JP2009300941A - Method for manufacturing magneto-optical spatial light modulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform polarization treatment of a piezoelectric body without damaging a TFT while keeping a temperature process rule after following a fundamental concept that a magneto-optical layer, a piezoelectric layer and a thin film transistor circuit layer are accumulated in this order from a lower side and to improve characteristics of the TFT without deterioration of the characteristics of the piezoelectric body. <P>SOLUTION: Defect repairing treatment by steam annealing is performed in a stage that a MOS structure of the TFT is formed after the magneto-optical layer (YIG 12) and the piezoelectric layer (PZT 16) are formed on a substrate 10. Contact holes 30 are formed in a gate electrode and in a source/drain region, a flat conductive film 36 for collectively connecting them through the contact holes is provided, an electric field is applied between the flat conductive film and a common electrode 14 of the piezoelectric layer to perform polarization and then the flat conductive film is removed. Thereby, the magneto-optical layer, the piezoelectric layer and the thin film transistor circuit layer are layered in this order on the substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a magneto-optic spatial light modulator having a TFT (thin film transistor) and controlling a pixel using an inverse piezoelectric effect, and more specifically, a magneto-optic layer and a piezoelectric layer are laminated. Further, after the TFTMOS structure of the thin film transistor circuit layer is fabricated, defect repair processing by annealing is performed, and then a solid conductive film (conductive film covering almost the entire surface) is formed to collectively polarize the piezoelectric layer, and then the remaining processes are performed. The present invention relates to a method of manufacturing a magneto-optic spatial light modulator which is implemented to complete a TFT and an active matrix electric wiring. This technology is useful for a spatial light modulator that modulates incident light into an image file or page data at high speed using the magneto-optical effect in an optical memory, an optical storage, an optical display, or the like.

  The spatial light modulator is a device that spatially modulates the amplitude, phase, or polarization state of incident light, and has a configuration in which a large number of pixel determining elements are two-dimensionally arranged. Since the spatial light modulator having such a two-dimensional array of pixels can process information in parallel at high speed, an optical information processing system, optical computing, projector TV, moving image hologram recording, optical volume recording, etc. It is attracting attention as a key device to be realized. In these fields, since it is necessary to process a large amount of information at high speed, it is important for the spatial light modulator to have a high operating speed and high reliability. Therefore, in recent years, diligent research and development has been progressing on magneto-optical devices utilizing the magneto-optical effect (Faraday effect) of magnetic films.

  Conventional magneto-optic spatial light modulators were current-driven systems that applied and controlled a magnetic field to pixel decision elements by supplying current, but recently, each pixel decision element has been individually utilized using the inverse piezoelectric effect. There has been proposed a voltage drive system that is configured to be able to apply stress and control the magnetization direction of the pixel determining element to reduce power consumption and heat generation (see Patent Document 1). In the latter method, for example, a magneto-optical layer including a large number of pixel determining elements, a piezoelectric body that applies stress to each pixel determining element by being deformed by itself, and each pixel determining element is sandwiched between the piezoelectric bodies. The first and second conductor layers are arranged so as to intersect at positions. Here, when the magneto-optical layer is formed by the LPE method, the composition (lattice mismatch) or the like is designed so that the magnetic spin is intentionally in-plane with respect to the film. Further, by controlling the growth temperature, it is changed to a magnetic spin that is easily oriented in the direction perpendicular to the plane in the crystalline state due to the growth-induced anisotropy. When magnetostriction occurs there, the induced anisotropy is relaxed, and the magnetic characteristics are changed so that the magnetic spin is easily directed in the conventional in-plane direction. Alternatively, since the reversal magnetic field changes due to magnetostriction, the direction of magnetic spin can be controlled using an additional external control magnetic field. As described above, each pixel determining element of the magneto-optical layer changes its magnetic characteristics in accordance with the applied stress and sets the magnetization direction. Since this method is a voltage drive type, since almost no current flows, the problem of heat generation can be solved, and there is an advantage that a high frame speed can be obtained by high-speed operation of a piezoelectric body (PZT: lead zirconate titanate).

  However, such a voltage-driven magneto-optic spatial light modulator has a problem in that the contrast decreases as the number of pixel determining elements increases. Recently, taking advantage of these advantages, TFTs are mounted to form an active matrix drive so that display contrast does not decrease even when the number of pixel determining elements increases, and high reliability of data processing can be maintained. It has been proposed. In the case of such a structure, a major key point in device fabrication is how the magneto-optic layer, piezoelectric layer, and thin film transistor circuit layer are fabricated.

  In the manufacture of a device, there is usually a rule that a layer having a higher process temperature (handling temperature) precedes. In the case of a magneto-optic spatial light modulator, the YIG (yttrium iron garnet crystal film) of the magneto-optic layer has a melting point of about 900 ° C. or higher, so that it is heated to a temperature corresponding to it regardless of the film formation method. In order to improve the characteristics, it is usually heated to about 1000 ° C. or higher by annealing. Next, film formation of a piezoelectric body (for example, PZT) is typically a vapor phase method or a liquid phase method, and is heated to about 600 ° C. in annealing, dehydration, or hydroxyl group firing for extracting crystallinity of the perovskite structure. The On the other hand, the TFT is manufactured at a temperature of about 500 ° C. or less if a low temperature process is used. However, when aluminum is used for the wiring, if the temperature is 550 ° C. or higher, wiring problems occur. Influence distribution. Therefore, considering the process temperature of these components, a structure in which the magneto-optic layer / piezoelectric layer / thin film transistor circuit layer are laminated in this order is appropriate.

However, if such a laminated structure of magneto-optical layer / piezoelectric layer / thin film transistor circuit layer is manufactured in order from the lower layer, the following adverse effects occur.
(1) A polarization process is required for a piezoelectric body, but when the Curie point is reached, the polarization disappears, and usually when the temperature reaches half of the Curie point, the piezoelectric characteristics are significantly deteriorated. For example, PZT belongs to a class having a high Curie point among ferroelectrics, but it is about 360 ° C. Therefore, if the PZT is exposed to a high temperature of 180 ° C. or higher in the process after the polarization treatment, the piezoelectric body does not function. That is, it cannot withstand the process temperature of the thin film transistor circuit layer.
(2) In order to solve this problem, it is conceivable to perform polarization after the thin film transistor circuit layer forming step, but in a device that has been completed up to the thin film transistor circuit layer forming step, the piezoelectric layer is located below the thin film transistor circuit layer, Since one is a common electrode and the other is an individual electrode, in order to polarize, it is necessary to turn on all active matrix TFTs and apply a voltage for polarization to the source side. Therefore, separate voltages must be applied to all gates and sources. Usually, since the number of pixel determining elements is enormous, it is necessary to prepare a special fixture (jig for voltage application) having the same number of styluses as the scanning lines + signal lines. Moreover, in order to completely polarize the piezoelectric body, a large electric field strength is required, but in that case, there is a high possibility that the thin insulating layer of the TFT is destroyed. Therefore, in order to prevent destruction, the spontaneous polarization easily moves at a high temperature near the Curie point and is performed at a relatively low voltage of about 10V. It is not preferable. Thus, the polarization operation becomes extremely difficult.

  Unless these concerns are resolved, mass production of magneto-optic spatial light modulators equipped with TFTs is difficult. However, if the concept of stacking the magneto-optic layer / piezoelectric layer / thin film transistor circuit layer in order from the bottom is overturned, the development effort and cost will be significantly increased.

By the way, although TFT is mounted in flat panel displays, such as a liquid crystal and organic EL, in recent years, about this kind of TFT, the processing method called high pressure steam annealing attracts attention. This is a technique that can realize repair of crystal defects and improvement of interface characteristics by causing a hydrothermal synthesis reaction in a high-pressure steam atmosphere. If this technique is used, defects can be repaired and characteristics can be recovered even with TFTs having degraded characteristics. Although it is considered effective to use high-pressure steam annealing to improve TFT characteristics even in magneto-optic spatial light modulators with a TFT-mounted / inverted-piezoelectric effect system, the function of the piezoelectric material can be improved even if TFT characteristics can be improved by high-pressure steam annealing. May be damaged.
JP 2003-315756 A

  The problem to be solved by the present invention follows the basic concept of stacking from the bottom in the order of magneto-optic layer / piezoelectric layer / thin film transistor circuit layer, observes temperature process rules, and has an enormous number of pixel determining elements. Even in this case, the polarization treatment of the piezoelectric body can be easily performed without damaging the TFT, the characteristics of the piezoelectric body are not deteriorated, and the characteristics of the TFT can be improved. In addition, the increase in the number of photomasks, processes and man-hours can be suppressed to prevent an increase in cost, and complicated jigs for polarization can be eliminated.

  The present invention provides a magneto-optical layer in which a large number of pixel determining elements that give rotation or phase difference in polarization direction to incident light by a magneto-optical effect are arranged, and each pixel determining element is deformed by an inverse piezoelectric effect. A piezoelectric layer having a stress applying element for individually applying stress, and a MOS type TFT for each pixel determining element for selecting the pixel determining element and applying a voltage to the stress applying element, and each TFT TFT driving / reverse piezoelectric effect, comprising a thin film transistor circuit layer formed with active matrix type electrical wiring for selectively driving, and the magneto-optic layer, piezoelectric layer, and thin film transistor circuit layer being laminated in that order on the substrate This is a method of manufacturing a utilization type magneto-optic spatial light modulator.

  Here, in the present invention, after the magneto-optic layer and the piezoelectric layer are formed on the substrate, the defect repair process is performed by annealing at the stage where the MOS structure of the TFT is manufactured, and then the gate electrode, the source / drain region, and even the individual electrode A contact hole is formed, a solid conductive film is provided for collectively connecting the gate electrode, the source / drain region, and the individual electrodes through the contact hole, and a voltage for polarization is applied between the solid conductive film and the common electrode. Then, the piezoelectric body is subjected to polarization treatment, and then the unnecessary portion of the solid conductive film is removed. Alternatively, after changing the order in part, forming the magneto-optic layer and the piezoelectric layer on the substrate, producing the TFT MOS structure, and forming the contact hole to the gate electrode and the source / drain region and further to the individual electrode, Defect repair processing by annealing is performed, and a solid conductive film that collectively connects gate electrodes, source / drain regions and individual electrodes is provided, and polarization processing is performed by applying a voltage for polarization between the solid conductive film and the common electrode. Then, unnecessary portions of the solid conductive film may be removed. The annealing is, for example, a combination of oxygen annealing for improving the characteristics of the oxide film and subsequent water vapor annealing for improving the characteristics of the TFT. The solid conductive film may leave a necessary part in a subsequent process.

  The active matrix electrical wiring is a system in which a voltage for selective driving is applied to the gate of each MOS type TFT, and an output voltage to the stress applying element is transmitted from the source to the drain. In order to apply an electric field to each stress applying element, a common electrode is provided on the magneto-optic layer side, and an individual electrode separated for each pixel determining element is provided on the thin film transistor circuit layer side. The region, the drain wiring, the drain region, and the individual electrode are electrically connected by a plug.

  In the method of manufacturing a magneto-optic spatial light modulator according to the present invention, the magneto-optical layer and the piezoelectric layer are formed on a substrate to produce a MOS structure of a thin film transistor circuit layer, and then a defect repair process is performed by annealing, In addition, a solid conductive film for connecting individual electrodes at once is provided in the source / drain region, and a voltage for polarization is applied between the solid conductive film and the common electrode to perform polarization processing of the piezoelectric body. Therefore, even TFTs whose characteristics have deteriorated during the manufacturing process can repair defects and restore their characteristics, and the piezoelectric material is polarized at one point between two points, the lower common electrode and the upper solid conductive layer. Since it can be implemented by applying a polarization voltage only to the TFT, a special jig for touching each electrode of all TFTs is not necessary, and there is no fear of damaging the TFTs. Possible to manufacture a magneto-optic spatial light modulator of a T mounted and inverse piezoelectric effect utilized. Since this magneto-optic spatial light modulator incorporates the usefulness of active matrix driving, it has excellent display capability, is voltage driven, has low power, and can operate at high speed.

  The magneto-optic spatial light modulator manufactured by the method of the present invention is deformed by a magneto-optic layer in which a large number of pixel determining elements that give rotation or phase difference of the polarization direction to incident light are arranged by the magneto-optic effect and an inverse piezoelectric effect. A piezoelectric layer having a stress applying element that individually applies stress to each pixel determining element, and for each pixel determining element for selecting the pixel determining element and applying a voltage to the stress applying element. A thin film transistor circuit layer in which an active matrix type electric wiring for selectively driving each TFT is formed and a MOS type TFT is provided, and the magneto-optic layer, the piezoelectric layer, and the thin film transistor circuit layer are stacked in that order on the substrate. This is the structure.

  The active matrix electrical wiring is a system in which a voltage for selective driving is applied to the gate of each MOS type TFT, and an output voltage to the stress applying element is transmitted from the source to the drain. The piezoelectric layer has a structure in which a common electrode is provided on the magneto-optical layer side and an individual electrode separated for each pixel determining element is provided on the thin film transistor circuit layer side in order to apply an electric field to each stress applying element. . In these, the source wiring and the source region, the drain wiring, the drain region, and the individual electrode are electrically connected by a plug.

  In the present invention, after the magneto-optic layer and the piezoelectric layer are formed on the substrate, the TFT MOS structure of the thin film transistor circuit layer is manufactured, and defect repair processing is performed by annealing, and the gate electrode, the source / drain region, and the individual electrode are formed. A solid conductive film connected in a lump is provided, and a voltage for polarization is applied between the solid conductive film and the common electrode to polarize the piezoelectric body. In this way, during TFT manufacturing, defect repair processing by annealing is performed, once a solid conductive film is provided and polarization processing is performed, and then the remaining TFT manufacturing process is restarted. There are features.

  The main manufacturing process of the present invention is shown in FIG. First, as shown in FIG. 1A, a magneto-optical layer, a piezoelectric layer, and a thin film transistor circuit layer are laminated up to the MOS structure which is the main part of the TFT. The steps up to here are basically the same as those in the conventional method, and will be described briefly. A YIG layer (magneto-optic layer) is grown on the garnet substrate 10. The magneto-optic layer includes a number of pixel determining elements (YIG) that can set the magnetization direction and rotate the polarization direction of incident light by the magneto-optic effect. Here, the pixel determining elements are separated from each other by, for example, a structure in which YIG 12 is embedded in each pixel region of the garnet substrate 10 so that the magnetization directions can be set independently. On top of this, a common electrode 14 also serving as a mirror, a PZT (piezoelectric body) 16, and an individual electrode 18 corresponding to each pixel determining element are formed. Next, a base film 20, ion-implanted Si source / drain regions 22, a gate insulating film 24 and a gate electrode 26 are formed, and finally an interlayer insulating film 28 is formed.

Step A: Annealing Treatment As described above, annealing for defect repair is performed when the MOS structure of the TFT is manufactured (see A in FIG. 1). The annealing performed here is oxygen annealing and high-pressure steam annealing. The oxygen annealing is high-temperature annealing (500 ° C. or lower) performed in an oxygen atmosphere, and is a post-treatment for improving the characteristics of the oxide film. A relatively good insulating film can be obtained by manufacturing an oxide film by a CVD method or a reactive sputtering method. However, a porous film is formed by a simple RF sputtering method, and abnormal dissolution occurs during wet etching such as HF. It may be difficult to control the formation of contact holes. Oxygen annealing condenses the film density and facilitates the control of etching with HF. High pressure steam annealing is a technique for forming a stable oxygen film by repairing crystal defects and improving interface characteristics by causing a hydrothermal synthesis reaction in a high pressure steam atmosphere (260 ° C.). Empirically, when dry etching using Ar ions is used for patterning the TFT, the electrical characteristics of the TFT deteriorate. However, the electrical characteristics can be recovered by performing high-pressure steam annealing on the TFT having deteriorated characteristics.

Step B: Contact hole formation Next, for the MOS structure of each TFT, a contact hole for forming a plug in the gate electrode and the source / drain region, and further a contact hole reaching the individual electrode of the piezoelectric layer from the drain region (contact) are formed. A hole is indicated by reference numeral 30), and one via hole 32 is formed so as to reach the common electrode of the piezoelectric layer (see B in FIG. 1). These are performed by wet etching with HF (hydrofluoric acid).

Step C: Solid conductive film formation, polarization treatment Thereafter, a solid conductive film 34 for connecting the gate electrode and the source / drain regions and the individual electrodes at once is provided on the uppermost layer, and polarization is applied between the solid conductive film 34 and the common electrode 14. PZT is polarized by applying a voltage V for the purpose (see C in FIG. 1). It should be noted that both the solid conductive film and the ridge are masked only at least around the via hole 32 so that the conductive film does not adhere. A conductive material is buried in the contact hole by the uppermost solid conductive film 34, and each individual electrode, gate electrode, source / drain region, etc. are all short-circuited, so that the two areas of the solid conductive film 34 and the common electrode 14 are touched. A voltage necessary for polarization can be easily applied by simply needle-making. At that time, since the MOS structure of the TFT is short-circuited, no voltage is applied to the gate insulating film 24, and no current flows through the semiconductor. Therefore, even if a large voltage for polarization is applied at a high temperature, the MOS structure There is no fear of being destroyed. For example, the polarization operation is performed at 200 ° C. and an electric field strength of 6 kV / mm.

Step D: Contact Plug Formation Finally, in order to perform predetermined patterning, unnecessary portions of the solid conductive film used for polarization are removed by etching to form contact plugs 36 (see D in FIG. 1). Not only the contact plug but also the wiring 38 can be formed at the same time. Aluminum is selected as the material for the solid conductive film, and the solid conductive film is removed by chemical or physical etching (for example, wet etching) that is friendly to the TFT. The remaining steps of manufacturing the thin film transistor circuit layer may be the same as in the prior art. In addition, after performing various improvement processes by heat treatment, in order to avoid a step of deteriorating film quality such as milling, electroless plating is performed if gold plating is necessary.

  In this way, a magneto-optic spatial light modulator with TFT can be manufactured. The details are shown in FIG. On the garnet substrate 10, a magneto-optic layer (YIG) 40, a piezoelectric layer (PZT) 42, and a thin film transistor circuit layer 44 are laminated in that order. The thin film transistor circuit layer 44 has an active matrix for selecting and driving the TFTs for each pixel determining element in order to select the pixel determining element and maintain the voltage application state to the stress applying element. This is a structure in which a type electric wiring is formed.

  This spatial light modulator is a reflection type in which a mirror is provided on the back side of each pixel determining element. The YIG constituting the magneto-optical layer 40 is a film having a magnetization direction in a direction perpendicular to the film surface, and is magnetized by rotating the internal magnetic spin according to the magnitude and direction of the stress direction received from the piezoelectric layer 42. The optical effect changes, and the TFT maintains the strained state by the piezoelectric layer 42 for a necessary time. The piezoelectric layer 42 has a structure in which PZT is sandwiched between two types of electrodes, and one electrode (a lower electrode located on the magneto-optical layer side) is a common electrode 14 that also serves as a mirror, and the other electrode The upper electrode (here, the upper electrode) is an individual electrode 18 separated according to the projected shape and arrangement of each pixel determining element, and is located on the thin film transistor circuit layer side.

  FIG. 3 is an explanatory diagram of the active matrix type electrical wiring in which the plane of the thin film transistor circuit layer is shown in perspective. The active matrix type electric wiring 50 includes a scanning line, a signal line, a common line, and the like. Here, the scanning lines and the signal lines are formed in the gap between the pixel determining element and the pixel determining element, and the TFT 48 is arranged offset from the center of the pixel determining element 52.

  Next, control of the magnetization direction by voltage drive will be briefly described with reference to FIG. For easy understanding, the deformation of PZT is drawn extremely large in the figure. Since the TFT (switch element) 48 is off when there is no voltage, no stress is applied to YIG. Since the magnetization direction is perpendicular to the film surface, the thickness of YIG contributes to Faraday rotation. When the signal is turned on, as shown in FIG. 4, a voltage is applied to the upper and lower surfaces of the PZT 16 and a stress is applied to the YIG 12. When the PZT 16 is extended and deformed, the YIG 12 receives a compressive stress. As a result, the anisotropy energy of the internal magnetic spin is reduced and the magnetization direction is easily rotated. Therefore, when an external magnetic field is applied, the deformation of PZT 16 is triggered to align the magnetization direction with the direction of the external magnetic field. If the magnetization direction is rotated 180 degrees, the Faraday rotation is reversed. When the signal is off, the accumulated charges remain in the PZT partitioned by the individual electrodes, and the magnetic field on state is maintained. Incident light is transmitted through the garnet substrate 10 and the YIG 12, reflected by the common electrode 14, and then transmitted through the YIG 12 and the garnet substrate 10 to be emitted. While the light travels back and forth through the YIG 12, the plane of polarization rotates by a predetermined angle in the + direction or the-direction.

  FIG. 5 shows a spatial modulation method of page data using the spatial light modulator configured as described above. The light from the light source 60 is converted into linearly polarized light by the lens / polarizer 62 and applied to the spatial light modulator 64. Reflected light from the spatial light modulator 64 is converted into light contrast by the lens / analyzer 66 according to the plane of polarization, and input to the detector (C-MOS) 68 to modulate incident light into page data. be able to.

  An example of the production conditions of the prototype magneto-optic spatial light modulator will be described. A YIG (magneto-optic layer) was formed on the GGG substrate. YIG is a bismuth-substituted yttrium iron garnet single crystal film grown on a GGG substrate by the LPE (liquid phase epitaxial) method. The film thickness is 2 μm, and the polarization plane rotates 9 degrees in a single pass. Since the product of the present invention is a reflective device, it has a Faraday rotation angle of 18 degrees in a double pass. Here, in order to make a pixel into a cell and prevent magnetic interference between the pixels, the YGG is embedded in each pixel determining element in the GGG substrate. The pixel pitch is 16 μm and the inter-pixel gap is 2 μm.

  PZT (piezoelectric body) was laminated via a common electrode that also served as a mirror, and individual electrodes were formed thereon. The common electrode also serving as a mirror is a Ti / Pt film (Ti closer to PZT), and was formed by RF magnetron sputtering. The film thicknesses are Ti: 20 nm and Pt: 200 nm. The reflectivity as a mirror was 30% (wavelength: 532 nm). PZT was produced by AD method (aerosol deposition method). The film thickness of PZT was 5 μm, and after the film formation, annealing was performed in the atmosphere at 600 ° C. After the annealing treatment, CPM was applied to obtain a finish with a flatness of about 10 nm.

Next, a part of the thin film transistor circuit layer (up to the MOS structure of the TFT) was provided. On the individual electrode, an undercoat, a Si film serving as a source / drain region of the TFT, a gate insulating film (SiO ₂ film), a gate electrode, and an overcoat were sequentially provided. The Si and SiO ₂ films were formed by RF magnetron sputtering at an RF power of 100 W, a back pressure of 10 ⁻⁷ Torr, a gas pressure of 0.5 Pa, and a substrate heating of 250 ° C. The film thickness is Si: 50 nm and the gate insulating film (SiO ₂ ): 150 nm. Patterning used Ar ion milling. The gate electrode is Ti / Pt, and the film thicknesses are Ti: 20 nm and Pt: 200 nm. Excimer laser annealing (ELA) conditions are gas type KrF, homogenizer energy distribution of 10% or less, spot size □ 5 mm, pulse width 50 ns, energy density 120 mJ / cm ² , and 25 shots. The ion implantation conditions are through the SiO ₂ film (150 nm). The implanted element is P, the input energy is 110 keV, the dose is 2 × 10 ⁺¹⁵ / cm ² , and the activation annealing is 500 ° C., 3 hours, and the N ₂ atmosphere.

  At the stage where the TFT MOS structure is fabricated in this way, oxygen annealing (temperature: 500 ° C.) is performed, and further high-pressure steam annealing (temperature: 260 ° C., pressure: 1.6 MPa, top temperature holding time: 1 hour) is performed. It was. Next, contact holes were formed up to the gate electrode, source / drain regions and even individual electrodes, and via holes were also formed in the common electrode. These were performed by wet etching with a 10-fold dilution of buffered HF.

  A solid conductive film for polarization was formed on the uppermost layer. The solid conductive film is an aluminum film and has a thickness of 200 nm. Then, in the heating furnace, a voltage for polarization was applied between the common electrode for the polarization solid conductive film and the piezoelectric layer to perform polarization treatment of the piezoelectric body. The polarization work was performed at 200 ° C. by applying a voltage of 30 V for 15 minutes. As for the obtained PZT characteristics, the relative dielectric constant was 800, and the d31 constant (index of the magnitude of strain) was 80 pm / V. Thereafter, the solid conductive film for polarization was removed by etching, and the source / drain electrode was patterned on the top to provide a contact plug. The source / drain electrode was connected to a signal line provided thereon.

  The evaluation results of the piezoelectric body will be described. FIG. 6 shows the polarization-applied electric field characteristics using the applied voltage during polarization as a parameter. As described above, an important PZT strain constant of 80 pm / V was obtained, and it was confirmed that there was no problem in operation as a piezoelectric body for a magnetic spatial light modulator.

  Next, evaluation results of the thin film transistor will be described. The driving condition was that the source grounded input Vd = 10 V and the gate Vg = 15 V were applied. FIG. 7 shows an Ids-Vgs characteristic (logarithmic display) using Vds as a parameter. It was confirmed that there was no problem in operation as a TFT.

  From these results, the temperature process rule was observed and the magneto-optical spatial light modulator operated well. As described above, PZT was a good product even when viewed from the measured numerical values. The TFT was also a non-defective product in terms of electrical characteristics, despite the irregular manufacturing process.

Explanatory drawing of the manufacturing process of the magneto-optic spatial light modulator which concerns on this invention. The block diagram of the obtained magneto-optical spatial light modulator. Explanatory drawing of an active matrix type electrical wiring. Explanatory drawing of the control of the magnetization direction by voltage drive. Explanatory drawing of the spatial modulation method of the page data using a spatial light modulator. The characteristic diagram for evaluating a piezoelectric material. Ids-Vgs characteristic (logarithm display) diagram of TFT.

Explanation of symbols

10 Garnet substrate 12 YIG
14 Common electrode 16 PZT
18 Individual Electrode 20 Base Film 22 Source / Drain Region 24 Gate Insulating Film 26 Gate Electrode 28 Interlayer Insulating Film 30 Contact Hole 32 Via Hole 34 Solid Conductive Film 36 Contact Plug

Claims (4)

A magneto-optical layer in which a large number of pixel determining elements that give rotation or phase difference in polarization direction to incident light by the magneto-optical effect are arranged, and stress is individually applied to each of the pixel determining elements by deformation by the inverse piezoelectric effect. A piezoelectric layer having a stress applying element to be applied, and a MOS type TFT for each pixel determining element for selecting the pixel determining element and applying an electric field to the stress applying element, and selectively driving each TFT. A TFT-driven / inverted-piezoelectric-effect-type magnetism comprising a thin film transistor circuit layer having active matrix electrical wiring formed thereon, and the magneto-optic layer, piezoelectric layer, and thin film transistor circuit layer being laminated on the substrate in that order. In a method of manufacturing an optical spatial light modulator,
When the magneto-optic layer and the piezoelectric layer are formed on the substrate and the MOS structure of the TFT is fabricated, defect repair processing is performed by annealing, then a contact hole is formed to the gate electrode, the source / drain region, and further to the individual electrode, A solid conductive film that collectively connects the gate electrodes, source / drain regions, and individual electrodes through the contact holes is provided, and a polarization voltage is applied between the solid conductive film and the common electrode to polarize the piezoelectric body. And then removing unnecessary portions of the solid conductive film. A method of manufacturing a magneto-optical spatial light modulator. A magneto-optical layer in which a large number of pixel determining elements that give rotation or phase difference in polarization direction to incident light by the magneto-optical effect are arranged, and stress is individually applied to each of the pixel determining elements by deformation by the inverse piezoelectric effect. A piezoelectric layer having a stress applying element to be applied, and a MOS type TFT for each pixel determining element for selecting the pixel determining element and applying an electric field to the stress applying element, and selectively driving each TFT. A TFT-driven reverse piezoelectric effect-based magneto-optical system comprising a thin-film transistor circuit layer on which active matrix electrical wiring is formed, and the magneto-optical layer, piezoelectric layer, and thin-film transistor circuit layer formed in that order on the substrate. In a method of manufacturing a spatial light modulator,
After forming the magneto-optic layer and the piezoelectric layer on the substrate, the MOS structure of the TFT is fabricated, and at the stage where the contact hole is formed to the gate electrode, the source / drain region and even the individual electrode, defect repair processing is performed by annealing, and the gate A solid conductive film for connecting electrodes and source / drain regions as well as individual electrodes is provided, and a voltage for polarization is applied between the solid conductive film and the common electrode to perform polarization treatment of the piezoelectric body. A method of manufacturing a magneto-optic spatial light modulator, wherein an unnecessary portion of the solid conductive film is removed.   3. The method of manufacturing a magneto-optic spatial light modulator according to claim 1, wherein the annealing is a combination of oxygen annealing for improving characteristics of an oxide film and subsequent water vapor annealing for improving characteristics of the TFT.   The active matrix electrical wiring is a system in which an electric field for selective driving is applied to the gate of each MOS type TFT, and an output voltage to the stress applying element is transmitted from the source to the drain. In order to apply an electric field to each stress applying element, a common electrode is provided on the magneto-optic layer side, and an individual electrode separated for each pixel determining element is provided on the thin film transistor circuit layer side. 4. The method of manufacturing a magneto-optic spatial light modulator according to claim 1, wherein the region, the drain wiring, the drain region, and the individual electrode are electrically connected by a plug.

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