JP2008244943A - Film bulk acoustic resonator and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film bulk acoustic resonator which adjusts an antiresonant frequency using a simple constitution, without causing spurious oscillations and is superior in a work controllability. <P>SOLUTION: The film bulk acoustic resonator 50 is provided with a lamination resonator 51, which vibrates longitudinally in a thickness direction and an impedance adjusting portion 52, which adjusts the antiresonant frequency of the lamination resonator 51 by changing an impedance of the laminated resonator 51. The antiresonant frequency of the lamination resonator 51 is adjusted, by forming a capacity element connected in parallel to the lamination resonator 51 as the impedance adjusting portion 52. A lower electrode 20A of the laminated resonator 51 and a lower electrode 20B of the impedance adjusting portion 52 are isolated physically and control the generation of the spurious oscillations, caused by propagating a transversal wave generated in the lamination resonator 51 to the impedance adjusting portion 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thin film bulk wave resonator and a manufacturing method thereof.

  Numerous resonances using piezoelectric materials such as thin film bulk acoustic resonators and surface acoustic wave resonators as resonators that make up bandpass filters for wireless LAN and mobile communication devices The vessel has been put into practical use. In particular, thin film bulk acoustic wave resonators are commercialized as RF filters for PCS (Personal Communication Service) systems, which have an excellent Q value due to the structure in which elastic waves propagate in the film thickness direction, and require high frequency selectivity. ing. The thin film bulk acoustic wave resonator has a substrate and a laminated resonator formed on the substrate. The laminated resonator has a piezoelectric film and a pair of upper and lower electrodes sandwiching the piezoelectric film from above and below, and when a high frequency signal is applied between the upper electrode and the lower electrode, the laminated resonance The body is excited in the longitudinal direction at a resonance frequency at which the film thickness is equal to ½ wavelength.

  In the thin film bulk acoustic wave resonator, the resonance frequency can be controlled by adjusting the thickness of the laminated resonator. In order to obtain a desired resonance frequency, it is necessary to accurately adjust the thickness of the piezoelectric film and the electrode, but there is a limit to the processing accuracy such as etching. In view of such circumstances, Japanese Patent No. 3822470 provides a planned cutting portion connected to the upper electrode or the lower electrode of the resonator, and changes the inductance depending on the state of the planned cutting portion, thereby resonating the resonator. A method for adjusting the frequency has been proposed.

However, a basic configuration is such that a one-port resonator is connected in series and parallel in a ladder form, such as a ladder filter, and the resonance frequency of the series arm resonator and the anti-resonance frequency of the parallel arm resonator are substantially matched. Thus, in a filter that obtains bandpass characteristics, it is necessary to adjust not only the resonance frequency but also the antiresonance frequency. In view of such circumstances, Japanese Patent Laid-Open No. 9-64682 provides a frequency adjusting capacitor connected to the resonator, and adjusts the anti-resonance frequency of the resonator by increasing / decreasing the electrode area of the frequency adjusting capacitor. A method has been proposed.
Japanese Patent No. 3822470 JP-A-9-64682

  However, in the technique disclosed in Japanese Patent Laid-Open No. 9-64682, the number of steps for manufacturing the frequency adjusting capacitor is increased and a certain amount of mounting area is required. The inconvenience that it becomes difficult arises.

  In the thin film bulk acoustic wave resonator, not only a longitudinal wave (TE wave) in the main vibration mode but also a transverse wave (TS wave) is generated as a secondary. Since the common lower electrode for the resonator and the lower electrode for frequency adjustment disclosed in the publication are used, the transverse wave generated in the piezoelectric film of the resonator is not applied to the common lower electrode. Propagating and reflecting at the end of the frequency adjusting capacitor may cause spurious vibrations, which may degrade the filter characteristics.

  Further, in the resonator structure disclosed in the publication, a common lower electrode is formed in the process of separating the resonator piezoelectric film and the frequency adjusting capacitor piezoelectric film by wet etching using an alkaline aqueous solution or the like. There is a risk of over-etching, and there is a problem that precise processing control is difficult.

  Therefore, the present invention provides a thin film bulk wave resonator excellent in processing controllability capable of adjusting the antiresonance frequency with a simple configuration without causing spurious vibrations and a method for manufacturing the same. This is the issue.

  In order to solve the above problems, a thin film bulk acoustic wave resonator according to the present invention adjusts an anti-resonance frequency of a laminated resonator by changing the impedance of the laminated resonator that longitudinally vibrates in the thickness direction and the laminated resonator. And an impedance adjustment unit. By forming the capacitive element connected in parallel to the laminated resonator as the impedance adjustment unit, it is possible to adjust the anti-resonance frequency of the laminated resonator.

  Here, the laminated resonator includes a first lower electrode laminated on the substrate and a first piezoelectric film laminated on the first lower electrode. The impedance adjusting unit includes a second lower electrode laminated on the substrate and a second piezoelectric film laminated on the second lower electrode. A common upper electrode is laminated on the first piezoelectric film and the second piezoelectric film, and the first lower electrode and the second lower electrode are separated.

  According to such a configuration, since it is not necessary to form the impedance adjustment ground on the bottom surface of the substrate, the impedance adjustment portion can be formed without going through a complicated manufacturing process. In addition, since the area of the impedance adjustment unit can be designed according to the impedance adjustment amount of the laminated resonator, it can be formed in an arbitrary shape on the remaining portion of the chip, and the limited area can be effectively used. . Furthermore, the transverse wave generated in the laminated resonator propagates to the impedance adjusting unit, and the reflected wave becomes spurious vibration. The first lower electrode of the laminated resonator and the second lower electrode of the impedance adjusting unit are: Since they are physically separated, the transverse wave generated in the laminated resonator is not propagated to the impedance adjusting unit, and the occurrence of spurious vibration can be suppressed.

  Between the 1st lower electrode and the 2nd lower electrode, the groove-shaped recessed part depressed in the inside of a board | substrate may be formed. According to such a configuration, since the propagation of the transverse wave generated in the laminated resonator to the impedance adjusting unit can be effectively suppressed, the generation of spurious vibrations can be further effectively suppressed.

  In the substrate, a cavity is preferably formed at a position corresponding to the laminated resonator, and the recess is preferably extended in a direction oblique to the side surface of the cavity. According to such a configuration, the transverse wave propagating from the laminated resonator to the concave portion can be reflected in a direction different from the incident oblique direction, and the vibration energy can be attenuated. It can be effectively suppressed.

  If the planar pattern of the upper electrode constituting the impedance adjustment unit is larger than the planar pattern of the second lower electrode, the impedance of the laminated resonator is reduced by utilizing the parasitic capacitance formed between the upper electrode and the substrate. Since it can be adjusted, it is effective when the frequency increases.

  A method of manufacturing a thin film bulk acoustic wave resonator according to the present invention includes a multilayer resonator including a first lower electrode and a first piezoelectric film, and an antiresonance frequency of the multilayer resonator by changing the impedance of the multilayer resonator. A method for manufacturing a thin film bulk acoustic wave resonator having an impedance adjusting unit including a second lower electrode and a second piezoelectric film, Forming a lower electrode and a second lower electrode separated from the first lower electrode on the substrate, forming a first piezoelectric film on the first lower electrode, Forming a second piezoelectric film on the second lower electrode, and forming a common upper electrode on the first piezoelectric film and the second piezoelectric film.

  According to such a method, the impedance adjusting portion can be formed by a simple manufacturing process.

  According to the present invention, the impedance adjustment unit can be formed without going through a complicated manufacturing process. In addition, since the area of the impedance adjustment unit can be designed according to the impedance adjustment amount of the laminated resonator, it can be formed in an arbitrary shape on the remaining portion of the chip, and the limited area can be effectively used. . Furthermore, since the first lower electrode of the laminated resonator and the second lower electrode of the impedance adjusting unit are physically separated, the transverse wave generated in the laminated resonator is not propagated to the impedance adjusting unit. And generation of spurious vibrations can be suppressed.

  Embodiments according to the present invention will be described below with reference to the drawings. Devices with the same reference numerals indicate the same devices, and redundant description is omitted. The drawings are schematic, and the relationship between the thickness and the planar dimensions and the ratio of the thickness of each layer are different from the actual ones. Moreover, the part from which the relationship and ratio of a mutual dimension differ between drawings is contained.

  The device structure of the thin film bulk acoustic wave resonator 50 according to the first embodiment will be described with reference to FIGS. 1 is a plan view of the thin film bulk acoustic wave resonator 50, FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1, and FIG. 3 is a cross-sectional view taken along line 3-3 in FIG.

  The thin film bulk acoustic wave resonator 50 includes a substrate 10, a laminated resonator 51, and an impedance adjusting unit 52 (see FIG. 3). The material of the substrate 10 is not particularly limited as long as it has an appropriate mechanical strength and is suitable for fine processing such as etching. For example, a silicon single crystal substrate or a sapphire single crystal substrate is used. A ceramic substrate, a quartz substrate, a glass substrate, or the like is preferable. An insulating film 11 such as a silicon oxide film or a silicon nitride film is formed on the front surface and the back surface of the substrate 10. Further, in the substrate 10, a cavity 12 is opened on the back surface of the substrate corresponding to the position of the stacked resonator 51 in order to ensure free vibration in the thickness direction of the stacked resonator 51. However, since the insulating film 11 is not essential for the laminated resonator 51, it may not be formed.

The laminated resonator 51 includes a lower electrode 20A laminated on the insulating film 11, a piezoelectric film 30A laminated on the lower electrode 20A, and an upper electrode 40 laminated on the piezoelectric film 30A. The material of the piezoelectric film 30A is preferably a piezoelectric material having a large electromechanical coupling coefficient, a small propagation loss and a power flow angle, a small delay time temperature coefficient, and a low frequency dispersion of propagation speed. ZnO), aluminum nitride (AlN), potassium niobate (KNbO ₃ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lead zirconate titanate (PZT), barium titanate (BaTiO ₃ ), etc. Is preferred. Further, as the material of the lower electrode 20A and the upper electrode 40, a conductive material capable of forming an appropriate orientation of the piezoelectric film 30A, for example, ruthenium (Ru), aluminum (Al), molybdenum (Mo), titanium ( Ti), platinum (Pt), gold (Au), tungsten (W), tantalum (Ta), or an alloy containing any two or more of these is preferable.

  When a high frequency signal is applied to the lower electrode 20A and the upper electrode 40, the piezoelectric film 30A vibrates in the thickness direction due to the inverse piezoelectric effect of the piezoelectric film 30A, and exhibits electrical resonance characteristics. Furthermore, the elastic wave or vibration generated in the piezoelectric film 30A is converted into an electric signal by the piezoelectric effect of the piezoelectric film 30A. This elastic wave is a thickness longitudinal vibration wave having a main displacement in the thickness direction of the piezoelectric film 30A. Depending on the electrode material, the acoustic wave has a resonance frequency at which the film thickness of the laminated resonator 51 is approximately equal to ½ wavelength. Excited.

  On the other hand, the impedance adjustment unit 52 includes a lower electrode 20B stacked on the insulating film 11, a piezoelectric film 30B stacked on the lower electrode 20B, and an upper electrode 40 stacked on the piezoelectric film 30B. The impedance adjustment unit 52 is formed on the substrate 10 where the cavity 12 is not formed, and functions as a capacitive element. Here, the upper electrode 40 of the laminated resonator 51 and the upper electrode 40 of the impedance adjusting unit 52 are common, and the lower electrode 20A of the laminated resonator 51 and the lower electrode 20B of the impedance adjusting unit 52 are 3 Although they are physically separated in the -3 line cross-sectional view, they are electrically connected via a wiring (not shown) or a common ground (not shown). The impedance adjusting unit 52 is connected in parallel to the laminated resonator 51 and has a function of adjusting the impedance (capacitive reactance component) of the laminated resonator 51. However, since the insulating film 11 is not essential for the impedance adjustment unit 52, it may not be formed.

  The piezoelectric film 30A of the laminated resonator 51 and the piezoelectric film 30B of the impedance adjusting unit 52 are separated into island shapes.

FIG. 4 shows an equivalent circuit of the thin film bulk wave resonator 50. This equivalent circuit is a circuit in which an equivalent circuit 51E of the laminated resonator 51 and an equivalent circuit 52E of the impedance adjustment unit 52 are connected in parallel. The equivalent circuit 51E is a parallel connection circuit of a capacitor C2 and a series connection circuit of a capacitor C1, an inductance L, and a resistor R, and the equivalent circuit 52E is a capacitor Cv. Here, when the resonance frequency of the thin film bulk acoustic wave resonator 50 is fr and the antiresonance frequency is fa, the following equations (1) to (2) are established.
fr = 1 / 2π (L × C1) ^1/2 (1)
fa = fr [1+ {C1 / (C2 + Cv)}] ^1/2 (2)

  From the equations (1) to (2), it can be understood that the impedance adjustment unit 52 can adjust only the anti-resonance frequency fa without changing the resonance frequency fr by adjusting the capacitance Cv. Here, Cv means the electrostatic capacity between the upper electrode 40 and the lower electrode 20B, and the planar pattern of the upper electrode 40 constituting the impedance adjusting unit 52 has a shape larger than that of the lower electrode 20B. In this case, the parasitic capacitance formed between the upper electrode 40 and the substrate 10 via the piezoelectric film 30B is also included. Here, the capacitance between the upper electrode 40 and the lower electrode 20B is effective for coarse adjustment of the anti-resonance frequency fa, and the parasitic capacitance between the upper electrode 40 and the substrate 10 has an anti-resonance frequency fa. Effective for fine adjustment.

  The plane pattern means a plan view when the substrate 10 is viewed from an infinite distance in the vertical direction on the upper surface of the substrate 10.

  FIG. 5 is a graph showing the relationship between the electrode area of the impedance adjustment unit 52 and the antiresonance frequency variation. The capacitance value Cv of the impedance adjustment unit 52 is determined by the film thickness and dielectric constant of the piezoelectric film 30B and the electrode area. According to this graph, when the film thickness of the piezoelectric film 30B is constant, the antiresonance frequency variation tends to increase as the electrode area increases.

  FIG. 6 shows the relationship between the capacitance value Cv of the impedance adjustment unit 52 and the antiresonance frequency change amount Δfa. This table shows that the anti-resonance frequency variation Δfa tends to increase as the capacitance value Cv increases. For reference, this table also shows the relationship between the capacitance value Cv, the resonance frequency fr, and the antiresonance frequency fa.

  FIG. 7 shows a correspondence relationship between the electrode area of the impedance adjustment unit 52, the film thickness of the piezoelectric film 30B, and the capacitance value Cv.

  FIG. 8 is a graph showing the correspondence between the electrode area of the impedance adjustment unit 52 and the capacitance value Cv. Since the capacitance value Cv is determined by the film thickness and dielectric constant of the piezoelectric film 30B and the electrode area, the graph becomes a straight line passing through the origin, and becomes steeper as the film thickness of the piezoelectric film 30B decreases.

  As shown in these graphs or tables, when the anti-resonance frequency fa does not match the desired frequency, the deformation for reducing the electrode area of the impedance adjusting unit 52 by etching or the like according to the thickness of the piezoelectric film 30B. By applying the processing, the anti-resonance frequency fa can be matched with a desired frequency.

  As the capacitance value Cv of the impedance adjustment unit 52, a value of about 0 pF to 10 pF is practically sufficient, and a capacitance of about 0 pF to 5 pF is particularly practical. Further, it is practically sufficient if the adjustment amount of the anti-resonance frequency is about 150 MHz at the maximum, and an adjustment amount of about 50 MHz at the maximum is particularly practical.

Next, a manufacturing process of the thin film bulk acoustic wave resonator 50 will be described with reference to FIG.
First, as shown in FIG. 9A, for example, a (100) silicon substrate is prepared as the substrate 10, and the insulating film 11 is formed on the front surface and the back surface of the substrate 10. For example, in order to form a silicon oxide film as the insulating film 11, a thermal oxidation method or the like may be applied. Further, a metal film of about 50 nm to 600 nm is deposited on the insulating film 11 using RF magnetron sputtering, etc., an etching mask is formed by photolithography, the metal film is patterned by ion milling or the like, and separated into islands. The lower electrodes 20A and 20B thus formed are formed. However, as described above, the insulating film 11 is not essential.

  Next, as shown in FIG. 9B, a piezoelectric material is deposited on the lower electrodes 20A and 20B by an RF magnetron sputtering method or the like. The film thickness of the piezoelectric material may be adjusted according to the resonance frequency fr. For example, if the resonance frequency is set to about 2.0 GHz using AlN, it depends on the electrode material, but about 0.8 μm to 2 μm. What is necessary is just to set to the film thickness of. Then, after forming an etching mask by photolithography, the piezoelectric material is patterned into islands by patterning the piezoelectric material by reactive ion etching using a chloride gas or wet etching using an alkaline aqueous solution or the like. 30A and 30B are formed.

  Subsequently, as shown in FIG. 9C, a metal film of about 50 nm to 600 nm is formed by RF magnetron sputtering or the like so as to cover the piezoelectric films 30A and 30B exposed on the surface and the insulating film 11. After depositing and forming an etching mask by photolithography, the upper electrode 40 is formed by selectively etching the metal film by ion milling, wet etching or the like.

  Finally, as shown in FIG. 9D, after forming an etching mask on the back surface of the substrate 10 by photolithography, the back surface of the substrate is opened by reactive ion etching using a fluoride-based gas, and the cavity 12 is formed. Form.

  According to the present embodiment, since it is not necessary to form the impedance adjustment ground on the bottom surface of the substrate, the impedance adjustment portion 52 can be formed without going through a complicated manufacturing process. Moreover, since the area of the impedance adjustment unit 52 can be designed according to the impedance adjustment amount of the laminated resonator 51, it can be formed in an arbitrary shape on the remaining portion on the chip, and the limited area Can be used effectively.

  The device structure of the thin film bulk acoustic wave resonator 60 according to the second embodiment will be described with reference to FIGS. Here, FIG. 10 is a plan view of the thin film bulk wave resonator 60, and FIG. 11 is a sectional view taken along line 11-11 in FIG.

  The thin film bulk wave resonator 60 includes a substrate 10, a laminated resonator 61, and an impedance adjustment unit 62 (see FIG. 11). Between the laminated resonator 61 and the impedance adjustment unit 62, a groove-shaped recess 63 that is recessed from the substrate surface into the substrate is formed. The concave portion 63 has a function of blocking the transverse wave generated in the piezoelectric film 30 </ b> A of the laminated resonator 61 from propagating to the impedance adjusting unit 62. As the depth D1 and the width W1 of the recess 63, it is preferable to have dimensions necessary and sufficient for blocking the propagation of the transverse wave, and for example, a dimension equal to or greater than the half wavelength of the transverse wave is suitable. Further, it is desirable that the extending direction of the recess 63 is inclined with respect to the side surface of the cavity 12. According to such a configuration, the transverse wave propagating from the laminated resonator 61 to the recess 63 can be reflected in a direction different from the incident oblique direction, and the vibration energy can be attenuated. Generation can be effectively suppressed.

  A device structure of the thin film bulk acoustic wave resonator 70 according to the third embodiment will be described with reference to FIGS. Here, FIG. 12 is a plan view of the thin film bulk acoustic wave resonator 70, and FIG. 13 is a sectional view taken along line 13-13 in FIG.

  The thin film bulk wave resonator 70 includes a substrate 10, a laminated resonator 71, and an impedance adjustment unit 72 (see FIG. 13). Between the laminated resonator 71 and the impedance adjusting unit 72, a groove-like recess 14 that is recessed from the back surface of the substrate into the substrate is formed. The concave portion 14 has a function of blocking the transverse wave generated in the piezoelectric film 30 </ b> A of the laminated resonator 71 from propagating to the impedance adjusting unit 72. The depth D2 and the width W2 of the concave portion 14 preferably have dimensions that are necessary and sufficient to block the propagation of the transverse wave. For example, a dimension that is equal to or greater than the half wavelength of the transverse wave is suitable. The recess 14 may be formed to a depth at which the insulating film 11 on the substrate surface is exposed on the back side of the substrate. Further, it is desirable that the extending direction of the recess 14 is inclined with respect to the side surface of the cavity 12. According to this configuration, the transverse wave propagating from the laminated resonator 71 to the concave portion 14 can be reflected in a direction different from the incident oblique direction and the vibration energy can be attenuated. Generation can be effectively suppressed.

  The device structure of the thin film bulk acoustic wave resonator 80 according to the fourth embodiment will be described with reference to FIGS. 14 is a plan view of the thin film bulk acoustic wave resonator 80, and FIG. 15 is a sectional view taken along line 15-15 in FIG.

  The thin film bulk acoustic wave resonator 80 includes a substrate 10, a laminated resonator 81, and a plurality of impedance adjustment units 82A and 82B (see FIG. 15). The impedance adjustment unit 82A includes a lower electrode 20B, a piezoelectric film 30B, and an upper electrode 40A, and the upper electrode 40A is common to the upper electrode 40A of the multilayer resonator 81. The impedance adjustment unit 82B includes a lower electrode 20B, a piezoelectric film 30B, and an upper electrode 40B. The upper electrode 40A and the upper electrode 40B are physically separated in the sectional view taken along the line 15-15, but are electrically connected via a wiring (not shown) or a common ground (not shown).

  According to the present embodiment, since the thin film bulk acoustic wave resonator 80 includes the plurality of impedance adjusting units 82A and 82B, the impedance of the laminated resonator 81 can be finely adjusted. The capacitance values of the individual impedance adjustment units 82A and 82B are preferably about 0 pF to 1.5 pF, and the combined capacitance of the plurality of impedance adjustment units 82A and 82B is preferably about 0 pF to 5 pF. Further, from the viewpoint of facilitating the impedance adjustment of the laminated resonator 81, the capacitance values of the individual impedance adjustment units 82A and 82B may be the same, and the shapes thereof may all be the same.

FIG. 16 shows a circuit configuration of a duplexer 90 according to the fifth embodiment.
The duplexer 90 includes an antenna terminal ANT1 connected to an antenna (not shown), a transmission signal terminal SX1 connected to a transmission circuit (not shown) that outputs a transmission signal to the antenna, and reception received via the antenna. A reception signal terminal RX1 connected to a reception circuit (not shown) for inputting a signal, a transmission filter 91 that allows the transmission signal to pass and blocks the reception signal, and reception that allows the reception signal to pass and blocks the transmission signal. Filter 92. Either one or both of the transmission filter 91 and the reception filter 92 has a circuit configuration in which a ladder filter 100 shown in FIG. The ladder type filter 100 is obtained by connecting a series arm resonator 101 and a parallel arm resonator 102 in a ladder shape. One or both of the series arm resonator 101 and the parallel arm resonator 102 are any of the thin film bulk wave resonators 50 to 80 according to the first to fourth embodiments.

1 is a plan view of a thin film bulk acoustic wave resonator according to Example 1. FIG. FIG. 2 is a sectional view taken along line 2-2 in FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 1. 1 is an equivalent circuit diagram of a thin film bulk acoustic wave resonator according to Example 1. FIG. It is a graph which shows the relationship between the electrode area of an impedance adjustment part, and an antiresonance frequency variation | change_quantity. It is a table which shows the relationship between the capacitance value of an impedance adjustment part, and antiresonance frequency variation | change_quantity. It is a table which shows the correspondence with the electrode area of an impedance adjustment part, the film thickness of a piezoelectric material film, and a capacity value. It is a graph which shows the correspondence of the electrode area of an impedance adjustment part, and a capacitance value. 6 is a manufacturing process cross-sectional view of the thin film bulk acoustic wave resonator according to Example 1. FIG. 6 is a plan view of a thin film bulk acoustic wave resonator according to Example 2. FIG. It is the 11-11 line sectional view in FIG. 6 is a plan view of a thin film bulk acoustic wave resonator according to Example 3. FIG. FIG. 13 is a sectional view taken along line 13-13 in FIG. 6 is a plan view of a thin film bulk acoustic wave resonator according to Example 4. FIG. FIG. 15 is a sectional view taken along line 15-15 in FIG. 14. FIG. 10 is a circuit configuration diagram of a duplexer according to a fifth embodiment. It is a circuit block diagram of a ladder type filter.

Explanation of symbols

50, 60, 70, 80 ... thin film bulk acoustic wave resonators 51, 61, 71, 81 ... laminated resonators 52, 62, 72, 82 ... impedance adjusters 20A, 20B ... lower electrodes 30A, 30B ... piezoelectric film 40, 40A, 40B ... Upper electrode

Claims (5)

A thin film bulk acoustic wave resonator comprising: a laminated resonator that longitudinally vibrates in a thickness direction; and an impedance adjusting unit for adjusting an anti-resonance frequency of the laminated resonator by changing an impedance of the laminated resonator,
The laminated resonator includes a first lower electrode laminated on a substrate, and a first piezoelectric film laminated on the first lower electrode,
The impedance adjustment unit includes a second lower electrode laminated on the substrate, and a second piezoelectric film laminated on the second lower electrode,
A common upper electrode is laminated on the first piezoelectric film and the second piezoelectric film,
A thin film bulk acoustic wave resonator in which the first lower electrode and the second lower electrode are separated. The thin film bulk acoustic wave resonator according to claim 1,
A thin film bulk acoustic wave resonator in which a groove-like recess that is recessed inside the substrate is formed between the first lower electrode and the second lower electrode. The thin film bulk acoustic wave resonator according to claim 2,
In the substrate, a cavity is formed at a position corresponding to the laminated resonator,
The recess is a thin film bulk acoustic wave resonator extending in a direction oblique to the side surface of the cavity. The thin film bulk acoustic wave resonator according to claim 1,
A thin film bulk acoustic wave resonator in which a planar pattern of the upper electrode constituting the impedance adjusting unit is larger than a planar pattern of the second lower electrode. A laminated resonator including a first lower electrode and a first piezoelectric film; and an impedance adjusting unit for adjusting an anti-resonance frequency of the laminated resonator by changing an impedance of the laminated resonator, A method for manufacturing a thin film bulk acoustic wave resonator having a second lower electrode and an impedance adjustment unit including a second piezoelectric film,
Forming each of the first lower electrode and the second lower electrode separated from the first lower electrode on a substrate;
Forming the first piezoelectric film on the first lower electrode;
Forming the second piezoelectric film on the second lower electrode;
Forming a common upper electrode on the first piezoelectric film and the second piezoelectric film;
A method of manufacturing a thin film bulk acoustic wave resonator.

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