JPS59158512A - High dielectric thin film condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high dielectric thin film capacitor that is small in size and has a large capacitance. As electronic devices become smaller, the number of electronic components housed per unit volume is increasing. Boundary-related elements such as transistors and diodes have become extremely miniaturized due to advances in integrated circuit fabrication technology, but capacitors, on the other hand, have a characteristic that capacitance is directly proportional to electrode area, so it is difficult to reduce capacitance. It is not easy to downsize without In particular, miniaturization of capacitors having a capacitance of 1 μF or more is slow.

There are three ways to downsize a capacitor without reducing capacitance. One is to increase the permittivity of the dielectric material. TiO is a material with a large dielectric constant.
Examples include oxides such as 2 and ferroelectrics such as BaTiO3. Capacitors using such a high dielectric material have traditionally existed as ceramic capacitors, but these are manufactured using a method in which the high dielectric material is made into a slurry with an organic binder, etc., and then stretched thin and sintered. , because it contains many voids inside, it does not fully demonstrate the characteristics of the material. As described below, it is still insufficient to reduce the thickness, which is a factor in miniaturizing capacitors.

Another way to downsize capacitors is to reduce the thickness of the base material that makes up the electrodes. This method is expected to have the effect of reducing the volume occupied by the electrode.

Another method is to reduce the thickness of the dielectric. This method not only has the effect of reducing the volume occupied by the dielectric, but also has the effect of increasing the capacitance if the electrode area is the same.In other words, to make the capacitance the same, the electrode area must be increased. It has the effect of making it smaller. 1. The latter two methods of reducing the thickness of the structure make it difficult to manufacture such a thin structure, but also require a special method in the process of processing it into a capacitor. , becomes unwieldy. In other words, this method is unavoidably adopted in order to increase the capacitance, and it would be desirable if the capacitance could be made smaller without reducing the capacitance by using a more manageable thickness.

In view of this situation, the present inventor conducted extensive research to develop a compact capacitor with a large capacitance, and as a result, arrived at the present invention. That is, in a capacitor in which the electrode is a metal foil and the dielectric is a high dielectric thin film, a metal 1 serving as an electrode of the capacitor is coated on the surface of the metal foil under a reduced pressure of IXIO Torr or less.
It has been found that a capacitor constructed from a high dielectric thin film laminated metal foil obtained by laminating high dielectric thin films with a thickness of 0.01 to 1 micron satisfies the objects of the present invention.

Any metal foil may be used as the electrode in the present invention as long as it is a good electrical conductor, but aluminum foil is most suitable because it is easy to dry and is inexpensive. As mentioned above, the thinner the metal foil, the better it is for miniaturization, but the process of developing and storing a high dielectric thin film,
In the process of processing into condensers, aluminum foil with a thickness of 20 microns or more tends to break or wrinkle, making the work extremely difficult. The purpose of the present invention is to use a metal foil with a thickness that is easy to handle. The surface of the metal foil is preferably smooth in order to improve its adhesion to the χ1 pole.

Examples of the high dielectric material according to the invention include oxides of Ti and Ta, and ferroelectric materials such as BaT iO3. These high dielectric materials k1. Methods for laminating metal foil with a thickness of 01 to 1 micron under reduced pressure of X 10 Torr or less include vacuum evaporation, sputtering, ion blating, low pressure CVD, and plasma C.
There is the VD method etc. ], The reason why the metal foil melts under reduced pressure below XIO Torr is that no voids are generated in the laminated high dielectric thin films. This is also to prevent the formation of an oxide film on itself. All of the above-mentioned lamination methods are suitable for forming a thin film under such reduced pressure conditions. High dielectric materials include BaTiO3 in which part of the Ba is replaced with residual dust such as Sr, and materials with a dielectric constant of over 10.000 at room temperature, which are extremely effective in reducing the size of capacitors. However, when stacking such high dielectric thin films, it is desirable to use a high frequency sputtering method using a high dielectric material microcrystallized by sintering as a target.

In particular, the magnetron-based high-frequency sputtering method is the most disadvantageous in terms of production because it forms a thin film at a high speed. The thickness of the dielectric layer may be selected appropriately depending on the capacitance and withstand voltage required for the intended capacitor.

For miniaturization, it is better to make the case thinner, but in addition to lowering the withstand voltage, it also increases the frequency of pinholes.
A thickness of 1 micron or less has no practical meaning.Also, since high dielectric materials have brittle properties, freezing of 1 micron or more is not suitable for use in rolls of laminates [7]. No. The highly dielectric thin film laminated metal foil prepared in this way is the first generation, and is processed into a condenser as shown below. As shown in Figure 1, metal foil 1 (1) is laminated with metal foil 1 (1), a metal foil (2) is layered on the carcass (3) as a counter electrode, gold foil (4) is layered with gold, and a lead wire is used. (5, 5') and stop the whole thing with resin (6). Further, as shown in Fig. 2, a conductive paint (9) is applied to the surface of the high dielectric thin film (8) of the laminate (7), and a conductive adhesive (11) is applied to the lead wire (10). ), and the whole is made of resin (12)
Seal with. 1, as shown in Figure 3, the laminate (13) e
, a large number of sheets are stacked one on top of the other with slight shifts alternately, and the electrode extraction portions (14, 14) and lead wires (15, 15) are attached to the shifted portions and sealed with resin (16). As shown in Figure 3, two long tape-like laminates are used to make one
can also be made isomorphic.

Examples are given below.

Example 1 Ti02 was deposited on one side of an aluminum foil with a thickness of 25μ and a smooth surface using an electron beam heating vacuum evaporation apparatus to a thickness of a.
It was deposited to a thickness of 0.05 micron.

Since the acid accumulation in the deposited film composition had decreased, the laminate was
The composition was adjusted by heating at 00°C for 5 hours in air. A capacitor was fabricated by laminating 50 sheets of this laminate as shown in FIG. The size of the capacitor is the thickness],, 3
wn, width 30 mm, depth 50 mm, and electrode area was 65 mm. The capacitance of this capacitor was 4.0 μF.

Example 2 An aluminum foil with a thickness of 50 μm and a smooth surface was coated with a tarquent made of BaTiO3-based porcelain having a dielectric constant of 18.000 at room temperature. Dielectric layers were laminated. As shown in FIG. 2, this laminate was made into a capacitor using conductive paint.

The capacitor had a thickness of 0.2 m, a width of 30 pieces, a depth of 100 mm, and an electrode area of 0.3 cm.

The capacitance of this capacitor was 80IiF.

It should be noted that a capacitor having such a shape is used standing up on a circuit board, and in that case, the area occupied by the board is 06-.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of a capacitor using one high dielectric thin film laminated metal foil according to the present invention, and FIG. 3 is a cross-sectional view of a capacitor using a large number of high dielectric thin film laminated metal foils. Patent Applicant: Sumitomo Bakelite Co., Ltd. Figure 2 One inch Figure 3 2 16

Claims (1)

[Claims] A high dielectric thin film capacitor characterized in that a high dielectric thin film is laminated with a thickness of 0.01 to 1 micron at a reduced pressure of 1 x lOTor or less on the surface of a metal foil serving as an electrode.