Patent Application
20230317691
The present invention relates to an electronic device on which a functional element substrate provided with a functional element is mounted.
An electronic device on which a functional element substrate provided with a functional element, such as an integrated circuit, is mounted is provided with a heat sink and the like so that heat that is generated during driving from the functional element and wiring is dissipated to the outside. Specifically, the electronic device described in Japanese Unexamined Patent Application Publication No. 2004-165281 has a face-up structure in which a semiconductor chip (functional element substrate) is provided at a base substrate such that a main surface thereof at which a functional element and an electrode are disposed faces upward. Therefore, a terminal is led out to the outside from the electrode disposed at the main surface of the semiconductor chip by wire wiring, which increases the size of the chip. In the electronic device, the main surface side on which the functional element and the electrode are disposed is sealed with a mold resin, and a heat sink is provided at a back surface of the semiconductor chip opposite to the main surface.
It is possible in the electronic device in Japanese Unexamined Patent Application Publication No. 2004-165281, if the material of the semiconductor chip is silicon (Si), to transfer heat that is generated from the functional element on the main surface side of the semiconductor chip to the back surface of the semiconductor chip and dissipate the heat at the heat sink. The material of the semiconductor chip is, however, not limited to silicon and may be a compound semiconductor or the like. The thermal conductivity of compound semiconductors is lower than the thermal conductivity of silicon. Therefore, in the configuration described in Japanese Unexamined Patent Application Publication No. 2004-165281, there is a likelihood that the heat generated from the functional element is not sufficiently transferred to the base substrate from the main surface (first main surface) side of the semiconductor chip and deteriorates heat dissipation.
Thus, preferred embodiments of the present invention provide electronic devices each capable of improving heat dissipation by transferring heat to a base substrate from, of a functional element substrate including a first main surface provided with a functional element, the first main surface side.
An electronic device according to one aspect of a preferred embodiment of the present disclosure includes a functional element substrate including a first main surface provided with a functional element that is a piezoelectric substrate or a compound semiconductor substrate, a base substrate on which the functional element substrate is mounted such that a second main surface of the functional element substrate opposite to the first main surface faces the base substrate, a metal connection body that connects the second main surface of the functional element substrate and the base substrate to each other, a first metal body that is provided at the first main surface of the functional element substrate, the first metal body including at least a portion that extends to outside the functional element substrate in plan view from the first main surface, and a via that connects the portion of the first metal body outside the functional element substrate and the base substrate to each other, the via having a higher thermal conductivity than the functional element substrate.
According to one aspect of a preferred embodiment of the present disclosure, the portion of the first metal body outside the functional element is connected to the base substrate by the via having a higher thermal conductivity than the functional element substrate, and it is thus possible to improve heat dissipation by transferring heat to the base substrate from the first main surface side of the functional element substrate having the first main surface provided with the functional element.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
Hereinafter, electronic devices according to preferred embodiments will be described with reference to the drawings. In the following description, the same components are given the same signs. The names and functions of those components are also the same. Therefore, those components will not be described in detail repeatedly.
The functional elements 11 are each provided with an electrode 12 (functional element electrode). The substrate 10 is connected at the other main surface opposite to the one main surface provided with the electrodes 12 to the base substrate 20 by a metal connection body 30 (for example, solder, conductive paste, or the like). Preferably, the metal connection body 30 includes at least a portion extending to outside the substrate 10 in plan view from the one main surface. In other words, preferably, the metal connection body 30 extends from inside the substrate 10 to outside the substrate 10 in plan view from the one main surface. In the electronic device 100 illustrated in
When the functional elements 11 are operated by supplying electric power and a signal to the functional elements 11, heat is generated in the functional elements 11 and the electrodes 12 during operation. It is possible, if a material such as silicon (Si) having high thermal conductivity is used in the substrate 10, to transfer the heat generated in the functional elements 11 and the electrodes 12 to the base substrate 20 from the other main surface (second main surface) side of the substrate 10 through the substrate 10 and dissipate the heat. Incidentally, the thermal conductivity of silicon is about 160 W/(m·k) to about 200 W/(m·k), for example.
The substrate 10 is, however, a piezoelectric substrate or a compound semiconductor substrate. A material used in the piezoelectric substrate is, for example, crystal, LiTaO3, LiNbO3, KNbO3, La3Ga5SiO14, Li2B4O7, or the like, and a material used in the compound semiconductor substrate is GaAs, GaN, or the like. Any of the materials is a material that has lower thermal conductivity than silicon and the like, and there is a likelihood of the materials being not able to sufficiently transfer the heat generated in the functional elements 11 and the electrodes 12 to the base substrate 20 from the other main surface side of the substrate 10 through the substrate 10 and dissipate the heat. Incidentally, the thermal conductivity of LiTaO3 and LiNbO3 is about 3 W/(m·k) to about 5 W/(m·k), for example. The thermal conductivity of GaAs is about 55 W/(m·k), for example. The thermal conductivity of GaN is about 100 W/(m·k), for example.
Thus, the electronic device 100 according to Preferred Embodiment 1 includes a heat conduction path along which the heat that is generated in the functional elements 11 and the electrodes 12 is transferred to the base substrate 20. Specifically, the electronic device 100 is provided with a metal body 50 (first metal body) on the one main surface side of the substrate 10 where the functional elements 11 and the electrodes 12 are provided. At least a portion of the metal body 50 extends to outside the substrate 10 in plan view from the one main surface. In other words, preferably, the metal body 50 extends from inside the substrate 10 to outside the substrate 10 in plan view from the one main surface. The portion of the metal body 50 provided outside is located on both sides of opposing sides of the substrate 10 in plan view from the one main surface.
This portion of the metal body 50 outside the substrate 10 and the base substrate 20 are connected to each other by a via 60. In the metal body 50, for example, copper, aluminum (Al), or the like is used. In the via 60, for example, at least one of a copper-based conductive paste solidified material and a silver-based conductive paste solidified material that have higher thermal conductivity than the substrate 10 is used. While the via 60 illustrated in
As a result of the metal body 50 and the base substrate 20 being connected to each other by the via 60, a new heat conduction path along which the heat generated in the functional elements 11 and the electrodes 12 is transferred from the metal body 50 through the via 60 to the base substrate 20 can be ensured. Specifically, the new heat conduction path is a heat conduction path along which the heat that is generated in the functional elements 11 and the electrodes 12 is transferred to the metal body 50, the via 60, the metal connection body 30, and wiring or an electrode formed on the base substrate 20 in this order to be dissipated from the one main surface of the substrate 10 to the base substrate 20. Consequently, the electronic device 100 can improve heat dissipation to the base substrate 20 not only from the other main surface (second main surface) of the substrate 10 but also from the one main surface (first main surface) of the substrate 10.
It is preferable in the electronic device 100 that a cross-sectional area that is obtained by cutting the portion of the via 60 connected to the metal connection body 30 in a lateral direction orthogonal to the laminate direction of the metal connection body 30 and the via 60 be larger than at least one of cross-sectional areas obtained by cutting each of a plurality of the metal connection bodies 30 in the lateral direction. By increasing the cross-sectional area of the via 60, it is possible to ensure a large heat conduction path along which heat is transferred from the metal body 50 to the via 60 and reaches the metal connection body 30 and the base substrate 20 and possible to further improve the heat dissipation from the one main surface of the substrate 10.
As illustrated in
The electronic device 100 illustrated in
Regarding the electronic device 100 illustrated in
In the electronic device 100A, a conductive film 13 having a higher thermal conductivity than the substrate 10 is formed in a recess 10a that is formed by recessing the other main surface of the substrate 10. On the substrate 10, the recess 10a is recessed toward the functional elements 11. In other words, the recess 10a is an opening portion that is open at the substrate 10 to the metal connection body 30 side. The conductive film 13 is made of, for example, a multilayer structure that includes at least one of copper (Cu), gold (Au), tungsten (W), and nickel (Ni) or an alloy that includes at least one of copper (Cu), gold (Au), tungsten (W), and nickel (Ni). The conductive film 13 is in contact with the metal body 70. Therefore, due to the conductive film 13 provided in the recess 10a of the substrate 10, the electronic device 100A can further improve the heat dissipation from the other main surface of the substrate 10 to the base substrate 20. In plan view from the one main surface, the recess 10a is at least provided at a position on the substrate 10 where the recess 10a overlaps a region in which the functional elements 11 or the electrodes 12 are provided.
As described above, the electronic devices 100 and 100A according to Preferred Embodiment 1 each include the substrate 10, the base substrate 20, the metal connection body 30, the metal body 50, and the via 60. The substrate 10 includes the one main surface provided with the functional elements 11 and is a piezoelectric substrate or a compound semiconductor substrate. The substrate 10 is mounted on the base substrate 20 such that the other main surface of the substrate 10 opposite to the one main surface faces the base substrate 20. The metal connection body 30 connects the other main surface of the substrate 10 and the base substrate 20 to each other. The metal body 50 is provided at the one main surface of the substrate 10 and includes at least a portion extending to outside the substrate 10 in plan view from the one main surface. The via 60 connects the portion of the metal body 50 outside the substrate 10 and the base substrate 20 to each other and has higher thermal conductivity than the substrate 10.
Consequently, each of the electronic devices 100 and 100A according to Preferred Embodiment 1 can improve heat dissipation from the one main surface of the substrate 10 to the base substrate 20 since the metal body 50 including at least a portion extending to outside the substrate 10 in plan view from the one main surface and the base substrate 20 are connected to each other by the via having a higher thermal conductivity than the substrate 10.
Preferably, the metal body 50 extends across the substrate 10 in plan view from the one main surface such that a portion of the metal body 50 outside the substrate 10 is located on both sides of opposing sides of the substrate 10 in plan view from the one main surface, and the portion of the metal body 50 on both sides is connected to the base substrate 20 with the via 60 interposed therebetween. Consequently, each of the electronic devices 100 and 100A can ensure a large path of heat conduction from the one main surface side of the substrate 10 to the base substrate 20 side.
Preferably, the metal connection body 30 extends from inside the substrate 10 in plan view from the one main surface to outside the substrate 10. Consequently, each of the electronic devices 100 and 100A can ensure a large path of heat conduction from the one main surface side of the substrate 10 to the base substrate 20 side.
Preferably, the metal body 70 is further provided between the other main surface of the substrate 10 and the metal connection body 30. Consequently, connection between the other main surface of the substrate 10 and the metal connection body 30 is eased. Further, the metal body 70 is preferably provided to extend from inside the substrate 10 in plan view from the one main surface to outside the substrate 10.
Preferably, the recess 10a is provided on the other main surface of the substrate 10, the conductive film 13 having a higher thermal conductivity than the substrate 10 is formed in the recess 10a, and the conductive film 13 is in contact with the metal connection body 30. Consequently, the electronic device 100A can further improve the heat dissipation from the other main surface of the substrate 10.
Preferably, the insulator 80 that covers the side surface of the substrate 10 is further included. Consequently, each of the electronic device 100 and 100A can ensure electrical insulation from the side surface of the substrate 10.
Regarding each of the electronic devices 100 and 100A according to Preferred Embodiment 1, a configuration in which the other main surface of the substrate 10 is connected to the base substrate 20 with the metal body 70 and the metal connection body 30 interposed therebetween has been described. Regarding an electronic device according to Preferred Embodiment 2, a configuration in which a support body is provided at the other main surface of the substrate will be described.
Specifically, the material used in the support body 40 is a conductive paste solidified material or the like based on silicon (Si), silicon carbide (SiC), aluminum oxide (for example, Al2O3), boron nitride (BN), aluminum nitride (AlN), silicon nitride, copper (Cu), nickel (Ni), or silver (Ag). Incidentally, the thermal conductivity of copper is about 300 W/(m·k) to about 400 W/(m·k), for example. The thermal conductivity of silicon carbide is about 200 W/(m·k), for example. The thermal conductivity of boron nitride is about 150 W/(m·k) to about 200 W/(m·k), for example. The thermal conductivity of aluminum nitride is about 150 W/(m·k) to about 180 W/(m·k), for example.
The thickness of the substrate 10 can be reduced by providing the support body 40. By combining the substrate 10 and the support body 40 to form a substrate having a predetermined thickness, the thickness of the substrate 10 is reduced to thereby, while maintaining the characteristics of the substrate 10, reduce a portion having low thermal conductivity and to increase the thickness of the support body 40 to thereby increase a portion having high thermal conductivity. Consequently, the heat generated in the functional elements 11 and the electrodes 12 is transferred from the support body 40 side to the base substrate 20 efficiently, which improves heat dissipation.
Regarding the electronic device 200 illustrated in
In the electronic device 200A, a conductive film 41 having a higher thermal conductivity than the support body 40 is formed in a recess 40a that is formed by recessing the surface of the support body 40 opposite to the surface thereof in contact with the substrate 10. On the support body 40, the recess 40a is recessed toward the functional elements 11. In other words, the recess 40a is an opening portion that is open at the support body 40 to the metal connection body 30 side. The conductive film 41 is made of a multilayer structure that includes at least one of, for example, copper (Cu), gold (Au), tungsten (W), and nickel (Ni) or an alloy that includes at least one of copper (Cu), gold (Au), tungsten (W), and nickel (Ni). The conductive film 41 is in contact with the metal body 70. Therefore, due to the conductive film 41 provided in the recess 40a of the support body 40, the electronic device 200A can further improve the heat dissipation from the other main surface of the substrate 10. In plan view from the one main surface, the recess 40a is at least provided at a position on the substrate 10 where the recess 40a overlaps a region in which the functional elements 11 or the electrodes 12 are provided. Alternatively, the support body 40 may be provided with, instead of the recess 40a, a through hole that extends through the support body 40 and reaches the other main surface of the substrate 10.
As described above, each of the electronic devices 200 and 200A according to Preferred Embodiment 2 further includes the support body 40 provided at the other main surface of the substrate 10 and having a higher thermal conductivity than the substrate 10, and the metal connection body 30 connects the other main surface of the substrate 10 to the base substrate 20 with the support body 40 interposed therebetween. Consequently, due to the provision of the support body 40 having a higher thermal conductivity than the substrate 10, each of the electronic devices 200 and 200A according to Preferred Embodiment 2 can improve the heat dissipation from the other main surface of the substrate 10.
Preferably, the support body 40 has the recess 40a or a through hole in a surface that is opposite to a surface close to the substrate 10, the conductive film 41 having a higher thermal conductivity than the support body 40 is formed in the recess or the through hole, and the conductive film 41 is in contact with the metal connection body 30. Consequently, the electronic device 200A can further improve the heat dissipation from the other main surface of the substrate 10. When the metal body 70 is provided, the conductive film 41 is in contact with the metal connection body 30 with the metal body 70 interposed therebetween.
Preferably, the support body 40 includes at least one of a mixture of a metal and a resin, silicon, silicon carbide, aluminum oxide, boron nitride, aluminum nitride, silicon nitride, copper, and nickel.
Preferably, the insulator 80 that covers a side surface of the substrate 10 and a side surface of the support body 40 is further included. Here, the side surface of the support body 40 is a surface that connects a surface of the support body 40 close to the substrate 10 and a surface of the support body 40 opposite to the surface close to the substrate 10 to each other. Consequently, each of the electronic devices 200 and 200A can ensure electrical insulation from the side surfaces of the substrate 10 and the support body 40.
Regarding the electronic devices 100 and 100A according to Preferred Embodiment 1 and the electronic devices 200 and 200A according to Preferred Embodiment 2, a configuration in which the metal body 50 is provided at the one main surface of the substrate 10 has been described. Regarding an electronic device according to Preferred Embodiment 3, a configuration in which an electronic component is mounted on a surface of a metal body on a side opposite to a side that is in contact with a substrate will be described.
In the electronic device 300 illustrated in
Next, a method of manufacturing the electronic device 300 will be described. The manufacture method up to mounting of the electronic component 90 on a surface of the metal body 50 is the same as a method of manufacturing the electronic device 200 illustrated in
First, a method of manufacturing the substrate 10 provided with the functional elements 11 will be described.
Next, the via 60 is formed at a predetermined position on a temporary substrate. The via 60 is formed on the temporary substrate by a semi-additive method or the like. By forming the via 60 by the semi-additive method, it is possible to form the via 60 that is substantially perpendicular and substantially rectangular and that has a high aspect ratio. It is thus possible to reduce or minimize the positional displacement of the via 60 in plan view from the support body 40. In order to improve heat dissipation from the other main surface of the substrate 10, it is preferable to increase the cross-sectional area of the via 60 within a range in which the via 60 does not affect the electrical characteristics of the functional elements 11.
On the temporary substrate in which the via 60 is formed at a predetermined position, the substrate 10 is positioned such that the one main surface faces the temporary substrate. The substrate 10 and the via 60 on the temporary substrate are covered by an insulator, and the thicknesses of the support body 40, the via 60, and the insulator are each reduced to a desired thickness.
Next, the temporary substrate 25 is removed from the substrate 10, and the metal bodies 50 and 70 are formed at one main surface of the substrate 10 and a surface of the support body 40 on a side opposite to a side that is in contact with the substrate 10, respectively.
The metal body 70 is formed by a semi-additive method, and a metal pattern or the like for connection to wiring provided at the base substrate 20 is patterned on the metal body 70. The material of the metal body 70 is preferably a metal film including copper mainly. On the metal body 70, an under-bump metal layer, an electrically insulating layer, and the like are formed for solder connection, and a mounting pad for connecting the base substrate 20 and the substrate 10 to each other by solder is formed. Patterning of the metal body 70 is formed to extend from the substrate 10 to the region of the insulator 80. In other words, the metal body 70 extends to the metal connection body 30 outside the substrate 10 in plan view from the support body 40. Consequently, the path of heat conduction to the base substrate 20 can be widened.
In addition, the metal body 50 is formed by a semi-additive method, and, as illustrated in
Next, at the terminal pads 51 and 52 on the metal body 50, an under-bump metal layer is formed for solder connection, and the electronic component 90 is mounted on the lower side of the metal body 50 in
Next, an under-bump metal layer is formed at, of the metal body 70, a portion that is to be connected to the metal connection body 30. On the formed under-bump metal layer, the metal connection body 30, which is a terminal for connection to the base substrate 20, is formed. At this time, patterning of the metal connection body 30 is formed to extend from the substrate 10 to the region of the insulator 80. In other words, a portion of the metal connection body 30 extends to outside the substrate 10. Consequently, the path of heat conduction to the base substrate 20 can be widened. In particular, the metal connection body 30 is generally made of solder or a conductive paste and tends to have low thermal conductivity and hinder the heat conduction. Thus, by increasing the size of the portion of the metal connection body 30 connected to the metal body 70, the heat dissipation can be improved.
Next, the substrate 10 on which the metal connection body 30 is formed is connected to a wiring layer on the base substrate 20, and the substrate 10 is mounted on the base substrate 20. A sectional view in which the substrate 10 is mounted on the base substrate 20 is illustrated in
Further, one example in which the functional elements 11 provided at the substrate 10 are surface acoustic wave elements will be described.
It is required when the functional elements 11 are surface acoustic wave elements to ensure operation of a plurality of comb electrodes (IDT electrodes) and the like by providing a hollow portion at the side provided with the functional elements 11. Therefore, in the electronic device 300A, as illustrated in
As described above, each of the electronic devices 300 and 300A according to Preferred Embodiment 3 further includes the electronic component 90 that is mounted on a surface of the metal body 50 opposite to the surface thereof close to the substrate 10. Consequently, the electronic devices 300 and 300A can realize devices that have various configurations while improving the heat dissipation from one main surface of the substrate 10. The cross-sectional area of the via 60 is preferably larger than the cross-sectional area of a portion (for example, a portion (bump 92) at which the electronic component 90 is electrically connected) of the electronic component 90 at which the electronic component 90 is mounted on a surface of the metal body. Consequently, the path of heat conduction to the base substrate 20 can be widened.
Regarding the electronic devices 200 and 200A according to Preferred Embodiment 2, a configuration in which the support body 40 is provided at the substrate 10 has been described. Regarding an electronic device according to Preferred Embodiment 4, an example in which a component other than the support body 40 is provided at the other main surface of the substrate 10 will be described. The configuration, in which the electronic component 90 is mounted on a surface of the metal body 50, described in Preferred Embodiment 3 may be applied to the electronic device according to Preferred Embodiment 4.
In the electronic device 400A, an insertion layer 42 is provided between the substrate 10 and the support body 40. The insertion layer 42 has higher thermal conductivity than the substrate 10 and the support body 40. Therefore, heat dissipation from the other main surface of the substrate 10 can be further improved. The insertion layer 42 may be provided, instead of at the entire surface between the substrate 10 and the support body 40, only at a portion that includes a region of the substrate 10 where the functional elements 11 and the electrodes 12 are provided in plan view from the support body 40. As a material of the highly thermally conductive insertion layer 42, a metal material including copper mainly or the like is preferably selected.
In the electronic device 400B, an intermediate layer 43 is provided between the substrate 10 and the support body 40 so as to be in contact with the substrate 10. The intermediate layer 43 has a coefficient of linear expansion that is between the coefficient of linear expansion of the substrate 10 and the coefficient of linear expansion of the support body 40. Therefore, a compressive stress can be applied by the intermediate layer 43 to the substrate 10 at the time of a temperature increase. In particular, when the substrate 10 is a crystalline substrate, the compressive stress of the intermediate layer 43 can reduce or prevent generation of cracking of the substrate 10 due to a tensile stress being applied to the substrate 10 at the time of a temperature increase. As the intermediate layer 43, a material that includes copper (Cu), gold (Au), platinum (Pt), titanium (Ti), tantalum (Ta), tungsten (W), or the like can be used. In addition, an intermediate layer that is made of a material having a coefficient of linear expansion smaller than the coefficients of linear expansion of the support body 40 and the substrate 10 may be provided on the support body 40.
The electronic device 400C is one example applied to a surface acoustic wave device, the substrate 10 is constituted by a piezoelectric substrate, and the support body defines and functions as a high-acoustic-velocity support substrate 45 through which bulk waves propagate at a higher acoustic velocity than acoustic waves, such as surface acoustic waves and boundary waves, propagating through the piezoelectric substrate. In addition, the electronic device 400C is further provided with a low-acoustic-velocity film 46 between the substrate 10 and the high-acoustic-velocity support substrate 45 and through which bulk waves propagate at a lower acoustic velocity than acoustic waves that propagate through the piezoelectric substrate. In other words, the electronic device 400C has a multilayer structure in which the substrate 10, the low-acoustic-velocity film 46, and the high-acoustic-velocity support substrate 45 are laminated in this order.
The substrate 10 includes, for example, a 50° Y-cut X-propagation LiTaO3 piezoelectric single crystal or piezoelectric ceramics (a lithium tantalate single crystal or ceramics cut along a plane that has, as a normal line, an axis rotated by 50° from the Y-axis with the X-axis as the center axis and through which acoustic waves propagate in the X-axis direction). For example, when a wavelength determined by an electrode finger pitch of IDT electrodes, which are the functional elements 11, is λ, the thickness of the substrate 10 is less than or equal to about 3.5λ.
The high-acoustic-velocity support substrate 45 is a substrate that supports the low-acoustic-velocity film 46 and the substrate 10 provided with the functional elements 11. The high-acoustic-velocity support substrate 45 is also a substrate in which the acoustic velocity of bulk waves in the high-acoustic-velocity support substrate 45 is higher than the acoustic velocity of acoustic waves, such as surface acoustic waves and boundary waves, propagating through the substrate 10, and the high-acoustic-velocity support substrate 45 functions to confine acoustic waves in a portion where the substrate 10 and the low-acoustic-velocity film 46 are laminated so as not to leak upward in
The low-acoustic-velocity film 46 is a film in which the acoustic velocity of bulk waves in the low-acoustic-velocity film 46 is lower than the acoustic velocity of acoustic waves propagating through the substrate 10 and is disposed between the substrate 10 and the high-acoustic-velocity support substrate 45. This structure and a property of acoustic waves that energy thereof basically concentrates in a medium in which acoustic velocity is low suppress leaking of acoustic wave energy to the outside of the IDT electrodes as the functional elements 11. The thickness of the low-acoustic-velocity film 46 is, for example, about 670 nm. With this multilayer structure, the Q-value at a resonant frequency and an anti-resonant frequency can be significantly increased compared with a structure in which the piezoelectric substrate is used as a single layer. In other words, since a surface acoustic wave resonator having a high Q-value can be configured, it is possible to configure a filter in which an insertion loss is small by using the acoustic wave resonator.
As a material of the high-acoustic-velocity support substrate 45, a piezoelectric, such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon, sapphire, lithium tantalate, lithium niobate, or crystal, ceramics such as alumina, zirconia, cordierite, mullite, steatite, or forsterite, magnesia diamond, a material including one of the aforementioned materials as a main component, or a material including a mixture of the aforementioned materials can be used.
The low-acoustic-velocity film 46 is made of, for example, a material including, as a main component, glass, silicon oxynitride, tantalum oxide, or a compound in which fluorine, carbon, or boron is added to silicon oxide. The material of the low-acoustic-velocity film 46 is at least a material having a relatively low acoustic velocity.
The high-acoustic-velocity support substrate 45 may have a structure in which a support body and a high-acoustic film through which bulk waves propagate at a higher acoustic velocity than acoustic waves, such as surface acoustic wave and boundary waves, propagating through the substrate 10 are laminated. In this case, in the support body, a piezoelectric such as sapphire, lithium tantalate, lithium niobate, or crystal, various types of ceramics such as alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, or forsterite, a dielectric such as glass, a semiconductor such as silicon or gallium nitride, a resin substrate, or the like can be used. In the high-acoustic film, a variety of high-acoustic-velocity materials including aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, a DLC film, diamond, a medium including one of the aforementioned materials as a main component, and a medium including a mixture of the aforementioned materials as a main component can be used.
As described above, the electronic device 400A according to Preferred Embodiment 4 further includes, between the support body 40 and the substrate 10, the insertion layer 42 that has higher thermal conductivity than the substrate 10 and the support body 40. Consequently, it is possible to further improve the heat dissipation from the other main surface of the substrate 10.
In addition, the electronic device 400B according to Preferred Embodiment 4 further includes, between the substrate 10 and the support body 40, the intermediate layer 43 that is provided in contact with the substrate 10 and that has a coefficient of linear expansion that is between the coefficient of linear expansion of the substrate 10 and the coefficient of linear expansion of the support body 40. Consequently, a compressive stress can be applied by the intermediate layer 43 to the substrate 10 at the time of a temperature increase.
Further, in the electronic device 400C according to Preferred Embodiment 4, the substrate is a piezoelectric substrate, the support body 40 is the high-acoustic-velocity support substrate 45 through which bulk waves propagate at a higher acoustic velocity than acoustic waves, such as surface acoustic waves and boundary waves, propagating through the piezoelectric substrate, and the electronic device 400C further includes the low-acoustic-velocity film 46 provided between the substrate 10 and the high-acoustic-velocity support substrate 45 and through which bulk wave propagate at a lower acoustic velocity than acoustic waves that propagate through the substrate 10. Consequently, it is possible to confine acoustic waves in a portion where the substrate 10 and the low-acoustic-velocity film 46 are laminated so as not to leak upward from the high-acoustic-velocity support substrate 45.
The configurations of the electronic devices 400A to 400C described in Preferred Embodiment 4 may be combined together, as appropriate.
In the electronic device 500, the support body 40 has a surface roughness that is larger on a surface close to the metal body 70 than on a surface close to the substrate 10. In other words, the surface roughness 40b of the surface of the support body 40 close to the metal body 70 is larger than the surface roughness of the surface thereof close to the substrate 10. Consequently, a contact area between the support body 40 and the metal body 70 is increased. It is thus possible to improve heat dissipation to the metal body 70.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-000078 | Jan 2021 | JP | national |
This application claims the benefit of priority to Japanese Patent Application No. 2021-000078 filed on Jan. 4, 2021 and is a Continuation application of PCT Application No. PCT/JP2021/045551 filed on Dec. 10, 2021. The entire contents of each application are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2021/045551 | Dec 2021 | US |
| Child | 18207699 | US |
