JP2010147869A - Baw resonance device and method of manufacturing the same - Google Patents

Baw resonance device and method of manufacturing the same Download PDF

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JP2010147869A
JP2010147869A JP2008323856A JP2008323856A JP2010147869A JP 2010147869 A JP2010147869 A JP 2010147869A JP 2008323856 A JP2008323856 A JP 2008323856A JP 2008323856 A JP2008323856 A JP 2008323856A JP 2010147869 A JP2010147869 A JP 2010147869A
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substrate
resonator
single crystal
upper
layer
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Yoshiki Hayazaki
Chomei Matsushima
Takeo Shirai
Norihiro Yamauchi
Takaaki Yoshihara
孝明 吉原
規裕 山内
嘉城 早崎
朝明 松嶋
健雄 白井
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Panasonic Electric Works Co Ltd
パナソニック電工株式会社
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Abstract

A BAW resonance device capable of improving the crystallinity of a piezoelectric layer, improving the mechanical quality factor, and capable of being reduced in size and robustness, and a manufacturing method thereof.
A resonator 3 having a piezoelectric layer 32 between a lower electrode 31 and an upper electrode 33 is formed on one surface side of a support substrate 1, and the support substrate in the lower electrode 31 of the resonator 3 is formed on the support substrate 1. A cavity 1a that exposes the surface on the one side is formed. The piezoelectric material of the piezoelectric layer 32 is a PZT material, and the entire area of the piezoelectric layer 32 in plan view is formed on the lower electrode 31. The support substrate 1 has a laminated structure of an upper layer substrate 11 and a lower layer substrate 12 having different thicknesses. The upper layer substrate 11 is made of a single crystal MgO substrate, is thinner than the lower layer substrate 12, and has a cavity 1a. However, it is constituted by a trapezoidal opening 11a that is penetrating in the thickness direction of the upper substrate 11 by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate.
[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.

  2. Description of the Related Art Conventionally, in the field of mobile communication devices such as cellular phones, FBAR (Film Bulk Acoustic Resonator) type BAW resonator devices applicable to high frequency filters used in a high frequency band of 2 GHz or higher have been researched and developed in various places.

  Further, as a ferroelectric thin film device having the same structure as this type of BAW resonance device, for example, as shown in FIG. 6B, a support substrate 101 made of a single crystal Si substrate, and one surface of the support substrate 101 And a vibrating portion 130 having a laminated structure of a lower electrode 131 made of a Pt film, a ferroelectric thin film 132 made of a PZT thin film, and an upper electrode 133 made of a Pt film. A device in which a gap 141 is formed between the portion 130 and the lower electrode 131 has been proposed (see, for example, Patent Document 1). In manufacturing the ferroelectric thin film device shown in FIG. 6B, the support substrate 101 is formed on the one surface of the support substrate 101 made of a single crystal Si substrate as shown in FIG. A sacrificial thin plate 120 made of a single crystal MgO thin plate or a single crystal STO thin plate having a plane size smaller than the plane size is bonded, and then a lower electrode 131, a ferroelectric thin film 132, and an upper electrode 133 are sequentially formed, and then the sacrificial thin plate is formed. A gap 141 is formed by selectively etching away 120.

  Further, conventionally, as shown in FIG. 7, a resonator 3 ′ having a piezoelectric layer 32 ′ between a lower electrode 31 ′ and an upper electrode 33 ′ is formed on one surface side of the support substrate 1 ′. 1 is a BAW resonance device in which a cavity 1a ′ exposing the surface of the lower electrode 31 ′ of the resonator 3 ′ on the side of the support substrate 1 ′ is formed, and the support substrate 1 ′ is made of a single crystal Si substrate. An opening 11a having a laminated structure of an upper layer substrate 11 ′ and a lower layer substrate 12 ′ made of a single crystal Si substrate and having a cavity 1a ′ penetrating in the thickness direction of the upper layer substrate 11 ′ closer to the resonator 3 ′. A BAW resonance device constituted by 'is proposed (see Patent Document 2).

  In the BAW resonance apparatus having the configuration shown in FIG. 7, the opening 11a ′ is formed only in the upper substrate 11 ′ that is thinner than the entire support substrate 1 ′. Therefore, the dimensional conversion difference of the opening 11a ′ can be reduced. In addition, since the opening 11a ′ is formed by etching from the back surface side of the upper layer substrate 11 ′ at the time of manufacture, compared with a structure in which the cavity 1a ′ is formed by etching from the front surface side of the support substrate 1 ′. , Can be solidified.

  Patent Document 2 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 resonator having the configuration shown in FIG. 7, AlN is used as the piezoelectric material of the piezoelectric layer 32 ′ and Si is used as the material of the support substrate 1 ′. However, a filter for UWB (Ultra Wide Band) is used. As a piezoelectric material for 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. Lead-based piezoelectric materials (for example, PZT, PMN-PZT, etc.) are employed, and MgO or STO (: SrTiO 3 ) is employed as the material of the support substrate 1 ′ in order to improve the crystallinity of the piezoelectric layer 32 ′. Can be considered.
JP-A-8-78735 JP 2005-295250 A

  When the ferroelectric thin film device having the configuration shown in FIG. 6 is applied to a BAW resonance device, the lower electrode 131 made of a Pt film, the ferroelectric thin film 132 made of a PZT thin film, and the upper electrode 133 made of a Pt film, respectively. The film thickness may be changed as appropriate, but a ferroelectric thin film 132 made of a PZT thin film is formed on the one surface side of the support substrate 101 after a sacrificial thin plate is locally bonded on the one surface of the support substrate 101 during manufacturing. Therefore, it is difficult to obtain a PZT thin film with good crystallinity and a desired mechanical quality factor (Q value) cannot be obtained. It has been desired to improve the mechanical quality factor by improving the crystallinity of the PZT thin film.

  Further, in the BAW resonance apparatus having the configuration shown in FIG. 7, the resonator 3 ′ is formed on the upper substrate 11 ′ made of a single crystal Si substrate, and the piezoelectric layer 32 ′ in the resonator 3 ′ has a predetermined structure. Since it is formed so as to straddle the lower electrode 31 ′ and the upper substrate 11 ′, it is difficult to obtain a piezoelectric layer 32 ′ having good crystallinity, and improvement of the crystallinity of the piezoelectric layer 32 ′ is desired. It was.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is to improve the crystallinity of the piezoelectric layer, improve the mechanical quality factor, and reduce the size and robustness of the BAW. An object of the present invention is to provide a resonance apparatus and a manufacturing method thereof.

  According to the first aspect of the present invention, a resonator having a piezoelectric layer between the lower electrode and the upper electrode is formed on one surface side of the support substrate, and the support substrate side surface of the lower electrode of the resonator is exposed to the support substrate. The piezoelectric material of the piezoelectric layer is a PZT-based material or a KNN-based material, and the piezoelectric layer is entirely formed on the lower electrode in a plan view. The upper layer substrate and the lower layer substrate having different thicknesses from each other, the upper layer substrate on the side of the support substrate that is relatively closer to the resonator is made of a single crystal MgO substrate or a single crystal STO substrate, The cavity is thinner than the lower layer substrate on the far side from the resonator, and the cavity is at least in the thickness direction of the upper layer substrate by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate. It is constituted by the opening of the set cross-section trapezoidal, characterized by comprising.

  According to this invention, since the piezoelectric material of the piezoelectric layer is a PZT-based material or a KNN-based material, the electromechanical coupling coefficient can be increased as compared with the case where the piezoelectric layer is formed of AlN, and the support Since the substrate is formed with a cavity that exposes the surface of the lower electrode of the resonator on the side of the support substrate, the resonator can be formed directly on the support substrate at the time of manufacture. Since the entire area in a plan view is formed on the lower electrode, the piezoelectric layer can be easily formed by any of the sputtering method, the sol-gel method, and the CVD method. Since it is formed of a single crystal MgO substrate or a single crystal STO substrate, the crystallinity of the piezoelectric layer can be improved, and the mechanical quality factor can be improved. Since an opening is formed from the back surface side of the thin layer substrate as compared to the underlying substrate, downsizing and hardening.

  According to a second aspect of the present invention, in the first aspect of the invention, the lower substrate is a single crystal Si substrate.

  According to the present invention, the lower substrate can be reduced in cost as compared with the case where the lower substrate is formed of a single crystal MgO substrate or a single crystal STO substrate in the same manner as the upper substrate.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the lower layer substrate has a through hole penetrating in the thickness direction and communicating with the opening, and the through hole is formed in the thickness direction. It is a vertical hole with uniform opening size.

  According to this invention, by forming the opening in the upper layer substrate through the through hole of the lower layer substrate, the through hole and the opening can form the cavity, and the through hole is a vertical hole. Therefore, it can be reduced in size.

  A fourth aspect of the present invention is a method of manufacturing a BAW resonator according to the first or second aspect of the present invention, wherein a single crystal substrate comprising a single crystal MgO substrate or a single crystal STO substrate that is the basis of the upper layer substrate is provided on one surface. A resonator forming step of forming a resonator on the substrate, a thinning step of forming an upper substrate of a predetermined thickness by thinning the single crystal substrate from the other surface side after the resonator forming step, and a thinning step After the opening forming step, the opening is formed on the upper substrate by wet anisotropic etching using the crystal orientation dependence of the etching rate from the side opposite to the resonator side, and after the opening forming step. And a substrate bonding step of forming a support substrate by bonding the upper layer substrate and the lower layer substrate.

  According to the present invention, after a resonator is formed on one surface of a single crystal substrate consisting of a single crystal MgO substrate or a single crystal STO substrate that is the basis of the upper layer substrate, the single crystal substrate is thinned from the other surface side. Then, an upper substrate having a predetermined thickness is formed, and then the opening is formed on the upper substrate from the side opposite to the resonator side by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate, and thereafter Since the support substrate is formed by joining the upper layer substrate and the lower layer substrate, the crystallinity of the piezoelectric layer can be improved, the mechanical quality factor can be improved, and the BAW that can be reduced in size and robustness A resonant device can be provided.

  A fifth aspect of the present invention is a method of manufacturing a BAW resonator according to the third aspect of the present invention, wherein a single crystal substrate consisting of a single crystal MgO substrate or a single crystal STO substrate that is the basis of an upper layer substrate is bonded to a lower layer substrate. A thinning step of forming an upper layer substrate by thinning the single crystal substrate from one surface side opposite to the lower layer substrate side after the bonding step, and an upper layer substrate after the thinning step; A resonator forming step of forming a resonator on the one surface of the substrate, and a through hole forming step of forming the through hole reaching the upper layer substrate from the side opposite to the upper layer substrate side in the lower layer substrate after the resonator forming step And a wet etching step in which the opening is formed in the upper substrate through the through hole after the through hole forming step by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate. To.

  According to the present invention, a single crystal substrate consisting of a single crystal MgO substrate or a single crystal STO substrate that is the basis of an upper layer substrate is bonded to a lower layer substrate, and then the single crystal substrate is placed on one side opposite to the lower layer substrate side. The upper layer substrate is formed by thinning from the surface side, and then a resonator is formed on the one surface of the upper layer substrate, and then the penetration that reaches the upper layer substrate from the side opposite to the upper layer substrate side in the lower layer substrate A hole is formed, and then the opening is formed in the upper substrate through the through hole by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate, so that the crystallinity of the piezoelectric layer can be improved. Thus, it is possible to provide a BAW resonance device that can improve the mechanical quality factor and can be reduced in size and robustness.

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

  According to the fourth and fifth aspects of the invention, it is possible to provide a BAW resonance device that can improve the crystallinity of the piezoelectric layer, improve the mechanical quality factor, and can be downsized and robust. There is.

(Embodiment 1)
As shown in FIG. 1, the BAW resonator of this embodiment includes a plurality of (in this embodiment, eight) piezoelectric layers 32 between the lower electrode 31 and the upper electrode 33 on one surface side of the support substrate 1. However, in FIG. 1, only four resonators 3 are formed, and an insulating layer 4 surrounding each resonator 3 is formed in a plan view. A plurality of trapezoidal cavities 1a exposing the surface of the lower electrode 31 on the side of the support substrate 1 are formed by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate. 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 illustrated in FIG. 2, a plurality of sets (four sets in the present embodiment) of two resonators 3 each having the lower electrodes 31 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 resonator 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 an opening 11 a is formed 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 formation and has a small difference in lattice constant 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 100 μm, and the thickness of the lower substrate 12 is set to 300 μm. However, these thicknesses are only examples and are not particularly limited.

  Further, the support substrate 1 is configured by the above-described cavity 1a including a trapezoidal opening 11a having a trapezoidal cross section penetrating in the thickness direction of the upper substrate 11 by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate. Has been.

  Here, a single crystal MgO substrate is used as the upper substrate 11, but a single crystal STO substrate may be used. Further, as the lower layer substrate 12, a single crystal Si substrate is used, but a single crystal MgO substrate or a single crystal STO substrate may be used. Each of the upper substrate 11 and the lower substrate 12 has a main surface (upper surface in FIG. 1B) having a (001) plane.

  According to the BAW resonance device of the present embodiment described above, since the piezoelectric material of the piezoelectric layer 32 is a PZT-based material or a KNN-based material, the electromechanical coupling coefficient compared to the case where the piezoelectric layer 32 is formed of AlN. Can be increased. Further, according to the BAW resonance apparatus of the present embodiment, the cavity 1a that exposes the surface of the lower electrode 31 of the resonator 3 on the side of the support substrate 1 is formed in the support substrate 1, thereby resonating during manufacture. The child 3 can be formed directly on the support substrate 1, and the entire area of the piezoelectric layer 32 in plan view is formed on the lower electrode 31, so that the piezoelectric layer 32 can be formed by sputtering, sol-gel method or CVD method. Any of these can be easily formed, and the upper substrate 11 serving as the base of the resonator 3 of the support substrate 1 is formed of a single crystal MgO substrate or a single crystal STO substrate, so that the crystallinity of the piezoelectric layer 32 is improved. It is possible to improve the mechanical quality factor. In addition, according to the BAW resonance apparatus of the present embodiment, since the opening 11a is formed from the back surface side of the upper substrate 11 which is thinner than the lower substrate 12, the etching time required for forming the opening 1a can be shortened and the size can be reduced. And can be made robust. By shortening the etching time, it is possible to prevent etching damage from being generated in the piezoelectric layer 32 and the upper electrode 33 when the cavity 1a is formed, and it is possible to prevent a decrease in mechanical quality factor and disconnection. Further, in the BAW resonator of the present embodiment, since the lower layer substrate 12 is composed of a single crystal Si substrate, the lower layer substrate 12 is composed of a single crystal MgO substrate or a single crystal STO substrate in the same manner as the upper layer substrate 11. Compared with this, the cost can be reduced.

  Hereinafter, a method for manufacturing the BAW resonator according to the present embodiment will be described with reference to FIG.

First, by performing a resonator forming step of forming the resonator 3 on one surface of a single crystal substrate 11A made of a single crystal MgO substrate or a single crystal STO substrate that is the basis of the upper layer substrate 11, FIG. Get the structure shown. Here, in the resonator forming step, a first metal film (for example, a Pt film) serving as a base of the lower electrode 31 is formed on the entire surface on the one surface side of the single crystal substrate 11A by a sputtering method, an EB evaporation method, or a CVD method. A piezoelectric material layer made of a PZT thin film serving as the basis of the piezoelectric layer 32 is formed on the entire surface of the single crystal substrate 11A after the first metal film forming step and the first metal film forming step. A piezoelectric material layer forming process formed by a sputtering method, a sol-gel method, a CVD method, or the like, and after the piezoelectric material layer forming process, the piezoelectric material layer is patterned by using a photolithography technique and an etching technique. Patterning the first metal film using a piezoelectric material layer patterning step for forming the piezoelectric layer 32 comprising a part, and a photolithography technique and an etching technique The first metal film patterning step and, above one surface of the entire surface such as SiO 2 film of a single crystal substrate 11A after the first metal film patterning step of forming a lower electrode 31 made of a part than the first metal film An insulating layer forming step for forming the insulating layer 4 made of sputtering by a sputtering method, a CVD method, or the like, and an insulating for forming an opening 4a in the insulating layer 4 using a photolithography technique and an etching technique after the insulating layer forming step After the layer patterning step and the insulating layer patterning step, a second metal film (for example, a Pt film) serving as the basis of the upper electrode 33 and the metal wiring 34 is sputtered on the entire surface on the one surface side of the single crystal substrate 11A. A second metal film forming process formed by EB deposition, EB vapor deposition, CVD, or the like, and using a photolithography technique and an etching technique after the second metal film forming process. It is composed of a second metal film patterning step of forming an upper electrode 33 and the metal wiring 34 formed of a part of the second metal film. In the resonator forming step, a seed layer forming step for forming an SRO layer as a seed layer for controlling the orientation of the piezoelectric material layer is provided between the first metal film forming step and the piezoelectric material layer forming step. May be.

  After the above-described resonator forming step, a handling substrate laminating step of laminating a handling substrate 14 made of a single crystal Si substrate to the one surface side of the single crystal substrate 11 via an adhesive layer 13 made of a resist layer is performed. Thus, the structure shown in FIG.

  After the above-mentioned handling substrate laminating step, the structure shown in FIG. 3C is obtained by performing the thinning step of forming the upper substrate 11 having a predetermined thickness by thinning the single crystal substrate 11A from the other surface side. . Here, in the thinning process, for example, the single crystal substrate 11A may be thinned by CMP (Chemical Mechanical Polishing) or the like, and wet etching for removing a damaged layer by polishing may be performed.

  After the above-described thinning process, an opening forming process is performed in which the opening 11a is formed on the upper substrate 11 from the side opposite to the resonator 3 by wet anisotropic etching using the crystal orientation dependence of the etching rate. As a result, the structure shown in FIG. Here, in the opening forming step, a mask layer 15 made of a resist layer patterned for forming the opening 11a is formed on the other surface side of the single crystal substrate 11 using a photolithography technique, and then the single crystal substrate is formed. 11 is anisotropically etched from the other surface side using a predetermined etching solution. When a single crystal MgO substrate is employed as the single crystal substrate 11A, a phosphoric acid solution (for example, a phosphoric acid aqueous solution) may be used as the predetermined etching solution.

  After the opening forming step described above, after removing the mask layer 15, performing a substrate bonding step of forming the support substrate 1 by bonding the upper substrate 11 and the lower substrate 12 made of a single crystal Si substrate. Thus, the structure shown in FIG. 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 substrate bonding step described above, the handling substrate 14 and the adhesive layer 13 are peeled off to obtain the BAW resonance device having the structure shown in FIG.

  In the manufacture of the above-described BAW resonance device, a number of BAW resonance devices are formed at the wafer level using wafers as the above-described single crystal substrate 11A, handling substrate 14, and lower layer substrate 12, and then individual BAW resonances are performed in a dicing process. What is necessary is just to divide into apparatuses. By the way, in the manufacture of the BAW resonator of the present embodiment, the opening 11a is formed in the upper layer substrate 11 for each of the two resonators 3 in each set in the opening forming step. Compared with the case where one resonator 3 is formed, 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 resonator 3 is formed on the one surface of the single crystal substrate 11A made of the single crystal MgO substrate or the single crystal STO substrate that is the basis of the upper substrate 11. Then, the upper substrate 11 having a predetermined thickness is formed by thinning the single crystal substrate 11A from the other surface side, and then the opening 11a is etched in the upper layer substrate 11 from the side opposite to the resonator 3 side. Since the support substrate 1 is formed by bonding the upper substrate 11 and the lower substrate 12 after that, the crystallinity of the piezoelectric layer 32 is improved. Therefore, it is possible to provide a BAW resonance device that can improve the mechanical quality factor and can be reduced in size and robustness.

(Embodiment 2)
The basic configuration of the BAW resonator according to the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 4, the lower substrate 12 in the support substrate 1 is provided in the thickness direction so as to penetrate the opening 11 a of the upper substrate 11. It has a through hole 12a that communicates, and the difference is that the opening 11a of the upper substrate 11 and the through hole 12a of the lower substrate 12 form a cavity 1a that exposes the lower electrode 31 of the resonator 3. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  By the way, in the BAW resonance device of the present embodiment, the through hole 12a of the lower layer substrate 12 is a vertical hole having a uniform opening size in the thickness direction of the lower layer substrate 12, and therefore the upper layer through the through hole 12a of the lower layer substrate 12. By forming the opening 11a in the substrate 11, the through hole 12a and the opening 11a can form the cavity 1a. Since the through hole 12a is a vertical hole, the size can be reduced.

  Hereinafter, the method for manufacturing the BAW resonator according to the present embodiment will be described with reference to FIG.

  First, a substrate bonding step is performed in which a single crystal substrate made of a single crystal MgO substrate or a single crystal STO substrate serving as the basis of the upper layer substrate 11 and a lower layer substrate 12 made of a single crystal Si substrate are bonded. The upper layer substrate 11 is formed by performing a thinning process for thinning the substrate from the one surface side opposite to the lower layer substrate 12 side, thereby obtaining the structure shown in FIG. Here, in the thinning step, for example, the single crystal substrate may be thinned from the one surface side by a CMP method or the like, and wet etching may be performed to remove a damaged layer by polishing.

  After the above-described thinning step, the structure shown in FIG. 5B is obtained by performing the resonator forming step of forming the resonator 3 on the one surface of the upper substrate 11. The description of the resonator forming step is omitted because the single crystal substrate 11A in the resonator forming step described in the first embodiment is merely replaced with the support substrate 1.

  After the above-described resonator forming step, by performing a through hole forming step of forming a through hole 12a consisting of a vertical hole reaching the other surface of the upper layer substrate 11 from the side opposite to the upper layer substrate 11 side in the lower layer substrate 12, The structure shown in FIG. 5C is obtained. Here, in the through hole forming step, a mask layer 17 made of a resist layer patterned for forming the through hole 12a is formed on the lower substrate 12 opposite to the upper substrate 11 side, and the one surface side of the upper substrate 11 is formed. After the mask layer 18 made of a resist layer is formed on the entire surface of the substrate, the through hole 12a is formed in the lower layer substrate 12 by using an anisotropic etching technique using an inductively coupled plasma (ICP) type dry etching apparatus, for example. Forming.

  After the above-described through hole forming step, a wet etching step is performed in which the opening 11a is formed in the upper layer substrate 11 through the through hole 12a of the lower layer substrate 12 by wet anisotropic etching using the crystal orientation dependence of the etching rate. Thus, the structure shown in FIG.

  After the above-described wet etching process, a mask layer removing process for removing the mask layers 17 and 18 is performed to obtain a BAW resonance device having a structure shown in FIG.

  In manufacturing the above-described BAW resonance device, a plurality of BAW resonance devices may be formed at the wafer level using a wafer as the single crystal substrate and the lower layer substrate 12 and then divided into individual BAW resonance devices in a dicing process.

  According to the method for manufacturing the BAW resonator of the present embodiment described above, the single crystal substrate that is the single crystal MgO substrate or the single crystal STO substrate that is the basis of the upper layer substrate 11 and the lower layer substrate 12 are bonded, The upper substrate 11 is formed by thinning the single crystal substrate from the one surface side opposite to the lower substrate 12 side, and then the resonator 3 is formed on the one surface of the upper layer substrate 11. Then, a through hole 12a that reaches the upper layer substrate 11 from the side opposite to the upper layer substrate 11 side in the lower layer substrate 12 is formed, and then the opening 11a is formed in the upper layer substrate 11 through the through hole 12a, and the etching rate depends on the crystal orientation. Since it is formed by using wet anisotropic etching, the crystallinity of the piezoelectric layer 32 can be improved, the mechanical quality factor can be improved, and miniaturization and robustness can be achieved. It is possible to provide the AW resonator. Further, in the method for manufacturing the BAW resonator according to the present embodiment, it is not necessary to use the handling substrate 14 (see FIG. 3B) described in the first embodiment, so that the manufacturing cost can be reduced.

The BAW resonance apparatus of Embodiment 1 is shown, (a) is a principal part schematic plan view, (b) is a principal part schematic sectional drawing. 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. The BAW resonance apparatus of Embodiment 1 is shown, (a) is a principal part schematic plan view, (b) is a principal part schematic sectional drawing. It is principal process sectional drawing for demonstrating the manufacturing method of a BAW resonance apparatus same as the above. It is main process sectional drawing for demonstrating the manufacturing method of the ferroelectric thin film apparatus of a prior art example. It is a schematic sectional drawing of the conventional BAW resonance apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 1a Cavity 3 Resonator 11 Upper layer substrate 11a Opening part 12 Lower layer substrate 31 Lower electrode 32 Piezoelectric layer 33 Upper electrode

Claims (5)

  1.   A resonator having a piezoelectric layer is formed on one surface side of the support substrate between the lower electrode and the upper electrode, and a cavity is formed in the support substrate to expose the surface on the support substrate side of the lower electrode of the resonator. A BAW resonance device in which the piezoelectric material of the piezoelectric layer is a PZT-based material or a KNN-based material, and the piezoelectric layer is entirely formed on the lower electrode in a plan view, and the support substrate is an upper-layer substrate having a different thickness And an upper layer substrate that is relatively close to the resonator in the support substrate is composed of a single crystal MgO substrate or a single crystal STO substrate and is relatively far from the resonator. A trapezoidal cross section in which the cavity is thinner than a certain lower substrate and the cavity penetrates at least in the thickness direction of the upper substrate by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate BAW resonator apparatus characterized by comprising constituted by the opening of.
  2.   2. The BAW resonance device according to claim 1, wherein the lower layer substrate is made of a single crystal Si substrate.
  3.   2. The lower layer substrate has a through hole penetrating in a thickness direction and communicating with the opening, and the through hole is a vertical hole having a uniform opening size in the thickness direction. Or the BAW resonance apparatus of Claim 2.
  4.   3. A method of manufacturing a BAW resonator according to claim 1, wherein a resonator is formed on one surface of a single crystal substrate comprising a single crystal MgO substrate or a single crystal STO substrate as a base of an upper layer substrate. A thin layer forming step of forming an upper substrate of a predetermined thickness by thinning the single crystal substrate from the other surface side after the resonator forming step, and a resonance in the upper layer substrate after the thinning step An opening forming step of forming the opening from the side opposite to the child side by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate, and an upper layer substrate and a lower layer substrate after the opening forming step. A method of manufacturing a BAW resonance device comprising: a substrate bonding step of forming a support substrate by bonding.
  5.   4. A method of manufacturing a BAW resonator according to claim 3, wherein a substrate bonding step for bonding a single crystal substrate consisting of a single crystal MgO substrate or a single crystal STO substrate as a base of an upper substrate and a lower substrate, and a substrate bonding step After that, the single crystal substrate is thinned from one surface side opposite to the lower substrate side to form an upper layer substrate, and after the thinning step, resonance on the one surface of the upper layer substrate A resonator forming step of forming a child, a through hole forming step of forming the through hole reaching the upper layer substrate from the side opposite to the upper layer substrate side in the lower layer substrate after the resonator forming step, and a through hole forming step And a wet etching step of forming the opening in the upper substrate through the through hole by wet anisotropic etching utilizing the crystal orientation dependence of the etching rate later. The method of production.
JP2008323856A 2008-12-19 2008-12-19 Baw resonance device and method of manufacturing the same Withdrawn JP2010147869A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012165132A (en) * 2011-02-04 2012-08-30 Taiyo Yuden Co Ltd Method for manufacturing acoustic wave device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012165132A (en) * 2011-02-04 2012-08-30 Taiyo Yuden Co Ltd Method for manufacturing acoustic wave device
US9148107B2 (en) 2011-02-04 2015-09-29 Taiyo Yuden Co., Ltd. Method for manufacturing acoustic wave device

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