JP2011077601A - Elastic wave device and method of manufacturing elastic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic wave device in which an electrode pad hardly corrodes and which has excellent reliability, and to provide a method of manufacturing the same. <P>SOLUTION: The elastic wave device includes: a piezoelectric substrate 3; an excitation electrode 5 arranged on the principal plane 3a of the piezoelectric substrate 3; an electrode pad 13 arranged on the principal plane 3a of the piezoelectric substrate 3 and electrically connected to the excitation electrode 5; a protection cover 9 comprising a frame 19 arranged on the piezoelectric substrate to enclose the excitation electrode 5 and cover the electrode pad 13, and a lid 21 for closing an opening of the frame 19; a through conductor 15 erected on the electrode pad 13 to go through the protection cover 9 in a thickness direction; a terminal 4 arranged on the protection cover, connected to a face opposite from the electrode pad side of the through conductor 15, wherein an outer circumferential edge is located beyond the outer circumferential edge of the through conductor 15 in plan view; and an annular conductor 2 arranged in the protection cover and connected to the terminal 4 while enclosing the through conductor 15. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an elastic wave device such as a surface acoustic wave (SAW) device and a piezoelectric thin film resonator (FBAR), and a method for manufacturing the same.

  2. Description of the Related Art A so-called wafer level package acoustic wave device for the purpose of downsizing and the like is known. In this acoustic wave device, excitation electrodes disposed on the main surface of the element substrate are accommodated in the vibration space. The vibration space is formed by a hollow portion provided in the protective cover. In addition, a through conductor penetrating the protective cover is erected on an electrode pad connected to the excitation electrode, and a terminal connected to the through conductor is provided on the protective cover (see, for example, Patent Document 1).

JP 2007-208665 A

  By the way, in the elastic wave device having the above-described structure, separation may occur between the protective cover and the through conductor due to a difference in linear expansion coefficient between the protective cover and the through conductor. When peeling occurs between the protective cover and the through conductor in this way, the peeling easily reaches the connecting portion between the through conductor and the electrode pad, starting from the peeling. Normally, the electrode pad is made of aluminum or the like that is easily corroded by moisture, so when the peeling reaches the connection part between the through conductor and the electrode pad, the electrode pad is corroded by moisture that has penetrated from the peeling part. May end up.

  When the electrode pad is corroded, the electrical characteristics of the acoustic wave device are deteriorated, and conduction failure between the penetrating conductor and the electrode pad occurs, leading to a decrease in reliability of the acoustic wave device.

  The present invention has been invented to address the above-described problems, and provides an elastic wave device and an elastic wave device manufacturing method that are less likely to cause corrosion of electrode pads and that are excellent in reliability.

  The acoustic wave device of the present invention includes a piezoelectric substrate, an excitation electrode disposed on the main surface of the piezoelectric substrate, an electrode pad disposed on the main surface of the piezoelectric substrate and electrically connected to the excitation electrode, A protective cover comprising a frame portion that is disposed on the piezoelectric substrate so as to surround the excitation electrode and cover the electrode pad, and a lid portion that is disposed on the frame portion so as to close the opening of the frame portion. And a through conductor standing on the electrode pad and penetrating the protective cover in the thickness direction, and disposed on the protective cover and connected to the surface of the through conductor opposite to the electrode pad side, as viewed in plan A terminal whose outer peripheral edge is located outside the outer peripheral edge of the through conductor, and an annular conductor disposed in the protective cover and connected to the terminal in a state of surrounding the through conductor. With That.

  According to the present invention, it is difficult for moisture to reach the electrode pad, and corrosion of the electrode pad can be reduced. As a result, it is possible to provide an elastic wave device having excellent reliability and a method for manufacturing the elastic wave device.

(A) is a top view which shows the surface acoustic wave apparatus which concerns on embodiment of this invention, (b) is a top view of the state which removed the protective cover of the surface acoustic wave apparatus shown to Fig.1 (a). (A) is sectional drawing in the Ia-Ia line of Fig.1 (a), (b) is sectional drawing in the Ib-Ib line of Fig.1 (a). (A) is sectional drawing to which a part of surface acoustic wave apparatus which concerns on embodiment of this invention was expanded, (b) is sectional drawing to which a part of surface acoustic wave apparatus as a comparative example was expanded. It is sectional drawing to which a part of surface acoustic wave apparatus concerning the modification of embodiment of this invention was expanded. It is sectional drawing to which a part of surface acoustic wave apparatus as a comparative example was expanded. It is sectional drawing which expanded a part of surface acoustic wave apparatus concerning another modification of embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the surface acoustic wave apparatus which concerns on embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the surface acoustic wave apparatus which concerns on embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the surface acoustic wave apparatus which concerns on embodiment of this invention.

  FIG. 1A is a plan view showing a surface acoustic wave device 1 according to an embodiment of the present invention. FIG. 1B is a plan view of the surface acoustic wave device 1 shown in FIG. 1A with the protective cover 9 removed. 2A is a cross-sectional view taken along line Ia-Ia in FIG. 1A, and FIG. 2B is a cross-sectional view taken along line Ib-Ib in FIG. 1 and 2 schematically show the surface acoustic wave device 1 in order to facilitate understanding of the surface acoustic wave device 1. In implementation, the size of each part of the surface acoustic wave device 1 is shown. The number, shape, etc. may be set as appropriate.

  The surface acoustic wave device 1 includes a piezoelectric substrate 3, an excitation electrode 5 disposed on the piezoelectric substrate 3, a protective cover 9 for protecting the excitation electrode 5, and an electrode pad connected to the excitation electrode 5 via a connection wiring 11. 13, a through conductor 15 standing on the electrode pad 13, a terminal 4 connected to the through conductor 15, and an annular conductor 2 connected to the terminal 4 so as to surround the through conductor 15. In FIG. 1A, the annular conductor 2 positioned below the terminal 4 is indicated by a dotted line, and the through conductor 15 is indicated by a one-dot chain line.

  The piezoelectric substrate 3 is a rectangular parallelepiped single crystal substrate having piezoelectricity such as a lithium tantalate single crystal or a lithium niobate single crystal. The longitudinal width of the piezoelectric substrate 3 is, for example, 0.5 mm to 2.0 mm, the lateral width is, for example, 0.3 mm to 1.6 mm, and the thickness is, for example, 0.1 mm to 0.5 mm.

  The piezoelectric substrate 3 has a first main surface 3a and a second main surface 3b on the back side. In the present embodiment, nothing is formed on the second main surface 3b side, but a resin layer or the like for protecting the piezoelectric substrate 3 may be formed.

  The excitation electrode 5 is formed on the first main surface 3a of the piezoelectric substrate 3 and has a plurality of pairs of comb-like electrodes. The comb-like electrode has a plurality of electrode fingers extending in a direction perpendicular to the propagation direction of the surface acoustic wave in the piezoelectric substrate 3 (the vertical direction in the drawing of FIG. 1). The pair of comb-shaped electrodes are formed so that the electrode fingers mesh with each other. In the present embodiment, the excitation electrode 5 shown on the right side of FIG. 1B functions as a dual-mode surface acoustic wave filter, and the excitation electrode 5 shown on the left side exhibits the characteristics of a dual-mode surface acoustic wave filter. Functions as a resonator to be adjusted. FIG. 1 is a schematic diagram, and actually, a plurality of pairs of comb-like electrodes having a larger number of electrode fingers than those shown are provided. Further, a plurality of excitation electrodes 5 may be connected by a system such as series connection or parallel connection, and a ladder type surface acoustic wave filter or the like may be configured. At both ends of the excitation electrode 5, reflectors having comb-like electrodes (may be regarded as a part of the excitation electrode 5) are provided. The excitation electrode 5 is formed of, for example, an Al alloy such as an Al—Cu alloy, and the thickness thereof is, for example, 0.1 μm to 1.0 μm.

  In addition to the excitation electrode 5, an electrode pad 13 and a connection wiring 11 are formed on the first main surface 3 a of the piezoelectric substrate 3. The connection wiring 11 is for connecting the excitation electrode 5 and a predetermined electrode pad 13. As shown in FIG. 1B, the connection wiring 11 is formed in an appropriate pattern on the first main surface 3 a and is connected to the excitation electrode 5. In FIG. 1B, the connection wiring 11 connected to the electrode pad 13 located at the center on the upper side of the piezoelectric substrate 3 among the plurality of electrode pads 13 includes the other connection wiring 11 and the insulating member 8. Crossing through. Thus, by using the insulating member 8 to connect the connection wirings 11 in a three-dimensional manner, the degree of freedom of the arrangement location of the electrode pads 13 is improved, which can contribute to downsizing of the surface acoustic wave device. The insulating member 8 is made of, for example, polyimide resin.

  A plurality of electrode pads 13 are provided, and the number is six in this embodiment. In FIG. 1B, the three electrode pads 13 arranged on the upper side center, the lower side center, and the lower left side of the piezoelectric substrate 3 are ground electrode pads. In FIG. 1B, electrode pads 13 arranged on the upper left, upper right and lower right of the piezoelectric substrate 3 are electrode pads for input / output signals. The electrode pad 13 is formed so as to have a somewhat large area in order to provide the through conductor 15 thereon, and has a circular shape with a diameter of 20 μm to 100 μm, for example. The shape of the electrode pad 13 is not limited to a circle, and may be an ellipse or a rectangle. The electrode pad 13 and the connection wiring 11 can be formed by the same process as the excitation electrode 5 using the same material as the excitation electrode 5, or can be formed by another process using another material. In the present embodiment, the electrode pad 13 and the connection wiring 11 are made of the same Al alloy as that of the excitation electrode 5, and the thickness thereof is, for example, 0.1 μm to 1.0 μm.

  As shown in FIG. 2, a protective film 7 is provided over substantially the entire first main surface 3 a of the piezoelectric substrate 3 so as to cover the excitation electrode 5 and the connection wiring 11. Thus, by covering the excitation electrode 5 and the connection wiring 11 with the protective film 7, it can suppress that the excitation electrode 5 and the connection wiring 11 oxidize. The protective film 7 is formed of, for example, a material having an insulating property and a mass that is light enough not to affect the propagation of the surface acoustic wave. For example, silicon oxide, silicon nitride, silicon, or the like is preferably used.

  The protective film 7 is formed so as to cover a part of the electrode pad 13. Specifically, it is formed to have an opening 7o that exposes the central portion of the electrode pad 13, and a through conductor 15 is connected to a portion exposed from the opening 7o of the electrode pad 13. Yes. In other words, a portion of the electrode pad 13 that is not connected to the through conductor 15 is covered with the protective film 7. Thus, by covering the portion of the electrode pad 13 that is not connected to the through conductor 15 with the protective film 7, the protective film 7 is interposed between the electrode pad 13 and the protective cover 9. That is, the electrode pad 13 and the protective cover 9 can be in a state where there is almost no portion in direct contact. Compared with the adhesive force between the electrode pad 13 and the protective cover 9, the adhesive force between the protective film 7 and the protective cover 9 is very strong. Therefore, by providing the protective film 7 between the electrode pad 13 and the protective cover 9 as in the present embodiment, the protective cover is formed at that portion, rather than when the electrode pad 13 and the protective cover 9 are in direct contact with each other. It can suppress that 9 peels.

  A protective cover 9 is provided on the first main surface 3a side of the piezoelectric substrate 3 on which the excitation electrode 5, the electrode pad 13, the protective film 7 and the like are formed. The protective cover 9 constitutes a vibration space 6 on the excitation electrode 5 for facilitating the propagation of surface acoustic waves. In other words, the protective cover 9 includes the frame portion 19 that forms the inner wall 19 a of the vibration space 6 and the lid portion 21 that forms the ceiling 21 a of the vibration space 6.

  The thickness of the layer constituting the frame portion 19 and the thickness of the lid portion 21 may be set as appropriate. For example, the thickness is several μm to 30 μm. The frame portion 19 and the lid portion 21 are formed to have substantially the same thickness.

  The frame portion 19 and the lid portion 21 can be formed of different materials, but are preferably formed of the same material in order to increase the adhesive strength between the frame portion 19 and the lid portion 21. The frame portion 19 and the lid portion 21 are formed of, for example, a photocurable material that is cured by being irradiated with light such as ultraviolet rays or visible light, for example, a negative photoresist. As the photocurable material, a resin curable by radical polymerization such as an acrylic group or a methacrylic group can be used. More specifically, urethane acrylate, polyester acrylate, or epoxy acrylate resins can be used. In the drawing, for convenience of explanation, the frame portion 19 and the lid portion 21 are clearly shown as the boundary line between the frame portion 19 and the lid portion 21, but the frame portion 19 and the lid portion 21 may be integrally formed.

  Thus, by using the protective cover 9 made of resin to secure the vibration space 6 on the piezoelectric substrate, the entire surface size is reduced to the same size as the plane size of the piezoelectric substrate 3. It can be a device.

  As shown in FIG. 2, the vibration space 6 is formed so that the cross section is substantially rectangular and the corner on the lid 21 side is rounded. In other words, the inner wall 19a and the ceiling 21a constituting the vibration space 6 are formed in an arch shape. Thereby, it can suppress that the cover part 21 bends. As a result, for example, the surface acoustic wave device 1 can be downsized by reducing the height of the vibration space 6. The planar shape of the vibration space 6 (the shape when viewed from the first main surface 3a side) may be set as appropriate. FIG. 1B shows an inner wall 19a corresponding to the outer periphery of the vibration space 6 by a dotted line.

  A through conductor 15 is provided so as to penetrate the protective cover 9. The through conductor 15 stands on each electrode pad 15. The excitation electrode 5 can be electrically connected to an external electric circuit or the ground through the through conductor 15. In order to reinforce the connection between the electrode pad 13 and the through conductor 15, a connection reinforcing layer made of chromium, nickel, or gold may be interposed between the electrode pad 13 and the through conductor 15.

  The through conductor 15 is formed of, for example, Cu, Au, Ni, or solder. The through conductor 15 is formed in a columnar shape, for example, and has a diameter in a plan view of 20 μm to 120 μm.

  In the present embodiment, the through conductor 15 is formed by a plating method, and a plating base layer 16 is formed between the through conductor 15 and the protective cover 9.

  A terminal 4 is connected to the tip of the through conductor 15 exposed from the protective cover 9. The terminal 4 is formed in, for example, a disk shape, and the outer peripheral edge when viewed from above is located outside the outer peripheral edge of the through conductor 15. The diameter of the terminal 4 is formed so as to be about 5 μm to 100 μm larger than the diameter of the through conductor 15. Further, the terminals 4 and the through conductors 15 are arranged so that their central axes substantially coincide. In the present embodiment, the terminal 4 is made of Cu, for example, and is integrally formed with the through conductor 15 by a plating method. By connecting the terminal 4 and an external circuit board with a conductive adhesive such as solder, the surface acoustic wave device 1 is electrically and mechanically connected to the external circuit board.

  An annular conductor 2 is connected to the terminal 4. The annular conductor 2 is formed in an annular shape so as to surround the through conductor 15. The annular conductor 2 is disposed in the protective cover 9, and a gap between the annular conductor 2 and the through conductor 15 is filled with a resin constituting the protective cover 9. Yes. Providing the annular conductor 2 makes it difficult for moisture to reach the electrode pad 13. This will be described with reference to FIG. FIG. 3 is an enlarged cross-sectional view of the through conductor 15 and its peripheral portion, (a) is a view when the annular conductor 2 is provided, and (b) is a view when the annular conductor 2 is not provided. The white arrow in the middle indicates the moisture intrusion path when peeling occurs between the through conductor 15 and the protective cover 9. When the annular conductor 2 is not provided, moisture reaches the electrode pad 13 almost linearly along the side surface of the through conductor 15 as shown in FIG. In contrast, the moisture intrusion path when the annular conductor 2 is provided is along the side surface of the annular conductor 2 and the side surface of the through conductor 15 as shown in FIG. That is, by providing the annular conductor 2, the moisture intrusion path can be lengthened by an amount that bypasses the side surface of the annular conductor 2, and the moisture hardly reaches the electrode pad 13. As a result, it is possible to obtain a highly reliable surface acoustic wave device in which corrosion of the electrode pad 13 is suppressed. In order to sufficiently lengthen the moisture intrusion route to the electrode pad 13, the annular conductor 2 may be formed so as to penetrate the protective cover 9 in the thickness direction. However, in this case, the protective film 7 is interposed between the electrode pad 13 and the lower end of the annular conductor 2 so that the annular conductor 2 does not contact the electrode pad 13.

  Further, by providing such an annular conductor 2 around the through conductor 15, an anchor effect is exhibited, and peeling between the through conductor 15 and the protective cover 6 is less likely to occur, and the mechanical strength of the through conductor 15 is improved. There is also an advantage that can be made.

  In order to obtain the above effect by the annular conductor 2, it is preferable that the interval between the annular conductor 2 and the through conductor 15 be set to about 10 μm to 45 μm.

  In the present embodiment, the annular conductor 2 is formed by plating using Cu, and a plating base layer 16 is formed between the annular conductor 2 and the protective cover 9. By forming the annular conductor 2 by plating in the same manner as the through conductor 15 and the terminal 4, the annular conductor 2, the through conductor 15, and the terminal 4 can be integrally formed, and the production efficiency is good. In addition, these do not necessarily need to be formed integrally, and can be formed by different methods using different materials.

  FIG. 4 shows a modified example of the surface acoustic wave device 1, and is an enlarged cross-sectional view of the through conductor 15 and its peripheral portion. The modification shown in FIG. 4 is different from the surface acoustic wave device 1 according to the embodiment described above in the shape of the annular conductor 2, and the other configuration is the same. Specifically, the lower end of the annular conductor 2 of the surface acoustic wave device 1 according to the embodiment described above has reached the protective film 7, whereas in the modification shown in FIG. Is located in the protective cover 9. As described above, the lower end of the annular conductor 2 is positioned in the protective cover 9, so that the airtightness of the vibration space 6 is suppressed while suppressing the corrosion of the electrode pad 13 as compared with the case where the annular conductor 2 is not provided. Property can be maintained in a good state.

  When the annular conductor 2 is not provided, when the peeling generated between the through conductor 15 and the protective cover 9 reaches the lower end of the through conductor 15, the protective cover 9 starts from that as shown by the white arrow in FIG. 5. There may be a case where peeling occurs also in a portion in contact with the main surface side of the piezoelectric substrate 3 (between the protective cover 9 and the protective film 7 in FIG. 5). When the separation reaches the vibration space 6, the airtightness of the vibration space 6 is not maintained, and the atmosphere of the vibration space 6 is changed. As a result, the characteristics of the surface acoustic wave device are deteriorated.

  On the other hand, in the surface acoustic wave device according to the modification shown in FIG. 4, even if separation occurs between the through conductor 15 and the protective cover 9, the outside air enters the vibration space 6 as much as the annular conductor 2 exists. Compared to the case where the path is long and the annular conductor 2 is not provided, the airtightness of the vibration space 6 can be maintained in a good state for a long time.

  When the lower end of the annular conductor 2 is positioned in the protective cover 9, it is preferable from the viewpoint of production efficiency that the position of the lower end of the annular conductor 2 and the position of the lower surface of the lid portion 21 are at the same height. This is because a groove for forming the annular conductor 2 can be formed at the same time when a hole for forming the through conductor 15 is formed in the lid portion 21. The height position refers to a position when the first main surface 3a of the piezoelectric substrate 3 is used as a reference.

  FIG. 6 is a view showing still another modified example of the surface acoustic wave device 1 according to the embodiment described above, and is an enlarged cross-sectional view of the through conductor 15 and its surroundings. As shown in the figure, the annular conductor 2 may be provided twice. As a result, the moisture infiltration path can be further lengthened. When the annular conductor 2 is provided twice, it is preferable to shorten the outer annular conductor 2. The annular conductor 2 may be triple or more.

  Next, a method for manufacturing the surface acoustic wave device 1 will be described. 7-9 is sectional drawing explaining an example of the manufacturing method of the surface acoustic wave apparatus 1, and has shown the part corresponded in the cross section in the Ia-Ia line | wire of Fig.1 (a). The steps described below are realized in a so-called wafer process. That is, thin film formation, a photolithography method, or the like is performed on the mother substrate that becomes the piezoelectric substrate 3 by being divided, and then dicing is performed so that a large number of surface acoustic wave devices 1 are parallelized. It is formed. However, in FIGS. 7-9, only the part corresponding to one surface acoustic wave apparatus 1 is shown in figure.

  The manufacturing method of the surface acoustic wave device 1 generally includes a step of forming the excitation electrode 5, a step of forming the protective cover 9, and a step of forming the through conductor 15. Specifically, it is as follows.

  First, as shown in FIG. 7A, the connection wiring 11, the electrode pad 13, and the excitation electrode 5 (not shown in the drawing) are formed on the first main surface 3 a of the piezoelectric substrate 3. Specifically, first, a metal layer is formed on the first main surface 3a of the piezoelectric substrate 3 by a thin film forming method such as a sputtering method, a vapor deposition method or a CVD (Chemical Vapor Deposition) method. Next, the metal layer is patterned by a photolithography method using a reduction projection exposure machine (stepper) and an RIE (Reactive Ion Etching) apparatus. Thereby, the connection wiring 11, the electrode pad 13, and the excitation electrode 5 are formed.

  Next, a protective film 7 is formed as shown in FIG. First, a thin film to be the protective film 7 is formed by a thin film forming method such as a CVD method or a vapor deposition method so as to cover the excitation electrode 5, the connection wiring 11, and the electrode pad 13. Next, a part of the thin film is removed by photolithography so that the central portion of the upper surface of the electrode pad 13 is exposed, and the opening 7o is formed. In addition, after forming the protective film 7 or before forming, a connection reinforcing layer is formed on the upper surface of the electrode pad 13 by sequentially stacking chromium, nickel, and gold on the electrode pad 13 by vapor deposition or the like. Also good.

  Next, as shown in FIGS. 7C to 8B, a frame portion 19 is formed. Specifically, first, as shown in FIG. 7C, the first layer 31 that becomes the frame portion 19 is formed on the protective film 7. The first layer 31 is formed, for example, by attaching a film formed of a negative photoresist.

  Next, as shown in FIG. 8A, exposure processing is performed by irradiating the first layer 31 with light L such as ultraviolet rays through a photomask 33. The photomask 33 is configured, for example, by forming a light shielding layer 37 on a transparent substrate 35. The light shielding layer 37 is disposed at a position corresponding to the position where the first layer 31 is to be removed. Specifically, the light shielding layer 37 is disposed at a location corresponding to the formation position of the vibration space 6, the through conductor 15, and the formation position of the annular conductor 2. The exposure may be projection exposure, proximity exposure, or close exposure.

  Thereafter, as shown in FIG. 8B, development processing is performed to leave a portion irradiated with light in the first layer 31 and remove a portion not irradiated with light. Thereby, in the first layer 31, a vibration space hole 39 serving as the vibration space 6, a first through conductor hole 41 in which the through conductor 15 is disposed, and the annular conductor 2 are disposed in the first layer 31. 1 annular hole portion 42 is formed, and the frame portion 19 is completed.

  Next, the lid portion 21 is formed. Specifically, first, as shown in FIG. 8C, the second layer 43 constituting the lid portion 21 is formed on the frame portion 19. The second layer 43 is formed, for example, by attaching a film formed of a negative photoresist. By forming the second layer 43, the opening of the frame portion 19 is closed, and the vibration space 6 is formed. The first layer 31 and the second layer 43 are joined by being heated.

  Next, as shown in FIG. 9A, exposure processing is performed by irradiating the second layer 43 with light L such as ultraviolet rays through a photomask 45. Similar to the photomask 33, the photomask 45 is configured by forming a light shielding layer 49 on the transparent substrate 47. The light shielding layer 49 is disposed at a position corresponding to the position where the second layer 43 should be removed. That is, it is disposed at a location corresponding to the formation position of the through conductor 15 and the annular conductor 2. The exposure may be projection exposure, proximity exposure, or close exposure.

  Thereafter, as shown in FIG. 9B, development processing is performed to leave a portion irradiated with light in the second layer 43 and remove a portion not irradiated with light. As a result, the second through-conductor through-hole 51 is formed on the first through-conductor hole 41, and the first through-conductor through-hole 41 and the second through-conductor through-hole 51 are formed. And are connected. In addition, a second annular hole 52 is formed on the first annular hole 42, and the first annular hole 42 and the second annular hole 52 are connected to each other. In this way, the lid portion 21 is completed. By forming the lid portion 21, the protective cover 9 including the frame portion 19 and the lid portion 21 is completed.

  After forming the protective cover 9, the through conductor 15, the annular conductor 2, and the terminal 4 are formed. Specifically, first, as shown in FIG. 9C, the plating base layer 16 and the plating resist layer 57 are formed.

  The plating base layer 16 is a suitable example formed of a Ti—Cu alloy or the like, for example, by flash plating.

  The plating resist layer 57 is formed on the plating base layer 16. The plating resist layer 57 is formed on the substrate by a technique such as spin coating and then patterned. The patterning is performed such that an opening 57o is formed immediately above the first and second through-conductor hole portions 41 and 51 and the first and second annular hole portions 42 and 52. The opening 57 o is formed such that its inner wall is located outside the outer peripheral edge of the second annular hole 52. Next, the plating base layer 16 exposed from the opening 57o is plated. Thus, the first and second through-conductor hole portions 41 and 51, the first and second annular hole portions 42 and 52, and the peripheral portion of the second annular hole portion 52 are filled with metal, and the through-conductor 15, the annular conductor 2 and the terminal 4 are completed. Finally, unnecessary portions of the plating resist layer 57 and the plating base layer are removed to complete the surface acoustic wave device 1.

  The plating resist layers 57 and 67 described above can be removed by using an organic solvent such as acetone or IPA or an alkaline organic solvent such as dimethyl sulfoxide. Further, when Cu is used as the plating base layer, it can be removed by a mixed solution of ferric chloride, phosphoric acid and hydrogen peroxide, for example. Further, when Ti is used as the plating base layer, it can be removed with, for example, dilute hydrofluoric acid or a mixed solution of ammonia and hydrogen peroxide.

  In the method for manufacturing the surface acoustic wave device 1 described above, if only the second annular hole 52 is formed without forming the first annular hole 42, the position of the lower end of the annular conductor 2 and the lid A surface acoustic wave device in which the position of the lower surface of the portion 21 is at the same height position can be obtained.

  According to the method for manufacturing the surface acoustic wave device described above, the annular conductor 2 can be formed together with the process of forming the through conductor 15. That is, since it is not necessary to separately provide a process for forming the annular conductor 2, the productivity of the surface acoustic wave device 1 is not reduced.

  The present invention is not limited to the above embodiments and modifications, and may be implemented in various aspects.

  In the above-described embodiment, the surface acoustic wave device as an example of the acoustic wave device has been described. However, for example, a piezoelectric thin film resonator may be used.

  Moreover, the manufacturing method of an elastic wave apparatus is not limited to what forms a frame part and a cover part sequentially. For example, a sacrificial layer is formed in a region to be the vibration space 6, a resin to be a frame portion and a lid portion is laminated around the sacrificial layer, and then the sacrificial layer is formed through a hole portion formed in the frame portion or the lid portion. Alternatively, the vibration space 6 may be formed.

1. Surface acoustic wave device (elastic wave device)
2 ... annular conductor 3 ... piezoelectric substrate 4 ... terminal 5 ... excitation electrode 6 ... vibration space 7 ... protective layer 8 ... insulating member 9 ... protective cover 15 ...・ Penetration conductor

Claims (8)

A piezoelectric substrate;
An excitation electrode disposed on a main surface of the piezoelectric substrate;
An electrode pad disposed on the main surface of the piezoelectric substrate and electrically connected to the excitation electrode;
A protective cover comprising a frame portion that surrounds the excitation electrode and covers the electrode pad, and a lid portion that covers the opening of the frame portion;
A through conductor standing on the electrode pad and penetrating the protective cover in the thickness direction;
A terminal disposed on the protective cover and connected to a surface opposite to the electrode pad side of the through conductor, and an outer peripheral edge when viewed from above is located outside the outer peripheral edge of the through conductor;
An annular conductor disposed in the protective cover and connected to the terminal in a state surrounding the through conductor;
An elastic wave device comprising:   The elastic wave device according to claim 1, wherein the protective cover is made of resin. The outer peripheral edge of the electrode pad when viewed in plan is located outside the outer peripheral edge of the through conductor,
The acoustic wave device according to claim 2, wherein a protective film made of silicon oxide or silicon nitride is interposed between the electrode pad and the protective cover. The outer peripheral edge of the electrode pad when viewed in plan is located outside the outer peripheral edge of the annular conductor,
The elastic wave device according to claim 3, wherein the annular conductor penetrates the protective cover in the thickness direction, and a lower end thereof is in contact with the protective film.   The elastic wave device according to claim 1, wherein a lower end of the annular conductor is located in the protective cover.   The elastic wave device according to claim 5, wherein the position of the lower end of the annular conductor and the position of the lower surface of the lid portion are at the same height position. Forming on the main surface of the piezoelectric substrate an excitation electrode and an electrode pad electrically connected to the excitation electrode;
Forming a first layer on the main surface of the piezoelectric substrate so as to cover the excitation electrode and the electrode pad;
A through hole for vibration space is formed on the excitation electrode of the first layer, a first through conductor hole is formed so that the electrode pad is exposed on the electrode pad of the first layer, and the first through hole is formed. Forming a first annular hole around each of the first through-conductor holes in one layer so as to surround the first through-holes;
Forming a second layer on the first layer so as to cover the vibration space hole, the first through-conductor hole, and the first annular hole;
A second through-conductor hole is formed on the first through-conductor hole in the second layer, and a second through-conductor hole is formed on the first annular hole in the second layer. Forming a second annular hole so as to surround each part;
By filling the first and second through-conductor hole portions and the first and second annular hole portions with a conductive material, a through-conductor and an annular conductor surrounding the through-conductor are formed, and the through-hole is formed. Forming a conductor and a terminal connected to the annular conductor;
A method of manufacturing an acoustic wave device including: Forming on the main surface of the piezoelectric substrate an excitation electrode and an electrode pad electrically connected to the excitation electrode;
Forming a first layer on the main surface of the piezoelectric substrate so as to cover the excitation electrode and the electrode pad;
A vibration space hole is formed on the excitation electrode of the first layer, and a first through-conductor hole is formed so as to expose the electrode pad on the electrode pad of the first layer. And a process of
Forming a second layer on the first layer so as to cover the vibration space hole and the first through-conductor hole;
A second through-conductor hole is formed on the first through-conductor hole in the second layer, and the second through-conductor hole is surrounded by the second layer. Forming a second annular hole;
By filling the first and second through-conductor holes and the second annular hole with a conductive material, a through conductor and an annular conductor surrounding the through conductor are formed, and the through conductor and the Forming a terminal connected to the annular conductor;
A method of manufacturing an acoustic wave device including: