JP3750324B2 - Device having thin film multilayer electrode and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an element having a thin film multilayer electrode mainly used in a high frequency region and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, as electronic components have been miniaturized, devices have been miniaturized by using high dielectric constant materials even in high frequency bands such as microwaves, quasi-millimeter waves, and millimeter waves. However, when the shape is reduced by using a high dielectric constant material, there is a problem in that energy loss increases in inverse proportion to the cubic root of the volume. The energy loss of this high-frequency device can be broadly classified into conductor loss due to the skin effect and dielectric loss due to the dielectric material. In recent years, dielectric materials having low loss characteristics even with high dielectric constants. Therefore, the conductor loss dominates the energy loss rather than the dielectric loss.
[0003]
Under the circumstances as described above, the present applicant disclosed in International Application Publication No. WO95 / 06336 that a thin film conductor layer, a thin film dielectric layer, and a thin film dielectric layer are formed on a dielectric substrate as electrodes capable of reducing conductor loss in a high frequency band. A thin film multi-layer electrode was proposed, which was constructed by alternately laminating layers through adhesive layers. The thin film multilayer electrode proposed here is assumed to be formed on a dielectric substrate having a flat surface (a sapphire substrate made of a single crystal of alumina subjected to mirror polishing is exemplified). Each film thickness of the thin film conductor layer and the thin film dielectric layer is set as follows.
[0004]
[Problems to be solved by the invention]
However, for example, when a ceramic substrate is used as the dielectric substrate, the substrate surface usually has irregularities due to the presence of pores or the like. The unevenness can be flattened to some extent by surface polishing or the like. However, since there are a large number of pores not only on the substrate surface but also on the inside of the substrate, a new pore becomes apparent on the surface by the polishing process, and the substrate surface cannot be sufficiently flattened. Here, FIG. 3 shows a cross-sectional view showing a film structure when a thin film multilayer electrode is formed on a dielectric substrate having a pore. As shown in FIG. 3, the thin film conductor layer 35 and the thin film dielectric layer 36 are laminated on the dielectric substrate 32 to form the thin film multilayer electrode 34. The thin film conductor layer 35 and the thin film dielectric layer 36 are Corrugations corresponding to the pores 37 of the substrate 32 are provided. If each layer is formed with irregularities in this way, the low-loss operation as originally designed cannot be realized. Further, when a thin film is laminated on a substrate having a pore, there is a very high possibility that adjacent thin film conductor layers are short-circuited in the film formation process. Any of these situations greatly deteriorates the skin effect suppression effect of the thin-film multilayer electrode.
[0005]
In response to such a problem, the applicant of the present application disclosed in Japanese Patent Application No. 8-140056 and Japanese Patent Application No. 9-288748 is a flattening for flattening the irregularities of the substrate between the dielectric substrate and the thin film multilayer electrode. A method of interposing a film was proposed to solve these problems.
[0006]
However, even if these methods are used, the following new problems have occurred. That is, in forming the planarizing film, as shown in FIGS. 4A to 4D, the planarizing film 33 is formed on the dielectric substrate 32 until the surface of the planarizing film 33 becomes flat by a technique such as sputtering. The thin film multilayer electrode 34 was formed after that. For this reason, it takes a long time to complete the formation of the planarizing film 33 and is not suitable for mass production. Further, since the planarizing film 33 is thick, there is a problem that the influence on the electrical characteristics of the thin film multilayer electrode 34 formed thereon is increased.
[0007]
Accordingly, an object of the present invention is to solve the above technical problems, and to provide an element having a thin film multilayer electrode having a structure that is not easily affected by unevenness of a substrate, and a method for manufacturing the same. There is.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in an element having a thin film multilayer electrode of the present invention, a thin film in which a dielectric substrate and thin film conductor layers and thin film dielectric layers are alternately laminated on the dielectric substrate via an adhesive layer An element having a thin film multilayer electrode comprising a multilayer electrode and a planarization film interposed between the dielectric substrate and the thin film multilayer electrode, the surface of the planarization film in contact with the thin film multilayer electrode, A polishing process is performed to flatten the surface.
[0009]
In this way, the planarization film interposed between the dielectric substrate and the thin film multilayer electrode is removed by actively removing the portion of the planarization film that does not contribute to the planarization of the substrate by polishing the planarization film. The thickness of the chemical film can be reduced. As a result, the influence of the planarizing film on the thin film multilayer electrode can be kept low. Further, since the surface is flattened by polishing processing unlike the conventional case, it is not necessary to continue film formation until the surface is flattened, and the film formation time can be shortened.
[0010]
The planarizing film is made of Ti, Ta, W, Cr, Zr, Nb, Hf, V, Mo, Ti—N, Ta—N, or a material obtained by mixing two or more of these, or added to these. Use materials with added ingredients .
This is because these materials are easily bonded to the dielectric substrate and the thin film conductor layer constituting the thin film multilayer electrode, and the adhesion between the dielectric substrate and the thin film multilayer electrode can be increased by the adhesive action.
These materials are also used for adhesion between the thin-film conductor layer and the thin-film dielectric layer constituting the thin-film multilayer electrode, so that the materials used can be shared and the efficiency of film formation can be improved.
[0011]
The method for manufacturing an element having a thin film multilayer electrode according to the present invention comprises a thin film multilayer electrode comprising a thin film multilayer electrode in which thin film conductor layers and thin film dielectric layers are alternately laminated on a dielectric substrate via an adhesive layer. In a method for manufacturing an element having an electrode, a step of preparing a dielectric substrate, and a planarizing film for planarizing unevenness of the substrate surface on the surface of the dielectric substrate are made of Ti, Ta, W, Cr, Zr, Nb, Hf. , V, Mo, Ti—N, Ta—N, a process obtained by using a material obtained by mixing two or more of these, or a material obtained by adding an additive to these, and the surface of the planarizing film is flat The removal process which removes an unnecessary part so that it may become, and the process of forming a thin film multilayer electrode on the planarization film | membrane after a removal process.
[0012]
The removing step preferably includes a step of performing a polishing process so that the surface roughness Ra of the planarizing film is 0.05 μm or less in order to stably operate the thin-film multilayer electrode with low loss.
[0013]
In particular, when a polishing method such as surface grinding or buffing is used, the surface of the planarizing film may be oxidized during the polishing process to become a work-affected layer, resulting in deterioration of conductivity. Therefore, it is desirable to remove the work-affected layer by wet etching or the like.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
[First embodiment, FIGS. 1 to 2]
An element 1 having a thin film multilayer electrode of the first embodiment is shown in FIG. FIG. 1 is a cross-sectional view of the element 1, in which a planarizing film 3 and a thin film multilayer electrode 4 are formed on a dielectric substrate 2. The dielectric substrate 2 has pores 7, but the surface of the dielectric substrate 2 is planarized by the planarization film 3. A thin film multilayer electrode 4 is formed on the planarizing film 3 by alternately laminating thin film conductor layers 5 and thin film dielectric layers 6. Each layer constituting the thin film multilayer electrode 4 is formed flat without being affected by the pore 7.
[0016]
Next, a method for manufacturing the element 1 of this example will be described with reference to FIGS.
[0017]
First, a dielectric substrate 2 is prepared, and a planarizing film 3 made of Ti is formed on the substrate by sputtering. The flattening film 3 is formed thicker than the portion where the recessed portion of the pore 7 is sufficiently filled (FIGS. 2A and 2B). Next, an unnecessary portion of the planarizing film 3 formed thicker than necessary (that is, a portion of the planarizing film that does not contribute to planarization of the dielectric substrate) is removed by polishing (FIG. 2C). )). Then, the thin-film multilayer electrode 4 is formed on the planarized film 3 subjected to the polishing process based on a predetermined thickness design value (FIG. 2D). The element 1 is manufactured as described above.
[0018]
By the way, the reason why Ti is used as the material of the planarizing film 3 in this embodiment is that Ti has high adhesion to both the dielectric substrate 2 made of SiO2 and the like and the thin film conductor layer 5 made of Cu and the like. It is. By using such a highly adhesive material, it is possible to effectively suppress film peeling caused by deterioration with time and difference in thermal expansion coefficient. Materials having high adhesion to both the dielectric substrate 2 and the thin film conductor layer 5 include Ta, W, Cr, Zr, Nb, Hf, V, Mo, Ti—N, and Ta—N in addition to Ti. Alternatively, a material obtained by mixing two or more of these, or a material obtained by adding an additive to these may be considered. In many cases, these materials are interposed as an adhesive layer between the thin-film conductor layer 5 and the thin-film dielectric layer 6 constituting the thin-film multilayer electrode 4, but the material of the adhesive layer and the flattening film is formed. It is preferable to make it common in order to improve efficiency.
[0019]
Although the material suitable for the planarization film has been described above, the present invention is not limited to this, and various known materials can be used as long as the material can be used for film formation. For example, Cu to be used as a thin film conductor layer, Ag, Au, and _{Al, SiO 2, Al 2 O} 3 used superconductors as represented by Y-Ba-Cu-O, also as a thin film dielectric layer, Si ₃ N ₄ , Ta ₂ O ₅ or the like can be used.
[0020]
In the present embodiment, the sputtering method is used to form the planarizing film 3 because the film thickness required for planarizing the pores can be relatively thin. Thereby, the film formation time can be shortened and the time required for the polishing process can be shortened at the same time. Further, since the thin film multilayer electrode 4 formed on the planarizing film 3 is usually formed by sputtering, the film forming method can be shared. However, the film forming method is not limited to this, and various film forming methods such as vacuum film forming methods such as vapor deposition and MO-CVD, printing and baking methods, electrolytic plating methods and electroless plating methods should be used. Can do.
[0021]
Further, as a specific method for polishing the planarizing film 3 of this embodiment, various polishing methods such as surface grinding, buff polishing, milling from an oblique direction, and wet etching can be used. Note that when the polishing process is performed so that the surface roughness Ra of the planarizing film is 0.05 μm or less, the thin film multilayer electrode 4 initially forms the thin film conductor layer 5 and the thin film dielectric layer 6 constituting the thin film multilayer electrode 4. It has been confirmed that it can be formed flat enough to stably operate with low loss as designed.
[0022]
[Second Embodiment]
The element having the thin film multilayer electrode according to the second embodiment of the present invention is characterized in that after the unnecessary portion of the flattening film is removed by the polishing process, the work-affected layer described below is further removed by wet etching.
[0023]
That is, when a polishing process is performed by a physical grinding method such as surface grinding or buffing, generally, the polishing surface becomes relatively high due to friction, or the surface to be polished is washed with water during the polishing process. Under such circumstances, the polishing surface is very easily oxidized, but if the polishing surface is oxidized, the conductivity of the planarizing film 3 is deteriorated, and the characteristics of the thin film multilayer electrode formed thereon are adversely affected. Effect. Further, when the polished surface is oxidized, the adhesiveness of the planarizing film 3 is deteriorated, so that the effect of suppressing the film peeling of the planarizing film 3 cannot be realized sufficiently.
[0024]
Therefore, the work-affected layer, that is, the oxide layer formed on the surface of the flattening film, was removed again by wet etching that can remove the oxide layer while maintaining the surface roughness of the surface of the flattening film 3 at a desired value. Is.
[0025]
In other respects, the structure and manufacturing method of the element are the same as those of the element 1 of the first embodiment, and the description thereof is omitted.
[0026]
【The invention's effect】
As is clear from the above description, the following excellent effects can be obtained by the element having the thin film multilayer electrode of the present invention and the method for manufacturing the same.
[0027]
That is, the planarization film interposed between the dielectric substrate and the thin-film multilayer electrode is removed by applying a polishing process to the planarization film and actively removing the portion of the planarization film that does not contribute to the planarization of the substrate. The film thickness can be reduced. As a result, the influence of the planarizing film on the characteristics of the thin-film multilayer electrode can be kept low. Also, unlike the conventional case, since the surface is flattened by the polishing process, it is sufficient to form the film until the pores are filled, and it is not necessary to continue the film formation until the flattened film surface is completely flattened. Shortening can be achieved.
[0028]
Further, Ti, Ta, W, Cr, Zr, Nb, Hf, V, Mo, Ti-N, Ta-N, or a material obtained by mixing two or more of these, or additives to the planarizing film By using this material, the adhesion between the dielectric substrate and the thin film multilayer electrode can be increased by the adhesive action, and the film peeling caused by the deterioration with time and the difference in thermal expansion coefficient can be effectively suppressed. Can do. These materials are also used for adhesion between the thin-film conductor layer and the thin-film dielectric layer constituting the thin-film multilayer electrode, so that the materials used can be shared and the efficiency of film formation can be improved.
[0029]
Furthermore, by removing the work-affected layer generated on the surface layer of the planarizing film in the removing step by wet etching, the conductivity and adhesion of the planarizing film can be kept good.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an element having a thin film multilayer electrode according to a first embodiment of the present invention. FIGS. 2 (a) to (d) are diagrams showing a method for manufacturing the element.
FIG. 3 is a cross-sectional view of a device having a thin film multilayer electrode of a conventional example.
FIGS. 4A to 4D are diagrams showing a method for manufacturing a thin film multilayer electrode of a different conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 31 ... Element 2 which has a thin film multilayer electrode, 32 ... Dielectric substrate 3, 33 ... Planarization film 4, 34 ... Thin film multilayer electrode 5, 35 ... Thin film conductor layer 6, 36: Thin film dielectric layers 7, 37: Pore

Claims (4)

A dielectric substrate, a thin film multilayer electrode in which thin film conductor layers and thin film dielectric layers are alternately laminated on the dielectric substrate via an adhesive layer, and planarization interposed between the dielectric substrate and the thin film multilayer electrode An element having a thin film multilayer electrode comprising a film,
A surface of the flattening film in contact with the thin film multilayer electrode is subjected to a polishing process for flattening the surface , and the flattening film includes Ti, Ta, W, Cr, Zr, Nb, Hf, An element having a thin-film multilayer electrode, characterized by comprising V, Mo, Ti—N, Ta—N, a material obtained by mixing two or more of these, or a material obtained by adding an additive thereto . In a method for manufacturing an element having a thin film multilayer electrode formed by forming a thin film multilayer electrode in which thin film conductor layers and thin film dielectric layers are alternately laminated on a dielectric substrate,
Preparing a dielectric substrate; and
A flattening film for flattening the unevenness of the substrate surface on the surface of the dielectric substrate is Ti, Ta, W, Cr, Zr, Nb, Hf, V, Mo, Ti-N, Ta-N, or two of these. A step of using a material obtained by mixing the above, or a material obtained by adding an additive to these, and
A removal step of removing unnecessary portions so that the surface of the planarization film becomes flat;
And a step of forming a thin film multilayer electrode on the planarized film after the removing step. A method of manufacturing an element having a thin film multilayer electrode. 3. The method of manufacturing an element having a thin film multilayer electrode according to claim 2 , wherein the removing step includes a step of removing the work-affected layer generated on the surface layer of the planarizing film by wet etching. Said removing step includes elements having a thin-film multilayer electrode according to claim 2 or claim 3 surface roughness Ra of the flattening film is characterized in that it comprises a step of performing polishing processing so as to 0.05μm or less Manufacturing method.

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