JP3514222B2 - Piezoelectric resonator, electronic components and electronic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonator, a piezoelectric component, and a piezoelectric device, and more particularly, to a piezoelectric resonator using elastic vibration of a piezoelectric layer, and an electronic component and an electronic device using the same.

[0002]

2. Description of the Related Art The resonance frequency of a piezoelectric thin-film resonator utilizing the thickness vibration of a piezoelectric substrate is inversely proportional to the thickness of the piezoelectric substrate. However, the thickness of the piezoelectric substrate itself has been reduced to a practical high frequency limit of several hundred MHz in the fundamental mode due to its mechanical strength and restrictions on handling.

In order to solve such a problem, a piezoelectric thin film resonator has been conventionally proposed, and has been proposed as a filter or a resonator. As shown in FIG. 1, the piezoelectric thin-film resonator 1 is formed by partially etching the Si substrate 2 using a microfabrication method so that a part of the Si substrate 2 has a thickness of several μm.
A thin film support 3 having the following thickness is formed, and a ZnO piezoelectric thin film 4 having a pair of excitation electrodes 5a and 5b is provided thereon.

In such a piezoelectric thin-film resonator 1, the thin-film supporting portion 3 can be thinned by using a fine processing technique, and the piezoelectric thin-film 4 can be formed thin by sputtering or the like. There is a possibility that high-frequency characteristics can be extended up to this point.

However, the temperature coefficient of resonance frequency (TCF) of ZnO is about -70 ppm / ° C., and the temperature coefficient of resonance frequency of Si is about −30 ppm / ° C. Also has a negative value, so Z
The combination of the piezoelectric thin film 4 made of nO and the thin film support 3 made of Si has a disadvantage that the temperature characteristic of the resonance frequency in the fundamental mode is deteriorated.

In the piezoelectric thin film resonator 6 shown in FIG.
The SiO ₂ thin film 7 is formed on the surface of the Si substrate 2 by thermal oxidation or the like, and the Si substrate 2 is partially etched to form the thin film support 3 with the SiO ₂ thin film 7, and the excitation electrodes 5 a and Piezoelectric thin film 4 having 5b on both sides
Is provided.

The temperature coefficient of the resonance frequency of ZnO is about -70.
ppm / ° C, temperature coefficient of resonance frequency of SiO ₂ is about +100
ppm / ° C., and the sign of the temperature coefficient of the resonance frequency is different between ZnO and SiO _2.
By setting the ratio of the thickness of the thin film support portion 3 made of SiO ₂ to a certain appropriate value (roughly 2: 1), the temperature coefficient of the resonance frequency in the fundamental mode can be reduced, The frequency temperature characteristics can be stabilized (Japanese Patent Application Laid-Open No. 58-121817).

FIG. 3 is a sectional view showing a piezoelectric thin film resonator 9 having another structure. This is a floating structure (air bridge structure)
A piezoelectric thin-film resonator 9 having a thin-film support portion 12 formed of SiO ₂ on a Si substrate 10 with an air gap 11 interposed therebetween, and the thin-film support portion 12 formed so as to float from the Si substrate 10. The excitation electrodes 14a, 1
A ZnO piezoelectric thin film 13 having 4b on both sides is provided.

In this piezoelectric thin-film resonator 9, similarly to the piezoelectric thin-film resonator 6 shown in FIG. 2, the ratio of the thickness of the ZnO piezoelectric thin film 13 to the thickness of the SiO ₂ thin-film support portion 12 is set to an appropriate value. By setting, the temperature coefficient of the resonance frequency is reduced,
The temperature characteristics of the resonance frequency can be stabilized.

[0010]

In the second piezoelectric thin film resonator 6, the temperature coefficient of the resonance frequency can be offset by combining the ZnO piezoelectric thin film 4 and the SiO ₂ thin film support 3. Further, in the third piezoelectric thin film resonator 9, the temperature coefficient of the resonance frequency can be canceled by combining the ZnO piezoelectric thin film 13 and the SiO ₂ thin film supporting portion 12.

However, while ZnO is a piezoelectric material,
Since SiO ₂ is a non-piezoelectric material, these piezoelectric thin-film resonators have low resonance response and poor resonance characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and it is an object of the present invention to stabilize the temperature characteristic of the resonance frequency, and to provide a good resonance characteristic with a large resonance response. An object of the present invention is to provide a piezoelectric resonator, an electronic component, and an electronic device.

[0013]

SUMMARY and its effect for solving the piezoelectric resonator according to claim 1, on a base plate, so as to float at least a portion of the substrate, i.e., the insulating so as not to contact the substrate Forming a body layer, and arranging a piezoelectric laminate in which one or more piezoelectric layers made of AlN and one or more piezoelectric layers made of ZnO are laminated on the insulator layer; An electrode is provided so as to sandwich at least one of the piezoelectric layers constituting the piezoelectric laminate. The piezoelectric resonator according to claim 2, wherein the piezoelectric resonator is provided on a substrate.
Insulation layer so that at least part of the substrate is lifted from the substrate
And a layer or a layer having a positive temperature coefficient of resonance frequency.
Represents a plurality of piezoelectric layers and one or more layers having a negative temperature coefficient.
Is used to insulate a piezoelectric laminate in which a plurality of piezoelectric layers are laminated.
Any of the above-described piezoelectric laminates arranged on the body layer
The piezoelectric layer is also sandwiched between any of the electrodes.
It is characterized by having provided. The piezoelectric according to claim 3.
The resonator floats at least partially above the substrate.
Form the insulator layer as if
One or more piezoelectric layers having a positive coefficient and the temperature
Stack one or more piezoelectric layers with negative coefficient
Placed on the insulator layer, the piezoelectric laminate
Sandwich at least one of the piezoelectric layers constituting the laminate
Before the temperature coefficient of the resonance frequency is negative.
The piezoelectric layer is made of ZnO, LiNbO ₃ , LiTaO ₃ ,
_{PbZr X Ti (1-X)} O 3 [0 ≦ x ≦ 0. 52] of
Characterized by using either piezoelectric material as the main component
And The piezoelectric resonator according to claim 4 is provided on a substrate.
And at least a part of the substrate is floated from the substrate.
One layer forming an edge layer and having a positive temperature coefficient of resonance frequency
Alternatively, a plurality of piezoelectric layers and one layer having a negative temperature coefficient
Or, a piezoelectric laminate in which a plurality of piezoelectric layers are laminated
The pressure forming the piezoelectric laminate is disposed on the insulating layer.
An electrode is provided so as to sandwich at least one of the electric conductor layers,
The piezoelectric layer having a positive temperature coefficient of resonance frequency is
_{N, PbZr X Ti (1-} X) O 3 [0. 54 ≦ x ≦
1] as a main component. Contract
The piezoelectric resonator according to claim 5, wherein the piezoelectric resonator is provided on a substrate,
Form insulator layer so that at least part of it floats
And one or more layers having a positive temperature coefficient of resonance frequency.
Piezoelectric layer and one or more layers whose temperature coefficient is negative
The piezoelectric laminate obtained by laminating the piezoelectric layers of
Disposed on the piezoelectric laminate,
An electrode is provided so as to sandwich at least one layer, and the insulator layer
Is composed mainly of SiO ₂ or SiN.
Features.

In the piezoelectric resonator according to any one of the first to fifth aspects , AlN or one or more piezoelectric layers having a positive temperature coefficient of the resonance frequency, and ZnO or a negative temperature coefficient thereof. Since one or more piezoelectric layers are laminated on the insulator layer, the resonance frequency of the entire piezoelectric resonator can be set by appropriately setting the thickness of the insulator layer and each piezoelectric layer. Can be made substantially zero. Moreover, since both the layer having a positive temperature coefficient and the layer having a negative temperature coefficient of the resonance frequency in the piezoelectric laminate are made of the piezoelectric material, the resonance response of the piezoelectric resonator is improved, and as possible out is possible to improve the resonance characteristics.

When the piezoelectric layer is formed directly on the substrate, the piezoelectric layer may be etched when the substrate or the sacrificial layer is etched in order to lift it off the substrate. Processing becomes difficult. On the other hand, in the piezoelectric resonator according to claims 1 to 5 , the insulating layer is provided on the substrate, and the insulating layer is generally difficult to be etched by an etching solution for etching the substrate or the sacrificial layer. In addition, processing in the manufacturing process can be facilitated.

Further, since the insulator layer and the two or more kinds of piezoelectric layers are laminated on the substrate, the material parameters of the vibrating part become three or more, and the adjustment of the mechanical coupling coefficient and the piezoelectric characteristics can be performed. .

[0017] Therefore, according to the piezoelectric resonator according to claim 1 to 5, to stabilize the temperature characteristic of the resonance frequency, the resonance response increased to be able to improve the resonance characteristics,
In addition, an etching process for floating the insulator layer from the substrate can be easily performed, and the degree of freedom in designing other characteristics can be increased.

The piezoelectric resonator according to the sixth aspect is the first aspect of the invention.
Alternatively , in the piezoelectric resonator described in any one of 3 to 5 , any one of the piezoelectric layers included in the piezoelectric laminate is sandwiched between any one of the electrodes.

In the piezoelectric resonator according to the second or sixth aspect , since all the piezoelectric layers are sandwiched between the electrodes, when an excitation electric signal is input to the electrodes, all the piezoelectric layers are excited. Is done. Therefore, the resonance response of the piezoelectric resonator can be made extremely large, and a piezoelectric resonator having strong resonance characteristics can be manufactured.

According to a seventh aspect of the present invention, there is provided a piezoelectric resonator according to the second aspect.
Alternatively , the piezoelectric layer having a negative temperature coefficient of the resonance frequency in the piezoelectric resonator described in 4 to 6 is made of ZnO, LiNb.
_{O 3, LiTaO 3, PbZr X} Ti (1-X) O
₃ [0 ≦ x ≦ 0.52], characterized in that it is composed mainly of a piezoelectric material.

ZnO, LiNbO ₃ , LiTaO ₃ , P
bZr _X Ti _(1-X) O ₃ [0 ≦ x ≦ 0.52]
8. The piezoelectric device according to claim 3 , wherein each of the piezoelectric materials is a piezoelectric material, and the temperature coefficient of the resonance frequency has a negative value .
In the case of a piezoelectric resonator, by combining with a piezoelectric layer having a positive temperature coefficient of resonance frequency, a piezoelectric resonator having good resonance characteristics can be manufactured.

[0022] The piezoelectric resonator according to the eighth aspect is characterized in that:
The piezoelectric layer having a positive temperature coefficient of the resonance frequency in the piezoelectric resonator described in 2, 3, or 5 to 7 is made of AlN, PbZ.
r _X Ti _(1-X) O ₃ [0.54 ≦ x ≦ 1] is characterized by being composed mainly of a piezoelectric material.

AlN, PbZr _X Ti _(1-X) O
₃ [0.54 ≦ x ≦ 1] is a piezoelectric material,
Moreover, since the temperature coefficient of the resonance frequency has a positive value, in the piezoelectric resonator according to claim 4 or 8,
By combining with a piezoelectric layer having a negative temperature coefficient of resonance frequency, a piezoelectric resonator having good resonance characteristics can be manufactured.

According to a ninth aspect of the present invention, there is provided a piezoelectric resonator according to the first aspect.
In the piezoelectric resonator according to any one of Items 4 to 6 , the insulator layer is mainly composed of SiO ₂ or SiN.

The insulator layer made of SiO ₂ or SiN can be arbitrarily patterned by photolithography and etching such as RIE. For this reason, in the piezoelectric resonator according to claim 5 or 9 , SiO ₂ or SiN
Is used as a piezoelectric film or a protective film for a substrate. Further, it can be formed in an arbitrary shape and used as a mask for etching a specific portion of the substrate. Further, in SiO ₂ , the temperature coefficient of the resonance frequency has a positive value, and in SiN, the temperature coefficient of the resonance frequency has a negative value. Therefore, the design of the piezoelectric resonator can be made by selectively using SiO ₂ and SiN. Can be easier.

Further, the piezoelectric resonator according to claim 10 or 1
As described in 1 , it can be applied to electronic components and electronic devices such as surface mounted type, chip type, package type and other piezoelectric resonators, piezoelectric filters, discriminators, etc. In addition, it is possible to obtain an electronic component and an electronic device having a large resonance response and good resonance characteristics.

[0027]

(First Embodiment) FIG. 4 is a sectional view showing the structure of a piezoelectric thin-film resonator 21 according to a first embodiment of the present invention. In this piezoelectric thin film resonator 21,
An SiO ₂ thin film 23 is formed on the upper surface of a Si
A cavity 24 is provided by opening the center of the substrate 22. SiO
_{2 The} portion of the thin film 23 corresponding to the cavity 24 is the thin film support 2
It becomes 5. An SiO ₂ film 29 is also formed on the lower surface of the Si substrate 22. _On the upper surface of the SiO ₂ thin film 23,
A piezoelectric thin film 26A made of AlN is formed, a piezoelectric thin film 26Z made of ZnO is formed thereon, and a piezoelectric laminated body 28 made of the AlN piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z is arranged on the thin film support 25. Have been. A
One excitation electrode 27a is provided on the lower surface of the 1N piezoelectric thin film 26A.
And a part of the excitation electrode 27a is exposed from the AlN piezoelectric thin film 26A. The other excitation electrode 27b is provided on the upper surface of the ZnO piezoelectric thin film 26Z.

In this way, the excitation electrodes 27a and 27b are provided on both surfaces of the vibration portion composed of the laminate of the ZnO piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A, and the thickness vibrates when an excitation electric signal is applied.

FIGS. 5 (a) to 5 (h) are schematic diagrams showing the steps of manufacturing the piezoelectric thin film resonator 21. FIG. First, (10
0) A surface Si substrate 22 is prepared, and an SiO ₂ film 29 is formed on the back surface of the Si substrate 22 by sputtering or the like. Then
A resist film 30 is formed on the SiO ₂ film 29, and the resist film 30 is patterned by photolithography to form an opening (FIG. 5A). The SiO ₂ film 29 is selectively etched with hydrofluoric acid or the like through the opening of the resist film 30 to make an opening in the SiO ₂ film 29 in accordance with the opening of the resist film 30 (FIG. 5B). After removing the resist film 30 formed on the back surface of the Si substrate 22, a SiO ₂ thin film 23 is formed on the surface of the Si substrate 22 by sputtering, CDD, or the like (FIG. 5C).

Using the SiO ₂ film 29 on the back surface as a mask, T
The Si substrate 22 is anisotropically etched from the lower surface side with an etchant such as MAH. By this anisotropic etching, the center of the Si substrate 22 is opened, and the SiO ₂ thin film 2 is opened.
A cavity 24 is formed below 3. As a result, the SiO ₂ thin film 2
3 is supported by a Si substrate 22 around the
₍₂₎ The center of the thin film 23 is floating above the cavity 24 from the Si substrate 22 (FIG. 5D). At this time, S
Since the iO ₂ thin film 23 is not etched by an etchant such as TMAH, processing for floating the SiO ₂ thin film 23 from the Si substrate 22 can be easily performed.

Next, an electrode material is deposited on the surface of the SiO ₂ substrate 23 by a lift-off deposition method to form one excitation electrode 27a (FIG. 5E). Thereafter, the excitation electrode 27a and the SiO 2
_{(2) An} AlN piezoelectric thin film 26A is formed on the thin film 23 (FIG. 5F). At this time, a part of the excitation electrode 27a is
It is exposed from the N thin film.

Further, ZnO is deposited by reactive sputtering using a metal mask to form an AlN piezoelectric thin film 2.
6A, a ZnO piezoelectric thin film 26Z is formed [FIG.
(G)]. An electrode material is deposited on the ZnO piezoelectric thin film 26Z by a lift-off deposition method, and the other excitation electrode 2
7b is formed [FIG. 5 (h)]. Thus, FIG.
The piezoelectric thin film resonator 21 having the structure shown in FIG.

The temperature coefficient of the resonance frequency of ZnO has a negative value.
AlN and SiO _TwoTemperature of the resonance frequency
Since the degree coefficient has a positive value,_TwoThin film support
25, AlN piezoelectric thin film 26A and ZnO piezoelectric thin film 26Z.
According to the bonded piezoelectric thin film resonator 21, SiO 2_Two
Thin film 23, AlN piezoelectric thin film 26A, ZnO piezoelectric thin film 26
By appropriately setting the film thickness ratio of Z, the temperature of the resonance frequency
The coefficient can be made almost zero.

In a conventional piezoelectric thin film resonator,
Of the two types of thin films having different positive and negative temperature coefficients for canceling the temperature coefficient of the resonance frequency, only one of the thin films is formed of a piezoelectric material, whereas the thin film resonator 21 of the present invention has the same structure. Since both the ZnO piezoelectric thin film 26Z having a negative temperature coefficient of the resonance frequency and the AlN piezoelectric thin film 26A having a positive temperature coefficient are made of a piezoelectric material, the excitation electrodes 27a,
When an electric signal is applied to both piezoelectric thin films 26A and 26Z through 27b, elastic vibration (thickness vibration) is generated in both piezoelectric thin films 26A and 26Z, a large resonance response can be obtained, and strong resonance characteristics can be realized.

In addition, since the temperature coefficient of the resonance frequency of SiO ₂ is larger than the temperature coefficient of the resonance frequency of AlN, in order to cancel the temperature coefficient of the resonance frequency of ZnO, only the AlN piezoelectric thin film 26A must be used. SiO ₂ than the case
It is better to use the thin film support 25 together with the piezoelectric laminate 28 and S
The total thickness of the iO ₂ thin film support 25 can be reduced, and the piezoelectric thin film resonator 21 can be adapted to a high frequency range.

Further, as material parameters, the SiO ₂ thin film support 25 which is an insulator, the AlN piezoelectric thin film 26
A, since there are three of the ZnO piezoelectric thin films 26Z, the temperature coefficient of the resonance frequency and the characteristics other than the resonance characteristics, such as the mechanical engagement coefficient, can be adjusted, and the degree of freedom in design is increased.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating the piezoelectric thin-film resonator 31 according to the embodiment.
You. In the piezoelectric thin film resonator 31, the Si substrate 22
SiO on top of_TwoA thin film 23 is formed and is
By forming a cavity 24 in the center, SiO_TwoThin film 2
3 is formed. Furthermore, SiO_TwoOf the thin film support 25
A ZnO piezoelectric thin film 26Z is formed thereon, and an AlN pressure
By forming the electric thin film 26A, SiO 2 _TwoThin film support
The ZnO piezoelectric thin film 26Z and the AlN piezoelectric thin film 2
A piezoelectric laminate 28 made of 6A is provided. Also, Al
Piezoelectric composed of N piezoelectric thin film 26A and ZnO piezoelectric thin film 26Z
The excitation electrodes 2 are provided on the upper and lower surfaces of the laminate 28, respectively.
7b and 27a are provided.

The piezoelectric thin film resonator 31 is different from the first embodiment in that an AlN piezoelectric thin film 26A and a ZnO piezoelectric thin film 26Z
Are replaced, and as in the first embodiment, the SiO ₂ thin film supporting portion 25, the ZnO piezoelectric thin film 26Z
By appropriately setting the film thickness of the AlN piezoelectric thin film 26A and the AlN piezoelectric thin film 26A, the temperature coefficient of the resonance frequency can be stabilized. Further, Zn having different signs of the temperature coefficient of the resonance frequency.
Since both the O piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A vibrate piezoelectrically, the resonance impedance of the piezoelectric thin film resonator 31 can be increased, and strong resonance characteristics can be obtained.

[0039] Further, that it can by SiO ₂ thin film support portion 25 to facilitate the etching operation of the Si substrate 22, the piezoelectric thin film resonator 31 by thinning the total thickness of the piezoelectric layered body 28 and the SiO ₂ thin film support 25 As in the first embodiment, it is possible to cope with a high-frequency region and the degree of design freedom is increased by increasing material parameters.

(Third Embodiment) FIG. 7 is a sectional view showing a piezoelectric thin film resonator 32 according to a third embodiment of the present invention. This piezoelectric thin-film resonator 32 has an S
The SiO ₂ thin film support 25 is formed by forming the iO ₂ thin film support 25 and forming a cavity 24 in the center of the Si substrate 22 by anisotropic etching. Furthermore, S
By forming the AlN piezoelectric thin film 26A on the iO ₂ thin film support 25, forming the ZnO piezoelectric thin film 26Z thereon, and further forming the AlN piezoelectric thin film 26A thereon,
Piezoelectric laminate 2 having a three-layer structure on SiO ₂ thin film support 25
8 are provided. Also, the upper AlN piezoelectric thin film 26A,
ZnO piezoelectric thin film 26Z and underlying AlN piezoelectric thin film 26A
On the upper and lower surfaces of the vibrating portion composed of the piezoelectric laminate 28 of
Excitation electrodes 27b and 27a are provided respectively.

Even when such a three-layer piezoelectric laminate 28 is used, the ZnO piezoelectric thin film 26Z having a negative temperature coefficient of the resonance frequency and the AlN piezoelectric film 26 having a positive temperature coefficient of the resonance frequency are used. By appropriately setting the respective film thickness ratios of the thin film 26A and the SiO ₂ thin film support 25, the temperature coefficient of the resonance frequency can be made substantially zero, and the temperature characteristics can be stabilized.

Further, the upper and lower AlN piezoelectric thin films 26A sandwiched between the excitation electrodes 27a and 27b and the Zn
Since each of the O piezoelectric thin films 26Z is made of a piezoelectric material, when an electric signal is applied to the piezoelectric laminate 28 through the excitation electrodes 27a and 27b, the piezoelectric thin films 26A, 26Z and 26A of the piezoelectric laminate 28 elastically vibrate. Occurs,
A large resonance response can be obtained, and strong resonance characteristics can be realized.

Further, the piezoelectric thin film resonator 3 having the above structure
In the piezoelectric laminate 2, the work of etching the Si substrate 22 can be easily performed by the SiO ₂ thin film support 25.
By making the total film thickness of the thin film support 8 and the thin film support portion 25 thin, the piezoelectric thin film resonator 32 can cope with a high frequency region, and there is an advantage that the degree of freedom in design is increased by increasing the material parameters.

(Fourth Embodiment) FIG. 8 is a sectional view showing a piezoelectric thin film resonator 33 according to a fourth embodiment of the present invention. In the piezoelectric thin film resonator 33, the Si substrate 22
An SiO ₂ thin film supporting portion 25 is formed by forming a SiO ₂ thin film 23 on the upper surface of the substrate and forming a cavity 24 in the center of the Si substrate 22. Further, a ZnO piezoelectric thin film 26Z is formed on the SiO ₂ thin film supporting portion 25, and A
By forming the 1N piezoelectric thin film 26A and further forming the ZnO piezoelectric thin film 26Z thereon, the three-layer piezoelectric laminate 28 is provided on the SiO ₂ thin film support 25.
Excitation electrodes 27b and 27a are provided on the upper and lower surfaces of the three-layer piezoelectric laminate 28, respectively.

The piezoelectric thin-film resonator 33 is composed of the piezoelectric laminate 2
Each piezoelectric thin film 26Z constituting the 8, 26A, an arrangement of AlN piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z Since the third embodiment is only reversed at 26Z, as in the third embodiment, SiO ₂ By appropriately setting the thickness of the thin film support 25 and the thickness of each of the piezoelectric thin films 26Z, 26A, 26Z, the temperature coefficient of the resonance frequency can be stabilized. Further, since each of the piezoelectric thin films 26Z, 26A, 26Z constituting the piezoelectric laminate 28 undergoes piezoelectric vibration, the resonance impedance of the piezoelectric thin film resonator 33 can be increased, and strong resonance characteristics can be obtained.

Further, the SiO ₂ thin film supporting portion 25 allows the S
The point that the etching operation of the i-substrate 22 can be facilitated, the point that the total thickness of the piezoelectric laminate 28 and the SiO ₂ thin film supporting portion 25 is reduced to enable the piezoelectric thin film resonator 33 to cope with a high frequency region, As in the other embodiments, the degree of design freedom is increased by increasing the parameters.

(Fifth Embodiment) FIG. 9 is a sectional view showing a piezoelectric thin-film resonator 34 according to a fifth embodiment of the present invention. This piezoelectric thin-film resonator 34 has an S
An SiO ₂ thin film 23 is formed, and S ₂ is formed by anisotropic etching.
An SiO ₂ thin film 23 is formed by forming a cavity 24 in the center of the i-substrate 22. Further, an AlN piezoelectric thin film 26A is formed on the SiO ₂ thin film supporting portion 25, and a ZnO piezoelectric thin film 26Z is formed thereon, whereby the SiO ₂ thin film 26A is formed.
AlN piezoelectric thin film 26A and ZnO on thin film support 25
A piezoelectric laminate 28 made of a piezoelectric thin film 26Z is provided.
Excitation electrodes 27b and 27a are provided on the upper and lower surfaces of the ZnO piezoelectric thin film 26Z, respectively.

Also in the piezoelectric thin film resonator 34 having such a structure, the resonance frequency can be reduced by appropriately setting the thickness ratio of the thin film support portion 25 made of SiO ₂ , the AlN piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z. The temperature coefficient can be made substantially zero, and the temperature characteristics can be stabilized.

In the piezoelectric thin-film resonator 34, since the ZnO piezoelectric thin film 26Z is sandwiched between the excitation electrodes 27a and 27b, when an electric signal is applied to the ZnO piezoelectric thin film 26Z through the excitation electrodes 27a and 27b, 26
Elastic vibration (thickness vibration) occurs in Z, a large resonance response can be obtained, and strong resonance characteristics can be realized. On the other hand, the AlN piezoelectric thin film 26A has the excitation electrodes 27a, 27a.
b, AlN is a piezoelectric material, so that when a signal voltage is applied to the excitation electrodes 27a, 27b, the AlN
A voltage is also applied to the piezoelectric thin film 26A by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 34.

[0050] Further, that it can by SiO ₂ thin film support portion 25 to facilitate the etching operation of the Si substrate 22, the piezoelectric thin film resonator 34 by reducing the total thickness of the piezoelectric layered body 28 and the SiO ₂ thin film support 25 As in the other embodiments, it is possible to cope with a high frequency region and the degree of design freedom is increased by increasing material parameters.

(Sixth Embodiment) FIG. 10 shows a sixth embodiment of the present invention.
It is sectional drawing which shows the piezoelectric thin film resonator 35 by embodiment. The piezoelectric thin-film resonator 35 includes the same SiO ₂ thin-film support portion 25 and piezoelectric laminate 28 as in the fifth embodiment (FIG. 9).
In this configuration, excitation electrodes 27b and 27a are provided on the upper and lower surfaces of the AlN piezoelectric thin film 26A, respectively.

Also in the piezoelectric thin film resonator 35 having such a structure, the temperature characteristic of the resonance frequency can be made substantially zero to stabilize the temperature characteristics. In addition, ZnO piezoelectric thin film 2
6Z is outside the space between the excitation electrodes 27a and 27b.
Since nO is a piezoelectric material, the excitation electrodes 27a and 27b
When a signal voltage is applied to the ZnO piezoelectric thin film 26Z, a voltage is applied to the ZnO piezoelectric thin film 26Z by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 35.

Further, the piezoelectric thin-film resonator 35 also has a fifth
Like the piezoelectric resonator 34 according to the embodiment, since the piezoelectric resonator 34 is formed of the SiO ₂ thin film 23, the etching process of the Si substrate 22 can be simplified, the degree of freedom in design is increased, and it is possible to cope with a high frequency region. Has advantages.

(Seventh Embodiment) FIG. 11 shows a seventh embodiment of the present invention.
It is sectional drawing which shows the piezoelectric thin film resonator 36 by embodiment. The piezoelectric thin-film resonator 36 has an S
An SiO ₂ thin film 23 is formed, and S ₂ is formed by anisotropic etching.
An SiO ₂ thin film 23 is formed by forming a cavity 24 in the center of the i-substrate 22. Further, the thin film support 25
A ZnO piezoelectric thin film 26Z is formed on the
By forming the piezoelectric thin film 26A, the thin film support 25
ZnO piezoelectric thin film 26Z and AlN piezoelectric thin film 26A
Is provided. The excitation electrodes 2 are provided on the upper and lower surfaces of the AlN piezoelectric thin film 26A, respectively.
7b and 27a are provided.

Also in the piezoelectric thin film resonator 36 having such a structure, the resonance frequency can be reduced by appropriately setting the respective film thickness ratios of the thin film support portion 25 made of SiO ₂ , the ZnO piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A. The temperature coefficient can be made substantially zero, and the temperature characteristics can be stabilized.

In the piezoelectric thin film resonator 36, since the AlN piezoelectric thin film 26A is sandwiched between the excitation electrodes 27a and 27b, when an electric signal is applied to the AlN piezoelectric thin film 26A through the excitation electrodes 27a and 27b, 26
Elastic vibration occurs in A, a large resonance response can be obtained, and strong resonance characteristics can be realized. On the other hand, the ZnO piezoelectric thin film 26Z is located between the excitation electrodes 27a and 27b, but since ZnO is a piezoelectric material, the excitation electrode 27
a, 27b when a signal voltage is applied to the ZnO piezoelectric thin film 2
A voltage is also applied to 6Z by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin-film resonator 36.

Further, the etching operation of the Si substrate 22 can be facilitated by the SiO ₂ thin film supporting portion 25, and the total thickness of the piezoelectric laminate 28 and the thin film supporting portion 25 is reduced, so that the high frequency region of the piezoelectric thin film resonator 36 is reduced. As in the other embodiments, it is possible to cope with the problem, and the design flexibility is increased by increasing the material parameters.

(Eighth Embodiment) FIG. 12 shows an eighth embodiment of the present invention.
It is sectional drawing which shows the piezoelectric thin film resonator 37 by embodiment. This piezoelectric thin-film resonator 37 is similar to that of the seventh embodiment (FIG. 1).
In the same configuration of the thin film supporting portion 25 and the piezoelectric laminate 28 as in 1), excitation electrodes 27b and 27a are provided on the upper and lower surfaces of the ZnO piezoelectric thin film 26Z, respectively.

Also in the piezoelectric thin-film resonator 37 having such a structure, the temperature coefficient of the resonance frequency can be made substantially zero to stabilize the temperature characteristics. The AlN piezoelectric thin film 2
6A is outside between the excitation electrodes 27a and 27b,
Since 1N is a piezoelectric material, the excitation electrodes 27a and 27b
When a signal voltage is applied to the piezoelectric thin film resonator 26A, a voltage is applied to the AlN piezoelectric thin film 26A by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 37.

Further, this piezoelectric thin-film resonator 37 is
Like the piezoelectric resonator 36 according to the embodiment, the thin film is made of SiO 2.
Since it is formed of the _two thin films 23, it has the advantages that the etching process of the Si substrate 22 can be simplified, the degree of freedom in design is increased, and it is possible to cope with a high frequency region.

(Ninth Embodiment) FIG. 13 shows a ninth embodiment of the present invention.
It is sectional drawing which shows the piezoelectric thin film resonator 38 by embodiment. This piezoelectric thin-film resonator 38 has an S
An SiO ₂ thin film 23 is formed, and S ₂ is formed by anisotropic etching.
An SiO ₂ thin film 23 is formed by forming a cavity 24 in the center of the i-substrate 22. Further, the thin film support 25
An AlN piezoelectric thin film 26A is formed on the
By forming the piezoelectric thin film 26Z and further forming the AlN piezoelectric thin film 26A thereon, the piezoelectric lamination including the lower AlN piezoelectric thin film 26A, the ZnO piezoelectric thin film 26Z, and the upper AlN piezoelectric thin film 26A on the thin film support 25. Body 28
Is provided. Excitation electrodes 27b and 27a are provided on the upper surface of the upper AlN piezoelectric thin film 26A and the lower surface of the ZnO piezoelectric thin film 26Z, respectively.

Also in the piezoelectric thin film resonator 38 having such a structure, the resonance frequency can be reduced by appropriately setting the respective thickness ratios of the SiO ₂ thin film support portion 25, the upper AlN piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z. The temperature coefficient can be made substantially zero, and the temperature characteristics can be stabilized.

In the piezoelectric thin film resonator 38, the upper Al
Since the N piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z are sandwiched between the excitation electrodes 27a and 27b, the excitation electrode 27
a, 27b through the upper AlN piezoelectric thin films 26A and Z
When an electric signal is applied to the nO piezoelectric thin film 26Z, the upper layer A
Elastic vibration occurs in the 1N piezoelectric thin film 26A and the ZnO piezoelectric thin film 26Z, and a large resonance response can be obtained.
Strong resonance characteristics can be realized. On the other hand, the lower AlN piezoelectric thin film 26A is outside the space between the excitation electrodes 27a and 27b, but when a signal voltage is applied to the excitation electrodes 27a and 27b, the voltage is also applied to the lower AlN piezoelectric thin film 26A by dielectric polarization. This contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 38.

Further, the etching operation of the Si substrate 22 can be facilitated by the SiO ₂ thin film supporting portion 25, and the total thickness of the piezoelectric laminate 28 and the thin film supporting portion 25 is reduced, so that the piezoelectric thin film resonator 38 can be moved to the high frequency region. And the degree of design freedom is increased by increasing the material parameters.

(Tenth Embodiment) FIG. 14 is a sectional view showing a piezoelectric thin film resonator 39 according to a tenth embodiment of the present invention. This piezoelectric thin-film resonator 39 has the same structure of the thin-film support portion 25 and the piezoelectric laminate 28 as in the ninth embodiment (FIG. 13), except that the upper surface of the ZnO piezoelectric thin film 26Z and the lower A
An excitation electrode 27 is provided on the lower surface of the 1N piezoelectric thin film 26A.
b, 27a.

Also in the piezoelectric thin-film resonator 39 having such a structure, the temperature coefficient of the resonance frequency can be made substantially zero to stabilize the temperature characteristics. The upper AlN piezoelectric thin film 26A is located between the excitation electrodes 27a and 27b, but when a signal voltage is applied to the excitation electrodes 27a and 27b, a voltage is also applied to the AlN piezoelectric thin film 26A by dielectric polarization. This contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 39.

Further, the piezoelectric thin-film resonator 39 also has a ninth
Like the piezoelectric resonator 38 according to the embodiment, the thin film is made of SiO 2.
Since it is formed of the _two thin films 23, it has the advantages that the etching process of the Si substrate 22 can be simplified, the degree of freedom in design is increased, and it is possible to cope with a high frequency region.

(Eleventh Embodiment) FIG. 15 is a sectional view showing a piezoelectric thin film resonator 40 according to an eleventh embodiment of the present invention. This piezoelectric thin-film resonator 40 has excitation electrodes 27b and 27a on the upper and lower surfaces of a ZnO piezoelectric thin film 26Z in the same configuration of the SiO ₂ thin-film support 25 and the piezoelectric laminate 28 as in the ninth embodiment (FIG. 13). It is provided.

Also in the piezoelectric thin film resonator 40 having such a structure, the temperature characteristic of the resonance frequency can be made substantially zero to stabilize the temperature characteristics. The upper and lower layers A
The 1N piezoelectric thin films 26A, 26A are both excitation electrodes 27.
a, 27b, but outside the excitation electrodes 27a, 27b
When a signal voltage is applied to the upper and lower AlN piezoelectric thin films 26
A voltage is applied to A and 26A by dielectric polarization, which contributes to improvement of the resonance characteristics of the piezoelectric thin film resonator 40.

Further, since the piezoelectric thin film resonator 40 also has the lowermost thin film formed of the SiO ₂ thin film 23,
It has advantages that the etching process of the substrate 22 can be simplified, the degree of freedom in design can be increased, and it is possible to cope with a high frequency region.

In this embodiment, only one piezoelectric thin film is sandwiched between the excitation electrodes 27a and 27b. In the drawing, only the ZnO piezoelectric thin film 26Z is applied to the excitation electrodes 27a and 27b.
b, the upper or lower AlN piezoelectric thin film 26
Only A may be sandwiched between the excitation electrodes 27a and 27b.

(Twelfth Embodiment) FIG. 16 is a sectional view showing a piezoelectric thin-film resonator 41 according to a twelfth embodiment of the present invention. The piezoelectric thin film resonator 41, the SiO ₂ film 23 is formed on the Si substrate 22, to form the SiO ₂ film 23 by forming a cavity 24 in the central portion of the Si substrate 22 by anisotropic etching. Further, a ZnO piezoelectric thin film 26Z is formed on the thin film supporting portion 25, and A
By forming the 1N piezoelectric thin film 26A and further forming the ZnO piezoelectric thin film 26Z thereon, the lower ZnO piezoelectric thin film 26Z and the AlN piezoelectric thin film 26
A and a piezoelectric laminated body 28 composed of an upper ZnO piezoelectric thin film 26Z are provided. The upper ZnO piezoelectric thin film 26Z
And excitation electrodes 27b and 27a, respectively, are provided on the upper surface of the AlN piezoelectric thin film 26A.

In the piezoelectric thin film resonator 41 having such a structure, the thin film supporting portion 25 made of SiO ₂ and the Zn
O piezoelectric thin film 26Z, AlN piezoelectric thin film 26A and upper layer Z
By appropriately setting the respective film thickness ratios of the nO piezoelectric thin film 26Z, the temperature coefficient of the resonance frequency can be made substantially zero, and the temperature characteristics can be stabilized.

In the piezoelectric thin-film resonator 41, the upper Zn layer
Since the O piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A are sandwiched between the excitation electrodes 27a, 27b, the excitation electrodes 27
a and 27b through the upper ZnO piezoelectric thin films 26Z and A
When an electric signal is applied to the 1N piezoelectric thin film 26A, the upper layer Z
Elastic vibration occurs in the nO piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A, and a large resonance response can be obtained.
Strong resonance characteristics can be realized. On the other hand, the lower ZnO piezoelectric thin film 26Z is located between the excitation electrodes 27a and 27b, but since ZnO is a piezoelectric material, the excitation electrodes 27a and
When a signal voltage is applied to 27b, a voltage is also applied to the upper ZnO piezoelectric thin film 26Z by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 41.

Further, the etching work of the Si substrate 22 can be facilitated by the SiO ₂ thin film supporting portion 25, and the total film thickness of the piezoelectric laminate 28 and the thin film supporting portion 25 can be reduced so that the piezoelectric thin film resonator 41 can be moved to the high frequency region. And the degree of design freedom is increased by increasing the material parameters.

(Thirteenth Embodiment) FIG. 17 is a sectional view showing a piezoelectric thin-film resonator 42 according to a thirteenth embodiment of the present invention. This piezoelectric thin-film resonator 42 has the same structure of the thin-film supporting portion 25 and the piezoelectric laminate 28 as the twelfth embodiment (FIG. 16), and has the upper surface of the AlN piezoelectric thin film 26A and the lower Z layer.
An excitation electrode 27 is provided on the lower surface of the nO piezoelectric thin film 26Z.
b, 27a.

Also in the piezoelectric thin film resonator 42 having such a structure, the temperature coefficient of the resonance frequency can be made substantially zero to stabilize the temperature characteristic. The upper ZnO piezoelectric thin film 26Z is located between the excitation electrodes 27a and 27b, but when a signal voltage is applied to the excitation electrodes 27a and 27b, a voltage is also applied to the ZnO piezoelectric thin film 26Z by dielectric polarization. This contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator.

Further, the piezoelectric thin-film resonator 42 also has the first
Like the piezoelectric resonator 41 according to the second embodiment, since it is formed of the SiO ₂ thin film 23, the etching process of the Si substrate 22 can be simplified, the degree of freedom in design is increased, and it is possible to cope with a high frequency region. It has such advantages.

(Fourteenth Embodiment) FIG. 18 is a sectional view showing a piezoelectric thin film resonator 43 according to a fourteenth embodiment of the present invention. This piezoelectric thin-film resonator 43 has the same thin-film support portion 25 and piezoelectric laminate 28 as the twelfth embodiment (FIG. 16), except that excitation electrodes 27b and 27a are provided on the upper and lower surfaces of the AlN piezoelectric thin film 26A. Things.

Also in the piezoelectric thin film resonator 43 having such a structure, the temperature coefficient of the resonance frequency can be made substantially zero, and the temperature characteristics can be stabilized. In addition, Z of the upper layer and the lower layer
Each of the nO piezoelectric thin films 26Z and 26Z is an excitation electrode 27.
a, 27b, but outside the excitation electrodes 27a, 27b
When a signal voltage is applied to the upper and lower ZnO piezoelectric thin films 26
A voltage is also applied to Z and 26Z by dielectric polarization, which contributes to the improvement of the resonance characteristics of the piezoelectric thin film resonator 43.

Further, the piezoelectric thin-film resonator 43 is also made of Si
Since it is formed of the O ₂ thin film 23, it has advantages that the etching process of the Si substrate 22 can be simplified, the degree of freedom in design is increased, and it is possible to cope with a high frequency region.

In this embodiment, only one piezoelectric thin film is sandwiched between the excitation electrodes 27a and 27b.
8, only the AlN piezoelectric thin film 26A is used as the excitation electrodes 27a,
Although it is sandwiched between 27b, only the upper or lower ZnO piezoelectric thin film 26Z may be sandwiched between the excitation electrodes 27a and 27b.

(Fifteenth Embodiment) FIG. 19 is a sectional view showing a piezoelectric thin film resonator 44 according to a fifteenth embodiment of the present invention. The piezoelectric thin-film resonator 44 is formed by forming an SiO ₂ thin film 23 on a Si substrate 22 and forming a cavity 24 in the center of the Si substrate 22 by anisotropic etching, thereby forming a thin film supporting portion 25 on the SiO ₂ thin film 23. To form Further, a ZnO piezoelectric thin film 26Z is formed on the thin film support 25, an AlN piezoelectric thin film 26A is formed thereon, and a ZnO piezoelectric thin film 26Z is further formed thereon.
A lower ZnO piezoelectric thin film 26Z, A on the thin film support 25
A piezoelectric laminate 28 including an 1N piezoelectric thin film 26A and an upper ZnO piezoelectric thin film 26Z is provided. In addition, the upper layer Zn
Excitation electrodes 27a are provided on the boundary between the O piezoelectric thin film 26Z and the AlN piezoelectric thin film 26A and the lower surface of the lower ZnO piezoelectric thin film 26Z, respectively, so that they are electrically connected to each other. Zn
Excitation electrodes 27b on the boundaries of the O piezoelectric thin film 26Z
Are provided so as to conduct each other.

In the piezoelectric thin film resonator 44 having such a structure, since the upper ZnO piezoelectric thin film 26Z, the AlN piezoelectric thin film 26A and the lower ZnO piezoelectric thin film 26Z are connected in parallel, the excitation electrode 27a , 27b, an electric signal is applied to each of the piezoelectric thin films 26A, 26Z, elastic vibration is generated in all of the piezoelectric thin films 26Z, 26A, 26Z, a large resonance response can be obtained, and strong resonance characteristics can be realized.

Also in such a laminate having a three-layer structure, the thin film support 25, the lower ZnO piezoelectric thin film 26Z,
By appropriately setting the respective film thickness ratios of the AlN piezoelectric thin film 26A and the upper ZnO piezoelectric thin film 26Z, the temperature coefficient of the resonance frequency can be made almost zero, and the temperature characteristics can be stabilized.

Further, even in the piezoelectric thin film resonator 44 having such a structure, since the lowermost thin film is formed of the SiO ₂ thin film 23, the etching process of the Si substrate 22 can be simplified, and the design freedom can be improved. It has the advantages that the degree is high and it is possible to cope with a high frequency range.

The above description is only an example, and the excitation electrode 27 in the piezoelectric laminate 28 having another configuration is described.
Of course, a and 27b may be formed in three or more layers.

(Sixteenth Embodiment) FIG. 20 is a sectional view showing a piezoelectric thin-film resonator 51 according to a sixteenth embodiment of the present invention. This is a piezoelectric thin film resonator 51 having a floating structure (air bridge structure), in which a thin film support portion 54 made of SiO ₂ is formed on a glass substrate 52 via an air gap 53, and the thin film support portion 54 is formed. AlN piezoelectric thin film 5 on top
Piezoelectric laminate 56 composed of 5A and ZnO piezoelectric thin film 55Z
Is provided. Excitation electrodes 57b and 57a are provided on the upper and lower surfaces of a piezoelectric laminate 56 composed of the ZnO piezoelectric thin film 55Z and the AlN piezoelectric thin film 55A.

In this way, the excitation electrodes 57 are provided on both surfaces of the vibrating portion composed of the ZnO piezoelectric thin film 55Z and the AlN piezoelectric thin film 55A.
a, 57b are provided, and when an electric signal for excitation is applied, the thickness vibrates.

FIGS. 21 (a) to 21 (g) are schematic diagrams showing the steps of manufacturing the piezoelectric thin film resonator 51. FIG. First, a sacrifice layer 58 made of ZnO is formed on a glass substrate 52 by a sputtering method, and the sacrifice layer 58 is etched while leaving a portion serving as an air gap 53 (FIG. 21A). Next, a thin film supporting portion 54 is formed of SiO ₂ on the sacrificial layer 58 by a reactive sputtering method (FIG. 21).
(B)].

Next, an excitation electrode 57a is formed of Al on the thin film supporting portion 54 by lift-off deposition [FIG. 21 (c)]. Thin film support 54 and excitation electrode 57
A piezoelectric thin film 55A made of AlN is formed on the substrate a by a reactive sputtering method (FIG. 21D).

Thereafter, the sacrifice layer 58 is etched using an aqueous acetic acid solution, and the air gap 5
3 is formed, and the thin film supporting portion 54 is floated from the upper surface of the glass substrate 52 (FIG. 21E). At this time, since the thin film supporting portion 54 made of SiO ₂ is not etched by an etching solution such as CH ₃ COOH, the thin film supporting portion 54 is not etched.
Can be easily performed for floating the glass substrate 52 from the glass substrate 52. The sacrificial layer 58 may be removed by etching before forming the AlN piezoelectric thin film 55A.

Next, a ZnO piezoelectric thin film 55Z is formed on the upper surface of the AlN piezoelectric thin film 55A by a sputtering method [FIG.
(F)], using a metal mask to form Zn by vacuum evaporation.
An excitation electrode 57b is formed on the O piezoelectric thin film 55Z [FIG. 21 (g)]. Thus, the piezoelectric thin film resonator 51 having a floating structure as shown in FIG. 20 is manufactured.

The temperature coefficient of the resonance frequency of ZnO has a negative value while the temperature coefficient of the resonance frequency of AlN has a positive value. In the piezoelectric thin-film resonator 51 having the thin film 55A and the ZnO piezoelectric thin film 55Z, the thin-film support 54
By appropriately setting the thickness ratio between the O piezoelectric thin film 55Z and the AlN piezoelectric thin film 55A, the temperature coefficient of the resonance frequency can be made substantially zero.

Further, in this piezoelectric thin film resonator 51, since both the ZnO piezoelectric thin film 55Z and the AlN piezoelectric thin film 55A are made of a piezoelectric material, the piezoelectric thin film resonator 51A and the AlN piezoelectric thin film 55A are passed through the excitation electrodes 57a and 57b. When an electric signal is applied, elastic vibration occurs in both piezoelectric thin films 55A and 55Z, a large resonance response can be obtained, and strong resonance characteristics can be realized.

Further, since the value of the temperature coefficient of the resonance frequency of SiO ₂ is larger than the value of the temperature coefficient of the resonance frequency of AlN, in order to cancel the temperature coefficient of the resonance frequency of ZnO, only the AlN piezoelectric thin film 55A needs to be used. SiO ₂ than the case
The combined use of the thin film support portions 54 can reduce the total film thickness of the piezoelectric laminate 56 and the thin film support portions 54, and can adapt the piezoelectric thin film resonator 51 to a high frequency region.

Further, as material parameters, the SiO ₂ thin film supporting portion 54 which is an insulator, the AlN piezoelectric thin film 55
A, since there are three ZnO piezoelectric thin films 55Z, the temperature coefficient of the resonance frequency and the characteristics other than the resonance characteristics, such as the mechanical engagement coefficient, can be adjusted, and the degree of freedom in design is increased.

Further, according to the piezoelectric thin film resonator 51 having such a floating structure, the back surface of the substrate 52 does not need to be cut by etching, so that there is no need to limit the substrate to a specific material such as a glass substrate. There is.

The piezoelectric thin-film resonator 51 of this embodiment
In the above, ZnO and AlN are replaced with each other, a ZnO piezoelectric thin film 55Z is provided on the thin film support 54, and AlN is placed thereon.
The N piezoelectric thin film 55A may be formed.

(Seventeenth Embodiment) Various embodiments have been described for the diaphragm type piezoelectric thin film resonator.
As for the piezoelectric thin film resonator having a floating structure, three or more layers of piezoelectric thin films are formed on a thin film supporting portion, only a part of the piezoelectric thin film constituting a piezoelectric laminate is sandwiched between excitation electrodes, Various embodiments are possible, such as changing the combination of materials.

For example, FIG. 22 is a sectional view showing a piezoelectric thin-film resonator 59 according to a seventeenth embodiment of the present invention, which shows a different embodiment of the piezoelectric thin-film resonator 59 having a floating structure. In this piezoelectric thin-film resonator 59, a floating structure SiO 2 is formed on a glass substrate 52 via an air gap 53.
₍₂₎ Form a thin film support part 54, and place Al
An N piezoelectric thin film 55A is formed, and a ZnO piezoelectric thin film 5 is formed thereon.
5Z is formed, and excitation electrodes 57b and 57a are formed on the upper and lower surfaces of the ZnO piezoelectric thin film 55Z.

In the piezoelectric thin-film resonator 59, since the ZnO piezoelectric thin film 55Z is sandwiched between the excitation electrodes 57a and 57b, when an electric signal is applied to the ZnO piezoelectric thin film 55Z through the excitation electrodes 57a and 57b, 55
Elastic vibration occurs in Z, and a resonance response can be obtained. On the other hand, the AlN piezoelectric thin film 55A is
a, 57b, but outside the excitation electrodes 57a, 57b.
When a signal voltage is applied to the piezoelectric thin film resonator 55A, a voltage is applied to the AlN piezoelectric thin film 55A by dielectric polarization, and the resonance characteristics of the piezoelectric thin film resonator 59 can be improved. Therefore, also in this embodiment, it is possible to manufacture the piezoelectric thin film resonator 59 having stable resonance frequency temperature characteristics and strong resonance characteristics.

Further, the piezoelectric thin-film resonator 59 having such a structure also has the advantages that the degree of freedom in design is increased and that it is possible to cope with a high-frequency region as in the sixteenth embodiment.

(Eighteenth Embodiment) FIG. 23 is a sectional view showing the structure of a piezoelectric resonator 60 according to an eighteenth embodiment of the present invention. In this embodiment, a cavity 24 is formed on the upper surface of the Si substrate 22 by etching the upper surface of the Si substrate 22, and an SiO ₂ film 23 (a thin film supporting portion) is formed on the Si substrate 22 as an insulating film. 25), excitation electrode 27a, AlN piezoelectric thin film 26A, ZnO piezoelectric thin film 26
Z and the excitation electrode 27b are formed. An SiO ₂ film 29 is provided on the lower surface of the Si substrate 22. The manufacturing procedure, after forming the SiO ₂ film 23 on the upper surface of the Si substrate 22, an etchant is injected to the upper surface of the Si substrate 22 from the opening provided in the SiO ₂ film 23, located under the opening of the SiO ₂ film 23 The cavity 24 is provided by etching a part of the Si substrate 22. Then, sequentially excitation electrodes 27a on the upper surface of the SiO ₂ film 23, AlN piezoelectric thin film 26A, Zn
The O piezoelectric thin film 26Z and the excitation electrode 26b may be provided.

This embodiment corresponds to the first embodiment in which the cavities 24 are formed not from the back surface of the substrate but from the front surface. Such a piezoelectric resonator 30 has the same operation and effect as the first embodiment. Also in this embodiment, embodiments corresponding to the second to sixteenth embodiments are possible depending on the combination of the piezoelectric film and the electrodes.

In each of the above embodiments, the case where ZnO and AlN are combined as the piezoelectric material has been described. In addition, ZnO, LiNbO ₃ , LiTa
O ₃ , PbZr _X Ti _(1-X) O ₃ [0 ≦ x ≦ 0.5
A combination of a piezoelectric material having a negative temperature coefficient of the resonance frequency such as 2] and a piezoelectric material such as AlN having a positive temperature coefficient of the resonance frequency may be used. Further, the lowermost thin film and the thin film support may be formed of SiN.

[0107]

According to the piezoelectric resonator according to the first aspect,
Since one or more piezoelectric layers having a positive temperature coefficient of the resonance frequency and one or more piezoelectric layers having a negative temperature coefficient are laminated on the insulating layer, By appropriately setting the thickness of the body layer and each piezoelectric layer,
The temperature coefficient of the resonance frequency of the entire piezoelectric resonator can be made substantially zero. Moreover, since both the layer having a positive temperature coefficient and the layer having a negative temperature coefficient of the resonance frequency in the piezoelectric laminate are made of the piezoelectric material, the resonance response of the piezoelectric resonator is improved, and The resonance characteristics can be improved.

In the piezoelectric resonator according to the first aspect, an insulating layer is provided on the substrate, and the insulating layer is generally not easily etched by an etching solution for etching the substrate or the sacrificial layer. Processing in the manufacturing process can be facilitated.

Further, since the insulator layer and two or more kinds of piezoelectric layers are laminated on the substrate, the material parameters of the vibrating portion become three or more, and the adjustment of the mechanical coupling coefficient, the piezoelectric characteristics, and the like can be performed. .

Therefore, according to the piezoelectric resonator of the first aspect, the temperature characteristics of the resonance frequency are stable, the resonance response is large, the resonance characteristics are good, and the etching process for floating the insulator layer from the substrate. Can be easily performed, and the degree of freedom in designing other characteristics can be increased.

In the piezoelectric resonator according to the second aspect,
Since all the piezoelectric layers are sandwiched between the electrodes, all the piezoelectric layers are excited by inputting an excitation electric signal to the electrodes. Therefore, the resonance response of the piezoelectric resonator can be made extremely large, and a piezoelectric resonator having strong resonance characteristics can be manufactured.

ZnO, LiNbO ₃ , LiTaO ₃ , Pb
The Zr _X Ti _(1-X) O ₃ [0 ≦ x ≦ 0.52] is a piezoelectric material, and has a negative temperature coefficient of the resonance frequency. According to the described piezoelectric resonator, a piezoelectric resonator having excellent resonance characteristics can be manufactured by combining the piezoelectric resonator with a piezoelectric layer having a positive temperature coefficient of the resonance frequency.

AlN, PbZr _X Ti _(1-X) O
₃ [0.54 ≦ x ≦ 1] is a piezoelectric material, and the temperature coefficient of the resonance frequency has a positive value.
By combining with a piezoelectric layer having a negative temperature coefficient of resonance frequency, a piezoelectric resonator having good resonance characteristics can be manufactured.

The insulator layer made of SiO ₂ or SiN can be arbitrarily patterned by photolithography and etching such as RIE. For this reason, in the piezoelectric resonator described in claim 5, an insulating film made of SiO ₂ or SiN is used as a piezoelectric film or a protective film for a substrate. Further, it can be formed in an arbitrary shape and used as a mask for etching a specific portion of the substrate. Further, in SiO ₂ , the temperature coefficient of the resonance frequency is a positive value, and in SiN, the temperature coefficient of the resonance frequency is a negative value. Therefore, by using SiO ₂ and SiN properly, the design of the piezoelectric resonator can be improved. Can be easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a conventional piezoelectric thin-film resonator.

FIG. 2 is a cross-sectional view showing the structure of another conventional piezoelectric thin film resonator in which the temperature characteristic of the resonance frequency is improved.

FIG. 3 is a cross-sectional view showing the structure of another conventional piezoelectric thin-film resonator having a floating structure.

FIG. 4 is a sectional view showing the structure of the piezoelectric thin film resonator according to the first embodiment of the present invention.

5 (a) to 5 (h) are schematic diagrams for explaining a manufacturing process of the piezoelectric thin film resonator according to the embodiment.

FIG. 6 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a third embodiment of the present invention.

FIG. 8 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a sixth embodiment of the present invention.

FIG. 11 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a seventh embodiment;

FIG. 12 is a sectional view showing the structure of a piezoelectric thin-film resonator according to an eighth embodiment of the present invention.

FIG. 13 is a sectional view showing a structure of a piezoelectric thin film resonator according to a ninth embodiment of the present invention.

FIG. 14 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a tenth embodiment of the present invention.

FIG. 15 is a sectional view showing the structure of a piezoelectric thin-film resonator according to an eleventh embodiment of the present invention.

FIG. 16 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a twelfth embodiment of the present invention.

FIG. 17 is a sectional view showing a structure of a piezoelectric thin-film resonator according to a thirteenth embodiment of the present invention.

FIG. 18 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a fourteenth embodiment of the present invention.

FIG. 19 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a fifteenth embodiment of the present invention.

FIG. 20 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a sixteenth embodiment of the present invention.

FIGS. 21 (a) to (g) are schematic views illustrating a manufacturing process of the piezoelectric thin film resonator of the above.

FIG. 22 is a sectional view showing the structure of a piezoelectric thin-film resonator according to a seventeenth embodiment of the present invention.

FIG. 23 is a sectional view showing the structure of a piezoelectric thin film resonator according to an eighteenth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 22 Si substrate 23 SiO ₂ thin film 25 Thin film support 26A, 55A AlN piezoelectric thin film 26Z, 55Z ZnO piezoelectric thin film 27a, 27b, 57a, 57b Exciting electrodes 28, 56 Piezoelectric laminate 52 Glass substrate 53 Air gap 54 Thin film support

Continuation of the front page (56) References JP-A-2000-165188 (JP, A) JP-A-4-349164 (JP, A) JP-A-3-148186 (JP, A) JP-A-60-126907 (JP, A A) JP-A-60-68711 (JP, A) JP-A-7-254836 (JP, A) JP-A-58-137317 (JP, A) JP-A-7-30354 (JP, A) −32925 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H 9/17 C23C 14/06 C23C 14/08 H01L 21/205 H01L 41/083 H01L 41/09 H01L 41 / 18 H03H 9/54

Claims (11)

(57) [Claims] An insulator layer is formed on a substrate so that at least a part of the insulator layer is lifted from the substrate. One or more piezoelectric layers of AlN and one or more layers of ZnO A piezoelectric resonator, comprising: a piezoelectric laminate in which a piezoelectric layer is laminated on the insulator layer; and electrodes provided so as to sandwich at least one of the piezoelectric layers constituting the piezoelectric laminate. . (2) On a substrate, at least a part of the substrate
To form an insulator layer so that
One or more piezoelectric layers having a positive temperature coefficient;
One or more piezoelectric layers having a negative temperature coefficient
Placing the laminated piezoelectric laminate on the insulator layer, the
Any piezoelectric layer that composes the piezoelectric laminate
The electrode is provided so as to be sandwiched between the poles.
Piezoelectric resonator. (3) On a substrate, at least a part of the substrate
To form an insulator layer so that
One or more piezoelectric layers having a positive temperature coefficient;
One or more piezoelectric layers having a negative temperature coefficient
Placing the laminated piezoelectric laminate on the insulator layer, the
Sandwich at least one of the piezoelectric layers constituting the piezoelectric laminate
Electrodes in such a way that the temperature coefficient of the resonance frequency is negative.
The piezoelectric layer is made of ZnO, LiNbO. _3. LiTaO
₃ , PbZr _X Ti _(1-X) O ₃ [0 ≦ x ≦ 0 . 5
2) Any one of the piezoelectric materials as the main component
A piezoelectric resonator characterized in that: (4) On a substrate, at least a part of the substrate
To form an insulator layer so that
One or more piezoelectric layers having a positive temperature coefficient;
One or more piezoelectric layers having a negative temperature coefficient
Placing the laminated piezoelectric laminate on the insulator layer, the
Sandwich at least one of the piezoelectric layers constituting the piezoelectric laminate
The temperature coefficient of the resonance frequency is positive.
The piezoelectric layer is made of AlN, PbZr _X Ti _(1-X)
O ₃ [0 . 54 ≦ x ≦ 1] as a main component
A piezoelectric resonator characterized in that: (5) On a substrate, at least a part of the substrate
To form an insulator layer so that
One or more piezoelectric layers having a positive temperature coefficient;
One or more piezoelectric layers having a negative temperature coefficient
Placing the laminated piezoelectric laminate on the insulator layer, the
Sandwich at least one of the piezoelectric layers constituting the piezoelectric laminate
Electrodes are provided as described above, and the insulator layer is formed of SiO 2 ₂ or
A piezoelectric element characterized by comprising SiN as a main component.
pendulum. 6. Any of the piezoelectric layer constituting the piezoelectric layered body, characterized in that it is sandwiched between one of the electrodes, the piezoelectric resonator according to claim 1 or 3-5. 7. The piezoelectric layer having a negative temperature coefficient of resonance frequency is made of ZnO, LiNbO ₃ , LiTaO ₃ , PbZr.
7. The piezoelectric resonance according to claim 2 , wherein the piezoelectric material is mainly composed of a piezoelectric material of _X Ti _(1-X) O ₃ [0 ≦ x ≦ 0.52]. Child. 8. The piezoelectric layer temperature coefficient of resonant frequency is _{positive, AlN, PbZr X Ti (1} -X) O 3 [0.5
4 ≦ x ≦ 1] as a main component, and the piezoelectric resonator according to claim 2, 3 or 5-7 . Wherein said insulator layer is characterized by being composed of SiO ₂ or SiN as a main component, the piezoelectric resonator according to claim 1-4 or 6-8. 10. An electronic component using the piezoelectric resonator according to any one of claims 1-9. 11. An electronic apparatus using the piezoelectric resonator according to any one of claims 1-9.