JP4710456B2 - Boundary acoustic wave device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a boundary acoustic wave device using a boundary acoustic wave propagating along a boundary between a first medium and a second medium, and in particular, a three-medium structure in which a third medium is stacked on a second medium. The present invention relates to a boundary acoustic wave device having an under bump metal (UBM) to which bumps are bonded and a manufacturing method thereof.

  Conventionally, surface acoustic wave devices have been widely used to configure filters and resonators of communication equipment. On the other hand, in recent years, various boundary acoustic wave devices using boundary acoustic waves have been proposed in place of the surface acoustic wave devices. In the boundary acoustic wave device, a boundary acoustic wave that propagates through the interface between the piezoelectric body and the insulator is used. Since the interface through which the boundary acoustic wave propagates is sealed by the piezoelectric body and the insulator, a complicated package structure is not required.

  Patent Document 1 discloses a three-medium type boundary acoustic wave device shown in FIG. 8 as an example of such a boundary acoustic wave device.

  In the boundary acoustic wave device 501, a second medium 503 made of an insulator is stacked on a first medium 502 made of a piezoelectric material, and the second medium 503 is on the opposite side of the first medium 502. A third medium 504 is stacked on the surface. Here, an IDT is formed at the interface between the first medium 502 and the second medium 503, and an elastic boundary wave is excited by applying an AC voltage to the IDT.

The first medium 502 is made of a piezoelectric single crystal such as a LiTaO ₃ substrate, the second medium 503 is made of polycrystalline silicon oxide, and the third medium 504 is made of polycrystalline. It is composed of a silicon film.
WO98 / 52279

  As described in Patent Document 1, a so-called three-medium type boundary acoustic wave device has been conventionally known. Also in this type of boundary acoustic wave device, in order to mount on a mounting substrate with high density, a metal bump is bonded to the surface acoustic wave device, and the metal bump is used to bond to an electrode on the mounting substrate. Bump bonding, in which a surface acoustic wave device is mounted, has been frequently used. Therefore, it is desirable that the boundary acoustic wave device is also configured to be mounted on the mounting substrate by bump bonding.

  However, the basic structure of the boundary acoustic wave device is only shown in Patent Document 1 and the like, and a specific structure suitable for bump bonding has not been proposed in the conventional boundary acoustic wave device.

  An object of the present invention is a three-medium boundary acoustic wave device in view of the above-described state of the prior art, and can be laminated on a mounting substrate by bump bonding or the like, and has excellent reliability. Another object of the present invention is to provide a boundary acoustic wave device.

According to a wide aspect of the present invention, a first medium, an IDT provided on the first medium, and a second medium provided to cover the IDT on the first medium; In the boundary acoustic wave device having the third medium laminated on the second medium, the boundary wave device includes a wiring formed on the first medium so as to be electrically connected to the IDT, The second medium has a second medium opening that partially exposes the wiring, and the third medium has a third medium opening, and the third medium opening has a third medium opening. The formed under bump metal and the lower surface of the under bump metal are bonded to each other, and the second medium and the second medium are formed between the third medium and the second medium at the second medium opening. An interface with the first medium, at which the IDT and the electric power are connected. Manner and UBM underlying layer connected to said further comprising a feed line that is UBM underlayer and electrically connected to the second medium at the interface between the third medium, the feed line, At the interface between the second medium and the third medium, intersects with the stacking direction of the structure in which the first medium, the second medium, and the third medium of the boundary acoustic wave device are stacked. A boundary acoustic wave device is provided which is exposed at an end face extending in the direction of the boundary.

  In another specific aspect of the boundary acoustic wave device according to the present invention, the third medium opening is disposed on the second medium opening so as to be continuous with the second medium opening, The under bump metal is formed so as to extend from the third medium opening to the second medium opening.

  In still another specific aspect of the boundary acoustic wave device according to the present invention, the third medium opening and the under bump metal are disposed above a region where the IDT is formed.

  In still another specific aspect of the boundary acoustic wave device according to the present invention, the third medium opening and the under bump metal are formed in a portion other than above the region where the IDT is formed.

  In still another specific aspect of the boundary acoustic wave device according to the present invention, the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium is a sound absorbing film.

  In still another specific aspect of the boundary acoustic wave device according to the present invention, the first medium is a dielectric substrate, the second medium is a piezoelectric film, and the third medium is a sound absorbing film.

  The method for manufacturing a boundary acoustic wave device according to the present invention includes a step of preparing a mother substrate made of a first medium, a step of forming an IDT on the mother substrate, and an electrical connection to the IDT. A step of forming a wiring, a step of forming a second medium so as to cover the IDT on a mother substrate on which the IDT is formed, and a second part of which the wiring is partially exposed to the second medium. Forming a medium opening, and forming a UBM underlayer that extends from above the second medium into the second medium opening and is electrically connected to the wiring in the second medium opening Forming a feed line so as to be electrically connected to the UBM underlayer at an interface between the second medium and the third medium, and a dicing region of the mother substrate. Electrically connected to the UBM underlayer Forming a conductive dicing line, forming a third medium on the second medium, and thirdly exposing the UBM foundation layer to the third medium. A step of forming a medium opening, a step of forming an under bump metal so as to be electrically connected to the UBM underlayer in the third medium opening by electrolytic plating, and the mother along the dicing line. And a step of dicing the substrate and taking out each boundary acoustic wave device.

  In a specific aspect of the manufacturing method according to the present invention, at least two of the step of forming the UBM underlayer, the step of forming the power supply line, and the step of forming the dicing line are made of the same conductive material. Used simultaneously.

  In another specific aspect of the manufacturing method according to the present invention, the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium is a sound absorbing film.

  In still another specific aspect of the manufacturing method according to the present invention, the first medium is a dielectric substrate, the second medium is a piezoelectric film, and the third medium is a sound absorbing film.

  According to the present invention, there is provided a three-medium type boundary acoustic wave device in which a second medium and a third medium are stacked on a first medium. In the present invention, the under bump metal is formed in the third medium opening provided in the third medium, and therefore, the bump is bonded by bonding the metal bump on the under bump metal. A boundary acoustic wave device can be provided. In addition, a UBM underlayer is bonded to the lower surface of the under bump metal, and the UBM underlayer is connected to a power supply line at the interface between the third medium and the second medium. Therefore, it is possible to form the under bump metal by electrolytic plating on the UBM underlayer by supplying power from the power supply line.

  In addition, since the feed line is provided at the interface between the second medium and the third medium, the portion of the feed line that reaches the outer surface of the boundary acoustic wave device, that is, the first medium, the second medium, and the second medium. The distance between the exposed portion of the feed line exposed at the end surface extending in the direction intersecting the stacking direction of the structure in which the medium and the third medium are stacked is sufficiently long. . That is, a power supply line is provided at the interface between the second medium and the third medium, which is an interface different from the interface between the second medium and the first medium in which the IDT is formed. As a result, even if moisture enters from the exposed portion, it is possible to lengthen the penetration path to the IDT, and therefore, it is possible to provide a highly reliable boundary acoustic wave device that is unlikely to be affected by moisture penetration. be able to.

  The third medium opening is positioned on the second medium opening so as to be continuous with the second medium opening, and the under bump metal is disposed from the third medium opening to the second medium. When formed so as to reach the inside of the opening, the third medium opening can be formed on the second medium opening, so that the second medium opening, the third medium opening, The boundary acoustic wave device can be miniaturized as compared with the case where these are separately provided.

  When the third medium opening and the under bump metal are arranged above the area where the IDT is formed, the third medium opening and the under bump are located outside the area where the IDT is formed. The boundary acoustic wave device can be downsized as compared with the case where metal is disposed. Further, since the distance between the plurality of bumps can be shortened, the stress between the bumps after being mounted on the mounting substrate can be reduced.

  When the third medium opening and the under bump metal are formed outside the upper portion of the region where the IDT is formed, the stress from the metal bump side formed on the under bump metal is Even if added, the stress is hardly transmitted to the IDT side. Therefore, it is possible to provide a boundary acoustic wave device in which the characteristic variation due to the stress hardly occurs.

  In the boundary acoustic wave device according to the present invention, the materials constituting the first to third media are not particularly limited, but the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium is a sound absorbing film. Or when the first medium is a dielectric substrate, the second medium is a piezoelectric film, and the third medium is a sound absorbing film, the third medium side from between the first and second media. Can be absorbed by the sound absorbing film, and good resonance characteristics and filter characteristics can be obtained.

  In the manufacturing method according to the present invention, under bump metal can be formed on the UBM underlayer by electrolytic plating at a stage where the UBM underlayer is partially exposed at the third medium opening. Therefore, a boundary acoustic wave device suitable for bump bonding can be easily provided. In particular, the UBM underlayer is electrically connected to a dicing line via a power supply line. Therefore, a voltage can be applied from the dicing line to the UBM underlayer through the power supply line, so that the under bump metal can be easily formed by electrolytic plating.

  In the boundary acoustic wave device obtained by dicing the mother substrate along the dicing line, the distance from the portion of the feed line exposed at the end surface of the boundary acoustic wave device to the IDT is made sufficiently long. Therefore, the fluctuation of characteristics due to moisture hardly occurs. Therefore, the boundary acoustic wave device excellent in reliability can be provided.

  In the case where at least two steps among the step of forming the UBM underlayer, the step of forming the power supply line, and the step of forming the dicing line are performed simultaneously using the same conductive material, simplification of the manufacturing method and material Cost reduction can be achieved.

  In the method for manufacturing a boundary acoustic wave device according to the present invention, the materials constituting the first to third media are not particularly limited, but the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium. Is a sound-absorbing film, or the first medium is a dielectric substrate, the second medium is a piezoelectric film, and the third medium is a sound-absorbing film. The bulk wave propagating to the medium side can be absorbed by the sound absorbing film, and good resonance characteristics and filter characteristics can be obtained.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

In the method for manufacturing a boundary acoustic wave device according to the present embodiment, first, a wafer for forming a piezoelectric substrate as a first medium is prepared. As a piezoelectric material constituting such a wafer, a piezoelectric single crystal such as LiTaO ₃ , LiNbO ₃ or quartz, or a piezoelectric ceramic can be used.

  FIG. 3A is a schematic plan view showing the structure of a stage in the middle of forming various electrodes on the wafer. As shown in FIG. 3A, the wafer 1 has a substantially circular shape, but the planar shape of the wafer 1 is not particularly limited. In this wafer 1, a large number of boundary acoustic wave devices are formed in a matrix. That is, a dicing line 2 made of a conductive material and a plurality of dicing lines 3 extending in parallel to the Y direction are formed on the wafer 1 so as to extend in parallel in the X direction at a predetermined interval. By dividing the wafer 1 along the dicing lines 2 and 3, individual boundary acoustic wave devices are cut out.

  As shown in FIG. 3A, the power supply terminals 4 and 5 are formed so as to be electrically connected to the dicing lines 2 and 3. The power supply terminals 4 and 5 constitute terminal portions to which a voltage is applied in the later-described electrolytic plating. The feed terminals 4 and 5 are made of the same conductive material as the dicing lines 2 and 3.

FIG. 3B is an enlarged plan view schematically showing a portion where one boundary acoustic wave device is formed in the wafer 1. One boundary acoustic wave device 6 is formed in a rectangular portion surrounded by the dicing line 2 and the dicing line 3. FIG. 2 is a front sectional view of a portion along the AA line of the single boundary acoustic wave device 6. In the boundary acoustic wave device 6, an insulating film 7 as a second medium and a sound absorbing film 8 as a third medium are stacked on a piezoelectric substrate 1 </ b> A obtained by cutting the wafer 1. Various electrodes including IDT 9 are formed at the interface between the piezoelectric substrate 1 </ b> A and the insulating film 7. The insulating film 7 is made of an appropriate insulating material such as SiO ₂ . The insulating film 7 can be made of an appropriate inorganic or organic insulating material other than SiO ₂ .

  The sound absorbing film 8 is provided to protect the insulating film 7. The sound absorbing film 8 can be made of an appropriate organic material such as polyimide or epoxy resin, or an appropriate inorganic material. The sound absorbing film 8 functions to absorb a bulk wave radiated from an IDT, which will be described later, and is therefore named a sound absorbing film.

In this embodiment and the embodiments described later, the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium is a sound absorbing film. However, the first medium is a dielectric substrate, and the second medium is a second substrate. The medium may be a piezoelectric film, and the third medium may be a sound absorbing film. In this case, an appropriate dielectric material such as SiO ₂ can be used as the dielectric substrate. As the piezoelectric material constituting the piezoelectric film, a piezoelectric material similar to the piezoelectric material constituting the piezoelectric substrate can be used.

  At least one IDT 9 is formed at the boundary between the piezoelectric substrate 1 </ b> A and the insulating film 7. In the present embodiment, reflectors are arranged on both sides of the IDT 9 in the boundary acoustic wave propagation direction to constitute a boundary acoustic wave resonator. However, the electrode structure including the IDT 9 can be appropriately modified so as to constitute an appropriate resonator or filter.

  The IDT 9 can be made of, for example, Al, Cu, or other appropriate metal or alloy. Moreover, IDT9 may be formed of the laminated film formed by laminating a plurality of metals.

  3B, in the boundary acoustic wave device 6, metal bumps 11a to 11d for performing bump bonding are formed on the upper surface of the sound absorbing film 8. As shown in FIG. FIG. 3B shows a state before the metal bumps 11a to 11d are formed. As described above, the formation positions of the metal bumps 11a to 11d are indicated by alternate long and short dash lines. The metal bumps 11a to 11d are made of an appropriate metal such as a metal bump.

  Since the metal bumps 11a to 11d are formed on the upper surface of the sound absorbing film 8, the upper surface side of the sound absorbing film 8 is opposed to the mounting substrate, and the boundary acoustic wave device 6 is easily and enlarged by bump bonding. It can be installed without.

  Next, the manufacturing method of the boundary acoustic wave device 6 will be described more specifically with reference to FIG.

  First, as shown in FIG. 4A, an IDT 9 is formed on the wafer 1. 4A to 4D, only a part of the wafer 1 is taken out and illustrated in an enlarged front sectional view. Actually, each boundary acoustic wave device 6 is obtained by dividing the wafer 1 along the dicing lines 2 and 3 described above at the final stage of the manufacturing process, as will be described later.

  FIG. 4A is an enlarged cross-sectional view of a portion along the line BB in FIG. An IDT 9 is first formed on the wafer 1 by photolithography or the like. Next, as illustrated in FIG. 4B, the wiring 12 is formed so as to be electrically connected to the IDT 9. The wiring 12 is made of an appropriate metal such as AlCu. However, it is desirable that the wiring 12 has as low an electrical resistance as possible. Therefore, it is desirable to form the wiring 12 having a thickness greater than that of the IDT 9.

  The wiring 12 desirably has an adhesion layer for ensuring adhesion strength between the piezoelectric substrate and the IDT. That is, it is desirable to stack an adhesive layer made of a metal having a higher adhesion to the piezoelectric substrate and the IDT, such as Ni, NiCr, and Ti, on the main electrode layer such as Al. The formation method of the wiring 12 is not particularly limited, and may be performed by an appropriate thin film formation method.

Next, as shown in FIG. 4C, an insulating film 7 is formed on the wafer 1 so as to cover the IDT 9. In the present embodiment, the insulating film 7 is made of SiO ₂ and has a thickness of about several μm to several tens μm. The insulating film 7 can be formed by an appropriate thin film forming method such as sputtering.

  Next, as shown in FIG. 4D, an insulating film opening 7 a is formed in the insulating film 7. The insulating film opening 7a is formed so that a part of the wiring 12 is exposed. The insulating film opening 7a can be formed by a dry etching method such as reactive ion etching, for example. However, the insulating film opening 7a may be formed by a method other than the dry etching method.

  Next, as shown in FIG. 5A, in the insulating film opening 7a, the UBM foundation layer 13, the feed line 14, and the dicing line 3 are simultaneously formed using the same conductive material. In FIG. 5A, the UBM underlayer 13, the feed line 14, and the dicing line 3 are illustrated with different hatching, but in the present embodiment, they are formed simultaneously and in a single band with the same conductive material. The UBM underlayer 13 is provided for forming an under bump metal (UBM), which will be described later, by electrolytic plating thereon. That is, it functions as an underlayer for forming the under bump metal by electrolytic plating. However, the UBM underlayer 13 is formed not only at the portion where the under bump metal is provided, but also on the surface of the insulating film 7, that is, the interface between the insulating film 7 and the sound absorbing film 8. And it is connected with the electric power feeding line 14 provided in the interface of the insulating film 7 and the sound absorption film 8. FIG. The dicing line 3 is formed on the insulating film 7 so as to be connected to the power supply line 14.

  Therefore, although not shown in the dicing line 3 and FIG. 5A, the dicing line 2 shown in FIG. 3A is formed at the interface between the insulating film 7 and the sound absorbing film 8. Therefore, in FIG. 3A, the dicing lines 2 and 3 are indicated by broken lines in a plan view.

  The UBM underlayer 13, the feed line 14, and the dicing line 3 are made of a suitable metal such as Al or Cu. However, preferably, in order to ensure the adhesion strength to the insulating film 7 and the wiring 12, it is desirable to have a structure in which an adhesion layer made of Ni, NiCr, Ti, or the like is laminated on the electrode layer. More preferably, it is desirable to further laminate a metal film having excellent corrosion resistance, for example, a corrosion-resistant metal layer made of Ni or Pt.

  That is, a structure in which an adhesion layer, a main electrode layer, and a corrosion-resistant metal layer are laminated in this order is more desirable.

  The power supply line 14 is connected to the dicing line 3, and the dicing line 3 is electrically connected to the power supply terminals 4 and 5 as shown in FIG. Therefore, the power supply terminals 4 and 5 and the UBM underlayer 13 are electrically connected.

  Next, as shown in FIG. 5B, an epoxy resin film is formed as the sound absorbing film 8. The epoxy resin film is formed by applying and curing a thermosetting epoxy resin composition or a photocurable epoxy resin composition. Other resins such as polyimide other than epoxy resin may be used. By forming the sound absorbing film 8, the insulating film opening 7 a is filled with the resin material constituting the sound absorbing film 8. Thereafter, an opening 8a is formed in the sound absorbing film 8 as shown in FIG. In forming the sound absorbing film opening 8a, the insulating film opening 7a is exposed again by removing the constituent material of the sound absorbing film 8 buried below the sound absorbing film opening 8a. Such an opening can be formed by an appropriate method such as photolithography using a photosensitive resin or the like. Therefore, the insulating film opening 7a is formed again, and the UBM foundation layer 13 is exposed to the bottom of the insulating film opening 7a again.

  Next, a voltage is applied from the power supply terminals 4 and 5 shown in FIG. 3A, and a UBM is formed by electrolytic plating. As shown in FIG. 5D, the UBM 15 is formed in this way. In the present embodiment, the UBM 15 is formed by electrolytic plating of Ni as a metal.

  In this embodiment, the UBM is formed by electrolytic plating of Ni. However, the UBM can be formed of an appropriate metal other than Ni. As shown in FIG. 5D, the UBM 15 is preferably formed so that the upper surface 8a of the sound absorbing film 8 is flush with the upper surface. Thereby, formation of metal bumps is facilitated.

  Next, metal bumps such as solder are formed on the UBM 15 by a printing method or the like. In this manner, the metal bumps 11a to 11d shown in FIG. 1B are provided.

  Next, the wafer 1 is cut so as to remove portions where the dicing lines 2 and 3 are formed along the dicing lines 2 and 3 shown in FIG. In dicing, the dicing regions 2A and 3A including the dicing lines 2 and 3 shown in FIG. 1A are removed, and is a cross-sectional view taken along the line P-P in FIG. As shown in 1 (b), the end face 6a is formed by cutting. In this way, each boundary acoustic wave device 6 is taken out.

  In the obtained boundary acoustic wave device 6, since the metal bumps 11a to 11d are provided, they can be mounted on the mounting substrate by bump bonding.

  Further, when the UBM 15 is formed, a current flows through the path of the feed terminal 4, 5-dicing line 2, 3-feed line 14-UBM underlayer 13, and the UBM 15 is formed by electrolytic plating. A large number of UBMs can be easily formed on the wafer 1.

  In addition, dicing is performed so that the conductive dicing lines 2 and 3 are removed. That is, the width of the portion to be removed during dicing is made larger than the width of the dicing lines 2 and 3. Therefore, as shown in FIG. 1B, there is no dicing line on the end surface 6 a of the obtained boundary acoustic wave device 6. However, as shown in FIGS. 1B and 1C, the power supply line 14 is exposed on the end face 6a. The end surface 6a extends in a direction orthogonal to the main surface of the wafer 1, but the end surface 6a is insulated from the piezoelectric substrate in the boundary acoustic wave device in a structure in which the piezoelectric substrate, the insulating film, and the dielectric film are laminated. It suffices if it extends in a direction intersecting the boundary surface with the film, and does not necessarily extend in a direction orthogonal to the film.

  However, even if moisture enters from the portion where the power supply line 14 is provided, the path between the portion exposed on the end face 6a of the power supply line 14 and the IDT 9 is lengthened. That is, unlike the above-described embodiment, when the power supply line 14 is formed at the interface between the piezoelectric substrate 1A and the insulating film 7, the portion where the power supply line is finally exposed on the end face 6a and the IDT 9 are the same. In the above embodiment, the exposed portion of the feeder line 14 and the IDT 9 are formed at different interfaces, and the distance between the two is relatively long. . Therefore, even if moisture invades slightly, it is difficult to reach IDT 9 and thus reliability can be improved.

  In the boundary acoustic wave device, when the feed line 14 is finally exposed to the end face 6a, the feed line 14 may be corroded by moisture, or moisture may enter the inside through the surface of the feed line 14. In this case, in the boundary acoustic wave device 6, the interface between the piezoelectric substrate 1A and the insulating film 7 is a part where the IDT 9 is formed, and is an important part where excitation / excitation of the boundary acoustic wave is performed. On the other hand, the power supply line 14 for forming the UBM by electrolytic plating is a portion that is not necessary at the time of mounting in the boundary acoustic wave device 6 finally connected. Therefore, it is effective to prevent deterioration of characteristics due to intrusion of moisture and the like by positioning the power supply line 14 not at the interface between the piezoelectric substrate 1A and the insulating film 7 but at the interface between the insulating film 7 and the sound absorbing film 8. It is.

  In the above embodiment, as shown in FIG. 5A, the UBM foundation layer 13, the feed line 14 and the dicing line 3 are formed in the same process using the same conductive material, but these are different processes. It may be formed. Moreover, these may be formed of different conductive materials. However, as described above, by simultaneously forming the UBM underlayer 13, the power supply line 14, and the dicing line 3 with the same conductive material, the process can be simplified and the material cost can be reduced. Further, at least two of the UBM underlayer 13, the power supply line 14, and the dicing line may be simultaneously formed in the same process.

  In the above embodiment, as schematically shown in FIG. 1A, the metal bumps 11a to 11d and the metal bumps 11a to 11d are on the upper surface outside the region above the portion where the IDT 9 is formed. The UBM to be formed was placed. Therefore, even when a stress is applied to the mounting structure of the boundary acoustic wave device 6 from the metal bumps 11a to 11d in the layer, the stress is not easily transmitted to the IDT 9. Therefore, the characteristic hardly changes due to the stress at the time of mounting.

  In addition to the wiring 12 formed between the piezoelectric substrate and the insulating film, an electrical wiring may be formed between the insulating film and the sound absorbing film, and the electrical wiring may be connected to the wiring 12. Three-dimensional wiring may be configured between the two. In particular, when a plurality of filter elements and resonators are formed by boundary acoustic waves, efficient wiring can be performed by configuring an electrical wiring between the insulating film and the sound absorbing film.

  6A and 6B are schematic partial cutaway plan views for explaining the boundary acoustic wave device according to the second embodiment of the present invention, and along the line SS in FIG. 6A. It is a typical partial front sectional view.

  In the boundary acoustic wave device 21 of the second embodiment, the metal bumps 22a to 22d are located above the region where the IDT 9 is provided. That is, as shown in FIG. 6B, in the second embodiment, the IDT 9 and the wiring 12 are formed on the piezoelectric substrate 1A, and the insulating film 7 is formed so as to cover the IDT 9. Further, the insulating film opening 7a is formed in the insulating film 7 in the same manner as in the first embodiment. In the second embodiment, the insulating film opening 7a has a smaller diameter than that of the first embodiment.

  However, the sound absorbing film 8 is formed on the insulating film 7 so as to enter the insulating film opening 7a. The sound absorbing film opening 8a provided in the sound absorbing film 8 is formed so as not to overlap the insulating film opening 7a. That is, the sound absorbing film opening 8a is formed above the region where the IDT 9 is provided. The UBM foundation layer 13 has a portion reaching the bottom of the insulating film opening 7a so as to be electrically connected to the lower wiring 12 in the insulating film opening 7a.

  However, the UBM foundation layer 13 reaches the bottom of the insulating film opening 7 a, and the second connection reaches the interface between the insulating film 7 and the sound absorbing film 8 on both sides of the portion 13 a connected to the wiring 12. It has the parts 13b and 13c. That is, the portion 13a is formed so as to extend from the portion connected to the wiring 12 to the side surface of the insulating film opening 7a, and is connected to the connecting portions 13b and 13c at the upper end of the portion reaching the side surface. . One connection portion 13 b of the UBM foundation layer 13 is connected to the power supply line 14. The other connecting portion 13c reaches above the region where the IDT 9 is provided, and reaches the sound absorbing film opening 8a provided in the region above the portion where the IDT 9 is provided.

  In the second embodiment, the UBM 23 is formed by electrolytic plating at the sound absorbing film opening 8a by electrolytic plating with the end of the connection portion 13c of the UBM base layer 13 as a base.

  As shown in FIG. 6A, the metal bumps 22a to 22d are formed on the UBM provided as described above.

  As in the second embodiment, the UBM 23 is formed above the region where the IDT 9 is provided, and the metal bumps 22a to 22d are arranged above the region where the IDT 9 is provided, whereby the boundary acoustic wave device 21 is formed. Mounting space can be reduced. That is, it is possible to increase the arrangement density of the metal bumps 22a to 22d, reduce the mounting space, and reduce the size of the boundary acoustic wave device 21 itself.

  The boundary acoustic wave device 21 of the second embodiment is configured in the same manner as the boundary acoustic wave device 6 of the first embodiment except for the above points. Therefore, also in the boundary acoustic wave device 21 of the second embodiment, the UBM can be formed by electrolytic plating using the feed line 14. Further, since the distance between the portion where the feed line 14 is exposed and the IDT 9 is relatively long after dicing, the characteristics are hardly changed due to intrusion or the like.

  7A and 7B are a schematic plan view for explaining a boundary acoustic wave device according to a third embodiment of the present invention and a manufacturing method thereof, and a TT line in FIG. 7A. It is a typical partial notch front sectional drawing of the part in alignment with. The boundary acoustic wave device 31 of the third embodiment corresponds to a modification of the boundary acoustic wave device 21 of the second embodiment. That is, as shown in FIG. 7B, the sound absorbing film opening 8a is formed in the outer region above the region where the IDT 9 is provided, more specifically in the region closer to the end face 6a. In the sound absorbing film 8a, the UBM 33 is formed by electrolytic plating, as in the case of the second embodiment. As shown in FIG. 7A, metal bumps 32a to 32d are formed on the UBM 33 formed as shown.

  Therefore, in the boundary acoustic wave device 31 of the third embodiment, even if a stress is applied during the mounting in the portion where the metal bumps 32a to 32d are provided, the stress is not easily transmitted to the IDT 9, and the characteristics due to the stress are It has the advantage that fluctuations are less likely to occur.

  Also in the third embodiment, the power supply line 14 is exposed to the end face 6a, but the distance between the exposed portion of the power supply line 14 and the IDT 9 is set to a sufficient length, so that moisture can enter. Variations in characteristics due to are difficult to occur.

  In the third embodiment, the UBM 33 is formed on the connection portion 34 b connected to the power supply line 14 of the UBM foundation layer 34. That is, the UBM foundation layer 34 includes a portion 34a connected to the wiring 12 in the insulating film opening 7a and the connection portion 34b.

(A) is the top view which shows a boundary acoustic wave apparatus typically in the manufacturing method of the boundary acoustic wave apparatus concerning the 1st Embodiment of this invention, (b) is the 1st principal part of a boundary acoustic wave apparatus. It is front sectional drawing of the part in alignment with the PP line in Fig.1 (a) which shows the state after this dicing, (c) is a side view which shows the end surface cut out by dicing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic partially cutaway front sectional view for explaining the structure of a boundary acoustic wave device according to a first embodiment of the present invention. (A) is a schematic plan view for demonstrating the wafer and dicing line which are prepared with the manufacturing method of the 1st Embodiment of this invention, (b) is one elastic boundary wave apparatus in a wafer. The enlarged plan view of the part currently comprised. (A)-(d) is each partial front sectional drawing for demonstrating the manufacturing process of the elastic boundary wave apparatus of 1st Embodiment. (A)-(d) is each partial front sectional drawing for demonstrating the manufacturing process of the elastic boundary wave apparatus of 1st Embodiment. (A) is a schematic plan view for explaining the positions of metal bumps formed on a wafer in the method for manufacturing a boundary acoustic wave device according to the second embodiment of the present invention, and (b) shows the boundary acoustic wave. The fragmentary front sectional view of the part which followed the SS line in (a) which shows the principal part of an apparatus. (A) is a schematic plan view for explaining the positions of metal bumps formed on a wafer by the method for manufacturing a boundary acoustic wave device according to the third embodiment of the present invention, and (b) shows the boundary acoustic wave. The fragmentary front sectional view which follows the TT line | wire in (a) which shows the principal part of an apparatus. A typical sectional view showing an example of the conventional boundary acoustic wave device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer 1A ... Piezoelectric substrate 2, 3 ... Dicing line 6 ... Elastic boundary wave apparatus 7 ... Insulating film 7a ... Insulating film opening 8 ... Sound absorbing film 8a ... Sound absorbing film opening 9 ... IDT
11a to 11d ... Metal bump 12 ... Wiring 13 ... UBM underlayer 13a ... Part 13b, 13c ... Connection part 14 ... Feed line 15 ... UBM
21 ... boundary acoustic wave device 22a-22d ... metal bump 23 ... UBM
31 ... boundary acoustic wave devices 32a to 32d ... metal bumps 33 ... UBM
34 ... UBM underlayer

Claims (10)

A first medium; an IDT provided on the first medium; a second medium provided on the first medium so as to cover the IDT; and the second medium. In the boundary acoustic wave device having the third medium,
A wiring formed on the first medium so as to be electrically connected to the IDT;
The second medium has a second medium opening partly exposing the wiring,
The third medium has a third medium opening;
An under bump metal formed in the third medium opening;
Bonded to the lower surface of the under bump metal, and between the third medium and the second medium, at the interface between the second medium and the first medium at the second medium opening. A UBM foundation layer electrically connected to the IDT at the interface;
A feed line electrically connected to the UBM underlayer at the interface between the second medium and the third medium ;
The feed line has a structure in which the first medium, the second medium, and the third medium of the boundary acoustic wave device are stacked at the interface between the second medium and the third medium. The boundary acoustic wave device is exposed at an end surface extending in a direction intersecting with the laminating direction . The third medium opening is disposed on the second medium opening so as to be continuous with the second medium opening, and the under bump metal is disposed from the third medium opening to the second medium opening. The boundary acoustic wave device according to claim 1 , wherein the boundary acoustic wave device is formed so as to reach the inside of the two medium openings. The boundary acoustic wave device according to claim 1 , wherein the third medium opening and the under bump metal are disposed above a region where the IDT is formed. 2. The boundary acoustic wave device according to claim 1 , wherein the third medium opening and the under bump metal are formed in a portion other than above the region where the IDT is formed. The boundary acoustic wave according to any one of claims 1 to 4 , wherein the first medium is a piezoelectric substrate, the second medium is an insulating film, and the third medium is a sound absorbing film. apparatus. Said first medium is a dielectric substrate, the second medium piezoelectric film, wherein the third medium is absorbing film, the elastic according to any one of claims 1-4 Boundary wave device. Preparing a mother substrate made of a first medium;
Forming an IDT on the mother substrate;
Forming a wiring so as to be electrically connected to the IDT;
Forming a second medium on the mother substrate on which the IDT is formed so as to cover the IDT;
Forming a second medium opening in which the wiring is partially exposed in the second medium;
Forming a UBM foundation layer extending from above the second medium into the second medium opening and electrically connected to the wiring in the second medium opening;
Forming a power supply line so as to be electrically connected to the UBM underlayer at an interface between the second medium and the third medium;
Forming a conductive dicing line electrically connected to the UBM underlayer in a region of the mother substrate to be diced;
Forming a third medium on the second medium;
Forming a third medium opening in the third medium to partially expose the UBM foundation layer;
Forming an under bump metal in the third medium opening by electrolytic plating so as to be electrically connected to the UBM underlayer;
And a step of dicing the mother substrate along the dicing line and taking out the individual boundary acoustic wave devices. The elastic according to claim 7 , wherein at least two of the step of forming the UBM foundation layer, the step of forming the power supply line, and the step of forming the dicing line are performed simultaneously using the same conductive material. Boundary wave device manufacturing method. It said first medium is a piezoelectric substrate, the second medium is an insulating film, the third medium is characterized in that it is a sound-absorbing layer, the manufacturing method of the boundary acoustic wave device according to claim 7 or 8. Characterized in that said first medium is a dielectric substrate, the second medium piezoelectric film, the third medium is sound-absorbing layer, the production of the boundary acoustic wave device according to claim 7 or 8 Method.

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