Antenna element

Abstract

The invention provides an antenna element capable of realizing broadband of available electromagnetic waves. An antenna element according to an embodiment of the present invention is provided with an inorganic material substrate, a first conductor layer, a support substrate, a cavity, and a ground conductor layer. The first conductor layer is disposed on one side of the inorganic material substrate in the thickness direction and includes a patch antenna. The support substrate is disposed on the opposite side of the inorganic material substrate from the first conductor layer. The cavity portion is disposed on the opposite side of the inorganic material substrate from the first conductor layer and on the inorganic material substrate side of the support substrate. The ground conductor layer is disposed in the hollow portion. The thickness t of the inorganic material substrate satisfies the following formula (1). When the patch antenna is projected in the thickness direction of the inorganic material substrate, at least a part of the projection surface of the patch antenna overlaps the cavity.

Description

Technical Field

[0001] This invention relates to an antenna element. Background Technology

[0002] Conventional electromagnetic wave sensors are known, in which electromagnetic waves are transmitted to an object, and reflected waves reflected from the object are received to monitor the object. Typically, such electromagnetic wave sensors utilize antenna elements capable of transmitting and / or receiving electromagnetic waves. As an example of an antenna element, a single antenna has been proposed, comprising: a dielectric substrate; a signal conversion section disposed on the surface of the dielectric substrate; and a ground plane disposed on the back side of the dielectric substrate (see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6955590 Summary of the Invention

[0006] In recent years, the applications of electromagnetic wave sensors have expanded, and their use as human body sensing sensors has been explored. However, when the single antenna described in Patent Document 1 is applied to a human body sensing sensor, the required resolution is sometimes not fully achieved. The resolution of an electromagnetic wave sensor depends on the width of the frequency range (hereinafter referred to as the bandwidth) of the electromagnetic waves available in the antenna element. Therefore, a wide bandwidth of available electromagnetic waves is desirable for the antenna element.

[0007] The main objective of this invention is to provide an antenna element capable of enabling the broadbanding of usable electromagnetic waves.

[0008] [1] The antenna element according to the embodiments of the present invention includes: an inorganic material substrate, a first conductor layer, a support substrate, a void portion, and a ground conductor layer. The first conductor layer is disposed on one side in the thickness direction of the inorganic material substrate. The first conductor layer includes a patch antenna. The support substrate is disposed on the side opposite to the first conductor layer relative to the inorganic material substrate. The void portion is disposed on the side opposite to the first conductor layer relative to the inorganic material substrate and on the inorganic material substrate side of the support substrate. The ground conductor layer is disposed in the void portion. The ground conductor layer is capable of generating an electric field between itself and the patch antenna. The thickness t of the inorganic material substrate satisfies the following formula (1). When the patch antenna is projected along the thickness direction of the inorganic material substrate, at least a portion of the projection surface of the patch antenna overlaps with the void portion.

[0009] [Mathematical Expression 1]

[0010]

[0011] (In the formula, t represents the thickness of the inorganic material substrate. λ represents the wavelength of the electromagnetic wave transmitted and / or received in the antenna element. ε represents the relative permittivity of the inorganic material substrate. a represents a value greater than 3.)

[0012] [2] In the antenna element described in [1] above, when the patch antenna is projected along the thickness direction of the inorganic material substrate, the entire projection surface of the patch antenna can overlap with the cavity portion.

[0013] [3] In the antenna element described in [1] or [2] above, the first conductor layer may further include a transmission line. The transmission line is connected to the patch antenna described above.

[0014] [4] The antenna element described in [3] above may further include a first ground layer. The first ground layer is disposed between the inorganic material substrate and the support substrate at a portion different from the void portion. When the transmission line is projected along the thickness direction of the inorganic material substrate, at least a portion of the projection surface of the transmission line overlaps with the first ground layer.

[0015] [5] The antenna element described in [4] above may further include a bonding portion. This bonding portion bonds the inorganic material substrate and the support substrate.

[0016] [6] In the antenna element described in [5] above, the bonding portion may include a first bonding layer and a second bonding layer. The first bonding layer is disposed on the surface of the inorganic material substrate opposite to the first conductor layer in the thickness direction of the inorganic material substrate. The second bonding layer is disposed on the surface of the first ground layer opposite to the support substrate in the thickness direction of the inorganic material substrate. The second bonding layer is bonded to the first bonding layer.

[0017] [7] In any of the antenna elements described in [1] to [6] above, the thickness t of the inorganic material substrate can be less than 100 μm.

[0018] [8] In any of the antenna elements described in [1] to [7] above, the frequency of the electromagnetic waves transmitted and / or received in the antenna element can be 20 GHz to 20 THz.

[0019] [9] In any of the antenna elements described in [1] to [8] above, the inorganic material substrate may be made of quartz glass.

[0020]

[10] In any of the antenna elements described in [1] to [9] above, the supporting substrate may be made of silicon.

[0021] Invention Effects

[0022] According to embodiments of the present invention, broadbanding of available electromagnetic waves can be achieved. Attached Figure Description

[0023] Figure 1 This is a schematic perspective view of the antenna element involved in the embodiments of the present invention.

[0024] Figure 2 yes Figure 1 The II-II' cross-sectional view of the antenna element.

[0025] Figure 3 This is a schematic perspective view of an antenna element according to another embodiment of the present invention.

[0026] Figure 4 This is a schematic perspective view of an antenna element according to another embodiment of the present invention.

[0027] Figure 5 This is a schematic perspective view of an antenna element according to another embodiment of the present invention.

[0028] Figure 6 This is a schematic perspective view of an antenna element according to another embodiment of the present invention.

[0029] Figure 7 yes Figure 1 A schematic perspective view of the support substrate and the second conductor layer of the antenna element.

[0030] Figure 8 It is shown Figure 7 A schematic perspective view of another embodiment of the second conductor layer.

[0031] Figure 9 It is shown Figure 7 A schematic perspective view of another embodiment of the second conductor layer.

[0032] Figure 10 This is a graph showing the S11 parameters in the antenna element of Embodiment 1.

[0033] Figure 11 This is a graph showing the S11 parameters in the antenna element of Comparative Example 1. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings; however, the present invention is not limited to these embodiments. Furthermore, the accompanying drawings make the description clearer, and therefore, the width, thickness, shape, etc., of each part are sometimes schematically shown compared to the embodiments; however, this is merely an example and does not limit the interpretation of the present invention.

[0035] A. Overall Structure of Antenna Elements

[0036] Figure 1 This is a schematic perspective view of an antenna element according to one embodiment of the present invention. Figure 2 yes Figure 1 The II-II' cross-sectional view of the antenna element.

[0037] Typically, the antenna element 100 is capable of transmitting and / or receiving electromagnetic waves in the millimeter-wave to terahertz wave range. Millimeter waves are typically electromagnetic waves with frequencies of approximately 20 GHz to 300 GHz, and terahertz waves are typically electromagnetic waves with frequencies of approximately 300 GHz to 20 THz.

[0038] The frequency of the electromagnetic waves that the antenna element can transmit and / or receive is, for example, 20 GHz to 20 THz, or, for example, 20 GHz to 500 GHz, or, for example, 20 GHz to 300 GHz, or, for example, 100 GHz to 200 GHz.

[0039] Antenna element 100 includes: an inorganic material substrate 2, a first conductor layer 1, a support substrate 3, a cavity 5, and a ground conductor layer 41. The first conductor layer 1 is disposed on one side of the inorganic material substrate 2 in the thickness direction. The first conductor layer 1 includes a patch antenna 11. The support substrate 3 is disposed on the opposite side of the first conductor layer 1 relative to the inorganic material substrate 2. The cavity 5 is disposed on the opposite side of the first conductor layer 1 relative to the inorganic material substrate 2 and is disposed on the inorganic material substrate side of the support substrate 3. The ground conductor layer 41 is disposed within the cavity 5. The patch antenna 11, the ground conductor layer 41, and the inorganic material substrate 2 located therebetween typically constitute a planar antenna. The ground conductor layer 41 is capable of generating an electric field between itself and the patch antenna 11. More specifically, when the patch antenna 11 receives and / or transmits the aforementioned high-frequency electromagnetic waves, an electric field is generated between the patch antenna 11 and the ground conductor layer 41. The thickness t of the inorganic material substrate 2 satisfies the following formula (1). When the patch antenna 11 is projected along the thickness direction of the inorganic material substrate 2, at least a portion of the projection surface of the patch antenna 11 overlaps with the cavity portion 5.

[0040] [Mathematical Expression 1]

[0041]

[0042] (In the formula, t represents the thickness of the inorganic material substrate 2. λ represents the wavelength of the electromagnetic wave transmitted and / or received in the antenna element 100. ε represents the relative permittivity of the inorganic material substrate 2. a represents a value of 3 or higher.)

[0043] Based on this configuration, since the thickness of the inorganic material substrate 2 satisfies the above formula (1), even when the antenna element 100 transmits and / or receives the aforementioned high-frequency electromagnetic waves, the induction of planar mode can be suppressed, thereby suppressing the resonance of the inorganic material substrate 2. In addition, when the patch antenna 11 is projected along the thickness direction of the inorganic material substrate 2, at least a portion of the projection surface of the patch antenna 11 overlaps with the void portion 5. Therefore, the bandwidth of the frequency (resonance frequency) that can resonate between the patch antenna 11 and the ground conductor layer 41 can be expanded, resulting in a broadband frequency emitted from the antenna element 100.

[0044] Therefore, the reflection loss of electromagnetic waves in antenna element 100 can be significantly reduced. As a result, the bandwidth of electromagnetic waves with sufficiently small reflection loss, that is, the bandwidth of electromagnetic waves whose S11 parameter representing reflection loss reaches a specified value or below, can be extended in antenna element 100. In other words, antenna element 100 can function as a broadband antenna.

[0045] In one embodiment, the bandwidth (-10dB bandwidth) of the electromagnetic wave for which the S11 parameter (reflection loss) of the antenna element 100 reaches -10dB or less is, for example, 5.0 GHz or more, preferably 8.0 GHz or more, more preferably 10.0 GHz or more, and even more preferably 13.0 GHz or more.

[0046] On the other hand, the upper limit of the -10dB bandwidth of antenna element 100 is typically 50GHz. It should be noted that the S11 parameters are determined using, for example, a network analyzer.

[0047] Furthermore, regarding antenna element 100, miniaturization is under development, and circuit integration is expected to be achieved in the future. Therefore, it is anticipated that antenna element 100 will also require miniaturization along with its integration. In the aforementioned antenna element 100, the thickness of the inorganic material substrate 2 satisfies the above formula (1), achieving thin-walled inorganic material substrate 2. Therefore, broadband antenna element 100 can be achieved, and miniaturization can also be met.

[0048] The area ratio of the portion of the projection surface of the patch antenna 11 that overlaps with the cavity 5 is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more. If the projection surface of the patch antenna 11 overlaps with the cavity 5 in the above-mentioned area ratio, broadband antenna element 100 can be stably achieved.

[0049] In one embodiment, when the patch antenna 11 is projected along the thickness direction of the inorganic material substrate 2, the entire projection surface of the patch antenna 11 overlaps with the cavity portion 5. That is, the area ratio of the portion of the projection surface of the patch antenna 11 that overlaps with the cavity portion 5 is 100%. With this configuration, broadband antenna element 100 can be stably achieved.

[0050] In one embodiment, when the patch antenna 11 and the cavity portion 5 are projected along the thickness direction of the inorganic material substrate 2, the projected area of ​​the cavity portion 5 is greater than or equal to the projected area of ​​the patch antenna 11. The projected area of ​​the cavity portion 5 is, for example, 1 to 4 times, preferably 1 to 3 times, the projected area of ​​the patch antenna 11. If the projected area of ​​the cavity portion 5 is in such a relationship with the projected area of ​​the patch antenna 11, the patch antenna 11 can be easily positioned by overlapping the cavity portion 5 when viewed from the thickness direction of the inorganic material substrate 2. Therefore, the design freedom of the patch antenna 11 can be increased, and the broadband of the antenna element 100 can be achieved more stably.

[0051] In the example shown, when the patch antenna 11 and the void portion 5 are projected along the thickness direction of the inorganic material substrate 2, the outer edge of the projection surface of the void portion 5 is spaced apart from the outer edge of the projection surface of the patch antenna 11. Figure 2 As shown, in the normal direction to the outer edge of the projection surface of the patch antenna 11, the distance L between the outer edge of the projection surface of the cavity 5 and the outer edge of the projection surface of the patch antenna 11 is, for example, 0 μm to λ / 2ε μm, or for example, 0 μm to λ / 4ε μm. Here, ε represents the relative permittivity of the inorganic material substrate 2. If the distance L between the outer edge of the cavity 5 and the patch antenna 11 is within such a range, the design freedom of the patch antenna 11 can be further improved, and the broadband of the antenna element 100 can be achieved more stably.

[0052] like Figure 1 As shown, the patch antenna 11 has any suitable shape. Examples of shapes for the patch antenna 11 as viewed from the thickness direction of the inorganic material substrate 2 include: a triangle, a quadrilateral, a pentagon, a hexagon or larger, a roughly circular shape, and a roughly elliptical shape. In the example shown, the patch antenna 11 has a roughly rectangular shape when viewed from the thickness direction of the inorganic material substrate 2.

[0053] The cavity 5 has any suitable shape. As an example of the shape of the cavity 5 as viewed from the thickness direction of the inorganic material substrate 2, the same shape as the patch antenna 11 described above can be given.

[0054] In one embodiment, when viewed from the thickness direction of the inorganic material substrate 2, the cavity 5 has a shape similar to that of the patch antenna 11. In the example shown, the cavity 5 and the patch antenna 11 have similar shapes to each other, and the center of the patch antenna 11 and the center of the cavity 5 are located on the same axis along the thickness direction of the inorganic material substrate 2.

[0055] In one embodiment, the first conductor layer 1 includes a patch antenna 11 and a transmission line 12. The transmission line 12 is connected to the patch antenna 11. The end of the transmission line 12 opposite to the patch antenna 11 is typically configured to be connectable to an external device. With this configuration, an electrical signal input from an external device can be supplied to the patch antenna 11 via the transmission line 12. When an electrical signal is supplied to the patch antenna 11, the patch antenna 11 and the ground conductor layer 41 can convert the electrical signal into an electromagnetic wave. Therefore, the patch antenna 11 can radiate the electromagnetic wave converted from the electrical signal. Furthermore, when the patch antenna 11 receives an electromagnetic wave, the patch antenna 11 and the ground conductor layer 41 can convert the electromagnetic wave into an electrical signal. Therefore, the antenna element 100 can transmit the electrical signal converted from the electromagnetic wave to an external device via the transmission line 12.

[0056] The transmission line 12 typically has a flat strip shape extending along a predetermined direction. The width of the transmission line 12 is, for example, 2 μm to 800 μm. When the patch antenna 11 has a generally rectangular shape, the direction in which the transmission line 12 extends is typically approximately parallel to the width direction of the patch antenna 11.

[0057] In one embodiment, the patch antenna 11 and the transmission line 12 are configured in an impedance-matched manner.

[0058] like Figure 3 As shown, the patch antenna 11 may have a notch 111. The notch 111 is disposed adjacent to the connection portion of the transmission line 12 in the patch antenna 11. The notch 111 has any suitable configuration. The notch 111 is recessed from the outer edge of the patch antenna 11 toward the inward side.

[0059] In addition, such as Figure 4 As shown, the patch antenna 11 may have a slit 112. The slit 112 extends through the patch antenna 11 along the thickness direction. The slit 112 has any suitable configuration. In the example shown, when viewed from the thickness direction of the inorganic material substrate 2, the slit 112 has a generally U-shaped form.

[0060] Additionally, the transmission line 12 may have a narrow portion 121 and a wide portion 122. The narrow portion 121 is located at the end of the transmission line 12 on the side of the patch antenna 11. The narrow portion 121 is connected to the patch antenna 11. The width of the narrow portion 121 is smaller than the width of the wide portion 122. The width of the narrow portion 121 can be arbitrarily and appropriately adjusted. The wide portion 122 is located on the opposite side of the patch antenna 11 relative to the narrow portion 121. The range of the width of the wide portion 122 is, for example, the same as the range of the width of the transmission line 12 described above.

[0061] like Figure 1 and Figure 2 As shown, in one embodiment, the transmission line 12 constitutes a waveguide capable of propagating electromagnetic waves. Thus, electromagnetic waves can be supplied to the patch antenna 100. In the example shown, the transmission line 12, together with the first ground layer 42, constitutes a microstrip line. It should be noted that, hereinafter, the transmission line 12 constituting the microstrip line is sometimes referred to as the MS-type signal wiring 12a. The antenna element 100 includes: a patch antenna 11, a ground conductor layer 41, the MS-type signal wiring 12a, and the first ground layer 42, constituting a microstrip patch antenna.

[0062] The width of the MS type signal wiring 12a is, for example, 20μm to 800μm, preferably 50μm to 500μm.

[0063] Typically, the first ground layer 42 is disposed between the inorganic material substrate 2 and the support substrate 3 in a location different from the void portion 5. When the transmission line 12 (MS type signal wiring 12a) is projected along the thickness direction of the inorganic material substrate 2, at least a portion of the projection surface of the transmission line 12 overlaps with the first ground layer 42.

[0064] With this configuration, if a voltage is applied to the MS-type signal wiring 12a and the first ground layer 42, an electric field is generated between the MS-type signal wiring 12a and the first ground layer 42. Therefore, electromagnetic waves input from an external device can combine with the electric field generated between the MS-type signal wiring 12a and the first ground layer 42, propagate within the inorganic material substrate 2, and reach the patch antenna 11. Furthermore, when the patch antenna 11 receives electromagnetic waves, these waves can propagate within the inorganic material substrate 2 through the electric field generated between the MS-type signal wiring 12a and the first ground layer 42, and be transmitted to the external device.

[0065] In addition, such as Figure 5As shown, in another embodiment, the transmission line 12 and the second ground layer 13 together constitute a coplanar line. In this embodiment, the first conductor layer 1 also includes a second ground layer 13. It should be noted that, hereinafter, the transmission line 12 constituting the coplanar line is sometimes referred to as the CP-type signal wiring 12b. The antenna element 100 includes: a patch antenna 11, a ground conductor layer 41, the CP-type signal wiring 12b, and the second ground layer 13, constituting a coplanar patch antenna.

[0066] The width of the CP type signal wiring 12b is, for example, 2μm to 200μm, preferably 20μm to 150μm.

[0067] The second grounding layer 13 is configured to sandwich the transmission line 12 in a direction orthogonal to the direction in which the transmission line 12 (CP type signal wiring 12b) extends. A gap (slit) is formed between the second grounding layer 13 and the transmission line 12 (CP type signal wiring 12b) in a direction orthogonal to the direction in which the transmission line 12 extends. The width of this gap is, for example, 2 μm to 100 μm, preferably 5 μm to 80 μm.

[0068] With this configuration, if a voltage is applied to the CP-type signal wiring 12b, an electric field is generated between the CP-type signal wiring 12b and the second ground layer 13. Therefore, electromagnetic waves input from an external device can combine with the electric field generated between the CP-type signal wiring 12b and the second ground layer 13, propagate in the inorganic material substrate 2, and be transmitted to the patch antenna 11. Furthermore, when the patch antenna 11 receives electromagnetic waves, these electromagnetic waves can propagate in the inorganic material substrate 2 through the electric field generated between the CP-type signal wiring 12b and the second ground layer 13, and be transmitted to the external device.

[0069] In addition, such as Figure 6 As shown, the second ground layer 13 can be configured to surround the patch antenna 11 in addition to the transmission line 12. In this case, the aforementioned gap (slit) is formed between the second ground layer 13 and the patch antenna 11. Therefore, it is possible to... Figure 5 The antenna is composed of different designs.

[0070] Furthermore, the antenna element 100 with the CP-type signal wiring 12b preferably also includes the aforementioned first ground layer 42. With this configuration, leakage of the electric field generated between the CP-type signal wiring 12b and the second ground layer 13 to the support substrate 3 can be suppressed, and the occurrence of resonance and / or stray capacitance can be sufficiently suppressed, thereby suppressing variations in antenna characteristics caused by dimensional deviations.

[0071] It should be noted that, although not illustrated, the first ground layer 42 and the second ground layer 13 can be conductive. If the first ground layer 42 and the second ground layer 13 are conductive, grounding can be strengthened, thereby suppressing stray capacitance from surrounding lines or components. In one embodiment, by forming a plurality of vias on the inorganic material substrate 2 and providing a conductor within each via, the first ground layer 42 and the second ground layer 13 are short-circuited.

[0072] In this specification, "antenna element" includes both a wafer (antenna element wafer) having at least one antenna element formed thereon and a chip obtained by cutting the antenna element wafer.

[0073] B. Detailed information on antenna components

[0074] The following is for reference Figure 1 and Figure 2 The details of each component of the antenna element 100 are explained.

[0075] B-1. Inorganic material substrate

[0076] The inorganic material substrate 2 has an upper surface for the first conductor layer 1 to be disposed, and a lower surface located within the antenna element 100. The thickness t of the inorganic material substrate 2 satisfies the above formula (1). In the above formula (1), a preferably represents a value of 6 or more.

[0077] The thickness of the inorganic material substrate 2 is, for example, 1 μm or more, preferably 2 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, particularly preferably 30 μm or more, and especially preferably 40 μm or more. If the thickness of the inorganic material substrate 2 is lower than such a lower limit, the thickness and size of the electrodes constituting the transmission line 12 will be reduced to about a few μm, making it difficult to impedance match with the patch antenna 11. In addition, the tolerance of transmission performance due to manufacturing deviations is sometimes significantly reduced.

[0078] On the other hand, the thickness of the inorganic material substrate 2 is, for example, 500 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and especially preferably 60 μm or less.

[0079] If the thickness of the inorganic material substrate 2 is below such an upper limit, the induction of planar mode and / or resonance of the inorganic material substrate 2 can be stably suppressed. Therefore, the reflection loss of the antenna element 100 during electromagnetic wave transmission and / or reception can be further reduced. As a result, the bandwidth of electromagnetic waves with sufficiently small reflection characteristics (typically -10 dB bandwidth) can be extended in the antenna element 100, thereby enabling further broadbanding of the antenna element 100.

[0080] The relative permittivity ε of the inorganic material substrate 2 at 300 GHz is, for example, 12.0 or less, preferably 10.0 or less, and more preferably 5.0 or less. The lower limit of the relative permittivity ε of the inorganic material substrate 2 at 300 GHz is typically 3.5. The dielectric loss tangent (dielectric loss) tanδ of the inorganic material substrate 2 at 300 GHz is, for example, 0.0030 or less, preferably 0.0020 or less, and more preferably 0.0015 or less.

[0081] If the relative permittivity ε and dielectric loss tangent (tanδ) of the inorganic material substrate 2 are within such a range, the reflection loss in the antenna element 100 can be further reduced. It should be noted that the relative permittivity ε and dielectric loss tangent (tanδ) can be measured, for example, by terahertz time-domain spectrophotometry. Furthermore, in this specification, when the measurement frequency is not mentioned regarding the relative permittivity and dielectric loss tangent, it refers to the relative permittivity and dielectric loss tangent at 300 GHz.

[0082] The inorganic material substrate 2 is composed of inorganic materials. Any suitable material can be used as the inorganic material, as long as the desired effect of the embodiment of the present invention is achieved. Examples of inorganic materials constituting the inorganic material substrate 2 include: single-crystal quartz (relative permittivity 4.5, dielectric loss tangent 0.0013), amorphous quartz (quartz glass, relative permittivity 3.8, dielectric loss tangent 0.0010), spinel (relative permittivity 8.3, dielectric loss tangent 0.0020), AlN (relative permittivity 8.5, dielectric loss tangent 0.0015), sapphire (relative permittivity 9.4, dielectric loss tangent 0.0030), SiC (relative permittivity 9.8, dielectric loss tangent 0.0022), magnesium oxide (relative permittivity 10.0, dielectric loss tangent 0.0012), and silicon (relative permittivity 11.7, dielectric loss tangent 0.0016).

[0083] Among these inorganic materials, amorphous quartz (quartz glass) is a preferred example.

[0084] If the inorganic material substrate 2 is made of quartz glass, the reflection loss in the antenna element 100 can be further reduced more stably. Furthermore, compared to resin-based substrates, it has a larger dielectric constant, thus allowing for a smaller substrate size. Also, the relatively small dielectric constant in inorganic materials is advantageous for reducing delay. Additionally, the first conductor layer 1 (metal layer) can be formed without roughening or surface treatment.

[0085] It should be noted that, although not shown in the figure, the inorganic material substrate 2 can be bent in such a way that the portion overlapping with the cavity 5 when viewed from the thickness direction sinks into the cavity 5.

[0086] B-2. First conductor layer

[0087] In one embodiment, the first conductor layer 1 is disposed on the surface (one side in the thickness direction) of the inorganic material substrate 2 and is in direct contact with the inorganic material substrate 2.

[0088] The first conductor layer 1 is typically made of metal. Examples of metals include chromium (Cr), nickel (Ni), copper (Cu), and gold (Au). Metals can be used alone or in combination. The first conductor layer 1 can be a single layer or formed by stacking two or more layers. The thickness of the first conductor layer 1 is, for example, 1 μm to 20 μm, preferably 4 μm to 10 μm.

[0089] B-3. ​​Supporting substrate

[0090] The support substrate 3 provides excellent strength to the antenna element 100. In the example shown, the support substrate 3 supports the inorganic material substrate 2 through the first ground layer 42 and the joint 6 (described later). This allows the inorganic material substrate 2 to be thinned as described above. The support substrate 3 can have any suitable configuration.

[0091] Examples of materials constituting the support substrate 3 include: indium phosphide (InP), silicon (Si), glass, silicon aluminum oxynitride ceramic (Si3N4-Al2O3), andalusite (3Al2O3·2SiO2, 2Al2O3·3SiO2), aluminum nitride (AlN), magnesium oxide (MgO), aluminum oxide (Al2O3), spinel (MgAl2O4), sapphire, quartz, crystal, gallium nitride (GaN), silicon carbide (SiC), silicon nitride (Si3N4), and gallium oxide (Ga2O3).

[0092] The thermal conductivity of the material constituting the support substrate 3 is preferably 150 W / km or more, and more preferably 200 W / km or more.

[0093] When the antenna element 100 is connected to an external device (e.g., an amplifier), the inorganic material substrate 2 may be heated by the external device, and the heat from the inorganic material substrate 2 may adversely affect the external device. In this regard, if the material constituting the support substrate 3 has the aforementioned thermal conductivity, the support substrate 3 can function as a heat sink to effectively dissipate the heat from the inorganic material substrate 2.

[0094] From the viewpoint of thermal conductivity, the following materials are preferably used to form the support substrate 3: silicon (thermal conductivity: about 160 W / Km), silicon carbide (thermal conductivity: about 270 W / Km), and aluminum nitride (thermal conductivity: about 150 W / Km to 250 W / Km).

[0095] Furthermore, it is ideal for the linear expansion coefficient of the material constituting the support substrate 3 to be closer to that of the material constituting the inorganic material substrate 2. For example, the linear expansion coefficient of the material constituting the support substrate 3 is in the range of 50% to 150% relative to the linear expansion coefficient of the material constituting the inorganic material substrate 2. If the linear expansion coefficient of the material constituting the support substrate 3 is within such a range, thermal deformation (typically warping) of the antenna element 100 can be suppressed.

[0096] Among the materials constituting such a support substrate 3, indium phosphide, silicon, aluminum nitride, gallium nitride, silicon carbide, and silicon nitride are preferred, silicon, aluminum nitride, gallium nitride, silicon carbide, and silicon nitride are more preferred, and silicon is especially preferred.

[0097] like Figure 2 As shown, in one embodiment, the support substrate 3 has a recess 31 corresponding to the cavity portion 5.

[0098] Typically, the recess 31 is recessed downwards (away from the inorganic material substrate 2) from the upper surface of the support substrate 3 (the surface on the side of the inorganic material substrate 2). When viewed from the thickness direction of the inorganic material substrate 2, the recess 31 has the same shape as the cavity 5 described above. In the example shown, the recess 31 has a generally U-shaped opening towards the inorganic material substrate 2 in the cross-section obtained by cutting the support substrate 3 along the thickness direction. The inner surface of the recess 31 includes a side surface and a bottom surface. The side surface of the recess 31 extends along the thickness direction of the inorganic material substrate 2. The direction in which the side surface of the recess 31 extends can be exactly the same as (i.e., parallel) to the thickness direction of the inorganic material substrate 2, or it can be slightly inclined relative to the thickness direction of the inorganic material substrate 2. The bottom surface of the recess 31 extends in a direction intersecting (typically orthogonal) the thickness direction of the inorganic material substrate 2.

[0099] B-4. Second conductor layer

[0100] In one embodiment, the antenna element 100 further includes a second conductor layer 4 comprising a ground conductor layer 41. The second conductor layer 4 is disposed between the inorganic material substrate 2 and the support substrate 3. The second conductor layer 4 is typically disposed on the upper surface of the support substrate 3 (the surface on the side of the inorganic material substrate 2) and is in direct contact with the support substrate 3.

[0101] In the example shown, the ground conductor layer 41 included in the second conductor layer 4 is located within the recess 31 of the supporting substrate 3. The ground conductor layer 41 is at least disposed on the bottom surface of the recess 31. In the example shown, the ground conductor layer 41 is disposed on the entire inner surface of the recess 31. Thus, at least a portion of the ground conductor layer 41 is disposed opposite to the patch antenna 11 in the thickness direction of the inorganic material substrate 2. Therefore, an electric field can be stably generated between the patch antenna 11 and the ground conductor layer 41.

[0102] In one embodiment, the second conductor layer 4 further includes a first ground layer 42. The first ground layer 42 can be disposed at any suitable location, provided it overlaps with at least a portion of the projection surface of the transmission line 12 as described above. The first ground layer 42 is disposed on the upper surface of the support substrate 3 (the surface on the inorganic material substrate 2 side) excluding the recess 31. The first ground layer 42 can be partially disposed on the upper surface of the support substrate 3 excluding the recess 31 (see reference). Figure 7 Alternatively, it can be disposed on the entire upper surface of the support substrate 3, excluding the recess 31 (see reference). Figure 8 ).

[0103] like Figure 8 As shown, in one embodiment, the first ground layer 42 is disposed on the entire upper surface of the support substrate 3, excluding the recess 31. In the example shown, the first ground layer 42 and the ground conductor layer 41 are continuous with each other. If the ground conductor layer 41 and the first ground layer 42 are continuous with each other to form the second conductor layer 4, the grounding function is stable throughout the substrate, and the design and manufacture of the antenna element 100 can be facilitated.

[0104] The second conductor layer 4 is, for example, made of the same metal as the first conductor layer 1.

[0105] Typically, the thickness of the second conductor layer 4 is less than the thickness of the first conductor layer 1. The thickness of the second conductor layer 4 is, for example, 1 nm to 30 μm, preferably 10 nm to 10 μm.

[0106] B-5. Joint

[0107] like Figure 1 and Figure 2 As shown, in one embodiment, the antenna element 100 further includes a bonding portion 6. The bonding portion 6 bonds the inorganic material substrate 2 and the support substrate 3. In the example shown, the bonding portion 6 bonds the inorganic material substrate 2 and the support substrate 3 on which the first ground layer 42 is provided, and is located between the inorganic material substrate 2 and the first ground layer 42.

[0108] The joint 6 can be made of organic materials (typically organic adhesives) or inorganic materials.

[0109] In one embodiment, the bonding portion 6 is made of an inorganic material. Examples of inorganic materials constituting the bonding portion 6 include SiO2, amorphous silicon, and tantalum oxide, with amorphous silicon being the most preferred. The thickness of the bonding portion 6 is, for example, 0.001 μm to 10 μm, and preferably 0.01 μm to 3 μm.

[0110] In one embodiment, the inorganic material substrate 2 and the support substrate 3 on which the first ground layer 42 is formed are directly bonded. This forms a bonding portion 6 between the inorganic material substrate 2 and the first ground layer 42. In this specification, "direct bonding" means that the two layers or substrates are bonded without any organic material (typically an organic adhesive). The form of direct bonding can be appropriately set according to the configuration of the layers or substrates being bonded. Furthermore, the interface bonded by direct bonding is typically amorphous. Therefore, the thermal resistance of the bonding interface can be significantly reduced compared to resin bonding. Thus, when the antenna element 100 is connected to an external device, even if heat generated from the external device is transferred to the inorganic material substrate 2, such heat can be easily escaped from the inorganic material substrate 2 to the package via the support substrate 3. As a result, the inorganic material substrate 2 can efficiently dissipate heat, thereby suppressing the degradation of the external device's characteristics.

[0111] Furthermore, by integrating them using direct bonding, peeling in the antenna element 100 can be well suppressed, resulting in good suppression of damage (e.g., cracks) to the inorganic material substrate 2 caused by such peeling.

[0112] Furthermore, by integrating them through direct bonding without the aid of resin, the heat resistance and chemical resistance in subsequent manufacturing processes can be improved, thereby suppressing the deterioration of antenna characteristics caused by heat or moisture absorption on the antenna element 100.

[0113] The joint 6 can have a single-layer structure or a multi-layer structure. For example... Figure 2 As shown, in one embodiment, the joint 6 has a layered structure. The joint 6 includes a first joint layer 61 and a second joint layer 62.

[0114] A first bonding layer 61 is disposed on the surface of the inorganic material substrate 2. More specifically, the first bonding layer 61 is disposed on the surface of the inorganic material substrate 2 opposite to the first conductor layer 1 in the thickness direction of the inorganic material substrate 2. In the example shown, the first bonding layer 61 is disposed on the lower surface of the inorganic material substrate 2 (the surface opposite to the first conductor layer 1) and is in direct contact with the inorganic material substrate 2. The first bonding layer 61 may be partially disposed on the lower surface of the inorganic material substrate 2 or may be disposed on the entire lower surface of the inorganic material substrate 2. In the example shown, the first bonding layer 61 is disposed on the entire lower surface of the inorganic material substrate 2.

[0115] The thickness of the first bonding layer 61 is, for example, 0.5 nm to 5 μm, preferably 0.01 μm to 1.5 μm, and more preferably 0.01 μm to 0.05 μm.

[0116] The second bonding layer 62 is disposed on the surface of the first ground layer 42. More specifically, the second bonding layer 62 is disposed on the surface of the first ground layer 42 opposite to the supporting substrate 3 in the thickness direction of the inorganic material substrate 2. In the example shown, the second bonding layer 62 is disposed on the upper surface of the first ground layer 42 (the surface opposite to the supporting substrate 3) and is in direct contact with the first ground layer 42. The second bonding layer 62 may be disposed only on the first ground layer 42, or it may be disposed on both the first ground layer 42 and the ground conductor layer 41. In the example shown, the second bonding layer 62 is disposed on the entire upper surface of both the ground conductor layer 41 and the first ground layer 42. In other words, the second bonding layer 62 is stacked on the entire second conductor layer 4.

[0117] The thickness range of the second bonding layer 62 is, for example, the same as the thickness range of the first bonding layer 61 described above.

[0118] The second bonding layer 62 is bonded to the first bonding layer 61 and is integrated with the first bonding layer 61. In the example shown, the portion of the second bonding layer 62 located on the first ground layer 42 is directly bonded to the first bonding layer 61.

[0119] It should be explained that, for example Figure 9 As shown, the second conductor layer 4 may not include the first ground layer 42, and may consist only of the ground conductor layer 41. In this case, although not shown, the joint 6 is located between the portion of the upper surface of the support substrate 3 excluding the recess 31 and the inorganic material substrate 2, thereby joining them together.

[0120] B-6. Cavity

[0121] like Figure 2 As shown, in one embodiment, the void portion 5 is located inside the region surrounded by the inorganic material substrate 2 and the ground conductor layer 41. The void portion 5 is formed by a groove formed in the support substrate 3. The void portion 5 is defined by a first bonding layer 61 provided on the lower surface of the inorganic material substrate 2 or on the lower surface of the inorganic material substrate 2, and a second bonding layer 62 provided on the upper surface of the ground conductor layer 41 or on the upper surface of the ground conductor layer 41. In the example shown, the void portion 5 is defined by the first bonding layer 61 provided on the lower surface of the inorganic material substrate 2 and the second bonding layer 62 provided on the upper surface of the ground conductor layer 41.

[0122] Air is typically present in the cavity 5. In another embodiment, the cavity 5 is in a vacuum state.

[0123] The dimension d (hereinafter referred to as depth d) of the cavity 5 in the thickness direction of the inorganic material substrate 2 is arbitrarily and appropriately varied according to the configuration of the antenna element 100 and the frequency of the electromagnetic waves transmitted and / or received by the antenna element 100. The depth d of the cavity 5 is, for example, 1 μm to 250 μm. It should be noted that the depth d of the cavity 5 refers to the distance between the lower surface of the inorganic material substrate 2 (the surface opposite to the first conductor layer 1) and the upper surface of the ground conductor layer 41 (the surface opposite to the support substrate 3) in the thickness direction of the inorganic material substrate 2.

[0124] In one embodiment, the patch antenna 11 is rectangular in shape, and when the antenna element 100 transmits and receives electromagnetic waves with a frequency of 100 GHz to 200 GHz, the depth d of the cavity 5 is, for example, 5 μm to 250 μm.

[0125] In another embodiment, the patch antenna 11 is rectangular in shape, and when the antenna element 100 transmits and receives electromagnetic waves with a frequency of 250 GHz to 350 GHz, the depth d of the cavity 5 is, for example, 5 μm to 200 μm.

[0126] C. Antenna element manufacturing methods

[0127] Next, refer to Figure 2 One embodiment of the manufacturing method of antenna element 100 will be described.

[0128] In one embodiment, firstly, a support substrate 3 having a recess 31 is prepared. For example, the recess 31 is formed on the support substrate 3 using reactive ion etching.

[0129] Next, a second conductor layer 4 is formed on the upper surface of the support substrate 3 where the recess 31 is formed. Any suitable film-forming method can be used. Examples of film-forming methods include sputtering, deposition, and vapor deposition; deposition is preferred.

[0130] Next, an inorganic material substrate 2 is prepared, and the inorganic material substrate 2 and the support substrate 3 are directly bonded. More specifically, a first bonding layer 61 is formed on the lower surface of the inorganic material substrate 2. Additionally, a second bonding layer 62 is formed on the upper surface of the second conductor layer 4. Methods for forming these layers include, for example, sputtering, deposition, and vapor deposition; sputtering is preferred. The surfaces of the first bonding layer 61 and the second bonding layer 62 are planarized as needed using grinding.

[0131] Direct bonding can be achieved, for example, using the following sequence. In a high-vacuum chamber (e.g., 1×10⁻⁶), -6(Approximately Pa) irradiates the bonding surfaces of the constituent elements (layers or substrates) to be bonded with a neutral beam. In one embodiment, during surface activation using a neutral beam, an inert gas is introduced into the chamber, and a high voltage is applied from a DC power supply to the electrodes disposed within the chamber. With this configuration, electrons move due to the electric field generated between the electrodes (positive electrode) and the chamber (negative electrode), generating a beam of atoms and ions originating from the inert gas. The ion beam reaching the gate is neutralized at the gate, thus the beam of neutral atoms is emitted from the high-speed atomic beam source. The atomic species constituting the beam are preferably inert gas elements (e.g., argon (Ar), nitrogen (N)). The voltage for activation using beam irradiation is, for example, 0.5 kV to 2.0 kV, and the current is, for example, 50 mA to 200 mA. The irradiation time of the neutral beam is, for example, 10 seconds to 300 seconds, preferably 30 seconds to 120 seconds.

[0132] As a result, the inorganic materials present at each interface, and more specifically at the beam irradiation surface, are activated.

[0133] Next, in a vacuum atmosphere at room temperature (23°C), the activated bonding surfaces are brought into contact with each other. The load at this contact can be, for example, 100N to 20000N. Thus, the first bonding layer 61 and the second bonding layer 62 are bonded together to form a joint 6.

[0134] Thus, a laminate having a structure of inorganic material substrate 2 / bonding portion 6 / second conductor layer 4 / support substrate 3 is obtained. It should be noted that the direct bonding method is not limited to this, and surface activation methods based on FAB (Fast Atom Beam) or ion guns, atomic diffusion methods, plasma bonding methods, etc., can also be applied.

[0135] The laminate is subjected to heat treatment as needed. This improves the bonding strength between the inorganic material substrate and the support substrate. The heating temperature is, for example, 60°C to 140°C, preferably 80°C to 120°C. The heating time is, for example, 10 minutes to 5 hours, preferably 30 minutes to 3 hours.

[0136] Next, the inorganic material substrate 2 is ground as needed to achieve the aforementioned thickness, thus thinning the wall. Chemical mechanical polishing (CMP) is an example of such a grinding method.

[0137] Next, a first conductor layer 1 is formed on the upper surface of the inorganic material substrate 2. In one embodiment, after forming a photoresist having openings corresponding to the first conductor layer on the upper surface of the inorganic material substrate 2, the first conductor layer is formed using the photoresist. Methods for forming the metal film include, for example, sputtering, deposition, and vapor deposition; deposition is preferred.

[0138] Through the above operations, an antenna element 100 having a structure of a first conductor layer 1 / inorganic material substrate 2 / joint portion 6 / second conductor layer 4 / support substrate 3 is manufactured, and the antenna element 100 including the cavity portion 5 is also manufactured.

[0139] Antenna element 100 like this can be applied to any suitable optical device (e.g., waveguide element, electromagnetic wave sensor). In particular, antenna element 100 broadbands the available electromagnetic waves, thus making it well-suited for human body sensing sensors requiring excellent resolution. If the aforementioned antenna element 100 is applied to a human body sensing sensor, human movements (postures) can be monitored with high accuracy. Examples of human body sensing sensors include: vehicle posture monitoring sensors and human-machine interface (HMI) posture monitoring sensors.

[0140] Example

[0141] The present invention will be specifically described below through embodiments; however, the present invention is not limited to these embodiments.

[0142] <Example 1>

[0143] A 0.5 mm thick quartz glass wafer (inorganic material substrate) was prepared. A 0.02 μm amorphous silicon film (first bonding layer) was formed on the surface of the inorganic material substrate using sputtering. After film formation, the first bonding layer was polished to perform planarization. Here, the arithmetic mean roughness of the surface of the first bonding layer within 10 μm was measured using atomic force microscopy, and the result was 0.2 nm.

[0144] In addition, a silicon wafer (support substrate) with a thickness of 250 μm is prepared. Next, a recess is formed on the upper surface of the support substrate by reactive ion etching. When viewed from the thickness direction of the support substrate, the recess has a roughly rectangular shape. The dimension of the recess in the long side direction is 1100 μm, the dimension of the recess in the short side direction is 720 μm, and the depth of the recess is 175 μm.

[0145] Next, a gold film (second conductor layer) with a thickness of 1 μm is formed on the upper surface of the support substrate in which the recess is formed by sputtering. The second conductor layer integrally comprises: a ground conductor layer located in the recess, and a first ground layer located on the upper surface of the support substrate excluding the recess.

[0146] Next, a 0.02 μm amorphous silicon film (second bonding layer) was formed on the second conductor layer by sputtering. After film formation, the second bonding layer was polished to perform planarization. Here, the arithmetic mean roughness of the surface of the second bonding layer within 10 μm was measured using atomic force microscopy, and the result was 0.2 nm.

[0147] Next, the inorganic material substrate and the support substrate are directly bonded as follows. First, the inorganic material substrate with the first bonding layer formed and the support substrate with the second bonding layer and the second conductor layer formed are placed in a vacuum chamber, and then bonded at 10°C. -6 In a vacuum of approximately Pa, the bonding surfaces of the two substrates (the surfaces of the first and second bonding layers) were irradiated with a high-speed Ar neutral atom beam (accelerating voltage 1 kV, Ar flow rate 60 sccm) for 70 seconds. After irradiation, the substrates were left to cool for 10 minutes. Then, the surfaces of the first and second bonding layers (the irradiated surfaces) were brought into contact, and a pressure of 4.90 kN was applied for 2 minutes to bond the inorganic material substrate and the support substrate. In other words, the inorganic material substrate and the support substrate were directly bonded together using the bonding portion and the second conductor layer. After bonding, the inorganic material substrate was ground to a thickness of 50 μm.

[0148] Next, a photoresist is applied to the surface (polished surface) of the inorganic material substrate opposite to the bonding portion, and patterned by photolithography to expose the portion where the first conductor layer will be formed. Then, a copper film (first conductor layer) with a thickness of 5 μm is formed on the upper surface of the inorganic material substrate exposed from the photoresist by sputtering. Finally, the photoresist is removed.

[0149] The first conductor layer includes a patch antenna and MS-type signal wiring. Viewed from the thickness direction of the inorganic material substrate, the patch antenna has a roughly rectangular shape. The length of the patch antenna ( Figure 1 The direction orthogonal to the II-II' direction is 860 μm, and the width of the patch antenna ( Figure 1 The width of the line in the II-II' direction is 590μm. The MS type signal wiring consists of a wide section and a narrow section, and the line width of each section is set such that the impedance can be matched with 50Ω.

[0150] Through the above operations, we obtain Figure 1 The antenna element shown is a structure consisting of a first conductor layer, an inorganic material substrate, a bonding portion, a second conductor layer, and a supporting substrate. This antenna element has a cavity corresponding to the recess. When the patch antenna is projected along the thickness direction of the inorganic material substrate, the entire projection plane of the patch antenna overlaps with the cavity. The projection plane of the patch antenna is 507400 μm. 2 The projected area of ​​the cavity is 792,000 μm. 2 .

[0151] <Comparative Example 1>

[0152] No recesses are formed in the supporting substrate; otherwise, the antenna element is obtained in the same manner as in Embodiment 1. This antenna element does not have any voids.

[0153] <Determination of S11 parameters>

[0154] For the antenna elements obtained in the embodiments and comparative examples, a network analyzer was used to measure the S11 parameter, which represents reflection loss, with the sampling frequency set to 120 GHz. The results are shown below. Figure 10 and Figure 11 .

[0155] Depend on Figure 10 It can be seen that when the antenna element has a cavity, the S11 parameter of the antenna element reaches a bandwidth of 10.2 GHz for electromagnetic waves below -10 dB (-10 dB bandwidth). On the other hand, as... Figure 11 As shown, the -10dB bandwidth of an antenna element without a cavity is 4.9GHz. Therefore, it can be concluded that if an antenna element has a cavity, the antenna element can be broadbanded.

[0156] Industrial availability

[0157] The antenna elements described in the embodiments of the present invention can be used in a wide range of fields such as next-generation high-speed communications and sensors, and in particular, they can be well used as human body sensing sensors.

[0158] Explanation of reference numerals in the attached figures

[0159] 1 First conductor layer

[0160] 11 Patch Antenna

[0161] 12 Transmission Lines

[0162] 2 Inorganic material substrates

[0163] 3 Supporting substrate

[0164] 31 recess

[0165] 4 Second conductor layer

[0166] 41 Grounding conductor layer

[0167] 5. Cavity

[0168] 6. Joint

[0169] 61 First bonding layer

[0170] 62 Second bonding layer

[0171] 100 antenna elements

Claims

1. An antenna element comprising: Inorganic material substrates; A first conductor layer is disposed on one side of the inorganic material substrate in the thickness direction, and the first conductor layer includes a patch antenna. A support substrate, which is disposed on the opposite side of the first conductor layer relative to the inorganic material substrate; A void portion, which is disposed on the side opposite to the first conductor layer and disposed on the inorganic material substrate side of the support substrate; as well as A grounding conductor layer is disposed within the cavity, and this grounding conductor layer is capable of generating an electric field between itself and the patch antenna. The thickness t of the inorganic material substrate satisfies the following formula (1). When the patch antenna is projected along the thickness direction of the inorganic material substrate, at least a portion of the projection surface of the patch antenna overlaps with the void portion: [Mathematical Expression 1] In the formula, t represents the thickness of the inorganic material substrate, λ represents the wavelength of the electromagnetic waves transmitted and / or received in the antenna element, ε represents the relative permittivity of the inorganic material substrate, and a represents a value greater than 3.

2. The antenna element according to claim 1, wherein, When the patch antenna is projected along the thickness direction of the inorganic material substrate, the entire projection surface of the patch antenna overlaps with the cavity.

3. The antenna element according to claim 1 or 2, wherein, The first conductor layer also includes a transmission line connected to the patch antenna.

4. The antenna element according to claim 3, wherein, The antenna element further includes a first ground layer, which is disposed between the inorganic material substrate and the supporting substrate at a location different from the void portion. When the transmission line is projected along the thickness direction of the inorganic material substrate, at least a portion of the projection surface of the transmission line overlaps with the first ground layer.

5. The antenna element according to claim 4, wherein, The antenna element also includes a bonding portion that bonds the inorganic material substrate and the support substrate.

6. The antenna element according to claim 5, wherein, The joint includes: A first bonding layer is disposed on the surface of the inorganic material substrate on the side opposite to the first conductor layer in the thickness direction of the inorganic material substrate; and A second bonding layer is disposed on the surface of the first ground layer on the side opposite to the supporting substrate in the thickness direction of the inorganic material substrate. The second bonding layer is bonded to the first bonding layer.

7. The antenna element according to claim 1 or 2, wherein, The thickness t of the inorganic material substrate is less than 100 μm.

8. The antenna element according to claim 1 or 2, wherein, The frequency of the electromagnetic waves transmitted and / or received in the antenna element is 20 GHz to 20 THz.

9. The antenna element according to claim 1 or 2, wherein, The inorganic material substrate is made of quartz glass.

10. The antenna element according to claim 1 or 2, wherein, The supporting substrate is made of silicon.

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