Terahertz device

Abstract

This terahertz device comprises: a semiconductor substrate that has a substrate front surface and a substrate back surface opposite to the substrate front surface; a metal layer that is provided on at least a portion of the substrate front surface; a dielectric layer that covers the substrate front surface in addition to the metal layer; an active element that is provided in the dielectric layer and that is configured to oscillate or detect electromagnetic waves; and an antenna that is provided on the dielectric layer and electrically connected to the active element and that is configured to radiate or receive the electromagnetic waves. The metal layer, when viewed in the direction orthogonal to the substrate front surface, is formed at the same position as at least the antenna on the substrate front surface. The metal layer is electrically in a floating state.

Description

Terahertz Device

[0001] The present disclosure relates to terahertz devices.

[0002] In recent years, as electronic devices such as transistors have become increasingly miniaturized and their size has reached nanoscale, a phenomenon known as the quantum effect has become observable. Development is underway to utilize this quantum effect to realize ultrafast devices and devices with new functions.

[0003] In such an environment, attempts are being made to utilize electromagnetic waves in a frequency range called the terahertz band, which has a frequency of 0.1 THz to 10 THz, to perform high-capacity communication, information processing, imaging, measurement, etc. This frequency range combines the properties of both light and radio waves, and if devices operating in this frequency band are realized, they could be used for many applications, including the aforementioned imaging, high-capacity communication, and information processing, as well as measurements in various fields such as physical properties, astronomy, and biology.

[0004] As an element for emitting or receiving electromagnetic waves in the terahertz band, for example, a terahertz device having a structure in which a resonant tunneling diode and a fine slot antenna are integrated is known (see, for example, Patent Document 1).

[0005] Japanese Patent Application Laid-Open No. 2020-115500

[0006] However, when electromagnetic waves propagate through components arranged around the resonant tunneling diode of a terahertz device, there is a risk that electromagnetic waves of a frequency different from the desired frequency will be generated.

[0007] A terahertz device according to one aspect of the present disclosure comprises a semiconductor substrate having a substrate surface and a substrate back surface opposite the substrate surface, a metal layer provided on at least a portion of the substrate surface, a dielectric layer covering the substrate surface together with the metal layer, an active element provided in the dielectric layer for oscillating or detecting electromagnetic waves, and an antenna provided on the dielectric layer, electrically connected to the active element, and for emitting or receiving the electromagnetic waves, wherein the metal layer is formed at a position on the substrate surface that overlaps with at least the antenna when viewed from a direction perpendicular to the substrate surface, and the metal layer is in an electrically floating state.

[0008] The terahertz device of the present disclosure can suppress the generation of electromagnetic waves with frequencies different from the electromagnetic waves with a desired frequency.

[0009] FIG. 1 is a schematic plan view of a terahertz device according to a first embodiment. FIG. 2 is a schematic side view of the terahertz device of FIG. 1. FIG. 3 is a schematic cross-sectional view of the terahertz device taken along line F3-F3 in FIG. 1. FIG. 4 is a schematic cross-sectional view of an active element of the terahertz device of FIG. 1, with the active element and its periphery enlarged. FIG. 5 is a schematic cross-sectional view of an active element of the terahertz device of FIG. 4, with the periphery enlarged. FIG. 6 is a schematic side view of a terahertz device according to a comparative example. FIG. 7 is a schematic side view of a terahertz device according to the first embodiment. FIG. 8 is a graph showing the relationship between the frequency of an electromagnetic wave and the real part of the admittance. FIG. 9 is a graph showing the relationship between the frequency of an electromagnetic wave and the imaginary part of the admittance. FIG. 10 is a schematic cross-sectional view of a terahertz device according to a second embodiment. FIG. 11 is a graph showing the relationship between the thickness of the dielectric layer of the terahertz device of FIG. 10 and the radiation efficiency of the electromagnetic wave. FIG. 12 is a schematic plan view of a terahertz device according to a third embodiment. FIG. 13 is a schematic plan view of a terahertz device according to a fourth embodiment. FIG. 14 is a schematic cross-sectional view of a terahertz device taken along line F14-F14 in FIG. 13. FIG. 15 is a schematic plan view of a terahertz device according to a fifth embodiment. FIG. 16 is a schematic cross-sectional view of a terahertz device taken along line F16-F16 in FIG. 15. FIG. 17 is a schematic cross-sectional view of a terahertz device taken along line F17-F17 in FIG. 15. FIG. 18 is a schematic cross-sectional view of an active element and its periphery in a terahertz device according to a modified example, enlarging the active element and its periphery in a terahertz device according to a modified example. FIG. 19 is a schematic cross-sectional view of an active element and its periphery in a terahertz device according to a modified example, enlarging the active element and its periphery in a terahertz device according to a modified example. FIG. 20 is a schematic plan view of a terahertz device according to a modified example. FIG. 21 is a schematic plan view of a terahertz device according to a modified example. FIG. 22 is a schematic cross-sectional view of a terahertz device taken along line F22-F22 in FIG. 21. FIG. 23 is a schematic plan view of a terahertz device according to a modified example. FIG. 24 is a schematic cross-sectional view of a terahertz unit according to a first application example of the terahertz device. Fig. 25 is a schematic cross-sectional view of a terahertz unit according to a second application example of the terahertz device. Fig. 26 is a schematic plan view of a terahertz unit according to a third application example of the terahertz device.

[0010] Hereinafter, several embodiments of the terahertz device of the present disclosure will be described with reference to the accompanying drawings. Note that for simplicity and clarity of explanation, the components shown in the drawings are not necessarily drawn to scale. Also, for ease of understanding, hatching lines may be omitted in cross-sectional views. The accompanying drawings merely illustrate embodiments of the present disclosure and should not be considered as limiting the present disclosure.

[0011] The following detailed description includes devices, systems, and methods embodying exemplary embodiments of the present disclosure. This detailed description is merely illustrative in nature and is not intended to limit the embodiments of the present disclosure or the application and uses of such embodiments.

[0012] (General Configuration of Terahertz Device) First Embodiment A general configuration of a terahertz device 10 according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0013] 1 and 2, the terahertz device 10 is formed in a rectangular parallelepiped shape. The terahertz device 10 includes a device front surface 11, a device back surface 12 opposite the device front surface 11, and device side surfaces 13 to 16 extending between the device front surface 11 and the device back surface 12. In this embodiment, the direction perpendicular to the device front surface 11 is referred to as the "z direction." Two directions perpendicular to the z direction that are orthogonal to each other are referred to as the "x direction" and the "y direction," respectively.

[0014] Device side surface 13 and device side surface 14 are spaced apart from each other in the x direction. Both device side surface 13 and device side surface 14 extend along the yz plane. Device side surface 15 and device side surface 16 are spaced apart from each other in the y direction. Both device side surface 15 and device side surface 16 extend along the xz plane.

[0015] As shown in Fig. 2, the terahertz device 10 includes a semiconductor substrate 20. The semiconductor substrate 20 is formed in a flat plate shape. As shown in Fig. 1, the shape of the semiconductor substrate 20 when viewed from the z direction is rectangular. Note that the shape of the semiconductor substrate 20 when viewed from the z direction is not limited to rectangular, and may be circular, elliptical, or polygonal. The semiconductor substrate 20 may be made of any of a variety of materials, including InP (indium phosphide), GaAs (gallium arsenide), AlGaAs (aluminum gallium arsenide), InGaAs (indium gallium arsenide), InGaAsP (indium gallium arsenide phosphide), Si (silicon), SiC (silicon carbide), GaN (gallium nitride), and GaN ２ In this embodiment, the semiconductor substrate 20 is made of a material containing InP.

[0016] 2, the semiconductor substrate 20 has a substrate front surface 21 and a substrate back surface 22 opposite the substrate front surface 21. The substrate front surface 21 faces the same side as the device front surface 11, and the substrate back surface 22 faces the same side as the device back surface 12. The semiconductor substrate 20 has substrate side surfaces that form part of each of the device side surfaces 13 to 16. Because the substrate front surface 21 faces the same side as the device front surface 11, the z direction is a direction perpendicular to the substrate surface 21. Therefore, "viewed from the z direction" refers to viewing from a direction perpendicular to the substrate surface 21.

[0017] The terahertz device 10 includes a metal layer 30 provided on at least a portion of a substrate surface 21, and a dielectric layer 40 covering the substrate surface 21 together with the metal layer 30. In this embodiment, the metal layer 30 is in contact with the substrate surface 21. The metal layer 30 has a surface 31 and a back surface 32 opposite the surface 31. The surface 31 faces the same side as the substrate surface 21, and the back surface 32 faces the same side as the substrate back surface 22. The back surface 32 is in contact with the substrate surface 21. Note that another member, such as an insulating layer, may be interposed between the metal layer 30 and the substrate surface 21.

[0018] The metal layer 30 is formed of at least one metal material selected from the group consisting of gold (Au), silver (Ag), aluminum (Al), copper (Cu), titanium (Ti), titanium nitride (TiN), and platinum (Pt). It can also be said that the metal layer 30 contains at least one of Au, Ag, Al, Cu, Ti, and Pt. In this embodiment, the metal layer 30 is formed of a material containing Au. The metal layer 30 is formed by, for example, sputtering. The metal layer 30 may also be formed of a stacked structure of multiple metal layers.

[0019] The dielectric layer 40 is made of an insulating material, such as silicon oxide (SiO ２ In this embodiment, the dielectric layer 40 is formed over the entire surface 31 of the metal layer 30 .

[0020] The dielectric layer 40 has a front surface 41 and a back surface 42 opposite to the front surface 41. The front surface 41 faces the same side as the front surface 21 of the substrate, and the back surface 42 faces the same side as the back surface 22 of the substrate. The front surface 41 constitutes the device surface 11. The back surface 42 is in contact with the front surface 31 of the metal layer 30. Note that another member such as an insulating layer may be interposed between the front surface 31 of the metal layer 30 and the dielectric layer 40.

[0021] As shown in FIGS. 1 and 3 , the terahertz device 10 includes an active element 50 disposed within a dielectric layer 40 and an antenna 60 disposed on the dielectric layer 40. The active element 50 converts electromagnetic waves into electrical energy. Note that the term "electromagnetic waves" encompasses the concepts of either light or radio waves, or both. The active element 50 is an element that emits electromagnetic waves (terahertz waves) in a predetermined frequency band, for example, the terahertz band. In this case, the active element 50 can be considered a terahertz element that emits terahertz waves. Alternatively, for example, the active element 50 can be an element that detects terahertz waves, which are electromagnetic waves in a predetermined frequency band, for example, the terahertz band. In this case, the active element 50 can be considered a terahertz element that receives terahertz waves. Here, the frequency band of the terahertz waves is, for example, 0.1 THz to 10 THz.

[0022] The active element 50 converts the supplied electrical energy into electromagnetic waves by oscillating with the supplied electrical energy. As a result, the active element 50 oscillates electromagnetic waves in a desired frequency band. The active element 50 also receives electromagnetic waves and converts the electromagnetic waves into electrical energy. As a result, the active element 50 detects electromagnetic waves in a desired frequency band.

[0023] The shape of the active element 50 when viewed from the z direction is rectangular. Note that the shape of the active element 50 when viewed from the z direction is not limited to a rectangular shape, and may be any of a circular shape, an elliptical shape, and a polygonal shape.

[0024] 1, in this embodiment, the antenna 60 is configured as a dipole antenna. More specifically, the antenna 60 has a first antenna unit 61 and a second antenna unit 62 extending in opposite directions in the x direction. The first antenna unit 61 and the second antenna unit 62 are arranged at the same position in the y direction and spaced apart from each other in the x direction. The first antenna unit 61 is positioned closer to the device side surface 13 than the second antenna unit 62.

[0025] The antenna 60 is electrically connected to the active element 50. When the active element 50 oscillates electromagnetic waves, the antenna 60 radiates the electromagnetic waves from the active element 50 to the outside of the terahertz device 10. When the active element 50 detects electromagnetic waves, the antenna 60 receives electromagnetic waves incident from the outside of the terahertz device 10.

[0026] The antenna 60 is made of at least one metal material selected from the group consisting of Au, Ag, Al, Cu, Ti, TiN, and Pt. In this embodiment, the antenna 60 is made of a material containing Au. In other words, the antenna 60 is made of the same material as the metal layer 30.

[0027] The terahertz device 10 includes a first electrode 70 and a second electrode 80 provided on the dielectric layer 40. The first electrode 70 and the second electrode 80 are electrically connected to the antenna 60. In this embodiment, the first electrode 70 and the second electrode 80 are formed integrally with the antenna 60.

[0028] The first electrode 70 and the second electrode 80 are disposed closer to the device side surface 16 than the antenna 60. The first electrode 70 and the second electrode 80 are disposed side by side in the x direction. The first electrode 70 is disposed closer to the device side surface 14 than the second electrode 80. The first electrode 70 and the second electrode 80 are formed of at least one metal material selected from the group consisting of Au, Ag, Al, Cu, Ti, TiN, and Pt. In this embodiment, the first electrode 70 and the second electrode 80 are formed of a material containing Au. In other words, the first electrode 70 and the second electrode 80 are formed of the same material as the antenna 60. As such, in this embodiment, the metal layer 30, the antenna 60, the first electrode 70, and the second electrode 80 are formed of the same material.

[0029] The first electrode 70 is connected to the first antenna portion 61. The first electrode 70 has a first electrode pad 71 and a first connection electrode 72 that connects the first electrode pad 71 and the first antenna portion 61. In this embodiment, the first electrode pad 71, the first connection electrode 72, and the first antenna portion 61 are integrally formed.

[0030] The second electrode 80 is connected to the second antenna portion 62. The second electrode 80 has a second electrode pad 81 and a second connection electrode 82 that connects the second electrode pad 81 and the second antenna portion 62. In this embodiment, the second electrode pad 81, the second connection electrode 82, and the second antenna portion 62 are integrally formed. Here, in this embodiment, the first electrode pad 71 and the second electrode pad 81 correspond to "electrode pads."

[0031] The first electrode pad 71 and the second electrode pad 81 are arranged at the same position in the y direction and spaced apart from each other in the x direction. When viewed from the z direction, each of the first electrode pad 71 and the second electrode pad 81 has a rectangular shape. In this embodiment, the first electrode pad 71 constitutes a main electrode, and the second electrode pad 81 constitutes a ground electrode.

[0032] Both the first connection electrode 72 and the second connection electrode 82 extend along the y direction. The first connection electrode 72 is connected in the x direction to a portion of the first antenna unit 61 that is closer to the second antenna unit 62 than the center of the first antenna unit 61 in the x direction. The second connection electrode 82 is connected in the x direction to a portion of the second antenna unit 62 that is closer to the first antenna unit 61 than the center of the second antenna unit 62 in the x direction.

[0033] In this embodiment, the first electrode pad 71, the first connection electrode 72, the second electrode pad 81, and the second connection electrode 82 are provided on the dielectric layer 40. In one example, the first electrode pad 71, the first connection electrode 72, the second electrode pad 81, and the second connection electrode 82 are formed on the surface 41 of the dielectric layer 40 by sputtering.

[0034] 2 , the terahertz device 10 includes a back-side metal layer 90 formed on the substrate back surface 22 of the semiconductor substrate 20. In this embodiment, the back-side metal layer 90 is formed over the entire substrate back surface 22. The back-side metal layer 90 is made of at least one metal material selected from the group consisting of Au, Ag, Al, Cu, Ti, TiN, and Pt. In this embodiment, the back-side metal layer 90 is made of a material containing Au. In other words, the back-side metal layer 90 is made of the same material as the antenna 60.

[0035] 3, the active element 50 is provided on the substrate surface 21 of the semiconductor substrate 20. The active element 50 is covered with the dielectric layer 40. As a result, it can be said that the active element 50 is provided within the dielectric layer 40.

[0036] As shown in FIG. 1 , the active element 50 is disposed at the center of the substrate surface 21 in the x and y directions. For example, the active element 50 is an element that exchanges electromagnetic waves of a predetermined frequency band with electrical energy, and therefore converts electrical energy supplied from the first electrode 70 and the second electrode 80 into electromagnetic waves of a predetermined frequency band. The electromagnetic waves from the active element 50 are radiated by the antenna 60. Therefore, the active element 50 can be referred to as an oscillation point P1 that oscillates electromagnetic waves, and the antenna 60 can be referred to as a radiation point P2 that radiates electromagnetic waves. In this embodiment, the radiation point P2 and the oscillation point P1 are located at the same position. Note that the position of the oscillation point P1 is not limited to the same position as the radiation point P2 and can be arbitrarily changed. Furthermore, the position of the oscillation point P1 can be located at any position on the substrate surface 21 when viewed from the z direction.

[0037] The active element 50 is, for example, a resonant tunneling diode (RTD). The active element 50 may also be, for example, a tunnel injection transit time (TUNNETT) diode, an impact ionization avalanche transit time (IMPATT) diode, a GaAs-based field effect transistor (FET), a GaN-based FET, a high electron mobility transistor (HEMT), or a heterojunction bipolar transistor (HBT).

[0038] A description will now be given of an example of a configuration for realizing the active element 50. As shown in Fig. 4, the active element 50 is provided between the first antenna portion 61 and the semiconductor substrate 20 in the z direction.

[0039] 4 and 5, a semiconductor layer 51a is provided on the substrate surface 21 of the semiconductor substrate 20. The semiconductor layer 51a has a rectangular shape when viewed from the z direction. The semiconductor layer 51a is made of, for example, GaInAs. The semiconductor layer 51a is heavily doped with n-type impurities.

[0040] 5, a GaInAs layer 52a is stacked on a semiconductor layer 51a. The GaInAs layer 52a is doped with n-type impurities. The n-type impurity concentration of the GaInAs layer 52a is lower than the n-type impurity concentration of the semiconductor layer 51a.

[0041] A GaInAs layer 53a is stacked on the GaInAs layer 52a. The GaInAs layer 53a is not doped with impurities. An AlAs layer 54a is stacked on the GaInAs layer 53a. An InGaAs layer 55 is stacked on the AlAs layer 54a. The InGaAs layer 55 is not doped with impurities. An AlAs layer 54b is stacked on the InGaAs layer 55. The AlAs layer 54a, the InGaAs layer 55, and the AlAs layer 54b form a resonant tunnel section.

[0042] An undoped GaInAs layer 53b is stacked on the AlAs layer 54b. An n-type impurity-doped GaInAs layer 52b is stacked on the GaInAs layer 53b. A highly doped GaInAs layer 51b is stacked on the GaInAs layer 52b. Therefore, the n-type impurity concentration of the GaInAs layer 51b is higher than that of the GaInAs layer 52b.

[0043] The specific configuration of the active element 50 can be changed as desired as long as it can generate (or detect, or both) electromagnetic waves. In other words, the active element 50 may be any element that can perform at least one of oscillation and detection of electromagnetic waves in the terahertz band.

[0044] 3, the first antenna unit 61 includes a first antenna body 61a provided on the dielectric layer 40 and a first connection portion 61b connected to the active element 50. The second antenna unit 62 includes a second antenna body 62a provided on the dielectric layer 40 and a second connection portion 62b connected to the semiconductor layer 51a.

[0045] 1, the first antenna body 61a and the second antenna body 62a are arranged at the same position in the y direction and spaced apart from each other in the x direction. The first antenna body 61a and the second antenna body 62a extend on opposite sides of each other in the x direction. Both the antenna body 61a and the second antenna body 62a extend along the x direction. The length of the antenna 60, i.e., the length in the x direction from the tip of the first antenna body 61a to the tip of the second antenna body 62a, is set to, for example, half the wavelength λ (λ / 2) of the electromagnetic waves oscillated by the active element 50.

[0046] 4 , the first connection portion 61b of the first antenna portion 61 is provided in a first opening 43 formed in the dielectric layer 40. The first opening 43 penetrates the dielectric layer 40 in the z direction. The first opening 43 and the first connection portion 61b are provided in a position overlapping with the active element 50 when viewed from the z direction. Therefore, it can be said that the active element 50 is provided in the first opening 43. The first connection portion 61b is located on the GaInAs layer 51b and is in contact with the GaInAs layer 51b.

[0047] The second connection portion 62b of the second antenna portion 62 is provided in a second opening 44 formed in the dielectric layer 40. The second opening 44 penetrates the dielectric layer 40 in the z direction. The second opening 44 and the second connection portion 62b are provided at a position different from the active element 50 in the x direction when viewed from the z direction. On the other hand, the second opening 44 and the second connection portion 62b are provided at the same position as the active element 50 in the y direction when viewed from the z direction. The second opening 44 and the second connection portion 62b are provided at a position overlapping with the semiconductor layer 51a when viewed from the z direction.

[0048] (Detailed Structure of the Metal Layer) As shown in FIG. 1 , the metal layer 30 is formed so as to avoid the semiconductor layer 51 a. That is, the metal layer 30 has a rectangular opening 33 that is slightly larger than the semiconductor layer 51 a when viewed from the z direction. As shown in FIG. 3 , the metal layer 30 is formed in a position facing both the first antenna main body 61 a and the second antenna main body 62 a in the z direction. When viewed from the z direction, the metal layer 30 is formed so as to overlap the entire first antenna main body 61 a. When viewed from the z direction, the metal layer 30 is formed so as to overlap the entire second antenna main body 62 a. In this embodiment, the metal layer 30 is formed over the entire substrate surface 21 of the semiconductor substrate 20 except for the opening 33.

[0049] 4, the thickness TM of the metal layer 30 is thinner than the thickness TB of the semiconductor substrate 20 (see FIG. 2). The thickness TM of the metal layer 30 is thinner than the thickness TD of the dielectric layer 40. The thickness TM of the metal layer 30 is thinner than the thickness TA of the antenna 60. The thickness TM of the metal layer 30 may be equal to the thickness TMB of the back-side metal layer 90 (see FIG. 2).

[0050] Here, the thickness TM of the metal layer 30 can be defined as the distance in the z direction between the front surface 31 and the back surface 32 of the metal layer 30. The thickness TD of the dielectric layer 40 can be defined as the distance in the z direction between the front surface 41 and the back surface 42 of the dielectric layer 40. The back surface 42 here is the surface that contacts the front surface 31 of the metal layer 30. The thickness TA of the antenna 60 refers to the thickness of the first antenna main body 61a, for example. Note that the thickness TB of the antenna 60 may refer to the thickness of the second antenna main body 62a.

[0051] The thickness TM of the metal layer 30 can be changed as desired. In one example, the thickness TM of the metal layer 30 may be equal to the thickness TA of the antenna 60, or may be thicker than the thickness TA of the antenna 60. In another example, the thickness TM of the metal layer 30 may be thicker than the thickness TMB of the back-side metal layer 90, or may be thinner than the thickness TMB of the back-side metal layer 90. However, from the viewpoint of manufacturing costs, it is preferable that the thickness TM of the metal layer 30 be as thin as possible within a range of thicknesses that can reflect electromagnetic waves.

[0052] 4, the metal layer 30 is formed to be spaced apart from the semiconductor layer 51a in a direction perpendicular to the z-direction. A dielectric layer 40 is interposed between the metal layer 30 and the semiconductor layer 51a. Furthermore, the metal layer 30 is electrically insulated from the active element 50, the first electrode 70, and the second electrode 80 by the dielectric layer 40. As such, in this embodiment, the metal layer 30 is in an electrically floating state.

[0053] (Operation) The operation of the terahertz device 10 of this embodiment will be described. FIGS. 6 and 7 are model diagrams of the terahertz devices used in the simulation, showing the side structure of each terahertz device. FIG. 6 shows the configuration of a terahertz device of a comparative example, and FIG. 7 shows the configuration of a terahertz device of an example. In FIGS. 6 and 7, to simplify the simulation, only an antenna is provided on the dielectric layer. Furthermore, in FIGS. 6 and 7, the antenna 60 is shown in a simplified form. The terahertz device of the comparative example in FIG. 6 differs from the terahertz device of the example in FIG. 7 in that it does not include a metal layer 30.

[0054] Fig. 8 and Fig. 9 are graphs showing the relationship between the frequency of the electromagnetic wave and the admittance in the terahertz device of the comparative example in Fig. 6 and the terahertz device of the example in Fig. 7. Fig. 8 shows the real part of the admittance, and Fig. 9 shows the imaginary part of the admittance. In Fig. 8 and Fig. 9, the solid line shows the simulation results of the example, and the dashed line shows the simulation results of the comparative example.

[0055] 8, in the terahertz device of the comparative example, resonance occurs at multiple frequencies, as indicated by the dashed lines, resulting in multiple peaks in the real part of the admittance, whereas in the terahertz device of the example, a peak in the real part of the admittance occurs at one frequency A1, as indicated by the solid line.

[0056] 9, in the terahertz device of the comparative example, resonance occurs at multiple frequencies, as indicated by the dashed lines, resulting in multiple peaks in the imaginary part of the admittance, whereas in the terahertz device of the example, a peak in the imaginary part of the admittance occurs at one frequency A2, as indicated by the solid line graph.

[0057] As described above, the terahertz device of the comparative example does not include the metal layer 30, and therefore, electromagnetic waves enter the semiconductor substrate 20, generating a substrate mode due to the propagation of electromagnetic waves in the semiconductor substrate 20. This results in the generation of electromagnetic waves of multiple frequencies. On the other hand, the terahertz device of the example uses the metal layer 30 to prevent electromagnetic waves from entering the semiconductor substrate 20, and therefore can suppress the generation of a substrate mode due to the propagation of electromagnetic waves in the semiconductor substrate 20. Therefore, the generation of electromagnetic waves of multiple frequencies can be suppressed.

[0058] (Effects) The terahertz device 10 of this embodiment provides the following effects. (1-1) The terahertz device 10 includes a semiconductor substrate 20 having a substrate surface 21 and a substrate back surface 22 opposite the substrate surface 21, a metal layer 30 provided on at least a portion of the substrate surface 21, a dielectric layer 40 covering the substrate surface 21 together with the metal layer 30, an active element 50 provided in the dielectric layer 40 and configured to oscillate or detect electromagnetic waves, and an antenna 60 provided on the dielectric layer 40 and electrically connected to the active element 50 and configured to emit or receive electromagnetic waves. When viewed from a direction perpendicular to the substrate surface 21 (the z direction), the metal layer 30 is formed at a position on the substrate surface 21 that overlaps with at least the antenna 60. The metal layer 30 is in an electrically floating state.

[0059] According to this configuration, electromagnetic waves radiated from the antenna 60 toward the semiconductor substrate 20 are reflected by the metal layer 30 provided between the antenna 60 and the semiconductor substrate 20. In other words, the metal layer 30 prevents the electromagnetic waves from entering the semiconductor substrate 20. Therefore, it is possible to prevent the generation of a substrate mode due to the propagation of electromagnetic waves in the semiconductor substrate 20, and therefore it is possible to prevent the generation of electromagnetic waves with frequencies different from the desired electromagnetic waves.

[0060] In addition, because the metal layer 30 is in an electrically floating state, there is no need to provide a structure for electrically connecting the metal layer 30 to other components in the terahertz device 10. Therefore, the configuration of the terahertz device 10 can be simplified, and an increase in the size of the terahertz device 10 can be suppressed.

[0061] (1-2) The thickness TM of the metal layer 30 is thinner than the thickness TD of the dielectric layer 40. According to this configuration, the manufacturing cost of the terahertz device 10 can be reduced by forming the thickness TM of the metal layer 30 to be thin.

[0062] (1-3) The thickness TM of the metal layer 30 is thinner than the thickness TA of the antenna 60. According to this configuration, the manufacturing cost of the terahertz device 10 can be reduced by forming the thickness TM of the metal layer 30 to be thin.

[0063] (1-4) The metal layer 30 is formed over the entire substrate surface 21 of the semiconductor substrate 20. This configuration makes it even more difficult for electromagnetic waves radiated from the antenna 60 toward the semiconductor substrate 20 and electromagnetic waves incident from outside the terahertz device 10 to penetrate into the semiconductor substrate 20. Therefore, the occurrence of substrate modes in the semiconductor substrate 20 can be further suppressed.

[0064] Second Embodiment A terahertz device 10 according to a second embodiment will be described with reference to Figures 10 and 11. The terahertz device 10 according to this embodiment differs from the terahertz device 10 according to the first embodiment mainly in the configuration of the dielectric layer 40 and the configuration of the antenna 60. In the second embodiment, differences from the first embodiment will be described in detail, and components common to the first embodiment will be denoted by the same reference numerals and will not be described again.

[0065] 10 , the dielectric layer 40 of this embodiment has a laminated structure of a first dielectric layer 40A and a second dielectric layer 40B. The second dielectric layer 40B is laminated on the first dielectric layer 40A. The dielectric layer 40 may also include a third dielectric layer provided on the second dielectric layer 40B. In other words, the dielectric layer 40 of this embodiment may have any structure as long as it is composed of a laminated structure of multiple dielectric layers.

[0066] The first dielectric layer 40A is in contact with the substrate surface 21 of the semiconductor substrate 20. The first dielectric layer 40A covers the metal layer 30, the semiconductor layer 51a, and the active element 50. When viewed from the z direction, the first dielectric layer 40A is formed over the entire substrate surface 21. The first dielectric layer 40A is made of, for example, SiO ２ The material is formed from a material containing

[0067] The first dielectric layer 40A has a first opening 45 and a second opening 46 spaced apart from each other. Both the first opening 45 and the second opening 46 are positioned to overlap the semiconductor layer 51a when viewed from the z direction. The first opening 45 is positioned to overlap the active element 50 when viewed from the z direction. The second opening 46 is positioned at the same position as the first opening 45 in the y direction but spaced apart in the x direction.

[0068] The second dielectric layer 40B is in contact with the first dielectric layer 40A. When viewed from the z direction, the second dielectric layer 40B is formed over the entire first dielectric layer 40A. The second dielectric layer 40B is made of, for example, SiO ２ In the present embodiment, the first dielectric layer 40A and the second dielectric layer 40B are formed of the same material, but this is not limiting. The second dielectric layer 40B may be formed of a material different from that of the first dielectric layer 40A. In one example, the second dielectric layer 40B may be formed of a material including at least one of silicon nitride (SiN) and silicon oxynitride (SiON).

[0069] The second dielectric layer 40B has an opening 47 penetrating the second dielectric layer 40B in the z-direction. The opening 47 is connected to both the first opening 45 and the second opening 46 of the first dielectric layer 40A. That is, when viewed from the z-direction, the opening area of ​​the opening 47 is larger than the opening areas of the first opening 45 and the second opening 46. In this embodiment, the inner surface of the opening 47 extends along the z-direction. The opening 47 and the first dielectric layer 40A form a recess 40C. The surface of the first dielectric layer 40A forms the bottom surface of the recess 40C. The recess 40C opens to the front surface 41 of the dielectric layer 40 and is recessed from the front surface 41 toward the back surface 42. Here, the front surface of the first dielectric layer 40A is the surface of the first dielectric layer 40A facing the second dielectric layer 40B and in contact with the second dielectric layer 40B.

[0070] The first connection portion 61b of the first antenna portion 61 of the antenna 60 is provided within the first opening 45 and the opening 47. The first connection portion 61b contacts the active element 50, as in the first embodiment. When viewed from the z direction, the first opening 45 is located at the center of the opening 47 in the x direction. Therefore, when viewed from the z direction, the active element 50 is located at the center of the opening 47 in the x direction. The first connection portion 61b includes a first portion extending in the z direction along the inner surface of the opening 47, a second portion provided to fill the first opening 45, and a third portion connecting the first portion and the second portion. The end of the first portion opposite the third portion in the z direction is connected to the first antenna main body 61a. The end of the second portion opposite the third portion in the z direction is in contact with the active element 50. The third portion is provided on the first dielectric layer 40A. The third portion extends in the x direction, so that the first connection portion 61b is formed in a stepped shape.

[0071] The second connection portion 62b of the second antenna portion 62 is provided within the second opening 46 and the opening 47. The second connection portion 62b contacts the semiconductor layer 51a, as in the first embodiment. When viewed from the z direction, the second opening 46 is located closer to the device side surface 13 in the x direction within the opening 47. The second connection portion 62b includes a first portion extending in the z direction along the inner surface of the opening 47, a second portion provided to fill the second opening 46, and a step portion provided between the first and second portions. The ends of the first portion opposite the step portion in the z direction are connected to the second antenna main body portion 62a. The ends of the second portion opposite the step portion in the z direction are in contact with the semiconductor layer 51a. The step portion is provided on the first dielectric layer 40A.

[0072] The first antenna body 61a and the second antenna body 62a of the antenna 60 are formed on the second dielectric layer 40B. The distance between the first antenna body 61a and the second antenna body 62a in the x direction is greater than the distance between the first antenna body 61a and the second antenna body 62a in the x direction in the first embodiment.

[0073] The thickness TD2 of the second dielectric layer 40B is thicker than the thickness TD1 of the first dielectric layer 40A. The difference between the thickness TD2 and the thickness TD1 is about 100 times. In other words, the thickness TD2 is about 100 times thicker than the thickness TD1. In this embodiment, the thickness TD of the dielectric layer 40 is the sum of the thickness TD1 of the first dielectric layer 40A and the thickness TD2 of the second dielectric layer 40B.

[0074] Here, the thickness TD1 of the first dielectric layer 40A can be defined as the distance in the z direction between the front and back surfaces of the first dielectric layer 40A. The back surface of the first dielectric layer 40A is the surface of the first dielectric layer 40A that contacts the front surface 31 of the metal layer 30. The thickness TD2 of the second dielectric layer 40B can be defined as the distance in the z direction between the front and back surfaces of the second dielectric layer 40B. The front surface of the second dielectric layer 40B is the front surface 41 of the dielectric layer 40. The back surface of the second dielectric layer 40B is the surface of the second dielectric layer 40B that contacts the front surface of the first dielectric layer 40A.

[0075] Similar to the first embodiment, the thickness TD of the dielectric layer 40 is greater than the thickness TM of the metal layer 30. The thickness TD2 of the second dielectric layer 40B is greater than the thickness TM of the metal layer 30. The thickness TD1 of the first dielectric layer 40A is greater than the thickness TM of the metal layer 30.

[0076] The thickness TD of the dielectric layer 40 is greater than the thickness TA of the antenna 60. The thickness TD2 of the second dielectric layer 40B is greater than the thickness TA of the antenna 60. The thickness TD1 of the first dielectric layer 40A is greater than the thickness TA of the antenna 60.

[0077] The thickness TD of the dielectric layer 40 is greater than the thickness TMB of the back-side metal layer 90. The thickness TD2 of the second dielectric layer 40B is greater than the thickness TMB of the back-side metal layer 90. The thickness TD1 of the first dielectric layer 40A is greater than the thickness TMB of the back-side metal layer 90.

[0078] The thickness TD1 of the first dielectric layer 40A may be equal to the thickness TM of the metal layer 30, or may be thinner than the thickness TM of the metal layer 30. The thickness TD1 of the first dielectric layer 40A may be equal to the thickness TA of the antenna 60, or may be thinner than the thickness TA of the antenna 60. The thickness TD1 of the first dielectric layer 40A may be equal to the thickness TMB of the back-side metal layer 90, or may be thicker than the thickness TMB of the back-side metal layer 90.

[0079] Fig. 11 is a graph showing the relationship between the thickness TD of the dielectric layer 40 and the radiation efficiency of the electromagnetic waves. In the graph of Fig. 11, the frequency of the electromagnetic waves oscillated by the active element 50 is in the 300 GHz band.

[0080] Here, the wavelength λ of the electromagnetic wave is the effective wavelength in the dielectric layer 40, and λ = λ _０ × (1 / √ε _ｒ ) can be defined as λ _０ is the wavelength in free space, and ε _ｒ is the relative dielectric constant of the dielectric layer 40. Here, the free space is a space in which no dielectric exists, such as a vacuum. In this embodiment, the relative dielectric constant ε of the dielectric layer 40 is _ｒ When the frequency of the electromagnetic wave is in the 300 GHz band, the wavelength λ of the electromagnetic wave is _０is 1 mm. Therefore, the wavelength λ of the electromagnetic wave is about 542 μm.

[0081] As shown in Fig. 11, the electromagnetic wave radiation efficiency improves as the thickness TD of the dielectric layer 40 increases. When the electromagnetic wave radiation efficiency is to be close to 100%, the thickness TD of the dielectric layer 40 is preferably equal to or greater than ¼ of the wavelength λ of the electromagnetic wave. In other words, the thickness TD of the dielectric layer 40 is preferably equal to or greater than 136 µm. Furthermore, the thickness TD of the dielectric layer 40 is preferably equal to or greater than 1 / 10 of the wavelength λ of the electromagnetic wave. In other words, the thickness TD of the dielectric layer 40 is preferably equal to or greater than 54 µm.

[0082] The electromagnetic wave radiation efficiency may be 50% or more. In this embodiment, the electromagnetic wave radiation efficiency is 50% when the thickness TD of the dielectric layer 40 is about 40 μm. In other words, the thickness TD of the dielectric layer 40 is preferably 40 μm or more.

[0083] (Effects) According to the terahertz device 10 of this embodiment, the following effects can be obtained in addition to the effects of the first embodiment.

[0084] (2-1) The dielectric layer 40 has a laminated structure of multiple dielectric layers. The dielectric layer 40 includes a first dielectric layer 40A and a second dielectric layer 40B. This structure allows the thickness TD of the dielectric layer 40 to be easily adjusted.

[0085] (2-2) The thickness TD of the dielectric layer 40 is equal to or greater than 1 / 10 of the wavelength λ of the electromagnetic wave oscillated by the active element 50. With this configuration, the radiation efficiency of the electromagnetic wave is increased as shown in FIG. 11 , and the output of the electromagnetic wave radiated by the terahertz device 10 can be increased.

[0086] (2-3) The thickness TD of the dielectric layer 40 may be 40 μm or more. With this configuration, the radiation efficiency of the electromagnetic waves becomes 50% or more as shown in FIG. 11 , and the output of the electromagnetic waves radiated by the terahertz device 10 can be increased.

[0087] Third Embodiment A terahertz device 10 according to a third embodiment will be described with reference to Fig. 12. The terahertz device 10 according to this embodiment differs from the terahertz device 10 according to the first embodiment mainly in the configuration of the antenna 60. In the third embodiment, differences from the first embodiment will be described in detail, and components common to the first embodiment will be denoted by the same reference numerals, and their description may be omitted.

[0088] As shown in Figure 12, the antenna 60 forms a bowtie antenna. More specifically, the first antenna body 61a is tapered so that its width increases toward the device side surface 14. The tip surface of the first antenna body 61a is formed along the yz plane. The second antenna body 62a is tapered so that its width increases toward the device side surface 13. The tip surface of the second antenna body 62a is formed along the yz plane. Here, the tip surface of the first antenna body 61a is the end surface of the first antenna body 61a closer to the device side surface 14, and the tip surface of the second antenna body 62a is the end surface of the second antenna body 62a closer to the device side surface 13.

[0089] Of both ends in the x direction of the first antenna main body 61a, a first connecting portion 61b (not shown) is connected to the end closer to the second antenna main body 62a. Of both ends in the x direction of the second antenna main body 62a, a second connecting portion 62b (not shown) is connected to the end closer to the first antenna main body 61a. The configurations of the first connecting portion 61b and the second connecting portion 62b are the same as in the first embodiment, and therefore description thereof will be omitted.

[0090] Fourth Embodiment A terahertz device 10 according to a fourth embodiment will be described with reference to Fig. 13 and Fig. 14. The terahertz device 10 according to this embodiment differs from the terahertz device 10 according to the second embodiment mainly in the configuration of the antenna 60. In the fourth embodiment, differences from the second embodiment will be described in detail, and components common to the second embodiment will be denoted by the same reference numerals and will not be described again.

[0091] 13 , the antenna 60 forms a loop antenna. More specifically, the antenna 60 has a ring-shaped portion 63. When viewed from the z direction, the ring-shaped portion 63 is formed in an annular shape with a gap at the end closer to the device side surface 16. In other words, the ring-shaped portion 63 includes a first end 63 a and a second end 63 b.

[0092] The ring-shaped portion 63 has overlapping portions when viewed from the z direction. More specifically, the ring-shaped portion 63 includes a first portion 63A and a second portion 63B formed in an arc shape. The first portion 63A includes a first end portion 63a, and the second portion 63B includes a second end portion 63b. The first portion 63A includes a first overlapping portion 63Aa, and the second portion 63B includes a second overlapping portion 63Ba. The first overlapping portion 63Aa is one of both end portions of the first portion 63A opposite the first end portion 63a. The second overlapping portion 63Ba is one of both end portions of the second portion 63B opposite the second end portion 63b.

[0093] Although not shown, the first end 63a is connected to the first connection portion 61b. The first end 63a is also connected to the first connection electrode 72 of the first electrode 70. In other words, the first portion 63A of the ring-shaped portion 63 is connected to the first connection electrode 72.

[0094] Although not shown, the second end 63b is connected to the second connection portion 62b. The second end 63b is also connected to the second connection electrode 82 of the second electrode 80. In other words, the second portion 63B of the ring-shaped portion 63 is connected to the second connection electrode 82.

[0095] The terahertz device 10 further includes an MIM (Metal-Insulator-Metal) capacitor 65. The MIM capacitor 65 is formed at a position spaced apart in the y direction from the active element 50 when viewed from the z direction. The MIM capacitor 65 is disposed closer to the device side surface 15 than the active element 50 when viewed from the z direction.

[0096] FIG. 14 shows the cross-sectional structure of the MIM capacitor 65. As shown in FIG. 14, the MIM capacitor 65 is formed by a first portion 63A and a second portion 63B of the ring-shaped portion 63. More specifically, the MIM capacitor 65 includes a first overlapping portion 63Aa of the first portion 63A and a second overlapping portion 63Ba of the second portion 63B. The first overlapping portion 63Aa and the second overlapping portion 63Ba are disposed opposite each other in the z direction. A dielectric layer 66 is interposed between the first overlapping portion 63Aa and the second overlapping portion 63Ba in the z direction. Thus, the MIM capacitor 65 includes the first overlapping portion 63Aa, the second overlapping portion 63Ba, and the dielectric layer 66.

[0097] The first overlapping portion 63Aa is provided on the dielectric layer 66. The first portion 63A has a portion that extends continuously from the first overlapping portion 63Aa along the side surface of the dielectric layer 66. The first overlapping portion 63Aa constitutes a first electrode of the MIM capacitor 65.

[0098] The second overlapping portion 63Ba is interposed between the dielectric layer 40 and the dielectric layer 66. The second overlapping portion 63Ba constitutes a second electrode of the MIM capacitor 65. The dielectric layer 66 is in contact with both the first overlapping portion 63Aa and the second overlapping portion 63Ba. The dielectric layer 66 is made of, for example, SiO ２ The dielectric layer 66 may be formed of a material containing at least one of SiN and SiON. Note that the dielectric layer 66 may be formed of a material different from that of the dielectric layer 40. In one example, the dielectric layer 66 may be formed of a material containing at least one of SiN and SiON.

[0099] Fifth Embodiment A terahertz device 10 according to a fifth embodiment will be described with reference to Figures 15 to 17. The terahertz device 10 according to this embodiment differs from the terahertz device 10 according to the second embodiment mainly in the configurations of the antenna 60, the first electrode 70, and the second electrode 80. In the fifth embodiment, differences from the second embodiment will be described in detail, and components common to the second embodiment will be denoted by the same reference numerals and will not be described again.

[0100] As shown in FIG. 15 , the antenna 60 forms a slot antenna. The antenna 60 is composed of a first electrode 70 and a second electrode 80. The first electrode 70 and the second electrode 80 form a slot 64. More specifically, the first electrode pad 71 of the first electrode 70 is disposed closer to the device side surface 14 than the center in the x direction of the substrate surface 21 of the semiconductor substrate 20. The first electrode pad 71 is formed in the y direction over the entire y-direction length of the substrate surface 21. The first electrode pad 71 is formed in the x direction so as to be slightly smaller than half the x-direction length of the substrate surface 21. The second electrode pad 81 of the second electrode 80 is disposed closer to the device side surface 13 than the center in the x direction of the substrate surface 21 of the semiconductor substrate 20. The second electrode pad 81 is formed in the y direction over the entire y-direction length of the substrate surface 21. The second electrode pad 81 is formed in the x direction so as to be slightly smaller than half the x-direction length of the substrate surface 21. These electrode pads 71 ​​and 81 form a slot 64 , which is a gap between the first electrode pad 71 and the second electrode pad 81 , at the center of the substrate surface 21 in the x direction.

[0101] When viewed from the z direction, the first connection electrode 72 extends from the center position of the first electrode 70 in the y direction toward the second electrode 80. When viewed from the z direction, the first connection electrode 72 extends along the x direction.

[0102] 16 , unlike the second embodiment, the first connection electrode 72 of the first electrode 70 is connected to the active element 50. The first connection electrode 72 includes a first portion extending in the x-direction on the second dielectric layer 40B, a second portion extending in the z-direction along the inner surface that forms the opening 47 of the second dielectric layer 40B, a third portion extending in the x-direction on the first dielectric layer 40A, and a fourth portion provided so as to fill the first opening 45 of the first dielectric layer 40A. As shown in FIG. 16 , the first connection electrode 72 is formed in a stepped shape.

[0103] 15 , the second connection electrode 82 extends from the center of the second electrode 80 in the y direction toward the first electrode 70 when viewed from the z direction. The second connection electrode 82 extends along the x direction when viewed from the z direction. The first connection electrode 72 and the second connection electrode 82 are arranged at the same positions in the y direction and spaced apart from each other in the x direction.

[0104] 16 , the second connection electrode 82 of the second electrode 80 is connected to the semiconductor layer 51 a, unlike in the second embodiment. The second connection electrode 82 includes a first portion extending in the x direction on the second dielectric layer 40B, a second portion extending in the z direction along the inner side surface that forms the opening 47 of the second dielectric layer 40B, a third portion provided so as to fill the second opening 46 of the first dielectric layer 40A, and a step portion provided between the second and third portions.

[0105] 15 , the terahertz device 10 further includes a first MIM (Metal-Insulator-Metal) capacitor 100 and a second MIM capacitor 110. When viewed from the z direction, the first MIM capacitor 100 is provided at an end closer to the device side surface 15 and at the center in the x direction. When viewed from the z direction, the second MIM capacitor 110 is provided at an end closer to the device side surface 16 and at the center in the x direction.

[0106] Both the first MIM capacitor 100 and the second MIM capacitor 110 are composed of a first electrode 70 and a second electrode 80. The first electrode 70 includes a first opposing electrode 73 that constitutes the first MIM capacitor 100 and a first opposing electrode 74 that constitutes the second MIM capacitor 110. The second electrode 80 includes a second opposing electrode 83 that constitutes the first MIM capacitor 100 and a second opposing electrode 84 that constitutes the second MIM capacitor 110. The first opposing electrode 73 is disposed opposite the second opposing electrode 83 in the z direction. The first opposing electrode 74 is disposed opposite the second opposing electrode 84 in the z direction.

[0107] 17 shows the cross-sectional structure of the second MIM capacitor 110. As shown in Fig. 17, a dielectric layer 120 is interposed between the first opposing electrode 74 and the second opposing electrode 84 in the z direction. In this manner, the second MIM capacitor 110 has the first opposing electrode 74, the second opposing electrode 84, and the dielectric layer 120.

[0108] The second opposing electrode 84 includes an opposing electrode portion 84a provided on the dielectric layer 120 and a connection portion 84b that connects the opposing electrode portion 84a and the second electrode pad 81. The connection portion 84b extends along the side surface of the dielectric layer 120.

[0109] The first opposing electrode 74 is interposed between the dielectric layer 120 and the second dielectric layer 40B. The first opposing electrode 74 is provided at the same position in the z direction as the first electrode pad 71 (second electrode pad 81).

[0110] The dielectric layer 120 is in contact with both the opposing electrode portion 84a and the first opposing electrode 74. The dielectric layer 120 is also interposed between the first electrode pad 71 and the second opposing electrode 84 in the x direction. The dielectric layer 120 is made of, for example, SiO ２ The dielectric layer 120 may be formed of a material that includes at least one of SiN and SiON. Note that the dielectric layer 120 may be formed of a material that is different from the materials of the first dielectric layer 40A and the second dielectric layer 40B. In one example, the dielectric layer 120 may be formed of a material that includes at least one of SiN and SiON.

[0111] The first MIM capacitor 100 is configured such that the positional relationship in the z direction between the first opposing electrode 74 and the second opposing electrode 84 is opposite to the positional relationship in the z direction between the first opposing electrode 73 and the second opposing electrode 83. That is, the second opposing electrode 83 is interposed between the dielectric layer 120 and the second dielectric layer 40B. The first opposing electrode 73 includes an opposing electrode portion provided on the dielectric layer 120 and a connection portion that connects the opposing electrode portion to the first electrode pad 71. In this way, the first MIM capacitor 100, like the second MIM capacitor 110, has the first opposing electrode 73, the second opposing electrode 83, and the dielectric layer 120.

[0112] <Modifications> The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0113] In the first embodiment, the configurations of the antenna 60, the first electrode 70, and the second electrode 80 can be changed as desired. As an example, the configurations of the antenna 60, the first electrode 70, and the second electrode 80 may be the slot antenna configuration of the fifth embodiment.

[0114] In the second embodiment, the configuration of the antenna 60 can be changed as desired. For example, the antenna 60 may have the configuration of the bowtie antenna of the third embodiment. For another example, the antenna 60 may have the configuration of the loop antenna of the fourth embodiment.

[0115] In the second embodiment, the configurations of the first connecting portion 61b and the second connecting portion 62b of the antenna 60 can be changed as desired. By changing the shape of the opening 47 in the second dielectric layer 40B, the first connecting portion 61b and the second connecting portion 62b can be changed to the configurations shown in Figures 18 and 19, for example.

[0116] 18 , the opening 47 in the second dielectric layer 40B may be tapered so that the opening area decreases toward the first dielectric layer 40A. A first portion of the first connecting portion 61b provided on the inner surface of the opening 47 and a first portion of the second connecting portion 62b provided on the inner surface of the opening 47 are inclined toward each other toward the first dielectric layer 40A. In other words, both the first portion of the first connecting portion 61b and the first portion of the second connecting portion 62b extend along the inner surface of the opening 47. In this manner, the first connecting portion 61b and the second connecting portion 62b may be formed along the inner surface of the recess 40C of the dielectric layer 40.

[0117] 19 , the openings 47 in the second dielectric layer 40B include a first opening 47A and a second opening 47B. When viewed from the z direction, the first opening 47A is provided at a position different from the first opening 45 in the first dielectric layer 40A. When viewed from the z direction, the second opening 47B is provided at a position different from the second opening 46 in the first dielectric layer 40A.

[0118] The first connection portion 61b includes a first portion embedded in the first opening 47A, a second portion embedded in the first opening 45, and a third portion connecting the first and second portions. The third portion is provided on the first dielectric layer 40A. The first portion extends in the z-direction. The third portion extends in the x-direction.

[0119] The second connection portion 62b includes a first portion embedded in the second opening 47B, a second portion embedded in the second opening 46, and a step portion provided between the first and second portions. The step portion is provided on the first dielectric layer 40A. The first portion extends in the z-direction. In this manner, the first connection portion 61b and the second connection portion 62b may include a via provided in the dielectric layer 40.

[0120] In each of the above embodiments, the area where the metal layer 30 is formed on the substrate surface 21 of the semiconductor substrate 20 can be changed as desired. In one example, as shown in Fig. 20 , the metal layer 30 may be formed only at a position facing the antenna 60 in the z direction and in its periphery. For convenience, in Fig. 20 , the metal layer 30 is indicated by a dashed line surrounding the antenna 60.

[0121] A back-side metal layer 90 is formed on the back surface 22 of the substrate. With this configuration, the electromagnetic waves radiated from the antenna 60 are incident on an area of ​​the semiconductor substrate 20 other than the area where the metal layer 30 is formed. In this way, the electromagnetic waves incident on the semiconductor substrate 20 are reflected by the back-side metal layer 90 in a direction different from that of the antenna 60. Even in this way, the occurrence of a substrate mode in the semiconductor substrate 20 can be suppressed, and therefore the occurrence of electromagnetic waves of multiple frequencies can be suppressed.

[0122] In each of the above embodiments, the area where the dielectric layer 40 is formed on the substrate surface 21 of the semiconductor substrate 20 can be changed as desired. In one example, as shown in Figures 21 and 22, the dielectric layer 40 may be formed only in an area closer to the device side surface 15 than the first electrode pad 71 and the second electrode pad 81. In the example shown in Figure 21, the antenna 60, the first connection electrode 72, and the second connection electrode 82 are all positioned so as to overlap the dielectric layer 40 when viewed from the z direction.

[0123] FIG. 22 mainly shows the cross-sectional structure of the first electrode 70. The configuration of the second electrode 80 is the same as that of the first electrode 70, and therefore a detailed description thereof will be omitted. As shown in FIG. 22 , the first electrode pad 71 is formed on the substrate surface 21 at a position different from the dielectric layer 40. In the example of FIG. 22 , the first electrode pad 71 is in contact with the substrate surface 21. Meanwhile, the first connection electrode 72 includes a portion formed on the dielectric layer 40. More specifically, the first connection electrode 72 includes a first portion that is in contact with a side surface of the dielectric layer 40 and extends in the z-direction, and a second portion that is formed so as to be in contact with the surface 41 of the dielectric layer 40. The first portion connects the second portion to the first electrode pad 71.

[0124] The adhesion between the substrate surface 21 and the first electrode pad 71 is stronger than the adhesion between the surface 41 of the dielectric layer 40 and the first electrode pad 71. Therefore, by forming the first electrode pad 71 on the substrate surface 21, the first electrode pad 71 is less likely to peel off from the substrate surface 21. Therefore, for example, it is possible to prevent the first electrode pad 71 from peeling off from the substrate surface 21 due to a force applied to the first electrode pad 71 when cutting the first electrode 70 and the semiconductor substrate 20 with a dicing blade.

[0125] In the first to third embodiments, the terahertz device 10 may include an MIM capacitor 130. In one example, as shown in FIG. 23 , the first electrode 70 includes a first opposing electrode 74 and a connection portion 75. The first opposing electrode 74 is provided between the first connection electrode 72 and the first electrode pad 71 in the y direction. The first opposing electrode 74 is connected to the first connection electrode 72. Both the first opposing electrode 74 and the connection portion 75 are provided on the dielectric layer 40. That is, both the first opposing electrode 74 and the connection portion 75 are provided at the same position in the z direction as the first electrode pad 71 and the first connection electrode 72. When viewed from the z direction, the first opposing electrode 74 is formed in a rectangular shape. The connection portion 75 is provided between the first opposing electrode 74 and the first electrode pad 71 in the y direction so as to connect the first opposing electrode 74 and the first electrode pad 71.

[0126] The second electrode 80 includes a second opposing electrode 84, a first connection portion 85, and a second connection portion 86. The second opposing electrode 84 is disposed opposite the first opposing electrode 74 in the z direction while being spaced apart from the first opposing electrode 74. The second opposing electrode 84 is disposed on the opposite side of the dielectric layer 40 from the first opposing electrode 74. The second opposing electrode 84 is disposed at a position spaced apart from the dielectric layer 40 in the z direction. In other words, the second opposing electrode 84 is disposed at a different position in the z direction from the second electrode pad 81 and the second connection electrode 82. The first connection portion 85 is disposed between the second opposing electrode 84 and the second electrode pad 81 to connect the second opposing electrode 84 and the second electrode pad 81. The second connection portion 86 is disposed between the second opposing electrode 84 and the second connection electrode 82 to connect the second opposing electrode 84 and the second connection electrode 82.

[0127] Although not shown, a dielectric layer is interposed between the first opposing electrode 74 and the second opposing electrode 84. The dielectric layer is the same as, for example, the dielectric layer 120 of the fifth embodiment. In this way, the MIM capacitor 130 has the first opposing electrode 74, the second opposing electrode 84, and the dielectric layer.

[0128] In each of the above embodiments, the metal layer 30 may be located inward from the device side surfaces 13 to 16. In one example, the metal layer 30 is formed in a rectangular shape that is slightly smaller than the rectangular shape formed by the device side surfaces 13 to 16 when viewed from the z direction.

[0129] According to this configuration, for example, in the process of cutting the semiconductor substrate with a dicing blade to separate the terahertz devices 10, the metal layer 30 is not cut. As a result, no force is applied directly from the dicing blade to the metal layer 30 in this process, and therefore the metal layer 30 is less likely to peel off from the substrate surface 21.

[0130] The configuration of the dielectric layer 40 in the second embodiment may be applied to the third embodiment. The configuration of the dielectric layer 40 in the first embodiment may be applied to the fourth and fifth embodiments.

[0131] <Application Examples of Terahertz Device> The terahertz device 10 of each of the above-described embodiments and modified examples can be applied to the terahertz units 200, 300, and 400 of the following first to third application examples.

[0132] 24, the terahertz unit 200 includes the terahertz device 10, a dielectric 210, an antenna base 220, a reflective film 230 as a reflective portion, and a gas space 240. The gas in the gas space 240 is, for example, air.

[0133] The dielectric 210 is made of a dielectric material that transmits electromagnetic waves generated by the terahertz device 10. In the first application example, the dielectric 210 is made of a resin material. An example of the resin material is epoxy resin (e.g., glass epoxy resin). The dielectric 210 has insulating properties. The dielectric refractive index n2, which is the refractive index (absolute refractive index) of the dielectric 210, is lower than the element refractive index n1, which is the refractive index of the terahertz device 10. The element refractive index n1 is higher than the gas refractive index n3, which is the refractive index of the gas in the gas space 240. The dielectric refractive index n2 is higher than the gas refractive index n3. For example, the dielectric refractive index n2 is 1.55, and the element refractive index n1 is 3.4. The element refractive index n1 is the refractive index of the semiconductor substrate 20. In the first application example, the semiconductor substrate 20 is made of a material containing InP.

[0134] The dielectric 210 surrounds the terahertz device 10. In the first application example, the dielectric 210 surrounds the entire terahertz device 10. It can also be said that the dielectric 210 seals the terahertz device 10. The dielectric 210 is formed in the shape of, for example, a rectangular plate.

[0135] The antenna base 220 has a rectangular parallelepiped shape as a whole. The antenna base 220 is formed, for example, from an insulating material. In one example, the antenna base 220 is made of a dielectric material, for example, a synthetic resin such as epoxy resin. The material forming the antenna base 220 is arbitrary, and may be, for example, silicon or glass.

[0136] A dielectric 210 is laminated on a base surface 221 of the antenna base 220. The dielectric 210 is formed so as to protrude from the antenna base 220 when viewed from the z direction. The antenna base 220 has an antenna recess 222 recessed from the base surface 221. The antenna recess 222 is recessed in a direction away from the base surface 221 and away from the dielectric 210. In the first application example, the antenna recess 222 is formed in a hemispherical shape as a whole. The antenna recess 222 opens toward the dielectric 210. The opening of the antenna recess 222 is circular when viewed from the z direction.

[0137] The antenna recess 222 has an antenna surface 223 that faces the terahertz device 10 across the dielectric 210 and the gas space 240. The antenna surface 223 is the inner surface of the antenna recess 222. The antenna surface 223 is formed to correspond to the shape of the antenna. In one example, the antenna surface 223 is curved so as to be concave in a direction away from the terahertz device 10. The antenna surface 223 is curved, for example, in a cone shape. In one example, the antenna surface 223 is curved so as to have a parabolic antenna shape.

[0138] The reflective film 230 reflects the electromagnetic waves emitted from the terahertz device 10 in one direction. The reflective film 230 is formed on the antenna surface 223. Therefore, the reflective film 230 has an antenna shape. In the first application example, the reflective film 230 is a parabolic mirror of revolution. The reflective film 230 is formed of a material that reflects the electromagnetic waves emitted from the terahertz device 10, and is formed of, for example, a metal such as Cu or an alloy. The reflective film 230 may have a single-layer structure or a multi-layer structure. The electromagnetic waves emitted from the terahertz device 10 are reflected upward by the reflective film 230. Therefore, the terahertz unit 200 is configured to emit electromagnetic waves upward.

[0139] The terahertz unit 200 includes external electrodes 251 and 252 used for electrical connection to the outside, and conductive portions 261 and 262 electrically connected to the terahertz device 10. The external electrodes 251 and 252 and the conductive portions 261 and 262 are each provided on the dielectric 210. The external electrodes 251 and 252 are provided so as to be exposed from the dielectric 210. The conductive portions 261 and 262 are provided within the dielectric 210.

[0140] The external electrodes 251 and 252 are arranged at positions that do not overlap the reflective film 230 when viewed from the z direction. Specifically, the external electrodes 251 and 252 are provided on a portion of the dielectric 210 that protrudes from the antenna base 220.

[0141] The conductive portions 261 and 262 connect the external electrodes 251 and 252 to the terahertz device 10. More specifically, the conductive portion 261 electrically connects the external electrode 251 to the first electrode 70 of the terahertz device 10. The conductive portion 262 electrically connects the external electrode 252 to the second electrode 80 of the terahertz device 10.

[0142] The terahertz device 10 is flip-chip mounted on the conductive portions 261 and 262. Specifically, the conductive portion 261 is connected to the first electrode pad 71 via a bump 271. The conductive portion 262 is connected to the second electrode pad 81 via a bump 272. The bumps 271 and 272 are configured with a layered structure of, for example, a metal layer containing Cu, a metal layer containing Ti, and a metal layer containing tin (Sn). Note that the bumps 271 and 272 may also have a single-layer structure.

[0143] Second Application Example As shown in FIG. 25, a terahertz unit 300 includes the terahertz device 10 , a support substrate 310 , and a waveguide 320 .

[0144] The support substrate 310 is formed in the shape of a rectangular plate. The support substrate 310 is made of an insulating material. An example of the insulating material is epoxy resin. The support substrate 310 has a substrate front surface 311 and a substrate back surface 312 opposite to the substrate front surface 311. Here, the substrate front surface 311 corresponds to the "support substrate front surface."

[0145] Two power supply lines 313 are formed on the substrate surface 311. Two external electrodes 314 are provided on the substrate back surface 312. Two connection conductors 315 are provided within the support substrate 310, respectively connecting the two power supply lines 313 and the two external electrodes 314. The terahertz device 10 is mounted on the substrate surface 311. The first electrode pad 71 of the first electrode 70 and the second electrode pad 81 of the second electrode 80 of the terahertz device 10 are individually electrically connected to the two power supply lines 313 by wires W.

[0146] The waveguide 320 is a hollow metal tube that transmits electromagnetic waves. The waveguide 320 is formed of a material that is opaque to the electromagnetic waves emitted or detected by the terahertz device 10. Metallic materials such as Cu, Cu alloys, Al, and Al alloys are used as this material. The waveguide 320 is laminated on the substrate surface 311. The waveguide 320 includes a through-hole 321 that penetrates the waveguide 320 in the z-direction. The waveguide 320 is formed in a rectangular parallelepiped shape. The support substrate 310 covers one end of the through-hole 321 in the z-direction. The waveguide 320 houses the terahertz device 10. That is, the terahertz device 10 is disposed within the through-hole 321 when viewed from the z-direction. The through-hole 321 functions as a transmission region 322 that transmits electromagnetic waves. The transmission region 322 is defined by the tapered surface of the through-hole 321. It can also be said that the terahertz device 10 is disposed within the transmission region 322 .

[0147] The shape of the through hole 321 when viewed from the z direction is circular. The through hole 321 is formed in a tapered shape that increases in diameter as it moves away from the support substrate 310 in the z direction. In other words, the through hole 321 is formed in a tapered shape that increases in diameter as it moves away from the terahertz device 10 in the z direction. The shape of the through hole 321 can be changed as desired. In one example, the shape of the through hole 321 when viewed from the z direction may be a polygon such as a rectangle.

[0148] 26, a terahertz unit 400 includes two terahertz devices 10 and an insulating substrate 410 that supports the terahertz devices 10. The insulating substrate 410 is made of AlN, SiC, alumina (Al ２ O ３ ), Si, and SiO ２ The insulating substrate 410 is made of at least one material selected from the group consisting of the following: The insulating substrate 410 has higher rigidity than the semiconductor substrate 20. For example, the thickness of the insulating substrate 410 is greater than the thickness of the semiconductor substrate 20.

[0149] The two terahertz devices 10 include a terahertz device 10 that emits electromagnetic waves and a terahertz device 10 that detects electromagnetic waves. The two terahertz devices 10 are arranged side by side and spaced apart from each other on an insulating substrate 410. Hereinafter, of the two terahertz devices 10, the terahertz device that emits electromagnetic waves will be referred to as a first terahertz device 10A, and the terahertz device that detects electromagnetic waves will be referred to as a second terahertz device 10B.

[0150] The first terahertz device 10A includes a first semiconductor substrate 20A, a first metal layer, a first dielectric layer, a first active element, a first antenna, a first electrode 70, and a second electrode 80. The first semiconductor substrate 20A, the first metal layer, the first dielectric layer, the first active element, the first antenna, the first electrode 70, and the second electrode 80 have the same configurations as the semiconductor substrate 20, the metal layer 30, the dielectric layer 40, the active element 50, the antenna 60, the first electrode 70, and the second electrode 80 in each of the above-described embodiments. For this reason, in FIG. 26 , the first dielectric layer, the first active element, and the first antenna are assigned the same reference numerals as the dielectric layer 40, the active element 50, and the antenna 60.

[0151] The first semiconductor substrate 20A has a first substrate surface and a first substrate back surface opposite to the first substrate surface. A first metal layer is formed on the first substrate surface. A first dielectric layer is formed to cover the first substrate surface together with the first metal layer. The first active element is an element that oscillates electromagnetic waves. The first antenna is configured to radiate electromagnetic waves. The first metal layer is formed on the first substrate surface at a position that overlaps with at least the first antenna when viewed from the z direction. The first metal layer is in an electrically floating state.

[0152] The second terahertz device 10B includes a second semiconductor substrate 20B, a second metal layer, a second dielectric layer, a second active element, a second antenna, a first electrode 70, and a second electrode 80. The second semiconductor substrate 20B, the second metal layer, the second dielectric layer, the second active element, the second antenna, the first electrode 70, and the second electrode 80 have the same configurations as the semiconductor substrate 20, the metal layer 30, the dielectric layer 40, the active element 50, the antenna 60, the first electrode 70, and the second electrode 80 in each of the above-described embodiments. For this reason, in FIG. 26 , the second dielectric layer, the second active element, and the second antenna are assigned the same reference numerals as the dielectric layer 40, the active element 50, and the antenna 60.

[0153] The second semiconductor substrate 20B has a second substrate surface and a second substrate back surface opposite the second substrate surface. A second metal layer is formed on the second substrate surface. A second dielectric layer is formed to cover the second substrate surface together with the second metal layer. The second active element is an element that detects electromagnetic waves. The second antenna is configured to receive electromagnetic waves. The second metal layer is formed on the second substrate surface at a position that overlaps with at least the second antenna when viewed from the z direction. The second metal layer is in an electrically floating state.

[0154] Furthermore, the terahertz unit 400 may include three or more terahertz devices 10. That is, the terahertz unit 400 includes a plurality of terahertz devices 10. All of the plurality of terahertz devices 10 may be configured to emit electromagnetic waves. All of the plurality of terahertz devices 10 may be configured to detect electromagnetic waves. Furthermore, among the plurality of terahertz devices 10, the number of first terahertz devices 10A and the number of second terahertz devices 10B may be different from each other.

[0155] As used herein, "at least one of A and B" should be understood to mean "A only, or B only, or both A and B." The term "on" as used in this disclosure includes the meanings "on" and "above," unless the context clearly indicates otherwise. Thus, the expression "a first layer is formed on a second layer" is intended to mean that in some embodiments, the first layer may be placed directly on the second layer in contact with the second layer, while in other embodiments, the first layer may be placed above the second layer without contacting the second layer. In other words, the term "on" does not exclude a structure in which another layer is formed between the first and second layers.

[0156] Directional terms such as "vertical," "horizontal," "upper," "lower," "top," "bottom," "forward," "rearward," "sideways," "left," "right," "front," "rear," etc., used in this disclosure depend on the particular orientation of the device being described and illustrated. Various alternative orientations are contemplated in this disclosure, and therefore these directional terms should not be construed narrowly.

[0157] <Supplementary Notes> The technical ideas that can be understood from the above-described embodiment and each modified example are described below. Note that, for the purpose of aiding understanding and not intending to limit the scope of the invention, the corresponding reference numerals in the embodiment are shown in parentheses for the configurations described in the Supplementary Notes. The reference numerals are shown as examples to aid understanding, and the components described with each reference numeral should not be limited to the components indicated by the reference numerals.

[0158] (Supplementary Note 1) A terahertz device (10) comprising: a semiconductor substrate (20) having a substrate surface (21) and a substrate back surface (22) opposite to the substrate surface (21); a metal layer (30) provided on at least a portion of the substrate surface (21); a dielectric layer (40) covering the substrate surface (21) together with the metal layer (30); an active element (50) provided in the dielectric layer (40) and configured to oscillate or detect electromagnetic waves; and an antenna (60) provided on the dielectric layer (40), electrically connected to the active element (50), and configured to radiate or receive the electromagnetic waves, wherein the metal layer (30) is formed at a position on the substrate surface (21) that overlaps with at least the antenna (60) when viewed from a direction perpendicular to the substrate surface (21) (z direction), and the metal layer (30) is in an electrically floating state.

[0159] (Supplementary Note 2) The terahertz device according to Supplementary Note 1, wherein the thickness (TM) of the metal layer (30) is smaller than the thickness (TD) of the dielectric layer (40).

[0160] (Supplementary Note 3) The terahertz device according to Supplementary Note 1 or 2, wherein the thickness (TM) of the metal layer (30) is smaller than the thickness (TA) of the antenna (60).

[0161] (Supplementary Note 4) The terahertz device according to any one of Supplementary Notes 1 to 3, wherein the metal layer (30) is formed over the entire surface of the substrate (21).

[0162] (Supplementary Note 5) The terahertz device according to any one of Supplementary Notes 1 to 4, wherein the thickness (TD) of the dielectric layer (40) is equal to or greater than 1 / 10 of the effective wavelength (λ) of the electromagnetic wave.

[0163] (Supplementary Note 6) The terahertz device according to Supplementary Note 5, wherein the dielectric layer (40) has a laminated structure of a plurality of dielectric layers (40A, 40B).

[0164] (Supplementary Note 7) The terahertz device according to any one of Supplementary Notes 1 to 6, further comprising a backside metal layer (90) provided on the backside of the substrate (22).

[0165] (Supplementary Note 8) The terahertz device according to any one of Supplementary Notes 1 to 7, wherein the antenna (60) includes a first antenna body (61a) and a second antenna body (62a) provided on the dielectric layer (40), a first connection portion (61b) connected to the first antenna body (61a), and a second connection portion (62b) connected to the second antenna body (62a), wherein a recess (40C) is provided in the dielectric layer (40) at a position overlapping with the active element (50) when viewed from a direction perpendicular to the substrate surface (21) (z direction), and the first connection portion (61b) and the second connection portion (62b) are provided along an inner surface constituting the recess (40C) and are configured in a tapered shape.

[0166] (Supplementary Note 9) The terahertz device according to any one of Supplementary Notes 1 to 7, wherein the antenna (60) includes a first antenna body (61a) and a second antenna body (62a) provided on the dielectric layer (40), a first connection portion (61b) connected to the first antenna body (61a), and a second connection portion (62b) connected to the second antenna body (62a), and both the first connection portion (61b) and the second connection portion (62b) include vias provided in the dielectric layer (40).

[0167] (Supplementary Note 10) The terahertz device according to any one of Supplementary Notes 1 to 9, further comprising electrode pads (71, 81) electrically connected to the active element (50), the electrode pads (71, 81) being formed on the substrate surface (21).

[0168] (Supplementary Note 11) The terahertz device according to any one of Supplementary Notes 1 to 10, wherein the metal layer (30) contains at least one of Au, Al, Cu, Ti, and Pt.

[0169] (Supplementary Note 12) The terahertz device according to any one of Supplementary Notes 1 to 11, wherein the antenna (60) is configured by any one of a dipole antenna, a bowtie antenna, a loop antenna, and a slot antenna.

[0170] (Supplementary Note 13) The terahertz device according to any one of Supplementary Notes 1 to 12, comprising a first electrode (70) and a second electrode (80) electrically connected to the active element (50), wherein the first electrode (70) and the second electrode (80) include a first opposing electrode (74) and a second opposing electrode (84) arranged opposite each other so as to form a capacitor (130) electrically connected to the active element (50).

[0171] (Supplementary Note 14) A terahertz unit (200) comprising: a terahertz device (10) according to any one of Supplementary Notes 1 to 13; a dielectric (210) formed of a dielectric material and surrounding the terahertz device (10); a gas space (240) in which a gas is present; and a reflecting section (230) having a portion facing the terahertz device (10) across the dielectric (210) and the gas space (240), and configured to reflect the electromagnetic wave generated from the active element (50) and propagated through the dielectric (210) and the gas space (240) in one direction.

[0172] (Supplementary Note 15) A terahertz unit (300) comprising: a support substrate (310) having a support substrate surface (311); a waveguide (320) laminated on the support substrate surface (311) and having a transmission region (322) for transmitting the electromagnetic wave; and a terahertz device (10) according to any one of Supplementary Notes 1 to 13 mounted on the support substrate surface (311) within the transmission region (322).

[0173] (Supplementary Note 16) A terahertz unit (400) comprising: a terahertz device (10) according to any one of Supplementary Notes 1 to 13; and a support substrate (410) supporting the terahertz device (10), wherein a plurality of the terahertz devices (10) are provided, one of the plurality of terahertz devices (10) being a first terahertz device (10A) configured with the active element (50) to emit electromagnetic waves, and another of the plurality of terahertz devices (10) being a second terahertz device (10B) configured with the active element (50) to detect electromagnetic waves.

[0174] (Supplementary Note 17) A terahertz device (10), comprising: a dielectric (210) formed of a dielectric material and surrounding the terahertz device (10); a gas space (240) in which a gas is present; and a reflecting section (230) having a portion facing the terahertz device (10) through the dielectric (210) and the gas space (240), and configured to reflect, in one direction, the electromagnetic wave generated from the active element (50) and propagated through the dielectric (210) and the gas space (240), wherein the terahertz device (10) comprises: a semiconductor substrate (20) having a substrate surface (21) and a substrate back surface (22) opposite to the substrate surface (21); a metal layer (30) provided on at least a portion of the substrate surface (21); and a dielectric layer (40) covering the substrate surface (21) together with the metal layer (30); a terahertz unit (200) comprising: an active element (50) provided in the dielectric layer (40) for oscillating or detecting electromagnetic waves; and an antenna (60) provided on the dielectric layer (40), electrically connected to the active element (50), and configured to radiate or receive the electromagnetic waves; the metal layer (30) is formed at a position on the substrate surface (21) that overlaps with at least the antenna (60) when viewed from a direction perpendicular to the substrate surface (21) (z direction); and the metal layer (30) is in an electrically floating state.

[0175] (Supplementary Note 18) A terahertz device (10) comprising: a support substrate (310) having a support substrate surface (311); a waveguide (320) laminated on the support substrate surface (311) and having a transmission region (322) for transmitting the electromagnetic wave; and a terahertz device (10) mounted on the support substrate surface (311) within the transmission region (322), wherein the terahertz device (10) comprises: a semiconductor substrate (20) having a substrate surface (21) and a substrate back surface (22) opposite to the substrate surface (21); a metal layer (30) provided on at least a portion of the substrate surface (21); a dielectric layer (40) covering the substrate surface (21) together with the metal layer (30); and an active element (50) provided in the dielectric layer (40) and configured to oscillate or detect an electromagnetic wave. an antenna (60) provided on the dielectric layer (40), electrically connected to the active element (50), and configured to radiate or receive the electromagnetic waves, wherein the metal layer (30) is formed at a position on the substrate surface (21) that overlaps with at least the antenna (60) when viewed from a direction perpendicular to the substrate surface (21) (z direction), and the metal layer (30) is in an electrically floating state.

[0176] (Supplementary Note 19) A terahertz device comprising: a first terahertz device (10A) and a second terahertz device (10B); and a support substrate (410) supporting the first terahertz device (10A) and the second terahertz device (10B), wherein the first terahertz device (10A) comprises: a first semiconductor substrate (20A) having a first substrate front surface (21) and a first substrate back surface (22) opposite to the first substrate front surface (21); a first metal layer (30) provided on at least a portion of the first substrate front surface (21); a first dielectric layer (40) covering the first substrate front surface (21) together with the first metal layer (30); and a first active element (50) provided in the first dielectric layer (40) and configured to oscillate an electromagnetic wave; and a first antenna (60) provided on the first dielectric layer (40), electrically connected to the first active element (50), and configured to radiate or receive the electromagnetic waves, wherein the first metal layer (30) is formed at a position on the first substrate surface (21) that overlaps with at least the first antenna (60) when viewed from a direction perpendicular to the first substrate surface (21) (z direction), and the first metal layer (30) is in an electrically floating state, and the second terahertz device (10B) includes: a second semiconductor substrate (20B) having a second substrate surface (21) and a second substrate back surface (22) opposite to the second substrate surface (21), a second metal layer (30) provided on at least a portion of the second substrate surface (21), and a second dielectric layer (40) that covers the second substrate surface (21) together with the second metal layer (30), a second active element (50) provided in the second dielectric layer (40) and configured to detect electromagnetic waves; and a second antenna (60) provided on the second dielectric layer (40), electrically connected to the second active element (50), and configured to radiate or receive the electromagnetic waves, wherein the second metal layer (30) is formed at a position on the second substrate surface (21) that overlaps with at least the second antenna (60) when viewed from a direction perpendicular to the second substrate surface (21) (z direction), and the second metal layer (30) is in an electrically floating state.

[0177] The above description is merely illustrative. Those skilled in the art will recognize that many more possible combinations and permutations are possible other than the components and methods (manufacturing processes) listed for the purpose of illustrating the technology of the present disclosure. The present disclosure is intended to embrace all alternatives, modifications, and variations that fall within the scope of the present disclosure, including the claims.

[0178] DESCRIPTION OF SYMBOLS 10... Terahertz device 10A... First terahertz device 10B... Second terahertz device 11... Device surface 12... Device back surface 13-16... Device side surfaces 20... Semiconductor substrate 20A... First semiconductor substrate 20B... Second semiconductor substrate 21... Substrate surface 22... Substrate back surface 30... Metal layer 31... Surface 32... Back surface 33... Opening 40... Dielectric layer 40A... First dielectric layer 40B... Second dielectric layer 40C... Recess 41... Surface 42... Back surface 43... First opening 44... Second opening 45... First opening 46... Second opening 47... Opening 47A... First opening 47B... Second opening 50... Active element 51a... Semiconductor layer 51b... GaInAs layer 52a... GaInAs layer 52b... GaInAs layer 53a...GaInAs layer 53b...GaInAs layer 54a...AlAs layer 54b...AlAs layer 55...InGaAs layer 60...Antenna 61...First antenna portion 61a...First antenna main body portion 61b...First connection portion 62...Second antenna portion 62a...Second antenna main body portion 62b...Second connection portion 63...Ring-shaped portion 63a...First end portion 63b...Second end portion 63A...First portion 63B...Second portion 63Aa...First overlapping portion 63Ba...Second overlapping portion 64...Slot 65...MIM capacitor 66...Dielectric layer 70...First electrode 71...First electrode pad 72...First connection electrode 73...First opposing electrode 74...First opposing electrode 75...Connection portion 80...Second electrode 81... Second electrode pad 82... Second connection electrode 83... Second opposing electrode 84... Second opposing electrode 84a... Opposing electrode portion 84b... Connection portion 85... First connection portion 86... Second connection portion 90... Back surface side metal layer 100... First MIM capacitor 110... Second MIM capacitor 120... Dielectric layer 130... MIM capacitor 200... Terahertz unit 210... Dielectric 220... Antenna base 221... Base surface 222... Antenna recess 223... Antenna surface 230... Reflecting film 240... Gas space 251, 252... External electrodes 261, 262... Conductive portion 271,272...Bump 300...Terahertz unit 310...Support substrate 311...Substrate surface 312...Substrate back surface 313...Power supply line 314...External electrode 315...Connecting conductor 320...Waveguide 321...Through hole 322...Transmission area 400...Terahertz unit 410...Insulating substrate W...Wire P1...Oscillation point P2...Radiation point TM...Thickness of metal layer TB...Thickness of semiconductor substrate TD...Thickness of dielectric layer TA...Thickness of antenna TMB...Thickness of back side metal layer TD1...Thickness of first dielectric layer TD2...Thickness of second dielectric layer

Claims

1. a semiconductor substrate having a substrate front surface and a substrate back surface opposite to the substrate front surface; a metal layer provided on at least a portion of the surface of the substrate; a dielectric layer covering the metal layer and the surface of the substrate; an active element disposed within the dielectric layer and configured to generate or detect electromagnetic waves; an antenna provided on the dielectric layer, electrically connected to the active element, and configured to radiate or receive the electromagnetic wave; the metal layer is formed at a position on the substrate surface that overlaps at least the antenna when viewed from a direction perpendicular to the substrate surface, The metal layer is in an electrically floating state. Terahertz device.

2. The thickness of the metal layer is less than the thickness of the dielectric layer. The terahertz device according to claim 1 .

3. The thickness of the metal layer is less than the thickness of the antenna. The terahertz device according to claim 1 .

4. The metal layer is formed over the entire surface of the substrate. The terahertz device according to claim 1 .

5. The thickness of the dielectric layer is equal to or greater than 1 / 10 of the effective wavelength of the electromagnetic wave. The terahertz device according to claim 1 .

6. The dielectric layer is formed of a laminated structure of a plurality of dielectric layers. The terahertz device according to claim 5 .

7. The substrate further includes a backside metal layer provided on the backside of the substrate. The terahertz device according to claim 1 .

8. The antenna is a first antenna body and a second antenna body provided on the dielectric layer; a first connection portion connected to the first antenna body; A second connection portion connected to the second antenna body; Including, a recess is provided in the dielectric layer at a position overlapping the active element when viewed from a direction perpendicular to the substrate surface; The first connection portion and the second connection portion are provided along the inner surface that constitutes the recess and are configured in a tapered shape. The terahertz device according to claim 1 .

9. The antenna is a first antenna body and a second antenna body provided on the dielectric layer; a first connection portion connected to the first antenna body; A second connection portion connected to the second antenna body; Including, Both the first connection portion and the second connection portion include a via provided in the dielectric layer. The terahertz device according to claim 1 .

10. further comprising an electrode pad electrically connected to the active element; The electrode pad is formed on the surface of the substrate. The terahertz device according to claim 1 .

11. The metal layer includes at least one of Au, Al, Cu, Ti, and Pt. The terahertz device according to claim 1 .

12. The antenna is one of a dipole antenna, a bowtie antenna, a loop antenna, and a slot antenna. The terahertz device according to any one of claims 1 to 11.