JP5921733B2 - Method for manufacturing a surface acoustic wave device - Google Patents

Description

  The present invention relates to a method for manufacturing a surface-mounted surface acoustic wave device mainly used in mobile communication equipment.

  As shown in FIG. 7, the conventional surface acoustic wave device has a plurality of comb-shaped electrodes 2, a plurality of pad electrodes 3, a space between the plurality of comb-shaped electrodes 2, and a comb-shaped electrode 2 and a pad electrode 3. And a side wall 5 is provided on the piezoelectric substrate 1 so as to surround the comb-shaped electrode 2, and a metal is formed on the upper surface of the side wall 5 so as to cover the comb-shaped electrode 2 from the upper surface. By adhering the top plate 6 with the adhesive layer 7, the excitation space 8 of the comb-shaped electrode 2 is secured, and the outer shape is secured by covering it with the sealing resin 9, and the sealing The external electrode 11 provided on the sealing resin 9 and the pad electrode 3 are electrically connected using the columnar electrode 10 penetrating the resin 9.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2008-159844 A

  However, in such a surface acoustic wave device, in order to suppress the contribution of the dielectric constant by the side wall 5, a space is provided between the wiring 4 and the top plate 6 without providing the side wall 5, thereby suppressing the generation of parasitic capacitance. However, in the part where the area of the comb electrode 2 is large, the distance between the comb electrode 2 and the wiring 4 and the top plate 6 is shortened when the top plate 6 is bent by the injection pressure or external force of the sealing resin 9. The parasitic capacitance increases and the electrical characteristics of the surface acoustic wave device deteriorate. Therefore, in the conventional surface acoustic wave device, it is necessary to set the height of the excitation space 8 high, and there is a limit to reducing the height.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a method of manufacturing a surface acoustic wave device that can be reduced in height.

  In order to achieve the above object, the present invention is a step of forming a plurality of comb electrodes, a plurality of pad electrodes, and wirings connecting the comb electrodes and the pad electrodes on the surface of the piezoelectric substrate, A step of providing a non-conductor portion between the wirings divided in the vicinity of the comb-shaped electrode, a step of forming a side wall surrounding the comb-shaped electrode, a step of forming a columnar portion in the non-conductive portion, and the side wall Forming a top plate on the upper surface of the substrate and the upper surface of the columnar portion, and the columnar portion is disposed on the piezoelectric substrate side on the non-conductor portion so as to be in non-contact with the sidewall on the inner side of the sidewall. To the top plate side.

  Further, the present invention is a step of forming a plurality of comb-shaped electrodes, a plurality of pad electrodes, and a wiring connecting the comb-shaped electrodes and the pad electrodes on the surface of the piezoelectric substrate, and is divided near the comb-shaped electrodes. A step of providing a non-conductor portion between the formed wirings, a step of forming a side wall surrounding the comb-shaped electrode, a step of forming a columnar portion in the non-conductor portion, an upper surface of the side surface and the columnar portion Forming a top plate on the upper surface, and the columnar part has a configuration that has a tapered shape that expands toward the piezoelectric substrate.

  By having the above configuration, the method of manufacturing the surface acoustic wave device of the present invention can secure the distance between the piezoelectric substrate and the top plate even when an external force is applied, and between the wiring and the top plate. An increase in parasitic capacitance can be suppressed, and as a result, it is possible to suppress the deterioration of electrical characteristics even when the surface acoustic wave device is reduced in height.

Sectional drawing of the surface acoustic wave device in Embodiment 1 which concerns on this invention (A), (b) Pattern arrangement of the surface acoustic wave device Sectional drawing of the surface acoustic wave device in Embodiment 2 which concerns on this invention (A), (b) Pattern arrangement of the surface acoustic wave device (A)-(f) Manufacturing process figure which shows the manufacturing method of the same surface acoustic wave device Sectional drawing of the surface acoustic wave device in Embodiment 3 which concerns on this invention Sectional view of a conventional surface acoustic wave device

(Embodiment 1)
Hereinafter, the surface acoustic wave device according to the present invention will be described using the first embodiment. In addition, the same code | symbol is attached | subjected and demonstrated about the structure similar to the conventional surface acoustic wave device mentioned above.

  FIG. 1 is a cross-sectional view of a surface acoustic wave duplexer that is an example of a surface acoustic wave device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the basic structure is the same as that of a conventional surface acoustic wave device, on the surface of a piezoelectric substrate 1 between a plurality of comb electrodes 2, a plurality of pad electrodes 3, and the plurality of comb electrodes 2. In addition, a wiring 4 for connecting the comb electrode 2 and the pad electrode 3 is provided, and a side wall 5 is provided on the piezoelectric substrate 1 so as to surround the comb electrode 2 and the comb electrode 2 is covered from above. A metal top plate 6 is bonded to the upper surface of the side wall 5 through an adhesive layer 7 to secure an excitation space 8 for the comb-shaped electrode 2 and further covered with a sealing resin 9 to form an outer shape. And the external electrode 11 provided on the sealing resin 9 and the pad electrode 3 are electrically connected using the columnar electrode 10 penetrating the sealing resin 9. This is an example of a surface acoustic wave device. Those constituting the surface acoustic wave duplexer.

  Here, the piezoelectric substrate 1 is made of rotating Y-cut X-propagating lithium tantalate having a plate thickness of about 100 to 350 μm, and the comb electrode 2, pad electrode 3 and wiring 4 are mainly made of aluminum having a thickness of about 1 μm. The side wall 5 is composed of a polyimide resin that is patterned by photolithography and cured by heat, and the top plate 6 is a copper foil 6a of about 1 to 10 μm. Is provided with a plating layer 6b having a thickness of about 20 to 40 μm, which ensures the shape of the excitation space with respect to the external force and the heat dissipation with respect to the heat generation of the comb-shaped electrode 2. Which is connected to the ground.

  The adhesive layer 7 is made of an epoxy resin having a thickness of about 1 to 10 μm, the sealing resin 9 is made of an epoxy resin containing silicon oxide as a filler, and the columnar electrode 10 Is formed by plating with copper as a main component, and the external terminal 11 is made of a metal conductor such as copper, and functions as an antenna terminal, a transmission terminal, a reception terminal, and a ground terminal in a surface acoustic wave duplexer. is there.

  In the first embodiment according to the present invention, the non-conductive columnar portion 12 that reaches the top plate 6 on the wiring 4 that connects the plurality of comb electrodes 2 and between the comb electrodes 2 and the pad electrodes 3. Is provided. As described above, in Embodiment 1 according to the present invention, the columnar portion 12 having substantially the same height as the side wall 5 is provided between the wiring 4 and the top plate 6 near the comb-shaped electrode 2. Can be suppressed, and a distance between the wiring 4 and the top plate 6 can be ensured. As a result, even if the surface acoustic wave device is lowered, the distance between the wiring 4 and the top plate 6 can be reduced. Since the generation of parasitic capacitance due to capacitive coupling of the surface acoustic wave device can be suppressed, the surface acoustic wave device can be reduced in height.

  Next, a pattern arrangement of a surface acoustic wave duplexer which is an example of the surface acoustic wave device according to the first embodiment of the present invention will be described with reference to FIGS.

  2A is an electrode pattern arrangement diagram on the piezoelectric substrate of the surface acoustic wave device according to the first embodiment of the present invention, and FIG. 2B is a side wall and columnar shape on the piezoelectric substrate of the surface acoustic wave device. FIG.

  2A and 2B, 3a is a pad electrode connected to the antenna terminal, 3b is a pad electrode connected to the transmission terminal, 3c is a pad electrode connected to the reception terminal, and 3d is connected to the ground terminal. In the pad electrode, a circuit on the pad electrode 3b side from the pad electrode 3a is a transmitting circuit, and a circuit on the pad electrode 3c side from the pad electrode 3a is a receiving circuit. The wiring 4a on the series line from the pad electrode 3a to the pad electrode 3b and on the series line from the pad electrode 3a to the pad electrode 3c constitutes a signal line, and the comb electrodes on these series lines 2 is a series resonator. Further, the comb electrode 2 on the parallel line branched from the series line and connected to the pad electrode 3d constitutes a parallel resonator, and the wiring 4b connecting the comb electrode 2 and the pad electrode 3d on the parallel line has a ground line. It is what constitutes. Further, the side wall 5 made of polyimide resin is provided on the piezoelectric substrate 1 so as to surround the comb-shaped electrode 2.

  In the first embodiment according to the present invention, the non-conductive property which is located on the signal line wiring 4 a and reaches the top plate 6 among the wirings 4 connected to the comb-shaped electrode 2 on the piezoelectric substrate 1. The columnar part 12 is provided.

  Here, as shown in FIGS. 2A and 2B, a space is provided on the signal line wiring 4a near the comb electrode 2 without providing the side wall 5, and a side wall is formed on the wiring 4a. It is preferable to provide a plurality of isolated columnar portions 12 independent of 5. This is because there is a potential difference between the wiring 4a of the signal line and the top plate 6 connected to the ground line, and the generation of parasitic capacitance is suppressed by minimizing the influence of the dielectric material between them. This is because it can. On the other hand, the wiring 4b of the ground line has the same potential as the top plate 6 and does not generate a parasitic capacitance, and therefore may be covered with the side wall 5.

  In the surface acoustic wave device according to the first embodiment of the present invention described above, the surface acoustic wave duplexer has been described as an example, but the same effect can be obtained when applied to other surface acoustic wave devices. It is what you have.

(Embodiment 2)
Hereinafter, the surface acoustic wave device according to the present invention will be described using the second embodiment.

  In the second embodiment, the same components as those in the first embodiment according to the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The second embodiment is different from the first embodiment according to the present invention described above in that a non-conductor portion is provided in the wiring 4 under the columnar portion 12.

  FIG. 3 is a cross-sectional view of a surface acoustic wave duplexer which is an example of a surface acoustic wave device according to Embodiment 2 of the present invention.

  As shown in FIG. 3, in Embodiment 2 according to the present invention, a non-conductor portion 13 is provided in the wiring 4 that connects between the plurality of comb electrodes 2 and between the comb electrodes 2 and the pad electrodes 3. The non-conductive columnar portion 12 is provided on the non-conductive portion 13 and extends from the piezoelectric substrate 1 to the top plate 6. As described above, the non-conductor portion 13 is provided in the wiring 4 without providing the columnar portion 12 on the conductor of the wiring 4, and the columnar portion 12 is provided on the non-conductor portion 13. As a result, the influence of the dielectric constant of the columnar portion 12 on the capacitive coupling between the wiring 4 and the top plate 6 can be minimized, so that the surface acoustic wave device can be further reduced in height.

  Next, a pattern arrangement of a surface acoustic wave duplexer that is an example of the surface acoustic wave device according to the second embodiment of the present invention will be described with reference to FIGS.

  FIG. 4A is an electrode pattern arrangement diagram on the piezoelectric substrate of the surface acoustic wave device according to the second embodiment of the present invention, and FIG. 4B is a side wall and columnar shape on the piezoelectric substrate of the surface acoustic wave device. FIG.

  As shown in FIGS. 4A and 4B, in the second embodiment according to the present invention, among the wirings connected to the comb-shaped electrode 2, the non-conductor portion 13 is provided in the signal line wiring 4a. In addition, a non-conductive columnar portion 12 is provided on the non-conductor portion 13 and extends from the piezoelectric substrate 1 to the top plate 6.

  Here, as shown in FIGS. 4A and 4B, a space is provided on the wiring 4a near the comb-shaped electrode 2 without providing the side wall 5, and a non-conductor portion is formed in the wiring 4a. 13 and further provided with the columnar portion 12 positioned on the non-conductor portion 13, and the effect of such a configuration is remarkable in the wiring 4a of the signal line. This is because there is a potential difference between the wiring 4a of the signal line and the top plate 6 connected to the ground line, and the generation of parasitic capacitance can be suppressed by not having a dielectric substance between them. . On the other hand, the wiring 4b of the ground line has the same potential as the top plate 6 and does not generate a parasitic capacitance, and therefore may be covered with the side wall 5.

  Note that in the signal line in the transmission circuit, a large amount of electric power is applied to the comb electrode 2 on the side close to the pad electrode 3b connected to the transmission terminal. It is preferable to divide and provide the columnar part 12 on each non-conductor part 13, and if the wiring 4a is divided in this way, the current flowing into and out of the comb electrode 2 is locally concentrated. It is possible to equalize without increasing, and by suppressing the increase of the resistance component, it is possible to suppress the increase in insertion loss and equalize the heat dissipation.

  Next, a method for manufacturing the surface acoustic wave device according to the second embodiment of the present invention will be described with reference to FIGS.

  First, as shown in FIG. 5A, a plurality of comb-shaped electrodes 2, a plurality of pad electrodes 3, and the above-described electrodes are formed on the surface of a piezoelectric substrate 1 made of lithium tantalate or lithium niobate using a photolithography technique. The wiring 4 that connects between the plurality of comb-shaped electrodes 2 and between the comb-shaped electrode 2 and the pad electrode 3 is formed of an alloy mainly composed of aluminum. At this time, the wiring 4 is divided near the comb-shaped electrode 2, and the non-conductor portion 13 is provided between the divided wirings 4.

  Next, as shown in FIG. 5B, a photosensitive polyimide resin is applied to the piezoelectric substrate 1, and the sidewall 5 surrounding the comb-shaped electrode 2 is formed by performing exposure and development. The height of the side wall 5 is about 5 to 15 μm. In the step of forming the side wall 5, the columnar portion 12 made of a photosensitive polyimide resin is formed on the non-conductive portion 13 provided between the wirings 4 simultaneously with the formation of the side wall 5. By this simultaneous formation, the height of the columnar portion 12 becomes substantially the same as the height of the side wall 5.

  Next, as shown in FIG.5 (c), the copper foil 6a is bonded together on the upper surface of the side wall 5 and the upper surface of the columnar part 12 via the adhesive layer 7, and the copper foil 6a is predetermined | prescribed from it using a resist. Etch to the pattern. Then, a sputtered film made of metal is formed thereon.

  Next, as shown in FIG. 5 (d), a resist pattern 14a is formed on the piezoelectric substrate 1 with openings for forming the plating layer 6b and the columnar electrode 10, and the plating layer 6b and the plating layer 6b are formed by electrolytic plating. The columnar electrode 10 is formed.

  Next, as shown in FIG. 5E, a resist pattern 14b having an opening at a portion where the columnar electrode 10 is to be formed is formed, and the columnar electrode 10 is formed further up by electrolytic plating.

  Next, as shown in FIG. 5 (f), after removing the resist patterns 14a and 14b, the entire surface of the piezoelectric substrate 1 is covered with the sealing resin 9, and this surface is polished and flattened. The upper surface of the columnar electrode 10 is exposed, and the external terminal 11 electrically connected to the upper surface of the columnar electrode 10 is formed. Thereafter, the piezoelectric substrate 1 and the sealing resin 9 are simultaneously cut by dicing to obtain individual surface acoustic wave devices from the aggregate substrate.

(Embodiment 3)
Hereinafter, the surface acoustic wave device according to the present invention will be described using the third embodiment.

  In the third embodiment, the same reference numerals are given to the components common to the above-described second embodiment according to the present invention, and the description thereof is omitted.

  The third embodiment is different from the second embodiment according to the present invention described above in that the lower outer peripheral end of the columnar portion 12 is formed so as to cover the wiring 4 around the non-conductor portion 13. is there.

  FIG. 6 is a cross-sectional view of a surface acoustic wave duplexer which is an example of a surface acoustic wave device according to Embodiment 3 of the present invention.

  As shown in FIG. 6, in the third embodiment according to the present invention, the lower outer peripheral end of the columnar part 12 is formed so as to cover the wiring 4 around the non-conductor part 13, and this configuration is adopted. As a result, the strength at the lower part of the columnar part 12 with respect to external force can be secured more firmly, and the heat generated from the comb-shaped electrode 2 can be effectively transmitted to the top plate 6 through the columnar part 12. Good heat dissipation characteristics can be obtained. This improvement in heat dissipation characteristics can improve the power handling characteristics, and this improvement in power handling characteristics can reduce the number of stages of multi-stage comb electrodes, etc. As a result, further miniaturization becomes possible.

  Further, the wall surface of the columnar portion 12 may be tapered so as to spread from the top to the bottom as shown in FIG. 6. With this configuration, the wiring 4, the top plate 6, Since the contribution of the dielectric constant of the columnar portion 12 to the capacitive coupling between the two can be further suppressed, the parasitic capacitance can be more effectively suppressed.

  The method of manufacturing the surface acoustic wave device according to the present invention can achieve a low profile, and is mainly a surface mounted surface acoustic wave filter or surface acoustic wave duplexer used for mobile communication devices. This is useful in devices and the like.

DESCRIPTION OF SYMBOLS 1 Piezoelectric substrate 2 Comb electrode 3 Pad electrode 4 Wiring 5 Side wall 6 Top plate 8 Excitation space 9 Sealing resin 11 External terminal 12 Columnar part 13 Non-conductor part

Claims (15)

A method of manufacturing a surface acoustic wave device, comprising:
Forming a plurality of comb electrodes, a plurality of pad electrodes, and wirings connecting the comb electrodes and the pad electrodes on the surface of the piezoelectric substrate, wherein the wirings divided in the vicinity of the comb electrodes are A step in which a non-conductor portion is provided,
Forming sidewalls surrounding the comb electrodes;
Forming a columnar portion in the non-conductor portion;
Forming a top plate on the upper surface of the side wall and the upper surface of the columnar part,
The columnar part is provided on the non-conductor part from the piezoelectric substrate side to the top plate side so as not to be in contact with the side wall inside the side wall. A method of manufacturing a surface acoustic wave device, comprising:
Forming a plurality of comb electrodes, a plurality of pad electrodes, and wirings connecting the comb electrodes and the pad electrodes on the surface of the piezoelectric substrate, wherein the wirings divided in the vicinity of the comb electrodes are A step of providing a non-conductor portion between,
Forming sidewalls surrounding the comb electrodes;
Forming a columnar portion in the non-conductor portion;
Forming a top plate on the upper surface of the side wall and the upper surface of the columnar part,
The columnar portion has a taper shape that expands toward the piezoelectric substrate.   The method according to claim 1, wherein a lower outer peripheral end of the columnar portion is provided so as to cover the wiring.   The method according to any one of claims 1 to 3, wherein the comb-shaped electrode and the wiring form a transmission circuit or a reception circuit.   The method according to claim 4, wherein a plurality of the non-conductor portions are provided in one of the wirings connecting between the comb electrodes on a signal line of the transmission circuit or the reception circuit.   The method according to claim 5, wherein the columnar portion is provided in each of the plurality of non-conductor portions.   The method according to claim 1, wherein the surface acoustic wave device is a surface acoustic wave duplexer.   The method according to any one of claims 1 to 7, wherein a height of the columnar portion is the same as a height of the side wall.   The method according to any one of claims 1 to 8, wherein the step of forming the top plate includes a step of bonding a metal foil to the upper surface of the side wall and the upper surface of the columnar part via an adhesive layer.   The method of claim 9, further comprising forming a plating layer on an upper surface of the metal foil.   The method according to claim 10, wherein a columnar electrode extending upward from the pad electrode is formed at the same time as the plating layer is formed.   The method of claim 11, further comprising extending the columnar electrode upward by plating.   The method according to claim 12, further comprising a step of covering the top plate and the piezoelectric substrate with a sealing resin.   The method according to claim 13, further comprising exposing an upper surface of the columnar electrode from a surface of the sealing resin.   The method according to any one of claims 1 to 14, wherein the step of forming the side wall and the step of forming the columnar part are performed simultaneously.

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