JP2009141661A - Electromagnetic wave detecting element and electromagnetic wave detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave detecting element and an electromagnetic wave detecting device, capable of efficiently detecting electromagnetic waves of terahertz band. <P>SOLUTION: A first antenna element-forming region 10 comprises a dielectric body, a metal layer 11 formed on its surface, a first antenna element group that are formed in array in the metal layer to receive electromagnetic waves in terahertz band, and a detection element which converts the received electric power at the first antenna element group into a detection voltage. A second antenna element-forming region 20 comprises a second antenna element group that are formed in an array, in the metal layer other than the first antenna element-forming region 10 so that the first antenna element group is substantially orthogonal to a polarized plane, for receiving the electromagnetic waves of terahertz band; and a detection element which converts the received electric power at the second antenna element group, formed around the central parts of antenna elements of the second antenna element group into a detection voltage. The metal layer comprises a groove, so formed as to output the detection voltage in the first antenna element-forming region 10 and the second antenna element-forming region 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave detection element and an electromagnetic wave detection device capable of detecting an electromagnetic wave in a terahertz region.

  The millimeter-wave / far-infrared frequency region (terahertz region) having a wavelength on the order of 10 mm to several thousandths of millimeters is expected to be applied to remote sensing such as radio astronomy or global environment observation. In the ISS (International Space Station) project, which has become a hot topic recently, an experiment to observe the ozone layer with a sensor using a superconducting material is planned as one of the observations of the global environment. Thus, the frequency region of millimeter wave to far infrared light is one of the very attractive frequency regions in practical use. In order to build such a system, research and development of sensors in addition to oscillators and transmission lines are very important.

  As far-infrared light detectors, there are quantum detectors typified by Schottky diodes and thermal detectors. Unlike the quantum detector, the thermal detector has an advantage that the sensitivity is small in frequency dependence and easy to use. A bolometer, which is an example of a thermal detector, converts energy of infrared electromagnetic waves into heat, and detects a temperature change due to the thermal conversion as a resistance value change. This bolometer is widely used because it has a simple structure and is easy to manufacture, and can be detected at room temperature in a wide frequency band from the near infrared to the far infrared.

  When the bolometer is actually used as a far-infrared light detection element, it is necessary to provide an absorption film for infrared light on the surface of the bolometer in order to efficiently absorb heat. However, when the measurement wavelength is in the long-infrared long wavelength region of 20 μm or more, the thin absorption film cannot absorb far-infrared light, and it is necessary to increase the thickness of the absorption film. However, when the thickness of the absorber is increased, the heat capacity of the absorber increases, so that the input power to the bolometer is reduced and the response speed of the bolometer is also reduced. The present inventors have proposed a detection method using an antenna-coupled microbolometer in which an antenna is attached to a bolometer instead of an absorber (for example, Non-Patent Document 1).

  FIG. 10 is a diagram illustrating an example of an antenna-coupled microbolometer. An antenna-coupled microbolometer 100 in which a bolometer and a single slot antenna are coupled uses a slot antenna 104 as an antenna element coupled to the bolometer 102. The slot antenna 104 is formed by providing a rectangular slot in the metal layer 108 that is a metal layer laminated on the dielectric 106, and has directivity perpendicular to the dielectric. The bolometer 102 is disposed substantially at the center of the slot, which is the feeding point of the slot antenna 104, and by providing the metal layer 108 with thin slit-shaped grooves 110, the left and right metal surfaces are insulated, and a constant current to the bolometer 102 is obtained. And the detection voltage from the bolometer 102 can be taken out.

FIG. 11 is a schematic diagram showing the detection principle of the antenna-coupled microbolometer. The detection voltage ΔV _n in such an antenna-coupled microbolometer 100 can be expressed by the following equation. For example, when the far-infrared light as an electromagnetic wave is irradiated to the antenna coupling microbolometer 100 shown in FIG. 10, power of the electromagnetic waves of the slot antenna 104 has received is supplied to the bolometer 102, the resistance value R ₁₁ of the bolometer 102 is R ₁₁ to change to + ΔR _11. Further, the voltage _{V 1} of the bolometer 102 ends by applying current _{I B} is changed to _{V 1} + _{ΔV 1.} The detected voltage at this time can be expressed as in equation (1).

Here, dR / dT is a resistance temperature coefficient, dT / dP is a thermal resistance, and both depend on the material and shape of the bolometer 102. P ₁₁ is power supplied from the slot antenna 104 to the bolometer 102.

  When such an antenna-coupled microbolometer 100 is used, the volume of the bolometer 102 can be reduced regardless of the size of the light receiving surface, in addition to being able to lead to a decrease in heat capacity without using an absorption film. . Therefore, by supplying the far-infrared light power received by the slot antenna 104 to the bolometer 102 having a small volume, the response speed and sensitivity of the far-infrared light can be improved.

Here, the received power of the antenna element is determined by the product of the power density of the effective aperture surface of the antenna element and the electromagnetic wave, and the effective aperture surface of the antenna element is proportional to the square of the wavelength. Therefore, even if the antenna elements have the same gain, if the wavelengths are different, the effective aperture surface is different and the received power is different. For example, when the power density is the same, the reception power in the submillimeter wave (2.5 THz) takes a very small value of 1.4 × 10 ⁻⁶ times that of the microwave (3 GHz). For this reason, it is necessary to improve the reception power in the submillimeter wave band. Therefore, the present inventors have proposed an antenna-coupled microbolometer array in which a bolometer is coupled to each individual slot antenna (see, for example, Non-Patent Document 1).

  FIG. 12 is a diagram illustrating an example of an antenna-coupled microbolometer array. In the antenna-coupled microbolometer array 200, a plurality of rectangular slot antennas 206 as antenna elements are formed on a metal layer 204 stacked on a dielectric 202, and a thin slit-shaped groove 210 is provided on the metal layer 204. Thus, the left and right metal surfaces are insulated so that a constant current can be applied to the bolometer 208 and a detection voltage can be taken out from the bolometer 208. This antenna-coupled microbolometer array 200 is different from the antenna-coupled microbolometer 100 shown in FIG. 10 in that a plurality of slot antennas 206 each have a bolometer 208. For example, the detection voltage when two single-slot antenna-coupled microbolometers are arranged in series can be expressed as in equation (2).

  Here, if the bolometer characteristics of the respective antenna elements, that is, (dR / dT) (dT / dP) are equal, it can be expressed as the following equation (3).

  Further, when considering similarly the case where the slot of the slot antenna 206 is an n-array, the detected voltage can be expressed by the following equations (4) and (5).

  The array structure in the antenna-coupled microbolometer array 200 as described above is suitable for coupling with a bolometer that detects only the power of far-infrared light. Therefore, when the number of antenna elements is increased, a detection voltage proportional to the number of arrays can be obtained.

The Institute of Image Information and Television Engineers Vol. 55, no. 2 (2001) pp. 310-316

  However, the conventional antenna-coupled microbolometer array can detect only the polarization of the electromagnetic wave in a specific direction. In addition, although the gain can be increased by increasing the number of antenna element arrays, there is a problem that the directivity of the antenna elements changes accordingly.

  The present invention solves the above-described conventional problems, and an electromagnetic wave detection element and an electromagnetic wave that can detect only an electromagnetic wave in the terahertz region without increasing the directivity and increasing only the gain and not depending on the polarization plane. An object is to provide a detection device.

  As a result of intensive studies in order to solve the above-described problems, the present inventors have reached the present invention. That is, the electromagnetic wave detection element according to the present invention is an element for detecting an electromagnetic wave in the terahertz region regardless of the plane of polarization. The dielectric, the metal layer formed on the surface thereof, and the metal layer are substantially mutually connected. The first antenna element group that is formed in an array with equal intervals and receives the electromagnetic wave, and the received power at the first antenna element group that is formed at substantially the center of each of the antenna elements of the first antenna element group A first antenna element formation region comprising a first detection element group for converting the detection voltage into a detection voltage, and a region other than the first antenna element formation region so that the plane of polarization of the first antenna element group is substantially orthogonal A second antenna element group that is formed in an array at substantially equal intervals on the metal layer and that receives the electromagnetic wave, and is formed at a substantially central portion of each antenna element of the second antenna element group. And a second antenna element formation region comprising a second detection element group for converting received power at the second antenna element group into a detection voltage, and the metal layer is formed with the first antenna element formation. And a groove portion for forming a plurality of connection regions for outputting a detection voltage by the first detection element group and the second detection element group in the region and the second antenna element formation region.

  An electromagnetic wave detection device according to the present invention is an electromagnetic wave detection device comprising an electromagnetic wave detection element for detecting an electromagnetic wave in a terahertz region regardless of a plurality of polarization planes arranged in a matrix. The elements include a dielectric, a metal layer formed on the surface thereof, a first antenna element group that receives the electromagnetic waves and is formed in an array at substantially equal intervals on the metal layer, and the first antenna element group. A first antenna element formation region formed in a substantially central portion of each of the antenna elements, the first antenna element formation region comprising a first detection element group for converting received power at the first antenna element group into a detection voltage; and The antenna elements are formed in an array at substantially equal intervals on the metal layer other than the first antenna element formation region so that the plane of polarization and the plane of polarization are substantially orthogonal, and receive the electromagnetic waves. And a second detection element group which is formed at substantially the center of each of the antenna elements of the second antenna element group and the second antenna element group and converts received power at the second antenna element group into a detection voltage. Two antenna element formation regions, and the metal layer is formed by the first detection element group and the second detection element group in the first antenna element formation region and the second antenna element formation region. It is characterized by having a groove for forming a plurality of connection regions for outputting a detection voltage.

  According to the present invention, it is possible to detect electromagnetic waves in the terahertz region without depending on the polarization plane, and it is possible to increase only the gain without changing the directivity of the antenna element.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Needless to say, the present invention is not limited to the following examples, and can be arbitrarily changed without departing from the gist of the present invention.

  FIG. 1 is a diagram schematically showing an electromagnetic wave detecting element in the present embodiment. The electromagnetic wave detection device 1 includes a large number of electromagnetic wave detection elements 2 in which antenna elements and detection elements are integrated. When the frequency of the received wave is 2.5 THz, for example, 2500 pixels are arranged in a square with a side of 1 cm. Operates as an imaging device.

  The electromagnetic wave detection element 2 is composed of, for example, one unit of a two-dimensional element for detecting 2.5 THz, and twelve slot arrays are arranged two-dimensionally. One unit has a side of about 2λ (λ is an incident wavelength), and when the incident wave is 2.5 THz, a side has a square shape of about 200 μm, that is, a side has a wavelength of 2.5 THz of 118 μm. It is comprised so that it may become about twice as long. The size of one unit of the two-dimensional element is not particularly limited as long as it is a size capable of collecting the electromagnetic wave in the terahertz region, and may be another size.

  As described above, the electromagnetic wave detection element 2 constituting one unit of the electromagnetic wave detection device 1 includes the antenna element formation region 10, the antenna element formation region 20, the antenna element formation region 30, and the antenna element formation region 40.

  FIG. 2 is a diagram showing a detailed configuration of the electromagnetic wave detection element in the present embodiment. The antenna element formation region 10 to the antenna element formation region 40 are provided on a dielectric (not shown), a metal layer laminated on the surface of the dielectric, an antenna element provided on the metal layer, and each antenna element. Detection element.

  For example, in the antenna element formation region 10, three antenna elements 12 are provided in a metal layer 11 formed on a dielectric material in an array with substantially equal intervals in a direction parallel to the longitudinal direction. A groove portion 14 that is formed at a substantially central portion of the antenna element 12 and that is a groove portion for outputting a detected voltage is formed substantially in parallel with the upper side surface of the dielectric and is opened at the edge of the dielectric.

  The dielectric is made of a dielectric material having a low loss in the frequency band of the antenna element 12, that is, a material that transmits the electromagnetic wave without substantially absorbing it. This dielectric functions as an insulating material that does not conduct electricity with respect to a DC voltage. The dielectric has a dielectric constant ε, and a material having an arbitrary dielectric constant can be used as will be described later. Specifically, quartz, alumina, quartz, gallium arsenide, or the like can be used as the dielectric material.

  In addition, the thickness of the dielectric is optimally set to an odd multiple of a quarter wavelength in terms of antenna characteristics, but this is not the case when a lens is used as the dielectric material.

  The metal layer 11 formed on the surface of the dielectric is made of, for example, a metal material and constitutes a conductive layer. This metal layer 11 is joined to a dielectric by a technique such as vapor deposition, a metal having strong adhesion to the dielectric, for example, an aluminum barrier metal layer such as chromium or titanium, and gold, copper, nickel or the like on the surface thereof. It consists of a power feeding layer. The metal layer 11 may be a single layer or a laminate of a plurality of layers. Moreover, it is preferable that the thickness of the metal layer 11 is about the incident depth (skin depth) of the incident wave or thicker.

  The metal layer 11 has a groove 14a and a groove 14b. The groove 14 is a thin slit-shaped line, is formed substantially parallel to the upper surface of the dielectric, and is opened at the edge of the dielectric. The groove 14 is preferably formed so as to be located at a distance of about 0.25 L from the longitudinal end of the antenna element 12 so as not to affect the reception characteristics of the antenna element 12. Here, L refers to the length of the antenna element 12 in the longitudinal direction. The groove 14 formed in this way is insulated from the left and right metal layers 11 with respect to the longitudinal direction of the groove 14 to apply a constant current to the detection element 13 and output a detection voltage from the detection element 13. A connection area is formed.

  The antenna element 12 formed on the metal layer 11 is a portion that is hollowed out in a rectangular shape in the metal layer 11 so that the dielectric is exposed when viewed from one side where the metal layer 11 is laminated. The antenna element 12 is formed by processing the metal layer 11 at a predetermined position by an etching technique or the like. The antenna element 12 is preferably provided with, for example, a substantially rectangular slot in the metal layer 11, and the same slots are arranged in parallel in an array without changing the antenna pattern, thereby increasing the gain.

  Moreover, it is preferable that the arrangement of the antenna elements in each antenna element formation region has symmetry. For example, as shown in the present embodiment, the number of antenna elements in each antenna element formation region is set to 3 arrays so that the antenna elements are arranged symmetrically, thereby making it easy to manufacture the electromagnetic wave detecting element 2 It can be. Furthermore, by arranging the antenna elements symmetrically, the independence of each antenna element can be maintained, and four pairs of antennas in the antenna element formation region 10 to the antenna element formation region 40 as shown in the present embodiment. Can be arranged in a substantially square shape, which is convenient for arraying.

  Note that the number of antenna elements 12 is not limited to a total of 12 arrays in which the number of antenna elements in each antenna element formation region is three as shown in the present embodiment. The number of arrays in which electromagnetic waves in the region can be collected can be set.

In the antenna element 12 in the present embodiment, the length L in the longitudinal direction of each antenna element 12 parallel to one surface of the metal layer 11 and the length W in the short direction of each slot are determined by the average wavelength λ of electromagnetic waves. _m is used to operate as a one-wavelength antenna. For example, L is set to about 0.72λ _m and W is set to about 0.08λ _m so as to operate as a one-wavelength antenna having an impedance of 50 ohms. Here, λ _m is the average wavelength of the electromagnetic wave in the terahertz region to be detected, and can be expressed by equation (6).

Here, λ ₀ is the wavelength of the electromagnetic wave in the atmosphere, λ _m is the average wavelength of the electromagnetic wave, and ε _r is the dielectric constant of the dielectric. Therefore, any dielectric can be used in this embodiment as described above.

Further, the distance d between the centers of the antenna elements in the direction of the electric field (E-plane) of the antenna element 12 can be expressed as 0 <d <2λ _d, and in this embodiment is particularly about 0.5λ _d . Is preferred. Here, λ _d is a dielectric wavelength represented by the equation (7). The reason for this will be described below.

FIG. 3 is a diagram illustrating the relationship between the received power and the slot interval of the antenna element. FIG. 3 shows the result of the received signal when the slot array is irradiated with the microwave of 4.7 GHz. The horizontal axis is the distance d in the E-plane direction of the 3-slot array, and the vertical axis is the sum of the received power of each antenna element. Show. Received from this result, most received power is large when the slot distance and 1.5 [lambda] _d, and then when a 0.5 [lambda _d spacing increases, whereas in the the 1.0Ramuda _d and 2.0Ramuda _d It was confirmed that the power decreased.

Thus, when the distance d between the centers of the antenna elements 12 in the E-plane direction of the antenna element 12 is set to 0.5λ _d and 1.5λ _d , it is 1.5λ when compared with the same number of arrays. Although an array of at _d-spacing is optimal, the area occupied by three slots arranged at 1.5 [lambda] _d intervals by arranging the slots at 0.5 [lambda _d interval when compared with the received power per area 7 Slots can be placed. That is, about 3dB increase in the sum of the total received power towards the 7-slot array of 0.5 [lambda _d spacing than 3 slot array of 1.5 [lambda] _d spacing. Therefore, from the viewpoint of sensitivity to the area occupied by the sensing element 22 in this embodiment, the spacing of the antenna elements 21 arranged in the E-plane direction is preferably set to about 0.5 [lambda _d spacing.

  The detection element 13 formed on the antenna element 12 is made of, for example, a semiconductor such as polysilicon or amorphous silicon, a metal such as platinum, tantalum, or nickel, a superconductor such as niobium nitride, YBCO, vanadium oxide, or ceramic. The antenna element 12 is disposed at a substantially central portion of the slot that is a feeding point. The detection element 13 is an element that utilizes the property that the resistance value of the resistor changes according to temperature. For example, the electromagnetic wave in the terahertz region that is incident using the bolometer as the detection element 13 is converted into heat by the sensor unit of the pixel, The temperature change of the sensor can be detected and read out in the form of an electrical signal.

  The detection element 13 is formed such that the length of the detection element 13 parallel to the metal layer 11 with respect to the longitudinal direction of the antenna element 12 is about 20% or less with respect to the length of the antenna element 12 in the longitudinal direction. It is preferable. By forming the detection element 13 in this way, it is possible to reduce the influence on the reception operation of the antenna element 12 and efficiently convert the power of the electromagnetic wave in the terahertz region received by the antenna element 12 into a detection voltage. Become.

  Further, in the detection element 13 arranged at the center of the antenna element 12, the width of the antenna element 12 in the longitudinal direction affects the center frequency and the antenna resistance (radiation resistance) of the antenna element 12. Therefore, the detection element 13 can operate the antenna element 12 as designed by setting the width of the antenna element 12 in the longitudinal direction to 20% or less of the length in the longitudinal direction of the antenna element 12.

  Next, referring to FIG. 2 again, the configuration of the antenna element formation region 10 to the antenna element formation region 40 of the electromagnetic wave detection element 2 in the present embodiment will be further described. Note that the configuration in the antenna element formation region 20 to the antenna element formation region 40, that is, the d, W, L values and the shapes of the antenna element and the detection element are the same as those in the antenna element formation region 10 described above. Omitted.

  The antenna element formation region 20 rotates the antenna element formation region 10 by about 90 degrees in a clockwise direction when viewed from the upper surface of the metal layer 11, and the antenna element formation region 10 is mirror-symmetrical with respect to AA. Is formed. In the antenna element formation region 20, the antenna elements 21 are formed in an array at substantially equal intervals in a direction substantially parallel to the longitudinal direction. That is, the antenna elements 21 in the antenna element formation region 20 are formed so that the longitudinal direction thereof is substantially orthogonal to the longitudinal direction of the antenna elements 12 in the antenna element formation region 10. Therefore, each antenna element 21 in the antenna element formation region 20 has a plane of polarization substantially orthogonal to each antenna element 12 in the antenna element formation region 10. Here, the plane of polarization refers to a plane in which the direction of the electric field and the traveling direction are constant.

  The groove 23a and the groove 23b are thin slit-shaped lines, are formed substantially parallel to the upper surface of the dielectric, and open at the edge of the dielectric. With such a configuration, insulation with the left and right metal layers 11 with respect to the longitudinal direction of the groove 23 is formed, and a connection region for applying a constant current to the detection element 22 and outputting a detection voltage from the detection element 22 is formed. ing.

  Thus, the electromagnetic wave detection element 2 can detect the electromagnetic wave in the terahertz region without depending on the polarization plane by having the antenna element formation region 10 and the antenna element formation region 20. Therefore, for example, it is possible to detect a vertically polarized wave having an electric field perpendicular to the earth and a horizontally polarized wave having an electric field horizontal to the earth from among terahertz electromagnetic waves in the plane of polarization.

  Each antenna element 31 in the antenna element formation region 30 is formed such that its longitudinal direction is substantially parallel to the longitudinal direction of each antenna element 21 in the antenna element formation region 20. In addition, each antenna element 31 in the antenna element formation region 30 is formed so that its longitudinal direction is substantially orthogonal to the longitudinal direction of each antenna element 12 in the antenna element formation region 10. That is, the antenna element formation region 30 is formed so that the plane of polarization of each antenna element 21 of the antenna element formation region 20 is substantially the same, and the plane of polarization of each antenna element of the antenna element formation region 10 is substantially the same. So as to be orthogonal to each other.

  The groove part 33a and the groove part 33b are thin slit-shaped lines, are formed substantially in parallel with the upper surface of the dielectric, and open at the edge of the dielectric. With such a configuration, a connection region for applying a constant current to the detection element 32 and outputting a detection voltage from the detection element 32 is formed by insulating the left and right metal layers 11 with respect to the longitudinal direction of the groove 33. ing.

  Each antenna element 41 in the antenna element formation region 40 is formed such that its longitudinal direction is substantially parallel to the longitudinal direction of each antenna element 12 in the antenna element formation region 10. In addition, each antenna element 41 in the antenna element formation region 40 is formed such that its longitudinal direction is substantially orthogonal to the longitudinal direction of each antenna element in the antenna element formation region 20 and the antenna element formation region 30. That is, each antenna element in the antenna element formation region 40 is formed so that the plane of polarization is substantially the same as each antenna element 12 in the antenna element formation region 10, and each antenna element in the antenna element formation region 20 is formed. 21 and the antenna element 31 in the antenna element formation region 30 are formed so that the plane of polarization is substantially orthogonal.

  The groove 43a and the groove 43b are thin slit-shaped lines, are formed substantially parallel to the upper surface of the dielectric, and open at the edge of the dielectric. With such a configuration, a connection region for applying a constant current to the detection element 42 and outputting a detection voltage from the detection element 42 is formed by insulating the groove 43 from the left and right metal layers 11.

  In other words, the antenna element formation region 10 and the antenna element formation region 40 have a point object positional relationship with respect to the center point of one pixel having a side of about 200 μm when the frequency of the received wave is 2.5 THz, and The antenna element formation region 20 and the antenna element formation region 30 are formed so as to have a point object positional relationship with respect to the center point of one pixel having a side of about 200 μm. By including the antenna element formation region 10 to the antenna element formation region 40 as described above, it is possible to detect electromagnetic waves in the terahertz region without depending on the plane of polarization. Therefore, for example, two orthogonal polarizations of electromagnetic waves in the terahertz region, that is, vertical polarization and horizontal polarization can be detected. In this way, by separating and detecting the two polarized waves, it is possible to improve the separability of electromagnetic waves in the terahertz region.

  In addition to the antenna element forming region 10 and the antenna element forming region 20, when the antenna element forming region 30 and the antenna element forming region 40 are further included, the antenna element for receiving electromagnetic waves in the terahertz region is used. Since the number can be increased, electromagnetic waves in the terahertz region can be detected with higher sensitivity.

  Next, the operation of the electromagnetic wave detection element 2 according to the present embodiment will be described. For example, when the electromagnetic wave detection element 2 is irradiated with an electromagnetic wave in the terahertz region, the power received independently by each antenna element is supplied to each detection element. The resistance value of the detection element changes based on the power supplied from each antenna element, and the voltage across the detection element changes due to the applied current. In this way, the received power of the electromagnetic wave in the terahertz region received independently by each antenna element can be output as the detection voltage of each detection element.

  FIG. 4 is a diagram showing the detection principle of the electromagnetic wave detection element in the present embodiment. A plurality of connection regions for outputting detection voltages by the respective detection elements connected in series are formed by the groove portions 14, 23, 33, and 43 provided in the metal layer 11 shown in FIG. As shown in FIG. 4, for example, when the electromagnetic wave detection element 2 is irradiated with an electromagnetic wave in a terahertz region where the frequency of the received wave is 2.5 THz, the antenna element formation region 10 is based on the power supplied from each antenna element. Detection element 13a, detection element 13b, detection element 13c, detection element 22a, detection element 22b, detection element 22c in antenna element formation region 20, detection element 32a, detection element 32b, detection element 32c, and antenna element in antenna element formation region 30 The detection element 42a, the detection element 42b, and the detection element 42c in the formation region 40 convert the detection voltage into a detection voltage, and the converted voltage is output via the terminal 15, the terminal 24, the terminal 34, and the terminal 44.

  Next, the reason why the detection voltage is determined only by the number of arrays in the electromagnetic wave detection element 2 according to the present embodiment will be described with reference to FIGS.

  FIG. 5 is a diagram showing a reception pattern when a microwave of 4.7 GHz is irradiated from a single slot to a 9-slot array. The upper side is a pattern on the air side, the lower side is a pattern on the dielectric side, and 0 ° and 180 ° are angles perpendicular to the substrate. Each reception pattern is a combination of reception patterns for each number of arrays. The thick line is for a single slot and is shown as a theoretical pattern.

  From this result, it was confirmed that the received power increased as the number of arrays increased. In addition, it was confirmed that the shape of the received pattern substantially matched the theoretical pattern of the single slot antenna regardless of the number of arrays. Furthermore, it was confirmed that the reception pattern did not change with the number of slot antenna arrays.

Note that a reception pattern that does not depend on the number of arrays can be obtained in the same manner even when 2.5 THz-CH ₃ OH laser light corresponding to electromagnetic waves in the terahertz region is irradiated (see, for example, Non-Patent Document 1).

  FIG. 6 is a diagram showing the relationship between the front detection voltage and the number of arrays in the slot antenna coupling microbolometer. The horizontal axis indicates the number of arrays, and the vertical axis indicates the detection voltage. The black circles and triangles indicate the slots formed in the metal layer 51 in which the slot antenna array is laminated on the dielectric as shown in FIG. The antenna 52, the bolometer 53 formed substantially at the center of the slot antenna 52, and the slot antenna-coupled microbolometer array 50 having a groove portion 54 and a dielectric as shown in FIG. Detection voltage when a slot antenna 62 formed in the metal layer 61, a bolometer 63 formed substantially at the center of the slot antenna 62, and a slot antenna coupling microbolometer array 60 having two-dimensionally arranged grooves 64 are used. The actual measured values are shown.

  From the results shown in FIG. 6, it was confirmed that a detection voltage proportional to the number of arrays was obtained from a one-dimensional measured value. Further, it was confirmed from the actually measured values in the one-dimensional and two-dimensional array elements that substantially the same detection voltage can be obtained regardless of the one-dimensional or two-dimensional when the number of arrays is the same. Therefore, the detection voltage in the slot antenna coupled microbolometer array can be determined only by the number of arrays.

  Next, an example of a manufacturing process of the electromagnetic wave detection element 2 according to the present embodiment will be described.

  FIG. 9 is a schematic diagram showing a manufacturing process of the electromagnetic wave detection element 2 in the present embodiment. The electromagnetic wave detection element in the present embodiment was created through steps S1 to S8 described below using a fine processing technique.

  First, in step S1, a metal layer is laminated on the dielectric 70 (a, b). As the metal layer, for example, an aluminum barrier metal layer 71 such as chromium or titanium, and a power feeding layer 72 such as gold, copper, or nickel are formed on the surface thereof. In the present embodiment, chromium is deposited as the barrier metal layer 71 and gold is deposited as the power feeding layer 72.

  In step S2, a resist 73 for exposing a portion to be an antenna element is applied to the metal layer (c). In this embodiment, positive resist ZEP-520 for electronic drawing is applied, but other well-known resists can be used.

  In step S3, the slot antenna serving as the antenna element is patterned by performing electron drawing on the resist 73 applied in step S2 (d).

  In step S4, the metal layer of the antenna part patterned in step S3 is etched. As the etching, wet etching such as chromic acid-based etching and non-chromic acid-based etching, and dry etching such as gas phase etching and plasma etching can be employed. The target metal is dissolved by etching. In this embodiment mode, it is preferable to dissolve chromium and gold which are metal layers by dry etching which is vapor phase etching because microfabrication is possible and selectivity with a photoresist is high.

  In step S5, the resist 73 is removed (f) to complete the slot antenna 75 as an antenna part (g).

  Subsequently, in step S6, a resist 76 for light exposure is again applied to the dielectric 70 processed in step S5 (h). In the present embodiment, the positive resist S-1400-31 is applied as the light exposure resist 76, but other well-known light exposure resists may be used.

  In step S7, a portion to be a detection element is patterned by light exposure (i). In the present embodiment, a part to be a bolometer is patterned by light exposure.

  In step S8, a material 77 to be a detection element is stacked on the part patterned in step S7 (j) and lifted off (k), thereby completing a slot antenna coupling microbolometer 78 that is an electromagnetic wave detection element (l). In this embodiment mode, bismuth (Bi) is vapor-deposited as the material 77 to be the detection element.

  Although FIG. 9 shows the manufacturing process of a single slot slot antenna coupling microbolometer, the antenna element can be manufactured in the same manner when the antenna elements are arrayed like the electromagnetic wave detecting element 2 in the present embodiment. it can. Further, the electromagnetic wave detection element 2 may be manufactured by using other well-known techniques without being limited to the above-described microfabrication method. Further, the slot antenna in the electromagnetic wave detection element 2 is conveniently formed in the same shape, but is not limited to this example and may be formed in different shapes.

  The electromagnetic wave detection element 2 manufactured in this way can increase only the gain without changing the directivity and can detect two orthogonal polarizations of the electromagnetic wave in the terahertz region without depending on the polarization plane. Moreover, according to the electromagnetic wave detection element 2, it is possible to detect and detect two orthogonal polarizations using vertical polarization and horizontal polarization. Thus, by separating and detecting the two polarized waves, for example, the user's separability can be improved. Furthermore, according to the electromagnetic wave detection element 2 having the antenna element formation region 10 to the antenna element formation region 40, the number of antenna elements for receiving electromagnetic waves in the terahertz region can be increased, so that the terahertz region is more sensitive. It becomes possible to detect the electromagnetic wave.

  In addition, the electromagnetic wave detection device 1 including the electromagnetic wave detection element 2 for detecting the electromagnetic wave in the terahertz region regardless of a plurality of polarization planes arranged in a matrix increases only the gain without changing the directivity. In addition, two orthogonal polarizations of the electromagnetic wave in the terahertz region can be detected without depending on the polarization plane. Furthermore, according to the electromagnetic wave detection apparatus 1 in which the plurality of electromagnetic wave detection elements 2 arranged in a matrix form have the antenna element formation region 10 to the antenna element formation region 40, vertical polarization and horizontal polarization are used and orthogonal. The two polarized waves can be detected separately. Thus, by separating and detecting the two polarized waves, for example, the user's separability can be improved.

It is a figure which shows the electromagnetic wave detection element in this Embodiment. It is a figure which shows the detailed structure of the electromagnetic wave detection element in this Embodiment. It is a figure which shows the relationship between received power and the slot space | interval of an antenna element. It is a figure which shows the detection operation of the electromagnetic wave detection element in this Embodiment. It is a figure which shows the receiving pattern at the time of irradiating the microwave 4.7GHz with respect to a 9 slot array from a single slot. It is a figure which shows the relationship between the front detection voltage in a slot antenna coupling | bonding microbolometer, and the number of arrays. It is a figure which shows a one-dimensional slot antenna coupling | bonding microbolometer array. It is a figure which shows a two-dimensional slot antenna coupling | bonding microbolometer array. It is a schematic diagram which shows the manufacturing process of the electromagnetic wave detection element in this Embodiment. It is a figure which shows an example of an antenna coupling | bonding microbolometer. It is a figure which shows the detection principle of an antenna coupling | bonding microbolometer. It is a figure which shows an example of an antenna coupling | bonding microbolometer array.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electromagnetic wave detection apparatus, 2 Electromagnetic wave detection element 10, 20, 30, 40 Antenna element formation area, 11 Metal layer, 12, 21, 31, 41 Antenna element, 13, 22, 32, 42 Detection element 14, 23, 33, 43 Groove, 100 Antenna coupled microbolometer, 200 Antenna coupled microbolometer array

Claims (7)

An element for detecting electromagnetic waves in the terahertz region regardless of the plane of polarization,
A dielectric and a metal layer formed on the surface;
A first antenna element group that is formed in an array at substantially equal intervals on the metal layer and that receives the electromagnetic wave, and is formed at substantially the center of each of the antenna elements of the first antenna element group, and the first antenna A first antenna element formation region comprising a first detection element group for converting received power in the element group into a detection voltage;
A second antenna that receives the electromagnetic waves and is formed in an array at substantially equal intervals on the metal layer other than the first antenna element formation region so that the plane of polarization of the first antenna element group is substantially orthogonal to the first antenna element group. A second detection element group formed at a substantially central portion of each of the element group and the antenna element of the second antenna element group, the second detection element group converting received power at the second antenna element group into a detection voltage. An antenna element forming region,
The metal layer includes a plurality of connection regions that output detection voltages from the first detection element group and the second detection element group in the first antenna element formation region and the second antenna element formation region. An electromagnetic wave detecting element having a first groove to be formed. The metal layers other than the first antenna element forming region and the second antenna element forming region are arranged in an array at substantially equal intervals so that the plane of polarization is substantially the same as that of the first antenna element group. Formed at a substantially central portion of each of the third antenna element group that receives the electromagnetic wave and the antenna elements of the third antenna element group, and converts the received power at the third antenna element group into a detection voltage. A third antenna element formation region comprising a third detection element group
The metal layer other than the first antenna element formation region, the second antenna element formation region, and the third antenna element formation region so that the plane of polarization is substantially the same as that of the second antenna element group. Are formed in an array at substantially equal intervals, and are formed at substantially the center of each of the fourth antenna element group for receiving the electromagnetic wave and the antenna elements of the fourth antenna element group, and the fourth antenna element group. And a fourth antenna element forming region comprising a fourth detection element group for converting the received power at the detection voltage into a detection voltage,
The metal layer includes a plurality of connection regions that output detection voltages from the third detection element group and the fourth detection element group in the third antenna element formation region and the fourth antenna element formation region. The electromagnetic wave detecting element according to claim 1, further comprising a second groove portion to be formed.   The positional relationship between the first antenna element formation region and the third antenna element formation region is a point object with respect to the center point of the pixel, and the second antenna element formation region and the fourth antenna element formation region The electromagnetic wave detecting element according to claim 2, wherein the antenna element forming region is a point object with respect to a center point of the pixel.   Each detection element of the detection element group has a length with respect to the longitudinal direction of the antenna element in the detection element parallel to the metal layer so that the length in the longitudinal direction of the antenna element is about 20% or less. The electromagnetic wave detecting element according to any one of claims 1 to 3, wherein the electromagnetic wave detecting element is formed.   5. The electromagnetic wave detecting element according to claim 1, wherein the antenna element is formed in a substantially rectangular shape, and a length in a longitudinal direction thereof is about one wavelength of the electromagnetic wave.   6. The electromagnetic wave detection element according to claim 1, wherein the antenna element of the antenna element group is a slot antenna, and the detection element of the detection element group is a bolometer. An electromagnetic wave detection device comprising an electromagnetic wave detection element for detecting electromagnetic waves in a terahertz region regardless of a plurality of polarization planes arranged in a matrix,
The electromagnetic wave detecting element is
A dielectric and a metal layer formed on the surface;
A first antenna element group that is formed in an array at substantially equal intervals on the metal layer and that receives the electromagnetic wave, and is formed at substantially the center of each of the antenna elements of the first antenna element group, and the first antenna A first antenna element formation region comprising a first detection element group for converting received power in the element group into a detection voltage;
A second antenna that receives the electromagnetic waves and is formed in an array at substantially equal intervals on the metal layer other than the first antenna element formation region so that the plane of polarization of the first antenna element group is substantially orthogonal to the first antenna element group. A second detection element group formed at a substantially central portion of each of the element group and the antenna element of the second antenna element group, the second detection element group converting received power at the second antenna element group into a detection voltage. An antenna element forming region,
The metal layer includes a plurality of connection regions that output detection voltages from the first detection element group and the second detection element group in the first antenna element formation region and the second antenna element formation region. An electromagnetic wave detecting device having a groove to be formed.

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