JP2003229538A - Non-volatile memory and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase storage capacity in a non-volatile memory used for all sorts of electric equipment. <P>SOLUTION: A memory substance is two-dimensionally aligned on a polymer film having a thickness of approximately several μm. The memory material is connected to electrodes 13 and 14 via a resistance electrode 12, and is made of a phase change material 11. The polymer film where a memory cell is formed is reeled up in a roll shape, and is multilayered for cutting. The memory cell is laminated, for example, from a first cell formation layer 15 to a third cell formation layer 19, and is aligned three-dimensionally, thus obtaining a large- capacity non-volatile memory. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-volatile memory that does not require a power source to hold a memory.

[0002]

2. Description of the Related Art Conventionally, as a non-volatile memory, for example, one disclosed in a published patent publication "Japanese Patent Publication No. 2001-502848" is known. A conventional technique will be described below with reference to the drawings.

FIG. 8 shows a cross-sectional structure of a conventional nonvolatile memory, which includes a Si substrate 81, a phase change material 82, an electrode A8.
3, an electrode B84, and a resistance electrode 85. The phase change material 82 is a substance that reversibly undergoes a phase transition between an amorphous state and a crystalline state, and is characterized by high resistance in the amorphous state and low resistance in the crystalline state. Electrode A83, Electrode B
84, the phase change material 82 at a certain address arranged on the surface of the Si substrate 81 and the resistance electrode 85 are energized, and the crystallinity of the phase change material 82 is controlled by the action of the generated Joule heat. The resistance value of the material 82 is changed. Writing is performed by changing the phase change material 82 from an amorphous state to a crystalline state, and the resistance value changes from high resistance to low resistance accordingly. On the contrary, erasing is performed by changing the crystalline state to the amorphous state, and the resistance value changes from low resistance to high resistance. The reading is performed by detecting the resistance value of the phase change material 82 at the same electrode.

[0004]

However, it is difficult to increase the storage capacity of the conventional nonvolatile memory. The present invention aims to increase the storage capacity.

[0005]

In order to solve this problem, according to the present invention, a polymer film having a thickness of several μm, in which a memory material having electrodes is two-dimensionally arranged, is wound into a roll. After that, the memory cells are cut into individual memories and the memory cells are arranged three-dimensionally.

As a result, a large capacity nonvolatile memory can be obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is a non-volatile memory in which memory cells having electrodes connected to a memory substance are three-dimensionally arranged on a substrate made of a polymer. By using the polymer, the cost is lower than that of Si, and the memory cells are arranged three-dimensionally, so that the recording capacity is increased as compared with the case where they are arranged two-dimensionally.

According to a second aspect of the present invention, there is provided a non-volatile memory in which a film made of a polymer in which memory cells having electrodes connected to a memory substance are two-dimensionally arranged is laminated, and by using a polymer substrate, Since the layers are laminated, even if they are about several microns thick, they do not crack like Si and are easy to handle.

The invention according to claim 3 is the nonvolatile memory according to claim 1-2, wherein the polymer is any one of polycarbonate, polyethylene terephthalate, polypropylene, polyimide, polyamide, and polybenzoxazole. This has the effect that the device structure is stable with a relatively small volume change with respect to the temperature change.

The invention according to claim 4 is the nonvolatile memory according to claim 1 in which the memory substance is a phase change material, and the heat conduction is poor because the substrate is a polymer.
It has an effect that the phase change material can be heated with less electric power.

According to a fifth aspect of the present invention, the projections having sharp and sharp tips are pressed against the polymer film to form a region in which the polymer film is easily etched. The method for manufacturing a non-volatile memory of No. 1 has an effect of forming via holes for wiring in the substrate.

According to a sixth aspect of the present invention, a structure in which conductive projections having sharp tips are arranged on a plane is brought close to the surface of the polymer film arranged on the metal plate, and the polymer film is sandwiched. The region which is easy to be etched is formed in the polymer film by applying a voltage between the metal plate and the conductive protrusion to generate ions or discharge from the tip of the conductive protrusion. This is a method for manufacturing a non-volatile memory, and has the function of forming via holes for wiring in the substrate.

According to a seventh aspect of the present invention, a polymer film in which a memory substance having electrodes is two-dimensionally arranged is wound into a roll, laminated and cut, and divided into individual memories. This is the method for manufacturing the nonvolatile memory described above, and has an effect of easily increasing the number of stacked layers.

The invention according to claim 8 is characterized in that a conductive rod-shaped substance having a sharp tip is mechanically driven into the substrate to connect the layers inside the substrate with each other. However, even if a conductive rod-shaped substance with a sharp tip is mechanically driven, the polymer is
It does not crush like the above, and has a function of inserting a conductive rod-shaped substance between layers to obtain an electrical contact between the layers.

The invention according to claim 9 is characterized in that a conductive rod-shaped substance having a sharp tip is mechanically driven into a substrate to take out an electrode of a layer inside the substrate to the outside.
The method for manufacturing a nonvolatile memory according to the description, the polymer does not crush like Si even when mechanically hitting a conductive rod-shaped substance having a sharp tip, and the conductive rod-shaped substance is inserted into the substrate, It has a function of taking out the electrode to the outside.

According to a tenth aspect of the present invention, the flexible display is incorporated with a battery.
The non-volatile memory described in -4 is used, and the characters and images displayed on the display surface are dynamically changed by reading the data recorded in the non-volatile memory with battery power while maintaining the bending characteristics of the flexible display. It has the action of causing.

An eleventh aspect of the present invention is the nonvolatile memory according to the first aspect, which is incorporated with an antenna for supplying electric power for reading to a flexible display, and uses radio waves such as microwaves as an antenna. Power is supplied to the non-volatile memory in a contactless manner.

Next, specific examples of the present invention will be described.

(Embodiment 1) This embodiment will be described with reference to FIG.

FIG. 1 is a sectional view showing a nonvolatile memory according to an embodiment of the present invention.

In FIG. 1, a phase-change material 11 serves as a memory substance for recording, retaining and erasing data, and its structure is composed of a substance that undergoes a phase transition between a polycrystalline state and an amorphous state. . It is well known that an amorphous semiconductor containing chalcogenide undergoes this kind of phase transition, and the Ge—Sb—Te system was used in this example.

The resistance electrode 12 generates heat energy when energized to control the phase change of the phase change material 11, and is made of metal. C with low resistivity
It is preferable to use a metal having a relatively higher specific resistance than u or the like, and Rh was used in this embodiment. In addition, other P
Pure metals such as t, Ni, Co, Ti, and W, alloys such as TiW, and intermetallic compounds such as TiAlN may be used. Due to Joule heat generation of the resistance electrode 12 and the phase change material 11 itself, a phase transition between an amorphous state (high resistance) and a polycrystalline state (low resistance) in the phase change material is arbitrarily performed.

The electrodes 13 and 14 have a function of electrically connecting to the resistance electrode 12 and the phase change material 11 and wiring.
It is made of low-resistance metal.

First cell formation layer 15 and second cell formation layer 1
7. Each of the third and third cell forming layers 19 has a function of arranging memory cells two-dimensionally, and is made of a polymer film.

The first protective layer 16 serves to electrically insulate the first cell forming layer 15 and the second cell forming layer and to bond the layers, and is made of an insulating polymer material. Second
The protective layer 18 includes the second cell formation layer 17 and the third cell formation layer 19
It performs the function of electrical insulation and adhesion between layers, and is also composed of an insulating polymer material. Third protective layer 1
10 has a function of protecting the surface of the third cell forming layer 19, and is made of an insulating polymer material.

FIG. 2 is an explanatory view of the method for manufacturing the nonvolatile memory according to the present embodiment.

The prepared polymer film 21 has a very thin thickness of about several microns. Polycarbonate was used as the material because the volume change is relatively small with respect to temperature change and the device structure is stable. Other materials may be polyethylene terephthalate, polypropylene, polyimide, polyamide, polybenzoxazole and the like. In particular, a polymer material such as polyimide is preferable because it can withstand a high temperature up to 500 ° C instantaneously. When Si has such a thickness, it is easily cracked and difficult to handle. However, since the substrate is made of polymer, it does not crack even at such a thin thickness and is easy to handle.

First, as shown in FIG. 2A, a step of forming defects 24 on the polymer film 21 was performed. First, the polymer film 21 was placed on a smooth plate 22. On top of that, a projection plate 23 in which very sharp needle-like structures having a projection tip diameter of about 50 nm were arranged was pressed. As a result, defects 24 were generated at the protrusion contact portions of the polymer film 21 due to the local pressure application by the protrusions to the polymer film 21. A cross-sectional view of the polymer film 21 having the defect 24 is shown in FIG.

When this polymer film 21 was dipped in a KOH solution, defects 24 were selectively etched, and holes 25 having a diameter of about 200 nm were opened. FIG. 2C is a cross-sectional view of the polymer film 21 having holes 25 formed by selectively etching defects.

Rh was filled in the hole 25 by an electroplating method, and the phase change material 11 and the electrodes 13 and 14 were vapor-deposited to form a memory cell. FIG. 2D shows a cross-sectional view of the completed polymer film 21 having a memory cell formed therein.

The polymer film with holes as shown in FIG. 2 (c) could be prepared by the following method. First, the melted organic solvent of the polymer film 21 was applied to the smooth plate 22, and the projection plate 23 was pressed against it. afterwards,
When the smooth plate 22 was heated to evaporate the organic solvent, a polymer film having aligned depressions was obtained. Immersion of this polymer film in an etching solution resulted in the formation of holes of similar size.

Transistors that electrically specify memory cells were also formed on the polymer film. FIG. 3 shows a wiring diagram of a memory cell having a transistor. Phase change material 3
The third electrode 32 can be turned on / off by the transistor 31, and the memory cell at the specified address can be accessed. However, for simplification of the drawing, this transistor is not shown in FIGS. 1, 2, and 6. The resistance electrode 12 of FIG. 1 is not shown in FIG. 3 for the same reason.

After forming a memory cell on one polymer film, the polymer film was laminated as follows. FIG. 4 is an explanatory view of the polymer film laminating method according to the present embodiment. On one surface (upper surface) of a polymer film having a memory cell, a polymer film having a thickness of about several microns and having an insulating property and a slightly low melting point is stacked as a protective film. Polymer film 41 with this protective film
Fig. 4 shows the appearance in which the
It shows in (a). Cutting machine 43 with a blade like a cutter
This roll is cut into device sizes using.
FIG. 4B shows a process of dividing the memory into individual memories. An external view of the divided device obtained as a result is shown in FIG. The heat treatment softens the protective film, and the laminated polymer films are bonded and integrated. Note that an adhesive having fluidity at room temperature may be used for adhesion between layers, and by drying the adhesive at room temperature, it is possible to integrate the laminated polymer films without applying heat treatment. .

The wiring method between polymer film layers is shown in FIG.
It will be described with reference to the cross-sectional view of the three-dimensionally wired nonvolatile memory according to the embodiment of the present invention shown in FIG. FIG. 5A is a cross-sectional view of a non-volatile memory with inter-layer wiring, and shows a nail electrode 5 with a sharp tip.
4 from the surface of the polymer, and the first layer electrode 51 and the second layer
This is an example in which the layer electrode 52 and the third layer electrode 53 are connected. Further, FIG. 5B is a cross-sectional view of the nonvolatile memory in which the internal wiring is drawn to the outside, and is an example in which the nail electrode 514 is driven from the polymer surface and the second layer electrode 512 is drawn from the inside of the polymer to the outside. At this time, the length of the nail electrode 514 is adjusted so as not to reach the first layer electrode 511. Also,
The third layer electrode 513 is formed in a structure in which the nail electrode 514 does not contact. In this way, by using the polymer substrate, even when mechanically driving a pointed structure,
The polymer has a function of making electrical contact between layers without being crushed like Si.

As described above, when the non-volatile memory according to the present embodiment is used, the polymer film forming the memory cells has a multi-layer structure, whereby the memory cells are three-dimensionally arranged, and as a result, the recording capacity is increased. To be Further, since the polymer is used as the substrate material, it can be manufactured at a lower cost than the conventional substrate made of Si, and at the same time, the heat conduction of the substrate is worse than that of Si or SiO2, so that the phase change material can be heated. It also has the advantage of requiring less power.

In this embodiment, the number of laminated layers is three, but other number of laminated layers can be similarly applied.

In the above description, an example in which the memory substance is composed of an inorganic phase change material has been described, but a phase change material using an organic substance such as pentacene whose resistance value greatly changes between amorphous and crystalline may be used. .

Example 2 FIG. 2A shown in Example 1
A manufacturing method different from the above method was also tried.

FIG. 6 shows a process of forming defects in a polymer film according to an embodiment of the present invention. After sandwiching the polymer film 61 between the metal plate 62 and the conductive protrusion plate 63, a potential is applied to the metal plate 62 and the conductive protrusion plate 63, whereby defects are generated in the polymer film 61. Figure 6
(A) is an explanatory view of the case where the conductive protrusion plate 63 is brought into contact with the polymer film 61. When a high voltage of about several hundreds of volts was applied momentarily to the negative electrode on the protrusion side, discharge was generated between the protrusion and the metal plate, and defects were generated in the polymer film. By adjusting the applied voltage and the applied time, the size of the generated defect was changed. As compared with Example 1, the diameter of the hole formed by etching can be reduced to 100 nm or less, and at the same time, the projection tip portion is less deteriorated due to the defect generation, and the projection plate can be used many times.

FIG. 6B is an explanatory view when the polymer film and the conductive projection plate are separated. When the protrusion side is made the positive electrode and a high voltage of about 10 kV is momentarily applied,
Atoms were desorbed from the projection tip by electric field, ionized, and high-energy particles accelerated by an applied voltage collided with the polymer film, causing defects in the polymer film. When the rare gas atom was added, the rare gas atom was rather ionized at the tip of the protrusion, creating a defect in the polymer film. In particular, when Xe, which is a heavy atom, is used, defects are likely to occur. As compared with the method of FIG. 6A, it has a feature that there is less variation in the diameter of holes formed by selectively etching defects.

Further, the precursor of the polymer film is applied on the metal plate 62 and a voltage is applied as shown in FIG. 6 (a) or 6 (b), and then the metal plate 62 is heated to generate the polymer on the spot. Defects occur in the polymer film even when it is synthesized into a film. The polymer film was perforated by etching the polymer film with a KOH solution.

As described above, if the step of forming defects in the polymer film according to the present invention is used, 1) the diameter of the hole formed by etching can be made small, 2) the deterioration of the protruding plate is small and its life is long, 3). The effect of reducing the variation in the diameter of the holes was obtained.

The conductive material forming the protrusions may be Si doped with a large amount of impurities, or Si coated with a metal, or may be carbon nanotubes or the like.

(Embodiment 3) A usage example of the nonvolatile memory manufactured in Embodiment 1-2 will be described.

FIG. 7 is an explanatory diagram of a nonvolatile memory incorporated in a flexible display according to an embodiment of the present invention. FIG. 7A is an external view of a display surface of a flexible display having a non-volatile memory. Characters 72 and images 73 are displayed on the flexible display 71 and can be bent in the display state. However,
The non-volatile memory is not visible in this external view because it is built in on the back side of the display surface or inside the display. A memory is required to dynamically change displayed characters and images, and when a conventional memory is attached to a flexible display, the display becomes inflexible. By setting the total thickness of the polymer, which is the substrate of the non-volatile memory according to the present embodiment, to such a degree that the polymer can be easily bent, the non-volatile memory can be mounted on the flexible display without impairing the bending characteristics, and the above problems are solved. In the present embodiment, the thickness of the polymer film on which the memory cells are two-dimensionally arranged is set to 5 μm, 5 μm is placed on it as a protective film, and these are laminated in three layers.
The total thickness was 30 μm. Characters and images to be displayed are changed by loading data from the mounted non-volatile memory and changing the characters and images to be displayed by writing data externally to the non-volatile memory. Of course, when the amount of data to be handled is small, it is sufficient that the memory cells of the non-volatile memory are two-dimensionally arrayed, and it is not necessary to increase the storage capacity by three-dimensionally arraying.

FIG. 7B shows a schematic view of the nonvolatile memory and the battery arranged on the back side of the display surface. Non-volatile memory 7
A battery 75 for reading the data written in 4 and displaying it on the display surface is mounted. We also use a thin and flexible battery to prevent the display surface of the display from bending. The battery may be a type that uses an electrochemical reaction or a type that uses photoexcitation.

A method of supplying electric power by a method different from that of FIG. 7B is shown in a schematic view of a nonvolatile memory and an antenna arranged on the back side of the display surface of FIG. 7C. Electric power was supplied in a non-contact manner by receiving radio waves with the antenna 76.
In this example, a microwave of 2.45 GHz was used. Since the antenna was formed by using the strip line on the flexible substrate, it did not interfere with the bending function. Even if the flexible display is moved to a place where radio waves do not reach, or the supply of radio waves is stopped, the data in the nonvolatile memory is retained, and when the supply of radio waves is restarted, characters and images appear on the display and Changed to.

In the present embodiment, the flexible display has no display section on the back side, and the nonvolatile memory, the battery, and the antenna are mounted on the back side of the flexible display. However, the nonvolatile memory, the battery, and the antenna are embedded inside the flexible display. But it doesn't matter.

As described above, according to the present invention, the characters and images displayed on the display surface can be dynamically changed by using the data recorded in the non-volatile memory while maintaining the bending characteristic of the flexible display. was gotten.

[0050]

As described above, according to the present invention, the advantageous effect that the memory cells are three-dimensionally arranged and the recording capacity is increased can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a nonvolatile memory according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method for manufacturing a nonvolatile memory according to an embodiment of the present invention.

FIG. 3 is a wiring diagram of a memory cell having a transistor.

FIG. 4 is an explanatory view of a polymer film laminating method according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a three-dimensionally wired nonvolatile memory according to an embodiment of the present invention.

FIG. 6 is an explanatory view of a process of forming a defect in a polymer film according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of a nonvolatile memory incorporated in a flexible display according to an embodiment of the present invention.

FIG. 8 is a sectional view of a conventional nonvolatile memory.

[Explanation of symbols]

11 Phase change material 12 Resistance electrode 13 electrodes 14 electrodes 15 First cell formation layer 16 First protective layer 17 Second cell formation layer 18 Second protective layer 19 Third cell forming layer 110 Third protective layer 21 Polymer film 22 Smooth plate 23 Projection plate 24 defects 25 holes 31 transistor 32 electrodes 33 Phase change material 41 polymer film 42 cylinder 43 cutting device 51 First Layer Electrode 52 Second layer electrode 53 Third layer electrode 54 nail electrode 511 First layer electrode 512 Second layer electrode 513 Third layer electrode 514 nail electrode 61 Polymer film 62 metal plate 63 Conductive protrusion plate 71 Flexible display 72 characters 73 images 74 Non-volatile memory 75 battery 76 antenna 81 Si substrate 82 Phase change material 83 Electrode A 84 Electrode B 85 Resistance electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Otsuka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5F083 FZ07

Claims (11)

[Claims] 1. A non-volatile memory in which memory cells having electrodes connected to a memory material are three-dimensionally arranged on a substrate made of a polymer. 2. A non-volatile memory in which a film made of a polymer in which memory cells having electrodes connected to a memory material are two-dimensionally arranged is laminated. 3. The polymer is polycarbonate, polyethylene terephthalate, polypropylene, polyimide,
The nonvolatile memory according to claim 1 or 2, which is one of polyamide and polybenzoxazole. 4. The memory material is a phase change material.
4. The nonvolatile memory according to any one of 3 to 3. 5. The method for manufacturing a non-volatile memory according to claim 1, wherein the polymer film is formed by pressing a structure in which projections having sharp tips are arranged on a plane. A method of manufacturing a non-volatile memory, comprising the step of forming a region which is easily etched. 6. The method for manufacturing a non-volatile memory according to claim 1, wherein a structure in which conductive projections having sharp tips are arranged on a plane is provided on a metal plate. The polymer film is placed on the polymer film by bringing it closer to the surface of the polymer film placed and applying a voltage between the metal plate and the conductive protrusion across the polymer film to cause ion emission or discharge from the tip of the conductive protrusion. A method of manufacturing a non-volatile memory, comprising the step of forming a region that is easily etched. 7. The method for manufacturing a non-volatile memory according to claim 1, wherein a polymer film in which a memory substance having an electrode is two-dimensionally arranged is rolled into a laminated state. A method for manufacturing a non-volatile memory, comprising a step of cutting and dividing into individual memories. 8. The method for manufacturing a non-volatile memory according to claim 1, wherein a conductive rod-shaped substance having a sharp tip is mechanically driven into the substrate to connect the layers inside the substrate. A method for manufacturing a non-volatile memory, comprising the steps of: 9. The method for manufacturing a non-volatile memory according to claim 1, wherein a conductive rod-shaped substance having a sharp tip is mechanically driven into the substrate, and electrodes of layers inside the substrate are externally exposed. A method for manufacturing a non-volatile memory, comprising the step of taking out the non-volatile memory. 10. A flexible display comprising the non-volatile memory according to claim 1 and a battery. 11. The flexible display according to claim 10, further comprising an antenna for supplying electric power for reading.