JP2017199706A - Thin-film capacitor material and method of manufacturing thin-film capacitor material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such as oxidization of a lower part electrode of a thin-film capacitor material and deterioration of dielectric characteristics due to heat treatment.SOLUTION: A method of manufacturing a thin-film capacitor material includes: a step (1) of manufacturing a nickel foil with an NiAl film by forming a predetermined NiAl film in a predetermined nickel foil as a second conductive material; a step (2) of forming a dielectric film on the surface of the NiAl film by performing heat treatment at least under a non-oxidizing atmosphere and at a temperature of 900°C or more and 1400°C or less; and a step (3) of forming a first conductive material on the surface of the dielectric film.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a thin film capacitor material and a method of manufacturing the thin film capacitor material, and more specifically, a dielectric film is provided between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode. In the thin film capacitor material, as the second conductive material constituting the lower electrode, an inexpensive nickel foil is used in place of the conventionally expensive platinum group material, and at that time, for the crystallization of the dielectric film The present invention relates to a thin film capacitor material capable of solving problems such as oxidation of a lower electrode due to high temperature heat treatment and deterioration of dielectric characteristics due to heat treatment, and a method for manufacturing the thin film capacitor material.

  In recent years, as materials for devices such as microsensors and microactuators and thin film capacitors, a conductive material constituting the lower electrode, a dielectric film, and a conductive material constituting the upper electrode are sequentially formed on a substrate made of silicon, glass or ceramics. Then, attempts to use a multilayer substrate obtained by patterning by an etching method or the like have been actively made.

As the dielectric film used for the member, a film having a perovskite structure such as Pb (Zr, Ti), BaTiO ₃ or the like is used. As the film forming method, a sputtering method, a sol-gel method, an MOCVD method, and the like have been put into practical use. When forming a Pb (Zr, Ti) (PZT) film or a BaTiO ₃ (BT) film by these methods, in order to obtain a high dielectric constant, the formed substrate is heated to about 600 to 1000 ° C., It is essential to crystallize the dielectric film. However, when exposed to such a high temperature in an atmosphere containing oxygen, the conductive material constituting the lower electrode (hereinafter sometimes referred to as the lower conductive material) reacts with components in the oxide or dielectric. Thus, there arises a problem that the dielectric characteristics are greatly deteriorated.

In order to suppress such a phenomenon, as a lower electrode, a Pt film is formed on a laminated substrate represented by Si / SiO ₂ / TiO ₂ having a structure in which a SiO ₂ film and a TiO ₂ film are laminated on a silicon substrate. In general, a multilayer substrate which is formed as a lower conductor and which is stable even at a high temperature is used. For example, in a substrate configuration in which a capacitive element is formed on an interlayer insulating film formed on a substrate, as the capacitive element, a capacitive insulating film made of SBT (SrTaBiO) is formed on a Pt lower conductive material. Discloses a dielectric capacitor made of a laminate of Pt films, which is a conductive material constituting the upper electrode (hereinafter sometimes referred to as an upper conductive material) (see, for example, Patent Document 1).

By the way, when manufacturing the multilayer substrate as described above, the production of the Si / SiO ₂ / TiO ₂ laminated substrate has many steps and is expensive because it uses a silicon substrate and a Pt film. It was a big problem.

As a solution to this problem, a cost-effective substrate has been studied in place of the silicon substrate, but there is a problem to be solved. For example, in a synthetic SiO ₂ substrate, heat resistance and cracking due to thermal shock are problematic. In addition, with ceramic substrates such as Al ₂ O ₃ , it is generally difficult to make the substrate surface completely non-porous and easily cause defects in the film. In addition, when a metal material such as stainless steel is used as the substrate or the lower conductive material, when the dielectric film is heat-treated in an atmosphere containing oxygen, the substrate is oxidized and a reaction occurs at the substrate / dielectric interface, resulting in dielectric characteristics. There is a problem that gets worse.

  On the other hand, it has been studied to select a dielectric film together with the substrate to prevent deterioration of dielectric characteristics. For example, when a nickel foil or nickel alloy foil is used for the lower electrode material and a Pb, La (Zr, Ti) film is used for the dielectric film (see, for example, Patent Document 2), the dielectric film is crystallized. Therefore, it is possible to prevent oxidation of the lower electrode material and deterioration of the dielectric characteristics. However, this method has a problem that the dielectric film is limited. That is, when a BT film is used as the dielectric film, the heat treatment temperature necessary for the crystallization is usually 700 to 1000 ° C., and the dielectric properties are not improved at 600 ° C. or lower. Here, if heat treatment is performed at a temperature of 700 to 1000 ° C., the surface of the nickel foil is oxidized in an instant, and the effect as a conductive material cannot be exhibited.

  Further, the nickel foil has a problem. For example, the surface of a normal nickel foil obtained by a rolling method often has a maximum surface roughness (Rmax) of 1 μm or more. Therefore, when a dielectric film is laminated on a nickel foil with a thickness of about 400 nm, Since the unevenness of the foil is large, a portion where the dielectric film is not attached is likely to occur, which causes deterioration of the dielectric characteristics.

  Accordingly, a nickel foil having a thickness of 10 to 500 μm, a surface resistance value of 0.1 to 1Ω, and a maximum surface roughness (Rmax) of 100 to 700 nm is used, and a dielectric is formed on the surface under specific heat treatment conditions. There is a method for forming a film and further forming a first conductive material on the surface thereof to solve problems such as oxidation of the lower electrode by heat treatment for crystallization of the dielectric film and deterioration of dielectric characteristics by heat treatment. It has been proposed (see Patent Document 3). However, since the firing temperature cannot be raised to prevent oxidation of the Ni foil, the dielectric characteristics may be lowered, and there is room for improvement.

  As another means, an attempt has been made to use a conductive oxide for the conductive material of the lower electrode so that the problem of oxidation of the conductive material is solved even if heat treatment is performed at a high temperature in an oxygen atmosphere ( For example, see Patent Document 4.) Since this conductive oxide is not affected by oxygen in the atmosphere, the reaction with the dielectric film does not occur even when heat treatment is performed at a high temperature. However, since the conductive oxide to be used uses a platinum group element, the problem of high cost remains. In addition, since the conductive oxide is difficult to sinter, it is difficult to use the conductive oxide after forming it into a substrate shape. Therefore, since it is formed by film formation by sputtering or the like, combined use with a silicon substrate, a ceramic substrate or the like is inevitable.

  In MLCC, it is studied to form an electrode by sintering a paste material of NiAl intermetallic compound as an internal electrode in order to improve oxidation resistance (for example, Patent Document 5). However, since NiAl intermetallic compounds lack ductility, it is difficult to produce a foil by rolling or the like, and it is difficult to produce a smooth and self-supporting film by firing a paste material.

  From the above situation, a heat treatment for crystallization of a dielectric film in a thin film capacitor material having a dielectric film between the first conductive material constituting the upper electrode and the second conductive material constituting the lower electrode There is a need to solve problems such as oxidation of the lower electrode due to, and deterioration of dielectric properties due to heat treatment.

Japanese Patent Laid-Open No. 2004-040005 JP 2006-135036 A JP 2009-295907 A JP 2003-174150 A JP 2012-195557 A

R.A. Mahesh et al., Materials Chemistry and Physics, 114, (2009), 629

  An object of the present invention is to provide a thin film capacitor material having a dielectric film between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode in view of the above-mentioned problems of the prior art. As the second conductive material constituting the lower electrode, an electrode in which a NiAl film is formed on a predetermined nickel foil is used instead of the conventional platinum group material, which is expensive, and the dielectric film is crystallized. An object of the present invention is to provide a method of manufacturing a thin film capacitor material that can eliminate problems such as oxidation of the lower electrode by heat treatment and deterioration of dielectric characteristics by heat treatment.

  In order to achieve the above object, the present inventors have provided a method for manufacturing a thin film capacitor material having a dielectric film between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode. As a result of extensive research, a nickel foil with NiAl film having specific characteristics was prepared as the second conductive material, and a dielectric film was formed on the surface under specific heat treatment conditions. When the first conductive material was formed on the substrate, it was found that problems such as oxidation of the lower electrode due to heat treatment for crystallization of the dielectric film and deterioration of dielectric properties due to heat treatment could be solved, and the present invention was completed. did.

That is, according to the first aspect of the present invention, there is provided a method for manufacturing a thin film capacitor material having a dielectric film between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode. There,
A method for producing a thin film capacitor material comprising the following steps (1) to (3) is provided.
Step (1): On the surface of the nickel foil having a surface having a maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less as the second conductive material, the Ni composition is 65 mass% or more and 73 mass% or less, and the balance is Al. A nickel foil with a NiAl film on which a NiAl film having a composition is formed is manufactured.
Step (2): A dielectric film is formed on the surface of the NiAl film by performing heat treatment at least at a temperature of 900 ° C. or higher and 1400 ° C. or lower in a non-oxidizing atmosphere.
Step (3): A first conductive material is formed on the surface of the dielectric film.

According to a second aspect of the present invention, there is provided the method for producing a thin film capacitor material according to claim 1, wherein in the first aspect, the step (1) includes the following steps. .
Step: Select a NiAl film having a surface resistance value of 0.01Ω or more and 1Ω or less after forming the NiAl film.

According to a third aspect of the present invention, there is provided a method for manufacturing a thin film capacitor material, wherein in the first aspect or the second aspect, the step (2) includes the following steps.
Process: After the film formation of the following steps (a) to (c) is repeated a plurality of times on the surface of the NiAl film, a third heat treatment is performed at a temperature of 900 ° C. to 1400 ° C. in a non-oxidizing atmosphere. To form a dielectric film.
(A) A dielectric film precursor solution is applied.
(B) Next, it is subjected to a first heat treatment in which heating is performed at a temperature of 300 ° C. or higher and 350 ° C. or lower in an oxidizing atmosphere.
(C) Subsequently, a second heat treatment is performed by heating at a temperature of 450 ° C. or higher and 950 ° C. or lower in an oxidizing atmosphere.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the method further comprises the following step (4) following step (3): A method of manufacturing a thin film capacitor material is provided.
Step (4): A fourth heat treatment is performed in an atmosphere containing oxygen.

  According to a fifth aspect of the present invention, the thin film capacitor material according to any one of the first to fourth aspects, wherein the nickel foil is produced by electroforming. A manufacturing method is provided.

  According to the sixth aspect of the present invention, in any one of the first to fifth aspects, the dielectric precursor solution is 1-butanol, 1-pentanol, 3methyl-1 At least one alcohol selected from the group consisting of butanol, 2-methyl-1-butanol, 2-methyl-2-butanol, and 2-methyl-1-propanol, butyl acetate, propyl acetate, isopentyl acetate, and butyl butyrate At least one ester selected from the group consisting of Ba, Sr, Mg, and Ca in a mixed solvent consisting of at least one ester selected from the group consisting of carboxylic acid that is 2-ethylhexanoic acid A thin film obtained by adding a metal element and at least one metal element selected from the group consisting of Ti, Sn, and Zr Method for producing Yapashita material is provided.

  According to the seventh aspect of the present invention, in the sixth aspect, the mixing ratio of the mixed solvent is such that the alcohols: esters: carboxylic acid has a volume ratio of 2: 2: 1 to 2: 1: 1. A method for producing a thin film capacitor material is provided.

According to the eighth aspect of the present invention, in any one of the first to seventh aspects, the dielectric film has a unit capacitance of 1.9 μF / cm ² or more. A method for manufacturing a thin film capacitor material is provided.

According to the ninth aspect of the present invention, in any one of the first to eighth aspects, the current is measured when the DC voltage is changed from -3V to 3V, and the maximum current is measured. A thin film capacitor material manufacturing method is provided, in which a leakage current represented by a value obtained by dividing the above by an electrode area is 5 nA / cm ² or less.

  According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the thickness of the nickel foil is 10 μm or more and 500 μm or less. A manufacturing method is provided.

  According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the temperature of the third heat treatment in the step (2) is a non-oxidizing atmosphere and the temperature is There is provided a method for producing a thin film capacitor material, wherein the heat treatment performed at 900 ° C. or higher and 1400 ° C. or lower is performed in a carbon container.

  According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the thickness of the dielectric film is not less than 100 nm and not more than 500 nm. A method of manufacturing the material is provided.

  According to a thirteenth aspect of the present invention, in any one of the first to twelfth aspects, the method for producing a thin film capacitor material is characterized in that the NiAl film is formed by sputtering. Is provided.

According to a fourteenth aspect of the present invention, there is provided a thin film capacitor material comprising a dielectric film between the first conductive material constituting the upper electrode and the second conductive material constituting the lower electrode, The two conductive materials have a nickel foil having a surface with a maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less, laminated on the surface, a Ni composition of 65 mass% or more and 73 mass% or less, and the balance is Al. A nickel foil with a NiAl film having a surface resistance on the NiAl film side of 0.1Ω or more and 1Ω or less, a unit capacitance of 1.9 μF / cm ² or more, and a DC voltage of − Provided is a thin film capacitor material characterized by measuring a current when applied by changing from 3 V to 3 V and having a leakage current represented by a value obtained by dividing a maximum current by an electrode area of 5 nA / cm ² or less. .

  The method of manufacturing a thin film capacitor material according to the present invention comprises forming a lower electrode in a thin film capacitor material having a dielectric film between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode. As the second conductive material, a nickel foil with a NiAl alloy film is used instead of the conventionally expensive platinum group material, and at this time, oxidation of the lower electrode by heat treatment for crystallization of the dielectric film, and Problems such as deterioration of dielectric properties due to heat treatment can be solved, and a thin film capacitor material having excellent unit capacitance of the dielectric film and a small leakage current can be obtained. Therefore, its industrial value is extremely large.

It is sectional drawing which shows an example of the thin film capacitor material which concerns on embodiment. It is a flowchart of the manufacturing method which concerns on embodiment. FIG. 3 is a flowchart of the manufacturing method following FIG. 2. It is explanatory drawing of the manufacturing method which concerns on embodiment. FIG. 5 is an explanatory diagram of the manufacturing method according to the embodiment, following FIG. 4.

  The present invention will be described below with reference to the drawings. However, the present invention is not limited to this. Further, in the drawings, in order to describe the embodiment, the scale is appropriately changed and expressed by partially enlarging or emphasizing the description.

  The manufacturing method of the thin film capacitor material and the thin film capacitor material of the present invention will be described in detail. In describing the thin film capacitor material manufacturing method (hereinafter simply referred to as “manufacturing method”) and the thin film capacitor material, FIGS. FIG. 1 is a cross-sectional view illustrating an example of the thin film capacitor material according to the embodiment. 2 and 3 are flowcharts of the manufacturing method. 4 and 5 are explanatory diagrams of the manufacturing method, respectively.

  Hereinafter, the thin film capacitor material MC will be described based on the present manufacturing method. This manufacturing method is a method for manufacturing the thin film capacitor material MC shown as an example in FIG. The thin film capacitor material MC includes a dielectric film 3 between the first conductive material 1 constituting the upper electrode and the second conductive material 2 constituting the lower electrode.

As shown in FIG.1 and FIG.2, this manufacturing method is characterized by including the following process (1)-(3).
Step (1) (Step S1): As the second conductive material 2, the Ni composition is 65% by mass or more and 73% on the surface 4a of the nickel foil 4 having the surface 4a whose maximum surface roughness (Rmax) is 1 nm or more and 20 nm or less. The NiAl film-attached nickel foil 2 is manufactured by forming the NiAl film 5 having a composition of Al or less and the balance being Al.
Step (2) (Step S2): The dielectric film 3 is formed on the surface of the NiAl film 5 by performing heat treatment at least at a temperature of 900 ° C. or higher and 1400 ° C. or lower in a non-oxidizing atmosphere.
Step (3) (Step S3): The first conductive material 1 is formed on the surface of the dielectric film 3.

  In the present invention, the nickel foil 4 having the specific thickness and having the specific maximum surface roughness (Rmax) is used as the second conductive material in the step (1), and the dielectric in the step (2). It is important to optimize the heat treatment conditions when forming the film. Thus, even when an inexpensive nickel foil 4 is used as the second conductive material 2 constituting the lower electrode instead of the conventional platinum group material, which is expensive, a heat treatment for crystallization of the dielectric film 3 is performed. Thus, problems such as oxidation of the lower electrode 2 due to heat treatment and deterioration of dielectric characteristics due to heat treatment can be solved, and a thin film capacitor material MC excellent in unit capacitance of the dielectric film 3 can be obtained. Moreover, a practical capacitor is required to have a small leakage current. According to this manufacturing method, the thin film capacitor material MC having a small leakage current can be manufactured.

Below, each process is demonstrated.
[Step (1)]
Step (1) manufactures the second conductive material 2 (step S1 shown in FIG. 2). In step (1), for example, in step S11, as shown in FIG. 4A, first, a nickel foil 4 having a surface 4a having a maximum surface roughness (Rmax) of 1 nm to 20 nm is prepared. In the nickel foil 4 of the present embodiment, for example, the upper surface corresponds to the surface 4a. In this specification, “maximum surface roughness (Rmax)” means a value based on JIS B 0601-1994. In this specification, “Maximum surface roughness (Rmax)” is measured by measuring the three-dimensional shape of five 20 μm square regions on the material surface using an atomic force microscope (AFM), and is attached to the AFM. It is the value calculated | required by statistically processing the measured value of the height direction (thickness direction) obtained by measurement using the software to do. Note that the nickel foil 4 does not have to be all surfaces 4a. For example, the nickel foil 4 only needs to have the surface 4a in a portion where the dielectric film 3 to be described later is formed, but it is preferable that one whole surface of the nickel foil 4 is the surface 4a.

  As the nickel foil 4, it is essential to use a nickel foil having a surface 4a having a maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less. Thereby, the uniformity of the NiAl film 5 formed on the nickel foil 4 and the uniformity of the dielectric film 3 formed on the NiAl film 5 are maintained, and the deterioration of the dielectric characteristics due to the inhibition of film formation can be prevented. it can. That is, when the surface of a nickel foil obtained by a commercially available rolling method is observed with an atomic force microscope (AFM), for example, the maximum surface roughness is often 1 μm or more. When the NiAl film 5 or the dielectric film 3 is laminated with a thickness of 100 nm, the portion on which the film is not formed is generated due to the unevenness on the surface of the nickel foil 4, and the dielectric characteristics are deteriorated. In addition, when the maximum surface roughness of the nickel foil 4 is less than 1 nm, it becomes difficult to manufacture the nickel foil 4 because it is difficult to manage the polishing state of the glass substrate used for the manufacture of the nickel foil 4 and the electroforming bath. In addition, when the maximum surface roughness of the nickel foil 4 exceeds 20 nm, for example, when the thickness of the dielectric film 3 is 100 nm or less, the NiAl film 5 and the dielectric film 3 may be broken, which is not preferable.

  Moreover, the thickness T1 of the nickel foil 4 is, for example, not less than 10 μm and not more than 500 μm. In order to give the second conductive material 2 the role of a base material (film support), since the strength is low in ordinary pure nickel foil, for example, when the precursor solution of the dielectric film 3 is applied, etc. Is difficult to handle. Therefore, the thickness T1 of the nickel foil 4 is preferably 10 μm or more. On the other hand, when the thickness T1 of the nickel foil 4 exceeds 500 μm, practicality (eg, dielectric characteristics) as a thin film capacitor is impaired, which is not preferable.

  Moreover, as the said nickel foil 4, the commercially available nickel foil prepared by predetermined thickness by the electroforming method, the rolling method, the electrolysis method etc. is used, for example. Among these, it is preferable to use a nickel foil obtained by electroforming. This is because the electroforming method is particularly excellent in controlling the surface roughness of the nickel foil as compared with the electrolytic method and the rolling method. Note that the surface roughness of the nickel foil by electroforming is determined by the surface roughness of the substrate used during electroforming. For example, the nickel foil 4 having a maximum surface roughness of 20 nm or less can be produced by using polished glass for the substrate used during electroforming. Moreover, although the purity of the nickel foil 4 is not specifically limited, For example, 99% or more is preferable and 3N (99.9%) or more is more preferable from a viewpoint of electrical conduction characteristics.

  Here, the relationship between the surface resistance value of nickel foil 4 and the oxidation state and their temperature will be described. When the nickel foil 4 is heated to 500 ° C. or higher in an atmosphere containing oxygen, the surface resistance value is deteriorated and the dielectric characteristics are greatly affected. For example, the surface resistance value after holding the nickel foil 4 having a surface resistance value of 0.2Ω in the atmosphere at a temperature of 600 ° C. for 30 minutes deteriorates to 20Ω, which is 100 times the original value. When the surface of the nickel foil 4 at this time is X-ray diffracted, the formation of NiO is confirmed. If a nickel foil having a nickel oxide film is heat-treated at a higher temperature, a reaction with the dielectric film 3 occurs, and the dielectric characteristics are greatly deteriorated.

  However, in order to obtain desired dielectric characteristics in the subsequent heat treatment, it is not possible to perform all heat treatments from a low temperature in a non-oxidizing atmosphere under conditions that suppress oxidation. That is, when the dielectric film 3 is formed by applying the precursor solution on the second conductive material 2, it is necessary to perform calcination and main firing. Here, the calcination and the main baking decompose the organic components remaining in the dielectric film 3 from the precursor solution, and the precursor solution becomes a complete oxide form. In order to actively decompose this organic component, an atmosphere containing oxygen is required, and for example, it is desirable to perform the treatment at a temperature of at least 500 ° C.

  Therefore, the inventors of the present application have studied the oxidation prevention on the surface of the nickel foil 4 and formed a NiAl film 5 on the surface of the nickel foil 4 to dramatically improve the oxidation resistance on the surface of the nickel foil 4. I found it. NiAl intermetallic compounds are known to exhibit excellent oxidation resistance. For example, even a thin film produced by sputtering is known to withstand heat treatment at 900 to 1000 ° C. (for example, RA Mahesh et al. Materials Chemistry and Physics, 114, (2009), 629). In this manufacturing method, by using a nickel foil having a NiAl intermetallic compound formed on the surface (nickel foil 2 with a NiAl film), the oxidation resistance of the surface of the nickel foil 4 is drastically improved. Heat treatment can be performed up to about 950 ° C.

  In this manufacturing method, in step S12 shown in FIG. 2, a NiAl film 5 is formed on the surface 4a of the nickel foil 4 as shown in FIG. 4B. Thereby, nickel foil 2 with NiAl film (second conductive material 2) is manufactured. As a result, it is possible to suppress a decrease in dielectric characteristics between the second conductive material 2 (nickel foil 4) and the dielectric film 3 caused by oxidation of the nickel foil 4 by heat treatment performed later. As shown in FIG. 4B, the NiAl film 5 is preferably formed on the entire upper surface of the surface 4a of the nickel foil 4, but is not limited to this. For example, the upper surface of the surface 4a of the nickel foil 4 is used. A NiAl film 5 may be formed on at least a part of the film.

The NiAl film 5 has a composition in which the Ni composition is 65 mass% or more and 73 mass% or less and the balance is Al with respect to the total mass of the NiAl film 5. When the NiAl film 5 is processed at a high temperature, if the Ni composition is less than 65% by mass, the Al phase is not preferable. If the Ni composition exceeds 73% by mass, the Ni phase is not preferable. The method for forming the NiAl film 5 is not particularly limited. For example, it is preferable to form the NiAl film 5 by DC sputtering using a NiAl alloy target. In this case, for example, a film having excellent uniformity can be formed. The NiAl alloy target is not particularly limited. For example, NiAl or a mixture of Ni and Al ₃ Ni ₂ powders having a predetermined composition and produced by a hot press method can be used. The thickness T2 of the NiAl film 5 is preferably 0.05 μm or more and 1 μm or less, for example, from the viewpoints of dielectric properties, oxidation prevention of the nickel foil 4, and the like.

  By the way, a good electrode film needs to have a low electric resistance. If an oxide film (oxide film) is formed, the resistance increases. For this reason, it is necessary to always monitor the formation of the oxide film. As one means for that purpose, the surface resistance value on the NiAl film 5 side of the nickel foil 2 with the NiAl film is monitored, and the surface resistance value is 0.1Ω or more and 1Ω or less.

  In this manufacturing method, for example, after the nickel foil 2 with NiAl film 2 is manufactured in step S12 shown in FIG. 2, the surface resistance value on the NiAl film 5 side of the nickel foil 2 with NiAl film is 0.01Ω or more and 1Ω in step S13. The NiAl film-coated nickel foil 2 is selected as follows. As a result, it is possible to eliminate the nickel foil 2 with the NiAl film in which the oxide film is frequently formed, and as a result, it is possible to more reliably obtain a thin film capacitor material having a superior unit capacitance of the dielectric film and a low leakage current. be able to. For example, step S13 can be performed by measuring the surface resistance value of the NiAl film 5 using a known device capable of measuring the resistance value. In the present specification, the “surface resistance value” is a value measured with a tester by contacting two terminals determined to have a width of 1 cm. The nickel foil 2 with the NiAl film having the above characteristics can be suitably used as the second conductive material 2 (electrode) for the thin film capacitor material MC. Whether or not step S13 is performed is arbitrary, and step S13 may not be performed.

[Step (2)]
Following step (1) shown in FIG. 2, dielectric film 3 is formed on the surface of second conductive material 2 in step S2 (step (2)). In step (2), first, for example, in step S21, the dielectric precursor film 6 is formed on the surface of the NiAl film 5 as shown in FIG. 4C or FIG. The dielectric precursor film 6 can be formed by a known film forming method such as a coating / firing method, a sputtering method, a sol-gel method, an MOCVD method, or a laser ablation method. The film thickness of the dielectric precursor film 6 is set so as to be, for example, about 100 nm or more and 500 nm or less, after the heat treatment in step S22 shown in FIG. In this case, the dielectric characteristics can be made more stable.

  Subsequently, in step S22 of FIG. 2, heat treatment is performed in a non-oxidizing atmosphere and at a temperature of 900 ° C. or higher and 1400 ° C. or lower. Thereby, as shown in FIG. 5, the dielectric film 3 is formed on the surface of the NiAl film 5. In addition, the time of the heat treatment in step S22 can be performed, for example, for about 30 minutes to 120 minutes. The non-oxidizing atmosphere can be formed by using, for example, an inert gas. The amount (flow rate) of the inert gas is not particularly limited. For example, it is preferable to flow the inert gas into the furnace at a flow rate of 0.5 L / min or more and 5 L / min or less. The inert gas is not particularly limited as long as it is an inert gas. For example, when the inert gas uses nitrogen gas, it is preferable because it is inexpensive and easy to handle. Further, the non-oxidizing atmosphere in the heat treatment in step S22 may be formed in a vacuum state. For example, when the heat treatment in step S22 is performed under vacuum, for example, it is preferable to perform evacuation to 0.1 Pa or more, preferably 0.01 Pa or less as an atmosphere having non-oxidizing characteristics.

Hereinafter, as an example of a method for forming the dielectric precursor film 6, a method for forming the dielectric precursor film 6 by a coating / firing method will be described. When the dielectric precursor film 6 is formed by a coating / firing method, for example, in steps S23 to S25 shown in FIG. 3, as shown in FIG. 4C, on the surface of the NiAl film 5, the following ( After forming the film 6 (dielectric precursor film 6) a plurality of times by repeating the procedures (i) to (c) (the procedure from step S23 to step S25), the temperature is 900 ° C. or higher and 1400 ° C. or lower in a non-oxidizing atmosphere. The dielectric film 3 is formed by performing a third heat treatment (step S26) that is heated at a temperature.
(A) A dielectric film precursor solution is applied (step S23).
(B) Next, it is subjected to a first heat treatment in which heating is performed at a temperature of 300 ° C. or higher and 350 ° C. or lower in an oxidizing atmosphere (step S24).
(C) Subsequently, a second heat treatment is performed by heating at a temperature of 450 ° C. or higher and 950 ° C. or lower in an oxidizing atmosphere (step S25).

  The step (2) will be described more specifically. First, in the procedure (b) of step S23, for example, a precursor solution for forming a dielectric film 3 prepared in advance on the surface of the NiAl film-attached nickel foil 2 as the second conductive material is spin-coated. Etc. and dry. This drying can be performed, for example, by heating in the atmosphere at a temperature of about 150 ° C. for about 10 minutes. For example, the precursor solution is preferably applied to all of the surface (the upper surface in FIG. 4B) of the NiAl film-coated nickel foil 2, but may be applied to at least a part. The method of applying the precursor solution is not limited to the spin coating method, and other coating methods may be employed. For example, the precursor solution may be applied by spray application or slit coater application. The drying conditions for the precursor solution are not particularly limited, and for example, conditions other than those described above can be employed without departing from the spirit of the present invention. The components of the precursor solution will be described later.

  Next, the procedure (b) of step S24 and the step (c) of step S25 are performed successively and calcined. In the procedure (b), the first heat treatment is performed in an oxidizing atmosphere at a temperature of 300 ° C. or higher and 350 ° C. or lower, for example, for about 30 minutes. In the procedure (c), a second heat treatment is performed by heating at a temperature of 450 ° C. or higher and 950 ° C. or lower for about 30 minutes in an oxidizing atmosphere. Thereby, the dielectric precursor film 6 shown in FIG. 4C is formed. The film thickness T3 (see FIG. 4C) formed by these procedures is only 40 nm or more and 80 nm or less after the main baking (third heat treatment) per time. The oxidizing atmosphere in the first heat treatment and the second heat treatment is not particularly limited as long as it is an oxygen-containing atmosphere. For example, air is preferable from the viewpoints of cost and convenience. Further, the time of the first heat treatment and the time of the second heat treatment are not particularly limited, and for example, conditions other than those described above can be adopted without departing from the gist of the present invention.

  By the way, in order to obtain the dielectric characteristics stably, for example, the thickness of the dielectric film 3 is preferably at least 100 nm and more preferably 200 nm or more, so that the above-described application and calcining ((i) to (c) )) Is repeated a plurality of times, and the thickness of the dielectric precursor film 6 is increased as shown in FIG. For example, when the film thickness T4 (see FIG. 5) after the third heat treatment (main firing) of the dielectric film 3 is not less than 100 nm and not more than 500 nm, the dielectric characteristics can be made more stable. When the film thickness of the dielectric film 3 after the third heat treatment (main firing) is set to 100 nm or more and 500 nm or less, for example, depending on the slurry concentration of the precursor solution described above, the application and calcination ((a) It is preferable to repeat the procedure of (c) 3-6 times.

  Following the formation of the dielectric precursor film 6 in step S21 shown in FIG. 2, in step S26, a third heat treatment is performed as the main firing. Thereby, as shown in FIG. 5, the dielectric film 3 is formed. The third heat treatment is performed at a temperature of 900 ° C. or higher and 1400 ° C. or lower in a non-oxidizing atmosphere. The third heat treatment is the same as step S22 shown in FIG. After this main baking (third heat treatment), as shown in FIG. 5, a dielectric film 3 having a film thickness T4 of 100 nm to 500 nm is formed.

  Moreover, it is preferable to perform the main baking and the heat treatment in step S22 described above in a carbon container. The shape of the carbon container is preferably such that the entire NiAl film-coated nickel foil 2 on which the dielectric precursor film 6 is formed is wrapped, and the NiAl film-coated nickel foil 2 on which the dielectric precursor film 6 is formed as much as possible between the container and the container. It is more preferable that there is no space. Further, instead of being inserted into the carbon container, it may be sandwiched between carbon plates. That is, by performing main firing in a carbon container, oxidation during heat treatment can be more reliably suppressed. In the case where the main calcination is performed at a temperature of 1100 ° C. or higher and 1400 ° C. or lower without being put in a carbon container, it is difficult to reliably prevent oxidation even if an inert gas is introduced. When the main firing is performed at a temperature lower than 1100 ° C., the thin film capacitor material MC has the NiAl film 5 and has high oxidation resistance. Therefore, the thin film capacitor material MC is sufficiently oxidized under an inert atmosphere without using a carbon container. Can be suppressed. In this case, for example, an alumina container can be used instead of the carbon container.

  The main firing is performed for crystallization of the dielectric film 3 and complete removal of organic components in the dielectric film 3, and these conditions are maintained at a temperature of 900 ° C. or higher and 1400 ° C. or lower for a predetermined time. Achieved below. That is, since the BT film system has a higher crystallization temperature than the PZT film system, the unit capacitance of the dielectric film is deteriorated when the temperature is lower than 700 ° C. On the other hand, when the temperature of the main baking exceeds 1400 ° C., it is difficult to suppress the oxidation of the NiAl film 3 even under the above conditions, and as a result, the dielectric characteristics deteriorate. Moreover, the time of this baking is not specifically limited in the range which does not deviate from the meaning of this invention, For example, it can carry out normally within 30 minutes or more and 120 minutes.

[Step (3)]
Following step (2) shown in FIG. 2, in step S3 (step (3)), the first conductive material 1 (see FIG. 1) constituting the upper conductor (upper electrode) on the surface of the dielectric film 3 is formed. ). Thereby, the thin film capacitor material MC shown in FIG. 1 can be obtained.

  The first conductive material 1 is not particularly limited, and for example, a conductive metal such as copper, nickel, silver, gold, or platinum is used. Among them, nickel similar to the second conductive material 2 (lower conductive material) is preferable in terms of durability such as aging and cost. The thickness T5 (see FIG. 1) of the first conductive material 1 is not particularly limited as long as it does not depart from the spirit of the present invention. For example, about 100 nm is preferable from the viewpoint of dielectric characteristics.

  Examples of the film formation method for the first conductive material 1 (upper electrode) include a printing method using a paste, a coating method, a sputtering method (sputtering method), and the like, and among these, a sputtering method that can easily form a pad shape is preferable. In the sputtering method, for example, a metal mask having an arbitrary shape and size can be applied to the dielectric film 3, and a conductive material (a material having conductivity) can be sputtered in that state.

[Step (4)]
In the present manufacturing method, step (4) (step S4) may be performed as necessary following step (3) shown in FIG. In step (4), the thin film capacitor material obtained in step (3) is subjected to a fourth heat treatment in an atmosphere containing oxygen. Thereby, dielectric characteristics can be further improved or stabilized. This is due to, for example, operational effects such as reducing the influence of different phases generated at the dielectric interface when the upper conductive material is formed, improving the overall adhesion, and reducing strain.

  Note that whether or not to perform step (4) is arbitrary. For example, when the first conductive material 1 (upper electrode) is produced by a sputtering method, it is preferable to perform the step (4). In this case, the sputter damage of the dielectric film 3 can be recovered. Further, when the first conductive material 1 (upper electrode) is formed by applying a conductive paste or by vacuum deposition, the step (4) is not necessarily required.

  The temperature condition of the fourth heat treatment is not particularly limited as long as it does not depart from the gist of the present invention, but for example, a condition of 600 ° C. or more and 950 ° C. or less is preferable, and about 600 ° C. is more preferable. Since the fourth heat treatment is more effective in an atmosphere containing oxygen, the lower conductive material (lower electrode) may be oxidized at a temperature exceeding 950 ° C. Further, the time of the fourth heat treatment is not particularly limited as long as it does not depart from the gist of the present invention, but for example, it can usually be performed within 30 minutes to 120 minutes.

[Dielectric film and its precursor solution]
The dielectric film 3 used in the present manufacturing method is not particularly limited. For example, the present manufacturing method may be made of BT (BaTiO ₃ ), or Sr, Ca, Mg, Sn, and Zr as additive elements. It is preferably applied when forming the dielectric film 3 containing at least one selected from the group consisting of This is because the BT (BaTiO ₃ ) -based material has a relatively high crystallization temperature, so that the oxidation resistance by the heat treatment of the NiAl film-coated nickel foil 2 used in the present manufacturing method works effectively.

  The precursor solution of the dielectric film 3 is not particularly limited. For example, 1-butanol, 1-pentanol, 3methyl-1butanol, 2methyl-1butanol, 2-methyl-2-butanol And at least one alcohol selected from the group consisting of 2-methyl-1-propanol, at least one ester selected from the group consisting of butyl acetate, propyl acetate, isopentyl acetate, and butyl butyrate, and 2 -Selected from the group consisting of at least one alkaline earth metal element selected from the group consisting of Ba, Sr, Mg and Ca and Ti, Sn and Zr in the mixed solvent consisting of carboxylic acid which is ethylhexanoic acid Those formed by adding at least one metal element can be used.

  The method for preparing the precursor solution is not particularly limited. For example, as described below, an organic acid salt solution (A) containing an alkaline earth metal element and Ti, Sn, and Zr are used. A method of preparing a precursor solution by separately preparing an alkoxide solution (B) containing at least one metal element selected from the group consisting of both at a predetermined ratio is simple and stable. Is preferable in view of high.

[Method for preparing organic acid salt solution (A)]
As a method for preparing the organic acid salt solution (A), for example, first, the above-mentioned predetermined mixed solvent is heated while refluxing at a temperature of 100 ° C. or higher and 110 ° C. or lower in an inert gas atmosphere. Next, using at least one metal of an alkaline earth metal element selected from the group consisting of Ba, Sr, Mg and Ca to be blended, or an alkoxide or carboxylate thereof as a raw material, a heated predetermined mixed solvent Add and dissolve. Note that depending on the raw material, the temperature rises remarkably due to the heat of dissolution as the dissolution proceeds, so care must be taken. Here, the raw materials are dissolved by, for example, stirring and heating for 1 hour to 3 hours. Here, as a feature when using a mixed solvent, compared to a solvent that does not mix (solvent consisting of a single substance), the raw material can be easily dissolved, and even when the mixed solvent is in a single state, Since water miscibility is low, the preservability is better than before.

  Further, the blending ratio of the above mixed solvent is also important. As for the mixed solvent, for example, at least one kind of solvent from each of alcohols, esters and carboxylic acids is preferably blended at a predetermined blending ratio. For example, when the mixed solvent uses a mixed solvent composed of alcohols, esters, and carboxylic acids to dissolve the alkaline earth metal element metal, the mixing ratio of the mixed solvent is alcohols: esters: carboxylic acids, The volume ratio is preferably 2: 2: 1 or more and 2: 1: 1 or less (for 100 parts by volume of alcohol, esters are 50 to 100 parts by volume and carboxylic acid is 50 parts by volume). Thereby, liquid solubility and stability increase. For example, in the case of a mixed solvent of alcohols and esters without adding carboxylic acid, the solubility and liquid storage stability of the metal alkoxide are slightly inferior. The metal concentration (metal element concentration) of the organic acid salt solution (A) is preferably, for example, 0.4 mol / L or more and 1.2 mol / L or less.

[Method for Preparing Alkoxide Liquid (B)]
As a method for preparing the alkoxide liquid (B), for example, a metal alkoxide containing at least one metal element selected from the group consisting of Ti, Sn and Zr, or a carboxylate is used as a raw material. Among the raw materials, examples of the metal alkoxide include methoxide, ethoxide, isopropoxide, or butoxide, and isopropoxide or butoxide is particularly preferable because of an appropriate reaction rate. Further, as the carboxylate, acetate or ethylhexanoate compounds can be used. Subsequently, these raw materials are obtained from 1-butanol, 1-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 2-methyl-1-propanol. A mixture comprising at least one alcohol selected from the group consisting of, at least one ester selected from the group consisting of propyl acetate, isopentyl acetate, butyl acetate, and butyl butyrate, and 2-ethylhexanoic acid as the carboxylic acid. It is added to a solvent and dissolved by stirring in the atmosphere at a temperature of 20 ° C. or more and 60 ° C. or less for a period of 0.2 hours to 2 hours. In addition, the conditions of this stirring are not specifically limited, If it does not deviate from the meaning of this invention, it is arbitrary. The metal concentration (metal element concentration) of the alkoxide liquid (B) is preferably 0.4 mol / L or more and 1.2 mol / L or less, for example.

[Method of synthesizing precursor solution]
As a method for synthesizing the precursor solution, for example, after cooling the organic acid salt solution (A) and the alkoxide solution (B), both solutions are mixed so that the amount of metal contained in the solution is 1: 1 by molar ratio. After blending, they are mixed. Next, in an inert gas atmosphere, the reaction is sufficiently performed at a temperature of 100 ° C. or higher and 110 ° C. or lower, for example, for 2 hours or longer to synthesize a compound containing a constituent element.

  Here, control of this synthesis temperature is important. For example, when the synthesis temperature is less than 100 ° C., the constituent elements are present alone, resulting in a difference in hydrolysis rate, and the uniformity of the film composition may be inferior. On the other hand, when the synthesis temperature exceeds 110 ° C., not only the volatilization of the solvent is activated, but the contents may also be volatilized at the same time to cause a composition shift.

  In the preparation method of the precursor solution, since it is performed while refluxing in the synthesis heating at the time of dissolution, there is no volatile component from the solvent, and there is no fluctuation of the liquid composition.

As described above, according to this manufacturing method, the thin film capacitor material MC shown in FIG. 1 can be manufactured. In this thin film capacitor material MC, the second conductive material 2 is laminated on the surface 4a, the nickel foil 4 having the surface 4a having the maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less, and the Ni composition is 65% by mass. And a NiAl film 5 with a balance of Al and a NiAl film 5 with the balance being Al, a unit capacitance of 1.9 μF / cm ² or more, and a leakage current of 5 nA / cm ^2. It is as follows. The nickel foil with the NiAl film has a surface resistance value of 0.1Ω or more and 1Ω or less. The thin film capacitor material MC has a dielectric loss of 0.3% or less, for example. Thus, according to this manufacturing method, the thin film capacitor material MC with excellent dielectric properties and small leakage current can be manufactured. In this specification, the “unit capacitance” is a value obtained by obtaining the capacitance when an AC voltage is applied under the conditions of 1.0 V and a frequency of 1 MHz. Further, in this specification, “leakage current” is a value represented by a value obtained by measuring a current when a DC voltage is changed from −3 V to 3 V and dividing the maximum current by an electrode area. In this specification, “dielectric loss” (D) is a value (tan δ) obtained by measuring the imaginary component of the dielectric constant and dividing the loss energy by the accumulated energy in the dielectric constant measurement under the condition of a frequency of 1 MHz.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples.

In addition, the thickness / maximum surface roughness (Rmax) of the nickel foil 4 used in the examples and comparative examples, the composition analysis / film thickness / surface resistance value of the NIAl film, and the dielectric characteristics of the obtained thin film capacitor material MC The evaluation method of leakage current is as follows.
(1) Measurement of the thickness of the nickel foil 4: It was measured with a micrometer.
(2) Measurement of the maximum surface roughness (Rmax) of the nickel foil 4: Using an atomic force microscope (AFM), five three-dimensional shapes are measured in a 20 μm square area of the surface and attached to the AFM. The height data was statistically processed using software.
(3) Composition analysis of NIAl film: An ICP emission analysis method was used.
(4) NiAl film thickness: measured with an optical profiler (NewView 6200) manufactured by Zygo.
(5) Measurement of surface resistance value of nickel foil 2 with NiAl film: Two terminals determined to have a width of 1 cm were contacted and measured with a tester.
(6) Measurement of dielectric characteristics: An electrostatic capacity (unit electrostatic capacity) at an AC voltage of 1.0 V and a frequency of 1 MHz was obtained, and a relative dielectric constant and a dielectric loss were calculated from the obtained electrostatic capacity.
(7) Measurement of leakage current: The current was measured by changing the DC voltage from −3 V to 3 V, and the leakage current (A / cm ² ) was calculated by dividing the maximum current by the electrode area.

Moreover, the preparation method of the precursor solution of the dielectric film 3 used by the Example and the comparative example is as follows.
[Method for Preparing BT Precursor Solution (Precursor Solution of Dielectric Film 3)]
Metal barium was added to 75 mL of a mixed solvent blended at a volume ratio of 2-methyl-1-butanol: 2-ethylhexanoic acid = 2: 1, and stirred and mixed at 110 ° C. for 2 hours in a nitrogen stream. A barium organic acid salt solution (A) having a Ba concentration of 0.8 mol / L was prepared.
On the other hand, titanium tetraisopropoxide having the same number of moles as metal barium is added to 25 mL of butyl butyrate and stirred and mixed in the atmosphere at 25 ° C. for 0.4 hours to obtain a titanium alkoxide liquid (B ) Was prepared.
Next, the titanium alkoxide liquid (B) is dropped into the barium organic acid salt liquid (A) so that the molar ratio is barium: titanium = 1: 1, and the mixture is stirred and mixed at 110 ° C. for 2 hours in a nitrogen stream. A precursor solution for BT having a total metal element concentration of 0.8 mol / L (final concentration of titanium 0.4 mol / L, final concentration of barium 0.4 Mmol / L) was obtained. The volume ratio of alcohols, esters and carboxylic acids in this precursor solution is 2: 1: 1.

(Examples 1-4)
The BT precursor solution was used as a coating solution.
As a second conductive material, a NiAl film having a thickness of 0.3 μm and Ni of 69% by mass is formed by a DC sputtering method on a nickel foil 4 (purity 99.5%) having a thickness of 100 μm and a maximum surface roughness (Rmax) of 18 nm. 5 was formed. The Ni foil 2 with NiAl film 2 was cut into 3 cm square. The surface resistance value was 0.2Ω.

  The coating solution was applied for 20 seconds by spin coating (rotation speed: 1500 rpm). After coating, after drying for 10 minutes at a temperature of 150 ° C., it is subjected to a first heat treatment at a temperature of 350 ° C. for 30 minutes in the atmosphere, followed by a second heat treatment at a temperature of 500 ° C. for 30 minutes in the atmosphere. did. The steps from the coating to the second heat treatment are repeated 4 times (Example 1), 5 times (Example 2), 6 times (Example 3), and 7 times (Example 4) to form the film of the dielectric film 3. Four types of samples with different thicknesses were produced.

  Next, the obtained four types of samples were inserted into a carbon container, which was inserted into a core tube of an electric furnace. Here, a tubular furnace having a core tube diameter of 75 mm was used as the electric furnace. First, replacement was performed for 1 hour while flowing nitrogen gas at 1 L / min into the furnace tube.

  Next, it was subjected to a third heat treatment at a temperature of 900 ° C. for 60 minutes while flowing nitrogen gas, followed by firing to form a BT film (dielectric film 3), and the thickness of the BT film was confirmed. 1 was 220 nm, Example 2 was 260 nm, Example 3 was 310 nm, and Example 4 was 360 nm.

Thereafter, a first conductive material 1 made of platinum having a diameter of 0.32 mm was sputtered on the BT film as an upper electrode. After forming the first conductive material 1 (upper electrode), heat treatment was performed in the atmosphere at a temperature of 500 ° C. for 30 minutes (fourth heat treatment) to obtain the thin film capacitor material MC shown in FIG. Using this, dielectric characteristics and leakage current were measured. The results are shown in Table 1. When the unit capacitance is 1.9 μF / cm ² or more, the dielectric property is judged as “good”, and when the leakage current is 5 nA / cm ² or less, the leakage current is judged as “good”.

(Examples 5 to 8)
A thin film capacitor material MC was obtained in the same manner as in Examples 1 to 4 except that the temperature of the third heat treatment was set to 1000 ° C., and the dielectric characteristics and leakage current were measured. The results are shown in Table 1.

(Examples 9 to 12)
Except that the temperature of the third heat treatment was set to 1100 ° C., it was carried out in the same manner as in Examples 1 to 4, and the thin film capacitor material MC was obtained, and the dielectric characteristics and the leakage current were measured. The results are shown in Table 1.

(Examples 13 to 16)
A thin film capacitor material MC was obtained in the same manner as in Examples 1 to 4 except that the temperature of the third heat treatment was 1200 ° C., and the dielectric characteristics and leakage current were measured. The results are shown in Table 1.

(Examples 17 to 20)
Except that the temperature of the third heat treatment was set to 1400 ° C., it was carried out in the same manner as in Examples 1 to 4 to obtain the thin film capacitor material MC, and the dielectric characteristics and the leakage current were measured. The results are shown in Table 1.

(Examples 21 to 24)
A thin film capacitor material MC was obtained in the same manner as in Examples 13 to 16 except that the Ni content of the NiAl film 5 was set to 65% by mass, and dielectric characteristics and leakage current were measured. The results are shown in Table 2.

(Examples 25 to 28)
A thin film capacitor material MC was obtained in the same manner as in Examples 13 to 16 except that the Ni content of the NiAl film 5 was set to 73% by mass, and dielectric characteristics and leakage current were measured. The results are shown in Table 2.

(Examples 28 to 32)
A thin film capacitor material MC was obtained in the same manner as in Examples 13 to 16 except that the thickness of the NiAl film 5 was 1.0 μm, and dielectric characteristics and leakage current were measured. The results are shown in Table 2.

(Examples 33 to 36)
A thin film capacitor material MC was obtained in the same manner as in Examples 13 to 16 except that the thickness of the NiAl film 5 was set to 0.05 μm, and the dielectric characteristics and the leakage current were measured. The results are shown in Table 2.

(Comparative Examples 1-4)
A thin film capacitor material was obtained in the same manner as in Examples 1 to 4 except that the temperature of the third heat treatment was 800 ° C., and the dielectric characteristics and the leakage current were measured. The results are shown in Table 3.

(Comparative Examples 5 to 8)
A thin film capacitor material was obtained in the same manner as in Examples 1 to 4 except that the temperature of the third heat treatment was set to 700 ° C., and dielectric characteristics and leakage current were measured. The results are shown in Table 3.

(Comparative Examples 9-12)
As the second conductive material, a nickel foil having a maximum surface roughness (Rmax) of 840 nm obtained by mirror polishing the surface of a rolled nickel foil (purity 99.5%) having a thickness of 100 μm and a surface resistance value of 0.1Ω is used. A thin film capacitor material was obtained and dielectric characteristics and leakage current were measured except that the NiAl film 5 was not formed on the second conductive material. The results are shown in Table 3.

(Comparative Examples 13 to 16)
A thin film capacitor material was obtained in the same manner as in Examples 1 to 4 except that the NiAl film 5 was not formed on the second conductive material, and dielectric characteristics and leakage current were measured. The results are shown in Table 3.

(Comparative Examples 17-20)
As the second conductive material, a nickel foil having a maximum surface roughness (Rmax) of 840 nm obtained by mirror polishing the surface of a rolled nickel foil (purity 99.5%) having a thickness of 100 μm and a surface resistance value of 0.1Ω is used. In the same manner as in Examples 1 to 4, except that the NiAl film 5 was not formed on the second conductive material and the temperature of the third heat treatment was set to 800 ° C., a thin film capacitor material was obtained. The dielectric properties and leakage current were measured. The results are shown in Table 3.

(Comparative Examples 21-24)
A thin film capacitor material was obtained in the same manner as in Examples 1 to 4 except that the Ni content of the NiAl film was set to 62% by mass and the temperature of the third heat treatment was set to 1200 ° C. Dielectric characteristics and leakage current were obtained. Was measured. The results are shown in Table 3.

(Comparative Examples 25-28)
A thin film capacitor material was obtained in the same manner as in Examples 1 to 4 except that the Ni content of the NiAl film was 80% by mass and the temperature of the third heat treatment was 1200 ° C. Was measured. The results are shown in Table 3.

From Table 1 to Table 3, in the example, a unit capacitance of 1.9 μF / cm ² or more and a leakage current of 5 nA / cm ² or less can be obtained, and excellent dielectric characteristics and leakage current characteristics can be obtained. I understand.
On the other hand, in the comparative example, satisfactory results were not obtained in both dielectric characteristics and leakage current characteristics.

  As is apparent from the above, the method for producing a thin film capacitor material of the present invention is particularly suitable for a thin film capacitor forming material and a component built-in capacitor obtained by using the thin film capacitor forming material.

  The technical scope of the present invention is not limited to the aspects described in the above-described embodiments. One or more of the requirements described in the above embodiments and the like may be omitted. In addition, the requirements described in the above-described embodiments and the like can be combined as appropriate. In addition, as long as it is permitted by law, the disclosure of all documents cited in the above-described embodiments and the like is incorporated as a part of the description of the text.

MC: Thin film capacitor material 1: Upper electrode (first conductive material)
2 ... Lower electrode (second conductive material)
3 ... Dielectric film 4 ... Nickel foil 5 ... NiAl film

Claims (14)

A method of manufacturing a thin film capacitor material having a dielectric film between a first conductive material constituting an upper electrode and a second conductive material constituting a lower electrode,
The manufacturing method of the thin film capacitor material characterized by including the following process (1)-(3).
Step (1): On the surface of the nickel foil having a surface having a maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less as the second conductive material, the Ni composition is 65% by mass or more and 73% by mass or less and the balance is left. A nickel foil with a NiAl film on which a NiAl film having an Al composition is formed is manufactured.
Step (2): A dielectric film is formed on the surface of the NiAl film by performing a heat treatment at least in a non-oxidizing atmosphere and at a temperature of 900 ° C. to 1400 ° C.
Step (3): A first conductive material is formed on the surface of the dielectric film. The said process (1) includes the following process, The manufacturing method of the thin film capacitor material of Claim 1 characterized by the above-mentioned.
Step: After the NiAl film is formed, the surface resistance value on the NiAl film side is selected from 0.01Ω to 1Ω. The said process (2) includes the following process, The manufacturing method of the thin film capacitor material of Claim 1 or Claim 2 characterized by the above-mentioned.
Process: A third heat treatment in which the following steps (a) to (c) are repeatedly formed on the surface of the NiAl film a plurality of times and then heated at a temperature of 900 ° C. to 1400 ° C. in a non-oxidizing atmosphere. To form a dielectric film.
(A) A dielectric film precursor solution is applied.
(B) Next, it is subjected to a first heat treatment in which heating is performed at a temperature of 300 ° C. or higher and 350 ° C. or lower in an oxidizing atmosphere.
(C) Subsequently, a second heat treatment is performed by heating at a temperature of 450 ° C. or higher and 950 ° C. or lower in an oxidizing atmosphere. Furthermore, following the said process (3), the following process (4) is included, The manufacturing method of the thin film capacitor material as described in any one of Claims 1-3 characterized by the above-mentioned.
Step (4): A fourth heat treatment is performed in an atmosphere containing oxygen.   The said nickel foil is produced by the electroforming method, The manufacturing method of the thin film capacitor material as described in any one of Claims 1-4 characterized by the above-mentioned.   The dielectric precursor solution is selected from the group consisting of 1-butanol, 1-pentanol, 3methyl-1 butanol, 2methyl-1 butanol, 2-methyl-2-butanol, and 2-methyl-1-propanol. In a mixed solvent comprising at least one alcohol selected, at least one ester selected from the group consisting of butyl acetate, propyl acetate, isopentyl acetate, and butyl butyrate, and a carboxylic acid that is 2-ethylhexanoic acid And at least one alkaline earth metal element selected from the group consisting of Ba, Sr, Mg and Ca and at least one metal element selected from the group consisting of Ti, Sn and Zr. The method for producing a thin film capacitor material according to any one of claims 1 to 5, wherein:   7. The thin film capacitor material according to claim 6, wherein the mixing ratio of the mixed solvent is such that alcohols: esters: carboxylic acid has a capacity ratio in the range of 2: 2: 1 to 2: 1: 1. Manufacturing method. The method of manufacturing a thin film capacitor material according to any one of claims 1 to 7, wherein the dielectric film has a unit capacitance of 1.9 µF / cm ² or more. 2. A current measured when a DC voltage is changed from -3V to 3V is measured, and a leakage current represented by a value obtained by dividing a maximum current by an electrode area is 5 nA / cm ² or less. The method for producing a thin film capacitor material according to claim 8.   The thickness of the said nickel foil is 10 micrometers or more and 500 micrometers or less, The manufacturing method of the thin film capacitor material as described in any one of Claims 1-9 characterized by the above-mentioned.   The heat treatment performed in the step (2) in a non-oxidizing atmosphere and at a temperature of 900 ° C. to 1400 ° C. is performed in a carbon container. The manufacturing method of the thin film capacitor material of item.   12. The method of manufacturing a thin film capacitor material according to claim 1, wherein a thickness of the dielectric film is not less than 100 nm and not more than 500 nm.   The method of manufacturing a thin film capacitor material according to claim 1, wherein the NiAl film is formed by sputtering. A thin film capacitor material comprising a dielectric film between a first conductive material constituting the upper electrode and a second conductive material constituting the lower electrode,
The second conductive material includes a nickel foil having a surface with a maximum surface roughness (Rmax) of 1 nm or more and 20 nm or less, laminated on the surface, and a Ni composition of 65% by mass to 73% by mass with the balance being Al. A NiAl film-attached nickel foil comprising a NiAl film having the composition:
When the unit capacitance is 1.9 μF / cm ² or more and the DC voltage is changed from −3 V to 3 V, the current is measured, and the leakage current represented by the value obtained by dividing the maximum current by the electrode area is A thin film capacitor material, wherein the material is 5 nA / cm ² or less.

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