JPH08148588A - Optical storage and writing/reading devices for it - Google Patents

Abstract

PURPOSE: To provide an optical storage which can speedily rewrite random information. CONSTITUTION: A floating gate 5 of a memory cell which is an electric charge accumulation layer has a larger area than a control gate 7, its one portion protrudes from the overlapped part with the control gate 7, and electric field which is terminated at a light reflection layer 15 of the reverse side via the inside of a substrate 1 is generated at this part. Information is written to the memory cell by setting a drain region 3 and a control gate 7 of a specific memory cell selected by a selection circuit as a positive potential for a source region 2 and by injecting generated hot electrons into the floating gate 5. Information is read out (reproduced) by applying light to the floating gate 5 and reading the change of polarization due to the influence of fringe electric field Ef generated at the edge part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device for reproducing (reading) information by using light, and more particularly to an optical storage device capable of rewriting information at high speed and at random.

[0002]

2. Description of the Related Art A CD (Compact Disc) is generally known as a storage device for reading information by using light. The CD irradiates a laser beam on a pit row (uneven surface) formed on the surface of the disk and reads the difference in reflectance due to the unevenness as information, and the currently popular one is reproduction only.

Regarding an optical disk in which information can be rewritten, for example, "Rewritable optical disk material" (1989)
Year, published by the Industrial Research Council).

Rewritable optical disks include magneto-optical disks that utilize the magneto-optical effect and optical disks that utilize phase change. Magneto-optical discs use perpendicularly magnetized films and record information by changing the direction of magnetization by the heat of a magnetic field and laser light. For reproduction, laser light is irradiated to rotate the plane of polarization of the light. A method of detecting is used. On the other hand, a phase change type optical disc is one in which information is recorded by changing the phase of a disc material by heating with a laser beam, and a method of irradiating a laser beam and reading a difference in reflectance due to a phase is used for reproduction. .

[0005]

However, in the above-described conventional rewritable optical disk, as in the case of reproduction, since the storage units (bits) are sequentially accessed by the mechanical mechanism to perform the rewriting, However, there is a drawback that it takes time to rewrite.

An object of the present invention is to provide an optical storage device capable of high speed and random rewriting of information.

Another object of the present invention is to provide a writing device for writing information in the above optical storage device.

Another object of the present invention is to provide a reading device for reproducing the information written in the optical storage device.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0010]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

In the optical storage device of the present invention, an electrically writable charge storage layer is provided in a part of a material having an electro-optical effect, and a fringe electric field corresponding to the presence or absence of charges injected into the charge storage layer is applied. The change in polarization is read as information.

In the optical storage device of the present invention, a first substrate on which an electrically writable charge storage layer is formed and a second substrate made of a material having an electro-optical effect are arranged to face each other. A change in polarization due to a fringe electric field corresponding to the presence or absence of charges injected into the charge storage layer of the first substrate is read as information.

In the optical storage device of the present invention, a pair of electrodes and a ferroelectric layer sandwiched between them are formed on a substrate, and spontaneous polarization of the ferroelectric layer is generated by applying voltages having different polarities. The change in direction is read as information.

[0014]

According to the above means, an electric field is generated in the vicinity of the material having the electro-optical effect due to the charges in the charge storage layer provided in or near the material and the electric field of the electro-optical effect material in the vicinity thereof is generated. A slight anisotropy is generated in the refractive index, and the deflecting surface of the laser light is rotated. For example, if the analyzer is rotated so that the intensity of light is maximum and the intensity is minimum when there is no electric charge in accordance with the deflection surface when there is electric charge, the light intensity according to the presence or absence of electric charge Changes can be detected.

Information can be electrically rewritten by setting the presence or absence of charges in the charge storage layer as an information unit. When the polarization of a ferroelectric substance is used, information can be electrically rewritten and read by light in the same manner. As described above, it is possible to rewrite information at random, especially at high speed.

As another method of injecting charges, the charge storage layer may be irradiated with an electron beam. In this case, the substrate does not have to be a semiconductor, and it is not necessary to integrate a circuit for writing on the substrate.

By providing another conductive layer having a potential difference from the charge storage layer at a position close to the charge storage layer, the electric field strength generated therebetween can be increased and the effect on light can be enhanced.

When a material having an electro-optical effect is brought close to the substrate, even when the charge storage layer is arranged on the substrate having no electro-optical effect, the change in polarization due to the fringe electric field corresponding to the presence or absence of electric charge is prevented. It can be read as information.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, those having the same function are designated by the same reference numeral, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a plan view showing a memory cell (for 4 bits) of an optical storage device according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line II-II 'in FIG. It is a figure.

The memory cell of this optical storage device is formed on the main surface of a substrate 1 made of a compound semiconductor such as GaAs, which has a so-called electro-optical effect, whose optical properties change in an electric field.

The memory cell is an EE which is a kind of semiconductor memory.
PROM (Electrically Erasable Programable Read On
a source region 2 and a drain region 3 formed on the substrate 1, a floating gate (charge storage layer) 5 formed on the substrate 1 via a first gate insulating film 4, and A control gate 7 is formed on the floating gate 5 via a second gate insulating film 6, and one memory cell stores 1-bit information.

The source region 2 of each memory cell has an insulating film 8
The drain region 3 is connected to the wiring 11 via the ohmic electrode 10 in the connection hole 9 opened in the above, and the drain region 3 is opened via the ohmic electrode 10 in the other connection hole 9 opened in the insulating film 8. It is connected to the wiring 12. The control gate 7 of each memory cell extends in a direction orthogonal to the wirings 11 and 12 and is connected to a wiring (word line) 13 formed integrally with the control gate 7. Although not shown, these wirings 11, 12, and 13 are connected to a selection circuit (X address decoder and Y selection circuit) for selecting a memory cell.
Address decoder), power supply circuit, etc.

A large number of memory cells as described above are formed in a matrix on the main surface of the substrate 1 to form a memory array. Further, a surface protection film 14 for covering the memory cells and the wirings 11, 12, 13 is formed on the front surface of the substrate 1, and a light reflection film formed by depositing a metal film on the back surface of the substrate 1. The layer 15 is formed.

3 and 4 are enlarged perspective views of one memory cell. In addition, these figures show the wiring 1
Illustration of 1, 12, and 13 is omitted.

To write information to the memory cell, the drain region 3 and the control gate 7 of a predetermined memory cell selected by the selection circuit are set to a positive potential with respect to the source region 2 as in the case of the EEPROM of the semiconductor memory. The generated hot electrons are injected into the floating gate 5. Information is erased by grounding the control gate 7, applying a positive high voltage to the substrate 1, and drawing out electrons from the floating gate 5.

The optical storage device of the present embodiment uses the electro-optical effect, unlike the conventional optical disc, etc., in the physical phenomenon used when reading (reproducing) information.

As shown in FIG. 3, the floating gate 5, which is a charge storage layer, has a larger area than the control gate 7, and has a structure in which a part of the floating gate 5 extends horizontally from a portion overlapping the control gate 7. , Fig. 5
As shown in FIG. 5, an electric field is generated in this portion, which passes through the substrate 1 and terminates in the light reflection layer 15 on the back surface thereof. To read (reproduce) information, this portion is irradiated with light from above the substrate 1,
This is performed by reading the change in polarization due to the influence of the fringe electric field Ef generated at the end of the floating gate 5.

FIG. 6 is a block diagram showing an example of a reading device used for reproducing information in the optical storage device of this embodiment.

The reading device is not particularly limited, but the laser diode 71 as the light source and the parallel lens 7 are used.
2, a polarizer 73, a half mirror 74, an objective lens 75,
It is composed of an analyzer 77, a photodiode 78, an amplifier 79 and the like.

For reading information, laser light L is linearly polarized by a polarizer 73 beside the charge storage layer (floating gate 5) of the memory cell formed on the main surface of the substrate 1.
Reflected light L radiated by ₁ and returned through the half mirror 74
_The analyzer 77 detects that the polarization state of No. ₂ is changed by the fringe electric field corresponding to the presence or absence of charge, and the photodiode 78 converts this into an electric signal S.

Next, an example of a method of manufacturing the optical storage device of this embodiment will be described with reference to FIGS.
Will be explained.

First, as shown in FIG. 7, p ^- type GaA is used.
After depositing a silicon oxide film on the substrate 1 made of s by the CVD method to form the first gate insulating film 4, a polycrystalline silicon film 5A is deposited on the first gate insulating film 4 by the CVD method.

Next, as shown in FIG. 8, the floating gate (charge storage layer) 5 of the memory cell is formed by patterning the polycrystalline silicon film 5A by dry etching using the photoresist 18A as a mask.

Next, after removing the photoresist 18A, as shown in FIG. 9, a silicon oxide film is deposited on the substrate 1 by the CVD method to form a second gate insulating film 6, and then the floating gate 5 is formed. And using the new photoresist 18B as a mask, an n-type impurity (for example, S
i) is ion-implanted.

Next, after removing the photoresist 18B, the source region 2 and the drain region 3 of the memory cell are formed by annealing the substrate 1 to activate the impurities as shown in FIG. Then, a polycrystalline silicon film 7A is deposited on the substrate 1 by the CVD method.

Next, as shown in FIG. 11, the polycrystalline silicon film 7A and the second gate insulating film 6 are patterned by dry etching using the photoresist 18C as a mask to control the memory cell control gate 7 (and FIG. A wiring 13) not shown in 11 is formed.

Next, after removing the photoresist 18C, as shown in FIG. 12, the first gate insulating film 4 on the source region 2 and the drain region 3 is removed by etching to expose the exposed source region 2 and drain. An ohmic metal film such as AuGe / Ni / Au is deposited on the surface of the region 3 by an electron beam evaporation method or the like to form the ohmic electrode 10.

Next, as shown in FIG. 13, C is formed on the substrate 1.
After depositing an insulating film 8 of silicon oxide or the like by the VD method, the insulating film 8 on the ohmic electrode 10 is removed by etching to form a connection hole 9 and then, as shown in FIG. A metal film such as Au or Al is deposited by a method or the like, and is patterned to form the wirings 11 and 12. At this time, the same metal film is deposited on the back surface of the substrate 1 to form the light reflection layer 15. After that, an insulating film such as silicon oxide is deposited on the substrate 1 by the CVD method to form the surface protection film 14, thereby completing the memory cell of the optical storage device shown in FIGS.

The floating gate 5 and the control gate 7 of the memory cell are not limited to polycrystalline silicon and W
It may be composed of a refractory metal silicide such as Six or Al, or a laminated film of them and polycrystalline silicon.

In this embodiment, the charge storage layer is composed of the floating gate 5. However, for example, the memory cell is composed of MNOS.
(Metal Nitride Oxide Semiconductor) structure,
Electric charges may be accumulated at the interface between the silicon oxide film and the silicon nitride film.

An EEPROM-like integrated circuit is formed on the main surface of a substrate made of a material having no electro-optical effect (eg, Si), and a second substrate having an electro-optical effect (eg, GaAs substrate) is formed on the surface. ) And irradiate light, an optical storage device similar to that of this embodiment can be obtained. As the second substrate material having the electro-optical effect, in addition to GaAs, an inorganic electro-optical material such as LiNbO ₃ or various organic electro-optical materials can be used.

A substrate made of a material having an electro-optical effect (eg, GaAs) is attached to a substrate made of a material having no electro-optical effect (eg, Si), or GaAs is formed by MOCVD, MBE, or the like. Crystals may be grown.

(Second Embodiment) FIG. 15 shows a second embodiment of the present invention.
16 is a plan view showing a memory cell (for 6 bits) of the optical storage device, and FIG. 16 is a cross-sectional view taken along line XVI-XVI 'of FIG.

The memory cell of the optical storage device of the present embodiment is formed on the main surface of the substrate 1 made of GaAs having the electro-optical effect as in the case of the first embodiment.
Unlike the memory cell of, the source region 2 and the drain region 3
Are not provided separately, and these are not provided in one n ⁺ type semiconductor region 1
High integration has been realized by integrally forming with 7.

To write information, the n ⁺ type semiconductor region 17 is grounded and the control gate 7 is set to a positive potential.
Electrons are injected into the floating gate 5 using a Fowler-Nordoheim tunnel. In addition, information is erased by the n ⁺ type semiconductor region 17,
The control gate 7 is set to a positive potential, and the electrons in the floating gate 5 are extracted by the Fowler-Nordheim tunnel. Reading (reproduction) of information is performed by the same method as in the first embodiment.

(Third Embodiment) FIG. 17 shows a third embodiment of the present invention.
18 is a plan view showing a memory cell of the optical storage device of FIG.
FIG. 18 is a cross-sectional view taken along line XVIII-XVIII ′ of FIG.

The optical storage devices of Examples 1 and 2 use the substrate 1 having an electro-optical effect, and read the change in polarization due to the influence of the fringe electric field generated at the end of the charge storage section to obtain information. Although reading (reproducing) is performed, the optical storage device of the present embodiment reads information by utilizing the spontaneous polarization of the ferroelectric substance in the electric field.

Memory cell MC of the optical storage device of this embodiment
Is composed of a pair of electrodes (lower electrode 21 and upper electrode 22) formed on the main surface of the substrate 20 made of, for example, Si or GaAs, and a ferroelectric layer 23 sandwiched between them. The memory cell stores 1-bit information.

The ferroelectric layer 23 is made of (Ba, Sr) Ti.
A ferroelectric thin film such as O, TiO, YO, PZT, and PLZT is deposited and formed on the substrate 20 by using a sputtering method or the like. The lower electrode 21 and the upper electrode 22 are formed by patterning a metal film such as Au or Al deposited on the substrate 20 by using a sputtering method or the like. Although not shown, the lower electrode 21 and the upper electrode 22 are selected by a selection circuit (X address decoder and Y selection circuit) for selecting a memory cell.
Address decoder), power supply circuit, etc.

As shown in FIG. 17, the lower electrode 21 and the upper electrode 22 extend in the direction intersecting with each other on the main surface of the substrate 20, and one memory cell is formed at each intersection. In addition, as shown in FIG.
A surface protective film 14 that covers the lower electrode 21, the upper electrode 22, and the ferroelectric layer 23 is formed on the surface of the.

Information is written by applying a voltage with a changed polarity between a pair of electrodes (lower electrode 21 and upper electrode 22) of the memory cell, and reading (reproduction) is performed by the ferroelectric between the pair of electrodes. The light L is applied to the body layer 23, and the phase change of the reflected light due to the difference in the spontaneous polarization direction of the ferroelectric layer 23 is read by using, for example, the reading device of the first embodiment (see FIG. 6).

(Fourth Embodiment) FIG. 19 shows a fourth embodiment of the present invention.
20 is a plan view showing a memory cell of the optical storage device of FIG.
FIG. 20 is a sectional view taken along line XX-XX ′ of FIG. 19.

The optical storage device of this embodiment is, for example, Si, G
A first electrode (charge storage layer) 30 for injecting charges and a second electrode 31 are arranged close to each other on a main surface of a substrate 20 made of aAs or the like, and they are arranged in an organic film 32 having an electro-optical effect.
Covered with. The second electrode is common to each memory cell, does not inject charges, is in a floating state, or is connected to a fixed potential such as ground.

Between the first electrode 30 and the second electrode 31,
An electric field is generated depending on the presence / absence of charges in the charge storage layer (first electrode 30) that passes through the organic film 32, which is a material having an electro-optical effect, so that the light L is applied to the electric field to polarize the polarization plane of the reflected light. It is possible to read (reproduce) the information by detecting the change of. The light L is applied to the first electrode 30 from above the substrate 20.
The first electrode 30 may be provided on the electro-optical effect material, and the information may be read by applying light from the back surface of the substrate 20.

FIG. 21 is a block diagram showing an example of a writing device for writing information in the optical storage device of this embodiment.

In this writing device, a MOSFET Q, a resistor 34, a selectable electrode 35 for writing, an X address decoder 4 are provided on the main surface of a substrate 33 different from the above optical storage device.
0, Y address decoder 41, power supply circuits 42, 43, etc. are integrated.

When writing information, the main surface of the substrate 33 is brought into close contact with the main surface of the substrate 20 of the optical storage device or 1 μm.
To a certain degree, the polarities of the power supply circuits 42 and 43 of the writing device are synchronously changed to output a voltage to the electrode 35, and the opposite first electrode (charge storage layer) 30 of the optical storage device is provided.
Inject charge into.

In order to bring the substrate 33 of the writing device close to the substrate 20 of the optical storage device, a spacer is provided between the substrates 20 and 33, or the substrate 33 is floated above the substrate 20 by air pressure or the like. The electrode 35 of the writing device is shown in FIG.
The shape is not limited to the flat plate shape as shown in FIG.

In the optical memory device of this embodiment, the first electrode 30 and the second electrode 31 may be covered with a normal insulating film such as silicon oxide instead of the organic film 32 having an electro-optical effect. In that case, information can be similarly read by irradiating light on a substrate made of a material having an electro-optical effect on an ordinary insulating film. Further, in that case, if the transparent electrode is adhered to the substrate having the electro-optical effect, the second electrode 31 is also unnecessary, so that the integration degree of the optical storage device can be improved.

(Fifth Embodiment) FIG. 22 shows a fifth embodiment of the present invention.
23 is a plan view showing the optical storage device of FIG.
It is a sectional view taken along the line III-XXIII '. Also, FIG.
Also shown is a writing device 50, a reading device 60 and an alignment mechanism 61.

In the optical memory device of this embodiment, the electrode 52 connected to a fixed potential such as ground is formed over the entire main surface of the substrate 51, and the ferroelectric layer 5 is formed on the electrode 52.
3, 54 and a large number of light reflection layers 55 are provided. The ferroelectric layers 53 and 54 may be uniformly formed on the entire surface of the substrate 51.

To write information, the writing device 50 of the fourth embodiment (see FIG. 21) is arranged on the substrate 51 of the optical storage device so as to face it, and first, the light reflecting layer 55 is read by the reading device 60 using light. Read the position of. Next, the alignment mechanism 61 is driven based on this information, and the writing electrode 35 formed on the main surface of the substrate 33 of the writing device 50 corresponds to the ferroelectric layers 53 and 54 of the optical storage device. After the alignment as described above, the predetermined electrode 35 is selected by the circuit (X address decoder 40, Y address decoder 41) of the writing device 50, and an electric field is generated between the electrode 35 and the electrode 52 of the optical storage device to generate the ferroelectric substance. Information is written by changing the polarization directions of the layer 53 and the ferroelectric layer 54. At this time, the temperature of the substrate 51 may be increased in order to facilitate the polarization change.

To read information, the ferroelectric layers 53 and 54 are irradiated with light, and the phase change of the reflected light due to the difference in polarization direction is read using the reading device 60. FIG. 24 shows an example of the configuration of the reading device 60, which is not particularly limited, but includes a laser diode 81 which is a light source, a parallel lens 82, and a polarizer 8.
3, half mirror 84, objective lens 85, analyzer 86,
It is composed of a lens system 87, a photodetector integrated circuit 88, a positioning mechanism 89, and the like.

The reading device 60 magnifies the image of the optical storage device by the lens system 87 and forms the magnified image on the photodetector integrated circuit 88 by using the alignment mechanism 89. Even the detector integrated circuit 88 can read an optical storage device having a high degree of integration.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

In the above-mentioned embodiment, the charge storage layer was formed by patterning the conductive layer deposited on the substrate. However, a charge storage layer is formed by implanting impurities into a part of a material having an electro-optical effect by an ion implantation method. You can also do it.

[0068]

The effects obtained by the typical ones of the inventions disclosed in this application will be briefly described as follows.
It is as follows.

According to the optical storage device of the present invention, the presence / absence of charges in the charge storage layer is used as an information unit, so that it is possible to rewrite information at random at high speed.

Further, according to the optical storage device of the present invention, the polarization of the ferroelectric substance is used as an information unit, so that it is possible to rewrite information at random at high speed.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of an optical storage device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II ′ of FIG.

FIG. 3 is an enlarged perspective view showing one memory cell of the optical storage device of the first embodiment.

FIG. 4 is an enlarged perspective view showing one memory cell of the optical storage device of the first embodiment.

FIG. 5 is an enlarged perspective view showing one memory cell of the optical storage device of the first embodiment.

FIG. 6 is a configuration diagram of a reading device used in the optical storage device of the first embodiment.

FIG. 7 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 8 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 9 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 10 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 11 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 12 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 13 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 14 is a cross-sectional view of the substrate showing the method of manufacturing the optical storage device of the first embodiment.

FIG. 15 is a plan view showing a main part of an optical storage device according to a second embodiment of the present invention.

16 is a cross-sectional view taken along line XVI-XVI 'of FIG.

FIG. 17 is a plan view showing a main part of an optical storage device according to a third embodiment of the present invention.

18 is a cross-sectional view taken along the line XVIII-XVIII 'of FIG.

FIG. 19 is a plan view showing a main part of an optical storage device according to a fourth embodiment of the present invention.

20 is a cross-sectional view taken along line XX-XX ′ of FIG.

FIG. 21 is a configuration diagram of a writing device used in the optical storage device of the fourth embodiment.

FIG. 22 is a plan view showing a main part of an optical storage device according to a fifth embodiment of the present invention.

23 is a cross-sectional view taken along the line XXIII-XXIII 'of FIG.

FIG. 24 is a configuration diagram of a reading device used in the optical storage device of the fifth embodiment.

[Explanation of symbols]

1 substrate 2 source region 3 drain region 4 first gate insulating film 5 floating gate (charge storage layer) 5A polycrystalline silicon film 6 second gate insulating film 7 control gate 7A polycrystalline silicon film 8 insulating film 9 insulating film 10 ohmic electrode 10 Reference Signs List 11 wiring 12 wiring 13 wiring 14 surface protective film 15 light reflecting layer 17 n ⁺ type semiconductor region 18A photoresist 18B photoresist 18C photoresist 20 substrate 21 lower electrode 22 upper electrode 23 ferroelectric layer 30 first electrode 31 second electrode 32 Organic Film 33 Substrate 34 Resistor 35 Electrode 40 X Address Decoder 41 Y Address Decoder 42 Power Supply Circuit 43 Power Supply Circuit 50 Writing Device 51 Substrate 52 Electrode 53 Ferroelectric Layer 54 Ferroelectric Layer 55 Light Reflecting Layer 60 Reading Device 61 Alignment Mechanism 71 The diode 72 Parallel lens 73 Polarizer 74 Half mirror 75 Objective lens 77 Analyzer 78 Photodiode 79 Amplifier 81 Laser diode 82 Parallel lens 83 Polarizer 84 Half mirror 85 Objective lens 86 Analyzer 87 Lens system 88 Photodetector integrated circuit 89 Positioning mechanism E Electrical signal L ₁ Laser light L ₂ Reflected light

Claims (11)

[Claims] 1. A memory device in which information is read by light, in which a charge storage layer that is electrically writable is provided in a part of a material having an electro-optical effect, and the presence or absence of charges injected into the charge storage layer. An optical storage device configured to read, as information, a change in polarization due to a fringe electric field corresponding to. 2. The optical storage device according to claim 1, wherein a source region, a drain region, and a charge are formed on a main surface of a substrate that is made of a semiconductor material having an electro-optical effect and has a light reflection layer formed on the back surface thereof. An optical storage device, comprising: a memory cell formed of a floating gate and a control gate that form an accumulation layer; and a circuit for writing data in the charge accumulation layer of the memory cell, which are integrated. 3. The optical storage device according to claim 2, wherein the source region and the drain region are integrally formed by one semiconductor region. 4. The optical storage device according to claim 1, wherein the first electrode forming the charge storage layer and the second electrode connected to a floating state or a fixed potential are arranged to face each other, An optical storage device, characterized in that the first electrode and the second electrode are coated with a material having an electro-optical effect. 5. A memory device in which information is read by light, the first substrate having an electrically writable charge storage layer formed thereon, and the second substrate made of a material having an electro-optical effect. Is arranged so as to face each other, and a change in polarization due to a fringe electric field corresponding to the presence or absence of charges injected into the charge storage layer of the first substrate is read as information. 6. A memory device in which information is read by light, wherein a pair of electrodes and a ferroelectric layer sandwiched between the electrodes are formed on a substrate, and the ferroelectric layer is formed by applying voltages having different polarities. An optical storage device, which is configured to read a change in the direction of spontaneous polarization of a body layer as information. 7. The optical storage device according to claim 6, wherein the ferroelectric layer is irradiated with light, and a phase change of reflected light due to a difference in direction of spontaneous polarization is read as information. Storage device. 8. A writing device for injecting charges into the charge storage layer of the optical memory device according to claim 1, wherein the charge of the memory device is on a substrate different from that of the memory device according to claim 1. A writing device comprising: an electrode for injecting charges into a position corresponding to the storage layer; and a circuit for selecting the electrode. 9. A device for reading information from the optical storage device according to claim 1, wherein the conversion means converts the light from the laser light source into linearly polarized light, and the linearly polarized laser light is converted into light. A reading device, comprising: a detection unit that irradiates a storage device and detects that the polarization state of the reflected light is changed by a fringe electric field corresponding to the presence or absence of an electric charge. 10. A memory device in which information is read by light, in which an electrode connected to a fixed potential is formed on a substrate, and a ferroelectric layer and a light reflection layer are formed on the electrode, and a polarity is provided. The optical storage device is characterized in that the change in the direction of the spontaneous polarization of the ferroelectric layer due to the application of different voltages is read as information. 11. A device for reading information from the optical storage device according to claim 10, wherein a light source for irradiating a ferroelectric layer of the optical storage device with light and a reflected light of the light are enlarged. And a means for detecting the same.