JPH05129149A - Film capacitor - Google Patents

Abstract

PURPOSE:To see that the film such as the dielectric, the inner electrode, etc., made on a glaze and the resin layer on an inorganic insulating film can not be made with high accuracy with specified patterns shapes by solving the theme such as that the pattern shape of a film dielectric, an inner electrode, etc., can not be made with high accuracy. CONSTITUTION:The thickness of the glaze layer 2 on a ceramic board 1 is 10-25mum and the average roughness Ra of time center line at the surface of the glaze layer is 0.01-0.2mum. Hereby, the specified pattern shape of the film or the protective resin made on the glaze layer can be made with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film capacitor used in electronic circuits in electronic equipment and the like.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, there has been an increasing demand for chipping and miniaturization of electronic components accompanying the high-density mounting of electronic components using surface mounting technology. .. Among them, various efforts have been made to reduce the size of capacitors, and one of the efforts is a thin film capacitor in which the dielectric film is made thin.

A conventional thin film capacitor will be described below. FIG. 1 is a sectional view showing the basic structure of a conventional thin film capacitor and a thin film capacitor of the present invention.
The glaze layer 2 is formed by a pattern as shown in FIG. 1, and the thin-film dielectric 3 and the internal electrodes 4a and 4b which are displaced layer by layer across the glaze layer 2 toward both ends of the ceramic substrate 1. Are alternately laminated, and the inorganic insulating film 5 is formed except for the internal electrodes 4a and 4b at both ends of the ceramic substrate 1.
A resin layer 6 was formed on the inorganic insulating film 5, and the external electrode 7 was formed by dividing this into individual pieces to form a thin film capacitor.

At this time, in order to secure the adhesion strength of the external electrodes 7, both ends of the ceramic substrate 1 are made into non-glaze parts 8 having an average center line roughness (hereinafter referred to as Ra) of 0.1 μm or more, and the thin film dielectric is used. Ra must be 0.01 μm or less for the surface of the glaze layer 2 that can sufficiently exhibit the characteristics of the body 3, and in order to achieve this, the thickness of the glaze layer 2 is set as shown in FIG. It had to be thick, that is, about 50 μm.

[0005]

However, in the above-mentioned conventional thin film capacitor, since the glaze layer 2 has a large film thickness, when the pattern of the thin film dielectric 3, the internal electrodes 4a, 4b, etc. is formed. However, there is a problem that it is impossible to secure a predetermined pattern shape with high accuracy.

As shown in the cross-sectional shape of the conventional glaze layer 2 in FIG. 3, when the glaze layer 2 has a large film thickness, the shape thereof becomes a mountain shape having very few flat regions, and therefore, a plate shape. This is because when the pattern is formed using the mask (not shown), the adhesion between the mask and the glaze surface becomes incomplete.

Also, regarding the formation of the resin layer 6 on the inorganic insulating film 5, when a pattern is formed by a method such as screen printing or photolithography, a screen mask and a grain are formed in the same manner as described above. The accuracy of the resin shape is deteriorated due to the incomplete adhesion of the scratch surface or the deterioration of the resolution of the photoresist, and it is difficult to secure the line width of the scribe line when dividing into individual pieces later.

The present invention is intended to solve the above-mentioned problems. The dielectric layer formed on the surface of the glaze layer, thin films such as internal electrodes, and the predetermined pattern shape of the resin layer on the inorganic insulating film can be precisely formed. An object is to provide a thin film capacitor that can be formed.

[0009]

In order to achieve the above object, the thin film capacitor of the present invention has a glaze layer having a thickness of 10
To 25 μm, and Ra at that time is 0.01 to 0.2 μm
It is what

[0010]

Therefore, according to the present invention, the film thickness of the glaze layer is set to 10 to 25 μm to improve the adhesion between the plate-shaped mask or screen mask and the glaze surface.
Also, since the deterioration of the resolution of the photoresist is reduced,
It is possible to ensure a predetermined pattern shape of the resin layer on the thin film such as the dielectric and the internal electrode and the inorganic insulating film with high accuracy. Ra of the glaze surface at that time is 0.01 to 0.2.
If it is μm, the characteristics of the thin film dielectric can be sufficiently satisfied.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a thin film capacitor according to the present invention. The same parts as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted. Differences will be described.

In the thin film capacitor of the present invention, the glaze layer 2 is provided on the ceramic substrate 1, and the internal electrode 4a is formed so as to extend over the glaze layer 2 and the non-glaze portion 8. Then, After forming the thin film dielectric 3 made of an organic material so as to straddle the internal electrode 4a and the glaze layer 2, an internal electrode 4b having a polarity different from that of the internal electrode 4a is formed on the thin film dielectric 3 and further, The thin film dielectric 3 is formed on the internal electrode 4b. By repeating such lamination, a predetermined number of laminations are completed to form individual thin film capacitors, and the inorganic insulating film 5 is formed.
Is used as a sealing film over the entire surface of the thin film capacitor, and the resin layer 6 is formed on the inorganic insulating film 5 with the non-glaze portion 8 left, and then the resin layer 6 is not formed. The inorganic insulating film 5 is removed by etching to expose the non-glaze part 8. Thereafter, each thin film capacitor is divided into individual pieces by inserting a scribe line by a carbon dioxide gas laser into individual pieces, and both ends of the ceramic substrate 1 including the non-glaze portion 8 in which the end portion of the internal electrode laminated portion is formed. The external electrode 7 is formed on the portion to complete the thin film capacitor shown in FIG.

Two types of embodiments and three types of comparative examples will be described in more detail below with reference to the drawings.

Example 1 A thin film capacitor was formed on a ceramic substrate 1 with the structure shown in FIG. The thickness of the glaze layer 2 is 25 μm, and Ra on the glaze surface is 0.05 μm.
m, and the internal electrodes 4a and 4b are made of aluminum with 500Å
EB vapor deposition (electron beam evaporation source vapor deposition) with a thickness of 2000 .ANG., And polyurea as a thin film dielectric 3 made of an organic material was patterned at a thickness of 2000 .ANG. By a vapor deposition polymerization method using a metal mask. The inorganic insulating film 5 is a silicon oxynitride film (SiON) formed by a plasma CVD method.
The resin layer 6 was formed by a photolithography method using a positive resist OFPR-2 manufactured by Tokyo Ohka Kogyo Co., Ltd.

Then, the SiON film in the portion where the resin layer 6 is not formed is removed by immersing it in an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed in a ratio of 1: 5. EXAMPLE 1 A scribe line by a carbon dioxide gas laser was inserted to divide the substrate to form external electrodes 7.
The thin film capacitor of was completed.

Example 2 A thin film capacitor was formed on a ceramic substrate 1 with the structure shown in FIG. The thickness of the glaze layer 2 is 10 μm, and Ra on the glaze surface is 0.2 μm.
The inner electrodes 4a and 4b are formed by EB vapor-depositing aluminum with a thickness of 500Å, and polyurea is used as the thin-film dielectric 3.
Patterns were formed with a thickness of 000Å by vapor deposition polymerization using metal masks. As the inorganic insulating film 5, a SiON film having a thickness of 2 μm is formed by a plasma CVD method, and as the resin layer 6, a screen printing resin 1300 # 120 white manufactured by Seiko Advance Co., Ltd. is formed by a screen printing method. ..

Then, the SiON film at the portion where the resin layer 6 is not formed is removed by immersing it in an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed at a ratio of 1: 5. EXAMPLE 2 A scribe line using a carbon dioxide gas laser was inserted to divide the substrate to form external electrodes 7.
The thin film capacitor of was completed.

Comparative Example 1 A thin film capacitor having a conventional glaze layer 2 shown in FIG. 3 was formed on a ceramic substrate 1. The thickness of the glaze layer 2 is 50 μm, Ra on the glaze surface is 0.005 μm, and the internal electrodes 4a and 4b are
Was EB vapor-deposited with a thickness of 500 Å, and as the thin film dielectric 3, polyurea with a thickness of 2000 Å was formed by vapor deposition polymerization using a metal mask. The inorganic insulating film 5 is SiON formed by plasma CVD method.
The film was formed to a thickness of 2 μm, and the resin layer 6 was formed by a photolithography method using a positive resist OFPR-2 manufactured by Tokyo Ohka Kogyo Co., Ltd.

Next, the SiON film in the portion where the resin layer 6 is not formed is removed by immersing it in an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed in a ratio of 1: 5. Comparative Example 1 in which a scribe line by a carbon dioxide gas laser was inserted to divide the substrate to form external electrodes 7.
The thin film capacitor of was completed.

Comparative Example 2 A thin film capacitor having a conventional glaze layer 2 shown in FIG. 3 was formed on a ceramic substrate 1. The thickness of the glaze layer 2 is 50 μm, Ra of the glaze surface is 0.01 μm, aluminum is EB vapor-deposited on the internal electrodes 4a and 4b to a thickness of 500 Å, and the thin film dielectric 3 is made of polyurea to a thickness of 2000 Å. Then, patterns were formed by vapor deposition polymerization using metal masks. As the inorganic insulating film 5, a SiON film having a thickness of 2 μm is formed by a plasma CVD method, and as the resin layer 6, a screen printing resin 1300 # 120 white manufactured by Seiko Advance Co., Ltd. is formed by a screen printing method. ..

Then, the SiON film in the portion where the resin layer 6 is not formed is removed by immersing in an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed at a ratio of 1: 5. Comparative Example 2 in which a scribing line using a carbon dioxide gas laser was inserted to divide the substrate into external electrodes 7.
The thin film capacitor of was completed.

(Comparative Example 3) A thin film capacitor was formed on a ceramic substrate 1 with the structure shown in FIG. The thickness of the glaze layer 2 is 5 μm, Ra on the glaze surface is 0.4 μm, and aluminum is deposited on the internal electrodes 4a and 4b by a thickness of 500 Å by EB to form polyurea as a thin film dielectric 3.
Patterns having a thickness of 00Å were formed by vapor deposition polymerization using metal masks. The inorganic insulating film 5 is plasma C
A SiON film by the VD method was formed to a thickness of 2 μm, and the resin layer 6 was formed by Seiko Advance Co., Ltd. screen printing resin 1300 # 120 white by the screen printing method.

Next, the SiON film in the portion where the resin layer 6 is not formed is removed by immersing it in an etching solution in which hydrofluoric acid (HF) and ammonium fluoride (NH ₄ F) are mixed at a ratio of 1: 5. Comparative Example 3 in which a scribing line using a carbon dioxide gas laser was inserted to divide the substrate to form external electrodes 7.
The thin film capacitor of was completed.

The characteristics of the thin film capacitors according to Examples 1 and 2 and the characteristics of the thin film capacitors according to Comparative Examples 1, 2 and 3 are shown in comparison with (Table 1).

[0025]

Table 1 In Comparative Examples 1 and 2 using the conventional glaze layer 2 having a film thickness of about 50 μm, about 40% of the completed devices have poor reliability, and the tan δ value becomes abnormal due to the charge / discharge test. It was One of the causes of the poor reliability is that the thin film dielectric 3 made of polyurea leaks from the metal mask because the adhesion between the metal mask and the surface of the glaze layer 2 is poor.
This is an incomplete sealing of the SiON film because the clearance with the inorganic insulating film 5 made of the N film cannot be secured. Another cause is that the resin layer 6 protrudes from the resin layer 6 due to the resolution of the photoresist or the deterioration of the resin forming accuracy due to the screen printing. There is a possibility that a crack is generated in the SiON film by hitting.

The cause of the abnormal tan δ value in the charge / discharge test is that the electrical connection between the internal electrodes 4a and 4b and the external electrode 7 is deteriorated by the protrusion of the resin layer 6 to the external electrode 7 side.

When the glaze layer 2 having a film thickness of 5 μm is used as in Comparative Example 3, Ra becomes 0.4 μm. Therefore, all the pattern precisions are good, but the withstand voltage of the polyurea is deteriorated and the sealing property of the SiON film is deteriorated, so that the withstand voltage yield is lowered and the reliability is also lowered.

On the other hand, in Examples 1 and 2, by setting the thickness of the glaze layer 2 to 10 to 25 μm, the completed element can secure the clearance between the polyurea and the SiON film, and the resolution of the photoresist is good. Or the accuracy of the resin formation by the screen printing method can be improved.
There was no protrusion, and the laser portion could be secured, and 100% reliability could be secured. Also, the electrical connection between the internal electrodes 4a and 4b and the external electrode 7 was good, and there was no change in the tan δ value due to the charge / discharge test.
Further, Ra had no problem in characteristics up to 0.2 μm.

In this embodiment, polyurea is used as the thin film dielectric 3, but the same effect can be obtained by using other organic thin film or inorganic thin film. Further, although SiON by the plasma CVD method is used as the inorganic insulating film 5, a material having a good sealing property by another film forming method may be used. In addition, the resin layer 6
The resin may be any other applicable resin material, and the photolithographic method or the screen printing method is used in the present embodiment as the forming method, but it goes without saying that other methods may be used. Further, although the present invention describes the thin film capacitor, the same can be said for other circuit parts using other organic, inorganic, and metal thin films.

[0030]

As is apparent from the above embodiments, the thin film capacitor of the present invention has a glaze layer thickness of 10 to 25 .mu.m.
By setting m and Ra to 0.01 to 0.2 μm, the adhesion between the glaze surface and the plate-like or screen mask is improved, and the deterioration of the resolution of the photoresist is reduced,
A predetermined pattern shape can be secured with high accuracy, and excellent capacitor characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic configuration of an embodiment of the present invention and a conventional thin film capacitor.

FIG. 2 is a perspective view showing a printing pattern of a glaze layer in a conventional thin film capacitor.

FIG. 3 is a partial sectional view showing the shape of a glaze layer on a ceramic substrate in the same thin film capacitor.

[Explanation of symbols]

 1 Ceramic Substrate 2 Glaze Layer 3 Thin Film Dielectric 4a, 4b Internal Electrode 5 Inorganic Insulation Film 6 Resin Layer 7 External Electrode

Claims (1)

[Claims] 1. A ceramic substrate on which a glaze layer is formed in a region excluding both ends of at least one main surface, and a thin film dielectric is interposed on the glaze layer to be laminated, and one end of each of the glaze layers is formed into the glaze layer. -A pair of internal electrodes alternately extended over the ceramic substrate at both ends of the ceramic substrate, and both ends of the ceramic substrate on the laminated pair of internal electrodes and a thin film dielectric. An inorganic insulating film formed by removing
A thin film capacitor having a resin layer formed on the inorganic insulating film, and external electrodes formed on both ends of the ceramic substrate in an extended portion of the internal electrode not covered by the inorganic insulating film and the resin layer. And the thickness of the glaze layer is 10 μm to 25 μm, and
The average center line roughness (Ra) of the surface of the slag layer is 0.01 μm to
A thin film capacitor having a thickness of 0.2 μm.