CN100550619C - The manufacture method of Lamb wave formula high-frequency apparatus, Lamb wave formula high-frequency apparatus - Google Patents

Abstract

The invention provides the manufacture method of a kind of Lamb wave formula high-frequency apparatus, Lamb wave formula high-frequency apparatus, this equipment can improve structural strength, realize stable properties that this method is difficult for breaking, can improving rate of finished products in manufacturing step.Lamb wave formula high-frequency apparatus (10) is provided with the space (54) of area greater than the transmission region of Lamb wave by constituting at piezoelectric substrate (20) that is formed with IDT electrode (30) on the interarea and the reinforcement substrate (50) that is bonded on another interarea of piezoelectric substrate (20) on the composition surface of piezoelectric substrate (20) and reinforcement substrate (50).And the manufacture method of this Lamb wave formula high-frequency apparatus (10) comprising: strengthening the step that substrate (50) upward forms the recess (53) that is equivalent to space (54); In recess (53), form the step of sacrifice layer; At the slab that engages piezoelectric substrate (20) with strengthen substrate (50) afterwards, the slab of piezoelectric substrate (20) ground be the step of specific thickness; Form the step of IDT electrode (30) and reflector (41,42); And remove sacrifice layer to form the step in space (54).

Description

Ram wave type high frequency device, manufacturing method of Lamb wave type high frequency device

technical field

The present invention relates to a Lamb wave type high frequency device and a method for manufacturing the Lamb wave type high frequency device. Specifically, it relates to a Lamb wave type high-frequency device formed by bonding a reinforcing substrate to a piezoelectric substrate having IDT electrodes and a method of manufacturing the same.

Background technique

Conventionally, as representative examples of high-frequency resonators, there are surface acoustic wave devices using Rayleigh waves, leaky waves, and SH waves, and those using volume waves, that is, Lamb waves. Ram wave element.

For example, in a known Rayleigh-wave surface acoustic wave device, an IDT electrode is formed in the Z'-axis direction on the surface of a quartz substrate called ST-cut quartz (see, for example, Non-Patent Document 1).

Also, a known SH-wave surface acoustic wave device transmits a transverse wave in which the propagation direction of a surface acoustic wave is shifted by 90 degrees relative to STW-cut quartz, that is, ST-cut quartz (see, for example, Patent Document 1).

In addition, there is also known a Lamb wave element of a volume wave system that does not use surface acoustic waves but repeatedly reflects and propagates on the upper and lower surfaces of a piezoelectric substrate. The phase velocity of this Lamb wave element is faster than that of surface acoustic waves, so it is called It is recognized that it is particularly suitable for high frequencies (for example, refer to Non-Patent Document 2 and Patent Document 2).

In addition, it is known that an AT-cut quartz substrate is used as a piezoelectric substrate as a Lamb wave high-frequency resonator using the above-mentioned Lamb wave element. By setting the relationship between the thickness H of the quartz substrate and the wavelength λ of the Lamb wave, In the range of 0<2H/λ≤10, Lamb waves can be effectively excited.

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-233645 (pages 3 to 6, FIG. 1 )

[Patent Document 2] Japanese Unexamined Patent Publication No. 2003-258596

[Non-Patent Document 1] TECHNIALCALREPORT OF IEICE.US99-20 (199-06) pp. 37-42, "Analysis of the cycle number-temperature characteristics of elastic surface waves using the finite element method", Shigeo Kagami

[Non-Patent Document 2] The 33rd EM Symposium 2004, pages 93 to 96, "Substrates for Ram Wave Type Elastic Surface Elements", Kyohiko Nakagawa, Masayuki Momose, Shoji Kakio

In these Patent Documents 1 and 2 and Non-Patent Documents 1 and 2, the piezoelectric substrate has a thickness of several μm to several tens of μm and is easily cracked, so handling is difficult. In particular, a Lamb wave-type high-frequency device can achieve higher frequencies than surface acoustic waves. However, as disclosed in Patent Document 2, in order to excite Lamb waves, the thickness of the piezoelectric substrate must be several wavelengths. Therefore, compared with the surface acoustic wave device, there are problems that it is easy to break, difficult to handle, and lower in yield.

Contents of the invention

It is an object of the present invention to provide a Lamb wave type high-frequency device that improves structural strength and realizes stable resonance characteristics, and a manufacturing method that is less likely to break during the manufacturing process and can improve yields, with the aim of solving the aforementioned problems. .

The Lamb wave-type high-frequency device of the present invention is characterized in that it is composed of a piezoelectric substrate on which an IDT electrode is formed on one main surface, and a reinforcing substrate bonded to the other main surface of the piezoelectric substrate. The piezoelectric substrate or the reinforced substrate is provided with a space larger than the transmission area of the Lamb wave, and a joint surface is provided on the periphery of the space, and the space is provided on the reinforced substrate or the piezoelectric substrate. A groove-shaped concave portion is formed on either side of the groove, wherein the groove is opened on a pair of opposing side surfaces.

According to the present invention, since the reinforcing substrate is provided and the thin and fragile piezoelectric substrate and the reinforcing substrate are bonded together, it is possible to provide a Lamb wave type high-frequency device that has improved mechanical strength, is not easily broken, and is easy to handle.

In addition, since a space with an area larger than the transmission region of the Lamb wave is provided on the piezoelectric substrate or the reinforcing substrate, the mechanical strength can be ensured, and the energy loss of the Lamb wave excitation at the joint surface can be eliminated, and high excitation efficiency and stable resonance can be realized. Characteristics of the Lamb wave type high-frequency equipment.

The cross-sectional shape of the groove-shaped recess is formed in a substantially U-shape with openings on a pair of opposing side surfaces of the piezoelectric substrate or the reinforcing substrate, and the periphery of the recess is reinforced in two directions. The details will be described later in the embodiments, but the sacrificial layer is formed in the concave portion, and after the IDT electrode is formed, the sacrificial layer can be easily removed from the side opening.

Furthermore, in the present invention, it is preferable that the piezoelectric substrate is formed of a quartz substrate.

By using a quartz substrate as a piezoelectric substrate, it is possible to achieve a temperature characteristic superior to that of a surface acoustic wave element using an STW-cut quartz substrate or an ST-cut quartz substrate in the prior art.

In addition, in the method of manufacturing a Lamb wave type high frequency device according to the present invention, the Lamb wave type high frequency device comprises a piezoelectric substrate having an IDT electrode formed on one main surface, and another piezoelectric substrate bonded to the piezoelectric substrate. The reinforcement substrate on the main surface is composed of a space larger than the transmission area of the Lamb wave on the piezoelectric substrate or the reinforcement substrate, and a joint surface is provided on the periphery of the space, and it is characterized in that the manufacturing The method includes the step of forming a recess corresponding to the space by using a groove provided on either one of the thick plate of the piezoelectric substrate or the reinforcing substrate, wherein the grooves are located in a pair of opposing a side opening; a step of forming a sacrificial layer in the concave portion; a bonding step of bonding the thick plate of the piezoelectric substrate and the reinforcing substrate; after the bonding step, grinding the thick plate of the piezoelectric substrate to a prescribed thickness a grinding step; after the grinding step, a step of forming an IDT electrode; and a step of removing the sacrificial layer.

According to the present invention, after the sacrificial layer is formed in the concave portion, the piezoelectric substrate is bonded to the reinforcing substrate in a thick state, the piezoelectric substrate is ground to a predetermined thickness, and the IDT electrodes are formed, and the sacrificial layer is removed to form the above-mentioned space. . Therefore, since the sacrificial layer is provided immediately before the completion of the Lamb wave type high-frequency device, cracking of the piezoelectric substrate can be reduced in the middle of the manufacturing process, and the yield can be improved.

Furthermore, since the concave portion is formed in a groove shape, there is an effect that the sacrificial layer can be easily removed from the openings at both ends of the groove.

Furthermore, the present invention provides a method of manufacturing a Lamb wave type high frequency device comprising a piezoelectric substrate having an IDT electrode formed on one main surface, and a piezoelectric substrate bonded to the piezoelectric substrate. The other main surface is composed of a reinforcing substrate, and a space having an area larger than the transmission region of the Lamb wave is provided on the piezoelectric substrate or the reinforcing substrate, and a joint surface is provided on the periphery of the space, and it is characterized in that, The manufacturing method includes the steps of: forming a box-shaped recess corresponding to the space on the reinforcing substrate; providing a through hole on the bottom surface of the recess; forming a sacrificial layer in the recess; a bonding step of bonding the thick plate of the piezoelectric substrate and the reinforcing substrate; a grinding step of grinding the thick plate of the piezoelectric substrate to a predetermined thickness after the bonding step; and a step of forming an IDT electrode after the grinding step ; and the step of removing said sacrificial layer.

In this way, the concave portion has a box shape, and even if the sacrificial layer is formed inside the box, by providing the through hole communicating with the concave portion, the sacrificial layer can be removed using the through hole.

Preferably, the piezoelectric substrate is formed of a quartz substrate, and the sacrificial layer is formed of a material whose etching solution is different from that of the piezoelectric substrate.

Here, the material different from the etchant means, for example, when removing the sacrificial layer using an etching method, the sacrificial layer is dissolved by the etchant but the piezoelectric substrate is not. Zinc oxide (ZnO) and aluminum nitride (AlN )wait.

In this way, when removing the sacrificial layer, the interface between the piezoelectric substrate and the sacrificial layer is not processed using an etching solution, and good resonance characteristics can be obtained in the Lamb waves reflected from the front and back surfaces of the piezoelectric substrate.

And, it is preferable to use a quartz substrate to form the piezoelectric substrate, and include the following steps: using SiO ₂ to form the sacrificial layer, and to form an etching protection layer on the other main surface of the piezoelectric substrate; after removing the After the step of sacrificing the layer, the step of removing the etching protective layer within an area larger than the transmission region of Lamb waves.

A structure that is a vibrating body composed of a piezoelectric substrate and a reinforcing substrate is generally called a MEMS (Micro Electro Mechanical Systems) structure. SiO ₂ is generally used to form a sacrificial layer in a MEMS structure. However, since the etching solution for _SiO2 of the quartz substrate and the sacrificial layer is the same, in the step of removing the sacrificial layer, the other main surface (ie, the back surface) of the quartz substrate that is in contact with the sacrificial layer is also etched. Lamb wave-type high-frequency equipment is a volume wave, so the back will also affect the vibration characteristics. Therefore, by providing an etching protection layer on the back surface of the quartz substrate, the quartz substrate can be protected from the etchant.

In addition, the present invention provides a method of manufacturing a Lamb wave-type high-frequency device comprising a piezoelectric substrate having an IDT electrode formed on one main surface, and a piezoelectric substrate bonded to the piezoelectric substrate. The other main surface is composed of a reinforcing substrate, and a space having an area larger than the transmission region of the Lamb wave is provided on the piezoelectric substrate or the reinforcing substrate, and a joint surface is provided on the periphery of the space, and it is characterized in that, This manufacturing method includes: forming a concave portion corresponding to the space on either the thick plate of the piezoelectric substrate or the reinforcing substrate; and bonding the thick plate of the piezoelectric substrate and the reinforcing substrate. a step of filling the space with a sacrificial layer made of a thermosetting resin and curing the space after the joining step; grinding the thick plate of the piezoelectric substrate to a predetermined thickness after curing the sacrificial layer a grinding step; after the grinding step, a step of forming an IDT electrode; and a step of removing the sacrificial layer.

By using a thermosetting resin as a sacrificial layer, it is possible to inject and fill the space with a thermosetting resin after joining the thick plate of the piezoelectric substrate and the reinforcing substrate, so that a vapor deposition device and a CVD (Chemical Vapor Deposition) device for forming a sacrificial layer are unnecessary and other expensive devices.

Description of drawings

FIG. 1 is a perspective view showing a Lamborne-type high-frequency device according to Embodiment 1 of the present invention.

Fig. 2 is a cross-sectional view schematically showing the A-A cross-section in Fig. 1 .

3 is a graph showing frequency-temperature characteristics of the Lamb wave type high-frequency device according to Embodiment 1 of the present invention.

4 is a cross-sectional view schematically showing a Lamb wave type high-frequency device according to Embodiment 2 of the present invention.

FIG. 5 is a perspective view schematically showing a Lamb wave type high-frequency device according to Embodiment 3 of the present invention.

FIG. 6 is a perspective view schematically showing a Lamb wave type high-frequency device according to Embodiment 4 of the present invention.

FIG. 7 is a perspective view schematically showing a Lamb wave type high-frequency device according to Embodiment 5 of the present invention.

8 is a cross-sectional view schematically showing a state in which a Lamb wave-type high-frequency device according to Embodiment 5 of the present invention is mounted in a package.

FIG. 9 is a cross-sectional view schematically showing main manufacturing steps of the Lamb wave-type high-frequency device according to the manufacturing method 1 of the present invention.

10 is a cross-sectional view schematically showing some steps of the Lamb wave-type high-frequency device described in Embodiment 4 according to Manufacturing Method 2 of the present invention.

11 is a cross-sectional view schematically showing some steps of the Lamb wave-type high-frequency device described in Embodiment 1 according to Manufacturing Method 3 of the present invention.

12 is a cross-sectional view showing main steps of a manufacturing method when SiO ₂ is used as a sacrificial layer according to Embodiment 4 of the present invention.

13 is a cross-sectional view showing main steps of a manufacturing method when a thermosetting resin is used as a sacrificial layer according to Embodiment 5 of the present invention.

Fig. 14 shows the manufacturing method 6 of the present invention, (a) is a perspective view showing the state after the sacrificial layer is formed, and (b) is a cross-sectional view showing the C-C cross section in (a).

15 is a cross-sectional view showing a state in which a sacrificial layer made of a thermosetting resin is formed according to Manufacturing Method 7 of the present invention.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 3 show a Lamborne high-frequency device according to Embodiment 1 of the present invention, FIG. 4 shows a Lambert-type high-frequency device according to Embodiment 2, and FIG. As for the high-frequency equipment, FIG. 6 shows the Lamb wave high-frequency equipment according to the fourth embodiment, and FIGS. 7 and 8 show the Lamb wave high-frequency equipment according to the fifth embodiment. 9 to 11 show a method of manufacturing a Lamb wave type high-frequency device according to the present invention.

(Embodiment 1)

1 and 2 show a Lamb wave type high-frequency device according to Embodiment 1, and FIG. 1 is a perspective view thereof, and FIG. 2 is a cross-sectional view schematically showing an A-A cutting plane in FIG. 1 . In FIG. 1 , a Lamb wave type high-frequency device 10 is constituted by bonding a piezoelectric substrate 20 and a reinforcing substrate 50 .

The piezoelectric substrate 20 is a thin plate made of a quartz substrate with the same thickness, and an IDT electrode 30 made of comb-shaped aluminum is formed on one main surface, and a pair of reflectors are formed on both sides of the IDT electrode 30 in the traveling direction of the Lamb wave. Devices 41,42. The IDT electrode 30 has IN/OUT electrodes 31 and GND electrodes 32 . The IN/OUT electrode 31 has a plurality of electrode fingers 31a and a bus bar 31b connecting the electrode fingers 31a. The GND electrode 32 has a plurality of electrode fingers 32a and a bus bar 32b connecting the electrode fingers 32a. Furthermore, the electrode fingers 31a and 32a are alternately arranged to form interdigital electrodes.

The reflectors 41, 42 are respectively composed of electrode fingers 41a, 42a arranged in a lattice, bus bars 41b connecting both ends of the electrode fingers 41a, and bus bars 42b connecting both ends of the electrode fingers 42a.

In addition, the Lamb wave type high-frequency device 10 in which the IDT electrode 30 is formed in this way is called a one-port resonator.

Next, the relationship between the IDT electrode 30 , the reflectors 41 , 42 and the reinforcing substrate 50 will be described with reference to FIG. 2 . Also refer to FIG. 1 . In FIG. 2 , the distance between the electrode fingers 31a and 32a is expressed as P _I , the line width of the electrode fingers 31a and 32a is expressed as L _I , and the respective distances between the IN/OUT electrodes 31 and the GND electrodes 32 are expressed as pull The wavelength λ of the M-wave expresses the thickness of the electrode as H _I . At this time, the wavelength λ of the Lamb wave is set to be twice the pitch _PI .

Also, the pitch of the electrode fingers 42a of the reflector 42 is expressed as P _r , the line width is expressed as L _r , and the thickness is expressed as H _r .

In the Lamb wave type high frequency, the thickness H of the piezoelectric substrate 20 is set so that the relationship between the wavelength λ of the Lamb wave is within the range of 0<2H/λ≦10 described in the above-mentioned Patent Document 2. This can effectively excite Lamb waves, which is well known. Therefore, the thickness of the piezoelectric substrate 20 is several micrometers to several tens of micrometers.

The other main surface of the piezoelectric substrate 20 on which the above-mentioned IDT electrodes 30 and reflectors 41 and 42 are formed, that is, the rear surface side, is bonded to the reinforcing substrate 50 . The reinforcement substrate 50 is a plate substrate made of silicon in this embodiment, and a box-shaped recess 53 is formed in the center. Therefore, the reinforcing substrate 50 is constituted by a concave portion 53 provided in the central portion and an edge portion 51 provided on the entire periphery of the concave portion 53 .

The piezoelectric substrate 20 is bonded to the bonding surface 52 on the upper surface of the edge portion 51 of the reinforcing substrate 50 using bonding means such as chemical bonding or an adhesive to form a space 54 . The inside of this space 54 is in a vacuum state. At this time, the bonding surface 52 forms a range away from the IDT electrode 30 and the reflectors 41 and 42 , that is, a space 54 having an area larger than the transmission region of the Lamb wave, as shown by the inner peripheral surface P in FIG. 1 . Therefore, splicing does not have any effect on the transmission of Lamb waves.

In addition, the entire peripheral portion of the piezoelectric substrate 20 is bonded to the edge portion 51 of the reinforcing substrate 50 to achieve reinforcement.

The Lamb wave type high-frequency device 10 configured in this way excites a Lamb wave by inputting an input drive signal of a predetermined frequency to the IDT electrode 30, and reflects it on the front and back surfaces of the piezoelectric substrate 20 while moving toward the direction of the reflectors 41 and 42. transmission. And, it is reflected by the reflectors 41 and 42 .

Next, the frequency-temperature characteristics of the Lamb wave-type high-frequency device 10 of the present embodiment will be described.

FIG. 3 is a graph showing the frequency-temperature characteristics of the Lamb wave type high-frequency device 10 . The vertical axis represents the resonance frequency deviation (ppm), and the horizontal axis represents the temperature (° C.). As shown in FIG. 3 , the Lamb wave-type high-frequency device 10 using a quartz substrate as the piezoelectric substrate 20 realizes frequency-temperature characteristics superior to STW-cut quartz substrates and ST-cut quartz substrates (ST-SAW).

Therefore, according to Embodiment 1, the entire peripheral portion of the concave portion 53 (that is, the space 54) is bonded to the reinforcing substrate 50, so even if the thickness of the piezoelectric substrate 20 required by excitation conditions is several micrometers, it is possible to maintain improved mechanical strength, Ram wave type high-frequency device 10 that is not easy to break and is easy to handle.

In addition, a space 54 having an area larger than the transmission region of the Lamb waves is provided between the piezoelectric substrate 20 and the reinforcing substrate 50, and the inside of the space 54 is vacuumed, so that the mechanical strength can be ensured and the Lamb wave excitation on the back surface of the piezoelectric substrate can be excluded. The energy loss of the Lamb wave type high-frequency device 10 with high excitation efficiency and stable resonance characteristics can be realized.

Furthermore, by using a quartz substrate as a piezoelectric substrate, it is possible to realize a frequency-temperature characteristic superior to an STW-cut quartz substrate or an ST-cut quartz substrate (ST-SAW).

(Embodiment 2)

Next, Embodiment 2 of the present invention will be described with reference to the drawings. In Embodiment 1 described above (see FIG. 2 ), the concave portion is provided on the reinforcement substrate side, but Embodiment 2 is characterized in that it is provided on the piezoelectric substrate side. Therefore, differences from Embodiment 1 will be mainly described.

FIG. 4 is a cross-sectional view schematically showing a Lamb wave type high-frequency device 10 according to Embodiment 2. As shown in FIG. In FIG. 4 , piezoelectric substrate 20 has IDT electrodes 30 and reflectors 41 and 42 formed on one main surface (front surface), and box-shaped recess 23 is formed on the other main surface (back surface).

The bottom thickness H of the concave portion 23 is set such that its relationship with the wavelength λ of the Lamb wave falls within the range of 0<2H/λ≦10. A rim 21 is formed around the recess 23 , and a joint surface 22 on the upper surface (lower surface in the figure) of the rim 21 is chemically or adhesively bonded to the reinforcing substrate 50 to form a space 24 . The reinforcing substrate 50 is formed using a thick plate made of silicon.

Therefore, according to Embodiment 2, the piezoelectric substrate 20 makes the edge portion 21 a reinforcing portion and is bonded to the reinforcing substrate 50 to improve mechanical strength. And, the inside of the space 24 becomes a vacuum state. Thereby, the same effect as that of Embodiment 1 described above is obtained.

(Embodiment 3)

Next, a Lamb wave-type high-frequency device according to Embodiment 3 of the present invention will be described with reference to the drawings. In the aforementioned first embodiment (see FIG. 2 ), a box-shaped recess for forming a space is provided on the reinforcing substrate, but the feature of the third embodiment is that a groove-shaped recess is provided. Therefore, differences will be mainly described.

FIG. 5 is a perspective view schematically showing a Lamb wave type high-frequency device 110 according to Embodiment 3. As shown in FIG.

”状)的凹部153。凹部153形成为横穿加强基板150，所以宽度方向的侧面开口，在长度方向两侧设有缘部151。并且，在该缘部151的上表面的接合面152上，通过化学接合或粘接剂等接合手段使压电基板20与加强基板150接合，从而形成空间154。压电基板20的结构与实施方式1(参照图2)所示的压电基板相同。On the reinforcement substrate 150 is formed a groove shape (approximately ""

” shape) of the concave portion 153. The concave portion 153 is formed to cross the reinforcing substrate 150, so the side surface in the width direction is opened, and the edge portion 151 is provided on both sides in the longitudinal direction. And, on the joint surface 152 on the upper surface of the edge portion 151, Piezoelectric substrate 20 is bonded to reinforcing substrate 150 by chemical bonding or bonding means such as an adhesive to form space 154. The structure of piezoelectric substrate 20 is the same as that of the piezoelectric substrate shown in Embodiment 1 (see FIG. 2 ).

In addition, the direction in which the recess 153 is formed is not limited as long as it has an area away from the IDT electrode 30 and the reflectors 41 and 42 , that is, an area larger than the propagation region of the Lamb wave.

(Embodiment 4)

Next, a Lamb wave-type high-frequency device according to Embodiment 4 of the present invention will be described with reference to the drawings. In Embodiment 2 described above (see FIG. 4 ), the piezoelectric substrate is provided with a box-shaped recess for forming a space, while Embodiment 4 is characterized in that a groove-shaped recess is provided. Therefore, differences will be mainly described.

”状)的凹部123。凹部123形成为横穿压电基板120，所以宽度方向的侧面开口，在长度方向两侧设有缘部121。并且，在该缘部121的上表面(在图中为下表面)的接合面122上，通过化学接合或粘接剂等接合手段使压电基板120与加强基板250接合，从而形成空间124。加强基板250的结构与实施方式2(参照图4)所示的压电基板相同。FIG. 6 is a perspective view schematically showing a Lamborne high-frequency device 210 according to Embodiment 4. As shown in FIG. Grooves are formed on the piezoelectric substrate 120 (approximately "" when viewed from the front

” shape) of the concave portion 123. The concave portion 123 is formed to cross the piezoelectric substrate 120, so the side surface in the width direction is open, and edge portions 121 are provided on both sides in the longitudinal direction. And, on the upper surface of the edge portion 121 (in the figure, On the bonding surface 122 of the lower surface), the piezoelectric substrate 120 and the reinforcing substrate 250 are bonded by chemical bonding or adhesives to form a space 124. The structure of the reinforcing substrate 250 is the same as that of Embodiment 2 (see FIG. 4 ). The piezoelectric substrate shown is the same.

In addition, the formation direction of the concave portion 123 is not limited as long as it has an area away from the IDT electrode 30 and the reflectors 41 , 42 , that is, larger than the propagation region of the Lamb wave.

Therefore, according to the aforementioned Embodiment 3 and Embodiment 4, although there is a difference that the concave portion 153 and the concave portion 123 are respectively provided on the reinforcement substrate 150 or the piezoelectric substrate 120, the structural strength of the piezoelectric substrate 120 can be improved, which is similar to the foregoing embodiment. Ways 1 and 2 have roughly the same effect.

In addition, the shape of the concave portion 123 or the concave portion 153 when viewed from the front is approximately "" The details will be described later in the manufacturing method. Forming the sacrificial layer in the concave portion 123 or the concave portion 153 has the effect that the sacrificial layer can be easily removed from the side opening after the IDT electrode is formed.

(Embodiment 5)

Next, a Lamb wave type high-frequency device according to Embodiment 5 of the present invention will be described with reference to the drawings. Embodiment 5 is characterized in that any one of the Lamb wave-type high-frequency devices 10 , 110 , and 210 described in Embodiment 1 to Embodiment 4 described above is accommodated in a package. Here, the Lamb wave type high-frequency device 10 shown in Embodiment 1 will be described as an example, and the same symbols will be assigned to the same parts.

FIG. 7 is a perspective view schematically showing a Lamb wave type high-frequency device 10 according to Embodiment 5. As shown in FIG. In FIG. 7 , a plurality of pads are provided on the upper surfaces of IDT electrodes 30 and bus bars 31 b , 32 b , 41 b , and 42 b of reflectors 41 , 42 formed on the surface of piezoelectric substrate 20 .

More specifically, two pads 33 in total are provided on the upper surfaces of the bus bars 31 b and 32 b of the IDT electrode 30 , four in total. In addition, two bonding pads 34 are provided on the respective bus bars 41 b and 42 b of the reflectors 41 and 42 , totaling four. These pads 33 and 34 are made of metal such as copper and solder, a conductive adhesive, and the like, and are formed in a substantially hemispherical shape with substantially the same size.

Furthermore, as shown in FIG. 7 , the pads 33 and 34 are provided so as to be generally balanced in plan view so as to house and bond the Lamb wave type high-frequency device 10 in the package 60 (see FIG. 8 ). Therefore, the installation positions and number of the pads 33 and 34 are not limited.

The Lamb wave type high-frequency device 10 having the pads 33 and 34 formed in this way is mounted in the package 60 .

FIG. 8 is a cross-sectional view schematically showing a state in which the Lamb wave type high-frequency device 10 is mounted in the package 60, and shows a B-B cross-section in FIG. 7 . Also refer to FIG. 7 . In FIG. 8 , the package 60 is a container formed with a case 70 and a lid 80 . In this embodiment, both the housing 70 and the cover 80 are made of ceramics.

The case 70 is formed by laminating a base body 70a and an edge portion 70b, and at the junction of the base body 70a and the edge portion 70b, the connection electrode 71 or the connection electrode 72 formed on the inner surface of the base body 70a extends to an external connection provided on the back surface of the base body 70a. terminal 75 or external connection terminal 76 (illustration of the connection state is omitted).

The Lamb wave type high-frequency device 10 faces the piezoelectric substrate 20 on the insertion base 70 a side. Here, the pad 33 provided on the bus bar 31b is arranged at the position of the connection electrode 71, the pad 33 provided on the bus bar 32b is arranged at the position of the connection electrode 72, and the pads provided on the bus bars 41b and 42b are respectively arranged. 34 are arranged at the positions of the electrode pads 73 and 74, and bonded together by means such as heating and pressure bonding. Such bonding is called flip-chip mounting.

Therefore, the IN/OUT electrode 31 (shown in FIG. 1 ) is connected to the external connection terminal 75 and the GND electrode 32 (shown in FIG. 1 ) is connected to the external connection terminal 76, so that a predetermined excitation drive signal can be input from the outside.

In addition, the reflectors 41, 42 are electrically independent from the IDT electrodes 30, so the electrode pads 73, 74 are provided in order to obtain a good balance of the Lamb wave type high-frequency device 10 and to improve the bonding strength with the substrate 70a. of.

After the Ram wave type high-frequency device 10 is mounted in the case 70, the cover body 320 is bonded to the edge portion 70b using bonding means such as chemical bonding or an adhesive. At this time, the space 61 inside the package 60 is in a vacuum state.

In the present embodiment, an example in which the Lamb wave-type high-frequency device 10 shown in Embodiment 1 is accommodated in the package 60 has been described. Devices can also be installed and housed in the enclosure 60 using the same method.

In Embodiments 1 and 2, the space 54 and the space 24 are vacuumed, and by vacuuming the space 61 inside the package 60, all the excitation regions of the Lamb waves are in a vacuum state.

Furthermore, in Embodiments 3 and 4, the space 61 is evacuated at the time of packaging, and at this time, the space 154 and the interior of the space 124 which are partly opened can also be evacuated at the same time.

Therefore, according to the above-mentioned fifth embodiment, since the Lamb wave device 10 reinforced by the reinforcing substrate 50 is further accommodated in the package 60, the Lamb wave device 10 can be protected from the external environment.

In addition, it is known that when the IDT electrode 30 is damaged or the like, or when moisture or dust adheres, the excitation characteristics are significantly degraded. However, the IDT electrodes 30 can be protected and good resonance characteristics can be maintained by being housed in the package 60 and being in a vacuum state.

In addition, since the inside of the package is kept in a vacuum state, energy loss can be suppressed also on the side of the IDT electrode 30 .

And, by setting the pads 33, 34 on the bus bars 31b, 32b, 41b, 42b that do not affect the excitation, and bonding to the connection electrodes 71, 72 and the electrode pads 73, 74, it is possible to realize the connection with the connection electrodes 71, 72. electrical connection, and securely fix the Lamb wave type high-frequency device 10 on the package 60 (substrate 70a).

In addition, by adopting flip-chip mounting, compared with the wire bonding mounting used in the mounting of surface acoustic wave elements in the past, it can also be used for fixing and connecting, so the thickness and area required for mounting can be reduced, and flatness can be realized. miniaturization and miniaturization.

(manufacturing method 1)

Next, a method of manufacturing a Lamb wave type high-frequency device according to the present invention will be described with reference to the drawings.

Fig. 9 is a cross-sectional view schematically showing the main manufacturing steps of the Lamb wave type high-frequency device of the present invention. In addition, FIG. 9 exemplifies the Lamb wave type high-frequency device 110 in which the groove-shaped concave portion 153 is formed on the reinforcing substrate 150 described in Embodiment 3 (see FIG. 5 ).

First, as shown in FIG. 9( a ), groove-shaped recesses 153 are formed on a reinforcing substrate 150 made of a silicon flat plate. As methods for forming the recessed portion 153 , there are a method of removing a portion corresponding to the recessed portion 153 by an etching method, and a method of laminating the edge portions 151 on opposite end portions of the flat base 155 . In addition, since the groove shape is formed, processing methods such as grinding can also be selected.

Then, as shown in FIG. 9( b ), a sacrificial layer 156 made of zinc oxide (ZnO) is formed inside the concave portion 153 by CVD or the like, and the upper surface of the sacrificial layer 156 and the edge portion 151 is smoothed by using a CMP method or the like. .

In addition, as the sacrificial layer 156, metals such as aluminum nitride (AlN) and Al, Cu, Cr, Ag, etc. may be used in addition to zinc oxide. The etchant for these sacrificial layer materials is different from the piezoelectric substrate made of quartz, and a material that does not dissolve the rear surface of the piezoelectric substrate by etching the sacrificial layer when removing the sacrificial layer described later is selected.

Then, as shown in FIG. 9(c), the thick plate 20a of the quartz substrate which is the raw material of the piezoelectric substrate is bonded to the reinforcing substrate 150 on which the sacrificial layer 156 is formed, using bonding means such as chemical bonding or an adhesive. In addition, here, the thickness of the thick plate 20a is set to 100 μm.

Then, as shown in FIG. 9( d ), in a state where the thick plate 20 a and the reinforcing substrate 150 a are bonded, the thick plate 20 a is ground to form the piezoelectric substrate 20 having a predetermined thickness. The thickness H of the piezoelectric substrate 20 is set so that its relationship with the wavelength λ of the Lamb wave is in the range of 0<2H/λ≦10, specifically several micrometers.

Then, the IDT electrodes 30 and the reflectors 41 and 42 are formed on the surface of the piezoelectric substrate 20 using photolithography (shown in FIG. 9( e )).

Then, as shown in FIG. 9( f ), the sacrificial layer 156 is removed by release etching to form a space 154 .

In addition, a step of forming the IDT electrode 30 and the reflectors 41 and 42 may be performed after the release etching step.

The pads 33 and 34 (see FIG. 7 ) may be formed after the IDT electrodes 30 and the reflectors 41 and 42 are formed.

(manufacturing method 2)

Next, a manufacturing method 2 of the Lamb wave type high-frequency device 210 (see FIG. 6 ) described in the foregoing fourth embodiment will be described with reference to FIG. 10 , and differences from the foregoing manufacturing method will be mainly described.

First, groove-shaped recesses 123 are formed on the thick plate 20a of the quartz substrate by etching, and sacrificial layers 125 made of zinc oxide are formed inside the recesses 123 by CVD. The upper surface of the portion 121 is smoothed.

In addition, it is bonded to the reinforcing substrate 150 using bonding means such as chemical bonding or an adhesive. Fig. 10(a) shows the state after bonding.

Then, as shown in FIG. 10(b), the thick plate 20a is ground to form a piezoelectric substrate 120 having a predetermined thickness. The thickness H of the piezoelectric substrate 120 is set such that its relationship with the wavelength λ of the Lamb wave is in the range of 0<2H/λ≦10, specifically several micrometers.

Hereinafter, the method of forming the IDT electrode 30, the reflectors 41, 42, and the method of removing the sacrificial layer 125 are the same as those described above (see FIG. 9(e) and FIG. 9(f)), so descriptions thereof are omitted.

According to the manufacturing method of the above-mentioned Lamb wave type high-frequency device, as shown in FIG. thickness of. Alternatively, as shown in FIG. 10 , the sacrificial layer 125 is formed in the concave portion 123 in the state where the piezoelectric substrate is the thick plate 20a, the concave portion 123 and the reinforcing substrate 150 are bonded, and ground to a predetermined thickness. Then, the sacrificial layer 156 or the sacrificial layer 125 is removed to form the spaces 154 and 124 .

Therefore, since the sacrificial layer 156 or the sacrificial layer 125 is provided immediately before the Lamb wave type high-frequency device is completed, cracking of the piezoelectric substrate can be reduced in the middle of the manufacturing process, and the yield can be improved.

In addition, since the concave portion 153 or the concave portion 123 is formed in a groove shape, the sacrificial layer 156 or the sacrificial layer 125 can be easily removed from the opening of the groove.

(manufacturing method 3)

Next, a method of manufacturing the Lamb wave-type high-frequency device described in Embodiment 1 will be described with reference to the drawings.

FIG. 11 shows the manufacturing method 3 of the present invention, and is a cross-sectional view schematically showing some steps of the Lamb wave type high-frequency device 10 (see FIGS. 1 and 2 ) explained in the first embodiment. This Lamb wave type high-frequency device 10 has a structure in which a box-shaped recess 53 is formed on a reinforcing substrate 50, and the recess 53 has no opening when the piezoelectric substrate 20 (thick plate 20a) is bonded thereto. Therefore, the sacrificial layer 56 cannot be removed in the manufacturing method shown in FIG. 9 . Here, this method is characterized in that the reinforcing substrate 50 is provided with the recessed portion 53 and a through-hole communicating with the bottom of the recessed portion 53 .

First, a box-shaped recess 53 and through-holes 57 and 58 communicating with the bottom of the recess 53 are provided on the reinforcing substrate 50 . Also, a sacrificial layer 56 is formed to fill at least the recess 53 (shown in FIG. 1( a )). In this way, the upper surface of the reinforcing substrate 50 including the sacrificial layer 56 is polished and smoothed, and the thick plate 20 a of the piezoelectric substrate 20 is bonded. In subsequent steps, the Lamb wave type high-frequency device 10 shown in FIG. 11( b ) is formed through the same steps as those in FIGS. 9( c ) to ( f ).

Here, the removal of the sacrificial layer 56 can be performed using the through holes 57 and 58 provided in the reinforcing substrate 50 . After the sacrificial layer 56 is removed, although not shown, the space 54 communicates with the through-holes 57 and 58 .

In addition, although the through-holes 57 and 58 are provided in FIG. 11 , the number of through-holes is not limited to two, and may be one or more. Also, the shape of the through hole is not limited, and may be, for example, circular or quadrilateral.

By accommodating the thus formed Lamb wave type high-frequency device 10 in the package 60 described in Embodiment 5 (see FIG. 8 ), the inside of the space 54 can also be kept in a vacuum state.

In addition, the Lamb wave type high-frequency device 10 of Embodiment 2 described above can also be formed by the same manufacturing method. This Lamb wave type high-frequency device 10 (see FIG. 4 ) has a structure in which a box-shaped recess 23 is formed on a piezoelectric substrate 20, and the recess 23 has no opening when the piezoelectric substrate 20 (thick plate 20a) is bonded. department. Therefore, although not shown, a through-hole communicating with the concave portion 23 of the piezoelectric substrate 20 may be provided in the reinforcing substrate 50, and the sacrificial layer may be removed from the through-hole to manufacture.

Therefore, according to the above-mentioned manufacturing method, even in the structures described in Embodiments 1 and 2 in which the box-shaped concave portion is formed on the piezoelectric substrate 20 or the reinforcing substrate 50 , by providing a through hole communicating with the concave portion, the through hole can be used. hole to remove the sacrificial layer.

(manufacturing method 4)

Next, a manufacturing method 4 of a Lamb wave type high-frequency device according to the present invention will be described with reference to the drawings. This manufacturing method 4 is a manufacturing method when _SiO2 is used as a sacrificial layer, and is a Lamb wave type high frequency device having the same structure as the Lamb wave type high frequency device 110 described in Embodiment 3 (see FIG. 5 ). Manufacturing method. Therefore, differences will be mainly described. Also refer to FIG. 9 which shows the manufacturing method of the Lamb wave type high-frequency device of Embodiment 3. FIG.

FIG. 12 shows manufacturing method 4, and is a cross-sectional view showing main steps of the manufacturing method when SiO ₂ is used as the sacrificial layer. First, as shown in FIG. 12( a ), an etching protection layer (sometimes referred to as an etching stopper layer) 25 is formed on the entire rear surface of the thick plate 20 a of the quartz substrate. The etching protection layer 25 is a thin metal layer, and its material is selected from copper, aluminum, etc., and materials different from the etchant and quartz. The etching protection layer 25 is formed by vapor deposition, sputtering, or the like.

Then, a sacrificial layer 156 made of SiO ₂ is formed inside the concave portion 153 provided in the reinforcing substrate 150 by CVD or the like (see FIGS. 9( a ) and 9 ( b )). And, after smoothing by CMP, as shown in FIG. 20a is ground to a predetermined thickness of the quartz substrate 20 .

Then, as shown in FIG. 12(c), an IDT electrode 30 and reflectors 41, 42 are formed on the surface of the quartz substrate 20 by photolithography. Then, a resist (not shown) is applied to the entire surface of the quartz substrate 20 including the IDT electrode 30 and the reflectors 41 and 42, and the sacrificial layer 156 is removed by etching.

For the removal of the sacrificial layer 156, DHF (dilute hydrofluoric acid) and BHF (buffered hydrofluoric acid) were used as etching solutions. At this time, SiO ₂ as a sacrificial layer is dissolved and removed, but the reinforcement substrate 150 made of silicon, the surface of the quartz substrate 20 covered with resist, and the etching protection layer 25 are not dissolved. Then, the etching protection layer 25 is removed by etching. The removal range of the etching resist 25 may be larger than the area of the Lamb wave transmission region, that is, the range outside the formation range of the IDT electrode 30 and the reflectors 41 and 42 .

And, when the resist is removed, the Lamb wave type high-frequency device 110 in which the space 154 is formed between the quartz substrate 20 and the reinforcing substrate 150 as shown in FIG. 12( d ) is formed.

Alternatively, after removing the sacrificial layer 156 and the etching protection layer 25 , removing the resist to form the IDT electrode 30 and the reflectors 41 and 42 may also be performed.

In addition, the above-mentioned example of the manufacturing method has been described using the Lamb wave type high-frequency device 110 of the third embodiment in which the space 154 is formed by the groove-shaped concave portion 153 , but it can also be applied to the pulley described in the first embodiment having the box-shaped concave portion 53 . M-wave type high-frequency device 10 (see FIG. 1 and FIG. 11 ).

Furthermore, it can also be applied to the Lamb wave type high-frequency device 210 described in Embodiment 4 (see FIG. 6 ) in which the concave portion 153 is provided on the quartz substrate 20 . In this case, an etching protection layer may be formed on the inner surface of the concave portion 123 .

Therefore, according to the above-mentioned manufacturing method 4, in the step of removing the sacrificial layer 156, the etching protection layer 156 is provided on the back surface of the quartz substrate 20 in contact with the sacrificial layer 156, thereby, as the sacrificial layer of the MEMS structure, a general quartz substrate is used. When SiO ₂ is used as the sacrificial layer, it is also possible to protect the quartz substrate 20 during the etching step of the sacrificial layer.

(manufacturing method 5)

Next, a manufacturing method 5 of a Lamb wave type high-frequency device according to the present invention will be described with reference to the drawings. This manufacturing method is a manufacturing method using a thermosetting resin as a sacrificial layer, and is a manufacturing method of a Lamb wave type high frequency device having the same structure as the Lamb wave type high frequency device 110 described in Embodiment 3 (see FIG. 5 ). . Therefore, differences will be mainly described, and FIG. 9 showing a method of manufacturing a Lamb wave-type high-frequency device according to Embodiment 3 will also be referred to.

FIG. 13 is a cross-sectional view showing main steps of the manufacturing method when a thermosetting resin is used as the sacrificial layer 130 according to the manufacturing method 5. As shown in FIG. First, as shown in FIG. 13( a ), the reinforcing substrate 150 formed with the concave portion 153 and the thick quartz substrate plate 20 a are joined to form a space 154 between the reinforcing substrate 150 and the thick quartz substrate plate 20 a.

Then, the reinforcing substrate 150 and the thick plate 20 a of the quartz substrate are inserted into the mounting jig 350 in a bonded state. Fig. 13 (b) is a sectional view showing a cut surface (cross section in the width direction) of the Lamb wave type high-frequency device 110 shown in Fig. 5 in a direction perpendicular to the propagation direction of the Lamb wave, and Fig. 13 (c) is top view. In Fig. 13(b) and (c), the reinforcement substrate 150 is formed as a thick plate 20a larger than the quartz substrate in the width direction, and protrudes to both sides in the width direction. The mounting jig 350 is formed to surround the outer periphery of the reinforcing substrate 150 with the edge portion 350a. Also, the edge portion 350 a protrudes from the upper surface of the reinforcing substrate 150 .

Openings 153 a , 153 b are formed between the thick plate 20 a of the quartz substrate and the edge 350 a of the mounting jig 350 in the state of being mounted on the mounting jig 350 . The openings 153a, 153b are provided in the direction of both ends perpendicular to the direction in which the IDT electrodes 30 and the reflectors 41, 42 are arranged in parallel (that is, the propagation direction of Lamb waves). A liquid thermosetting resin is injected from these openings 153 a and 153 b to fill the space 154 . As the thermosetting resin, phenolic resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, polyurethane resin, thermosetting polyamide resin, etc. can be used. And, the thermosetting resin is cured by heating to form the sacrificial layer 130 .

In addition, when injecting the thermosetting resin, if it is injected from one of the openings 153a and 153b and sucked from the other, air bubbles and the like will not remain inside the space 154 .

After the sacrificial layer 130 is formed, the slab 20a of the quartz substrate is ground to a predetermined thickness to form the IDT electrodes 30 and reflectors 41 and 42, and the sacrificial layer 130 is removed to form the Lamborghini high-frequency device 110. The steps after grinding are the same as those shown in Figs. 9(c) to (f), so illustration is omitted.

The sacrificial layer 130 can be removed by dipping into a solvent or the like through the openings 153a and 153b. Therefore, the size of the openings 153a and 153b may be suitably set to a size that allows the thermosetting resin to be easily injected and the solvent to be easily immersed. After the sacrificial layer 130 is removed, the Lamb wave type high-frequency device 110 can be easily detached from the mounting jig 350 .

And, also can be the step of forming IDT electrode 30 and reflector 41,42 after removing sacrificial layer 130, so also can be in the state that removes sacrificial layer 130 and unloads from mounting jig 350, forms IDT electrode 30 and reflector. Devices 41,42.

Therefore, according to manufacturing method 5, by using a thermosetting resin as the sacrificial layer 130, after the thick plate 20a of the quartz substrate and the reinforcing substrate 150 are bonded, the space 154 can be filled with the thermosetting resin, and the evaporation process for forming the sacrificial layer 130 is unnecessary. Expensive equipment such as plating equipment and CVD equipment.

In addition, since the surface of the sacrificial layer 154 is smoothed following the back surface of the quartz substrate 20, smoothing treatment such as CMP is unnecessary, and the manufacturing steps can be shortened. In addition, the openings 153a, 153b may be provided in the direction in which the IDT electrodes 30 and the reflectors 41, 42 are arranged in parallel.

(manufacturing method 6)

Next, a manufacturing method 6 of a Lamb wave type high-frequency device will be described with reference to the drawings. This manufacturing method 6 is a modified example of the aforementioned manufacturing method 5, and is a manufacturing method that uses a thermosetting resin as the sacrificial layer 130 and does not use a mounting jig.

14 shows manufacturing method 6, FIG. 14( a ) is a perspective view showing the state after the sacrificial layer 130 is formed, and FIG. 14( b ) is a cross-sectional view showing a C-C cross section in FIG. 14( a ). In FIGS. 14( a ) and ( b ), a box-shaped recess 155 is formed on the reinforcing substrate 150 .

The concave portion 155 is formed larger than both sides in the width direction of the thick plate 20a of the quartz substrate, and the periphery of the concave portion 155 is surrounded by four edge portions 151a to 151d. Therefore, openings 155a and 155b are formed on both sides in the width direction of the thick quartz substrate 20a in a state where the thick quartz substrate 20a and the reinforcing substrate 150 are bonded.

A filling liquid thermosetting resin is injected into the space 154 through the openings 155a and 155b. Then, it is cured by heating to form the sacrificial layer 130 . After the sacrificial layer 130 is formed, the slab 20a of the quartz substrate is ground to a predetermined thickness to form an IDT electrode and a reflector, and the sacrificial layer 130 is removed. Thus, the Lamb wave type high-frequency device 110 is formed.

The sacrificial layer 130 can be removed by dipping into a solvent or the like through the openings 153a and 153b. Therefore, the size (width) of the openings 153a and 153b may be appropriately set to a size that facilitates the injection of the thermosetting resin and facilitates the penetration of the solvent.

Therefore, according to the above-mentioned manufacturing method 6, when the thermosetting resin is filled into the space 154, the thermosetting resin can be sealed in the concave portion 155 of the reinforcing substrate 150 by using the edge portions 151a to 151d, so that there is no need for mounting jigs and the like, and the same effect as described above can be achieved. Manufacturing method 5 has the same effect. In addition, the openings 153a, 153b may be provided in the direction in which the IDT electrodes 30 and the reflectors 41, 42 are arranged in parallel.

(manufacturing method 7)

Next, a manufacturing method 7 of a Lamb wave type high-frequency device will be described with reference to the drawings. This manufacturing method is a modified example of the above-mentioned manufacturing method 6, and a box-shaped recess is formed on the reinforcing substrate. The form as a Lamb wave type high-frequency device is the same as that of the first embodiment, and it is characterized in that the sacrificial layer is made of a thermosetting resin for the manufacturing method shown in FIG. 11 . Just explain the differences.

FIG. 15 shows manufacturing method 7, and is a cross-sectional view showing a state in which a sacrificial layer 130 made of a thermosetting resin is formed. In FIG. 15 , a box-shaped recess 53 is formed on a reinforcing substrate 50 . The concave portion 53 forms a space 54 closed by the edge portion 51 in a state where the thick plate 20 a of the quartz substrate is joined.

Through-holes 57 and 58 for communicating the reinforcing substrate 50 with the inside and outside of the space 54 are provided on the bottom surface of the recess 53 . The liquid thermosetting resin is injected into the space 54 through one of the through hole 57 and the through hole 58, and the other is opened or sucked. After filling the space 54 with a thermosetting resin, it is heated and cured to form the sacrificial layer 130 . After the sacrificial layer 130 is formed, the slab 20a of the quartz substrate is sequentially ground to a predetermined thickness to form an IDT electrode and a reflector, and the sacrificial layer 130 is removed. Thus, a Lamb wave type high-frequency device is formed.

The sacrificial layer 130 is removed by using the through holes 57 and 58 provided in the reinforcing substrate 50 . After the sacrificial layer 56 is removed, although not shown, the space 54 communicates with the through-holes 57 and 58 .

In addition, in FIG. 15 , the structure in which two through-holes 57 and 58 are provided, but the number of through-holes is not limited to two, and may be one or more. Also, the shape of the through hole is not limited, and may be, for example, circular or quadrilateral.

Therefore, according to the above-mentioned manufacturing method 7, in addition to obtaining the same effect as the aforementioned manufacturing methods 5 and 6, the installation jig like the manufacturing method 5 is not required. In addition, since the planar shapes of the quartz substrate 20 and the reinforcing substrate 50 are identical, there is no need for an edge portion for enclosing the liquid thermosetting resin as in the manufacturing method 6 described above, so that miniaturization can be achieved.

Furthermore, after filling liquid or gas into the space 54, the through-holes 57 and 58 can be sealed. In this way, by making the interface on the rear surface of the quartz substrate 20 liquid or gas, it is possible to change the reflection state of the Lamb wave on the rear side, and to increase the selection of resonance modes.

In addition, the present invention is not limited to the foregoing embodiments, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

For example, in the configuration described in the foregoing embodiments, a quartz substrate was described as an example of a piezoelectric substrate, but lithium tantalate, lithium niobate, lithium tetraborate, langasite, langanite, niobate, etc. may also be used. Piezoelectric substrates such as potassium, and other non-piezoelectric substrates.

In addition, according to the above-mentioned manufacturing method for forming a sacrificial layer, as a piezoelectric substrate, piezoelectric thin films such as zinc oxide, aluminum nitride, and tantalum pentoxide, cadmium sulfide, zinc sulfide, gallium arsenide, indium antimonide, etc. piezoelectric semiconductors.

In addition, in the foregoing embodiments, a 1-port resonator was described as an example of a Lamb wave type high-frequency device, but it can also be applied to a 2-port resonator or a filter including an IDT electrode and a reflector.

Therefore, according to the present invention, it is possible to provide a Lamb wave-type high-frequency device with improved mechanical strength and stable characteristics, and a manufacturing method that is less likely to be broken during the manufacturing process and has improved yield.

Claims (9)

1. a Lamb wave formula high-frequency apparatus is characterized in that,

This Lamb wave formula high-frequency apparatus is by constituting at the reinforcement substrate that is formed with the piezoelectric substrate of IDT electrode on the interarea and be bonded on another interarea of described piezoelectric substrate,

Be provided with the space of area greater than the transmission region of Lamb wave on described piezoelectric substrate or described reinforcement substrate, the periphery in described space is provided with the composition surface,

Described space is formed by the recess of the groove shape on the either party who is located at described reinforcement substrate or described piezoelectric substrate, and wherein, described groove is at opposed a pair of lateral opening.

2. Lamb wave according to claim 1 formula high-frequency apparatus is characterized in that described piezoelectric substrate is made of quartz base plate.

3. the manufacture method of a Lamb wave formula high-frequency apparatus, this Lamb wave formula high-frequency apparatus is by constituting at the reinforcement substrate that is formed with the piezoelectric substrate of IDT electrode on the interarea and be bonded on another interarea of described piezoelectric substrate, on described piezoelectric substrate or described reinforcement substrate, be provided with the space of area greater than the transmission region of Lamb wave, periphery in described space is provided with the composition surface, it is characterized in that this manufacture method comprises following step:

The step that groove on the either party of the slab of described piezoelectric substrate or described reinforcement substrate forms the recess that is equivalent to described space is located in utilization, and wherein, described groove is at opposed a pair of lateral opening;

In described recess, form the step of sacrifice layer;

Engage the engagement step of the slab and the described reinforcement substrate of described piezoelectric substrate;

After engagement step, it is the grinding steps of specific thickness that the slab of described piezoelectric substrate is ground;

After grinding steps, form the step of IDT electrode; With

Remove the step of described sacrifice layer.

4. the manufacture method of Lamb wave according to claim 3 formula high-frequency apparatus is characterized in that described piezoelectric substrate is made of quartz base plate, and utilizes its etching solution material different with the etching solution of described piezoelectric substrate to form described sacrifice layer.

5. the manufacture method of Lamb wave according to claim 3 formula high-frequency apparatus is characterized in that described piezoelectric substrate is made of quartz base plate,

This manufacture method may further comprise the steps:

On another interarea of described piezoelectric substrate, form the step of etch protection layer;

Utilize SiO ₂Form the step of described sacrifice layer; With

After removing the step of described sacrifice layer, remove the step of described etch protection layer in greater than the scope of the transmission region of Lamb wave at area.

6. the manufacture method of a Lamb wave formula high-frequency apparatus, this Lamb wave formula high-frequency apparatus is by constituting at the reinforcement substrate that is formed with the piezoelectric substrate of IDT electrode on the interarea and be bonded on another interarea of described piezoelectric substrate, on described piezoelectric substrate or described reinforcement substrate, be provided with the space of area greater than the transmission region of Lamb wave, periphery in described space is provided with the composition surface, it is characterized in that this manufacture method comprises following step:

On described reinforcement substrate, form the step of the case shape recess that is equivalent to described space;

The step of through hole is set in the bottom surface of described recess;

In described recess, form the step of sacrifice layer;

Engage the engagement step of the slab and the described reinforcement substrate of described piezoelectric substrate;

After engagement step, it is the grinding steps of specific thickness that the slab of described piezoelectric substrate is ground;

After grinding steps, form the step of IDT electrode; With

Remove the step of described sacrifice layer.

7. the manufacture method of Lamb wave according to claim 6 formula high-frequency apparatus is characterized in that described piezoelectric substrate is made of quartz base plate, and utilizes its etching solution material different with the etching solution of described piezoelectric substrate to form described sacrifice layer.

8. the manufacture method of Lamb wave according to claim 6 formula high-frequency apparatus is characterized in that described piezoelectric substrate is made of quartz base plate,

This manufacture method may further comprise the steps:

On another interarea of described piezoelectric substrate, form the step of etch protection layer;

Utilize SiO ₂Form the step of described sacrifice layer; With

After removing the step of described sacrifice layer, remove the step of described etch protection layer in greater than the scope of the transmission region of Lamb wave at area.

9. the manufacture method of a Lamb wave formula high-frequency apparatus, this Lamb wave formula high-frequency apparatus is by constituting at the reinforcement substrate that is formed with the piezoelectric substrate of IDT electrode on the interarea and be bonded on another interarea of described piezoelectric substrate, on described piezoelectric substrate or described reinforcement substrate, be provided with the space of area greater than the transmission region of Lamb wave, periphery in described space is provided with the composition surface, it is characterized in that this manufacture method comprises following step:

On the either party of the slab of described piezoelectric substrate or described reinforcement substrate, form the step of the recess that is equivalent to described space;

Engage the engagement step of the slab and the described reinforcement substrate of described piezoelectric substrate;

After described engagement step, fill the sacrifice layer that constitutes by thermosetting resin and make its step of curing to described space;

After described sacrifice layer was solidified, it was the grinding steps of specific thickness that the slab of described piezoelectric substrate is ground;

After grinding steps, form the step of IDT electrode; With

Remove the step of described sacrifice layer.

Images