JP5883100B2 - Elastic wave device and manufacturing method thereof - Google Patents

Description

The present invention relates to a surface acoustic wave (SAW) device or a piezoelectric thin film resonator (F).
The present invention relates to an elastic wave device such as BAR (Film Bulk Acoustic Resonator).

A so-called wafer level package (WLP: Wafer Level Package) type acoustic wave device for the purpose of downsizing is known. This WLP type acoustic wave device has a piezoelectric substrate, an excitation electrode provided on the piezoelectric substrate, a cover for sealing the excitation electrode, and a cylindrical terminal penetrating the cover in the height direction (for example, Patent Document 1).

  Such a WLP type acoustic wave device is a piezoelectric wafer having a plurality of regions corresponding to one acoustic wave device, and in each region, an excitation electrode, a cover, a terminal, and the like are sequentially formed, and finally the wafer. Is manufactured by cutting each region.

JP 2008-227748 A

  The acoustic wave device is required to be further miniaturized, and it is thought that the request will continue in the future. However, if the structure of the current WLP type acoustic wave device is maintained, the overall structure is further miniaturized. It has become difficult.

  Further, if the entire structure of the elastic wave device is large, the number of elastic wave devices that can be obtained from one wafer is reduced accordingly, which hinders improvement in productivity of the elastic wave device.

  Therefore, it is desired to provide an acoustic wave device having a smaller overall structure and a method for manufacturing the same.

  An elastic wave device as one embodiment of the present invention includes a substrate, an excitation electrode disposed on the principal surface of the substrate, and the entire height direction on the side surface disposed on the principal surface so as to cover the excitation electrode. A cover having a groove portion extending over, and a terminal having a pillar portion filling the groove portion in a state where a side surface is flush with a side surface of the cover and electrically connected to the excitation electrode. Is.

  According to another aspect of the present invention, there is provided a method of manufacturing an acoustic wave device, the method comprising: forming an excitation electrode in each region of a wafer having a first region and a second region adjacent to the first region on a main surface; Forming a cover constituent layer covering the excitation electrode formed in each region, having a part straddling the boundary between one region and the second region, and a portion straddling the boundary of the cover constituent layer Forming a through hole straddling the boundary, forming a terminal constituent member filling the through hole, and cutting the wafer, the cover constituent layer, and the terminal constituent member along the boundary. Is included.

The elastic wave device configured as described above has a structure in which a groove portion is provided on a side surface of the cover and a terminal is provided so as to fill the groove portion, and the side surface of the terminal is located in the same plane as the side surface of the cover. Therefore, the cover becomes smaller than the conventional one, and the elastic wave device can be miniaturized. That is, the above configuration is compared with an elastic wave device in which the entire cylindrical terminal is covered by a member constituting the cover, in other words, an elastic wave device in which the side surface of the cover is positioned outward from the terminal. The elastic wave device has a structure in which the vertical and horizontal widths of the cover are narrowed to the position where the terminals are formed, and the elastic wave device can be reduced in size by the narrowed amount.

  Further, according to the method of manufacturing an acoustic wave device comprising the above steps, a step of forming at least a through hole across the boundary in a portion across the boundary between the first region and the second region of the cover constituent layer, and the through hole A step of forming a terminal component member that fills the substrate and a step of cutting the wafer, the cover component layer, and the terminal component member along the boundary, so that an elastic wave device corresponding to the downsizing can be easily manufactured. be able to. Further, since the number of elastic wave devices that can be obtained from one wafer increases, the productivity of the elastic wave device can be improved.

1 is an external perspective view of a SAW device according to an embodiment of the present invention. (A) is a plan view of the SAW device of FIG. 1, and (b) is a plan view of a state in which the cover of the SAW device of FIG. 1 is removed. It is sectional drawing in the III-III line of Fig.2 (a). It is an expanded sectional view of the part shown by M of FIG. (A) to (d) are cross-sectional views illustrating a method for manufacturing the SAW device of FIG. (A) to (d) are cross-sectional views illustrating a method for manufacturing the SAW device of FIG. (A) to (d) are cross-sectional views illustrating a method for manufacturing the SAW device of FIG. (A) And (b) is sectional drawing explaining the manufacturing method of the SAW apparatus of FIG. It is a top view explaining the manufacturing method of the SAW device of FIG. It is sectional drawing in the state which mounted the SAW apparatus of FIG. 1 on the circuit board.

<Structure of SAW device>
FIG. 1 is an external perspective view of a SAW device 1 according to an embodiment of the present invention, and FIGS. 2A and 2B are plan views of the SAW device 1. FIG. 2B is a plan view of the state where the cover 5 is removed. FIG. 3 is a cross-sectional view taken along the line III-III in FIG.

  The SAW device 1 is a so-called WLP type SAW device. The SAW device 1 includes a substrate 3, an excitation electrode 2 disposed on the main surface 3 a of the substrate 3, a cover 5 that protects the excitation electrode 2, a plurality of terminals 7 that are exposed from the cover 5, and an upper surface of the cover 5. The reinforcing layer 4 disposed and the insulating film 10 covering the reinforcing layer 4 are provided. In FIG. 1, the insulating film 10 is omitted.

  Signals are input to the SAW device 1 via any of the plurality of terminals 7. The input signal is filtered by the SAW device 1. Then, the SAW device 1 outputs the filtered signal via any of the plurality of terminals 7.

The substrate 3 is formed of a piezoelectric substrate. For example, the 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 planar shape of the substrate 3 may be appropriately set. For example, the substrate 3 is a rectangle having a predetermined direction (Y direction) as a longitudinal direction. Although the magnitude | size of the board | substrate 3 may be set suitably, for example, thickness is 0.2 mm-0.5 mm, and the length of 1 side is 0.5 mm-2 mm.

  Various electrodes and wirings such as the excitation electrode 2 and the connection wiring 11 are provided on the main surface 3 a of the substrate 3.

  A conductor layer 13 is attached to a back surface 3b which is a surface opposite to the main surface 3a of the substrate 3. By attaching the conductor layer 13 to the back surface 3b, excess charges accumulated in the substrate 3 are discharged, and the characteristics of the SAW device as a filter can be stabilized. Note that the back surface of the substrate 3 may be exposed without providing the conductor layer 13.

  The excitation electrode 2 is for generating SAW. As shown in FIG. 2B, the excitation electrode 2 includes a plurality of IDT electrodes composed of a pair of comb-like electrodes having a plurality of electrode fingers, and reflector electrodes disposed at both ends of the plurality of IDT electrodes. By arranging the excitation electrode 2 on the upper surface of the piezoelectric substrate 3, for example, a dual mode SAW resonator filter or the like is configured. FIG. 2B is a schematic diagram, and actually, a plurality of pairs of comb-like electrodes having a larger number of electrode fingers are provided. In addition, a plurality of excitation electrodes 2 may be connected by a system such as a series connection or a parallel connection, and a ladder-type SAW filter or the like may be configured. The excitation electrode 2 is made of an Al alloy such as an Al—Cu alloy.

  The excitation electrode 2 disposed on the main surface 3 a of the substrate 3 is connected to the terminal 7 via the connection wiring 11. The connection wiring 11 is made of, for example, the same material as that of the excitation electrode 2 and is made of an Al alloy such as an Al—Cu alloy. Further, the thickness of the wiring connection 11 may be made larger than the thickness of the excitation electrode 2 in order to reduce the wiring resistance of the connection wiring 11.

  Various electrodes and wirings such as the excitation electrode 2 formed on the main surface 3a of the substrate 3 are covered with a protective layer 14 as shown in the sectional view of FIG. The protective layer 14 contributes to the prevention of oxidation of various electrodes and wirings provided on the main surface 3a of the substrate 3 such as the excitation electrode 2. The protective layer 14 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 SAW. For example, the protective layer 14 is made of silicon oxide, silicon nitride, silicon, or the like.

  A cover 5 for protecting various electrodes and wirings arranged on the main surface 3 a of the substrate 3 and securing a sealing space 6 for the excitation electrode 2 is arranged on the main surface 3 a of the substrate 3. The planar shape of the cover 5 is, for example, the same as the planar shape of the substrate 3 and is rectangular. The cover 5 is formed slightly smaller than the main surface 3a of the substrate 3 so that the outer peripheral portion of the main surface 3a of the substrate 3 is exposed when viewed in plan.

  The cover 5 includes a frame portion 15 stacked on the main surface 3 a of the substrate 3 and a lid portion 17 stacked on the frame portion 15. An opening 16 is formed in the frame portion 15. The opening 16 is provided in a portion that overlaps the excitation electrode 2 when the frame 15 is viewed in plan. In other words, the inner wall of the frame portion 15 surrounds the excitation electrode 2 in plan view. When the opening 16 is closed by the lid 17, the sealing space 6 is formed between the main surface 3 a of the substrate 3 and the cover 5.

  The frame portion 15 is configured by a layer having a substantially constant thickness. The thickness of the frame portion 15 is, for example, 10 μm to 30 μm. The lid portion 17 is composed of a layer having a substantially constant thickness. The thickness of the lid part 17 is, for example, 10 μm to 30 μm.

The frame portion 15 and the lid portion 17 are made of, for example, a photosensitive resin. The photosensitive resin is, for example, a urethane acrylate-based, polyester acrylate-based, or epoxy acrylate-based resin that is cured by radical polymerization of an acryl group or a methacryl group.

  The frame portion 15 and the lid portion 17 may be formed of the same material or may be formed of different materials. In the figure, for convenience of explanation, the boundary line between the frame portion 15 and the lid portion 17 is clearly shown. However, in an actual product, the frame portion 15 and the lid portion 17 are formed of the same material and are integrally formed. It may be.

  The sealed space 6 is a hollow portion provided in the cover 5 and is provided in a region above the excitation electrode 2. Since the sealing space 6 is provided on the upper surface of the excitation electrode 2, the SAW generated by the excitation electrode 2 can easily propagate through the substrate 3. As shown by the broken line in FIG. 2A, the sealing space 6 is formed in a generally rectangular shape in plan view. Further, as shown in the cross-sectional view of FIG. 3, a corner portion on the lid portion 17 side of the sealing space 6, that is, a portion on the lid portion 17 side of the inner wall surface of the frame portion 15 is formed in a curved surface shape. Thereby, even if a large pressure is applied to the SAW device 1 from the outside when the SAW device 1 mounted on the external circuit board is resin-molded, the lid portion 17 can be prevented from being bent. Further, the size and number of the sealing spaces 6 may be set as appropriate. FIG. 2A shows an example in which only one sealing space 6 is provided. For example, when a plurality of excitation electrodes 2 are provided, a plurality of sealing spaces 6 are provided for each of the plurality of excitation electrodes 2. May be provided.

  Grooves 18 are provided at the four corners of the cover 5 and the central part of the long side. The groove portion 18 extends over the entire height direction of the side surface of the cover 5. The planar shape of the groove portion 18 positioned at the four corners of the cover 5 is a sector shape with a central angle of about 90 °. The planar shape of the groove located at the center of the long side of the cover 5 is a fan shape with a central angle of about 180 °, that is, a semicircular shape.

  The groove portion 18 is filled with the terminal 7. More specifically, the groove portion 18 is filled with a column portion 9 constituting a part of the terminal 7. The column portion 9 is disposed on the pad 8 provided near the end of the connection wiring 11. The side surface of the column portion 9 is located on the same plane as the side surface of the cover 5. That is, the side surface of the column portion 9 and the side surface of the cover 5 are flush with each other. Thus, since the pillar portion 9 fills the groove portion 18, the planar shape thereof is substantially the same as the planar shape of the groove portion 18. That is, the planar shape of the column part 9 positioned at the four corners of the cover 5 is a fan shape with a central angle of about 90 °, and the planar shape of the column part 9 positioned at the central part of the long side of the cover 5 is the central angle. Is a fan shape of about 180 °. In other words, the column portions 9 located at the four corners of the cover 5 correspond to one when the cylinder is divided into four equal parts in plan view, and the column portion 9 located at the center of the long side of the cover 5 Corresponds to one of two halves in plan view.

  The shape of the pillar part 9 is not limited to this, and for example, the diameter may be changed between a part of the pillar part 9 located in the frame part 15 and a part located in the lid part 17. Moreover, you may make it the side in the cross-sectional shape when the pillar part 9 is cut | disconnected in a height direction incline. In other words, the shape may be a part of a cone. By making the pillar portion 9 in such a shape, it is possible to suppress the terminal 7 from being pulled out of the substrate 3.

  The column portion 9 is formed by, for example, copper plating, and a plating base layer (not shown) is provided between the column portion 9 and the cover 5. The plating base layer is made of, for example, titanium or copper.

  A connection reinforcing layer may be provided between the column portion 9 and the connection wiring 11. The connection strengthening layer is for reinforcing the connection wiring 11 formed relatively thin and strengthening the connection between the connection wiring 11 and the column portion 9. The connection reinforcing layer has, for example, a three-layer structure in which chromium, nickel, and gold are stacked in this order from the main surface 3a side.

  On the other hand, a flange portion 12 is connected to an exposed portion of the column portion 9 from the main surface 5a of the cover 5. The flange portion 12 and the column portion 9 constitute a terminal 7. The flange portion 12 is formed by, for example, copper plating. When the flange part 12 and the column part 9 are formed by copper plating, both can be formed integrally.

  For example, the flange portion 12 is formed to be slightly larger than the end surface of the column portion 9 so as to cover the end surface exposed from the main surface 5 a of the cover 5 of the column portion 9, and the outer peripheral portion is laminated on the cover 5. Has been. The shape of the flange portion 12 in a plan view corresponds to the planar shape of the connected column portion 9.

  On the main surface 5a of the cover 5 on which the flange portion 12 is disposed, the reinforcing layer 4 is disposed as shown in FIGS. In FIG. 2A, the reinforcing layer 4 is indicated by a one-dot chain line. The reinforcing layer 4 is for reinforcing the strength of the cover 5. For example, after mounting the SAW device 1 on an external circuit board or the like, the entire SAW device 1 may be resin-molded, and a large pressure is applied to the SAW device 1 when resin-molding. Even in this case, the cover 5 can be prevented from being deformed by providing the reinforcing layer 4. As a result, the shape of the sealing space 6 can be prevented from being greatly distorted, so that the reliability of the SAW device 1 can be improved.

  The reinforcing layer 4 is made of a material having a higher Young's modulus than the material constituting the cover 5. For example, the Young's modulus of the cover 5 is 0.5 to 1.0 GPa, whereas the Young's modulus of the reinforcing layer 4 is 100 to 250 GPa. Specifically, the reinforcing layer 4 is made of a metal such as copper. The thickness of the reinforcing layer 4 is, for example, 1 to 50 μm. The reinforcing layer 4 is formed in a rectangular shape over a relatively wide range of the cover 5. From the viewpoint of preventing the deformation of the sealing space 6, it is preferable that the cover 5 is formed larger than the sealing space 6 so as to cover at least the entire sealing space 6 when seen through the plane. More specifically, as shown in FIG. 2A, the outer periphery of the reinforcing layer 4 may be located 5 μm or more outside the outer peripheral edge (opening portion of the frame portion 15) of the sealing space 6. The reinforcing layer 4 is not connected to the flange portion 12 and is in an electrically floating state.

  As shown in FIG. 3, the reinforcing layer 4 has an upper surface and side surfaces covered with an insulating film 10. By providing the insulating film 10, it is possible to prevent the conductive bonding material such as solder attached to the terminals 7 from adhering to the reinforcing layer 4 when the SAW device 1 is mounted on an external circuit board. Thus, the SAW device 1 in which mounting defects and electrical characteristics are hardly deteriorated can be obtained.

  If at least the side surface of the surface of the reinforcing layer 4 is covered with the insulating film 10, it is possible to sufficiently suppress the conductive bonding material such as solder attached to the terminals 7 from adhering to the reinforcing layer 4. By covering the upper surface of the reinforcing layer 4 with the insulating film 10, it is possible to more reliably suppress the conductive bonding material from adhering to the reinforcing layer 4. The insulating film 10 has a similar shape that is slightly larger than the reinforcing layer 4 in plan view. Note that the planar shape of the insulating film 10 is not limited to this, and for example, the insulating film 10 may be formed on the entire main surface 5 a of the cover 5 with a window provided in a portion corresponding to the flange 12.

  This insulating film 10 is made of resin. Specifically, as the resin material of the insulating film 10, a phenol resin, a fluorine resin, an epoxy resin, an acrylic resin, or the like can be used. As described above, the insulating film 10 made of resin reaches the main surface 5 a of the cover 5 along the side surface of the reinforcing layer 4. Since the insulating film 10 reaches the main surface 5 a of the cover 5, the insulating film 10 made of a resin material and the cover 5 are firmly bonded at the reaching portion, so that the insulating film 10 is peeled off from the reinforcing layer 4. Can be suppressed. Therefore, the reinforcing layer 4 is hardly exposed when the insulating film 10 is peeled off, and the effect of preventing the adhesion of the conductive bonding material to the reinforcing layer 4 is improved.

FIG. 4 is an enlarged view of a region M circled in FIG.
In FIG. 4, when focusing on the flange portion 12, a plating film 19 is formed on the surface of the flange portion 12. The plating film 19 has a two-layer structure of a first metal film 19a covering the flange portion 12 and a second metal film 19b covering the first metal film 19a. The first metal film 19a is for preventing diffusion (solder erosion) of the metal constituting the flange portion 12 (terminal 7) into the solder. For example, Cu, Ni, Pt, Pd, Ti, And alloys thereof can be used. The second metal film 19b is for preventing oxidation of the first metal film 19a and improving solder wettability, and for example, Au, Ag, or the like can be used.

  Next, paying attention to the insulating film 10, the insulating film 10 is located at a predetermined distance d from the flange portion 12. If the distance d is too small, the insulating film 10 tends to be peeled off from the cover 5. If the distance d is too small, the plating film 19 provided on the surface of the flange portion 12 grows in a region between the insulating film 10 and the flange portion 12, and the insulating film 10 is pushed up by the plating film 19 grown in the region. It is because it is done. Thus, the plating film 19 grows also in the region between the insulating film 10 and the flange portion 12 because the plating solution residue tends to exist in the portion when the distance d is too small. is there. For example, when the flange portion 12 is formed of Cu and the first metal film 19a is formed of Ni, it is necessary to treat the surface of the flange portion 12 made of Cu to be catalytically active against the reducing agent in the Ni plating solution. Therefore, a process for replacing Pd on the surface of the flange portion 12 is performed. At this time, if the distance d is too small, fine particles of Pd remain in the gap between the flange portion 12 and the insulating film 10, and the Pd serves as a catalyst nucleus to deposit Ni in that portion. Therefore, in order to prevent such a plating solution residue from remaining, it is necessary to increase the distance d to some extent. Specifically, the distance d is preferably set to 20 μm or more.

  As for the flange part 12, the outer peripheral part of a lower end part inclines inward as it goes to the main surface 5a of the cover 5. FIG. By forming the flange portion 12 in such a shape, the distance d between the insulating film 12 and the flange portion 12 can be increased without reducing the area of the upper surface of the flange portion 12. Therefore, the effect of suppressing the peeling of the insulating film 10 can be enhanced while keeping the area of the upper surface of the flange portion 12 necessary for maintaining the mounting strength of the SAW device 1 at a predetermined size. Moreover, since the surface area of the flange part 12 becomes large compared with the thing which an edge part does not incline inside, there exists an advantage that the contact area with solder increases and the mounting strength of the SAW apparatus 1 can be improved.

  Next, paying attention to the reinforcing layer 4, the outer peripheral portion of the lower end portion of the reinforcing layer 4 is inclined inwardly toward the main surface 5 a of the cover 5, as in the flange portion 12. By forming the end portion of the reinforcing layer 4 in such a shape, the insulating film 10 goes around to the inclined portion. As a result, the contact area between the insulating film 10 and the cover 5 can be increased by the amount of the insulating film 10 that has entered the inclined portion without reducing the distance d, and thus the main surface of the cover 5 of the insulating film 10. The effect of preventing peeling from 5a can be enhanced.

  Several windows 20 are provided in the insulating film 10. The window portion 20 is formed by hollowing out a part of the insulating film 10, and the reinforcing layer 4 is exposed from the portion. By providing such a window portion 20, when the SAW device 1 is mounted on an external circuit board, the reinforcing layer 4 can be connected to a pad provided on the circuit board. That is, the part exposed from the window part 20 among the reinforcement layers 4 can be functioned as a terminal. Thereby, the mounting strength of the SAW device 1 on the circuit board can be improved. Further, if the exposed portion of the reinforcing layer 4 from the window portion 20 is connected to the ground pad of the circuit board, the reinforcing layer 4 becomes the ground potential, and the electrical characteristics of the SAW device 1 can be stabilized.

  Although the shape of the window part 20 is circular, for example, arbitrary shapes, such as a polygonal thing, are possible. The window part 20 is located only on the main surface 5 a of the cover 5 just above the frame part 15. In other words, the window part 20 is not located in a place overlapping the vibration space 6. The portion of the main surface 5a of the cover 5 that overlaps the frame portion 15 is relatively more stable in shape than the portion that does not overlap the frame portion 15 (the portion that overlaps the vibration space 6). By providing, the mounting of the SAW device 1 is stabilized when the reinforcing layer 4 exposed from the window portion 20 is connected to an external pad.

  For example, as shown in FIG. 10, the SAW device 1 is configured such that a plurality of terminals 7 are pads on the mounting surface with the surface on the cover 5 facing the mounting surface of the circuit board 25 and placed on the mounting surface. 24 is mounted in a connected state. The terminal 7 and the pad 24 are connected by a conductive bonding material 26 such as solder. The entire acoustic wave device 1 is covered with a sealing resin 27.

  When forming the sealing resin 27, the SAW device 1 may be placed under an environment of a large pressure. Even in such an environment, the metal reinforcing layer 4 is provided, so that the sealing space 6 is not greatly deformed. Further, since the reinforcing layer 4 is covered with the insulating film 10 as described above, the contact of the mounting conductive bonding material 26 with the reinforcing layer 4 is suppressed. By connecting the reinforcing layer 4 exposed from the window portion 20 to the pad 24, the mounting strength of the SAW device 1 is improved. Furthermore, since the side surface of the terminal 7 (side surface of the column portion 9) is exposed, the mounting strength of the SAW device 1 can be increased by attaching the conductive bonding material 26 to this portion.

  According to the SAW device 1 described above, the groove portion 18 is provided on the side surface of the cover 5, and the terminal 7 is provided so as to fill the groove portion 18, and the side surface of the terminal 7 is in the same plane as the side surface of the cover 5. Since the structure is located, the elastic wave device can be downsized as compared with the conventional device in which the entire column portion of the terminal is covered with the cover. That is, as compared with the conventional acoustic wave device, the cover has a structure in which the vertical and horizontal widths are narrowed to the position where the terminals are formed, and the acoustic wave device can be miniaturized by the narrowed amount.

<Method for Manufacturing SAW Device>
Next, a method for manufacturing the SAW device 1 will be described with reference to FIGS. 5 to 9 are schematic cross-sectional views for explaining a method for manufacturing the SAW device 1. Each cross-sectional view is a cross-sectional view of a portion corresponding to FIG.

  The steps described below are realized in a so-called wafer process. That is, a thin film formation, a photolithography method, or the like is performed on a wafer having a plurality of regions to be a single substrate 3 by being divided, and then dicing is performed so that a large number of SAW devices 1 are obtained. Formed in parallel. However, in FIGS. 5A to 8B, only a part (first region and second region) in the wafer is illustrated. In addition, the shape of electrodes, wirings, and the like changes with the progress of the process, but common symbols may be used before and after the change.

  First, as shown in FIG. 5A, a wafer 33 having a first region T1 and a second region T2 adjacent to the first region is prepared. A boundary between the first region T1 and the second region T2 is indicated by a boundary line BL. The wafer 33 is a piezoelectric wafer such as a lithium tantalate single crystal or a lithium niobate single crystal.

Various electrodes and wirings such as the excitation electrode 2 and the connection wiring 11 are formed on the main surface 33 a of the wafer 33. Specifically, first, a conductor layer is formed on the main surface 3a of the wafer 33 by a thin film forming method such as a sputtering method, a vapor deposition method or a CVD (Chemical Vapor Deposition) method. Next, the conductor layer is patterned by a photolithography method using a reduction projection exposure machine (stepper) and an RIE (Reactive Ion Etching) apparatus. Thereby, the excitation electrode 2 and the connection wiring 11 are formed in each region.

  When various electrodes and wiring such as the excitation electrode 2 and the connection conductor 11 are formed, a protective layer 14 is formed as shown in FIG. Specifically, a thin film to be the protective layer 14 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 2 and the connection wiring 11. Next, a part of the thin film is removed by photolithography so that a portion of the connection wiring 11 where the column portion 9 is disposed is exposed. Thereby, the protective layer 14 is formed. Next, a connection reinforcing layer is formed as necessary. The connection reinforcing layer is formed by forming a conductive layer on the exposed portion of the connection wiring 11 from the protective layer 14 and the protective layer 14 by vapor deposition or the like, and patterning by a lift-off method or a photolithography method. .

  When the protective layer 14 is formed, the frame portion 15 is formed as shown in FIGS. 5C to 6A.

  Specifically, first, as shown in FIG. 5C, a frame portion constituting layer 35 that becomes the frame portion 15 is formed on the main surface 3 a of the substrate 3. The frame portion constituting layer 35 is formed so as to straddle the boundary between the first region T1 and the second region T2. The frame portion constituting layer 35 is formed, for example, by attaching a film formed of a negative type photoresist. Thereafter, the wafer 33 on which the frame portion constituting layer 35 is formed is subjected to heat treatment. Thereby, the adhesion strength between the frame portion constituting layer 35 and the wafer 33 can be increased.

  Next, as shown in FIG. 5D, the frame component layer 35 is irradiated with light L such as ultraviolet rays through the photomask 40. That is, an exposure process is performed. The photomask 40 is configured, for example, by forming a light shielding layer 39 on a transparent substrate 38. The light shielding layer 39 is disposed at a position corresponding to the position where the frame portion constituting layer 35 is to be removed. That is, they are arranged at positions corresponding to the sealing space 6, the column portion 9, and the dicing line, respectively. Each light shielding layer has a different width, the light shielding layer corresponding to the sealing space 6 is the largest, and the width of the light shielding layer corresponding to the column portion 9 is the smallest. The exposure may be projection exposure, proximity exposure, or contact exposure.

  Thereafter, as shown in FIG. 6A, development processing is performed to leave the portion irradiated with light in the frame portion constituting layer 35 and remove the portion not irradiated with light. Thereby, the opening part 16 used as the sealing space 6 and the 1st hole part 41 used as the groove part 18 for arrange | positioning the pillar part 9 are formed in the frame structure layer 35. FIG. At this time, the first hole 41 is formed so as to straddle the boundary between the first region T1 and the second region T2. At the same time, a groove serving as a dicing line is also formed. In the present embodiment, since the first hole portion 41 is positioned on the dicing line, the first hole portion 41 may be regarded as a part of the groove portion for the dicing line. However, the diameter of the first hole 41 is usually larger than the width of the groove. In this way, the frame portion 15 is formed.

  At the edge of the region where the light L of the frame portion constituting layer 35 is irradiated, the irradiated light L is diverged to the region where the light L of the frame portion constituting layer 35 is not irradiated. The light does not reach the 33a side sufficiently. Therefore, the edge portion of the region where the light of the frame portion constituting layer 35 is irradiated is removed without the main surface 33a side of the wafer 33 being sufficiently cured. As a result, the first hole portion 41 and the opening portion 16 are easily formed in a tapered shape (forward tapered shape) whose diameter increases toward the main surface 33a side.

  When the first hole portion 41 and the opening portion 16 are formed, the lid portion 17 is formed as shown in FIGS. 6 (b) to 6 (d).

  Specifically, first, as shown in FIG. 6B, a lid component layer 37 that becomes the lid portion 17 is formed on the frame portion 15. At this time, the lid portion constituting layer 37 is formed so as to straddle the boundary between the first region T1 and the second region T2. The lid component layer 37 is formed, for example, by attaching a film formed of a negative photoresist. By forming the lid component layer 37, the opening 16 of the frame portion 15 is closed, and the sealed space 6 is configured. The frame part 15 and the lid part constituting layer 37 are joined by being heated.

  Next, as shown in FIG. 6C, light L such as ultraviolet rays is irradiated to the lid constituting layer 37 through the photomask 50. That is, an exposure process is performed. Similar to the photomask 40, the photomask 50 is configured by attaching a light shielding layer 52 having a predetermined pattern on a transparent substrate 51. The light shielding layer 52 is disposed at a position corresponding to a position where the lid constituting layer 37 is to be removed. That is, it is disposed at a position corresponding to the column portion 9 and a position corresponding to the dicing line. For example, the photomask 50 has a configuration in which a portion corresponding to the sealing space 6 in the light shielding layer 39 in the photomask 40 is removed. The exposure may be projection exposure, proximity exposure, or close exposure.

  Thereafter, as shown in FIG. 6D, development processing is performed to leave a portion irradiated with light and remove a portion not irradiated with light from the lid constituting layer 37. As a result, a second hole 43 for arranging the column part 9 is formed in the lid part constituting layer 37. That is, the lid portion 17 is formed. By forming the lid portion 17, the cover 5 including the frame portion 15 and the lid portion 17 is completed. The second hole 43 is formed on the first hole 41. That is, the first hole 41 and the second hole 43 are connected to form one through hole 45.

  When the cover 5 is formed, the through portion 9 and the flange portion 12 are formed as shown in FIGS. 7 (a) and 7 (b). Specifically, a plating base layer (not shown) is first formed so as to cover the exposed portion of the cover 5. In addition to the exposed portion of the cover 5, the plating base layer is also formed on the inner peripheral surface and bottom surface of the through hole 45 and on the inner peripheral surface and bottom surface of the groove on the dicing line. The plating base layer is preferably formed of Ti—Cu or the like by, for example, sputtering or flash plating.

  The plating resist layer 55 is formed on the plating base layer. The plating resist layer 55 is formed on the substrate by a technique such as spin coating. In the plating resist layer 55, a flange hole portion 57 is formed on the through hole 45, and a reinforcing layer hole portion 54 is formed in a region where the reinforcing layer 4 is formed. The flange hole portion 57 has a diameter larger than that of the second hole portion 43, and the depth (thickness of the plating resist layer 55) is equal to or greater than the thickness of the flange portion 12. The reinforcing layer hole 54 is formed to be larger than the sealing space 6 so as to include the entire sealing space 6 when seen in a plan view, and the depth thereof is set to the same size as the flange hole 57. ing. The flange hole 57 and the reinforcing layer hole 54 are formed by, for example, photolithography.

  Next, as shown in FIG. 7B, the plating resist layer 55 is deformed so that the outer peripheral portion of the lower end portion of the plating resist layer 55 is inclined outwardly toward the main surface 5 a of the cover 5. To. In other words, the inner peripheral portion of the lower end portion of the hole portions (the reinforcing layer hole portion 54 and the flange hole portion 57) provided in the plating resist layer 55 is inwardly directed toward the main surface 5 a of the cover 5. The plating resist layer 55 is deformed so as to be inclined. Specifically, by heating the plating resist layer 55 at a predetermined temperature, the outer peripheral portion of the lower end of the plating resist layer 55 can be deformed so as to be inclined outward.

  Next, by performing a plating process, the reinforcing layer hole 54, the through hole 45, and the flange hole 57 are filled with a metal material such as Cu. The plating method may be selected as appropriate, but the electroplating method is preferable. This is because the electroplating method has a high degree of freedom in the height of the columnar terminals 7 and has good adhesion to the plating base layer. After performing the plating treatment, the upper surface of the metal layer formed by plating is polished by chemical mechanical polishing or the like to have a predetermined thickness.

  Thereafter, by removing the resist layer 55 for plating, as shown in FIG. 7C, the metal layer 44 that becomes the reinforcing layer 4 is formed on the vibration space 6, and the terminal that becomes the terminal 7 in the through hole 45. A component 47 is formed. Here, as described above, since the end portion of the plating resist layer 55 is inclined outwardly toward the main surface 5a of the cover 5, the plating resist layer 55 is formed as a guide. Contrary to the plating resist layer 55, the end of the metal layer 44 is inclined inward as the end goes toward the main surface 5 a of the cover 5.

  FIG. 9 is a plan view of the wafer 33 at the stage of FIG. The cross section taken along the line VII-VII in FIG. 9 corresponds to FIG. As shown in FIG. 9, since the terminal component member 47 to be the terminal 7 is located on the boundary line BL, the side surface of the cover 5 is simply cut along the boundary line BL in the last cutting step. The terminals 7 whose side surfaces are located on the same surface can be easily formed.

  Next, as shown in FIG. 7D, an insulating film constituting layer 59 to be the insulating film 10 is formed. The insulating film constituting layer 59 is formed so as to cover the flange portion 12 and the reinforcing layer 4 by, for example, applying a negative photosensitive resin to the upper surface 5 of the cover 5 by a spin coat method or the like.

  Next, as shown in FIG. 8A, the insulating film constituting layer 59 is irradiated with light L such as ultraviolet rays through the photomask 60, that is, an exposure process is performed. The photomask 60 is configured by attaching a light shielding layer 62 to a transparent substrate 61. The light shielding layer 62 is disposed at a position corresponding to the position where the insulating film constituting layer 59 is to be removed. That is, the light shielding layer 62 is provided at a position corresponding to a region along the outer periphery of the main surface 5 a of the cover 5 including the flange portion 12 and a position where the window portion 20 is formed. Here, the light shielding layer 62 is formed to have a width larger than the width of the flange portion 12. In the subsequent process, when a portion of the insulating film constituting layer 59 corresponding to the flange portion 12 is removed, a gap having a predetermined interval is formed between the insulating film 10 and the flange portion 12. After performing exposure using such a photomask 60, the development process is performed to cover the reinforcing layer 4 as shown in FIG. 8B, and the insulating layer in which the window portion 20 is formed in part. 10 is formed.

  Then, the plating film 19 is formed by plating the flange portion 12. Finally, the wafer 33 is cut along the dicing line (boundary line BL). At this time, the individual SAW devices 1 are completed by cutting the wafer 33, the cover constituent layer 39, and the terminal constituent member 47 located on the boundary between the first region T1 and the second region T2. The cutting mainly includes a first cutting step for cutting a portion of the cover constituting layer 39 and a second cutting step for mainly cutting a portion of the wafer 33. The first cutting step is performed using a first blade suitable for cutting the cover constituent layer 39, and the second cutting step is performed using a second blade suitable for cutting the wafer 33. Since the blade width of the first blade is larger than the blade width of the second blade, a step corresponding to the difference in the blade width is formed after cutting.

  According to the above-described manufacturing method, the small SAW device 1 can be easily manufactured without greatly changing the conventional manufacturing process. In addition, since the number of SAW devices 1 that can be acquired from one wafer 33 increases, the productivity of the SAW device can be improved.

  In the above embodiment, the SAW device 1 is an example of the acoustic wave device of the present invention. The frame portion constituting layer 35 and the lid portion constituting layer 37 are examples of the cover constituting layer of the present invention.

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

  The elastic wave device is not limited to the SAW device. For example, the acoustic wave device may be a piezoelectric thin film resonator. In the acoustic wave device, the protective layer 14, the connection reinforcing layer 8, and the conductor layer 13 may be omitted, or conversely, other appropriate layers may be formed. For example, in the embodiment, a resin layer that covers the conductor layer 13 may be provided. By providing a resin layer covering the conductor layer 13, there is an advantage that marking becomes easy.

1. Surface acoustic wave device (elastic wave device)
2 ... excitation electrode 3 ... substrate 4 ... reinforcing layer 5 ... cover 6 ... sealed space 7 ... terminal 9 ... column 10 ... insulating film 11 ... Connection wiring 12 ... flange 14 ... protective layer 15 ... frame 16 ... opening 17 ... lid 20 ... window

Claims (19)

A substrate,
An excitation electrode provided on the substrate;
A cover provided on the substrate via a space so as to cover the excitation electrode;
A terminal that is electrically connected to the excitation electrode and that is at least partially guided to the top of the cover along the outer surface of the cover;
The terminal is located inside the outer periphery of the substrate ,
The cover is an elastic wave device located inside the outer periphery of the substrate . 2. The acoustic wave device according to claim 1, wherein the outer surface of the cover has a concave portion that is recessed toward the space, and at least a part of the terminal is disposed in the concave portion. The cover has an annular frame portion that surrounds the space and a lid portion that closes an opening of the frame portion,
3. The elasticity according to claim 1, wherein the terminal has a width different between a height region portion corresponding to the frame portion and a height region portion corresponding to the lid portion in a cross-sectional view. Wave equipment. The elastic wave device according to any one of claims 1 to 3 , wherein the terminal includes a column portion and a flange portion coupled to an upper portion of the column portion. The elastic wave device according to claim 4 , wherein the flange portion is laminated on the cover. The cover has an annular frame portion that surrounds the space and a lid portion that closes an opening of the frame portion,
The width of the terminal is different between a portion located on a side of the outer surface of the cover and a portion located in a height region above the upper surface of the cover in a cross-sectional view. The elastic wave apparatus in any one of thru | or 5 . The elastic wave device according to any one of claims 1 to 6 , further comprising a reinforcing layer made of metal on the cover. The elastic wave device according to claim 7 , wherein an end portion of the reinforcing layer extends laterally from the space in a cross-sectional view. 9. The elastic wave device according to claim 7 , wherein an outer periphery of the reinforcing layer is located outside the entire outer periphery of the space in plan view. The elastic wave device according to any one of claims 7 to 9 , further comprising an insulating film that covers the reinforcing layer and is provided with a window portion that exposes a part of the reinforcing layer. The elastic wave device according to any one of claims 7 to 10 , further comprising a portion where a main surface of the cover is exposed between the reinforcing layer and the terminal. 11. The acoustic wave device according to claim 10 , wherein the insulating layer covers the entire main surface of the cover in a state where a second window portion is provided in a portion corresponding to the terminal. The elastic wave device according to any one of claims 1 to 12 , further comprising a conductor layer on a back surface opposite to the main surface of the substrate. The elastic wave device according to claim 2 , wherein a planar shape of the concave portion of the cover is a semicircular shape. The elastic wave device according to claim 2 , wherein a planar shape of the concave portion of the cover is a fan shape. The excitation electrode is a comb-shaped electrode, the elastic wave device according to claim 1 to 15. The elastic wave device according to any one of claims 1 to 16 ,
And a circuit board on which the acoustic wave device is mounted. The mounting structure according to claim 17 , further comprising a sealing member provided on the circuit board so as to cover the acoustic wave device. The acoustic wave device includes an exposed surface in which the outer peripheral portion of the main surface of the substrate is exposed from the cover,
The mounting structure according to claim 18 , wherein the sealing member is in contact with the exposed surface.

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