Patent Publication Number: US-2022216302-A1

Title: Electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 63/134,186, filed on Jan. 6, 2021 and Chinese application no. 202111284065.X, filed on Nov. 1, 2021. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to an electronic device. 
     Description of Related Art 
     Among electronic devices, a radio frequency (RF) device is employed to transmit or receive electromagnetic waves, and is thus an indispensable part of wireless communication technology. How to improve directivity of the radio frequency device so that the electromagnetic wave propagates in a specific direction is one of research and development focuses for researchers in the related field. 
     SUMMARY 
     The disclosure provides an electronic device, in which improvement to directivity of a radio frequency device can be facilitated. 
     According to an embodiment of the disclosure, an electronic device includes a substrate, a first electrode, a second electrode, a modulation element, a first solder, and a switch element. The first electrode is disposed on the substrate. The second electrode is disposed on the substrate. The modulation element is disposed on the substrate and includes at least two connecting pads. The first solder is disposed between the first electrode and one connecting pad of the modulation element. The switch element is disposed on the substrate. The one connecting pad of the modulation element is electrically connected to the switch element sequentially through the first solder, the first electrode, and the second electrode. 
     To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1A  and  FIG. 1B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a first embodiment of the disclosure. 
         FIG. 2A  and  FIG. 2B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a second embodiment of the disclosure. 
         FIG. 3A  and  FIG. 3B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a third embodiment of the disclosure. 
         FIG. 4A  and  FIG. 4B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a fourth embodiment of the disclosure. 
         FIG. 5A  and  FIG. 5B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a fifth embodiment of the disclosure. 
         FIG. 6A  and  FIG. 6B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a sixth embodiment of the disclosure. 
         FIG. 7  to  FIG. 9  are schematic partial cross-sectional views of manufacturing process flows of the electronic device according to the first embodiment of the disclosure. 
         FIG. 10  to  FIG. 13  are schematic partial cross-sectional views of manufacturing process flows of the electronic device according to the second embodiment of the disclosure. 
         FIG. 14  and  FIG. 15  are respectively schematic partial cross-sectional views of an electronic device according to a seventh embodiment and an eighth embodiment of the disclosure. 
         FIG. 16A  to  FIG. 16D  are schematic partial views of manufacturing process flows of an electronic device according to a ninth embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The disclosure may be understood with reference to the following detailed description and the accompanying drawings. It should be noted that, for ease of understanding by readers and simplicity of the drawings, the multiple drawings in the disclosure show only a part of an electronic device/display device, and specific elements in the drawings are not drawn to actual scale. In addition, the number and size of each element in the figures only serve for exemplifying instead of limiting the scope of the disclosure. For example, the relative size, thickness, and position of each film layer, region, or structure may be reduced or increased for clarity. 
     Some terms are used to refer to specific elements throughout the whole specification and the appended claims in the disclosure. Those skilled in the art should understand that electronic device manufacturers may use different names to refer to the same elements. Herein, it is not intended to distinguish elements with the same function but different names. In the description and claims below, terms such as “have” and “include” are open-ended terms, so they should be interpreted as “including, but not limited to . . . ”. 
     The directional terms mentioned herein, such as “above”, “below”, “front”, “back”, “left”, “right”, and the like, refer only to the directions in the accompanying drawings. Therefore, the directional terms are used for describing instead of limiting the disclosure. It should be understood that when an element or film layer is referred to as being disposed “on”, or “connected to” another element or film layer, the element or film layer may be directly on or connected to said another element or film layer, or intervening elements or film layers may also be present (non-direct circumstances). In contrast, when an element or film layer is referred to as being “directly on” or “directly connected to” another element, no intervening elements or film layers are present. 
     The terms “about”, “equal to”, “equal”, “same”, “substantially”, or “generally” mentioned herein typically mean within a range of 10% of a given value, or within a range of 5%, 3%, 2%, 1%, or 0.5% of the given value. In addition, unless otherwise specified, the terms “the given range is from a first value to a second value” and “the given value falls within a range of a first value to a second value” each mean that the given range includes the first value, the second value, and other values in between. 
     In the embodiment of the disclosure, terms such as “connect”, “interconnect”, and the like, regarding bonding and connection, unless specifically defined, may mean that two structures are in direct contact, or may also mean that two structures are not in direct contact, and other structures are disposed between the two structures. The terms regarding bonding and connection may also include the case where both structures are movable or both structures are fixed. In addition, the term “electrical connection” refers to series connection between two elements through direct or indirect connection. For example, the two elements may be directly connected, or the two elements may be connected in series through one or more conductive elements. Moreover, the term “electrically coupling” refers to two elements separated from each other without any other conductive element between the two elements to connect the two in series. 
     In the following embodiments, the same or similar elements will use the same or similar reference numerals, and repeated description thereof will be omitted. In addition, features in different embodiments may be arbitrarily mixed and used in combination with each other without departing from or conflicting with the spirit of the disclosure, and simple equivalent variations and modifications made in accordance with this specification or the claims are still within the scope covered by the disclosure. Moreover, “first”, “second”, and similar terms mentioned in the specification or the claims serve to merely name discrete elements or differentiate among different embodiments or scopes, and are not intended to limit an upper limit or a lower limit of the quantity of elements or limit the manufacturing sequence or configuration sequence of elements. 
     The electronic device of the disclosure may include, but is not limited to, a radio frequency device or an electronic device having a radio frequency element. The electronic device may include a bendable or flexible electronic device. The radio frequency element may include a frequency selective surface (FSS), RF-Filter, polarizer, resonator, antenna, or the like. The radio frequency device will be taken as the electronic device below to describe the content of the disclosure. Nonetheless, the disclosure is not limited thereto. 
       FIG. 1A  and  FIG. 1B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a first embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 1B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 1A  for the cross-section of section line A-A′ in  FIG. 1B . 
     With reference to  FIG. 1A  and  FIG. 1B , an electronic device  1  may include a substrate  10 , a first electrode  11 , a second electrode  12 , a modulation element  13 , a first solder  14 , and a switch element  15 . The first electrode  11  is disposed on the substrate  10 . The second electrode  12  is disposed on the substrate  10 . The modulation element  13  is disposed on the substrate  10  and includes at least two connecting pads, for example, a connecting pad P 1  and a connecting pad P 2 . The first solder  14  is disposed between the first electrode  11  and one connecting pad (e.g., the connecting pad P 1 ) of the modulation element  13 . The switch element  15  is disposed on the substrate  10 . The one connecting pad (e.g., the connecting pad P 1 ) of the modulation element  13  is electrically connected to the switch element  15  sequentially through the first solder  14 , the first electrode  11 , and the second electrode  12 . 
     To be specific, the substrate  10  is configured to carry elements. The substrate  10  may be a rigid substrate, a bendable substrate, or a flexible substrate. For example, the substrate  10  may include, but is not limited to, a glass substrate, a polymer film, a printed circuit board, a base layer formed of ceramics, or a combination of the above. 
     From the cross-sectional view of the electronic device  1 , as shown in  FIG. 1A , the first electrode  11  is disposed between the substrate  10  and the second electrode  12 , and the second electrode  12  is disposed between the first electrode  11  and the switch element  15 . The first electrode  11  and the second electrode  12  serve as an intermediate medium for electrically connecting the switch element  15  and the modulation element  13 . For example, the materials of the first electrode  11  and the second electrode  12  may include, but is not limited to, copper, aluminum, any material with high conductivity, or a combination of the above. 
     The modulation element  13  is disposed corresponding to the first electrode  11 . For example, the modulation element  13  at least partially overlaps the first electrode  11  in the normal direction (e.g., a third direction D 3 ) of the substrate  10 . From the top view of the electronic device  1 , as shown in  FIG. 1B , the modulation element  13  respectively has a width W 1  and a width W 2  in a first direction D 1  and a second direction D 2 . The width W 1  and the width W 2  may be greater than or equal to 20 micrometers and less than or equal to 1000 micrometers (20 μm≤W 1 ≤1000 μm; 20 μm≤W 2 ≤1000 μm). Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the modulation element  13  includes a variable capacitor. For example, the variable capacitor may be formed by a liquid crystal device, a variable capacitor diode, micro electro mechanical systems (MEMS), or the like. Nonetheless, the disclosure is not limited thereto. 
     By changing the voltage applied to the variable capacitor, the equivalent capacitance in the radio frequency circuit can be controlled, so that the phase and the amplitude of the electromagnetic wave change correspondingly, thus controlling the direction of the electromagnetic wave or improving directivity of the radio frequency device. The transmission medium of the electromagnetic wave may include, but is not limited to, a transmission line, a waveguide structure, a free space, or the like. The electromagnetic wave may include, but is not limited to, a planar wave, a cylindrical wave, a spherical wave, or the like. The frequency range of the electromagnetic wave may include, but is not limited to, radio frequency, millimeter wave, Terahertz (THz), infrared light, visible light, or the like. 
     The connecting pad P 1  of the modulation element  13  is welded on the first electrode  11  through the first solder  14 . For example, the first solder  14  may include, but is not limited to, a solder ball, a copper pillar, any other suitable metal, or a metal alloy. 
     The switch element  15  is configured to drive the modulation element  13 . For example, the switch element  15  may include a thin film transistor (TFT). The material of the channel layer (not shown) of the thin film transistor may include, but is not limited to, low-temperature polysilicon, amorphous silicon, oxide semiconductor, organic semiconductor, III-V compound semiconductor, or the like. 
     Depending on different requirements, the electronic device  1  may also include other elements or layers. For example, the electronic device  1  may also include a third electrode  16  and a second solder  17 . Nonetheless, the disclosure is not limited thereto. 
     The third electrode  16  is disposed on the substrate  10 . In some embodiments, the third electrode  16  and the first electrode  11  may be manufactured in the same layer. For example, the third electrode  16  and the first electrode  11  may both belong to a first conductive layer C 1 . In other words, the third electrode  16  and the first electrode  11  may have the same material and may be formed by the same patterning process. 
     The second solder  17  is disposed between the third electrode  16  and the other connecting pad (e.g., the connecting pad P 2 ) of the modulation element  13 . The other connecting pad (e.g., the connecting pad P 2 ) of the modulation element  13  may be electrically connected to the third electrode  16  through the second solder  17 . Specifically, the connecting pad P 2  of the modulation element  13  is welded on the third electrode  16  through the second solder  17 . The second solder  17  may include, for example but not limited to, a tin ball, a copper pillar, any other suitable metals, or a metal alloy. 
     In some embodiments, the electronic device  1  may also include a fourth electrode  18 . The fourth electrode  18  is arranged on the substrate  10 . In addition, from the cross-sectional view of the electronic device  1 , as shown in  FIG. 1A , the third electrode  16  is disposed between the fourth electrode  18  and the substrate  10 . In some embodiments, the fourth electrode  18  and the second electrode  12  may be manufactured in the same layer. For example, the fourth electrode  18  and the second electrode  12  may both belong to a second conductive layer C 2 . In other words, the fourth electrode  18  and the second electrode  12  may have the same material and may be formed by the same patterning process. 
     In some embodiments, the first conductive layer C 1  may also include a conductive pattern PT 1  and a conductive pattern PT 2  in addition to the first electrode  11  and the third electrode  16 . The first electrode  11  is disposed between the conductive pattern PT 1  and the third electrode  16 . In addition, the first electrode  11 , the conductive pattern PT 1 , and the third electrode  16  are separated from each other. For example, a gap G 1  is present between the first electrode  11  and the conductive pattern PT 1 , and a gap G 2  is present between the first electrode  11  and the third electrode  16 . The third electrode  16  is disposed between the first electrode  11  and the conductive pattern PT 2 . In addition, the third electrode  16 , the first electrode  11 , and the conductive pattern PT 2  are separated from each other. For example, a gap G 3  is present between the third electrode  16  and the conductive pattern PT 2 . 
     From the cross-sectional view of the electronic device  1 , as shown in  FIG. 1A , the conductive pattern PT 1  is disposed between the second electrode  12  and the substrate  10 , and the second electrode  12  is disposed between the switch element  15  and the conductive pattern PT 1 . The gap G 1  between the conductive pattern PT 1  and the first electrode  11  may be covered by the second electrode  12 . In addition, the conductive pattern PT 2  is disposed between the fourth electrode  18  and the substrate  10 . The gap G 3  between the conductive pattern PT 2  and the third electrode  16  may be covered by the fourth electrode  18 . Moreover, the modulation element  13  is disposed corresponding to the gap G 2  between the first electrode  11  and the third electrode  16 . For example, the modulation element  13  at least partially overlaps the gap G 2  in the third direction D 3 . 
     In some embodiments, the first conductive layer C 1  and the second conductive layer C 2  may each be a metal layer. The electromagnetic wave transmitted below the first conductive layer C 1  may be transmitted to the modulation element  13  from the region (e.g., the gap G 2 ) that is not covered by the first conductive layer C 1  or the second conductive layer C 2 , and output from the electronic device  1  after operation (e.g., adjustment of the phase, amplitude, transmission direction, or the like of the electromagnetic wave) of the modulation element  13 . 
     In some embodiments, the electronic device  1  may also include an isolation layer  19 . In addition, the first conductive layer C 1  and the second conductive layer C 2  may be separated from each other by the isolation layer  19 . For example, the conductive pattern PT 1  may be separated from the second electrode  12  and the switch element  15  by the isolation layer  19 , and the conductive pattern PT 2  may be separated from the fourth electrode  18  by the isolation layer  19 . The isolation layer  19  may have an opening A 1  and an opening A 2 . The opening A 1  and the opening A 2  respectively expose the first electrode  11  and the third electrode  16 . The second electrode  12  is electrically connected to the first electrode  11  through the opening A 1 . The fourth electrode  18  is electrically connected to the third electrode  16  through the opening A 2 . The material of the isolation layer  19  may include, but is not limited to, silicon nitride (SiNx), silicon oxide (SiOx), epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, or a combination of the above. 
     In some embodiments, the electronic device  1  may also include a passivation layer  20 . The passivation layer  20  covers the switch element  15 , the second electrode  12 , and the isolation layer  19 . The material of the passivation layer  20  may include, but is not limited to, silicon nitride, silicon oxide, epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, or a combination of the above. 
     The electronic device  1  may have a through hole TH 1 - 1  and a through hole TH 1 - 2 . The through hole TH 1 - 1  may be located between the opening A 1  and the through hole TH 1 - 2 , and the through hole TH 1 - 1  penetrates the passivation layer  20  and the isolation layer  19  and exposes the first electrode  11 . The through hole TH 1 - 2  may be located between the through hole TH 1 - 1  and the opening A 2 , and the through hole TH 1 - 2  penetrates the passivation layer  20  and the isolation layer  19  and exposes the third electrode  16 . 
     The electronic device  1  may also include a connecting pad P 3  and a connecting pad P 4 . The connecting pad P 3  is disposed in the through hole TH 1 - 1  and on the first electrode  11 . The first solder  14  is also disposed in the through hole TH 1 - 1  and may be electrically connected between the connecting pad P 1  and the connecting pad P 3 . The connecting pad P 4  is disposed in the through hole TH 1 - 2  and on the third electrode  16 . The second solder  17  is also disposed in the through hole TH 1 - 2  and may be electrically connected between the connecting pad P 2  and the connecting pad P 4 . The connecting pad P 1  of the modulation element  13  may be electrically connected to the switch element  15  sequentially through the first solder  14 , the connecting pad P 3 , the first electrode  11 , and the second electrode  12 , for example. The connecting pad P 2  of the modulation element  13  may be electrically connected to ground sequentially through the second solder  17 , the connecting pad P 4 , the third electrode  16 , and the fourth electrode  18 , for example. The voltage (e.g., a DC voltage) received by the connecting pad P 1  is different from a voltage (e.g., a ground voltage) received by the connecting pad P 2 . The materials of the connecting pad P 3  and the connecting pad P 4  may include, but is not limited to, nickel gold, nickel palladium gold, silver, gold, nickel, tin, organic solderability preservative (OSP), other conductive materials, or a combination of the above. In some embodiments, the size of the connecting pad P 3  and the connecting pad P 4  may be 10 micrometers*10 micrometers to 160 micrometers*160 micrometers (10 μm*10 μm≤size≤160 μm*160 μm). Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the electronic device  1  may also include a protection layer  21 . The protection layer  21  is disposed on the passivation layer  20 , and the protection layer  21  may cover the modulation element  13  and wrap the connecting pad P 1 , the connecting pad P 2 , the first solder  14 , and the second solder  17 . Nonetheless, the disclosure is not limited thereto. The cross-sectional shape of the protection layer  21  may include a hemispherical shape, but is not limited thereto. It should be noted that the hemisphere is not limited to half of a sphere. The material of the protection layer  21  may include, but is not limited to, epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, parylene, or a combination of the above. 
       FIG. 2A  and  FIG. 2B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a second embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 2B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 2A  for the cross-section of section line B-B′ in  FIG. 2B . 
     With reference to  FIG. 2A  and  FIG. 2B , the main differences between an electronic device  1 A and the electronic device  1  of  FIG. 1A  and  FIG. 1B  are described as follows. The electronic device  1 A includes the substrate  10 , the first electrode  11 , the second electrode  12 , the modulation element  13 , the first solder  14 , the switch element  15 , the third electrode  16 , the second solder  17 , the fourth electrode  18 , a dielectric film  19 A, the passivation layer  20 , the protection layer  21 , a dielectric layer  22 , the conductive pattern PT 1 , the conductive pattern PT 2 , the connecting pad P 3 , the connecting pad P 4 , a connecting pad P 5 , and a connecting pad P 6 . 
     The dielectric film  19 A is configured to carry the second conductive layer C 2  (including the second electrode  12  and the fourth electrode  18 ), the switch element  15 , and the passivation layer  20 . For example, the material of the dielectric film  19 A may include, but is not limited to, epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, or a combination of the above. In some embodiments, a maximum thickness T 19 A of the dielectric film  19 A in the third direction D 3  is greater than or equal to 5 μm and less than or equal to 500 μm. Nonetheless, the disclosure is not limited thereto. 
     The dielectric film  19 A may be attached to the first conductive layer C 1  (including the first electrode  11 , the third electrode  16 , the conductive pattern PT 1 , and the conductive pattern PT 2 ) through the dielectric layer  22 . The material of the dielectric layer  22  may include, for example but not limited to, epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, any adhesive material, or a combination of the above. A maximum thickness T 22  of the dielectric layer  22  in the third direction D 3  may be greater than 1/10000 times the wavelength of the electromagnetic wave and less than  100  times the wavelength of the electromagnetic wave. In some embodiments, the maximum thickness T 22  of the dielectric layer  22  in the third direction D 3  is greater than or equal to 5 μm and less than or equal to 50 μm. Nonetheless, the disclosure is not limited thereto. 
     From the cross-sectional view of the electronic device  1 A, as shown in  FIG. 2A , the dielectric layer  22  is disposed between the first conductive layer C 1  and the dielectric film  19 A, and the dielectric film  19 A is disposed between the second conductive layer C 2  and the dielectric layer  22 . The passivation layer  20  may have an opening A 3  and an opening A 4 . The opening A 3  and the opening A 4  respectively expose the second electrode  12  and the fourth electrode  18 . The connecting pad P 5  and the connecting pad P 6  are respectively disposed in an opening A 5  and an opening A 6 . The materials of the connecting pad P 5  and the connecting pad P 6  may include, but is not limited to, nickel gold, nickel palladium gold, silver, gold, nickel, tin, organic solderability preservative, other conductive materials, or a combination of the above. 
     The electronic device  1 A may have a through hole TH 1  and a through hole TH 2 . The through hole TH 1  penetrates the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  and exposes the first electrode  11 . The through hole TH 2  penetrates the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  and exposes the third electrode  16 . The connecting pad P 3  is disposed in the through hole TH 1  and on the first electrode  11 . The connecting pad P 4  is disposed in the through hole TH 2  and on the third electrode  16 . 
     The first solder  14  is disposed on the connecting pad P 5 , and the first solder  14  is connected to the connecting pad P 3  disposed on the first electrode  11  through the through hole TH 1 . Specifically, the first solder  14  electrically connects the connecting pad P 1 , the connecting pad P 3 , and the connecting pad P 5 . In some embodiments, the first solder  14  may be in direct contact with the sidewall surface of the second electrode  12 , so that the first electrode  11  may be electrically connected to the switch element  15  sequentially through the first solder  14  and the second electrode  12 . For example, the first electrode  11  may be electrically connected to the switch element  15  sequentially through the connecting pad P 3 , the first solder  14 , and the second electrode  12 . Nonetheless, the disclosure is not limited thereto. 
     The second solder  17  is disposed on the connecting pad P 6 , and the second solder  17  is connected to the connecting pad P 4  disposed on the third electrode  16  through the through hole TH 2 . Specifically, the second solder  17  electrically connects the connecting pad P 2 , the connecting pad P 4 , and the connecting pad P 6 . In some embodiments, the second solder  17  may be in direct contact with the sidewall surface of the fourth electrode  18 , so that the third electrode  16  may be electrically connected to ground sequentially through the second solder  17  and the fourth electrode  18 . For example, the third electrode  16  may be electrically connected to ground sequentially through the connecting pad P 4 , the second solder  17 , and the fourth electrode  18 . Nonetheless, the disclosure is not limited thereto. 
     Respectively disposing the switch element  15  and the first conductive layer C 1  on different substrates (e.g., the substrate  10  and the dielectric film  19 A) and then attaching the dielectric film  19 A to the first conductive layer C 1  through the dielectric layer  22  facilitate improving the warpage of the first conductive layer C 1  caused by the mismatch between thermal expansion coefficients of the first conductive layer C 1  and the substrate  10  during a high-temperature manufacturing process (e.g., the manufacturing of the switch element  15 ). 
       FIG. 3A  and  FIG. 3B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a third embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 3B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 3A  for the cross-section of section line C-C′ in  FIG. 3B . 
     With reference to  FIG. 3A  and  FIG. 3B , the main differences between an electronic device  1 B and the electronic device  1 A of  FIG. 2A  and  FIG. 2B  are described as follows. The electronic device  1 B includes the substrate  10 , the first electrode  11 , the second electrode  12 , the modulation element  13 , the first solder  14 , the switch element  15 , the third electrode  16 , the second solder  17 , the fourth electrode  18 , the dielectric film  19 A, the passivation layer  20 , the protection layer  21 , the dielectric layer  22 , a third solder  23 , a fourth solder  24 , the conductive pattern PT 1 , the conductive pattern PT 2 , the connecting pad P 3 , the connecting pad P 4 , the connecting pad P 5 , the connecting pad P 6 , a connecting pad P 7 , and a connecting pad P 8 . 
     The electronic device  1 B may have a through hole TH 3  and a through hole TH 4  in addition to the through hole TH 1  and the through hole TH 2 . The through hole TH 3  penetrates the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  and exposes the first electrode  11 . The through hole TH 4  penetrates the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  and exposes the third electrode  16 . The through hole TH 4 , the through hole TH 2 , the through hole TH 1 , and the through hole TH 3  are arranged in the second direction D 2 , for example. The through hole TH 3  is located between the opening A 3  and the through hole TH 1 , and the through hole TH 4  is located between the opening A 4  and the through hole TH 2 . 
     The connecting pad P 7  is disposed in the through hole TH 3  and on the first electrode  11 . The connecting pad P 8  is disposed in the through hole TH 4  and on the third electrode  16 . The materials of the connecting pad P 7  and the connecting pad P 8  may include, but is not limited to, nickel gold, nickel palladium gold, silver, gold, nickel, tin, organic solderability preservative, other conductive materials, or a combination of the above. 
     The first solder  14  electrically connects the connecting pad P 1  and the connecting pad P 3 , and the first solder  14  is separated from the second electrode  12  and the connecting pad P 5 . The third solder  23  is disposed on the connecting pad P 5 , and the third solder  23  is connected to the connecting pad P 7  disposed on the first electrode  11  through the through hole TH 3 . In some embodiments, the third solder  23  may be in direct contact with the sidewall surface of the second electrode  12 , so that the connecting pad P 1  of the modulation element  13  may be electrically connected to the switch element  15  sequentially through the first solder  14  and the second electrode  12 . For example, the connecting pad P 1  may be electrically connected to the switch element  15  sequentially through the first solder  14 , the connecting pad P 3 , the first electrode  11 , the connecting pad P 7 , the third solder  23 , and the second electrode  12 . 
     The second solder  17  electrically connects the connecting pad P 2  and the connecting pad P 4 , and the second solder  17  is separated from the fourth electrode  18  and the connecting pad P 6 . The fourth solder  24  is disposed on the connecting pad P 6 , and the fourth solder  24  is connected to the connecting pad P 8  disposed on the third electrode  16  through the through hole TH 4 . In some embodiments, the fourth solder  24  may be in direct contact with the sidewall surface of the fourth electrode  18 , so that the connecting pad P 2  of the modulation element  13  may be electrically connected to ground sequentially through the second solder  17  and the fourth electrode  18 . For example, the connecting pad P 2  may be electrically connected to ground sequentially through the second solder  17 , the connecting pad P 4 , the third electrode  16 , the connecting pad P 8 , the fourth solder  24 , and the fourth electrode  18 . 
     The third solder  23  and the fourth solder  24  may include, for example but not limited to, solder balls, copper pillars, other suitable metals, or metal alloys. In addition, the protection layer  21  may further cover the third solder  23  and the fourth solder  24 . 
     The design in which each solder is connected between two connecting pads can increase the process yield or facilitate an increase in the productivity capacity. 
       FIG. 4A  and  FIG. 4B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a fourth embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 4B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 4A  for the cross-section of section line D-D′ in  FIG. 4B . 
     With reference to  FIG. 4A  and  FIG. 4B , the main differences between an electronic device  1 C and the electronic device  1 B of  FIG. 3A  and  FIG. 3B  are described as follows. In the electronic device  1 C, the through hole TH 1  and the through hole TH 2  in  FIG. 3A  and  FIG. 3B  are replaced with a through hole TH 5 . The through hole TH 5  penetrates the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  and exposes the first electrode  11 , the third electrode  16 , and the substrate  10  exposed by the first electrode  11  and the third electrode  16 . The modulation element  13  is disposed in the through hole TH 5 . The connecting pad P 1  of the modulation element  13  is bonded to the connecting pad P 3  disposed on the first electrode  11  through the first solder  14 , and the connecting pad P 2  of the modulation element  13  is bonded to the connecting pad P 4  disposed on the third electrode  16  through the second solder  17 . 
     By forming a through hole (e.g., the through hole TH 5 ) with a relatively large pore size, the modulation element  13  can be conveniently disposed or the adjustable range of the modulation element  13  can be increased. 
       FIG. 5A  and  FIG. 5B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a fifth embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 5B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 5A  for the cross-section of section line E-E′ in  FIG. 5B . 
     With reference to  FIG. 5A  and  FIG. 5B , the main differences between an electronic device  1 D and the electronic device  1 A of  FIG. 2A  and  FIG. 2B  are described as follows. In the electronic device  1 D, it is possible that a first conductive layer C 1 ′ does not include the conductive pattern PT 1  and the conductive pattern PT 2 . In addition, it is possible that the electronic device  1 D does not include the through hole TH 1 , the through hole TH 2 , the connecting pad P 3 , and the connecting pad P 4 . Moreover, the modulation element  13  is electrically coupled to the first electrode  11 , and one connecting pad (e.g., the connecting pad P 1 ) of the modulation element  13  is electrically connected to the switch element  15 . 
     To be specific, the first solder  14  is, for example, electrically connected to the connecting pad P 1  and the connecting pad P 5 . In addition, the connecting pad P 1  of the modulation element  13  is electrically connected to the switch element  15  sequentially through the first solder  14 , the connecting pad P 5 , and the second electrode  12 , for example. On the other hand, the modulation element  13  is also electrically coupled to the third electrode  16 . For example, the third electrode  16  is electrically coupled to the connecting pad P 2  of the modulation element  13 . The second solder  17  is, for example, electrically connected to the connecting pad P 2  and the connecting pad P 6 . In addition, the connecting pad P 2  of the modulation element  13  is, for example, electrically connected to ground sequentially through the second solder  17 , the connecting pad P 6 , and the fourth electrode  18 . 
     In some embodiments, the first conductive layer C 1 ′ and a second conductive layer C 2 ′ may each be a metal layer. The electromagnetic wave transmitted below the first conductive layer C 1 ′ may be transmitted to the modulation element  13  sequentially through the gap G 2  of the first conductive layer C 1 ′ and a gap G 4  of the second conductive layer C 2 ′. The electromagnetic wave may be output from the electronic device  1 D after operation (e.g., adjustment of the phase, amplitude, transmission direction, or the like of the electromagnetic wave) of the modulation element  13 . The size of the gap G 2  may be smaller than, equal to, or larger than the gap G 4 , which is not particularly limited herein. 
     The design in which the first conductive layer C 1 ′ and the second conductive layer C 2 ′ are overlapped in the third direction D 3  facilitates an increase in the adjustable capacitance. 
       FIG. 6A  and  FIG. 6B  are respectively a schematic partial cross-sectional view and a schematic partial top view of an electronic device according to a sixth embodiment of the disclosure. In order to clearly show the relative configuration relationships between some elements and/or film layers,  FIG. 6B  omits illustration of some elements and/or film layers of the electronic device. In addition, reference may be made to  FIG. 6A  for the cross-section of section line F-F′ in  FIG. 6B . 
     With reference to  FIG. 6A  and  FIG. 6B , the main differences between an electronic device  1 E and the electronic device  1 D of  FIG. 5A  and  FIG. 5B  are described as follows. The electronic device lE includes the through hole TH 2  and the connecting pad P 4 . In addition, the third electrode  16  is electrically connected to the connecting pad P 2  of the modulation element  13 . 
     For example, the second solder  17  may be disposed on the connecting pad P 6  and electrically connected between the connecting pad P 2  and the connecting pad P 4  through the through hole TH 2 . 
     In some other embodiments, although not shown, the first solder  14  may be disposed on the connecting pad P 5  and electrically connected between the connecting pad P 1  and the connecting pad P 3  through the through hole TH 1  (see  FIG. 2A ). In addition, the second solder  17  may be electrically connected between the connecting pad P 2  and the connecting pad P 6  (see  FIG. 5A ). 
     In this embodiment, the third electrode  16  may be electrically connected to ground. Nonetheless, the disclosure is not limited thereto. In some other embodiments, the third electrode  16  may receive a first DC voltage, and the fourth electrode  18  may receive a second DC voltage. Nonetheless, the disclosure is not limited thereto. In some other embodiments, the manufacturing of the third electrode  16  may be omitted. 
       FIG. 7  to  FIG. 9  are schematic partial cross-sectional views of manufacturing process flows of the electronic device according to the first embodiment of the disclosure. With reference to  FIG. 7  first, the first conductive layer C 1  is formed on the substrate  10 . The first conductive layer C 1  is a patterned conductive layer and may include the first electrode  11 , the third electrode  16 , the conductive pattern PT 1 , and the conductive pattern PT 2 . Nonetheless, the disclosure is not limited thereto. 
     With reference to  FIG. 8 , after the first conductive layer C 1  is formed, the isolation layer  19 , the second conductive layer C 2 , the switch element  15 , and the passivation layer  20  are sequentially formed on the substrate  10 . The second conductive layer C 2  is a patterned conductive layer and may include the second electrode  12  and the fourth electrode  18 . Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the switch element  15  may be directly formed on the substrate  10  through a photolithography process to facilitate the manufacturing. In some other embodiments, the switch element  15  may be bonded onto the substrate  10  through conductive bumps (not shown) to reduce the manufacturing cost. 
     Next, the through hole TH 1 - 1  and the through hole TH 1 - 2  penetrating the passivation layer  20  and the isolation layer  19  are formed. The through hole TH 1 - 1  and the through hole TH 1 - 2  may be formed by, for example but not limited to, photolithography and etching. 
     Then, the connecting pad P 3  and the connecting pad P 4  are formed in the through hole TH 1 - 1  and the through hole TH 1 - 2 , respectively. The connecting pad P 3  and the connecting pad P 4  may be formed by, for example but not limited to, chemical plating, immersion, electrolysis, or the like. 
     With reference to  FIG. 9 , the first solder  14  and the second solder  17  are respectively formed on the connecting pad P 3  and the connecting pad P 4  by printing. Next, the connecting pad P 1  and the connecting pad P 2  of the modulation element  13  are respectively disposed on the first solder  14  and the second solder  17 . Then, the connecting pad P 1  and the connecting pad P 2  of the modulation element  13  are fixed on the first solder  14  and the second solder  17  through solder reflow. Next, the protection layer  21  is formed. As such, the manufacturing of the electronic device  1  is preliminarily completed. 
       FIG. 10  to  FIG. 13  are schematic partial cross-sectional views of manufacturing process flows of the electronic device according to the second embodiment of the disclosure. With reference to  FIG. 10  first, the first conductive layer C 1  and the dielectric layer  22  are sequentially formed on the substrate  10 . 
     With reference to  FIG. 11 , the dielectric film  19 A, the second conductive layer C 2  (including the second electrode  12  and the fourth electrode  18 ), and the passivation layer  20  are sequentially formed on a carrier CR. The carrier board CR may include a rigid carrier board, such as a glass substrate. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the steps shown in  FIG. 11  may be performed after the steps shown in  FIG. 10 . In some other embodiments, the steps shown in  FIG. 10  may be performed after the steps shown in  FIG. 11 . 
     With reference to  FIG. 12 , the carrier board CR is removed, and the dielectric film  19 A is attached to the dielectric layer  22 . The carrier CR may be removed, for example, by laser lift-off, namely by irradiating a release layer (not shown) disposed between the carrier CR and the dielectric film  19 A with laser to separate the carrier CR and the dielectric film  19 A. Nonetheless, the disclosure is not limited thereto. 
     Next, the through hole TH 1  and the through hole TH 2  penetrating the passivation layer  20 , the dielectric film  19 A, and the dielectric layer  22  are formed to expose the first electrode  11  and the third electrode  16 . The through hole TH 1  and the through hole TH 2  may be formed by, for example but not limited to, laser drilling. In other embodiments, at least one of the through hole TH 1  and the through hole TH 2  may also be formed by photolithography and etching, laser drilling, or a combination of the above. A pore size R 1  (e.g., a diameter) of the through hole TH 1  and a pore size R 2  (e.g., a diameter) of the through hole TH 2  may be greater than or equal to 40 μm to facilitate subsequent formation of solders in the through hole TH 1  and the through hole TH 2 . Nonetheless, the disclosure is not limited thereto. 
     With reference to  FIG. 13 , the connecting pad P 5 , the connecting pad P 3 , the connecting pad P 4 , and the connecting pad P 6  are respectively formed in the opening A 3 , the through hole TH 1 , the through hole TH 2 , and the opening A 4 . The connecting pad P 5 , the connecting pad P 3 , the connecting pad P 4 , and the connecting pad P 6  may be formed by, for example but not limited to, chemical plating, immersion, electrolysis, or the like. 
     Next, the first solder  14  is formed on the connecting pad P 3  and the connecting pad P 5  and the second solder  17  is formed on the connecting pad P 4  and the connecting pad P 6  by printing or the like. Then, the connecting pad P 1  and the connecting pad P 2  of the modulation element  13  are respectively disposed on the first solder  14  and the second solder  17 . Next, the connecting pad P 1  and the connecting pad P 2  of the modulation element  13  are fixed on the first solder  14  and the second solder  17  through solder reflow. Then, the protection layer  21  is formed. As such, the manufacturing of the electronic device  1 A is preliminarily completed. 
     The manufacturing methods of the electronic device  1 B to the electronic device  1 E are generally similar to the manufacturing method of the electronic device  1 A, and will thus not be described in detail below. 
     In addition, although not shown, the electronic device  1 A to the electronic device  1 E may also be modified according to  FIG. 1A , where the conductive layers, the switch element, the modulation element, the solders, the isolation layer, the passivation layer, the connecting pads, and the protection layer are disposed on the same substrate (e.g., the substrate  10 ). 
     In addition, in the above-mentioned embodiments, although the switch element and other elements/film layers are all disposed on the same side of the substrate, the disclosure is not limited thereto. In other embodiments not shown, the switch element may also be disposed below the substrate, so that the switch element and other elements/film layers are respectively disposed on opposite sides of the substrate. Under this architecture, the switch element may be electrically connected to the second electrode through circuits (e.g., vias or other circuits) not shown. 
       FIG. 14  and  FIG. 15  are respectively schematic partial cross-sectional views of an electronic device according to a seventh embodiment and an eighth embodiment of the disclosure. For the schematic partial top view of the electronic devices of  FIG. 14  and  FIG. 15 , reference may be made to  FIG. 1B . 
     With reference to  FIG. 14 , the main differences between an electronic device  1 F and the electronic device  1 A of  FIG. 2A  are described as follows. In the electronic device  1 F, after the dielectric film  19 A is disposed on the substrate  10 , a through hole TH 6  that penetrates the dielectric film  19 A and the dielectric layer  22  and exposes the first electrode  11  and the third electrode  16  is formed. Next, the second conductive layer C 2  is formed on the substrate  10 . The second electrode  12  of the second conductive layer C 2  is disposed on the dielectric film  19 A, extends into the through hole TH 6 , and is in contact with the first electrode  11 . The fourth electrode  18  of the second conductive layer C 2  is disposed on the dielectric film  19 A, extends into the through hole TH 6 , and is in contact with the third electrode  16 . Then, the switch element  15  and the passivation layer  20  are formed. Next, the connecting pad P 3  and the connecting pad P 4  are respectively formed in the opening A 3  and the opening A 4  of the passivation layer  20 . Moreover, the connecting pad P 1  and the connecting pad P 2  of the modulation element  13  are fixed on the connecting pad P 3  and the connecting pad P 4  through the first solder  14  and the second solder  17 . Then, the protection layer  21  is formed. As such, the manufacturing of the electronic device  1 F is preliminarily completed. 
     During the manufacturing of the electronic device  1 F, the dielectric film  19 A and the dielectric layer  22  at the gap G 2  are removed when the through hole TH 6  is formed. Accordingly, in the electronic device  1 F, the dielectric film  19 A and the dielectric layer  22  are not present below the modulation element  13 . In addition, the second electrode  12  is in contact with the first electrode  11 , and the second electrode  12  is separated from the connecting pad P 3  by the passivation layer  20 ; the fourth electrode  18  is in contact with the third electrode  16 , and the fourth electrode  18  is separated from the connecting pad P 4  by the passivation layer  20 . 
     With reference to  FIG. 15 , the main differences between an electronic device  1 G and the electronic device  1 F of  FIG. 14  are described as follows. In the electronic device  1 G, the opening A 3  exposes part of the second electrode  12 , and the connecting pad P 3  is disposed on the first electrode  11  and covers the part of the second electrode  12  exposed by the opening A 3 . In addition, the opening A 4  exposes part of the fourth electrode  18 , and the connecting pad P 4  is disposed on the third electrode  16  and covers the part of the fourth electrode  18  exposed by the opening A 4 . 
       FIG. 16A  to  FIG. 16D  are schematic partial views of manufacturing process flows of an electronic device according to a ninth embodiment of the disclosure, wherein  FIGS. 16A and 16B  are schematic partial top views, and  FIGS. 16C and 16D  are schematic partial cross-sectional views. 
     With reference to  FIG. 16A , a plurality of switches SW are formed on a substrate SUB. For example, the substrate SUB may include, but is not limited to, a glass substrate, a polymer film, a printed circuit board, a base layer formed of ceramics, or a combination of the above. The switches SW may include thin film transistors (TFTs). The material of the channel layer (not shown) of the thin film transistor may include, but is not limited to, low-temperature polysilicon, amorphous silicon, oxide semiconductor, organic semiconductor, III-V compound semiconductor, or the like. The plurality of switches SW may be arranged along the first direction D 1  and the second direction D 2 . 
     With reference to  FIG. 16B , a plurality of bonding pads P 15  are formed on the plurality of switches SW. The materials of the connecting pads P 15 ′ may include, but is not limited to, nickel gold, nickel palladium gold, silver, gold, nickel, tin, organic solderability preservative (OSP), other conductive materials, or a combination of the above. Then, a cutting process is performed on the substrate SUB to form a plurality of switch elements  15  (one switch element  15  is shown in  FIG. 16C  and  FIG. 16D ) separated from each other. For example, a laser (not shown) is utilized to cut the substrate SUB along cutting lines (see dash lines in  FIG. 16B ). 
     With reference to  FIG. 16C , the switch element  15  and the modulation element  13  are then bonded to the substrate  10  through solders CT. For example, the bonding pads P 15  of the switch element  15  are bonded to connecting pads P 15 ′ on the substrate  10  through solders CT. The solders CT may include, for example but not limited to, a tin ball, a copper pillar, any other suitable metals, or a metal alloy. The materials of the bonding pads P 15  may include, but is not limited to, nickel gold, nickel palladium gold, silver, gold, nickel, tin, organic solderability preservative (OSP), other conductive materials, or a combination of the above. Please refer to the previous description for the method of bonding the modulation element  13  to the substrate  10 , which will not be repeated here. 
     With reference to  FIG. 16D , an electronic device  1 H is formed after a protection layer  21  and a protection layer  21 ′ are formed on the passivation layer  20 . The protection layer  21  may cover the modulation element  13  and wrap the connecting pad P 1 , the connecting pad P 2 , the first solder  14 , and the second solder  17 . The protection layer  21 ′ may cover the switch element  15  and wrap the connecting pads P 15 ′ and the solders CT. In some embodiments, the material of the protection layer  21 ′ may include, but is not limited to, epoxy resin, acrylic, solder resist, silicon materials, bismaleimide, polyimide, parylene, or a combination of the above. Materials of the protection layer  21 ′ and the protection layer  21  may be the same or different. For example, dielectric constant (Dk) and dissipation factor (Df) of the protection layer  21  may be lower than those of the protection layer  21 ′, respectively. In some embodiments, the dissipation factor of the protection layer  21  may be less than  0 . 01 , but is not limited thereto. 
     In summary of the foregoing, in the embodiments of the disclosure, by changing the voltage applied to the variable capacitor, the equivalent capacitance in the radio frequency circuit can be controlled, so that the phase and the amplitude of the electromagnetic wave change correspondingly, thus controlling the direction of the electromagnetic wave or improving directivity of the radio frequency device. 
     Each of the above embodiments only serves for describing, instead of limiting, the technical solutions of the disclosure. Although the disclosure has been described in detail with reference to the above-mentioned embodiments, those ordinarily skilled in the art should understand that the technical solutions described in the above-mentioned embodiments may still be combined or modified, or that some or all technical features therein may be equivalently replaced. However, the nature of the corresponding technical solutions so combined, modified, or replaced does not depart from the scope of the technical solutions of the embodiments of the disclosure. 
     Although the embodiments and the advantages thereof have been disclosed as above, it should be understood that any person having ordinary skill in the art may make variations, replacements, and modifications without departing from the spirit and scope of the disclosure, and the feature in each embodiment may be arbitrarily mixed with and replaced by each other to form another new embodiment. In addition, the protection scope of the disclosure is not limited to a process, machine, manufacturing, material composition, device, method, and step in a specific embodiment in this specification. Any person having ordinary skill in the art can understand from the content of the disclosure that the existing or to-be-developed process, machine, manufacturing, material composition, device, method, and step may be used according to the disclosure as long as the substantially same function can be implemented or the substantially same result can be obtained in the embodiments described herein. Therefore, the protection scope of the disclosure includes the above-mentioned process, machine, manufacturing, material composition, device, method, and step. In addition, each claim forms an independent embodiment, and the protection scope of the disclosure also includes a combination of each of the claims and embodiments. The protection scope of the disclosure should be subject to the appended claims.