2) by an aluminum film. The aluminum film is crystallographically oriented in a constant direction, whereby stressmigration of the aluminum film is suppressed.

Description

Surface acoustic wave device

The present invention relates to surface acoustic wave apparatus, particularly on piezoelectric substrate, be formed with the surface acoustic wave apparatus of the electrode that makes by aluminium.

Widely used in recent years surface acoustic wave apparatus is for using the such surface acoustic wave apparatus of filter, harmonic oscillator of elastic surface wave (the following SAW that is called for short sometimes).

In these surface acoustic wave apparatus, generally has grid (grating) electrode that forms interdigital (interdigital) electrode and/or form on the surface of substrate of piezoelectricity by a plurality of bonding jumpers that are arranged in parallel.

The material that is used for piezoelectric substrate can be used crystal, lithium tantalate (LiTaO ₃), lithium niobate (LiNbO ₃), lithium tetraborate (Li ₂B ₄O ₇) such monocrystalline, or at sapphire (Al ₂O ₃) form the ZnO/Al of zinc oxide (ZnO) on the substrate ₂O ₃Deng.

Again, the metal that is used to form above-mentioned interdigital electrode and grid electrode generally uses aluminium.Why use aluminium to be in this wise because its photoetching is easy, its proportion is little so electrode load mass effect is little, and its conductance is high.

But recognize that then the effect owing to surface acoustic wave apparatus makes the aluminium electrode be subjected to strong stress, and moves as on the surface acoustic wave apparatus SAW filter or the SAW harmonic oscillator as add the signal of high-voltage level.This migration is referred to as stress migration (Stress migration) owing to be that stress causes in order to distinguish mutually with electromigration.As this phenomenon takes place, then can cause electric short circuit, insert the loss increase, the Q value reduction of harmonic oscillator etc.Again because stress migration is the high more easy more generation of frequency, so this becomes a big problem in the special surface acoustic wave apparatus that uses under high-frequency.

Particularly with regard to harmonic oscillator, in order with it stable vibration to take place, the just essential gain that improves oscillating circuit is with the signal that adds that voltage level is very high.Surface wave is closed between the reflector in the harmonic oscillator of the both sides of transducer configuration reflector again, is added with standing wave on transducer and reflector, therefore is added with strong stress on these.According to the occasion of such reason, then be in the situation that stress migration takes place especially easily in harmonic oscillator.Thereby in existing SAW harmonic oscillator, have no alternative but to make it under low voltage level, to work, thereby C/N is improved than (carrier-to-noise ratio) or the SSB phase noise is lowered for the phenomenon that suppress to produce stress migration as far as possible.

Again, as with regard to the SAW filter, particularly in the filter of usefulness of posting a letter owing to will add the signal of high-voltage level, so be easy to cause stress migration.

The countermeasure that prevents stress migration as described above is to add Cu, the Ti of trace, Ni, Mg, Pd etc. in the aluminium of electrode material, but effect is still undesirable.

Again, recently attractive as the substrate of temperature characterisitic better elastic Surface Wave Device is that about 105 ° of rotary Y cuttings cut (LST cutting) crystal substrate.The surface acoustic wave apparatus that uses such LST sliced crystal substrate is to leak the device that elastic surface wave (LSAW) is propagated along the surface of its substrate, it is characterized in that having the better temperature characterisitic of surface acoustic wave apparatus than with ST sliced crystal substrate.

But, in the occasion of using ST sliced crystal substrate, the thickness that is order aluminium electrode be elastic surface wave wavelength about 2%, there is not special generation problem yet, in contrast, known the occasion people that use LST sliced crystal plate as making the thickness of aluminium electrode be higher than 1% of wavelength, then for example can cause that the Q value sharply reduces in the harmonic oscillator, and characteristic degradation.In the occasion that makes the reduced thickness of the aluminium electrode on the LST sliced crystal substrate for fear of such characteristic degradation, crystal particle volume owing to the aluminium that forms electrode in existing polycrystalline aluminium is big, so apparent electrical resistance rate becomes big, cause that therefore the insertion loss increases or the Q value reduces.Particularly such shortcoming is very remarkable in the high frequency field that wavelength can shorten.

Therefore inventor of the present invention mentions the reason of above-mentioned stress migration once more.Consequently for recognizing that the aluminium that will become the electrode that forms by electron beam evaporation plating or sputter etc. be not oriented in certain orientation aspect the crystallography, but be in amorphous many crystalline states.Therefore can think and in such aluminium electrode, be easy to take place the stress migration that causes by the crystal boundary diffusion.

So the object of the present invention is to provide the surface acoustic wave apparatus that possesses the aluminium electrode that is difficult to take place stress migration.

The present invention be directed to and possess piezoelectric substrate and on piezoelectric substrate, form and the invention of the surface acoustic wave apparatus of the electrode of configuration example such as transducer, it is characterized in that electrode contains the aluminium film that is oriented in certain orientation on crystal orientation.

Like this, can think that the aluminium film that makes crystal axis be oriented in certain orientation shows the character close with single crystal film.Thereby such aluminium film is difficult to cause stress migration.Thereby, can prevent the stress migration and electric short circuit that causes and the increase of inserting loss according to this invention.Be applicable to the occasion of harmonic oscillator again in the present invention, can prevent stress migration and make its Q value reduction.Thereby can make the life-span of surface acoustic wave apparatus elongated by the generation that suppresses stress migration.

Again, in general, the stress migration frequency of generation is high more to be remarkable more.But according to the present invention owing to can suppress the generation of such stress migration, so can keep the high frequency characteristics of surface acoustic wave apparatus well.

According to the present invention, when adding the signal of high-voltage level, also can suppress the generation of stress migration again.Even thereby in the high circuit of signal level, in practicality, also can use according to surface acoustic wave apparatus of the present invention.Thereby be applicable to elastic wave resonant's period of the day from 11 p.m. to 1 a.m owing to can add the signal of high-voltage level without any problem ground in the present invention, so can make C/N than increase and the attenuating of SSB phase noise.Again owing to can under gain big and over excited state, using harmonic oscillator, so harmonic oscillator is stably vibrated.Even again the present invention add high voltage signal post a letter with filter in also can be suitable for well.

As piezoelectric substrate to use crystal substrate, lithium tantalate LiTaO ₃Substrate, lithium niobate LiNbO ₃Substrate, lithium tetraborate Li ₂B ₄O ₇The monocrystal substrate that substrate is such, or be used in sapphire (Al ₂O ₃) on the substrate epitaxial growth ZnO/Al of ZnO film is arranged ₂O ₃Substrate is better.

Better to use rotary Y cutting to cut crystal substrate in the occasion of using crystal substrate as piezoelectric substrate, using the occasion of crystal substrate like this as piezoelectric substrate, the aluminium film can be (311) alignment films.

With the occasion of cutting crystal substrate with rotary Y cutting preferably embodiment can in 25 °-39 ° scope, choose the anglec of rotation that rotary Y cutting cuts crystal.

Another preferably embodiment can in 103 °-107 ° scope, select to be used for the anglec of rotation that the rotary Y cutting of substrate cuts crystal.Therefore can provide and leak the surface acoustic wave apparatus that elastic surface wave is propagated on substrate.The aluminium film that this moment, crystallographic axis pointed to certain orientation shows the character near single crystal film owing to be not the set of crystal grain, so even when its very thin thickness, also can keep electric on conducting good.Thereby use the surface acoustic wave apparatus of LST sliced crystal substrate might bring into play the good temperature characterisitic that it had originally.Particularly its meaning is very big and can realize using LST sliced crystal substrate and surface acoustic wave apparatus that be used for the high frequency field in the high frequency field.

Using Li ₂B ₄O ₇Substrate during as piezoelectric substrate to use 45 ° of rotation X cutting substrates better.

As in the aluminium film, adding the additive of micro-Cu, Ti, Ni, Mg, Pd etc., be effective then to further inhibition migration.The addition of this additive can be selected in the scope of 0.1 weight %-10 weight %.

Fig. 1 is the plane graph of the surface acoustic wave apparatus of one embodiment of the invention.

Fig. 2 represents the transmission characteristic of 50 Ω systems of surface acoustic wave apparatus shown in Figure 1.

Fig. 3 is the manipulated or operated apparatus of using for the anti-electricity characteristic of estimating surface acoustic wave apparatus.

The curve that Fig. 4 uses for the termination of judging the life-span of being caused by stress migration for expression.

Fig. 5 A is the photo that the aluminium film of embodiments of the invention obtains by reflection high-velocity electrons diffraction (reflection high-enery electron diffraction).

Fig. 5 B is the key diagram of Fig. 5 A.

Fig. 6 A is the aluminium film according to comparative example, by reflecting the photo that the high-velocity electrons diffraction obtains.

Fig. 6 B is the key diagram of Fig. 6 A.

The photo that Fig. 7 A obtains by reflection high-velocity electrons diffraction for according to another embodiment of the present invention aluminium film.

Fig. 7 B is the key diagram of Fig. 7 A.

Fig. 8 is the curve chart that is illustrated in the relation of the thickness of the aluminium electrode among the embodiment shown in Fig. 7 A and its resistivity.

With reference to Fig. 1, surface acoustic wave apparatus 1 has piezoelectric substrate 2.On the surface of piezoelectric substrate 2, for example be formed with two interdigital transducers 3 and 4, with and the position seemingly clamp 2 reflectors 5 and 6 of these transducers 3,4.Interdigital transducer 3 has paired interdigital electrode 7 and 8.Be equipped with in the electrode on the interdigital electrode 7 and refer to refer on a part opposed with respect to the electrode that is equipped with on interdigital electrode 8.Interdigital transducer 4 has paired

interdigital electrode

9 and 10 on the other hand.Be equipped with in the electrode on the interdigital electrode 9 and refer to refer on a part opposed with respect to the electrode that is equipped with on interdigital electrode 10.

Interdigital electrode

7,8,9 links to each other with

lead terminal

11,12,13 and 14 respectively with 10.

Reflector 5 forms by having a plurality of parallel and

routine bonding jumpers

15 and 16 grid electrode respectively with 6.

Such surface acoustic wave apparatus 1 both can have been worked as 2 port SAW harmonic oscillator usefulness, can work as 2 port SAW filters again and use.In the occasion of SAW harmonic oscillator, the either side that can omit transducer 3 and 4 becomes 1 port SAW resonator.Reflector 5 and 6 can not formed by bonding jumper again, but provide by formed a plurality of grooves on piezoelectric substrate.In the occasion of SAW filter, available transducer 3 and 4 either party then are output transducer for its opposing party of input transducer.In the occasion of filter, also can be without reflector 5 and 6.And also available transducer more than 3 constitutes.

Describe by the details of its manufacturing sequence below surface acoustic wave apparatus shown in Figure 11.

33.5 ° of rotary Y cuttings after the use mirror ultrafinish cut crystal substrate as piezoelectric substrate 2.

On the surface of this piezoelectric substrate 2, by electron beam evaporation plating with about 1000 Thickness form the aluminium film.

When forming above-mentioned aluminium film, usually the temperature of evaporation rate and substrate 2 was hanked 10 respectively in the past / second and+160 ℃, by comparing, make evaporation rate higher and temperature substrate 2 is lower with such condition, found the aluminium film in the possibility that is directed to certain orientation aspect the crystal orientation.Be set at 40 according to the experiment that the present inventor carried out at evaporation rate

When the temperature of/second and substrate 2 is set at 80 ℃, obtained the aluminium film of (311) orientations.

(311) face of this aluminium film is made epitaxially grown situation and has been obtained confirmation with reflection high-velocity electrons diffraction (RHEED) method.Fig. 5 A is with so resulting photo of RHEED method.Fig. 5 B is the key diagram of Fig. 5 A.

17 is the direct projection spot of electron ray in Fig. 5 B, and seen in 18 in the zone be reflective graphics.In the reflective graphics shown in Fig. 5 A and Fig. 5 B, spot why occurs and be can confirming that from this point resulting aluminium film is just carrying out epitaxial growth because on crystal structure, there is periodic cause.

On the other hand, confirmed that at above-mentioned evaporation rate be 10 / second and substrate temperature are not carrying out epitaxial growth for the aluminium film of institute's evaporation under+160 ℃ the condition, and become random orientation (noncrystal).RHEED photo about this comparative example is Fig. 6 A.Fig. 6 B is the key diagram of Fig. 6 A.

In Fig. 6 B, 19 is the direct projection spot of electron ray, and seen in 20 in the zone is reflective graphics.The spot that any electron ray on this reflective graphics, do not occur.The reflective graphics of zone in 20 in the form of a ring or dizzy shape.In the time can obtaining the reflective graphics of ring-type or dizzy shape like this, can be assessed as the aluminium film is polycrystalline or noncrystal.

Below, respectively various embodiments of the present invention and comparative example have been carried out following processing.

Promptly by photoetching process (photolithograph) processing aluminium film, thereby on the surface of piezoelectric substrate 2, form 2 interdigital transducers 3 and 4 and the reflector 5 and 6 that constitutes by grid electrode as shown in Figure 1.

The about 4.7 μ m of the wavelength of SAW, electrode refer in the SAW device 1 that obtains like this about 1.17 μ m of width, opening (aperture) are about 100 wavelength.Though illustrate to such an extent that simplify again in Fig. 1, the

interdigital electrode

7,8,9 and 10 that is in fact comprised in transducer 3 and 4 has 50 electrodes respectively and refers to, reflector 5 and 6 has 300 bonding jumpers respectively again.

The 50 Ω series transmission characteristic of 2 port SAW harmonic oscillators 1 of the present embodiment that obtains so as shown in Figure 2.The peak value of attenuation appears at frequency and is about the 674MHZ place as can be seen from Figure 2, and the insertion loss at this crest frequency place is about 6 decibels of dB.The longitudinal axis on the left side in Fig. 2 is represented relative attenuation, and is the zero shellfish with the insertion at crest frequency place loss.The SAW harmonic oscillator of comparative example has also been represented and roughly the same characteristic shown in Figure 2.

Coming the anti-electricity characteristic in each embodiment and the comparative example with device shown in Figure 3 below is that the stress migration suppression characteristic is estimated.In device shown in Figure 3, carry out power amplification by the output of 22 pairs of oscillators 21 of power amplifier, and the output of power amplifier 22 is added on the SAW harmonic oscillator 1.Output P(t with SAW harmonic oscillator 1) is input on the power meter 23, and measures its output level therein.The output of power meter 23 machine 24 as calculated feeds back to oscillator 21, in view of the above the frequency of oscillator 21 is controlled, and is made the frequency that is added to the signal on the SAW1 be always crest frequency in the transmission characteristic.SAW harmonic oscillator 1 is packed into and is therefore made the environment temperature of SAW harmonic oscillator 1 up to 85 ℃ in the thermostat 25.This is in order to make the condition of the speed of SAW harmonic oscillator 1 deterioration add to SAW harmonic oscillator 1 in order to raising.

Make power amplifier 22 be output as 1W(50 Ω series like this), measure the output level Po at initial stage in advance, and with through the output P(t behind the t sometime) become P(t)≤be the life-span td of SAW harmonic oscillator 1 in Po-1(dB).This is owing to it is generally acknowledged P(t) curve can become as shown in Figure 4.It is suitable that the time that former output Po with the initial stage reduces 1dB is estimated as life-span td.

Test portion A, B that estimated and C constitute interdigital transducer 3 and 4 and the test portion of reflector 5 and 6 with aluminium film as shown below.

A: the fine aluminium of random orientation

B: the copper of the fine aluminium+1Wt% of random orientation

C: epitaxially grown fine aluminium

Test portion A and B are the test portions that is equivalent to comparative example of the present invention.Herein, test portion B has added the test portion with the copper that suppresses migration effect.On the other hand, test portion C is the test portion that is equivalent to embodiments of the invention.

Again in test portion A, B and C with the identical crystal substrate of cutting angle as piezoelectric substrate, and the figure of transducer and reflector also is identical.

In the occasion of estimating the life-span td of each test portion with device shown in Figure 3, then:

Below A:5 divides

B: about 150 minutes

More than C:900 divides.

Herein,, then improved more than 30 times in the life-span,, then brought up to more than 6 times in the life-span again by making the aluminium film carry out epitaxial growth as test portion B and C are compared by adding copper as test portion A and B are compared.In other words, can find out that in the time will comparing with C test portion C compares certain life-span of 180 times of having realized surpassing with test portion A with the test portion A of fine aluminium.

Below, add copper and also be applicable to test portion C, because of confirmed this copper that adds by test portion B the effect that suppresses migration is arranged.Promptly made and removed outside the aluminium epitaxial film that forms the copper that has added 1Wt% all identical test portion with test portion C.About this test portion since during the power of the known 1W of adding long being not suitable for of life-span experimentize, so add the power of 2.5W.Confirmed to reach the life-span more than 8000 minutes in view of the above.Generally, the accelerator coefficient that is caused by power is said to be 3 to 4 powers, so the accelerator coefficient of the occasion of 2.5W is 2.5 of 1W ³To 2.5 ⁴Doubly, promptly be about 15 to 39 times.Thereby during 2.5W be life-span more than 8000 minutes as being converted to the occasion of 1W, then the life-span is equivalent to about more than 120,000 to 312,000 minutes.

The occasion of interpolation copper is compared with the occasion of fine aluminium epitaxial film and can be obtained about 130 to 340 times life-span on the aluminium epitaxial film like this.The effect that same life-saving is also arranged when adding the such additive of titanium Ti, nickel, magnesium Mg, palladium Pd outside the known copper removal.The addition of such additive is not owing to as too smallly then have a substantial effect.So need be added to usually more than the 0.1wt%, and for example cross at most because the resistivity of aluminium film increases, so be preferably in below the 10Wt% usually.

Can also on piezoelectric substrate, be pre-formed the substrate as the aluminium alignment films such as the extremely thin titanium Ti film that is thinned to its orientation of not overslaugh or chromium Cr film.

The aluminium epitaxial film becomes (311) orientation on 25 ° of crystal substrates that cut to 39 ° of rotary Y cuttings, and also can be orientated on the crystal substrate of the cutting angle beyond this.

Generally, for the aluminium film is done epitaxial growth, lattice must mate mutually between substrate and aluminium film.Cut between crystal substrate and the aluminium film because about 30 ° of rotary Y cuttings cut (311) face of crystal substrate and aluminium epitaxial film mates on lattice at rotary Y cutting, the aluminium film is orientated on (311) face on the crystal substrate so cut at 25 ° to 35 ° rotary Y cuttings, and carries out epitaxial growth.What but (311) face of aluminium epitaxial film might not be with crystal substrate is surperficial parallel.When the cut surface of crystal substrate during from above-mentioned angle deviating, the orientation of (311) face of aluminium epitaxial film tilts with the cut surface of crystal substrate.Thereby in other the occasion of rotation cutting angle, also can determine the direction of orientation of aluminium film corresponding with it, so crystal substrate is not particularly limited in rotary Y cutting and cuts.For example, in the occasion of 2 rotation sliced crystals, (311) face of aluminium film can make the aluminium film carry out epitaxial growth on the direction of the matching condition that satisfies lattice substantially.

Associated is cut (LST cutting) crystal substrates as piezoelectric substrate with 105 ° after mirror ultrafinish rotations, and is carried out the processing same with the foregoing description therewith, can obtain SAW device 1 as shown in Figure 1.105 ° of rotation sliced crystal substrates that use herein have the opposite of the good strong point of temperature characterisitic as mentioned above, and the thickness of the aluminium electrode of Xing Chenging becomes 1% weakness that the Q value reduction of generation harmonic oscillator also arranged when above of the wavelength of SAW thereon.

Such crystal substrate as piezoelectric substrate 2 shown in Figure 1, is formed thickness about 400 by the electron beam evaporation plating condition identical with the above embodiments on piezoelectric substrate

The aluminium film of (wavelength about 0.7%).And available RHEED method confirms that this aluminium film is just in epitaxial growth.Fig. 7 A is the RHEED photo of resulting aluminium film.Fig. 7 B is the key diagram of Fig. 7 A.

The direct projection spot of 26 expression electron raies in Fig. 7 B.Reflective graphics appears on zone 27.In this reflective graphics, can confirm to represent that the aluminium film is carrying out epitaxially grown spot.

Press above-mentioned such resulting aluminium film with photoetching process processing below, and make 2 port SAW harmonic oscillators 1 as shown in Figure 1.The wavelength that this harmonic oscillator 1 is removed SAW is that the width that about 5.9 μ m, electrode refer to is 1.47 μ m, the number that constitutes the grid electrode bonding jumper of each reflector 5 and 6 is outside 500, and is all identical with the foregoing description.

This SAW harmonic oscillator 1 characteristics showed and characteristic shown in Figure 2 are practically identical.

With device shown in Figure 3 and with the method identical the life-span is estimated below with the above embodiments.

At first, concerning formed with the epitaxial growth pure aluminium film transducer 3 and 4 and the test portion of reflector 5 and 6, in the life-span that can obtain under the situation that adds 1W power more than 800 minutes.Again with regard to formed transducer 3 and 4 and the test portion of reflector 5 and 6 from the epitaxial growth aluminium film that is added with 1Wt% copper, owing to oversize being unsuitable for of life-span when adding 1W power experimentizes, so added the power of 2.5W.The life-span of this test portion reached more than 7000 minutes in view of the above.This life-span as by above-mentioned accelerator coefficient, be scaled the occasion of 1W, then its life-span is equivalent to about more than 105,000 to 273,000 minutes.

Identical with the above embodiments, when adding copper on the aluminium epitaxial film, the addition of copper is preferably between the 0.1Wt% to 10Wt%.Also can add Ti, Ni again, Mg, Pd wait and replace adding copper.

As a comparative example, identical with the person that is used for the foregoing description is piezoelectric substrate with LST sliced crystal substrate, thereon with identical 400

Thickness forms the aluminium film of random orientation, has obtained same 2 port SAW harmonic oscillators.But the insertion of this harmonic oscillator loss fails to show the original characteristic that has of 2 port SAW harmonic oscillators greatly and fully.

Thereby, with regard to aluminium epitaxial film and aluminium random orientation film, studied the relation of the thickness of each film and resistivity after, its result obtains result shown in Figure 8.In Fig. 8, on transverse axis, represent thickness (

), on the longitudinal axis, represent resistivity (Ω cm).Solid line is the occasion of aluminium epitaxial film again, and dotted line is the occasion of aluminium random orientation film.

As shown in Figure 8, at aluminium epitaxial film (solid line) even the occasion thickness be 400 , also can keep low-resistivity, in contrast,, be 400 at thickness in the occasion of aluminium random orientation film (dotted line) The time, shown resistivity is big in the extreme.Its reason can think because aluminium random orientation film is made of the set of crystal grain, so at thickness hour, film becomes island constructs, and can not reach favorable conductive.

Be as piezoelectric substrate in the above description with crystal substrate.And also can use LiTaO ₃Substrate, LiNbO ₃Substrate, LiB ₄O ₇Substrate, ZnO/Al ₂O ₃Substrates etc. are made piezoelectric substrate.Even on these latter's piezoelectric substrate, also can form the aluminium alignment films by membrance casting condition and/or the film build method (for example ion beam sputtering, the method that ion plating is such) of suitably selecting aluminium.In these occasions, perhaps be the aluminium epitaxial film, perhaps be not limited to (311) alignment films.In a word, the crystal orientation of aluminium epitaxial film is confirmed as satisfying the condition that each lattice is complementary between aluminium film and substrate.

Particularly as using the big LiT of electricapparatus attachment coefficient ₂O ₃Substrate, LiNb ₂O ₃Substrate or Li ₂B ₄O ₇Substrate is then compared with the occasion with crystal substrate.Can realize pass band and lose little SAW filter and the little harmonic oscillator of Capacity Ratio.Particularly as using 45 ° of rotation cutting Li ₂B ₄O ₇Substrate can realize that then temperature coefficient is zero SAW device.

Claims

1, a kind of surface acoustic wave apparatus comprises:

Piezoelectric substrate;

The electrode assembly that on above-mentioned piezoelectric substrate, forms;

It is characterized in that:

Above-mentioned electrode assembly contains the aluminium film that is oriented to certain orientation on crystal orientation, and above-mentioned aluminium film is (311) alignment films.

2, a kind of surface acoustic wave apparatus comprises:

Piezoelectric substrate;

The electrode assembly that on above-mentioned piezoelectric substrate, forms:

It is characterized in that:

Above-mentioned electrode assembly contains the aluminium film that is oriented to certain orientation on crystal orientation, and above-mentioned aluminium film is (311) alignment films, and is epitaxially grown.

3, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned piezoelectric substrate is that rotary Y cutting cuts crystal substrate.

4, surface acoustic wave apparatus as claimed in claim 3 is characterized in that the anglec of rotation that above-mentioned rotary Y cutting cuts crystal is 25 ° to 39 °.

5, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned piezoelectric substrate is LiTaO ₃Substrate.

6, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned piezoelectric substrate is LiNbO ₃Substrate.

7, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned piezoelectric substrate is Li ₂B ₄O ₇Substrate.

8, surface acoustic wave apparatus as claimed in claim 7 is characterized in that above-mentioned Li ₂B ₄O ₃Substrate is 45 ° of rotation cutting substrates.

9, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned piezoelectric substrate has sapphire substrate and epitaxially grown ZnO film on above-mentioned sapphire substrate.

10, surface acoustic wave apparatus as claimed in claim 1 or 2 is characterized in that above-mentioned aluminium film contains at least a additive of selecting by from the group that Cu, Ti, Ni, Mg and Pd formed of forming.

11, surface acoustic wave apparatus as claimed in claim 10 is characterized in that above-mentioned additive contains 0.1 weight % to 10 weight % in above-mentioned aluminium film.

12, surface acoustic wave apparatus as claimed in claim 3 is characterized in that the anglec of rotation that above-mentioned rotary Y cutting cuts crystal is 103-107 °

13, a kind of elastic wave resonant's comprises:

Piezoelectric substrate: and

On above-mentioned piezoelectric substrate, form, at least one transducer and position thereof seemingly clamp at least two reflectors of above-mentioned transducer.

It is characterized in that:

Above-mentioned transducer contains the aluminium film that is oriented in certain orientation aspect crystal orientation, and above-mentioned aluminium film is (311) alignment films.

14, surface acoustic wave apparatus as claimed in claim 13 is characterized in that above-mentioned reflector contains at the aluminium film that is oriented in aspect the crystal orientation on the certain orientation.

15, a kind of acoustic surface wave filter comprises

Piezoelectric substrate:

The input and output transducer that on above-mentioned piezoelectric substrate, forms;

It is characterized in that:

Above-mentioned input and output transducer contains at the aluminium film that is oriented in aspect the crystal orientation on the certain orientation, and above-mentioned aluminium film is (311) alignment films.