Detection machine and detector

Abstract

To improve the accuracy of detecting a magnetic field.SOLUTION: A detection machine comprises: a diamond crystal in which an NV center is formed; a loop antenna provided on the diamond crystal; and a dielectric substrate. The NV center is arranged on one face of the diamond crystal. The dielectric substrate has a cylindrical shape opening at both an end on a detection target side in an axial direction and an end on the opposite side of the detection target side. In an axial direction view, an outer peripheral part of the diamond crystal is located on the outside of an inner peripheral part of the dielectric substrate and on the inside of an outer peripheral part of the dielectric substrate. The loop antenna is arranged on a surface of the diamond crystal on the opposite side of a surface where the NV center is formed, and is electrically connected to a high-frequency transmission line formed on the dielectric substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to detectors and detection devices. [Background technology]

[0002] Patent Document 1 discloses an apparatus that uses a SQUID element to measure the magnetic field on each point of a sample. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-014541 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, a sapphire window is inserted between the sample and the SQUID element, and a certain distance must be provided between the sapphire window and the SQUID element for thermal insulation. This makes it impossible to bring the SQUID element close to the sample. This makes it difficult to separate and observe adjacent magnetic field distributions. As such, there is room for improvement in detection accuracy. [Means for solving the problem]

[0005] A detector according to one embodiment comprises a diamond crystal in which an NV center is formed, a loop antenna provided on the diamond crystal, and a dielectric substrate, wherein the NV center is arranged on one surface of the diamond crystal, the dielectric substrate is cylindrical with both an end on the axial side of the detection object and an end opposite the detection object being open, the outer periphery of the diamond crystal is located outside the inner periphery of the dielectric substrate and inside the outer periphery of the dielectric substrate when viewed in the axial direction, and the loop antenna is arranged on the surface of the diamond crystal opposite the surface on which the NV center is formed and is electrically connected to a high-frequency transmission line formed on the dielectric substrate.

[0006] A detection device according to one embodiment is a detection device comprising the above-described detector, a light-emitting element, and a light-receiving element, wherein the light-emitting element irradiates light onto the NV center, and the light-receiving element receives fluorescence from the NV center. [Effects of the Invention]

[0007] According to a detector and a detection device according to one aspect of the present disclosure, a magnetic field can be detected with high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view illustrating an outline of a detection substrate of a detector according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a detector and a detection device according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram illustrating another example of the detector and the detection device according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram illustrating another example of the dielectric substrate. [Figure 5] FIG. 5 is a block diagram illustrating an example of the signal control unit. [Figure 6] FIG. 6 is a cross-sectional view for explaining an outline of a detection substrate of a detector according to the second embodiment. [Figure 7]FIG. 7 is a schematic diagram illustrating an example of a detector and a detection device according to the second embodiment. [Figure 8] FIG. 8 is a schematic diagram illustrating an example of the detection substrate. [Figure 9] FIG. 9 is a plan view illustrating an example of an antenna conductor. [Figure 10] FIG. 10 is a plan view illustrating another example of the antenna conductor. [Figure 11] FIG. 11 is a plan view illustrating another example of the antenna conductor. [Figure 12] FIG. 12 is a graph illustrating an example of the reflection characteristics of an antenna conductor. DETAILED DESCRIPTION OF THE INVENTION

[0009] A detector and a detection device according to an embodiment will be described below. The detector and the detection device are for detecting a magnetic field generated in a detection target. FIG. 1 is a cross-sectional view illustrating an outline of a detection substrate of a detector according to a first embodiment. FIG. 2 is a schematic diagram illustrating an example of a detector and a detection device according to the first embodiment. FIG. 3 is a schematic diagram illustrating another example of a detector and a detection device according to the first embodiment.

[0010] [First embodiment] (detection target) The detection target is an object to be detected by the detector 10 and the detection device 1, in other words, a sample. A magnetic field is generated in the detection target due to a current. In the example shown in FIG. 1, the detection target includes a dielectric 100 and conductors 101, 102, 103, and 104 arranged inside the dielectric 100. The conductors 101, 102, and 103 are arranged at intervals on the surface 100a side of the dielectric 100. The width d21 of the conductors 101, 102, and 103 is, for example, approximately 1 μm. The conductor 104 is arranged on the surface 100b side of the dielectric 100. A current I1 flows in the conductor 101 from the front side to the back side in FIG. 1. The current I1 flows on the surface 100a side of the dielectric 100. The direction of a magnetic field F1 due to the current I1 is indicated by an arrow. A current I2 flows in the conductor 102 from the back side to the front side in FIG. 1. Current I2 flows on the surface 100a side of dielectric 100. The direction of magnetic field F2 due to current I2 is indicated by an arrow. Current I3 flows in conductor 103 from the front side to the back side in FIG. 1. Current I3 flows on the surface 100a side of dielectric 100. The direction of magnetic field F3 due to current I3 is indicated by an arrow. Current I4 flows in conductor 104 from the left side to the right side in FIG. 1. Current I4 flows on the surface 100b side of dielectric 100. The direction of magnetic field F4 due to current I4 is indicated by an arrow.

[0011] (detector) The detector 10 comprises a detection substrate 11 and a dielectric substrate 13 .

[0012] The detection substrate 11 is a so-called diamond sensor, and includes a diamond crystal 111, an NV center 112, a high-frequency line conductor (not shown), and an antenna conductor 113 that is a radiator.

[0013] Diamond crystal 111 has NV centers 112 formed on a surface 111b opposite to a surface 111a in contact with antenna conductor 113. Diamond crystal 111 has a side length d11 of, for example, 2 mm. Diamond crystal 111 has a thickness d12 of, for example, 100 μm.

[0014] The surface 111a is exposed in a region where the antenna conductor 113 is not provided. The exposed portion is referred to as an exposed portion 111c. The exposed portion 111c is located in the center of the surface 111a of the diamond crystal 111.

[0015] Surface 111b is a magnetic field acting surface facing the detection target. An NV center 112 is formed on the surface 111b side. Surface 111b is a smooth plane that can be in close contact with or close to the surface of the detection target to within a few microns while remaining parallel to the surface of the detection target. A thin conductive film may be provided on surface 111b to pass a current due to magnetic field coupling with the detection target.

[0016] An objective lens (not shown) is placed close to face 111a of diamond crystal 111, and the diamond crystal 111 and the objective lens may have anti-reflection coatings on their surfaces.

[0017] The diamond crystal 111 has a surface 111b on which the NV center 112 is provided protruding from the dielectric substrate 13. The surface 111b is the part that senses the magnetic field to be measured.

[0018] The NV center 112 may be arranged singly or in multiple arrays on the face 111b side of the diamond crystal 111. In this embodiment, FIG. 1 and other figures illustrate a state in which multiple NV centers 112 are arranged. It is preferable that the orientation of the NV centers 112 is aligned in one direction. The NV centers 112 may also be crystals with multiple different orientations.

[0019] The NV center 112 is a complex defect in the diamond crystal 111 where carbon would normally be present, replaced by nitrogen, with a vacancy at the adjacent position. The NV center 112 is missing a portion of the degenerate shared electron pair. In zero magnetic field, the NV center 112 has electrons with orbital angular momentum at two levels, m=0 and m=±1. Because the m=±1 electrons have a magnetic moment, they are affected by an external magnetic field, and the degeneracy of m=±1 is broken, resulting in two more energy levels. The strength of the external magnetic field can be detected by detecting the electron spin resonance caused by these using light waves and microwaves.

[0020] The electrons in the NV center 112 are excited by light with a wavelength of 532 nm and emit fluorescence with a wavelength of 638 nm during the relaxation process. This fluorescence process is unlikely to occur at the electron spin resonance frequency. Therefore, by utilizing this property, the state of the m=±1 electrons can be observed. The electron spin resonance frequency of the NV center 112 in the diamond crystal 111 is known to be approximately 2.87 GHz in zero magnetic field. When microwaves with the frequency of this resonance point (resonance frequency) are irradiated, the fluorescence with a wavelength of 638 nm is quenched. Furthermore, the resonant frequency of the microwave changes due to changes in the state of the m=±1 electrons depending on the magnitude of the external magnetic field, etc. This change can be detected by measuring the frequency change in the fluorescence intensity, allowing for detection of magnetic fields and currents. Light with a wavelength of 532 nm enters the exposed portion 111c, and fluorescence with a wavelength of 638 nm exits the exposed portion 111c.

[0021] The high-frequency line conductor is formed on face 111a of diamond crystal 111. The high-frequency line conductor has a center conductor and a ground conductor spaced a certain distance from it. The impedance is adjusted by the distance between the center conductor and the ground conductor. The center conductor and ground conductor are connected to the center conductor and ground conductor of the high-frequency line conductor of dielectric substrate 13 by solder 15, respectively.

[0022] The antenna conductor 113 transmits and radiates microwaves to be irradiated to the NV centers 112 of the diamond crystal 111. The antenna conductor 113 is located on the surface of the diamond crystal 111 opposite to the surface on which the NV centers 112 are formed. The antenna conductor 113 is electrically connected to the exposed portion of the interior pattern 16 of the dielectric substrate 13 via solder 15. The antenna conductor 113 is provided on the outer periphery of the surface 111a of the diamond crystal 111. The antenna conductor 113 is formed in a ring shape when viewed in the normal direction of the surface 111a (hereinafter referred to as "plan view"). The antenna conductor 113 is a loop antenna formed from a conductive thin film. The end of the antenna conductor 113 is connected to the ground conductor of the high-frequency line conductor. The loop diameter of the antenna conductor 113 is approximately several mm. An exposed portion 111c is located approximately in the center of the inside of the antenna conductor 113 and serves as an optical input / output portion. The exposed portion 111 c is disposed inside the flange portion 133 of the dielectric substrate 13 .

[0023] The dielectric base 13 is a support base that supports the outer periphery of the detection board 11. The dielectric base 13 houses the detection board 11. The dielectric base 13 is formed in a cylindrical shape that houses the detection board 11. In the present disclosure, the dielectric base 13 is formed in a square cylindrical shape that corresponds to the outer shape of the detection board 11. The dielectric base 13 is formed of a resin-based material such as SiO2, glass material, ceramic material, or glass epoxy. A high-frequency transmission line is formed in the dielectric base 13, and this high-frequency transmission line is electrically connected to the antenna conductor 113.

[0024] The dielectric base 13 has a first housing portion 131, a second housing portion 132, and a flange portion 133. The first housing portion 131 and the second housing portion 132 are separated by the flange portion 133, which is located in the middle of the dielectric base 13 in the axial direction. The flange portion 133 protrudes toward the inner periphery of the dielectric base 13. The flange portion 133 is formed in a ring shape in a plan view. The first housing portion 131 is a support portion that supports the optical window 14. The first housing portion 131 is located on one side of the dielectric base 13 in the axial direction. The optical window 14 is located in the center of the first housing portion 131 of the dielectric base 13. The second housing portion 132 is a support portion that supports the detection board 11. The second housing portion 132 is located on the other side of the dielectric base 13 in the axial direction. The detection board 11 is located in the center of the second housing portion 132 of the dielectric base 13.

[0025] Although FIG. 2 shows a configuration in which the surface 111b protrudes in the axial direction from the surface 13b of the dielectric substrate 13, the surface 111b and the surface 13b of the dielectric substrate 13 may be flat.

[0026] The optical window 14 is housed in the dielectric substrate 13 and is disposed opposite the detection substrate 11. The optical window 14 is supported by a first housing portion 131 of the dielectric substrate 13. The optical window 14 transmits and receives light to and from the NV center 112 of the detection substrate 11 of the detector 10. The optical window 14 is formed of a material such as sapphire or quartz. One surface 14a of the optical window 14 is flat with the surface 13a opposite to the surface 13b of the dielectric substrate 13. The surface 14b opposite to the surface 14a of the optical window 14 faces the surface 111a of the diamond crystal 111 of the detection substrate 11 with a gap between them. The optical window 14 is not an essential component.

[0027] The dielectric substrate 13 includes a high-frequency transmission line that transmits microwave signals to the detection board 11 and includes an internal pattern 16 and an RF (Radio Frequency) via 17. The high-frequency transmission line is composed of two conductors provided on the dielectric substrate 13. One of the conductors is a center conductor, and the other is a ground conductor. The center conductor and the ground conductor are separated by a certain distance. The internal pattern 16 and the RF via 17 form either the center conductor or the ground conductor. The center conductor and the ground conductor are connected to the center conductor and the ground conductor of the high-frequency line conductor of the detection board 11, respectively, by solder 15. The internal pattern 16 is a thin-film conductor pattern formed inside the dielectric substrate 13, and includes a portion that is partially exposed on the surface of the dielectric substrate 13.

[0028] An example of a configuration in which the interior pattern 16 and RF via 17 function as a high-frequency transmission line will be described. The RF via 17 has a through-hole formed in its inner wall. This through-hole functions as a signal line. The interior pattern 16 may have ground lines (ground conductors) running on both sides of the signal line (center conductor) in a plan view. The through-hole of the RF via 17 is connected to the signal line of the interior pattern 16. The signal line of the interior pattern 16 is connected via solder 15 to a pad conductor 1142 (see, for example, FIG. 9 ) to which an end of the antenna conductor 113 is connected. In this way, a high-frequency microwave signal is transmitted through a high-frequency transmission path that passes through the microwave source, pad 18, via 17, interior pattern 16, solder 15, pad conductor 1142, and antenna conductor 113 in this order. As a result, microwaves are generated from the antenna conductor 113.

[0029] The solder 15 is provided on the lower surface of the flange portion 133 of the dielectric base 13. The solder 15 is provided in a ring shape in a plan view. The solder 15 is electrically connected to the antenna conductor 113 and the interior pattern 16 of the detection board 11.

[0030] The interior pattern 16 is provided on the flange portion 133 of the dielectric substrate 13. The interior pattern 16 is electrically connected to the solder 15 and the RF via 17.

[0031] The RF via 17 extends from the interior pattern 16 to the surface 13a of the dielectric substrate 13 at the outer periphery of the dielectric substrate 13. The RF via 17 is electrically connected to the interior pattern 16 and the bonding pad .

[0032] The bonding pad 18 is provided on the surface 13a of the dielectric substrate 13. The bonding pad 18 is electrically connected to the RF via 17.

[0033] In the dielectric base 13 described above, an example has been shown in which the dielectric base 13 has the first accommodating portion 131, the second accommodating portion 132, and the flange portion 133, but it is also possible to have a configuration that does not have these first accommodating portion 131, the second accommodating portion 132, and the flange portion 133.

[0034] FIG. 4 is a schematic diagram illustrating another example of a dielectric substrate. For example, as shown in FIG. 4, the dielectric substrate 13 may be flat and have a through-hole in the center. The dielectric substrate 13 has a high-frequency transmission line on its surface or inside. The diamond crystal 111 of the detection substrate 11 is provided on the lower surface of the dielectric substrate 13 so as to cover the through-hole. The antenna conductor 113 provided on the upper surface (surface 111a) of the detection substrate 11 is connected to the high-frequency transmission line of the dielectric substrate 13 via solder 5. The exposed portion 111c of the diamond crystal 111 is visible from the upper surface side of the dielectric substrate through the through-hole. A high-frequency connector may be attached to the end of the high-frequency transmission line.

[0035] With this configuration, even if the diamond crystal 111 is small, the dielectric substrate is used as an intermediary, allowing for a large, easily handled microwave input terminal. This allows for easy transmission of microwaves by controlling the characteristic impedance to the NV center 112. With this configuration, light and microwaves are input and output from the surface 111a of the detector 10, enabling detection with high sensitivity by placing the target microcircuit or the like close to the surface 111b. Furthermore, because microwaves are irradiated onto the NV center 112 from the surface 111a, microwave transmission is less likely to be impeded by the target microcircuit or the like than when the NV center 112 is irradiated from the surface 111b. This makes the detector suitable for detecting various microcircuits, such as those with large thicknesses or those containing multiple circuits in the thickness direction. Furthermore, even if the antenna conductor 113 is small, microwaves can be efficiently applied using a high-frequency line conductor or a high-frequency connector, making it suitable for high-resolution detection of microcircuits or the like.

[0036] (Detection device) The detection device 1 has a detector 10, a light-emitting element 21, and a light-receiving element 22. More specifically, the detection device 1 includes a detection substrate 11, a dielectric base 13 that houses the detection substrate 11, and the light-emitting element 21 and light-receiving element 22 that input and output light to and from an NV center 112. The detection device 1 may also include a sample stage 110 on which a detection target is placed.

[0037] The light-emitting element 21 and the light-receiving element 22 detect the magnetism of the dielectric 100, which is the detection target. In this embodiment, the light-emitting element 21 and the light-receiving element 22 detect the magnetism while scanning over the dielectric 100. The light-emitting element 21 and the light-receiving element 22 are arranged facing each other on the detection substrate 11 of the detector 10. The light-emitting element 21 and the light-receiving element 22 input and output light to the NV center 112 of the diamond crystal 111. The light-emitting element 21 is a light source, and the light-receiving element 22 is a light receiver. The light-emitting element 21 and the light-receiving element 22 are controlled by a control circuit (not shown). The control circuit controls the light emission of the light-emitting element 21. The control circuit controls the light reception of the light-receiving element 22. The control circuit processes a signal of red fluorescence received by the light-receiving element 22. The control circuit outputs the magnetic field strength as a result.

[0038] The light-emitting element 21 irradiates light onto the detection substrate 11 of the detector 10. The light-emitting element 21 emits excitation light that irradiates the diamond crystal 111. The light-emitting element 21 irradiates the excitation light onto the NV center 112. The light-emitting element 21 is a laser diode. The light-emitting element 21 emits laser light with a wavelength of, for example, 527 nm based on the control of the control circuit. The light-emitting element 21 emits green excitation light. For example, a green light-emitting diode (LED: Light Emitting Diode), a green surface-emitting laser diode (VCSEL: Vertical Cavity Surface Emitting Laser), a green edge-emitting laser diode (LD: Laser Diode), etc. can be used as the light-emitting element 21.

[0039] The light receiving element 22 detects the fluorescence from the detection substrate 11 of the detector 10. The light receiving element 22 is a photodiode. The light receiving element 22 receives the fluorescence from the NV center 112 of the diamond crystal 111 based on the control of the control circuit. The light receiving element 22 receives the fluorescence emitted by the excitation light from the diamond crystal 111. The light receiving element 22 can be, for example, a Si-PIN photodiode (PD: Photo Diode) or an InGaAs-PIN photodiode.

[0040] 2, the light-emitting element 21 and the light-receiving element 22 may be disposed in close contact with the exposed portion 111c of the surface 111a of the diamond crystal 111. In this case, power is supplied to each of the light-emitting element 21 and the light-receiving element 22 from wiring (not shown) formed independently of the dielectric substrate 13.

[0041] 3, the light-emitting element 21 and the light-receiving element 22 may be arranged directly above the exposed portion 111c of the face 111a of the diamond crystal 111, spaced apart by a certain distance. In this case, an optical window, which is an optical component such as a lens or mirror, may be used between the light-emitting element 21 and the light-receiving element 22 and the NV center 112. The light-emitting element 21 and the light-receiving element 22 may be an optical pickup in which light-emitting and receiving elements are integrated.

[0042] The sample stage 110 is a platform on which an object is placed. The sample stage 110 has a flat surface 110a. The object is placed on the surface 110a.

[0043] The light emitting element 21 and the light receiving element 22 may be miniaturized to input and output fluorescence and excitation light while scanning the surface 111 a of the diamond crystal 111 of the detection substrate 11 of the detector 10 .

[0044] The light emitting element 21 and the light receiving element 22 may be shaped so as to be able to input and output fluorescence and excitation light to the entire surface 111a of the diamond crystal 111 of the detection substrate 11 of the detector 10 without scanning.

[0045] The microwaves irradiated to the NV centers 112 of the diamond crystal 111 are generated by an oscillator 31 (see FIG. 5 ), which is a microwave source. The oscillator 31 is, for example, a voltage-controlled oscillator (VCO). The oscillator 31 may be composed of a semiconductor element such as a heterojunction bipolar transistor (HBT), a field-effect transistor (FET), a complementary metal-oxide semiconductor (MOS), or a high electron mobility transistor (HEMT). The semiconductor element is made of, for example, Si, GaAs, or GaN. Such an oscillator is connected to the pad 18 via a high-frequency circuit (not shown). The oscillator is not shown in FIGS. 2 and 3 .

[0046] (Signal control unit) FIG. 5 is a block diagram illustrating an example of a signal control unit. The signal control unit 200 is, for example, a microcomputer. The signal control unit 200 controls the light-emitting operation of the light-emitting element 21. The signal control unit 200 controls the light-receiving operation of the light-receiving element 22. The signal control unit 200 controls the microwave oscillation operation of the oscillator 31, which is a microwave source that generates microwaves. An optical signal of a fluorescent image captured by the light-receiving element 22 is output to the signal control unit 200. The signal control unit 200 has a signal processing unit 202, which is a signal processing circuit, and a control unit 201, which is a control circuit. The control unit 201 supplies timing signals to the light-receiving element 22, the light-emitting element 21, and the oscillator 31 to control their operation. The control unit 201 controls the setting of the frequency of the microwave output from the oscillator 31. The signal processing unit 202 performs image processing of the fluorescent image based on the optical signal input from the light-receiving element 22. The signal control unit 200 and the oscillator 31 are each formed on, for example, a semiconductor chip. Although FIG. 5 shows an example in which the signal control unit 200 and the oscillation element 31 are formed on different semiconductor chips, they may also be formed on a single semiconductor chip.

[0047] (Detection method) A method for detecting a magnetic field of a detection target using the detection device 1 will be described. First, a dielectric 100, which is a detection target, is placed on the surface 110a of the sample stage 110. Magnetic fields F1, F2, F3, and F4 are generated in the dielectric 100 by currents I1, I2, I3, and I4.

[0048] The surface 100a of the dielectric 100 is brought close to or in close contact with the surface 111b of the diamond crystal 111, which is the magnetic field acting surface of the detection substrate 11 of the detection device 1. A spatial change in the direction or magnitude of the magnetic field generated in the dielectric 100 acts on the NV center 112 located near the surface 111b of the diamond crystal 111 of the detection substrate 11 of the detection device 1.

[0049] Then, the detection substrate 11 is scanned with the fluorescence and excitation light by the light-emitting element 21 and the light-receiving element 22 of the detection device 1. As a result, the NV centers 112 are irradiated and excited from the exposed portion 111c of the surface 111a of the diamond crystal 111 of the detection substrate 11. The light-emitting element 21 and the light-receiving element 22 receive, as fluorescence, an electron spin resonance signal of the NV centers 112 excited by the excitation light from the exposed portion 111c of the surface 111a of the diamond crystal 111. The light-emitting element 21 and the light-receiving element 22 receive a fluorescence signal corresponding to a change in the direction or magnitude of the magnetic field.

[0050] In this way, the light-emitting element 21 and the light-receiving element 22 of the detection device 1 detect the magnetic charge of the detection object. The light-emitting element 21 and the light-receiving element 22 detect the level of the magnetic charge of the detection object. The light-emitting element 21 and the light-receiving element 22 calculate the strength of the magnetic field from the signals that are the detection results of the light-emitting element 21 and the light-receiving element 22, and output the result.

[0051] (Application of the detection device) One example of an application of the detection device 1 shown in Fig. 2 is the magnetic head of a magnetic force microscope. The magnetic head is connected to the magnetic force microscope when in use. In this case, the semiconductor element with the signal control unit and the semiconductor element with the microwave source are mounted on the magnetic force microscope, not on the magnetic head itself. The bonding pad 18 is connected to the microwave source, and the light-emitting element 21 and the light-receiving element 22 are connected to the signal control unit.

[0052] (effect) As described above, in this embodiment, both the NV center 112 and the antenna conductor 113 can be provided in the diamond crystal 111. According to this embodiment, the NV center 112 and the antenna conductor 113 can be provided close to each other. As a result, this embodiment can accurately position the antenna conductor 113 relative to the NV center 112. Therefore, this embodiment can effectively apply microwaves of sufficient intensity to the NV center 112 in a specific location with little power.

[0053] In this embodiment, an NV center 112 is formed on one surface 111b of a diamond crystal 111, and an antenna conductor 113 is formed on the opposite surface 111a. In this embodiment, the antenna conductor 113 on the other surface 111a can be accurately positioned relative to the NV center 112 on one surface 111b during manufacturing. According to this embodiment, microwaves of sufficient intensity can be effectively applied to the NV centers 112 in specific locations with little power.

[0054] In this embodiment, one surface 111b of the diamond crystal 111 is arranged so as to be close to the detection target. According to this embodiment, the NV center 112 is close to the detection target, thereby improving measurement accuracy. Furthermore, in this embodiment, the NV center 112 is formed on one surface 111b of the diamond crystal 111, and the antenna conductor 113 is formed on the opposite surface 111a, so that one surface 111b can be brought closer to the detection target.

[0055] In this embodiment, even if multiple antenna conductors 113 are provided and the circuit becomes complicated, the multiple NV centers 112 and each circuit can be arranged with high precision positional relationships. According to this embodiment, it is also easy to implement an expansion so that multiple NV centers 112 operate independently.

[0056] In this embodiment, the NV center 112 and the antenna conductor 113 are integrated with the diamond crystal 111 sandwiched therebetween. This embodiment reduces fluctuations in the arrangement due to temperature fluctuations, mechanical vibrations, and other factors during assembly as a module. This embodiment enables highly stable operation.

[0057] In this embodiment, no detection window or the like is provided on surface 111b of diamond crystal 111, which is the magnetic field acting surface of detection substrate 11 of detection device 1. According to this embodiment, surface 111b of diamond crystal 111 of detection device 1 can be brought close to or in close contact with the detection target. As a result, this embodiment can detect changes in the direction or magnitude of a magnetic field of about several μm, which were previously difficult to detect, and the spatial distribution of current vectors detected by a current magnetic field of the order of nT. In this way, this embodiment can improve the detection accuracy of the detection target.

[0058] In this embodiment, the NV center 112 formed on the surface 111b of the diamond crystal 111 can be brought close to or in close contact with the detection target. According to this embodiment, even very weak currents such as leaks can be detected.

[0059] In this embodiment, the detection substrate 11 is scanned with fluorescence and excitation light by the light-emitting element 21 and the light-receiving element 22 of the detection device 1. According to this embodiment, it is possible to detect changes in the direction or magnitude of the magnetic field generated in the detection target, and the spatial distribution of the current vector detected by the current magnetic field. According to this embodiment, it is possible to easily identify the path of the complex current magnetic field, in other words, the current path, etc.

[0060] In this embodiment, the dielectric substrate 13 is formed in a cylindrical shape to accommodate the detection substrate 11. According to this embodiment, the detector 10 is made into a unit, which makes it easy to handle.

[0061] In this embodiment, an exposed portion 111c is exposed on the surface 111a of the diamond crystal 111. According to this embodiment, the light emitting element 21 and the light receiving element 22 can input and output fluorescence and excitation light from the exposed portion 111c to the surface 111a of the diamond crystal 111 of the detection substrate 11 of the detector 10.

[0062] In this embodiment, face 111b of diamond crystal 111 is a smooth surface. According to this embodiment, face 111b of diamond crystal 111 can be brought into close contact with or close to the surface of the detection target at a level of several μm or less while remaining parallel to the surface. According to this embodiment, it is possible to detect changes in the direction or magnitude of a magnetic field of about several μm, and the spatial distribution of a current vector detected by a current magnetic field of the order of nT.

[0063] In this embodiment, an optical window 14 is provided which is housed in a dielectric substrate 13 and is disposed opposite the detection substrate 11. According to this embodiment, the detection substrate 11 can be protected from dust and the like.

[0064] [Second embodiment] Fig. 6 is a cross-sectional view illustrating an outline of a detection board of a detector according to a second embodiment. Fig. 7 is a schematic diagram illustrating an example of a detector and a detection device according to a second embodiment. Fig. 8 is a schematic diagram illustrating an example of a detection board. In the second embodiment, the same components as in the first embodiment are denoted by the same reference numerals and descriptions thereof will be omitted.

[0065] The diamond crystal 111 has a side length d11 of, for example, 1 mm, and a thickness d12 of, for example, 200 μm.

[0066] The surface 111a is brought into contact with a contact portion 134 of the dielectric substrate 13, which will be described later.

[0067] FIG. 9 is a plan view illustrating an example of an antenna conductor. The antenna conductor 113 transmits microwaves to be irradiated to the NV centers 112 of the diamond crystal 111. The antenna conductor 113 is located on the surface 111a of the diamond crystal 111 opposite to the surface 111b on which the NV centers 112 are formed. The antenna conductor 113 is interposed between the solder 15 and the surface 111a of the diamond crystal 111. The antenna conductor 113 is provided on the outer periphery of the surface 111a of the diamond crystal 111. The antenna conductor 113 is formed in a ring shape when viewed in the normal direction of the surface 111a (hereinafter referred to as "plan view"). The antenna conductor 113 is a loop antenna formed of a conductive thin film. The antenna conductor 113 is formed in a ring shape with a portion open. An end of the antenna conductor 113 is connected to a pad conductor 1142 of the high-frequency line conductor 114. The loop diameter of the antenna conductor 113 is approximately several mm.

[0068] The antenna conductor 113 is a small loop antenna. The frequency of the antenna conductor 113 is, for example, 2.8 GHz or more and 2.9 GHz or less. The input power of the antenna conductor 113 is, for example, −20 dBm.

[0069] The high-frequency line conductor 114 is formed on the face 111a of the diamond crystal 111. The high-frequency line conductor 114 has a center conductor and a ground conductor spaced a certain distance from it. The impedance is adjusted by the distance between the center conductor and the ground conductor. The center conductor and ground conductor are connected by soldering to the center conductor and ground conductor of the high-frequency line conductor (not shown) of the dielectric substrate 13. As shown in Figures 9 to 11, the high-frequency line conductor 114 may not require a ground conductor, and the antenna conductor 113 may be connected directly to the pad conductors 1141 and 1142. It is preferable that the line connecting them constitutes the high-frequency line conductor 114 and be as short as possible.

[0070] The pad conductor 1141 is connected to the surface electrode 23 via a wiring 1143. The pad conductor 1141 is made of, for example, gold. The pad conductor 1141 has a film thickness of, for example, 200 nm or more and 1000 nm or less.

[0071] An end of the antenna conductor 113 is connected to the pad conductor 1142. The pad conductor 1142 is made of, for example, gold. The pad conductor 1142 has a film thickness of, for example, 200 nm or more and 1000 nm or less.

[0072] The oscillation element 31 is electrically connected to the wiring on the dielectric base 13. The oscillation element 31 is in contact with the dielectric base 13. The oscillation element 31 is located on the surface 111a of the diamond crystal 111 opposite to the surface 11b on which the NV center 112 is formed. The oscillation element 31 is accommodated in the third accommodation portion 135 of the dielectric base 13. The oscillation element 31 may be connected to the ground conductor of the dielectric base 13 by wire bonding or solder ball connection. The oscillation element 31 is electrically connected to the antenna conductor 113 of the detection board 11 at the abutment portion 134 of the dielectric base 13.

[0073] The dielectric substrate 13 is electrically connected to the detection substrate 11 via solder, including the high-frequency line conductor (not shown) of the dielectric substrate 13, the high-frequency line conductor 114 arranged on the surface 111a of the diamond crystal 111, and the antenna conductor 113.

[0074] The dielectric base 13 has a first housing portion 131, a second housing portion 132, and a third housing portion 135. The first housing portion 131 and the second housing portion 132 are continuous in the axial direction. The first housing portion 131 and the second housing portion 132 penetrate the dielectric base 13 from the surface 13a to the surface 13b. The opening width of the first housing portion 131 is wider than the opening width of the second housing portion 132. The boundary between the first housing portion 131 and the second housing portion 132 has an abutting portion 134 with a narrow opening width.

[0075] The first housing portion 131 is arranged on one side in the axial direction of the dielectric base 13. The light emitting element 21 and the light receiving element 22 are arranged in the first housing portion 131. The second housing portion 132 is a support portion that supports the detection board 11. The second housing portion 132 is arranged on the other side in the axial direction of the dielectric base 13. The detection board 11 is arranged in the center of the second housing portion 132 of the dielectric base 13.

[0076] The third housing portion 135 is formed in a concave shape on the surface 13a of the dielectric base 13. In the third housing portion 135, the oscillation element 31 is disposed.

[0077] The insides may be airtightly sealed by providing lids on the first housing portion 131, the second housing portion 132, and the third housing portion 135. The dielectric base 13 may be provided with lead terminals or ball terminals.

[0078] Although FIG. 7 shows a configuration in which the surface 111b protrudes in the axial direction from the surface 13b of the dielectric substrate 13, the surface 111b and the surface 13b of the dielectric substrate 13 may be flat.

[0079] The solder is provided on the contact portion 134 of the dielectric base 13. The solder is provided in a ring shape in a plan view. The solder is electrically connected to the high-frequency line conductor 114 of the detection board 11, the antenna conductor 113, and the interior pattern of the dielectric base 13.

[0080] (Detection device) The light-emitting element 21 and the light-receiving element 22 are arranged inside the ring-shaped antenna conductor 113. The light-emitting portion and the light-incident portion are arranged facing the surface 111a. The light-emitting element 21 and the light-receiving element 22 are arranged in close contact with the exposed portion 111c of the surface 111a of the diamond crystal 111, as shown in FIG. 7, for example. In this case, power is supplied to the light-emitting element 21 and the light-receiving element 22 from a pad conductor 1141 and a wiring 1143 formed independently of the dielectric base 13. The light-emitting element 21 and the light-receiving element 22 may be connected to the ground conductor of the dielectric base 13 by wire bonding or solder ball connection.

[0081] The light-emitting element 21 and the light-receiving element 22 may be disposed, for example, directly above the exposed portion 111c of the surface 111a of the diamond crystal 111, spaced a certain distance apart. In this case, optical components such as lenses, filters, isolators, mirrors, and anti-reflection films may be used between the light-emitting element 21 and the light-receiving element 22 and the NV center 112.

[0082] The light emitting element 21 and the light receiving element 22 have a side length d13 of, for example, 300 μm, and a thickness d14 of, for example, 100 μm.

[0083] The surface electrodes 23 are disposed on the surface 21b, which is the lower surface of the light-emitting element 21, and on the surface 22b, which is the lower surface of the light-receiving element 22. The surface electrodes 23 are connected to the ground conductor of the dielectric substrate 13 by wire bonding.

[0084] The back electrode 24 is disposed on the surface 21a which is the upper surface of the light emitting element 21 and on the surface 22a which is the upper surface of the light receiving element 22. The back electrode 24 is connected to the ground conductor of the dielectric base 13 by wire bonding.

[0085] The upper surface of the light-emitting element 21 and the upper surface of the light-receiving element 22 are the surfaces of the light-emitting element 21 and the light-receiving element 22 opposite to the diamond crystal 111. The lower surface of the light-emitting element 21 and the lower surface of the light-receiving element 22 are the surfaces of the light-emitting element 21 and the light-receiving element 22 facing the diamond crystal 111. The surfaces of the light-emitting element 21 and the light-receiving element 22 on the light input / output side face the NV center 112.

[0086] When the light-emitting element 21 is a diode such as an LED or an LD, the front surface electrode 23 and the back surface electrode 24 function as an anode electrode or a cathode electrode, respectively. Either the front surface electrode 23 or the back surface electrode 24 may be an anode electrode or a cathode electrode. When the light-receiving element 22 is a diode such as a PD, the front surface electrode 23 and the back surface electrode 24 function as an anode electrode or a cathode electrode, respectively. Either the front surface electrode 23 or the back surface electrode 24 may be an anode electrode or a cathode electrode. The front surface electrode 23 of the light-emitting element 21 is connected to a pad conductor 1141 via a wiring 1143. The front surface electrode 23 of the light-receiving element 22 is connected to the pad conductor 1141 via a wiring 1143. The pad conductor 1141 and the back surface electrode 24 are electrically connected to a semiconductor element in which a signal control unit 200 (see FIG. 5) is formed.

[0087] (Detection method) The surface 100a of the dielectric 100 is placed close to or in close contact with the surface 111b of the diamond crystal 111, which is the magnetic field acting surface of the detection substrate 11 of the detection device 1. As shown in FIG. 5 , microwaves generated by the oscillation element 31, which is the microwave source, propagate to the antenna conductor 113 of the detection substrate 11 through a high-frequency transmission line (not shown) provided inside the dielectric substrate 13. The microwaves are then radiated from the antenna conductor 113. The radiated microwaves then act on the NV centers 112, causing electron spin resonance. A spatial change in the direction or magnitude of the magnetic field generated in the dielectric 100 acts on the NV centers 112 located near the surface 111b of the diamond crystal 111 of the detection substrate 11 of the detection device 1.

[0088] Then, the detection substrate 11 is scanned with fluorescence and excitation light by the light-emitting element 21 and light-receiving element 22 of the detection device 1. More specifically, the green excitation light from the light-emitting element 21 is incident on the surface 111b, which is the front surface, from the exposed portion 111c of the surface 111a, which is the back surface of the diamond crystal 111. The green excitation light incident on the surface 111b side then diffuses widely within the surface 111b of the diamond crystal 111, irradiating and exciting the NV centers 112. As a result, the NV centers 112 are irradiated and excited from the exposed portion 111c of the surface 111a of the diamond crystal 111 of the detection substrate 11.

[0089] The excited NV centers 112 then emit red fluorescence, which enters from face 111b, which is the front surface of diamond crystal 111, to exposed portion 111c of face 111a, which is the back surface. The fluorescence then diffuses within face 111a of diamond crystal 111 and enters the light-receiving surface of light-receiving element 22. Light-emitting element 21 and light-receiving element 22 receive, as fluorescence, an electron spin resonance signal of NV centers 112 excited by the excitation light from exposed portion 111c of face 111a of diamond crystal 111. Light-emitting element 21 and light-receiving element 22 receive a fluorescence signal corresponding to a change in the direction or magnitude of the magnetic field.

[0090] The magnetic field to be measured acts on the NV center 112, changing the electron spin resonance frequency. The intensity of the red fluorescence changes in response to the change in the electron spin resonance frequency. The detection device 1 then reads this to detect the magnitude of the magnetic field. The detection device 1 also operates as a current sensor by measuring the magnetic field caused by a current.

[0091] (Application of the detection device) One example of an application of the detection device 1 shown in Fig. 7 is a device for measuring the charge / discharge current of a battery. In this case, a semiconductor element formed with a signal control unit and a semiconductor element formed with a microwave source are configured as an integrated module with diamond crystal 111. In Fig. 7, only the semiconductor element formed with the microwave source is shown as oscillation element 31, but a semiconductor element formed with a signal control unit may also be provided separately.

[0092] (effect) As described above, in this embodiment, the detection device 1 is formed by integrating the detector 10, the light-emitting element 21, and the light-receiving element 22. In this embodiment, the oscillation element 31 is electrically connected to the wiring on the dielectric substrate 13. In this embodiment, a magnetic sensor using a diamond crystal can be configured to be small, simple, and robust. According to this embodiment, diamond crystal has no hysteresis and has good linearity in magnetic field measurement, so current accumulation can be detected with high accuracy. In this embodiment, for example, errors are not accumulated when a secondary battery is repeatedly charged and discharged, and the charge amount of a storage battery can be accurately grasped and predicted. This embodiment can be suitably used, for example, in storage battery systems and inverter systems for electric vehicles.

[0093] In this embodiment, the oscillation element 31 is in contact with the dielectric substrate 13. According to this embodiment, the magnetic sensor using diamond crystal can be miniaturized.

[0094] In this embodiment, the oscillation element 31 is located on the surface 111a of the diamond crystal 111 opposite to the surface 11b on which the NV center 112 is formed, and is not located on the side of the surface 111b of the diamond crystal 111 which is the magnetic field application surface of the detection substrate 11 of the detection device 1. According to this embodiment, the surface 111b of the diamond crystal 111 of the detection device 1 can be brought close to or in close contact with the detection target.

[0095] In this embodiment, the surface 111b of the diamond crystal 111, which is the magnetic field acting surface of the detection substrate 11 of the detection device 1, protrudes from the surface 13b of the dielectric substrate 13. According to this embodiment, the surface 111b of the diamond crystal 111 of the detection device 1 can be brought close to or in close contact with the detection target. As a result, this embodiment can detect changes in the direction or magnitude of a magnetic field of about several μm, which were previously difficult to detect, and current vectors detected by current magnetic fields of the order of nT. In this way, this embodiment can improve the detection accuracy of the detection target.

[0096] (Variation 1) Fig. 10 is a plan view illustrating another example of an antenna conductor. The antenna conductor 113 shown in Fig. 10 is formed in the shape of a rectangular frame with one side open. A light emitting element 21 and a light receiving element 22 are arranged inside the antenna conductor 113.

[0097] (Variation 2) FIG. 11 is a plan view illustrating another example of an antenna conductor. The antenna conductor 113 shown in FIG. 11 is formed in a rectangular frame shape. A comb portion 115 is provided in a part of the antenna conductor 113. The comb portion 115 includes a comb portion 1151 having teeth extending from one side of the rectangular antenna conductor 113 to the opposite side, and a comb portion 1152 having teeth extending from the opposite side to the other side. The comb portion 115 is a so-called IDT (Inter Digital Transducer) and forms a capacitance-forming portion. The comb portions 1151 and 1152 form a capacitance. The comb portions 1151 and 1152 can suppress reflection of microwaves of a specific frequency incident on the antenna conductor 113 by adjusting the line and space and number of pairs of the electrodes. By providing the comb portion 115, even if the antenna conductor 113 is very small, it can effectively radiate microwaves of about 3 GHz, making it suitable for detecting microcircuits. In this way, the antenna conductor 113, which is a radiator, has a first side having a first comb portion 1151 and a second side having a second comb portion 1152. The first comb portion 1151 and the second comb portion 1152 are arranged to interdigitate with each other to form a capacitance forming portion. FIG. 12 is a graph illustrating an example of the reflection characteristics of the antenna conductor 113. FIG. 12 shows the S 11 This is an example of reflection characteristics. 11 According to the reflection characteristics, it is found that the reflection of microwaves in the range of 2.7 to 2.9 GHz from the antenna conductor 113 is suppressed, and microwaves in the range of 2.7 to 2.9 GHz are effectively radiated from the antenna conductor 113.

[0098] In the above, a member or fluid with high relative magnetic permeability may be inserted between the detection substrate 11 of the detection device 1 and the detection target, thereby further improving the detection accuracy.

[0099] In the above, a member or fluid with high relative magnetic permeability may be inserted into a space located on the optical path of the fluorescence and excitation light inside the detector 10. This can further improve the detection accuracy.

[0100] (Other variations) In the above, a member or fluid with high relative magnetic permeability may be inserted between the detection substrate 11 of the detection device 1 and the detection target, thereby further improving the detection accuracy.

[0101] In the above, a member or fluid with high relative magnetic permeability may be inserted into a space located on the optical path of the fluorescence and excitation light inside the detector 10. This can further improve the detection accuracy.

[0102] Instead of the dielectric substrate 13, a high frequency microwave signal may be input to the antenna conductor 113 via a fiber or the like.

[0103] An insulating film may be formed on the antenna conductor 113, and another antenna conductor 113 may be laminated on top of that. In this case, it is possible to operate at multiple frequencies, which makes it easy to measure electron spin resonance points at multiple points.

[0104] In the above description, the NV center 112 is formed on one surface 111b of the diamond crystal 111, and the antenna conductor 113 is formed on the opposite surface 111a, but this is not limiting. The NV center 112 and the antenna conductor 113 may be arranged on the surface 111a, or the NV center 112 and the antenna conductor 113 may be arranged on the surface 111b.

[0105] The antenna conductor 113 may be configured as follows: The antenna conductor 113 is disposed on one surface of a separate substrate separate from the diamond crystal 111. One surface of the separate substrate is then placed in close contact with the surface of the diamond crystal 111. The antenna conductor 113 thus disposed is also included in the radiator provided in the diamond crystal 111. The separate substrate is preferably, for example, a glass plate that is transparent to excitation light and fluorescence. A separate substrate made of a glass plate is placed on the surface 111a of the diamond crystal 111. If the light-emitting element 21 and the light-receiving element 22 are then further placed thereon, light can be input and output through the separate substrate. The separate substrate may also be, for example, a non-transparent substrate other than a glass plate. In this case, the separate substrate, which is a non-transparent substrate, is placed on the surface 111a of the diamond crystal. Light can then be input and output to and from the light-emitting element 21 and the light-receiving element 22 from below the diamond crystal 111.

[0106] The embodiments disclosed in the present application can be modified without departing from the spirit and scope of the invention. Furthermore, the embodiments disclosed in the present application and their modifications can be combined as appropriate.

[0107] Although specific embodiments have been described to fully and clearly disclose the claimed technology, the appended claims should not be limited to the above-described embodiments, but should be construed to embody all modifications and alternative arrangements that may be made by those skilled in the art within the scope of the basic concept presented herein. [Explanation of symbols]

[0108] 1. Detection device 10 Detector 11 Detection board 111 Diamond Crystal 111a, 111b side 112 NV Center 113 Antenna conductor (radiator) 13 Dielectric substrate 13a, 13b side 131 First Storage Unit 132 Second storage section 133 Tsuba 14 Optical window 14a, 14b side 15 Solder 16 Interior Pattern 17 RF vias 18 Bonding Pads 21 Light-emitting element 22 Photodetector 31 Oscillator (microwave source) 100 Dielectric 101, 102, 103, 104 conductors 200 Signal control section 201 Control Unit 202 Signal Processing Unit F1, F2, F3, F4 magnetic fields I1, I2, I3, I4 current

Claims

1. a diamond crystal in which an NV center is formed; a loop antenna provided on the diamond crystal; a dielectric substrate; Equipped with the NV center is located on one face of the diamond crystal; the dielectric substrate is cylindrical and has an axially open end on the detection target side and an axially open end on the opposite side from the detection target side, an outer periphery of the diamond crystal is located outside the inner periphery of the dielectric substrate and inside the outer periphery of the dielectric substrate when viewed in the axial direction; the loop antenna is disposed on a surface of the diamond crystal opposite to a surface on which the NV center is formed, and is electrically connected to a high-frequency transmission line formed on the dielectric substrate. Detector.

2. The loop antenna has a first side having a first comb portion and a second side having a second comb portion, and the first comb portion and the second comb portion are arranged to mesh with each other to form a capacitance forming portion.

2. The detector of claim 1.

3. the cylindrical end of the dielectric substrate facing the detection target is located on the opposite side of the surface of the diamond crystal facing the detection target; 3. A detector according to claim 1 or 2.

4. The loop antenna is formed in a ring shape, a surface of the diamond crystal opposite to the surface on which the NV center is formed, where a portion on which the loop antenna is not disposed is exposed; 3. A detector according to claim 1 or 2.

5. The surface of the diamond crystal on which the NV center is formed is a smooth surface.

3. A detector according to claim 1 or 2.

6. A detection device comprising the detector according to claim 1 or 2, a light-emitting element, and a light-receiving element, the light emitting element irradiates light onto the NV center; the light receiving element receives the fluorescence from the NV center; Detection device.

7. the light-emitting element and the light-receiving element are disposed in close contact with a portion of the surface of the diamond crystal opposite to the surface on which the NV center is formed, where the loop antenna is not disposed; The detection device according to claim 6.

8. the light-emitting element and the light-receiving element are disposed at a certain distance from each other directly above a portion of the diamond crystal on the side opposite to the side on which the NV center is formed, where the loop antenna is not disposed. The detection device according to claim 6.

9. The detector is housed in the dielectric substrate and has an optical window disposed opposite the detector substrate. Equipped with the optical window is located within an opening at the opposite axial end of the dielectric substrate; The detection device according to claim 8.

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