JP2007318712A - Device including piezoelectric thin film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device including a piezoelectric thin film capable of suppressing a spurious radiation by preventing the occurrence of unnecessary vibration in a lateral mode, and capable of avoiding degradation of reliability by stress concentration. <P>SOLUTION: An acoustic resonator according to the present invention includes a substrate 105, a support section 104 provided on the substrate 105, a lower electrode 103 provided on the support section 104, a piezoelectric body 101 provided on the lower electrode 103, and an upper electrode 102 provided on the piezoelectric body 101. The lower electrode 103, the piezoelectric body 101 and the upper electrode 102 form a vibration section 107. The support section 104 for supporting the vibration section 107 is shaped such that at least one portion of a vertical cross-section thereof has a curvature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a device having a piezoelectric thin film and a manufacturing method thereof, and more specifically to an acoustic resonator and a micromachine switch used in a high-frequency circuit of a mobile communication terminal such as a mobile phone or a wireless LAN, and a manufacturing method thereof. .

  Components incorporated in electronic devices such as portable devices are required to be small, light, low loss, and highly reliable. Many devices having a piezoelectric thin film have been proposed as devices that meet such requirements. Examples of devices that can be expected to be small, lightweight, and have low loss characteristics include a filter using an acoustic resonator and a micromachine switch.

  FIG. 13A is an example of a cross-sectional view of a conventional acoustic resonator (see, for example, Patent Document 1). This conventional acoustic resonator has a structure in which a vibrating portion in which a piezoelectric body 1 is sandwiched between an upper electrode 2 and a lower electrode 3 is placed on a substrate 5. A cavity 4 is formed in the substrate 5 by partially etching from the back surface using a fine processing method.

  The acoustic resonator generates vibration in the thickness direction by applying an electric field in the thickness direction of the piezoelectric body 1 by the upper electrode 2 and the lower electrode 3. Hereinafter, with reference to FIG. 13B to FIG. 13D, the operation of the acoustic resonator when the thickness longitudinal vibration of the infinite flat plate is used will be described. FIG. 13B is a schematic perspective view for explaining the operation of the acoustic resonator. FIG. 13C is a diagram illustrating frequency characteristics of admittance of the acoustic resonator. FIG. 13D is an equivalent circuit diagram of the acoustic resonator.

  When an electric field is applied between the upper electrode 2 and the lower electrode 3, electrical energy is converted into mechanical energy by the piezoelectric body 1. The induced mechanical vibration is a thickness direction stretching vibration, and expands and contracts in the same direction as the electric field. The acoustic resonator uses resonance vibration in the thickness direction of the piezoelectric body 1 and operates at resonance at a frequency at which the thickness becomes equal to ½ wavelength. Thickness longitudinal vibration of the piezoelectric body 1 is ensured by the cavity 4. As shown in FIG. 13D, an equivalent circuit of the acoustic resonator is expressed by a configuration in which a series resonance unit including a capacitor C1, an inductor L1, and a resistor R1 is connected to a capacitor C0 in parallel with the series resonance unit. Therefore, the admittance of the acoustic resonator is maximized at the resonance frequency fr and minimized at the antiresonance frequency fa. Here, fr = 1 / {2π · √ (L1 · C1)} and fa = fr · √ (1 + C1 / C0).

  FIG. 14 is an example of a perspective view of a conventional micromachine switch using the piezoelectric effect (see, for example, Patent Document 2). This conventional micromachine switch is a signal line conductor 12 formed on a substrate 11, a drive short-circuit mechanism 15 that blocks the passage of high-frequency signals, and a drive means that displaces the drive short-circuit mechanism 15 by giving a control signal. It is comprised with the piezoelectric material 16.

In FIG. 14, when the signal is interrupted, a voltage is applied as a control signal to the piezoelectric body 16 so that the signal line conductor 12 and the ground conductor 13 are in contact with the conductive layer 17 on the bottom surface of the drive short-circuit mechanism 15. When passing a signal, no voltage is applied to the piezoelectric body 16.
JP-A-60-68711 JP 2003-217421 A JP 2000-332568 A JP 2005-45694 A

  However, the conventional acoustic resonator has not only a vibration mode in the thickness direction (longitudinal mode) but also a vibration mode (transverse mode) that actually propagates in a plane parallel to the electrode. In the acoustic resonator, a part of the vibration part is fixed to the substrate 5. Therefore, the vibration propagated parallel to the electrode surface is reflected at a fixed position and becomes unnecessary vibration. This unnecessary vibration causes spurious frequency characteristics.

  As a method for avoiding spurious due to the transverse mode, a method has been proposed in which the cavity shape of the acoustic resonator is polygonal as shown in FIG. 15 (see, for example, Patent Document 3). By making the cavity shape of the acoustic resonator a polygonal structure, when transverse mode vibration is reflected at a fixed position, it propagates in a direction different from the incident direction, thereby reducing spurious. That is, the spurious is prevented from appearing in the frequency band of the vibration mode in the thickness direction of the acoustic resonator.

  However, in this method, in addition to the necessity to design the electrode structure and the cavity structure for each acoustic resonator, there is a problem that a redesign is required every time the frequency or the impedance of the transmission line is changed. ing.

  Moreover, since the conventional acoustic resonator has a structure in which local stress is concentrated on the piezoelectric thin film, problems such as film peeling and cracks occur during the manufacturing process.

  As a method for avoiding this problem, as shown in FIG. 16, at the step portion of the interface between the piezoelectric film 32 and the lower electrode 31 corresponding to the end shape of the gap V, the interface between the piezoelectric film 32 and the lower electrode 31 is A plurality of surfaces that are non-parallel to the surface of the substrate 30 and have different angles (α, β, γ) with the surface of the substrate 30 are stacked from the substrate 30 side to the top of the gap V. A structure of an acoustic resonator is disclosed (for example, see Patent Document 4). By adopting this structure (air bridge type), local stress is prevented from concentrating on the piezoelectric film 32.

  However, in this method, the shape of the support layer 40 is complicated because a plurality of angles formed by the interface between the piezoelectric film 32 and the lower electrode 31 and the substrate exist. Therefore, although stress relaxation is possible, there are problems such as a complicated manufacturing method.

  On the other hand, in the conventional micromachine switch, since the connection point between the drive short-circuit mechanism 15 and the support portion 9 is vertical, stress concentration occurs at the connection point when mechanically displaced, resulting in mechanical reliability. There was a problem that the deterioration of sex occurred.

Therefore, an object of the present invention is to provide a device having a piezoelectric thin film that can suppress the occurrence of unnecessary vibration due to the transverse mode and suppress spurious vibrations, and avoids a decrease in reliability due to stress concentration.
Furthermore, the objective of this invention is providing the manufacturing method effective in order to implement | achieve the device.

  The present invention is directed to an acoustic resonator that vibrates at a predetermined frequency and a micromachine switch that uses a piezoelectric effect and an electrostatic effect. In order to achieve the above object, an acoustic resonator according to the present invention includes a substrate, a piezoelectric body made of a piezoelectric thin film, an upper electrode sandwiching the piezoelectric body, and a vibrating section composed of a lower electrode, and a vibrating section. And a support portion that is provided between the substrate and the substrate and has a curvature at least at one point in the vertical cross section. The micromachine switch of the present invention includes a substrate, a driving electrode provided on the substrate, a piezoelectric body made of a piezoelectric thin film, an upper electrode, a lower electrode, and a signal line movable electrode sandwiching the piezoelectric body. And a support portion that is provided between the movable portion and the substrate and has a curvature at least at one location in the vertical cross section.

  It is preferable that the support portion has a vertical cross-sectional shape in which the width becomes narrowest or widest near the center portion in the thickness direction. Further, it is preferable that the support portion has a vertical cross-sectional shape in which a surface in contact with the substrate and a surface in contact with the lower electrode are parallel.

  The acoustic resonator and the micromachine switch of the present invention described above function alone, but may be configured as a composite device, a filter, a duplexer, and a communication device including a plurality of acoustic resonators and / or micromachine switches.

  The acoustic resonator and the micromachine switch having the above structure include a step of forming a piezoelectric body on a first substrate, a step of forming a lower electrode on one main surface of the piezoelectric body, and a first support member on the lower electrode. Forming the second support member on the second substrate, bonding the first support member and the second support member, and the first step after the bonding step It is manufactured by separating the substrate and transferring the piezoelectric body on which the lower electrode is formed from the first substrate to the second substrate, and forming the upper electrode on the other main surface of the piezoelectric body. .

  Typically, the bonding step is performed by eutectic crystal bonding of the first support member and the second support member. In this case, it is desirable that the first support member and the second support member are multilayer films containing at least gold tin (AuSn) or gold silicon (AuSi). The first support member and the second support member may be formed with different widths or thicknesses.

  According to the present invention, the support portion functions as a structure having a plurality of resonance frequencies, and unnecessary vibrations caused by vibration leakage are dispersed (damped). Thereby, an admittance curve without spurious can be obtained between the resonance frequency and the anti-resonance frequency of the vibration part.

(Structural example of acoustic resonator)
FIG. 1 is a cross-sectional view schematically showing the structure of an acoustic resonator according to an embodiment of the present invention. The acoustic resonator shown in FIG. 1 includes a substrate 105, a support portion 104 formed on the substrate 105, a lower electrode 103 formed on the support portion 104, and a piezoelectric body formed on the lower electrode 103. 101 and an upper electrode 102 formed on the piezoelectric body 101. The lower electrode 103, the piezoelectric body 101, and the upper electrode 102 constitute a vibration unit 107. A region surrounded by the substrate 105, the support portion 104, and the lower electrode 103 functions as a cavity 106. The cavity 106 is a space provided so that the vibration unit 107 does not hinder excitation of longitudinal vibration in the thickness direction.

  The piezoelectric body 101 includes aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT) based material, lithium niobate (LiNbO3), lithium tantalate (LiTaO3), or potassium niobate (KNbO3). A piezoelectric material such as is used. For the upper electrode 102 and the lower electrode 103, a conductive material such as molybdenum (Mo), aluminum (Al), tungsten (W), platinum (Pt), gold (Au), titanium (Ti), or copper (Cu). Alternatively, a laminated metal or alloy thereof is used. For the substrate 105, silicon (Si), gallium arsenide (GaAs), SiC, or the like is used.

  A feature of the acoustic resonator of the present invention is that the support portion 104 that supports the vibration portion 107 is formed so that at least one portion of the vertical cross section has a curvature. The surface in contact with the substrate 105 and the surface in contact with the lower electrode 103 are preferably parallel. For example, as shown in FIG. 1, the width near the center of the support portion 104 is narrow. The reason why the support portion 104 is formed in such a vertical cross-sectional shape is that unnecessary vibration that causes spurious vibrations is not generated near the resonance frequency. The reason is considered as follows.

As described in the above description of the prior art, unnecessary vibration occurs because vibration leakage occurs in the substrate at the fixed portion. Therefore, when the resonance frequency of the support unit 104 is close to the resonance frequency of the vibration unit 107, the vibration excited by the vibration unit 107 leaks to the substrate 105 through the support unit 104 and is excited as unnecessary vibration. Since the vertical cross-sectional shape of the support portion of the conventional acoustic resonator is a shape that does not have a curvature such as a square or a trapezoid, the support portion has a single resonance frequency and a large unnecessary vibration occurs.
Therefore, in the present invention, the support section 104 is made to function as a structure having a plurality of resonance frequencies by giving a curvature to the vertical cross-sectional shape of the support section 104, thereby dispersing (attenuating) unnecessary vibration caused by vibration leakage. I did that. As a result, an admittance curve without spurious was obtained between the resonance frequency and the anti-resonance frequency (see FIG. 4A described later).

  Note that the acoustic resonator of the present invention can exhibit the above-described effect if the support portion 104 is formed so that at least one portion of the vertical cross section has a curvature. Therefore, the shape of the support portion 104 is not limited to the example shown in FIG. 1, and for example, the shapes shown in FIGS. 2A to 2F are also conceivable. Moreover, the support part 104 may be comprised with one annular structure, and may be comprised with the some columnar structure.

(Production example of acoustic resonator)
3A and 3B are diagrams schematically showing a procedure of a preferable manufacturing method of the acoustic resonator having the above structure. In this manufacturing method, the acoustic resonator shown in FIG. 1 is manufactured by using a bonding method.

  First, a film formation substrate 108 made of silicon, glass, sapphire, or the like is prepared, and a piezoelectric body 101 is formed on the film formation substrate 108 (FIG. 3A, step a). Next, the lower electrode 103 is formed on the piezoelectric body 101 by film formation and patterning (FIG. 3A, step b). Next, a support member 104a that becomes a part of the support portion 104 is formed on the lower electrode 103 (FIG. 3A, step c). Next, a substrate 105 that supports the vibration unit 107 is prepared, and a support member 104b that is a part of the support unit 104 is formed on the substrate 105 (FIG. 3A, step d). Materials such as gold and tin are used for the support members 104a and 104b.

  Next, the supporting member 104a of the film-forming substrate 108 and the supporting member 104b of the substrate 105 are faced to each other, and gold and tin are bonded together by eutectic crystal (FIG. 3A, step e). For example, once the gold tin is melted at 375 ° C. and 0.3 MPa and then solidified again, the support portion 104 having a structure that cannot be obtained by etching can be easily realized (FIG. 3B, step f). Next, the film-forming substrate 108 is removed from the formed product obtained by bonding the two substrates (FIG. 3B, step g). For example, the deposition substrate 108 can be removed by wet etching or dry etching. Through these steps e to g, the formed material originally on the film formation substrate 108 is transferred to the substrate 105. Next, the upper electrode 102 is formed on the piezoelectric body 101 by film formation and patterning (FIG. 3B, step h). Finally, unnecessary portions of the piezoelectric body 101 are removed by etching (FIG. 3B, step i), thereby completing the acoustic resonator shown in FIG.

  According to the manufacturing method of the present invention, by using gold tin as the material of the support portion 104 and using a simple bonding method of eutectic crystal that is once melted and then solidified, the shape of the support portion 104 (the cavity 106 The shape) is a complicated shape having a curvature in a vertical section that cannot be obtained by etching or the like.

  FIG. 4A shows the frequency characteristics of the acoustic resonator manufactured by the manufacturing method of the present invention, and FIG. 4B shows the conventional manufacturing method (for example, the materials are stacked in the upward direction from the substrate, and the cavity removes the sacrificial layer. The frequency characteristics of the acoustic resonator manufactured by the above method are shown. As can be seen from FIGS. 4A and 4B, the spurious generated near the resonance frequency in the conventional acoustic resonator is not generated in the acoustic resonator of the present invention.

  In the present embodiment, an example in which eutectic crystal is performed using gold tin as the material of the support portion 104 has been described. However, other materials can be used as long as they are materials capable of eutectic crystal bonding (for example, gold and silicon). It is also possible to use it. By using materials with different melting properties, it is possible to easily form a support portion having a curved section. Further, at least one of the supporting members 104a and 104b may be a gold-tin material, and may be formed of a multilayer film containing a gold-tin material. Further, the thickness and width of the support members 104a and 104b can be freely set.

  In this embodiment, the piezoelectric body 101 is directly formed on the film formation substrate 108, but another film may be formed between the film formation substrate 108 and the piezoelectric body 101. For example, when the AlN piezoelectric body 101 is formed on the film formation substrate 108, AlN is formed on the film formation substrate 108, Mo is formed thereon, and finally the piezoelectric body 101 is formed. For example, it is possible to obtain an effect that the piezoelectric body 101 is not directly damaged by the removal of the film formation substrate 108.

(Example of micromachine switch structure)
5A and 5B are a perspective view and a cross-sectional view schematically showing the structure of a micromachine switch according to an embodiment of the present invention. The micromachine switch in FIGS. 5A and 5B is formed on the substrate 205, the support portion 204 formed on the substrate 205, the lower electrode 203 formed on the support portion 204, and the lower electrode 203. The piezoelectric body 201, the upper electrode 202 formed on the piezoelectric body 201, the signal line movable electrode 207 formed on the same main surface as the lower electrode 203 of the piezoelectric body 201, and the substrate 205 are formed. Drive electrode 206. The lower electrode 203, the piezoelectric body 201, and the upper electrode 202 constitute the movable part 200. For the piezoelectric body 201, the upper electrode 202, the lower electrode 203, and the substrate 205, the same materials as those described for the acoustic resonator can be used. On the substrate 205, two signal line fixed electrodes 208 and 209 are formed at positions where they are brought into conduction by contact with the signal line movable electrode 207.

  A feature of the micromachine switch of the present invention is that the support portion 204 that supports the movable portion 200 is formed so that at least one portion of the vertical section has a curvature. The surface in contact with the substrate 205 and the surface in contact with the lower electrode 203 are preferably parallel. For example, as illustrated in FIG. 5B, the width near the center of the support portion 204 is narrow. The reason why the support portion 204 is formed in such a vertical cross-sectional shape is that stress concentration on the portion connecting the movable portion 200 and the support portion 204 during the switching operation can be reduced. The reason is considered as follows.

The movable part 200 is displaced in the direction of the substrate 205 by a switching operation. At this time, since the support part 204 is being fixed, it does not move. Therefore, since the movable part 200 is supported and fixed by the support part 204, stress concentration occurs near the connection part.
Therefore, in the present invention, by providing the vertical cross-sectional shape of the support portion 204 with a curvature, the stress is dispersed without being concentrated on the connection portion between the movable portion 200 and the support portion 204. As a result, the maximum distortion during switching can be reduced, and the mechanical reliability can be improved. In addition, since the upper surface of the support portion 204 is disposed in parallel with the substrate 205, the initial stress can be reduced, and the maximum strain can be reduced.

  Note that the micromachine switch of the present invention can exhibit the above-described effects if the support portion 204 is formed so that at least one portion of the vertical cross section has a curvature. Therefore, the shape of the support portion 204 is not limited to the example of the cantilever shape in which the support portion of the movable portion 200 shown in FIGS. 5A and 5B is one side, and other shapes can be considered.

  For example, FIG. 6A is a diagram of a micromachine switch having a doubly-supported beam shape in which both support portions of the movable part are supported. FIG. 6B is a diagram illustrating an example in which micromachine switches having a cantilever shape are connected in a U-shape. FIG. 6C is a diagram of a micromachine switch having a structure in which the thicknesses of the upper electrode and the lower electrode are the same using a plurality of piezoelectric thin films. FIG. 6D is a diagram of a micromachine switch having a structure in which the support portion has a layer structure of a plurality of materials. The number of contact points of the switch may be one or plural. Moreover, you may comprise a support part with an electroconductive material and it may utilize as wiring.

  FIG. 6E is a diagram of a micromachine switch in which a switch unit and a variable capacitor unit are configured together. FIG. 6F is an equivalent circuit of the micromachine switch of FIG. 6E. This micromachine switch has a structure in which a gap is generated below the variable capacitance section 252 even when the switch section 251 is turned ON and the signal line movable electrode and the signal line fixed electrode come into contact with each other. And this micromachine switch changes the capacitance value of the variable capacity | capacitance part 252 by changing the voltage applied to each electrode, and changing a gap width, as shown to FIG. 6G.

(Manufacturing example of micromachine switch)
7A and 7B are diagrams schematically showing a procedure of a preferable manufacturing method of the micromachine switch having the above structure. In this manufacturing method, the micromachine switch shown in FIG. 5B is manufactured by using a bonding method.

  First, a deposition substrate 108 made of silicon, glass, sapphire, or the like is prepared, and a piezoelectric body 201 is formed on the deposition substrate 108 (FIG. 7A, step a). Next, the lower electrode 203 and the signal line movable electrode 207 are formed on the piezoelectric body 201 by film formation and patterning (FIG. 7A, step b). Next, a support member 204a to be a part of the support portion 204 is formed on the lower electrode 203 (FIG. 7A, step c). Next, a substrate 205 that supports the movable portion 200 is prepared, and a support member 204b, a drive electrode 206, and signal line fixed electrodes 208 and 209 (not shown) that are a part of the support portion 204 are attached to the substrate 205. Form on top (FIG. 7A, step d). Materials such as gold and tin are used for the support members 204a and 204b.

  Next, the supporting member 204a of the film-forming substrate 108 and the supporting member 204b of the substrate 205 are faced to each other, and gold and tin are bonded together by eutectic crystal (FIG. 7A, step e). For example, once the gold tin is melted at 375 ° C. and 0.3 MPa and then solidified again, the support portion 204 having a structure that cannot be obtained by etching can be easily realized (FIG. 7B, step f). Next, the film-forming substrate 108 is removed from the formed product obtained by bonding the two substrates (FIG. 7B, step g). For example, the deposition substrate 108 can be removed by wet etching or dry etching. Through these steps e to g, the formed material originally on the film formation substrate 108 is transferred to the substrate 205. Next, the upper electrode 202 is formed on the piezoelectric body 201 by film formation and patterning (FIG. 7B, step h). Finally, unnecessary portions of the piezoelectric body 201 are removed by etching (FIG. 7B, step i) to complete the micromachine switch shown in FIG. 5B.

  According to the manufacturing method of the present invention, the shape of the support portion 204 can be etched by using a simple joining method of eutectic crystal that is once melted and then solidified using gold tin as the material of the support portion 204. In such a case, a vertical section that cannot be obtained has a complicated shape having a curvature.

(Example of micromachine switch drive circuit)
FIG. 8A shows an example of a drive circuit for the micromachine switch described above. FIG. 8B is a diagram showing an operation example of the drive circuit for the micromachine switch shown in FIG. 8A. In this drive circuit, a micromachine switch is inserted between the connection point of switching elements A and B connected in series and the connection point of switching elements C and D connected in series (the upper electrode 202 of the micromachine switch and The lower electrode 203 is connected to each other).

State (1) in FIG. 8B: When the switching element A is in the ON state (switching element B is in the OFF state), the power supply voltage Vd is applied to the V1 terminal. At this time, since the switching element C is in the OFF state (the switching element D is in the ON state), the V2 terminal is at the GND potential. As a result, the voltage Vd is applied to the micromachine switch.
State (2) in FIG. 8B: When the switching element A is in the ON state (switching element B is in the OFF state), the power supply voltage Vd is applied to the V1 terminal. At this time, since the switching element C is in the ON state (the switching element D is in the OFF state), the potential at the V2 terminal is also the voltage Vd. As a result, a voltage of 0 V is applied to the micromachine switch.

State (3) in FIG. 8B: When the switching element A is in the OFF state (switching element B is in the ON state), the V1 terminal is at the GND potential. At this time, since the switching element C is in the ON state (the switching element D is in the OFF state), the potential at the V2 terminal is the voltage Vd. As a result, the voltage −Vd is applied to the micromachine switch.
State (4) in FIG. 8B: When the switching element A is in the OFF state (switching element B is in the ON state), the V1 terminal is at the GND potential. At this time, since the switching element C is in the OFF state (the switching element D is in the ON state), the V2 terminal is at the GND potential. As a result, a voltage of 0 V is applied to the micromachine switch.

  Thus, by driving, a voltage of ± Vd with respect to the power supply voltage Vd can be applied to the micromachine switch, and displacement due to the piezoelectric effect can be performed in both cases of ON / OFF. Therefore, the operation can be performed at a higher speed than the operation in the driving voltage range of 0 to Vd.

(Example of configuration using acoustic resonator)
FIG. 9 is a diagram showing a circuit example of a ladder type filter using the acoustic resonator of the present invention. The ladder type filter shown in FIG. 9 includes a series acoustic resonator 302 inserted in series between the input / output terminals 301 and a parallel acoustic resonator 303 inserted in parallel. By setting the resonance frequency of the series acoustic resonator 302 to be higher than the resonance frequency of the parallel acoustic resonator 303, a ladder filter having bandpass characteristics can be realized. Preferably, by making the resonance frequency of the acoustic resonator 302 substantially coincide with the anti-resonance frequency of the acoustic resonator 303, it is possible to realize a ladder filter that is more excellent in passband flatness. Further, by using the above-described acoustic resonator of the present invention, energy can be concentrated only on desired vibration, and a ladder type filter with little loss can be realized.

  FIG. 10 is a diagram showing a circuit example (ladder-type filter switching circuit) of a composite device using the acoustic resonator and the micromachine switch of the present invention. The ladder type filter shown in FIG. 10 has a configuration in which the ladder type filter shown in FIG.

  Note that the number of connection stages of the ladder filter is not limited to the one and two stages shown in FIGS. 9 and 10, and may be a multistage structure. Further, the ladder configuration is not limited to the L type, and other configurations such as a T type and a π type can be used. Furthermore, the same effect can be obtained even if a lattice type filter is configured in addition to the ladder type.

  FIG. 11 is a diagram illustrating an example of the duplexer 410 using the ladder filter as described above. In the duplexer 410 illustrated in FIG. 11, a transmission filter 414, a phase shift circuit 415, and a reception filter 416 are directly connected between the transmission terminal 411 and the reception terminal 412 in order, and the transmission filter 414 and the phase shift circuit 415 are connected to each other. An antenna terminal 413 is connected between them. The ladder filter is used for at least one of the transmission filter 414 and the reception filter 416. With this configuration, a low-loss duplexer can be realized.

  FIG. 12 is a diagram illustrating an example of the communication device 420 using the duplexer as described above. In the communication device 420 illustrated in FIG. 12, a signal input from the transmission terminal 421 passes through the baseband unit 423, is amplified by the power amplifier (PA) 424, is filtered by the transmission filter 425, and is transmitted as a radio wave from the antenna 428. The A signal received by the antenna 428 is filtered by the reception filter 426, amplified by the LNA 427, passed through the baseband unit 423, and transmitted to the reception terminal 422. The ladder filter is used for at least one of the transmission filter 425 and the reception filter 426. With this configuration, the communication device 420 with low loss and low power consumption can be realized.

  The acoustic resonator and the micromachine switch of the present invention can be used for a high-frequency circuit of a mobile communication terminal such as a mobile phone or a wireless LAN.

Sectional drawing which showed typically the structure of the acoustic resonator which concerns on one Embodiment of this invention Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically Sectional drawing which showed the structure of the other acoustic resonator which concerns on one Embodiment of this invention typically The figure which showed schematically the procedure of the manufacturing method of the acoustic resonator of FIG. The figure which showed schematically the procedure of the manufacturing method of the acoustic resonator of FIG. The figure which shows the frequency characteristic of the acoustic resonator which concerns on one Embodiment of this invention. The figure which shows the frequency characteristic of the conventional acoustic resonator The perspective view which showed typically the structure of the micromachine switch which concerns on one Embodiment of this invention Sectional drawing which showed typically the structure of the micromachine switch which concerns on one Embodiment of this invention Sectional drawing which showed typically the structure of the other micromachine switch concerning one Embodiment of this invention The perspective view which showed typically the structure of the other micromachine switch which concerns on one Embodiment of this invention. Sectional drawing which showed typically the structure of the other micromachine switch concerning one Embodiment of this invention Sectional drawing which showed typically the structure of the other micromachine switch concerning one Embodiment of this invention The perspective view which showed typically the structure of the other micromachine switch which concerns on one Embodiment of this invention. 6E equivalent circuit diagram of the micromachine switch of FIG. The figure which showed the operation example of the micromachine switch of FIG. 6E The figure which showed roughly the procedure of the manufacturing method of the micromachine switch of FIG. 5B. The figure which showed roughly the procedure of the manufacturing method of the micromachine switch of FIG. 5B. Diagram showing an example of a drive circuit for a micromachine switch The figure which shows the operation example of the drive circuit of the micromachine switch shown to FIG. 8A The figure which shows the circuit example of the ladder type filter using the acoustic resonator of this invention The figure which shows the circuit example of the ladder type filter using the acoustic resonator and micromachine switch of this invention The figure which shows the example of the duplexer using the ladder type filter The figure which shows the example of the communication equipment which uses the duplexer The figure for demonstrating the conventional acoustic resonator The figure for demonstrating the conventional acoustic resonator The figure for demonstrating the conventional acoustic resonator The figure for demonstrating the conventional acoustic resonator A perspective view for explaining a conventional micromachine switch The figure which shows the example of the cavity used for the conventional acoustic resonator The figure for demonstrating the other conventional acoustic resonator

Explanation of symbols

101, 201 Piezoelectric bodies 102, 103, 202, 203, 206 to 209 Electrodes 104, 204 Support sections 104a, 104b Support members 105, 205 Substrate 106 Cavity 107 Vibration section 108 Film-forming substrate 200 Movable section 251 Switch section 252 Variable capacitance Sections 302 and 303 Acoustic resonator 314 Micromachine switch 410 Duplexer 414 and 425 Transmission filter 415 Phase shift circuit 416 and 426 Reception filter 423 Baseband section 424 Power amplifier (PA)
427 LNA
428 antenna

Claims (17)

An acoustic resonator that vibrates at a predetermined frequency,
A substrate,
A piezoelectric body made of a piezoelectric thin film, an upper electrode sandwiching the piezoelectric body, and a vibrating section composed of a lower electrode;
An acoustic resonator comprising: a support portion that is provided between the vibrating portion and the substrate and has a shape in which at least one portion of a vertical cross section has a curvature.   2. The acoustic resonator according to claim 1, wherein the support portion has a vertical cross-sectional shape having a narrowest width near a central portion in a thickness direction.   2. The acoustic resonator according to claim 1, wherein the support portion has a vertical cross-sectional shape having a widest width near a central portion in a thickness direction.   The acoustic resonator according to claim 1, wherein the support portion has a vertical cross-sectional shape in which a surface in contact with the substrate and a surface in contact with the lower electrode are parallel to each other. A micromachine switch using a piezoelectric effect and an electrostatic effect,
A substrate,
A driving electrode provided on the substrate;
A movable portion composed of a piezoelectric body made of a piezoelectric thin film, an upper electrode sandwiching the piezoelectric body, a lower electrode, and a signal line movable electrode;
A micromachine switch comprising: a support portion provided between the movable portion and the substrate and having a shape in which at least one portion of a vertical cross section has a curvature.   6. The micromachine switch according to claim 5, wherein the support portion has a vertical cross-sectional shape having a narrowest width near a central portion in a thickness direction.   The micromachine switch according to claim 5, wherein the support portion has a vertical cross-sectional shape that is widest near a central portion in a thickness direction.   The micromachine switch according to claim 5, wherein the support portion has a vertical cross-sectional shape in which a surface in contact with the substrate and a surface in contact with the lower electrode are parallel to each other.   A composite device comprising a plurality of acoustic resonators and a micromachine switch, comprising: at least one acoustic resonator according to claim 1; and at least one micromachine switch according to claim 5.   A filter comprising at least one acoustic resonator according to claim 1.   A duplexer comprising at least one composite device according to claim 9.   A communication device comprising at least one duplexer according to claim 11. A method for manufacturing a device having a piezoelectric thin film,
Forming a piezoelectric body on the first substrate;
Forming a lower electrode on one main surface of the piezoelectric body;
Forming a first support member on the lower electrode;
Forming a second support member on the second substrate;
Bonding the first support member and the second support member;
Separating the first substrate after the bonding step, and transferring the piezoelectric body on which the lower electrode is formed from the first substrate to the second substrate;
Forming an upper electrode on the other main surface of the piezoelectric body.   The manufacturing method according to claim 13, wherein the bonding step is performed by eutectic crystal bonding of the first support member and the second support member.   The manufacturing method according to claim 13, wherein the first support member and the second support member are multilayer films containing at least gold tin (AuSn) or gold silicon (AuSi).   The manufacturing method according to claim 13, wherein the first support member and the second support member are formed with different widths.   The manufacturing method according to claim 13, wherein the first support member and the second support member are formed with different thicknesses.

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