JP2021034746A - Electronic device and method of manufacturing the same, filter, and multiplexer - Google Patents

Abstract

To achieve miniaturization.SOLUTION: An electronic device comprises: a single support substrate 10 that has a first surface and a second surface opposed to the first surface; a function element provided on the first surface of the support substrate; a first metal layer 16a conductively connected with the function element, buried in the support substrate, exposed to the first surface side, and formed so that its width becomes narrower from the first surface to the second surface; and a second metal layer 16b overlapped with the first metal layer in a plan view, being in contact with the first metal layer in the support substrate, buried in the support substrate, exposed to the second surface, and formed so as to have a minimum cross sectional area in the plan view larger than a cross sectional area of the first metal layer at a contact surface with the first metal layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electronic device and its manufacturing method, a filter and a multiplexer, for example, an electronic device having a wiring penetrating a substrate and a manufacturing method thereof, a filter and a multiplexer.

There are known elastic wave devices that use a composite substrate in which a piezoelectric substrate is bonded to the upper surface of a support substrate (for example, Patent Documents 1 to 3). A first through hole that penetrates the piezoelectric substrate is formed from the upper surface of the composite substrate, a first connection electrode is formed in the first through hole, and a second through hole that penetrates the support substrate from the lower surface of the composite substrate. It is known to form a second connection electrode connected to the first connection electrode in the second through hole (for example, Patent Document 3).

JP-A-2017-157922 JP-A-2017-169139 Japanese Unexamined Patent Publication No. 2011-130385

When a through hole is formed in the support substrate, the through hole has a shape in which the width becomes narrower toward the tip. Therefore, if the cross section of the through hole on one surface of the support substrate is a desired area, the cross section of the through hole on the other surface of the support substrate becomes large. Therefore, the size of the elastic wave device becomes large.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the size.

The present invention is between a single support substrate having a first surface and a second surface facing the first surface, a functional element provided on the first surface of the support substrate, and the functional element. Is conductively connected, is embedded in the support substrate, is exposed to the first surface side, and the width becomes narrower from the first surface toward the second surface, and the first metal layer in a plan view. On the contact surface that overlaps with the metal layer, is in contact with the first metal layer in the support substrate, is embedded in the support substrate, is exposed to the second surface, and has the smallest cross-sectional area in plan view in contact with the first metal layer. An electronic device including a second metal layer larger than the cross-sectional area of the first metal layer.

In the above configuration, it has a third surface provided with the functional element and a fourth surface facing the third surface, and the fourth surface is directly or indirectly joined to the first surface of the support substrate. The functional element is provided with a piezoelectric substrate and a wiring that electrically connects the functional element and the first metal layer through a hole that overlaps with the first metal layer and penetrates the piezoelectric substrate in a plan view. Can be configured to be a piezoelectric element.

In the above configuration, the contact surface may be located below the center in the thickness direction of the support substrate.

In the above configuration, the wiring is provided in a third metal layer embedded in the hole and having a surface substantially flat with the third surface, and provided on the surface of the first metal layer and the third surface to connect to the functional element. It can be configured to include a fourth metal layer.

In the above configuration, the functional element may be a piezoelectric thin film resonator provided on the first surface.

In the above configuration, it is possible to have a configuration in which terminals are provided on the second surface, which overlaps with the second metal layer and is in contact with the second metal layer in a plan view.

In the above configuration, the width of the second metal layer can be narrowed from the second surface toward the first surface.

In the above configuration, the support substrate may be a sapphire substrate, a spinel substrate, a quartz substrate, or a crystal substrate.

The present invention is a filter including the above electronic device.

The present invention is a multiplexer including the above filter.

In the present invention, a single support substrate having a first surface and a second surface facing the first surface and having a functional element provided on the first surface penetrates the support substrate from the first surface. A step of forming a first hole whose width becomes narrower from the first surface toward the second surface, a step of forming a first metal layer embedded in the first hole, and a step of forming the second surface. A step of polishing or grinding so that the first metal layer is not exposed, a step of forming a second hole reaching the first metal layer from the second surface after the step of polishing or grinding, and the second step. A method for manufacturing an electronic device, comprising a step of forming a second metal layer embedded in a hole and having a minimum cross-sectional area in plan view larger than the cross-sectional area of the first metal layer on a contact surface in contact with the first metal layer. Is.

According to the present invention, the size can be reduced.

1 (a) and 1 (b) are a cross-sectional view and a plan view of the elastic wave device according to the first embodiment. FIG. 2A is a plan view of the elastic wave element in the first embodiment, and FIG. 2B is a cross-sectional view of the via wiring. FIG. 3 is a cross-sectional view of the elastic wave device according to the first modification of the first embodiment. 4 (a) to 4 (d) are cross-sectional views (No. 1) showing a method of manufacturing an elastic wave device according to a modification 1 of the first embodiment. 5 (a) to 5 (d) are cross-sectional views (No. 2) showing a method of manufacturing an elastic wave device according to a modification 1 of the first embodiment. 6 (a) to 6 (d) are cross-sectional views (No. 3) showing a method of manufacturing an elastic wave device according to a modification 1 of the first embodiment. 7 (a) to 7 (c) are cross-sectional views showing a manufacturing method in the vicinity of the via wiring in Comparative Example 1. 8 (a) to 8 (d) are cross-sectional views showing a manufacturing method in the vicinity of the via wiring in the first embodiment. 9 (a) and 9 (b) are cross-sectional views of the elastic wave device according to the modified examples 2 and 3 of the first embodiment. FIG. 10 (a) is a cross-sectional view of the elastic wave device according to the modified example 4 of the first embodiment, and FIG. 10 (b) is a cross-sectional view of the elastic wave element. FIG. 11 is a cross-sectional view of the elastic wave device according to the modified example 5 of the first embodiment. FIG. 12A is a circuit diagram of the filter according to the second embodiment, and FIG. 12B is a circuit diagram of the duplexer according to the first modification of the second embodiment.

Hereinafter, examples of the present invention will be described with reference to the drawings, using an elastic wave device as an example as an electronic device.

1 (a) and 1 (b) are a cross-sectional view and a plan view of the elastic wave device according to the first embodiment. FIG. 1B mainly shows the support substrate 10, the piezoelectric substrate 11, and the annular metal layer 30.

As shown in FIGS. 1A and 1B, the piezoelectric substrate 11 is bonded on the upper surface 51 of the support substrate 10. The support substrate 10 is, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, or a silicon substrate. The piezoelectric substrate 11 is, for example, a lithium tantalate substrate or a lithium niobate substrate. The coefficient of linear expansion of the support substrate 10 is smaller than that of the piezoelectric substrate 11.

An elastic wave element 12 and wiring 14 are provided on the upper surface 53 of the piezoelectric substrate 11. A hole 15c that penetrates the piezoelectric substrate 11 is provided. A metal layer 17 is embedded in the hole 15c. The upper surface of the metal layer 17 and the upper surface 53 of the piezoelectric substrate 11 are substantially flat. The wiring 14 comes into contact with the upper surface of the metal layer 17. A through hole 15 that penetrates the support substrate 10 is provided. The through hole 15 includes holes 15a and 15b. The via wiring 16 is embedded in the through hole 15. The via wiring 16 includes a metal layer 16a embedded in the hole 15a and a metal layer 16b embedded in the hole 15b.

The terminal 18 is provided on the lower surface 52 of the support substrate 10. The terminal 18 is a foot pad for connecting the elastic wave element 12 to the outside. The via wiring 16 and the metal layer 17 electrically connect the terminal 18 and the wiring 14. The wiring 14, the via wiring 16, the metal layer 17, and the terminal 18 are metal layers such as a copper layer, an aluminum layer, a platinum layer, a nickel layer, or a gold layer.

The piezoelectric substrate 11 is removed from the peripheral edge of the support substrate 10. An annular metal layer 30 is provided on the support substrate 10 so as to surround the piezoelectric substrate 11. An annular bonding layer 32 is provided on the annular metal layer 30. A lid 34 is provided on the annular bonding layer 32. The annular bonding layer 32 joins the annular metal layer 30 and the lid 34. The cyclic metal layer 30 is, for example, a nickel layer or a copper layer. The annular bonding layer 32 is a solder such as tin silver or tin silver copper. The lid 34 is, for example, a metal plate such as Kovar or an insulating plate such as a sapphire substrate. The elastic wave element 12 is sealed in the gap 26 by the annular metal layer 30, the annular bonding layer 32, and the lid 34.

FIG. 2A is a plan view of the elastic wave element in the first embodiment, and FIG. 2B is a cross-sectional view of the via wiring. As shown in FIG. 2A, the elastic wave element 12 is an elastic surface wave resonator. An IDT (Interdigital Transducer) 40 and a reflector 42 are formed on the piezoelectric substrate 11. The IDT 40 has a pair of comb-shaped electrodes 40a facing each other. The comb-shaped electrode 40a has a plurality of electrode fingers 40b and a bus bar 40c for connecting the plurality of electrode fingers 40b. Reflectors 42 are provided on both sides of the IDT 40. IDT40 excites surface acoustic waves on the piezoelectric substrate 11. The wavelength of the elastic wave is substantially equal to the pitch of the electrode fingers 40b of one comb-shaped electrode 40a of the pair of comb-shaped electrodes 40a. That is, the wavelength of the elastic wave is substantially equal to twice the pitch of the electrode fingers 40b of the pair of comb-shaped electrodes 40a. The IDT 40 and the reflector 42 are formed of, for example, an aluminum film, a copper film or a molybdenum film. A protective film or a temperature compensation film may be provided on the piezoelectric substrate 11 so as to cover the IDT 40 and the reflector 42.

As shown in FIG. 2B, the side surface of the metal layer 17 is tapered, and the cross section of the metal layer 17 becomes smaller from the upper surface 53 of the piezoelectric substrate 11 toward the upper surface 51 of the support substrate 10. The angle θ3 of the internal angle formed by the upper surface and the side surface of the metal layer 17 is an acute angle. As a result, the width D6 on the lower surface of the metal layer 17 is smaller than the width D5 on the upper surface of the metal layer 17.

The metal layer 16a is tapered, and its cross section becomes smaller from the upper surface 51 to the lower surface 52 of the support substrate 10. The angle θ1 of the internal angle formed by the upper surface and the side surface of the metal layer 16a is an acute angle. The width D2 on the lower surface of the metal layer 16a is smaller than the width D1 on the upper surface of the metal layer 16a. The side surface of the metal layer 16b is tapered, and the cross section of the metal layer 16b becomes smaller from the lower surface 52 to the upper surface 51 of the support substrate 10. The angle θ2 of the internal angle formed by the lower surface and the side surface of the metal layer 16b is an acute angle. The width D4 on the upper surface of the metal layer 16b is smaller than the width D3 on the lower surface of the metal layer 16b. The width D6 is larger than D1 and the width D4 is larger than D2.

The support substrate 10 and the piezoelectric substrate 11 are, for example, a sapphire substrate and a 42 ° rotated Y-cut X-propagated lithium tantalate substrate, respectively. The thickness T0 of the support substrate 10 is larger than the thickness T1 of the piezoelectric substrate 11. The thicknesses T0 and T1 of the support substrate 10 and the piezoelectric substrate 11 are, for example, 50 μm to 120 μm and 0.1 μm to 20 μm, respectively.

The metal layers 16a, 16b and 17 are, for example, copper layers. The height H2 of the metal layer 16b is smaller than, for example, the height H1 of the metal layer 16a, for example, 5 μm to 20 μm. The width D5 of the upper surface of the metal layer 17 is larger than the width D1 of the upper surface of the metal layer 16a, for example. The width D3 of the lower surface of the metal layer 16b is larger than the width D2 of the lower surface of the metal layer 16a, for example. The width D2 is preferably 10 μm or more because of the bondability and contactability between the metal layers 16a and 16b. The widths D1, D2 and D5 are, for example, 30 μm, 15 μm and 74 μm, respectively. The angle θ1 is, for example, 88 ° to 80 °. The angles θ2 and θ3 are, for example, 45 ° to 80 °, respectively.

[Modification 1 of Example 1]
FIG. 3 is a cross-sectional view of the elastic wave device according to the first modification of the first embodiment. As shown in FIG. 3, in the modified example 1 of the first embodiment, the metal layer 17 is not embedded in the hole 15c. The wiring 14 is provided on the side surface and the bottom surface of the hole 15c, and comes into contact with the metal layer 16a on the bottom surface. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

[Manufacturing method of modified example 1 of Example 1]
4 (a) to 6 (d) are cross-sectional views showing a method of manufacturing an elastic wave device according to a modification 1 of the first embodiment. As shown in FIG. 4A, the upper surface 51 of the support substrate 10 is irradiated with laser light to form a hole 15a. When the hole 15a is formed by irradiating the laser beam, the side surface of the hole 15a becomes tapered.

As shown in FIG. 4B, a seed layer 16c is formed on the inner surface of the hole 15a and the upper surface of the support substrate 10 by, for example, a sputtering method. A plating layer 16d is formed on the seed layer 16c by, for example, a plating method. The seed layer 16c and the plating layer 16d are made of the same metal material and are, for example, a copper layer. An adhesion layer such as a titanium layer may be provided between the seed layer 16c and the support substrate 10. The plating layer 16d and the seed layer 16c on the upper surface 51 are flattened by, for example, a CMP (Chemical Mechanical Polishing) method so that the upper surface 51 of the support substrate 10 is exposed. As a result, a metal layer 16a embedded in the hole 15a is formed from the seed layer 16c and the plating layer 16d. In the following drawings, the seed layer 16c and the plating layer 16d are not shown and are shown as a metal layer 16a.

As shown in FIG. 4C, the upper surface 51 of the support substrate 10 and the lower surface of the piezoelectric substrate 11 are joined at room temperature by using, for example, a surface activation method. The support substrate 10 and the piezoelectric substrate 11 may be directly bonded to each other via an amorphous layer having a diameter of several nm or the like. Further, for example, they may be indirectly bonded via an insulating layer such as aluminum oxide, silicon oxide, or silicon oxide to which fluorine is added. The upper surface 53 of the piezoelectric substrate 11 is flattened by, for example, the CMP method. As a result, the piezoelectric substrate 11 has a desired thickness. As shown in FIG. 4D, an elastic wave element 12 is formed on the upper surface 53 of the piezoelectric substrate 11 by, for example, a sputtering method or a vacuum vapor deposition method.

As shown in FIG. 5A, the holes 15c and the openings 15d penetrating the piezoelectric substrate 11 are formed by using, for example, a wet or dry etching method. At this time, the support substrate 10 is hardly etched. The hole 15c is formed so as to overlap the metal layer 16a, and the metal layer 16a is exposed from the hole 15c. The opening 15d is formed on the peripheral edge of the support substrate 10 so as to surround the elastic wave element 12. The sides of the holes 15c and the openings 15d are tapered.

As shown in FIG. 5B, wiring 14 is formed on the inner surface of the hole 15c and the upper surface 53 of the piezoelectric substrate 11 by using, for example, a sputtering method or a vacuum vapor deposition method. The wiring 14 electrically connects the elastic wave element 12 and the metal layer 16a. Since the side surface of the hole 15c is tapered, the wiring 14 does not break in the hole 15c.

As shown in FIG. 5C, the annular metal layer 30 and the annular bonding layer 32 are formed on the upper surface 51 of the support substrate 10 in the opening 15d by, for example, a plating method. As shown in FIG. 5D, the lid 34 is mounted on the annular bonding layer 32 and heated to bond the annular bonding layer 32 and the lid 34. As a result, the elastic wave element 12 is sealed in the gap 26.

As shown in FIG. 6A, the lower surface 52 of the support substrate 10 is, for example, polished or ground. As a result, the support substrate 10 is thinned. The metal layer 16a is not exposed from the lower surface 52.

As shown in FIG. 6B, a hole 15b is formed in the lower surface 52 of the support substrate 10 by, for example, a wet or dry etching method or a laser beam. The hole 15b is formed so as to overlap the metal layer 16a, and the metal layer 16a is exposed from the hole 15b. The side surface of the hole 15b is tapered.

As shown in FIG. 6C, a seed layer 16c is formed on the inner surface of the hole 15b and the lower surface of the support substrate 10 by, for example, a sputtering method. A plating layer 16d is formed under the seed layer 16c by using, for example, a plating method. The seed layer 16c and the plating layer 16d are made of the same metal material and are, for example, a copper layer. An adhesion layer such as a titanium layer may be provided between the seed layer 16c and the support substrate 10. The plating layer 16d and the seed layer 16c under the lower surface 52 are flattened by using, for example, the CMP method so that the lower surface 52 of the support substrate 10 is exposed. As a result, the metal layer 16b embedded in the hole 15b is formed from the seed layer 16c and the plating layer 16d. In the following drawings, the seed layer 16c and the plating layer 16d are not shown and are shown as a metal layer 16b.

As shown in FIG. 6D, terminals 18 are formed on the lower surface 52 of the support substrate 10 by using, for example, a sputtering method or a vacuum vapor deposition method. The terminal 18 is, for example, a titanium layer, a copper layer, a nickel layer, and a gold layer from the support substrate 10 side. The support substrate 10 and the lid 34 are cut using, for example, a dicing method. As described above, the elastic wave device according to the first modification of the first embodiment is manufactured.

7 (a) to 7 (c) are cross-sectional views showing a manufacturing method in the vicinity of the via wiring in Comparative Example 1. As shown in FIG. 7A, the thickness T0'of the support substrate 10 is, for example, 400 μm to 500 μm. The metal layer 17 is formed in the hole 15c of the piezoelectric substrate 11, and the metal layer 16a is formed in the hole 15a of the support substrate 10. The metal layer 16a does not penetrate the support substrate 10. The height H1'of the metal layer 16a is, for example, 125 μm. The width of the upper surface of the metal layer 16a is D1.

As shown in FIG. 7B, the lower surface 52 of the support substrate 10 is polished or ground. As a result, the thickness T0 of the support substrate 10 becomes about 75 μm. The metal layer 16a is exposed on the lower surface 52 of the support substrate 10. The width of the lower surface of the metal layer 16a is D2. As shown in FIG. 7C, a terminal 18 in contact with the metal layer 16a is formed on the lower surface 52 of the support substrate 10.

The cross section of the hole 15a becomes smaller from the upper surface 51 to the lower surface 52. This is because the hole 15a is formed from the upper surface 51. For example, when the hole 15a is formed by using laser light, the angle θ1 formed by the upper surface and the side surface of the metal layer 16a is 80 ° to 85 °. When the hole 15a is formed by the etching method, the angle θ1 becomes smaller. When the width D2 of the lower surface of the metal layer 16a becomes smaller, the bondability between the metal layer 16a and the terminal 18 decreases. Further, the contact resistance between the metal layer 16a and the terminal 18 becomes small. Therefore, the width D2 is preferably 10 μm or more, for example.

The thickness T0 of the support substrate 10 is required to be at least a desired thickness in order to suppress the warp of the support substrate 10 and / or secure the strength. For example, if the thickness T0 is 75 μm, the width D2 is 15 μm, and the angle θ1 is 84 °, the width D1 is 40 μm. The width D5 is larger than the width D2 and is, for example, 84 μm. In this way, the elastic wave device becomes large.

Further, in FIG. 7B, cracks 64 may be formed in the support substrate 10 in the vicinity of the metal layer 16a. This is because the support substrate 10 is hard and the metal layer 16a is soft.

8 (a) to 8 (d) are cross-sectional views showing a manufacturing method in the vicinity of the via wiring in the first embodiment. As shown in FIG. 8A, the thickness T0'of the support substrate 10 is, for example, 400 μm to 500 μm. The metal layer 17 is formed in the hole 15c of the piezoelectric substrate 11, and the metal layer 16a is formed in the hole 15a of the support substrate 10. The height H1 of the metal layer 16a is, for example, 65 μm. The width of the lower surface of the metal layer 16a is D2.

As shown in FIG. 8B, the lower surface 52 of the support substrate 10 is polished or ground. As a result, the thickness T0 ″ of the support substrate 10 becomes, for example, 76 μm. The metal layer 16a is not exposed on the lower surface 52 of the support substrate 10. As shown in FIG. 8C, a hole 15b is formed from the lower surface 52 of the support substrate 10. The height H2'of the hole 15b is, for example, 11 μm. A metal layer 16b'is formed on the inner surface of the hole 15b and under the lower surface 52 of the support substrate 10 by using, for example, a plating method.

As shown in FIG. 8D, the metal layer 16b'on the lower surface 52 of the support substrate 10 is polished or ground. As a result, the lower surface 52 of the support substrate 10 is exposed, and the metal layer 16b is embedded in the hole 15b. At this time, the lower surface 52 of the support substrate 10 is polished or ground, and the thickness T0 of the support substrate 10 is, for example, 75 μm, and the height H2 of the metal layer 16b is 10 μm. At this time, the lower surface 52 of the support substrate 10 may be hardly polished or ground. The via wiring 16 is formed from the metal layers 16a and 16b. A terminal 18 in contact with the metal layer 16b is formed on the lower surface 52 of the support substrate 10.

In Example 1, if the width D2 on the contact surface where the metal layers 16a and 16b are in contact is 15 μm, the height H1 is 65 μm, and the angle θ1 is 84 °, the width D1 is 30 μm. When the difference between the widths D1 and D5 is about the same as that of Comparative Example 1, the width D5 is 74 μm. As described above, the width D5 can be made smaller than that of Comparative Example 1, and the elastic wave device can be miniaturized. Since the width D3 of the metal layer 16b in contact with the terminal 18 can be made larger than that of Comparative Example 1, the bonding strength between the metal layer 16b and the terminal 18 can be increased, and the contact resistance between the metal layer 16b and the terminal 18 can be reduced.

In FIG. 8B, cracks 64 may be formed on the support substrate 10 in the vicinity of the metal layer 16a. By forming the hole 15b larger than the width D2 of the metal layer 16a as shown in FIG. 8C, the crack 64 of the support substrate 10 can be removed.

The interface between the support substrate 10 and the piezoelectric substrate 11 has the largest shear stress due to thermal stress. Therefore, as in Patent Document 3, if the interface between the thinnest via wiring and the metal layer is located near the interface between the support substrate 10 and the piezoelectric substrate 11, the metal layer may be peeled off due to shear stress. ..

In the first embodiment, the thinnest of the via wiring 16 and the contact surface where the metal layers 16a and 16b are joined are sufficiently separated from the interface between the support substrate 10 and the piezoelectric substrate 11. Therefore, peeling due to shear stress can be suppressed. The height H1 of the metal layer 16a is preferably equal to or higher than the height H2 of the metal layer 16b. As a result, peeling of the metal layers 16a and 16b due to shear stress can be suppressed. The height H1 is preferably twice or more, more preferably three times or more the height H2.

[Modification 2 of Example 1]
FIG. 9A is a cross-sectional view of the elastic wave device according to the second modification of the first embodiment. As shown in FIG. 9A, in the second modification of the first embodiment, the piezoelectric substrate 11 is indirectly bonded to the upper surface of the support substrate 10 via the bonding layer 13. The bonding layer 13 is an insulating film such as a silicon oxide film. The thickness of the bonding layer 13 is, for example, 1 μm. The piezoelectric substrate 11 is bonded at room temperature on the bonding layer 13. An aluminum oxide film having a thickness of several tens of nm may be provided between the bonding layer 13 and the piezoelectric substrate 11. A silicon nitride film may be provided between the bonding layer 13 and the support substrate 10. When the bonding layer 13 is an insulating film such as a silicon oxide film, a metal film such as a titanium film may be provided in the silicon oxide film. The titanium film joins silicon oxide films together. When a metal film such as a titanium film is provided, it is preferable that an insulating film such as a silicon oxide film is provided between the side surface of the hole 15c and the wiring 14. As a result, an electrical short circuit between the metal film and the wiring 14 can be suppressed. Other configurations are the same as those of the first modification of the first embodiment, and the description thereof will be omitted.

[Modification 3 of Example 1]
FIG. 9B is a cross-sectional view of the elastic wave device according to the third modification of the first embodiment. As shown in FIG. 9B, in the modified example 3 of the first embodiment, the metal layer 16b is not provided, and the terminal 18 is embedded in the hole 15b. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted. In the first and second modifications of the first embodiment, the terminal 18 may be embedded in the hole 15b.

[Modified Example 4 of Example 1]
FIG. 10 (a) is a cross-sectional view of the elastic wave device according to the modified example 4 of the first embodiment, and FIG. 10 (b) is a cross-sectional view of the elastic wave element. As shown in FIG. 10A, in the modified example 4 of the first embodiment, the piezoelectric substrate 11 is not bonded to the upper surface 51 of the support substrate 10. An elastic wave element 12 and wiring 14 are provided on the upper surface 51 of the support substrate 10. Other configurations are the same as those of the first embodiment and the first and second modifications thereof, and the description thereof will be omitted.

As shown in FIG. 10B, the elastic wave element 12 is a piezoelectric thin film resonator. A piezoelectric film 46 is provided on the support substrate 10. The lower electrode 44 and the upper electrode 48 are provided so as to sandwich the piezoelectric film 46. A gap 45 is formed between the lower electrode 44 and the support substrate 10. The region where the lower electrode 44 and the upper electrode 48 face each other with at least a part of the piezoelectric film 46 sandwiched is the resonance region 47. In the resonance region 47, the lower electrode 44 and the upper electrode 48 excite elastic waves in the thickness longitudinal vibration mode in the piezoelectric film 46. The support substrate 10 is, for example, a sapphire substrate, a spinel substrate, an alumina substrate, a glass substrate, a crystal substrate, or a silicon substrate. The lower electrode 44 and the upper electrode 48 are metal films such as a ruthenium film. The piezoelectric film 46 is, for example, an aluminum nitride film. An acoustic reflection film that reflects elastic waves may be provided instead of the gap 45.

In the modified example 4 of the first embodiment, the shear stress caused by the difference in the coefficient of linear expansion between the piezoelectric substrate 11 and the support substrate 10 described in the first embodiment is small. Therefore, the height of the metal layer 16a may be smaller than the height of the metal layer 16b.

[Modification 5 of Example 1]
FIG. 11 is a cross-sectional view of the elastic wave device according to the modified example 5 of the first embodiment. As shown in FIG. 11, in the modified example 5 of the first embodiment, the substrate 20 is mounted on the support substrate 10. The substrate 20 is, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, or a silicon substrate. An elastic wave element 22 and a wiring 24 are provided on the lower surface of the substrate 20. The wiring 24 is, for example, a metal layer such as a copper layer, an aluminum layer, a platinum layer, or a gold layer. The substrate 20 is flip-chip mounted (face-down mounted) on the piezoelectric substrate 11 via bumps 28. The bump 28 is, for example, a gold bump, a solder bump or a copper bump. The bump 28 joins the wires 14 and 24.

The annular metal layer 35 is embedded in the opening 15d on the peripheral edge of the support substrate 10. An annular metal layer 36 is provided on the annular metal layer 35. The cyclic metal layers 35 and 36 are, for example, a copper layer and a nickel layer, respectively. A sealing portion 37 is provided on the annular metal layer 36 so as to surround the substrate 20. The sealing portion 37 is, for example, a metal layer such as solder (tin silver, tin or tin silver copper) or an insulating layer such as resin. The sealing portion 37 is joined to the annular metal layer 36. A flat lid 38 is provided on the upper surface of the substrate 20 and the upper surface of the sealing portion 37. The lid 38 is a metal plate such as a Kovar plate or an insulating plate. A protective film 39 is provided so as to cover the lid 38 and the sealing portion 37. The protective film 39 is a metal film such as a nickel film or an insulating film.

The elastic wave element 12 faces the substrate 20 via the gap 26. The elastic wave element 22 faces the piezoelectric substrate 11 via the gap 26. The elastic wave elements 12 and 22 are sealed by a sealing portion 37, a support substrate 10, a substrate 20, and a lid 38. The bump 28 is surrounded by the void 26. The terminal 18 is electrically connected to the elastic wave element 12 via the via wiring 16 and the wiring 14, and is further electrically connected to the elastic wave element 22 via the bump 28 and the wiring 24. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

As in the modified example 5 of the first embodiment, the substrate 20 may be mounted on the support substrate 10 of the first embodiment and the modified examples 1 to 4. Although an example of a piezoelectric thin film resonator has been described as the surface acoustic wave element 22, the elastic wave element 22 may be an elastic surface wave resonator. Although the example of the elastic wave element 22 has been described as the functional element provided on the lower surface of the substrate 20, the functional element may be a passive element such as an inductor or a capacitor, an active element including a transistor, or a MEMS (Micro Electro Mechanical Systems) element. ..

According to the first embodiment and its modifications, the elastic wave element 12 (functional element) is provided on the upper surface 51 (first surface) of the single support substrate 10. The metal layer 16a or the terminal 18 (first metal layer) is conductively connected to the elastic wave element 12, embedded in the support substrate 10 and exposed to the upper surface 51 side, and from the upper surface 51 to the lower surface 52 (on the first surface). The width becomes narrower (for example, the cross section gradually becomes smaller) toward the facing second surface). The metal layer 16b (second metal layer) overlaps with the metal layer 16a in a plan view, is in contact with the metal layer 16a in the support substrate 10, is embedded in the support substrate 10, and is exposed from the lower surface 52. The minimum cross-sectional area of the metal layer 16b in a plan view is larger than the cross-sectional area of the metal layer 16a on the contact surface in contact with the metal layer 16a (or the terminal 18) and 16b.

As a manufacturing method, as shown in FIG. 4A, the width becomes narrower from the upper surface 51 (first surface) to the lower surface 52 (second surface) without penetrating the support substrate 10 (for example, the cross section is widened). A hole 15a (first hole) (which gradually becomes smaller) is formed. As shown in FIG. 4B, a metal layer 16a (first metal layer) to be embedded in the hole 15a is formed. As shown in FIG. 6A, the lower surface 52 is polished or ground so that the metal layer 16a is not exposed. As shown in FIG. 6B, a hole 15b (second hole) that reaches the metal layer 16a from the lower surface 52 is formed thereafter. As shown in FIG. 6C, a metal layer 16b (second metal layer) is formed which is embedded in the hole 15b and whose minimum cross-sectional area in a plan view is larger than the cross-sectional area of the metal layer 16a on the contact surface in contact with the metal layer 16a. To do.

In Comparative Example 1 of FIG. 7C, the cross section of the metal layer 16a is the smallest on the lower surface 52. When the thickness T0 of the support substrate 10 is set to a desired thickness, the size of the elastic wave device becomes large. In Example 1 and its modifications, as shown in FIG. 8D, the smallest cross section of the via wiring 16 is the cross section of the metal layer 16a on the surface where the metal layers 16a and 16b come into contact with each other. Thereby, even if the thickness T0 of the support substrate 10 is the same as that of Comparative Example 1, the elastic wave device can be miniaturized. Further, the crack 64 and the like of the support substrate 10 formed in the vicinity of the metal layer 16a of FIG. 7B of Comparative Example 1 can be removed by the holes 15b.

As in the first embodiment and the first to third and fifth modifications thereof, the elastic wave element 12 is provided on the upper surface 53 (third surface) of the piezoelectric substrate 11, and the lower surface (fourth surface facing the third surface) of the piezoelectric substrate 11 is provided. ) Is directly or indirectly bonded to the upper surface 51 of the support substrate 10. The wiring 14 and the metal layer 17 (or the wiring 14) are connected to the elastic wave element 12 and the metal layer 16a through a hole 15c that overlaps with the metal layer 16a in a plan view and penetrates the piezoelectric substrate 11. When the piezoelectric substrate 11 is bonded on the support substrate 10, when the metal layer is bonded at the interface between the support substrate 10 and the piezoelectric substrate 11 as in Patent Document 3, the metal layer is formed by the shear stress caused by the thermal stress. It may come off. In Example 1 and modifications 1 to 3 and 5 thereof, the metal layers 16a and 16b are joined in a single support substrate 10. As a result, the shear stress caused by the thermal stress of the support substrate 10 and the piezoelectric substrate 11 on the contact surface between the metal layers 16a and 16b is small. Therefore, peeling of the metal layers 16a and 16b can be suppressed.

The contact surfaces of the metal layers 16a and 16b are located below the center of the support substrate 10 in the thickness direction. As a result, the contact surface can be kept away from the interface between the support substrate 10 and the piezoelectric substrate 11. Therefore, the shear stress on the contact surface can be made smaller.

The metal layer 17 (third metal layer) is embedded in the holes 15c and has a substantially flat surface as the upper surface 53. The wiring 14 (fourth metal layer) is provided on the surface and the upper surface 53 of the metal layer 17 and is connected to the elastic wave element 12 (piezoelectric element). In such a structure, since the metal layer 17 is embedded in the holes 15c, the shear stress at the interface between the metal layers 17 and 16a becomes large. Since the smallest cross section is located in the support substrate 10, the shear stress at the contact surface between the metal layers 16a and 16b having a small cross section is reduced.

As in the modified example 4 of the first embodiment, the piezoelectric substrate 11 is not provided, and the elastic wave element 12 may be a piezoelectric thin film resonator provided on the upper surface 51 of the support substrate 10.

As in the first, second, fourth, and fifth modifications of the first embodiment, the terminal 18 is provided on the lower surface 52 so as to overlap the metal layer 16b and contact the metal layer 16b in a plan view. As a result, the cross section of the via wiring 16 at the interface between the via wiring 16 and the terminal 18 can be made larger than that of Comparative Example 1. Therefore, the joint strength between the via wiring 16 and the terminal 18 can be increased, and the contact resistance can be reduced.

The width of the metal layer 16b becomes narrower from the lower surface 52 toward the upper surface 51. As a result, the contact area between the metal layer 16b and the terminal 18 can be increased. In addition, cracks 64 and the like can be further removed.

The support substrate is a sapphire substrate, a spinel substrate, a quartz substrate or a crystal substrate. The sapphire substrate is a substrate containing a single crystal Al ₂ O ₃ as a main component. The spinel substrate is a substrate containing single crystal or polycrystalline MgAl ₂ O ₄ as a main component. The quartz substrate is _{a substrate containing amorphous SiO 2} as a main component. The crystal substrate is a substrate containing single crystal SiO ₂ as a main component. In this case, since the support substrate 10 is hard, there is a high possibility that a crack 64 is formed on the lower surface 52 of the support substrate 10 in FIG. 8B. Therefore, the crack 64 can be removed by providing the metal layer 16b.

In the first embodiment and its modifications, the elastic wave element 12 has been described as an example of the functional element, but the functional element may be a passive element such as an inductor or a capacitor, an active element including a transistor, a MEMS element, or the like.

Example 2 is an example of a filter and a duplexer. FIG. 12A is a circuit diagram of the filter according to the second embodiment. As shown in FIG. 12A, one or more series resonators S1 to S4 are connected in series between the input terminal Tin and the output terminal Tout. One or more parallel resonators P1 to P4 are connected in parallel between the input terminal Tin and the output terminal Tout. The filter of the second embodiment may be formed by the elastic wave element 12. The number of series resonators and parallel resonators can be set as appropriate. Although the ladder type filter has been described as an example of the filter, the filter may be a multiple mode type filter.

FIG. 12B is a circuit diagram of the duplexer according to the first modification of the second embodiment. As shown in FIG. 12B, a transmission filter 60 is connected between the common terminal Ant and the transmission terminal Tx. A reception filter 62 is connected between the common terminal Ant and the reception terminal Rx. The transmission filter 60 passes a signal in the transmission band among the high-frequency signals input from the transmission terminal Tx to the common terminal Ant as a transmission signal, and suppresses signals of other frequencies. The reception filter 62 passes a signal in the reception band among the high frequency signals input from the common terminal Ant to the reception terminal Rx as a reception signal, and suppresses signals of other frequencies. At least one of the transmission filter 60 and the reception filter 62 can be the filter of the second embodiment. Further, the transmission filter 60 may be formed by the elastic wave element 12, and the reception filter 62 may be formed by the elastic wave element 22.

Although the duplexer has been described as an example as the multiplexer, a triplexer or a quadplexer may be used.

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

10 Support board 11 Piezoelectric board 12, 22 Elastic wave element 14, 24 Wiring 15a, 15b Hole 15c Hole 16 Via wiring 16a, 16b, 17 Metal layer 18 Terminal 20 Board 26 Void 30 Circular metal layer 32 Circular bonding layer 34 Lid 60 Transmission Filter 62 Receive filter 51, 53 Top surface 52 Bottom surface

Claims (11)

A single support substrate having a first surface and a second surface facing the first surface,
A functional element provided on the first surface of the support substrate and
A first metal layer that is conductively connected to the functional element, embedded in the support substrate, exposed to the first surface side, and narrowed in width from the first surface to the second surface.
It overlaps with the first metal layer in a plan view, is in contact with the first metal layer in the support substrate, is embedded in the support substrate and is exposed on the second surface, and the minimum cross-sectional area in the plan view is the first metal. A second metal layer larger than the cross-sectional area of the first metal layer on the contact surface in contact with the layer,
Electronic device with. A piezoelectric substrate having a third surface provided with the functional element and a fourth surface facing the third surface, and the fourth surface is directly or indirectly bonded to the first surface of the support substrate. ,
A wiring that electrically connects the functional element and the first metal layer through a hole that overlaps with the first metal layer and penetrates the piezoelectric substrate in a plan view is provided.
The electronic device according to claim 1, wherein the functional element is a piezoelectric element. The electronic device according to claim 2, wherein the contact surface is located below the center in the thickness direction of the support substrate. The wiring includes a third metal layer embedded in the hole and having a surface substantially flat with the third surface, and a fourth metal layer provided on the surface of the first metal layer and the third surface and connected to the functional element. The electronic device according to claim 2 or 3, wherein the electronic device comprises. The electronic device according to claim 1, wherein the functional element is a piezoelectric thin film resonator provided on the first surface. The electronic device according to any one of claims 1 to 5, which is provided with a terminal which overlaps with the second metal layer in a plan view and is in contact with the second metal layer and is provided on the second surface. The electronic device according to any one of claims 1 to 6, wherein the width of the second metal layer becomes narrower from the second surface toward the first surface. The electronic device according to any one of claims 1 to 7, wherein the support substrate is a sapphire substrate, a spinel substrate, a quartz substrate, or a crystal substrate. A filter comprising the electronic device according to any one of claims 1 to 8. A multiplexer containing the filter according to claim 9. The first surface does not penetrate the support substrate from the first surface to a single support substrate having a first surface and a second surface facing the first surface and a functional element is provided on the first surface. A step of forming a first hole whose width becomes narrower from the first surface toward the second surface, and
The step of forming the first metal layer to be embedded in the first hole and
A step of polishing or grinding the second surface so that the first metal layer is not exposed, and
After the polishing or grinding step, a step of forming a second hole reaching the first metal layer from the second surface and a step of forming the second hole.
A step of forming a second metal layer embedded in the second hole and having a minimum cross-sectional area in a plan view larger than the cross-sectional area of the first metal layer on a contact surface in contact with the first metal layer.
A method of manufacturing an electronic device including.

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