WO2006114922A1

WO2006114922A1 - Surface acoustic wave element, composite piezoelectric chip and method for manufacturing such surface acoustic wave element

Info

Publication number: WO2006114922A1
Application number: PCT/JP2006/301514
Authority: WO
Inventors: Masayuki Tanno
Original assignee: Shin-Etsu Chemical Co., Ltd.
Priority date: 2005-04-25
Filing date: 2006-01-31
Publication date: 2006-11-02
Also published as: JP2006304206A

Abstract

A surface acoustic wave element wherein an electrode for exciting and detecting surface acoustic waves is formed on a piezoelectric substrate is characterized in that the element is provided with at least a composite piezoelectric chip, which is formed by machining a composite piezoelectric substrate, having the piezoelectric substrate bonded to a supporting substrate, into a chip shape, and a mounting board for mounting the composite piezoelectric chip by flip chip bonding. The surface acoustic wave element is also characterized in that mounting is performed to have an expansion coefficient αc(ppm/°C) of the surface of the piezoelectric substrate in a specific direction and an expansion coefficient αs(ppm/°C ) of the mounting board satisfy the relationship of αs<αc<αs+6. Thus, the surface acoustic wave element having high productivity and high frequency temperature characteristic improving effects, the composite piezoelectric chip and a method for manufacturing such surface acoustic wave element are provided.

Description

Specification

Surface acoustic wave device, composite piezoelectric chip, and manufacturing method thereof

Technical field

The present invention relates to a surface acoustic wave device, a composite piezoelectric chip used for a surface acoustic wave device, and the like, and a method for manufacturing the same. Background art

[0002] For example, a surface acoustic wave (SAW) element in which a comb-shaped electrode for exciting a surface acoustic wave is formed on a piezoelectric substrate is used as a frequency selection component in high-frequency communication such as a cellular phone. It is done. The piezoelectric substrate material used for this has a high conversion efficiency (hereinafter referred to as an electromechanical coupling coefficient) from an electric signal to mechanical vibration, and the center of a filter or the like determined by the electrode interval of the comb electrodes and the acoustic velocity of the elastic wave. It is required that the frequency does not vary with temperature (hereinafter referred to as frequency-temperature characteristics).

That is, it is preferable to have a piezoelectric substrate having both a large electromechanical coupling coefficient and a small frequency temperature coefficient.

An example of a piezoelectric substrate that realizes such characteristics is a composite piezoelectric substrate in which a piezoelectric substrate and another substrate are bonded.

[0003] As an example of such a composite piezoelectric substrate, an electrode for exciting and detecting an elastic wave is provided on the surface of the piezoelectric material, and the composite laminate is bonded to the back surface of the piezoelectric material. A temperature stabilized surface acoustic wave device is disclosed. In this surface wave device, temperature is corrected in the piezoelectric material by inducing a controlled stress change in the piezoelectric material (see Japanese Patent Application Laid-Open No. 51-25951).

In this example, “a LiNbO (lithium niobate) substrate is firmly bonded to the composite laminate.

Three

As described above, a compressive force is generated on the substrate as described above, and this compressive force increases as the temperature increases. By force, a means for correcting the influence of temperature on the delay time and the filter center frequency can be obtained. It is said that. This is because the expansion coefficient of the composite laminate as the support substrate is higher than that of the surface acoustic wave propagation direction of the LiNbO substrate, which is a piezoelectric material. This means that the stress is generated in the piezoelectric substrate according to the temperature change, and the influence of the temperature on the delay time and the filter center frequency of the SAW device can be corrected.

[0004] Further, there is disclosed an electrical component in which a functional element having an electrode on the surface of the piezoelectric plate is housed in a package by bonding a rigid plate and a piezoelectric plate using an adhesive. (See JP-A-02-62108).

That is, a surface acoustic wave device using a composite piezoelectric substrate in which a piezoelectric material and a substrate having a smaller expansion coefficient are bonded together has improved frequency-temperature characteristics, uses an adhesive, and uses a rigid plate and a piezoelectric plate. It is a known technique to bond plates together to form an integrated substrate.

[0005] Further, a piezoelectric substrate, an interdigital transducer (IDT) and a bump each having a plurality of electrode fingers and a bus bar that connects these electrode fingers in common are formed on the piezoelectric substrate. The surface acoustic wave device is mounted on a mounting substrate by flip chip bonding via the bump, and the mounting substrate is smaller than the piezoelectric substrate. A surface acoustic wave device having a linear expansion coefficient, wherein the bump is arranged so that thermal expansion and contraction of the piezoelectric substrate due to temperature change are suppressed by the mounting substrate. A mounting structure is disclosed (see JP 2003-324334 A).

In this example, LiTaO (expansion coefficient 16ppm / ° C) is used as the piezoelectric body.

Three

A surface acoustic wave filter mounted on a mounting board by means of flip-chip bonding using alumina (expansion coefficient 7ppm / ° C) as a base material has a frequency fluctuation of l lkHz at an operating frequency of 1.9GHz. It is disclosed that it has been improved by / ° C.

This improvement effect is preferably improved by about 6ppmZ ° C in terms of temperature coefficient.

[0006] On the other hand, BPAbbot, J.Caron, J.Chocola, K.Lin , S.Malocha, N.Naumenko and P.Wei sh, "Advances in Rf SAW Substrates", 2 nd International Symposium on Acoustic Wav e Devices for In Future Mobile Communication Systems, pp.233-243, 2003, 48 ° rotated Y-cut LiTaO is used as the piezoelectric material, and the Si substrate that is the supporting substrate is used for this piezoelectric material. A surface acoustic wave device using a composite piezoelectric substrate directly bonded via an SiO layer is disclosed.

2

Has been. The operating frequency temperature characteristics of this surface acoustic wave device are -12 ppm / ° C when the composite piezoelectric chip is connected by the bonding wire method. (Or _35ppm / ° C) and it is described that the temperature characteristics deteriorate.

Disclosure of the invention

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface acoustic wave device and a composite piezoelectric chip that have high productivity and high effect of improving frequency temperature characteristics, and a method for manufacturing the same. It is to provide.

In order to solve the above problems, the present invention provides a surface acoustic wave element in which an electrode for exciting and detecting a surface acoustic wave is formed on a piezoelectric substrate, and includes at least a piezoelectric substrate and a support substrate. A composite piezoelectric chip obtained by processing the bonded composite piezoelectric substrate into a chip shape, and a mounting substrate on which the composite piezoelectric chip is mounted by flip chip bonding, and an expansion coefficient ac (ppm / ° in a specific direction on the surface of the piezoelectric substrate) C) and the expansion coefficient as (ppm ° C) of the mounting board,

ひ S 、ひひ S + Ό

Provided is a surface acoustic wave device that is mounted so as to satisfy the following relationship.

[0009] As described above, a composite piezoelectric chip in which a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate is added to a chip shape, and a mounting substrate on which the composite piezoelectric chip is mounted by flip chip bonding are provided. If the piezoelectric substrate surface is mounted so that the expansion coefficient ac in a specific direction and the expansion coefficient s of the mounting board satisfy the above relationship, the productivity will be high. Can be an element.

[0010] In this case, the specific direction is preferably within ± 0.5 degrees from the propagation direction of the surface acoustic wave excited by the electrode.

As described above, if the specific direction is within ± 0.5 degrees from the propagation direction of the surface acoustic wave, the effect of improving the frequency-temperature characteristics can be obtained with certainty, and the propagation opening of the surface acoustic wave can be obtained. Therefore, the surface acoustic wave element can be obtained with less insertion loss and less insertion loss.

[0011] The mounting substrate is preferably made of alumina or a low expansion ceramic.

Thus, if the mounting board is made of alumina or low expansion ceramic, the composite piezoelectric chip can be mounted so that the expansion coefficient Hc and Hs satisfy the above relationship by adjusting the thickness of the piezoelectric board. The surface acoustic wave device can be made.

[0012] Preferably, the piezoelectric substrate is made of one of lithium tantalate, lithium niobate, and lithium borate.

Thus, if the piezoelectric substrate is made of a crystalline material having a large electromechanical coupling coefficient, a surface acoustic wave element with a wide bandwidth as a frequency selective filter and a small insertion loss can be obtained.

[0013] The composite piezoelectric chip is preferably mounted via bumps.

As described above, if the composite piezoelectric chip is mounted via the bumps, the surface acoustic wave element can be effectively electrically and mechanically connected.

Further, the present invention is a composite piezoelectric chip obtained by processing a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate into a chip shape, and the composite piezoelectric chip excites a surface acoustic wave on the piezoelectric substrate. 'The electrode to be detected is formed and mounted on the mounting board by flip chip bonding, and the expansion coefficient Hc (pp m / ° C) in the specific direction of the surface of the piezoelectric substrate is the expansion of the mounting board. Coefficient as (ppm / ° C),

a s <a c, α S + Ό

Provided is a composite piezoelectric chip that is mounted so as to satisfy the following relationship.

[0015] Thus, a composite piezoelectric chip in which a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate is added to a chip shape, and an electrode for exciting and detecting a surface acoustic wave is formed on the piezoelectric substrate. And mounted on the mounting board by flip-chip bonding, and further mounted so that the expansion coefficient in a specific direction of the piezoelectric substrate surface satisfies the above relationship with the expansion coefficient of the mounting board. Thus, a composite piezoelectric chip capable of producing a surface acoustic wave device with high productivity and high frequency temperature characteristic improvement effect can be obtained. In this case, the specific direction is preferably within ± 0.5 degrees from the propagation direction of the surface acoustic wave excited by the electrode.

As described above, if the specific direction is within ± 0.5 degrees from the propagation direction of the surface acoustic wave, the effect of improving the frequency-temperature characteristics can be surely obtained, and the propagation loss of the surface acoustic wave is reduced. Can be a composite piezoelectric chip that can produce surface acoustic wave elements with low insertion loss

[0017] Preferably, the mounting substrate is made of alumina or a low expansion ceramic.

As described above, if the mounting substrate on which the composite piezoelectric substrate is mounted is made of alumina or low expansion ceramic, the relationship between the expansion coefficient Hc and Hs can be obtained by adjusting the thickness of the piezoelectric substrate. It can be a composite piezoelectric chip that can be mounted so as to satisfy.

[0018] The piezoelectric substrate is preferably made of one of lithium tantalate, lithium niobate, and lithium borate.

Thus, if the piezoelectric substrate is made of a crystal material having a large electromechanical coupling coefficient, a composite piezoelectric chip capable of producing a surface acoustic wave element with a wide bandwidth as a frequency selective filter and a small insertion loss can be obtained. .

[0019] The composite piezoelectric chip is preferably mounted via bumps.

As described above, if the composite piezoelectric chip is mounted via the bumps, the composite piezoelectric chip can be effectively electrically and mechanically connected.

[0020] The present invention also relates to a method for manufacturing a surface acoustic wave element, wherein at least a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate to each other in a chip shape is processed on the piezoelectric substrate. When an electrode for exciting and detecting surface acoustic waves is formed and the composite piezoelectric chip is mounted on a mounting substrate by flip chip bonding, the expansion coefficient Hc (ppm / ° C) of the piezoelectric substrate surface in a specific direction is formed. C) and the expansion coefficient of the mounting board (s) (ppm / ° C)

a c s + o

Provided is a method for manufacturing a surface acoustic wave device that is mounted so as to satisfy the following relationship. In this way, an electrode for detecting and detecting a surface acoustic wave is formed on a piezoelectric substrate of a composite piezoelectric chip obtained by adding a composite piezoelectric substrate in which a piezoelectric substrate and a support substrate are bonded together to a chip shape. When a piezoelectric chip is mounted on a mounting board by flip chip bonding, the expansion coefficient ac (ppm / ° C) in a specific direction on the surface of the piezoelectric board and the expansion coefficient as (ppm / ° C) of the mounting board If it is mounted so as to satisfy the above, a surface acoustic wave device having a high effect of improving the frequency temperature characteristic can be manufactured with high productivity.

At this time, it is preferable that the composite piezoelectric chip is mounted via bumps.

As described above, if the composite piezoelectric chip is mounted via the bumps, it can be electrically and mechanically effectively connected.

[0023] A surface acoustic wave device according to the present invention, a composite piezoelectric chip obtained by processing a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate into a chip shape, and a mounting substrate on which the composite piezoelectric chip is mounted by flip-chip bonding If the surface acoustic wave element is mounted so that the expansion coefficient ac of the piezoelectric substrate surface in a specific direction and the expansion coefficient as of the mounting board as satisfy the relationship: ac + as + 6 Therefore, the effect of improving the frequency temperature characteristics is high, and a surface acoustic wave device can be obtained.

[0024] Further, in the composite piezoelectric chip according to the present invention, an electrode for exciting and detecting a surface acoustic wave is formed on the piezoelectric substrate, and mounted on the mounting substrate by flip chip bonding. If it is mounted so that the expansion coefficient ac in a specific direction satisfies the above relationship with the expansion coefficient as of the mounting board, it is a composite that can produce a surface acoustic wave device with high productivity and high frequency temperature characteristics improvement effect. Can be a piezoelectric chip.

Furthermore, according to the present invention, an electrode for exciting and detecting a surface acoustic wave is formed on the piezoelectric substrate of a composite piezoelectric chip obtained by processing a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate into a chip shape. When mounting a piezoelectric chip on a mounting board by flip chip bonding, the expansion coefficient H (ppmZ ° C) in a specific direction on the surface of the piezoelectric board and the expansion coefficient as (ppm / ° C) of the mounting board are as described above. If it is mounted so as to satisfy the above conditions, a surface acoustic wave device having a high effect of improving frequency temperature characteristics can be manufactured with high productivity. Brief Description of Drawings FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of a surface acoustic wave element according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0027] Embodiments of the present invention will be specifically described below, but the present invention is not limited to these.

FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of a surface acoustic wave device according to the present invention. This surface acoustic wave device 10 includes at least a composite piezoelectric substrate in which a piezoelectric substrate 2 and a support substrate 3 are bonded together. A composite piezoelectric chip 1 processed into a chip shape, and a mounting substrate 8 on which the composite piezoelectric chip 1 is mounted by flip chip bonding via bumps 7 are provided. In addition, an electrode 9 for exciting and detecting a surface acoustic wave is formed on the piezoelectric substrate 1.

The expansion coefficient et c (ppm / ° C) in the specific direction of the surface of the piezoelectric substrate 1 and the expansion coefficient as (ppm / ° C) of the mounting board and the force as It is implemented.

[0028] By having such a configuration, the surface acoustic wave element 10 can achieve a high frequency temperature characteristic improvement effect with high productivity.

That is, the surface acoustic wave device in which the composite piezoelectric substrate is mounted by flip chip bonding as in the present invention has a frequency temperature coefficient of several ppm Z ° C to several tens _P pmZ as compared with the case of mounting by the chip and wire method, for example. Productivity can be increased because it is mounted by flip chip bonding that only improves by about ° C.

[0029] If c is smaller than s, BPAbbot, J. Caron, J. Chocola, K. Lin, S. Malo cha, N. Naumenko and P. Welsh, Advances in Rf SAW Substrates ", ^{2 nd International Symposium on Acoustic Wave Devices} for Future Mobile Communication Systems, like the p p.233-243,2003, deterioration compared with the case where the frequency temperature characteristic when mounted by flip chip bonding is implemented by a chip-and-wire method As a result, it is impossible to achieve both the frequency temperature characteristics improvement effect and high productivity, and if ac is greater than _α s + 6 (ppm / ° C), the frequency temperature coefficient is improved. The effect is small, that is, it can achieve both high frequency improvement effect and high productivity by implementing it so as to satisfy the relationship of as ac ac as + 6. The expansion coefficient satisfies the above relationship. For example, the mounting may be performed by adjusting the thickness of the piezoelectric substrate, the thickness of the adhesive layer for bonding the piezoelectric substrate and the support substrate, the chip size, and the like.

[0030] If the specific direction is within ± 0.5 degrees from the propagation direction of the surface acoustic wave, the effect of the expansion coefficient appears most prominently in the propagation direction of the surface acoustic wave. An effect can be obtained reliably. In addition, the surface acoustic wave device can be obtained with less propagation loss of surface acoustic waves and less insertion loss.

Hereinafter, the surface acoustic wave element 10 will be specifically described.

The composite piezoelectric chip 1 is obtained by processing a composite piezoelectric substrate in which a piezoelectric substrate 2 and a support substrate 3 are bonded into a chip shape. The electrode 9 excites and detects surface acoustic waves on the piezoelectric substrate 2 9. And is mounted on the mounting substrate via flip-chip bonding via bumps.The expansion coefficient ac (ppmZ ° C) of the piezoelectric substrate surface in a specific direction is the expansion coefficient of the mounting substrate (s) (ppm / ° C) and H s <H c <H s +6.

By having such a configuration, the composite piezoelectric chip 1 can be a composite piezoelectric chip capable of producing a surface acoustic wave element with high productivity and high frequency temperature characteristic improvement effect.

In addition, the composite piezoelectric chip 1 is obtained by processing a composite piezoelectric substrate in which a piezoelectric substrate 2 and a support substrate 3 having an expansion coefficient smaller than the piezoelectric substrate 2 are bonded directly or via an adhesive layer 4 into a chip shape. Even if it was formed.

With such a configuration, stress is generated in the piezoelectric substrate 2 in response to temperature changes, and in addition to the effect of satisfying the above relationship with the expansion coefficient act as it can. In addition, if bonded together through the adhesive layer 4, it can be made relatively inexpensive. Such a composite piezoelectric chip 1 is prepared by, for example, applying an adhesive to one or both of the piezoelectric substrate 2 and the support substrate 3 and bonding them firmly under vacuum (composite piezoelectric substrate portion 11 is produced) It can be produced by covering it. At this time, it is preferable to clean the surface of each substrate before bonding so that no foreign matter is mixed into the adhesive surface, and the surface is hydrophilized with an ammonia-hydrogen peroxide solution or the like, or a plasma treatment is performed. The adhesion may be increased by heating the substrate to 100 ° C and pre-treating it with short-wave UV light with a wavelength of 200 nm or less and high-concentration ozone. The size of the composite piezoelectric substrate that is the base material of the composite piezoelectric chip is not particularly limited.

It can be 100mm, but it can be more or less.

The piezoelectric substrate 2 preferably has a thickness force of ˜˜: 100 μm, and the bonding surface 5 of the piezoelectric substrate 2 is processed into a rough surface. If the adhesive surface 5 is processed into a rough surface, the back reflection of the bulk wave is suppressed, and the adhesive force of the piezoelectric substrate can be further increased. Further, if the thickness of the piezoelectric substrate 2 is 5 to 100 μm, particularly preferably 15 to 30 μm, it is preferable because warpage due to heating is small and there is no crack. If the thickness of the piezoelectric substrate 2 is less than 5 zm, cracks will occur when processing the piezoelectric substrate 2 to a desired thickness if, for example, processing strain caused by polishing ij, lapping process, etc. remains inside the piezoelectric substrate. May occur. If it is thicker than 100 zm, the piezoelectric substrate 2 may be cracked when the composite piezoelectric chip 1 is heated to about 250 ° C. In order to set the thickness of the piezoelectric substrate 2 to a desired value within the above range, for example, after forming a composite piezoelectric substrate, the piezoelectric substrate may be ground, lapped, and polished (polished).

[0034] The piezoelectric substrate 2 may be any material as long as it is made of a piezoelectric crystal material such as quartz, but is made of any one of lithium tantalate, lithium niobate, and lithium borate. If so, these are crystalline materials having a large electromechanical coupling coefficient, so that a surface acoustic wave device with a wide bandwidth as a frequency selection filter and a low insertion loss can be formed, and a composite material capable of producing such a surface acoustic wave device. Can be a piezoelectric chip. A piezoelectric substrate made of these piezoelectric crystal materials can be obtained with a high quality by growing these single crystal rods by, for example, the Chiyoklarsky method and slicing them to a desired thickness.

The substrate orientation is also selected appropriately according to the type of piezoelectric crystal material, application of the surface acoustic wave device, desired characteristics, etc., such as 36 ° rotation Y-cut, 41 ° rotation Y-cut, 45 ° rotation Y-cut, etc. That power S.

[0035] The support substrate 3 may be made of, for example, synthetic quartz, but is made of Si. Preferably, both surface layers of the support substrate 3 have a thickness of 0.:! To 20 zm. The silicon oxide film 6 may be formed by being oxidized by the above.

Thus, if the support substrate 3 is made of Si, which is most practically used for manufacturing semiconductor devices, the surface acoustic wave element and the semiconductor device can be easily combined. Normally, a composite piezoelectric substrate formed by bonding a Si substrate and a piezoelectric substrate has an expansion coefficient of both substrates. Since they are different, warping may occur when heated. Therefore, warping of the composite piezoelectric chip 1 can be reduced by oxidizing both surface layers of the support substrate 3 to a thickness of 0.:! To 20 / im and forming the Si oxide film 6. Further, when the adhesive layer 4 is present, the surface resistance value is IX 10 ¹⁵ Ω or more, the resistance value of the Si support substrate 3 is 2000 Ω′cm or more, and the Si oxide film 6 is formed. If it is a thing, insulation can fully be ensured and an electrical property can also be improved. Thus, if the resistance of the adhesive layer 4 and the Si support substrate 3 is extremely large, even if the Si oxide films on both surfaces of the support substrate 3 are thin to some extent, the electrical insulation can be dramatically improved.

[0036] If the Si oxide film 6 is present only on one surface of the support substrate 3, the composite piezoelectric substrate 1 warps even at room temperature and peels off from the outer periphery when the piezoelectric substrate 2 is processed to the above thickness. Or, it is preferable because cracks occur from the outer periphery. Also, if the thickness of the Si oxide film 6 is less than 0.1 zm, the effect of reducing warpage of the composite piezoelectric substrate 1 is small. If it is thicker than 20 zm, for example, the composite piezoelectric substrate 1 is about 300 ° C in an N atmosphere. Cracks may occur in the piezoelectric substrate 2 when heated to

2

This is not preferable.

[0037] The thickness of the Si oxide film 6 does not necessarily have to be the same on both surfaces as long as it is within the above range, but it is preferable that the thickness be the same. In addition, the support substrate 3 made of Si, for example, grows a single crystal rod of Si by the floating zone method and slices it to a desired thickness, so that it has a very high resistance of 2000 Ω'cm or more. Quality product is obtained. Further, in order to oxidize both surface layers of the support substrate 3, for example, a high pressure oxidation method can be used, and the Si oxide film 6 can be easily made to have the desired thickness with high productivity.

[0038] As an adhesive constituting the adhesive layer 4, for example, if it is a photo-curing adhesive mainly composed of epoxy metal talate, a heat resistance of 250 ° C or more can be obtained, and a viscosity before photo-curing can be obtained. Since it is as low as 10 Ocps or less, a uniform adhesive layer can be easily formed by spin coating or other application methods. If the adhesive layer can be made uniform in this way, the composite piezoelectric chip 1 becomes a high-quality one that is uniformly bonded, and is more difficult to peel. And since it is photo-curable, the piezoelectric substrate 2 and the support substrate 3 can be firmly bonded and bonded by light irradiation at room temperature. Therefore, it is preferable because it can maintain a flat shape at room temperature. Furthermore, the adhesive surface resistance as large as ¹ X 10 1 ⁵ Ω, yet since tan S at 1GHz is 0.1 or less and small in a high frequency region Loss is small and preferable. Here, tan 5 is a quantity representing the dielectric loss tangent.

In such a composite piezoelectric chip 1, an electrode 9 for exciting and detecting a surface acoustic wave is formed on a piezoelectric substrate 2. The electrode 9 can be formed by using a conventional photolithography method or the like. For example, a pair of comb electrodes composed of a plurality of electrode fingers and a bus bar that commonly connects the electrode fingers face each other so that the electrode fingers intersect. One or more electrodes are formed depending on the desired function of the surface acoustic wave device. In addition, reflectors may be formed on both sides of the electrode 9.

Then, such a composite piezoelectric chip 1 is mounted on the mounting substrate 8 by conventional flip chip bonding via bumps 7 made of, for example, Au or Sn. If the mounting substrate 8 is made of anorenomina (expansion coefficient 8 ppm / ° C) or low expansion ceramic (expansion coefficient 5.5 ppm / ° C), the expansion coefficient is an appropriate value. It is easy to adjust and mount so that the above relationship is satisfied, but a mounting board made of other materials can be used.

According to the present invention, such a surface acoustic wave element 10 is provided with a surface acoustic wave on the piezoelectric substrate of the composite piezoelectric chip 1 obtained by processing a composite piezoelectric substrate in which the piezoelectric substrate 2 and the support substrate 3 are bonded into a chip shape. When the composite piezoelectric chip 1 is mounted on the mounting substrate 8 via the bump 7 by flip chip bonding, an expansion coefficient ct c (ppm / ppm) of the surface of the piezoelectric substrate 2 is formed. ° C) and the expansion coefficient _α s (ppm / ° C) of the mounting substrate 8 satisfy the relationship of as <ct c <as + 6, for example, the thickness of the piezoelectric substrate, the piezoelectric substrate and the supporting substrate Manufacturability can be achieved by adjusting the thickness of the adhesive layer to be bonded, the chip size, etc., and mounting.

[0042] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto.

(Example 1)

The surface layers on both sides of a Si substrate with a diameter of 4 inches (100 mm), a thickness of 200 zm, and a resistance of 5000 Ω 'cm were oxidized to a thickness of 6 _β m by high-pressure oxidation. Next, a 4 inch (10 Omm) 36 ° rotated Y-cut lithium tantalate (LiTaO) substrate with a thickness of 0.2 mm (200 The surface Ra (average surface roughness) was 0.12 μm by double-sided lapping.

[0043] Next, the surface of the Si substrate with an oxide film is cleaned, and the substrate is further pretreated with short-wave UV light having a wavelength of 200 nm or less and high-concentration ozone while heating to 100 ° C, and then epoxy metatalarate. A UV-curing adhesive mainly composed of was spin-coated and applied uniformly on one surface of this substrate. Next, the back surface of the LiTaO substrate is cleaned, and the adhesive is removed.

Three

Apply in the same way, and adhere the adhesive-coated surface of the Si substrate with oxide film to the LiTaO substrate

Three

The agent-coated surface was bonded under vacuum at a pressure 1 X 10- ³ mbar.

Next, the bonded composite piezoelectric substrate was irradiated with ultraviolet rays having an illuminance of 50 mW / cm ² for 10 minutes to cure the adhesive. At this time, the adhesive layer was uniformly 5 xm thick within the substrate surface. After chamfering this composite piezoelectric substrate, wrap the surface side of the LiTaO substrate.

Three

And I removed 160 x m IJ by polishing IJ, and further polished the LiTaO substrate thickness to 15

Three

It was set to μm.

[0045] When the composite piezoelectric substrate produced in this way was heated to 150 ° C, the amount of warpage was as small as 2 mm at the maximum. Next, this composite piezoelectric substrate was cut into a 1 × 1.2 mm composite piezoelectric substrate chip, and when this chip was heated to 300 ° C in an N atmosphere, the chip did not crack.

2

I got it. In addition, even if the chip is subjected to a heat cycle of 40 ° C to 125 ° C for 1000 cycles

There was no change from before the heat cycle.

[0046] Next, an electrode having an electrode width of about 0.5 microns for exciting and detecting surface acoustic waves is provided on the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. A 1-port surface acoustic wave resonator was fabricated by forming reflectors on both sides.

[0047] At this time, X is the leakage surface acoustic wave propagation direction of the surface on which the electrode of the LiTaO substrate is formed.

Three

The coefficient of expansion in the direction ± 0.5 ° was obtained by heating and cooling the composite piezoelectric chip and the temperature change of the electrode width was determined by in-situ observation, and was found to be c = 10 ppm / ° C.

[0048] Next, the composite piezoelectric chip on which the electrode is formed is made into a low expansion ceramic (expansion coefficient s = 5

Packaging was performed by flip-chip connection to a mounting board made of 5ppmZ ° C) via solder bumps made of Ag and Sn.

[0049] The temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the composite piezoelectric chip is flip-chip connected is changed from _40 ° C to 85 ° C. As a result, the temperature coefficient of the resonance frequency was 10 ppm / ° C, and the temperature coefficient of the anti-resonance frequency was 20 ppm / ° C.

[0050] (Example 2)

A Si substrate having a diameter of 4 inches (100 mm), a thickness of 200 zm, and a resistance value of 5000 Ω 'cm was prepared. Next, a 36 ° rotating Y-cut lithium tantalate (Li TaO) substrate with a diameter of 4 inches (100 mm) is 0. Smm ^ OO z m), and Ra on the surface is 0.12 x m by double-sided wrapping.

Three

I was like that.

[0051] Next, the surface of the Si substrate is cleaned, and the substrate is pre-treated with short-wave UV light having a wavelength of 200 nm or less and high-concentration ozone while heating the substrate to 100 ° C, with epoxy metatalylate as the main component. A UV curable adhesive was spin coated and applied uniformly on one side of the substrate. Next, the back surface of the LiTaO substrate is washed, and the adhesive is applied in the same manner,

Three

Pressure between the adhesive surface of the Si substrate and the adhesive surface of the LiTaO substrate is 1 X 10 " ³ mbar

Three

Were bonded together under vacuum.

Next, the bonded composite piezoelectric substrate was irradiated with ultraviolet rays having an illuminance of 50 mW / cm ² for 10 minutes to cure the adhesive. At this time, the adhesive layer was uniformly 5 μΐη thick within the substrate surface. After chamfering this composite piezoelectric substrate, the surface side of the LiTaO substrate is ground and ground.

Three

155 / i m IJ removed by wrapping and further LiTaO substrate thickness of 20 / i by polishing

Three

I became m.

[0053] When the composite piezoelectric substrate fabricated in this way was heated to 150 ° C, the amount of warpage was as small as 4 mm at maximum. In addition, when this composite piezoelectric substrate was cut into 1 x 1.2 mm composite piezoelectric substrate chips and heated to 300 ° C in an N atmosphere, the chips were not cracked.

2

It was. Also, the chip is _40. C-125. Even after 1000 heat cycles of C, there was no change from before the heat cycle.

[0054] Next, an electrode having an electrode width of about 0.5 microns for exciting and detecting surface acoustic waves is provided on the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. A 1-port surface acoustic wave resonator was fabricated by forming reflectors on both sides.

[0055] At this time, the surface acoustic wave propagation direction of the surface on which the electrode of the LiTa03 substrate is formed The expansion coefficient ac in the X direction ± 0.5 ° was obtained by heating and cooling the composite piezoelectric chip and the temperature change of the electrode width was determined by in-situ observation, and was ac = 11 ppm / ° C.

[0056] Next, the composite piezoelectric chip on which the electrode is formed is made into a low expansion ceramic (expansion coefficient a s = 5

Packaging was performed by flip-chip connection to a mounting substrate consisting of 5ppm / ° C) via solder bumps made of Sn.

[0057] The temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the composite piezoelectric chip is flip-chip connected is investigated by changing the ambient temperature from _40 ° C to 85 ° C. As a result of examining each temperature coefficient, the temperature coefficient of the resonance frequency is 14 _PP m /

The temperature coefficient of ° C and antiresonance frequency was 124ppm / ° C.

[Example 3]

A synthetic quartz substrate having a diameter of 4 inches (100 mm) and a thickness of 150 zm was prepared. Next, a 4 inch (100 mm) diameter 36 ° rotated Y-cut lithium tantalate (LiTaO) substrate is

Three

The surface Ra was 0 · 12 μm by double-sided wrapping at 0.2 mm (200 / im).

[0059] Next, the surface of the synthetic quartz substrate was cleaned, and further, this substrate was pretreated with short-wave UV light having a wavelength of 200 nm or less and high-concentration ozone while being heated to 100 ° C, and the epoxy metal talate was the main component. A UV curable adhesive was spin-coated and uniformly applied on one surface of the substrate. Next, clean the back of the LiTaO substrate and apply the adhesive in the same way

Three

Pressure between the adhesive-coated surface of the synthetic quartz substrate and the adhesive-coated surface of the LiTaO substrate 1

Three

X 10—bonded under vacuum of ³ mbar.

Next, the bonded composite piezoelectric substrate was irradiated with ultraviolet rays having an illuminance of 50 mW / cm ² for 10 minutes to cure the adhesive. At this time, the adhesive layer was uniformly 5 xm thick within the substrate surface. After chamfering this composite piezoelectric substrate, the surface side of the LiTaO substrate is ground and ground.

Three

155 μ πι ij is removed by wrapping, and the LiTaO substrate thickness is 20 μ by polishing.

Three

I tried to become m.

[0061] When the composite piezoelectric substrate thus fabricated was heated to 150 ° C, the amount of warpage was as small as 4 mm at maximum. In addition, when this composite piezoelectric substrate was cut into 1 x 1.2 mm composite piezoelectric substrate chips and heated to 300 ° C in an N atmosphere, the chips were not cracked. It was. Even when the chip was subjected to a heat cycle of 140 ° C to 125 ° C for 1000 cycles, there was no change from before the heat cycle.

[0062] Next, an electrode having an electrode width of about 0.5 microns for exciting and detecting surface acoustic waves is provided on the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. A 1-port surface acoustic wave resonator was fabricated by forming reflectors on both sides.

[0063] At this time, X is the leakage surface acoustic wave propagation direction of the surface on which the electrode of the LiTaO substrate is formed.

Three

The coefficient of expansion in the direction ± 0.5 ° was obtained by heating and cooling the composite piezoelectric chip and the temperature change of the electrode width was determined by in-situ observation, and was found to be c = 8 ppm / ° C.

[0064] Next, the composite piezoelectric chip on which the electrode is formed is made into a low expansion ceramic (expansion coefficient s = 5

Packaging was performed by flip-chip connection to a mounting board consisting of 5ppm / ° C) via solder bumps made of Sn.

[0065] The temperature dependence of the resonance frequency and anti-resonance frequency of a 1-port surface acoustic wave resonator in which the composite piezoelectric chip is flip-chip connected is investigated by changing the ambient temperature from -40 ° C to 85 ° C. As a result of examining each temperature coefficient, the temperature coefficient of resonance frequency is 13ppm /

The temperature coefficient of ° C and antiresonance frequency was 23ppm / ° C.

[0066] (Example 4)

We prepared a Si substrate with a diameter of 4 inches (100 mm), a thickness of 200 / im, and a resistance value of 5000 Ω 'cm with one side mirrored. Next, double-side polishing of a 36-degree rotated Y-cut lithium tantalate (LiTaO) substrate with a diameter of 4 inches (100mm) to a thickness of 0 · 15mm (150im)

Three

Finished by. Each of the substrates was pretreated with short-wave UV light having a wavelength of 200 nm or less and high-concentration ozone while being heated to 100 ° C.

Then, if stuck at room temperature the LiTaO substrate and the Si substrate under vacuum at a pressure l X 10_ ⁴ mbar

Three

Let

[0067] Next, two bonded substrates of the LiTaO substrate and the Si substrate manufactured by the same method

Three

It was made to oppose on the O board | substrate side, it bonded through the epoxy adhesive, and it heated to 250 degreeC.

Three

Then, it cooled to room temperature, peeled off the contact bonding layer with the sulfuric acid, and produced the composite piezoelectric substrate. Then, after chamfering this composite piezoelectric substrate, the surface side of the LiTaO substrate is ground and Lj is removed by lapping, and the thickness of LiTaO substrate is reduced to 30 / im by polishing.

Three

It was made to become.

[0068] Further, when this composite piezoelectric substrate was cut into a 1 x 1.2 mm composite piezoelectric substrate chip and this chip was heated to 300 ° C in an N atmosphere, the chip had a cracking force. In addition, the chip

2

Even when the heat cycle of _40 ° C to 125 ° C was applied for 1000 cycles, there was no change from before the heat cycle.

[0069] Next, an electrode having an electrode width of about 0.5 microns for exciting and detecting a surface acoustic wave is provided on the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. A 1-port surface acoustic wave resonator was fabricated by forming reflectors on both sides.

[0070] At this time, X is the leakage surface acoustic wave propagation direction of the surface on which the electrode of the LiTaO substrate is formed.

Three

The coefficient of expansion in the direction ± 0.5 ° was determined by in-situ observation of the temperature change of the electrode width by heating and cooling the composite piezoelectric chip and found to be c = 7 ppm / ° C.

[0071] Next, the composite piezoelectric chip on which the electrode is formed is made into a low expansion ceramic (expansion coefficient a s = 5

[0072] The temperature dependence of the resonance frequency and anti-resonance frequency of a 1-port surface acoustic wave resonator with flip-chip connection of the composite piezoelectric chip was investigated by changing the ambient temperature from -40 ° C to 85 ° C. As a result of examining each temperature coefficient, the temperature coefficient of resonance frequency is 13ppm /

In any of the above embodiments, the temperature coefficient is small for both the resonance frequency and the anti-resonance frequency.

It was confirmed that the effect of improving frequency temperature characteristics was high.

[0073] (Comparative example:! ~ 4)

As Comparative Examples 1 to 4, the resonance frequency and anti-resonance of a 1-port surface acoustic wave resonator produced by mounting a composite piezoelectric chip produced in exactly the same manner as in Examples 1 to 4 by the chip-and-wire method, respectively. The temperature dependence of the resonance frequency was manually examined by changing the ambient temperature from 140 ° C to 85 ° C, and the temperature coefficient of each was investigated. As a result, in Comparative Example 1, the temperature coefficient of the resonance frequency is 120 ppm / ° C, and the temperature coefficient of the anti-resonance frequency is 30 ppm / ° C. Met. In Comparative Example 2, the temperature coefficient of the resonance frequency was −24 ppm / ° C., and the temperature coefficient of the anti-resonance frequency was −34 ppm / ° C. In Comparative Example 3, the temperature coefficient of the resonance frequency was 23 ppm / ° C, and the temperature coefficient of the antiresonance frequency was 33 ppm / ° C. In Comparative Example 4, the temperature coefficient of the resonance frequency was _19ppmZ ° C, and the temperature coefficient of the antiresonance frequency was _29ppm / ° C. That is, in Comparative Examples:! To 4, each temperature coefficient was larger by 6 to 10 ppm / ° C than Examples 1 to 4.

[0074] (Comparative Examples 5 and 6)

4 inch (100mm) diameter 36 ° rotation Y-cut lithium tantalate (LiTaO) substrate thick

3 was 0.2 mm (200 z m), the surface was mirror-finished, and the back was lapped so that Ra would be 0.12 z m. Next, this piezoelectric substrate was processed into a 1 × 1.2 mm piezoelectric chip.

[0075] Next, an electrode having an electrode width of about 0.5 microns for exciting and detecting a surface acoustic wave is provided on the above-described piezoelectric chip so that the operating frequency is about 1.9 GHz. A 1-port surface acoustic wave resonator was fabricated by forming a reflector.

At this time, the expansion coefficient ac of the surface of the LiTa03 substrate on which the electrode is formed is X-direction ± 0.5 ° which is the direction of propagation of the leaky surface acoustic wave, and the piezoelectric chip is heated and cooled to change the temperature of the electrode width. Was obtained by in-situ observation, and was ac = 16 ppm / ° C.

Next, the piezoelectric chip on which the electrode is formed is flip-chip connected to a mounting substrate made of low expansion ceramic (expansion coefficient as = 5.5 ppm / ° C.) via solder bumps made of Ag and Sn. And packaging.

[0078] The temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the piezoelectric chip is flip-chip connected is examined by changing the ambient temperature from 40 ° C to 85 ° C. As a result of examining the temperature coefficient, the temperature coefficient of the resonance frequency was 1 26 _PP m / ° C, and the temperature coefficient of the anti-resonance frequency was as large as _36 ppm / ° C.

[0079] In addition, the temperature dependence of the resonance frequency and anti-resonance frequency of a 1-port surface acoustic wave resonator manufactured by mounting a piezoelectric chip similar to that described above by the chip-and-wire method is _40. As a result of examining each temperature coefficient by changing from ° C to 85 ° C, the temperature coefficient of the resonance frequency is -30ppm / ° C, and the temperature coefficient of the anti-resonance frequency is -40ppm / ° C. It was a threshold.

[0080] (Comparative Example 7)

We prepared a Si substrate with a diameter of 4 inches (100 mm), a thickness of 200 zm, and a resistance of 5000 Ω 'cm with one side mirrored. Then, 6 mm of SiO was deposited on the mirror-finished Si surface by plasma CVD.

2

Next, a 4 inch (100 mm) diameter, 36 ° rotated Y-cut lithium tantalate (LiTaO) substrate

3 was finished by double-side polishing to a thickness of 0.15 mm (150 μm).

[0081] The surface of the Si substrate with SiO on which the SiO is deposited is bonded to the lithium tantalate substrate.

twenty two

Nitrogen plasma was irradiated to the surface on the side.

Next, the LiTaO substrate and Si substrate are bonded together at room temperature under a vacuum of 1 X 10 ^_4 mbar.

Three

It was.

[0082] Next, two bonded substrates of the LiTaO substrate and the Si substrate manufactured by the same method were combined with LiTaO.

Three

Then, it cooled to room temperature, peeled off the contact bonding layer with the sulfuric acid, and produced the composite piezoelectric substrate. Then, after chamfering this composite piezoelectric substrate, the surface side of the LiTaO substrate is ground and

Three

110 / i m IJ is removed by lapping, and the LiTaO substrate thickness is 25 / i m by polishing.

Three

I tried to become.

[0083] Next, the composite piezoelectric substrate is cut into a 1 x 1.2 mm composite piezoelectric substrate chip, and surface acoustic waves are excited and detected on the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. An electrode with an electrode width of about 0.5 microns was provided, and reflectors were formed on both sides to produce a 1-port surface acoustic wave resonator.

[0084] At this time, X is the direction of leakage surface acoustic wave propagation on the surface of the LiTaO substrate where the electrodes are formed.

Three

The coefficient of expansion in the direction ± 0.5 ° was obtained by heating and cooling the composite piezoelectric chip and the temperature change of the electrode width was determined by in-situ observation, and c = 4 ppm / ° C.

[0085] Next, the composite piezoelectric chip with electrodes formed thereon is flip-chip connected to a mounting substrate made of alumina ceramic (expansion coefficient s = 8ppm / ° C) via solder bumps made of Ag and Sn and packaged. I did. [0086] The temperature dependence of the resonance frequency and anti-resonance frequency of a 1-port surface acoustic wave resonator in which the composite piezoelectric chip is flip-chip connected is investigated by changing the ambient temperature from -40 ° C to 85 ° C. As a result of examining each temperature coefficient, the temperature coefficient of the resonance frequency was 23 ppm / ° C, and the temperature coefficient of the anti-resonance frequency was 135 ppm / ° C, and the temperature characteristic improvement effect was small.

[0087] Further, the temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the composite piezoelectric chip is mounted in a chip-and-wire connection is set to 40 ° C force 85 ° C. until examined by changing the temperature coefficient of the result the resonance frequency of examining the temperature coefficient of each _ 12ppmZ ° C, the temperature coefficient of the anti-resonance frequency _ 22 _PP m / ° was the C and good temperature characteristics, The mounting work is complicated and the productivity is not high.

[0088] (Comparative Example 8)

A gadolinium gallium garnet (G GG) substrate having a diameter of 4 inches (100 mm) and a thickness of 200 μm was prepared. Next, a 4 ° (100mm) 36 ° rotated Y-cut lithium tantalate (LiTaO) substrate with a thickness of 0.2mm (200 μΐη) and double-sided wrapping with a surface Ra of 0

Three

12 / i Caro's to be m.

[0089] Next, the surface of the GGG substrate is cleaned, and the substrate is pretreated with short-wave UV light having a wavelength of 2 OOnm or less and high-concentration ozone while being heated to 100 ° C, and the epoxy metal talate is the main component. A UV curable adhesive was spin-coated and applied uniformly on one surface. Next, the back surface of the LiTaO substrate is cleaned, the adhesive is applied in the same manner, and the GGG substrate is applied.

Three

True adhesive coated surface of the LiTaO substrate and the adhesive coated surface of the plate of the pressure 1 X 10_ ³ mbar

Three

Bonded in the air.

Three

I tried to become m.

Next, this composite piezoelectric substrate is cut into a 1 × 1.2 mm composite piezoelectric substrate chip, and surface acoustic waves are excited to the composite piezoelectric chip so that the operating frequency is about 1.9 GHz. Do An electrode with a width of 0.5 microns was provided, and reflectors were formed on both sides to produce a 1-port surface acoustic wave resonator.

[0092] At this time, X is the leakage surface acoustic wave propagation direction of the surface on which the electrode of the LiTaO substrate is formed.

Three

The coefficient of expansion of direction ± 0.5 ° was determined by heating and cooling the composite piezoelectric chip and measuring the temperature change of the electrode width by in-situ observation, and c = 15 ppm / ° C.

Next, the composite piezoelectric chip on which the electrode is formed is flip-chip connected to a mounting substrate made of an alumina ceramic substrate (expansion coefficient s = 8 ppm / ° C) via solder bumps made of Ag and Sn. I did packaging.

[0094] The temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the composite piezoelectric chip is flip-chip connected is investigated by changing the ambient temperature from _40 ° C to 85 ° C. As a result of examining each temperature coefficient, the temperature coefficient of the resonance frequency was 1 29 _PP m / ° C, and the temperature coefficient of the anti-resonance frequency was 1 39 ppm / ° C.

[0095] Further, the temperature dependence of the resonance frequency and anti-resonance frequency of the 1-port surface acoustic wave resonator in which the composite piezoelectric chip is mounted in a chip-and-wire connection is as follows. As a result of examining each temperature coefficient, the temperature coefficient of the resonance frequency was -30 ppm / ° C, and the temperature coefficient of the anti-resonance frequency was -40 ppm / ° C, and there was no effect of improving temperature characteristics.

Note that the present invention is not limited to the above-described embodiment. The above-described embodiments are merely examples, and those having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same functions and effects will be recognized. However, it is included in the technical scope of the present invention.

[0097] For example, in the embodiment, a force Li using a 36 ° rotated Y-cut LiTaO substrate as a piezoelectric substrate.

Three

An NbO substrate or another piezoelectric substrate may be used. These piezoelectric substrates are also pyroelectric.

Three

The surface charge accumulation may be eliminated.

Claims

The scope of the claims

[1] A surface acoustic wave device in which an electrode for exciting and detecting surface acoustic waves is formed on a piezoelectric substrate, and at least a composite piezoelectric substrate in which a piezoelectric substrate and a support substrate are bonded together is processed into a chip shape A composite piezoelectric chip; and a mounting substrate on which the composite piezoelectric chip is mounted by flip chip bonding. An expansion coefficient ac (ppm / ° C) in a specific direction of the surface of the piezoelectric substrate, and an expansion coefficient of the mounting substrate S (ppm / ° C)

a s <a c, α S + Ό

The surface acoustic wave device is mounted so as to satisfy the following relationship.

[2] The surface acoustic wave device according to claim 1, wherein the specific direction is within ± 0.5 degrees from the propagation direction of the surface acoustic wave excited by the electrode. Surface wave element.

[3] The surface acoustic wave device according to claim 1 or 2, wherein the mounting substrate is made of alumina or low expansion ceramic.

[4] In the surface acoustic wave device according to any one of claims 1 to 3, the piezoelectric substrate is made of any one of lithium tantalate, lithium niobate, and lithium borate. A surface acoustic wave device.

[5] The surface acoustic wave device according to any one of claims 1 to 4, wherein the composite piezoelectric chip is mounted via a bump.

[6] A composite piezoelectric chip obtained by processing a composite piezoelectric substrate obtained by bonding a piezoelectric substrate and a support substrate into a chip shape, and the composite piezoelectric chip has electrodes for exciting and detecting surface acoustic waves on the piezoelectric substrate. Formed and mounted on a mounting substrate by flip-chip bonding, and the expansion coefficient ac (ppm / ° C) in a specific direction of the surface of the piezoelectric substrate is Mounting board expansion coefficient as (ppm / ° C),

a a c <α s + 6

A composite piezoelectric chip that is mounted so as to satisfy the following relationship.

[7] The composite piezoelectric chip according to [6], wherein the specific direction is within ± 0.5 degrees from the propagation direction of the surface acoustic wave excited by the electrode. Piezoelectric chip.

[8] The composite piezoelectric chip according to [6] or [7], wherein the mounting substrate is made of alumina or a low expansion ceramic.

[9] The composite piezoelectric chip according to any one of claims 6 to 8, wherein the piezoelectric substrate is made of any one of lithium tantalate, lithium niobate, and lithium borate. A composite piezoelectric chip characterized by that.

[10] The composite piezoelectric chip according to any one of [6] to [9], wherein the composite piezoelectric chip is mounted via bumps.

[11] A method of manufacturing a surface acoustic wave device, wherein at least an elastic surface wave is applied on a piezoelectric substrate of a composite piezoelectric chip obtained by processing a composite piezoelectric substrate in which a piezoelectric substrate and a support substrate are bonded into a chip shape. When an electrode for excitation and detection is formed and the composite piezoelectric chip is mounted on a mounting board by flip chip bonding, an expansion coefficient H (ppm / ° C) in a specific direction on the surface of the piezoelectric board, and the mounting The expansion coefficient of the substrate (s / ppm / ° C) is

a c s + o

The surface acoustic wave device is manufactured so as to satisfy the relationship.

12. The method for manufacturing a surface acoustic wave device according to claim 11, wherein the composite piezoelectric chip is A method of manufacturing a surface acoustic wave element, wherein the surface acoustic wave element is mounted via a bump.