JP2003017366A - Thin film capacitor element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film capacitor element in which a high Q can be realized while preventing short circuit of electrodes surely and limitation on the available substrate is not severe. SOLUTION: A resist pattern 10 is formed on an underlying material 9 formed on the surface of a substrate 1 and after the surface of the underlying material 9 is subjected to electrolytic plating of a conductive material 11, the resist pattern 10 is stripped and unnecessary underlying material 9 is removed thus forming a laminate of the underlying material 9 and the conductive material 11 having a desired shape on the substrate 1. Subsequently, an insulating material 12 is deposited on the substrate 1 to cover the laminate and the conductive material 11 is polished together with the insulating material 12 thus forming first and second electrode parts 2 and 3 and an insulator layer 4 having flattened upper surface on the substrate 1. Thereafter, a dielectric layer 5 is patterned on the upper surface of the first electrode part 2 and the insulator layer 4 and a first upper electrode part 6 being connected with the upper surface of the first electrode part 2 and a second upper electrode part 7 being connected with the upper surface of the second electrode part 3 through the surface of the dielectric layer 5 are formed thus obtaining a thin film capacitor element where the first electrode part 2 faces the second upper electrode 7 through the dielectric layer 5.

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 element used in various small electronic circuits and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 5 is a cross-sectional view of a conventionally known thin film capacitor element. This thin film capacitor element is formed by laminating a lower electrode 101, a dielectric layer 102 and an upper electrode 103 which are sequentially formed on a substrate 100. It has a structure.

The substrate 100 is a glazed alumina substrate in which the entire surface of the alumina 100a is coated with a glass film 100b, and the surface thereof is smoothed by the glass film 100b. The lower electrode 101 is formed by etching Cu or the like formed on the substrate 100 by a sputtering method or a plating method into a desired pattern shape.
A taper is formed at the end portion of 1. Dielectric layer 102
On the substrate 100 and the lower electrode 101 by sputtering or CVD
SiO ₂ formed by using the etching method is etched into a desired pattern shape, and the dielectric layer 1 after patterning
Reference numeral 02 extends to the substrate 100 through the surface of the lower electrode 101 and the tapered surface of the end portion. The upper electrode 103 is the substrate 1
00 and Cu formed on the dielectric layer 102 by a sputtering method or a plating method are etched into a desired pattern shape, and the upper electrode 103 after patterning has a taper on the surface and the end portion of the dielectric layer 102. Substrate 100 through the surface
It extends to the top.

In the thin film capacitor element having such a structure, since the end portion of the lower electrode 101 has a tapered surface, the dielectric layer 102 has a uniform film thickness from the surface of the lower electrode 101 to the substrate 100. Can be formed into
It is possible to prevent a short circuit between the lower electrode 101 and the upper electrode 103.

[0005]

In the conventional thin film capacitor element configured as described above, since the end portion of the lower electrode 101 has a tapered surface, the dielectric layer 102 is formed from the surface of the lower electrode 101 to the substrate 100. It is possible to form a uniform film thickness on the upper side, and it is possible to prevent a short circuit between the lower electrode 101 and the upper electrode 103. However, in order to make the film thickness of the dielectric layer 102 uniform, it is necessary to make the taper angle of the lower electrode 101 as gentle as possible, and there is a problem that such a taper process involves difficulty in the manufacturing process. Further, in order to form such a taper having a gentle inclination angle, it is necessary to set the film thickness of the lower electrode 101 thin, and as a result, there is a problem that the Q value of the capacitor is lowered. Furthermore, since the film thickness of the lower electrode 101 must be reduced, it is necessary to use a glaze alumina substrate having a smooth surface as the substrate 100, and there is a restriction that an inexpensive alumina substrate cannot be used.

The present invention has been made in view of the circumstances of the prior art as described above, and an object of the present invention is to reliably prevent a short circuit of an electrode and realize a high Q value, and to provide a usable substrate. An object is to provide a thin film capacitor element with few restrictions.

[0007]

In order to achieve the above object, in a thin film capacitor element according to the present invention, first and second lower electrodes separated by an insulating layer are formed on a substrate, and at the same time, these insulating layers are formed. The upper surface of the body layer and the first and second lower electrodes are flat surfaces, and the end portion of the dielectric layer formed on the first lower electrode is extended to at least the insulator layer. The upper electrode formed on the second
It is characterized by being laminated on the upper surface of the lower electrode of.

In the thin film capacitor element thus constructed, the upper surfaces of the insulating layer and the first and second lower electrodes are flattened to the same plane, and the flat surface is covered with the dielectric layer. Since the upper electrode is sequentially laminated, the lower electrode can be made thicker and a short circuit between the electrodes can be surely prevented, and an inexpensive alumina substrate can be used.

In the above structure, the capacitance value of the thin film capacitor element is determined by the overlapping range of the first lower electrode and the upper electrode that face each other with the dielectric layer in between. Also, it is preferable to connect the upper electrode.

In order to achieve the above object, in the method of manufacturing a thin film capacitor element according to the present invention, a lower electrode forming step of forming a pair of lower electrodes separated by a gap on a substrate by plating, and the inside of the gap. An insulating layer forming step of forming an insulating layer on the insulating layer, a flattening step of making the upper surfaces of the lower electrodes and the insulating layer flush with each other, and at least the insulating layer from the upper surface of the one lower electrode. And a dielectric layer forming step of forming a dielectric layer on the upper surface of the dielectric layer, and an upper electrode forming step of forming an upper electrode by plating from the upper surface of the dielectric layer to the upper surface of the other lower electrode. .

According to such a structure, by forming the thick film lower electrode by plating, it is possible to realize a lower resistance and a higher Q value of the electrode, and moreover, to form a pair of lower electrodes. The upper surface of the insulator layer is flattened on the same plane, the dielectric layer and the upper electrode are sequentially laminated on the flat surface, and the lower electrode connected to the upper electrode and the lower electrode located directly below the dielectric layer Since and are insulated via the insulator layer, it is possible to reliably prevent a short circuit between the electrodes.

In the above structure, it is preferable that, in the upper electrode forming step, another upper electrode is simultaneously formed on the lower electrode directly below the dielectric layer by plating, in addition to the upper electrode laminated on the dielectric layer. .

Further, in the above structure, in the lower electrode forming step, after forming an underlayer on the substrate, a resist pattern is formed on the surface of the underlayer and a metal material is plated, and then the resist pattern is formed. It is preferable to employ a step of removing the underlying layer exposed by peeling because the lower electrode and the insulating layer having a desired shape can be easily formed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a thin film capacitor element according to an embodiment of the present invention, and FIGS. 2 and 3 are the thin film capacitor. It is explanatory drawing which shows the manufacturing process of an element.

As shown in FIG. 1, the thin film capacitor element according to the present embodiment example includes a first electrode portion 2, a second electrode portion 3 and an insulating layer 4 formed on a substrate 1, and these. It is composed of a dielectric layer 5 formed on a flat upper surface, a first upper electrode 6 and a second upper electrode 7, and the first and second electrode portions 2 and 3 are provided with an underlying layer 8 in between. It is formed on the substrate 1. The first electrode portion 2 and the second electrode portion 3 are separated by the insulator layer 4, and the first upper electrode 6 extends from the first electrode portion 2 to the upper surface of the insulator layer 4 adjacent on the left side thereof. Has been formed. The dielectric layer 5 is formed from the first electrode portion 2 to the upper surface of the insulator layer 4 on the right side of the first electrode portion 2.
The upper electrode 7 is formed from the dielectric layer 5 to the upper surface of the second electrode portion 3. The first electrode portion 2 and the first upper electrode 6 function as the lower electrode of the thin film capacitor element, and the second electrode portion 3 and the second upper electrode 7 function as the upper electrode of the thin film capacitor element. The capacitance value of this thin film capacitor element is defined by the overlapping portion of the first electrode portion 2 and the second upper electrode 7 that face each other with the dielectric layer 5 in between.

A glaze alumina substrate or a glaze-free alumina substrate is used as the substrate 1. Since the alumina substrate having a purity of 99.5% is used in this embodiment, the surface roughness (Ra) of the surface of the substrate 1 is ) Is an uneven surface of about 30 to 100 nm. Cr / Cu, T as the underlayer 8
i / Cu, Cr / Au, Ti / Au, or the like is used, and these materials are formed on the surface of the substrate 1 by sputtering, vapor deposition, ion beam sputtering, or the like. In this case, it is preferable that the thickness of Cr or Ti in the lower layer, which is the adhesion layer to the substrate 1, be 5 to 50 nm, and the thickness of Cu or Au in the upper layer be about 50 to 200 nm.

Cu is used for the first and second electrode portions 2 and 3,
Conductive materials such as Au, Cu / Ni, and Cu / Ni-P are used, and they are formed by electrolytically plating these conductive materials on the surface of the underlayer 8. The base layer 8 and the first and second electrode portions 2 and 3 are formed in the same shape. In this case, after forming a resist pattern of a desired shape on the surface of the base layer 8 formed on the substrate 1, By electroplating the surface of the underlayer 8 with the above-described conductor material, and then removing the resist, the first and second electrode portions 2 and 3 having a desired shape are formed. After the resist is peeled off, the underlying layer 8 covered with the resist pattern is removed by ion milling to form the underlying layer 8 having the same shape as the first and second electrode portions 2 and 3. . Al ₂ is used as the insulator layer 4.
An insulating material such as O ₃ is used. The insulating material is formed on the substrate 1 by sputtering or CVD so as to cover the first and second electrode portions 2 and 3, and then the first and second insulating materials are formed. The surfaces of the electrodes 2 and 3 and the insulating material are CMP (Chemical Mechanical)
It is formed by flattening using the cal polish) method.

SiO is used for the dielectric layer 5._Two, Ta_TwoO₅, A
lSiO_TwoInsulating materials such as
After forming a film by sputtering or CVD method, this is desired
It is formed by patterning into a shape. Than
Specifically, first, disconnect the first and second electrode portions 2 and 3.
SiO on the surface of the edge layer 4_Two, Ta_TwoO₅, AlSiO _Two
After depositing an insulating material such as
By coating and exposing / developing this resist.
A resist pattern having a desired shape is formed. After this, this
In the RIE method using the resist pattern as a mask
CF_FourGas or C_ThreeF₈Or O to them_TwoAdd
The insulating material is etched by using the selected gas, and the
Insulating material outside by ion milling method using Ar gas
The resist pattern and then remove the resist pattern.
For example, the dielectric layer 5 having a desired shape is formed.

The first and second upper electrodes 6 and 7 are formed in the same manner as the first and second electrode portions 2 and 3. That is, a base layer is formed on the surfaces of the first and second electrode portions 2 and 3 including the dielectric layer 5 and the insulator layer 4, and the surface of the base layer has a shape corresponding to both upper electrodes 6 and 7. After forming the resist pattern, Cu, Au, Cu / Ni, C
If a conductive material such as u / Ni-P is electroplated on the surface of the underlayer and then the resist is peeled off and the unnecessary underlayer is removed by the ion milling method, the first and second desired shapes can be obtained.
Upper electrodes 6 and 7 are formed.

Next, the manufacturing process of the thin film capacitor element thus constructed will be described mainly with reference to FIGS.

First, as a lower electrode forming step, FIG.
As shown in (a), Cr / Cu, Ti / C are formed on the surface of the substrate (alumina substrate or glazed alumina substrate) 1.
After forming a base material 9 such as u, Cr / Au, or Ti / Au by a sputtering method, a vapor deposition method, an ion beam sputtering, or the like, as shown in FIG. Exposing the resist to the desired pattern shape
The resist pattern 10 is formed by developing. Next, FIG.
As shown in (c), Cu, Au, Cu / Ni, Cu / is formed on the surface of the base material 9 on which the resist pattern 10 is formed.
A conductor material 11 such as Ni-P is electrolytically plated. The conductor material 11 forms the first and second electrode portions 2 and 3, and the film thickness thereof is determined by the circuit design.
A film thickness of about 5 to 5.0 μm is preferable. Next, FIG.
After removing the resist pattern 10 as shown in FIG. 2D, as shown in FIG.
When the r ion is incident at an angle of 0 to 30 degrees and the base material 9 exposed by peeling the resist pattern 10 is removed, a base layer 8 having the same shape as the first and second electrode portions 2 and 3 is formed. .

Next, as an insulating layer forming step, FIG.
As shown in (a), an insulating material 12 such as Al ₂ O ₃ is formed on the substrate 1 by a sputtering method or a CVD method, the conductor material 11 is completely covered with the insulating material 12, and then a flattening treatment is performed. In the process, the conductor material 11 and the insulating material 12 are commercialized.
The P method is used to polish to the position indicated by the broken line in FIG. As a result, the upper surfaces of the conductor material 11 and the insulating material 12 are flattened on the same plane, and as shown in FIG. 3B, the first and second electrode portions 2 having the flattened upper surfaces on the substrate 1 are formed. 3 and the insulator layer 4 are formed.

Next, as a dielectric layer forming step, an insulating material such as SiO ₂ , Ta ₂ O ₅ or AlSiO ₂ is formed on the surfaces of the flattened first and second electrode portions 2 and 3 and the insulating layer 4. 3 is formed by sputtering and then patterned into a desired shape by using a photolithography technique.
As shown in (c), the dielectric layer 5 is formed on the upper surfaces of the first electrode portion 2 and the insulating layer 4. Although the dielectric layer 5 needs to be formed at least from the upper surface of the first electrode portion 2 to the upper surface of the insulator layer 4, the dielectric layer 5 extends beyond the insulator layer 4 to the second surface.
It may be extended to the upper surface of the electrode part 3.

Next, as an upper electrode forming step, FIG.
As shown in (d), the first upper electrode 6 connected to the upper surface of the first electrode portion 2 and the second upper electrode 6 connected to the upper surface of the second electrode portion 3 through the surface of the dielectric layer 5. The upper electrode 7 is formed. Since the upper electrode forming process is the same as the lower electrode forming process described above, detailed description thereof is omitted here.

As described above, in the thin film capacitor element according to the present embodiment, the first electrode portion 2 and the second electrode portion 3 which are thick films are formed by plating, and the lower electrode of the thin film capacitor element is formed into the first electrode portion. 1 has a two-layer structure of the electrode portion 2 and the first upper electrode 6, and the upper electrode of the thin film capacitor element also has a two-layer structure of the second electrode portion 3 and the second upper electrode 7. And high Q value can be realized. Also, the first
The upper surfaces of the second electrode portions 2 and 3 and the insulating layer 4 are flattened on the same plane, and the dielectric layer 5 and the second upper electrode 7 are sequentially laminated on the flat surface and the dielectric layer is formed. Since the first electrode portion 2 located immediately below 5 and the second electrode portion 3 connected to the second upper electrode 7 are insulated via the insulator layer 4, It is possible to surely prevent a short circuit between the lower electrodes.

In the embodiment described above, the first upper electrode 6 is formed so as to partially overlap the lead-out portion of the first electrode portion 2, but the second electrode portion 3 is formed.
Similarly to the connection structure between the first upper electrode 6 and the second upper electrode 7, the first upper electrode 6 may be formed so as to completely overlap with the first electrode portion 2. Resistance and high Q value can be further promoted.

FIG. 4 is a cross-sectional view showing an application example to an electronic circuit board, and this electronic circuit board is used as various high frequency devices. As shown in the figure, thin film circuit elements such as a thin film capacitor element 20, a thin film resistance element 30, and a thin film inductor element 40 are formed on a substrate 1 of this electronic circuit board.
0, 30, 40 are the substrate 1 depending on the required circuit configuration.
Many are formed in the upper effective area. Since the thin film capacitor element 20 has the same configuration as that of the above-described embodiment, duplicate description will be omitted here.

The thin film resistance element 30 includes a heat sink portion 31 formed on the substrate 1, a pair of electrode portions 32, an insulating layer 33, and an insulating film 3 sequentially laminated on the flat upper surfaces thereof.
4 and the resistance film 35 and the protection film 36,
The heat sink portion 31 and the pair of electrode portions 32 are made of an insulating layer 33.
Are separated by. The heat sink portion 31 and the pair of electrode portions 32 serve as the first and second electrodes of the thin film capacitor element 20.
The electrode parts 2 and 3 are made of the same material and are formed in the same step. The insulator layer 33 is made of the same material as the insulator layer 4 of the thin film capacitor element 20, and these are also formed in the same process. The insulating film 34 covers the upper surface of the heat sink portion 31 and extends to the insulating layers 33 on both sides thereof,
The insulating film 34 is made of AlSiO, AlSiN, AlSiO.
It is formed by forming a film of an insulating material such as N, AlN, Al ₂ O ₃ , or SiO ₂ by a sputtering method, a CVD method, or the like, and then patterning this into a desired shape. Resistive film 3
Reference numeral 5 covers the insulating film 34 and extends to the upper surfaces of the pair of electrode portions 32. This resistance film 35 is formed by forming a resistance material such as TaN or TaSiO by a sputtering method or the like and then patterning it into a desired shape. Formed by. The protective film 36 covers the resistance film 35. The protective film 36 is formed of an organic insulating material such as polyimide or resist, or SiO ₂ ,
It is formed by forming a film of an inorganic insulating material such as Al ₂ O ₃ by a sputtering method or the like and then patterning this into a desired shape.

The thin film inductor element 40 includes a conductor layer 41 and an insulator layer 42 formed on the substrate 1, an insulating layer 43 formed on the flat upper surfaces of the conductor layer 41 and the insulator layer 42, and a conductor. The inner electrode 44 extending from the upper surface of the inner end portion of the layer 41 to the outside through the insulating layer 43, and the conductor layer 41.
And an outer electrode 45 that is routed from the upper surface of the outer end of the conductive layer 41 over the insulating layer 43, and the conductor layer 41 is formed in a spiral shape in plan view. The conductor layer 41 is made of the same material as the electrode portions 2 and 3 of the thin film capacitor element 20, the heat sink portion 31 and the electrode portions 32 of the thin film resistance element 30,
These are formed in the same process. The insulator layer 42 is made of the same material as the insulator layer 4 of the thin film capacitor element 20 and the insulator layer 33 of the thin film resistance element 30, and these are also formed in the same process. The insulating layer 43 is made of AlSiO ₂ , SiO ₂ , T
Inorganic insulating material such as a ₂ O _{5 is} used for the conductor layer 41 and the insulator layer 4.
The insulating layer 43 after patterning is formed by depositing a film on the substrate 2 by a sputtering method or the like and then patterning it into a desired shape, or by forming an organic insulating material such as a resist by a photolithography technique and curing it at a high temperature. Has a shape exposing the upper surface of the inner end portion and the upper surface of the outer end portion of the conductor layer 41.
The inner electrode 44 and the outer electrode 45 are made of Cu, Cu / Ni, Cu
/ Ni-P, Cu / Ni / Au, Cu / Ni-P / A
It is made of a conductor material such as u or Au, and is formed by electrolytically plating these conductor materials on the surface of the insulating layer 43 in the same process as the conductor layer 41.

In the electronic circuit board thus constructed, the first and second electrode portions 2 and 3 of the thin film capacitor element 20, the heat sink portion 31 of the thin film resistance element 30, both electrode portions 32 and the insulator layer. 33, the conductor layer 41 and the insulator layer 42 of the thin film inductor element 40, and the lower electrode forming step shown in FIG. 2A to FIG.
Since the insulating layer forming step shown in (a) and the flattening step shown in FIG. 3 (b) can be formed in the same process, the manufacturing process of the electronic circuit board can be simplified. Further, since the resistance film 35 of the thin film resistance element 30 is formed on the flat surfaces of the heat sink portion 31, both electrode portions 32 and the insulator layer 33 with the insulating film 34 interposed therebetween, the thick film heat sink portion 31 is formed by plating. By forming both the electrode portions 32 and, it is possible to reduce the resistance of the electrodes, reduce the variation in the resistance value due to the unevenness of the resistance film forming surface, and heat generated from the resistance film 35 can be reduced. The heat sink 31 directly below can efficiently dissipate heat. Furthermore, the insulating layer 43 of the thin film inductor element 40 and the inner electrode 4
Since No. 4 is laminated on the upper surfaces of the conductor layer 41 and the insulator layer 42 that have been flattened, it is possible to realize a high Q value by forming the thick conductor layer 41 by plating. In addition, the manufacturing process of the insulating layer 43, the inner electrode 44, and the outer electrode 45 can be simplified.

[0031]

The present invention is carried out in the form as described above, and has the following effects.

By forming a thick film lower electrode on the substrate by plating, lower resistance and higher Q value of the electrode can be realized, and moreover, a pair of lower electrode and the upper surface of the insulating layer are formed. Is planarized on the same plane, and the dielectric layer and the upper electrode are sequentially laminated on these flat surfaces, so that it is possible to reliably prevent a short circuit between the electrodes and use an inexpensive alumina substrate. Will also be possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thin film capacitor element according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of the thin film capacitor element.

FIG. 3 is an explanatory view showing a manufacturing process of the thin film capacitor element.

FIG. 4 is a cross-sectional view of an electronic circuit board to which the present invention has been applied.

FIG. 5 is a cross-sectional view of a thin film capacitor element according to a conventional example.

[Explanation of symbols]

1 substrate 2 First electrode part 3 Second electrode part 3 4 Insulator layer 5 Dielectric layer 6 First upper electrode 7 Second upper electrode 8 Underlayer 9 Base material 10 Resist pattern 11 Conductor material 12 Insulation material 20 Thin film capacitor element 30 Thin film resistance element 40 Thin film inductor element

Claims (5)

[Claims] 1. A first lower electrode and a second lower electrode which are separated by an insulating layer are formed on a substrate, and the upper surfaces of the insulating layer and the first lower electrode are made flat. The end portion of the dielectric layer formed on the first lower electrode extends to at least the insulator layer, and the upper electrode formed on the dielectric layer is laminated on the upper surface of the second lower electrode. Thin film capacitor element. 2. The thin film capacitor element according to claim 1, wherein another upper electrode is laminated on the upper surface of the first lower electrode. 3. A lower electrode forming step of forming a pair of lower electrodes separated by a gap on a substrate by plating, an insulating layer forming step of forming an insulating layer inside the gap, and both lower electrodes. And a flattening treatment step for making the upper surface of the insulator layer flush with each other; a dielectric layer forming step for forming a dielectric layer from the upper surface of the one lower electrode to at least the upper surface of the insulator layer; An upper electrode forming step of forming an upper electrode by plating from the upper surface of the layer to the upper surface of the other lower electrode. 4. The method according to claim 3, wherein the upper electrode forming step includes a step of simultaneously forming the upper electrode and another upper electrode stacked on the upper surface of the one lower electrode by plating. And a method for manufacturing a thin film capacitor element. 5. The method according to claim 3 or 4, wherein in the lower electrode forming step, after forming an underlayer on the substrate, a resist pattern is formed on a surface of the underlayer and a metal material is plated, Then, the method of manufacturing a thin film capacitor element, which comprises a step of removing the exposed underlayer by peeling the resist pattern.