JP2010147874A - Baw resonance device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a BAW resonance device that can improve crystallinity of piezoelectric layers and mechanical quality factors of entire resonators and can be ruggedized, and to provide a method of manufacturing the same. <P>SOLUTION: The piezoelectric layer 32 in the resonator 3 at one surface side of a support substrate 1 is formed by PZT. A lower electrode 31 of the resonator 3 and a cavity 1a, which exposes the surface of the side of the support substrate 1 in an insulating layer 4, are formed on the support substrate 1. An etching hole 5 communicating with the cavity 1a is formed in the insulating layer 4. The support substrate 1 includes a lamination structure of upper- and lower-layer substrates 11, 12 having mutually different thicknesses. The upper-layer substrate 11 exists at a side relatively closer to the resonator 3 on the support substrate 1, comprises a single crystal MgO substrate, and is thinner than the lower-layer substrate 12 existing at a side relatively far from the resonator 3. The cavity 1a includes an opening that penetrates in a thickness direction of the upper-layer substrate 11 and communicates with an etching hole 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 cavity 1a ′ is formed to expose the surface on the 1 ′ side so that the piezoelectric layer 32 ′ can be physically vibrated, and communicates with the cavity 1a ′ at the periphery of the resonator 3 ′ in the support layer 7 ′. Four slit-shaped etching holes 5 ′ for forming cavities 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, ethylenediamine pyrocatechol aqueous solution) for etching the support substrate 1 ′ made of the Si substrate through the etching hole 5 ′ when the cavity 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 filter for UWB (Ultra Wide Band). 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. A lead-based piezoelectric material (for example, PZT, PMN-PZT, etc.) is adopted, and MgO or SrTiO ₃ (: STO) is adopted as the material of the support substrate 1 ′ in order to improve the crystallinity of the piezoelectric layer 32 ′. Conceivable.
JP-A-9-130199

  By the way, in the BAW resonance apparatus having the configuration shown in FIG. 8, 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 resonance device having the configuration shown in FIG. 8, the resonator 3 ′ is formed on the support layer 7 ′ on the one surface side of the support substrate 1 ′ made of a single crystal Si substrate, so that the crystallinity is good. It is difficult to obtain a piezoelectric layer 32 ', and improvement in crystallinity of the piezoelectric layer 32' has been desired.

  Further, in the BAW resonance apparatus having the configuration shown in FIG. 8, even if a single crystal MgO substrate or a single crystal STO substrate is used as the support substrate 1 ′ instead of the single crystal Si substrate, the resonator 3 ′ is on the support layer 7 ′. Therefore, it is difficult to obtain the piezoelectric layer 32 ′ having good crystallinity. In the BAW resonator having the configuration shown in FIG. 8, when a single crystal MgO substrate or a single crystal STO substrate is used as the support substrate 1 ′ in place of the single crystal Si substrate, the single crystal for forming the cavity 1a ′ is used. The etching time of the MgO substrate becomes long and becomes fragile.

  The present invention has been made in view of the above-mentioned reasons, and its object is to improve the crystallinity of the piezoelectric layer, improve the mechanical quality factor of the entire resonator, and be able to be robust. And providing a manufacturing method thereof.

  According to a first aspect of the present invention, there is provided a support substrate, a resonator formed on one surface side of the support substrate and having a piezoelectric layer made of a PZT material or a KNN material between the lower electrode and the upper electrode, and the support substrate. An insulating layer formed on one surface side and supported by a support substrate and surrounding the resonator in a plan view and holding the resonator, and the support substrate includes a lower electrode of the resonator and a surface on the support substrate side of the insulating layer. A cavity to be exposed is formed, an etching hole communicating with the cavity is formed in the insulating layer, and the support substrate has a laminated structure of an upper layer substrate and a lower layer substrate having different thicknesses. The upper substrate on the side relatively close to the resonator is made of a single crystal MgO substrate or a single crystal STO substrate, and is thinner than the lower layer substrate relatively far from the resonator, and It said cavity is formed through the thickness direction of the upper substrate, characterized by comprising constructed by an opening communicating with the etching holes.

  According to the present invention, the resonator having the piezoelectric layer between the lower electrode and the upper electrode formed on the one surface side of the support substrate, and formed on the one surface side of the support substrate and supported by the support substrate in plan view. And an insulating layer that surrounds the resonator and holds the resonator, the support substrate is formed with a cavity that exposes the lower electrode of the resonator and the surface of the insulating layer on the support substrate side, and the insulating layer Since the etching hole communicating with the cavity is formed, the energy loss of bulk acoustic waves can be reduced, the mechanical quality factor of the entire resonator can be improved, and the piezoelectric layer is formed of PZT material or KNN material. Therefore, the electromechanical coupling coefficient can be increased as compared with the case where the support substrate is formed of AlN or ZnO, and the supporting substrate is different from the upper layer substrate having a different thickness. Since the upper substrate, which has a laminated structure with the layer substrate and is closer to the resonator in the support substrate, is composed of a single crystal MgO substrate or a single crystal STO substrate, the crystallinity of the piezoelectric layer can be improved and resonance The mechanical quality factor of the entire element can be improved, and the upper layer substrate is thinner than the lower layer substrate relatively far from the resonator, and the cavity penetrates in the thickness direction of the upper layer substrate. Since it is constituted by the opening communicated with the etching hole, the etching time required for forming the cavity can be shortened, and robustness can be achieved.

  A second aspect of the present invention is a method for manufacturing a BAW resonator according to the first aspect of the present invention, wherein the single crystal MgO substrate or single unit is bonded to one surface of a lower layer substrate made of a different material and forms a support substrate together with the lower layer substrate. After forming a resonator and an insulating layer on one surface side of the upper layer substrate made of a crystal STO substrate, an etching hole is formed in the insulating layer, and then an etchant is introduced through the etching hole to penetrate in the thickness direction of the upper layer substrate. The cavity formed of a portion is formed by wet etching.

  According to the present invention, it is possible to provide a BAW resonance device that can improve the crystallinity of the piezoelectric layer, improve the mechanical quality factor of the entire resonator, and can be robust.

  According to a third aspect of the present invention, in the second aspect of the present invention, the upper substrate is thinned to a predetermined thickness before the resonator and the etching hole are formed.

  According to the present invention, it is possible to prevent the resonator and the insulating layer from being damaged when the upper layer substrate is thinned, and to further reduce the thickness of the upper layer substrate. The etching time for forming the film can be further shortened.

  According to a fourth aspect of the invention, in the third aspect of the invention, the predetermined thickness is set to a value smaller than a side etching amount when the opening is formed by wet etching the upper substrate. It is characterized by.

  According to the present invention, the etching time for forming the opening can be shortened.

  A fifth aspect of the present invention is characterized in that, in the second to fourth aspects of the invention, a single crystal Si substrate is used as the lower layer substrate.

  According to this invention, when the opening is formed, the lower layer substrate can be used as an etching stopper, the reproducibility of the shape of the opening can be improved, and the etching time required for forming the opening Can be shortened.

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

  According to the second aspect of the invention, there is an effect that it is possible to provide a BAW resonance device that can improve the crystallinity of the piezoelectric layer, improve the mechanical quality factor of the entire resonator, and can be robust.

  As shown in FIG. 1, the BAW resonator according to the present embodiment includes a plurality of piezoelectric layers 32 (on a support substrate 1 and on a surface of the support substrate 1 and between a lower electrode 31 and an upper electrode 33 ( In this embodiment, eight) resonators 3 and an 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. And. Further, the BAW resonator of this embodiment has a plurality of (five in this embodiment) cross-sections that expose the surface of the lower electrode 31 of each resonator 3 and the surface of the insulating layer 4 on the side of the support substrate 1 on the support substrate 1. A plurality of inverted trapezoidal cavities 1a are formed by wet etching (wet anisotropic etching utilizing the crystal orientation dependence of the etching rate), and a plurality of (this embodiment) communicate with each of the cavities 1a. Then, five) etching holes 5 are provided. Here, each etching hole 5 is formed in a portion corresponding to the central portion in the projection region of each cavity 1 a in the insulating layer 4. 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 resonance device of the present 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 this embodiment employs PZT as the piezoelectric material of the piezoelectric layer 32, and 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, as long as it is a PZT-based material, not only PZT but also PZT or PMN-PZT to which impurities are added may be used. The electromechanical coupling coefficient can be increased as compared with the case where is AlN or ZnO. In addition, the piezoelectric material of the piezoelectric layer 32 is not limited to a PZT-based material. For example, lead-free KNN (K _0.5 Na _0.5 NbO ₃ ), KN (KNbO ₃ ), NN (NaNbO ₃ ), A KNN-based material such as KNN added with impurities (for example, Li, Nb, Ta, Sb, Cu, etc.) may be used.

  By the way, the whole area of the piezoelectric layer 32 in plan view is formed on the lower electrode 31, and the outer peripheral line of the piezoelectric layer 32 is located inside the outer peripheral line of the lower electrode 31.

  Further, in the BAW resonance device of the present embodiment, Pt is adopted as the metal material of the lower electrode 31, but the material of the lower electrode 31 is not limited to Pt, and becomes a cavity 1a in the upper layer substrate 11 described later. Any metal material may be used as long as it is resistant to an etching solution for forming the opening and has a small lattice constant difference from the piezoelectric material of the piezoelectric layer 32. Further, although Al is adopted as the metal material of the upper electrode 33, the metal material of the upper electrode 33 is representative when not only Al but, for example, Pt, Mo, W, Ir, Cr, Ru or the like is adopted. The mechanical quality factor of the upper electrode 33 can be increased compared to the case of Au, which is a simple electrode material, and the mechanical quality factor of the entire resonator 3 can be increased.

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, the support substrate 1 has a laminated structure of an upper layer substrate 11 and a lower layer substrate 12 having different thicknesses, and the upper layer substrate 11 on the side of the support substrate 1 that is relatively closer to the resonator 3 is a single crystal MgO. It is made of a substrate and is thinner than the lower layer substrate 12 that is relatively far from the resonator 3. In the present embodiment, the thickness of the upper substrate 11 is set to 5 μm, and the thickness of the lower substrate 12 is set to 300 μm. However, these thicknesses are merely examples, and are not particularly limited.

  Further, the support substrate 1 is configured by an opening having an inverted trapezoidal cross section in which the above-described cavity 1 a is provided so as to penetrate in the thickness direction of the upper layer substrate 11.

  Here, as the upper substrate 11, a single crystal MgO substrate having a (001) plane on one surface opposite to the lower substrate 12 side is used, but a single crystal STO substrate having the (001) plane on the one surface is used. It may be used. The plane orientation of the one surface of the upper substrate 11 is not particularly limited, and may be set as appropriate according to the desired plane orientation of the piezoelectric layer 32. Moreover, although the single crystal Si substrate is used as the lower layer substrate 12, a glass substrate may be used.

  According to the BAW resonance apparatus of the present embodiment described above, the resonator 3 formed on the one surface side of the support substrate 1 and having the piezoelectric layer 32 between the lower electrode 31 and the upper electrode 33, and the support substrate 1. An insulating layer 4 that is formed on the one surface side, is supported by the support substrate 1 and surrounds the resonator 3 in a plan view and holds the resonator 3, and the lower electrode 31 of the resonator 3 and the insulating layer 4 are insulated. Since the cavity 1a exposing the surface of the layer 4 on the support substrate 1 side is formed, and the etching hole 5 communicating with the cavity 1a is formed in the insulating layer 4, energy loss of bulk acoustic waves can be reduced. The mechanical quality factor of the entire resonator 3 can be improved. Moreover, in the BAW resonance device of the present embodiment, the support substrate 1 has a laminated structure of the upper layer substrate 11 and the lower layer substrate 12 having different thicknesses, and is relatively closer to the resonator 3 in the support substrate 1. Since the upper substrate 11 is made of a single crystal MgO substrate or a single crystal STO substrate, the crystallinity of the piezoelectric layer 32 made of PZT material or KNN material can be improved and the mechanical quality factor of the entire resonator 3 can be improved. Further, the upper substrate 11 is thinner than the lower substrate 12 that is relatively far from the resonator 3, and the cavity 1 a is an opening that penetrates in the thickness direction of the upper substrate 11 and communicates with the etching hole 5. Since it is comprised by the part, the etching time required for formation of the cavity 1a can be shortened, and solidification becomes possible.

  Hereinafter, a method of manufacturing the BAW resonator according to the present embodiment will be described with reference to FIGS. 3 to 7. In each of FIGS. 3 to 7, the left side is a schematic corresponding to the AA ′ cross section of FIG. Process cross-sectional view, the right side shows a schematic process cross-sectional view corresponding to BB ′ in FIG.

  First, the structure shown in FIG. 3A is obtained by performing a substrate bonding step of bonding the upper layer substrate 11 made of a single crystal MgO substrate and the lower layer substrate 12 made of a single crystal Si substrate. In the substrate bonding step, the upper substrate 11 and the lower substrate 12 may be bonded by, for example, metal-metal (for example, Au—Au) room temperature bonding or eutectic bonding using AuSn. Is not particularly limited.

  After the above-described substrate bonding step, by performing a thinning step of thinning the upper layer substrate 11 from one surface side opposite to the lower layer substrate 12 side to a predetermined thickness (for example, about 5 μm), FIG. ) Is obtained. Here, in the thinning step, for example, the upper substrate 11 may be thinned from the one surface side by CMP or the like, and wet etching may be performed to remove the damaged layer by polishing. The predetermined thickness of the upper substrate 11 is not limited to 5 μm, and may be set as appropriate within a range of about 3 to 50 μm, for example.

  After the above-described thinning step, 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 upper substrate 11 on the one surface side by sputtering, EB vapor deposition, CVD, or the like. The structure shown in FIG. 3C is obtained by performing the first metal film forming step formed by the above.

  Thereafter, a piezoelectric material layer forming process 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 sputtering, CVD, sol-gel, or the like. Then, the structure shown in FIG. 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. 3E is obtained by performing the first resist layer forming step formed on the piezoelectric material layer 32a.

  Thereafter, a piezoelectric material layer patterning step is performed in which the piezoelectric material layer 32a is formed by etching the piezoelectric material layer 32a using the first resist layer 61 as a mask, thereby forming the piezoelectric material layer patterning step shown in FIG. 4), 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. By performing the second resist layer forming step formed on the one surface side, the structure shown in FIG. 4C is obtained.

  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. 4 (d) is obtained, and then the second resist layer 62 is removed to obtain the structure shown in FIG. 4 (e).

Thereafter, an insulating layer forming process 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. By performing the third resist layer forming step, the structure shown in FIG. 5B is obtained.

  After that, by performing an opening portion forming step for forming the opening portion 4a in the insulating layer 4 using a dry etching technique, the structure shown in FIG. 5C is obtained, and then the third resist layer 63 is formed. By removing, the structure shown in FIG. 5D 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. The structure shown in FIG. 5E is obtained by performing the second metal film forming step.

  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. To obtain the structure shown in FIG. 6B, and then the fourth resist layer 64 is removed to obtain the structure shown in FIG. 6C.

  Thereafter, a resist layer (hereinafter referred to as a fifth resist layer) 65 patterned to form the etching hole 5 of the insulating layer 4 on the one surface side of the support substrate 1 is formed using a photolithography technique. By performing the fifth resist layer forming step, the structure shown in FIG. 6D is obtained.

  Thereafter, by using the fifth resist layer 65 as a mask, an etching hole forming step for forming the etching hole 5 by etching the insulating layer 4 by a dry etching technique is performed, thereby obtaining the structure shown in FIG.

Thereafter, by using the fifth resist layer 65 as a mask, a predetermined etchant is introduced through the etching hole 5 and the support substrate 1 is wet-etched to form an opening serving as a cavity 1a in the upper substrate 11 of the support substrate 1. By performing the forming step, the structure shown in FIG. 7B is obtained. When a single crystal MgO substrate is adopted as the upper layer substrate 11, a phosphoric acid solution (for example, a phosphoric acid aqueous solution heated to about 70 to 90 ° C., for example) may be used as the predetermined etchant. 11 is a single crystal STO substrate, the material of the insulating layer 4 is Si ₃ N ₄ , and the liquid temperature is room temperature (for example, 25 ° C.), for example, as a predetermined etchant in the cavity forming step. A hydrofluoric acid aqueous solution having a concentration of 3 wt% may be used.

  After the above-described cavity forming step, the fifth resist layer 65 is removed to obtain a BAW resonator having the structure shown in FIG.

  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, the single crystal MgO substrate or the single crystal STO which is bonded to one surface side of the lower layer substrate 12 made of a different material and forms the support substrate 1 together with the lower layer substrate 12. After the resonator 3 and the insulating layer 4 are formed on the one surface side of the upper substrate 11 made of a substrate, an etching hole 5 is formed in the insulating layer 4, and then an etchant is introduced through the etching hole 5 to form the upper layer substrate 11. Since the cavity 1a having an opening penetrating in the thickness direction is formed by wet etching, the space between the lower electrode 31 and the upper electrode 33 is formed on the one surface side of the upper layer substrate 11 made of a single crystal MgO substrate or a single crystal SrTiO ₃ substrate. Since the resonator 3 having the piezoelectric layer 32 can be directly formed on the support layer 7 'as shown in FIG. Provided is a BAW resonance device that can improve the crystallinity of the piezoelectric layer 32 as well as the mechanical quality factor of the entire resonator 3 and can be robust compared to a case where a manufacturing method for forming 3 ′ is employed. can do.

  Further, according to the method of manufacturing the BAW resonator of the present embodiment, the upper substrate 11 is thinned to the predetermined thickness before the resonator 3 and the etching hole 5 are formed. The resonator 3 and the insulating layer 4 can be prevented from being damaged when the thickness is reduced, and the upper layer substrate 11 is compared with the case where the thickness of the upper layer substrate 11 is reduced after the resonator 3 and the etching hole 5 are formed. Therefore, it is possible to further reduce the etching time when forming the opening serving as the cavity 1a.

  Further, in the present embodiment, the predetermined thickness of the upper substrate 11 is set such that the side etching amount when forming the opening that becomes the cavity 1a by wet etching the upper substrate 11 (this side etching amount is the resonator amount). 3 is set according to the relative positional relationship between the center of 3 and the etching hole 5, and is set to a value smaller than 15 μm in this embodiment (5 μm in this embodiment). Therefore, the etching time when forming the opening can be shortened. In addition, what is necessary is just to set the side etching amount suitably in the range of about 10-100 micrometers.

  In the method for manufacturing the BAW resonator according to this embodiment, since the single crystal Si substrate is used as the lower layer substrate 12, the lower layer substrate 12 is used as an etching stopper when the opening serving as the cavity 1a is formed. In addition, the reproducibility of the shape of the opening can be improved and the etching time required for forming the opening can be shortened.

The BAW resonance apparatus in 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). . 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. 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, (b) is A-A 'schematic sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 1a Cavity 3 Resonator 4 Insulating layer 5 Etching hole 11 Upper layer substrate 12 Lower layer substrate 31 Lower electrode 32 Piezoelectric layer 33 Upper electrode

Claims (5)

  A support substrate, a resonator formed on one surface side of the support substrate and having a piezoelectric layer made of a PZT material or a KNN material between the lower electrode and the upper electrode, and formed on the one surface side of the support substrate. An insulating layer that is supported by the support substrate and surrounds the resonator and holds the resonator in plan view, and a cavity that exposes the lower electrode of the resonator and the surface of the insulating layer on the support substrate side is formed in the support substrate. In addition, an etching hole communicating with the cavity is formed in the insulating layer, and the support substrate has a laminated structure of an upper layer substrate and a lower layer substrate having different thicknesses, and is relatively a resonator in the support substrate. The upper layer substrate on the near side is made of a single crystal MgO substrate or a single crystal STO substrate, and is thinner than the lower layer substrate on the relatively far side from the resonator, and the cavity is an upper layer BAW resonator apparatus characterized by comprising configured by an opening communicating with the etched holes formed through the thickness direction of the plate.   2. The method of manufacturing a BAW resonator according to claim 1, wherein the upper substrate is a single crystal MgO substrate or a single crystal STO substrate that is bonded to one surface side of a lower substrate made of a different material and constitutes a support substrate together with the lower substrate. After forming a resonator and an insulating layer on one surface side, an etching hole is formed in the insulating layer, and then an etchant is introduced through the etching hole to wet the cavity including an opening penetrating in the thickness direction of the upper substrate. A method of manufacturing a BAW resonance device, characterized by being formed by etching.   3. The method of manufacturing a BAW resonator according to claim 2, wherein the upper layer substrate is thinned to a predetermined thickness before forming the resonator and the etching hole.   4. The BAW resonator according to claim 3, wherein the predetermined thickness is set to a value smaller than a side etching amount when the opening is formed by wet etching the upper substrate. Method.   The method for manufacturing a BAW resonance device according to claim 2, wherein a single crystal Si substrate is used as the lower layer substrate.

Images