Waveguide mode converter

Abstract

A waveguide mode converter with excellent conversion efficiency is provided. A waveguide mode converter according to one embodiment of the present disclosure comprises a substrate made of an inorganic material, a first conductor layer, a support substrate, a cavity section, and a backshort conductor layer. The first conductor layer is arranged on one side of the substrate made of an inorganic material in a thickness direction of the substrate made of an inorganic material. The support substrate is arranged on one side opposite the first conductor layer with respect to the substrate made of an inorganic material. The cavity section is arranged on the side opposite the first conductor layer with respect to the substrate made of an inorganic material and is located on the side of the substrate made of an inorganic material of the support substrate.The backshort conductor layer is arranged on an inner surface of the cavity section. The first conductor layer comprises signal wiring. The signal wiring forms a planar conductor capable of conducting an electromagnetic wave. The signal wiring has an end section that overlaps the cavity section when viewed from the thickness direction of the substrate, which is made of an inorganic material.

Description

Technical field

[0001] The present disclosure relates to a waveguide mode converter. State of the art

[0002] In recent years, it has become desirable to connect an antenna and a radio frequency circuit in a communication device. The use of a waveguide mode converter in the connection between the antenna and the radio frequency circuit has been discussed. Such a waveguide mode converter must be capable of bidirectional conversion between a waveguide mode present in a waveguide tube that can be connected to the antenna and a waveguide mode present in a planar transmission line that can be connected to the radio frequency circuit.

[0003] As an example of such a waveguide mode converter, the following microstrip line-waveguide tube converter has been proposed (see patent document 1). The microstrip line-waveguide tube converter comprises a first dielectric substrate to be connected to a waveguide tube, a second dielectric substrate stacked on top of the first dielectric substrate, and a microstrip line formed between the first and second dielectric substrates. In such a microstrip line-waveguide tube converter, a dielectric-filled waveguide tube formed from the first and second dielectric substrates acts as a backshort section (tuning section). Document listPatent documents

[0004] [PTL 1] JP 2008-193162 A Summary of the invention: Technical problem

[0005] However, in the microstrip waveguide tube converter as described in patent document 1, the backshort section is formed from the dielectric-filled waveguide tube, and thus a dielectric loss of an electromagnetic wave is caused in a waveguide mode conversion of the electromagnetic wave, and the conversion efficiency of the electromagnetic wave may consequently become insufficient.

[0006] The primary objective of the present disclosure is to provide a waveguide mode converter capable of achieving excellent conversion efficiency. Solution to the problem

[0007] [1] A waveguide mode converter according to one embodiment of the present disclosure comprises a substrate made of an inorganic material, a first conductor layer, a support substrate, a cavity section, and a backshort conductor layer (tuning section conductor layer). The first conductor layer is arranged on one side of the substrate made of an inorganic material in a thickness direction of the substrate made of an inorganic material. The support substrate is arranged on one side opposite the first conductor layer with respect to the substrate made of an inorganic material. The cavity section is arranged on the side opposite the first conductor layer with respect to the substrate made of an inorganic material and on the side of the substrate made of an inorganic material of the support substrate. The backshort conductor layer is arranged in the cavity section. The first conductor layer comprises signal wiring.The signal wiring forms a planar conductor capable of transmitting an electromagnetic wave. The signal wiring has an end section that overlaps the cavity section, viewed from the thickness direction of the substrate made of an inorganic material.

[0008] [2] In the waveguide mode converter according to the aforementioned subject matter [1], the substrate made of an inorganic material can comprise a mode-conversion section which overlaps the cavity section viewed from the thickness direction of the substrate made of an inorganic material. The waveguide mode converter can further comprise a leakage suppression section which is designed to prevent leakage of the electromagnetic wave from the mode-conversion section. The leakage suppression section is arranged such that it extends through the substrate made of an inorganic material and surrounds the mode-conversion section.

[0009] [3] In the waveguide mode converter according to the aforementioned article [2], the leakage suppression section can be formed from a plurality of conductor columns. The plurality of conductor columns are arranged at intervals from one another.

[0010] [4] In the waveguide mode converter according to the aforementioned article [2], the leakage suppression section can be formed from a conductor wall. The conductor wall extends continuously in such a way that it surrounds the mode conversion part.

[0011] [5] In the waveguide mode converter according to one of the aforementioned articles [1] to [4], the first conductor layer may further comprise a first grounding layer. The first grounding layer is arranged at a distance from one end section of the signal wiring such that it surrounds one end section of the signal wiring.

[0012] [6] The waveguide mode converter according to the aforementioned subject matter [5] may further comprise a second grounding layer. The second grounding layer is arranged in a part that is distinct from the cavity section between the substrate made of an inorganic material and the support substrate. The second grounding layer is arranged such that, viewed in the thickness direction of the substrate made of an inorganic material, it surrounds the cavity section.

[0013] [7] In the waveguide mode converter according to the aforementioned item [6], the first grounding layer and the second grounding layer can be electrically connected to each other.

[0014] [8] The waveguide mode converter according to any of the aforementioned articles [1] to [7] may further comprise a waveguide element. The waveguide element is located on the side opposite the substrate made of an inorganic material with respect to the first conductor layer. The waveguide element comprises a hollow waveguide extending in the thickness direction of the substrate made of an inorganic material. The hollow waveguide is located opposite one end section of the signal wiring in the thickness direction of the substrate made of an inorganic material.

[0015] [9] In the waveguide mode converter according to the aforementioned subject matter [8], the planar line formed from the signal wiring can guide an electromagnetic wave in a quasi-TEM mode. The hollow waveguide can guide an electromagnetic wave in a TE mode.

[0016]

[10] The waveguide mode converter according to any of the aforementioned articles [1] to [9] may further comprise a connecting section. The connecting section connects the substrate made of an inorganic material and the support substrate.

[0017]

[11] In the waveguide mode converter according to one of the aforementioned articles [1] to

[10] , the substrate made of an inorganic material may have a thickness of 100 µm or less.

[0018]

[12] In the waveguide mode converter according to one of the aforementioned items [1] to

[11] , the substrate can be made of an inorganic material made of quartz glass.

[0019]

[13] In the waveguide mode converter according to one of the aforementioned articles [1] to

[12] , the frequency of the electromagnetic wave that can be guided in the waveguide mode converter can be from 20 GHz to 20 THz. Advantageous effects of the invention

[0020] According to the embodiment of the present disclosure, the waveguide mode converter can be obtained with excellent conversion efficiency. Brief description of the drawings Fig. Figure 1 is a schematic perspective view of a waveguide mode converter according to an embodiment of the present disclosure. Fig. Figure 2 is a cross-sectional view of the waveguide mode converter along line II-II' of Fig. 1. Fig. Figure 3 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 4 is a schematic perspective view of a second conductor layer and a support substrate used in the waveguide mode converter of Fig. 1 are included. Fig. Figure 5 is a schematic perspective view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 6 is a cross-sectional view of the waveguide mode converter along line VI-VI' of Fig. 5. Fig. Figure 7 is a schematic perspective view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 8 is a schematic perspective view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 9 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 10 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 11 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 12 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Fig. Figure 13 is a schematic cross-sectional view of a waveguide mode converter according to a further embodiment of the present disclosure. Description of embodiments

[0021] Embodiments of the present disclosure are described below with reference to the drawings. However, the present disclosure is not limited to these embodiments. Furthermore, the drawings may be shown schematically with respect to the width, thickness, shape, and the like of each component in comparison with the embodiments to make the description clearer; however, this is only an example and does not limit the interpretation of the present disclosure. A. Overall structure of the waveguide mode converter

[0022] The Fig. Figure 1 is a schematic perspective view of a waveguide mode converter according to an embodiment of the present disclosure and the Fig. Figure 2 is a cross-sectional view of the waveguide mode converter along line II-II' of Fig. 1.

[0023] A waveguide mode converter 100 in the example shown comprises a substrate made of an inorganic material 2, a first conductor layer 1, a support substrate 3, a cavity section 5, and a backshort conductor layer 41. The first conductor layer 1 is arranged on one side of the substrate made of an inorganic material 2 in a thickness direction of the substrate made of an inorganic material 2. The first conductor layer 1 includes a signal wiring 12 extending in a predetermined direction. The signal wiring 12 forms a planar conductor capable of transmitting an electromagnetic wave. The support substrate 3 is arranged on one side opposite the first conductor layer 1 with respect to the substrate made of an inorganic material 2.The cavity section 5 is located on the side opposite the first conductor layer 1 with respect to the substrate made of an inorganic material 2 and is located on the side of the substrate made of an inorganic material of the support substrate 3. The backshort conductor layer 41 is located within the cavity section 5. The substrate made of an inorganic material 2 typically includes a mode-transition part 21 that overlaps the cavity section 5 in the thickness direction of the substrate made of an inorganic material 2. In other words, the mode-transition part 21 is a portion of the substrate made of an inorganic material 2 that overlaps a protrusion surface on which the cavity section 5 is protruded in the thickness direction of the substrate made of an inorganic material 2.The signal wiring 12 comprises, in the direction in which the signal wiring 12 extends, a first end section E1, which serves as one end section, and a second end section E2, which serves as another end section. The first end section E1 of the signal wiring 12 overlaps the cavity section 5 viewed from the thickness direction of the substrate made of an inorganic material 2.

[0024] In such a waveguide mode converter 100, the mode conversion part 21 of the substrate made of an inorganic material 2, the cavity section 5 and the backshort conductor layer 41 form a backshort section (tuning section) BS (see the Fig. 2) Accordingly, compared to a case where the backshort section is formed from a dielectric-filled waveguide tube, the dielectric loss in the waveguide mode conversion of an electromagnetic wave can be reduced and the conversion efficiency of the electromagnetic wave can be improved.

[0025] The waveguide mode converter 100 can typically perform a bidirectional conversion between a waveguide mode present in the planar transmission line formed from the signal wiring 12 and a waveguide mode present in a hollow waveguide. The planar transmission line can typically transmit an electromagnetic wave in a quasi-TEM mode. The hollow waveguide can typically transmit an electromagnetic wave in a TE mode.

[0026] Typical examples of electromagnetic waves that can be guided in the Waveguide Mode Converter 100 range from millimeter waves to terahertz waves. The "millimeter wave" is typically an electromagnetic wave with a frequency of approximately 20 GHz to approximately 300 GHz, and the "terahertz wave" is typically an electromagnetic wave with a frequency of approximately 300 GHz to approximately 20 THz.

[0027] The frequency of the electromagnetic wave that can be guided through the waveguide mode converter 100 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 yet another example from 100 GHz to 200 GHz.

[0028] As it is in the Fig. As shown in Figure 3, in one embodiment the waveguide mode converter 100 further comprises a waveguide element 8 which includes a hollow waveguide. In some instances below, the waveguide mode converter 100 comprising the waveguide element 8 is distinguished from the waveguide mode converter 100 not comprising the waveguide element 8, referred to as converter 101 provided with a waveguide element.

[0029] The waveguide element 8 is located on a side opposite the substrate made of an inorganic material 2 with respect to the first conductor layer 1. The waveguide element 8 is typically located on a side opposite the backshort section BS with respect to the first end section E1 of the first ground layer 11. The hollow waveguide incorporated into the waveguide element 8 extends in the thickness direction of the substrate made of an inorganic material 2. The hollow waveguide is opposite the first end section E1 of the signal wiring 12 in the thickness direction of the substrate made of an inorganic material 2. In the example shown, a central axis of the hollow waveguide and a center of the cavity section 5 are coaxially located along the thickness direction of the substrate made of an inorganic material 2.

[0030] The waveguide element 8 is positioned relative to the first end section E1 of the signal wiring 12 by any suitable method.

[0031] The signal wiring 12 typically has a flat ribbon shape that extends linearly. The direction in which the signal wiring 12 extends is essentially orthogonal to the thickness direction of the substrate made of an inorganic material 2. For example, a dimension of the signal wiring 12 in a width direction (a direction orthogonal to both the thickness direction of the substrate made of an inorganic material 2 and the direction in which the signal wiring 12 extends) is from 20 µm to 800 µm.

[0032] In the example shown, the first end section E1 of the signal wiring 12 is arranged in the mode-conversion part 21 of the substrate made of an inorganic material 2. The second end section E2 of the signal wiring 12 is arranged in any suitable position in a part of the substrate made of an inorganic material 2 that does not include the mode-conversion part 21. The second end section E2 of the signal wiring 12 is typically designed so that it can be connected to any suitable external device (see the Fig. 13) Examples of the external device include a high-frequency circuit, an amplifier, and a frequency filter. In the Fig. 13 is an amplifier 9 connected to the second end section E2 of the signal wiring 12.

[0033] In such a setup, when an electromagnetic wave (an electrical signal) is introduced from the external device into the planar line formed by the signal wiring 12, the electromagnetic wave is guided through the planar line in a specific mode corresponding to the planar line (typically in the quasi-TEM mode) so that it reaches the backshort section BS. Thereafter, in the backshort section BS, the electromagnetic wave is transformed into a specific mode corresponding to the hollow waveguide (typically the TE mode) for guidance to the hollow waveguide.

[0034] As it is in the Fig. As shown in Figure 1, the first end section E1 of the signal wiring 12 can overlap the center of the cavity section 5 viewed from the thickness direction of the substrate made of an inorganic material 2 or can be displaced from the center.

[0035] In one embodiment, the first end section E1 of the signal wiring 12 overlaps a central part of the cavity section 5 in the width direction of the signal wiring 12, viewed from the thickness direction of the substrate made of an inorganic material 2. By arranging the first end section E1 of the signal wiring 12 in this way, the conversion efficiency of the waveguide mode converter 100 can be further improved.

[0036] Furthermore, the first end section E1 of the signal wiring 12 can overlap a central part of the cavity section 5 in the direction in which the signal wiring 12 extends when viewed from the thickness direction of the substrate made of an inorganic material 2, or can be displaced from the central part.

[0037] As it is in the Fig. As shown in Figure 2, an end edge of the first end section E1 of the signal wiring 12 is located away from an end edge of the cavity section 5 in the direction in which the signal wiring 12 extends.

[0038] In one embodiment, the position of the first end section E1 in the direction in which the signal wiring 12 extends is suitably and expediently configured according to a distance L1 between the end edge of the first end section E1 and a first end edge of the cavity section 5, and a distance L2 between the end edge of the first end section E1 and a second end edge of the cavity section 5. The first end edge of the cavity section 5 is located between the first end section E1 and the second end section E2 in the direction in which the signal wiring 12 extends. The second end edge of the cavity section 5 is located on a side opposite the second end section E2 with respect to the first end section E1 in the direction in which the signal wiring 12 extends.

[0039] In the direction in which the signal wiring 12 extends, the distance L1 between the end edge of the first end section E1 of the signal wiring 12 and the first end edge of the cavity section 5, viewed from the thickness direction of the substrate made of an inorganic material 2, corresponds to a length of the signal wiring 12 entering the cavity section 5. For example, the distance L1 between the end edge of the first end section E1 and the first end edge of the cavity section 5 ranges from (λ / 12ε) µm to (3λ / 4ε) µm. (λ represents a wavelength of the electromagnetic wave guided in the waveguide mode converter 100. ε represents a relative dielectric constant of the substrate made of an inorganic material 2.) The distance L1 is in particular from 10 µm to 700 µm and in another example from 100 µm to 500 µm.More precisely, the distance L1 represents a distance between the end edge of the first end section E1 of the signal wiring 12 and a side surface corresponding to a first end edge of a recess 31, which will be described later, in the direction in which the signal wiring 12 extends.

[0040] In the direction in which the signal wiring 12 extends, for example, a region of distance L2 between the end edge of the first end section E1 of the signal wiring 12 and the second end edge of the cavity section 5 corresponds to the aforementioned region of distance L1. More precisely, distance L2 represents a distance between the end edge of the first end section E1 of the signal wiring 12 and a side surface corresponding to a second end edge of the recess 31, which will be described later, in the direction in which the signal wiring 12 extends.

[0041] The shape of the first end section E1 of the signal wiring 12 is designed to be suitable and appropriate. Examples of the shape of the first end section E1, viewed from the thickness direction of the substrate made of an inorganic material 2, include polygonal shapes, such as a rectangular shape, a circular shape, an oval shape, a conical shape, and other shapes.

[0042] As it is in the Fig. As shown in Figure 1, in one embodiment the first conductor layer 1 further comprises a first grounding layer 11. The first grounding layer 11 is arranged at a distance from the first end section E1 of the signal wiring 12, such that it surrounds the first end section E1 of the signal wiring 12. If the first conductor layer 1 comprises the first grounding layer 11, leakage of the electromagnetic wave from the backshort section BS can be prevented.

[0043] In the example shown, the first grounding layer 11 comprises an opening section 11a and a slot 11b. The opening section 11a of the first grounding layer 11 corresponds to the mode-conversion part 21 of the substrate made of an inorganic material 2 and exposes the mode-conversion part 21. The slot 11b is formed by cutting out a portion of the first grounding layer 11 that defines the opening section 11a. The slot 11b is continuous with the opening section 11a. The slot 11b typically extends in the same direction as the signal wiring 12. A portion of the signal wiring 12 is located in the slot 11b between the first end section E1 and the second end section E2. The first end section E1 of the signal wiring 12 is located in the opening section 11a.

[0044] As it is in the Fig. As shown in Figure 2, the waveguide mode converter 100 in one embodiment further comprises a second grounding layer 42. The second grounding layer 42 is arranged in a portion, distinct from the cavity section 5, between the substrate made of an inorganic material 2 and the support substrate 3. The second grounding layer 42 is arranged such that, viewed from the thickness direction of the substrate made of an inorganic material 2, it surrounds the entire cavity section 5. With such a design, leakage of the electromagnetic wave from the backshort section BS can be reliably prevented.

[0045] The second grounding layer 42 can be arranged at a distance from the backshort conductor layer 41 or can be continuous with the backshort conductor layer 41. In the example shown, the second grounding layer 42 is continuous with the backshort conductor layer 41 (see the Fig. 4) If the second grounding layer 42 and the backshort conductor layer 41 are continuous with each other, the grounding function is stable over the entire substrate and the waveguide mode converter 100 can be easily designed and manufactured.

[0046] Furthermore, at least part of the second earthing layer 42 overlaps the first earthing layer 11 when viewed from the thickness direction of the substrate made of an inorganic material 2.

[0047] As it is in the Fig. As shown in Figure 5, the waveguide mode converter 100 in one embodiment further comprises a leakage suppression section 7. The leakage suppression section 7 is designed to prevent leakage of the electromagnetic wave from the mode conversion part 21 of the substrate made of an inorganic material 2. The leakage suppression section 7 is arranged such that it extends through the substrate made of an inorganic material 2 and surrounds the mode conversion part 21.

[0048] As it is in the Fig. As shown in Figure 6, the leakage suppression section 7 typically includes a through-hole 7a that allows the passage of the electromagnetic wave. The through-hole 7a is located in a portion of the leakage suppression section 7 that overlaps the signal wiring 12 when viewed from the thickness direction of the substrate made of an inorganic material 2 (see Figure 6). Fig. 5) The leakage suppression section 7 is typically formed from a conductor material and is preferably formed from a metal (described later) that corresponds to that of the first conductor layer 1.

[0049] In the example shown, the leakage suppression section 7 is formed from a plurality of conductor columns 71. The plurality of conductor columns 71 are arranged at suitable intervals from one another, except for a portion which corresponds to the through-opening 7a (see the Fig. 5) Each of the plurality of conductor columns 71 typically extends in the thickness direction through the substrate made of an inorganic material 2. The conductor column 71 is arranged in a through-hole 22 formed in the substrate made of an inorganic material 2. That is, in this embodiment, the substrate made of an inorganic material 2 comprises a plurality of through-holes 22 such that they correspond to the plurality of conductor columns 71. In one embodiment, the conductor column 71 is formed from a conductor material that is filled into the through-hole 22. Furthermore, the conductor column 71 can be formed from a conductive film that is formed on an inner surface of the through-hole 22.

[0050] The spacing between adjacent conductor columns 71 is appropriately and expediently set according to the wavelength of the electromagnetic wave to be conducted. The spacing between the central axes of the adjacent conductor columns 71 is, for example, from 30 µm to 400 µm, preferably from 60 µm to 300 µm (see the Fig. 5).

[0051] Furthermore, as stated in the Fig. As shown in Figure 7, the conductor section 7 is formed from a conductor wall 72. The conductor wall 72 extends continuously such that it surrounds the mode-conversion part 21, except for a portion corresponding to the through-hole 7a. In the example shown, the conductor wall 72 has a substantially rectangular tube shape, and a portion of the conductor wall 72 is cut out to form the through-hole 7a.

[0052] As it is in the Fig. As shown in Figure 6, the first grounding layer 11 and the second grounding layer 42 are electrically connected in one embodiment. When the first grounding layer 11 and the second grounding layer 42 are electrically connected, the grounding can be enhanced, and stray capacitance due to a conductor or element in the environment can be prevented. Furthermore, leakage of the electromagnetic wave from the backshort section BS can be more reliably prevented.

[0053] In the example shown, the first grounding layer 11 and the second grounding layer 42 are electrically connected to each other via the leakage suppression section 7. In particular, one end section of the leakage suppression section 7 in the thickness direction of the substrate made of an inorganic material 2 is in contact with the first grounding layer 11, and another end section of the leakage suppression section 7 in the thickness direction of the substrate made of an inorganic material 2 is in contact with the second grounding layer 42.

[0054] In one embodiment, the signal wiring 12 forms a microstrip line together with the second grounding layer 42. The signal wiring 12, which forms the microstrip line, is sometimes referred to below as the "MS-type signal wiring 12a". In this embodiment, the second grounding layer 42 extends such that, viewed from the thickness direction of the substrate made of an inorganic material 2, it overlaps at least a portion of the MS-type signal wiring 12a.

[0055] With such a setup, when a voltage is applied to the MS-type signal wiring 12a and the second grounding layer 42, an electric field is generated between the MS-type signal wiring 12a and the second grounding layer 42. Accordingly, an electromagnetic wave introduced by the external device can couple with the electric field generated between the MS-type signal wiring 12a and the second grounding layer 42 and be guided through the substrate made of an inorganic material 2 so that it reaches the backshort section BS.

[0056] One dimension of the signal wiring of the MS type 12a in the lateral direction is, for example, from 20 µm to 800 µm, preferably from 50 µm to 500 µm. Furthermore, the dimension of the signal wiring of the MS type 12a in the lateral direction can be changed along the transmission direction of the electromagnetic wave.

[0057] Furthermore, as is stated in the Fig. Figure 8 shows that in a further embodiment the signal wiring 12 comprises a coplanar conductor together with third grounding layers 13. In this embodiment, the first conductor layer 1 further comprises the third grounding layers 13. The signal wiring 12, which forms the coplanar conductor, is sometimes referred to below as the “CP-type signal wiring 12b”.

[0058] The third earthing layers 13 are arranged such that they sandwich-like surround the CP-type 12b signal wiring in the lateral direction of the CP-type 12b signal wiring. In the lateral direction of the signal wiring 12, an air gap (slot) is formed between the third earthing layer 13 and the CP-type 12b signal wiring.

[0059] With such a setup, when a voltage is applied to the CP-type 12b signal wiring, an electric field is generated between the CP-type 12b signal wiring and the third earthing layers 13. Accordingly, an electromagnetic wave introduced by the external device can couple with the electric field generated between the CP-type 12b signal wiring and the third earthing layers 13 and be guided through the substrate made of an inorganic material 2 so that it reaches the backshort section BS.

[0060] The third earthing layers 13 can be arranged at a distance from the first earthing layer 11 or can be continuous with the first earthing layer 11. In the example shown, the third earthing layers 13 are continuous with the first earthing layer 11. More precisely, the third earthing layers 13 are connected to portions of the first earthing layer 11 adjacent to the slot 11b. In this way, the air gap section between the third earthing layer 13 and the CP-type signal wiring 12b is connected to the opening section 11a of the first earthing layer 11 via the slot 11b of the first earthing layer 11.

[0061] One dimension of the CP-type 12b signal wiring in the lateral direction is, for example, from 2 µm to 200 µm, preferably from 20 µm to 150 µm. Furthermore, the dimension of the CP-type 12b signal wiring in the lateral direction can change along the transmission direction of the electromagnetic wave.

[0062] The width of the air gap section between the third grounding layer 13 and the signal wiring of CP type 12b is, for example, from 2 µm to 100 µm, preferably from 5 µm to 80 µm. Furthermore, the width of the air gap section between the third grounding layer 13 and the signal wiring of CP type 12b can change along the direction of transmission of the electromagnetic wave.

[0063] Furthermore, in the waveguide mode converter 100, which includes the CP-type 12b signal wiring, the second grounding layer 42 preferably extends such that, viewed from the thickness direction of the substrate made of an inorganic material 2, it overlaps at least a portion of each of the CP-type 12b signal wiring and the third grounding layer 13. This configuration prevents the electric field generated between the CP-type 12b signal wiring and the third grounding layer 13 from escaping to the substrate 3. Moreover, it prevents the occurrence of resonance and / or stray capacitance and avoids changes in the mode conversion characteristics due to dimensional variations.

[0064] As used here, the “waveguide mode converter” comprises both a wafer in which at least one waveguide mode converter is formed (waveguide mode converter wafer) and a chip obtained by cutting the waveguide mode converter wafer. B. Details of the waveguide mode converter

[0065] With reference to Fig. 1 and Fig. 2. Details of each element of the waveguide mode converter 100 are described below. B-1. Substrate made of an inorganic material

[0066] The substrate made of an inorganic material 2 has an upper surface on which the first conductor layer 1 is arranged, and a lower surface located within the waveguide mode converter 100. A thickness “t” of the substrate made of an inorganic material 2 typically satisfies the following expression (1). t<λaε

[0067] (In this expression, "t" represents the thickness of the substrate made of an inorganic material 2. λ represents the wavelength of an electromagnetic wave guided in the waveguide mode converter 100. ε represents the relative permittivity of the substrate made of an inorganic material 2. "a" represents a numerical value of 3 or more.)

[0068] In expression (1) ‘a’ preferably represents a numerical value of 6 or more.

[0069] The thickness of the substrate made of an inorganic material 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 most preferably 40 µm or more. If the thickness of the substrate made of an inorganic material 2 is less than these lower limits, the thickness and size of the signal wiring 12 are reduced to approximately several micrometers, and it becomes difficult to achieve impedance matching with the signal wiring 12. Furthermore, in some cases, the tolerance in the transmission power due to manufacturing variations is significantly reduced.

[0070] Furthermore, the thickness of the substrate made of an inorganic material 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 particularly preferably 60 µm or less.

[0071] If the substrate made of an inorganic material 2 has such a thickness, the induction of a plate mode and / or the resonance of the substrate made of an inorganic material 2 can be stably prevented. Accordingly, the loss at the time when the waveguide mode converter 100 guides the electromagnetic wave can be reduced. As a result, the conversion efficiency of the electromagnetic wave in the waveguide mode converter 100 can be further improved.

[0072] Furthermore, in recent years the development of a miniaturized communication device, to which the waveguide mode converter 100 is applied, has progressed, and it is predicted that this will also necessitate a miniaturization of the waveguide mode converter 100. In the waveguide mode converter 100, if the thickness of the substrate made of an inorganic material 2 meets the aforementioned thickness, the substrate made of an inorganic material 2 can be made thinner, thus fulfilling the need for miniaturization while simultaneously improving the conversion efficiency in the waveguide mode converter 100.

[0073] The relative permittivity ε of the substrate made of an inorganic material 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 permittivity ε of the substrate made of an inorganic material 2 at 300 GHz is typically 3.5. A dielectric loss factor (dielectric loss) tanδ of the substrate made of an inorganic material 2 at 300 GHz is, for example, 0.0030 or less, preferably 0.0020 or less, more preferably 0.0015 or less.

[0074] If the relative permittivity ε and the dielectric loss factor (dielectric loss) tanδ of the substrate made of an inorganic material 2 lie within such ranges, the dielectric loss in the waveguide mode converter 100 can be further reduced. The relative permittivity ε and the dielectric loss factor (dielectric loss) tanδ can be measured, for example, by terahertz time-domain spectroscopy. Furthermore, where a measurement frequency for the relative permittivity and the dielectric loss factor is not specified, the relative permittivity and the dielectric loss factor at 300 GHz are meant.

[0075] The substrate made of an inorganic material 2 is formed from an inorganic material. Any suitable material can be used as the inorganic material, as long as the effects are obtained according to the embodiments of the present disclosure.Examples of inorganic material for forming substrate 2 include single-crystal quartz (relative dielectric constant: 4.5, dielectric loss factor: 0.0013), amorphous quartz (quartz glass, relative dielectric constant: 3.8, dielectric loss factor: 0.0010), spinel (relative dielectric constant: 8.3, dielectric loss factor: 0.0020), Aln (relative dielectric constant: 8.5, dielectric loss factor: 0.0015), sapphire (relative dielectric constant: 9.4, dielectric loss factor: 0.0030), SiC (relative dielectric constant: 9.8, dielectric loss factor: 0.0022), magnesium oxide (relative dielectric constant: 10.0, dielectric loss factor: 0.0012), and silicon. (relative dielectric constant: 11.7, dielectric loss factor: 0.0016).

[0076] Of these inorganic materials, amorphous quartz (quartz glass) is preferred.

[0077] If the substrate is made of an inorganic material 2, specifically quartz glass, conduction loss in the waveguide mode converter 100 can be reduced more effectively. Furthermore, compared to a resin-based substrate, the quartz glass substrate has a high dielectric constant, allowing for a smaller substrate size. It also has a relatively low dielectric constant compared to other inorganic materials, making it advantageous for achieving low delay. Additionally, the first conductor layer 1 (metal layer) can be formed without surface roughening or treatment.

[0078] Although not shown, the substrate made of an inorganic material 2 may be curved such that a part of it, viewed from the thickness direction, overlaps the cavity section 5, extends into the cavity section 5. B-2. First conductor layer

[0079] In one embodiment, the first conductor layer 1, which comprises the signal wiring 12, is arranged on a surface (a surface in the thickness direction) of the substrate made of an inorganic material 2 and is in direct contact with the substrate made of an inorganic material 2. That is, the signal wiring 12 is arranged directly on the substrate made of an inorganic material 2.

[0080] The first conductor layer 1 typically comprises the aforementioned first earthing layer 11 in addition to the signal wiring 12. Furthermore, if the signal wiring 12 forms a coplanar conductor, the first conductor layer 1 also comprises the aforementioned third earthing layers 13 (see the Fig. 8).

[0081] The first conductor layer 1 is typically made of a metal. Examples of metals include chromium (Cr), nickel (Ni), copper (Cu), and gold (Au). The metals can be used alone or in combination. The first conductor layer 1 can be a single layer or 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

[0082] The support substrate 3 can impart excellent strength to the waveguide mode converter 100. In the example shown, the support substrate 3 supports the substrate made of an inorganic material 2 via the second grounding layer 42 and a connecting section 6 (described later). The support substrate 3 is bonded to the substrate made of an inorganic material 2 to reinforce the substrate made of an inorganic material 2. In other words, the support substrate 3 is a reinforcing substrate for strengthening the substrate made of an inorganic material 2. With this configuration, the substrate made of an inorganic material 2 can be made thinner, as described above. The support substrate 3 has a suitable structure.

[0083] Examples of materials for forming the support substrate 3 include indium phosphide (InP), silicon (Si), glass, SiAlON (Si3N4-Al2O3), mullite (3Al2O3·2SiO2, 2Al2O3·3SiO2), aluminum nitride (AlN), magnesium oxide (MgO), aluminum oxide (Al2O3), spinel (MgAl2O4), sapphire, quartz, crystalline quartz, gallium nitride (GaN), silicon carbide (SiC), silicon nitride (Si3N4) and gallium oxide (Ga2O3).

[0084] The thermal conductivity of the material for forming the support substrate 3 is preferably 150 W / K · m or more, more preferably 200 W / K · m or more.

[0085] When the external device is connected to the waveguide mode converter 100, the substrate made of an inorganic material 2 can be heated by the external device, and the heat from the substrate made of an inorganic material 2 can negatively affect the external device. In this regard, if the material used to form the support substrate 3 has the aforementioned thermal conductivity, the support substrate 3 acts as a heat sink or heat sink, and thus the heat from the substrate made of an inorganic material 2 can be easily dissipated.

[0086] Of the materials for forming the support substrate 3, silicon (thermal conductivity: about 160 W / K · m), silicon carbide (thermal conductivity: about 270 W / K · m) and aluminium nitride (thermal conductivity: from about 150 W / K · m to about 250 W / K · m) are preferred with regard to thermal conductivity.

[0087] Furthermore, the linear coefficient of expansion of the material used to form the support substrate 3 is preferably as close as possible to the linear coefficient of expansion of the material used to form the substrate from an inorganic material 2. The linear coefficient of expansion of the material used to form the support substrate 3 lies within the range of, for example, 50% to 150% relative to the linear coefficient of expansion of the material used to form the substrate from an inorganic material 2. If the linear coefficient of expansion of the material used to form the support substrate 3 lies within such a range, thermal deformation (typically warping) of the waveguide mode converter 100 can be prevented.

[0088] Of these materials for forming the 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 particularly preferred.

[0089] As it is in the Fig. As shown in Figure 2, the support substrate 3 in one embodiment comprises the recess 31, which corresponds to the cavity section 5. With such a structure, in which the dimension of the recess 31 is adjustable, the dimension of the cavity section 5 can be set with high accuracy over a relatively wide range. Accordingly, the backshort section BS can be easily obtained with a desired dimension.

[0090] The recess 31 is typically formed from an upper surface (surface on the side of the substrate made of an inorganic material 2) of the support substrate 3 downwards (in the direction away from the substrate made of an inorganic material 2). Viewed from the thickness direction of the substrate made of an inorganic material 2, the recess 31 has the same shape as that of the cavity section 5. In the example shown, the recess 31, in a cross-sectional surface obtained by cutting the support substrate 3 in its thickness direction, is essentially U-shaped and open towards the substrate made of an inorganic material 2. An internal surface of the recess 31 comprises side surfaces and a bottom surface. In the example shown, the side surfaces of the recess 31 extend in the thickness direction of the substrate made of an inorganic material 2.The lower surface of the recess 31 extends in a direction that intersects the thickness direction of the substrate made of an inorganic material 2 (typically in a direction orthogonal to it).

[0091] As it is in the Fig. As shown in Figure 9, the side surface of the recess 31 can be inclined relative to the thickness direction of the substrate made of an inorganic material 2. In the example shown, the side surface of the recess 31 is inclined inwards as it is removed from the substrate made of an inorganic material 2. Furthermore, as shown in the Fig. As shown in 10, the side surface of the recess 31 has a step difference. B-4. Second conductor layer

[0092] As it is in the Fig. As shown in Figure 2, the waveguide mode converter 100 in one embodiment comprises a second conductor layer 4. The second conductor layer 4 is arranged between the substrate made of an inorganic material 2 and the support substrate 3. The second conductor layer 4 is typically arranged on the upper surface (surface on the side of the substrate made of an inorganic material 2) of the support substrate 3 and is brought into direct contact with the support substrate 3.

[0093] The second conductor layer 4 comprises at least the backshort conductor layer 41. In the example shown, the backshort conductor layer 41 is arranged on the entire inner surface of the recess 31 of the support substrate 3.

[0094] In one embodiment, the second conductor layer 4 further comprises the second grounding layer 42. The second grounding layer 42 is arranged in any suitable position as long as it surrounds the cavity section 5, as described above. The second grounding layer 42 is arranged on a portion of the upper surface (surface on the side of the substrate made of an inorganic material 2) of the support substrate 3 that does not include the recess 31. The second grounding layer 42 may be arranged partially on the portion of the upper surface of the support substrate 3 that does not include the recess 31 (see the Fig. 11), or can be arranged on the entire part of the upper surface of the support substrate 3 that does not include the recess 31 (see the Fig. 4).

[0095] In one embodiment, the second grounding layer 42 is arranged over the entire portion of the upper surface of the support substrate 3 that does not include the recess 31. In the example shown, the second grounding layer 42 and the backshort conductor layer 41 are continuous with each other. Furthermore, as shown in the Fig. As shown in Figure 12, the second conductor layer 4 is formed only from the backshort conductor layer 41, without including the second grounding layer 42.

[0096] The second conductor layer 4, for example, is made of the same metal as that of the first conductor layer 1.

[0097] The thickness of the second conductor layer 4 is typically 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

[0098] As it is in the Fig. 1 and the Fig. As shown in Figure 2, the waveguide mode converter 100 in one embodiment further comprises the connecting section 6. The connecting section 6 connects the substrate made of an inorganic material 2 and the support substrate 3. In the example shown, the connecting section 6 is provided at least between the substrate made of an inorganic material 2 and the second grounding layer 42.

[0099] The connecting section 6 can be formed from an organic material (typically an organic adhesive) or from an inorganic material. In one embodiment, the connecting section 6 is formed from an inorganic material. Examples of the inorganic material for forming the connecting section 6 include SiO2, amorphous silicon, and tantalum oxide, with amorphous silicon being preferred.

[0100] The thickness of the connecting section 6 is, for example, from 0.001 µm to 10 µm, preferably from 0.01 µm to 3 µm.

[0101] A material for forming the connecting section 6 can be an amorphous material of the material for forming the substrate from an inorganic material 2, an amorphous material of the material for forming the support substrate 3, or the material of the second grounding layer 42.

[0102] The connecting section 6 can have a single-layer structure or a laminate structure. If the connecting section 6 has a laminate structure, layers made of materials that are different from each other, or materials that are the same material but have different compositions or densities, are laminated together.

[0103] In one embodiment, the substrate made of an inorganic material 2 and the support substrate 3 are directly bonded together. With this configuration, the bonding section 6 between the substrate made of an inorganic material 2 and the support substrate 3 is formed. As used here, the term "direct bonding" means that two layers or substrates are joined without an intervening organic material (typically an organic adhesive). The form of the direct bonding can be adjusted according to the configurations of the layers or substrates to be joined. Furthermore, an interface formed by direct bonding is typically amorphous. Consequently, the thermal stability of the bonded interface can be significantly reduced compared to resin bonding.Consequently, when the external device is connected to the waveguide mode converter 100, even if heat generated by the external device is transferred to the substrate made of inorganic material 2, this heat can easily escape from the substrate made of inorganic material 2 via the support substrate 3 to a housing. As a result, the heat can be efficiently dissipated from the substrate made of inorganic material 2, and a deterioration of the properties of the external device can be prevented.

[0104] Furthermore, if these components are integrated by direct connection, detachment in the waveguide mode converter 100 can be satisfactorily prevented, and as a result, damage (e.g., a crack) to the substrate made of an inorganic material 2 resulting from such detachment can be satisfactorily prevented.

[0105] Furthermore, if these components are integrated by direct bonding without an intervening resin, the thermal and chemical resistance can be improved in a backend manufacturing process, thus increasing the flexibility in selecting a manufacturing method for the waveguide mode converter 100. Additionally, compared to a case where the connection section 6 is made of an organic material, the coefficient of thermal expansion and the water absorption rate of the connection section 6 can be reduced. As a result, the bond reliability between the substrate made of an inorganic material 2 and the support substrate 3 can be improved, and the reliability of the waveguide mode converter 100 as a device exposed to an external environment can be enhanced.

[0106] The connecting section 6 can have a single-layer structure or a laminate structure. As described in the Fig. As shown in Figure 2, the connecting section 6 in one embodiment has a laminate structure. The connecting section 6 comprises a first connecting layer 61 and a second connecting layer 62.

[0107] In one embodiment, the first interconnect layer 61 is arranged on a surface of the substrate made of an inorganic material 2. In particular, the first interconnect layer 61 is arranged on a surface of the substrate made of an inorganic material 2 on the side opposite the first conductor layer 1 in the thickness direction of the substrate made of an inorganic material 2. In the example shown, the first interconnect layer 61 is arranged on the lower surface (surface on the side opposite the first conductor layer 1) of the substrate made of an inorganic material 2 and is in direct contact with the substrate made of an inorganic material 2. The first interconnect layer 61 can be arranged partially on the lower surface of the substrate made of an inorganic material 2 or can be arranged on the entire lower surface of the substrate made of an inorganic material 2.In the example shown, the first compound layer 61 is arranged on the entire lower surface of the substrate made of an inorganic material 2.

[0108] The thickness of the first compound layer 61 is, for example, from 0.5 nm to 5 µm, preferably from 0.01 µm to 1.5 µm, more preferably from 0.01 µm to 0.05 µm.

[0109] In one embodiment, the second interconnection layer 62 is arranged on a surface of the second grounding layer 42. In particular, the second interconnection layer 62 is arranged on a surface of the second grounding layer 42 on a side opposite the support substrate 3 in the thickness direction of the substrate made of an inorganic material 2. In the example shown, the second interconnection layer 62 is arranged on an upper surface (surface on the side opposite the support substrate 3) of the second grounding layer 42 and is in direct contact with the second grounding layer 42. The second interconnection layer 62 can be arranged only on the second grounding layer 42 or can be arranged on the backshort conductor layer 41 in addition to the second grounding layer 42.In the example shown, the second interconnect layer 62 is arranged on the entire upper surface of each of the backshort conductor layer 41 and the second ground layer 42. In other words, the second interconnect layer 62 is stacked on the entire second conductor layer 4.

[0110] The range of thickness of the second compound layer 62 is, for example, identical to the aforementioned range of thickness of the first compound layer 61.

[0111] The second connection layer 62 is connected to the first connection layer 61 for integration. In the example shown, a portion of the second connection layer 62, located on the second grounding layer 42, is directly connected to the first connection layer 61.

[0112] Furthermore, as is described in the Fig. Figure 6 shows that the waveguide mode converter 100 includes the leakage suppression section 7, the leakage suppression section 7 typically being collectively defined by the substrate of an inorganic material 2 and the interconnection section 6 (the first interconnection layer 61 and the second interconnection layer 62).

[0113] As it is in the Fig. As shown in Figure 12, if the second conductor layer 4 is formed only on the backshort conductor layer 41, at least a part of the connection section 6 is located between a part of the upper surface of the support substrate 3, which does not include the recess 31, and the substrate made of an inorganic material 2, and connects the part of the upper surface of the support substrate 3 and the substrate made of an inorganic material 2. B-6. Cavity section

[0114] In one embodiment as described in the Fig. As shown in Figure 2, the cavity section 5 is incorporated into the backshort section BS and is formed by a groove (recess 31) in the support substrate 3. The cavity section 5 is typically defined by the lower surface of the substrate made of an inorganic material 2 (in particular, the mode-conversion part 21) and the inner surface of the recess 31. In the example shown, the cavity section 5 contains the first interconnect layer 61, which is located on the lower surface of the substrate made of an inorganic material 2 (mode-conversion part 21), the backshort conductor layer 41, which is located on the inner surface of the recess 31, and the second interconnect layer 62, which is located on the upper surface of the backshort conductor layer 41.

[0115] Furthermore, in one embodiment, the cavity section 5 comprises a space containing air. This space is defined by the lower surface of the substrate made of an inorganic material 2 (mode conversion part 21) or the first compound layer 61 arranged on the lower surface of the substrate made of an inorganic material 2, and the upper surface of the backshort conductor layer 41 or the second compound layer 62 arranged on the upper surface of the backshort conductor layer 41.

[0116] As it is in the Fig. As shown in Figure 3, when the waveguide mode converter 100 includes the waveguide element 8, which encompasses the hollow waveguide, air is also present in the hollow waveguide. That is, air is present in each of the cavity section 5 enclosed in the backshort section BS and in the hollow waveguide. Thus, compared to a case where the cavity section 5 enclosed in the backshort section BS is filled with a dielectric material, a high-order mode can be stably prevented, and the backshort section BS can be designed simply. The space enclosed in the cavity section 5 can also be brought into a vacuum state.

[0117] Cavity section 5 has a suitable and appropriate shape and size. With the shape and size of cavity section 5 adjusted, the properties of the waveguide mode converter 100 (e.g., a resonant frequency or a band) can be appropriately and effectively set.

[0118] The shape of the cavity section 5, viewed from the thickness direction of the substrate made of an inorganic material 2, is suitably and expediently modified according to a cross-sectional shape of the hollow waveguide incorporated into the waveguide element 8. Examples of the shape of the cavity section 5, viewed from the thickness direction of the substrate made of an inorganic material 2, include a triangle, a quadrilateral, a pentagon, essentially a polygon with six or more sides, an essentially circular shape, and an essentially oval shape.

[0119] In one embodiment, the shape of the cavity section 5, viewed from the thickness direction of the substrate made of an inorganic material 2, is essentially identical to the cross-sectional shape of the hollow waveguide. In the example shown, the cavity section 5, viewed from the thickness direction of the substrate made of an inorganic material 2, has a substantially rectangular shape that is identical to the cross-sectional shape of the hollow waveguide (see the Fig. 1).

[0120] Furthermore, in a cross-sectional surface obtained by cutting the waveguide mode converter 100 in the thickness direction of the substrate made of an inorganic material 2, the cavity section 5 exhibits any suitable shape. Examples of the cross-sectional shape of the cavity section 5 include a triangle, a quadrilateral (see the Fig. 2 and Fig. 9), a pentagon and essentially a polygon with six or more sides (cf. the Fig. 10).

[0121] A maximum dimension “d” (hereinafter referred to as “depth d”) of the cavity section 5 in the thickness direction of the substrate made of an inorganic material 2 is suitably and expediently modified according to the design of the waveguide mode converter 100 and the frequency of the electromagnetic wave guided through the waveguide mode converter 100. In one embodiment, the depth “d” of the cavity section 5 is set within a range of (λg / 4) / 3 µm to (λg / 4) × 4 µm. λg represents a wavelength in the tube [µm] of the hollow waveguide incorporated into the waveguide element 8.

[0122] The depth “d” of the cavity section 5 is in particular from 10 µm to 500 µm. The depth “d” of the cavity section 5 refers to a distance in the thickness direction of the substrate made of an inorganic material 2 between the substrate made of an inorganic material 2 (in particular a surface in the mode-conversion part 21 on a side opposite the first conductor layer 1) and the backshort conductor layer 41, which is located on the lower surface of the recess 31 (in particular a surface of the backshort conductor layer 41 on a side opposite the support substrate 3). B-7. Waveguide element

[0123] In one embodiment, the waveguide mode converter 100 comprises the waveguide element 8, which includes a hollow waveguide. Examples of the waveguide element 8, which includes the hollow waveguide, include a waveguide tube 8a and a waveguide substrate 8b.

[0124] The waveguide tube 8a typically extends in the thickness direction of the substrate made of an inorganic material 2. An interior space of the waveguide tube 8a acts as the hollow waveguide. Examples of waveguide tube 8a materials include a metal corresponding to that of the first conductor layer 1 described above. The waveguide tube 8a can be rectangular or circular.

[0125] As it is in the Fig. As shown in Figure 13, the waveguide substrate 8b typically comprises a substrate body 81 with a through-hole 83 and a metal layer 82. The metal layer 82 is arranged on at least one inner surface of the through-hole 83. In one embodiment, the metal layer 82 is arranged on the entire surface of the substrate body 81, including the inner surface of the through-hole 83. Examples of a material for the metal layer 82 include a metal corresponding to that of the first conductor layer 1 described above. In the waveguide substrate 8b, a space enclosed by the metal layer 82, which is arranged on the inner surface of the through-hole 83, is formed as the hollow waveguide. C. Method for manufacturing the waveguide mode converter

[0126] Next, with reference to the Fig. 3 an embodiment of a method for manufacturing the waveguide mode converter 100 is described.

[0127] In one embodiment, the support substrate 3, which includes the recess 31, is first produced. The recess 31 is formed in the support substrate 3, for example, by reactive ion etching.

[0128] The second conductor layer 4 is then formed on the upper surface of the support substrate 3, in which the recess 31 is formed. Any suitable film formation process can be used as the method for forming the second conductor layer 4. Examples of film formation processes include sputtering, plating, and vapor deposition, with plating being preferred.

[0129] The substrate is then produced from an inorganic material 2, and the substrate and the support substrate 3 are directly bonded together. Specifically, the first compound layer 61 is formed on the lower surface of the substrate made of inorganic material 2. Furthermore, the second compound layer 62 is formed on the upper surface of the second conductor layer 4. Examples of methods for forming these layers include sputtering, plating, and vapor deposition, with sputtering being preferred. The surface of each of the first compound layer 61 and the second compound layer 62 is polished to a planar finish as required.

[0130] Direct connection can be achieved, for example, by the following procedure. In a high-vacuum chamber (e.g., approximately 1 × 10⁻⁶ m³ / s²), -6In this process, the interface surface of each of the components (layers or substrates) to be joined is irradiated with a neutralized beam. In one embodiment, when surface activation is performed with a neutralized beam, an inert gas is introduced into a chamber, and a high voltage is applied from a DC power source to an electrode located in the chamber. With such a setup, an electric field generated between the electrode (positive electrode) and the chamber (negative electrode) causes electrons to move, generating atomic and electron beams derived from the inert gas. Of the beams that reach a grating, the ion beam is neutralized at the grating, thus emitting a beam of neutral atoms from a high-speed atomic beam source. An atomic species for beam formation is preferably an inert gas element (e.g., argon (Ar) or nitrogen (N)).During activation by beam irradiation, the voltage is, for example, from 0.5 kV to 2.0 kV and the current is, for example, from 50 mA to 200 mA. The duration of irradiation with the neutralized beam is, for example, from 10 seconds to 300 seconds, preferably from 30 seconds to 120 seconds.

[0131] This irradiation activates every interface surface, especially the inorganic material present on each of the irradiated surfaces.

[0132] Then, in a vacuum atmosphere at a normal temperature (23 °C), the activated surfaces are brought into contact with each other. The load at the time of contact can range, for example, from 100 N to 20,000 N. Consequently, the first compound layer 61 and the second compound layer 62 are joined together, and the compound section 6 is formed.

[0133] These steps result in a laminate with the structure consisting of the substrate (an inorganic material 2), the interconnection section (6), the second conductor layer (4), and the support substrate (3). The direct bonding method is not limited to this; for example, a surface activation method using a fast atomic beam (FAB) or an ion gun, an atomic diffusion method, or a plasma bonding method can also be employed.

[0134] The laminate may be subjected to a heating treatment. This treatment can increase the bond strength between the inorganic substrate and the carrier substrate. The heating temperature is, for example, from 60 °C to 140 °C, preferably from 80 °C to 120 °C. The heating period is, for example, from 10 minutes to 5 hours, preferably from 30 minutes to 3 hours.

[0135] Furthermore, joining methods other than the direct joining method can be used.

[0136] For example, a high vacuum chamber (e.g., about 1 × 10) is used. -6Components (layers or substrates) to be joined are introduced, and the interface of a first component, which is one of these components (layers or substrates), is irradiated with a high-speed atomic beam using an inert gas, such as argon, as the atomic species. The material of the first component then adheres from the interface surface to the interface surface of a second component, which is another of the components, as a sputter layer. The resulting sputter layer is a material composed of atoms that make up the first component and may also contain atoms from the inert gas or from any device or equipment used. In this case, the sputter layer may be an amorphous layer.In this way, a compound layer formed from the material of the first component is created on the interface surface of the second component. Next, in a vacuum atmosphere at a standard temperature (23 °C), the irradiated surface of the first component and the surface of the compound layer formed on the second component are brought into contact and pressure is applied.

[0137] Even in this way, the first component and the second component can be connected to each other via the connecting section.

[0138] After joining, the amorphous layers of the first component and the second component can be formed between the first component and the bonding layer and / or between the second component and the bonding layer.

[0139] By using this joining method, the thickness of the joining layer can be reduced and the joining strength can be increased, thus increasing the heat dissipation capacity and the reliability of the waveguide mode converter 100 as a device.

[0140] The substrate, made of an inorganic material 2, is then polished, if necessary to thin it, so that it has the aforementioned thickness. Examples of the polishing process include chemical-mechanical polishing (CMP).

[0141] The first conductive layer 1 is then formed on the upper surface of the substrate made of an inorganic material 2. In one embodiment, after a photoresist with an opening corresponding to the first conductive layer has been formed on the upper surface of the substrate made of an inorganic material 2, the first conductive layer is formed using the photoresist. Examples of a method for forming a metal film include sputtering, plating, and vapor deposition, with plating being preferred.

[0142] Consequently, the waveguide mode converter 100 is manufactured, which has the structure of the first conductor layer 1 / the substrate made of an inorganic material 2 / the connecting section 6 / the second conductor layer 4 / the support substrate 3 and which includes the cavity section 5.

[0143] The waveguide element 8, which includes the hollow waveguide, is then positioned, if necessary, with respect to the first end section E1 of the signal wiring 12. In this way, the transducer 101, which is provided with a waveguide element, is manufactured.

[0144] If the waveguide element 8 is the waveguide tube 8a, for example, a housing is manufactured to which the waveguide tube 8a is attached, and the waveguide mode converter 100 is inserted into the housing. In this way, the waveguide tube 8a is positioned with respect to the first end section E1 of the signal wiring 12.

[0145] Furthermore, as stated in the Fig.Figure 13 shows that if the waveguide element 8 is the waveguide substrate 8b, for example, the waveguide substrate 8b is attached to a part of the first conductor layer 1 that does not include the signal wiring 12, and / or to a part of the substrate made of an inorganic material 2 that is exposed by the first conductor layer 1. In this way, the waveguide substrate 8b is positioned with respect to the first end section E1 of the signal wiring 12.

[0146] Examples of methods for attaching the waveguide substrate 8b include flip-chip mounting and the aforementioned direct connection, with direct connection being preferred. If direct connection is selected as the method for attaching the waveguide substrate 8b, the hollow waveguide tube of the waveguide substrate 8b can be stably positioned near the first end section E1 of the signal wiring 12. Accordingly, electromagnetic wave leakage between the hollow waveguide and the signal wiring 12 can be prevented. Commercial applicability

[0147] The waveguide mode converter according to the embodiments of the present disclosure can be used in a wide range of fields, such as next-generation high-speed communication devices and sensors, and can be used particularly advantageously in next-generation high-speed communication devices. Reference symbol list 1 First conductor layer 11 First earthing layer 12 Signal wiring 2. Substrate made of an inorganic material 3 Carrier substrate 4 Second conductor layer 41 Backshort ladder layer 5 Cavity section 6 Connection section 100 waveguide mode converters QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] JP 2008-193162 A

[0004]

Claims

[1] Waveguide mode converter, comprising: a substrate made of an inorganic material; a first conductor layer that is arranged on one side of the substrate made of an inorganic material in a thickness direction of the substrate made of an inorganic material; a support substrate which is arranged on one side opposite the first conductor layer with respect to the substrate made of an inorganic material; a cavity section arranged on the side opposite the first conductor layer with respect to the substrate made of an inorganic material and arranged on the side of the substrate made of an inorganic material of the support substrate; and a backshort conductor layer arranged in the cavity section, wherein the first conductor layer comprises a signal wiring which forms a planar conductor designed to conduct an electromagnetic wave, and wherein the signal wiring has an end section which overlaps the cavity section viewed from the thickness direction of the substrate made of an inorganic material. [2] Waveguide mode converter according to claim 1, wherein the substrate made of an inorganic material includes a mode-transition part which overlaps the cavity section viewed from the thickness direction of the substrate made of an inorganic material, wherein the waveguide mode converter further comprises a leakage suppression section designed to prevent leakage of the electromagnetic wave from the mode conversion part, and wherein the leakage suppression section is arranged such that it passes through the substrate made of an inorganic material and surrounds the mode conversion part. [3] Waveguide mode converter according to claim 2, wherein the leakage suppression section is formed from a plurality of conductor columns arranged at intervals from one another. [4] Waveguide mode converter according to claim 2, wherein the leakage suppression section is formed from a conductor wall which extends continuously such that it surrounds the mode conversion part. [5] Waveguide mode converter according to claim 1, wherein the first conductor layer further comprises a first grounding layer which is arranged at a distance from one end section of the signal wiring such that it surrounds one end section of the signal wiring. [6] Waveguide mode converter according to claim 5, further comprising a second grounding layer arranged in a part that is distinct from the cavity section between the substrate made of an inorganic material and the support substrate, wherein the second grounding layer is arranged such that it surrounds the cavity section viewed from the thickness direction of the substrate made of an inorganic material. [7] Waveguide mode converter according to claim 6, wherein the first grounding layer and the second grounding layer are electrically connected to each other. [8] Waveguide mode converter according to any one of claims 1 to 7, further comprising a waveguide element arranged on a side opposite the substrate made of an inorganic material with respect to the first conductor layer, wherein the waveguide element comprises a hollow waveguide extending in the thickness direction of the substrate made of an inorganic material, and wherein the hollow waveguide is opposite one end section of the signal wiring in the thickness direction of the substrate made of an inorganic material. [9] Waveguide mode converter according to claim 8, wherein the planar line formed from the signal wiring is configured to conduct an electromagnetic wave in a quasi-TEM mode, and wherein the hollow waveguide is designed to guide an electromagnetic wave in a TE mode. [10] Waveguide mode converter according to any one of claims 1 to 7, further comprising a connecting section designed to connect the substrate made of an inorganic material and the support substrate. [11] Waveguide mode converter according to any one of claims 1 to 7, wherein the substrate made of an inorganic material has a thickness of 100 µm or less. [12] Waveguide mode converter according to any one of claims 1 to 7, wherein the substrate is formed from an inorganic material made of quartz glass. [13] Waveguide mode converter according to any one of claims 1 to 7, wherein the frequency of the electromagnetic wave that can be guided in the waveguide mode converter is from 20 GHz to 20 THz.

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