JP2014146891A - Piezoelectric device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress peeling of a conductor line provided on an insulating member constituting a piezoelectric device from the insulating member.SOLUTION: A piezoelectric device 1 includes: a substrate 11 having a piezoelectric element 11A; a substrate-side line 13 and a supporting part 15 which are provided on the substrate 11; an insulating member 16 provided on the substrate 11 via the supporting part 15; a conductor line 14 provided on a surface 16Fb of the insulating member 16; and a via conductor V electrically connecting the substrate-side line 13 and the conductor line 14. The conductor line 14 is at least partially embedded in the insulating member 16 in the thickness direction thereof. Thus, an adhesion area between the conductor line 14 and the insulating member 16 is increased to improve adhesion strength.

Description

  The present invention relates to a piezoelectric device and a manufacturing method thereof.

  A piezoelectric device having a piezoelectric element is used as a filter or a resonator in communication equipment such as a mobile phone. In order to obtain necessary electrical characteristics from the piezoelectric device or to match with an external circuit, the piezoelectric device is provided with a circuit element such as an inductor or a capacitor in addition to the piezoelectric element.

  Patent Document 1 (WO 2006/134828) describes a piezoelectric device 101 as shown in FIG. 12 as the structure of the piezoelectric device. The piezoelectric device 101 is provided on the substrate 111 via the substrate 111 having the piezoelectric element 111A and the substrate-side line 113, a frame-shaped support portion 115 provided on the main surface 111M of the substrate 111, and the support portion 115. And an insulating member 116 provided on the insulating member 116 and a conductor line 114 provided on the insulating member 116. The substrate side line 113 and the conductor line 114 are electrically connected by the via conductor VZ. The conductor line 114 has a two-layer structure of a metal film 114 a and a connection member 114 b and is formed on the surface of the insulating member 116. Patent Document 1 also describes that the conductor line 114 has a role as a circuit element such as an inductor.

WO2006 / 134928

  Due to the miniaturization and high integration of communication equipment, miniaturization of the piezoelectric device 101 is required. For example, if the conductor line 114 of the piezoelectric device 101 is miniaturized in order to meet the demand for downsizing, the contact area between the conductor line and the insulating member 116 is reduced. In that case, the adhesion between the conductor line 114 and the insulating member 116 is reduced, and the conductor line 114 is easily peeled off from the insulating member 116.

  Moreover, when the material of the conductor line 114 is a metal and the material of the insulating material 116 is a resin or glass, there exists a limit in improving these adhesiveness from a material viewpoint. In addition, since communication devices are often used in an environment where temperature changes are repeated, if the linear expansion coefficients of the conductor line 114 and the insulating member 116 are different, the conductor line 114 is more easily peeled off.

  The objective of this invention is providing the piezoelectric device which can solve the subject mentioned above, and its manufacturing method.

  A piezoelectric device according to the present invention is provided on a substrate having a piezoelectric element, an insulating member provided on the substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element, and a surface of the insulating member. And a conductor line that is at least partially embedded in the thickness direction of the insulating member.

  Preferably, the piezoelectric device includes a support portion provided so as to surround the periphery of the piezoelectric element.

  Moreover, it is preferable that the cross section of the conductor line has an arc shape or an obtuse angle shape.

  The conductor line is preferably chamfered.

  Moreover, it is preferable that the cross section of a conductor track is a polygon and the corner | angular part of the polygon-shaped cross section is circular arc shape.

  More preferably, the conductor line includes an inductor.

  A method for manufacturing a piezoelectric device according to a first aspect of the present invention includes: a substrate preparing step of preparing a substrate having a piezoelectric element; and a substrate on a substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element. An insulating member installation step for providing a photosensitive insulating member, a groove forming step for forming a groove having a predetermined pattern on the surface of the insulating member by exposing and developing the insulating member, and embedding a conductive material in the groove, A conductor line forming step of forming a conductor line on the surface of the insulating member.

  According to a second aspect of the present invention, there is provided a method for manufacturing a piezoelectric device comprising: a substrate preparing step for preparing a substrate having a piezoelectric element; and a substrate on a substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element. Insulating member installation process for providing an insulating member, lower mold member arranging process for arranging a photosensitive lower mold member on the insulating member, and a groove mold having a predetermined pattern on the lower mold member by exposing and developing the lower mold member Forming a groove on the surface of the insulating member by removing the lower mold member and the insulating member at a uniform speed from the groove mold side formed on the lower mold member; A conductor line forming step of forming a conductor line on the surface of the insulating member by embedding a conductive material in the groove.

  A method for manufacturing a piezoelectric device according to a third aspect of the present invention includes a substrate preparation step of preparing a substrate having a piezoelectric element, an insulating member preparation step of preparing a photosensitive insulating member, and exposing and developing the insulating member. Thus, a groove forming step for forming a groove having a predetermined pattern on the surface of the insulating member, and a conductor line forming step for forming a conductor line on the surface of the insulating member by embedding a conductive material in the groove, and a conductor line are formed. And an insulating member installation step in which the insulating member is provided on the substrate so as to cover the piezoelectric element while providing a distance from the piezoelectric element.

  Preferably, in the piezoelectric device manufacturing method according to the first to third aspects of the present invention, the photosensitive upper mold member is provided on the surface having the groove of the insulating member between the groove forming step and the conductor line forming step. A conductor line forming step, further comprising: an upper die member arranging step to be arranged; and a through groove forming step of forming a through groove in the upper die member at a position corresponding to the groove by exposing and developing the upper die member Includes a step of embedding a conductive material in the groove and the through groove, and a step of removing the upper mold member disposed on the insulating member.

  In the piezoelectric device according to the present invention, since the conductor line is embedded in the insulating member provided on the substrate, the close contact area is increased and the close contact force is improved. Thereby, it can suppress that the conductor line of a piezoelectric device peels from an insulating member.

  In the piezoelectric device manufacturing method according to the first to third aspects of the present invention, after forming a groove in the insulating member, a conductive material is embedded in the groove. Thereby, the conductor line of the state embedded in the insulating member can be formed suitably, and the adhesive force of a conductor line and an insulating member can be improved.

1A is a diagram schematically showing a cross section of the piezoelectric device 1 according to the first embodiment of the present invention, and FIG. 1B is an enlarged cross-sectional view of a conductor line 14A in the piezoelectric device 1. FIG. is there. It is a modification regarding conductor line 14A shown in Drawing 1 (B), and is an expanded sectional view of conductor line 54A which is a modification. It is a figure for demonstrating the manufacturing method of the piezoelectric device 1 shown in FIG. It is a process for forming the conductor track | line 54A shown in FIG. 2, Comprising: It is a figure for demonstrating the groove | channel formation process among the processes. It is a figure for demonstrating the other example regarding the groove | channel formation process shown in FIG. It is a process for forming conductor line 54A shown in FIG. 2, Comprising: It is a figure for demonstrating the conductor line formation process of the process. It is the figure which showed typically the cross section of the piezoelectric device 2 which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the piezoelectric device 2 shown in FIG. It is the figure which showed typically the cross section of the piezoelectric device 3 which concerns on 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the piezoelectric device 3 shown in FIG. It is a figure for demonstrating the groove | channel formation process regarding the manufacturing method of the piezoelectric device 3 shown in FIG. 2 is a cross-sectional view of a piezoelectric device 101 shown in Patent Document 1. FIG.

[First Embodiment]
The piezoelectric device according to the first embodiment includes a piezoelectric element and a circuit element such as an inductor or a capacitor. Piezoelectric elements are used to mutually convert mechanical vibrations and electrical signals, and inductors or capacitors are used to obtain the necessary electrical properties from the piezoelectric elements or to match external circuitry. . Examples of the piezoelectric element include a SAW (Surface Acoustic Wave) filter, a SAW resonator, a boundary wave filter, and a BAW (Bulk Acoustic Wave) filter. Piezoelectric devices are used in communication devices such as mobile phones, for example, in the frequency band of 700 MHz to 3 GHz.

  As shown in FIG. 1A, the piezoelectric device 1 includes a substrate 11 having a piezoelectric element 11A and an insulating member 16 having a circuit element such as an inductor. In FIG. 1A, which is a schematic diagram, one piezoelectric element 11A is shown, but actually, a plurality of piezoelectric elements 11A are provided on the substrate 11. In the first embodiment, a SAW filter will be described as an example of the piezoelectric element 11A.

  Piezoelectric element electrodes 12 such as IDT (Inter Digital Transducer) electrodes 12A, pad electrodes 12B, and reflectors (not shown) are provided on the main surface 11M of the substrate 11. The height of the piezoelectric element electrode 12 is, for example, 0.2 μm. However, this height dimension is appropriately designed according to the frequency band in which the piezoelectric device 1 is used.

  Similarly, on the main surface 11M of the substrate 11 and around the piezoelectric element 11A, a substrate-side line 13 as a drawing line is provided. The dimension of the cross section of the board | substrate side track | line 13 is 10 micrometers in height (thickness), for example. Of the substrate side lines 13, the substrate side lines 13A and 13C are electrically connected to the piezoelectric element 11A via the pad electrode 12B.

  The substrate 11 is a piezoelectric substrate, and examples of the material include lithium niobate, potassium niobate, lithium tantalate, crystal, langasite, ZnO, PZT, and lithium borate. Examples of the material of the piezoelectric element electrode 12 and the substrate side line 13 include metals such as Al, Pt, Cu, Au, Ti, Ni, Cr, W, Pd, Co, and Mn. The piezoelectric element electrode 12 and the substrate side line 13 may be a single layer, may be a laminate of different metals, or may be an alloy of different metals. When the substrate-side line 13 is formed of a plurality of layers, the uppermost layer is preferably selected from Cu, Ni, Au, Pt, and Pd because it is easy to obtain adhesion with the plating film.

  Further, the substrate 11 is provided with a support portion 15 having a predetermined thickness in order to secure a space S in which the piezoelectric element 11A can vibrate. The thickness (height dimension) of the support portion 15 is, for example, 15 μm. The support portion 15 is provided on the main surface 11M of the substrate 11 so as not to overlap the piezoelectric element 11A. The support portion 15 includes an outer periphery support portion 15A provided on the outer periphery of the substrate 11 so as to surround the piezoelectric element electrode 12 and the substrate-side lines 13A and 13B, and a plurality of the support portions 15 provided on the inner side from the outer periphery of the substrate 11. And dotted support portions 15B and 15C. The support 15 is made of a photosensitive insulating material, and examples of the material include polyimide resin, epoxy resin, acrylic resin, silicon resin, and benzocyclobutene resin.

  Inside the support portion 15, a first via conductor V <b> 1 is provided so as to penetrate the support portion 15 in the thickness direction. The first via conductor V1 includes first via conductors V1a and V1b provided on both sides of the outer peripheral support portion 15A, and first via conductors V1c and V1d provided on the dotted support portions 15B and 15C, respectively. There is. The first via conductors V1a and V1b are components for extracting the electrical characteristics of the piezoelectric device 1 to the outside. The first via conductors V1c and V1d are components for electrically connecting the substrate-side lines 13B and 13C and a conductor line 14 described later.

  The insulating member 16 is provided on the substrate 11 via the support portion 15 so as to cover the piezoelectric element 11A while providing a distance from the piezoelectric element 11A. Specifically, the insulating member 16 is disposed in parallel with the main surface 11 </ b> M of the substrate 11 while being in contact with the support portion 15. Thereby, in the piezoelectric device 1, the space S closed by the board | substrate 11, the support part 15, and the insulating member 16 is formed, and a surface acoustic wave can be excited. Accordingly, surface acoustic waves propagate on the main surface 11M of the substrate 11. In practice, a plurality of piezoelectric elements 11A are also provided in a direction perpendicular to the paper surface with reference to the board-side line 13C (not shown), and a space S is also formed above these piezoelectric elements 11A. . The insulating member 16 is in the form of a film and has a thickness of 20 μm, for example. Examples of the material of the insulating member 16 include polyimide resin, epoxy resin, acrylic resin, silicon resin, and benzocyclobutene resin. If the insulating member 16 includes silica, alumina, or the like as a filler in advance, the strength of the insulating member 16 can be increased. The insulating member 16 and the support portion 15 may be integrated. In this case, the insulating member 16 having the support portion 15 is provided so as to cover the piezoelectric element 11 </ b> A while providing a distance from the substrate 11.

  A second via conductor V2 is provided inside the insulating member 16 so as to penetrate the insulating member 16 in the thickness direction. The second via conductors V2a, V2b, V2c, and V2d are provided on the insulating member 16 so as to be electrically connected to the first via conductors V1a, V1b, V1c, and V1d, respectively. Of the second via conductor V2, the second via conductors V2c and V2d are components for electrically connecting the substrate-side lines 13B and 13C and a conductor line 14 described later, respectively. The second via conductors V2a and V2b are components for extracting the electrical characteristics of the piezoelectric device 1 to the outside.

  In FIG. 1A, the end portions Ea and Eb of the second via conductors V2a and V2b are exposed on the surface of the insulating member 16, respectively, and the ends Ea and Eb are connected to an external circuit. Terminals (not shown) may be provided. In the following, when the via conductor V is simply called, it means one or both of the first via conductor V1 and the second via conductor V2.

  On the outer surface 16Fb of the insulating member 16, a conductor line 14 that is electrically connected to the substrate side line 13 through the via conductor V is provided. That is, the insulating member 16 is a cover for forming the closed space S, and is also a rewiring substrate for forming the conductor line 14 such as an inductor or a capacitor. The conductor lines 14A to 14C function as inductors and are connected to the piezoelectric element 11A. The conductor line 14A is a main body of a spiral inductor. The conductor line 14B is an outer peripheral end of the spiral inductor, and is electrically connected to the substrate side line 13B through the second via conductor V2c and the first via conductor V1c in this order. The conductor line 14C is the center of the spiral inductor and is electrically connected to the substrate side line 13C via the second via conductor V2d and the first via conductor V1d in this order.

  As shown in FIG. 1B, the cross section of the conductor line 14A is a quadrangle, and the corner CA of the cross section is an arc. The cross-sectional dimensions of the conductor line 14A are, for example, a width w of 15 μm and a thickness t of 10 μm, and an arcuate radius r at the corner CA is 2 μm. Here, the conductor line 14 is embedded in the thickness direction (height direction) of the insulating member 16. The dimension in which the conductor line 14 is embedded is about half of the thickness direction of the conductor line 14. However, the conductor line 14 should just be embedded at least partially with respect to the thickness direction of the insulating member 16. Further, the entire conductor line 14 may be embedded in the insulating member 16.

  That is, since the conductor line 14 is embedded in the insulating member 16, the contact area between the conductor line 14 and the insulating member 16 is increased, and the adhesion force to the insulating member 16 is improved. Further, since the cross section of the conductor line 14A has an arc shape, current concentration at the corner CA of the conductor cross section is suppressed even when the piezoelectric device 1 is used in a high frequency band, and the conductor The loss of the line can be reduced.

  Examples of the material of the conductor line 14 include Al, Pt, Cu, Au, Ti, Ni, Cr, W, Pd, Co, and Mn. The conductor line 14 may be a single layer, may be a laminate of different metals, or may be an alloy of different metals. When the conductor line 14 is formed of a plurality of layers, the uppermost layer is preferably selected from Cu, Ni, Au, Pt, and Pd because it is easy to obtain adhesion with the plating film.

  FIG. 2 is a diagram illustrating a conductor line 54A that is a modification of the conductor line 14A. Also in FIG. 2, about half of the thickness of the conductor line 54 </ b> A is embedded in the insulating member 16. Of the conductor line 54A, the embedded portion 54Aa embedded in the insulating member 16 has an arcuate curved shape. Of the conductor line 54A, the protruding portion 54Ab protruding without being embedded is trapezoidal. The corner portion CB1 of the protruding portion 54Ab and the corner portion CB2 connecting the protruding portion 54Ab and the embedded portion 54Aa have an obtuse angle shape. Further, the corner portion CB1 of the protruding portion 54Ab is chamfered so as to have an arc shape. Since the cross section of the conductor line 54A has an arc shape or an obtuse angle shape, current concentration in the conductor is suppressed even when the piezoelectric device 1 is used in a high frequency band.

  The shape of the cross section of the conductor line 14 is not limited to the shape shown in FIG. 1B or FIG. 2, and various modifications are possible. For example, the cross section of the conductor line may be a triangle or a polygon that is a pentagon or more, and the corners may be chamfered so as to have an arc shape. Further, the conductor line may be chamfered into a tapered shape. The conductor line may be a simple circle, an ellipse, or a pentagon or more polygon without being chamfered.

  In the piezoelectric device 1 according to the first embodiment, since the conductor line 14 is embedded in the insulating member 16, the close contact area increases and the close contact force is improved. Thereby, even if the piezoelectric device 1 is placed in an environment in which a temperature change occurs, it is possible to suppress the conductor line 14 from being separated from the insulating member 16. In addition, as temperature conditions here, the heat cycle test described in JEDJESD22-A104C of JEDEC (Solid State Technology Association) is mentioned, for example.

  Further, since the conductor line 14 is embedded in the insulating member 16, the height of the piezoelectric device 1 can be reduced by the embedded dimension. In particular, when the insulating member 16 is in the form of a film, there is a limit to reducing the thickness of the insulating member 16 itself. Therefore, by embedding the conductor line 16, the height can be reduced more effectively.

  Preferably, the cross section of the conductor line 14 has an arc shape or an obtuse angle shape. Alternatively, the conductor line 14 is preferably chamfered. Alternatively, the conductor line 14 has a polygonal cross section, and the corner CA of the polygonal cross section is preferably an arc. Thereby, even if the piezoelectric device 1 is used in a high frequency band, current concentration inside the conductor can be suppressed, and the loss of the conductor line can be reduced. If the conductor lines 14 having these shapes are simply arranged on the surface of the insulating member 16, the contact area between the conductor lines 14 is reduced and the peeling is easy. However, as in the first embodiment, the conductor lines 14 are separated from the insulating member. If embedded in the surface 16Fb of 16, the peeling of the conductor line 14 can be suppressed and the current concentration in the conductor can be suppressed.

  These conductor lines 14 are more effective when including an inductor. When the current concentration occurs at the corner CA of the conductor cross section, the Q value decreases. However, by adopting the structure shown in the first embodiment, the current concentration can be suppressed and the conductor line 14 can be prevented from peeling. .

  Next, a method for manufacturing the piezoelectric device 1 will be described with reference to FIGS. 3 (A) to 3 (E). The method for manufacturing the piezoelectric device 1 includes a substrate preparation step, a support portion installation step, an insulating member installation step, a groove formation step, a conductor line formation step, and a via conductor formation step.

  The step shown in FIG. 3A is a substrate preparation step for preparing the substrate 11. On the main surface 11M of the substrate 11, a piezoelectric element electrode 12 that is a component of the piezoelectric element 11 and a substrate side line 13 that is electrically connected to the piezoelectric element electrode 12 are formed in advance. The piezoelectric element electrode 12 and the substrate side line 13 are formed by, for example, vapor deposition or sputtering.

  FIG. 3B is a view for explaining a support portion installation step for providing the support portion 15 on the substrate 11 and a via conductor formation step for providing the first via conductor V1 on the support portion 15. The support portion 15 is provided on the main surface 11M of the substrate 11 by a photolithography method. Specifically, a photosensitive insulating material is applied to the main surface 11M of the substrate 11, and is exposed to light using a photomask having a predetermined pattern, and further developed using a predetermined chemical solution. It is formed by. The support portion 15 includes an outer peripheral support portion 15A and interspersed support portions 15B and 15C, which are formed at the same time.

  The support portion 15 is formed with a via hole VH1 for providing the first via conductor V1. The via hole VH1 is formed at a position on the substrate side line 13 so as to penetrate the support portion 15 in the thickness direction. The via hole VH1 is formed at the same time when the support portion 15 is formed by photolithography. Then, the first via conductor V1 is provided by plating the via hole VH1, and the first via conductor V1 and the substrate side line 13 are electrically connected.

  The process shown in FIG. 3C is an insulating member installation process in which the insulating member 16 is provided on the substrate 11. In this step, the insulating member 16 is installed in parallel with the main surface 11M of the substrate 11 so as to come into contact with the support portion 15. The insulating member 16 is a photosensitive insulating material, specifically a photosensitive polyimide film. The insulating member 16 is bonded to the support portion 15 while being pressed by a roller heated to 100 ° C. Thereby, a closed space S surrounding the piezoelectric element 11A is formed.

  The process shown in FIG. 3D is a groove forming process for forming the groove 61 having a predetermined pattern on the surface 16Fb of the insulating member 16. The groove 61 having a predetermined pattern is formed by, for example, a photolithography method. Specifically, the insulating member 16 is exposed to light by exposing the photosensitive insulating member 16 to ultraviolet rays through a photomask having a predetermined pattern. And the groove | channel 61 is formed by developing the insulating member 16 using a predetermined chemical | medical solution. The arc shape at the corner of the groove 61 is formed by appropriately defocusing the focus of the ultraviolet rays to be exposed. For the method of forming the arc shape, the process shown in FIG. 4A described later can be referred to.

  The insulating member 16 is provided with a via hole VH2 for providing the second via conductor V2. The via hole VH2 is formed so as to penetrate the insulating member 16 in the thickness direction at a position on the first via conductor V1. The via hole VH2 may be formed by the photolithography method simultaneously with the groove 61, or may be formed by laser processing.

  FIG. 3E is a diagram for explaining a conductor line forming step for forming the conductor line 14 and a via conductor forming step for providing the second via conductor V <b> 2 in the insulating member 16. In the conductor line forming step, the conductor line 14 is formed on the surface 16Fb of the insulating member 16 by embedding a conductive material in the groove 61 formed in the groove forming step. The conductive material is embedded in the groove 61 by a method such as plating, vapor deposition, or sputtering. The conductive material is not only embedded in the groove 61 but also formed so as to rise outward from the opening portion of the groove 61. Thus, the conductor line 14 has a structure in which a part is embedded in the thickness direction of the insulating member 16 and the other part protrudes from the groove 61. The arcuate shape of the protruding portion is formed by chamfering.

  The via hole VH2 is also filled with a conductive material to provide a second via conductor V2, and the second via conductor V2 and the first via conductor V1 are electrically connected. The piezoelectric device 1 is manufactured through the steps shown in FIGS. 3 (A) to 3 (E). Note that the first via conductor V1 and the second via conductor V2 may be collectively formed using a method such as plating.

  In the method for manufacturing the piezoelectric device 1 according to the first embodiment, after the groove 61 is formed in the insulating member 16, a conductive material is embedded in the groove 61. Thereby, the conductor line 14 embedded in the insulating member 16 can be formed. As a result, the adhesion between the conductor line 14 and the insulating member 16 can be improved.

  Here, with reference to FIGS. 4A and 4B, a groove forming step for forming a conductor line 54A as a modification will be described. The process shown in FIG. 4A is a process for exposing the insulating member 16, and the process shown in FIG. 4B is a process for developing the insulating member 16.

  First, as shown in FIG. 4A, a photomask 64 having a predetermined pattern is disposed on the insulating member 16. Then, the insulating member 16 is exposed (exposure) by exposing the photomask 64 to ultraviolet rays (ultraviolet rays). At this time, by defocusing the focus of the ultraviolet rays, a deeply exposed portion and a shallowly exposed portion in the insulating member 16 are continuously created (see the broken line in FIG. 4A). Thereafter, the exposed portion is removed by developing the insulating member 16 with a predetermined chemical solution (development). As a result, as shown in FIG. 4B, a groove 62 that is recessed in a curved shape is formed on the surface 16 </ b> Fb of the insulating member 16. Specifically, the groove 62 has an arc shape. Since the groove 62 is curved, the cross section of the conductor line 54A formed later also has a curve. Instead of defocusing the ultraviolet rays, the groove 62 recessed in a curved shape can be formed by changing the aperture ratio of the photomask 64 stepwise.

  The process shown in FIGS. 5A to 5C is a diagram showing another example of the groove forming process shown in FIGS. 4A and 4B. According to this, the groove 62 can be formed regardless of whether the insulating member 16 is a photosensitive material.

  The process shown in FIG. 5A is a lower mold member arranging process for arranging the lower mold member 66 on the insulating member 16, and the process shown in FIG. 5B is a groove mold having a predetermined pattern on the lower mold member 66. 68 is a groove forming process for forming 68. First, a photosensitive lower mold member 66 and a photomask 64 having a predetermined pattern are sequentially arranged on the insulating member 16. Then, the lower mold member 66 is exposed by exposing the photomask 64 to ultraviolet rays. At this time, similarly to the process shown in FIG. 4A, by defocusing the ultraviolet rays, a portion that deeply exposes the lower mold member 66 and a portion that shallowly exposes the lower mold member 66 are continuously created (in FIG. 5A). (See dashed line). Thereafter, the lower mold member 66 is developed with a predetermined chemical solution, and the exposed portion is removed. Thereby, as shown in FIG. 5B, a groove mold 68 that is recessed in a curved shape is formed in the lower mold member 66.

The process shown in FIG. 5C is a groove forming process for forming the groove 62 on the surface 16Fb of the insulating member 16 using the groove mold 68. In this step, the groove 62 is formed on the surface 16Fb of the insulating member 16 by removing the lower mold member 66 and the insulating member 16 at a uniform speed from the groove mold 62 side formed in the lower mold member 66 (Removal processing). To do. Examples of means for removing at a uniform rate include dry etching, wet etching, and sand blasting. The shape of the groove 62 formed by the removal is a shape obtained by transferring the shape of the groove mold 68. As a result, a groove 62 recessed in a curved shape is formed as shown in FIG. In this modification, silicon, sapphire, glass, LiTaO ₃ , LiNbO _3, or the like can be used as the insulating member 16 in place of the photosensitive polyimide. Since these materials have high rigidity, they are suitable as covers and rewiring boards.

  Next, a process for forming a conductor line 54A as a modification will be described with reference to FIGS. 6 (A) to 6 (D). As described above, when the piezoelectric device 1 is used in a high frequency band, it is preferable that current concentration does not occur at the corners of the conductor cross section of the conductor line. Therefore, a method of forming the conductor line 54A in which current concentration is less likely to occur at the corners of the conductor cross-section by the steps shown in FIGS. 6A to 6D will be described.

  The process shown in FIG. 6A is an upper mold member arranging process for arranging the upper mold member 76 on the insulating member 16. First, the seed layer 71 is formed along the surface 16Fb of the insulating member 16 by sputtering or the like. Thereby, the seed layer 71 is also formed in the groove 62 formed by the process shown in FIG. 4B or 5C. The seed layer 71 is a layer that serves as a power feeding path when the conductor line 54A is formed by plating. Examples of the material of the seed layer 71 include Cu or a laminated film of Ti and Cu. Next, the photosensitive upper mold member 76 is disposed on the surface of the insulating member 16 having the groove 62. The upper mold member 76 is a mold for forming the protrusion 54Ab on the embedded portion 54Aa shown in FIG. Here, as a method for forming the mold of the upper mold member 76, a case where a negative photoresist is used will be described as an example. First, a photomask 78 having a predetermined pattern is disposed on the upper mold member 76. The photomask 78 is designed so as to shield ultraviolet rays in a region where the groove 62 is present and to pass ultraviolet rays in a region where the groove 62 is not present when viewed from the plane direction. Next, the upper mold member 76 is exposed to ultraviolet rays, thereby exposing the upper mold member 76 to exposure. At this time, since the ultraviolet light attenuates as it proceeds in the thickness direction of the upper mold member 76, the area where the upper mold member 76 is exposed has a smaller area on the lower surface 76a side than the area on the upper surface 76b side of the upper mold member 76 (FIG. 6 (A) (see broken line).

  The process shown in FIG. 6B is a through groove forming process for forming the through groove 72 in the upper mold member 76. In this step, the upper die member 76 is developed to remove the unexposed areas of the upper die member 76. Thereby, in the upper mold member 76, the through groove 72 is formed at a position corresponding to the groove 62. The through-groove 72 has a larger area on the lower surface 76a side than the area on the upper surface 76b side of the upper mold member 76, and has a reverse taper shape. Thereby, the through-groove 72 for forming protrusion part 54Ab is formed. Since the through groove 72 has a reverse taper shape, the corners CB1 and CB2 of the protrusion 54Ab of the conductor line 54A to be formed later have an obtuse angle.

  The process shown in FIG. 6C is a conductor embedding process in which the conductive material 74 is embedded in the groove 62 and the through groove 72. The state where the conductive material 74 is embedded as shown in FIG. 6C is formed by depositing a conductor from above the upper mold member 76. Examples of the film forming method include plating, vapor deposition, and sputtering. If the conductive material 74 is made of Cu or Ni and the conductor is formed by electrolytic plating, the film forming rate is increased and the conductive material 74 can be embedded efficiently.

  The process shown in FIG. 6D is an upper mold member removing process for removing the upper mold member 76 arranged on the insulating member 16. In this step, the upper mold member 76 is removed together with the seed layer 71 in a region other than the groove 62. Thereby, the conductor line 54A is formed to have a predetermined pattern. At the same time as removing the upper mold member 76, the corner portion CB1 of the cross section of the conductor line 54A is chamfered. Examples of means for cutting the corner portion CB1 of the cross section of the upper mold member 76 and the conductor line 54A include dry etching, wet etching, and sand blasting.

  The cross section of the conductor line 54A formed by the steps shown in FIGS. 6A to 6D has an arc shape and an obtuse angle shape. Further, the corner portion CB1 of the cross section is chamfered. Thereby, even if it is a case where the piezoelectric device 1 is used in a high frequency band, the electric current concentration inside a conductor is suppressed.

  In the step of removing the upper mold member 76, the conductor line 54A is placed in a high temperature state and a physical peeling force is applied. However, since the conductor line 54A is embedded in the insulating member 16, peeling is performed. Can be suppressed.

[Second Embodiment]
FIG. 7 is a diagram schematically showing a cross section of the piezoelectric device 2 according to the second embodiment. The piezoelectric device 2 is an embodiment in which the conductor line 24 is also provided on the inner surface 26Fa of the insulating member 26. About the structure which is common in 1st Embodiment, the same number is attached | subjected in a figure and description is abbreviate | omitted.

  Two piezoelectric elements 11 </ b> A are provided on the substrate 21 of the piezoelectric device 2. However, actually, the piezoelectric element 11A (not shown) is also provided in a direction orthogonal to the paper surface. Substrate side lines 23A to 23C are provided on the main surface 21M of the substrate 21, and the substrate side lines 23A to 23C are electrically connected to the two piezoelectric elements 11A. The support portion 25 is provided on the main surface 21M of the substrate 21 so as to surround the piezoelectric element 11A. Although only the outer peripheral support portion 25 is shown in FIG. 7, other support portions (not shown) scattered inside the outer peripheral support portion 25 may be provided as necessary. The insulating member 26 is provided on the substrate 21 via the support portion 25 so as to cover the piezoelectric element 11A while providing a distance from the piezoelectric element 11A. As a result, a closed space S surrounded by the substrate 21, the support portion 25, and the insulating member 26 is formed.

  A conductor line 24 electrically connected to the substrate side line 23 is provided on the surface 26F of the insulating member 26. The conductor line 24 includes a conductor line 24E formed on the outer surface 26Fb of the insulating member 26 and conductor lines 24A to 24D formed on the inner surface 26Fa facing the main surface 21M of the substrate 21. Also in the second embodiment, the conductor line 24 is embedded in the thickness direction (height direction) with respect to the insulating member 26.

  The conductor lines 24A to 24C function as inductors and are connected in parallel to the piezoelectric element 11A. The conductor line 24A is a main body of a spiral inductor. The conductor line 24B is an outer peripheral end of the spiral inductor, and is electrically connected to the board side line 23A through the conductor line 24D and the first via conductor V1a in this order. The conductor line 24C is the center of the spiral inductor, and is electrically connected to the board side line 23C through the second via conductor V2c, the conductor line 24E, the second via conductor V2b, and the first via conductor V1b in this order. Connected. The conductor line 24D is electrically connected to the external terminal 29A via the second via conductor V2a, and the conductor line 24E is electrically connected to the external terminal 29B via the second via conductor V2b. .

  The external terminals 29A and 29B are for electrically connecting the piezoelectric device 2 to an external circuit (not shown), and are end portions Ea of the second via conductors V2a and V2b exposed on the surface 26Fb of the insulating member 26. , Eb, respectively. Examples of the material of the external terminal 29 include Cu, Ni, Au, Pd, and Sn—Ag. The external terminal 29 may be a single layer, a laminate of different metals, or an alloy of different metals.

  The second embodiment has the following effects in addition to the effects of the invention described in the first embodiment. According to the second embodiment, since the conductor lines 24 are provided on both the outer and inner surfaces of the insulating member 26, the area for forming circuit elements such as inductors in the piezoelectric device 2 can be increased. Further, compared to the first embodiment, the number of piezoelectric elements 11A formed on the substrate 21 can be increased.

  The manufacturing method of the piezoelectric device 2 will be described with reference to FIGS. The manufacturing method of the piezoelectric device 2 is characterized in that a groove 61a is formed in an insulating member 26 prepared in advance, and a conductive material is embedded in the groove 61a, and then the insulating member 26 is installed on the substrate 21.

  FIG. 8A is a diagram for explaining a substrate preparation step, a support portion installation step, and a via conductor formation step. In these steps, the support portion 25 is provided on the substrate 21 prepared in advance, and the first via conductor V <b> 1 is formed in the support portion 25. These steps are executed by the same method as in FIGS. 3A and 3B shown in the first embodiment.

  FIG. 8B is a diagram for explaining the insulating member preparing step and the conductor line forming step. The insulating member 26 prepared in advance is photosensitive. First, a groove 61a having a predetermined pattern is formed on the surface 26Fa of the insulating member 26 by a photolithography method. Thereafter, the conductive material is embedded in the groove 61a, and the conductor lines 24A to 24D are formed on the surface 26Fa of the insulating member 26.

  The process shown in FIG. 8C is an insulating member installation process in which the insulating member 26 is provided on the substrate 21. The insulating member 26 is disposed in contact with the support portion 25 so that the previously formed conductor lines 24 </ b> A to 24 </ b> D face the main surface 21 </ b> M of the substrate 21. At this time, the insulating member 26 is bonded to the support portion 25 in a positioned state so that the conductor line 24D is electrically connected to the first via conductor V1a.

  FIG. 8D is a view for explaining a conductor line forming step for forming the conductor line 24E and a via conductor forming step. In the conductor line forming step, the groove 61b having a predetermined pattern is formed on the surface 26Fb of the insulating member 26 by a photolithography method. Thereafter, the conductive material is embedded in the groove 61b, and the conductor line 24E is formed on the surface 26Fb of the insulating member 26. Prior to forming the conductor line 24E, the second via conductor V2c is formed in the insulating member 26. The second via conductors V2a and V2b are also formed by the same method as in the first embodiment.

  The process shown in FIG. 8E is an external terminal formation process for forming the external terminals 29. The external terminals 29A and 29B are formed at the end portions Ea and Eb of the second via conductors V2a and V2b, for example, by plating. The piezoelectric device 2 is manufactured by the steps shown in FIGS. 8A to 8E.

[Third Embodiment]
FIG. 9 is a diagram schematically showing a cross section of the piezoelectric device 3 according to the third embodiment. About the structure which is common in 1st Embodiment or 2nd Embodiment, the same code | symbol is attached | subjected in a figure and description is abbreviate | omitted.

The piezoelectric device 3 uses boundary acoustic waves instead of surface acoustic waves. Therefore, as shown in FIG. 9, a dielectric 38 is provided in a region surrounded by the substrate 31, the support portion 25, and the insulating member 36. Examples of the material of the dielectric 38 include SiO ₂ .

  The insulating member 36 of the piezoelectric device 3 includes two layers of insulating members 36A and 36B. The insulating member 36 is photosensitive, and examples of the material include silicon oxide, silicon nitride, silicon carbide, aluminum nitride, DLC (diamond-like carbon), and Si. Conductor lines 34A to 34C having a thickness equal to the thickness of the insulating member 36A are provided inside the insulating member 36A. The insulating member 36A is provided with second via conductors V2a and V2b, respectively. The insulating member 36B is provided further outside the insulating member 36A. Conductor lines 34D and 34E are provided on the outer surface 36Fb of the insulating member 36B. The conductor lines 34D and 34E are lead lines formed on the surface 36Fb of the insulating member 36B. The insulating member 36B is provided with third via conductors V3a and V3b. The third via conductors V3a and V3b are electrically connected to the second via conductors V2a and V2b, respectively, and the second via conductors V2a and V2b are electrically connected to the first via conductors V1a and V1b, respectively. Is done.

  The conductor lines 34A to 34C function as inductors and are connected in parallel to the piezoelectric element 11A. The conductor line 34A is the main body of the spiral inductor. The conductor line 34B is an outer peripheral end of the spiral inductor, and is electrically connected to the third via conductor V3a through the third via conductor V3c and the conductor line 34D in this order. The conductor line 34C is the center of the spiral inductor, and is electrically connected to the third via conductor V3b via the third via conductor V3d and the conductor line 34E.

  Further, a protective member 37 is provided so as to cover the conductor lines 34D and 34E, the insulating member 36, and the substrate 31. The protective member 37 is a photosensitive insulating material, and examples of the material include polyimide resin, epoxy resin, acrylic resin, silicon resin, and benzocyclobutene resin. The protective member 37 may be a single layer or a plurality of layers. By further providing the protective member 37 outside the insulating member 36, the strength of the piezoelectric device 3 is improved and the environmental resistance is also improved. Note that the fourth via conductors V4a and V4b are provided in the protective member 37 so as to be electrically connected to the third via conductors V3a and V3b, respectively.

  The external terminals 29A and 29B are provided at the end portions Ea and Eb of the fourth via conductors V4a and V4b exposed on the outer surface of the protective member 37, respectively. Bumps 39 are formed on the external terminals 29, respectively.

  A method for manufacturing the piezoelectric device 3 will be described with reference to FIGS. 10 (A) to 10 (E).

  FIG. 10A is a diagram for explaining a substrate preparation step, a support portion installation step, and a via conductor formation step. In these steps, the support portion 25 is provided on the substrate 31 prepared in advance, and the dielectric 38 is provided on the substrate 31. The support portion 25 is formed by a method similar to that shown in FIGS. 3A and 3B shown in the first embodiment. The dielectric 38 is formed by filling the dielectric material on the substrate 31 located on the inner peripheral side of the support portion 25 and then curing the dielectric material. The first via conductor V1 is also formed in this step.

  FIG. 10B is a diagram for explaining an insulating member installation step, a conductor line formation step, and a via conductor formation step. In these steps, the insulating member 36A is installed on the support portion 25, and the conductor lines 34A to 34C and the second via conductors V2a and V2b are formed.

  The insulating member 36A is formed by applying a liquid glass material to the support portion 25 and the dielectric 38 and then curing the glass material. The second via conductor V2 is formed by the same method as in the second embodiment. The conductor lines 34A to 34C are formed by embedding a conductive material in a groove 82 formed so as to penetrate the insulating member 36A in the thickness direction. Thereby, the thickness of the conductor lines 34A to 34C can be increased to an extent equal to the thickness of the insulating member 36A, and the area of the conductor cross section can be increased.

  The groove 82 is formed by, for example, a groove forming process shown in FIGS. 11 (A) and 11 (B). First, as shown in FIG. 11A, a photomask 88 having a predetermined pattern is placed on the insulating member 36A, and ultraviolet rays are exposed from above the photomask 88 to expose the insulating member 36A. Thereafter, as shown in FIG. 11B, the exposed portion is removed by developing the insulating member 36A with a predetermined chemical solution. As the predetermined chemical solution, a chemical solution in which the dielectric 38 is not melted and the exposed insulating member 36A is melted is selected. Thereby, the groove | channel 82 which has the depth which reaches | attains the surface 36Fa of 36 A of insulating members can be formed.

  FIG. 10C is a diagram for explaining an insulating member installation step, a conductor line formation step, and a via conductor formation step. In these steps, the insulating member 36B is installed outside the insulating member 36A, and the conductor lines 34D and 34E and the third via conductors V3a, V3b, V3c, and V3d are formed. The insulating member 36B is formed by applying a liquid glass material to the insulating member 36A and then curing the glass material. The conductor lines 34D and 34E are formed by the same method as in the second embodiment. The third via conductor V3 is formed by the same method as the second via conductor V2.

  FIG. 10D is a diagram for explaining the protective member forming step and the via conductor forming step. In these steps, after the protective member 37 is formed outside the insulating member 36B, the fourth via conductors V4a and V4b are formed inside the protective member 37. The protective member 37 is formed by applying a liquid epoxy resin on the outside of the insulating member 36B and then curing the epoxy resin in an oven. The fourth via conductors V4a and V4b are formed by forming a via hole in the protective member 37 with a laser and then filling the via hole with a conductive material. When the protective member 37 is photosensitive, a via hole may be formed by a photolithography method.

  The step shown in FIG. 10E is an external terminal formation step. In this step, the external terminals 29A and 29B are formed at the end portions Ea and Eb of the fourth via conductors V4a and V4b, respectively. The bump 39 is formed in contact with the external terminal 29 by a bump bonder (not shown). The piezoelectric device 3 is manufactured by the steps shown in FIGS. 10 (A) to 10 (E).

  Each of the embodiments described above is not intended to limit the invention described in the claims, and various modifications are possible within the scope where the same technical idea is recognized. For example, the conductor line may be a circuit element such as a capacitor or a resistor. Further, the support portion and the insulating member may be provided on the substrate in an integrated state instead of separate configurations. In addition, the piezoelectric device may be manufactured by forming a plurality of piezoelectric devices on the parent substrate and then dividing the parent substrate into pieces.

1: Piezoelectric device 11: Substrate 11A: Piezoelectric element 11M: Main surface 12 of substrate 11: Piezoelectric element electrode 12A: IDT electrode 12B: Pad electrodes 13, 13A, 13B, 13C: Substrate side lines 14, 14A, 14B, 14C, 54A: Conductor lines 15, 15A, 15B, 15C: Support part 16: Insulating members 16F, 16Fa, 16Fb: Surface 54Aa of insulating member 16: Buried part 54Ab of conductor line 54A: Protruding parts 61, 62 of conductor line 54A 64, 78: Photomask 66: Lower mold member 68: Groove mold 71: Seed layer 72: Through groove 74: Conductive material 76: Upper mold member CA, CB1, CB2: Corner portion of conductor line V: Via conductor V1, V1a , V1b, V1c, V1d: first via conductors V2, V2a, V2b, V2c, V2d: second via conductors VH1, VH2: via holes

Claims (10)

A substrate having a piezoelectric element;
An insulating member provided on the substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element;
A conductor line provided on the surface of the insulating member and at least partially embedded in the thickness direction of the insulating member;
A piezoelectric device comprising:   The piezoelectric device according to claim 1, further comprising a support portion provided so as to surround the periphery of the piezoelectric element.   The piezoelectric device according to claim 1, wherein a cross section of the conductor line has an arc shape or an obtuse angle shape.   The piezoelectric device according to any one of claims 1 to 3, wherein the conductor line is chamfered.   5. The piezoelectric device according to claim 1, wherein a cross section of the conductor line is a polygon, and a corner portion of the polygonal cross section is an arc shape.   The piezoelectric device according to claim 1, wherein the conductor line includes an inductor. A substrate preparation step of preparing a substrate having a piezoelectric element;
An insulating member installation step of providing a photosensitive insulating member on the substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element;
Forming a groove having a predetermined pattern on the surface of the insulating member by exposing and developing the insulating member; and
A conductor line forming step of forming a conductor line on the surface of the insulating member by embedding a conductive material in the groove;
A method for manufacturing a piezoelectric device comprising: A substrate preparation step of preparing a substrate having a piezoelectric element;
An insulating member installation step of providing an insulating member on the substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element;
A lower mold member arranging step of arranging a photosensitive lower mold member on the insulating member;
A groove mold forming step of forming a groove mold having a predetermined pattern on the lower mold member by exposing and developing the lower mold member;
A groove forming step of forming a groove on the surface of the insulating member by removing the lower mold member and the insulating member at a uniform rate from the groove mold side formed in the lower mold member;
A conductor line forming step of forming the conductor line on the surface of the insulating member by embedding a conductive material in the groove;
A method for manufacturing a piezoelectric device comprising: A substrate preparation step of preparing a substrate having a piezoelectric element;
An insulating member preparation step of preparing a photosensitive insulating member;
Forming a groove having a predetermined pattern on the surface of the insulating member by exposing and developing the insulating member; and
A conductor line forming step of forming a conductor line on the surface of the insulating member by embedding a conductive material in the groove;
An insulating member installation step in which the insulating member on which the conductor line is formed is provided on the substrate so as to cover the piezoelectric element while providing a distance to the piezoelectric element;
A method for manufacturing a piezoelectric device comprising: Between the groove forming step and the conductor line forming step,
An upper mold member arranging step of arranging a photosensitive upper mold member on the surface of the insulating member having the groove;
A through groove forming step of forming a through groove in the upper mold member at a position corresponding to the groove by exposing and developing the upper mold member;
Further comprising
The conductor line forming step includes
Embedding a conductive material in the groove and the through groove;
Removing the upper mold member disposed on the insulating member;
The method for manufacturing a piezoelectric device according to claim 7, comprising:

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