JPS6012771B2 - Capacitor manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a capacitor manufacturing method in which a dielectric layer is obtained by an anodic oxidation method. The purpose is to provide a method for anodizing.

Recently, there has been a strong desire to downsize capacitive elements in the field of microelectronics, and it is currently difficult to incorporate capacitive elements in flexible circuit technology in particular.

This is because there is a problem with the technology of configuring thin film capacitive elements on plastic sheet substrates to meet the demand for miniaturization. Specifically, the thin film materials of capacitor components such as vapor deposited films formed on substrates have problems. This is because they include aspects that are not practical in that they overlap with each other with excellent adhesion. For example, a polyethylene terephthalate film (100 mm thick) is used as a substrate, aluminum is vacuum-deposited,
This vapor deposited layer is anodized in an electrolytic solution using the Aoi deposited film as an anode to form N203, the peak 203 layer is used as a dielectric layer, and AI is vacuum evaporated on the dielectric layer as a counter electrode. However, when manufacturing capacitors, the adhesive strength between the polyethylene terephthalate film substrate and the peaks was a problem, and repeated bending stress caused problems with the capacitance.

The present invention eliminates such conventional drawbacks by disposing a flexible insulating substrate and a desired metal evaporation source facing each other in a vacuum chamber, and ionizing a portion of the metal vapor. The method is characterized in that a desired metal layer is formed on an insulating substrate that is held in a negative position with respect to the evaporation source by a vapor flow containing ions.

An example of a metal layer forming layer for implementing the present invention is shown in the drawings. The vacuum chamber 1 is usually made of stainless steel and has a water bath pipe on the outside, but it may also be made of gas, and it is preferable to choose a material that releases a small amount of gas. This vacuum chamber 1 is connected to a vacuum evacuation system 2 via a main pulp (not shown).
An evaporation source 3 and a sacrificial insulating substrate 4 having a negative potential with respect to the evaporation source 3 are disposed facing each other in a vacuum chamber 1, and a high frequency electrode 5 is disposed in a space between the two. Then, an electrode 6 having a barrier portion is provided on the evaporation source side of the insulating substrate 4. This electrode 6 is often made of stainless steel wire mesh. 7 shows a roll of the flexible insulating substrate 4, and the winding mechanism and drive mechanism are omitted.

Although the evaporation source 3 is an electron beam evaporation source shown in the figure, it is not limited to this and may be any known evaporation source such as a laser beam method, high-frequency induction heating method, or resistance heating method. From this point of view, electron beam evaporation sources and laser beam evaporation sources, in which the evaporated metal does not contain the constituent materials of the evaporation source, are advantageous, but from a practical standpoint, we believe that the electron beam evaporation source is optimal. Although there are several types of electron beam evaporation sources, an example of 180° deflection is shown. That is, the metal 3 to be evaporated is placed in a water-cooled steel hearth 8, and thermionic electrons emitted from the filament 9 are converted into beams by the high-voltage electrode 10 and beam forming poles 11 and 12, and sent into a deflection magnetic field (not shown) L, which causes the evaporation. Vaporize metal 3. 13 is a filament heating power source, and 14 is an acceleration power source. Reference numeral 15 is a DC power supply for the substrate, 16 is a high frequency power supply, and a matching box for improving the transmission efficiency of high frequency power is not shown.

17 is an insulating bushing; 18 is a needle valve, which has the role of adjusting the amount of inert gas 19 such as Xe introduced into the vacuum chamber 1 as necessary.

Next, to briefly explain the operation and operation, the inside of the vacuum chamber 1 is evacuated to 5×10-5 Ton or less in advance.

Thereafter, by adjusting the needle valve 18, for example, Ar gas is introduced to a level of 1×10-orr. It takes 10 to 30 minutes to reach equilibrium. Thereafter, the high frequency power source 16 is operated to generate a high frequency glow discharge near the high frequency power source 5. In this state, operate the electron beam evaporation source,
Vaporize metal 3. The metal vapor is ionized to a small extent simply by heating and evaporating it with an electron beam, but it is exposed to a high-frequency glow to further increase the amount of ions, and a metal vapor flow containing ions with accelerated energy is injected onto the substrate 4. Rapid deposition to form the desired metal layer.The DC accelerating voltage is not necessarily high, but 2 to 3 trillion V is often suitable below 10 KV.High frequency glow cannot be stabilized at 5 x 10-5 Ton. Therefore, if you want to avoid impurities (even Ar gas has the negative effect of lowering the withstand pressure), you can operate the electron beam evaporation source at a high 3-temperature operation with the shutter (not shown) closed, that is, generate a large amount of the desired metal vapor. Let, 5×10-
It is best to gradually increase the power of the electron beam and open the needle valve so that the pressure can be adjusted to 4 tons using only metal vapor.

In addition, although the ion content decreases somewhat, it is 45 × 10-5
An ionization mechanism consisting of a hot cathode and anode system that can stably generate ions even in a high vacuum of Torr may be provided in place of the high frequency electrode 5. After forming the metal layer, the entire substrate 4 is taken out from the vacuum chamber 1, and a part of the metal layer is anodized by a normal anodic oxidation method using an electrolytic solution to form a dielectric layer.
The counter electrode may then be formed by placing the substrate in a vacuum chamber again, or by another method. A capacitor is thus formed. Next, examples of the present invention will be shown.

[1'Substrate; Plastic film (2 types) (21
Metal: Tantalum (99.99% purity) ■ Electron beam:
Ship W [4' High frequency power: IKW (frequency about 13.58M) (5) Operating vacuum: 5 x 10-4 Torr [61
Electrolyte: 1% phosphoric acid aqueous solution '71 Counter electrode: Tantalum electron beam coating The upper case (■) uses a polyethylene terephthalate film as the substrate, and the lower case (2) uses a polypropylene film as the substrate.

Although no major differences were observed in terms of capacity,
It has been found that the capacitor of the present invention has fewer changes in terms of problems.

This effect is expected to enable the incorporation of a small capacitor with a larger capacity, for example, using TiO2 as a dielectric, into a flexible circuit, and we have confirmed that it actually works.

In addition, we also confirmed mountain 203 from AI, W03 from W, etc. By further developing it and winding it, it is also possible to manufacture large-capacity capacitors. As described above, according to the manufacturing method of the present invention, a capacitor with high withstand voltage can be obtained.

[Brief explanation of the drawing]

The drawing is a sectional front view of an apparatus used to carry out the manufacturing method of the present invention. 1... Vacuum chamber, 3... Evaporation source, 4...
...Movable insulating board.

Claims (1)

[Claims] 1 Forming a metal layer by ion plating on a flexible insulating substrate that is at a negative potential with respect to the evaporation source in a vacuum chamber,
A method for manufacturing a capacitor, comprising forming a part of the metal layer into a dielectric layer by anodic oxidation, and forming a counter electrode layer on the dielectric layer.