JP7019969B2 - Thin film capacitor - Google Patents

Description

The present invention relates to a thin film capacitor.

As an electronic component used in an electronic device, for example, Patent Document 1 discloses a thin film capacitor in which a capacitive portion including a dielectric thin film is formed on a substrate.

Japanese Unexamined Patent Publication No. 2007-81325

However, the thin film capacitor described in Patent Document 1 has a limit in reducing ESL (equivalent series inductance) due to the shape of the internal wiring.

The present invention has been made in view of the above, and an object of the present invention is to provide a thin film capacitor having a low ESL.

In order to achieve the above object, the thin film capacitor according to one embodiment of the present invention is laminated on the lower electrode layer, the dielectric layer laminated on a part of the lower electrode layer, and the dielectric layer. The lower electrode layer has a formed upper electrode layer, the lower electrode layer, the dielectric layer, and an insulating layer laminated on the upper electrode layer, and the lower electrode layer has a region in which the dielectric layer is not laminated. The first via conductor, which is divided into a plurality of terminal portions including the terminal portion including the terminal portion and is formed in an opening penetrating the insulating layer formed in the insulating layer on the upper electrode layer, and the lower electrode layer. A second via conductor formed in an opening penetrating the insulating layer formed in the insulating layer on a region where the dielectric layer is not laminated, and the first via conductor and the second via on the insulating layer. It has a connecting conductor that connects to and a conductor, and a conductor portion that has.

According to the above-mentioned thin film capacitor, when a current is passed through the capacitor portion including the lower electrode layer, the upper electrode layer and the dielectric layer, the first via conductor and the second via conductor of the conductor portion are formed in the insulating layer. The directions of the currents flowing between them are opposite to each other. Therefore, it is possible to cancel the increase in ESL due to the flow of current in each of the first via conductor and the second via conductor in and around the insulating layer, so that low ESL can be realized.

Here, it is possible to further have a protective layer made of an insulating material laminated on the insulating layer and the conductor portion.

As described above, a protective layer made of an insulating material is provided on the insulating layer and the conductor portion. With such a configuration, it is possible to prevent the conductor portion from being damaged on the upper surface of the insulating layer.

According to the present invention, a thin film capacitor with low ESL is provided.

It is sectional drawing which shows a part of the thin film capacitor which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the thin film capacitor shown in FIG. It is a figure for demonstrating the manufacturing method of the thin film capacitor shown in FIG.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a cross-sectional view schematically showing a part of a thin film capacitor according to an embodiment of the present invention. As shown in FIG. 1, the thin film capacitor 1 has a lower electrode layer 11, an upper electrode layer 12, a dielectric layer 13, an insulating layer 14, a conductor portion 15, and a protective layer 16. The dielectric layer 13 is laminated on the lower electrode layer 11, and the upper electrode layer 12 is laminated on the dielectric layer 13, whereby these form the capacitance portion 10 of the thin film capacitor 1.

In the present specification, the "lamination direction" is from the lower electrode layer 11 to the protective layer 16 such as the lower electrode layer 11, the dielectric layer 13, the upper electrode layer 12, the insulating layer 14, and the protective layer 16. In this direction, the layers are sequentially overlapped. Further, in the following description, the protective layer 16 side may be described as "upper" along the stacking direction, and the lower electrode layer 11 side may be described as "lower" along the stacking direction.

The capacitive portion 10 has a lower electrode layer 11 and an upper electrode layer 12, which are a pair of electrode layers provided along the stacking direction, and a dielectric layer 13 sandwiched between the pair of electrode layers. In the present embodiment, the case where the capacitive portion 10 has a single-layer structure having two electrode layers and one dielectric layer 13 will be described, but the capacitive portion 10 has a dielectric layer 13 on the lower electrode layer 11. And the internal electrode layer (not shown) may be alternately laminated, and the upper electrode layer 12 may be laminated on the uppermost dielectric layer.

The lower electrode layer 11 forming the lowermost layer of the thin film capacitor 1 is formed of a conductive material. Specifically, a material containing nickel (Ni) or copper (Cu) as a main component is preferably used as the lower electrode layer 11, and Ni is particularly preferably used. The term "main component" means that the proportion of the component is 50% by mass or more. When the main component of the lower electrode layer 11 is Ni, platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), ruthenium (Ru), osmium (Os), rhenium (Re), It further contains at least one selected from the group consisting of tungsten (W), chromium (Cr), tantalum (Ta), and silver (Ag) (hereinafter referred to as "additive element").

The lower electrode layer 11 is divided into a first terminal portion 11A and a second terminal portion 11B as a plurality of terminal portions. The first terminal portion 11A includes a region on which the dielectric layer 13 is not laminated on the upper surface, and this region is a region for electrically connecting to the upper electrode layer 12 as described later. An example is shown in which the second terminal portion 11B also includes a region in which the dielectric layer 13 is not laminated on the upper surface, but even if the dielectric layer 13 is laminated on the entire upper surface of the second terminal portion 11B. good. An insulating material 18 is filled between the first terminal portion 11A and the second terminal portion 11B, and the two are insulated from each other. The first terminal portion 11A and the second terminal portion 11B may be insulated from each other, and the insulating material 18 may not be provided between them. The thickness of the lower electrode layer 11 is, for example, about 300 nm to 10 μm.

The upper electrode layer 12 is formed of a conductive material. Specifically, a material containing nickel (Ni) or platinum (Pt) as a main component is preferably used as the upper electrode layer 12, and Ni is particularly preferably used. When the main component of the upper electrode layer 12 is Ni, an additive element may be further contained as in the lower electrode layer 11. Since the upper electrode layer 12 contains an additive element, interruption of the upper electrode layer 12 can be suppressed. The upper electrode layer 12 may contain a plurality of additive elements. The thickness of the upper electrode layer 12 is, for example, about 10 nm to 1000 nm.

The dielectric layer 13 is laminated on the lower electrode layer 11 and sandwiched between the lower electrode layer 11 and the upper electrode layer 12. The dielectric layer 13 is not laminated on the entire surface of the lower electrode layer 11, but at least a part of the upper surface of the first terminal portion 11A is exposed (the dielectric layer 13 is not laminated in the region). It is laminated on a part of the lower electrode layer 11 so as to be in a state). However, it is preferable that the area covering the upper surface of the second terminal portion 11B is large, and such a configuration can improve the function as the capacitance portion 10.

The dielectric layer 13 is made of a perovskite-based dielectric material. Examples of the perovskite-based dielectric material in the present embodiment include BaTiO ₃ (barium titanate), (Ba _1-X Sr _X ) TiO ₃ (barium titanate strontium), (Ba _1-X Ca _X ) TiO ₃ , and PbTIO. _3. A (ferroelectric) dielectric material having a perovskite structure such as Pb (Zr _X Ti _1-X ) O ₃ or a composite perovskite relaxer type represented by Pb (Mg _1/3 Nb _2/3 ) O ₃ or the like. Ferroelectric materials, bismuth layered compounds typified by Bi ₄ Ti ₃ O ₁₂ , SrBi ₂ Ta ₂ O ₉ , etc., represented by (Sr _1-X Ba _X ) Nb ₂ O ₆ , Pb Nb ₂ O ₆ and the like. It is composed of a tungsten bronze type ferroelectric material and the like. Here, in the perovskite structure, the perovskite relaxer type ferroelectric material, the bismuth layered compound, and the tungsten bronze type ferroelectric material, the A-site to B-site ratio is usually an integer ratio, but is intentionally for improving the characteristics. It may be deviated from the integer ratio. In addition, in order to control the characteristics of the dielectric layer 13, an additive substance may be appropriately contained as an auxiliary component in the dielectric layer 13. In addition, in order to control the characteristics of the dielectric layer 13, an additive substance may be appropriately contained as an auxiliary component in the dielectric layer 13. The thickness of the dielectric layer 13 is, for example, 10 nm to 1000 nm.

The insulating layer 14 is laminated so as to cover the upper surfaces of the lower electrode layer 11, the dielectric layer 13, and the upper electrode layer 12. The insulating layer 14 has an opening 14a penetrating from the upper surface thereof to the upper surface of the upper electrode layer 12, and an opening 14b penetrating from the upper surface thereof to the upper surface of the first terminal portion 11A of the lower electrode layer 11. The thickness of the insulating layer 14 is, for example, about 300 nm to 10 μm.

The conductor portion 15 is provided on the upper surface of the insulating layer 14 and in the openings 14a and 14b. In the opening 14a, the conductor portion 15 is a first via conductor 15a in contact with the upper electrode layer 12a. Further, in the opening 14b, the conductor portion 15 is a second via conductor 15b in contact with the first terminal portion 11A. The first via conductor 15a in the opening 14a and the second via conductor 15b in the opening 14b are connected by a connecting conductor 15c formed on the insulating layer 14. That is, the conductor portion 15 functions as a conductor wiring connecting the upper electrode layer 12a and the first terminal portion 11A. The conductor portion 15 is formed of a conductive material. Specifically, a material containing nickel (Ni) or copper (Cu) as a main component is preferably used as the conductor portion 15, and Cu is particularly preferably used. The thickness of the conductor portion 15 is, for example, about 1 μm to 5 μm. The distance between the first via conductor 15a and the second via conductor 15b (horizontal length orthogonal to the stacking direction: corresponding to the length of the connecting conductor 15c) is, for example, about 10 μm to 100 μm. It is in a state of being placed close to each other. With such a configuration, low ESL can be realized. This point will be described later.

The protective layer 16 is laminated so as to cover the upper surfaces of the insulating layer 14 and the conductor portion 15. Further, the protective layer 16 is introduced into the openings 14a and 14b so as to fill the openings 14a and 14b provided in the insulating layer 14. Therefore, the first via conductor 15a and the second via conductor 15b extend along the inner surfaces of the openings 14a and 14b, and the protective layer 16 is provided on the upper surface side (inner surface side).

The insulating layer 14 and the protective layer 16 are not particularly limited as long as they are insulating materials, but for example, a non-conductive resin such as polyimide, glass (SiO ₂ ), alumina (Al ₂ O ₃ ), and silicon knight. An inorganic material such as ride (SiN) or an insulating material obtained by mixing or laminating these can be used, but a resin material is preferably used. The thickness of each of the insulating layer 14 and the protective layer 16 is, for example, 0.5 μm or more and 10 μm or less.

In the thin film capacitor 1 described above, the upper electrode layer 12 and the first terminal portion 11A of the lower electrode layer 11 are electrically connected by the conductor portion 15. Therefore, when a current is passed through the first terminal portion 11A and the second terminal portion 11B as terminal electrodes, the upper electrode layer 12, the dielectric layer 13, and the second terminal portion 11B function as capacitors. Therefore, the larger the area in which the dielectric layer 13 and the second terminal portion 11B are in contact with each other, the larger the capacity of the capacitor can be.

In the thin film capacitor 1 described above, it is assumed that a current is passed from the first terminal portion 11A to the second terminal portion 11B. In this case, a current flows from the lower side to the upper side of the second via conductor 15b in the conductor portion 15. On the other hand, a current flows from above to below in the first via conductor 15a of the conductor portions 15. That is, the directions of the currents flowing through the two first via conductors 15a and the second via conductors 15b arranged in close proximity to each other are opposite to each other. Therefore, low ESL can be realized.

Next, a method for manufacturing the thin film capacitor 1 will be described with reference to FIGS. 2 and 3. 2 and 3 are diagrams for explaining a method of manufacturing the thin film capacitor shown in FIG. 1. Note that FIGS. 2 and 3 show an enlarged part of the thin film capacitor 1 in the middle of manufacturing. Actually, after forming a plurality of thin film capacitors 1 at a time, they are separated into individual thin film capacitors 1.

First, as shown in FIG. 2A, the lower electrode layer 11 is prepared, and the dielectric layer 13 and the upper electrode layer 12 are laminated on the upper surface thereof. As a method for laminating the dielectric layer 13, a film forming technique such as a solution method, a PVD (Physical Vapor Deposition) method such as sputtering, or a CVD (Chemical Vapor Deposition) method can be used. Further, as a method for laminating the upper electrode layer 12, for example, DC sputtering or the like can be mentioned. However, the laminating method is not particularly limited. Further, firing may be performed at the time of forming the dielectric layer 13.

Next, as shown in FIG. 2B, the insulating layer 14 is laminated so as to cover the upper surfaces of the lower electrode layer 11, the dielectric layer 13, and the upper electrode layer 12. As a method for forming the insulating layer 14, a film forming technique such as a solution method, a PVD (Physical Vapor Deposition) method such as sputtering, or a CVD (Chemical Vapor Deposition) method can be used. After that, openings 14a and 14b are formed in the insulating layer 14. The openings 14a and 14b are formed by dry etching using, for example, a patterned resist as a mask. At the opening 14a, the upper surface of the upper electrode layer 12 is exposed on the bottom surface, and the side surface formed by the insulating layer 14 is formed. At the opening 14b, the upper surface of the lower electrode layer 11 is exposed on the bottom surface, and the side surface formed by the insulating layer 14 is formed. The region exposed on the bottom surface of the opening 14b is the region on the upper surface of the first terminal portion 11A (see FIG. 1).

Next, as shown in FIG. 2 (c), the conductor portion 15 is formed. The conductor portion 15 is formed by sputtering or vapor-depositing a conductive material such as copper (Cu) and then patterning by etching. By this step, the conductor portion 15 including the first via conductor 15a, the second via conductor 15b, and the connecting conductor 15c is formed. The first via conductor 15a and the second via conductor 15b may be formed so that at least the lower electrode layer 11 and the upper electrode layer 12 are connected to each other, and cover all the bottom surfaces and side surfaces of the openings 14a and 14b. It does not have to be formed as such. Further, the first via conductor 15a and the second via conductor 15b may be formed so as to completely fill the openings 14a and 14b.

Next, as shown in FIG. 3A, the protective layer 16 is laminated so as to cover the upper surfaces of the insulating layer 14 and the conductor portion 15 (connecting conductor 15c). As a method for forming the protective layer 16, a film forming technique such as a solution method, a PVD (Physical Vapor Deposition) method such as sputtering, or a CVD (Chemical Vapor Deposition) method can be used. The protective layer 16 is also formed so as to be filled in the openings 14a and 14b of the insulating layer 14.

Next, as shown in FIG. 3B, the lower electrode layer 11 is divided into a first terminal portion 11A and a second terminal portion 11B. Examples of the method for dividing the lower electrode layer 11 include laser processing and the like, but the method is not particularly limited. After that, the region 11c formed between the first terminal portion 11A and the second terminal portion 11B is filled with the insulating material 18 (see FIG. 1) and individualized by dicing or the like, as shown in FIG. The thin film capacitor 1 is obtained.

Here, in the thin film capacitor 1 according to the present embodiment, the lower electrode layer 11 is divided into a plurality of portions, and the upper electrode layer 12 and the first of the lower electrode layers 11 divided into a plurality of portions by the conductor portion 15 are used. The terminal portion 11A is electrically connected to the terminal portion 11A. Therefore, in the thin film capacitor 1, the first terminal portion 11A and the second terminal portion 11B of the lower electrode layer 11 can be used as terminal electrodes for the capacitance portion 10. Further, by configuring the upper electrode layer 12 and the first terminal portion 11A of the lower electrode layer 11 to be electrically connected in this way, it is possible to prevent a short circuit or the like when the thin film capacitor 1 is separated into individual pieces. Can be done. Specifically, in the conventional thin film capacitor configuration, when the thin film capacitor 1 is individualized by dicing or the like, the wiring on the lower electrode layer 11 and the upper electrode layer 12 side (in the thin film capacitor 1 of the present embodiment). There was a possibility of short-circuiting with the conductor portion 15). On the other hand, in the thin film capacitor 1 according to the present embodiment, since the conductor portion 15 and the lower electrode layer 11 (first terminal portion 11A) are electrically connected, the risk of a short circuit can be avoided. .. Therefore, the yield of the thin film capacitor 1 can be improved.

Further, in the insulating layer 14, the directions of the currents flowing between the first via conductor 15a and the second via conductor 15b of the conductor portion 15 are opposite to each other. Therefore, it is possible to cancel the increase in ESL due to the current flowing in each of the first via conductor 15a and the second via conductor 15b in and around the insulating layer 14, so that low ESL can be realized. In order to achieve the above-mentioned low ESL, it is preferable that the via conductors are close to each other to such an extent that the ESLs can cancel each other out. Specifically, the distance between the first via conductor 15a and the second via conductor 15b (horizontal length orthogonal to the stacking direction: corresponding to the length of the connecting conductor 15c) is, for example, about 10 μm to 100 μm. If this is the case, the effect of lowering the ESL is enhanced.

Further, the thin film capacitor 1 is provided with a protective layer 16 made of an insulating material on the upper surfaces of the insulating layer 14 and the conductor portion 15. With such a configuration, it is possible to prevent the conductor portion 15 on the upper surface side from being damaged.

In the present embodiment, the case where the dielectric layer 13 of the capacitance portion 10 of the thin film capacitor 1 is a single layer structure has been described, but a so-called multilayer structure having a plurality of dielectric layers 13 may be used. In that case, an internal electrode layer is provided between the plurality of dielectric layers 13. When the capacitance portion 10 has one or more internal electrode layers, the lower electrode layer 11 is further divided according to the number of internal electrode layers, and the terminal portion and the internal electrode layer formed from the divided lower electrode layer 11 are further divided. By further providing the conductor wiring for individually connecting the two, the terminal can be provided on the lower electrode layer 11 side as in the thin film capacitor 1 described in the present embodiment. Further, the newly provided conductor wiring includes a via conductor formed in the two openings provided in the insulating layer 14 and a connecting conductor connecting the two via conductors, similarly to the conductor portion 15. Although it will be configured, the directions of the currents flowing through the two via conductors can be reversed from each other. Therefore, similar to the thin film capacitor 1, it is possible to realize low ESL around the conductor portion.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

For example, in the above embodiment, the case where the dielectric layer 13 is also laminated on the first terminal portion 11A of the lower electrode layer 11 which does not function as a capacitor has been described. However, the dielectric layer 13 may be provided at least on the second terminal portion 11B, and may not be provided on the first terminal portion 11A.

1 ... Thin film capacitor, 10 ... Capacitance part, 11 ... Lower electrode layer, 11A ... First terminal part, 11B ... Second terminal part, 12 ... Upper electrode layer, 13 ... Dielectric layer, 14 ... Insulation layer, 15 ... Conductor Part, 15a ... 1st via conductor, 15b ... 2nd via conductor, 15c ... connecting conductor, 16 ... protective layer.

Claims (1)

With the lower electrode layer,
A dielectric layer laminated on a part of the lower electrode layer and
The upper electrode layer laminated on the dielectric layer and
The lower electrode layer, the dielectric layer, and the insulating layer laminated on the upper electrode layer,
Have,
The lower electrode layer is divided into a plurality of terminal portions including a terminal portion having a region in which the dielectric layer is not laminated.
The first via conductor formed in the insulating layer on the upper electrode layer and connected to the upper electrode layer at the opening penetrating the insulating layer, and the dielectric layer among the lower electrode layers In the opening formed in the insulating layer on the non-stacked region and penetrating the insulating layer, in the terminal portion having the region in which the dielectric layer is not laminated among the plurality of terminal portions of the lower electrode layer. On the other hand, a conductor portion including a second via conductor formed so as to connect in the region and a connecting conductor connecting the first via conductor and the second via conductor on the insulating layer.
A protective layer made of an insulating material laminated on the insulating layer and the conductor portion , and
Further has a thin film capacitor.

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