JPH10284130A - Semiconductor substrate mounting type secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress and reduce influence affecting environments without using lithium metal for an electrode material while a lithium secondary battery is miniaturized and lightened, by forming a thin film electrode and solid electrolyte on a semiconductor substrate and using transistor metal oxide and the like for a negative electrode and a positive electrode. SOLUTION: A secondary battery is equipped with a silicon substrate 1 of P type or N type semiconductor material, a negative electrode 2, a solid electrolyte 3, a positive electrode 4, and electrodes for wiring 5a, 5b. The negative electrode 2, solid electrolyte 3, positive electrode 4 and electrodes for wiring 5a, 5b can be formed as thin films. A film thickness of the negative electrode 2 and positive electrode 4 is preferably about 0.2-0.5 μm. Transition metal oxide is preferably used for a positive electrode and a negative electrode. For the solid electrolyte 3, lithium phosphate which works as electrolyte even under a temperature which is not comparatively high is used. For the material of the electrodes for wiring 5a, 5b, metal such as gold, aluminum or the like of good conductivity is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate-mounted secondary battery, and more particularly to a substrate-mounted secondary battery which is suitable for miniaturization and weight reduction and does not use lithium metal for electrodes, preferably mounted on a semiconductor substrate. Type secondary battery.

[0002]

2. Description of the Related Art At present, downsizing of electronic equipment is rapidly progressing. For example, in some fields such as a semiconductor chip, the reduction is dramatically progressing, while in other fields such as a power supply section, the reduction is not progressing slowly. In recent years, in electronic devices, the size of the power supply unit may occupy most of the volume of the device.

However, the practical use of lithium secondary batteries has dramatically improved the performance of power supplies. Lithium rechargeable batteries are theoretically several times more chargeable and dischargeable than nickel-cadmium batteries, etc.
It is realized with a conventional size, and has no adverse effects such as a memory effect.

However, in the prior art, since the positive electrode and the negative electrode are made of metal pieces or metal foils, there is a limit in reducing the size.

[0005] In some cases, lithium metal itself is used for the negative electrode. Since lithium metal is a harmful substance, concern has been raised about environmental destruction.

For example, Japanese Patent Application Laid-Open No. Hei 6-260168 discloses a lithium secondary battery having an excellent high-rate discharge characteristic in which the amount of adhesive is reduced by improving the adhesion performance between a negative electrode and a current collector. For the purpose, the current collector of the negative electrode is a metal foil made of a metal or an alloy that does not form an alloy with lithium, and this metal foil is an electrolytic metal foil having a thickness of 50 μm or less, and forms irregularities on both surfaces of the metal foil. Lithium secondary batteries have been proposed.

[0007]

As described above, in a conventional lithium secondary battery, a metal piece or a metal foil is used for an electrode, and in some cases, lithium metal is used for an electrode.

When a metal piece or foil is used for an electrode, a lithium secondary battery cannot be constructed unless it has a certain thickness, so that the battery cannot be reduced in size.
There is a problem that.

[0009] Further, since a large amount of lithium metal, which is a harmful substance, must be used, there is a possibility of adversely affecting the environment or harming the human body.

[0010] Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a lithium secondary battery capable of reducing the size and weight of the lithium secondary battery. Another object of the present invention is to provide a lithium secondary battery that does not use lithium metal as an electrode material and suppresses and reduces the effect on the environment.

[0011]

In order to achieve the above object, a semiconductor substrate-mounted secondary battery according to the present invention is characterized in that a thinned electrode and a solid electrolyte are provided on a semiconductor substrate. .

The present invention is characterized in that the negative electrode and the positive electrode formed on the semiconductor substrate are preferably made of a transition metal oxide or the like, and constitute a lithium secondary battery without using a lithium metal piece. And

Further, the present invention is characterized in that a first thin film electrode, a solid electrolyte, and a second thin film electrode are laminated on a substrate in this order.

Further, the present invention is characterized in that a first electrode wiring, a first thin film electrode, a solid electrolyte, a second thin film electrode, and a second electrode wiring are laminated in this order on a substrate.

A substrate-mounted secondary battery according to the present invention includes first and second electrode wirings on an insulating film provided on a substrate,
First and second thin-film electrodes are disposed at substantially the same height on the first and second electrode wirings, respectively, and a solid electrolyte is provided so as to cover the first and second thin-film electrodes and a gap therebetween. It is characterized by the following.

Further, the present invention is characterized in that the substrate comprises a semiconductor substrate.

Further, the present invention is characterized in that the first thin-film electrode is configured to contain lithium ions in advance.

Further, the present invention is characterized in that the first thin-film electrode and the second thin-film electrode are made of a transition metal oxide.

[Summary of the Invention] In the present invention, an electrode and an electrolyte are thinned by a sputtering method or the like, and the constituents are made as thin as possible to reduce the size and weight of the lithium secondary battery. In addition, by not using lithium metal as an electrode material, adverse effects on the environment are suppressed to the utmost, thereby realizing environmental conservation. According to the present invention, a significant reduction in size and weight is achieved as compared with conventional lithium secondary batteries. More specifically, a positive electrode, a negative electrode,
By thinning the electrolyte by a sputtering method or the like, a battery having a thickness on the order of microns can be produced. In addition, the amount of lithium, which is a harmful substance, can be reduced to the utmost limit, and a battery having a minimal effect on the human body and an environment when destroyed can be realized. Furthermore, a battery can be formed on a semiconductor substrate, and a power supply unit provided outside the chip is not required, thereby achieving a particularly small and small electronic device.

[0020]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view showing the configuration of the first embodiment of the present invention. FIG. 2 is a sectional view taken along line XX of FIG. Referring to FIGS. 1 and 2, this embodiment includes a silicon substrate 1, a negative electrode (negative electrode) 2, a solid electrolyte 3, a positive electrode (positive electrode) 4, and a wiring electrode 5. .

The semiconductor substrate 1 may be a P-type or N-type substrate, and does not particularly depend on the impurity concentration or plane orientation in the substrate. Further, as the substrate, a member other than the semiconductor substrate may be used as long as a current flows and does not alloy with lithium.

The negative electrode 2 can be made into a thin film, and if it is a member used as an electrode material of a lithium secondary battery,
In this embodiment, the members are not particularly limited. This thinning of the electrode material is realized by forming a film by a sputtering method, an electron beam evaporation method, a heating evaporation method, or the like.

As a method of injecting lithium into the negative electrode 2 in advance, there are an ion implantation method, a method of performing discharge only once using a liquid electrolyte and a lithium metal electrode, and a method of using an electrode material containing lithium from the beginning. and so on.

In the present embodiment, the solid electrolyte 3 is not particularly limited as long as it can be formed into a thin film and can move lithium freely. For thinning the solid electrolyte 3, a sputtering method, an electron beam evaporation method, a heating evaporation method, a spin coating method, or the like can be used.

In the present embodiment, the material of the positive electrode 4 is not particularly limited as long as it can be made thin and is used as an electrode material of a lithium secondary battery.
The thinning of the electrode material is realized by forming a film by a sputtering method, an electron beam evaporation method, a heating evaporation method, or the like.

The wiring electrodes 5a and 5b can be made thin, have low resistance, and can be in ohmic contact with the material constituting the silicon substrate and the positive electrode 4. For the thinning of these electrode materials, a sputtering method, an electron beam evaporation method, a heating evaporation method, or the like can be applied.

If the film thickness of the negative electrode 2 and the positive electrode 4 is too small, the charge / discharge capacity is reduced, and if the film thickness is too large, the size is preferably 0.2 to 0.2.
The thickness is about 0.5 μm.

FIG. 3 is a sectional view showing the configuration of the second embodiment of the present invention.

Referring to FIG. 3, this embodiment is different from the first embodiment in that wiring electrode 5b is connected to negative electrode 2a.
And the silicon substrate 1. In this embodiment, since there is no need for a current to flow through the silicon substrate 1, the substrate 1 is not limited to a semiconductor material, but may be an insulator or the like.

FIG. 4 is a sectional view showing the structure of the third embodiment of the present invention.

Referring to FIG. 4, in this embodiment, an insulating film 6 is formed on a silicon substrate 1, wiring electrodes 5a and 5b are formed thereon, and a positive electrode 4 and a negative electrode 2 are connected to each other. They are arranged side by side on 5a and 5b. That is, the positive electrode 4 and the negative electrode 2 are not stacked as in the above embodiment. With such an arrangement, the thickness of the battery itself can be further reduced. Further, in the case of this embodiment, the substrate can be changed to an insulator.

[0033]

Next, the operation of the embodiment of the present invention will be described with reference to FIGS.

At the time of discharging, the lithium inside the negative electrode 2 is:
Separated into lithium ions and electrons, the lithium ions are emitted to the solid electrolyte 3 and the electrons are emitted to an external circuit.

The released lithium ions pass through the solid electrolyte 3 and are injected into the positive electrode 4. The emitted electrons are injected into the positive electrode 4 through an external circuit. As a result, lithium ions and electrons are injected into the positive electrode 4, and lithium is accumulated inside the positive electrode 4. When the potentials of the negative electrode 2 and the positive electrode 4 become the same, the discharge stops.

At the time of charging, a potential is applied from an external power supply. At this time, a negative (−) potential is applied to the positive electrode, and a positive (+) potential is applied to the negative electrode. Then, lithium moves in a manner opposite to that at the time of discharging. The lithium contained in the positive electrode 4 is separated into lithium ions and electrons, and the lithium ions pass through the solid electrolyte 3 and are injected into the negative electrode 2. The electrons pass through an external power supply and are injected into the negative electrode 2. Lithium is accumulated inside.

When no more lithium can be stored in the negative electrode 2 or all lithium ions are released from the positive electrode 4, the charging is completed.

As an example of a battery performing such an operation, the following lithium secondary battery can be considered.

Preferably, a transition metal oxide is used as a positive electrode or negative electrode material. For example, niobium oxide, cobalt oxide, vanadium oxide, and the like can be given. Any of the materials can be used as an electrode material of a lithium secondary battery. Here, vanadium pentoxide formed by a sputtering method is used. Vanadium pentoxide V ₂ O ₅ has a relatively high initial discharge potential of about 4 V and excellent discharge time among transition metal oxides. The vanadium pentoxide was used for the negative electrode 2 and the positive electrode 4
To be used as an electrode material.

As the solid electrolyte 3, lithium phosphate which acts as an electrolyte even at a relatively low temperature is used.

As the material of the wiring electrodes 5a and 5b,
It is appropriate to use a metal having good conductivity, such as gold or aluminum. For example, aluminum is used here.

As a specific production method, first, a thin film having a thickness of, for example, 200 nm is formed on the silicon substrate 1 as the electrode 5b by sputtering aluminum.

Next, vanadium pentoxide was formed as a negative electrode 2 on a silicon substrate by sputtering to a thickness of, for example, 300 nm.
A thin film of nm is formed.

Thereafter, lithium is injected into the negative electrode 2 in advance. Preferable examples of the method include lithium ion implantation, thinning of vanadium oxide containing lithium as a constituent substance, sputtering with lithium ions, simultaneous film formation of lithium and vanadium pentoxide, and insertion of lithium by a charge / discharge action.

In this embodiment, a method of inserting lithium by charge / discharge action is used. In this method, a general lithium secondary battery is formed using a liquid solid electrolyte and a lithium metal piece, and once discharged, lithium is inserted into vanadium pentoxide.

Then, a thin film having a thickness of, for example, 300 nm is formed on the negative electrode 2 by sputtering lithium phosphate as the solid electrolyte 3, and further, vanadium pentoxide is formed on the solid electrolyte 3 as the positive electrode 4. A thin film having a thickness of, for example, 300 nm is formed by a sputtering method.

Finally, a wiring electrode 5 a is formed on the positive electrode 4.
A thin film having a thickness of 200 nm is formed by a sputtering method.

In this embodiment, the thin films of different types are formed while being stacked as described above. At this time, in order to prevent a short circuit, the size of the thin film on the upper side is reduced.

Thus, the thickness on the silicon substrate 1 is about 12
A minute lithium secondary battery of 00 nm (1.2 μm) can be obtained.

[0050]

As described above, according to the present invention, the following effects can be obtained.

(1) A first effect of the present invention is that a power supply can be mounted on a semiconductor chip.
For this reason, the power supply conventionally provided outside the semiconductor chip can be removed, thereby enabling a significant downsizing.

The reason is that in the present invention, a battery is formed on a silicon substrate.

(2) The second effect of the present invention is that handling is easy.

The reason is that in the present invention, lithium metal is not used as a constituent material of the electrode.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view when FIG. 1 is cut along a line XX.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

[Description of Signs] 1 P-type or N-type silicon substrate 2 Negative electrode 3 Solid electrolyte 4 Positive electrode 5a Wiring electrode 5b Wiring electrode 6 Insulator

Claims (12)

[Claims] 1. A secondary battery mounted on a semiconductor substrate, comprising a thinned electrode and a solid electrolyte on a semiconductor substrate. 2. The method according to claim 1, wherein the negative electrode and the positive electrode formed on the semiconductor substrate are preferably made of a transition metal oxide or the like, and constitute a lithium secondary battery without using a lithium metal piece. Secondary battery mounted on a semiconductor substrate. 3. A substrate-mounted secondary battery comprising a first thin-film electrode, a solid electrolyte, and a second thin-film electrode laminated in this order on a substrate. 4. A first electrode wiring, a first thin film electrode,
A substrate-mounted secondary battery comprising a solid electrolyte, a second thin-film electrode, and a second electrode wiring laminated in this order. 5. A semiconductor device comprising: an insulating film provided on a substrate; and first and second electrode wirings provided on the insulating film, and first and second thin-film electrodes on the first and second electrode wirings, respectively, having substantially the same height. Arranging the first
A substrate-mounted secondary battery comprising a thin-film electrode, a second thin-film electrode, and a solid electrolyte so as to cover a gap therebetween. 6. The substrate mounted secondary battery according to claim 3, wherein said substrate is made of a semiconductor substrate. 7. The substrate-mounted secondary battery according to claim 3, wherein said first thin-film electrode is configured to contain lithium ions in advance. 8. The method according to claim 3, wherein said first thin film electrode and said second thin film electrode are made of a transition metal oxide.
The substrate-mounted secondary battery according to any one of the above. 9. The substrate mounted type secondary battery according to claim 4, wherein said substrate is made of a semiconductor or an insulating member. 10. A semiconductor device comprising: the first electrode wiring on the substrate;
A second electrode wiring on the second thin-film electrode;
The substrate-mounted secondary battery according to claim 3, wherein an electromotive force is obtained between the second electrode wirings. 11. A thin film electrode, an electrode wiring and the like formed by laminating on the substrate, wherein the area of the planar shape is gradually reduced in the upper layer than in the lower layer. The substrate-mounted secondary battery according to any one of claims 1 to 10. 12. A thin film electrode, an electrode wiring and the like which are sequentially laminated on the substrate have a predetermined film thickness, preferably approximately 200 to 200 nm.
The substrate-mounted secondary battery according to claim 3, wherein the secondary battery is formed to a thickness of 500 nm.