JPH05251259A - Manufacture of thin film multilayer capacitor - Google Patents

Abstract

PURPOSE:To enable a small thin film multilayer capacitor of high capacity to be manufactured high in productivity at a low cost by a method wherein different evaporation masks are used for the formation of a dielectric body and an electrode, and the side of the evaporation mask coming into contact with an evaporation source is set smaller than the other side in dimensions. CONSTITUTION:Al is evaporated on a substrate by sputtering using a stainless steel evaporation mask 4a whose side in contact with an evaporation mask source is set smaller than other side in dimensions for the formation of a lower electrode 2a. An SiO2 thin film dielectric 3a is evaporated thereon using a different mask 4b, and furthermore an Al electrode is evaporated thereon using a different mask 4c by sputtering. At this point, the evaporation mask 4b and 4c of stainless steel are 0.05mm-1mm in the same thickness as that of the mask 4a, and the sides of them in contact with an evaporation source are set smaller than the other sides in dimension by a length of 20-50mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film multilayer capacitor used as an electric circuit component.

[0002]

2. Description of the Related Art In recent years, with the development of surface mounting technology, there have been remarkable advances in miniaturization of electronic parts and chip formation. Therefore, in the capacitor industry as well, there is an increasing need for (1) miniaturization, large capacity, (2) response to high frequency circuits, and (3) enhancement of environmental resistance.

Conventional capacitors include electrolytic capacitors having a large capacity and ceramic capacitors having a small size, and film capacitors and mica capacitors are generally used as capacitors having excellent electric characteristics.
However, while these capacitors have excellent characteristics as described above, large-capacity electrolytic capacitors,
Small ceramic capacitors have insufficient electrical characteristics,
On the other hand, film capacitors with excellent electrical characteristics have the contradictory characteristics that it is difficult to make them small and have a large capacity.

Generally, as a method for increasing the capacity, (a)
Increase the dielectric constant, (b) increase the capacitance area,
(3) There are three possible ways to reduce the film thickness of the dielectric.

As for (a), BaTiO 3 is used as the dielectric.
It has been attempted for a long time to use a ferroelectric substance such as ₃ , PbTiO ₃ . However, regarding the method of using a ferroelectric substance, (1) if oxygen is not sufficiently supplied in the thin film formation process, it is likely to become a semiconductor. (2) If the film thickness is about 1 μm or less, the dielectric constant does not increase. (3) There is a problem that the dielectric constant has a large temperature dependency and a large electric field dependency, and further, a method of utilizing another substance having a high dielectric constant in order to increase the capacity is a technical solution. The current situation is that this has not been done.

On the other hand, in order to increase the capacity of the capacitor, the method of enlarging the capacity area of (b) is also an effective means. Known methods such as utilizing a laminated structure are ceramic capacitors, film capacitors, etc. Has been put into practical use in.

The method (c) of reducing the film thickness of the dielectric is applied to a thin film capacitor. As a conventional thin film capacitor, a TMM capacitor having a Ta ₂ O ₅ film as a dielectric is well known as a hybrid integrated circuit element. This is _{Ta-Ta 2 O 5 -MnO 2} -Meta
The self-healing action is utilized by sandwiching the MnO ₂ film as a semiconductor layer between the Ta ₂ O ₅ layer and the metal layer in the laminated structure of 1 to improve the withstand voltage of the capacitor as compared with the conventional TM capacitor. That enhances reliability.

[0008]

However, while this thin film capacitor has excellent electrical characteristics like the film capacitor, it is still insufficient for miniaturization and large capacity. Therefore, in order to meet market needs, further Combining (b) and (c), which can achieve small size and large capacity,
That is, it is essential to put a thin film capacitor having a laminated structure into practical use. However, there are many problems in terms of technology and cost, and it is the current situation that it is not yet ready for practical use.

For example, in a Ta ₂ O ₅ thin film capacitor, since a wet chemical treatment called an anodic oxidation method is performed to form a dielectric, a continuous dry process cannot be applied to a production process, and a laminated It is technically difficult to increase the capacitance area by the structure.

Also, in the case of a thin film capacitor having a laminated structure, when a thin film forming means is used, it is necessary to form a thin film pattern. Generally, pattern forming methods are roughly classified into three types: (A) reverse etching method, (B) photo etching method, and (C) mask method. At present, the methods (A) and (B), which are excellent in fine processing, are widely used for semiconductor elements, but these two methods are used for the production of a capacitor element which is cheaper than a semiconductor element by one digit or more. Although one of the two methods enables fine processing, it is not a practical pattern forming method in terms of cost and productivity because the process becomes complicated.

Further, in the photo-etching method or the like, since the pattern edge portion is sharply cut, when the film is formed on the pattern edge portion as the number of laminated layers increases, a problem of step coverage occurs, and as a result, the capacitor element is formed. Adversely affect the electrical characteristics of.

[0012]

In view of the above problems, a method of manufacturing a thin film multilayer capacitor according to the present invention uses a thin film forming means utilizing a dry process on a substrate having a lower electrode formed thereon, and a dielectric material. When alternately stacking at least one layer of electrodes, a mask method is used to form the pattern of the dielectric and the electrodes, and different vapor deposition masks are used for the dielectric and the electrodes. The feature is that the pattern size on the side is reduced.

[0013]

According to the above method, the present invention enables a laminated structure type thin film capacitor, which has not been practically used in a thin film capacitor, by using the existing mask method.

The use of the mask method makes it difficult to perform microfabrication as used in semiconductor devices, but makes it easy to repeatedly stack simple patterns, and the same mask can be reused. it can.

Further, the greatest advantage of the mask method is that the pattern size on the evaporation source side can be made smaller than that on the side where the shield (mask) is in contact with the substrate, and the substrate and the shield (mask).
The point is that a gap can be provided between the edge. In the photo etching method and the reverse etching method, there is no gap between the substrate and the edge of the shield (resist film),
Sharp cuts occur at the edge of the pattern and the pattern becomes clear. However, since the edge portion is sharply cut, when a film is attached thereon, the problem of step coverage, which is often said in semiconductor elements and the like, occurs. Further, even with the mask method, although there is a slight gap between the adhered substrate and the edge of the shield (resist film), the problem of step coverage at the edge cannot be ignored due to the stacking. Therefore, the mask method is used for the pattern formation, and as described above, the pattern size difference on the evaporation source side is made smaller than that on the side of the shield (mask) in contact with the base, so that the base and the shield (mask).
By providing a gap between the edge and the edge, it is possible to smooth the edge portion of the attached film and at the same time to eliminate the cut. As a result, the problem of electrode connection at the edge and the problem of dielectric breakdown of the dielectric can be almost eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an element cross-sectional view showing the basic structure of the thin film multilayer capacitor of this embodiment. In FIG. 1, reference numeral 1 is a glaze ceramic substrate 2a, 2b, 2 serving as a base.
c and 2d are Al electrodes, and 3a, 3b and 3c are SiO ₂ thin film dielectrics.

Next, a specific manufacturing method will be described with reference to FIG. 2. First, on the previously washed 0.7 mm-thick glaze ceramic substrate 1, the thickness is 0.2 mm. Using a stainless steel vapor deposition mask 4a in which the pattern size on the evaporation source side is 50 μm smaller than the contact side,
Al was sputter-deposited to a film thickness of 0.1 μm to form a lower electrode 2a (FIG. 2A). Next, a mask 4b having a different pattern is used on the upper portion thereof, and similarly, SiO ₂ is used.
The thin film dielectric 3a was 0.2 μm, and the vapor deposition mask 4c was used on the top of the thin film dielectric 3a, and the Al electrode was 0.1 μm, both of which were formed by sputter deposition (FIG. 2 (b),
(C)). At this time, as the vapor deposition masks 4b and 4c, stainless steel vapor deposition masks having a thickness of 0.2 mm as in the vapor deposition mask 4a and having a pattern dimension of 50 μm smaller on the evaporation source side than on the side in contact with the substrate were used. The dimensional difference between the pattern in contact with the substrate and the pattern on the evaporation source side was provided by wet taper etching. Thereafter, in this manner, Al electrodes and SiO ₂ thin film dielectrics were alternately laminated to form a 100-layer thin film multilayer capacitor A.

(Comparative Example 1) As Comparative Example 1, a thin film multilayer capacitor B was prepared in the same manner as in the above Example except that a vapor deposition mask was used in which the pattern on the side of the vapor deposition mask in contact with the substrate and the pattern on the side of the evaporation source were not provided with a dimensional difference. Created.

Comparative Example 2 A thin film multilayer capacitor C was prepared in the same manner as in the above example except that the photo etching method was used as Comparative Example 2. FIG. 3 is an element cross-sectional view showing the basic structure of a thin film multilayer capacitor using this photoetching method. Similar to the thin film multilayer capacitor A, 1 is a glaze ceramic substrate, 2a, 2b, 2c and 2d are Al.
The electrodes 3a, 3b, 3c are SiO ₂ thin film dielectrics.
The resist film used in the photoetching method is a positive resist material (OFPR-80 manufactured by Tokyo Ohka Co., Ltd.).
0), the dry etching method was used for etching.

Each of these multilayer thin film capacitors is 100
When they were created one by one, the yield of electrical inspection was the value shown in (Table 1).

[0022]

[Table 1]

Next, 10 good products of each of the thin film multilayer capacitors A, B and C were put into a withstand voltage (voltage breakdown) measurement, a dielectric loss tangent measurement and a charge / discharge test. The results are shown in (Table 2).

[0024]

[Table 2]

From the above results, the thin film multilayer capacitor produced by using the vapor deposition mask in which the pattern on the side of the vapor deposition mask in contact with the substrate and the pattern on the side of the evaporation source are provided with the dimensional difference has the most excellent characteristics, and the production yield is improved. However, it is clear that it is superior in terms of both electrical characteristics.

In this embodiment, the thickness is 0.2 mm, and the dimension of the pattern on the evaporation source side is 50 μm from the side in contact with the substrate.
A stainless steel vapor deposition mask with a small size was used, but if the thickness is less than 0.05 mm, or if the dimensional difference between the pattern in contact with the substrate and the evaporation source side is less than 20 μm, the substrate and the shield (mask) The effect of providing a gap between the edges disappears, and conversely, when the thickness exceeds 1 mm, or when the dimension difference between the pattern in contact with the substrate and the evaporation source side exceeds 500 μm, fine processing according to the purpose Since it is not possible to provide thin film multilayer capacitors that meet market needs, the thickness of the evaporation mask is 0.05 mm.
It is 1 mm or less, and it is necessary to reduce the dimension of the pattern on the evaporation source side from the side in contact with the substrate within the range of 20 μm to 500 μm.

Although SiO ₂ is used for the dielectric thin film in the explanation of the present invention, similar results can be obtained even if another inorganic thin film dielectric material or organic thin film dielectric material is used. Needless to say.

The electrode material is not limited to Al. Further, in the above-mentioned embodiment, the thin film was formed by the sputtering method, but it goes without saying that similar results can be obtained by other thin film forming methods.

[0029]

As is apparent from the above-described embodiments, the present invention provides a method of forming a dielectric and an electrode on a substrate by alternately stacking at least one layer of the dielectric and the electrode by using a thin film forming means utilizing a dry process. The mask method is used to form the pattern, and different vapor deposition masks are used for the dielectric and the electrodes, and the thickness of each vapor deposition mask is 0.05 mm or more and 1 mm.
It is as follows, and by making the dimensional difference of the pattern on the evaporation source side smaller than that on the side in contact with the substrate within the range of 20 μm or more and 500 μm or less, the edge portion of the attached film can be smoothed and the cut can be eliminated. As a result, the problem of electrode connection at the edge portion and the problem of dielectric breakdown of the dielectric can be almost eliminated, and a small-sized and large-capacity thin film multilayer capacitor can be provided at low cost with high productivity.

[Brief description of drawings]

FIG. 1 is an element cross-sectional view showing the basic structure of a thin film multilayer capacitor in one embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the present embodiment, in which (a) is a process diagram for forming a lower electrode, (b) is a process diagram for forming a thin film dielectric on the lower electrode, and (c) is a process diagram. Process drawing of forming Al electrode on thin film dielectric

FIG. 3 is an element cross-sectional view showing the basic structure of a thin film multilayer capacitor using a photo-etching method of this comparative example.

[Explanation of symbols]

1 ceramic substrate 2 a to 2 d Al electrodes 3 a to 3 c SiO ₂ thin film dielectric 4a~4c deposition mask

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yusuke Takada 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ) Inventor Shinichi Ono 2500 Hagizono, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd. (72) Inventor Yukio Masuda 2500 Hagien, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd.

Claims (2)

[Claims] 1. A mask method is used to form a pattern of the dielectric and the electrode when alternately stacking at least one layer of the dielectric and the electrode by using a thin film forming means utilizing a dry process on the substrate, and A method of manufacturing a thin film multilayer capacitor, wherein different vapor deposition masks are used for a dielectric and an electrode, and each vapor deposition mask has a smaller pattern size on the evaporation source side than on the side in contact with the substrate. 2. The thickness of the vapor deposition mask is 0.05 mm or more 1
2. The method for manufacturing a thin film multilayer capacitor according to claim 1, wherein the dimension difference between the pattern in contact with the substrate and the pattern on the evaporation source side is 20 μm or more and 500 μm or less.