JP2015138098A - Magnetoresistance effect element and spatial light modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistance effect element capable of reducing a switching current, and to provide a spatial light modulator using the magnetoresistance effect element.SOLUTION: A magnetoresistance effect element 120 includes: electrodes 121, 127 formed on a back plane 110; insulator layers 141, 142, 143 formed on peripheries of respective electrodes so as to insulate the electrodes 121, 127; a magnetization fixing layer 122 formed on the electrode 121; a magnetization fixing layer 126 formed on the electrode 127; an intermediate layer 123 formed on the magnetization fixing layer 122; an intermediate layer 125 formed on the magnetization fixing layer 126; and an optical modulation layer 124 formed on the intermediate layers 123, 125. A magnetization direction of the magnetization fixing layer 122 and a magnetization direction of the magnetization fixing layer 126 are antiparallel each other, light made incident on the optical modulation layer 124 is modulated by a magnetoresistance effect and a field application electrode 150 is formed oppositely to the optical modulation layer 124 through the insulator layer 143.

Description

  The present invention relates to a spatial light modulator (SLM) using a magneto-optic effect that can modulate a Kerr rotation angle by a magnetic Kerr effect into a binary state.

Optical elements that spatially modulate the phase and amplitude of light are applied to image exposure apparatuses such as holography, and are widely used in fields such as display technology and recording technology. In addition, since optical information can be processed in two dimensions in parallel, application to optical information processing technology and the like has been studied.
In recent years, a spin that injects spin by supplying current to a magnetoresistive effect element in a spatial light modulator (hereinafter also referred to as SLM as appropriate) using a magneto-optical effect. An injection type SLM (for example, Patent Document 1) and a domain wall drive type SLM for driving a domain wall (for example, see Patent Document 2) are known.

  In the case of the spin injection type SLM disclosed in Patent Document 1, as shown in FIG. 17, for example, a reflective spatial light modulator 500 includes a magnetoresistive element having a rectangular shape in plan view provided on a substrate 510, and A pair of electrodes are provided on the top and bottom. The magnetoresistive effect element includes, for example, a magnetization fixed layer 530, an intermediate layer 540, and a light modulation layer (magnetization free layer) 550. Each magnetoresistive element arranged in a two-dimensional array on the substrate functions as a pixel. An insulator 580 is interposed between adjacent magnetoresistive elements. In a magnetic film such as a magnetization fixed layer or a light modulation layer, cross-sectional hatching is omitted in order to make the direction of magnetization easier to see. In other drawings, some hatchings are omitted for the same purpose.

  Here, the upper electrode is provided with a window 571 provided on each of the linear metal electrodes 570 at positions facing the arranged magnetoresistive elements, and the window 571 is made of IZO, ITO or the like to transmit light. A transparent electrode 560 is used. The transparent electrode 560 is not hatched. The lower electrode 520 is a linear metal electrode and is disposed orthogonal to the upper electrode. When a current is supplied from the current source 590 to the magnetoresistive effect element between the upper and lower electrodes, spins are injected and the magnetization direction of the light modulation layer 550 is reversed.

This spatial light modulator 500 uses a magnetic Kerr effect to change the polarization state of the emitted light according to the direction of magnetization of the light modulation layer 550 (for example, the initial reflected light from the light modulation layer 550 and the magnetization fixed layer 530). Assuming that the Kerr rotation angle is α and the Kerr rotation angle of the light modulation layer 550 is θ _k1 , it is possible to modulate to (binary values of (θ _k1 + α) and (−θ _k1 + α)). In such a spatial light modulator 500, polarizers (incident polarization means 202, emission polarization means 203) are provided on the incident polarization side and the emission polarization side, respectively, and the polarization planes of these polarizers are set at a predetermined angle with respect to each other. Nicole arrangement.

As shown in FIG. 17, the light emitted from the light source 201 such as a laser contains various polarization components, but is filtered by the incident polarization means 202 so as to include only a polarization component in a certain direction. The plane of polarization of the laser light that has passed through the incident polarization means 202 is rotated depending on the direction of magnetization of the light modulation layer 550. For example, if the magnetization direction of the light modulating layer 550 is the plane of polarization of the laser light reflected when a downward, by the light modulation, theta _k1 only (+ θ _k1) for example clockwise as shown in Figure 17 rotates, Since this reflected light passes through the outgoing polarization means 203, it is in a “bright state”. On the other hand, when the polarization plane of the laser beam reflected when the direction of magnetization of the light modulation layer 550 is upward is rotated by θ _k1 (−θ _k1 ) counterclockwise, for example, as shown in FIG. Since this reflected light does not pass through the outgoing polarization means 203, it is in a “dark state”.

  In the case of the domain wall drive type SLM disclosed in Patent Document 2, as shown in FIG. 18, for example, a reflective spatial light modulator 600 is provided on a substrate 610 and is elongated in a plan view ( Light modulation layer) 630 and a pair of electrodes on the top and bottom. In the domain wall control layer 630, the magnetization is fixed such that the magnetization direction at one end and the magnetization direction at the center are antiparallel to each other. Each domain wall control layer 630 arranged in a two-dimensional array on the substrate functions as a pixel. An insulator 650 is interposed between the adjacent domain wall control layers 630. Here, the upper electrode 640 and the lower electrode 620 are disposed orthogonally. That is, FIG. 18 is a cross-sectional view in an oblique direction of 45 degrees. The domain wall control layer 630 is disposed in an oblique direction so that each end is connected to the upper and lower electrodes, and is elongated in plan view, so that light from above hardly passes through the upper electrode 640 and has a domain wall. The control layer 630 is reached. Therefore, the linear upper electrode 640 does not require a transparent electrode material, and is composed only of a normal electrode material such as Cu. When a current is supplied from the current source 660 to the domain wall control layer 630 between the lower electrode 620 and the upper electrode 640, the domain wall 631 generated between one end and the center of the domain wall control layer 630 becomes the other. Driven to the end side, the magnetization direction of the central portion of the domain wall control layer 630 is reversed.

This spatial light modulator 600 changes the polarization state of outgoing light (outgoing polarized light) according to the direction of magnetization of the domain wall control layer 630 by the magnetic Kerr effect, for example, binary values of (θ _k2 + α) and (−θ _k2 + α). Can be modulated. This spatial light modulator 600 also has a crossed Nicols arrangement in which the polarization planes of the incident polarization means 202 and the emission polarization means 203 are set at a predetermined angle. When the laser light is irradiated from the light source 201, the polarization plane of the laser light is rotated by + θ _k1 by light modulation according to the magnetization direction of the central portion of the domain wall control layer 630, and the light state is obtained. On the other hand, when rotating by −θ _k2 , the dark state is entered.

  However, in the spatial light modulator 600 shown in FIG. 18, the direction of magnetization at the end of the domain wall control layer 630 is anti-parallel to the direction of magnetization at the center, and therefore the aperture of the pixel (domain wall control layer 630). The rate will drop. So far, the inventors of the present application have proposed an SLM that can improve the spin injection SLM and increase the aperture ratio of a desired pixel (see Patent Document 3). In this SLM, each magnetoresistive element arranged in a two-dimensional array on the substrate functions as a pixel.

  The magnetoresistive effect element disclosed in Patent Document 3 is formed around each electrode so as to insulate the first electrode and the second electrode formed on the substrate from each other and the first electrode and the second electrode. An insulating layer formed on the first electrode, a first magnetization fixed layer formed on the first electrode, a second magnetization fixed layer formed on the second electrode, and the first magnetization fixed layer. The formed first intermediate layer, the second intermediate layer formed on the second magnetization fixed layer, and the magnetization free layer (optical modulation) formed on the first intermediate layer and the second intermediate layer Layer). In this magnetoresistive element, light incident on the magnetization free layer is modulated by a magneto-optic effect (Kerr effect). That is, the light incident on the magnetoresistive element from the side opposite to the substrate reaches the magnetization free layer without being passed through the electrode and is diffracted, so that the aperture ratio of the pixel can be increased. In this magnetoresistive effect element, since the magnetization direction of the first magnetization fixed layer and the magnetization direction of the second magnetization fixed layer are antiparallel to each other, it is a kind of double spin injection method, and the spin torque is 2 Doubled. Therefore, the efficiency of spin injection is improved.

  Conventionally, the coercive force control of an ultrathin magnetic film by applying an electric field has been reported as follows (see Patent Document 4 or Non-Patent Documents 1 and 2). In this report, it is said that the electrical state of the magnetic layer changes due to the accumulation of charges at the interface between the magnetic layer (magnetization free layer) and the insulator layer, resulting in a change in the coercivity of the magnetic layer. Yes. For example, Patent Document 4 describes that magnetization reversal control using a coercive force change by voltage is possible under a certain external assist magnetic field. However, the change in coercive force is temporary, and if the voltage is removed, the direction of magnetization returns to the original state. Therefore, as it is, stable switching between binary states of a magnetic memory or the like is achieved. It cannot be used.

Japanese Patent No. 4829850 JP 2010-020114 A JP 2012-78579 A International Publication No. 2009/133650

T. Maruyama, Y. Shiota, T. Nozaki, K. Ohta, N. Toda, M. Mizuguchi, T. Shinjo, M. Shiraishi, S. Mizukami, Y. Ando, and Y. Suzuki: Nat. Nanotechnol. 4 (2009) 158. D. Chiba, M. Kawaguchi, S. Fukami, N. Ishiwata, K. Shimamura, K. Kobayashi and T. Ono: Nat. Commun. 3 (2012) 888.

  The inventors of the present application have proposed SLMs such as a spin injection type in order to miniaturize the SLM and display, for example, a holographic stereoscopic image. The spin injection SLM has room for further improvement in the technique for narrowing the pixel pitch. For example, in the double spin injection type SLM described in Patent Document 3, in order to selectively switch a target pixel (double spin injection type magnetoresistive effect element), for example, a field effect is formed on a silicon substrate. It is necessary to prevent leakage current by using a backplane having a drive circuit such as a transistor (Field effect transistor: FET).

  However, in any of the spin injection SLMs described in Patent Document 1 or Patent Document 3, the current required for operation increases because the magnetization reversal current is high. That is, the switching current is large. Therefore, it has been difficult to reduce the pixel pitch by miniaturizing the MOS-FET or the like formed for each pixel. The reason is that the drain current flowing through the MOS-FET is proportional to W / L, where L is the gate length and W is the gate width. Therefore, it is necessary to increase the gate width W in order to increase the current. Because there is. Therefore, in order to reduce the pixel pitch, it is necessary to further reduce the switching current of the spin injection SLM.

  This invention is made | formed in view of the above problems, and makes it a subject to provide the magnetoresistive effect element and spatial light modulator which can reduce a switching current.

  In order to solve the above-described problems, a magnetoresistive effect element according to the present invention includes a first electrode and a second electrode formed on a substrate, and each electrode is insulated from the first electrode and the second electrode. An insulating layer formed around, a first magnetization fixed layer formed on the first electrode, a second magnetization fixed layer formed on the second electrode, and the first magnetization fixed layer A first intermediate layer formed on the first intermediate layer, a second intermediate layer formed on the second magnetization fixed layer, and a magnetization free layer formed on the first intermediate layer and the second intermediate layer The magnetization direction of the first magnetization fixed layer and the magnetization direction of the second magnetization fixed layer are anti-parallel to each other, and the magnetic field that modulates the light incident on the magnetization free layer by a magnetoresistive effect A resistance effect element, comprising an electrode for applying an electric field through the insulator layer facing the magnetization free layer It is characterized in.

  According to such a configuration, the magnetoresistive element is used for applying an electric field through the insulator layer facing the magnetization free layer (light modulation layer) in addition to the first electrode and the second electrode for injecting spin. It has an electrode. Accordingly, an electric field can be applied from the electric field applying electrode to the magnetization free layer during the spin injection magnetization reversal of the magnetoresistive effect element. When an electric field is applied to the magnetization free layer, charges are accumulated at the interface between the magnetization free layer and the region of the insulator layer interposed between the magnetization free layer and the electric field application electrode. The electronic state of the layer changes, resulting in a change in the coercivity of the magnetization free layer. By applying the electric field in this way, the coercive force of the magnetization free layer is temporarily attenuated, so that the spin injection magnetization can be reversed at a low current density. Therefore, the magnetoresistive effect element according to the present invention can reduce the current required for switching.

  In order to solve the above-described problem, in the spatial light modulator according to the present invention, the magnetoresistive effect element is arranged in a two-dimensional array on a backplane having a selection switching circuit, and the magnetization free layer side is arranged. In this case, polarized light is incident from the light beam and the reflected light or diffracted light is used.

  According to this configuration, the spatial light modulator can apply an electric field from the electric field application electrode to the magnetization free layer (light modulation layer) during the spin injection magnetization reversal of the magnetoresistive effect element selected on the backplane. As a result, the switching current can be reduced. Therefore, an electrically addressed SLM having a fine pixel pitch can be formed. Therefore, it is possible to provide stereoscopic holography (30 degrees or more) having a wide angle (viewing area angle) at which a stereoscopic image can be visually recognized.

Since the magnetoresistive effect element of the present invention includes the electrode for applying an electric field, the pitch at which the plurality of magnetoresistive effect elements are arranged can be reduced.
Further, the spatial light modulator of the present invention can make the pixel pitch narrower than the conventional configuration by arranging a plurality of magnetoresistive elements as pixels in a two-dimensional arrangement.

1 is a plan view schematically showing a spatial light modulator according to a first embodiment of the present invention. 1 is a circuit diagram schematically showing a spatial light modulator according to a first embodiment of the present invention. It is sectional drawing which shows typically the magnetoresistive effect element which concerns on 1st Embodiment of this invention. 1 is a cross-sectional view schematically showing a spatial light modulator according to a first embodiment of the present invention. FIG. 5A to FIG. 5D are explanatory diagrams of the light modulation operation in the spatial light modulation element according to the first embodiment of the present invention. FIG. 6A to FIG. 6D are cross-sectional views (part 1) schematically showing a manufacturing procedure of the spatial light modulator according to the first embodiment of the present invention. FIG. 7A to FIG. 7D are cross-sectional views (part 2) schematically showing the manufacturing procedure of the spatial light modulator according to the first embodiment of the present invention. FIG. 8A to FIG. 8D are cross-sectional views (part 3) schematically showing the manufacturing procedure of the spatial light modulator according to the first embodiment of the present invention. FIG. 9A to FIG. 9D are cross-sectional views (part 4) schematically showing the procedure for manufacturing the spatial light modulator according to the first embodiment of the present invention. FIG. 10A to FIG. 10D are cross-sectional views (part 5) schematically showing the procedure for manufacturing the spatial light modulator according to the first embodiment of the present invention. FIG. 11A to FIG. 11C are cross-sectional views (part 6) schematically showing a manufacturing procedure of the spatial light modulator according to the first embodiment of the present invention. It is a top view which shows typically the spatial light modulator which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically the magnetoresistive effect element which concerns on 2nd Embodiment of this invention. It is a circuit diagram showing typically a spatial light modulator concerning a 2nd embodiment of the present invention. It is sectional drawing which shows typically the experimental sample which simulated the magnetoresistive effect element which concerns on this invention. It is a graph which shows the coercive force when a voltage is applied to the experimental sample shown in FIG. It is sectional drawing which shows typically the 1st prior art example of a reflection type spatial light modulator. It is sectional drawing which shows typically the 2nd prior art example of a reflection type spatial light modulator.

  Hereinafter, the spatial light modulator of the present invention will be described in detail with reference to the drawings. Note that the thickness, size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation.

(First embodiment)
[Configuration of spatial light modulator]
The configuration of the spatial light modulator will be described below with reference to FIGS.
As shown in FIG. 1, the spatial light modulator 100 includes a backplane 110 having a selection switching circuit, a magnetoresistive effect element 120 arranged as a pixel on the backplane 110 as a pixel, and a magnetoresistive effect. And an insulator layer 140 provided around the element 120. The spatial light modulator 100 receives polarized light from the side of the light modulation layer 124 (see FIG. 4) of the magnetoresistive effect element 120 and uses the reflected light or diffracted light.

  Here, FIG. 1 is a schematic plan view of a portion where a 3 × 3 magnetoresistive effect element 120 is disposed on the backplane 110 as an example. Practically, pixel selection means 161, 162, 163, 164 are arranged on the backplane 110. 2 is an equivalent circuit diagram of the SLM formed on the MOS-FET of the backplane 110, FIG. 4 is a schematic cross-sectional view including a light irradiation mechanism, and FIG. It is typical sectional drawing of the backplane 110 corresponding to the magnetoresistive effect element 120). Note that at least one of the write / read power supply 170, the voltage application power supply 180, and the electrical resistance detection means 190 may be mounted on the backplane 110 of FIG.

As the backplane 110, a silicon backplane such as a MOS-FET that functions as a pixel selection circuit, a Si substrate with a thermal oxide film, a SiO ₂ substrate, a MgO substrate, a sapphire substrate, or the like can be used. However, if there is no pixel selection circuit, the switching current of the pixel leaks to other pixels, and the target pixel cannot be reliably driven (inverted), so a substrate with a pixel selection circuit should be used as the substrate. Is desirable.

  In the present embodiment, as shown in FIG. 3, the backplane 110 includes a substrate 111, a first power supply wiring 112, a second power supply wiring 113, an insulator layer 114, a pixel selection signal line 115, and a first selection signal line 115. The bonding wiring 116, the second bonding wiring 117, and the third bonding wiring 118 are provided.

The substrate 111 is provided for forming each wiring layer. As a material of the substrate 111, a known substrate material can be applied. Specifically, SiO ₂ (silicon oxide, glass), MgO (magnesium oxide), sapphire, GGG (gadolinium gallium garnet), SiC (silicon carbide), A Ge (germanium) single crystal substrate or the like can be used. In the present embodiment, as an example, a substrate in which a MOS-FET (source S, drain D, gate G) is formed on the surface layer of a Si substrate is used. Note that each MOS-FET is arranged so that one source region is shared between two adjacent MOS-FETs as in a conventionally known pixel selection switching circuit.

  As a material of each wiring layer provided on the substrate 111, a general electrode material can be applied. Specifically, for example, metals such as Cu, Al, Au, Ag, Ta, and Cr having good conductivity and alloys thereof can be used. As an example, it is preferable to use Cu as the material of each wiring layer. As a method for forming each wiring layer, for example, an electrode material is formed by a known method such as a sputtering method, and a photolithography step and a step such as an etching or lift-off method can be used.

  The first power supply wiring 112 is a linear wiring extending in the row direction for each row of the pixel array on the back plane 110 shown in FIG. As shown in FIG. 3, the first power supply wiring 112 is connected to the source S side of the MOS-FET via the third junction wiring 118 for each pixel in the depth direction.

  The second power supply wiring 113 is a linear wiring extending in the row direction for each row of the pixel array on the back plane 110 shown in FIG. As shown in FIG. 3, the second power supply wiring 113 is connected to the second electrode 127 of the magnetoresistive effect element 120 via the second junction wiring 117 for each pixel in the depth direction.

  The insulator layer 114 insulates the first power supply wiring 112, the second power supply wiring 113, the pixel selection signal line 115, the first bonding wiring 116, the second bonding wiring 117, the third bonding wiring 118, and the like. In order to do so, it is formed around each wiring.

  The pixel selection signal line 115 is a linear wiring extending in the column direction for each column of the pixel array on the back plane 110 shown in FIG. As shown in FIG. 3, the pixel selection signal line 115 functions as a gate G of the MOS-FET for each pixel.

  As shown in FIG. 3, the first junction wiring 116 is provided for each pixel, and connects the drain D side of the MOS-FET and the first electrode 121 of the magnetoresistive effect element 120. That is, the first electrode 121 of the magnetoresistive effect element 120 is connected to the drain D of the corresponding MOS-FET of the backplane 110, and is connected to the first power supply wiring 112 via the source S (FIGS. 1 and 2). 2). On the other hand, the second electrode 127 of the magnetoresistive effect element 120 is connected to the second power supply wiring 113 (see FIGS. 1 and 2). In FIG. 2, the magnetoresistive effect element 120 (pixel) is indicated by a variable resistance symbol.

  As shown in FIGS. 3 and 4, the magnetoresistive effect element 120 (pixel) includes a first electrode 121, a first magnetization fixed layer 122, a first intermediate layer 123, and a light modulation layer (magnetization free layer) 124. A second intermediate layer 125, a second magnetization fixed layer 126, a second electrode 127, an insulator layer 140, and an electric field applying electrode 150. The magnetoresistive effect element 120 modulates the light incident on the light modulation layer 124 by the magnetoresistive effect. In the following description, the insulator layer 140 will be described in order from the backplane 110 side by distinguishing the three layers of the first insulator layer 141, the second insulator layer 142, and the third insulator layer 143. You may form integrally with the same material, and you may form with a mutually different material. Hereinafter, unless otherwise distinguished, it is expressed as an insulator layer 140.

As shown in FIG. 3, the first electrode 121 and the second electrode 127 are formed on the backplane 110. An insulator layer 140 is formed around each electrode so as to insulate the first electrode 121 and the second electrode 127.
The first magnetization fixed layer 122 is formed on the first electrode 121, and the second magnetization fixed layer 126 is formed on the second electrode 127. The magnetization direction of the first magnetization fixed layer 122 and the magnetization direction of the second magnetization fixed layer 126 are antiparallel to each other.
The first intermediate layer 123 is formed on the first magnetization fixed layer 122, and the second intermediate layer 125 is formed on the second magnetization fixed layer 126.
The light modulation layer 124 is formed on the first intermediate layer 123 and the second intermediate layer 125.

  The electric field applying electrode 150 is provided through the insulator layer 140 so as to face the light modulation layer 124. In the present embodiment, the electric field application electrode 150 is disposed on the light modulation layer 124. Further, in the insulator layer 140, at least a portion of the insulator material stacked on the light modulation layer 124 is formed of a high dielectric constant material. That is, the third insulator layer 143 is formed of a high dielectric constant material.

  By forming the third insulator layer 143 with a material having a high dielectric constant, charges generated at the interface between the light modulation layer 124 and the region of the insulator layer interposed between the light modulation layer 124 and the electric field application electrode 150. Therefore, it is possible to greatly change the electronic state of the light modulation layer 124 and increase the change in coercive force. In this way, the coercive force of the light modulation layer 124 can be further attenuated, and the reversal current of spin injection magnetization reversal can be further reduced. The coercive force change was confirmed in a magnetoresistive effect element (TMR element 400) having an electric field application electrode, as will be described later. As described above, if the material of the third insulator layer 143 is a material having a high dielectric constant, the thickness of the light modulation layer 124 can be increased unless other conditions are changed.

In the present embodiment, as an example, the electric field applying electrode 150 is formed of a translucent material. By doing so, it is possible to form a light modulation element that irradiates polarized light from the electric field applying electrode 150 side and whose reflected light changes depending on the magnetization direction of the light modulation layer 124.
Here, the translucency is a property that allows incident light to easily pass through, and means a property that transmits incident light, for example, at least about 70% or more. Examples of such an electrode material include known transparent electrode materials such as indium tin oxide (ITO) and indium zinc oxide (IZO). As an example, it is preferable to use IZO for the electric field applying electrode 150.
As a method for forming the electric field applying electrode 150, for example, an electrode material is formed by a known method such as a sputtering method, and a photolithography step and a step such as an etching or lift-off method can be used. Note that, as a method for forming the transparent electrode material, a vacuum deposition method, a coating method, or the like can be used in addition to the sputtering method.

  As the material of the light modulation layer (magnetization free layer) 124, materials suitable for the magnetization free layer, for example, transition metal materials such as CoFeB, CoFe, Co, Fe, CoFeSi, and CoFeGe can be mainly used. [Transition metal / noble metal] multilayer film (Co / Pt multilayer film, Co / Pd multilayer film, Fe / Pd multilayer film, CoFe / Pd multilayer film, Fe / Pt multilayer film, etc.), or transition metal / noble metal An alloy (CoPt alloy, CoPd alloy, FePd alloy, FePt alloy, etc.), an alloy of a rare earth metal and a transition metal (GdFe alloy, GdCoFe alloy, GdCo alloy, TbFeCo alloy, etc.) or a multilayer film thereof, and an MnBi alloy, A material having a large magneto-optical effect such as a Mn / Bi multilayer film, a PtMnSb alloy, or a Pt / MnSb multilayer film can be used.

  In the present embodiment, the material of the light modulation layer 124 includes Gd. The light modulation layer 124 is formed of a multilayer film, and at least one of them is a film containing Gd. In the present embodiment, as an example, the light modulation layer 124 includes a GdFe alloy that is a perpendicular magnetic anisotropic material. By using such a material, the magnetoresistive effect element 120 has an effect that the magnetization can be reversed at a low current. In addition, the effect of applying an electric field can be increased, and even if the light modulation layer 124 is a relatively thick film (9 nm), a change in coercive force due to the electric field can be caused. Therefore, it is possible to provide the magnetoresistive element 120 that is resistant to external thermal disturbances.

Examples of the material of the first intermediate layer 123 and the second intermediate layer 125 include metals such as Cu, Al, Au, and Ag (film thickness of about ₂ nm to 6 nm), for example, Al ₂ O ₃ (relative dielectric constant 8.5, An insulator (film thickness of about 0.6 to 2 nm) such as a refractive index of 1.77) or MgO (relative dielectric constant of 9.8, refractive index of 1.74) can be used.
In order to read the change in resistance value when the light modulation layer is inverted, one of the first intermediate layer 123 and the second intermediate layer 125 may be a metal layer, and the other may be an insulator layer.
It is preferable that both the first intermediate layer 123 and the second intermediate layer 125 are insulator layers because each intermediate layer has a charge storage effect. Therefore, in this embodiment, both are insulator layers and the material is MgO.
When the first intermediate layer 123 and the second intermediate layer 125 are both metal layers, each intermediate layer has no charge storage effect, which is not preferable.
In any case, the third insulator layer 143 on the light modulation layer 124 has a charge accumulation effect. Further, when both the first intermediate layer 123 and the second intermediate layer 125 are insulator layers, the thickness of the insulator layers may be changed and deposited.

The first magnetization fixed layer 122 is a magnetic layer in which the magnetization direction is fixed in one direction. In all the magnetoresistive effect elements 120, for example, the magnetization direction of the first magnetization fixed layer 122 is fixed upward (see FIG. 4).
The second magnetization fixed layer 126 is a magnetic layer in which the magnetization direction is fixed in the other direction. In all the magnetoresistive effect elements 120, the magnetization direction of the second magnetization fixed layer 126 is fixed downward, for example (see FIG. 4).

  The first magnetization fixed layer 122 and the second magnetization fixed layer 126 can be made of a known magnetic material used for a CPP-GMR element or a TMR element, similarly to the light modulation layer 124. However, the magnetic material and thickness of the first magnetization fixed layer 122 and the second magnetization fixed layer 126 are selected so that the coercive force is larger than that of the light modulation layer 124 so that the magnetization is fixed.

As described above, the magnetization direction of the first magnetization fixed layer 122 and the magnetization direction of the second magnetization fixed layer 126 are antiparallel to each other.
One method for making the magnetizations of the two magnetization fixed layers antiparallel to each other is to use the same material for each magnetization fixed layer, but to change the film forming conditions (gas pressure) and keep the two magnetization fixed layers different. It should be set to magnetic force. When, for example, TbFeCo is used as the same material for each magnetization fixed layer and the gas type is Kr, the coercive force H = 4 kOe and the gas pressure is 3.1 when the gas pressure is 8.5 × 10 ⁻² Pa. A coercive force H = 2 kOe was obtained when × 10 ⁻¹ Pa.

When the coercive force of the first magnetization fixed layer 122 is H _c1 and the coercivity of the second magnetization fixed layer 126 is H _c2 , to stably reverse the magnetization of the light modulation layer having the coercive force of H _cf , H _cf <H _c1 <H _c2 . At this time, the operation (initialization) for setting the magnetization directions of the first magnetization fixed layer 122 and the second magnetization fixed layer 126 to antiparallel to each other is as follows. That is, the coercive force H _c1 of the first magnetization pinned layer 122, and a large magnetic field H than the coercive force H _c2 of the second magnetization pinned layer 126, is applied to the downward perpendicular to the film surface, the first magnetization pinned layer 122 and the The magnetizations of the two magnetization fixed layers 126 are both downward. Subsequently, a magnetic field H that is larger than the coercive force H _{c1 of} the first magnetization fixed layer 122 and smaller than the coercive force H _{c2 of} the second magnetization fixed layer 126 is applied upward in the direction perpendicular to the film surface, and the first magnetization fixed layer 122 is applied. Only the magnetization of is upward. Thereby, the initialization operation is completed.
The magnetization direction of the light modulation layer can be set to either upward or downward by passing a current pulse between the first electrode 121 and the second electrode 127 in each pixel.

At least one of the first magnetization fixed layer 122 and the second magnetization fixed layer 126 may have a multilayer structure using a magnetic exchange coupling film such as Ru. An example of such a multilayer structure is CoFe / Ru / CoFe / TbFeCo when expressed in the stacking order from the intermediate layer side.
When such a multilayer structure is realized by in-plane magnetization, for example, when expressed in the stacking order from the intermediate layer side, for example, CoFe / Ru / CoFe / IrMn (instead of IrMn, use an antiferromagnetic material such as FeMn, PtMn, etc.) Or the like.
With such a configuration, the magnetizations of the first magnetization fixed layer 122 and the second magnetization fixed layer 126 can be initially set in an antiparallel state without performing an operation of applying different magnetic fields.

In this embodiment, as an example, the magnetization directions are made antiparallel to each other by changing the material of the first magnetization fixed layer 122 and the material of the second magnetization fixed layer 126.
For this reason, the first magnetization fixed layer 122 is CoFe / TbFeCo / Ru in the stacking order from the first intermediate layer 123 side.
The second magnetization fixed layer 126 is CoFe / Ru / CoFe / TbFeCo / Ru in the order of stacking from the second intermediate layer 125 side. The underlayer Ru was used to increase the coercivity of TbFeCo. In the following, the underlayer may be referred to as a magnetization fixed layer.
Further, the first intermediate layer 123 and the second intermediate layer 125 are both made of MgO, and the underlying layer of the first magnetization fixed layer 122 and the second magnetization fixed layer 126 is so absorbed that the difference in film thickness of the magnetization fixed layer can be absorbed. Adjustment was made by changing the thickness of Ru.
An underlayer (not shown) for improving the adhesion is provided between the first magnetization fixed layer 122 and the first electrode 121 and between the second magnetization fixed layer 126 and the second electrode 127. It may be provided.

  The protective layer 128 protects the light modulation layer 124. In particular, when the light modulation layer 124 contains an easily oxidizable RE-TM alloy, it is provided as necessary to prevent oxidation of the surface (upper surface). The protective layer 128 is formed of a single layer of Ta, Ru, Cu, for example. Alternatively, a Cu / Ta two-layer metal film or a Cu / Ru two-layer metal film is formed in this order from the light modulation layer 124 side. As an example, the protective layer 128 is preferably composed of a Ru single layer.

The insulator forming the insulator layer 140 is made of a general insulator material. Examples of such materials include oxide films such as SiO ₂ and Al ₂ O ₃ , Si ₃ N ₄ and MgF ₂ . Here, the first insulator layer 141 is preferably formed of a material that is easily etched by a method having high etching selectivity such as reactive ion etching (RIE) in the process of manufacturing the magnetoresistive effect element 120. . In the present embodiment, as an example, the first insulator layer 141 and the second insulator layer 142 are made of SiO ₂ , and the third insulator layer 143 is made of SiN.

The insulating film 129 is provided to function as an etching stopper layer for performing an etching process with high accuracy in the process of manufacturing the magnetoresistive effect element 120 on the backplane 110. The insulating film 129 is preferably formed of a material that is difficult to etch (low etching rate) in the etching of the first insulator layer 141 when the magnetoresistive element 120 is manufactured. For example, if the first insulator layer 141 is SiO ₂ , Si nitride, MgO, Al ₂ O ₃ can be applied to the insulating film 129. In addition, if the first insulator layer 141 is Si nitride, MgO can be applied to the insulating film 129. In the present embodiment, the insulating film 129 is made of MgO. In the above process, the insulating film 129 is removed in a region where the backplane 110 and the magnetoresistive effect element 120 are electrically connected.

When the backplane 110 includes the MOS-FET as in the present embodiment, there is an advantageous effect that the SLM can be miniaturized by closely arranging the pixels as shown in the following (1) to (5).
(1) The drain output of the MOS-FET is input to one end of the magnetoresistive effect element 120, and the other end of the magnetoresistive effect element 120 is combined with other elements via the second power supply wiring 113 to generate a pulse power source (current source). 171).
(2) By connecting the source S of the MOS-FET to the first power supply wiring 112 and connecting the drain D of the MOS-FET to the second power supply wiring 113, the first power supply wiring 112 (source electrode) and the first power supply wiring 112 are connected. The two power supply wirings 113 (drain electrodes) can be drawn out in parallel.
(3) By connecting the gate G of the MOS-FET to the pixel selection signal line 115, the pixel selection signal line 115 (gate electrode) is connected to the first power supply wiring 112 (source electrode) and the second power supply wiring 113 (drain electrode). ) And the direction perpendicular to each other.
(4) The electric field applying electrode 150 which is a characteristic part of the magnetoresistive effect element 120 can be drawn out in parallel with the pixel selection signal line 115 (gate electrode).
(5) The MOS-FET could be easily manufactured on the backplane 110 with a pitch of about 1 μm to 5 μm, for example. Further, it can be further miniaturized and manufactured at a submicron order pitch.

The pixel selection means 161-164 cooperate, and the whole operation | movement is controlled by the control part which is not shown in figure.
The pixel selection means 161 is connected to the first power supply wiring 112 and the second power supply wiring 113 corresponding to each pixel on the backplane 110, and is connected to the write / read power supply 170 by switching.
The pixel selection unit 161 outputs a signal to a pixel to be selected at the time of writing. For example, in FIG. 2, a selection transistor in which the signal W ₁ is input to the gate, a selection transistor in which the signal W ₂ is input to the gate, , And a selection transistor to which the signal W ₃ is input to the gate. At the time of writing, a signal for outputting to a row where pixels to be selected are arranged is turned on, and a signal for outputting to other rows is turned off.

The pixel selection means 162 is provided for use with the optional electrical resistance detection means 190. The pixel selection means 162 is connected to the first power supply wiring 112 and the second power supply wiring 113 corresponding to each pixel on the backplane 110, and is connected to the electric resistance detection means 190 by switching.
The pixel selection unit 162 outputs a signal to a pixel to be selected at the time of reading. For example, in FIG. 2, a selection transistor in which the signal R ₁ is input to the gate and a selection transistor in which the signal R ₂ is input to the gate , And a selection transistor to which the signal R ₃ is input to the gate. At the time of reading, a signal for outputting to a row where pixels to be selected are arranged is turned on, and a signal for outputting to other rows is turned off.

The pixel selection unit 163 is connected to the pixel selection signal line 115 corresponding to each pixel on the backplane 110.
The pixel selection unit 163 outputs a signal to a pixel to be selected at the time of writing and reading, and supplies, for example, the signal G _{1, the} signal G _2, or the signal G ₃ input to the gate of the selection transistor in FIG. For this purpose, signal supply means (not shown) is provided. At the time of writing and reading, a signal for outputting to the column in which the pixel to be selected is arranged is turned on, and a signal for outputting to the other column is turned off.

The pixel selection means 164 is connected to the voltage application power source 180 and is connected to the electric field application electrode 150 corresponding to each pixel by switching.
The pixel selection means 164 outputs a signal to a pixel to be selected at the time of writing. For example, in FIG. 2, a selection transistor in which the signal A ₁ is input to the gate, a selection transistor in which the signal A ₂ is input to the gate, , And a selection transistor to which the signal A ₃ is input to the gate. At the time of writing, a signal for outputting to a column in which pixels to be selected are arranged is turned on, and a signal for outputting to other columns is turned off.

The writing / reading power supply 170 is connected to the voltage application power supply 180 by switching, and is connected to the pixel selection means 161 by switching.
The write / read power supply 170 includes the write current source 171 shown in FIGS. 2 and 3 as an essential component. Hereinafter, it is simply referred to as a current source 171.
The current source 171 may be a direct current, but in this embodiment, the pulse current is passed as schematically shown in FIGS. 2 and 3. The upstream and downstream of the current source 171, and a selection transistor signal T ₁ is input to the gate for example in FIG. 2, and a selection transistor signal T ₂ is input to the gate is provided. At the time of writing, each selection transistor is turned on, and at the time of reading, each is turned off.

In the present embodiment, the write / read power supply 170 further includes a read power supply 172 shown in FIG. The read power source 172 is an optional configuration for verifying whether or not the optical modulation layer 124 is in a magnetization reversal state. The read power source 172 may be a DC current source, a DC current source with an alternating current superimposed thereon, or a voltage source instead of the current source.
In the present embodiment, it is assumed that the read power source 172 is a DC current source. For example, in FIG. 2, a selection transistor to which the signal T ₃ is input to the gate and a selection transistor to which the signal T ₄ is input to the gate are provided upstream and downstream of the read power source 172. Each read transistor is turned on during reading, and turned off during writing.

The voltage application power source 180 is connected to the current source 171 at the time of writing (when the signals T ₁ and T ₂ are turned on in FIG. 2), and is selected by switching at the time of writing to the magnetoresistive effect element 120 (pixel). To the electric field applying electrode 150.
The voltage application power source 180 includes, for example, a DC power source 181 shown in FIG. The DC power source 181 applies a DC voltage for at least the time when the pulse current is passed by the current source 171. As an example, the terminal voltage of the DC power supply 181 may be about 1 volt.

For example, a negative terminal of the DC power supply 181 is connected to the second power supply wiring 113 of the backplane 110. In other words, the negative electrode terminal of the DC power supply 181 is connected to the second electrode 127 of the magnetoresistive effect element 120 from the linear second power supply wiring 113 in the in-plane direction via the second bonding wiring 117 in the thickness direction for each pixel. Has been.
For example, a positive electrode terminal of the DC power supply 181 is connected to the electric field application electrode 150 by switching via a wiring for each pixel (each pixel column) of the pixel selection unit 164.

  In the present embodiment, as an example, since the light modulation layer 124 includes a GdFe alloy of a perpendicular magnetic anisotropic material, the electric field application electrode 150 includes a DC terminal 181 on the positive terminal side, as will be described later. Even if the negative electrode terminal side is connected, the same effect can be obtained. Depending on the material used for the light modulation layer 124, the electric field application electrode 150 may have a desired effect only when the negative electrode terminal side of the DC power supply 181 is connected.

  The electrical resistance detection unit 190 is an optional configuration that is used together with the read power source 172 in order to verify whether or not the light modulation layer 124 is in a magnetization reversal state. The electrical resistance detection means 190 is connected to the selected magnetoresistive effect element 120 (pixel) by switching. The electrical resistance detection unit 190 includes, for example, a voltmeter 191 shown in FIG.

  The voltmeter 191 is a path from the read power supply 172 (DC current source) to the second electrode 127 via the light modulation layer 124 from the first electrode 121 of the selected magnetoresistive effect element 120 (pixel). In this case, the potential difference between the electrodes is measured. The electrical resistance value of the magnetoresistive effect element 120 selected here is a value obtained by dividing the measured voltage value by the read current value. By comparing this value with a predetermined threshold value, it is possible to verify whether or not the magnetization reversal state has occurred in the light modulation layer 124 of the selected magnetoresistive effect element 120 (pixel).

  The positive terminal of the voltmeter 191 is connected to the second power supply wiring 113 of the backplane 110. That is, the positive electrode terminal of the voltmeter 191 is connected to the second electrode 127 of the magnetoresistive effect element 120 from the linear second power supply wiring 113 in the in-plane direction via the second junction wiring 117 in the thickness direction for each pixel. Has been.

  The negative terminal of the voltmeter 191 is grounded, and is connected to the first power supply wiring 112 of the backplane 110 by switching via the wiring for each pixel (each pixel row) of the pixel selection unit 162. That is, the negative terminal of the voltmeter 191 is switched from the linear first power supply wiring 112 in the in-plane direction to the third junction wiring 118 in the thickness direction for each pixel, the source S and drain D of the MOS-FET, the first It is connected to the first electrode 121 of the magnetoresistive effect element 120 through one junction wiring 116.

  A holographic display device can be configured by providing the spatial light modulator 100 shown in FIG. 1 with the light irradiation mechanism shown in FIG. The light irradiation mechanism shown in FIG. 4 includes a light source 201 such as a laser, incident polarization means 202, and output polarization means 203. The electric field applying electrode 150 is made of a transparent electrode material, and hatching is omitted in the cross-sectional view of FIG.

[Operation of spatial light modulator]
Under the control of a control unit (not shown), the pixel selection units 161 to 164 cooperate to select the magnetoresistive effect element 120 to be brought into the bright state in the spatial light modulator 100 as a target pixel, and to change the magnetization of the light modulation layer 124. Control is performed to make the direction downward, and control to make the magnetization direction of the light modulation layer 124 of the magnetoresistive effect element 120 to be in the dark state upward is performed. The magnetization direction of the light modulation layer 124 of the magnetoresistive effect element 120 selected as the target is controlled by the direction in which the pulse current from the current source 171 flows. In this embodiment, as shown in FIG. 3, the pulse current from the read power supply 17 (DC current source) passes from the first electrode 121 of the selected magnetoresistive effect element 120 (pixel) via the light modulation layer 124. It flows along a route reaching the second electrode 127.

As shown in FIG. 4, the light emitted from the light source 201 such as a laser contains various polarization components, but is aligned on the polarization plane in one direction by the incident polarization means 202. The laser light that has passed through the incident polarization means 202 passes through the electric field application electrode 150 and enters each pixel. The polarization plane rotates depending on the magnetization direction of the light modulation layer 124 in each pixel. For example, when the polarization plane of the laser beam reflected when the magnetization direction of the light modulation layer 124 is downward is rotated by (θ _k + a), for example, clockwise as shown in FIG. Since the light passes through the outgoing polarization means 203, it is in the “bright state”. Here, the angle a is a value that varies depending on the sum of Kerr rotation angles with respect to the magnetizations of the first magnetization fixed layer 122 and the second magnetization fixed layer 126.

On the other hand, when the polarization plane of the laser light reflected when the magnetization direction of the light modulation layer 550 is upward is rotated by (θ _k + a), for example, counterclockwise as shown in FIG. When expressed as a rotation,-(θ _k + a) rotation), the reflected light does not pass through the outgoing polarization means 203, and thus becomes a “dark state”. Based on the above principle, the incident polarized light can be modulated by the magnetization direction of the light modulation layer 124 in each pixel.

  In the present embodiment, during the flow of the pulse current, the positive electrode terminal of the DC power supply 181 is connected to the electric field application electrode 150 of the selected magnetoresistive effect element 120 (pixel) as shown in FIG. In addition to being connected, the negative electrode terminal of the DC power supply 181 is connected to the second electrode 127. That is, the inter-terminal voltage of the DC power supply 181 is applied between the electric field application electrode 150 and the second electrode 127. Therefore, an electric field is applied from the electric field applying electrode 150 toward the second electrode 127 side. In other words, a positive electric field is applied from the electric field applying electrode 150 toward the light modulation layer 124. The electric field applying electrode 150 is an electrode for applying an electric field and is not an electrode for flowing current.

  The region of the third insulator layer 143 interposed between the light modulation layer 124 and the electric field application electrode 150 by applying an electric field to the light modulation layer 124 during the spin injection magnetization reversal of the magnetoresistive effect element 120. Charge is accumulated at the interface between the light modulation layer 124 and the light modulation layer 124. Therefore, the electronic state of the light modulation layer 124 changes, and as a result, the coercive force of the light modulation layer 124 changes and attenuates. Since the coercive force of the light modulation layer 124 is attenuated during the spin injection magnetization reversal, the reversal current of the spin injection magnetization reversal can be reduced. Therefore, the magnetoresistive effect element 120 can reduce a switching current. The magnetoresistive effect element 120 can be applied as a magnetic random access memory.

  When the electric field applying electrode 150 is connected to the negative terminal of the DC power supply 181, the direction of the electric field is opposite. Depending on the material used for the light modulation layer 124, it is better to connect in this way. In this case, an electric field is applied from the second electrode 127 side toward the electric field applying electrode 150. In other words, a negative electric field is applied from the electric field applying electrode 150 toward the light modulation layer 124. The direction of the electric field in this case is indicated by a thin and long arrow in FIG.

  In FIG. 4, the configuration excluding the electric field application electrode 150, which is a characteristic part of the magnetoresistive effect element 120 (pixel), is represented as a spatial light modulation function unit 130. The spatial light modulation function unit 130 has the same structure as the SLM described in Patent Document 3. The principle of controlling the magnetization direction in the spatial light modulation function unit 130 will be described with reference to FIG. Here, as shown in FIG. 5A, as an initial state, the magnetization direction is downward in the light modulation layer 124, upward in the first magnetization fixed layer 122, and downward in the second magnetization fixed layer 126. .

  A state changed from this initial state is assumed. At this time, as shown in FIG. 5B, when a pulse current is supplied from the current source 171 to the spatial light modulation function unit 130 with the first electrode 121 negative and the second electrode 127 positive, the first electrode In the electrons injected from 121, the upward spin passes through the first magnetization fixed layer 122, but the downward spin cannot pass through the first magnetization fixed layer 122. That is, the electrons injected from the first electrode 121 align the spin in the magnetization direction of the first magnetization fixed layer 122 (spin polarization), and the spin-polarized electron holds the spin upward in the first intermediate layer 123. The light passes through and is injected into the light modulation layer 124. In the light modulation layer 124, local spin torque is generated due to the interaction between the internal electrons that determine the magnetization direction of the light modulation layer 124 and the injected spin-polarized electrons. It reverses the spin of internal electrons that determines the magnetization direction. Therefore, as a result, the magnetization reversal of the light modulation layer 124 occurs from the side immediately above the first magnetization fixed layer 122.

  At the same time, on the side of the light modulation layer 124 immediately above the second magnetization fixed layer 126, the electrons holding the downward spin pass through the second magnetization fixed layer 126, but the upward spin passes through the second magnetization fixed layer 126. I can't. Therefore, electrons holding upward spin remain on the light modulation layer 124 immediately above the second magnetization fixed layer 126. Due to the torque due to the upward spin, magnetization reversal also occurs from the side immediately above the second magnetization fixed layer 126 of the light modulation layer 124. By supplying the pulse current in this way, the magnetization direction of the light modulation layer 124 is reversed, and as a result, the state shown in FIG. 5B is shifted to the state shown in FIG.

In the state shown in FIG. 5C, the direction of magnetization of the light modulation layer 124 is upward. Assume a state in which this state is further changed. At this time, as shown in FIG. 5D, when a pulse current is supplied from the current source 171 to the spatial light modulation function unit 130 with the first electrode 121 being positive and the second electrode 127 being negative, the second electrode The electrons injected from 127 align the spin in the magnetization direction of the second magnetization fixed layer 126 (spin polarization), and the spin-polarized electrons pass through the second intermediate layer 125 while maintaining the downward spin, Injected into the modulation layer 124. Due to the torque due to the downward spin, as a result, magnetization reversal of the light modulation layer 124 occurs from the side immediately above the second magnetization fixed layer 126.
At the same time, due to the torque due to the downward spin on the light modulation layer 124 near the first magnetization fixed layer 122, magnetization reversal also occurs from the light modulation layer 124 near the first magnetization fixed layer 122. By supplying the pulse current in this manner, the magnetization direction of the light modulation layer 124 is reversed, and as a result, the state shown in FIG. 5D is shifted to the state shown in FIG.

  Thus, the magnetization direction of the light modulation layer 124 can be controlled by the direction in which the pulse current flows. Further, by providing the first magnetization fixed layer 122 and the second magnetization fixed layer 126, the efficiency of spin injection can be improved, and even if the area of the light incident surface (emission surface) is increased, the light modulation is performed. Since the magnetization reversal of the layer 124 occurs efficiently, the aperture ratio of the pixel can be increased.

[Method for Fabricating Spatial Light Modulator and Magnetoresistive Element]
As an example of a method of manufacturing the spatial light modulator 100 and the magnetoresistive effect element 120 shown in FIG. 1, with reference to FIGS. I will explain.

  In the first step, the back plane 110 shown in FIG. 6A is formed. In this embodiment, a silicon backplane with a MOS-FET in which a MOS-FET is formed at a desired pixel pitch is formed using a known silicon process.

In the second step, as shown in FIG. 6B, an insulating film 129 is formed as an etching stopper on the backplane 110, and the magnetoresistive effect element 120 (pixel) is separated thereon. This is a step of forming one insulator layer 141.
As a film forming method, a known film forming method such as a sputtering method, a vacuum deposition method, a coating method, or the like can be used. In this embodiment, an ion beam sputtering method is used as the film forming method. Here, MgO is stacked as the insulating film 129, and SiO ₂ is used as the first insulator layer 141.

The third step is a step of forming a resist pattern 301 for the first magnetization fixed layer 122 on the first insulator layer 141 as shown in FIG.
The resist pattern 301 is a region corresponding to the first bonding wiring 116 of the backplane 110, and has a pattern in which a hole is formed in a portion of the region where the first magnetization fixed layer 122 is disposed, for example, an electron beam It is formed by a lithography method.

In the fourth step, as shown in FIG. 6D, the first insulator layer 141 is etched by reactive ion etching (RIE) using, for example, CF ₄ gas through the holes 302 formed in the resist pattern 301. At this time, etching stops at the insulating film 129 formed in the second step.

  The fifth step is a step of physically removing the etching stopper (insulating film 129) that is no longer necessary at the bottom of the hole 302. In this embodiment, as shown in FIG. 7A, insulation is performed by an ion beam milling method using inert gas ions such as Ar ions through a hole 303 penetrating the resist pattern 301 and the first insulator layer 141. The film 129 is physically milled until the first bonding wiring 116 of the backplane 110 is exposed.

The sixth step is a step of depositing a material or the like on the left side (the side on which the first magnetization fixed layer 122 is disposed) of the magnetoresistive effect element 120 in FIG. Here, as shown in FIG. 7B, the material of the first electrode 121, the material of the first magnetization fixed layer 122, the material of the first intermediate layer 123, and the material of the protective layer 304 are laminated in this order. Here, Ru may be used for the protective layer 304. However, since it is necessary to expose the first intermediate layer 123 in a later step, SiO ₂ is sufficient. Therefore, in this embodiment, SiO ₂ is laminated as the protective layer 304. As a result, as shown in FIG. 7B, the hole 305 penetrating through the resist pattern 301, the first insulator layer 141, and the insulating film 129 is buried with the material of the first magnetization fixed layer 122 or the like.

  The seventh step is a step of removing excess material other than the material embedded in the hole 305. Here, excess material such as a metal multilayer film stacked on the resist pattern 301 is peeled off together with the resist pattern 301 by a lift-off method. As a result, as shown in FIG. 7C, the surface of the first insulator layer 141 is exposed. At this time, the first intermediate layer 123 is not exposed because the protective layer 304 is present in the region of the backplane 110 that is on the first bonding wiring 116.

The eighth step is a step of forming a resist pattern 306 for the second magnetization fixed layer 126 on the first insulator layer 141 as shown in FIG.
The resist pattern 306 is a region corresponding to the second bonding wiring 117 of the back plane 110, and is formed, for example, by an electron beam so that a hole is formed in a portion of the region where the second magnetization fixed layer 126 is disposed. It is formed by a lithography method.

In the ninth step, as shown in FIG. 8A, the first insulator layer 141 is etched by reactive ion etching (RIE) using CF ₄ gas, for example, through the holes 307 formed in the resist pattern 306. At this time, etching stops at the insulating film 129 formed in the second step.

  The tenth step is a step of physically removing the etching stopper (insulating film 129) that is no longer necessary at the bottom of the hole 307. In the present embodiment, as shown in FIG. 8B, the insulating pattern is formed by ion beam milling using an inert gas ion such as Ar ions through a hole 308 penetrating the resist pattern 306 and the first insulator layer 141. The film 129 is physically milled until the second bonding wiring 117 of the backplane 110 is exposed.

The eleventh step is a step of depositing the material and the like on the right side (the side on which the second magnetization fixed layer 126 is disposed) of the magnetoresistive effect element 120 in FIG.
Here, as shown in FIG. 8C, the material of the second electrode 127, the material of the second magnetization fixed layer 126, the material of the second intermediate layer 125, and the material of the protective layer 309 are laminated in this order.
In this embodiment, the same material as the first electrode 121 is stacked as the second electrode 127 with the same film thickness. Further, the second magnetization fixed layer 126 is laminated by adding a material different from that of the first magnetization fixed layer 122 as a multilayer structure using a magnetic exchange coupling film. In addition, the underlayer of the first magnetization fixed layer 122 is formed thicker than the underlayer of the second magnetization fixed layer 126 so that the difference in film thickness between the two magnetization fixed layers can be absorbed. Further, a material similar to that of the protective layer 304 was stacked as the protective layer 309 with the same thickness. As a result, as shown in FIG. 8C, the hole 310 penetrating the resist pattern 306, the first insulator layer 141, and the insulating film 129 is buried with the material of the second magnetization fixed layer 126.

  The twelfth step is a step of removing excess material other than the material embedded in the hole 310. Here, excess material such as a metal multilayer film stacked on the resist pattern 306 is peeled off together with the resist pattern 306 by a lift-off method. As a result, as shown in FIG. 8D, the surface of the first insulator layer 141 is exposed. The first intermediate layer 123 is not exposed because the protective layer 304 is present in the region of the backplane 110 that contacts the first bonding wiring 116. In addition, since the protective layer 309 is present in the region of the backplane 110 that corresponds to the second junction wiring 117, the second intermediate layer 125 is not exposed.

  The thirteenth step is a step for exposing the intermediate layer that has been protected so far as preparation for stacking the light modulation layer in the next step. In the present embodiment, as shown in FIG. 9A, the surfaces of the first insulator layer 141 and the protective layers 304 and 309 are formed by the ion beam milling method using inert gas ions such as Ar ions. Physical milling is performed until the intermediate layer 123 and the second intermediate layer 125 are exposed.

  The fourteenth step is a step of depositing a material or the like of the light modulation layer 124 over the entire surface from above the first intermediate layer 123 and the second intermediate layer 125. Here, as shown in FIG. 9B, the material of the light modulation layer 124 and the material of the protective layer 128 are laminated in this order. In the present embodiment, CoFe / Gd / GdFe is laminated from the first intermediate layer 123 and the second intermediate layer 125 using the light modulation layer 124 as a multilayer film. Further, Ru was stacked as the protective layer 128.

  The fifteenth step is a step of forming a light modulation layer resist pattern 311 on the protective layer 128. The resist pattern 311 is a region corresponding to a region extending from the first intermediate layer 123 to the second intermediate layer 125 disposed thereunder, and the light modulation layer 124 indicated by a broken line in FIG. For example, it is formed by an electron beam lithography method so as to have a rectangular pattern similar to the above-described shape.

  The sixteenth step is a step of physically removing unnecessary portions of the protective layer 128 exposed without being protected by the resist pattern 311 and the light modulation layer 124 therebelow. In the present embodiment, as shown in FIG. 9 (d), an inert gas ion such as Ar ion is used for physical milling by ion beam milling until the first insulator layer 141 is exposed.

The seventeenth step is a step of depositing an insulating film between the magnetoresistive effect elements 120 (pixels). Here, the second insulator layer 142 is deposited on the side surface around the light modulation layer 124 and the side surface around the protective layer 128 exposed in the sixteenth step. In this embodiment, as shown in FIG. 10A, SiO ₂ is laminated as a second insulator layer 142 on the entire surface from the top of the resist pattern 311 and the portion processed in the previous process is backfilled.

  The 18th step is a step of removing excess insulator material other than the insulator layer backfilled in the 17th step. Here, the insulator layer stacked on the resist pattern 311 is peeled off together with the resist pattern 311 by a lift-off method. As a result, the protective layer 128 is exposed as shown in FIG. At this point, the spatial light modulation function unit 130 (see FIG. 4) is completed. Here, for example, the magnetization direction of the first magnetization fixed layer 122 may be set upward and the magnetization direction of the second magnetization fixed layer 126 may be initially set.

The nineteenth step is a step of depositing an insulating film between the electric field applying electrode 150 manufactured in a later step and the light modulation layer 124. Here, as shown in FIG. 10C, the third insulator layer 143 is deposited on the entire surface of the second insulator layer 142. As a material of the third insulator layer 143, an insulating material having a large dielectric constant can be used in addition to SiO ₂ , SiN, Ta ₂ O ₅ . Particularly preferred are those having a high dielectric constant and a high refractive index.

The 20th step is a step of forming a resist pattern 312 for the electric field applying electrode 150 on the third insulator layer 143 as shown in FIG.
The resist pattern 312 is a region corresponding to the light modulation layer 124 disposed thereunder, and is formed by, for example, an electron beam lithography method so as to have a pattern having an opening larger in area than the light modulation layer 124. The

In the twenty-first step, as shown in FIG. 11A, the third insulator layer 143 is etched by reactive ion etching (RIE) using, for example, CF ₄ gas through the opening of the resist pattern 312. At this time, the third insulator layer 143 is thinned on the protective layer 128 in a region having a larger area than the protective layer 128. If the film thickness of the third insulator layer 143 on the protective layer 128 is thin, there is a merit that the applied voltage value by the electric field applying electrode 150 created in a later step can be reduced. Because of concern, the lower limit is preferably about 10 nm, for example. Further, this film thickness is set within a range in which an insulation state with the electric field applying electrode 150 can be maintained and an effect of a change in coercive force by applying the electric field can be obtained. Therefore, it is preferable that it is about 10-30 nm, for example.

  The 22nd step is a step of depositing the material of the electric field applying electrode 150 on the entire surface of the resist pattern 312. As shown in FIG. 11B, the thin film region of the third insulator layer 143 is buried with the material of the electric field applying electrode 150 through the opening of the resist pattern 312. In this embodiment, a transparent electrode material such as IZO or ITO is laminated as the material for the electric field applying electrode 150.

  The 23rd step is a step of removing excess electrode material other than the electric field applying electrode 150 laminated on the thin film region of the third insulator layer 143. Here, the electrode layer laminated on the resist pattern 312 is peeled off together with the resist pattern 312 by a lift-off method. Thereby, as shown in FIG. 11C, the magnetoresistive effect element 120 is completed on the back plane 110.

  In addition, since another magnetoresistive effect element arranged immediately adjacent to the magnetoresistive effect element shown in FIG. 11C shares the source region of the MOS-FET of the backplane 110, the first magnetization fixed layer 122 is The second magnetization fixed layer 126 is symmetrically arranged on the right side in the figure and on the left side in the figure.

In the manufacturing method, the first magnetization fixed layer 122, the second magnetization fixed layer 126, the light modulation layer 124, and the like are sequentially deposited on the MOS-FET of the backplane 110. However, the spatial light modulator 100 and the magnetoresistance The manufacturing method of the effect element 120 is not limited to this.
For example, on the one hand, the back plane 110 is formed in the first step, and on the other hand, the magnetoresistive effect element 120 is finally laminated in an inverted state on the transparent substrate prepared in advance. An element array in which each material is deposited is prepared. After that, the transparent substrate on which the element array is deposited can be turned over, and the element array can be manufactured by using a conventionally known so-called bonding method in which the element array is aligned and bonded to each MOS-FET on the backplane 110. It is. When using such a bonding method, when forming each magnetoresistive element 120 on a transparent substrate, the process of forming the protective layer 128 and the insulating film 129, for example, can be omitted. Further, before the bonding, the magnetization direction of the first magnetization fixed layer 122 may be initially set so that the magnetization direction of the second magnetization fixed layer 126 is downward and the magnetization direction of the second magnetization fixed layer 126 is downward.

An example of the material and film thickness of each layer in the example of the magnetoresistive effect element 120 actually manufactured is as follows.
As a film forming method, an ion beam sputtering method was used.
Backplane 110: Silicon backplane substrate (with MOS-FET)
Protective layer 128: Ru (3 nm)
Light modulation layer 124: CoFe (0.3 nm) / Gd (0.2 nm) / GdFe (9 nm) from the intermediate layer side
First intermediate layer 123, second intermediate layer 125: MgO (1 nm)
First magnetization fixed layer 122: CoFe (0.5 nm) / TbFeCo (20 nm) / Ru (4.3 nm) from the intermediate layer side
Second magnetization fixed layer 126: CoFe (0.5 nm) / Ru (0.8 nm) / CoFe (0.5 nm) / TbFeCo (20 nm) / Ru (3 nm) from the intermediate layer side
Total film thickness of the first insulator layer 141 and the second insulator layer 142: SiO ₂ (38 nm)
Third insulator layer 143: AlN (20 nm)
Insulating film 129: MgO (5 nm)
Electrodes 121, 127: Ta (3 nm) / Cu (25 nm)
However, the inside of () shows a film thickness.

  As described above, the magnetoresistive effect element 120 according to the first embodiment has the electrode 150 for applying an electric field through the insulator layer 140 facing the light modulation layer 124 in addition to the electrode for injecting spin. Thus, an electric field can be applied from the electric field applying electrode 150 to the light modulation layer 124 during the spin injection magnetization reversal. When an electric field is applied to the light modulation layer 124 during the spin injection magnetization reversal, charges are accumulated at the interface between the insulator layer 140 and the light modulation layer 124, so that the electronic state of the light modulation layer 124 changes. As a result, the coercive force of the light modulation layer 124 is changed and attenuated, so that the reversal current of the spin injection magnetization reversal can be reduced. Therefore, according to the magnetoresistive effect element 120, the switching current can be reduced. Therefore, according to the spatial light modulator 100 in which the magnetoresistive effect elements 120 are arranged in a two-dimensional array, the switching current can be reduced.

(Second Embodiment)
12, 13, and 14 are diagrams schematically showing a spatial light modulator 100A according to the second embodiment. The spatial light modulator 100A is mainly different from the spatial light modulator 100 of the first embodiment in that the electric field application electrode 150 (see FIG. 1) of the magnetoresistive effect element 120 (pixel) is divided into two. FIG. 12 corresponds to FIG. FIG. 13 corresponds to FIG. FIG. 14 corresponds to FIG. In the spatial light modulator 100A, the same components as those in the spatial light modulator 100 are denoted by the same reference numerals and description thereof is omitted.

  The spatial light modulator 100A includes a magnetoresistive effect element 120A (pixel) as shown in FIG. The magnetoresistive effect element 120 </ b> A includes two electric field applying electrodes 151 and 152 facing the light modulation layer 124 via the insulator layer 140. In the present embodiment, the electric field applying electrodes 151 and 152 are disposed on the light modulation layer 124. In the present embodiment, the electric field applying electrodes 151 and 152 are made of a light-transmitting material. In the cross-sectional view of FIG. 13, there is a slight gap of, for example, about several tens of nanometers between the electric field application electrode 151 and the electric field application electrode 152 and is filled with the material of the third insulator layer 143. The third insulator layer 143 (see FIG. 13) is formed of a high dielectric constant material.

The pixel selection unit 164A shown in FIG. 12 is connected to a voltage application power source 180A and is connected to two electric field application electrodes 151 and 152 for each pixel (for each pixel column).
The pixel selection means 164A outputs a signal to a pixel to be selected at the time of writing. For example, in FIG. 14, a selection transistor in which the signal B ₁ is input to the gate, a selection transistor in which the signal B ₂ is input to the gate, , And a selection transistor to which the signal B ₃ is input to the gate. At the time of writing, the column n of the pixel selecting are arranged (n represents at least one of 1, 2, 3) is a signal A _n, B _n are both turned on to output, and outputs the other columns Is turned off.

The voltage application power source 180A includes DC power sources 181 and 182 (see FIGS. 13 and 14) corresponding to the two electric field application electrodes 151 and 152, respectively.
The DC power source 182 is connected so as to have a polarity opposite to that of the DC power source 181. That is, for example, the positive terminal of the DC power source 182 is connected to the first power supply wiring 112 of the backplane 110. In other words, the positive terminal of the DC power supply 182 is switched from the linear first power supply wiring 112 in the in-plane direction to the third junction wiring 118 in the thickness direction for each pixel, the source S and drain D of the MOS-FET, the first through switching. It is connected to the first electrode 121 of the magnetoresistive effect element 120 through one junction wiring 116. On the other hand, for example, the negative terminal of the DC power supply 182 is connected to the electric field application electrode 152 by switching via the wiring for each pixel (each pixel column) of the pixel selection unit 164A.

As shown in FIG. 13, the electric field application electrode 151 is provided so as to be disposed on the second magnetization fixed layer 126 side. Similar to the first embodiment, a terminal voltage of the DC power supply 181 is applied between the electric field applying electrode 151 and the second electrode 127. The electric field applying electrode 151 plays a role of applying a positive electric field with the second electrode 127 as a reference to the light modulation layer 124.
The electric field applying electrode 152 is provided so as to be disposed on the first magnetization fixed layer 122 side. A voltage between terminals of the DC power source 182 is applied between the electric field applying electrode 152 and the first electrode 121 through a MOS-FET. Here, the negative electrode terminal of the DC power supply 182 is connected to the electric field applying electrode 152, and the positive electrode terminal of the DC power supply 182 is connected to the first electrode 121 through the first power supply wiring 112 and the MOS-FET. It becomes. The electric field application electrode 152 plays a role of applying a negative electric field with the first power supply wiring 112 as a reference to the light modulation layer 124.

The spatial light modulator 100A according to the second embodiment has the same effects as those of the first embodiment.
According to the magnetoresistive effect element 120A according to the second embodiment, the electric field application electrode 151 is disposed on the second magnetization fixed layer 126 side, and the electric field application electrode 152 is disposed on the first magnetization fixed layer 122 side. Therefore, the electric charge accumulated at the interface between the insulator layer 140 and the light modulation layer 124 is biased by the position in the film of the light modulation layer 124 (the position in the left-right direction in FIG. 13). Can not be.

  In the present embodiment, as an example, since the light modulation layer 124 includes a GdFe alloy that is a perpendicular magnetic anisotropic material, the DC power supply 182 has a polarity that is electrically opposite to that of the DC power supply 181. It is connected to the. However, in the case of this material, the same effect can be obtained regardless of whether positive or negative voltage is applied to the electric field application electrode. Therefore, the same polarity voltage may be applied to both electrodes. On the other hand, when other materials are used for the light modulation layer 124, the desired effect is often obtained only when the negative electrode terminals of the DC power supplies 181 and 182 are connected to the electric field applying electrodes 151 and 152, respectively. It is preferable to do so.

(Specific examples of coercive force)
In order to confirm the basic principle of the present invention, a normal TMR (Tunnel MagnetoResistance) element was improved, and a TMR element 400 having a double insulation structure shown in FIG. 15 was fabricated as an experimental sample. The TMR element 400 includes a lower electrode layer 402 stacked on a substrate 401, a base layer 403, magnetization fixed layers 404 and 405 using two materials, and a magnetization free layer (light modulation layer using three materials). ) 408, 409, 410, a barrier layer (intermediate layer) 406 that insulates between the magnetization fixed layer and the magnetization free layer, an insulator layer 407 for isolation from other elements, and a magnetization free layer In addition to the metal protective layer 411, an insulator layer 412 and an upper electrode layer 413 are provided in this order on the metal protective layer 411.

  In the case of a normal TMR element, the upper electrode layer 413 can be provided directly on the metal protective layer 411. Therefore, the layer made of an insulator in the magnetic film structure between the upper electrode layer 413 and the lower electrode layer 402 has a barrier. Only the layer (intermediate layer) 406 is provided. On the other hand, the TMR element 400 includes an insulator layer 412 in addition to the barrier layer (intermediate layer) 406 in the magnetic film structure between the upper electrode layer 413 and the lower electrode layer 402. Therefore, the TMR element 400 is called a TMR element having a double insulation structure.

  Such a magnetic film structure of the TMR element 400 can be said to be similar to the magnetic film structure including the first magnetization fixed layer 122 in the left half of the magnetoresistive effect element 120 shown in FIG. The upper electrode layer 413 of the TMR element 400 shown in FIG. 15 functions as an electrode (corresponding to the electric field applying electrode 150) for applying an electric field to the magnetization free layers 408, 409, and 410 via the insulator layer 412.

  In the TMR element 400 shown in FIG. 15, the substrate 401 is a Si substrate having an oxide film formed on the surface. The lower electrode layer 402 has a two-layer structure in which Ta / Cu are sequentially stacked from the bottom. The upper electrode layer 413 is made of IZO, which is a transparent electrode material. About other members, a material name and a film thickness are shown in FIG. For this reason, hatching is omitted in the cross-sectional view of FIG.

  In order to apply an electric field from the upper electrode layer 413 to the magnetization free layer, specifically, for example, a positive electrode (+) of a voltage application power source that generates a predetermined bias voltage is connected to the lower electrode layer 402 and a negative electrode ( -) May be connected to the upper electrode layer 413. FIG. 15 shows such a state. And the electrical resistance of the film | membrane structure from the lower electrode layer 402 to the upper electrode layer 413 at this time was measured.

As shown in FIG. 15, when an electric field is applied to the magnetization free layer (CoFe / Gd / GdFe) with the lower electrode layer 402 as a base (reference) so that the upper electrode layer 413 has a negative potential (V ₋ ). The positive charges polarized in the magnetization fixed layer 405 accumulate on the interface side with the barrier layer (intermediate layer) 406. At the same time, negative charges polarized in the magnetization free layer 408 accumulate on the interface side with the barrier layer (intermediate layer) 406. That is, polarized charges accumulate at the upper and lower interfaces of the MgO insulating layer. In addition, when the electric field is applied, simultaneously, positive charges polarized in the metal protective layer 411 accumulate on the interface side with the insulator layer 412, and negative charges polarized in the upper electrode layer 413 , Accumulated on the interface side with the insulator layer 412. That is, polarized charges accumulate at the upper and lower interfaces of the SiN insulating layer.

  Here, when charges are sufficiently accumulated at the upper and lower interfaces of the MgO thin film, the electronic state of CoFe on the upper surface side of MgO changes and the coercive force changes. When the coercivity of CoFe changes, the coercivity of GdFe that is magnetically coupled through thin Gd changes. As a result, the coercive force of the entire magnetization free layer is considered to change.

  It should be noted that even if charges are sufficiently accumulated at the upper and lower interfaces of the SiN film, the metal protective layer 411 is not a magnetic film, so it is considered that there is almost no influence on the magnetization free layer.

Further, the positive electrode (+) and the negative electrode (−) of the voltage application power source are switched and connected so that the upper electrode layer 413 becomes a positive potential (V ₊ ) with the lower electrode layer 402 as a base (reference). Applying an external magnetic field large enough to cause magnetization reversal in the magnetization free layer while applying a constant electric field to the magnetization free layer with the bias voltage of the power supply for voltage application. The electrical resistance was measured while changing the direction. When the horizontal axis represents the externally applied magnetic field and the vertical axis represents the electrical resistance, the measurement result is plotted in a graph, and a hysteresis loop (MR curve) showing the magnetization reversal of the magnetization free layer (light modulation layer) from the change in electrical resistance. Can be requested. The coercive force can be obtained from the width of the hysteresis loop on the graph. Furthermore, after changing the condition of the voltage value of the bias voltage, measurement of the coercive force was repeated in the same manner under each condition.

FIG. 16 shows a graph in which each coercive force measured from the loop width of a hysteresis loop on a not-shown graph under each condition (voltage value of each bias voltage) is plotted according to the condition. In the graph of FIG. 16, the horizontal axis represents the bias voltage of the voltage application power source, and the vertical axis represents the coercivity of the magnetization free layer.
The unit of coercive force can be converted by 1 [Oe] = 79.577 [A / m].

In the case of the magnetization free layer used for the measurement at this time, even when the electric field is applied so that the upper electrode layer 413 has a positive potential (V ₊ ), the electric field is set to have a negative potential (V ₋ ). It can be seen that the coercive force of the magnetization free layer also decreases when applied. Since the coercive force of the magnetic film is proportional to the current flowing through the magnetic film, the reversal current of spin injection magnetization reversal can be reduced by applying an electric field to the magnetization free layer. Therefore, when a pulse current for reversing the spin injection magnetization is supplied from the current source to the magnetoresistive effect element, a bias voltage of a voltage application power source different from the current source must be applied to the electric field application electrode 150. Thus, if a predetermined electric field is applied from the electric field applying electrode 150 to the magnetization free layer, the magnetization reversal can be realized with a low current.

  Although the magnetoresistive effect element and the spatial light modulator according to the present invention have been described based on the embodiments, the present invention is not limited to these. For example, the electric field applying electrode 150 is disposed on the upper surface side (upper side in FIG. 3) of the light modulation layer 124, but the side surface side of the light modulation layer 124 (for example, the second magnetization fixed layer 126 is disposed). It is also possible to provide it on the other side. At this time, the insulator material disposed between the side surface of the light modulation layer 124 and the electric field application electrode is preferably a high dielectric constant material. When the electric field application electrode is provided on the side surface side of the light modulation layer 124 as described above, light incident from the upper surface side of the light modulation layer 124 can be incident on the light modulation layer 124 without passing through the electric field application electrode. . Therefore, it is not necessary to use a translucent electrode material as the material for applying an electric field, and a general metal electrode material such as Cu can be applied.

  Further, for example, assuming the pixel array of FIG. 1 (array of magnetoresistive effect elements), one electric field application electrode can be shared by two adjacent pixel columns. Specifically, when an electric field application electrode (positive voltage) is provided on the right side surface (the side where the second magnetization fixed layer 126 is disposed) in each light modulation layer 124 of the pixel array in the first column, the second column This corresponds to providing an electric field application electrode (positive voltage) on the left side (side on which the second magnetization fixed layer 126 is disposed) in each light modulation layer 124 of the pixel array. Therefore, an electric field is applied from the electric field application electrode (positive voltage) to each light modulation layer 124 of the pixel array in the first column, and simultaneously, an electric field is applied to each light modulation layer 124 in the pixel array in the second column. Can do. For this reason, if a plurality of electric field application electrodes (positive voltages) are arranged as in the 1-2 rows, the 3-4 rows,..., The electric field application electrodes necessary for the entire spatial light modulator 100 are obtained. The number can be reduced to ½.

  Further, for example, assuming the pixel array (magnetoresistance effect element array) in FIG. 12, the electric field application electrodes (positive voltage) are arranged between 1-2 columns, between 3-4 columns, and so on. When the electric field application electrode (negative voltage) is further arranged between 2-3 rows, between 4-5 rows,..., The electric field application electrode is provided on the upper surface side of the light modulation layer 124. In comparison, the number of electric field application electrodes necessary for the entire spatial light modulator 100 can be reduced to ½.

100, 100A Spatial light modulator 110 Backplane 111 Substrate 112 First power supply wiring 113 Second power supply wiring 114 Insulator layer 115 Pixel selection signal line 116 First joint wiring 117 Second joint wiring 118 Third joint wiring 120, 120A Magnetic Resistive effect element 121 First electrode 122 First magnetization fixed layer 123 First intermediate layer 124 Light modulation layer (magnetization free layer)
125 Second Intermediate Layer 126 Second Magnetization Fixed Layer 127 Second Electrode 128 Protective Layer 129 Insulating Film 130 Spatial Light Modulation Function Unit 140 Insulator Layer 141 First Insulator Layer 142 Second Insulator Layer 143 Third Insulator Layer 150 151, 152 Electric field application electrode 161, 162, 163, 164, 164A Pixel selection means 170 Write / read power supply 171 Write current source 172 Read power supply 180, 180A Voltage application power supply 181 DC power supply 182 DC power supply 190 Electrical resistance detection means 191 Voltmeter 201 Light source 202 Incident light changing means 203 Outgoing light changing means D Drain S Source G Gate

Claims (6)

A first electrode and a second electrode formed on the substrate;
An insulator layer formed around each electrode to insulate the first electrode from the second electrode;
A first magnetization pinned layer formed on the first electrode;
A second magnetization fixed layer formed on the second electrode;
A first intermediate layer formed on the first magnetization fixed layer;
A second intermediate layer formed on the second magnetization fixed layer;
A magnetization free layer formed on the first intermediate layer and the second intermediate layer, wherein a magnetization direction of the first magnetization fixed layer and a magnetization direction of the second magnetization fixed layer are opposite to each other. A magnetoresistive element that is parallel and modulates light incident on the magnetization free layer by a magnetoresistive effect,
A magnetoresistive effect element comprising an electrode for applying an electric field opposite to the magnetization free layer via the insulator layer. The electric field applying electrode is disposed on the magnetization free layer,
2. The magnetoresistive element according to claim 1, wherein at least a portion of the insulator material laminated on the magnetization free layer is made of a material having a high dielectric constant.   The magnetoresistive element according to claim 1, wherein the magnetization free layer is formed of a multilayer film, and at least one of the layers is a film containing Gd.   The magnetoresistive effect element according to any one of claims 1 to 3, wherein the electric field applying electrode is formed of a translucent material.   5. The magnetoresistive effect element according to claim 1, further comprising two of the electric field applying electrodes facing the magnetization free layer through the insulator layer. 6.   The magnetoresistive effect element according to any one of claims 1 to 5 is arranged in a two-dimensional array on a backplane which is the substrate and has a selective switching circuit, and from the magnetization free layer side. A spatial light modulator characterized by incident polarized light and utilizing reflected or diffracted light.

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