Antenna device

Abstract

An antenna device capable of usefully broadening a band of electromagnetic waves is provided. An antenna device according to an embodiment of the present invention includes an inorganic material substrate, a first conductor layer, a support substrate, a cavity portion, and a ground conductor layer. The first conductor layer is disposed on one side of the inorganic material substrate in a thickness direction of the inorganic material substrate and includes a patch antenna. The support substrate is disposed on a side opposite to the first conductor layer with respect to the inorganic material substrate. The cavity portion is disposed on the side of the inorganic material substrate opposite to the first conductor layer and is disposed on the inorganic material substrate side of the support substrate. The ground conductor layer is disposed in the cavity portion.The thickness "t" of the inorganic material substrate satisfies the following expression (1). When the patch antenna is projected in the thickness direction of the inorganic material substrate, at least a part of a projection surface of the patch antenna overlaps with the cavity portion. t < λ a ε

Description

Technical field

[0001] The present invention relates to an antenna device. Technical background

[0002] Until now, an electromagnetic wave sensor has been known that transmits an electromagnetic wave to an object to be detected and receives a wave reflected from the object to detect the object. An antenna device capable of transmitting and / or receiving an electromagnetic wave is typically employed in such an electromagnetic wave sensor. As an example of the antenna device, for example, a single antenna is proposed that includes a dielectric substrate, a signal conversion section disposed on the front surface of the dielectric substrate, and a ground plate disposed on the back surface of the dielectric substrate (see Patent Document 1). Citation listPatent literature

[0003] [PTL 1] JP 6955590 B2 Brief description of the inventionTechnical problem

[0004] In recent years, the applications of electromagnetic wave sensors have expanded, and the use of electromagnetic wave sensors as presence sensors is being considered. However, when the single antenna described in Patent Literature 1 is used for the presence sensor, the resolution required for the presence sensor cannot be sufficiently achieved. The resolution of the electromagnetic wave sensor depends on the width of a frequency range (hereinafter referred to as the "band") of electromagnetic waves that can be used in the antenna device. Therefore, it is expected that the band of electromagnetic waves that can be used by the antenna device will be broadened.

[0005] A main object of the present invention is to provide an antenna device with which it is possible to broaden a band of electromagnetic waves that can be used. Solution to the problem

[0006] [1] An antenna device according to an embodiment of the present invention includes an inorganic material substrate, a first conductor layer, a support substrate, a cavity portion, and a ground conductor layer. The first conductor layer is disposed on one side of the inorganic material substrate in a thickness direction of the inorganic material substrate. The first conductor layer includes a patch antenna. The support substrate is disposed on a side opposite to the first conductor layer with respect to the inorganic material substrate. The cavity portion is disposed on the side opposite to the first conductor layer with respect to the inorganic material substrate and is disposed on the inorganic material substrate side of the support substrate. The ground conductor layer is disposed in the cavity portion.The ground conductor layer is capable of generating an electric field between the ground conductor layer and the patch antenna. The thickness "t" of the inorganic material substrate satisfies expression (1) given below. When the patch antenna is projected in the thickness direction of the inorganic material substrate, at least a part of a projection surface of the patch antenna overlaps with the cavity portion: t<λaε where “t” represents the thickness of the inorganic material substrate, λ represents a wavelength of an electromagnetic wave transmitted and / or received by the antenna device, ε represents a relative dielectric constant of the inorganic material substrate, and “a” represents a numerical value of 3 or more.

[0007] [2] In the antenna device according to the above-mentioned item [1], when the patch antenna is projected in the thickness direction of the inorganic material substrate, the entire projection surface of the patch antenna in the antenna device can overlap with the cavity portion.

[0008] [3] In the antenna device according to the above-mentioned item [1] or [2], the first conductor layer may further include a transmission line. The transmission line is connected to the patch antenna.

[0009] [4] The antenna device according to the above-mentioned item [3] may further include a first ground layer. The first ground layer is disposed between the inorganic material substrate and the support substrate, and in a portion other than the cavity portion. When the transmission line is projected in the thickness direction of the inorganic material substrate, at least a portion of a projection surface of the transmission line overlaps with the first ground layer.

[0010] [5] The antenna device according to the above-mentioned item [4] may further include a connecting portion. The connecting portion is configured to connect the inorganic material substrate and the support substrate.

[0011] [6] In the antenna device according to the above-mentioned item [5], the connecting portion may include a first connecting layer and a second connecting layer. The first connecting layer is disposed on a surface of the inorganic material substrate on the opposite side to the first conductor layer in the thickness direction of the inorganic material substrate. The second connecting layer is disposed on a surface of the first grounding layer on a side opposite to the support substrate in the thickness direction of the inorganic material substrate. The second connecting layer is connected to the first connecting layer.

[0012] [7] In the antenna device according to any one of the above-mentioned items [1] to [6], the thickness “t” of the inorganic material substrate may be 100 µm or less.

[0013] [8] In the antenna device according to any one of the above-mentioned items [1] to [7], a frequency of the electromagnetic wave transmitted and / or received by the antenna device may be from 20 GHz to 20 THz.

[0014] [9] In the antenna device according to any one of the above-mentioned items [1] to [8], the inorganic material substrate may be formed of quartz glass.

[0015]

[10] In the antenna device according to any one of the above-mentioned items [1] to [9], the support substrate may be constructed of silicon. Advantageous effects of the invention

[0016] According to the embodiments of the present invention, it is possible to broaden the band of electromagnetic waves that can be used. Brief description of the drawings Fig. 1 is a schematic perspective view of an antenna device according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of the antenna device along the line II-II' of Fig. 1. Fig. 3 is a schematic perspective view of an antenna device according to another embodiment of the present invention. Fig. 4 is a schematic perspective view of an antenna device according to another embodiment of the present invention. Fig. 5 is a schematic perspective view of an antenna device according to another embodiment of the present invention. Fig. 6 is a schematic perspective view of an antenna device according to another embodiment of the present invention. Fig. 7 is a schematic perspective view of a support substrate and a second conductor layer used in the antenna device of Fig. 1 are included. Fig. Fig. 8 is a schematic perspective view illustrating another embodiment of the second conductor layer of Fig. 7. Fig. 9 is a schematic perspective view illustrating another embodiment of the second conductor layer of Fig. 7. Fig. 10 is a diagram showing an S11 parameter in an antenna device of Example 1. Fig. 11 is a diagram showing an S11 parameter in an antenna device of Comparative Example 1. Description of the embodiments

[0017] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the drawings may be schematically illustrated with respect to the width, thickness, shape, and the like of each component in comparison with the embodiments to clarify the description, but this is only an example and does not limit the scope of the present invention. A. Overall configuration of the antenna device

[0018] Fig. 1 is a schematic perspective view of an antenna device according to an embodiment of the present invention and Fig. 2 is a cross-sectional view of the antenna device along the line II-II' of Fig. 1.

[0019] An antenna device 100 is typically capable of transmitting and / or receiving an electromagnetic wave that is a millimeter wave / terahertz wave. The "millimeter wave" is typically an electromagnetic wave having a frequency of about 20 GHz to about 300 GHz, and the "terahertz wave" is typically an electromagnetic wave having a frequency of about 300 GHz to about 20 THz.

[0020] A frequency of the electromagnetic wave that can be transmitted and / or received by the antenna device is, in one example, from 20 GHz to 20 THz, in another example, from 20 GHz to 500 GHz, in another example, from 20 GHz to 300 GHz, and in another example, from 100 GHz to 200 GHz.

[0021] The antenna device 100 includes an inorganic material substrate 2, a first conductor layer 1, a support substrate 3, a cavity portion 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 of the inorganic material substrate 2. The first conductor layer 1 includes a patch antenna 11. The support substrate 3 is disposed on a side 1 opposite the first conductor layer with respect to the inorganic material substrate 2. The cavity portion 5 is disposed on the side 1 opposite the first conductor layer with respect to the inorganic material substrate 2 and on the inorganic material substrate side of the support substrate 3. The ground conductor layer 41 is disposed in the cavity portion 5.The patch antenna 11, the ground conductor layer 41, and the inorganic material substrate 2 therebetween typically constitute a planar antenna. The ground conductor layer 41 is capable of generating an electric field between the ground conductor layer 41 and the patch antenna 11. More specifically, when the patch antenna 11 receives and / or transmits the above-mentioned high-frequency electromagnetic wave, the ground conductor layer 41 generates the electric field between the patch antenna 11 and the ground conductor layer 41. A thickness "t" of the inorganic material substrate 2 satisfies expression (1) given below. When the patch antenna 11 is projected in the thickness direction of the inorganic material substrate 2, at least a part of a projection surface of the patch antenna 11 overlaps with the cavity portion 5:. t<λaε where “t” represents the thickness of the inorganic material substrate 2, λ represents a wavelength of the electromagnetic wave transmitted and / or received by the antenna device 100, ε represents a relative dielectric constant of the inorganic material substrate 2, and “a” represents a numerical value of 3 or more.

[0022] With such a configuration, the thickness of the inorganic material substrate 2 satisfies the aforementioned expression (1), and therefore, even in a case where the antenna device 100 transmits and / or receives the aforementioned high-frequency electromagnetic wave, the induction of a slab mode can be suppressed, and the resonance of the inorganic material substrate 2 can be suppressed. Further, when the patch antenna 11 is projected in the thickness direction of the inorganic material substrate 2, at least a part of the projection surface of the patch antenna 11 overlaps with the cavity portion 5, and therefore, the frequency band (resonance frequencies) that can resonate between the patch antenna 11 and the ground conductor layer 41 can be broadened, and as a result, the frequency band radiated from the antenna device 100 can be broadened.

[0023] With these effects, the return loss of the electromagnetic wave can be sufficiently reduced in the antenna device 100. As a result, the bandwidth of the electromagnetic wave in which the return loss is sufficiently small, that is, the bandwidth of the electromagnetic wave in which an S11 parameter representing the return loss has a predetermined value or less, can be broadened in the antenna device 100. In short, the antenna device 100 can function as a broadband antenna.

[0024] In one embodiment, the bandwidth of the electromagnetic wave in which the S11 parameter of the antenna device 100 (return loss) is -10 dB or less (-10 dB bandwidth) is, for example, 5.0 GHz or more, preferably 8.0 GHz or more, more preferably 10.0 GHz or more, even more preferably 13.0 GHz or more.

[0025] The upper limit of the -10 dB bandwidth of the antenna device 100 is typically 50 GHz. The S11 parameter is measured, for example, with a network analyzer.

[0026] Furthermore, the antenna device 100 is being developed to be miniaturized and is expected to integrate circuits in the future, and therefore, it is predicted that concomitant miniaturization of the antenna device 100 will also be required. In the antenna device 100 described above, the thickness of the inorganic material substrate 2 satisfies the aforementioned expression (1), and thinning of the inorganic material substrate 2 is achieved, and thus, the demand for miniaturization can also be met while broadening the band to be used in the antenna device 100.

[0027] An area ratio of the part of the above-mentioned projection surface of the patch antenna 11 that overlaps with the cavity portion 5 is, for example, 70% or more, preferably 80% or more, more preferably 90% or more. When the projection surface of the patch antenna 11 overlaps the cavity portion 5 with the above-mentioned area ratio, it is possible to stably broaden the band to be used in the antenna device 100.

[0028] In one embodiment, the entire projection surface of the patch antenna 11 overlaps with the cavity portion 5 when the patch antenna 11 is projected in the thickness direction of the inorganic material substrate 2. In other words, 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 such a configuration, it is possible to stably broaden the band to be used in the antenna device 100.

[0029] In one embodiment, when both the patch antenna 11 and the cavity portion 5 are projected in the thickness direction of the inorganic material substrate 2, the projected area of ​​the cavity portion 5 is equal to or greater than the projected area of ​​the patch antenna 11. The projected area of ​​the cavity portion 5 is, for example, one to four times the projected area of ​​the patch antenna 11, preferably one to three times the projected area of ​​the patch antenna 11. When the projected area of ​​the cavity portion 5 is in such a relationship to the projected area of ​​the patch antenna 11, the patch antenna 11 can be easily positioned so that the patch antenna 11 overlaps the cavity portion 5 when viewed from the thickness direction of the inorganic material substrate 2.In this way, it is possible to increase the degree of freedom in the design of the patch antenna 11 and it is also possible to broaden the band to be used in the antenna device 100 more stably.

[0030] In the illustrated example, when both the patch antenna 11 and the cavity portion 5 are projected in the thickness direction of the inorganic material substrate 2, an outer edge of the projection surface of the cavity portion 5 is arranged at a distance from an outer edge of the projection surface of the patch antenna 11. As in Fig. 2, in a direction perpendicular to the outer edge of the projection surface of the patch antenna 11, a distance L between the outer edge of the projection surface of the cavity portion 5 and the outer edge of the projection surface of the patch antenna 11 is 0 μm to λ / 2ε μm in one example and 0 μm to λ / 4ε μm in another example, where ε represents the relative dielectric constant of the inorganic material substrate 2. When the distance L between the outer edge of the cavity portion 5 and the outer edge of the patch antenna 11 falls within such a range, it is possible to further increase the degree of freedom in the design of the patch antenna 11, and it is also possible to further stably broaden the band to be used in the antenna device 100.

[0031] As in Fig. 1, the patch antenna 11 has any suitable shape. Examples of the shape of the patch antenna 11, as viewed from the thickness direction of the inorganic material substrate 2, include a triangle, a quadrilateral, a pentagon, a substantially polygon with six or more sides, a substantially circular shape, and a substantially oval shape. In the illustrated example, the patch antenna 11 has a substantially rectangular shape as viewed in the thickness direction of the inorganic material substrate 2.

[0032] The cavity portion 5 has any suitable shape. Examples of the shape of the cavity portion 5 viewed in the thickness direction of the inorganic material substrate 2 include the same shapes as the aforementioned shapes of the patch antenna 11.

[0033] In one embodiment, the cavity portion 5 has a similar shape to the patch antenna 11, viewed from the thickness direction of the inorganic material substrate 2. In the illustrated example, the cavity portion 5 and the patch antenna 11 have similar shapes, and a center of the patch antenna 11 and a center of the cavity portion 5 are arranged on the same axis along the thickness direction of the inorganic material substrate 2.

[0034] In one embodiment, the first conductor layer 1 includes a transmission line 12 in addition to the patch antenna 11. The transmission line 12 is connected to the patch antenna 11. An end portion of the transmission line 12 on the opposite side from the patch antenna 11 is typically configured to be connected to an external device. With such a configuration, an electrical signal input from the external device can be supplied to the patch antenna 11 via the transmission line 12. When the 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. Accordingly, the patch antenna 11 can transmit the electromagnetic wave converted from the electrical signal.When the patch antenna 11 continues to receive an electromagnetic wave, the patch antenna 11 and the ground conductor layer 41 can convert the electromagnetic wave into an electrical signal. Accordingly, the antenna device 100 can transmit the electrical signal converted from the electromagnetic wave to the external device via the transmission line 12.

[0035] The transmission line 12 typically has the shape of a flat strip extending in a specific direction. The width of the transmission line 12 is, for example, 2 µm to 800 µm. When the patch antenna 11 has a substantially rectangular shape, the direction in which the transmission line 12 extends is typically substantially parallel to a width direction of the patch antenna 11.

[0036] In one embodiment, impedance matching is achieved between the patch antenna 11 and the transmission line 12.

[0037] As in Fig. 3, the patch antenna 11 may include a cutout portion 111. The cutout portion 111 is positioned adjacent to a portion of the patch antenna 11 that is connected to the transmission line 12. The cutout portion 111 may have any suitable configuration. The cutout portion 111 is offset inward from the outer edge of the patch antenna 11.

[0038] As in Fig. 4, the patch antenna 11 may further include a slot 112. The slot 112 penetrates the patch antenna 11 in its thickness direction. The slot 112 has any suitable configuration. In the example shown, the slot 112 is substantially U-shaped, as viewed from the thickness direction of the inorganic material substrate 2.

[0039] Furthermore, the transmission line 12 may include a narrow portion 121 and a wide portion 122. The narrow portion 121 is located at an end portion of the transmission line 12 on the patch antenna 11 side. 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 is appropriately set. The wide portion 122 is arranged on an opposite side of the patch antenna 11 from the narrow portion 121. A range of the width of the wide portion 122 is, for example, the same as the aforementioned range of the width of the transmission line 12.

[0040] As in Fig. 1 and Fig. As shown in Figure 2, in one embodiment, the transmission line 12 forms a waveguide capable of transmitting the electromagnetic wave. With this configuration, the electromagnetic wave can be supplied to the patch antenna 100. In the example shown, the transmission line 12, together with a first ground layer 42, forms a microstrip line. The transmission line 12 forming the microstrip line is sometimes referred to hereinafter as the "MV signal line 12a." The antenna device 100 includes the patch antenna 11, the ground conductor layer 41, the MV signal wiring 12a, and the first ground layer 42, forming a microstrip patch antenna.

[0041] The width of the MS signal line 12a is, for example, from 20 µm to 800 µm, preferably from 50 µm to 500 µm.

[0042] The first ground layer 42 is typically disposed between the inorganic material substrate 2 and the support substrate 3 and in a portion other than the cavity portion 5. When the transmission line 12 (MS signal line 12a) is projected in the thickness direction of the inorganic material substrate 2, at least a portion of a projection surface of the transmission line 12 overlaps with the first ground layer 42.

[0043] With such a configuration, when a voltage is applied to the MV signal line 12a and the first ground layer 42, an electric field is generated between the MV signal line 12a and the first ground layer 42. Accordingly, an electromagnetic wave input from the external device can be coupled with the electric field generated between the MV signal line 12a and the first ground layer 42 and propagate through the inorganic material substrate 2 to reach the patch antenna 11. When the patch antenna 11 continues to receive an electromagnetic wave, the electromagnetic wave can propagate through the inorganic material substrate 2 due to the electric field generated between the MV signal wiring 12a and the first ground layer 42 to be transmitted to the external device.

[0044] As in Fig. 5, in another embodiment, the transmission line 12 forms a coplanar line together with second ground layers 13. In this embodiment, the first conductor layer 1 further includes the second ground layers 13. The transmission line 12 forming the coplanar line is sometimes referred to as a "CP signal line 12b" hereinafter. The antenna device 100 includes the patch antenna 11, the ground conductor layer 41, the CP signal line 12b, and the second ground layers 13, forming a coplanar patch antenna.

[0045] The width of the CP signal line 12b is, for example, from 2 µm to 200 µm, preferably from 20 µm to 150 µm.

[0046] The second ground layers 13 are arranged to sandwich the transmission line 12 in a direction orthogonal to the direction in which the transmission line 12 (CP signal wiring 12b) extends. A gap (slit) is formed between each of the second ground layers 13 and the transmission line 12 (CP signal wiring 12b) in the direction orthogonal to the direction in which the transmission line 12 extends. The width of the gap is, for example, 2 µm to 100 µm, preferably 5 µm to 80 µm.

[0047] With such a configuration, when a voltage is applied to the CP signal line 12b, an electric field is generated between the CP signal line 12b and the second ground layers 13. Accordingly, an electromagnetic wave input from the external device can be coupled with the electric field generated between the CP signal line 12b and the second ground layers 13 and propagate through the inorganic material substrate 2 to reach the patch antenna 11. Furthermore, when the patch antenna 11 receives an electromagnetic wave, the electromagnetic wave can propagate through the inorganic material substrate 2 due to the electric field generated between the CP signal line 12b and the second ground layers 13 to be transmitted to the external device.

[0048] As in Fig. 6, the second ground layer 13 may be arranged to surround the patch antenna 11 in addition to the transmission line 12. In this case, the above-mentioned gap (slit) is formed between the second ground layer 13 and the patch antenna 11. With this configuration, the antenna can be formed with a design different from that of the configuration of Fig. 5 differs.

[0049] Furthermore, the antenna device 100 including the CP signal line 12b preferably also includes the above-mentioned first ground layer 42. With such a configuration, the electric field generated between the CP signal line 12b and the second ground layer 13 can be prevented from transferring to the support substrate 3. Furthermore, it is possible to sufficiently suppress the occurrence of resonance and / or stray capacitance and suppress a change in antenna characteristics due to dimensional variation.

[0050] Although not shown, the first ground layer 42 and the second ground layer 13 may be electrically connected to each other. When the first ground layer 42 and the second ground layer 13 are electrically connected to each other, grounding can be enhanced, and therefore stray capacitance due to a wiring or a device in the surroundings can be suppressed. In one embodiment, a plurality of through holes are formed in the inorganic material substrate 2, and a via is formed in each of the through holes, so that the first ground layer 42 and the second ground layer 13 are short-circuited to each other.

[0051] As used herein, the “antenna device” includes both a wafer in which at least one antenna device is formed (antenna device wafer) and a chip obtained by cutting the antenna device wafer. B. Details of the antenna device

[0052] With reference to Fig. 1 and Fig. 2, details of the individual elements of the antenna device 100 are described below. B-1. Substrate made of inorganic material

[0053] The inorganic material substrate 2 has an upper surface on which the first conductor layer 1 is disposed and a lower surface located inside the antenna device 100. The thickness "t" of the inorganic material substrate 2 corresponds to the aforementioned expression (1). In expression (1), "a" preferably represents a numerical value of 6 or more.

[0054] 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, even more preferably 40 μm or more. If the thickness of the inorganic material substrate 2 is smaller than these lower limits, the thickness and size of an electrode included in the transmission line 12 are reduced to about a few micrometers, and it becomes difficult to achieve impedance matching with the patch antenna 11. In addition, the tolerance in transmission performance is significantly reduced in some cases due to manufacturing variations.

[0055] The thickness of the substrate 2 made of inorganic material 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, particularly preferably 60 µm or less.

[0056] When the thickness of the inorganic material substrate 2 has such an upper limit or less, the induction of a slab mode and / or the resonance of the inorganic material substrate 2 can be stably suppressed. Accordingly, a return loss at the time the antenna device 100 transmits and / or receives the electromagnetic wave can be further reduced. As a result, it is possible to broaden the bandwidth of the electromagnetic wave (typically a bandwidth of -10 dB) in which a reflection characteristic in the antenna device 100 is sufficiently small, and thus it is possible to further broaden the band to be used in the antenna device 100.

[0057] The relative dielectric constant ε of the inorganic material substrate 2 at 300 GHz is, for example, 12.0 or less, preferably 10.0 or less, more preferably 5.0 or less. A lower limit of the relative dielectric constant ε of the inorganic material substrate 2 at 300 GHz is typically 3.5. A 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, more preferably 0.0015 or less.

[0058] When the relative permittivity ε and dielectric loss tangent (dielectric loss) tanδ of the inorganic material substrate 2 fall within such ranges, the return loss in the antenna device 100 can be further reduced. The relative permittivity ε and dielectric loss tangent (dielectric loss) tanδ can be measured, for example, by terahertz time-domain spectroscopy. When no measurement frequency is specified here for the relative permittivity and dielectric loss tangent, the relative permittivity and dielectric loss tangent are meant at 300 GHz.

[0059] The inorganic material substrate 2 is formed from an inorganic material. Any suitable material can be used as the inorganic material as long as the effects according to the embodiments of the present invention are obtained.Examples of the inorganic material for forming the inorganic material substrate 2 include monocrystalline quartz (relative dielectric constant: 4.5, dielectric loss tangent: 0.0013), amorphous quartz (quartz glass, relative dielectric constant: 3.8, dielectric loss tangent: 0.0010), spinel (relative dielectric constant: 8.3, dielectric loss tangent: 0.0020), AlN (relative dielectric constant: 8.5, dielectric loss tangent: 0.0015), sapphire (relative dielectric constant: 9.4, dielectric loss tangent: 0.0030), SiC (relative dielectric constant: 9.8, dielectric loss tangent: 0.0022), magnesium oxide (relative dielectric constant: 10.0, dielectric Loss tangent: 0.0012) and silicon (relative dielectric constant: 11.7, dielectric loss tangent: 0.0016).

[0060] Of these inorganic materials, amorphous quartz (quartz glass) is preferred.

[0061] When the inorganic material substrate 2 is formed of quartz glass, the return loss in the antenna device 100 can be reduced more stably. Furthermore, the quartz glass substrate has a large dielectric constant compared to a resin-based substrate, allowing for a reduced substrate size. Furthermore, it has a relatively small dielectric constant among inorganic materials, making it advantageous for achieving low retardation. Furthermore, the first conductor layer 1 (metal layer) can be formed without surface roughening or surface treatment.

[0062] Although not shown, the substrate 2 made of inorganic material may be curved so that a part thereof overlapping with the cavity portion 5 sinks into the cavity portion 5 as viewed in the thickness direction. B-2. First conductor layer

[0063] In one embodiment, the first conductor layer 1 is arranged on a surface (a surface in its thickness direction) of the inorganic material substrate 2 and is brought into direct contact with the inorganic material substrate 2.

[0064] The first conductor layer 1 is typically made of a metal. Examples of metals are chromium (Cr), nickel (Ni), copper (Cu), and gold (Au). The metals can be used individually or in combination. The first conductor layer 1 can be made of a single layer or formed as a laminate of two or more layers. The thickness of the first conductor layer 1 is, for example, from 1 µm to 20 µm, preferably from 4 µm to 10 µm. B-3. ​​Carrier substrate

[0065] The support substrate 3 can impart excellent strength to the antenna device 100. In the illustrated example, the support substrate 3 supports the inorganic material substrate 2 via the first ground layer 42 and a connecting portion 6 (described later). In this configuration, the inorganic material substrate 2 can be thinned as described above. The support substrate 3 can be configured as desired.

[0066] Examples of a material for forming the carrier substrate 3 are indium phosphide (InP), silicon (Si), glass, SiAlON (Si 3 N 4 -Al 2 O 3 ), Mullite (3Al 2 O 3 2SiO 2 , 2Al 2 O 3 3SiO 2 ), aluminum nitride (AIN), magnesium oxide (MgO), aluminum oxide (Al 2 O 3 ), spinel (MgAl 2 O 4 ), sapphire, quartz, crystal, gallium nitride (GaN), silicon carbide (SiC), silicon nitride (Si 3 N4 ) and gallium oxide (Ga 2 O 3 ).

[0067] The thermal conductivity of the material for forming the carrier substrate 3 is preferably 150 W / K·m or more, preferably 200 W / K·m or more.

[0068] When the external device (e.g., amplifier) ​​is connected to the antenna device 100, the inorganic material substrate 2 may be heated by the external device, and the heat of the inorganic material substrate 2 may adversely affect the external device. If the material of the support substrate 3 has the above-mentioned thermal conductivity, the support substrate 3 acts as a heat sink, and thus the heat of the inorganic material substrate 2 can be smoothly dissipated.

[0069] Of the materials from which the carrier substrate 3 is constructed, silicon (thermal conductivity: approx. 160 W / K·m), silicon carbide (thermal conductivity: approx. 270 W / K·m) and aluminum nitride (thermal conductivity: approx. 150 W / K·m to approx. 250 W / K·m) are preferred from the point of view of thermal conductivity.

[0070] Furthermore, a linear expansion coefficient of the material for forming the support substrate 3 is preferably as close as possible to a linear expansion coefficient of the material for forming the inorganic material substrate 2. For example, the linear expansion coefficient of the material for forming the support substrate 3 is in the range of 50% to 150% with respect to the linear expansion coefficient of the material for forming the inorganic material substrate 2. When the linear expansion coefficient of the material for forming the support substrate 3 falls within such a range, thermal deformation (typically, warpage) of the antenna device 100 can be suppressed.

[0071] Of the materials from which the carrier substrate 3 is constructed, indium phosphide, silicon, aluminum nitride, gallium nitride, silicon carbide and silicon nitride are preferred, with silicon, aluminum nitride, gallium nitride, silicon carbide and silicon nitride being more preferred and silicon being particularly preferred.

[0072] As in Fig. 2, the carrier substrate 3 in one embodiment contains a recess 31 which corresponds to the cavity section 5.

[0073] The recess 31 is typically recessed downward (in the direction away from the inorganic material substrate 2) from an upper surface (surface of the inorganic material substrate 2) of the support substrate 3. The recess 31 has the same shape as the above-described cavity portion 5, viewed from the thickness direction of the inorganic material substrate 2. In the shown example, the recess 31 has a substantially U-shape, open toward the inorganic material substrate 2, in a cut surface obtained by cutting the support substrate 3 in its thickness direction. An inner surface of the recess 31 includes side surfaces and a bottom surface. The side surfaces of the recess 31 extend in the thickness direction of the inorganic material substrate 2.The direction in which the side surfaces of the recess 31 extend may exactly coincide with (i.e., parallel to) the thickness direction of the inorganic material substrate 2, or it may be slightly inclined with respect to the thickness direction of the inorganic material substrate 2. The bottom surface of the recess 31 extends in a direction that crosses the thickness direction of the inorganic material substrate 2 (typically a direction orthogonal thereto). B-4. Second conductor layer

[0074] In one embodiment, the antenna device 100 further includes a second conductor layer 4 including the 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 (surface on the side of the inorganic material substrate 2) of the support substrate 3 and is brought into direct contact with the support substrate 3.

[0075] In the illustrated example, the ground conductor layer 41 included in the second conductor layer 4 is arranged in the recess 31 of the support substrate 3. The ground conductor layer 41 is arranged at least on the bottom surface of the recess 31. In the illustrated example, the ground conductor layer 41 is arranged on the entire inner surface of the recess 31. With this arrangement, at least a part of the ground conductor layer 41 is arranged to face the patch antenna 11 in the thickness direction of the inorganic material substrate 2. Accordingly, the electric field can be stably generated between the patch antenna 11 and the ground conductor layer 41.

[0076] In one embodiment, the second conductor layer 4 further includes the first ground layer 42. The first ground layer 42 can be arranged at any suitable position as long as the first ground layer 42 overlaps at least a part of the projection surface of the transmission line 12, as described above. The first ground layer 42 is arranged on a part of the upper surface (surface on the side of the inorganic material substrate 2) of the support substrate 3 that excludes the recess 31. The first ground layer 42 may be partially arranged on the part of the upper surface of the support substrate 3 that excludes the recess 31 (see Fig. 7), or may be arranged on the entire part of the upper surface of the carrier substrate 3 excluding the recess 31 (see Fig. 8).

[0077] As in Fig. As shown in Figure 8, in one embodiment, the first grounding layer 42 is disposed on the entire portion of the upper surface of the support substrate 3 excluding the recess 31. In the illustrated example, the first grounding layer 42 and the ground conductor layer 41 are connected to each other. When the ground conductor layer 41 and the first grounding layer 42 are continuously connected to each other to form the second conductor layer 4, the grounding function becomes stable throughout the entire substrate, and therefore, the antenna device 100 can be easily designed and manufactured.

[0078] The second conductor layer 4 is made of the same metal as the first conductor layer 1.

[0079] The thickness of the second conductor layer 4 is generally less than the thickness of the first conductor layer 1. The thickness of the second conductor layer 4 is, for example, from 1 nm to 30 µm, preferably from 10 nm to 10 µm. B-5. Connecting section

[0080] As in Fig. 1 and Fig. 2, in one embodiment, the antenna device 100 further includes the connecting portion 6. The connecting portion 6 connects the inorganic material substrate 2 and the support substrate 3 to each other. In the illustrated example, the connecting portion 6 connects the inorganic material substrate 2 and the support substrate 3, on which the first ground layer 42 is arranged, and is arranged between the inorganic material substrate 2 and the first ground layer 42.

[0081] The connecting portion 6 may be constructed from an organic material (typically an organic adhesive) or from an inorganic material.

[0082] In one embodiment, the connecting portion 6 is formed from an inorganic material. Examples of the inorganic material for forming the connecting portion 6 include SiO 2, amorphous silicon, and tantalum oxide, with amorphous silicon being preferred. The thickness of the connecting portion 6 is, for example, from 0.001 µm to 10 µm, preferably from 0.01 µm to 3 µm.

[0083] In one embodiment, the inorganic material substrate 2 and the support substrate 3 on which the first grounding layer 42 is formed are directly bonded to each other. In this configuration, the bonding portion 6 is formed between the inorganic material substrate 2 and the first grounding layer 42. The term "direct bonding" used herein means that two layers or substrates are bonded to each other without interposing an organic material (typically an organic adhesive). The shape of the direct bonding can be determined according to the configurations of the layers or substrates to be bonded. Furthermore, an interface created by the direct bonding is usually amorphized. Accordingly, the thermal resistance of the bonding interface can be drastically reduced compared to resin bonding.Therefore, in the case where the external device is connected to the antenna device 100, even if heat generated by the external device is transferred to the inorganic material substrate 2, this heat can be smoothly dissipated from the inorganic material substrate 2 into a housing via the support substrate 3. As a result, the heat can be efficiently dissipated from the inorganic material substrate 2, and deterioration of the characteristics of the external device can be suppressed.

[0084] When these components are integrated by direct bonding, peeling in the antenna device 100 can be satisfactorily suppressed, and as a result, damage (e.g., crack) of the inorganic material substrate 2 resulting from such peeling can be satisfactorily suppressed.

[0085] When these components are integrated by directly bonding without interposing a resin, heat resistance and chemical resistance can be improved in a back-end process of manufacturing, and thus deterioration of antenna characteristics due to heat and moisture absorption in the antenna device 100 can be suppressed.

[0086] The connecting portion 6 may have a single-layer structure or a laminate structure. As shown in Fig. As shown in Figure 2, in one embodiment, the connecting portion 6 has a laminate structure. The connecting portion 6 includes a first connecting layer 61 and a second connecting layer 62.

[0087] The first interconnection layer 61 is disposed on a surface of the inorganic material substrate 2. More specifically, the first interconnection layer 61 is disposed on a surface of the inorganic material substrate 2 on the opposite side to the first conductor layer 1 in the thickness direction of the inorganic material substrate 2. In the illustrated example, the first interconnection layer 61 is disposed on the lower surface (surface on the opposite side to the first conductor layer 1) of the inorganic material substrate 2 and is brought into direct contact with the inorganic material substrate 2. The first interconnection layer 61 may be partially disposed on the lower surface of the inorganic material substrate 2 or on the entire lower surface of the inorganic material substrate 2.In the illustrated example, the first connecting layer 61 is arranged on the entire lower surface of the substrate 2 made of inorganic material.

[0088] The thickness of the first connecting layer 61 is, for example, 0.5 nm to 5 µm, preferably 0.01 µm to 1.5 µm, more preferably 0.01 µm to 0.05 µm.

[0089] The second connection layer 62 is arranged on a surface of the first ground layer 42. More specifically, the second connection layer 62 is arranged on a surface of the first ground layer 42 on a side opposite to the support substrate 3 in the thickness direction of the inorganic material substrate 2. In the illustrated example, the second connection layer 62 is arranged on an upper surface (surface on the side opposite to the support substrate 3) of the first ground layer 42 and is brought into direct contact with the first ground layer 42. The second connection layer 62 can be arranged only on the first ground layer 42 or, in addition to the first ground layer 42, also on the ground conductor layer 41. In the illustrated example, the second connection layer 62 is arranged on the entire upper surface of the ground conductor layer 41 and the first ground layer 42, respectively.In other words, the second interconnect layer 62 is stacked on the entire second conductor layer 4.

[0090] The thickness range of the second connecting layer 62 is the same as, for example, the above-mentioned thickness range of the first connecting layer 61.

[0091] The second interconnect layer 62 is connected to the first interconnect layer 61 to be integrated with the first interconnect layer 61. In the illustrated example, a portion of the second interconnect layer 62 that lies on the first ground layer 42 is directly connected to the first interconnect layer 61.

[0092] As in Fig. 9, the second conductor layer 4 may be formed only of the ground conductor layer 41 without including the first ground layer 42. In this case, although not shown, the connecting portion 6 is positioned between the part of the upper surface of the support substrate 3 excluding the recess 31 and the inorganic material substrate 2 to connect the part and the inorganic material substrate 2 to each other. B-6. Cavity section

[0093] As in Fig. 2, in one embodiment, the cavity portion 5 is located in a region surrounded by the inorganic material substrate 2 and the ground conductor layer 41. The cavity portion 5 is constructed from a groove formed in the support substrate 3. The cavity portion 5 is defined by the lower surface of the inorganic material substrate 2 or the first interconnect layer 61 disposed on the lower surface of the inorganic material substrate 2, and the upper surface of the ground conductor layer 41 or the second interconnect layer 62 disposed on the upper surface of the ground conductor layer 41. In the illustrated example, the cavity portion 5 is defined by the first interconnect layer 61 disposed on the lower surface of the inorganic material substrate 2 and the second interconnect layer 62 disposed on top of the ground conductor layer 41.

[0094] Typically, the cavity portion 5 contains air. In another embodiment, the cavity portion 5 is in a vacuum state.

[0095] A dimension "d" (hereinafter referred to as "depth 'd'") of the cavity portion 5 in the thickness direction of the inorganic material substrate 2 is appropriately and suitably changed according to the configuration of the antenna device 100 and the frequency of the electromagnetic wave transmitted and / or received by the antenna device 100. The depth "d" of the cavity portion 5 is, for example, from 1 µm to 250 µm. The depth "d" of the cavity portion 5 refers to a distance in the thickness direction of the inorganic material substrate 2 between the lower surface (surface on the side opposite the first conductor layer 1) of the inorganic material substrate 2 and the upper surface (surface on the side opposite the support substrate 3) of the ground conductor layer 41.

[0096] In one embodiment, when the patch antenna 11 has a rectangular shape and the antenna device 100 transmits and receives the electromagnetic wave having a frequency of 100 GHz to 200 GHz, the depth “d” of the cavity portion 5 is, for example, 5 µm to 250 µm.

[0097] In another embodiment, when the patch antenna 11 has a rectangular shape and the antenna device 100 transmits and receives the electromagnetic wave having a frequency of 250 GHz to 350 GHz, the depth “d” of the cavity portion 5 is, for example, 5 µm to 200 µm. C. Method for manufacturing an antenna device

[0098] The following is based on reference to Fig. 2 describes an embodiment of a method for manufacturing the antenna device 100.

[0099] In one embodiment, the carrier substrate 3 with the recess 31 is first produced. The recess 31 is formed in the carrier substrate 3, for example, by reactive ion etching.

[0100] Then, the second conductor layer 4 is formed on the upper surface of the support substrate 3 in which the recess 31 is formed. Any suitable film-forming method can be used for forming the second conductor layer 4. Examples of the film-forming method include sputtering, coating, and vapor deposition, with coating being preferred.

[0101] Then, the inorganic material substrate 2 is formed, and the inorganic material substrate 2 and the support substrate 3 are directly bonded to each other. Specifically, the first interconnection layer 61 is formed on the lower surface of the inorganic material substrate 2. The second interconnection layer 62 is formed on the upper surface of the second conductor layer 4. Examples of methods for forming these layers include sputtering, coating, and evaporation, with sputtering being preferred. The surface of both the first interconnection layer 61 and the second interconnection layer 62 is polished to planarize them as needed.

[0102] Direct joining can be achieved, for example, by the following procedure. In a high vacuum chamber (e.g., about 1×10 -6Pa), the bonding surface of each of the components (layers or substrates) to be bonded is irradiated with a neutralized beam. In one embodiment, surface activation with a neutralized beam involves introducing an inert gas into a chamber, and applying a high voltage from a direct current source to an electrode located in the chamber. In such a configuration, an electric field created between the electrode (positive electrode) and the chamber (negative electrode) causes electrons to move to generate atom and ion beams from the inert gas. Of the beams that have reached a grid, the ion beam is neutralized at the grid, so that a beam of neutral atoms is emitted from a high-speed atom beam source. The atomic species from which the beam is formed is preferably an inert gas element (e.g., argon (Ar) or nitrogen (N)).At the time of activation by irradiation, the voltage is, for example, 0.5 kV to 2.0 kV and the current is, for example, 50 mA to 200 mA. The duration of irradiation with the neutralized beam is, for example, 10 seconds to 300 seconds, preferably 30 seconds to 120 seconds.

[0103] This irradiation activates each bonding surface, or more precisely, the inorganic material located on each of the irradiated surfaces.

[0104] Then, the activated bonding surfaces are brought into contact with each other in a vacuum atmosphere at normal temperature (23°C). The load at the time of contact can be, for example, 100 N to 20,000 N. Consequently, the first bonding layer 61 and the second bonding layer 62 are bonded to each other, and the bonding portion 6 is formed.

[0105] Through these steps, a laminate having the structure of the inorganic material substrate 2 / the connecting portion 6 / the second conductor layer 4 / the support substrate 3 is obtained. The direct joining method is not limited to this, and, for example, a surface activation method using a fast atom beam (FAB) or an ion gun, an atom diffusion method, or a plasma joining method can be used.

[0106] The laminate is subjected to heat treatment as required. This treatment can increase the bond strength between the inorganic substrate and the carrier substrate. The heating temperature is, for example, between 60°C and 140°C, preferably between 80°C and 120°C. The heating duration is, for example, between 10 minutes and 5 hours, preferably between 30 minutes and 3 hours.

[0107] Subsequently, the inorganic material substrate 2 is polished as needed to thin it to the aforementioned thickness. Examples of the polishing process include chemical mechanical polishing (CMP).

[0108] Then, the first conductor layer 1 is formed on the upper surface of the inorganic material substrate 2. In one embodiment, after a resist having an opening corresponding to the first conductor layer is formed on the upper surface of the inorganic material substrate 2, the first conductor layer is formed over the resist. Examples of a method for forming a metal film include sputtering, coating, and evaporation, with coating being preferred.

[0109] In this way, the antenna device 100 having the structure of the first conductor layer 1 / the inorganic material substrate 2 / the connecting portion 6 / the second conductor layer 4 / the support substrate 3 and including the cavity portion 5 is manufactured.

[0110] The antenna device 100 described above can be applied to any suitable optical device (e.g., a waveguide device and an electromagnetic wave sensor). In particular, the band of electromagnetic waves that can be used in the antenna device 100 is broadened, and therefore the antenna device 100 can be suitably used for a presence sensor that requires excellent resolution. When the antenna device 100 described above is applied to a presence sensor, a person's movement (gesture) can be detected with high accuracy. Examples of the presence sensor include a gesture detection sensor in a vehicle and a gesture detection sensor for a human-machine interface (HMI). Examples

[0111] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited by these examples. <Beispiel 1>

[0112] A 0.5 mm thick quartz glass wafer (an inorganic substrate) was prepared. A 0.02 µm thick amorphous silicon film (first compound layer) was formed by sputtering on the surface of the inorganic substrate. After film formation, the first compound layer was polished to planarize it. The arithmetic average roughness of a 10 µm surface on the first compound layer was measured using an atomic force microscope and found to be 0.2 nm.

[0113] In addition, a silicon wafer (support substrate) with a thickness of 250 µm was prepared. Then, a recess was formed in the upper surface of the support substrate by reactive ion etching. The recess had a substantially rectangular shape in the thickness direction of the support substrate. The dimension of the recess along the long side was 1100 µm, the dimension of the recess along the short side was 720 µm, and the depth of the recess was 175 µm.

[0114] Then, a gold film (second conductor layer) with a thickness of 1 µm was sputtered onto the upper surface of the support substrate where the recess was formed. The second conductor layer included the ground layer located in the recess and the first ground layer located on the portion of the upper surface of the support substrate excluding the recess.

[0115] Then, a 0.02 µm-thick amorphous silicon film (second interconnect layer) was sputtered onto the second conductor layer. After film formation, the second interconnect layer was polished to planarize it. The arithmetic average roughness of a 10 µm surface on the second interconnect layer was measured with an atomic force microscope and found to be 0.2 nm.

[0116] Then, the inorganic material substrate and the support substrate were directly bonded together as described below. First, the inorganic material substrate on which the first interconnection layer was formed and the support substrate on which the second interconnection layer and the second conductor layer were formed were loaded into a vacuum chamber and placed in a vacuum on the order of 10 -6Pa, both bonding surfaces (the surfaces of the first bonding layer and the second bonding layer) were irradiated with a high-speed Ar neutral atom beam (acceleration voltage: 1 kV, Ar flow rate: 60 sccm) for 70 seconds. After irradiation, the inorganic substrate and the support substrate were allowed to stand for 10 minutes to cool, and the surfaces of the first bonding layer and the second bonding layer (irradiated surfaces) were brought into contact with each other, followed by a pressurization of 4.90 kN for 2 minutes to bond the inorganic substrate and the support substrate. That is, the inorganic substrate and the support substrate were directly bonded via the bonding portion and the second conductor layer. After bonding, the inorganic substrate was polished until the thickness reached 50 μm.

[0117] Then, a resist was applied to the surface (polished surface) of the inorganic material substrate opposite the connecting portion, and patterning was performed by photolithography to expose portions for forming the first conductor layer. Next, a copper film (first conductor layer) with a thickness of 5 μm was formed by sputtering on the upper surface of the inorganic material substrate exposed by the resist. The resist was then removed.

[0118] The first conductor layer contained the patch antenna and the MS signal line. The patch antenna had a substantially rectangular shape when viewed from the thickness direction of the inorganic material substrate. The length of the patch antenna (in the direction orthogonal to the direction of line II-II' of Fig. 1) was 860 µm and the width of the patch antenna (in the direction of line II-II' of Fig. 1) was 590 µm. The MS signal line was formed from a wide section and a narrow section, and the line width of each section was adjusted to match the impedance to 50 Ω.

[0119] In this way, the Fig. 1, that is, the antenna device having the configuration of the first conductor layer / inorganic material substrate / connecting portion / second conductor layer / supporting substrate, was obtained. The antenna device included the cavity portion corresponding to the recess. When the patch antenna was projected in the thickness direction of the inorganic material substrate, the entire projection surface of the patch antenna overlapped with the cavity portion. The projected surface area of ​​the patch antenna was 507,400 µm. 2 and the projected area of ​​the cavity section was 792000 µm 2 . <Vergleichsbeispiel 1>

[0120] The antenna device was manufactured in the same manner as in Example 1, except that the recess was not formed in the support substrate. The antenna device did not include the cavity portion. <Messung des S11-Parameters>

[0121] For each of the antenna devices obtained in Example and Comparative Example, the S11 parameter, which represents the return loss, was measured with a network analyzer by setting a sampling frequency of 120 GHz. The results are shown in Fig. 10 and Fig. 11 shown.

[0122] As from Fig. 10, the bandwidth of the electromagnetic wave in which the S11 parameter of the antenna device is -10 dB or less (-10 dB bandwidth) is 10.2 GHz when the antenna device includes the cavity section. In contrast, as shown in Fig.As shown in Figure 11, in the antenna device that does not include the cavity portion, the -10 dB bandwidth is 4.9 GHz. Accordingly, it can be seen that the band to be used in the antenna device can be broadened when the antenna device includes the cavity portion. Industrial applicability

[0123] The antenna device according to the embodiments of the present invention can be used in a variety of fields such as next-generation high-speed communication and sensors, and in particular can be suitably used as a presence sensor. List of reference symbols 1 first conductor layer 11 Patch antenna 12 transmission line 2 Substrate made of inorganic material 3 Carrier substrate 31 recess 4 second conductor layer 41 Earth conductor layer 5 Cavity section 6 connecting section 61 first connection layer 62 second connection layer 100 antenna device QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6955590 B2

[0003]

Claims

[1] Antenna device comprising: a substrate made of inorganic material; a first conductor layer disposed on one side of the inorganic material substrate in a thickness direction of the inorganic material substrate, the first conductor layer including a patch antenna; a support substrate arranged on a side opposite the first conductor layer with respect to the substrate made of inorganic material; a cavity portion disposed on the side opposite the first conductor layer with respect to the inorganic material substrate and disposed on the inorganic material substrate side of the support substrate; and a ground conductor layer disposed in the cavity portion, the ground conductor layer being capable of generating an electric field between the ground conductor layer and the patch antenna, wherein a thickness “t” of the inorganic material substrate satisfies expression (1) given below, and wherein, when the patch antenna is projected in the thickness direction of the inorganic material substrate, at least a part of a projection surface of the patch antenna overlaps with the cavity portion: t<λaε where "t" represents the thickness of the inorganic material substrate, λ represents a wavelength of an electromagnetic wave transmitted and / or received by the antenna device, ε represents a relative dielectric constant of the inorganic material substrate, and "a" represents a numerical value of 3 or more. [2] The antenna device according to claim 1, wherein, when the patch antenna is projected in the thickness direction of the inorganic material substrate, the entire projection surface of the patch antenna overlaps with the cavity portion. [3] The antenna device according to claim 1 or 2, wherein the first conductor layer further includes a transmission line connected to the patch antenna. [4] The antenna device according to claim 3, further comprising a first ground layer disposed between the inorganic material substrate and the support substrate and in a part different from the cavity portion, wherein, when the transmission line is projected in the thickness direction of the inorganic material substrate, at least a part of a projection surface of the transmission line overlaps with the first ground layer. [5] The antenna device according to claim 4, further comprising a connecting portion configured to connect the inorganic material substrate and the support substrate to each other. [6] The antenna device according to claim 5, wherein the connecting portion includes: a first interconnection layer disposed on a 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 connecting layer disposed on a surface of the first grounding layer on a side opposite to the support substrate in the thickness direction of the inorganic material substrate, and wherein the second connection layer is connected to the first connection layer. [7] The antenna device according to claim 1 or 2, wherein the thickness “t” of the inorganic material substrate is 100 µm or less. [8] The antenna device according to claim 1 or 2, wherein a frequency of the electromagnetic wave transmitted and / or received by the antenna device is from 20 GHz to 20 THz. [9] The antenna device according to claim 1 or 2, wherein the inorganic material substrate is formed of quartz glass. [10] The antenna device according to claim 1 or 2, wherein the support substrate is formed of silicon.

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