Light detection element and receiving device

Abstract

To provide novel light detection element and receiving device.SOLUTION: A light detection element includes a magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and light including an optical signal having a change in optical intensity is irradiated onto the first ferromagnetic layer, and the optical signal is received on the basis of an output voltage from the magnetic element, and the magnetization of the first ferromagnetic layer when the first ferromagnetic layer is irradiated with the light is smaller than the magnetization of the first ferromagnetic layer when the first ferromagnetic layer is not irradiated with the light.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical detection element and a receiving device.

Background Art

[0002] With the spread of the Internet, the communication volume has increased exponentially, and the importance of optical communication has been extremely enhanced. Optical communication is a communication means that converts an electrical signal into an optical signal and performs transmission and reception using the optical signal.

[0003] 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 semiconductor pn junction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] With the development of information and communication technologies, further increase in communication speed is required. In optical communication, in order to achieve high-speed communication, higher frequency of signal modulation is required. In the semiconductor photodiode shown in Patent Document 1, there is a problem that the reception sensitivity is significantly reduced with the increase in frequency, and a new breakthrough is required for further development.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a novel receiving device, receiving system, transmitting and receiving device, communication system, and optical detection element, and to provide a receiving device, receiving system, transmitting and receiving device, communication system, and optical detection element that enable high-speed communication.

Means for Solving the Problems

[0007] To solve the above problems, the following means are provided.

[0008] (1) The receiving device according to the first aspect includes a magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer. Light including an optical signal having a change in optical intensity is irradiated onto the first ferromagnetic layer, and the optical signal is received based on an output voltage from the magnetic element.

[0009] (2) In the receiving device according to the above aspect, the output voltage from the magnetic element may be configured to change in correspondence with a change in the intensity of the light irradiated onto the first ferromagnetic layer.

[0010] (3) In the receiving device according to the above aspect, the angle between the magnetization direction of the first ferromagnetic layer in a state where the first ferromagnetic layer is not irradiated with the light and the magnetization direction of the first ferromagnetic layer in a state where the first ferromagnetic layer is irradiated with the light may be greater than 0° and less than 90°.

[0011] [[ID=1B]](4) In the receiving device according to the above aspect, the optical signal has at least two levels of intensity, and the magnitude of the output voltage from the magnetic element indicates a first value when the intensity of the light irradiated onto the first ferromagnetic layer is a first intensity, and indicates a second value when the intensity of the light irradiated onto the first ferromagnetic layer is a second intensity. When the second intensity is greater than the first intensity and the second value is greater than the first value, a current may flow from the first ferromagnetic layer toward the second ferromagnetic layer, and when the second value is less than the first value, a current may flow from the second ferromagnetic layer toward the first ferromagnetic layer.

[0012] (5) The receiving device according to the above aspect further includes a hard bias layer that applies a bias magnetic field to the first ferromagnetic layer. The hard bias layer is located at a position overlapping the first ferromagnetic layer when viewed from any direction orthogonal to the stacking direction of the magnetic element, and the magnetization direction of the hard bias layer may be opposite to the magnetization direction of the first ferromagnetic layer in a state where the light is not irradiated.

[0013] (6) In the receiving device according to the above aspect, the magnetic element further includes a first electrode connected to the first ferromagnetic layer and a second electrode connected to the second ferromagnetic layer, and the first electrode may be transparent to light in the wavelength range of the optical signal used.

[0014] (7) The receiving device according to the above aspect further includes a soft magnetic material, and the soft magnetic material may cover at least a part of the outer periphery of the magnetic element from the outside in a plan view from the stacking direction of the magnetic element.

[0015] (8) In the receiving device according to the above aspect, the soft magnetic material is also above and below the magnetic element in the stacking direction, and the soft magnetic material on the first ferromagnetic layer side among the soft magnetic materials above and below the magnetic element may have an opening.

[0016] (9) In the receiving device according to the above aspect, a mesh-shaped magnetic net connected to the soft magnetic material may be provided in the opening.

[0017] (10) In the receiving device according to the above aspect, when the output voltage from the magnetic element is equal to or higher than a threshold value, it may be processed as a first signal, and when it is lower than the threshold value, it may be processed as a second signal.

[0018] (11) In the receiving device according to the above aspect, the change in the output voltage from the magnetic element within a predetermined time may be processed as a first signal, and the non-change in the output voltage from the magnetic element within a predetermined time may be processed as a second signal.

[0019] (12) The receiving device according to the above aspect further includes an integrated circuit, and the magnetic element and the integrated circuit are formed on the same substrate with an interlayer insulating film therebetween, and the integrated circuit and the magnetic element may be connected via a through wiring that penetrates the interlayer insulating film.

[0020] (13) The transceiver according to the second aspect includes the receiving device according to the above aspect and a transmitting device that transmits an optical signal.

[0021] (14) The communication system according to the third aspect includes a plurality of transceivers according to the above aspect.

[0022] (15) The portable terminal device according to the fourth aspect includes the receiving device according to the above aspect.

[0023] (16) The optical detection element according to the fifth aspect includes a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and the output voltage changes in response to a change in the intensity of light irradiated on the first ferromagnetic layer.

[0024] (17) In the optical detection element according to the above aspect, the angle between the magnetization direction of the first ferromagnetic layer in a state where the first ferromagnetic layer is not irradiated with the light and the magnetization direction of the first ferromagnetic layer in a state where the first ferromagnetic layer is irradiated with the light may be greater than 0° and less than 90°.

[0025] (18) The optical detection element according to the above aspect is irradiated with an optical signal having at least two levels of intensity. When the intensity of the light irradiated on the first ferromagnetic layer is the first intensity, the magnitude of the output voltage shows a first value, and when the intensity of the light irradiated on the first ferromagnetic layer is the second intensity, the magnitude of the output voltage shows a second value. Under the condition that the second intensity is greater than the first intensity, when the second value is greater than the first value, current flows from the first ferromagnetic layer toward the second ferromagnetic layer, and when the second value is less than the first value, current flows from the second ferromagnetic layer toward the first ferromagnetic layer. Such a configuration may be adopted.

Advantages of the Invention

[0026] The receiving device, the transmitting and receiving device, the communication system, the mobile terminal device, and the optical detection element according to the above aspect are novel and create new breakthroughs. Further, the receiving device, the transmitting and receiving device, the communication system, the mobile terminal device, and the optical detection element according to the above aspect enable high-speed communication.

Brief Description of the Drawings

[0027]

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Embodiments for Carrying Out the Invention

[0028] Hereinafter, embodiments will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show, for the sake of clarity, parts that are characteristic by being enlarged for convenience, and the dimensional ratios of the respective components may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and it is possible to appropriately modify and implement within the scope in which the effects of the present invention are achieved.

[0029] Define the directions. The stacking direction of the light detection element 10 is defined as the z direction, one direction in the plane orthogonal to the z direction is defined as the x direction, and the direction orthogonal to the x direction and the z direction is 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 the direction from the substrate Sb toward the light detection element 10. The up and down do not necessarily coincide with the direction in which gravity acts.

[0030] "First Embodiment" FIG. 1 is a conceptual diagram of a communication system 1000 according to the first embodiment. The communication system 1000 shown in FIG. 1 includes a plurality of transmission / reception devices 300 and a fiber FB connecting between the transmission / reception devices 300. The communication system 1000 can be used for short- and medium-distance communications such as within a data center and between data centers, and long-distance communications such as between cities. The transmission / reception device 300 is installed, for example, in a data center, a base station or a backbone station of a long-distance communication network. The fiber FB connects, for example, between data centers. The communication system 1000 performs communication between the transmission / reception devices 300 via the fiber FB, for example. The communication system 1000 may perform communication between the transmission / reception devices 300 wirelessly without using the fiber FB.

[0031] FIG. 2 is a block diagram of the transmission / reception device 300 according to the first embodiment. The transmission / reception device 300 includes a reception device 100 and a transmission device 200. The reception device 100 receives an optical signal L1, and the transmission device 200 transmits an optical signal L2. The light in this specification includes not only visible light rays but also infrared rays having a longer wavelength than visible light rays and ultraviolet rays having a shorter wavelength than visible light rays.

[0032] The receiving device 100 includes, for example, a photodetection element 10 and a signal processing unit 11. The photodetection element 10 converts an optical signal L1 into an electrical signal. Details of the photodetection element 10 will be described later. The signal processing unit 11 processes the electrical signal converted by the photodetection element 10. The signal processing unit 11 receives the signal included in the optical signal L1 by processing the electrical signal generated from the photodetection element 10.

[0033] The transmitting device 200 includes, for example, a light source 201, an electrical signal generation element 202, and an optical modulation element 203. The light source 201 is, for example, a laser element. The light source 201 may be outside the transmitting device 200. The electrical signal generation element 202 generates an electrical signal based on the transmission information. The electrical signal generation element 202 may be integrated with the signal conversion element of the signal processing unit 11. The optical modulation element 203 modulates the light output from the light source 201 based on the electrical signal generated by the electrical signal generation element 202, and outputs an optical signal L2.

[0034] FIG. 3 is a circuit diagram of the transceiver 300 according to the first embodiment. In FIG. 3, the signal processing unit 11 is omitted.

[0035] The receiving device 100 includes, for example, a photodetection element 10, a first electrode 15, a second electrode 16, an input terminal P in and an output terminal P out and a reference potential terminal P G and is provided with. The first electrode 15 and the second electrode 16 sandwich the photodetection element 10 in the stacking direction. The first electrode 15 is, for example, an electrode on the side irradiated with light including the optical signal L1.

[0036] The first electrode 15 is connected to, for example, the input terminal Pin and the output terminal Pout. The second electrode 16 is connected to, for example, the reference potential terminal PG. The input terminal Pin is connected to the power supply PS. The power supply PS may be external to the receiving device 100. The power supply PS applies a sense current, a reset current, etc. to the light detection element 10. When there is no need to flow a current from the outside to the light detection element 10, the input terminal Pin and the power supply PS may be omitted. The output terminal Pout outputs, for example, the voltage between the first electrode 15 and the second electrode 16 that sandwich the light detection element 10 in the stacking direction. The resistance value of the light detection element 10 in the stacking direction is obtained from Ohm's law by flowing a sense current in the stacking direction of the light detection element 10. The output terminal P out is connected to the signal processing unit 11. The reference potential terminal P G is connected to the reference potential and determines the reference potential of the receiving device 100. The reference potential in FIG. 3 is the ground G. The ground G may be provided outside the receiving device 100. The reference potential may be other than the ground G.

[0037] The receiving device 100 and the transmitting device 200 are connected to, for example, a common reference potential (ground G). The receiving device 100 and the transmitting device 200 may have different reference potentials. If the reference potentials of the receiving device 100 and the transmitting device 200 are the same, the generation of noise can be reduced.

[0038] FIG. 4 is a cross-sectional view of the receiving device 100 according to the first embodiment. The receiving device 100 includes, for example, a light detection element 10, an integrated circuit 20, and an interlayer insulating film 30. The light detection element 10, the integrated circuit 20, and the interlayer insulating film 30 are formed, for example, on the same substrate Sb.

[0039] The integrated circuit 20 includes a signal processing unit 11 that processes the signal output from the light detection element 10. For example, when the output voltage from the light detection element 10 (the resistance value of the light detection element 10 in the z direction) is equal to or greater than the threshold value, the integrated circuit 20 processes it as a first signal (e.g., "1"), and when it is less than the threshold value, it processes it as a second signal (e.g., "0"). When the transmission device 200 is formed on the same substrate Sb, the integrated circuit 20 may include a light source 201, an electrical signal generation element 202, and an optical modulation element 203. The integrated circuit 20 and the light detection element 10 are connected, for example, via a through-wiring w that penetrates the interlayer insulating film 30. Instead of the through-wiring w, these may be connected by wire bonding.

[0040] The interlayer insulating film 30 is an insulator that insulates between wirings and between elements in the multilayer wiring. The interlayer insulating film 30 is, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg. The interlayer insulating film 30 is, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ), etc.

[0041] FIG. 5 is a cross-sectional view of the light detection element 10 according to the first embodiment. In FIG. 5, the first electrode 15 and the second electrode 16 are shown simultaneously, and the direction of magnetization in the initial state of the ferromagnetic material is represented by an arrow.

[0042] The light detection element 10 is a magnetic element having at least a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a spacer layer 3. The spacer layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. In addition to these, the light detection element 10 may have a third ferromagnetic layer 4, a magnetic coupling layer 5, an underlayer 6, a perpendicular magnetization induction layer 7, a cap layer 8, and a sidewall insulating layer 9.

[0043] The light detection element 10 is, for example, an MTJ (Magnetic Tunnel Junction) element in which the spacer layer 3 is made of an insulating material. In this case, the light detection element 10 is an element whose resistance value in the z direction (the resistance value when a current flows in the z direction) changes according to the change in the relative angle between the magnetization direction of the first ferromagnetic layer 1 and the magnetization direction of the second ferromagnetic layer 2. Such an element is also called a magnetoresistive effect element.

[0044] The first ferromagnetic layer 1 is a light detection layer whose magnetization direction changes when irradiated with light from the outside. The first ferromagnetic layer 1 is also called a free magnetization layer. The free magnetization layer is a layer containing a magnetic material whose magnetization direction changes when a predetermined external energy is applied. The predetermined external energy is, for example, light irradiated from the outside, a current flowing in the z direction of the light detection element 10, or an external magnetic field. Since the magnetization of the ferromagnetic material can change its direction following a rapid change in the intensity of the light irradiated on the ferromagnetic material (a high-frequency optical signal), by using the first ferromagnetic layer 1 as a light detection layer, the receiving device 100 can receive a high-frequency optical signal, enabling high-speed optical communication.

[0045] The first ferromagnetic layer 1 contains a ferromagnetic material. The first ferromagnetic layer 1 contains, for example, at least one of Co, Fe, and Ni. The first ferromagnetic layer 1 contains, for example, magnetic elements such as Co, Fe, or Ni. The first ferromagnetic layer 1 may contain non-magnetic elements such as B, Mg, Hf, and Gd together with the above-described magnetic elements. The first ferromagnetic layer 1 may be, for example, an alloy containing magnetic elements and non-magnetic elements. The first ferromagnetic layer 1 may be composed of a plurality of layers. The first ferromagnetic layer 1 is, for example, a CoFeB alloy, a laminate in which a CoFeB alloy layer is sandwiched between Fe layers, or a laminate in which a CoFeB alloy layer is sandwiched between CoFe layers.

[0046] The first ferromagnetic layer 1 may be an in-plane magnetization film having an easy axis of magnetization in the in-plane direction (any direction in the xy plane) or a perpendicular magnetization film having an easy axis of magnetization in the film plane normal direction (z direction).

[0047] The film thickness of the first ferromagnetic layer 1 is, for example, 1 nm or more and 5 nm or less. The film thickness of the first ferromagnetic layer 1 is preferably, for example, 1 nm or more and 2 nm or less. When the first ferromagnetic layer 1 is a perpendicularly magnetized film, if the film thickness of the first ferromagnetic layer 1 is thin, the perpendicular magnetic anisotropy addition effect from the layers above and below the first ferromagnetic layer 1 is enhanced, and the perpendicular magnetic anisotropy of the first ferromagnetic layer increases. That is, when the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is high, the force for the magnetization to return to the z direction is enhanced. On the other hand, if the film thickness of the first ferromagnetic layer 1 is thick, the perpendicular magnetic anisotropy addition effect from the layers above and below the first ferromagnetic layer 1 is relatively weakened, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is weakened.

[0048] When the film thickness of the first ferromagnetic layer 1 becomes thinner, the volume as a ferromagnetic material becomes smaller, and when it becomes thicker, the volume as a ferromagnetic material becomes larger. The ease of response of the magnetization of the first ferromagnetic layer 1 when external energy is applied is inversely proportional to the product (KuV) of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 1. That is, when the product of the magnetic anisotropy and the volume of the first ferromagnetic layer 1 becomes smaller, the reactivity with respect to the optical signal L1 at ultra-high speeds increases. From such a perspective, as optical communication becomes ultra-high speed, it is preferable to appropriately design the magnetic anisotropy of the first ferromagnetic layer 1 and then reduce the volume of the first ferromagnetic layer 1. That is, it is preferable to make the film thickness of the first ferromagnetic layer 1 thinner for ultra-high speed communication.

[0049] When the film thickness of the first ferromagnetic layer 1 is thicker than 2 nm, for example, an insertion layer made of Mo or W may be provided in the first ferromagnetic layer 1. That is, a laminate in which a ferromagnetic layer, an insertion layer, and a ferromagnetic layer are laminated in this order in the z direction may be used as the first ferromagnetic layer 1. The perpendicular magnetic anisotropy of the entire first ferromagnetic layer 1 is enhanced by the interfacial magnetic anisotropy at the interface between the insertion layer and the ferromagnetic layer. The film thickness of the insertion layer is, for example, 0.1 nm to 0.6 nm.

[0050] The second ferromagnetic layer 2 is a magnetization fixing layer. The magnetization fixing layer is a layer made of a magnetic material whose magnetization direction is less likely to change than that of the magnetization free layer when a predetermined external energy is applied. The coercive force of the second ferromagnetic layer 2 is, for example, larger than that of the first ferromagnetic layer 1. The second ferromagnetic layer 2 has an easy axis of magnetization in the same direction as the first ferromagnetic layer 1. The second ferromagnetic layer 2 may be an in-plane magnetization film or a perpendicular magnetization film.

[0051] The material constituting the second ferromagnetic layer 2 is, for example, the same as that of the first ferromagnetic layer 1. The second ferromagnetic layer 2 may be, for example, a laminate in which Co with a thickness of 0.4 nm to 1.0 nm, Mo with a thickness of 0.1 nm to 0.5 nm, a CoFeB alloy with a thickness of 0.3 nm to 1.0 nm, and Fe with a thickness of 0.3 nm to 1.0 nm are stacked in this order.

[0052] The magnetization of the second ferromagnetic layer 2 may be fixed, for example, by magnetic coupling with the third ferromagnetic layer 4 via the magnetic coupling layer 5. In this case, the combination of the second ferromagnetic layer 2, the magnetic coupling layer 5, and the third ferromagnetic layer 4 may sometimes be referred to as a magnetization fixing layer.

[0053] The third ferromagnetic layer 4 magnetically couples with the second ferromagnetic layer 2, for example. The magnetic coupling is, for example, an antiferromagnetic coupling and is caused by the RKKY interaction. The material constituting the third ferromagnetic layer 4 is, for example, the same as that of the first ferromagnetic layer 1. The third ferromagnetic layer 4 is, for example, a laminate film in which Co and Pt are alternately stacked, or a laminate film in which Co and Ni are alternately stacked. The magnetic coupling layer 5 is, for example, Ru, Ir, or the like. The film thickness of the magnetic coupling layer 5 is, for example, a film thickness at which the second ferromagnetic layer 2 and the third ferromagnetic layer 4 are antiferromagnetically coupled by the RKKY interaction.

[0054] The spacer layer 3 is a non-magnetic layer disposed between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The spacer layer 3 is composed of a layer made of a conductor, an insulator, or a semiconductor, or a layer including an energization point made of a conductor in an insulator. The film thickness of the spacer layer 3 can be adjusted according to the orientation directions of the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 in the initial state described later.

[0055] For example, when the spacer layer 3 is made of an insulator, the photosensor element 10 has a magnetic tunnel junction (MTJ) composed of a first ferromagnetic layer 1, a spacer layer 3, and a second ferromagnetic layer 2. Such an element is called an MTJ element. In this case, the photosensor element 10 can exhibit the tunnel magnetoresistance (TMR) effect. For example, when the spacer layer 3 is made of a metal, the photosensor element 10 can exhibit the giant magnetoresistance (GMR) effect. Such an element is called a GMR element. The photosensor element 10 may have different names such as an MTJ element or a GMR element depending on the constituent material of the spacer layer 3, and is also generically called a magnetoresistive effect element.

[0056] When the spacer layer 3 is made of an insulating material, materials containing aluminum oxide, magnesium oxide, titanium oxide, silicon oxide, etc. can be used. Also, these insulating materials may contain elements such as Al, B, Si, Mg, and magnetic elements such as Co, Fe, Ni. By adjusting the film thickness of the spacer layer 3 so that a high TMR effect is exhibited between the first ferromagnetic layer 1 and the second ferromagnetic layer 2, a high magnetoresistance change rate can be obtained. In order to efficiently utilize the TMR effect, the film thickness of the spacer layer 3 may be about 0.5 to 5.0 nm, or may be about 1.0 to 2.5 nm.

[0057] When the spacer layer 3 is made of a nonmagnetic conductive material, conductive materials 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 3 may be about 0.5 to 5.0 nm, or may be about 2.0 to 3.0 nm.

[0058] When the spacer layer 3 is made of a nonmagnetic semiconductor material, materials 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 3 may be about 1.0 to 4.0 nm.

[0059] When applying a layer including an energization point formed of a conductor in a nonmagnetic insulator as the spacer layer 3, it may be configured as a structure including an energization point formed of a nonmagnetic conductor such as Cu, Au, or Al in a nonmagnetic insulator formed of aluminum oxide or magnesium oxide. Also, the conductor may be formed of a magnetic element such as Co, Fe, or Ni. In this case, the film thickness of the spacer layer 3 may be about 1.0 to 2.5 nm. The energization point is, for example, a columnar body having a diameter of 1 nm or more and 5 nm or less when viewed from a direction perpendicular to the film surface.

[0060] The underlayer 6 shown in FIG. 5 is, for example, on the second electrode 16. The underlayer 6 is a seed layer or a buffer layer. The seed layer enhances the crystallinity of the layer laminated on the seed layer. The seed layer is, for example, Pt, Ru, Hf, Zr, or NiFeCr. The film thickness of the seed layer is, for example, 1 nm or more and 5 nm or less. The buffer layer is a layer that relaxes the lattice mismatch between different crystals. The buffer layer is, for example, Ta, Ti, W, Zr, Hf, or a nitride of these elements. The film thickness of the buffer layer is, for example, 1 nm or more and 5 nm or less.

[0061] The perpendicular magnetization induction layer 7 is formed when the first ferromagnetic layer 1 is a perpendicular magnetization film. The perpendicular magnetization induction layer 7 is laminated on the first ferromagnetic layer 1. The perpendicular magnetization induction layer 7 induces the perpendicular magnetic anisotropy of the first ferromagnetic layer 1. The perpendicular magnetization induction layer 7 is, for example, magnesium oxide, W, Ta, Mo, or the like. When the perpendicular magnetization induction layer 7 is magnesium oxide, it is preferable that the magnesium oxide has an oxygen deficiency in order to enhance the conductivity. The film thickness of the perpendicular magnetization induction layer 7 is, for example, 0.5 nm or more and 2.0 nm or less.

[0062] The cap layer 8 is between the first ferromagnetic layer 1 and the first electrode 15. The cap layer 8 prevents damage to the lower layer during the process and enhances the crystallinity of the lower layer during annealing. The film thickness of the cap layer 8 is, for example, 3 nm or less so that sufficient light is irradiated to the first ferromagnetic layer 1.

[0063] The sidewall insulating layer 9 covers the periphery of the laminate including the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The sidewall insulating layer 9 is made of, for example, the same material as the interlayer insulating film 30.

[0064] The first electrode 15 is, for example, transparent to light in the wavelength range used for the optical signal L1. The wavelength range of the light used for the optical signal L1 is, for example, 300 nm or more and 2 μm or less, and includes the visible light region and the near-infrared light region. The first electrode 15 is a transparent electrode including a transparent electrode material of an oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO), etc. The first electrode 15 may be configured to have a plurality of columnar metals in these transparent electrode materials. In this case, the film thickness of the first electrode 15 is, for example, 10 nm to 300 nm. It is not essential to use the above transparent electrode material as the first electrode 15, and light from the outside may be made to reach the first ferromagnetic layer 1 by using a metal material such as Au, Cu, or Al with a thin film thickness. When a metal is used as the material of the first electrode 15, the film thickness of the first electrode 15 is, for example, 3 to 10 nm. In particular, Au has a higher transmittance of light with a wavelength near blue than other metal materials. Also, the first electrode 15 may have an antireflection film on the irradiation surface irradiated with light.

[0065] The second electrode 16 is made of a conductive material. The second electrode 16 is composed of, for example, a metal such as Cu, Al, or Au. Ta or Ti may be laminated above and below these metals. Also, a laminated film of Cu and Ta, a laminated film of Ta, Cu, and Ti, or a laminated film of Ta, Cu, and TaN may be used. Further, TiN or TaN may be used as the second electrode 16. The film thickness of the second electrode 16 is, for example, 200 nm to 800 nm. The second electrode 16 may be made to be transparent to light in the wavelength range of the optical signal L1. As the material of the second electrode 16, similar to the first electrode 15, for example, a transparent electrode material of an oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO), etc. may be used. Even when light is irradiated from the first electrode 15, depending on the intensity of the light, the light may reach the second electrode 16. In this case, since the second electrode 16 is configured to include a transparent electrode material of an oxide, compared to the case where the second electrode 16 is made of a metal, the reflection of light at the interface between the second electrode 16 and the layer in contact therewith can be suppressed.

[0066] The photodetector element 10 is manufactured by a lamination process, an annealing process, and a processing process for each layer. First, on the second electrode 16, a base layer 6, a third ferromagnetic layer 4, a magnetic coupling layer 5, a second ferromagnetic layer 2, a spacer layer 3, a first ferromagnetic layer 1, a perpendicular magnetization induction layer 7, and a cap layer 8 are laminated in this order. Each layer is formed, for example, by sputtering.

[0067] Next, the laminated film is annealed. The annealing temperature is, for example, from 250°C to 450°C. When the laminated film is formed on the same substrate as the semiconductor circuit, it is preferable to anneal at 400°C or higher. Thereafter, 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 may be 10 nm or more and 2000 nm or less, or may be 30 nm or more and 500 nm or less.

[0068] Next, an insulating layer is formed so as to cover the side surface of the columnar body. The insulating layer becomes the sidewall insulating layer 9. The sidewall insulating layer 9 may be laminated a plurality of times. Next, the upper surface of the cap layer 8 is exposed from the sidewall insulating layer 9 by chemical mechanical polishing (CMP), and the first electrode 15 is formed on the cap layer 8. The photodetection element 10 is obtained by the above process.

[0069] Next, the operation of the photodetection element 10 according to the first embodiment will be described. The first ferromagnetic layer 1 is irradiated with light including an optical signal L1 having a change in light intensity. A lens may be disposed on the side of the first ferromagnetic layer 1 in the stacking direction of the photodetection element 10 so that the light condensed on the first ferromagnetic layer 1 is irradiated through the lens. The lens may be formed in the wafer process for forming the photodetection element 10. The resistance value of the photodetection element 10 in the z direction changes due to the irradiation of the light including the optical signal L1 onto the first ferromagnetic layer 1. A case where the intensity of the light irradiated on the first ferromagnetic layer 1 has two levels of a first intensity and a second intensity will be described as an example. The second intensity is assumed to be greater than the first intensity. The first intensity may be the case where the intensity of the light irradiated on the first ferromagnetic layer 1 is zero.

[0070] The operation of the photodetection element 10 according to the first embodiment has two patterns. The first pattern is the case where the output voltage from the photodetection element 10 is higher in the case of the second intensity than in the case of the first intensity. The second pattern is the case where the output voltage from the photodetection element 10 is higher in the case of the first intensity than in the case of the second intensity.

[0071] FIGS. 6 and 7 are diagrams for explaining the operation of the first pattern of the photodetection element 10 according to the first embodiment. Two mechanisms are considered as the mechanism of the operation of the photodetection element 10. FIG. 6 is a diagram for explaining the first mechanism, and FIG. 7 is a diagram for explaining the second mechanism. The upper graphs in FIGS. 6 and 7 have the intensity of the light irradiated on the first ferromagnetic layer 1 on the vertical axis and time on the horizontal axis. The lower graphs in FIGS. 6 and 7 have the resistance value of the photodetection element 10 in the z direction on the vertical axis and time on the horizontal axis.

[0072] First, in a state where the first ferromagnetic layer 1 is irradiated with light of the first intensity (hereinafter referred to as the initial state), the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are in a parallel relationship. The resistance value of the light detection element 10 in the z direction shows the first resistance value R1, and the magnitude of the output voltage from the light detection element 10 shows the first value. The resistance value of the light detection element 10 in the z direction is obtained by using Ohm's law from the voltage value because a voltage is generated at both ends of the light detection element 10 in the z direction when a sense current Is flows in the z direction of the light detection element 10. The output voltage from the light detection element 10 is generated between the first electrode 15 and the second electrode 16. In the case of the first pattern shown in FIG. 6, it is preferable to flow the sense current Is from the first ferromagnetic layer 1 toward the second ferromagnetic layer 2. By flowing the sense current Is in this direction, a spin transfer torque in the same direction as the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1, and the magnetization M1 and the magnetization M2 are parallel in the initial state. Further, by flowing the sense current Is in this direction, it is possible to prevent the magnetization M1 of the first ferromagnetic layer 1 from reversing during operation.

[0073] Next, the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the first intensity to the second intensity. The second intensity is greater than the first intensity, and the magnetization M1 of the first ferromagnetic layer 1 changes from the initial state by the external energy due to the light irradiation. The state of the magnetization M1 is, for example, the tilt angle, magnitude, etc. with respect to the z direction. For example, as shown in FIG. 6, when the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the magnetization M1 tilts with respect to the z direction. The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in a state where the first ferromagnetic layer 1 is not irradiated with light including the optical signal L1 and the magnetization direction of the first ferromagnetic layer 1 at the second intensity is greater than 0° and less than 90°. Also, for example, as shown in FIG. 7, when the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the magnitude of the magnetization M1 becomes smaller. When the magnetization M1 of the first ferromagnetic layer 1 changes from the initial state, the resistance value of the light detection element 10 in the z direction shows the second resistance value R2, and the magnitude of the output voltage from the light detection element 10 shows the second value.

[0074] That is, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the resistance value of the light detection element 10 in the z direction changes from the first resistance value R1 to the second resistance value R2. In other words, corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer from the first intensity to the second intensity, the resistance value of the light detection element 10 in the z direction changes from the first resistance value R1 to the second resistance value R2. The second resistance value R2 is larger than the first resistance value R1, and the second value of the output voltage is larger than the first value. The second resistance value R2 is between the resistance value (first resistance value R1) when the magnetization M1 and the magnetization M2 are parallel and the resistance value when the magnetization M1 and the magnetization M2 are antiparallel. It is preferable that the magnetization M1 of the first ferromagnetic layer 1 is not inverted by the irradiation of the light including the optical signal L1 on the first ferromagnetic layer 1.

[0075] A spin transfer torque in the same direction as the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1. Therefore, in the case shown in FIG. 6, the magnetization M1 tries to return to the parallel state with the magnetization M2, and when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the light detection element 10 returns to the initial state. In the case shown in FIG. 7, when the intensity of the light irradiated on the first ferromagnetic layer 1 returns to the first intensity, the magnitude of the magnetization M1 of the first ferromagnetic layer 1 returns to its original value, and the light detection element 10 returns to the initial state. In any case, when the magnetization M1 returns to the initial state, the resistance value of the light detection element 10 in the z direction returns to the first resistance value R1. That is, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the resistance value of the light detection element 10 in the z direction changes from the second resistance value R2 to the first resistance value R1. In other words, corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer from the second intensity to the first intensity, the resistance value of the light detection element 10 in the z direction changes from the second resistance value R2 to the first resistance value R1.

[0076] In any mechanism, when the photosensing element 10 according to the first embodiment operates in the first pattern, the resistance value in the stacking direction of the photosensing element 10 changes corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer 1. That is, corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer 1, the output voltage from the photosensing element 10 changes. As a result, the photosensing element 10 can convert the change in the intensity of the optical signal L1 into a change in the resistance value in the z direction of the photosensing element 10, that is, a change in the output voltage from the photosensing element 10. In the examples shown in FIGS. 6 and 7, the resistance value in the stacking direction of the photosensing element 10, that is, the output voltage from the photosensing element 10, has a value corresponding to the intensity of the light irradiated on the first ferromagnetic layer 1. The output voltage signal from the photosensing element 10 representing the resistance value in the z direction of the photosensing element 10 is sent to the signal processing unit 11. When the output voltage from the photosensing element 10 (the resistance value in the z direction of the photosensing element 10) is equal to or greater than the threshold value, it is processed as a first signal (for example, "1"), and when it is less than the threshold value, it is processed as a second signal (for example, "0"). That is, the receiving device 100 receives the optical signal L1 based on the output voltage from the photosensing element 10 (the resistance value in the z direction of the photosensing element 10).

[0077] FIGS. 8 and 9 are diagrams for explaining the operation of the second pattern of the photosensing element 10 according to the first embodiment. FIG. 8 is a diagram for explaining the first mechanism, and FIG. 9 is a diagram for explaining the second mechanism. The upper graphs in FIGS. 8 and 9 have the intensity of the light irradiated on the first ferromagnetic layer 1 on the vertical axis and time on the horizontal axis. The lower graphs in FIGS. 8 and 9 have the resistance value in the z direction of the photosensing element 10 on the vertical axis and time on the horizontal axis.

[0078] The difference between the second pattern and the first pattern is that in the initial state, the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are in an antiparallel state, and the operating principle is the same as that of the first pattern.

[0079] First, in a state where the first ferromagnetic layer 1 is irradiated with light of the first intensity, the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are in an antiparallel state. The resistance value of the light detection element 10 in the z direction shows the first resistance value R1', and the magnitude of the output voltage from the light detection element 10 shows the first value. In the case of the second pattern shown in FIGS. 8 and 9, it is preferable that the sense current Is flows from the second ferromagnetic layer 2 toward the first ferromagnetic layer 1. By flowing the sense current Is in this direction, a spin transfer torque in the direction opposite to the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1, and in the initial state, the magnetization M1 and the magnetization M2 become antiparallel. In the second pattern, by reversing the direction of the sense current Is from the first pattern, the magnetization direction (magnetization stable direction) of the first ferromagnetic layer 1 in the initial state is reversed.

[0080] Next, the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity. The second intensity is greater than the first intensity, and the magnetization M1 of the first ferromagnetic layer 1 changes from the initial state. For example, as shown in FIG. 8, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the magnetization M1 tilts with respect to the z direction. Also, for example, as shown in FIG. 9, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the magnitude of the magnetization M1 decreases. When the magnetization M1 of the first ferromagnetic layer 1 changes, the resistance value of the light detection element 10 in the z direction shows the second resistance value R2', and the magnitude of the output voltage from the light detection element 10 shows the first value. That is, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the resistance value of the light detection element 10 in the z direction changes from the first resistance value R1' to the second resistance value R2'. In other words, corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer from the first intensity to the second intensity, the resistance value of the light detection element 10 in the z direction changes from the first resistance value R1' to the second resistance value R2'. The second resistance value R2' is smaller than the first resistance value R1', and the second value of the output voltage is smaller than the first value. The second resistance value R2' is between the resistance value (the first resistance value R1') when the magnetization M1 and the magnetization M2 are antiparallel and the resistance value (the first resistance value R1 in FIG. 6) when the magnetization M1 and the magnetization M2 are parallel.

[0081] A spin transfer torque in a direction opposite to the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1. Therefore, in the case shown in FIG. 8, the magnetization M1 tilted from the initial state returns to the initial state when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the second intensity to the first intensity. In the case shown in FIG. 9, when the intensity of the light irradiated on the first ferromagnetic layer 1 returns to the first intensity, the magnitude of the magnetization M1 of the first ferromagnetic layer 1 returns to its original value, and the photo-detection element 10 returns to the initial state. When the magnetization M1 returns to the initial state, the resistance value in the z direction of the photo-detection element 10 returns to the first resistance value R1'. That is, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the resistance value in the z direction of the photo-detection element 10 changes from the second resistance value R2' to the first resistance value R1'. In other words, corresponding to the change in the intensity of the light from the second intensity to the first intensity irradiated on the first ferromagnetic layer, the resistance value in the z direction of the photo-detection element 10 changes from the second resistance value R2' to the first resistance value R1'.

[0082] In any mechanism, when the photo-detection element 10 according to the first embodiment operates in the second pattern, the resistance value in the stacking direction of the photo-detection element 10 changes corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer 1. That is, corresponding to the change in the intensity of the light irradiated on the first ferromagnetic layer 1, the output voltage from the photo-detection element 10 changes. As a result, the photo-detection element 10 can convert the change in the intensity of the optical signal L1 into a change in the resistance value in the z direction of the photo-detection element 10, that is, a change in the output voltage from the photo-detection element 10. In the examples shown in FIGS. 8 and 9, the resistance value in the stacking direction of the photo-detection element 10, that is, the output voltage from the photo-detection element 10, is a value corresponding to the intensity of the light irradiated on the first ferromagnetic layer 1. The output voltage signal from the photo-detection element 10 representing the resistance value in the z direction of the photo-detection element 10 is sent to the signal processing unit 11, and when the output voltage from the photo-detection element 10 (the resistance value in the z direction of the photo-detection element 10) is equal to or greater than the threshold value, it is processed as a first signal (for example, "1"), and when it is less than the threshold value, it is processed as a second signal (for example, "0"). That is, the receiving device 100 receives the optical signal L1 based on the output voltage from the photo-detection element 10 (the resistance value in the z direction of the photo-detection element 10).

[0083] By applying a bias that acts to direct the magnetization M1 of the first ferromagnetic layer 1 in a direction either parallel or antiparallel to the direction of the magnetization M2, the resistance value of the light detection element 10, that is, the output voltage from the light detection element 10, can be changed in response to a change in the intensity of the light irradiated on the first ferromagnetic layer 1. In the examples of the first pattern and the second pattern described above, the application effect of the spin transfer torque by the sense current Is is used as the bias application effect. As the bias application effect, it is not limited to the application effect of the spin transfer torque by the sense current Is, and for example, another bias application effect as shown in the second to fourth modification examples described later may be used.

[0084] Here, it is conceivable that the orientation directions of the magnetization M1 and the magnetization M2 in the initial state are not oriented in the correct direction due to external factors such as an external magnetic field and heat. Therefore, before operating the light detection element 10 according to the first embodiment, a reset current may be applied in the z direction of the light detection element 10.

[0085] The reset current is a current having a current density sufficient to invert the magnetization M1 of the first ferromagnetic layer 1. In the case of the first pattern, the reset current flows from the first ferromagnetic layer 1 toward the second ferromagnetic layer 2. In the case of the second pattern, the reset current flows from the second ferromagnetic layer 2 toward the first ferromagnetic layer 1. When a reset current flows in the z direction of the light detection element 10, a spin transfer torque (STT) is applied to the magnetization M1, and the magnetization M1 of the first ferromagnetic layer 1 is oriented in the correct direction. In each pattern, the value of the reset current is larger than the value of the sense current.

[0086] So far, the case where the light irradiated on the first ferromagnetic layer 1 has two levels of the first intensity and the second intensity has been described as an example. However, the light detection element 10 according to the first embodiment can also read multi-valued information from the optical signal L1 by increasing the intensity of the light irradiated on the first ferromagnetic layer 1 to more than two levels.

[0087] Figures 10 and 11 show the behavior of the photosensor 10 when outputting multiple values using the photosensor 10 according to the first embodiment. Figure 10 is a diagram for explaining the first mechanism, and Figure 11 is a diagram for explaining the second mechanism. Figures 10 and 11 represent the magnetization state and the resistance value in the z direction of the photosensor 10 at the first intensity, the second intensity, the third intensity, and the fourth intensity in order from the left. The intensity of the light irradiated on the first ferromagnetic layer 1 becomes stronger in the order of the fourth intensity, the third intensity, the second intensity, and the first intensity. The first intensity may be zero for the intensity of the irradiated light.

[0088] As shown in Figure 10, when the magnetization M1 tilts according to the intensity of the irradiated light, the angular change from the initial state of the magnetization M1 becomes larger as the intensity of the light irradiated on the first ferromagnetic layer 1 becomes larger. The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the state where the first ferromagnetic layer 1 is not irradiated with light including the optical signal L1 and the directions of the respective magnetizations M1 of the second intensity, the third intensity, and the fourth intensity are all larger than 0° and smaller than 90°. The change in the resistance value of the photosensor 10 in the z direction with respect to the initial state becomes larger as the angular change from the initial state of the magnetization M1 becomes larger. In the example shown in Figure 10, the resistance value of the photosensor 10 in the z direction becomes larger as the angular change from the initial state of the magnetization M1 becomes larger. Therefore, the resistance value of the photosensor 10 in the z direction is different for each of the first intensity, the second intensity, the third intensity, and the fourth intensity. The photosensor 10 according to the first embodiment can read out, for example, 4-value information of "0", "1", "2", and "3" by defining the threshold value of the output voltage (threshold value of the resistance value) in multiple steps. Although the case of reading out 4 values is shown here as an example, the number of values to be read out can be freely designed by setting the threshold value of the output voltage (threshold value of the resistance value). It is preferable that the magnetization M1 of the first ferromagnetic layer 1 does not reverse by the irradiation of the light including the optical signal L1 onto the first ferromagnetic layer 1.

[0089] Similarly, in the case of Fig. 11, when the intensity of the light irradiated on the first ferromagnetic layer 1 increases, the magnitude of the magnetization M1 of the first ferromagnetic layer 1 decreases from the initial state due to the external energy by the light irradiation. When the magnetization M1 of the first ferromagnetic layer 1 decreases from the initial state, the resistance value in the z direction of the photodetector 10 changes. For example, according to the magnitude of the magnetization M1 of the first ferromagnetic layer 1, the resistance value in the z direction of the photodetector 10 changes to the second resistance value R2, the third resistance value R3, and the fourth resistance value R4. Therefore, similarly to the case of Fig. 10, the difference in the output voltage from the photodetector 10 can be output as multi-valued or analog data.

[0090] Also, here, the case where the magnetization M1 and the magnetization M2 are parallel in the initial state has been described as an example, but the magnetization M1 and the magnetization M2 may be antiparallel in the initial state. Similarly to Fig. 10, when the magnetization M1 tilts according to the intensity of the irradiated light, the resistance value in the z direction of the photodetector 10 becomes smaller as the angular change of the magnetization M1 from the initial state becomes larger.

[0091] Next, the operation when an abnormality occurs in the photodetector 10 will be described. Fig. 12 shows the behavior of the photodetector 10 when an abnormality occurs in the photodetector 10 according to the first embodiment. The upper graph in Fig. 12 has the intensity of the light irradiated on the first ferromagnetic layer 1 on the vertical axis and time on the horizontal axis. The lower graph in Fig. 12 has the resistance value in the z direction of the photodetector 10 on the vertical axis and time on the horizontal axis.

[0092] Fig. 12 is an example when an abnormality occurs when the photodetector 10 is operating in the first pattern. As an example of the abnormality, a case where the intensity of a part of the optical signal L1 irradiated on the first ferromagnetic layer 1 becomes abnormally strong is shown. The abnormality is not limited to the case where the intensity of the light becomes excessive, and may be, for example, a change in the operating temperature, a change in the intensity of the applied external magnetic field, etc. When the operating temperature or the external magnetic field changes, the stability of the magnetization M1 also changes.

[0093] When the photodetector element 10 operates normally in the first pattern, the resistance value of the photodetector element 10 in the z direction changes between the first resistance value R1 and the second resistance value R2. On the other hand, when the first ferromagnetic layer 1 is irradiated with excessive light, the magnetization M1 may tilt greatly from the initial state and the magnetization M1 may be reversed. In this case, the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 become antiparallel, and the resistance value becomes the third resistance value R3 (the same as the first resistance value R1' in the second pattern). The third resistance value R3 is larger than the first resistance value R1 and the second resistance value R2, and an abnormality is detected.

[0094] When an abnormality occurs in the photodetector element 10, the above-described reset current is applied. By applying the reset current, the magnetization M1 of the first ferromagnetic layer 1 returns to the correct direction, and the photodetector element 10 can be used normally again. Here, the first mechanism has been described, but the same principle also holds for the second mechanism. In the case of the second mechanism, when the first ferromagnetic layer 1 is irradiated with excessive light, the magnetization M1 may decrease greatly from the initial state and the magnetization M1 may be reversed.

[0095] As described above, the transceiver 300 and the receiver 100 according to the first embodiment receive an optical signal based on the output voltage from the photodetector element 10 (the resistance value of the photodetector element 10). Further, the photodetector element 10 according to the first embodiment can convert a change in the intensity of the optical signal L1 into a change in the output voltage from the photodetector element 10 (a change in the resistance value of the photodetector element 10 in the z direction) and can support high-speed communication.

[0096] Also, as described above, the magnetization M1 of the first ferromagnetic layer 1 is more likely to tilt as the volume of the first ferromagnetic layer 1 is smaller. In other words, when the volume of the first ferromagnetic layer 1 is reduced, the magnetization M1 can be tilted even with a small amount of light. That is, the photodetector element 10 according to the first embodiment can receive the optical signal L1 with high sensitivity.

[0097] More precisely, the ease of inclination of the magnetization M1 is determined by the magnitude of the product (KuV) of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 1. The smaller the KuV, the more inclined the magnetization is with a smaller amount of light, and the larger the KuV, the less inclined the magnetization is unless a larger amount of light is applied. That is, the KuV of the first ferromagnetic layer 1 will be designed according to the amount of light irradiated from the outside used in the application. When assuming an extremely small amount of light, such as a very minute amount of light or photon detection, by reducing the KuV of the first ferromagnetic layer, it becomes possible to detect light with such minute amounts of light. Detection of light with such minute amounts of light cannot be achieved with conventional light detection elements, which is a great advantage. That is, in order to reduce the KuV, by reducing the volume of the first ferromagnetic layer 1, that is, by reducing the element area or thinning the film thickness of the first ferromagnetic layer 1, photon detection also becomes possible.

[0098] In addition, the optical detection element 10 according to the first embodiment can receive the optical signal L1 regardless of the wavelength range of the irradiated light. For semiconductor photodetectors using a pn junction, appropriate semiconductor materials differ depending on the wavelength of the irradiated light. For example, InGaAs or the like is used for detecting near-infrared light with a wavelength of 1.3 μm or more and 1.5 μm or less. Also, for example, silicon is used for detecting visible light with a wavelength of 400 nm or more and 800 nm or less.

[0099] FIG. 13 is a diagram showing the simulation results of the sensitivity of the optical detection element 10 (Example) according to the first embodiment and the characteristic levels of a conventional semiconductor photodiode (Comparative Example 1) using InGaAs, which is a curve (approximate curve of sensitivity data of a plurality of known examples), when the wavelength of the irradiated light is 1.5 μm (near-infrared light). FIG. 14 is a diagram showing the simulation results of the sensitivity of the optical detection element 10 (Example) according to the first embodiment and the characteristic levels of a conventional semiconductor photodiode (Comparative Example 2) using silicon, which is a curve (approximate curve of sensitivity data of a plurality of known examples), when the wavelength of the irradiated light is 520 nm (visible light).

[0100] The conditions for the simulation of the embodiment were set as follows. The photodetector element 10 has a square planar shape with a side length of 200 nm and a sheet resistance (RA) of 5 Ωμm 2 and a magnetoresistive change rate (MR change rate) of 65%. The second ferromagnetic layer 2 (magnetization fixed layer) is an alloy layer containing CoFeB with a thickness of 2 nm, the spacer layer 3 is MgO, and the first ferromagnetic layer 1 is an alloy layer containing CoFeB with a thickness of 1.2 nm. The spot diameter of the light irradiated onto the photodetector element 10 was 900 nmφ. The sensitivity on the vertical axis of the graph is the output current amount with respect to the unit light irradiation amount. In the embodiment, the output current amount was converted by dividing the output voltage, which is the potential difference between the first electrode 15 and the second electrode 16, by the minimum resistance value of the photodetector element 10 (in the case of the first mechanism, the resistance value when the magnetizations M1 and M2 are in a parallel state).

[0101] Considering practical constraints (the intensity of the optical signal, compatibility with the peripheral circuit), a sensitivity of 0.5 A / W or more is often required. As shown in FIG. 13, even in Comparative Example 1 using InGaAs suitable for near-infrared light, a high-speed optical signal exceeding 40 GHz cannot be received with good sensitivity. In contrast, the photodetector element 10 according to the embodiment can receive a high-speed signal exceeding 100 GHz with good sensitivity. Also, as shown in FIG. 14, even in Comparative Example 2 using silicon suitable for visible light, only an optical signal less than 3 GHz can be received with good sensitivity, and it cannot handle high-speed signals. In contrast, the photodetector element 10 according to the embodiment can receive a high-speed signal exceeding 100 GHz with good sensitivity, similar to the case of near-infrared light.

[0102] That is, the photodetector element 10 according to the first embodiment can receive a high-speed optical signal with good sensitivity regardless of visible light or near-infrared light. Here, examples of visible light and near-infrared light are shown, but it is not limited to this example. For example, even for ultraviolet light with a wavelength of 200 nm or more and less than 400 nm, the photodetector element 10 can similarly respond at high speed.

[0103] As described above, the first embodiment has been described in detail with reference to the drawings, but the first embodiment is not limited to this example.

[0104] (First Modification Example) FIG. 15 is a circuit diagram of the transmission / reception device 301 according to the first modification example. The transmission / reception device 301 according to the first modification example is different from the transmission / reception device 300 in that the reception device 101 has an analog-to-digital converter AD. The same components as those in FIG. 3 are denoted by the same reference numerals and the description thereof is omitted.

[0105] The analog-to-digital converter AD is between the first electrode 15 and the output terminal P out and. The analog-to-digital converter AD converts the output voltage from the photodetector 10 (the resistance value of the photodetector 10 in the z direction) into digital data. That is, the transmission / reception device 301 according to the first modification example is less susceptible to the influence of noise and the like. The transmission / reception device 301 according to the first modification example can be particularly preferably used when the photodetector 10 outputs multiple values.

[0106] (Second Modification Example) FIG. 16 is a cross-sectional view of the photodetector according to the second modification example and its periphery cut along a plane in the z direction. FIG. 17 is a cross-sectional view of the photodetector according to the second modification example and its periphery cut along the xy plane passing through the first ferromagnetic layer 1. The reception device according to the second modification example further includes a hard bias layer 40 that applies a bias magnetic field to the first ferromagnetic layer 1. The same components as those in FIG. 5 are denoted by the same reference numerals and the description thereof is omitted.

[0107] The hard bias layer 40 is located at a position overlapping the first ferromagnetic layer 1 when viewed from any direction orthogonal to the z direction. There is a sidewall insulating layer 9 between the hard bias layer 40 and the first ferromagnetic layer 1. As shown in FIG. 17, the hard bias layer 40 surrounds, for example, the periphery of the first ferromagnetic layer 1. There may be a plurality of hard bias layers 40 sandwiching the first ferromagnetic layer 1 in any direction within the xy plane, for example.

[0108] The hard bias layer 40 is a hard magnetic material. The hard bias layer 40 is, for example, a CoPt alloy, a CoPtCr alloy, an FePt alloy, or a laminated film in which Co layers and Pt layers are alternately laminated. The film thickness of the hard bias layer 40 is, for example, 2 nm or more and 30 nm or less. The shortest width of the hard bias layer 40 in the xy plane is, for example, 10 nm or more and 500 nm or less.

[0109] The hard bias layer 40 has an easy axis of magnetization in the same direction as the first ferromagnetic layer 1. The magnetization direction of the magnetization M40 of the hard bias layer 40 is opposite to the magnetization direction of the magnetization M1 of the first ferromagnetic layer 1 in a state where no light is irradiated. The hard bias layer 40 may be a in-plane magnetization film or a perpendicular magnetization film.

[0110] The leakage magnetic field generated from the hard bias layer 40 acts on the magnetization M1 as a bias magnetic field applied to the first ferromagnetic layer 1. In the case of the first pattern described above, the magnetization M1 and the magnetization M2 are parallel in the initial state. In the case of the second pattern described above, the magnetization M1 and the magnetization M2 are antiparallel in the initial state. Further, the leakage magnetic field generated from the hard bias layer 40 prevents the magnetization M1 of the first ferromagnetic layer 1 from reversing during operation. That is, the application of the leakage magnetic field generated from the hard bias layer 40 to the first ferromagnetic layer 1 produces a bias application effect on the magnetization M1 of the first ferromagnetic layer 1.

[0111] (Third Modified Example) FIG. 18 is a cross-sectional view of the optical detection element according to the third modified example cut along a plane along the z direction. The optical detection element according to the third modified example further includes a wiring layer 50. The same components as those in FIG. 5 are denoted by the same reference numerals and the description thereof is omitted.

[0112] The wiring layer 50 is between the first electrode 15 and the first ferromagnetic layer 1. The wiring layer 50 extends in any direction in the xy plane.

[0113] When a current flows along the wiring layer 50, a spin current is generated by the spin Hall effect, and spins are injected into the first ferromagnetic layer 1. The spins injected into the first ferromagnetic layer 1 apply a spin-orbit torque (SOT) to the magnetization M1 of the first ferromagnetic layer 1.

[0114] The wiring layer 50 contains, for example, a non-magnetic heavy metal as a main element. The main element is the element with the highest proportion among the elements constituting the wiring layer 50. The wiring layer 50 contains, for example, a heavy metal having a specific gravity of yttrium (Y) or more. Since the non-magnetic heavy metal has a large atomic number of 39 or more and has d electrons or f electrons in the outermost shell, strong spin-orbit interaction occurs. The wiring layer 50 contains, for example, any one selected from the group consisting of Pt, W, Ta, Au, Hf, Mo. In particular, Pt, W, Ta, etc. are more preferable elements. In order to increase the spin-orbit interaction effect, it is preferable to use a β-phase crystal structure for W and Ta. The film thickness of the wiring layer 50 is preferably 1 to 10 nm, and more preferably 1 to 5 nm.

[0115] By flowing a current through the wiring layer 50, spins are injected from the wiring layer 50 into the first ferromagnetic layer 1, and a bias application effect on the magnetization M1 of the first ferromagnetic layer 1 occurs. By changing the direction of the current flowing through the wiring layer 50, the direction of the spins injected from the wiring layer 50 into the first ferromagnetic layer 1 can be changed, and the direction of the magnetization M1 of the first ferromagnetic layer 1 in the initial state (the magnetization stable direction of the magnetization M1) can be changed. Depending on the direction of the spins injected from the wiring layer 50 into the first ferromagnetic layer 1, in the case of the first pattern described above, the magnetization M1 and the magnetization M2 are parallel in the initial state, and in the case of the second pattern described above, the magnetization M1 and the magnetization M2 can be controlled to be anti-parallel in the initial state. Also, the spins injected from the wiring layer 50 into the first ferromagnetic layer 1 prevent the magnetization M1 of the first ferromagnetic layer 1 from reversing during operation. The direction of the spins injected from the wiring layer 50 into the first ferromagnetic layer 1 can be freely controlled by the direction of the current flowing along the wiring layer 50.

[0116] (Fourth Modification Example) FIG. 19 is a cross-sectional view of the receiving device 102 according to the fourth modification, taken along a plane along the z direction. FIG. 20 is a plan view of the receiving device 102 according to the fourth modification, viewed from the z direction. The receiving device 102 according to the fourth modification further includes a soft magnetic body 60. The same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

[0117] The soft magnetic body 60 is a magnetic shield. In a plan view from the z direction, the soft magnetic body 60 covers at least a part of the outer periphery of the light detection element 10 from the outside. When viewed from any direction in the xy plane, the soft magnetic body 60 overlaps at least a part of the first ferromagnetic layer 1. For example, in a plan view of the light detection element from the z direction, the soft magnetic body 60 covers the entire outer periphery of the light detection element 10. When viewed from any direction in the xy plane, the soft magnetic body 60 overlaps with all of the z-direction outer periphery of the first ferromagnetic layer 1.

[0118] The soft magnetic body 60 is, for example, a metal or alloy containing at least one of Fe, Ni, and Co. The soft magnetic body 60 is, for example, a NiFe alloy. The soft magnetic body 60 may be a magnetic body having insulating properties. The soft magnetic body 60 is, for example, a ceramic such as ferrite. The soft magnetic body 60 is, for example, a rare earth iron garnet (RIG). Yttrium iron garnet (YIG) is an example of a rare earth iron garnet (RIG).

[0119] The soft magnetic body 60 can suppress the application of an external magnetic field to the first ferromagnetic layer 1 and suppress the first ferromagnetic layer 1 from exhibiting unexpected behavior.

[0120] (Fifth Modification) FIG. 21 is a cross-sectional view of the receiving device 103 according to the fifth modification, taken along a plane along the z direction. FIG. 22 is a plan view of the receiving device 103 according to the fifth modification, viewed from the z direction. The receiving device 103 according to the fifth modification further includes a soft magnetic body 61. The same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

[0121] The soft magnetic body 61 is a magnetic shield. The soft magnetic body 61 is different from the soft magnetic body 60 in that it is also above and below the light detection element 10. The soft magnetic body 61 surrounds the periphery of the light detection element 10 except for the opening 62. The soft magnetic body 61 can use the same material as the soft magnetic body 60.

[0122] The soft magnetic body 61 has an opening 62 above it, which is the light incident side to the light detection element 10. The opening 62 is formed on the side of the first ferromagnetic layer 1 among the soft magnetic bodies 61 above and below the light detection element 10. There is a mesh-shaped magnetic net 63 connected to the soft magnetic body 61 in the opening 62. The magnetic net 63 contains a magnetic material, for example, the same material as the soft magnetic body 61.

[0123] The wiring connected to the first electrode 15 and the second electrode 16 is connected to an external contact provided outside the soft magnetic body 61 with an insulating layer 64 interposed therebetween.

[0124] By providing the soft magnetic body 61 above and below the light detection element 10, the magnetic shielding effect is further enhanced. Also, by providing the opening 62 in the soft magnetic body 61, light having the optical signal L1 can be efficiently irradiated onto the first ferromagnetic layer 1. Furthermore, by providing the magnetic net 63 in the opening 62, intrusion of an external magnetic field from the opening 62 can be suppressed.

[0125] (Sixth Modification Example) FIG. 23 is a cross-sectional view of the receiving device 104 according to the sixth modification example. The same components as those in FIG. 4 are denoted by the same reference numerals and the description thereof is omitted.

[0126] In the receiving device 104 according to the sixth modification example, the light detection element 10 is formed on the substrate Sb. In the receiving device 104 according to the sixth modification example, the integrated circuit 20 may be formed in the peripheral portion of the substrate Sb where the light detection element 10 is not formed, or may be formed outside the substrate. The integrated circuit 20 is connected to the light detection element 10 via wiring.

[0127] "Second Embodiment" The receiving device according to the second embodiment has an operation of the photodetector element different from that of the receiving device 100 according to the first embodiment. The element configuration of the receiving device according to the second embodiment is the same as that of the receiving device according to the first embodiment.

[0128] FIG. 24 is a diagram for explaining the operation of the receiving device according to the second embodiment. The receiving device according to the second embodiment uses, as a first signal (for example, “1”), the fact that the output voltage from the photodetector element 10 (the resistance value in the z direction of the photodetector element 10) changes within a predetermined time, and uses, as a second signal (for example, “0”), the fact that the output voltage from the photodetector element 10 (the resistance value in the z direction of the photodetector element 10) does not change within a predetermined time. The predetermined time is determined by the modulation frequency of the optical signal.

[0129] Hereinafter, based on the example shown in FIG. 24, the operation of the receiving device according to the second embodiment will be specifically described. First, the optical signal irradiated to the photodetector element 10 is defined. The optical signal is defined as “1” when the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the first intensity to the second intensity, and as “0” when the intensity of the light irradiated to the first ferromagnetic layer 1 is maintained at the first intensity over a predetermined time. The intensity of the light that has changed from the first intensity to the second intensity returns to the first intensity after a certain period of time.

[0130] The optical signal is irradiated to the first ferromagnetic layer 1 of the photodetector element 10. When the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the first intensity to the second intensity, the magnetization M1 of the first ferromagnetic layer 1 is reversed. When the intensity of the light irradiated to the first ferromagnetic layer 1 returns from the second intensity to the first intensity, the magnetization M1 of the first ferromagnetic layer 1 is not reversed. The resistance value in the z direction of the photodetector element changes from a low resistance R L to a high resistance R H or from a high resistance R H to a low resistance R LIt changes to. That is, when the intensity of the light irradiated on the first ferromagnetic layer 1 changes from the first intensity to the second intensity, regardless of whether the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are parallel or anti-parallel, in any case, the resistance value of the photosensor 10, that is, the output voltage from the photosensor 10 changes. That is, when the information of "1" is input as an optical signal, the output voltage (resistance value of the photosensor 10) from the photosensor 10 changes. By setting that the output voltage (resistance value in the z direction of the photosensor 10) from the photosensor 10 changes within a predetermined time as "1", the receiving device according to the second embodiment can receive the optical signal of "1" as a signal of "1" based on the output voltage (resistance value of the photosensor 10) from the photosensor 10.

[0131] On the other hand, when the first ferromagnetic layer 1 of the photosensor 10 is not irradiated with light or the intensity of the irradiated light is small, the magnetization M1 of the first ferromagnetic layer 1 maintains its state. Therefore, when the intensity of the light irradiated on the first ferromagnetic layer 1 is maintained at the first intensity over a predetermined time, the resistance value in the z direction of the photosensor 10, that is, the output voltage from the photosensor 10 does not change. That is, when the information of "0" is input as an optical signal, the output voltage (resistance value of the photosensor) from the photosensor 10 does not change. By setting that the output voltage (resistance value in the z direction of the photosensor 10) from the photosensor 10 does not change within a predetermined time as "0", the receiving device according to the second embodiment can receive the optical signal of "0" as a signal of "0" based on the output voltage (resistance value of the photosensor 10) from the photosensor 10.

[0132] As described above, the receiving device according to the second embodiment can receive an optical signal based on the presence or absence of a change in the output voltage (change in the resistance value in the z direction of the photosensor) from the photosensor 10 within a predetermined time. Also, the photosensor according to the second embodiment detects the resistance change between the case where the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are parallel and the case where they are anti-parallel, and the amount of change in the output voltage is large.

[0133] Note that in the second embodiment, the direction of the sense current flowing through the light detection element may be either from the first ferromagnetic layer 1 to the second ferromagnetic layer 2 or from the second ferromagnetic layer 2 to the first ferromagnetic layer 1. In the third embodiment, it is preferable that the value of the sense current is small so that the spin transfer torque due to the sense current does not become too large. Also, in the second embodiment, it does not matter whether the state in which the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are parallel or the state in which they are antiparallel is the initial state, so it is not necessary to apply a reset current.

[0134] As described above, the second embodiment has been described in detail with reference to the drawings, but the second embodiment is not limited to this example. For example, the first modification example, the fourth modification example, the fifth modification example, the sixth modification example, etc. shown in the first embodiment can be applied.

[0135] So far, taking the first embodiment and the second embodiment as examples, an example of applying the transmission and reception device to the communication system 1000 shown in FIG. 1 has been shown, but the communication system is not limited to this case.

[0136] For example, FIG. 25 is a conceptual diagram of another example of a communication system. The communication system 1001 shown in FIG. 25 is for communication between two mobile terminal devices 500. The mobile terminal device 500 is, for example, a smartphone, a tablet, or the like.

[0137] Each of the mobile terminal devices 500 includes a receiving device 100 and a transmitting device 200. An optical signal transmitted from the transmitting device 200 of one mobile terminal device 500 is received by the receiving device 100 of the other mobile terminal device 500. The light used for transmission and reception between the mobile terminal devices 500 is, for example, visible light. As the light detection element 10 of each receiving device 100, any of the light detection elements according to the first embodiment and the second embodiment is applicable.

[0138] For example, FIG. 26 is a conceptual diagram of another example of a communication system. The communication system 1002 shown in FIG. 26 is for communication between a mobile terminal device 500 and an information processing device 600. The information processing device 600 is, for example, a personal computer.

[0139] The mobile terminal device 500 includes a transmission device 200, and the information processing device 600 includes a reception device 100. The optical signal transmitted from the transmission device 200 of the mobile terminal device 500 is received by the reception device 100 of the information processing device 600. The light used for transmission and reception between the mobile terminal device 500 and the information processing device 600 is, for example, visible light. As the light detection element 10 of each reception device 100, any of the light detection elements according to the first to third embodiments is applied.

[0140] As described above, the present invention is not limited to the above embodiments and modifications, and various modifications and changes are possible within the scope of the gist of the present invention described within the scope of the claims.

Description of Reference Numerals

[0141] 1... First ferromagnetic layer, 2... Second ferromagnetic layer, 3... Spacer layer, 4... Third ferromagnetic layer, 5... Magnetic coupling layer, 6... Underlayer, 7... Vertical magnetization induction layer, 8... Cap layer, 9... Sidewall insulating layer, 10... Light detection element, 11... Signal processing unit, 15... First electrode, 16... Second electrode, 20... Integrated circuit, 30... Interlayer insulating film, 40... Hard bias layer, 50... Wiring layer, 60, 61... Soft magnetic body, 62... Opening, 63... Magnetic grid, 64... Insulating layer, 100, 101, 102, 103... Reception device, 200... Transmission device, 201... Light source, 202... Electric signal generation element, 203... Optical modulation element, 300, 301... Transmission and reception device, 500... Mobile terminal device, 600... Information processing device, 1000, 1001, 1002... Communication system, AD... Analog-to-digital converter, FB... Fiber, G... Ground, Is... Sense current, M1, M2, M40... Magnetization, P G ... Reference potential terminal, P in ... Input terminal, P out ... Output terminal, PS... Power supply, w... Through wiring

Claims

1. A magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, wherein light including an optical signal having a light intensity change is irradiated onto the first ferromagnetic layer, the optical signal is received based on an output voltage from the magnetic element, and a magnetization of the first ferromagnetic layer in a state where the first ferromagnetic layer is irradiated with the light is smaller than a magnetization of the first ferromagnetic layer in a state where the first ferromagnetic layer is not irradiated with the light, a light detection element.

2. A magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, wherein light including an optical signal having a light intensity change is irradiated onto the first ferromagnetic layer, the optical signal is received based on an output voltage from the magnetic element, and when an output voltage from the magnetic element is equal to or higher than a threshold value, it is processed as a first signal, and when it is less than the threshold value, it is processed as a second signal, a light detection element.

3. A magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, wherein an output voltage changes based on an intensity of light irradiated onto the first ferromagnetic layer, and a magnetization of the first ferromagnetic layer in a state where the first ferromagnetic layer is irradiated with the light is smaller than a magnetization of the first ferromagnetic layer in a state where the first ferromagnetic layer is not irradiated with the light, a light detection element.

4. A light detection element including a stacked film including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and a hard bias layer that applies a bias magnetic field to the first ferromagnetic layer, wherein the stacked film is configured to convert an intensity of light irradiated onto the first ferromagnetic layer into an output voltage from the stacked film based on the intensity, the hard bias layer is located at a position overlapping the stacked film when viewed in the stacking direction of the stacked film, and a magnetization direction of the hard bias layer is opposite to a magnetization direction of the first ferromagnetic layer in a state where the first ferromagnetic layer is not irradiated with the light.

5. A light detection element including a stacked film including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and a soft magnetic material, wherein the stacked film is configured to convert an intensity of light irradiated onto the first ferromagnetic layer into an output voltage from the stacked film based on the intensity, The soft magnetic body is a light detection element that covers at least a part of the outer periphery of the laminated film from the outside in a plan view from the lamination direction of the laminated film. **Claim 6** A laminated film including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; An integrated circuit; and The laminated film is configured to convert the intensity of light irradiated to the first ferromagnetic layer into an output voltage from the laminated film based on the intensity. The integrated circuit and the laminated film are formed on the same substrate with an interlayer insulating film therebetween. A light detection element in which the integrated circuit and the laminated film are connected through a through-wiring penetrating the interlayer insulating film. **Claim 7** A receiving apparatus including the light detection element according to any one of claims 1 to 6.

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