JP5119839B2 - Piezoelectric thin film resonator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric thin film resonator including a substrate, a vibration part having a piezoelectric thin film, and a support part that supports the vibration part on the substrate, and a method of manufacturing the same.

  Conventionally, a spread vibration type piezoelectric vibrator that has been miniaturized to such an extent that it can be used as a micro device has been used. As a spread vibration type piezoelectric vibrator, one having a high mechanical quality factor Qm and a relatively low frequency of about 1 to 10 MHz in resonance frequency is known (see Patent Document 1).

  FIG. 1 is a diagram showing a configuration of a conventional spread vibration type piezoelectric vibrator.

  The spread vibration type piezoelectric vibrator 191 includes a substrate 192, a pair of support parts 193, 193, a pair of support beams 194, 194, and a vibration part 195. The substrate 192 is made of Si material. The support portion 193 and the support beam 194 have a configuration in which an insulating film or a piezoelectric thin film is disposed on a base made of Si material. The support portions 193 and 193 are provided on the substrate 192 so as to face each other. The support beams 194 and 194 are provided between the support portions 193 and 193. The vibration unit 195 is provided between the support beams 194 and 194 and is supported in a state of floating above the substrate 192.

The vibration unit 195 includes a vibration plate 196, an insulating film 197, a piezoelectric thin film 198, an upper electrode 199A, and a lower electrode 200A. The diaphragm 196 is made of Si material. The insulating film 197 is provided on the vibration plate 196. The piezoelectric thin film 198 is made of a ZnO material and is provided on the insulating film 197. The upper electrode 199A and the lower electrode 200A are disposed in contact with the upper surface and the lower surface of the piezoelectric thin film 198, respectively. Terminal portions 199B and 200B are formed on the support portions 193 and 193. The terminal portions 199B and 200B are electrically connected to the upper electrode 199A and the lower electrode 200A, respectively, and are connected to external lead wires and the like. A contact hole 200 </ b> C is formed on the terminal portion 200 </ b> B of the lower electrode 200.
JP-A-8-186467

  In the spread vibration type piezoelectric vibrator shown in FIG. 1, the beam portion is formed of a material having high rigidity such as Si. Therefore, even if stress generated in the piezoelectric thin film is concentrated on the beam portion, the beam portion is almost bent. Absent. However, since the beam part and the vibration part are thick, there is a limit to reducing the overall height of the element.

  On the other hand, when the beam portion is made of a material having a low rigidity or a thin film, when the stress generated in the piezoelectric thin film is concentrated on the beam portion, the beam portion is elastically deformed, and the vibration portion may come into contact with the substrate. In addition, the elastic modulus of the beam portion varies, and it is difficult to make the height of the beam portion uniform for each product. Therefore, it is difficult to control the lower clearance between the vibrating portion and the substrate to be constant, and the lower clearance needs to be set wider in advance. In addition, when such a vibrator is enclosed in a small and low profile package such as a CSP, there is a possibility that the vibration part may come into contact with not only the substrate but also the lid of the package. It is also difficult to keep the upper clearance between them constant. Therefore, the upper clearance needs to be set wider in advance, and there is still a limit to reducing the overall height of the device.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a piezoelectric thin film resonator having improved reliability by eliminating the contact between the vibrating part and the lid while reducing the height of the package and a method for manufacturing the same.

  The piezoelectric thin film vibrator of the present invention includes a substrate, a vibrating part, a lid, and a support part. The vibration part includes a piezoelectric thin film disposed between a pair of electrodes. The lid includes a vibrating portion in an internal space with the substrate. The support part supports the vibration part and includes a beam part and a restriction part. A gap is provided between the beam portion and the substrate to elastically support the vibration portion. The limiting portion limits the change in the distance between the lid and the beam portion.

  Even if the vibrating part is enclosed in the internal space between the lid and the substrate, the space between the lid and the beam (upper clearance) is limited by the limiting part, so the stress generated in the piezoelectric thin film is concentrated on the beam. Even if the beam part is elastically deformed, the upper clearance is suppressed from being narrowed. Therefore, it is possible to prevent the corners and belly of the vibrating portion from coming into contact with the lid even if the vibrating portion is bent. In addition, the upper clearance between the lid and the beam can be made uniform for each product, and the upper clearance is set to a minimum to reduce the package size. For example, if the amount of flexure of the vibration part is at most about several μm, the upper clearance may be the same and slightly increased, and the package size can be reduced.

  It is preferable that the limiting portion has a column shape and is erected between the beam portion and the lid. This is because the change in the upper clearance between the lid and the beam can be limited with a simple shape.

  The limiting portion is preferably formed on the beam portion. When manufacturing, the limiting part can be formed continuously with the piezoelectric thin film or electrode thin film forming process, and if the amount of deflection of the vibration part is at most several μm, the thickness of the limiting part may be the same, and the thin film forming process limits The part can be formed.

  The limiting portion may be bonded to the lid. Thereby, a restriction | limiting part can be fixed and the structural strength of a support part can be raised.

  The restricting portion may include a conductive portion, and the lid may include an external connection terminal. The conductive portion is provided from one end on the lid side of the limiting portion to one end on the beam portion side, and is electrically connected to the electrode of the vibrating portion. The external connection terminal is electrically connected to the conductive portion through the via. Therefore, the external connection terminal provided on the lid and the electrode of the vibration part can be connected via the conductive part, and the wiring path length can be shortened. In this way, increase in electrical resistance and deterioration of electrical characteristics can be suppressed.

  The limiting portion may be made of any material among resin, Au, Cu, Al, and Sn. These materials are softer than other materials, can absorb vibration applied to the beam portion, and can more effectively suppress deterioration of characteristics due to vibration leakage.

  The vibration part may have a substantially rectangular shape, and the support part may be provided on both of two opposing sides of the vibration part. When the vibration part is supported by the double-supported beam structure, the deformation amount of the support part with respect to the same load is smaller than that of the cantilever structure. Therefore, the lower clearance between the vibrating part and the substrate can be narrowed. Further, the symmetry of the shape is maintained, and good electrical characteristics can be obtained without adversely affecting the line-symmetric or point-symmetric vibration mode of the vibration part.

  The vibration part may have a substantially rectangular shape, and the support part may be provided on one of two opposing sides of the vibration part. When the vibration part is supported by the cantilever structure, there is no thing that suppresses the elongation of the vibration part, and the vibration part hardly bends, so that the vibration part is less bent than the double-supported beam structure. Therefore, the upper clearance between the vibrating part and the lid can be narrowed. Moreover, the destruction by the stress of a vibration part can be prevented.

  The beam portion may have an arch shape and be connected to the substrate at one end thereof. Since the base of the beam portion is not fixed to the substrate and is held in an elastic state, deterioration of characteristics due to vibration leakage can be more effectively suppressed. The beam portion may have an arch shape and may be connected to the substrate at both ends thereof. Since the deformation of the beam part is reduced, the gap between the vibration part and the substrate can be narrowed.

  It is preferable that the magnitude of the residual stress in the compression direction of the film of the vibration part is smaller than the magnitude of the residual stress in the compression direction of the film of the beam part. This is because the warp of the beam part is larger than the warp of the vibration part, and the corners or antinodes of the vibration part can be more effectively prevented from contacting the substrate.

A method of manufacturing a piezoelectric thin film vibrator according to the present invention is a method for manufacturing the above-described piezoelectric thin film vibrator. And a limiting portion are formed in this stacking order to form a film structure on the substrate, a step of removing the sacrificial layer from the substrate, and a lower sacrificial layer is removed and floated from the substrate so as to include a structure having a predetermined shape, it is preferable to include a step of location Court the lid on the substrate.

  The film structure is preferably formed by applying a residual stress in the compression direction to the thin film layer.

  According to this invention, since the change in the upper clearance between the lid and the beam is limited by the limiting portion, it is possible to suppress the upper clearance from being narrowed even if the support and the support beam are elastically deformed. . Therefore, it is possible to prevent the corners and belly of the vibrating portion from coming into contact with the lid even if the vibrating portion is bent. By the limiting portion, the upper clearance can be made uniform for each product, the upper clearance can be minimized, the package size can be lowered, and the piezoelectric thin film resonator with improved reliability and a method for manufacturing the same can be provided.

<< First Embodiment >>
The piezoelectric thin film resonator according to the first embodiment will be described with reference to FIGS. Each figure shows a state where the bottom surface of the piezoelectric thin film resonator is placed on a horizontal plane.

  FIG. 2A is a perspective view of the piezoelectric thin film resonator 101. FIG. 2B is a perspective view of the main part of the piezoelectric thin film resonator 101 excluding the lid 30.

  The piezoelectric thin film resonator 101 includes a substrate (element wafer) 11, a lid 30, and a structure 100. The lid body 30 includes a frame body 31 and a top plate 32. The frame 31 constitutes the side wall surface of the lid 30, and the top plate 32 constitutes the ceiling surface of the lid 30. The lid 30 is disposed on the substrate 11.

  The structure 100 is accommodated in the internal space between the substrate 11 and the lid 30. The structure 100 includes a vibration unit 20, a support unit 21A, and a support unit 21B. The support part 21A and the support part 21B support both ends of the vibration part 20, and provide a clearance of about several μm between the vibration part 20 and the substrate 11 and between the vibration part 20 and the top plate 32. These clearances are formed by removing the pseudo control layer provided on the substrate in the manufacturing process described later.

  The vibration unit 20 is a rectangular flat plate and includes a piezoelectric thin film layer. The vibration unit 20 resonates in the spreading vibration mode or the length vibration mode of the piezoelectric thin film. In this embodiment, the electrical connection to the vibration part 20 is performed via the support parts 21 </ b> A and 21 </ b> B and the substrate 11.

  Since the vibration part 20 is supported by the support parts 21A and 21B in a doubly supported beam structure, the symmetry of the shape of the structure 100 is maintained, and without adversely affecting the line-symmetric or point-symmetric vibration mode of the vibration part 20. Good electrical characteristics can be obtained. Further, since the weight imparted to each support portion is smaller than when the vibration portion 20 is supported by a cantilever structure, the amount of deformation of each support portion is reduced, and the lower portion between the vibration portion 20 and the substrate 11 is reduced. Even if the clearance is set narrow, the risk of contact between the vibrating part 20 and the substrate 11 can be reduced.

  The support portions 21A and 21B include beam portions 24A and 24B and posts 25A and 25B.

  The beam portions 24A and 24B are composed of bridges 22A and 22B and arches 23A and 23B. Although the beam portions 24A and 24B will be described in detail later, the beam portions 24A and 24B include a piezoelectric thin film layer continuous from the vibrating portion 20, and the piezoelectric thin film layer continues to the substrate 11.

  The arches 23 </ b> A and 23 </ b> B are members that are bent into an upwardly convex bow shape (arch shape), and are held by the substrate 11 at both ends P and P thereof. The arches 23A and 23B maintain the lower clearance between the vibrating part 20 and the substrate 11 at about 5 μm. The arches 23A and 23B are formed by applying a compressive residual stress in a direction parallel to the substrate in the manufacturing process, and by removing the pseudo control layer provided in the lower layer, the compressive residual stress is released and becomes a bow shape.

  The bridges 22A and 22B extend from the apexes of the arches 23A and 23B or in the vicinity of the apexes in parallel with the substrate 11 and substantially perpendicular to the extending direction of the arches 23A and 23B. The bridges 22 </ b> A and 22 </ b> B are installed between the arches 23 </ b> A and 23 </ b> B and the vibration unit 20.

  The posts 25A and 25B have a cylindrical shape and extend from the apex of the arches 23A and 23B or near the apex to the ceiling surface side. The heights of the posts 25A and 25B are set so that the vibrating portion 20 and the top plate 32 do not come into contact with each other even when the vibrating portion 20 bends to the maximum extent. The posts 25A and 25B limit the change in the upper clearance between the top plate 32 and the beam portions 24A and 24B, and the upper clearance is suppressed from being narrower than the height of the posts 25A and 25B. Therefore, even if the vibration part 20 is bent, the corners and the belly can be prevented from coming into contact with the top board 32.

  3A is a cross-sectional view (upper cross-sectional view) of the AA portion in FIGS. 3B and 3C of the piezoelectric thin film resonator 101, and FIG. 3B is a cross-sectional view in FIG. FIG. 3C is a cross-sectional view of the CC section in FIG. 3A.

  The vibration unit 20 has a film structure in which an insulating layer 12, a lower electrode 13, a piezoelectric thin film 14, an upper electrode 15, a stress adjustment film 16, and a temperature characteristic compensation film 17 are stacked in this order from the substrate 11 side. The bridge 22 </ b> A has a film structure obtained by removing the lower electrode 13 from the film structure of the vibration unit 20. The bridge 22B has a film structure obtained by removing the upper electrode 15 from the film structure of the vibration unit 20. The arch 23 </ b> A has a film structure obtained by removing the lower electrode 13 and the stress adjustment film 16 from the film structure of the vibration unit 20. On the upper layer of the arch 23A, a layer that becomes the post 25A is laminated. The arch 23B has a film structure in which the upper electrode 15 and the stress adjustment film 16 are removed from the film structure of the vibration unit 20. On the upper layer of the arch 23B, a layer that becomes the post 25B is laminated. The substrate 11 is a base material of a material having a high resistivity, for example, a glass substrate, a high resistance Si substrate, a GaAs substrate, and the like. Although not shown, a film similar to the arches 23A and 23B is formed thereon. A structure is formed. Further, the upper electrode 15 is extracted from the one end of the arch 23A onto the substrate 11 as an extraction electrode. Further, the lower electrode 13 is extracted from the one end of the arch 23B onto the substrate 11 as an extraction electrode.

  In the figure, the ends of the posts 25A and 25B are spaced from the top plate 32 at the end on the ceiling surface side, but this interval varies depending on the amount of deflection of the arches 23A and 23B. When the amount of bending of the arches 23A and 23B is extremely large, the posts 25A and 25B come into contact with the top plate 32. Therefore, no matter how much the arches 23A and 23B are bent, the upper clearance 42 between the vibrating portion 20 and the top plate 32 can be secured at least by the height of the posts 25A and 25B. For this reason, even if the heights of the arches 23A and 23B vary from product to product, the upper clearance 42 between the vibration unit 20 and the top plate 32 can be set to a minimum, and the package size can be reduced. For example, if the deflection amount of the vibration part 20 is 1 μm at most, the upper clearance 42 between the vibration part and the lid body can be increased by setting the height of the posts 25A and 25B to 1 μm or slightly larger than that. Enough can be secured.

  The posts 25 </ b> A and 25 </ b> B may be bonded to the top plate 32. In this case, the posts 25A and 25B and the beam portions 24A and 24B can be fixed to the top plate 32, and the structural strength of the entire support portions 21A and 21B can be increased. In that case, the posts 25A and 25B are preferably made of a soft material. Examples of the soft material include resin, gold Au, copper Cu, aluminum Al, and tin Sn. By adopting such a material for the posts 25A and 25B, vibration generated in the beam portions 24A and 24B can be damped, and deterioration of characteristics due to vibration leakage can be effectively suppressed.

FIG. 4 is a diagram illustrating a configuration example of a thin film layer on the substrate 11 in the manufacturing process.
4A is a top view of the substrate 11 before the sacrificial layer 40 is removed, FIG. 4B is a cross-sectional view of the arch 23A before the sacrificial layer 40 is removed, and FIG. It is sectional drawing of the arch 23A after the layer 40 removal.

  In the manufacturing process of the piezoelectric thin film resonator 101, first, a sacrificial layer 40 having a predetermined pattern is formed on the substrate 11. The sacrificial layer 40 is made of a resist material.

  Then, the thin film layer 43 having the film structure shown in FIG. 3 is formed on the sacrificial layer 40 and the substrate 11. On the sacrificial layer 40, of the thin film layer 43, the vibration region 20, the bridges 22A and 22B, the posts 25A and 25B, and the central regions of the arches 23A and 23B are formed. On the substrate 11, both end regions of the arches 23 </ b> A and 23 </ b> B are formed in the thin film layer 43.

  Then, the sacrificial layer 40 is removed by a resist removal process or the like.

  Thereby, the lower clearance 41 is formed in the lower part of the vibration part 20, bridge 22A, 22B, and arch 23A, 23B. Further, the arches 23A and 23B are released from the compressive residual stress, the film is stretched, and deformed into a bow shape.

  Thereafter, the lid 30 is placed on the substrate 11. When the amount of bending of the arches 23A and 23B is large, the posts 25A and 25B provided on the uppermost parts of the arches 23A and 23B come into contact with the top plate 32 of the lid 30 and the uppermost parts of the arches 23A and 23B are pushed down. . Therefore, the upper clearance between the vibrating part 20 and the lid 30 is ensured, and the piezoelectric thin film resonator 101 is manufactured.

Next, details of the film structure will be described.
FIG. 5A shows the film structure of the vibrating portion 20 and the bridges 22A and 22B, and FIG. 5B shows the film structure of the arches 23A and 23B.

The insulating layer 12 is made of SiO ₂ , has a thickness of 1.7 μm, and a compressive residual stress of 180 MPa acts in a direction parallel to the substrate. The piezoelectric thin film 14 on the insulating layer 12 is made of AlN, has a thickness of 1.6 μm, and a compressive residual stress of 80 MPa acts in a direction parallel to the substrate. Although the upper electrode 15 and the lower electrode 13 exist above and below the piezoelectric thin film 14 of the vibration unit 20, both of the film thickness are thin and the influence of residual stress is small. The stress adjusting film 16 is made of AlN, has a thickness of 0.8 μm, and a tensile residual stress of 100 MPa acts in a direction parallel to the substrate. The uppermost temperature characteristic compensation film 17 is made of SiO ₂ , has a thickness of 3.3 μm, and a compressive residual stress of 180 MPa acts in a direction parallel to the substrate.

  As shown in FIG. 5A, in the vibration part and the bridge, the piezoelectric thin film 14 on which the compressive residual stress acts and the stress adjustment film 16 on which the tensile residual stress acts are laminated, and the residual stress is between them. Offset. Therefore, the magnitude of the compressive residual stress of the vibration part film is smaller than the magnitude of the compressive residual stress of the arch film. Therefore, the vibrating part / bridge does not bend greatly and maintains a relatively flat state.

  On the other hand, as shown in FIG. 5B, the arch does not have the stress adjusting film 16 shown in FIG. 5A, and the arches 23A and 23B both have the insulating layer 12 and the piezoelectric thin film 14 on which compressive residual stress acts. And the temperature characteristic compensation film 17. Therefore, after the sacrificial layer is removed, the arch extends in the surface direction of the substrate 11, and accordingly, the arch is lifted in a direction perpendicular to the substrate 11 to form an arch shape. At this time, in order to surely warp the arch upward, it is more preferable that the upper portion becomes larger when the compressive residual stress of the arch film is compared between the upper portion and the lower portion. As a result, as shown in FIG. 2, the vibration unit 20 is supported on the substrate 11 via the lower clearance 41 while being supported by the bridges 22 </ b> A and 22 </ b> B. The amount of arch deflection (height) can be set by the length of the arch and the strength of the residual stress of compression.

  Note that the film structure shown here is merely an example, and other film structures may be adopted. For example, the film thickness, the magnitude of the residual stress, and the order of the films may be different. Moreover, you may comprise so that only a compressive residual stress may act on a vibration part. Further, the arch may be provided with a layer on which a tensile residual stress acts.

  Further, according to the structure shown in FIGS. 2 and 3, electrical wiring to the vibration unit 20 is performed via the arches 23A and 23B, the bridges 22A and 22B, and the substrate 11, and the arches 23A and 23B are formed on the substrate. 11 is in contact with both ends P and P, respectively, and wiring resistance can be reduced by wiring in parallel from these two locations. Further, since there is no electrode step in the arches 23A and 23B, there is no discontinuity in the structure of the film due to the electrode steps in the film formed on the arches 23A and 23B. Increase in strength.

  However, wiring may be performed from one side of the arch for the convenience of routing the wiring pattern on the substrate. Further, wiring from one of the two support portions 21A and 21B to the upper electrode 15 and the lower electrode 13 may be performed. As a result, the external electrode can be taken out to one side of the substrate, and the entire chip size can be easily reduced.

<< Second Embodiment >>
FIG. 6 is a cross-sectional view of the piezoelectric thin film resonator 102 according to the second embodiment. What differs from the piezoelectric thin film resonator 101 shown in FIG. 3B is the structure of the posts 115A and 115B and the structure of the top plate 112.

  The posts 115A and 115B are made of a conductive material, and are formed from the upper electrode 15 or the lower electrode 13 provided on the arch to the position where the top plate 112 comes into contact. The material of the posts 115A and 115B is preferably gold Au, copper Cu, aluminum Al, tin Sn, or the like. The posts 115A and 115B also serve as the conductive portion of the present invention.

  The top plate 112 has electrodes 113A and 113B for external connection formed on the top surface thereof, electrodes 114A and 114B for connection to the posts 115A and 115B formed on the bottom surface thereof, and electrodes 113A and 113B and electrodes 114A and 114B. Are conducted through vias 116A and 116B.

  Therefore, the upper electrode 15 is drawn from the post 115A and the lower electrode 13 is drawn from the post 115B to the electrodes 113A and 113B on the top surface of the top plate as lead electrodes. Thereby, the wiring path length from the upper electrode 15 or the lower electrode 13 to the external connection terminal can be shortened by using the electrodes 113A and 113B provided on the top plate 112 as external connection terminals. Therefore, an increase in electrical resistance and deterioration of electrical characteristics can be suppressed.

  In addition, since the electrical connection from the upper electrode 15 or the lower electrode 13 of the vibration unit 20 to the external connection terminal can be performed without going through the substrate 11, the insulation of the substrate 11 may be low, and the material selection of the substrate 11 is possible. The degree of freedom increases, and the degree of freedom of the film formation process also increases.

<< Third Embodiment >>
FIG. 7 is a perspective view of the main part of the piezoelectric thin film resonator 103 according to the third embodiment. What differs from the piezoelectric thin film resonator 101 shown in FIG. 2 is the shapes of the arches 123A and 123B.
Both ends of the vibration part 20 are supported by support parts 121A and 121B, and a predetermined lower clearance is provided between the vibration parts 20 and the substrate by the beam parts 124A and 124B. The support portion 121A includes a bridge 22A drawn from the center of one short side of the vibration portion 20 and an arch 123A whose one end is in contact with the substrate. Similarly, the support portion 121B includes a bridge 22B drawn from the center of the other short side of the vibration portion 20 and an arch 123B whose one end is in contact with the substrate.

  Since each of the arches 123A and 123B is connected to the substrate only at one end P, it is not possible to use the bending due to the release of the compressive residual stress after the sacrifice layer is removed. Therefore, the sacrificial layer below the arches 123A and 123B is previously formed in a semi-bow shape (arch shape).

  The two arches 123A and 123B have the same extending direction extending from the substrate, but the connection positions of the arches to the substrate may be determined so as to extend in opposite directions.

<< Fourth Embodiment >>
FIG. 8 is a perspective view of the main part of the piezoelectric thin film resonator 104 according to the fourth embodiment. This corresponds to the piezoelectric thin film resonator 101 shown in FIG. 2 that is supported by the support portion 21A only from the center of one short side of the vibration portion 20.
With such a cantilever structure, the area occupied by the support portion on the substrate can be reduced, and the overall size can be reduced. In addition, since one side of the vibration part is not supported, the vibration part can be flat if the residual stress is equal between the upper part and the lower part of the film structure at the vibration part.

<< Fifth Embodiment >>
FIG. 9 is a perspective view of the main part of the piezoelectric thin film resonator 105 according to the fifth embodiment. What is different from the piezoelectric thin film resonator 101 shown in FIG. 2 is the structure of the support portions 131A and 131B.
The vibrating unit 20 is supported at both ends by the support units 131A and 131B, and a predetermined lower clearance is provided between the vibrating unit 20 and the substrate by the beam units 134A and 134B. The beam portions 134A and 134B are drawn out from the center of the short side of the vibration portion 20 and have a semi-bow shape with one end contacting the substrate.

  In any of the first to fifth embodiments, it is desirable that the vibration unit 20 is flat and substantially parallel to the substrate, but at least the vibration unit 20 may not be in contact with the substrate. According to the present invention, since a sufficient gap can be formed between the vibration part 20 and the substrate 11, the vibration part 20 protrudes upward, protrudes downward, or is slightly bent into a composite shape. It may be. Further, it may be somewhat non-parallel to the substrate.

  Further, the shape of the arch is preferably a rectangle as viewed from above, but other than that, for example, a meander shape may be used.

It is a perspective view which shows the structure of the conventional piezoelectric thin film resonator. 1 is a perspective view of a piezoelectric thin film resonator according to a first embodiment. It is sectional drawing of the same piezoelectric thin film resonator. It is a figure explaining the manufacturing process of the same piezoelectric thin film resonator. It is a figure which shows the example of the film | membrane structure of the piezoelectric thin film resonator. It is sectional drawing of the piezoelectric thin film resonator which concerns on 2nd Embodiment. It is a perspective view of the principal part of the piezoelectric thin film resonator which concerns on 3rd Embodiment. It is a perspective view of the principal part of the piezoelectric thin film resonator which concerns on 4th Embodiment. It is a perspective view of the principal part of the piezoelectric thin film resonator which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Board | substrate 13 ... Lower electrode 14 ... Piezoelectric thin film 15 ... Upper electrode 20 ... Vibrating part 21A, 21B, 121A, 121B, 131A, 131B ... Support part 22A, 22B ... Bridge 23A, 23B ... Arch 24A, 24B ... Beam part 25A , 25B, 115A, 115B ... post 30 ... cover 32 ... top plate 40 ... sacrificial layer 41 ... lower clearance 42 ... upper clearance 100 ... structures 101-105 ... piezoelectric thin film resonators 116A, 116B ... vias

Claims (11)

Piezoelectric thin film resonance comprising: a substrate; a vibration part in which a piezoelectric thin film is disposed between a pair of electrodes; a lid body that encloses the vibration part in an internal space of the substrate; and a support part that supports the vibration part. A child,
The support portion includes a beam portion that elastically supports the vibration portion by providing a gap between the substrate and a limiting portion that restricts a change in the distance between the lid and the beam portion. .   2. The piezoelectric thin film resonator according to claim 1, wherein the limiting portion has a column shape and is erected between the beam portion and the lid.   The piezoelectric thin film resonator according to claim 2, wherein the limiting portion is formed by film formation on the beam portion.   The piezoelectric thin film resonator according to claim 2 or 3, wherein the limiting portion is bonded to the lid. The limiting portion includes a conductive portion provided from one end on the lid side to one end on the beam portion side, which is electrically connected to one of the pair of electrodes of the vibrating portion,
5. The piezoelectric thin film resonator according to claim 2, wherein the lid includes an external connection terminal that conducts to the conductive portion through a through hole.   The piezoelectric thin film resonator according to any one of claims 2 to 5, wherein the restricting portion is made of any material of resin, Au, Cu, Al, and Sn. The vibrating portion has a substantially rectangular shape,
The piezoelectric thin film resonator according to claim 1, wherein the support part is provided on one or both sides of the two opposing sides of the vibration part.   The beam portion has an arch shape connected to the substrate at a first end and connected to the vibration portion at a second end, or an arch shape connected to the substrate at both ends and connected to the vibration portion at a substantially center. The piezoelectric thin film resonator according to any one of claims 1 to 7.   The piezoelectric thin film resonator according to claim 1, wherein the residual stress in the compression direction of the film of the vibration part is smaller than the residual stress in the compression direction of the film of the beam part. . A method for manufacturing a piezoelectric thin film resonator according to claim 1,
On a substrate, the steps constituting the sacrificial layer having a predetermined shape, and a thin film layer piezoelectric thin film is disposed between a pair of electrodes, wherein the limiting portion, was formed on this stacking order, a layer structure on the substrate,
Removing the sacrificial layer from the substrate;
Placing a lid on the substrate so that a lower-layer sacrificial layer is removed and a structure having a predetermined shape floating from the substrate is included.   The method of manufacturing a piezoelectric thin film resonator according to claim 10, wherein the film structure is formed by applying a residual stress in a compression direction to the thin film layer.

Images