JPH0324712A - Capacitor and manufacture thereof - 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 Technical Field of the Invention The present invention relates to a capacitor having a large capacitance and excellent voltage resistance, particularly a multilayer capacitor.

TECHNICAL BACKGROUND OF THE INVENTION One type of capacitor is a thin film capacitor made of a dielectric thin film. In this structure, a lower electrode, a dielectric film, and an upper electrode are laminated in this order on a substrate.

In such thin film capacitors, the capacitance is proportional to the permittivity of the dielectric film and inversely proportional to the thickness of the dielectric film. Therefore, in order to increase the capacitance, a material with a high permittivity must be used or a dielectric material All you have to do is make the film thinner. Generally, materials with a high dielectric constant have a large change in dielectric constant with temperature, so in a thin film capacitor using such a material as a dielectric film, the capacitance of the capacitor varies greatly with changes in temperature.

Therefore, it is conceivable to use a material with a small temperature coefficient as the dielectric thin film and reduce the thickness of the dielectric film in order to improve its capacity. However, in such cases, a satisfactory capacitance cannot be obtained unless the thickness of the dielectric is made sufficiently thin. Moreover, when the dielectric film is thin like this, there is a problem in that the withstand voltage becomes small due to unevenness or foreign matter in the underlying layer.

Furthermore, in conventional thin film capacitors, the lower electrode and dielectric film are laminated in this order on the substrate, so the lower electrode is also exposed to high temperature when the dielectric film is fired, resulting in excellent heat resistance. It was necessary to use an electrode such as PT. Moreover, when such a heat-resistant electrode is used, an adhesive layer is required between the electrode and the substrate, making the electrode manufacturing process complicated and costly.

It is known that a silicon oxide layer obtained by thermally oxidizing the surface of a Si substrate is used as a capacitor in integrated circuits, but as an individual capacitor, a film of silicon oxide layer is used to improve capacitance. When the thickness was reduced, there was a problem in that the withstand voltage property decreased.

In addition, as shown in FIG. 3, in order to increase the capacitance, a plurality of ceramic sheets 22 are made of dielectric material.
A ceramic multilayer capacitor 20 is also known in which the capacitors are laminated with internal electrodes 24 arranged alternately on the left and right sides, and the internal electrodes 24 of every other layer are connected by separate external electrodes 26 and 26.

Under these circumstances, the present inventors are developing a capacitor that can increase the capacitance by laminating Si substrates with a dielectric film formed on the surface, but the Compared to the case of stacking sheets 22, when stacking SL substrates on which dielectric films are formed, 81
Since the substrate also functions as an internal electrode, it was not possible to construct a capacitor with a laminated structure as shown in FIG.

OBJECTS OF THE INVENTION The present invention was made in view of the above circumstances, and an object of the present invention is to provide a capacitor having a large capacitance and excellent voltage resistance, and a method for manufacturing the same.

Summary of the Invention In order to achieve the above object, a capacitor according to the present invention includes a plurality of Si substrates and a dielectric film made of silicon oxide formed on the front and back surfaces of each Si substrate. , the Si substrates on which the dielectric films are formed are laminated in the film thickness direction with internal electrodes interposed therebetween, an insulating groove is formed at one end of each internal electrode, and an insulating groove in each internal electrode is formed. A first external electrode is connected to one side end surface of each Si substrate on the side where the insulating groove is formed, and a second external electrode is connected to one side end surface of each internal electrode on the side where the insulating groove is not formed. It is characterized by connected electrodes.

In the present invention, the specific resistance of the Si substrate is 0.1Ω・(1)
It is preferable that it is below.

Since the present invention has an electrode structure in which a plurality of Si substrates are electrically connected to each other and become part of the electrode, the lower electrode and the dielectric film are laminated in this order on the substrate as in the conventional case. There is no need to do so, and there is no need to worry about deterioration of the lower electrode that may occur when burning out the dielectric film. Furthermore, in the present invention, since silicon oxide formed on the front and back surfaces of the Si substrate is used as the dielectric film, the adhesion between the dielectric film and the SL substrate is improved, and cracks in the dielectric film can be prevented. It is possible to prevent this. Furthermore, although the silicon oxide film obtained by thermally oxidizing a Si substrate has a small dielectric constant of 4 or less, the film is dense and has a high withstand voltage, so that the withstand voltage property of the dielectric film is also improved. Furthermore, in the present invention, a silicon oxide film layer is provided not only on one side surface of the Si substrate but also on the back surface, and this is used as a dielectric film, and the silicon oxide layer is formed in this way. Since the Si substrates are laminated via internal electrodes, the capacitance is multiplied compared to the case where a dielectric film is formed on only one side of the Si substrates.

Further, the method for manufacturing a capacitor according to the present invention includes
A dielectric film made of silicon oxide is formed on the front and back surfaces of the i-substrate, and the Si substrates on which these dielectric films are formed are stacked with internal electrodes interposed between them, and one side of each internal electrode is An insulating groove is formed on the end face, a dielectric film made of silicon oxide is formed on the side end face of each Si substrate on the side where the insulating groove is not formed, and a dielectric film is formed on the side end face of each Si substrate on the side where the insulating groove is formed. Each S
A first external electrode is formed on one end surface of the i-substrate to connect these, and a second external electrode is formed on one end surface of each internal electrode on the side where the insulating groove is not formed to connect these. It is characterized by

According to the method for manufacturing a capacitor according to the present invention, since the insulating groove is provided at one end of the internal electrode, each S
This facilitates the process of connecting the i-substrates using the common first external electrode.

DETAILED DESCRIPTION OF THE INVENTION The capacitor according to the present invention will be specifically described below.

FIG. 1 is a sectional view showing an example of a capacitor according to the present invention;
FIG. 2 is a sectional view showing a method of manufacturing a capacitor according to the same embodiment.

As shown in FIG. 1, a capacitor 2 according to the present invention includes a plurality of Si substrates 4 and a dielectric film 6 formed on the front and back surfaces of each Si substrate 4. In the present invention, Si substrates 4 on which such dielectric films 6 are formed are stacked in the film thickness direction with internal electrodes 8 interposed therebetween.

The internal electrode 8 is a dielectric film 6 of the superimposed Si substrates 4.
It is interposed between them and is also located at the bottom end of the laminate.

An insulating groove 9 is formed in one end portion 8 of each internal electrode 8 interposed between dielectric films 6 .

In the embodiment shown in FIG. 1, a dielectric film 6a made of silicon oxide is also formed on the side end surface 4a of the Si substrate 4 on the side where the insulating groove 9 is not formed. Dielectric film 6a in this part
serves as an insulating layer between the Si substrate 4 and a second extraction electrode 16, which will be described later.

One side end surface 4 of each Si substrate 4 on the side where the insulating groove 9 is formed
A first external electrode 14 is formed in b to electrically connect each Si substrate 4 . Further, a second external electrode 16 is provided on one side end surface 8b of each internal electrode 8 on the side end surface 4a side of the Si substrate 4 covered with the dielectric film 6a.
The dielectric film 6a is formed on the dielectric film 6a so as to be electrically connected to each other. In the present invention, the Si substrate 4 also functions as an internal electrode.

The dielectric film 6.6a is made of silicon oxide and is preferably obtained by thermally oxidizing the Si substrate 4. however,
The dielectric films 6, 6a may be formed by other methods such as vapor deposition or sputtering. The thickness of such dielectric film 6 is preferably 50 to 10 μm, more preferably 100 to 5 μm. Note that the silicon oxide is mainly composed of S h O 2 , but may also contain SiO or the like.

As the internal electrode 8 and the first and second external electrodes 1416, electrodes such as Ag, CuSAu, A, Q, PtsPd, etc. can be used. Sputtering, vapor deposition, paste coating, and the like are used to form the internal electrodes 8 and the first and second external electrodes 14 and 16 on the surface of the dielectric film 6 and the side surfaces of the laminate. The thickness of the electrode 8 is 0.
It is preferable that it is 1 micrometer - 50 micrometers. Furthermore, the thickness of the external electrodes 14.16 is preferably 0.1 μm or more. Note that the second external electrode 16 does not necessarily need to be provided on the entire side surface of the laminate, and may be directly connected to one end surface of each internal electrode 8 by lead wires, wire bonding, or the like. In this case, the dielectric film 6a serving as an insulating film is not necessarily required.

It is preferable that the Si substrate 4 has a specific resistance of 0.1 Ω·cm or less. If the specific resistance of the Si substrate itself is small, S
This is because the i-substrate 4 also functions as an internal electrode. Specifically, as the Si substrate 4, a silicon wafer or the like is used. Silicon wafers include non-doped type, P
It is possible to use commercially available products of any type, such as type or N type, as they are. The thickness of the substrate 4 is not particularly limited, but is preferably determined so that the resistance value does not become large as an electrode, and is preferably thick enough to impart appropriate rigidity to the entire capacitor. Specifically, it is preferable to have a thickness of 0.1 mm or more. The substrate 4 is not necessarily limited to a flat plate shape. When the substrate has a shape other than a flat plate, the dielectric film and electrode portion formed thereon also have a shape that follows the shape of the substrate.

Next, a method for manufacturing the capacitor 2 according to the present invention will be explained.

First, a Si substrate 4 of a predetermined size is prepared, and this Si substrate 4 is heated under an oxidizing atmosphere. The heating temperature is preferably 300 to 1300°C, more preferably 700 to 110°C.
It is 0°C. The heating time is not particularly limited, but is preferably 3 minutes to 300 minutes, more preferably 10 minutes to 300 minutes.
The duration is 180 minutes. Through such heat treatment, Si
A dielectric film 6 made of a silicon oxide film having a predetermined thickness is formed on the front and back surfaces of the substrate 4 .

After that, a paste-like electrode material that will become the internal electrodes 8 is applied to the surface of the dielectric film 6 on these substrates 4, and a plurality of these are stacked and heated to form a paste-like material stacked between the Si substrates 4. Integrate the electrode parts of the Thereafter, it is cut into an appropriate size to prepare a laminated block 19 as shown in FIG.

Next, one side of one block 1. 9a, an insulating groove 9 is formed along the internal electrode 8 between the dielectric films 6. The insulating groove 9 is formed using a cutting saw or the like. The width of the insulating groove 9 is preferably such that the adjacent Si substrate 4 is not excessively shaved. Further, the depth of the groove 9 is determined so that the insulating effect of the insulating member 10 is maintained. In addition, the second
In the example shown in the figure, the internal electrode 8 is not formed on the entire surface between the dielectric films 6 and 6, but it may be formed on the entire surface.

Before and after that, one block is heated in an oxidizing atmosphere, and each S
A dielectric film 6a made of silicon oxide is also formed on the side end surface 4a of the i-substrate 4. Next, the side end surface of the block 19 on the side where the insulating groove 9 is formed is polished to remove the oxide film formed on the side end surface surface of the Si substrate, and a metal paste is applied to this side surface to remove the first In addition to providing the extraction electrode 14, a second extraction electrode 16 is provided by applying metal paste to the other side surface.

If the dielectric film 6a as an insulating film is not formed on the side end face of each Si substrate 4 on the side surface of one block on the side where the insulating groove 9 is not formed, the second extraction electrode 16
is formed by directly connecting the side end surfaces 8b of each internal electrode 8 using lead wires, wire bonding, etc., without applying metal paste or the like.

By providing the first and second extraction electrodes 14 and 16 on the two sides of the block 19 in this way, each extraction electrode 14.
16, each Si substrate 4 and each internal electrode 8 are connected in common, and the capacitor 2 is completed.

In such a capacitor 2, the silicon oxide films formed on the front and back surfaces of the substrate 4 are used as the dielectric film 6, and the Si substrates 4 are overlapped, so that the capacitor capacity is improved and the durability is improved. Voltage characteristics are also improved.

In addition, in the present invention, the means for manufacturing the capacitor 2 is not limited to the above-described embodiment, and can be variously modified.

Effects of the Invention As explained above, the present invention has an electrode structure in which a plurality of Sl substrates are electrically connected to each other and become part of the electrode. There is no need to laminate the lower electrode and the dielectric film in this order, and there is no need to worry about deterioration of the lower electrode that may occur when firing the dielectric film. Furthermore, in the present invention, since silicon oxide formed on the front and back surfaces of the silicon substrate is used as the dielectric film, the adhesion between the dielectric film and the silicon substrate is improved, and cracks in the dielectric film can be prevented. It is possible to prevent this. Moreover,
Although a silicon oxide film obtained by thermally oxidizing a silicon substrate has a small dielectric constant of 4 or less, the film is dense and has a high withstand voltage, so the withstand voltage property of the dielectric film is also improved. Furthermore, in the present invention, a silicon oxide film layer is provided not only on one side surface of the Si substrate but also on the back surface, and this is used as a dielectric film, and the silicon oxide layer is formed in this way. Since the Si substrates are laminated via internal electrodes, the S
Compared to the case where a dielectric film is formed only on one side of the i-substrate, the capacitance is increased several times.

Further, according to the capacitor manufacturing method according to the present invention, since the insulating groove is provided at one end of the internal electrode, the step of connecting each Si substrate with the common first external electrode becomes easy.

[Examples] The present invention will be described below based on more specific examples, but the present invention is not limited to these examples.

Example 1 Doped with sb, specific resistance is 0.01Ω・0, thickness is 0.5
The related Si substrate was heat treated at 1000° C. for 180 minutes in an 02 atmosphere to form a dielectric film made of 1000 silicon oxide. Next, apply Ag paste to the entire surface and stack 4 sheets of this to 100? After heating and drying for 30 minutes, the internal electrodes were baked to form a laminated block. this,
It was cut into 3 mm width pieces using a cutting saw. Then, along the bonding surface between the dielectric films on the side surface in the longitudinal direction, an insulation hole with a depth of 0.3 was formed using a cutting saw. Afterwards, this block was heated at 1000℃ for 20 minutes in an atmosphere of 0.
A silicon oxide film was also formed on both end faces by heat treatment.

Next, the side surface on which the insulating groove was formed was polished to a depth of about 1 μm to remove the Si thermal oxide film. Then, Ag paste was applied to this side surface and the opposite side surface and dried. Furthermore, this block was cut at right angles to the longitudinal direction to obtain chips of a predetermined size.

The results of measuring the characteristics of the capacitor thus obtained using an LCR meter are shown below.

The capacitance was 3 nF at a measurement frequency of I MHz, and the temperature coefficient of capacitance was 30 ppm/°C at a temperature of 80°C to -20°C.

Also, when the resistance value was measured at a constant voltage, it was 106Ω or more at 20V.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a capacitor according to the present invention;
FIG. 2 is a sectional view showing a method of manufacturing a capacitor according to the same embodiment, and FIG. 3 is a sectional view of a conventional ceramic capacitor. 2... Capacitor 6... Dielectric film 9... Insulating groove 16... Second external electrode 4... Si substrate 8... Internal electrode 14... First external electrode 1q.

Claims (1)

[Claims] 1) It has a plurality of Si substrates and a dielectric film made of silicon oxide formed on the front and back surfaces of each Si substrate, and the Si substrate on which the dielectric film is formed is used as an internal electrode. are laminated in the film thickness direction through the inner electrode, and an insulating groove is formed at one end of each internal electrode, and one end face of each Si substrate on the side where the insulating groove is formed in each internal electrode. A first external electrode is connected to the capacitor, and a second external electrode is connected to one end surface of each internal electrode on the side where the insulating groove is not formed. 2) A capacitor characterized in that the specific resistance of the Si substrate is 0.1 Ω·cm or less. 3) A dielectric film made of silicon oxide is formed on the front and back surfaces of a plurality of Si substrates, and the Si substrates on which these dielectric films are formed are stacked with internal electrodes interposed between them. An insulating groove is formed on one side end face of the electrode, and a dielectric film made of silicon oxide is formed on the side end face of each Si substrate on the side where the insulating groove is not formed before and after the insulating groove, and the insulating groove is formed. A first external electrode is formed on one side end surface of each Si substrate on the side where the insulation groove is formed, and a second external electrode is formed on one side end surface of each internal electrode on the side where the insulation groove is not formed.
A method for manufacturing a capacitor, comprising forming an external electrode.