JPS59225417A - Semiconductor memory - Google Patents

Abstract

PURPOSE:To guarantee the permanent operation of a semiconductor element by connecting a solar battery via a diode and a thin film secondary battery respectively in parallel with the semiconductor element having a volatile memory. CONSTITUTION:A totally solid-state thin film secondary battery is formed by using a TiS2 thin film as a positive electrode, an Li4SiO4-Li3PO4 group thin film as an electrolyte film and an Li metal as a negative electrode. The secondary battery and the solar battery are mounted together with a nonvolatile memory such as microcomputer and memory by the technology such as the tape carrier system so as to be incorporated in the form of a cash card. In the circuit constitution, the memory cell is connected in parallel with the secondary battery and the solar battery as shown in Fig. When a light is incoming, the solar battery is activated to charge the secondary battery and feed power to the memory cell or the like. When the light is interrupted conversely, the power is supplied from the secondary battery to the memory cell so as to form a thin nonvolatile memory device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] □ The present invention relates to card-shaped semiconductor memories such as data collection terminals and memory terminals.

[Background of the invention]

In recent years, due to advances in CMO8 circuit technology, the current consumption of semiconductor elements has been significantly reduced. Therefore, it has become possible to fully operate semiconductor circuits using crystalline silicon solar cells, amorphous silicon/solar cells, and ultra-small batteries (Japanese Patent Laid-Open No. 57-109183). for that,
To date, many cash card-sized devices have been developed that integrate a microcomputer, memory, and primary battery, and devices that integrate a solar cell, liquid crystal display, and microcomputer. However, the fundamental drawback of these devices is that they do not have a power source that can guarantee operation under all conditions. In other words, the above-mentioned Japanese Patent Application Laid-open No. 1983
-109183, which uses a primary battery, will no longer operate if the semiconductor element consumes an amount of charge equivalent to the capacity of the battery. Furthermore, devices using solar cells have the disadvantage that the device does not operate when light is cut off, and the contents of the semiconductor memory are also erased.

[Purpose of the invention]

An object of the present invention is to provide a card-shaped semiconductor memory that eliminates the drawbacks of these conventional techniques and ensures permanent operation of the device. A semiconductor element having a microcomputer, a microcomputer/built-in cash card, a random access memory, etc., a solar cell that drives it, and a thin film secondary battery are connected in parallel to the solar cell via a diode. Features.

The secondary battery is preferably an all-solid thin film secondary battery, particularly an all-solid thin film secondary battery.

The electric capacity per battery volume is large, making it difficult to charge.
This is because it can be used for more than 10 years.

The positive electrode material, negative electrode material, and solid electrolyte may be made into thin films using foil or solidified powder, but in order to make the entire battery thinner, so-called thin film technology, such as CVD,
As the negative electrode material, which is preferably manufactured by vapor deposition, sputtering, etc., Li or 1d Li alloy is used. The thickness of the negative electrode is difficult to determine because it is related to the desired capacity of the battery, but it is usually preferably 5 to 250 μm, and 10 to 100 am, in order to take advantage of the characteristics of an all-solid thin film secondary battery. It is highly preferable that

As a positive electrode material, use a material that accepts and releases lithium ions.
．． , V, 0,3. Vie, fxt is preferable◇
The thickness of the positive electrode is preferably about twice the thickness of the negative electrode.

As the solid electrolyte, Li2O/SiO□/P2O, a ternary compound described in JP-A No. 57-60669,
Or Li, O-8i0.・ZrO, ternary compounds, etc. are included. The former compound can form (1-x)Li4Sin4-xLi3PONb, both by sputtering, at certain compositions. Furthermore, it has excellent ionic conductivity at room temperature. The thickness of the solid electrolyte is preferably 2 to 50 am, and 3 to 20 am.
More preferably, it is m.

According to the second aspect of the present invention, the above device may further include a thin display.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to examples.〇 As a secondary battery, a Ti82 thin film was deposited as a positive electrode on a silicon substrate or a heat-resistant resin by the CVD method, and Li4 was used as an electrolytic replacement.
Sin4-Li, PO4-based thin film published in JP11F157-6
According to the Subaru method described in No. 0669, Li metal was formed as a negative electrode by vapor deposition. Furthermore, in order to inactivate the Li surface, Ni metal was made by vapor deposition and 8t3N4 was made by sputtering, and the surface was coated except for the rjBt current collector part, and an all-solid-state thin film secondary battery was fabricated. And so. The reaction area of this battery is 4
cm", and has a negative capacity of 15.mAh.Furthermore, a solar cell is formed by an a-8i pin junction on the same substrate, and connected so that the output voltage is 2 to 3V.

These are mounted together with a disk, microcomputer, memory, etc. using a tape carrier method, etc., and are integrated into a carrier or cylindrical card. The basic circuit configuration at this time is as shown in Figure 1. When there is light, the solar cell operates, charges the secondary battery, and supplies energy to the memory cells, peripheral cells, microcontrollers, etc. . Also, when the light is s#T,
Although the circuit is configured to be powered by a secondary battery, it is often desirable to operate only the most important information retention function, and the configuration shown in FIG. 1 is only for this case.

As an example, if 16Kb CM088RAM is used as memory, even when there is no light and the solar cells are not operating,
．． It was found that information is retained for more than five years. Furthermore, since the ρ device is normally used in the presence of light, the thin film battery is always in a nearly charged state. Therefore, 1.5
The device of the present invention will operate without being stored in a dark place for more than a year and will appear to have a permanent power supply.

Furthermore, it is easy to display information regarding the capacity of the battery on a portion of the display, such as a liquid crystal display, resulting in a more effective thin non-volatile memory device.

〔Effect of the invention〕

According to the present invention, a portable card-like memory device that has a power supply under any conditions can be created, so it becomes a device with new functions such as a non-volatile memory terminal for personal use, a memory file, and a data-like terminal, and its significance is big 0

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a circuit configuration of a thin semiconductor mesh according to the present invention.

Claims (1)

[Claims] 1. A semiconductor memory having a semiconductor element having a volatile memory and a solar cell for driving the same, and a thin film secondary battery connected in parallel to the solar cell via a diode. Semiconductor memory characterized by: □ 2. The semiconductor memory according to claim 1, wherein the Kamiki rechargeable battery is an all-solid-state thin film secondary battery. 3. The semiconductor memory O according to claim 1, wherein the secondary battery is an all-solid-state thin film lithium secondary battery.