JP2012239236A - Elastic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hollow structure which is not deformed by a pressure caused during modularization without deteriorating the yield.SOLUTION: An elastic wave device includes: a first sealing part 26 formed by a photosensitive resin and provided so as to have a cavity 16 on an elastic wave element 12 provided on a piezoelectric substrate 10; a second sealing part 28 formed by a photosensitive resin and provided on the first sealing part; an external connection part 22 provided on the second sealing part; and columnar electrodes 20, which penetrate through the first sealing part and the second sealing part, directly contact with the first sealing part and the second sealing part, and electrically connect the elastic wave element with the external connection part. The first sealing part 26 has: a third sealing part 30 provided so as to have a step making the width of the first sealing part on the substrate side wider than the width of the first sealing part on the opposite side and enclose a functional part of the elastic wave element; and a fourth sealing part 32 provided on the third sealing part 32 so as to form the cavity on the functional part. The width of the third sealing part is wider than that of the fourth sealing part, and the second sealing part includes a step part of the first sealing part and directly contacts with the first sealing part.

Description

  The present invention relates to an acoustic wave device, and more particularly, to an acoustic wave device including a sealing portion having a hollow portion above an acoustic wave element.

  As one of the acoustic wave devices using an acoustic wave, a comb-shaped electrode made of IDT (Interdigital Transducer) formed on the surface of a piezoelectric substrate is provided, and an elastic wave excited by applying electric power to the comb-shaped electrode is used. Surface acoustic wave devices are well known. This surface acoustic wave device is widely used in various circuits that process radio signals in a frequency band of 45 MHz to 2 GHz, for example, a transmission band-pass filter, a reception band-pass filter, an antenna duplexer, and the like.

  Recently, an elastic wave device using a piezoelectric thin film resonator (FBAR: Film Bulk Acoustic Resonator) in which a pair of electrodes are formed on the front and back sides of the piezoelectric thin film and the thickness vibration is used has been developed. An acoustic wave device using a piezoelectric thin film resonator has particularly good characteristics in a high frequency band, and is used in a frequency band of 1 GHz to 10 GHz, for example.

  In recent years, there has been remarkable progress in the field of mobile communication in particular, and signal processing equipment used in these fields has been downsized, and electronic components of acoustic wave devices have also been required to be downsized. At the same time, in order to maintain the characteristics of the acoustic wave element, a cavity is formed on the functional part of the acoustic wave element (surface acoustic wave element: electrode finger of IDT, piezoelectric thin film resonator element: region where upper and lower electrodes sandwich the piezoelectric thin film) It is necessary to provide a part.

  In order to satisfy such a requirement, a method of forming a structure (so-called hollow structure) in which a sealing portion having a hollow portion is provided on a functional portion of an acoustic wave element has been proposed. For example, in Patent Document 1, a melting structure is formed by forming a resin for dissolution in a region to be a cavity on an acoustic wave element, forming an upper plate on the resin for dissolution, and then removing the resin for dissolution. A method (conventional example 1) is disclosed. In Patent Document 2, a frame structure surrounding the electrical structure element is formed, an auxiliary film is pasted on the frame structure so that the electrical structure element is hollow, and a resin layer is formed thereon. A method (conventional example 2) for forming a hollow structure by removing the frame structure other than the roof portion is disclosed. In Patent Document 3, a resin film is pasted on a piezoelectric substrate on which an acoustic wave element is formed, a resin film above a functional part of the substrate on which a plurality of acoustic wave elements are provided is opened, and a circuit board is adhered to the resin film. A method of forming a hollow structure (conventional example 3) is disclosed. In Patent Document 4, a photosensitive resin is formed on a substrate provided with a plurality of acoustic wave elements, a photosensitive resin on a functional part of the acoustic wave element is opened, and a substrate of a wiring board assembly is mounted thereon. A method of forming a hollow structure by dividing by dicing (conventional example 4) is disclosed.

Japanese Patent No. 3291406 Special table 2003-523082 gazette Japanese Patent No. 3196693 Japanese Patent No. 3225906

  The elastic wave devices formed by the methods of Conventional Examples 1 to 4 cannot withstand the pressure applied during modularization, and the ceiling portion of the hollow structure is recessed. As a method of solving this problem, a method of increasing the thickness of the ceiling portion of the hollow structure is conceivable. However, when resin is further formed on the ceiling part of the hollow structure formed using resin, the problem that a yield falls newly arises.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an acoustic wave device having a hollow structure that is not deformed by pressure during modularization without reducing yield.

  The present invention includes an acoustic wave element provided on a substrate, a first sealing portion made of a photosensitive resin provided on the substrate so as to have a cavity on the acoustic wave element, and the first seal. A second sealing portion made of a photosensitive resin provided on the stop portion, an external connection portion provided on the second sealing portion, and penetrating the first sealing portion and the second sealing portion. And a columnar electrode that is in direct contact with the first sealing portion and the second sealing portion and electrically connects the acoustic wave element and the external connection portion, and the first sealing portion. Is a third sealing portion provided on the substrate so as to surround the functional portion of the acoustic wave device so that the substrate side has a step so that the width on the substrate side is wider than the width on the opposite side of the substrate. And a fourth sealing portion provided on the third sealing portion so as to form a cavity on the functional portion, and the third sealing portion The width is wider than the width of the fourth sealing portion, and the second sealing portion is in direct contact with the first sealing portion including the step portion of the first sealing portion. It is an elastic wave device. According to the present invention, it is possible to prevent peeling of the second sealing portion, and thus it is possible to provide an acoustic wave device having a hollow structure that is not deformed by pressure during modularization without reducing yield. .

In the above configuration, the shape of the step may be a staircase shape or a round shape.

  In the above configuration, the first sealing portion includes a third sealing portion provided on the substrate so as to surround a functional portion of the acoustic wave element, and a cavity portion formed on the functional portion. And a fourth sealing portion provided on the third sealing portion, and the width of the third sealing portion may be wider than the width of the fourth sealing portion. According to this structure, the 1st sealing part which has a level | step difference can be formed easily.

  The said structure WHEREIN: The angle which the said 4th sealing part side makes with the surface of the said 3rd sealing part and the side surface of the said 4th sealing part can be set as the structure which is an acute angle. Moreover, the said structure WHEREIN: The angle which the said 4th sealing part side makes with the surface of the said 3rd sealing part and the side surface of the said 4th sealing part can be set as the structure which is an obtuse angle.

  The said structure WHEREIN: The angle which the said 3rd sealing part side makes with the surface of the said board | substrate and the side surface of the said 3rd sealing part can be set as the structure which is an acute angle. According to this configuration, since the contact area between the second sealing portion and the substrate is increased, the adhesion between the second sealing portion and the substrate can be improved.

  The said structure WHEREIN: The said 3rd sealing part can be set as the structure whose contact surface with the said 4th sealing part is planar.

  The said structure WHEREIN: The said 3rd sealing part can be set as the structure which has an unevenness | corrugation in a contact surface with the said 4th sealing part. According to this structure, since the contact area of a 3rd sealing part and a 4th sealing part becomes large, the adhesive force of a 3rd sealing part and a 4th sealing part can be improved.

  The said structure WHEREIN: A said 1st sealing part and a said 2nd sealing part can be set as the structure which consists of photosensitive resin. According to this configuration, the first sealing portion and the second sealing portion can be easily formed. In the above configuration, the end surface of the second sealing portion is positioned on the substrate and on the inner side of the end surface of the substrate.

  According to the present invention, by providing the second sealing portion on the first sealing portion having a step, it is possible to prevent the second sealing portion from being peeled off, so that the module can be formed without reducing the yield. It is possible to provide an acoustic wave device having a hollow structure that is not deformed by the pressure at the time.

1A is a top view of an acoustic wave device according to Comparative Example 1, FIG. 1B is a cross-sectional view taken along the line A-A in FIG. 1A, and FIG. It is sectional drawing between BB of 1 (a). FIG. 2A to FIG. 2F are cross-sectional views illustrating manufacturing steps of the acoustic wave device according to Comparative Example 1. FIG. 3 is a cross-sectional view of an acoustic wave device according to Comparative Example 2. FIG. 4 is a cross-sectional view of an acoustic wave device according to Comparative Example 3. FIG. 5 is a diagram (part 1) for explaining a problem due to the influence of warpage of the wafer. FIG. 6 is a diagram (part 2) for explaining a problem due to the influence of wafer warpage. FIG. 7A is a top view of the acoustic wave device according to the first embodiment, FIG. 7B is a cross-sectional view taken along the line A-A in FIG. 7A, and FIG. It is sectional drawing between BB of 7 (a). FIG. 8A to FIG. 8F are cross-sectional views (part 1) showing the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 9A to FIG. 9F are cross-sectional views (part 2) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 10A to FIG. 10F are cross-sectional views (part 3) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 11A to FIG. 11F are cross-sectional views (part 4) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 12 is a diagram for explaining the round shape. FIG. 13 is a view for explaining a case where the contact surfaces of the third sealing portion and the fourth sealing portion have an uneven shape.

  First, an experiment conducted by the inventor to clarify the problems of the conventional examples 1 to 4 will be described. FIG. 1A to FIG. 1C show an acoustic wave device (Comparative Example 1) in which a hollow structure is formed using a photosensitive resin. 1A is a top view, FIG. 1B is a cross-sectional view taken along the line A-A in FIG. 1A, and FIG. 1C is a cross-sectional view taken along the line BB in FIG. is there. 1A shows the acoustic wave element 12, the wiring 14, and the cavity 16 through the first sealing portion 26. The acoustic wave element 12 and the wiring 14 are indicated by a solid line, and the cavity 16 is indicated by a broken line. ing. Referring to FIGS. 1A and 1B, an acoustic wave element 12 made of a metal film, such as an IDT and a reflector, is provided on the surface of the piezoelectric substrate 10, and an acoustic wave is further formed on the piezoelectric substrate 10. A first sealing portion 26 having a hollow portion 16 is provided on the functional portion of the element 12. The first sealing portion 26 forms the third sealing portion 30 provided on the piezoelectric substrate 10 so as to surround the functional portion of the acoustic wave element 12 and the cavity portion 16 on the functional portion of the acoustic wave element 12. And a fourth sealing portion 32 provided on the third sealing portion 30. The first sealing portion 26 has a height of 60 μm, and the cavity portion 16 has a height of 30 μm.

  With reference to FIG. 1A and FIG. 1C, a wiring 14 and an electrode pad 24 are formed on the surface of the piezoelectric substrate 10, and a first sealing portion 26 is provided on the wiring 14. The through electrode 20 penetrating the first sealing portion 26 is provided on the electrode pad 24, and the acoustic wave element 12 and the through electrode 20 are connected by the wiring 14 and the electrode pad 24 on the wiring 14. A solder ball 22 is provided on the through electrode 20. Accordingly, the through electrode 20 and the solder ball 22 function as a terminal portion that electrically connects the acoustic wave element 12 to the outside when the acoustic wave device is surface-mounted. As described above, the acoustic wave element 12 is sealed by the first sealing portion 26 having a hollow structure, and is connected to the solder ball 22 via the wiring 14 and the through electrode 20.

  With reference to FIG. 2A to FIG. 2F, a process of forming the first sealing portion 26 of the acoustic wave device according to Comparative Example 1 will be described. 2 (a) to 2 (c) are cross-sectional views corresponding to the area between AA in FIG. 1 (a), and FIGS. 2 (d) to 2 (f) are diagrams of FIG. 1 (a). It is sectional drawing of the location corresponded between BB. 2 (a) and 2 (d), a negative photosensitive epoxy resin is formed to a thickness of 30 μm on the piezoelectric substrate 10 on which the acoustic wave element 12, the wiring 14 and the electrode pad 24 are formed. It is applied using a spin coating method. Then dry. By performing exposure and development, the negative photosensitive epoxy resin on the acoustic wave element 12 and the electrode pad 24 is removed. As a result, an opening 36 is formed on the functional part of the acoustic wave element 12 and an opening 42 is formed on the electrode pad 24, thereby forming the third sealing part 30 so as to surround the functional part of the acoustic wave element 12. Is done. Further, the third sealing portion 30 is cured by heating in a nitrogen atmosphere at about 200 ° C. for about 1 hour.

  With reference to FIG. 2B and FIG. 2E, a film-like negative photosensitive epoxy resin having a thickness of 30 μm is pasted using a laminating method so as to hold the openings 36 and 42. As a result, the functional portion of the acoustic wave element 12 is covered, and the opening 36 becomes the cavity 16 and the opening 42 becomes the cavity 44. Referring to FIGS. 2C and 2F, the fourth seal is formed on the third sealing portion 30 so that the cavity portion 16 is formed on the functional portion of the acoustic wave element 12 by exposure and development. A stop 32 is formed. An opening 42 in which the through electrode 20 is to be formed is also formed on the electrode pad 24. Further, the fourth sealing portion 32 is cured by heating in a nitrogen atmosphere at about 200 ° C. for about 1 hour. Thereby, formation of the 1st sealing part 26 of the elastic wave device concerning the comparative example 1 is completed.

  When the elastic wave device according to the comparative example 1 is mounted on the module substrate and the resin for surface protection is transfer molded, the ceiling portion of the hollow structure is recessed by pressure, and the first sealing portion 26 is the elastic wave element 12. It was found that it touches the functional part.

  Next, an acoustic wave device (Comparative Example 2) in which the width of the third sealing portion 30 was narrow as shown in FIG. 3 was produced. FIG. 3 is a cross-sectional view of a portion corresponding to AA in FIG. Referring to FIG. 3, in Comparative Example 2, the width t1 of the third sealing portion 30 is 30 μm. Other configurations are the same as those of the first comparative example and are shown in FIG. 1A to FIG.

  As shown in FIG. 3, the elastic wave device according to Comparative Example 2 has a contact area between the third sealing portion 30 and the fourth sealing portion 32 because the width t1 of the third sealing portion 30 is as thin as 30 μm. small. For this reason, the close contact between the third sealing portion 30 and the fourth sealing portion 32 becomes insufficient, and the developing solution becomes the third by the development during the formation process of the fourth sealing portion 32 shown in FIG. It will enter into the hollow structure from the interface between the sealing part 30 and the fourth sealing part 32. As a result, it has been found that the functional part (electrode finger made of IDT) of the acoustic wave element 12 is contaminated by the developer, resulting in poor characteristics.

  From Comparative Example 2, the contact area between the third sealing portion 30 and the fourth sealing portion 32 needs to be increased. FIG. 4 is a cross-sectional view of an acoustic wave device according to Comparative Example 3 in which the contact area between the third sealing portion 30 and the fourth sealing portion 32 is increased. Referring to FIG. 4, in Comparative Example 3, the width t1 of the third sealing portion 30 is 80 μm. The other configuration is the same as that of Comparative Example 1 and is shown in FIGS.

  In Comparative Example 3, the area of the third sealing portion 30 in the wafer of the piezoelectric substrate 10 is larger than that in Comparative Example 2. For this reason, the compression force produced in the 3rd sealing part 30 by the heating in the formation process of the 3rd sealing part 30 as shown to FIG. 2A and FIG. Larger than As a result, the warpage of the wafer in Comparative Example 3 is larger than that in Comparative Example 2. When the piezoelectric substrate 10 is a 4-inch wafer, the amount of warping is 2.5 mm at the maximum. When the wafer in which the warpage has occurred is exposed as the formation process of the fourth sealing portion 32 as shown in FIG. 2C, ultraviolet rays (UV light) are emitted from the wafer outer peripheral portion where the influence of the warpage is large. As shown in FIG. 5, the pattern of the fourth sealing portion 32 is shifted from the pattern of the third sealing portion 30. Further, since the influence of the warpage increases as it goes to the outer peripheral portion of the wafer, the shift of the pattern of the fourth sealing portion 32 inevitably increases as it goes to the outer peripheral portion of the wafer.

  As shown in FIG. 5, in the acoustic wave device in which the pattern of the fourth sealing portion 32 is shifted from the pattern of the third sealing portion 30, the third sealing portion 30 and the fourth sealing portion 32 A region A having a small contact area is generated. For this reason, as described in Comparative Example 2, in the development in the process of forming the fourth sealing portion 32, the developer enters the hollow structure and the functional portion of the acoustic wave element 12 (electrode finger made of IDT) is contaminated. As a result, a characteristic defect occurs. In the case of a 4-inch wafer, the region where the developer does not enter the hollow structure, that is, the region having good characteristics is a region 90 mm from the center of the wafer.

  Further, as shown in FIG. 5, since the pattern of the fourth sealing portion 32 is shifted from the pattern of the third sealing portion 30, a region B in which the fourth sealing portion 32 becomes a wrinkle occurs. In this state, the second sealing portion 28 is formed on the first sealing portion 26 for the purpose of strengthening the first sealing portion 26 so that the ceiling portion of the hollow structure is not dented by the pressure at the time of modularization. Then, the region B that is a wrinkle is not irradiated with ultraviolet rays (UV light) during exposure, and as shown in FIG. 6, a cavity 16a is generated by development. Due to the hollow portion 16a, the contact area between the second sealing portion 28 and the piezoelectric substrate 10 is reduced, and the adhesion between the second sealing portion 28 and the piezoelectric substrate 10 is reduced. For this reason, the phenomenon which the 2nd sealing part 28 peels generate | occur | produces. In the case of a 4-inch wafer, the area where the second sealing portion 28 does not peel, that is, the non-defective area is an area 70 mm from the center of the wafer. As described above, the provision of the second sealing portion 28 on the first sealing portion 26 causes a problem that the yield decreases.

  Hereinafter, examples for solving the above-described problems will be described.

  FIG. 7A is a top view of the acoustic wave device according to the first embodiment. 7B is a cross-sectional view taken along the line AA in FIG. 7A, and FIG. 7C is a cross-sectional view taken along the line BB in FIG. 7A. In FIG. 7A, the acoustic wave element 12, the wiring 14, and the cavity 16 are illustrated through the first sealing portion 26 and the second sealing portion 28, and the acoustic wave element 12 and the wiring 14 are solid lines. The cavity 16 and the first sealing portion 26 are indicated by broken lines.

  Referring to FIGS. 7A and 7B, an acoustic wave element 12 including an IDT, a reflector, and the like formed on a surface of the piezoelectric substrate 10 is provided. On the piezoelectric substrate 10, a first sealing portion 26 having a hollow portion 16 on a functional portion of the acoustic wave element 12 is provided. The first sealing portion 26 has the third sealing portion 30 provided on the piezoelectric substrate 10 so as to surround the functional portion of the acoustic wave element 12, and the cavity portion 16 on the functional portion of the acoustic wave element 12. And a fourth sealing portion 32 provided on the third sealing portion 30. The width of the third sealing part 30 is wider than the width of the fourth sealing part 32, whereby the third sealing part 30 and the fourth sealing part 32 have a step. That is, the side surface P1 of the third sealing portion 30 protrudes from the side surface P2 of the fourth sealing portion 32, and the third sealing portion 30 and the fourth sealing portion 32 have a stepped step. Yes. Therefore, the first sealing portion 26 has a step such that the width t2 on the piezoelectric substrate 10 side is wider than the width t3 on the opposite side of the piezoelectric substrate 10. An angle θ1 formed between the surface of the piezoelectric substrate 10 and the side surface of the third sealing portion 30 on the third sealing portion 30 side is a right angle. An angle θ2 formed between the surface of the third sealing portion 30 and the side surface of the fourth sealing portion 32 on the fourth sealing portion 32 side is also a right angle. The third sealing part 30 has a flat contact surface with the fourth sealing part 32. A second sealing portion 28 is provided on the first sealing portion 26. In addition, the height of the 3rd sealing part 30 is 30 micrometers, the height of the 4th sealing part 32 is 30 micrometers, and the height of the 2nd sealing part 28 is 30 micrometers. The width t4 of the contact surface between the third sealing portion 30 and the fourth sealing portion 32 is 40 μm or more, and the width t5 of the third sealing portion 30 not in contact with the fourth sealing portion 32 is 30 μm or less. .

  7A and 7C, the wiring 14 and the electrode pad 24 are formed on the surface of the piezoelectric substrate 10, and the first sealing portion 26 and the second sealing portion 28 are provided on the wiring 14. It has been. A through electrode 20 that penetrates the first sealing portion 26 and the second sealing portion 28 is provided on the electrode pad 24, and the acoustic wave element 12 and the through electrode 20 are connected to the wiring 14 and the electrode pad 24 on the wiring 14. It is connected. A solder ball 22 is provided on the through electrode 20. Accordingly, the through electrode 20 and the solder ball 22 function as a terminal portion that electrically connects the acoustic wave element 12 to the outside when the acoustic wave device is surface-mounted.

  Next, a method for manufacturing the acoustic wave device according to the first embodiment will be described with reference to FIGS. 8A to FIG. 8C, FIG. 9A to FIG. 9C, FIG. 10A to FIG. 10C, and FIG. 11A to FIG. 11C. It is sectional drawing which showed the manufacturing process in the location corresponded between AA of Fig.7 (a). 8 (d) to FIG. 8 (f), FIG. 9 (d) to FIG. 9 (f), FIG. 10 (d) to FIG. 10 (f) and FIG. 11 (d) to FIG. It is sectional drawing which showed the manufacturing process in the location corresponded between BB of (a). FIGS. 8A to 11F show a manufacturing process performed using the piezoelectric substrate 10 in a wafer state, and there are a plurality of regions to be acoustic wave devices on the wafer. A region to be one acoustic wave device among the acoustic wave devices is illustrated and described. In FIG. 11C and FIG. 11F, the peripheral regions are separated by dicing, so that a plurality of acoustic wave devices formed on the wafer are separated into one.

Referring to FIGS. 8A and 8D, Al (aluminum), Cu (copper), or the like is used on the surface of the piezoelectric substrate 10 made of LiNbO ₃ (lithium niobate) or LiTaO ₃ (lithium tantalate). A metal film is formed, and the acoustic wave element 12 and the wiring 14 are formed. An electrode pad 24 is formed on the wiring 14 in a region where the through electrode 20 is to be formed. Referring to FIGS. 8B and 8E, a first resin film 31 that is a negative photosensitive epoxy resin is applied on the piezoelectric substrate 10, the acoustic wave element 12, and the wiring 14 by spin coating to a thickness of 30 μm. To do. With reference to FIGS. 8C and 8F, ultraviolet light (UV light) is applied to the region where the cavity 16 on the functional portion of the acoustic wave element 12 is to be formed using the mask, and the through electrode 20 on the electrode pad 24. The first resin film 31 in the region other than the region where the film is to be formed and the peripheral region is irradiated.

  With reference to FIGS. 9A and 9D, the first resin film 31 is developed to remove the first resin film 31 in the region not irradiated with ultraviolet rays (UV light). As a result, an opening 36 is formed at a location that should become the cavity 16 on the functional portion of the acoustic wave element 12, and a third sealing portion 30 is formed around the functional portion of the acoustic wave element 12. An opening 42 is formed on the electrode pad 24. The 3rd sealing part 30 is hardened by heat-processing at 200 degreeC in nitrogen atmosphere for 1 hour. Referring to FIGS. 9B and 9E, a second 30 μm-thick second photosensitive epoxy resin film that is applied to the protective film 40 so as to hold the openings 36 and 42. The resin film 33 is pressed and pasted onto the third sealing portion 30 using a pressing roll 38 such as a laminator. As a result, the functional portion of the acoustic wave element 12 is covered, and the opening 36 becomes the cavity 16 and the opening 42 becomes the cavity 44. Referring to FIG. 9C and FIG. 9F, ultraviolet rays (UV light) are irradiated using a mask.

  With reference to FIG. 10A and FIG. 10D, the protective film 40 is peeled off and developed to remove the second resin film 33 in the region not irradiated with ultraviolet rays (UV light). As a result, the fourth sealing portion 32 is formed on the third sealing portion 30 so as to form the cavity portion 16 on the functional portion of the acoustic wave element 12. An opening 42 is formed on the electrode pad 24. The fourth sealing portion 32 is cured by heat treatment at 200 ° C. for 1 hour in a nitrogen atmosphere. As a result, the third sealing portion 30 and the fourth sealing portion 32 are provided, the cavity portion 16 is provided on the acoustic wave element 12, and the width t2 on the piezoelectric substrate 10 side is opposite to the width t3 on the piezoelectric substrate 10 side. A first sealing portion 26 having a step which becomes wider is formed. With reference to FIG. 10B and FIG. 10E, a third resin film 35 having a thickness of 30 μm, which is a negative photosensitive epoxy resin, is formed so as to cover the first sealing portion 26. The third resin film 35 is, for example, in the form of a film, and is formed using vacuum lamination or a vacuum press method. Further, the third resin film 35 may be formed in a liquid state by a spin coating method. Referring to FIG. 10C and FIG. 10F, the region other than the region on the electrode pad 24 and the peripheral region is irradiated with ultraviolet rays (UV light) using a mask.

  Referring to FIGS. 11A and 11D, the third resin film 35 in the region not irradiated with ultraviolet rays (UV light) is removed by development. Thereby, the second sealing portion 28 is formed on the first sealing portion 26. The 2nd sealing part 28 is hardened by heat-processing at 200 degreeC in nitrogen atmosphere for 1 hour. The second sealing portion 28 has an opening 42 on the electrode pad 24. Further, the second sealing portion 28 is not formed in the peripheral region. Referring to FIGS. 11B and 11E, the conductive through electrode 20 is formed by electroless plating Ni (nickel), Cu, Au (gold), or the like in the opening 42. The through electrode 20 may be formed by a method of filling a conductive material such as silver paste into the opening 42 by printing. Referring to FIG. 11C and FIG. 11F, a solder ball 22 connected to the through electrode 20 is formed on the through electrode 20 by mounting a SnAg solder ball or by mask printing and reflowing SnAg solder paste. . Thus, the through electrode 20 and the solder ball 22 that are electrically connected to the acoustic wave element 12 are formed. Thereafter, the piezoelectric substrate 10 is cut by dicing in the peripheral region. Thus, the acoustic wave device according to Example 1 is completed.

  According to the first embodiment, as shown in FIG. 7B, the first sealing portion 26 has a step that makes the width t <b> 2 on the piezoelectric substrate 10 side wider than the width t <b> 3 on the opposite side of the piezoelectric substrate 10. Have. Thus, even when the pattern of the fourth sealing portion 32 is shifted from the pattern of the third sealing portion 30 in the peripheral portion of the wafer due to the influence of the warpage of the wafer of the piezoelectric substrate 10, the comparative example 3 shown in FIG. Thus, the area | region B where the 4th sealing part 32 becomes a wrinkle does not generate | occur | produce. For this reason, when the second sealing portion 28 is formed on the first sealing portion 26, the contact area between the second sealing portion 28 and the piezoelectric substrate 10 becomes larger at the wafer peripheral portion than in the comparative example 3. In addition, the adhesion of the second sealing portion 28 is improved and peeling can be suppressed. Therefore, the yield in Example 1 can be improved as compared with Comparative Example 3. In addition, since the second sealing portion 28 is provided on the first sealing portion 26, the function of the acoustic wave element 12 can be controlled by the pressure at the time of modularization even if the elastic wave device according to the first embodiment is modularized. It can prevent that the ceiling part of the 1st sealing part 26 and the 2nd sealing part 28 on a part dents.

  Further, as shown in FIG. 7B, the first sealing portion 26 includes a third sealing portion 30 provided on the piezoelectric substrate 10 so as to surround the functional portion of the acoustic wave element 12, and an acoustic wave element. And a fourth sealing portion 32 provided on the third sealing portion 30 so as to form the cavity portion 16 on the 12 functional portions. In addition, the width of the third sealing portion 30 is wider than the width of the fourth sealing portion 32, and thus the third sealing portion 30 and the fourth sealing portion 32 have a step. Accordingly, the first sealing portion 26 having a step so that the width t2 on the piezoelectric substrate 10 side is wider than the width t3 on the opposite side of the piezoelectric substrate 10 can be easily formed.

  Further, as shown in FIG. 7B, the width t4 of the contact surface between the third sealing portion 30 and the fourth sealing portion 32 is 40 μm or more. In this case, even when the pattern of the fourth sealing portion 32 is shifted from the pattern of the third sealing portion 30 due to the influence of the warp of the wafer, the third sealing portion 30 and the fourth sealing portion 32 are not aligned. A sufficient width t4 of the contact surface can be ensured. For this reason, it is possible to prevent the developer from entering the hollow portion 16 from the interface between the third sealing portion 30 and the fourth sealing portion 32 in the development in the step of forming the fourth sealing portion 32. Further, the width t5 of the third sealing portion 30 not in contact with the fourth sealing portion 32 is 30 μm or less. From the viewpoint of downsizing the acoustic wave device, it is preferable that the width t5 of the third sealing portion 30 not in contact with the fourth sealing portion 32 is 30 μm or less.

  Further, as shown in FIGS. 7A and 7C, the first sealing portion 26 composed of the third sealing portion 30 and the fourth sealing portion 32 is provided on the functional portion of the acoustic wave element 12. In the example, the cavity portion 16 is also formed in a region other than the region where the cavity portion 16 is to be formed, for example, a region around the through electrode 20. However, the first sealing portion 26 may not be formed in a region around the through electrode 20. As a result, the area occupied by the first sealing portion 26 on the wafer is reduced, so that the compressive force of the first sealing portion 26 generated by the heat treatment of the first sealing portion 26 can be suppressed, and the amount of warpage of the wafer is reduced. can do. For the same reason, there may be a case where only the third sealing portion 30 is formed in the region around the through electrode 20 and the fourth sealing portion 32 is not formed.

  Further, as shown in FIG. 7B, when the step provided in the first sealing portion 26 has a stepped shape, that is, the side surface and the surface of the third sealing portion 30 and the fourth seal. The case where the side surface and the surface of the stop portion 32 are each formed as a flat surface is shown as an example. However, as shown in FIG. 12, it has a round shape in which at least one of the corner between the side surface and the surface of the third sealing portion 30 and the corner of the fourth sealing portion is rounded. It may be the case. Even in this case, the yield is improved, and an acoustic wave device is obtained in which the ceiling of the first sealing portion 26 and the second sealing portion 28 on the functional portion of the acoustic wave element 12 is not recessed by the pressure at the time of modularization. Can do.

  Furthermore, as shown in FIG. 7B, an example in which the angle θ2 formed on the fourth sealing portion 32 side between the surface of the third sealing portion 30 and the side surface of the fourth sealing portion 32 is a right angle is taken as an example. Although shown, it may be an acute angle or an obtuse angle. However, if the obtuse angle is excessively large, a region that becomes a wrinkle is generated, and a region in which the second sealing portion 28 is not formed in the formation process of the second sealing portion 28 is generated. For this reason, the adhesive force of the 2nd sealing part 28 falls, and it will become easy to generate | occur | produce peeling. Therefore, it is preferable that the angle θ2 formed between the surface of the third sealing portion 30 and the side surface of the fourth sealing portion 32 on the fourth sealing portion 32 side is a right angle, an acute angle, or a slight obtuse angle.

  Furthermore, as shown in FIG. 7B, the case where the angle θ1 formed between the surface of the piezoelectric substrate 10 and the third sealing portion 30 on the third sealing portion 30 side is a right angle is shown, but the present invention is not limited thereto. Alternatively, it may be an acute angle. Even in this case, since the area | region used as a wrinkle does not generate | occur | produce with the 1st sealing part 26, the contact area of the 2nd sealing part 28 and the piezoelectric substrate 10 can be enlarged. Therefore, the adhesion of the second sealing portion 28 can be improved, and the yield can be improved.

  Furthermore, as shown in FIG. 7B, the third sealing portion 30 has been illustrated by taking an example in which the contact surface with the fourth sealing portion 32 is planar, but as shown in FIG. You may have. In the case of having irregularities, the contact area between the third sealing portion 30 and the fourth sealing portion 32 is increased, so that the adhesion between the third sealing portion 30 and the fourth sealing portion 32 is improved. Can be made. The uneven shape can be formed by exposing and developing the third sealing portion 30 using a mask having a desired uneven pattern.

  Further, as shown in FIG. 7B, the first sealing portion 26 has been shown in the case where one step is provided by the third sealing portion 30 and the fourth sealing portion 32. Not limited to this, a plurality of steps may be provided. Even in this case, since the peeling of the second sealing portion 28 can be prevented, the yield can be improved.

  In the first embodiment, the case where the first sealing portion 26 and the second sealing portion 28 are photosensitive epoxy resins is shown as an example. However, the present invention is not limited to this, and other materials can be used as long as the functional portion of the acoustic wave element 12 can be protected. But you can. However, since the first sealing portion 26 having a step and the second sealing portion 28 formed on the first sealing portion 26 can be easily formed, the photosensitive resin such as a photosensitive polyimide resin is used. Is preferred.

  In the first embodiment, the acoustic wave element 12 is a surface acoustic wave (SAW) element formed on the piezoelectric substrate 10, but is formed on a piezoelectric film formed on a substrate such as a silicon substrate. It may be the case of the SAW element made. A piezoelectric thin film resonator (FBAR) element can also be used. When the FBAR element is used, the substrate is not a piezoelectric substrate, but a silicon substrate, a glass substrate, a sapphire substrate, or the like is used, and the FBAR is formed using a piezoelectric film on the substrate.

  Furthermore, in the first embodiment, as shown in FIG. 7A, the case where two acoustic wave elements 12 and two cavities 16 are formed is shown, but the number is not limited thereto. Further, in the first embodiment, the case where the through electrode 20 and the solder ball 22 are used as the terminal portions has been described as an example. However, any terminal may be used as long as it is electrically connected to the outside for surface mounting, for example, Au, Cu It may be a bump using a metal such as.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Piezoelectric substrate 12 Elastic wave element 14 Wiring 16, 16a Cavity part 20 Through electrode 22 Solder ball 24 Electrode pad 26 1st sealing part 28 2nd sealing part 30 3rd sealing part 31 1st resin film 32 4th sealing Stop portion 33 Second resin film 35 Third resin film 36 Opening portion 38 Pressing roll 40 Protective film 42 Opening portion

Claims (8)

An acoustic wave device provided on a substrate;
A first sealing portion made of a photosensitive resin provided on the substrate so as to have a cavity on the acoustic wave element;
A second sealing portion made of a photosensitive resin provided on the first sealing portion;
An external connection portion provided on the second sealing portion;
Passing through the first sealing portion and the second sealing portion, directly contacting the first sealing portion and the second sealing portion, and electrically connecting the acoustic wave element and the external connection portion A columnar electrode,
The first sealing portion is provided on the substrate so as to surround the functional portion of the acoustic wave device so that the substrate side has a step so that the width on the substrate side is wider than the width on the opposite side of the substrate. A third sealing portion, and a fourth sealing portion provided on the third sealing portion so as to form a cavity on the functional portion, and the width of the third sealing portion Is wider than the width of the fourth sealing portion,
The elastic wave device, wherein the second sealing portion is in direct contact with the first sealing portion including the step portion of the first sealing portion.   2. The acoustic wave device according to claim 1, wherein a shape of the step is a step shape or a round shape.   3. The acoustic wave device according to claim 1, wherein an angle formed between the surface of the third sealing portion and the side surface of the fourth sealing portion on the side of the fourth sealing portion is an acute angle.   3. The acoustic wave device according to claim 1, wherein an angle formed between the surface of the third sealing portion and the side surface of the fourth sealing portion on the side of the fourth sealing portion is an obtuse angle.   5. The acoustic wave device according to claim 1, wherein an angle formed on a side of the third sealing portion between a surface of the substrate and a side surface of the third sealing portion is an acute angle.   6. The acoustic wave device according to claim 1, wherein a contact surface of the third sealing portion with the fourth sealing portion is planar.   6. The acoustic wave device according to claim 1, wherein the third sealing portion has an uneven surface on a contact surface with the fourth sealing portion.   8. The acoustic wave device according to claim 1, wherein an end face of the second sealing portion is located on the substrate and inside the end face of the substrate. 9.

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