JP2022070810A - Electrode structure and light detection element - Google Patents

Abstract

To provide an electrode structure and a light detection element which can sufficiently extract an electric signal from an element while sufficiently transmitting a light signal to the element.SOLUTION: A light detection element 1 comprises: a first electrode 10A; a second electrode 20; and a magnetic element 30 disposed between the first electrode and the second electrode. The first electrode 10A has: a metal film 11A; an opening 12A provided on a portion of the metal film 11A; and a transparent conductive film 13A disposed on the opening 12A. The transparent conductive film 13A is electrically connected to the magnetic element 30, and it is disposed so as to overlap the magnetic element 30 in plan view from the thickness direction of the transparent conductive film 13A.SELECTED DRAWING: Figure 3B

Description

The present invention relates to an electrode structure and a photodetector having the electrode structure.

With the spread of the Internet, the amount of communication has increased dramatically, and the importance of optical communication has become extremely high. Optical communication is a communication means that converts an electric signal into an optical signal and transmits / receives using the optical signal.

For example, Patent Document 1 describes a receiving device that receives an optical signal using a photodiode. The photodiode is, for example, a pn junction diode using a pn junction of a semiconductor.

Japanese Unexamined Patent Publication No. 2001-292107

With the development of information and communication technology, further speeding up of communication speed is required. Examples of high-speed communication include optical communication using far-infrared light used in a long-distance network and optical communication using visible light used between terminals. However, when visible light is used for high-speed optical communication, there is a problem that the reception sensitivity of a Si semiconductor photodiode significantly decreases when the frequency becomes several tens of GHz or more. On the other hand, the inventor has found that if a magnetic element having a spacer layer between two ferromagnetic layers is used, it can respond to a high-frequency optical signal and can be used as a receiving element for a high-frequency optical signal. In order to utilize such a magnetic element as an optical signal receiving element, a new structure capable of efficiently transmitting an optical signal to the element and efficiently extracting an electric signal from the element is required.

The present invention has been made in view of the above problems, and an electrode structure capable of efficiently transmitting an optical signal to an element and efficiently extracting an electric signal from the element and a photodetector element having the electrode structure are provided. The purpose is to provide.

The following means are provided to solve the above problems.

(1) The electrode structure according to the first aspect has a metal film, an opening provided in a part of the metal film, and a transparent conductive film arranged in the opening, and is transparent. The conductive film is electrically connected to the element and overlaps with the element in a plan view from the thickness direction of the transparent conductive film.

(2) In the above aspect, the element may be provided so as to include the element in a plan view from the thickness direction.

(3) In the above aspect, the length of the opening may be smaller than the wavelength of the light applied to the transparent conductive film.

(4) The light detection element according to the second aspect is the first electrode, the second electrode, the first ferromagnetic layer, the second ferromagnetic layer, the first ferromagnetic layer, and the second ferromagnetic layer. It comprises a spacer layer sandwiched between the first electrode and a magnetic element arranged between the first electrode and the second electrode, wherein the first electrode is a metal film and a metal film. It has an opening provided in a part thereof and a transparent conductive film arranged in the opening, and the transparent conductive film is electrically connected to the magnetic element to form a transparent conductive film. It overlaps with the magnetic element in a plan view from the thickness direction, and the transparent conductive film is irradiated with light.

(5) In the above aspect, the opening may be provided so as to include the magnetic element in a plan view from the thickness direction.

(6) In the above aspect, the length of the opening may be smaller than the wavelength of the light applied to the transparent conductive film.

(7) In the above embodiment, the light detection element further includes a light transmission unit that irradiates the transparent conductive film with light, and the light transmission unit is provided at one end of the light transmission unit and is provided with light from the outside. A first diffraction grating portion to be irradiated with light, a second diffraction grating portion provided at the other end of the light transmission portion and emitting light transmitted from the first diffraction grating portion, and the first diffraction grating portion. It has a waveguide provided between the second diffraction grating portion and the second diffraction grating portion, and the area of the first diffraction grating portion is larger than the area of the second diffraction grating portion in the plan view of the light transmission portion. It may be wide.

(8) In the above embodiment, the plurality of tunnel magnetic elements are provided in an array, and the opening thereof includes the plurality of magnetic elements in a plan view from the thickness direction of the transparent conductive film. It may be provided in.

According to the present invention, it is possible to provide an electrode structure and an optical detection element capable of efficiently transmitting an optical signal to an element and efficiently extracting an electric signal from the element.

FIG. 1 is a perspective view schematically showing a configuration of a photodetector element according to an embodiment of the present invention. FIG. 2 is a plan view showing the configuration of the light transmission unit in FIG. FIG. 3A is an enlarged perspective view of the photodetector element of FIG. FIG. 3B is a cross-sectional view taken along the line I-I of FIG. 3A. FIG. 4 is a cross-sectional view showing the configuration of a magnetic element provided in the photodetector element of FIG. FIG. 5A is a plan view showing the configuration of the first electrode in FIG. 1. FIG. 5B is a plan view showing a modified example of the first electrode of FIG. 5A. FIG. 6A is a diagram illustrating an example of the length of the opening in the present invention. FIG. 6A is a diagram illustrating another example of the length of the opening in the present invention. FIG. 7 is a plan view showing a modified example of the first electrode of FIG. 5B. FIG. 8 is a diagram showing an example of a communication system using the photodetector element of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings used in the following description, the featured portion may be enlarged for convenience in order to make the feature easy to understand, and the dimensional ratio of each component may be different from the actual one. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the present invention are exhibited.

Define the direction. The stacking direction of the light detection element 1 (stacking direction of the magnetic elements 30) is defined as the z direction, one direction in the plane orthogonal to the z direction is defined as the x direction, and the x direction and the direction orthogonal to the z direction are defined as the y direction. The z direction is an example of the stacking direction. Hereinafter, the + z direction may be expressed as “up” and the −z direction may be expressed as “down”. The + z direction is a direction from the first electrode to the second electrode, which will be described later. The top and bottom do not always match the direction in which gravity is applied.

FIG. 1 is a perspective view schematically showing a configuration of a photodetector element according to an embodiment of the present invention.
As shown in FIG. 1, the photodetection element 1 includes a first electrode 10A and a second electrode 20, and a magnetic element 30 arranged between the first electrode and the second electrode. The magnetic element 30 will be described later. Further, the photodetector element 1 further includes a light transmission unit 40 that irradiates a transparent conductive film described later provided on the first electrode 10A with light. The first electrode 10A and the second electrode 20 are electrically connected to the constant current drive circuit 51 and the signal processing circuit 52, respectively.
The light in the present invention is used to include not only visible light but also infrared rays having a wavelength longer than that of visible light and ultraviolet rays having a wavelength shorter than that of visible light.

FIG. 2 is a plan view showing the configuration of the light transmission unit 40 in FIG. As shown in FIG. 2, the light transmission unit 40 is provided at one end 40a of the light transmission unit 40, and is provided at the first diffraction grating unit 41 to which light from the outside is irradiated and the other end 40b of the light transmission unit. It has a second diffraction grating section 42 from which light transmitted from the first diffraction grating section 41 is emitted, and a waveguide 43 provided between the first diffraction grating section 41 and the second diffraction grating section 42. The shape of the light transmission unit 40 is not particularly limited, but is composed of, for example, a long plate-like body. The light transmission unit 40 has a core through which light propagates and a clad arranged on the outside so as to cover the core. The core is composed of, for example, tantalum oxide (Ta2O5). The clad is made of, for example, silicon oxide (SiOx, x = 1-2) or aluminum oxide (Ai2O3).

The first diffraction grating unit 41 is provided on one main surface 41a of the light transmission unit 40, and has a plurality of grooves 41B extending in the y direction of the light transmission unit 40. In the present embodiment, the x direction is the longitudinal direction of the light transmitting unit 40, the y direction is the width direction (lateral direction) of the light transmitting unit 40, and the plurality of grooves 41B extend along the width direction of the light transmitting unit 40. are doing.

The second diffraction grating portion 42 is provided on the other main surface 41b of the light transmission portion 40, and has a plurality of grooves 42B extending in the y direction of the light transmission portion 40. In this embodiment, a plurality of grooves 42B extend along the width direction of the light transmitting portion 40.

In the plan view of the light transmission unit 40, the area of the first diffraction grating unit 41 is preferably larger than the area of the second diffraction grating unit 42. The plan-viewing shapes of the first diffraction grating portion 41 and the second diffraction grating portion 42 are not particularly limited, but are, for example, substantially rectangular shapes. The dimensions and cross-sectional shape of the groove 41B constituting the first diffraction grating portion 41 are preferably the same as the dimensions and cross-sectional shape of the groove 42B constituting the second diffraction grating portion 42, but may be different.

The waveguide 43 transmits the light incident on the first diffraction grating section 41 to the second diffraction grating section 42. In the present embodiment, the waveguide 43 has a tapered shape, and the y-direction dimension (width-direction dimension) of the waveguide 43 gradually decreases from the first diffraction grating portion 41 toward the second diffraction grating portion 42. There is. By making the cross-sectional area of the waveguide 43 along the y direction smaller from the first diffraction grating portion 41 toward the second diffraction grating portion 42, the spot diameter of the light ray S2 emitted from the second diffraction grating portion 42 However, it is smaller than the spot diameter of the light ray S1 incident on the first diffraction grating portion 41. The spot diameter of the light ray S1 is, for example, 1 μm or more and 2 μm or less. The spot diameter of the optical signal S2 is about the wavelength of the optical signal. For example, when light (light rays) having a wavelength of 500 nm is irradiated to the first diffraction grating portion 41 with a spot diameter of 1 μm or more and 2 μm or less, light (light rays) having a spot diameter of, for example, 500 nm is emitted from the second diffraction grating portion by the waveguide 43. Emit from. In this way, the light ray S1 having a relatively large spot diameter on the order of several microns is received by the first diffraction grating unit 41 and transmitted through the waveguide 43, so that the light ray S2 having a spot diameter as small as the wavelength of the light is received by the second diffraction grating. It can be emitted from the unit 42.

In the present embodiment, the widthwise end surface 43A of the waveguide 43 has a linear shape in a plan view, but the present invention is not limited to this, and the widthwise dimension of the end portion 43b on the second diffraction grating portion 42 side is the waveguide. It suffices to have a shape smaller than the widthwise dimension of the end portion 43a on the first diffraction grating portion 41 side of the 43. For example, the widthwise end surface 43A of the waveguide 43 may have a curved shape or a stepped shape in a plan view.
Further, in the waveguide 43, the cross-sectional area along the y-direction is substantially the same as that of the first portion where the cross-sectional area along the y-direction decreases from the first diffraction grating portion 41 toward the second diffraction grating portion 42. It may have a site.

3A is an enlarged perspective view of the photodetector element 1 of FIG. 1, and FIG. 3B is a cross-sectional view taken along the line I-I of FIG. 3A.
As shown in FIGS. 3A and 3B, the first electrode 10A comprises a metal film 11A, an opening 12A provided in a part of the metal film 11A, and a transparent conductive film 13A arranged in the opening 12A. Have. The transparent conductive film 13A is electrically connected to the magnetic element 30 (element) and is arranged so as to overlap the magnetic element 30 in a plan view from the thickness direction (z direction) of the transparent conductive film 13A. The transparent conductive film 13A has main surfaces 13a and 13b facing each other in the thickness direction. In the example shown in FIGS. 3A and 3B, a part of one main surface 13a of the transparent conductive film 13A is in contact with at least a part of the z-direction (stacking direction) end surface 30a of the magnetic element 30. When the other main surface 13b of the transparent conductive film 13A is irradiated with light, the light transmitted through the transparent conductive film 13A is irradiated to the magnetic element 30. The first electrode 10A may have a thin film having electrical conductivity and transmitting light between the transparent conductive film 13A and the magnetic element 30.

The shape of the first electrode 10A is not particularly limited, but is composed of, for example, a long plate-like body extending in the x direction. The thickness (dimension in the z direction) of the metal film 11A is, for example, 50 nm or more and 100 nm or less. The metal film 11A is made of a metal such as copper, silver, or gold.

The opening 12A is provided at the end portion 10a in the longitudinal direction of the first electrode 10A, and has a substantially rectangular shape in a plan view from, for example, the z direction. The opening 12A is formed so as to penetrate the metal film along the z direction.

The transparent conductive film 13A is provided substantially parallel to the metal film 11A so as to close the entire opening 12A. In the present embodiment, the transparent conductive film 13A has a substantially rectangular shape in a plan view like the opening 12A. The thickness of the transparent conductive film 13A may be the same as or smaller than the thickness of the metal film, and is, for example, 25 nm to 100 nm. The transparent conductive film 13A has transparency to light in the wavelength range used by the light beam S1. The wavelength range of the light used for the light ray S1 is, for example, 300 nm or more and 2000 nm or less, and includes a visible light range. The transparent conductive film 13A is made of a non-metal substance, for example, an oxide. The transparent conductive film 13A is composed of one or more selected from, for example, indium tin oxide (ITO), zinc oxide (IZO), zinc oxide (ZnO), and zinc indium gallium oxide (IGZO). The electrical resistivity of the transparent conductive film 13A is larger than the electrical resistivity of the metal film, but since the transparent conductive film 13A is arranged in the opening 12A provided in a part of the metal film, the whole is transparent conductive. The resistance of the first electrode 10A can be reduced as compared with the case of being composed of a film. Therefore, according to the electrode structure of the first electrode 10A, the electric signal from the magnetic element 30 can be efficiently taken out while efficiently transmitting the light ray S1 to the magnetic element 30.

The shape of the second electrode 20 is not particularly limited, but is composed of, for example, a long plate-like body extending in the y direction. The thickness (dimension in the z direction) of the second electrode 20 is, for example, 20 nm to 80 nm. The second electrode 20 is composed of, for example, a laminated film of Ta, Cu and Ta, a laminated film of Ta, Cu and Ti, and a laminated film of Ta, Cu and TaN.

FIG. 4 is a cross-sectional view showing the configuration of the magnetic element 30 provided in the photodetector element 1 of FIG.
As shown in FIG. 4, the magnetic element 30 has at least a first ferromagnetic layer 31, a second ferromagnetic layer 32, and a spacer layer 33. The spacer layer 33 is located between the first ferromagnetic layer 31 and the second ferromagnetic layer 32, and is sandwiched between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. Further, the magnetic element 30 has a base layer 34 located between the second ferromagnetic layer 32 and the second electrode 20. As used herein, ferromagnetism includes ferrimagnetism.
In addition to the above-mentioned layer, the magnetic element 30 may have another ferromagnetic layer, a magnetic coupling layer, a perpendicular magnetization-inducing layer, a cap layer, a side wall insulating layer, and the like.

The magnetic element 30 is, for example, an MTJ (Magnetic Tunnel Junction) element in which the spacer layer 33 is made of an insulating material. In this case, the magnetic element 30 applies a resistance value in the z direction (current in the z direction) according to a relative change between the magnetization state of the first ferromagnetic layer 31 and the magnetization state of the second ferromagnetic layer 32. It is an element whose resistance value when flowing) changes. Such an element is also called a magnetoresistive effect element. For example, the magnetic element 30 causes a resistance value in the z direction (a current flows in the z direction) according to a change in the relative angle between the magnetization direction of the first ferromagnetic layer 31 and the magnetization direction of the second ferromagnetic layer 32. (Resistance value when this is done) changes. Further, for example, in the magnetic element 30, the resistance value in the z direction (the resistance value when a current is passed in the z direction) changes according to the change in the magnitude of the magnetization of the first ferromagnetic layer 31. The total thickness of the magnetic element 30 is, for example, 15 nm to 40 nm.

The first ferromagnetic layer 31 is a photodetection layer in which the state of magnetization (for example, the direction of magnetization or the magnitude of magnetization) changes when light is irradiated from the outside. The first ferromagnetic layer 31 is also called a magnetization free layer. The magnetization free layer is a layer containing a magnetic material whose magnetization state (for example, the direction of magnetization or the magnitude of magnetization) changes when a predetermined external force is applied. The predetermined external force is, for example, light emitted from the outside, a current flowing in the z direction of the magnetic element 30, or an external magnetic field.

The first ferromagnetic layer 31 contains a ferromagnet. The first ferromagnetic layer 31 contains, for example, a magnetic element such as Co, Fe, and Ni. The first ferromagnetic layer 31 may contain non-magnetic elements such as B, Mg, Hf, and Gd together with the magnetic elements. Further, the first ferromagnetic layer 31 may be, for example, an alloy containing a magnetic element and a non-magnetic element. The first ferromagnetic layer 31 may be composed of a plurality of layers. In that case, the first ferromagnetic layer 31 is, for example, a CoFeB alloy, a laminate in which a CoFeB alloy layer is sandwiched between Fe layers, and a laminate in which a CoFeB alloy layer is sandwiched between CoFe layers.

The first ferromagnetic layer 31 is a perpendicular magnetization having an easy magnetization axis in the direct direction (z direction) of the film surface even if the in-plane magnetized film has an easy magnetization axis in the in-plane direction (any direction in the xy plane). It may be a membrane.

The film thickness of the first ferromagnetic layer 31 is, for example, 1 nm or more and 5 nm or less, preferably 1 nm or more and 2 nm or less. When the first ferromagnetic layer 31 is a vertical magnetization film, if the thickness of the first ferromagnetic layer 31 is thin, the vertical magnetic anisotropy of the first ferromagnetic layer 31 increases. When the film thickness of the first ferromagnetic layer 31 is thicker than 2 nm, an insertion layer made of, for example, Mo and W may be provided in the first ferromagnetic layer 31. That is, the first ferromagnetic layer 31 may be a laminate in which the ferromagnetic layer, the insertion layer, and the ferromagnetic layer are laminated in order in the z direction. The interfacial magnetic anisotropy at the interface between the insertion layer and the ferromagnetic layer enhances the vertical magnetic anisotropy of the entire first ferromagnetic layer 31.

The second ferromagnetic layer 32 is a magnetization fixed layer. The magnetization fixed layer is a layer made of a magnetic material in which the state of magnetization (for example, the direction of magnetization or the magnitude of magnetization) is less likely to change than the free magnetization layer when a predetermined external force is applied. The coercive force of the second ferromagnetic layer 32 is, for example, larger than the coercive force of the first ferromagnetic layer 31. The second ferromagnetic layer 32 has an easy magnetization axis in the same direction as the first ferromagnetic layer 31. The second ferromagnetic layer 32 may be an in-plane magnetization film or a perpendicular magnetization film.

In the present embodiment, the second ferromagnetic layer 32 is composed of an inner ferromagnetic layer 32A, a non-magnetic layer 32B, and an outer ferromagnetic layer 32C. In this case, the magnetization of the inner ferromagnetic layer 32A is fixed by magnetic coupling with the outer ferromagnetic layer 32C via the non-magnetic layer 32B.

The material constituting the inner ferromagnetic layer 32A is, for example, the same as that of the first ferromagnetic layer 31. The inner ferromagnetic layer 32A is, for example, Co having a thickness of 0.4 nm or more and 1.0 nm or less, Mo having a thickness of 0.1 nm or more and 0.5 nm or less, and a CoFeB alloy having a thickness of 0.3 nm or less and 1.0 nm or less, 0. A laminated body in which Fe having a thickness of .3 nm or more and 1.0 nm or less are laminated in order may be used.

The outer ferromagnetic layer 32C is magnetically coupled to, for example, the inner ferromagnetic layer 32A. The magnetic coupling is, for example, an antiferromagnetic coupling and is caused by the RKKY interaction. The material constituting the outer ferromagnetic layer 32C is, for example, the same as that of the first ferromagnetic layer 31. The outer ferromagnetic layer 32C is, for example, a laminated film in which Co and Pt are alternately laminated, and a laminated film in which Co and Ni are alternately laminated.

The non-magnetic layer 32B is, for example, Ru, Ir, or the like. The film thickness of the non-magnetic layer 32B is, for example, a film thickness at which the inner ferromagnetic layer 32A and the outer ferromagnetic layer 32C are antiferromagnetically coupled by the RKKY interaction.

The spacer layer 33 is a non-magnetic layer arranged between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. The spacer layer 33 is composed of a layer made of a conductor, an insulator or a semiconductor, or a layer containing an energizing point made of a conductor in the insulator. The film thickness of the spacer layer 33 can be adjusted according to the orientation direction of the magnetization of the first ferromagnetic layer 31 and the magnetization of the second ferromagnetic layer 32 in the initial state.

In this embodiment, the spacer layer 33 is made of an insulator. In this case, the magnetic element 30 has a magnetic tunnel junction (MTJ: Magnetic Tunnel Junction) including a first ferromagnetic layer 31, a spacer layer 33, and a second ferromagnetic layer 32. Such an element is called an MTJ element. However, the spacer layer 33 may be made of metal. In that case, the magnetic element 30 can exhibit a giant magnetoresistive (GMR) effect. Such an element is called a GMR element.

When the spacer layer 33 is made of an insulating material, a material such as aluminum oxide, magnesium oxide, titanium oxide or silicon oxide can be used. A high magnetoresistive change rate can be obtained by adjusting the film thickness of the spacer layer 33 so that a high TMR (Tunnel Magnetoresisnce) effect is exhibited between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. In order to efficiently utilize the TMR effect, the film thickness of the spacer layer 33 may be about 0.5 nm or more and 10.0 nm or less.

When the spacer layer 33 is made of a non-magnetic conductive material, a conductive material such as Cu, Ag, Au or Ru can be used. In order to efficiently utilize the GMR effect, the film thickness of the spacer layer 33 may be about 0.5 nm or more and 3.0 nm or less.

When the spacer layer 33 is made of a non-magnetic semiconductor material, a material such as zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide or ITO can be used. In this case, the film thickness of the spacer layer 33 may be about 1.0 nm or more and 4.0 nm or less.

When a layer including a current-carrying point composed of a conductor in a non-magnetic insulator is applied as the spacer layer 33, CoFe, CoFeB, CoFeSi, CoMnGe, and CoMnSi are contained in the non-magnetic insulator composed of aluminum oxide or magnesium oxide. , ComnAl, Fe, Co, Au, Cu, Al or Mg, it is preferable to have a structure including a current-carrying point composed of a conductor. In this case, the film thickness of the spacer layer 33 may be about 0.5 nm or more and 2.0 nm or more. The energizing point is, for example, a columnar body having a diameter of 1 nm or more and 5 nm or less.
As described above, the magnetic element 30 may be referred to as an MTJ element, a GMR element, or the like depending on the constituent material of the spacer layer 33, but is also collectively referred to as a magnetoresistive effect element.

The photodetector element 1 configured as described above is manufactured by a laminating step, a heat treatment step, and a processing step of each layer. First, the base layer 34, the outer ferromagnetic layer 32C, the non-magnetic layer 32B, the inner ferromagnetic layer 32A, the spacer layer 33, and the first ferromagnetic layer 31 are laminated on the second electrode 20 in this order. Each layer is formed by, for example, sputtering. Further, another layer may be laminated as needed, such as forming a cap layer on the first ferromagnetic layer 31.

Next, the laminated film obtained above is subjected to a heat treatment such as annealing. When the annealing treatment is performed, the heating temperature is, for example, 400 ° C. or higher. After that, the laminated film is processed into a predetermined columnar body by photolithography and etching. The columnar body may be a cylinder or a prism. For example, the shortest width when the columnar body is viewed from the z direction is 10 nm or more and 1000 nm or less.

Next, the first electrode 10A is manufactured on the first ferromagnetic layer 31 or on a cap layer (not shown). After that, an opening 12A is formed in a part of the first electrode 10A by a known method such as resist and etching, and a transparent conductive film 13A is formed in the opening 12A by a known method such as sputtering. By the above steps, the photodetector element 1 is obtained.

When the transparent conductive film 13A is irradiated with light and the first ferromagnetic layer 31 of the magnetic element 30 is irradiated with light, the state of magnetization of the first ferromagnetic layer 31 (for example, the direction of magnetization or the magnitude of magnetization). ) Changes, and the resistance value of the magnetic element 30 changes. The light detection element 1 outputs the light ray S1 irradiated to the magnetic element 30 through the transparent conductive film 13A as a change in voltage between the first electrode 10A and the second electrode 20.

5A is a plan view showing the configuration of the first electrode 10A in FIG. 1, and FIG. 5B is a plan view showing a modified example of the first electrode 10A of FIG. 5A.

As shown in FIG. 5A, the opening 12A is preferably provided so as to include the magnetic element 30 in a plan view from the z direction. In the present embodiment, in a plan view from the z direction, the opening 12A has a circular shape having a y-direction dimension of L1, and the transparent conductive film 13A also has a circular shape having a y-direction dimension of L1. It has a shape. Further, the magnetic element 30 preferably has a circular shape having a y-direction dimension d1 smaller than the y-direction dimension L1 of the opening 12A. The magnetic element 30 may have a square shape having a y-direction dimension d1 smaller than the y-direction dimension L1 of the opening 12A. As a result, the light ray S1 can be transmitted to the entire magnetic element 30, and the optical signal can be transmitted to the magnetic element 30 more efficiently.

Further, as shown in FIG. 5B, it is preferable that the opening 12B is provided in the metal film 11B so as to include the magnetic element 30 in a plan view from the z direction. Then, in a plan view from the z direction, the opening 12B may have a square shape having a length in the y direction of L2, and the transparent conductive film 13B also has a length in the y direction of L2. It may have a square shape. In this case, the magnetic element 30 has a circular shape having a y-direction dimension d2 smaller than the y-direction dimension L2 of the opening 12B. The magnetic element 30 may have a square shape having a y-direction dimension d2 smaller than the y-direction dimension L2 of the opening 12B.

Here, the opening in the present invention may have various shapes such as a distorted circular shape, a rectangular shape, and a polygonal shape. The "length of the opening" in the present invention refers to the length of the shortest line segment among the line segments that pass through the center of gravity of the opening and overlap the opening in a plan view.
For example, as shown in FIG. 6A, the opening 12C has a distorted substantially circular shape. In this case, the length L3 of the opening 12C is the length of the shortest line segment that passes through the center of gravity P1 of the opening 12C and overlaps with the opening 12C in a plan view. The magnetic element 30 preferably has a circular shape or a square shape having a y-direction dimension d1 smaller than the length L3 of the opening 12C.

Further, as shown in FIG. 6B, the opening 12D has an octagonal shape. In this case, the length L4 of the opening 12D is the length of the shortest line segment that passes through the center of gravity P2 of the opening 12D and overlaps with the opening 12D. The magnetic element 30 preferably has a circular shape or a square shape having a y-direction dimension d2 smaller than the length L4 of the opening 12D.

Further, the length of the opening in the present invention is preferably smaller than the wavelength of the light applied to the transparent conductive film.
For example, the length L3 of the opening 12C is preferably smaller than the wavelength λ of light (d1 <L3 <λ). Similarly, the length L4 of the opening 12D is preferably smaller than the wavelength λ of light (d2 <L4 <λ). When the length of the opening is smaller than the wavelength λ of the light, radial near-field light is generated from the surface of the metal film of the opening when the light is incident on the opening, and this near-field light is compared with the vicinity of the opening. It is transmitted to a narrow range. Therefore, by making the length L3 of the opening 12C or the length L4 of the opening 12D smaller than the wavelength λ of the light, the light irradiated to the transparent conductive film 13A provided in the opening 12C or the opening 12D. Generates near-field light, and this near-field light irradiates the magnetic element 30. By using the near-field light in this way, the light intensity can be increased, and the optical signal can be transmitted to the magnetic element 30 more efficiently.

FIG. 7 is a plan view showing a modified example of the first electrode 10B of FIG. 5B.
As shown in FIG. 7, the first electrode 10E includes a metal film 11E, an opening 12E provided in a part of the metal film 11E, and a transparent conductive film 13E arranged in the opening 12E. .. The opening 12E extends in the y direction (the width direction of the first electrode 10E) and has a substantially rectangular shape in a plan view from the z direction. The opening 12E may have another shape such as an elliptical shape or an oval shape extending in the y direction.

In this modification, a plurality of magnetic elements 30-1, 30-2, and 30-3 are arranged in the y direction. The opening 12E is provided so as to include a plurality of magnetic elements 30-1, 30-2, and 30-3 in a plan view from the z direction. Further, it is preferable that each of the magnetic elements 30-1, 30-2, and 30-3 has a circular shape or a square shape having a y-direction dimension d5 smaller than the x-direction dimension L5 of the opening 12E. As a result, the light ray S1 can be transmitted to the entire magnetic element 30, and the optical signal can be transmitted to the magnetic element 30 more efficiently.

Further, the length L5 of the opening 12E is preferably smaller than the wavelength λ of the light applied to the transparent conductive film 13E (d5 <L5 <λ). As a result, the light intensity can be increased by the near-field light, and the optical signal can be transmitted to the magnetic element 30 more efficiently.

FIG. 8 is a diagram showing an example of a communication system using the photodetector element 1 of FIG.
As shown in FIG. 8, the communication system 60 includes a first terminal device 61 and a second terminal device 62. The first terminal device 61 and the second terminal device 62 are not particularly limited, but are, for example, mobile terminal devices. Examples of mobile terminal devices include smartphones and tablets.

Each of the first terminal device 61 and the second terminal device 62 has a receiving device and a transmitting device (not shown). The optical signal transmitted from the transmitting device of the first terminal device 61 is received by the receiving unit device of the second terminal device 62. The light used for transmission / reception between the first terminal device 61 and the second terminal device 62 is, for example, visible light. Each receiving device is provided with a photodetector, and the photodetector 1 can be applied as the photodetector.

In the communication system of FIG. 8, the first terminal device 61 and the second terminal device 62 are mobile terminal devices, but the present invention is not limited to this, and one or both of the two terminal devices may be stationary terminal devices. .. Further, one or both of the two terminal devices may function as a node for IoT communication or the like. Further, the communication system of FIG. 8 is wireless one-to-one communication, but the present invention is not limited to this, and wireless one-to-many communication may be used.

As described above, according to the present embodiment, the transparent conductive film 13A (13B, 13E) is electrically connected to the magnetic element 30 and has an opening so as to overlap the magnetic element 30 in a plan view from the z direction. By arranging the transparent conductive film 13A (13B, 13E) in the portions 12A (12B, 12E), the optical signal can be efficiently transmitted to the magnetic element 30 and the electric signal can be taken out, and the first electrode 10A (1st electrode 10A) Since the resistance of 10B and 10E) can be reduced, the electric signal from the magnetic element 30 can be efficiently extracted.

As described above, the present invention is not limited to the above-described embodiments and modifications, and various modifications and modifications can be made within the scope of the gist of the present invention described within the scope of claims.

1 Optical detection element 10a Longitudinal end 10A 1st electrode 10B 1st electrode 10E 1st electrode 11A Metal film 11B Metal film 11E Metal film 12A Opening 12B Opening 12C Opening 12D Opening 12E Opening 13A Transparent conductive film 13B Transparent conductive film 13a Main surface 13b Main surface 13E Transparent conductive film 20 Second electrode 20a Main surface 30 Magnetic element 30-1 Magnetic element 30-2 Magnetic element 30-3 Magnetic element 30az direction End face 30b z direction end face 31 1st ferromagnetic layer 32 2nd ferromagnetic layer 32A Inner ferromagnetic layer 32B Non-magnetic layer 32C Outer ferromagnetic layer 33 Spacer layer 34 Underlayer 40 Optical transmission part 40a One end 40b End end 41 First diffraction lattice part 41a Main surface 41b Main surface 41B Groove 42 Second diffraction grid 42B Groove 43 Waveguide 43a End 43A Widthwise end 43b End 51 Constant current drive circuit 52 Signal processing circuit 60 Communication system 61 First terminal device 62 Second terminal device

Claims (8)

With a metal film
An opening provided in a part of the metal film and
The transparent conductive film arranged in the opening and
Have,
The transparent conductive film has an electrode structure that is electrically connected to the element and overlaps with the element in a plan view from the thickness direction of the transparent conductive film. The electrode structure according to claim 1, wherein the opening is provided so as to include the element in a plan view from the thickness direction. The electrode structure according to claim 1 or 2, wherein the length of the opening is smaller than the wavelength of the light applied to the transparent conductive film. The first and second electrodes and
It has a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and has the first electrode and the second electrode. With the magnetic element placed between
Equipped with
The first electrode is
With a metal film
An opening provided in a part of the metal film and
The transparent conductive film arranged in the opening and
Have,
The transparent conductive film is electrically connected to the magnetic element and overlaps with the magnetic element in a plan view from the thickness direction of the transparent conductive film.
A photodetector that irradiates the transparent conductive film with light. The photodetector element according to claim 4, wherein the opening is provided so as to include the magnetic element in a plan view from the thickness direction. The photodetector according to claim 4 or 5, wherein the length of the opening is smaller than the wavelength of the light applied to the transparent conductive film. Further, a light transmitting unit for irradiating the transparent conductive film with light is provided.
The light transmission unit is
A first diffraction grating portion provided at one end of the light transmission portion and irradiated with light from the outside, and a first diffraction grating portion.
A second diffraction grating section provided at the other end of the light transmission section and emitting light transmitted from the first diffraction grating section, and a second diffraction grating section.
A waveguide provided between the first diffraction grating portion and the second diffraction grating portion,
Have,
The light detection element according to any one of claims 4 to 6, wherein the area of the first diffraction grating portion is wider than the area of the second diffraction grating portion in the plan view of the light transmission unit. A plurality of the magnetic elements are provided in an array.
The photodetection according to any one of claims 4 to 7, wherein the opening is provided so as to include the plurality of magnetic elements in a plan view from the thickness direction of the transparent conductive film. element.

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