JP2008042878A - Piezoelectric thin film device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance characteristics of a piezoelectric thin film device including a single or a plurality of piezoelectric thin film resonators by suppressing the sub-resonance of the piezoelectric thin film resonator. <P>SOLUTION: A piezoelectric thin film resonator 1 has such a structure as an adhesive layer 12, a cavity forming film 13, a lower surface electrode 15, a piezoelectric thin film 16 and an upper surface electrode 17 are laminated in this order on a supporting substrate 11. The upper surface electrode 171 is opposed to the lower surface electrode 15 while sandwiching the piezoelectric thin film 16 in an opposite region E1 becoming a vibrating portion. When the periphery of the opposite region E1 is fixed to the piezoelectric thin film resonator 1, the cavity forming film 13 is deposited to cover a range continuous from the periphery of the flat surface 15p of the lower surface electrode 15 to the lower surface of the piezoelectric thin film 16 via the end face 15s of the lower surface electrode 15 at a part constituted of the end face 15s of the lower surface electrode 15 out of the contour of the opposite region E1, and the range is fixed to the supporting substrate 11 through the adhesive layer 12 and the cavity forming film 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric thin film device including one or more piezoelectric thin film resonators.

  Conventionally, a piezoelectric bulk acoustic resonator (FBAR) is formed by sequentially forming a bottom electrode, a piezoelectric thin film, and a top electrode on a support substrate, and the top electrode and the bottom electrode face each other with the piezoelectric thin film interposed therebetween. It was manufactured by forming a cavity below the region (for example, Patent Document 1).

JP 2003-204239 A

  However, in the conventional piezoelectric thin film resonator, an unexpected spurious may be superimposed on the resonance waveform of the main resonance due to the influence of the secondary resonance caused by the vibration energy leaked from the facing region.

  The present invention has been made to solve this problem, and it is an object of the present invention to suppress the sub-resonance of a piezoelectric thin film resonator and improve the characteristics of a piezoelectric thin film device including one or more piezoelectric thin film resonators. .

  In order to solve the above problems, the invention of claim 1 is a piezoelectric thin film device including one or more piezoelectric thin film resonators, wherein the piezoelectric thin film and the first main surface and the second main surface of the piezoelectric thin film are provided. A first electrode and a second electrode that are opposed to each other with the piezoelectric thin film interposed therebetween, a support that supports the piezoelectric thin film from the second main surface side, and an outline of the opposing region Fixing means for fixing a continuous range from the end face of the second electrode to the second main surface of the piezoelectric thin film to the support in the first portion constituted by the end face of the second electrode. Is provided.

  The invention according to claim 2 is a piezoelectric thin film device including one or a plurality of piezoelectric thin film resonators, formed on the piezoelectric thin film and on the first main surface and the second main surface of the piezoelectric thin film, respectively. A first electrode and a second electrode that are opposed to each other with the piezoelectric thin film interposed therebetween, a support that supports the piezoelectric thin film from the side of the second main surface, and the second electrode out of the outline of the facing region In the first portion constituted by the end surface of the second electrode, a continuous range from the peripheral portion of the flat surface of the second electrode to the second main surface of the piezoelectric thin film through the end surface of the second electrode is the support. And fixing means for fixing to.

  According to a third aspect of the present invention, in the second portion other than the first portion of the outline of the counter area, the fixing means is configured so that the flat surface of the second electrode extends from the outline of the counter area to the counter area. The piezoelectric thin film device according to claim 1 or 2, wherein a continuous range leading to an outer edge portion is fixed to the support.

  According to a fourth aspect of the present invention, in the second portion other than the first portion of the outline of the facing region, the fixing means is configured so that the flat surface of the second electrode is spaced from the peripheral portion of the facing region. 3. The piezoelectric thin film device according to claim 1, wherein a continuous range extending from the outer region to the outer edge of the opposite region is fixed to the support.

  The invention according to claim 5 is a piezoelectric thin film device including one or a plurality of piezoelectric thin film resonators, formed on the piezoelectric thin film and the first main surface and the second main surface of the piezoelectric thin film, respectively, The first and second electrodes that face each other with the piezoelectric thin film interposed therebetween, a support that supports the piezoelectric thin film from the second main surface side, and a peripheral portion of the facing region, A fixing means for fixing the range extending to the outer edge of the opposing region to the support through the outer shell, and the first electrode or the second electrode is more mass per unit area than the central portion of the opposing region. Has a large weighted portion at the peripheral edge of the opposing region.

  According to a sixth aspect of the present invention, in the laminated body in which the first electrode, the piezoelectric thin film, and the second electrode are laminated, a reduced portion whose mass per unit area is smaller than that of the central portion of the facing region is used as the weighted portion. Along the weight portion and closer to the center portion.

  The invention of claim 7 is a piezoelectric thin film device including one or a plurality of piezoelectric thin film resonators, formed on the piezoelectric thin film and the first main surface and the second main surface of the piezoelectric thin film, respectively, The first and second electrodes that face each other with the piezoelectric thin film interposed therebetween, a support that supports the piezoelectric thin film from the second main surface side, and a peripheral portion of the facing region, And a fixing means for fixing a range extending to the outer edge of the facing region to the support through the outer shell, and the stacked body in which the first electrode, the piezoelectric thin film, and the second electrode are stacked includes the facing region. And a reduced portion having a mass per unit area smaller than that of the central portion along the outline of the opposing region.

  According to the first to seventh aspects of the invention, the sub-resonance of the piezoelectric thin film resonator can be suppressed, and the characteristics of the piezoelectric thin film device can be improved.

  According to the invention of claim 3, claim 4 or claim 6, it is possible to further suppress the sub-resonance of the piezoelectric thin film resonator.

  In the following, a preferred embodiment of the piezoelectric thin film device of the present invention will be described by taking, as an example, a single piezoelectric thin film resonator and a ladder-type filter combining two piezoelectric thin film resonators (hereinafter referred to as “piezoelectric thin film filter”). explain. However, the following embodiments do not mean that the piezoelectric thin film device of the present invention is limited to a single piezoelectric thin film resonator and a piezoelectric thin film filter. That is, the piezoelectric thin film device in the present invention generally means all piezoelectric thin film devices including one or a plurality of piezoelectric thin film resonators, and an oscillator and a trap including a single piezoelectric thin film resonator. And filters including a plurality of piezoelectric thin film resonators, duplexers, triplexers, traps, and the like. Here, the piezoelectric thin film resonator is a resonator using an electrical response by a bulk acoustic wave that is piezoelectrically excited by a thin film that cannot withstand its own weight without a support.

<1 First Embodiment>
1 to 4 are schematic views showing the configuration of the piezoelectric thin film resonator 1 according to the first embodiment of the present invention. FIG. 1 is a perspective view of the piezoelectric thin film resonator 1 as viewed from an oblique direction, FIG. 2 is a plan view of the piezoelectric thin film resonator 1 as viewed from above, and FIG. 3 is a piezoelectric view taken along the line III-III in FIG. 4 is a cross-sectional view showing a cross section of the piezoelectric thin film resonator 1 taken along the line IV-IV in FIG. For convenience of explanation, FIG. 1 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 1 to 4, the piezoelectric thin film resonator 1 includes an adhesive layer 12, a cavity forming film 13, a lower surface electrode 15, a piezoelectric thin film 16, and an upper surface electrode 17 laminated on a support substrate 11 in this order. It has the structure.

○ Piezoelectric thin films;
The piezoelectric thin film 16 is obtained by removing the piezoelectric substrate. More specifically, the piezoelectric thin film 16 removes a piezoelectric substrate having a thickness that can withstand its own weight (for example, 50 μm or more) to a thickness (for example, 10 μm or less) that cannot withstand its own weight. It can be obtained by thinning.

As the piezoelectric material constituting the piezoelectric thin film 16, a piezoelectric material having desired piezoelectric characteristics can be selected, but quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), Select single crystal materials that do not contain grain boundaries such as lithium tetraborate (Li ₂ B ₄ O ₇ ), zinc oxide (ZnO), potassium niobate (KNbO ₃ ) and langasite (La ₃ Ga ₃ SiO ₁₄ ) It is desirable. This is because by using a single crystal material as the piezoelectric material constituting the piezoelectric thin film 16, the electromechanical coupling coefficient and the mechanical quality factor of the piezoelectric thin film 16 can be improved.

  In addition, as the crystal orientation in the piezoelectric thin film 16, a crystal orientation having desired piezoelectric characteristics can be selected. Here, the crystal orientation in the piezoelectric thin film 16 is preferably a crystal orientation in which the temperature characteristics of the resonance frequency and antiresonance frequency of the piezoelectric thin film resonator 1 are favorable, and the crystal orientation in which the frequency temperature coefficient is “0”. Is more desirable.

  The removal processing of the piezoelectric substrate is performed by mechanical processing such as cutting, grinding and polishing, and chemical processing such as etching. Here, if a plurality of removal processing methods are combined and the piezoelectric substrate is removed while switching the removal processing method step by step from the removal processing method with a high processing speed to the removal processing method with a small process alteration occurring on the processing target. The quality of the piezoelectric thin film 16 can be improved and the characteristics of the piezoelectric thin film resonator 1 can be improved while maintaining high productivity. For example, after performing grinding in which a piezoelectric substrate is brought into contact with fixed abrasive grains and polishing in which a piezoelectric substrate is brought into contact with loose abrasive grains in order, a work-affected layer generated on the piezoelectric substrate by the polishing is finished and polished. If it removes by this, the speed at which the piezoelectric substrate is cut can be increased, the productivity of the piezoelectric thin film resonator 1 can be improved, and the quality of the piezoelectric thin film 16 can be improved. 1 characteristic can be improved. Note that a more specific method of removing the piezoelectric substrate will be described in an example described later.

  In such a piezoelectric thin film resonator 1, unlike the case where the piezoelectric thin film 16 is formed by sputtering or the like, the piezoelectric material constituting the piezoelectric thin film 16 and the crystal orientation in the piezoelectric thin film 16 are not restricted by the base. The degree of freedom in selecting the crystal orientation of the piezoelectric material and the piezoelectric thin film 16 constituting the piezoelectric thin film 16 is high. Therefore, the piezoelectric thin film resonator 1 can easily achieve desired characteristics.

  The piezoelectric thin film 16 penetrates between the upper surface and the lower surface of the piezoelectric thin film 16, and the upper electrode 172 and the lower electrode 15 that face each other with the piezoelectric thin film 16 interposed therebetween in a region other than the facing region E1 are electrically connected. A via hole VH1 is formed. The via hole VH1 short-circuits the upper surface electrode 172 and the lower surface electrode 15 with a conductive thin film formed on the inner surface of the via hole VH1, thereby conducting the current in a DC manner.

○ Top and bottom electrodes;
The upper surface electrode 17 and the lower surface electrode 15 are conductor thin films formed by depositing a conductive material on the upper surface and the lower surface of the piezoelectric thin film 16, respectively. The film thicknesses of the upper surface electrode 17 and the lower surface electrode 15 are determined in consideration of adhesion to the piezoelectric thin film 16, electrical resistance, power resistance, and the like. In order to suppress variations in the resonance frequency and antiresonance frequency of the piezoelectric thin film resonator 1 due to variations in the sound velocity and film thickness of the piezoelectric thin film 16, the film thicknesses of the upper surface electrode 17 and the lower surface electrode 15 are adjusted as appropriate. It may be.

  The conductive material constituting the upper surface electrode 17 and the lower surface electrode 15 is not particularly limited, but aluminum (Al), silver (Ag), copper (Cu), platinum (Pt), gold (Au), chromium (Cr), nickel It is desirable to select from metals such as (Ni), molybdenum (Mo), tungsten (W) and tantalum (Ta). Of course, an alloy may be used as the conductive material constituting the upper electrode 17 and the lower electrode 15. Further, the upper surface electrode 17 and the lower surface electrode 15 may be formed by stacking a plurality of types of conductive materials.

  Among the upper surface electrodes 17, the upper surface electrode 171 is opposed to the lower surface electrode 15 with the piezoelectric thin film 16 interposed therebetween in the facing region E <b> 1 that serves as a vibration part. The upper surface electrode 171 is extracted from the facing region E1 in the −X direction, and the extracted portion serves as a power feeding unit that supplies an excitation signal to the upper surface electrode 171.

  On the other hand, the lower surface electrode 15 is extracted from the facing region E1 in the + X direction, and the extracted portion serves as a power feeding unit that supplies an excitation signal to the lower surface electrode 15.

  Further, among the upper surface electrodes 17, the upper surface electrode 172 is opposed to the power feeding portion of the lower surface electrode 15 with the piezoelectric thin film 16 interposed therebetween in a region other than the facing region E1. Since the upper surface electrode 172 and the lower surface electrode 15 are electrically connected by the via hole VH1, the piezoelectric thin film resonator 1 feeds an excitation signal to the lower surface electrode 15 through the upper surface electrode 172 exposed to the outside.

  The facing region E1 has an elongated two-dimensional shape (rectangular in FIGS. 1 to 4), and the size in the longitudinal direction is more than twice the size in the short direction, more preferably more than four times. More desirably, it is 10 times or more.

  Here, “the elongated two-dimensional shape in which the size in the longitudinal direction is n (n = 2, 4, 10) or more times the size in the short direction” is typically the size in the longitudinal direction. A rectangle with a long side length La longer than the short side length Lb, which is the size in the short side direction, and an aspect ratio La / Lb of n or more (drawn with a solid line in FIG. 5) An ellipse in which the length La of the long axis, which is the size in the longitudinal direction, is longer than the length Lb of the short axis, which is the size in the short direction, and the aspect ratio La / Lb is n or more (Refer to the figure drawn with a solid line in FIG. 6).

  More generally speaking, “a long two-dimensional shape whose length in the longitudinal direction is not less than n times the size in the short direction” is a circumscribed rectangle having the smallest area (indicated by a dotted line in FIGS. 6 to 9). 2) is a two-dimensional shape in which the length La of the long side is not less than n times the length Lb of the short side, and the two-dimensional shape is axially symmetric with respect to both the symmetry axes Sa and Sb perpendicular to each other. In this case, the two-dimensional shape is such that the size in the direction of one symmetry axis Sa is not less than n times the size in the direction of the other symmetry axis Sb.

  Therefore, the opposing region E1 may be an oval shape drawn with a solid line in FIG. 7, a rectangle with rounded vertices drawn with a solid line in FIG. 8, or a solid line in FIG. The drawn vertex may be a rectangle dropped diagonally.

○ Support substrate;
The support substrate 11 supports the piezoelectric substrate on which the lower surface electrode 15 and the cavity forming film 13 are formed on the lower surface via the adhesive layer 12 when the piezoelectric substrate is removed during the manufacturing of the piezoelectric thin film resonator 1. It has a role as a support. In addition, after the piezoelectric thin film resonator 1 is manufactured, the support substrate 11 has the piezoelectric thin film 16 having the lower surface electrode 15 and the cavity forming film 13 formed on the lower surface and the upper surface electrode 17 formed on the upper surface via the adhesive layer 12. It also has a role as a support body that supports. Accordingly, the support substrate 11 is required to be able to withstand the force applied when the piezoelectric substrate is removed, and not to decrease in strength even after the piezoelectric thin film resonator 1 is manufactured.

  The material and thickness of the support substrate 11 can be appropriately selected so as to satisfy such requirements. However, the material of the support substrate 11 is a material having a thermal expansion coefficient close to that of the piezoelectric material constituting the piezoelectric thin film 16, more preferably a material having the same thermal expansion coefficient as the piezoelectric material constituting the piezoelectric thin film 16, for example, a piezoelectric body If the same material as the piezoelectric material constituting the thin film 16 is used, warping and breakage due to the difference in thermal expansion coefficient can be suppressed during the manufacturing of the piezoelectric thin film resonator 1. Thus, characteristic fluctuations and breakage due to the difference in thermal expansion coefficient can be suppressed. When a material having an anisotropic thermal expansion coefficient is used, it is desirable to consider that the piezoelectric thin film 16 and the support substrate 11 have the same thermal expansion coefficient in each direction. When the same piezoelectric material is used for the body thin film 16, it is desirable that the crystal orientations of the support substrate 11 and the piezoelectric thin film 16 are matched.

○ Adhesive layer;
The adhesive layer 12 serves to bond and fix the piezoelectric substrate having the lower surface electrode 15 and the cavity forming film 13 formed on the lower surface to the support substrate 11 when the piezoelectric substrate is removed during the manufacturing process of the piezoelectric thin film resonator 1. have. In addition, after the piezoelectric thin film resonator 1 is manufactured, the adhesive layer 12 adheres the piezoelectric thin film 16 having the lower electrode 15 and the cavity forming film 13 formed on the lower surface and the upper electrode 17 formed on the upper surface to the support substrate 11. It also has a fixing role. Therefore, the adhesive layer 12 is required to be able to withstand the force applied when the piezoelectric substrate is removed and that the adhesive force does not decrease even after the piezoelectric thin film resonator 1 is manufactured.

  Desirable examples of the adhesive layer 12 satisfying such requirements include an organic adhesive, preferably an epoxy adhesive having a filling effect and exhibiting sufficient adhesive force even if the object to be bonded is not completely flat ( Examples thereof include an adhesive layer 12 formed of an epoxy resin adhesive using thermosetting) and an acrylic adhesive (an acrylic resin adhesive using both photo-curing property and thermosetting property). By adopting such a resin, it is possible to prevent an unexpected gap from being generated between the piezoelectric substrate and the support substrate 11 and to prevent a crack or the like from being generated during the removal processing of the piezoelectric substrate by the gap. It is. However, this does not prevent the piezoelectric thin film 16 and the support substrate 11 from being bonded and fixed by the other adhesive layer 12.

○ Cavity forming film;
The cavity forming film 13 is an insulator film obtained by forming an insulating material. The insulating material constituting the cavity forming film 13 is not particularly limited, but is preferably selected from insulating materials such as silicon dioxide (SiO ₂ ).

  The cavity forming film 13 is formed across the region of the piezoelectric thin film 16 other than the facing region E1 and the peripheral portion of the facing region E1, and separates the central portion of the facing region E1 of the piezoelectric thin film 16 from the support substrate 11. A cavity C1 is formed. Here, the peripheral portion of the opposing region E1 is a portion that contacts the outline of the opposing region E1, and the central portion of the opposing region E1 is separated from the outline of the opposing region E1 and is surrounded by the peripheral portion of the opposing region E1. Part.

  That is, in the piezoelectric thin film resonator 1, the peripheral portion of the rectangular opposing region E1 is fixed to the support substrate 11 via the adhesive layer 12 and the cavity forming film 13, so that the vibration related to the vibration excited in the opposing region E1. The energy is prevented from leaking from the facing region E1, and the unexpected sub-resonance is suppressed. In the piezoelectric thin film resonator 1, when fixing the peripheral portion of the opposing region E 1, the peripheral portion of the flat surface 15 p of the lower surface electrode 15 in the portion constituted by the end surface 15 s of the lower surface electrode 15 in the outline of the opposing region E 1. Then, the cavity forming film 13 is formed so as to cover a continuous range from the end surface 15s of the lower surface electrode 15 to the lower surface of the piezoelectric thin film 16, and the range is supported via the adhesive layer 12 and the cavity forming film 13. It is fixed to the substrate 11. Further, in the piezoelectric thin film resonator 1, when the peripheral portion of the facing region E1 is fixed, a portion of the outer surface of the facing region E1 that is not constituted by the end surface 15s of the bottom electrode 15 is formed on the flat surface 15p of the bottom electrode 15. Then, a cavity forming film 13 is formed so as to cover a continuous area from the peripheral edge of the opposing area E1 to the outer edge of the opposing area E1 through the outline of the opposing area E1, and the adhesive layer 12 and the cavity are formed. It is fixed to the support substrate 11 through the film 13. Here, the peripheral part of the opposing area E1 is an area along the inside of the outline of the opposing area E1, and the outer edge part of the opposing area E1 is an area along the outside of the outline of the opposing area E1.

  Here, the flat surface 15p of the lower surface electrode 15 is parallel to the lower surface of the piezoelectric thin film 16, and the end surface 15s of the lower surface electrode 15 is not parallel to the lower surface of the piezoelectric thin film 16 (not necessarily perpendicular). Therefore, the fixing of the peripheral portion of the facing region E1 through the adhesive layer 12 and the cavity forming film 13 is the vibration of the piezoelectric thin film 16 by both normal stress (normal stress) and tangential stress (shear stress). It is a three-dimensional fixing that regulates. According to such three-dimensional fixation, the vibration of the piezoelectric thin film 16 can be strongly restricted at the peripheral portion of the excitation region E1, and vibration energy related to the vibration excited in the opposing region E1 is generated from the opposing region E1. Leakage can be particularly effectively prevented.

  In such three-dimensional fixing, the lower surface of the piezoelectric thin film 16 is polished flat, and the lower surface electrode 15 having a certain film thickness is formed as a partial electrode so as to cover a part of the lower surface. This is realized by obtaining a piezoelectric laminate in which 15 flat surfaces 15p and end surfaces 15s are exposed. Such a piezoelectric laminate with the lower electrode 15 protruding is difficult to obtain with a conventional piezoelectric thin film resonator in which the lower electrode, the piezoelectric thin film, and the upper electrode are formed by sputtering or the like.

  On the other hand, in the piezoelectric thin film resonator 1, the cavity forming film 13 serving as a spacer separates the central portion occupying most of the facing region E1 from the support substrate 11, and vibrations excited in the facing region E1 are generated. Interference with the support substrate 11 is avoided.

  1 to 4, in order to effectively suppress the sub-resonance, the lateral width (± X direction length) Xa and the vertical width (± Y direction length) Ya of the cavity C1 are opposed to each other. The width of the region E1 is made narrower than the horizontal width Xb and the vertical width Yb (Xa ≦ Xb, Ya ≦ Yb), and the cavity C1 is included in the facing region E1 when viewed from above, so that the entire outline of the facing region E1 is Although the example of fixing is shown, it is not essential to fix the entire outline of the facing area E1, and only a part of the outline may be fixed.

  For example, as shown in the plan view of FIG. 10, the lateral width Xa of the cavity C1 is made narrower than the lateral width Xb of the facing area E1 (Xa ≦ Xb), while the longitudinal width Ya of the cavity C1 is made larger than the longitudinal width Yb of the facing area E1. By widening (Ya> Yb), even if the end face 15s of the lower electrode 15 is fixed in the outline of the facing region E1, a practically sufficient sub-resonance suppressing effect can be obtained.

  Alternatively, as shown in the plan view of FIG. 11, the vertical width Ya of the cavity C1 is made narrower than the vertical width Yb of the facing region E1 (Ya ≦ Yb), while the lateral width Xa of the cavity C1 is made smaller than the lateral width Xb of the facing region E1. By widening (Xa> Xb), even if the end face 15s of the lower electrode 15 is fixed in the outline of the facing region E1, a practically sufficient sub-resonance suppressing effect can be obtained.

  Note that the lateral width Xa of the cavity C1 is made narrower than the lateral width Xb of the opposing region E1 (Xa ≦ Xb), as shown in the sectional view of FIG. 12, the lateral width Xa of the cavity C1 and the lateral width Xb of the opposing region E1 are the same. To include. This also applies to the relationship between the vertical width Ya of the cavity C1 and the vertical width Yb of the facing region E1. That is, in the piezoelectric thin film resonator 1, when fixing the outline of the facing area E 1, a portion formed by the end face 15 s of the lower face electrode 15 in the outer face of the facing area E 1 starts from the end face 15 s of the lower face electrode 15. The cavity forming film 13 may be formed so as to cover a continuous range reaching the lower surface of the body thin film 16, and the range may be fixed to the support substrate 11 via the adhesive layer 12 and the cavity forming film 13. Further, in the piezoelectric thin film resonator 1, in fixing the outline of the facing area E1, a portion of the outline of the facing area E1 that is not constituted by the end face 15s of the lower surface electrode 15 extends from the outline of the facing area E1 to the facing area. The cavity forming film 13 may be formed so as to cover a continuous range leading to the outer edge of E1, and the range may be fixed to the support substrate 11 via the adhesive layer 12 and the cavity forming film 13.

  Here, when the lateral width Xa of the cavity C1 is made narrower than the lateral width Xb of the opposing region E1, it is desirable that the lateral width Xa is 70% or more and 100% or less of the lateral width Xb, and the longitudinal width Ya of the cavity C1 is the longitudinal width of the opposing region E1. When narrower than the width Yb, it is desirable that the vertical width Ya is 70% to 100% of the vertical width Yb. More preferably, the lateral width Xa is desirably 80% or more and 100% or less of the lateral width Xb. When the longitudinal width Ya of the cavity C1 is made narrower than the longitudinal width Yb of the opposing region E1, the longitudinal width Ya is 80 of the longitudinal width Yb. % To 100% is better. This is because if the horizontal width Xa or the vertical width Ya falls below this range, the main resonance of the piezoelectric thin film resonator 1 will be affected. If the horizontal width Xa or the vertical width Ya exceeds this range, the sub-resonance suppressing effect will be exerted. This is because of a decrease.

  Further, the present invention can be applied to cases other than the case where the facing region E1 is rectangular. For example, even when the facing region E1 is circular, the cavity Ra is formed over the region other than the facing region E1 and the peripheral edge of the facing region E1, thereby setting the diameter Ra of the cavity C1 to the facing region E1. If the diameter is shorter than the diameter Rb (Ra ≦ Rb) and the cavity C1 is included in the facing region E1 when viewed from above, the secondary resonance can be effectively suppressed.

<2 Second Embodiment>
13 to 17 are schematic views showing the configuration of the piezoelectric thin film filter 2 according to the second embodiment of the present invention. 13 is a perspective view of the piezoelectric thin film filter 2 seen from an oblique direction, FIG. 14 is a plan view of the piezoelectric thin film filter 2 seen from above, and FIG. 15 is a piezoelectric thin film filter taken along the cutting line XV-XV in FIG. FIG. 16 is a cross-sectional view showing a cross section of the piezoelectric thin film filter 2 at the cutting line XVI-XVI in FIG. 13, and FIG. 17 is a view showing two piezoelectric thin film resonances included in the piezoelectric thin film filter 2. It is a circuit diagram which shows the electrical connection of child R21 and R22. For convenience of explanation, FIG. 13 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 13 to 17, the piezoelectric thin film filter 2 can be manufactured in the same procedure as the piezoelectric thin film resonator 1 of the first embodiment, and an adhesive layer 22 and a cavity are formed on a support substrate 21. The film 23, the lower surface electrode 25, the piezoelectric thin film 26, and the upper surface electrode 27 are stacked in this order. The support substrate 21, the adhesive layer 22, the cavity forming film 23, the lower surface electrode 25, the piezoelectric thin film 26, and the upper surface electrode 27 are the support substrate 11, the adhesive layer 12, the cavity forming film 13, and the lower surface electrode 15 of the first embodiment, respectively. The piezoelectric thin film 16 and the upper surface electrode 17 can be made of the same material.

  Here, the pattern of the upper surface electrode 27 and the lower surface electrode 25 different from the piezoelectric thin film resonator 1 of the first embodiment will be described.

  Among the upper surface electrodes 27, the upper surface electrode 271 is opposed to the lower surface electrode 25 with the piezoelectric thin film 26 interposed therebetween in the facing region E21, and constitutes a piezoelectric thin film resonator (series resonator) R22. The upper surface electrode 271 is pulled out from the facing region E21 in the + Y direction, and then the extending direction is sequentially bent in the + X direction and the −Y direction, and the extracted portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 271. Yes. A part of the power feeding unit is a pad P23 to which wiring to the outside is connected.

  The upper surface electrode 272 faces the lower surface electrode 25 across the piezoelectric thin film 26 in the facing region E22, and constitutes a piezoelectric thin film resonator (parallel resonator) R21. The upper surface electrode 272 is pulled out from the facing region E22 in the −Y direction, and then the extending direction is sequentially bent in the −X direction and the + Y direction, and the extracted portion serves as a power feeding unit that feeds an excitation signal to the upper surface electrode 272. ing. A part of the power feeding unit is pads P22 and P24 to which wiring to the outside is connected.

  The upper surface electrode 273 is opposed to the lower surface electrode 25 with the piezoelectric thin film 26 interposed therebetween in a region other than the opposed regions E21 and E22. Since the upper surface electrode 273 and the lower surface electrode 25 are electrically connected by the via hole VH2, the piezoelectric thin film filter 2 supplies an excitation signal to the lower surface electrode 25 through the upper surface electrode 273 exposed to the outside. A part of the upper surface electrode 273 is a pad P21 to which wiring to the outside is connected.

  Due to the upper surface electrode 27 and the lower surface electrode 25, the piezoelectric thin film filter 2 is a ladder-type bandpass filter in which the piezoelectric thin film resonators R21 and R22 are monolithically integrated.

  Similar to the cavity forming film 13 of the first embodiment, the cavity forming film 23 is formed across the region of the piezoelectric thin film 26 other than the facing regions E21 and E22 and the peripheral portions of the facing regions E21 and E22. Cavities C <b> 21 and C <b> 22 that separate the central portions of the opposing regions E <b> 21 and E <b> 22 of the body thin film 26 from the support substrate 23 are formed.

  That is, in the piezoelectric thin film filter 2 as well, the peripheral portions of the rectangular opposing regions E21 and E22 are fixed to the support substrate via the adhesive layer 22 and the cavity forming film 23, so that vibrations excited in the opposing regions E21 and E22 are generated. Such vibration energy is prevented from leaking from the opposed regions E21 and E22, and unexpected sub-resonance is suppressed, and the piezoelectric thin film resonators R21 and R22 are prevented from interfering with each other. In the piezoelectric thin film filter 2, when the peripheral portions of the opposing regions E21 and E22 are fixed, the flat surface 25p of the lower electrode 25 is formed in the portion constituted by the end surface 25s of the lower electrode 25 in the outer area of the opposing regions E21 and E22. A cavity forming film 23 is formed so as to cover a continuous area from the peripheral edge of the piezoelectric thin film 26 to the lower surface of the piezoelectric thin film 26 through the end face 25s of the lower electrode 25, and the adhesive layer 22 and the cavity forming film 23 are formed in the area. To the support substrate 21. Further, in the piezoelectric thin film resonator 1, when fixing the peripheral portions of the facing regions E21 and E22, the portion of the outer surface of the facing regions E21 and E22 that is not constituted by the end surface 25s of the lower surface electrode 25 A cavity forming film 23 is formed so as to cover a continuous area from the peripheral edge of the opposing regions E21 and E22 to the outer edge of the opposing regions E21 and E22 through the outer periphery of the opposing regions E21 and E22 on the flat surface 25p. The range is fixed to the support substrate 21 through the adhesive layer 22 and the cavity forming film 23.

  On the other hand, in the piezoelectric thin film filter 2, the cavity forming film 23 serving as a spacer separates the central portion occupying most of the opposing regions E21 and E22 from the support substrate 11 and is excited by the opposing regions E21 and E22. This prevents the vibrations from interfering with the support substrate 11.

  In the piezoelectric thin film filter 2 as well, the relationship between the lateral width of the cavity C21 (C22) and the lateral width of the facing region E21 (E22), and the longitudinal width of the cavity C21 (C22) and the longitudinal width of the facing region E21 (E22). The relationship can be the same as that of the piezoelectric thin film resonator 1 of the first embodiment, and the facing region E21 and / or E22 can be other than a rectangle.

<3 Third Embodiment>
18 to 21 are schematic views showing the configuration of the piezoelectric thin film resonator 3 according to the third embodiment of the present invention. 18 is a perspective view of the piezoelectric thin film resonator 3 viewed from an oblique direction, FIG. 19 is a plan view of the piezoelectric thin film resonator 3 viewed from above, and FIG. 20 is a piezoelectric view taken along the line XX-XX in FIG. FIG. 21 is a cross-sectional view showing a cross section of the thin-film resonator 3, and FIG. 21 is a cross-sectional view showing a cross-section of the piezoelectric thin-film resonator 3 along the XXI-XXI cutting line of FIG. For convenience of explanation, FIG. 18 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 18 to 21, the piezoelectric thin film resonator 3 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 1 of the first embodiment, and an adhesive layer 32, a cavity is formed on a support substrate 31. The formation film 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 are stacked in this order. The support substrate 31, the adhesive layer 32, the cavity forming film 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 (371, 372) are respectively the support substrate 11, the adhesive layer 12, and the cavity formation of the piezoelectric thin film resonator 1. It corresponds to the film 13, the lower surface electrode 15, the piezoelectric thin film 16 and the upper surface electrode 17 (171, 172), and can be made of the same material as these. Also in the piezoelectric thin film resonator 3, similarly to the piezoelectric thin film resonator 1, the upper surface electrode 372 is a non-opposing region outside the facing region E 31 where the upper surface electrode 371 and the lower surface electrode 35 face each other with the piezoelectric thin film 36 interposed therebetween. In E32, it opposes the lower surface electrode 35 across the piezoelectric thin film 16, and is connected to the lower surface electrode 35 by a via hole VH3.

  Similar to the cavity forming film 13, the cavity forming film 33 is formed across the frame-shaped region RG31 and the non-facing region E32 at the periphery of the facing region E31, and the piezoelectric thin film 36 is formed at the center of the facing region E31. A cavity C3 that is separated from the support substrate 31 is formed. Also in the piezoelectric thin film resonator 3, the relationship between the lateral width of the cavity C3 and the lateral width of the facing region E31 and the relationship between the longitudinal width of the cavity C3 and the longitudinal width of the facing region E31 are the same as those of the piezoelectric thin film resonator 1. The opposing area E31 can be other than a rectangle. This also applies to the piezoelectric thin film resonators 4 to 8 described below.

  That is, in the piezoelectric thin film resonator 3, as in the piezoelectric thin film resonator 1, the piezoelectric thin film 36 is fixed to the support substrate 31 via the adhesive layer 32 and the cavity forming film 33 in the region RG 31 and the non-facing region E 32. By fixing a continuous range from the peripheral edge of the region E31 to the outer edge of the facing region E31 through the outer periphery of the facing region E31, the vibration energy of the vibration excited in the facing region E31 is transferred to the facing region. Leakage from E31 is prevented, and unexpected sub-resonance is suppressed.

  The difference between the piezoelectric thin film resonator 1 and the piezoelectric thin film resonator 3 is that in the piezoelectric thin film resonator 3, the upper surface electrode 372 and the lower surface electrode 35 are conductors having a substantially uniform film thickness, like the upper surface electrode 172 and the lower surface electrode 15. Although it is a thin film, the upper surface electrode 371 is different from the upper surface electrode 171 and is adjacent to the frame-shaped region RG32 and the opposing region E31 on the periphery of the opposing region E31 on the conductive thin film having a substantially uniform film thickness. The conductive film is further overlapped with the rectangular region RG33. In FIG. 19, the hatched weighted portion 371W is formed by partially increasing the thickness of the upper surface electrode 371 beyond the inevitable variation in the regions RG32 and RG33.

  The weighted portion 371W has a larger mass per unit area than the central portion of the facing region E31 where the film thickness is substantially uniform, and plays a role of reducing the cut-off frequency of the elastic wave in the regions RG32 and RG33. Yes. In the piezoelectric thin film resonator 3, the lowering of the cutoff frequency prevents the vibration energy of the vibration excited in the facing region E 31 from leaking from the facing region E 31, and the sub-resonance that depends on the contour shape of the piezoelectric thin film 36. Is suppressed.

  The width w2 of the region RG32 bordering the central portion of the opposing region E31 is preferably 1% to 30% and more preferably 5% to 20% of the width w1 of the opposing region E31. This is because if the width w1 is out of this range, the effect of confining vibration energy is reduced. Here, the width w1 of the facing region E31 is the length of the short side when the shape of the facing region E31 is a rectangle, and the short axis when the shape of the facing region E31 is an ellipse. Length.

  The film thicknesses of the upper surface electrode 37 and the lower surface electrode 35 should be determined according to the conductive material to be formed. However, when tungsten is selected as the conductive material, it is desirable that the film thickness be 700 angstroms or more. This is because when the film thickness of the tungsten film is less than 700 angstroms, the electrical resistance increases, and the resonance resistance of the piezoelectric thin film resonator 3 significantly increases. Also, if the difference in film thickness between the weighted portion 371W and the portion other than the weighted portion 371W is typically about 500 angstroms, the sub-resonance of the piezoelectric thin film resonator 3 can be satisfactorily suppressed.

  Thus, in addition to fixing the peripheral portion of the opposing region E31 to the support substrate 31, when the weighted portion 371W in which the mass per unit area of the upper surface electrode 371 is larger than the central portion of the opposing region E31 is provided at the peripheral portion. In addition to effectively suppressing the sub-resonance, the Q value of the main resonance can be greatly improved.

  The upper surface electrode 371 can be formed by depositing a conductive thin film having a substantially uniform film thickness, and further depositing a conductive thin film on a portion to be the weighted portion 371W. It can also be formed by depositing a thick conductor thin film and thinning the portion other than the portion to be the weighted portion 371W.

  18 to 21 show an example in which the weighted portion 371W is disposed on the upper surface electrode 371, but the weighted portion may be disposed on the lower surface electrode 35 instead of the upper surface electrode 371, or the upper surface electrode 371 and A weighted portion may be disposed on both of the lower surface electrodes 35. Further, if the weighted portion 371W is formed by partially increasing the film thickness of the upper surface electrode 371, the weighted portion 371W can be easily formed. This means that the film thickness of the upper surface electrode 371 is partially increased. In addition to increasing the thickness, or in addition to partially increasing the thickness of the upper surface electrode 371, by partially increasing the specific gravity of the upper surface electrode 371, the formation of the weighted portion 371W is prevented. It is not a thing.

  The reason why the weighted portion 371W is disposed not only in the region R32 but also in the region RG33 serving as the power feeding unit is to reduce the electrical resistance of the power feeding unit. However, this does not preclude placing the weighted portion 371W only in the region R32 and not placing the weighted portion 371W in the region RG33.

  Further, another example of the weighted portion 371W will be described. It is not essential that the width of the region RG32 in which the weighted portion 371W is arranged is constant, for example, as shown in the plan view of FIG. The weighted portion 371W may be disposed across the frame-shaped region RG32 and the rectangular region RG33.

  In addition, even if the thickness of the weighted portion 371W increases as the distance from the central portion of the opposing region E31 increases, and the mass per unit area of the weighted portion 371W increases, the sub-resonance of the piezoelectric thin film resonator 3 is reduced. It can suppress well. Further, such a weighted portion 371W has an advantage that even if the shape of the weighted portion 371W is slightly changed, the effect of suppressing the secondary resonance is not greatly affected.

  For example, the cross-sectional view of FIG. 23 shows an example in which the weighted portion 371W has a staircase shape having a relatively thick portion and a relatively thin portion. FIG. 23 shows an example in which the weighted portion 371W has a two-step staircase shape, but the weighted portion 371W may have a three-step or more staircase shape. Alternatively, as shown in the cross-sectional view of FIG. 24, a slope-shaped weighted portion 371W in which the film thickness continuously increases may be disposed on the upper surface electrode 371.

<4 Fourth Embodiment>
25 to 28 are schematic views showing the configuration of the piezoelectric thin film resonator 4 according to the fourth embodiment of the present invention. 25 is a perspective view of the piezoelectric thin film resonator 4 as viewed obliquely, FIG. 26 is a plan view of the piezoelectric thin film resonator 4 as viewed from above, and FIG. 27 is a piezoelectric view taken along the line XXVII-XXVII in FIG. FIG. 28 is a cross-sectional view showing a cross section of the thin film resonator 4, and FIG. 28 is a cross sectional view showing a cross section of the piezoelectric thin film resonator 4 along the section line XXVIII-XXVIII in FIG. For convenience of explanation, FIG. 25 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 25 to 28, the piezoelectric thin film resonator 4 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 3 of the third embodiment, and an adhesive layer 42 and a cavity are formed on a support substrate 41. The formation film 43, the lower surface electrode 45, the piezoelectric thin film 46, and the upper surface electrode 47 are stacked in this order. The support substrate 41, the adhesive layer 42, the cavity forming film 43, the lower surface electrode 45, the piezoelectric thin film 46, and the upper surface electrode 47 (471, 472) are respectively the support substrate 31, the adhesive layer 32, and the cavity forming film of the third embodiment. 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 (371, 372), and can be made of the same material as these. Also in the piezoelectric thin film resonator 4, as in the piezoelectric thin film resonator 3, the upper surface electrode 472 is a non-opposing region outside the facing region E 41 where the upper surface electrode 471 and the lower surface electrode 45 face each other with the piezoelectric thin film 46 interposed therebetween. In E42, it opposes the lower surface electrode 45 across the piezoelectric thin film 46, and is connected to the lower surface electrode 45 by a via hole VH4.

  Similar to the cavity forming film 33, the cavity forming film 43 is formed across the frame-shaped region RG41 and the non-facing region E42 at the periphery of the facing region E41, and the piezoelectric thin film 46 is formed at the center of the facing region E41. A cavity C4 that is separated from the support substrate 31 is formed.

  Further, in the piezoelectric thin film resonator 4, as with the piezoelectric thin film resonator 3, the upper surface electrode 472 and the lower surface electrode 45 are conductive thin films having a substantially uniform film thickness, but the upper surface electrode 471 is substantially uniform. It has a structure in which a conductive thin film is further stacked on a thin conductive film so as to straddle a frame-shaped region RG42 at the periphery of the opposing region E41 and a rectangular region RG43 adjacent to the opposing region E41. .

  The difference between the piezoelectric thin film resonator 3 and the piezoelectric thin film resonator 4 is that the region RG42 is narrower than the region RG32. That is, in the piezoelectric thin film resonator 3, the width of the frame-shaped region RG32 in which the weighted portion 371W is arranged is wider than the width of the frame-shaped region RG31 fixed to the support substrate 31. In the thin film resonator 4, the width of the frame-shaped region RG42 in which the weighted portion 471W is disposed is narrower than the width of the frame-shaped region RG41 fixed to the support substrate 41.

  In the piezoelectric thin film resonator 4 as well, like the piezoelectric thin film resonator 3, not only the sub-resonance can be effectively suppressed, but also the Q value of the main resonance can be greatly improved.

<5 Fifth Embodiment>
29 to 32 are schematic views showing the configuration of the piezoelectric thin film resonator 5 according to the fifth embodiment of the present invention. 29 is a perspective view of the piezoelectric thin film resonator 5 as viewed from an oblique direction, FIG. 30 is a plan view of the piezoelectric thin film resonator 5 as viewed from above, and FIG. 31 is a piezoelectric diagram taken along a cutting line XXXI-XXXI in FIG. FIG. 32 is a cross-sectional view showing a cross section of the thin film resonator 5, and FIG. 32 is a cross sectional view showing a cross section of the piezoelectric thin film resonator 5 along the line XXXII-XXXII in FIG. 29. For convenience of explanation, FIG. 29 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 29 to 32, the piezoelectric thin film resonator 5 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 3 of the third embodiment, and an adhesive layer 52, a cavity are formed on a support substrate 51. The formation film 53, the lower surface electrode 55, the piezoelectric thin film 56, and the upper surface electrode 57 are stacked in this order. The support substrate 51, the adhesive layer 52, the cavity forming film 53, the lower surface electrode 55, the piezoelectric thin film 56, and the upper surface electrode 57 (571, 572) are respectively the support substrate 31, the adhesive layer 32, and the cavity forming film of the third embodiment. 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 (371, 372), and can be made of the same material as these. Also in the piezoelectric thin film resonator 5, similarly to the piezoelectric thin film resonator 3, the upper surface electrode 572 is a non-facing region outside the facing region E 51 where the upper surface electrode 571 and the lower surface electrode 55 face each other with the piezoelectric thin film 56 interposed therebetween. In E52, the lower electrode 55 is opposed to the lower electrode 55 with the piezoelectric thin film 56 interposed therebetween, and is connected to the lower electrode 55 by a via hole VH5.

  Similar to the cavity forming film 33, the cavity forming film 53 is formed across the peripheral region RG51 and the non-facing region E52 of the facing region E51, and the piezoelectric thin film 56 is attached to the support substrate 51 at the center of the facing region E51. A cavity C5 is formed to be separated from the cavity C5.

  In the piezoelectric thin film resonator 5, as with the piezoelectric thin film resonator 3, the upper surface electrode 572 and the lower surface electrode 55 are conductive thin films having a substantially uniform film thickness, but the upper surface electrode 571 is approximately uniform. It has a structure in which a conductor thin film is further overlapped on a conductive thin film having a thickness over a peripheral region RG52 of the opposing region E51 and a rectangular region RG53 adjacent to the opposing region E51.

  The difference between the piezoelectric thin film resonator 3 and the piezoelectric thin film resonator 5 is that the weighted portion 371W disposed on the upper surface electrode 371 of the piezoelectric thin film resonator 3 is a pair of opposite sides extending in the longitudinal direction of the rectangular opposing region E31. The weighted portion 571W disposed on the upper surface electrode 571 of the piezoelectric thin film resonator 5 is disposed along both the side and the short side which is a pair of opposite sides extending in the lateral direction. It exists in the point which is arrange | positioned along the edge | side and is not arrange | positioned along the short side of the rectangular opposing area | region E51. In other words, the weighted portion 371W has a frame shape that borders the central portion of the opposing region E31 and completely surrounds the central portion, but the weighted portion 571W borders the central portion of the opposing region E51. The frame is partly removed and does not completely surround the center.

  The reason why the weighted portion 571W is provided only along the long side and the weighted portion 571W is not provided along the short side is that the influence of the resonance of the resonator formed by the weighted portion 571W is avoided and the influence of the secondary resonance is less likely. It is to do. That is, as a positive reason, the area of the region RG52 occupied by the weighted portion 571W that forms a resonator having a resonance frequency lower than that of the central portion can be reduced, so that the strength of the sub-resonance superimposed on the low frequency side of the main resonance can be reduced. This is because it can be lowered. Further, as a negative reason, when the opposing region E51 is formed in an elongated two-dimensional shape, the elastic wave of the transverse mode propagates mainly in the direction crossing the long side, so that the weighted portion 571W is made along the short side. This is because the leakage of vibration energy from the facing region E51 can be sufficiently prevented even if it is not arranged.

<6 Sixth Embodiment>
33 to 36 are schematic views showing the configuration of the piezoelectric thin film resonator 6 according to the sixth embodiment of the present invention. FIG. 33 is a perspective view of the piezoelectric thin film resonator 6 as viewed from an oblique direction, FIG. 34 is a plan view of the piezoelectric thin film resonator 6 as viewed from above, and FIG. 35 is a piezoelectric diagram taken along the cutting line XXXV-XXXV in FIG. FIG. 36 is a cross-sectional view showing a cross section of the piezoelectric thin film resonator 6 taken along the line XXXVI-XXXVI in FIG. For convenience of explanation, FIG. 33 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 33 to 36, the piezoelectric thin film resonator 6 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 3 of the third embodiment, and an adhesive layer 62, a cavity is formed on a support substrate 61. The formation film 63, the lower surface electrode 65, the piezoelectric thin film 66, and the upper surface electrode 67 are stacked in this order. The support substrate 61, the adhesive layer 62, the cavity forming film 63, the lower surface electrode 65, the piezoelectric thin film 66, and the upper surface electrode 67 (671, 672) are respectively the support substrate 31, the adhesive layer 32, and the cavity forming film of the third embodiment. 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 (371, 372), and can be made of the same material as these. Also in the piezoelectric thin film resonator 6, similarly to the piezoelectric thin film resonator 3, the upper surface electrode 672 is a non-opposing region outside the facing region E 61 where the upper surface electrode 671 and the lower surface electrode 65 face each other with the piezoelectric thin film 66 interposed therebetween. In E62, it faces the lower electrode 65 with the piezoelectric thin film 66 interposed therebetween, and is connected to the lower electrode 65 by a via hole VH6.

  Similar to the cavity forming film 33, the cavity forming film 63 is formed across the frame-shaped region RG61 and the non-facing region E62 at the peripheral edge of the facing region E61, and the piezoelectric thin film 66 is formed at the center of the facing region E61. A cavity C <b> 6 that is separated from the support substrate 61 is formed.

  In the piezoelectric thin film resonator 6, as with the piezoelectric thin film resonator 3, the upper surface electrode 672 and the lower surface electrode 65 are conductive thin films having a substantially uniform film thickness, but the upper surface electrode 671 is substantially uniform. It has a structure in which a conductor thin film is further superimposed on a frame-shaped region RG62 on the periphery of the opposing region E61 and a rectangular region RG63 adjacent to the opposing region E61 on the conductor thin film having a thickness. .

  The first difference between the piezoelectric thin film resonator 3 and the piezoelectric thin film resonator 6 is that the piezoelectric thin film resonator 3 surrounds the central portion of the facing region E31 with a weighted portion 371W disposed in the region RG32. In the child 6, in addition to the weighted portion 6711W disposed in the region RG621, the center portion of the facing region E61 is double-wrapped by the weighted portion 6712W disposed in the region RG622 inside the child RG621.

  The second difference between the piezoelectric thin film resonator 3 and the piezoelectric thin film resonator 6 is that, in the piezoelectric thin film resonator 3, the thickness of the central portion of the upper surface electrode 371 and the thickness of the lower surface electrode 35 are substantially the same. Whereas the thickness of the weighted portion 371W of the upper surface electrode 371 is larger than the film thickness of the lower surface electrode 35, in the piezoelectric thin film resonator 6, the thickness of the weighted portions 6711W and 6712W of the upper surface electrode 671 and the lower surface electrode 65 are increased. The film thickness at the center of the upper surface electrode 671 is smaller than the film thickness of the lower surface electrode 65.

  In the piezoelectric thin film resonator 6 as well, similarly to the piezoelectric thin film resonator 3, not only the sub-resonance can be effectively suppressed, but also the Q value of the main resonance can be improved, and the weighted portion 671W is formed. Therefore, it is possible to avoid the influence of the resonance of the resonator, and to reduce the strength of the sub-resonance superimposed on the low frequency side of the main resonance.

<7 Seventh Embodiment>
37 to 40 are schematic views showing the configuration of the piezoelectric thin film resonator 7 according to the seventh embodiment of the present invention. 37 is a perspective view of the piezoelectric thin film resonator 7 as viewed from an oblique direction, FIG. 38 is a plan view of the piezoelectric thin film resonator 7 as viewed from above, and FIG. 39 is a piezoelectric view taken along the cutting line XXXIX-XXXIX in FIG. FIG. 40 is a cross-sectional view showing the cross section of the thin film resonator 7, and FIG. 40 is a cross sectional view showing the cross section of the piezoelectric thin film resonator 7 along the line XXXX-XXXX in FIG. 37. In FIG. 37, for convenience of explanation, an XYZ orthogonal coordinate system is defined in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 37 to 40, the piezoelectric thin film resonator 7 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 1 of the first embodiment, and an adhesive layer 72, a cavity are formed on a support substrate 71. The formation film 73, the lower surface electrode 75, the piezoelectric thin film 76, and the upper surface electrode 77 are stacked in this order. The support substrate 71, the adhesive layer 72, the cavity forming film 73, the lower electrode 75, the piezoelectric thin film 76, and the upper electrode 77 (771, 772) are respectively the support substrate 11, the adhesive layer 12, and the cavity forming film of the first embodiment. 13, corresponding to the lower electrode 15, the piezoelectric thin film 16, and the upper electrode 17 (171, 172), and can be made of the same material as these. Also in the piezoelectric thin film resonator 7, similarly to the piezoelectric thin film resonator 1, the upper surface electrode 772 is a non-opposing region outside the facing region E 71 where the upper surface electrode 771 and the lower surface electrode 75 face each other with the piezoelectric thin film 76 interposed therebetween. In E72, the piezoelectric thin film 76 is interposed between the lower electrode 75 and the lower electrode 75, and is connected to the lower electrode 75 via the via hole VH7.

  Similar to the cavity forming film 33, the cavity forming film 73 is formed across the frame-shaped region RG71 and the non-facing region E72 at the peripheral edge of the facing region E71, and the piezoelectric thin film 76 is formed at the center of the facing region E71. A cavity C <b> 7 that is separated from the support substrate 71 is formed.

  That is, in the piezoelectric thin film resonator 7, as in the piezoelectric thin film resonator 1, the piezoelectric thin film 76 is fixed to the support substrate 71 via the adhesive layer 72 and the cavity forming film 73 in the region RG 71 and the non-facing region E 72. By fixing a continuous range from the peripheral edge of the region E71 to the outer edge of the opposing region E71 through the outline of the opposing region E71 to the support substrate 71, the vibration energy of the vibration excited in the opposing region E71 is changed to the opposing region. Leakage from E71 is prevented, and unexpected sub-resonance is suppressed.

  The difference between the piezoelectric thin film resonator 1 and the piezoelectric thin film resonator 7 is that in the piezoelectric thin film resonator 7, the upper surface electrode 772 and the lower surface electrode 75 are conductors having a substantially uniform film thickness, like the upper surface electrode 172 and the lower surface electrode 15. Although it is a thin film, the upper surface electrode 771 is different from the upper surface electrode 171 in that it has a structure in which a reduced portion 771L is formed along the outline of the peripheral edge of the opposing region E71. In FIG. 38, hatched reduction portions 771L partially reduce the thickness of the upper surface electrode 771 beyond the inevitable variation in the region RG75, and form grooves at a certain distance from the outline of the opposing region E71. It is formed by forming. The width of the groove-shaped reduction portion 771L is preferably 1% or more and 30% or less of the width of the facing region E71, and more preferably 5% or more and 15% or less. As for the position of the reduced portion 771L, the distance from the outline of the opposing region E71 to the outside of the reduced portion is preferably 5% to 30% of the width of the opposing region E71, and more preferably 10% to 20%. Is desirable.

  The film thicknesses of the upper surface electrode 77 and the lower surface electrode 75 should be determined according to the conductive material to be formed. However, when tungsten is selected as the conductive material, it is desirable that the film thickness be 700 angstroms or more. This is because, when the film thickness of the tungsten film is less than 700 angstroms, the electrical resistance increases, and the resonance resistance of the piezoelectric thin film resonator 7 significantly increases. Further, when the difference in film thickness between the reduced portion 771L and the portion other than the reduced portion 771L is formed of a tungsten film, typically, if it is about 150 angstroms, the sub-resonance of the piezoelectric thin film resonator 7 is satisfactorily suppressed. be able to.

  The reduced portion 771L has a smaller mass per unit area than the central portion of the opposing region E71 where the film thickness is substantially uniform, and once increases the resonance frequency on the way from the central portion of the excitation region E71 to the outer shell. It plays a role to let you.

  In this way, in addition to fixing the peripheral portion of the opposing region E71 to the support substrate 71, the mass per unit area of the laminated body in which the upper surface electrode 771, the piezoelectric thin film 76, and the lower surface electrode 75 are stacked is equal to that of the opposing region E71. Providing a reduced portion that is smaller than the central portion along the outline of the opposing region E71 not only can effectively suppress the sub-resonance, but also can greatly improve the Q value of the main resonance. The intensity of the sub-resonance superimposed on the low frequency side can be reduced.

  The upper surface electrode 771 can be formed by depositing a conductor thin film having a substantially uniform film thickness and further depositing a conductor thin film on a portion other than the portion to be the reduced portion 771L. It can also be formed by forming a conductive thin film having a thickness and thinning the reduced portion 771L.

  In addition, as shown in FIGS. 5 to 9, when the facing region E71 is axisymmetric with respect to the orthogonal symmetry axes Sa and Sb, it is desirable that the mitigation portion 771L be an axis object with respect to the symmetry axes Sa and Sb. This is because asymmetric mode excitation can be suppressed.

  37 to 40 show an example in which the reduced portion 771L is arranged on the upper surface electrode 771, but the reduced portion 75L is provided on the lower surface electrode 751 instead of the upper surface electrode 771, as shown in the cross-sectional view of FIG. Alternatively, as shown in the cross-sectional view of FIG. 42, the reduction portions 771L and 75L may be disposed on both the upper surface electrode 771 and the lower surface electrode 75.

  In addition, if the reduced portion 771L is formed by partially reducing the thickness of the upper surface electrode 771, the reduced portion 771L can be easily formed. This means that the thickness of the upper surface electrode 771 is partially increased. In addition to making the thickness of the upper electrode 771 partially thin, or in addition to making the film thickness of the upper electrode 771 partially thinner, the specific gravity of the upper electrode 771 is partially reduced to prevent the reduction portion 771L from being formed. It is not a thing. Further, it is not essential to reduce the mass per unit area of the laminate by disposing the reducing portions on the upper surface electrode 771 and the lower surface electrode 75. As shown in the sectional view of FIG. You may make it make the mass per unit area of a laminated body small by arrange | positioning 76L.

  In addition, FIGS. 37 to 40 show an example in which the region RG75 is closer to the center than the region RG71, and the region RG75 and the region RG71 do not overlap, but as shown in the cross-sectional view of FIG. The same effect can be obtained when the region RG75 and the region RG71 overlap, that is, even if the piezoelectric thin film 76 is fixed to the support substrate 71 below the reduction portion 771L.

<8 Eighth Embodiment>
45 to 48 are schematic views showing the configuration of the piezoelectric thin film resonator 8 according to the eighth embodiment of the present invention. 45 is a perspective view of the piezoelectric thin film resonator 8 seen from an oblique direction, FIG. 46 is a plan view of the piezoelectric thin film resonator 8 seen from above, and FIG. 47 is a piezoelectric view taken along the cutting line XLVII-XLVII in FIG. 48 is a cross-sectional view showing a cross section of the thin-film resonator 8, and FIG. 48 is a cross-sectional view showing a cross-section of the piezoelectric thin-film resonator 8 along the cutting line XLVIII-XLVIII in FIG. For convenience of explanation, FIG. 45 defines an XYZ orthogonal coordinate system in which the left-right direction is the X-axis direction, the front-rear direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

  As shown in FIGS. 45 to 48, the piezoelectric thin film resonance 8 can be manufactured by a procedure similar to that of the piezoelectric thin film resonator 3 of the third embodiment, and an adhesive layer 82 and a cavity are formed on a support substrate 81. The film 83, the lower electrode 85, the piezoelectric thin film 86, and the upper electrode 87 are stacked in this order. The support substrate 81, the adhesive layer 82, the cavity forming film 83, the lower surface electrode 85, the piezoelectric thin film 86, and the upper surface electrode 87 (871, 872) are respectively the support substrate 31, the adhesive layer 32, and the cavity forming film of the third embodiment. 33, the lower surface electrode 35, the piezoelectric thin film 36, and the upper surface electrode 37 (371, 372), and can be made of the same material as these. Also in the piezoelectric thin film resonator 8, as in the piezoelectric thin film resonator 3, the upper surface electrode 872 is a non-opposing region outside the facing region E 81 where the upper surface electrode 871 and the lower surface electrode 85 face each other with the piezoelectric thin film 86 interposed therebetween. In E82, it faces the lower surface electrode 85 with the piezoelectric thin film 86 interposed therebetween, and is connected to the lower surface electrode 45 by a via hole VH8.

  Similar to the cavity forming film 33, the cavity forming film 83 is formed across the frame-shaped region RG81 and the non-facing region E82 at the periphery of the facing region E81, and the piezoelectric thin film 86 is formed at the center of the facing region E81. A cavity C <b> 8 that is separated from the support substrate 81 is formed.

  Further, in the piezoelectric thin film resonator 8, as in the piezoelectric thin film resonator 3, the upper surface electrode 872 and the lower surface electrode 85 are conductive thin films having a substantially uniform film thickness, but the upper surface electrode 871 is approximately uniform. It has a structure in which a conductor thin film is further stacked on a conductor thin film having a thickness over a frame-shaped region RG82 at the peripheral edge of the opposing region E81 and a rectangular region RG83 adjacent to the opposing region E81. .

  The difference between the piezoelectric thin film resonator 3 and the piezoelectric thin film resonator 8 is that in the piezoelectric thin film resonator 8, the upper surface electrode 871 has a groove-shaped reduction portion in a region RG85 closer to the center than the weighted portion 871W along the weighted portion 871W. It has the structure which formed 871L. The reduced portion 871L can be formed in the same manner as the reduced portion 771L disposed on the upper surface electrode 771 of the piezoelectric thin film resonator 7.

  As described above, in addition to fixing the peripheral portion of the opposing region E81 to the support substrate 81, a weighted portion where the mass per unit area of the upper surface electrode 871 is larger than the central portion of the opposing region E81 is provided at the peripheral portion. A reduction portion 871L in which the mass per unit area of the laminated body in which the upper surface electrode 871, the piezoelectric thin film 86, and the lower surface electrode 85 are laminated is smaller than the central portion of the opposing region E81 is provided along the outline of the opposing region E71. In addition to effectively suppressing the sub-resonance, the Q value of the main resonance can be significantly improved, and the strength of the sub-resonance superimposed on the low frequency side of the main resonance can be reduced. .

<9 Others>
The technical means described in the first to eighth embodiments can be used in various combinations. For example, the weighted portion 471W in the fourth embodiment, the weighted portion 671W in the sixth embodiment, and the weighted portion 871W in the eighth embodiment can be divided into two sides in the same manner as the weighted portion 571W in the fifth embodiment. Further, the reduced portion 771L in the seventh embodiment and the reduced portion 871L in the eighth embodiment can be made into two sides in the same manner as the weighted portion 571W in the fifth embodiment.

<Example 1>
Hereinafter, Example 1 relating to the piezoelectric thin film resonator 1 according to the first embodiment of the present invention will be described. In the piezoelectric thin film resonator 1 of Example 1, Xa = 18 μm, Xb = 20 μm, Ya = 246 μm, Yb = 250 μm, and the lateral width Xa and the vertical width Ya of the cavity C1 are respectively the lateral width Xb of the facing region E1. And smaller than the vertical width Yb (Xa <Xb, Ya <Yb).

  In the first embodiment, lithium niobate single crystal is used as the piezoelectric material constituting the piezoelectric thin film 16 and the support substrate 11, tungsten is used as the conductive material constituting the upper electrode 17 and the lower electrode 15, and the insulating material is used as the cavity forming film 13. The piezoelectric thin film resonator 1 was manufactured using silicon dioxide and an epoxy adhesive as a material constituting the adhesive layer 12.

  As shown in FIG. 49, the piezoelectric thin film resonator 1 according to the first embodiment integrates a large number (typically several hundred to several thousand) of piezoelectric thin film resonators 1 as shown in FIG. After the assembly (mother substrate) U1 is manufactured, the assembly U1 is cut with a dicing saw and separated into individual piezoelectric thin film resonators 1.

  Hereinafter, for the sake of convenience, the description will be focused on one piezoelectric thin film resonator 1 included in the assembly U1, but other piezoelectric thin film resonators 1 included in the assembly U1 are also considered. Manufactured in parallel.

  Subsequently, a method for manufacturing the piezoelectric thin film resonator 1 according to the first embodiment will be described with reference to cross-sectional views of FIGS. 50 to 51.

  In manufacturing the piezoelectric thin film resonator 1, first, a circular wafer (45-degree cut Y plate) of lithium niobate single crystal having a thickness of 0.5 mm and a diameter of 3 inches was prepared as the piezoelectric substrate 19 and the support substrate 11.

  Then, a tungsten film having a film thickness of 1000 angstroms is formed on the entire lower surface of the piezoelectric substrate 19 by sputtering, and patterning is performed using a general photolithography process, so that the lower surface electrode having the pattern shown in FIGS. 15 was obtained (FIG. 50 (A)).

  Subsequently, a silicon dioxide film having a thickness of 0.5 μm is formed on the entire lower surface of the piezoelectric substrate 19 by sputtering, and the piezoelectric thin film 16 obtained by removing the piezoelectric substrate 19 should become the opposing region E1. The silicon dioxide film formed at the center of the region was removed by wet etching using hydrofluoric acid. As a result, the cavity forming film 13 is formed in a region other than the central portion of the region to be the opposing region E1 in the piezoelectric thin film 16 (FIG. 50B).

  Subsequently, an epoxy adhesive serving as an adhesive layer 12 is applied to the upper surface of the support substrate 11, and the upper surface of the support substrate 11 is bonded to the lower surface of the piezoelectric substrate 19 on which the lower surface electrode 15 and the cavity forming film 13 are formed. It was. Then, pressure was applied to the support substrate 11 and the piezoelectric substrate 19 to perform press-bonding, and the thickness of the adhesive layer 12 was set to 0.5 μm. Thereafter, the bonded support substrate 11 and piezoelectric substrate 19 were left in an environment of 200 ° C. for 1 hour to cure the epoxy adhesive, and the support substrate 11 and piezoelectric substrate 19 were bonded. As a result, a cavity C1 having a depth of about 0.5 μm was formed below the center of the region to be the opposing region E1 in the piezoelectric thin film 16 of the piezoelectric substrate 19 (FIG. 50C).

  After the bonding between the support substrate 11 and the piezoelectric substrate 19 is completed, the lower surface of the support substrate 11 is bonded and fixed to the polishing jig while maintaining the state where the piezoelectric substrate 19 is bonded to the support substrate 11. The upper surface of 19 was ground with a fixed abrasive grinder to reduce the thickness of the piezoelectric substrate 19 to 50 μm. Further, the upper surface of the piezoelectric substrate 19 was polished with diamond abrasive grains to reduce the thickness of the piezoelectric substrate 19 to 2 μm. Finally, in order to remove the work-affected layer generated on the piezoelectric substrate 19 by polishing with diamond abrasive grains, the piezoelectric substrate 19 is subjected to final polishing using loose abrasive grains and a non-woven cloth polishing pad, A piezoelectric thin film 16 having a thickness of 1.00 μm was obtained (FIG. 50D).

  Next, the upper surface (polished surface) of the piezoelectric thin film 16 is washed with an organic solvent, and a chromium film having a thickness of 200 Å and a gold film having a thickness of 2000 Å are sequentially formed on the upper surface of the piezoelectric thin film 16. Then, by patterning the obtained laminated film using a general photolithography process, an etching mask M1 in which only a portion where the via hole VH1 of the piezoelectric thin film 16 is to be formed was obtained (FIG. 51 ( E)).

  After the formation of the etching mask M1, the piezoelectric thin film 16 is etched with buffered hydrofluoric acid heated to 65 ° C. to form a via hole VH1 penetrating between the upper and lower surfaces of the piezoelectric thin film 16 to form the lower surface electrode 15 The etching mask M1 was removed by etching (FIG. 51F).

  Further, a tungsten film having a thickness of 1000 angstroms is formed on the entire upper surface of the piezoelectric thin film 16 by sputtering, and patterning is performed using a general photolithography process, so that the upper surface electrode 17 having the pattern shown in FIGS. (FIG. 51G) was obtained. At this time, since the tungsten film is also formed on the inner side surface of the via hole VH1, conduction between the upper surface electrode 171 and the lower surface electrode 15 is ensured.

  When the frequency-impedance characteristics and frequency-phase characteristics of the piezoelectric thin film resonator 1 thus obtained were measured using an impedance analyzer and the resonance characteristics of the thickness longitudinal vibration were evaluated, the waveform shown in FIG. 52 was observed. It was done.

<Example 2>
Hereinafter, Example 2 relating to the piezoelectric thin film resonator 1 according to the first embodiment of the present invention will be described. In Example 2, Xa = 20 μm, Xb = 20 μm, Ya = 250 μm, Yb = 250 μm, and the horizontal width Xa and the vertical width Ya of the cavity C1 are respectively the same as the horizontal width Xb and the vertical width Yb of the facing region E1 (Xa = Xb, Ya = Yb) A piezoelectric thin film resonator 1 was manufactured in the same procedure as in Example 1, except that

  The piezoelectric thin film resonator 1 manufactured as described above is manufactured in the same procedure as in Example 1, and the frequency-impedance characteristic and the frequency-phase characteristic are measured using an impedance analyzer, and the resonance characteristics of the thickness longitudinal vibration are measured. When evaluated, the waveform shown in FIG. 53 was observed.

<Comparative Example 1>
Below, the comparative example 1 regarding the piezoelectric thin film resonator outside the range of this invention is demonstrated. In the comparative example, Xa = 40 μm, Xb = 20 μm, Ya = 290 μm, Yb = 250 μm, and the lateral width Xa and the vertical width Ya of the cavity C1 were expanded from the lateral width Xb and the vertical width Yb of the facing region E1, respectively (Xa> A piezoelectric thin film resonator was manufactured in the same procedure as in Example 1 except for the point Xb, Ya> Yb).

  When the frequency-impedance characteristics and frequency-phase characteristics of the piezoelectric thin-film resonator thus manufactured were measured using an impedance analyzer and the resonance characteristics of thickness longitudinal vibration were evaluated, the waveform shown in FIG. 54 was observed. It was.

<Contrast of Examples 1 and 2 and Comparative Example 1>
As apparent from FIGS. 52 to 54, the horizontal width Xa and the vertical width Ya of the cavity C1 are set to be equal to or less than the horizontal width Xb and the vertical width Yb of the facing region E1 (Xa ≦ Xb, Ya ≦ Yb), respectively. If the three-dimensional fixing in the outer shell is adopted, spurious superimposed on the main resonance as shown by the arrow in FIG. 54 can be significantly reduced. Further, by using such a piezoelectric thin film resonator 1 alone or in combination, a piezoelectric thin film device having good characteristics, for example, a piezoelectric thin film filter with less ripples can be obtained.

<Example 3>
Hereinafter, Example 3 relating to the piezoelectric thin film resonator 3 according to the third embodiment of the present invention will be described. In the third embodiment, a conductive thin film having a substantially uniform film thickness is formed, and the conductive thin film is further formed on the portion to be the weighted portion 371W to form the weighted portion 371W.

  In the third embodiment, lithium niobate single crystal is used as the piezoelectric material constituting the piezoelectric thin film 36 and the support substrate 31, tungsten is used as the conductive material constituting the upper electrode 37 and the lower electrode 35, and the insulating material is used to form the cavity forming film 33. The piezoelectric thin film resonator 3 was fabricated using silicon dioxide and an epoxy adhesive as a material constituting the adhesive layer 32.

  Similarly to the piezoelectric thin film resonator 1 of the first embodiment, the piezoelectric thin film resonator 3 of the third embodiment is manufactured by forming an assembly in which a large number of piezoelectric thin film resonators 3 are integrated, and then cutting the assembly with a dicing saw. In this way, the piezoelectric thin film resonators 3 are separated into individual piezoelectric thin film resonators 3.

  In the following, for the sake of convenience, the description will be focused on one piezoelectric thin film resonator 3 included in the assembly, but other piezoelectric thin film resonators 3 included in the assembly are also simultaneously parallel with the focused piezoelectric thin film resonator 3. Manufactured.

  Next, a method for manufacturing the piezoelectric thin film resonator 3 according to the third embodiment will be described with reference to cross-sectional views of FIGS.

  In manufacturing the piezoelectric thin film resonator 3, first, a circular wafer (45-degree cut Y plate) of lithium niobate single crystal having a thickness of 0.5 mm and a diameter of 3 inches was prepared as the piezoelectric substrate 39 and the support substrate 31.

  Then, a tungsten film having a film thickness of 1000 angstroms is formed on the entire lower surface of the piezoelectric substrate 39 by sputtering, and patterned by using a general photolithography process, so that the lower surface electrode having the pattern shown in FIGS. 35 was obtained (FIG. 55 (A)).

  Subsequently, a silicon dioxide film having a thickness of 0.5 μm is formed on the entire lower surface of the piezoelectric substrate 39 by sputtering, and hydrofluoric acid is used for the silicon dioxide film formed in regions other than the region RG31 and the non-opposing region E32. It was removed by wet etching. Thus, the cavity forming film 33 is formed in the region RG31 and the non-facing region E32 (FIG. 55B).

  Subsequently, an epoxy adhesive serving as an adhesive layer 32 is applied to the upper surface of the support substrate 31, and the upper surface of the support substrate 31 is bonded to the lower surface of the piezoelectric substrate 39 on which the lower electrode 35 and the cavity forming film 33 are formed. It was. Then, pressure was applied to the support substrate 31 and the piezoelectric substrate 39 to perform press-bonding, and the thickness of the adhesive layer 32 was set to 0.5 μm. Thereafter, the bonded support substrate 31 and piezoelectric substrate 39 were allowed to stand in an environment of 200 ° C. for 1 hour to cure the epoxy adhesive, and the support substrate 31 and the piezoelectric substrate 39 were bonded. As a result, a cavity C3 having a depth of about 0.5 μm was formed below the region to be the opposing region E31 in the piezoelectric thin film 36 of the piezoelectric substrate 39 (FIG. 55C).

  After the bonding between the support substrate 31 and the piezoelectric substrate 39 is completed, the lower surface of the support substrate 31 is bonded and fixed to the polishing jig while maintaining the state where the piezoelectric substrate 39 is bonded to the support substrate 31. The upper surface of 39 was ground with a fixed abrasive grinder to reduce the thickness of the piezoelectric substrate 39 to 50 μm. Further, the upper surface of the piezoelectric substrate 39 was polished with diamond abrasive grains to reduce the thickness of the piezoelectric substrate 39 to 2 μm. Finally, in order to remove the work-affected layer generated on the piezoelectric substrate 39 by polishing with diamond abrasive grains, the piezoelectric substrate 39 is subjected to final polishing using free abrasive grains and a non-woven cloth polishing pad, A piezoelectric thin film 36 having a thickness of 1.00 μm was obtained (FIG. 55D).

  Next, the upper surface (polished surface) of the piezoelectric thin film 36 is washed with an organic solvent, and a chromium film having a film thickness of 200 Å and a gold film having a film thickness of 2000 Å are sequentially formed on the upper surface of the piezoelectric thin film 36. Then, by patterning the obtained laminated film using a general photolithography process, an etching mask M3 in which only the portion where the via hole VH3 is to be formed in the piezoelectric thin film 36 is exposed is obtained (FIG. 56 ( E)).

  After the formation of the etching mask M3, the piezoelectric thin film 36 is etched with buffered hydrofluoric acid heated to 65 ° C. to form a via hole VH3 penetrating between the upper surface and the lower surface of the piezoelectric thin film 36 to form the lower surface electrode 35. And the etching mask M3 was removed by etching (FIG. 56F).

  In the subsequent step of forming the upper surface electrode 37, first, a tungsten film having a film thickness of 500 angstroms is formed on the entire upper surface of the piezoelectric thin film 36 by sputtering, and patterned by using a general photolithography process. The tungsten film 371a was left only in the portion of the electrode 37 that should become the weighted portion 371W (FIG. 56G).

  Further, a tungsten film having a thickness of 1000 angstroms is formed on the entire upper surface of the piezoelectric thin film 36 by sputtering, and patterning is performed using a general photolithography process, so that the patterns shown in FIGS. 33 and 34 are obtained. An upper surface electrode 37 having a weighted portion 371W and having a weighted portion 371W was obtained (FIG. 56H). At this time, since a tungsten film is also formed on the inner surface of the via hole VH3, conduction between the upper surface electrode 372 and the lower surface electrode 35 is ensured.

  Through such steps, the piezoelectric thin film resonator 3 shown in FIGS. 33 to 37 can be manufactured.

<Example 4>
Hereinafter, Example 4 relating to the piezoelectric thin film resonator 7 according to the seventh embodiment of the present invention will be described. In the fourth embodiment, a reduced portion 771L is formed by forming a conductive thin film having a substantially uniform film thickness and thinning a portion to be the reduced portion 771L.

  In Example 7, since the piezoelectric thin film filter 7 is manufactured in the same procedure as in Example 3 except for the process of forming the upper surface electrode 77, only the process of forming the upper surface electrode 77 will be described below.

  The formation process of the upper surface electrode 77 will be described with reference to the cross-sectional view of FIG. 57. First, a tungsten film having a film thickness of 200 angstroms is formed on the entire upper surface of the piezoelectric thin film 76 by sputtering. Patterning was performed using a lithography process, and a tungsten film 77a was formed in a region where the upper surface electrode 77 was to be formed, except for a portion to be the reduced portion 771L (FIG. 57A). At this time, since the tungsten film is also formed on the inner side surface of the via hole VH7, conduction between the upper surface electrode 772 and the lower surface electrode 75 is ensured.

  Further, a tungsten film having a thickness of 1000 angstroms was formed on the tungsten film 77a by sputtering, and an upper electrode 77 having a reduced portion 771L was formed through a photolithography process (FIG. 57B).

  Through such steps, the piezoelectric thin film resonator 7 shown in FIGS. 37 to 40 can be manufactured.

<Example 5>
Hereinafter, Example 5 relating to the piezoelectric thin film resonator 8 according to the eighth embodiment of the present invention will be described. In Example 5, a conductive thin film having a substantially uniform film thickness is formed, and the portion to be the reduced portion 871L is thinned to form the reduced portion 871L, and the portion to be the weighted portion 871W is thickened. Thus, a weighted portion 871W is formed.

  In Example 8, since the piezoelectric thin film filter 8 is manufactured by the same procedure as in Example 3 except for the process of forming the upper surface electrode 87, only the process of forming the upper surface electrode 87 will be described below.

  If an attempt is made to form the top electrode 871 having both the mitigating portion 871L and the weighted portion 871W using a wet photolithography process advantageous for low cost, it is necessary to perform selective etching. It is necessary to configure the electrode 871. For example, the upper surface electrode 871 can be configured by stacking a tungsten film having a thickened portion to be the weighted portion 871W on a tantalum film having a thinned portion to be the reduced portion 871L.

  In this case, first, a tantalum film having a thickness of 200 angstroms is formed by sputtering and patterned by using a general photolithography process, and a portion other than a portion to be the reduced portion 871L in a region where the upper surface electrode 87 is to be formed. Then, a tantalum film 87a is formed (FIG. 58A).

  Further, a tungsten film having a thickness of 500 angstroms is formed on the tantalum film 87a by sputtering, and patterning is performed using a general photolithography process, so that the tungsten film 87b remains in a portion to be the weighted portion 871. Patterning is performed in this manner (FIG. 58B).

  Then, a tungsten film having a film thickness of 1000 angstroms is formed on the tantalum film 87a and the tungsten film 87b by sputtering, and patterning is performed using a general photolithography process, so that the reduced portion 871L and the weighted portion 871W are formed. The provided upper electrode 87 is obtained (FIG. 59).

  Through such steps, the piezoelectric thin film resonator 8 shown in FIGS. 45 to 48 can be manufactured. If a dry photolithography process is used, the cost increases. However, the reduced portion 871L and the weighted portion 871W can be formed of the same conductive material without using a plurality of metals as described here. is there.

1 is a perspective view of a piezoelectric thin film resonator according to a first embodiment of the present invention. 1 is a plan view of a piezoelectric thin film resonator according to a first embodiment of the present invention. It is sectional drawing which shows the cross section of the piezoelectric thin film resonator in the III-III cutting line of FIG. It is sectional drawing which shows the cross section of the piezoelectric thin film resonator in the cutting | disconnection line of IV-IV of FIG. It is a figure which shows the example of a shape of an opposing area | region. It is a figure which shows the example of a shape of an opposing area | region. It is a figure which shows the example of a shape of an opposing area | region. It is a figure which shows the example of a shape of an opposing area | region. It is a figure which shows the example of a shape of an opposing area | region. FIG. 3 is a plan view of a piezoelectric thin film resonator in which a part of the outer area of an opposing region is fixed to a support substrate. FIG. 3 is a plan view of a piezoelectric thin film resonator in which a part of the outer area of an opposing region is fixed to a support substrate. FIG. 3 is a cross-sectional view of a piezoelectric thin film resonator in which the lateral width Xa of the cavity and the lateral width Xb of the opposing region are the same. It is a perspective view of the piezoelectric thin film filter which concerns on 2nd Embodiment of this invention. It is a top view of the piezoelectric thin film filter concerning a 2nd embodiment of the present invention. It is sectional drawing which shows the cross section of the piezoelectric thin film filter in the XX cutting line of FIG. It is sectional drawing which shows the cross section of the piezoelectric thin film filter in the cutting | disconnection line of XI-XI of FIG. It is a circuit diagram which shows the electrical connection of the two piezoelectric thin film resonators contained in a piezoelectric thin film filter. It is a perspective view of the piezoelectric thin film resonator which concerns on 3rd Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 3rd Embodiment of this invention. FIG. 19 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XX-XX in FIG. FIG. 19 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXI-XXI in FIG. 18. It is a top view which shows another example of a weighting part. It is sectional drawing which shows another example of a weighted part. It is sectional drawing which shows another example of a weighted part. It is a perspective view of the piezoelectric thin film resonator which concerns on 4th Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 4th Embodiment of this invention. FIG. 26 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XVII-XXVII in FIG. 25. FIG. 26 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXVIII-XXVIII in FIG. It is a perspective view of the piezoelectric thin film resonator which concerns on 5th Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 5th Embodiment of this invention. FIG. 30 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXI-XXXI in FIG. 29. FIG. 30 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXII-XXXII in FIG. 29. It is a perspective view of the piezoelectric thin film resonator which concerns on 6th Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 6th Embodiment of this invention. FIG. 34 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXV-XXXV in FIG. 33. FIG. 34 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXVI-XXXVI in FIG. 33. It is a perspective view of the piezoelectric thin film resonator which concerns on 7th Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 7th Embodiment of this invention. FIG. 38 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXIX-XXXIX in FIG. FIG. 38 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XXXX-XXXX in FIG. 37. It is sectional drawing which shows another example of the reduction part. It is sectional drawing which shows another example of the reduction part. It is sectional drawing which shows another example of the reduction part. It is sectional drawing which shows another example of the reduction part. It is a perspective view of the piezoelectric thin film resonator which concerns on 8th Embodiment of this invention. It is a top view of the piezoelectric thin film resonator which concerns on 8th Embodiment of this invention. FIG. 46 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XLVII-XLVII in FIG. 45. FIG. 46 is a cross-sectional view of the piezoelectric thin film resonator taken along the line XLVIII-XLVIII in FIG. 45. It is a figure which shows a mode that the aggregate | assembly which integrated many piezoelectric thin film resonators is cut | disconnected and isolate | separated into each piezoelectric thin film resonator. 3 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 1. FIG. 3 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 1. FIG. FIG. 3 is a diagram showing frequency-impedance characteristics of the piezoelectric thin film resonator according to Example 1. 6 is a diagram illustrating frequency-impedance characteristics of a piezoelectric thin film resonator according to Example 2. FIG. 6 is a diagram illustrating frequency-impedance characteristics of a piezoelectric thin film resonator according to Comparative Example 1. FIG. 6 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 2. FIG. 6 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 3. FIG. 6 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 4. FIG. FIG. 10 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 5. FIG. 10 is a diagram illustrating a method for manufacturing a piezoelectric thin film resonator according to Example 5.

Explanation of symbols

1, 2, 3, 4, 5, 6, 7, 8 Piezoelectric thin film resonators 11, 21, 31, 41, 51, 61, 71, 81 Support substrate 12, 22, 32, 42, 52, 62, 72, 82 Adhesive layer 13, 23, 33, 43, 53, 63, 73, 83 Cavity forming film 15, 25, 35, 45, 55, 65, 75, 85 Bottom electrode 16, 26, 36, 46, 56, 66, 76, 86 Piezoelectric thin film 17, 27, 37, 47, 57, 67, 77, 87 Upper surface electrode E1, E21, E22, E31, E41, E51, E61, E71, E81 Counter area

Claims (7)

A piezoelectric thin film device including one or more piezoelectric thin film resonators,
A piezoelectric thin film;
A first electrode and a second electrode formed on the first main surface and the second main surface of the piezoelectric thin film, respectively, facing each other with the piezoelectric thin film interposed therebetween in an opposing region;
A support for supporting the piezoelectric thin film from the second main surface side;
In the first portion constituted by the end face of the second electrode in the outline of the facing region, a continuous range from the end face of the second electrode to the second main surface of the piezoelectric thin film is formed on the support. Fixing means for fixing;
A piezoelectric thin film device comprising: A piezoelectric thin film device including one or more piezoelectric thin film resonators,
A piezoelectric thin film;
A first electrode and a second electrode formed on the first main surface and the second main surface of the piezoelectric thin film, respectively, facing each other with the piezoelectric thin film interposed therebetween in an opposing region;
A support for supporting the piezoelectric thin film from the second main surface side;
In the first portion constituted by the end face of the second electrode in the outline of the opposing region, the first portion of the piezoelectric thin film passes through the end face of the second electrode from the peripheral edge of the flat face of the second electrode. Fixing means for fixing a continuous range to the two principal surfaces to the support;
A piezoelectric thin film device comprising:   The fixing means is continuous from the outer surface of the opposing region to the outer edge of the opposing region on the flat surface of the second electrode in the second portion other than the first portion in the outer region of the opposing region. The piezoelectric thin film device according to claim 1 or 2, wherein a range is fixed to the support.   In the second part other than the first part, the fixing means includes a flat surface of the second electrode, and a peripheral part of the opposing area through an outline of the opposing area in the outer part of the opposing area, 3. The piezoelectric thin film device according to claim 1, wherein a continuous range leading to an outer edge portion of the opposing region is fixed to the support body. A piezoelectric thin film device including one or more piezoelectric thin film resonators,
A piezoelectric thin film;
A first electrode and a second electrode formed on the first main surface and the second main surface of the piezoelectric thin film, respectively, facing each other with the piezoelectric thin film interposed therebetween in an opposing region;
A support for supporting the piezoelectric thin film from the second main surface side;
A fixing means for fixing a range from the peripheral portion of the facing region to the outer edge portion of the facing region through the outline of the facing region to the support;
With
The piezoelectric thin film device according to claim 1, wherein the first electrode or the second electrode has a weighted portion at a peripheral portion of the counter region, which has a mass per unit area larger than that of a central portion of the counter region.   In the laminated body in which the first electrode, the piezoelectric thin film, and the second electrode are laminated, a reduced portion having a mass per unit area smaller than that of the central portion of the opposed region is centered along the weighted portion from the weighted portion. The piezoelectric thin film device according to claim 5, wherein the piezoelectric thin film device is disposed near a portion. A piezoelectric thin film device including one or more piezoelectric thin film resonators,
A piezoelectric thin film;
A first electrode and a second electrode formed on the first main surface and the second main surface of the piezoelectric thin film, respectively, facing each other with the piezoelectric thin film interposed therebetween in an opposing region;
A support for supporting the piezoelectric thin film from the second main surface side;
A fixing means for fixing a range from the peripheral portion of the facing region to the outer edge portion of the facing region through the outline of the facing region to the support;
With
The laminated body in which the first electrode, the piezoelectric thin film, and the second electrode are laminated has a reduced portion that has a mass per unit area smaller than a central portion of the opposing region along the outline of the opposing region. Characteristic piezoelectric thin film device.

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