JP2009290367A - Baw resonance device and method of manufacturing the same - Google Patents

Abstract

A BAW resonator device that can improve the mechanical quality factor of the entire resonator and can be made robust, and a method for manufacturing the same.
A plurality of resonators 3 each having a piezoelectric layer 32 between a lower electrode 31 and an upper electrode 33 are formed on one surface side of a support substrate 1 made of a single crystal substrate. A surrounding insulating layer 4 is formed, and a plurality of inverted trapezoidal cavities 1 a exposing the lower electrode 31 of the resonator 3 and the insulating layer 4 on the one surface of the support substrate 1 utilize the crystal orientation dependence of the etching rate. Formed by wet anisotropic etching. When it is assumed that the cavity 1a is formed by the anisotropic etching through one virtual etching hole 40 of the insulating layer 4, an opening is formed in the virtual formation region of the virtual etching hole 40 in the insulating layer 4 more than the virtual etching hole 40. A group of a plurality of small etching holes 41 is formed.
[Selection] Figure 1

Description

  The present invention relates to a BAW (Bulk Acoustic Wave) resonance device including a resonator using a longitudinal vibration mode in a thickness direction of a piezoelectric layer, and a manufacturing method thereof.

Conventionally, as a BAW resonance device applicable to a high-frequency filter used in a high-frequency band of 2 GHz or more in the field of mobile communication devices such as mobile phones, for example, a support made of a single crystal Si substrate as shown in FIG. A substrate 1 ', a resonator 3' formed on one surface side of the support substrate 1 'and having a laminated structure of a lower electrode 31', a piezoelectric layer 32 ', and an upper electrode 33', and the one surface side of the support substrate 1 ' And a support layer 7 ′ supported by the support substrate 1 ′ and holding the resonator 3 ′, and on the one surface side of the support substrate 1 ′, the support substrate in the support layer 7 ′ below the resonator 3 ′ A recess 1a ′ for exposing the surface on the 1 ′ side and allowing the piezoelectric layer 32 ′ to physically vibrate is formed, and at the periphery of the resonator 3 ′ in the support layer 7 ′, the recess 1a ′ is formed. Four slit-shaped etching holes 5 ′ for forming recesses communicating with the surface are seen in plan view. The piezoelectric layer 32 FBAR comprised formed along each side of the outer peripheral edge of the '(Film Bulk Acoustic Resonator) type BAW resonator shapes have been proposed (e.g., see Patent Document 1). Here, the support layer 7 ′ includes a high-concentration boron doping layer formed by doping boron on the Si substrate that is the basis of the support substrate 1 ′ and SiO ₂ formed on the one surface side of the support substrate 1 ′. And an insulating layer made of a film. In short, the support layer 7 ′ is resistant to an alkaline etching solution (for example, an ethylenediamine pyrocatechol aqueous solution) for etching the support substrate 1 ′ made of the Si substrate through the etching hole 5 ′ when the recess 1a ′ is formed. It is formed with the material which has.

  Patent Document 1 also describes that a filter (BAW filter) is formed by forming a plurality of resonators 3 ′ on the one surface side of the support substrate 1 ′.

In the BAW resonance device described above, PT, PZT, AlN, etc. are adopted as the piezoelectric material of the piezoelectric layer 32 ′, and Si etc. are adopted as the material of the support substrate 1 ′. However, as a UWB (Ultra Wide Band) filter, When applied, as a piezoelectric material of the piezoelectric layer 32 ', it is possible to obtain a bandwidth of about 10% with respect to the center frequency as compared with AlN whose bandwidth is only 4 to 5% with respect to the center frequency. It is conceivable to employ a lead-based piezoelectric material (for example, PZT, PMN-PZT, etc.) and employ MgO or SrTiO ₃ as the material of the support substrate 1 ′ in order to improve the crystallinity of the piezoelectric layer 32 ′.
JP-A-9-130199

  By the way, in the BAW resonator having the configuration shown in FIG. 7, since the support layer 7 ′ is formed under the resonator 3 ′, energy loss of bulk acoustic waves occurs due to the support layer 7 ′, and resonance occurs. There was a problem that the mechanical quality factor (Q value) of the whole child was lowered. Further, in the BAW resonator having the configuration shown in FIG. 7, four slit-like etching holes 5 for forming the recess 1a ′ communicating with the recess 1a ′ are formed in the periphery of the resonator 3 ′ in the support layer 7 ′. Since “is formed along each side of the outer peripheral edge of the piezoelectric layer 32 ′ having a rectangular shape in plan view, there is a problem that it becomes fragile.

  The present invention has been made in view of the above-mentioned reasons, and an object of the present invention is to provide a BAW resonator device that can improve the mechanical quality factor of the entire resonator and can be made robust, and a method for manufacturing the same. is there.

  The invention of claim 1 includes a support substrate made of a single crystal substrate, a resonator formed on one surface side of the support substrate and having a piezoelectric layer between the lower electrode and the upper electrode, and on the one surface side of the support substrate. And an insulating layer that is supported by the support substrate and surrounds the resonator and holds the resonator in plan view, and the lower electrode of the resonator and the surface on the support substrate side of the insulating layer are formed on the one surface of the support substrate. When it is assumed that the exposed cavity is formed by wet anisotropic etching using the crystal orientation dependence of the etching rate, and the cavity is formed by the anisotropic etching through one virtual etching hole of the insulating layer A group of a plurality of etching holes having an opening size smaller than that of the virtual etching hole is formed in a virtual formation region of the virtual etching hole in the insulating layer. And features.

  According to the present invention, the insulating substrate is provided on the one surface side of the support substrate, is supported by the support substrate, surrounds the resonator in a plan view, and holds the resonator. The cavity that exposes the surface on the support substrate side of the lower electrode and the insulating layer is formed by wet anisotropic etching using the crystal orientation dependence of the etching rate, so energy loss of bulk acoustic waves can be reduced In addition, the mechanical quality factor of the entire resonator can be improved, and the virtual etching hole is virtually formed in the insulating layer when it is assumed that the cavity is formed by the anisotropic etching through one virtual etching hole of the insulating layer. Since a group of a plurality of etching holes having an opening size smaller than that of the virtual etching hole is formed in the region, it becomes possible to be robust.

The invention of claim 2 is the invention of claim 1, wherein the single crystal substrate is a single crystal MgO substrate or a single crystal SrTiO ₃ substrate, and the piezoelectric layer is formed of a lead-based piezoelectric material. .

According to this invention, since the piezoelectric layer is formed of a lead-based piezoelectric material, an electromechanical coupling coefficient can be increased as compared with the case where the piezoelectric layer is formed of AlN, and the support substrate is Since it is formed of a single crystal MgO substrate or a single crystal SrTiO ₃ substrate, the crystallinity of the piezoelectric layer can be improved as compared with the case where the support substrate is formed of a single crystal Si substrate. The overall mechanical quality factor can be improved.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the group of etching holes is constituted by four etching holes so that a cross-shaped portion in plan view remains in a virtual formation region in the insulating layer. It is characterized by being made.

  According to this invention, although the opening size of each etching hole is relatively small, the etching time required for forming the cavity can be shortened, and robustness can be achieved.

  According to a fourth aspect of the present invention, in the method for manufacturing a BAW resonance device according to any one of the first to third aspects, the cavity is formed by etching the insulating layer on the one surface side of the support substrate. An etching hole group forming step for forming a group of holes, and an etching solution is introduced through the group of etching holes after the etching hole group forming step to anisotropically etch the support substrate, whereby a cavity is formed on the one surface of the support substrate. And a cavity forming step for forming the structure.

  According to the present invention, in forming the cavity, an etching hole group forming step is performed for forming a group of etching holes in the insulating layer on the one surface side of the support substrate, and then an etching solution is introduced through the group of etching holes. Since the cavity forming process for forming a cavity in the one surface of the support substrate is performed by anisotropically etching the support substrate, the mechanical quality factor of the entire resonator can be improved and the BAW resonance can be made robust An apparatus can be provided.

  According to the first aspect of the present invention, the mechanical quality factor of the entire resonator can be improved, and robustness can be achieved.

  According to the invention of claim 4, there is an effect that it is possible to provide a BAW resonance device that can improve the mechanical quality factor of the entire resonator and can be made robust.

  As shown in FIG. 1, the BAW resonator of this embodiment includes a plurality of resonators having a piezoelectric layer 32 between a lower electrode 31 and an upper electrode 33 on one surface side of a support substrate 1 made of a single crystal substrate. 3 is formed, and an insulating layer 4 surrounding each resonator 3 is formed in a plan view. The lower electrode 31 of the resonator 3 and the surface of the insulating layer 4 on the support substrate 1 side are formed on the one surface of the support substrate 1. A plurality of (in this embodiment, five) cross-sectionally trapezoidal cavities 1a that expose the surface are formed by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate. Further, in the BAW resonator of the present embodiment, a group of a plurality of (four in the present embodiment) etching holes 41 penetrating in the thickness direction of the insulating layer 4 is the center in the projection region of each cavity 1a in the insulating layer 4. Each etching hole 41 communicates with the cavity 1a. The insulating layer 4 has an opening 4a for defining the contact area between the upper electrode 33 and the piezoelectric layer 32.

  Further, in the BAW resonator of the present embodiment, the plurality of resonators 3 described above are connected so as to constitute the ladder type filter shown in FIG. 2, and the cut-off characteristics are steep in a high frequency band of 2 GHz or more and It can be used as a filter having a wide bandwidth, for example, a UWB filter.

  Each resonator 3 includes a lower electrode 31 formed on the one surface side of the support substrate 1, a piezoelectric layer 32 formed on the opposite side of the lower electrode 31 from the support substrate 1 side, and a lower electrode in the piezoelectric layer 32. And an upper electrode 33 formed on the side opposite to the 31 side, and by increasing the acoustic impedance ratio between the lower electrode 31 and the medium immediately below the lower electrode 31, the energy of the bulk acoustic wave toward the support substrate 1 side. The propagation of the signal is suppressed. In short, the BAW filter of this embodiment is configured by an FBAR in which a cavity 1 a is formed in the support substrate 1.

  In the example shown in FIG. 2, a plurality of sets (four sets in the illustrated example) of two resonators 3 in which the lower electrodes 31 are electrically connected to each other are provided. In the resonator 3, the lower electrode 31 and the piezoelectric layer 32 are continuously formed, and the upper electrode 33 is patterned so as to be insulated from each other. Here, between adjacent pairs, the upper electrodes 33 of the two adjacent resonators 3 are electrically connected to each other through a metal wiring 34 formed continuously with the upper electrode 33. Moreover, the area | region which contact | connects both the lower electrode 31 and the upper electrode 33 among the piezoelectric layers 32 formed ranging over the two resonators 3 of each group comprises each resonance area | region.

The BAW resonator of the present embodiment employs PZT as the piezoelectric material of the piezoelectric layer 32, and the support substrate 1 is a single crystal MgO substrate whose main surface is the (001) plane. However, a single crystal SrTiO ₃ substrate having a main surface of (001) plane may be used.

  Further, in the BAW resonance device of the present embodiment, Pt is adopted as the metal material of the lower electrode 31 and the upper electrode 33. However, these metal materials are not particularly limited. For example, Al or other metal materials are used. For example, if at least one selected from the group of Pt, Mo, W, Ir, Cr, Ru is employed, the metal material of each of the lower electrode 31 and the upper electrode 33 is a representative electrode material. As compared with the case of Au, the mechanical quality factor of each of the lower electrode 31 and the upper electrode 33 can be increased, and the mechanical quality factor of the entire resonator 3 can be increased. The lower electrode 31 and the upper electrode 33 are not necessarily made of the same metal material, and the metal material of the lower electrode 31 is a lattice with the piezoelectric material of the piezoelectric layer 32 in order to suppress lattice distortion of the piezoelectric layer 32. It is desirable to use a metal material having a small constant difference.

The piezoelectric layer 32 is composed of a piezoelectric thin film made of a (001) -oriented PZT thin film. Here, although not shown in FIG. 1, it is desirable to form an SRO layer as a seed layer for controlling the orientation of the piezoelectric layer 32 between the lower electrode 31 and the piezoelectric layer 32. In this embodiment, PZT is adopted as the piezoelectric material of the piezoelectric layer 32. However, the piezoelectric material is not limited to PZT, and may be any lead-based piezoelectric material such as PZT or PMN-PZT to which impurities are added. The electromechanical coupling coefficient can be increased as compared with the case where is AlN or ZnO. The piezoelectric material of the piezoelectric layer 32 is not limited to a lead-based piezoelectric material. For example, lead-free KNN (K _0.5 Na _0.5 NbO ₃ ), KN (KNbO ₃ ), NN (NaNbO ₃ ) , KNN added with impurities (for example, Li, Nb, Ta, Sb, Cu, etc.) can also be used.

Here, in the present embodiment, since the support substrate 1 made of a single crystal substrate is composed of a single crystal MgO substrate or a single crystal SrTiO ₃ substrate, compared to the case where the support substrate 1 is made of a single crystal Si substrate, The crystallinity of the piezoelectric layer 32 can be improved, and the mechanical quality factor of the entire resonator 3 can be improved.

As a material of the insulating layer 4, is adopted to SiO _2, is not limited to SiO _2, for example, it may be adopted _Si 3 _{N 4.} The insulating layer 4 is not limited to a single layer structure, and may be a multilayer structure, for example, a laminated film of a first insulating film made of SiO ₂ and a second insulating film made of Si ₃ N ₄ film.

  In the BAW resonator of this embodiment, the resonance frequency of the resonator 3 is set to 4 GHz, the thickness of the lower electrode 31 is set to 100 nm, the thickness of the piezoelectric layer 32 is set to 300 nm, and the thickness of the upper electrode 33 is set to 100 nm. However, these numerical values are examples and are not particularly limited. Moreover, when designing the resonance frequency in the range of 3 GHz to 5 GHz, the thickness of the piezoelectric layer 32 may be set as appropriate in the range of 200 nm to 600 nm.

  By the way, as described above, the BAW resonance device of the present embodiment has an inverted trapezoidal cross section that exposes the lower electrode 31 of the resonator 3 and the surface of the insulating layer 4 on the side of the support substrate 1 on the one surface of the support substrate 1. The cavity 1a is formed by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate, and the cavity 1a is formed with one virtual etching hole 40 (FIG. 1) in the insulating layer 4 in order to form the cavity 1a. A plurality (four) of opening sizes smaller than the virtual etching hole 40 in the virtual formation region of the virtual etching hole 40 in the insulating layer 4 when it is assumed to be formed by the anisotropic etching through (see (d)) The etching holes 41 are formed (a plurality of etching holes 41 are densely formed). Here, the virtual formation region has a square shape, and the group of etching holes 41 includes four etching holes 41 having a square opening shape, and the virtual formation region in the insulating layer 4 has a cross-shaped portion in plan view. Is formed to remain. Although the opening size of each etching hole 41 is set to 1/9 of the opening size of the virtual etching hole 40, the opening size of each etching hole 41 is not particularly limited. Further, the number of etching holes 41 in the group of etching holes 41 is not limited to four, and may be nine, for example, and in this case, it may be formed so that a planar lattice-like portion remains in the virtual formation region.

  According to the BAW resonance device of the present embodiment described above, the insulating layer 4 formed on the one surface side of the support substrate 1 and supported by the support substrate 1 so as to surround the resonator 3 and hold the resonator 3 in plan view. A cavity 1a having an inverted trapezoidal cross section that exposes the lower electrode 31 of the resonator 3 and the surface of the insulating layer 4 on the side of the supporting substrate 1 on the one surface of the supporting substrate 1 utilizes the crystal orientation dependence of the etching rate. Therefore, the energy loss of the bulk acoustic wave can be reduced, the mechanical quality factor of the entire resonator 3 can be improved, and the cavity 1a can be replaced with one virtual layer of the insulating layer 4. The virtual etching hole 4 is formed in the virtual formation region of the virtual etching hole 40 in the insulating layer 4 when it is assumed that the insulating layer 4 is formed by the anisotropic etching through the etching hole 40. Since a plurality of small groups of etching hole 41 of the aperture size is formed than Hardening is possible.

  Further, in the BAW resonator of the present embodiment, the group of the etching holes 41 is configured by the four etching holes 41 so that a cross-shaped portion in plan view remains in the virtual formation region in the insulating layer 4. Therefore, although the opening size of each etching hole 41 is made relatively small, the etching time required for forming the cavity 1a can be shortened and robustness can be achieved.

  Hereinafter, a method for manufacturing the BAW resonator according to the present embodiment will be described with reference to FIGS. 3 to 6. In each of FIGS. 3 to 6, the left side is a schematic corresponding to the BB ′ cross section of FIG. Process sectional drawing, the right side has shown schematic process sectional drawing corresponding to AA 'of Drawing 1 (a).

  First, a first metal film (for example, Pt film) 31a serving as a base of the lower electrode 31 is formed on the entire surface of the support substrate 1 made of a single crystal MgO substrate on the one surface side by sputtering, EB vapor deposition, CVD, or the like. The structure shown in FIG. 3A is obtained by performing the first metal film forming step formed by the above.

  Thereafter, a piezoelectric material layer forming step is performed in which a piezoelectric material layer 32a made of a PZT thin film serving as the basis of the piezoelectric layer 32 is formed on the entire surface of the support substrate 1 by a sputtering method, a CVD method, a sol-gel method, or the like. The structure shown in FIG. 3B is obtained. A seed layer forming step for forming an SRO layer as a seed layer for controlling the orientation of the piezoelectric material layer 32a may be provided between the first metal film forming step and the piezoelectric material layer forming step.

  After the piezoelectric material layer forming step, a resist layer 61 (hereinafter referred to as a first resist layer) 61 patterned to form the piezoelectric layer 32 made of a part of the piezoelectric material layer 32a is used by using a photolithography technique. The structure shown in FIG. 3C is obtained by performing the first resist layer forming step formed on the piezoelectric material layer 32a.

  Thereafter, by using the first resist layer 61 as a mask, the piezoelectric material layer 32a is etched to form a piezoelectric layer 32 made of a part of the piezoelectric material layer 32a, thereby performing a piezoelectric material layer patterning step shown in FIG. 3) is obtained, and then the first resist layer 61 is removed to obtain the structure shown in FIG.

  Thereafter, a resist layer (hereinafter referred to as a second resist layer) 62 patterned to form the lower electrode 31 made of a part of the first metal film 31a is applied to the support substrate 1 by using a photolithography technique. The structure shown in FIG. 4A is obtained by performing the second resist layer forming step formed on the one surface side.

  Thereafter, by performing the first metal film patterning step of forming the lower electrode 31 made of a part of the first metal film 31a by etching the first metal film 31a using the second resist layer 62 as a mask. 4B is obtained, and then the second resist layer 62 is removed to obtain the structure shown in FIG. 4C.

Thereafter, an insulating layer forming step is performed in which an insulating layer 4 made of, for example, a SiO ₂ film is formed on the entire surface of the one surface side of the support substrate 1 by a sputtering method, a CVD method, or the like, whereby the structure shown in FIG. obtain.

  Thereafter, a resist layer (hereinafter referred to as a third resist layer) 63 patterned to form the opening 4a in the insulating layer 4 is formed on the one surface side of the support substrate 1 using a photolithography technique. The structure shown in FIG. 4E is obtained by performing the third resist layer forming step.

  Thereafter, by performing a hole forming process for forming the hole 4a in the insulating layer 4 using a dry etching technique, the structure shown in FIG. 5A is obtained, and then the third resist layer 63 is removed. By doing so, the structure shown in FIG. 5B is obtained.

  Thereafter, a second metal film (for example, a Pt film) 33a serving as a basis for the upper electrode 33 and the metal wiring 34 is formed on the entire surface of the support substrate 1 on the one surface side by sputtering, EB vapor deposition, CVD, or the like. By performing the second metal film forming step, the structure shown in FIG. 5C is obtained.

  Thereafter, a resist layer 64 (hereinafter referred to as a fourth resist layer) 64 patterned to form the upper electrode 33 and the metal wiring 34, each of which is a part of the second metal film 33a, is obtained using a photolithography technique. Then, the fourth resist layer forming step formed on the one surface side of the support substrate 1 is performed to obtain the structure shown in FIG.

  Thereafter, a second metal film patterning step of forming the upper electrode 33 and the metal wiring 34 made of a part of the second metal film 33a by etching the second metal film 33a using the fourth resist layer 64 as a mask. 5A to obtain the structure shown in FIG. 5E, and then the fourth resist layer 64 is removed to obtain the structure shown in FIG.

  Thereafter, a resist layer (hereinafter referred to as a fifth resist layer) 65 patterned to form a group of etching holes 41 of the insulating layer 4 on the one surface side of the support substrate 1 is applied using a photolithography technique. By performing the fifth resist layer forming step to be formed, the structure shown in FIG. 6B is obtained.

  Thereafter, an etching hole group forming step of forming a group of etching holes 41 by etching (dry etching) the insulating layer 4 with a dry etching technique using the fifth resist layer 65 as a mask is performed, as shown in FIG. ) Is obtained.

  Thereafter, using the fifth resist layer 65 as a mask, a predetermined etching solution is introduced through the group of etching holes 41 to anisotropically etch the support substrate 1, thereby forming a cavity 1 a on the one surface of the support substrate 1. By performing the cavity forming step, the structure shown in FIG. 6D is obtained. When an MgO substrate is employed as the support substrate 1, a phosphoric acid solution (for example, a phosphoric acid aqueous solution) may be used as the predetermined etching solution.

  Thereafter, by performing a sixth resist layer removing step for removing the fifth resist layer 65, a BAW resonance device having a structure shown in FIG. 6E is obtained.

  In manufacturing the BAW resonance device described above, a large number of BAW resonance devices may be formed at the wafer level using a wafer as the support substrate 1 described above, and then divided into individual BAW resonance devices in a dicing process. By the way, in the manufacture of the BAW resonator of the present embodiment, the cavity 1a is formed in the support substrate 1 for each of the two resonators 3 in each set in the cavity forming step. Compared with the case where one is formed for every three, the overall size of the BAW resonator can be reduced. Further, the BAW resonator of this embodiment includes a plurality of sets of two resonators 3, but the set of resonators 3 may be one set, and the BAW resonator has only one resonator 3. May be provided.

According to the method for manufacturing the BAW resonator of the present embodiment described above, in forming the cavity 1a, an etching hole group forming step of forming a group of etching holes 41 in the insulating layer 4 on the one surface side of the support substrate 1 is performed. And then performing a cavity forming step of forming a cavity 1a on the one surface of the support substrate 1 by introducing an etchant through the group of etching holes 41 and anisotropically etching the support substrate 1, so that the resonator Thus, it is possible to provide a BAW resonance device that can improve the mechanical quality factor of 3 and can be made robust. Further, according to the above-described method for manufacturing a BAW resonator, the piezoelectric layer 33 is formed between the lower electrode 31 and the upper electrode 33 on the one surface side of the support substrate 1 made of a single crystal MgO substrate or a single crystal SrTiO ₃ substrate. Since the resonator 3 can be directly formed, the crystal of the lower electrode 31 can be compared with the case where the manufacturing method of forming the resonator 3 ′ on the support layer 7 ′ is adopted as shown in FIG. Since the crystallinity of the piezoelectric layer 32 can be improved, the mechanical quality factor of the resonator 3 can be improved.

  In the above-described embodiment, the shape of the cavity 1a is an inverted trapezoidal shape, but the shape of the cavity 1a is not limited to the inverted trapezoidal shape, and may be a V-shaped cross section, for example.

The BAW resonance apparatus of embodiment is shown, (a) is a schematic plan view, (b) is AA 'schematic sectional drawing of (a), (c) is BB' schematic sectional drawing of (a), ( d) is an enlarged view of the main part of (a). It is a circuit diagram of a BAW resonance apparatus same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of a BAW resonance apparatus same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of a BAW resonance apparatus same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of a BAW resonance apparatus same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of a BAW resonance apparatus same as the above. The BAW resonance apparatus of a prior art example is shown, (a) is a schematic plan view, A-A 'schematic sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 1a Cavity 3 Resonator 4 Insulating layer 31 Lower electrode 32 Piezoelectric layer 33 Upper electrode 40 Virtual etching hole 41 Etching hole

Claims (4)

  A support substrate made of a single crystal substrate, a resonator formed on one surface side of the support substrate and having a piezoelectric layer between the lower electrode and the upper electrode, and formed on the one surface side of the support substrate and supported by the support substrate An insulating layer that surrounds the resonator and holds the resonator in a plan view, and the cavity that exposes the lower electrode of the resonator and the surface of the insulating layer on the supporting substrate side has an etching rate on the one surface of the supporting substrate. The virtual etching in the insulating layer when it is assumed that the cavity is formed by the anisotropic etching through one virtual etching hole of the insulating layer, which is formed by wet anisotropic etching utilizing the crystal orientation dependency A group of a plurality of etching holes having a smaller opening size than the virtual etching hole is formed in a virtual hole forming region. Vibration apparatus. 2. The BAW resonance device according to claim 1, wherein the single crystal substrate is a single crystal MgO substrate or a single crystal SrTiO ₃ substrate, and the piezoelectric layer is formed of a lead-based piezoelectric material.   3. The BAW according to claim 1, wherein the group of etching holes includes four etching holes, and is formed so that a cross-shaped portion in plan view remains in a virtual formation region in the insulating layer. Resonant device.   4. The method of manufacturing a BAW resonator according to claim 1, wherein an etching hole group is formed in the insulating layer on the one surface side of the support substrate when forming the cavity. A hole group forming step, and a cavity forming step of forming a cavity in the one surface of the support substrate by introducing an etchant through the group of etching holes and anisotropically etching the support substrate after the etching hole group forming step. A method for manufacturing a BAW resonance device.

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