JP2010232329A - Thin-film capacitor and manufacturing method of thin-film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-film capacitor that has a dielectric thin film containing a composite oxide of Ca and Zr, which can suppress leakage current better than ever. <P>SOLUTION: A thin film capacitor 2 contains a dielectric composition expressed by the following chemical formula (1), and has a dielectric thin film 4 with a thickness of 200 to 1,000 nm and a pair of electrodes 6 and 8 that sandwich the dielectric thin film 4 between them. The chemical formula (1) is Ca<SB>m</SB>Zr<SB>1-x</SB>Ti<SB>x</SB>O<SB>3</SB>(where 0.9≤m≤1.1 and 0≤x<1). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin film capacitor and a method for manufacturing the thin film capacitor.

Conventionally, a multilayer capacitor using a sintered body made of a dielectric ceramic material (hereinafter, referred to as “Ca (Zr, Ti) O ₃ ”) mainly composed of CaZrO ₃ or CaTiO ₃ is used as a temperature compensation capacitor. It is known (see Patent Document 1 below). With the recent miniaturization of electronic devices, there is a demand for thinner temperature compensating capacitors.

JP 2001-167970 A JP 2002-075054 A Japanese Patent Laid-Open No. Sho 62-131415 Japanese Patent Publication No. 07-070432

In order to sinter the above Ca (Zr, Ti) O ₃ , firing at a high temperature of about 1300 to 1600 ° C. is required. However, when a base metal having a low melting point such as Ni is used as the internal electrode, if the Ca (Zr, Ti) O ₃ and the internal electrode are simultaneously fired at a high temperature, the internal electrode melts, and in some cases, the leakage current increases. It was a problem that a short circuit occurred. Another problem is that leakage current tends to occur as the capacitor becomes thinner.

As a method of preventing the melting of the internal electrodes, the Patent Document 2, by adding a sintering aid such as glass components in Ca (Zr, Ti) _{O 3,} Ca and (Zr, Ti) _{O 3} more A method of manufacturing a multilayer capacitor that is sintered at a low temperature has been proposed. Patent Document 3 proposes that 0.2 to 10 parts by weight of a sintering aid is added to 100 parts by weight of Ca (Zr, Ti) O ₃ used for manufacturing a multilayer capacitor. . Further, in Patent Document 3 described above, when the amount of the sintering aid is small, even if the firing temperature is 1300 ° C., the sintering of Ca (Zr, Ti) O ₃ having the desired electric characteristics is dense. It is stated that the body cannot be obtained.

However, even when the manufacturing methods described in Patent Documents 2 and 3 are adopted, the amount of shrinkage of the green sheet containing Ca (Zr, Ti) O ₃ and the binder is smaller than the amount of shrinkage of the internal electrode. Therefore, a large strain is generated between the dielectric layer and the internal electrode. And, as the dielectric layer and the internal electrode are both made thinner to make the multilayer capacitor thinner, the distortion between the dielectric layer and the internal electrode becomes more prominent. Therefore, in some cases, peeling (delamination) of the dielectric layer from the electrode and leakage current associated with the peeling easily occur, and there is a problem that the yield is greatly reduced.

  As described above, in the multilayer capacitor manufacturing methods described in Patent Documents 2 and 3, it is difficult to suppress the occurrence of leakage current accompanying the reduction in thickness of the multilayer capacitor.

As a manufacturing method different from the manufacturing methods described in Patent Documents 2 and 3, the Patent Document 4 is characterized in that a dielectric thin film is formed on an electrode by chemical vapor deposition in order to reduce the thickness of the capacitor. A method of manufacturing a thin film capacitor has been proposed. In this manufacturing method, a thin film of (Mg, Ca) TiO ₃ useful as a dielectric material for a temperature compensating capacitor is formed at a low temperature of 600 ° C. or lower. However, in order to form a thin film of (Mg, Ca) TiO _{3 at} a low temperature, it is necessary to use a plasma CVD method, an electron cyclotron (ECR) plasma CVD method, or a plasma sputtering method. An apparatus for carrying out these film forming methods is very expensive, and there is a problem that the cost is increased.

  Accordingly, the present invention has been made in view of the above problems, and includes a thin film capacitor including a dielectric thin film containing a composite oxide of Ca and Zr, and capable of suppressing a leakage current as compared with the prior art, and manufacture of the thin film capacitor It aims to provide a method.

In order to achieve the above object, a thin film capacitor of the present invention includes a dielectric thin film having a thickness of 200 to 1000 nm and a dielectric thin film sandwiched between a dielectric thin film including a dielectric composition represented by the following chemical formula (1). A pair of electrodes.
_{Ca m Zr 1-x Ti x} O 3 (1)
[In the chemical formula (1), 0.9 ≦ m ≦ 1.1 and 0 ≦ x <1. ]

According to the present invention, a leakage current can be suppressed as compared with a conventional thin film capacitor including a dielectric thin film containing Ca (Zr, Ti) O ₃ .

  In the present invention, the dielectric thin film preferably includes at least two dielectric layers substantially parallel to the electrode, and a planar interface is formed between the two dielectric layers. Thereby, it becomes easy to suppress the leakage current.

In the first method for producing a thin film capacitor of the present invention, one or more precursor layers are laminated on an electrode by pre-baking a coating formed from a solution of Ca and Zr once or more on the electrode. Laminating step, main firing step of firing one or more precursor layers laminated on the electrode at 850 to 1000 ° C. to form a dielectric layer on the electrode, and laminating step and main firing step alternately A thin film forming step of forming a dielectric thin film having a thickness of 200 to 1000 nm on the electrode by having two or more laminated dielectric layers, The Ti content is 0 mol or more, and the ratio M _Ca / (M _Zr + M _Ti ) of the number of moles of Ca M _Ca to the sum of the number of moles of _Zr M _Zr and the number of moles of _Ti M _Ti is 0.9-1. Set to 1.

  According to the first manufacturing method, the thin film capacitor of the present invention can be manufactured.

In said 1st manufacturing method, it is preferable that content of the sintering auxiliary agent in a solution shall be 1000 ppm or less with respect to metal element content in a solution. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor.

In the second method for producing a thin film capacitor of the present invention, one or more precursor layers are laminated on an electrode by pre-baking a coating film formed from a solution of Ca and Zr once or more on the electrode. And a main firing step of firing one or more precursor layers laminated on the electrode to form a dielectric layer on the electrode, the content of Ti in the solution being 0 mol or more and then, Zr ratio _M Ca _/ number of moles _{M Zr} and Ti moles _M moles of Ca to the sum of _{Ti M Ca} of the (M Zr _{+ M Ti)} is 0.9 to 1.1, sintering in a solution aid The content of the agent is set to 1000 ppm or less with respect to the metal element content in the solution.

  According to the second manufacturing method, the thin film capacitor of the present invention can be manufactured. One of the characteristics of the second manufacturing method is that the leakage current of the thin film capacitor is suppressed by deliberately reducing the amount of the sintering aid used as compared with the conventional manufacturing method. In other words, in the second manufacturing method, the dielectric thin film is sufficiently sintered at a low temperature even if the amount of the sintering aid is smaller than before or no sintering aid is used. It becomes possible to make it.

  In the second production method, the precursor layer is preferably subjected to main baking at 850 to 1000 ° C. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor.

  In the second manufacturing method, the dielectric thin film having two or more dielectric layers laminated and having a thickness of 200 to 1000 nm by alternately performing the lamination step and the main firing step twice or more. It is preferable to provide a thin film forming step of forming a film on the electrode. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor.

  According to the present invention, it is possible to provide a thin film capacitor including a dielectric thin film containing a complex oxide of Ca and Zr and capable of suppressing a leakage current as compared with the conventional one, and a method for manufacturing the thin film capacitor.

It is a schematic sectional drawing of the thin film capacitor which concerns on 1st embodiment of this invention. It is a schematic diagram which shows a part of manufacturing method of the thin film capacitor which concerns on 1st embodiment of this invention. It is a schematic diagram which shows a part of manufacturing method of the thin film capacitor which concerns on 1st embodiment of this invention. It is a schematic diagram which shows a part of manufacturing method of the thin film capacitor which concerns on 3rd embodiment of this invention. It is a SEM image of the section of the dielectric thin film with which the thin film capacitor concerning the example of the present invention is provided. FIG. 6A is a schematic diagram showing a part of a cross section of a dielectric thin film included in a thin film capacitor according to an embodiment of the present invention, and FIG. 6B shows a thin film capacitor according to a comparative example of the present invention. It is the schematic which shows a part of cross section of the dielectric material thin film provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In addition, the same code | symbol is attached | subjected about the same or equivalent element. In addition, although the positional relationship between the top, bottom, left and right is as shown in the drawing, the ratio of dimensions is not limited to that shown in the drawing. Further, when the description overlaps, the description is omitted.

[First embodiment]
(Thin film capacitor)
As shown in FIG. 1, the thin film capacitor 2 of the first embodiment includes a dielectric thin film 4 and a pair of electrodes (base electrode 6 and upper electrode 8) opposed in parallel with the dielectric thin film 4 interposed therebetween, Is provided. FIG. 1 is a cross-sectional view of the thin film capacitor 2 in the stacking direction of the base electrode 6, the dielectric thin film 4 and the upper electrode 8.

The dielectric thin film 4 includes a dielectric composition represented by the following chemical formula (1).
_{Ca m Zr 1-x Ti x} O 3 (1)
In chemical formula (1), 0.9 ≦ m ≦ 1.1 and 0 ≦ x <1.

  When m is out of the above numerical range, the leakage current increases as compared with the case where m is within the above numerical range.

In the above chemical formula (1), 0 ≦ x ≦ 0.2 is preferable. Thereby, the temperature characteristic of a capacitance can be improved. Specifically, the temperature coefficient τ _c of the electrostatic capacity of the dielectric thin film 4 satisfying 0 ≦ x ≦ 0.2 is −250 to 23 ppm / ° C., which satisfies EIA standard CK.

The thickness of the dielectric thin film 4 is 200 to 1000 nm. When the thickness of the dielectric thin film 4 is less than 200 nm, the leakage current increases as compared with the case where the thickness is 200 to 1000 nm, and in some cases, a short circuit occurs in the thin film capacitor. When the thickness of the dielectric thin film 4 is larger than 1000 nm, the leakage current increases as compared with the case where the thickness is 200 to 1000 nm. The area of the dielectric thin film 4 is, for example, about 0.9 × 0.5 mm ² .

  The dielectric thin film 4 includes a first dielectric layer 10 and a second dielectric layer 12 that are parallel to the lower electrode 6 and the upper electrode 8. A planar interface 14 is formed between the first dielectric layer 10 and the second dielectric layer 12.

  Although the fine structure of the interface 14 is not necessarily clear, the present inventors have found that a small amount of impurities or the like in the dielectric thin film 4 is deposited at the interface 14 and that many fine pores (voids) are formed. I think it is formed. The present inventors consider that the fact that this interface functions as a barrier against leakage current contributes to suppression of leakage current.

  The base electrode 6 may be a base metal or a noble metal, but preferably contains Ni as a main component. Ni is preferable in that it is easy to process by CMP (Chemical Mechanical Polishing) and is cheaper than noble metals. The purity of Ni constituting the base electrode 6 is preferably as high as possible, and is preferably 99.99% by weight or more. Note that the base electrode 6 may contain a small amount of impurities as long as the effects of the present invention are not impaired.

The base electrode 6 may be a metal foil or a metal thin film formed on a substrate such as Si, glass, or ceramic. When the base electrode 6 is a metal foil, the thickness of the base electrode 6 is preferably 5 to 100 μm, and more preferably 20 to 70 μm. When the thickness of the base electrode 6 is too thin, it tends to be difficult to hand link the base electrode 6 when the thin film capacitor 2 is manufactured. When the base electrode 6 is a metal thin film formed on a substrate, the thickness of the base electrode 6 is preferably 50 nm or more. In addition, before forming a metal thin film on a board | substrate, in order to improve the adhesiveness of a board | substrate and a metal thin film, you may form an adhesion layer on a board | substrate. The area of the base electrode 6 is, for example, about 1 × 0.5 mm ² .

  The upper electrode 8 may be a base metal or a noble metal, but is preferably made of Cu or a Cu alloy. Examples of the Cu alloy include a Corson-based Cu alloy to which Ni or Si is added, a Cu alloy to which Cr or Sn is added, a Cu alloy to which a Ni-Fe system is added, or the like. The upper electrode 8 may contain a small amount of impurities as long as the effects of the present invention are not impaired.

In the thin film capacitor 2 of the first embodiment, since the dielectric thin film 4 contains Ca _m Zr _1-x Ti _x O ₃ and the thickness of the dielectric thin film 4 is 200 to 1000 nm, Ca (Zr, Ti) O _As compared with a conventional thin film capacitor having a dielectric thin film including ₃ , leakage current can be suppressed. The thin film capacitor 2 of the first embodiment is suitably used as a temperature compensation capacitor for an LC resonance circuit or a crystal oscillator.

(Method for manufacturing thin film capacitor 2)
1st embodiment demonstrates the case where the thin film capacitor 2 is manufactured using the 1st manufacturing method mentioned above.

  The manufacturing method of the thin film capacitor according to the first embodiment is a lamination in which two precursor layers are laminated on a base electrode by pre-baking a coating film formed from a solution of Ca and Zr twice on the base electrode. And a main firing step of subjecting two precursor layers laminated on the base electrode to main firing at 850 to 1000 ° C. to form one dielectric layer on the base electrode. That is, in the first embodiment, the dielectric layer is formed on the base electrode using the solution method. And in 1st embodiment, it has the 1st dielectric material layer 10 and the 2nd dielectric material layer 12 which were laminated in the thin film formation process which performs a lamination process and a main calcination process twice each, and thickness is A dielectric thin film 4 having a thickness of 200 to 1000 nm is formed on the base electrode 6. Next, the upper electrode 8 is formed on the dielectric thin film 4 to obtain the thin film capacitor 2. Below, each process is demonstrated using FIG. 2, FIG. 2 and 3 are schematic cross-sectional views in the laminating direction of the coating film, the precursor layer, the dielectric layer, or the dielectric thin film.

  In the thin film formation step of the first embodiment, the following first lamination step, first main baking step, second lamination step, and second main baking step are performed.

<First lamination process>
In the first lamination step, first, the base electrode 6 is prepared. If necessary, the surface of the base electrode 6 may be polished by a method such as CMP, electropolishing or buffing.

  As shown in FIG. 2A, a solution of Ca and Zr is applied to the entire surface of the base electrode 6 to form a first coating film 20a. Application of the Ca and Zr solution may be performed by spin coating. The thickness of the first coating film 20a can be adjusted by the spin coat rotation speed, coating time, and the like.

In the first embodiment, the content of Ti in the solution of Ca and Zr is adjusted to 0 mol or more, and the ratio of the number of moles of Ca M _{Ca to} the total number of moles of _Zr M _Zr and number of moles of _Ti M _Ti in the solution. M _Ca / (M _Zr + M _Ti ) is adjusted to 0.9 to 1.1. Thereby, the composition of the dielectric composition included in the dielectric thin film 4 can be set to the composition represented by the following chemical formula (1). Hereinafter, a solution satisfying these conditions is referred to as a “metal solution”. _{Incidentally, M Ca / (M Zr +} M Ti) _is consistent with m in _{Ca m Zr 1-x Ti x} O 3.
_{Ca m Zr 1-x Ti x} O 3 (1)
In chemical formula (1), 0.9 ≦ m ≦ 1.1 and 0 ≦ x <1.

When M _Ca / (M _Zr + M _Ti ) is outside the above numerical range, the leakage current of the thin film capacitor 2 is increased as compared to the case where M _Ca / (M _Zr + M _Ti ) is within the above numerical range. . This increase in leakage current is due to the composition satisfying the stoichiometric ratio (M _Ca / (M _Zr + M _Ti ) = m = 1 when M _Ca / (M _Zr + M _Ti ) is outside the above numerical range. The deviation of M _Ca / (M _Zr + M _Ti ) from the composition increases, and in the main firing step described later, an oxide of Ca, an oxide of Zr or an oxide of Ti is generated in the dielectric thin film 4. The present inventors think that it originates in this.

In the first embodiment, the ratio M _Ti / (M _Zr + M _Ti ) in the metal solution is preferably adjusted to 0.0 to 0.2. Thereby, the temperature characteristic of the capacitance of the dielectric thin film 4 is improved. _{Incidentally, M Ti / (M Zr +} M Ti) _is consistent with x in _{Ca m Zr 1-x Ti x} O 3.

  As the metal solution, for example, a liquid obtained by dissolving organic salts of Ca and Zr in an organic solvent or the like may be used. Examples of the organic acid salt include octylate, neodecanoate, stearate, or naphthenate. If necessary, an organic acid salt of Ti may be added to the metal solution. Moreover, the thickness of the 1st coating film 20a can be adjusted by adjusting each content rate of Ca, Zr, and Ti in a metal solution.

  In the first embodiment, the content of the sintering aid in the metal solution is preferably 1000 ppm or less with respect to the metal element content in the metal solution. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor 2. In the first embodiment, even if the content of the sintering aid in the metal solution is 1000 ppm or less, the sufficiently sintered dielectric thin film 4 can be obtained by the main firing at a low temperature of 1000 ° C. or less. Is possible. Note that a sintering aid may be added to the metal solution as long as the effect of the present invention is not impaired.

  The sintering aid means, for example, the total amount of elements contained in the metal solution as impurities other than Ca, Zr, Ti and organic acid salts. Specific examples of sintering aids include alkali metals such as Na and K, alkaline earth metals such as Sr and Ba, transition metals such as Fe and Cr, rare earth elements such as La and Ce, and 13 such as Al and Ga. Group elements or Group 14 elements such as Si and Ge are listed. The content of each element contained in the metal solution as an impurity can be analyzed by ICP emission spectroscopic analysis or fluorescent X-ray analysis. Since the metal solution contains Zr as a raw material for the dielectric thin film 4, Hf, which is a similar element of Zr, is inevitably contained in the metal solution. Accordingly, in the first embodiment, Hf is not included in the sintering aid.

  By temporarily firing the first coating film 20a formed on the base electrode 6, the organic components in the first coating film 20a are thermally decomposed, and Ca, Zr, and Ti in the first coating film 20a are oxidized. . As a result, the first precursor layer 20 b is formed on the base electrode 6 as shown in FIG.

In the first embodiment, it is preferable that the first coating film 20a is temporarily fired in an oxidizing atmosphere such as air. Thus, in the sintering _step, the crystals of _{Ca m Zr 1-x Ti x} O 3 can be reliably generated. The first coating film 20a is preferably calcined at 400 to 600 ° C, more preferably calcined at 400 to 450 ° C. When the pre-baking temperature is too low, a part of the organic component in the first coating film 20a tends to remain in the first precursor layer 20a without being thermally decomposed. When the main firing step is performed on the first precursor layer 20a in which the organic component remains, the obtained dielectric layer becomes porous, and the density of the dielectric layer becomes low. As a result, the effect of the present invention of reducing the leakage current of the thin film capacitor 2 is reduced. If the pre-baking temperature is too high, the base electrode 6 tends to be oxidized. Although the time of temporary baking should just be adjusted suitably according to the thickness of the 1st coating film 20a, an area, etc., what is necessary is just to be about 5 to 30 minutes.

  As shown in FIG. 2C, a metal solution is applied to the entire surface of the first precursor layer 20b to form a second coating film 22a. Next, as shown in FIG. 2 (D), the second precursor 22a formed on the first precursor layer 20b is pre-fired by the same method as the first coat 20a, so that the second precursor is obtained. Layer 22b is formed on first precursor layer 20b.

  As described above, in the first laminating step, the first precursor layer 20b and the second precursor layer 22b are placed on the base electrode 6 by performing preliminary firing of the coating film formed from the metal solution twice on the base electrode. Laminate to.

<First main firing step>
In the first main firing step, the first precursor layer 20b and the second precursor layer 22b laminated on the base electrode 6 are subjected to main firing at 850 to 1000 ° C. By this firing, crystals of Ca _m Zr _1-x Ti _x O ₃ are grown in the first precursor layer 20b and the second precursor layer 22b, and the first dielectric layer 10 shown in FIG. It is formed on the electrode 6.

If the temperature of the main calcination is less than 850 ° _C., the crystal growth of _{Ca m Zr 1-x Ti x} O 3, sintering becomes insufficient, and there is a tendency that the effect of the present invention to suppress the leakage current decreases. On the other hand, when the temperature of the main baking is higher than 1000 ° C., a part of the base electrode 6 such as Ni evaporates and the effect of the present invention of suppressing the leakage current tends to be small.

In the first embodiment, the first precursor layer 20a and the second precursor layer 22b are preferably subjected to main firing in a vacuum atmosphere. Thereby, it becomes easy to grow a crystal of Ca _m Zr _1-x Ti _x O ₃ while suppressing oxidation of the base electrode 6. In the first embodiment, the vacuum atmosphere is, for example, a total pressure of about 1.0 × 10 ^{−3 to} 1.0 × 10 ¹ Pa and an oxygen partial pressure of 2.0 × 10 ⁻⁴ to 2. The atmosphere is about 0 Pa. The firing time may be about 5 minutes to 2 hours. Even if the firing atmosphere is an oxidizing atmosphere, a reducing atmosphere, or a neutral atmosphere, the thin film capacitor 2 can be obtained.

<Second lamination step>
In the second lamination step, as shown in FIG. 3A, a metal solution is applied to the entire surface of the first dielectric layer 10 to form a third coating film 30a by the same method as in the first lamination step. . Next, the third coating film 30a formed on the first dielectric layer 10 is temporarily fired by the same method as in the first lamination step. As a result, the third precursor layer 30b is formed on the first dielectric layer 10 as shown in FIG. And as shown in FIG.3 (C), a metal solution is apply | coated to the whole surface of the 3rd precursor layer 30b by the method similar to a 1st lamination process, and the 4th coating film 32a is formed. Next, the fourth coating film 32a formed on the third precursor layer 30b is temporarily fired by the same method as in the first lamination step. Thereby, as shown in FIG. 3D, the fourth precursor layer 32b is formed on the third precursor layer 30b.

<Second main firing step>
In the second main baking step, the third precursor layer 30a and the second precursor layer 32b laminated on the first dielectric layer 10 are main-fired by the same method as in the first main baking step. Accordingly, growing a crystal of _{Ca m Zr 1-x Ti x} O 3 in a third precursor layer 30b and the second precursor layer 22b in. As a result, as shown in FIG. 3E, the dielectric thin film 4 having the laminated first dielectric layer 10 and second dielectric layer 12 and having a thickness of 200 to 1000 nm is applied to the base electrode 6. Form on top. Then, by forming the upper electrode 8 on the dielectric thin film 4, the thin film capacitor 2 is completed in FIG. In the second main firing step, a planar interface 14 is formed between the first dielectric layer 10 and the second dielectric layer 12.

  The thickness of the dielectric thin film 4 may be 200 to 1000 nm by adjusting the thickness of each dielectric layer. The thickness of each dielectric layer may be adjusted according to the thickness of each precursor layer. What is necessary is just to adjust the thickness of each precursor layer with the thickness of each coating film.

  In the first embodiment, a dielectric thin film is formed by forming a coating film using a solution method and alternately performing a lamination process and a main baking process twice. Therefore, the first manufacturing method does not require an expensive apparatus required for performing a film forming method such as a plasma CVD method, an electron cyclotron (ECR) plasma CVD method, or a plasma sputtering method as in the conventional manufacturing method. Therefore, the thin film capacitor 2 can be manufactured at low cost.

Conventionally, Ca (Zr, Ti) O ₃ crystallizes more rapidly during main firing than other dielectric compositions, and therefore, a dielectric thin film containing Ca (Zr, Ti) O _{3 and} having a small leakage current is used at a low temperature. It was difficult to form by the main firing at. However, in the first embodiment, a coating film is formed using a solution method, and the lamination process and the main baking process at 850 to 1000 ° C. are alternately performed twice, respectively. _{Ca m Zr 1-x Ti x} O 3 of possible suppress an abrupt crystal growth. Therefore, in the first _embodiment, it comprises a _{Ca m Zr 1-x Ti x} O 3, the thickness it is possible to form a dielectric thin film 4 is 200 to 1000 nm.

[Second Embodiment]
As a second embodiment, a case where the thin film capacitor 2 is manufactured using the above-described second manufacturing method will be described. In addition, below, description is abbreviate | omitted about the common matter of 1st embodiment and 2nd embodiment, and only those differences are demonstrated.

In the method of manufacturing a thin film capacitor according to the second embodiment, a lamination step of laminating one or more precursor layers on the electrode by performing temporary firing of the coating film formed from the metal solution once or more on the electrode; And a main firing step of firing one or more precursor layers laminated on the electrode to form a dielectric layer on the electrode, and adjusting the Ti content in the metal solution to 0 mol or more and, adjusting Zr ratio _M Ca _/ number of moles _{M Zr} and Ti moles _M moles of Ca to the sum of _{Ti M Ca} of the (M Zr _{+ M Ti)} to 0.9 to 1.1, baked in a solution The content of the binder is adjusted to 1000 ppm or less with respect to the metal element content in the solution.

  In the second embodiment, it is possible to suppress the leakage current of the thin film capacitor 2 by deliberately reducing the amount of the sintering aid to be used as compared with the conventional manufacturing method. Further, in the second embodiment, even when the content of the sintering aid in the metal solution is less than the conventional case, or even when the metal solution does not contain the sintering aid, firing at 1000 ° C. or less. Thus, the dielectric thin film 4 can be sufficiently sintered.

  In the second embodiment, the precursor layer is preferably subjected to main baking at 850 to 1000 ° C. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor 2.

  In the second embodiment, the lamination process and the main baking process are alternately performed twice or more, whereby a dielectric thin film having two or more laminated dielectric layers and having a thickness of 200 to 1000 nm is formed as an electrode. It is preferable to provide the thin film formation process formed on top. Thereby, it becomes easy to suppress the leakage current of the thin film capacitor 2.

[Third embodiment]
Below, description is abbreviate | omitted about the common matter of 1st embodiment and 3rd embodiment, and only those differences are demonstrated.

  In the first embodiment, two laminated precursor layers are fired at a time to form one dielectric layer. In the third embodiment, one precursor layer is fired to produce one dielectric layer. A body layer is formed.

  That is, the thin film capacitor manufacturing method according to the third embodiment is a lamination process in which one precursor layer is laminated on the base electrode by performing temporary firing of the coating film formed from the metal solution once on the base electrode. And a main firing step of firing one precursor layer laminated on the base electrode at 850 to 1000 ° C. to form one dielectric layer on the base electrode, and a stacking step and a main firing step alternately. A thin film forming step of forming a dielectric thin film having a thickness of 200 to 1000 nm on the base electrode, the first dielectric layer and the second dielectric layer being laminated, Is provided. A thin film capacitor is obtained by forming an upper electrode on the dielectric thin film. Hereinafter, each process is demonstrated using FIG.

  In the thin film formation step of the third embodiment, the following first lamination step, first main baking step, second lamination step, and second main baking step are performed.

<First lamination process>
In the first lamination step, as shown in FIG. 4A, a metal solution is applied to the entire surface of the base electrode 6 to form a first coating film 10a. And the 1st precursor layer 10b is formed on the base electrode 6 as shown in FIG.4 (B) by temporarily baking the 1st coating film 10a formed on the base electrode 6. FIG.

<First main firing step>
In the first main baking step, the first precursor layer 10b laminated on the base electrode 6 is main-baked. Thereby, the first dielectric layer 10 c shown in FIG. 4C is formed on the base electrode 6.

<Second lamination step>
As shown in FIG. 4D, a metal solution is applied to the entire surface of the first dielectric layer 10c to form a second coating film 12a. Next, the second precursor 12a formed on the first dielectric layer 10c is temporarily fired by the same method as that for the first coating 10a, so that the second precursor as shown in FIG. A layer 12b is formed on the first dielectric layer 10c.

<Second main firing step>
In the second main firing step, the first dielectric layer 10c laminated by subjecting the second precursor layer 12b laminated on the first dielectric layer 10c to main firing in the same manner as in the first main firing step. And a second dielectric layer 12c, and a dielectric thin film 4c having a thickness of 200 to 1000 nm is formed on the base electrode 6. Then, by forming the upper electrode 8 on the dielectric thin film 4c, the thin film capacitor 2c is completed as shown in FIG. In the second main firing step, a planar interface 14c is formed between the first dielectric layer 10c and the second dielectric layer 12c.

  Also in the thin film capacitor 2c according to the third embodiment, the leakage current can be suppressed as compared with the conventional thin film capacitor, as in the first embodiment and the second embodiment.

  The preferred embodiments of the thin film capacitor and the thin film capacitor manufacturing method according to the present invention have been described above, but the present invention is not necessarily limited to the above-described embodiment.

  For example, three or more precursor layers may be stacked on the base electrode in the stacking step, and the stacking step and the main firing step are alternately performed three times or more, and three or more dielectric layers are stacked. A dielectric thin film may be formed. In any case, the thickness of the dielectric thin film 4 can be controlled within the range of 200 to 1000 nm by appropriately setting the thickness of each dielectric layer or the number of laminated dielectric layers. The thickness of each dielectric layer can be controlled by the thickness of each precursor layer or the number of stacked precursor layers. The thickness of each precursor layer can be controlled by the thickness of each coating film or the concentration of each organic acid salt of Ca, Zr, and Ti in the metal solution.

  The thin film capacitor may include a plurality of internal electrodes stacked via a plurality of dielectric thin films. When manufacturing such a thin film capacitor, after forming the dielectric thin film on the base electrode, the process of forming the internal electrode on the dielectric thin film and the process of forming the thin film on the internal electrode can be repeated alternately several times. That's fine. By repeating this process, the internal electrodes and the dielectric thin films are alternately stacked, and then the upper electrode is formed on the dielectric thin film located on the opposite side of the base electrode in the stacking direction. A thin film capacitor with electrodes is obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

Example 1
<Lamination process>
In Example 1, Ni foil having a thickness of 30 μm was used as the base electrode. A metal solution was applied to the entire surface of the Ni foil treated by CMP by spin coating to form a first coating film. The spin coating was performed for 20 seconds under the condition of 3000 rpm. As the metal solution, a solution obtained by dissolving octylates of Ca and Zr in butanol was used. The contents of octylates of Ca and Zr in the metal solution were adjusted so that _MCa / ( _MZr + _MTi ) was 0.9. Further, the content of Ti in the metal solution was 0 mol. That is, M _Ti / (M _Zr + M _Ti ) was set to 0. In Example 1, no impurity functioning as a sintering aid was added to the metal solution. Therefore, the content of impurities contained in the metal solution of ICP emission spectroscopic analysis was about 900 ppm with respect to the content of metal element in the metal solution.

  The first coating film was pre-baked in a tubular furnace for 10 minutes to form a first precursor layer having a thickness of about 50 nm on the Ni foil. In addition, temporary baking of the coating film was performed in the 400 degreeC air | atmosphere.

As in the case of the first coating film, a metal solution is applied onto the first precursor layer by spin coating to form a second coating film, and then the second coating film is pre-baked to obtain a thickness of 50 nm. A second precursor layer of the same degree was formed. Thereby, the thickness of the 1st precursor layer laminated | stacked on Ni foil and the 2nd precursor layer was 100 nm. In the following. The total thickness of the precursor layers laminated in one laminating process is denoted as “T _L ”.

  As described above, in the lamination process of Example 1, two precursor layers were laminated on the Ni foil.

<Main firing process>
The first precursor layer and the second precursor layer laminated on the Ni foil are placed in an infrared heating furnace, the inside of the furnace is depressurized using a vacuum pump, and the pressure in the furnace measured by an ionization vacuum gauge at room temperature is set. The pressure was adjusted to 0.01 Pa. And the temperature in a furnace was heated up to 900 degreeC, continuing the pressure_reduction | reduced_pressure by a vacuum pump. The first precursor layer and the second precursor layer laminated on the Ni foil were subjected to main firing for 30 minutes while maintaining the temperature in the furnace at 900 ° C. Thereby, a dielectric layer having a thickness of about 100 nm was formed on the Ni foil. Hereinafter, the temperature in the furnace at the time of the main baking is referred to as “main baking temperature”.

  As described above, in the main firing step of Example 1, one dielectric layer was formed on Ni by subjecting two stacked precursor layers to main firing.

<Thin film formation process>
In the thin film formation process of Example 1, the above-described lamination process and the main baking process were alternately performed three times, so that three dielectric layers were laminated on the Ni foil. Thus, a dielectric thin film having three laminated dielectric layers and a thickness of 300 nm was formed on the Ni foil. Then, a Cu electrode was formed on the dielectric thin film as the upper electrode, and the thin film capacitor of Example 1 was obtained. The upper electrode was formed by sputtering. Hereinafter, the thickness of the dielectric thin film is referred to as “T _F ”.

<Composition of dielectric thin film>
As a result of analysis by XRF, it was confirmed that the dielectric thin film of Example 1 was represented by the following chemical formula (1a).
Ca _0.9 ZrO ₃ (1a)

<Measurement of capacitance and leakage current>
The capacitance and leakage current of the thin film capacitor of Example 1 were measured. In addition, the relative dielectric constant ε _r was calculated from the capacitance of Example 1. Table 1 shows _εr and leakage current of Example 1.

An LCR meter (manufactured by Agilent Technologies, trade name: YHP-4284A) was used for the measurement of capacitance. In the measurement of capacitance, an AC voltage having a frequency of 1 MHz and an effective value of 1 V was applied between the base electrode and the upper electrode while maintaining the temperature of the dielectric thin film at 25 ° C. . Hereinafter, it referred the capacitance obtained in this manner with C _25.

  A semiconductor parameter analyzer (manufactured by Agilent Technologies, trade name: 4156C) was used for measuring the leakage current. In the measurement of leakage current, a voltage of 4 V was applied between the base electrode and the upper electrode while maintaining the temperature of the dielectric thin film at 25 ° C.

<Measurement of temperature coefficient>
The capacitance C ₁₂₅ in a state where the temperature of the dielectric thin film was maintained at 125 ° C. was measured by the same method as C ₂₅ described above. And the temperature coefficient (tau) _c of the electrostatic capacitance defined by a following formula (A) was computed. Table 1 shows τ _c of Example 1.
τ _c = 10 ⁶ × (C ₁₂₅ −C ₂₅ ) / {C ₂₅ × (125 ° C.-25 ° C.)} (A)

(Examples 2 to 5, Comparative Examples 1 and 2)
The thin film capacitors of Examples 2 to 5 and Comparative Examples 1 and 2 were produced in the same manner as in Example 1 except that the dielectric thin film having the composition shown in Table 1 was formed. Then, ε _r , leakage current, and τ _c of each thin film capacitor of Examples 2 to 5 and Comparative Examples 1 and 2 were determined in the same manner as in Example 1. The results are shown in Table 1. In Table 1, m is equal to M _Ca / (M _Zr + M _Ti ) in the metal solution, and x in Table 1 is equal to M _Ti / (M _Zr + M _Ti ) in the metal solution.

  As shown in Table 1, in Examples 1 to 5 where m is 0.9 to 1.1, it was confirmed that the leakage current was smaller than those of Comparative Examples 1 and 2.

  In Comparative Examples 1 and 2, the cause of the increase in the leakage current compared to the Example is that in Comparative Examples 1 and 2, the deviation of m from the composition satisfying the stoichiometric ratio (composition when m = 1). The present inventors consider that this is due to the fact that Ca oxide, Zr oxide, or Ti oxide is generated in the dielectric thin film.

  A cross section in the stacking direction of the dielectric thin film of Example 3 was photographed with a scanning electron microscope (SEM). The obtained SEM image is shown in FIG. As shown in FIG. 5, it was confirmed that the dielectric thin film 4d includes a first dielectric layer 10d, a second dielectric layer 12d, and a third dielectric layer 16d laminated on the Ni foil 6d. The first dielectric layer 10d is a layer formed in the first main firing step. The second dielectric layer 12d is a layer formed in the second main firing step. The third dielectric layer 16d is a layer formed in the third main firing step. In the cross section, a streak boundary line (a part of the interface) 14d was observed between the second dielectric layer 12d and the third dielectric layer 16d. That is, it was confirmed that a planar interface 14d was formed between the second dielectric layer 12d and the third dielectric layer 16d. In Examples 1, 2, 4, and 5, it was confirmed that a planar interface was formed between the dielectric layers.

(Comparative Example 3)
A thin film capacitor of Comparative Example 3 was produced in the same manner as in Example 3 except that the main firing temperature was maintained at 1200 ° C. In the same manner as in Example 3, a cross section in the stacking direction of the dielectric thin film of Comparative Example 3 was photographed with a scanning electron microscope (SEM).

  A schematic diagram of a cross section of the second dielectric layer 12d and the third dielectric layer 16d included in the dielectric thin film of Example 3 was produced based on the SEM image described above. A schematic diagram of Example 3 is shown in FIG. Moreover, the schematic of the cross section of the 2nd dielectric material layer with which the dielectric material thin film of the comparative example 3 is equipped, and the 3rd dielectric material layer was produced based on the above-mentioned SEM image. A schematic diagram of Comparative Example 3 is shown in FIG.

  As shown in FIG. 6A, in Example 3, the dielectric particles grown in the second dielectric layer 12d in the second main firing step and the third dielectric layer in the third main firing step. It was confirmed that the dielectric particles of the film grown in 16d were in close contact at the interface 14d. In addition, it was confirmed that the dielectric particles of Example 3 did not grow in the film thickness direction as compared with the dielectric particles of Comparative Example 3 shown in FIG. Further, it was confirmed that each dielectric layer of Example 3 was denser than each dielectric layer of Comparative Example 3.

  As shown in FIG. 6B, in Comparative Example 3 where the main firing temperature is 1200 ° C., an interface as in Example 3 is formed at the boundary 14e between the second dielectric layer 12e and the third dielectric layer 16e. That the dielectric particles are growing in the film thickness direction as compared with Example 3, and that the dielectric particles are growing in the film thickness direction so as to cross the boundary 14e. Was confirmed. Therefore, in Comparative Example 3, it was confirmed that the gap tends to be easily formed along the film thickness direction at the grain boundary. In the main baking process, a part of the Ni foil is deposited in the gap, which causes a short circuit between the electrodes and a deterioration of leak characteristics.

(Examples 6 to 15)
The thin film capacitors of Examples 6 to 15 were produced in the same manner as in Example 3 except that a dielectric thin film having the composition shown in Table 2 was formed. Then, ε _r , leakage current, and τ _c of each thin film capacitor of Examples 6 to 15 were obtained by the same method as in Example 1. The results are shown in Table 2. Note that m shown in Table 2 is equal to M _Ca / (M _Zr + M _Ti ) in the metal solution, and x shown in Table 2 is equal to M _Ti / (M _Zr + M _Ti ) in the metal solution.

As shown in Table 2, τ _c of Examples 6 to 15 where 0 ≦ x ≦ 0.2 is −250 to 23 ppm / ° C., and it was confirmed that CK of EIA standard was satisfied.

(Examples 16 to 19, Comparative Examples 4 and 5)
The thin film capacitors of Examples 16 to 19 and Comparative Examples 4 and 5 were produced in the same manner as in Example 3 except that the main firing temperature was changed to the temperature shown in Table 3. Then, ε _r , leakage current, and τ _c of each thin film capacitor of Examples 16 to 19 and Comparative Examples 4 and 5 were obtained in the same manner as in Example 1. The results are shown in Table 3.

(Examples 20 to 23, Comparative Examples 6 and 7)
In Examples 20 to 23 and Comparative Examples 6 and 7, the main firing temperature was set to the temperature shown in Table 3. In Examples 20 to 23 and Comparative Examples 6 and 7, one precursor layer having a thickness of 50 nm is formed in one lamination process, and the lamination process and the main baking process are alternately performed six times. Thus, a dielectric thin film having six laminated dielectric layers and having a thickness of 300 nm was formed.

Except for the above items, the thin film capacitors of Examples 20 to 23 and Comparative Examples 6 and 7 were produced in the same manner as in Example 3. Then, ε _r , leakage current, and τ _c of each thin film capacitor of Examples 20 to 23 and Comparative Examples 6 and 7 were determined in the same manner as in Example 1. The results are shown in Table 3.

  As shown in Table 3, it was confirmed that the leakage currents of Examples 16 to 23 having a main baking temperature of 850 to 1000 ° C. were smaller than those of Comparative Examples 4 to 7.

  In Comparative Examples 4 and 6 where the main firing temperature is less than 850 ° C., the dielectric thin film was insufficiently crystallized, so that the leakage current was larger than that of the example. In Comparative Examples 5 and 7 where the main baking temperature was higher than 1000 ° C., the leakage current was larger than that of the Example because the Ni foil evaporated during the main baking.

(Example 24)
In Example 24, two layers of a precursor layer having a thickness of 50 nm are laminated on Ni foil by performing coating film formation and temporary firing twice in one lamination step, and then the lamination step and main firing. By alternately performing the process twice, two dielectric layers having a thickness of 100 nm were stacked, and a dielectric thin film having a thickness of 200 nm was formed on the Ni foil.

  A thin film capacitor of Example 24 was produced in the same manner as in Example 3 except for the above items.

(Example 25)
In Example 25, a single precursor layer having a thickness of 50 nm is formed in one laminating process, and the laminating process and the main firing process are alternately performed four times, whereby a dielectric having a thickness of 50 nm is formed. Four body layers were laminated to form a dielectric thin film having a thickness of 200 nm.

  A thin film capacitor of Example 25 was produced in the same manner as in Example 3 except for the above items.

(Example 26)
In Example 26, one precursor layer having a thickness of 20 nm is formed in one lamination step, and the dielectric layer having a thickness of 20 nm is formed by alternately performing the lamination step and the main firing step 10 times. Ten layers were laminated to form a dielectric thin film having a thickness of 200 nm.

  A thin film capacitor of Example 26 was produced in the same manner as in Example 3 except for the above items.

(Comparative Example 8)
In Comparative Example 8, four layers of a precursor layer having a thickness of 50 nm were laminated on a Ni foil by performing coating film formation and temporary firing four times in one lamination step, and the thickness was 200 nm. One precursor layer was formed. In Comparative Example 8, a dielectric thin film having a thickness of 200 nm was formed by performing the laminating step and the main firing step once. That is, the dielectric thin film of Comparative Example 8 corresponds to one dielectric layer laminated on the Ni foil.

  A thin film capacitor of Comparative Example 8 was produced in the same manner as in Example 3 except for the above items.

(Example 27)
In Example 27, the formation of the coating film and the pre-baking were each performed three times in a single lamination step, whereby three precursor layers having a thickness of 50 nm were laminated on the Ni foil. By alternately performing the main firing step twice, two dielectric layers having a thickness of 150 nm were stacked, and a dielectric thin film having a thickness of 300 nm was formed on the Ni foil.

  A thin film capacitor of Example 27 was produced in the same manner as in Example 3 except for the above items.

(Example 28)
In Example 28, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination step. By alternately performing the main firing step three times, three dielectric layers having a thickness of 100 nm were stacked, and a dielectric thin film having a thickness of 300 nm was formed on the Ni foil.

  A thin film capacitor of Example 28 was produced in the same manner as in Example 3 except for the above items.

(Example 29)
In Example 29, one precursor layer having a thickness of 50 nm is formed in one laminating process, and the laminating process and the main firing process are alternately performed 6 times, whereby a dielectric having a thickness of 50 nm is formed. Six layers were laminated to form a dielectric thin film having a thickness of 300 nm.

  A thin film capacitor of Example 29 was produced in the same manner as in Example 3 except for the above items.

(Comparative Example 9)
In Comparative Example 9, six layers of a precursor layer having a thickness of 50 nm were stacked on a Ni foil by performing coating film formation and provisional baking six times in one lamination step, and the thickness was 300 nm. One precursor layer was formed. In Comparative Example 9, a dielectric thin film having a thickness of 300 nm was formed by performing the laminating step and the main firing step once. That is, the dielectric thin film of Comparative Example 9 corresponds to one dielectric layer laminated on the Ni foil.

  A thin film capacitor of Comparative Example 9 was produced in the same manner as in Example 3 except for the above items.

(Example 30)
In Example 30, six layers of the precursor layer having a thickness of 50 nm were laminated on the Ni foil by performing coating film formation and temporary firing six times in one lamination step, respectively. By alternately performing the firing step twice, two dielectric layers having a thickness of 300 nm were stacked, and a dielectric thin film having a thickness of 600 nm was formed on the Ni foil.

  A thin film capacitor of Example 30 was produced in the same manner as in Example 3 except for the above items.

(Example 31)
In Example 31, a precursor layer having a thickness of 50 nm is laminated on a Ni foil by performing coating film formation and temporary firing four times in one lamination step, and the lamination step is performed. By alternately performing the main firing step three times, three dielectric layers having a thickness of 200 nm were stacked, and a dielectric thin film having a thickness of 600 nm was formed on the Ni foil.

  A thin film capacitor of Example 31 was produced in the same manner as in Example 3 except for the above items.

(Example 32)
In Example 32, two layers of a precursor layer having a thickness of 50 nm were laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination step. By alternately performing the firing process six times, six dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 600 nm.

  A thin film capacitor of Example 32 was produced in the same manner as in Example 3 except for the above items.

(Comparative Example 10)
In Comparative Example 10, a precursor layer having a thickness of 50 nm is laminated on a Ni foil by performing coating film formation and provisional baking 12 times each in a single lamination step, and the thickness is 600 nm. One precursor layer was formed. In Comparative Example 10, a dielectric thin film having a thickness of 600 nm was formed by performing the lamination process and the main baking process once. That is, the dielectric thin film of Comparative Example 10 corresponds to one dielectric layer laminated on the Ni foil.

  Except for the above, a thin film capacitor of Comparative Example 10 was produced in the same manner as in Example 3.

Ε _r , leakage current, and τ _c of each thin film capacitor of Examples 24-32 and Comparative Examples 8-10 were determined in the same manner as in Example 1. The results are shown in Table 4.

  As shown in Table 4, the leakage current of Examples 24-32 in which the dielectric thin film provided with two or more dielectric layers was formed by performing the main baking step twice or more is only one main baking step. Thus, it was confirmed to be smaller than Comparative Examples 8 to 10 in which a dielectric thin film composed of one dielectric layer was formed.

  When the cross section in the lamination direction of the thin film capacitor of Examples 24-32 was observed with SEM, the streak-like boundary line existed in the cross section. That is, in Examples 24-32, it was confirmed that a planar interface was formed between the dielectric layers.

  On the other hand, when the cross section in the lamination direction of the thin film capacitors of Comparative Examples 8 to 10 was observed with an SEM, only a streak boundary line was present in the cross section. That is, it was confirmed that no interface exists in the dielectric thin films of Comparative Examples 8 to 10. In the dielectric thin films of Comparative Examples 8 to 10, the dielectric particles grow in the film thickness direction, and the interface between the dielectric particles becomes longer in the film thickness direction. Is considered.

(Example 33)
In Example 33, two layers of a precursor layer having a thickness of 50 nm are stacked on the Ni foil by performing coating film formation and temporary firing twice each in a single stacking process. By alternately performing the firing process twice, two dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 200 nm.

  A thin film capacitor of Example 33 was produced in the same manner as in Example 3 except for the above items.

(Example 34)
In Example 34, a coating layer was formed and pre-baked twice in a single laminating step, whereby two precursor layers having a thickness of 50 nm were laminated on the Ni foil. By alternately performing the firing process three times, three dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 300 nm.

  A thin film capacitor of Example 34 was produced in the same manner as in Example 3 except for the above items.

(Example 35)
In Example 35, two layers of a precursor layer having a thickness of 50 nm are stacked on the Ni foil by performing coating film formation and temporary firing twice each in a single stacking process. By alternately performing the firing process four times, four dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 400 nm.

  A thin film capacitor of Example 35 was produced in the same manner as in Example 3 except for the above items.

(Example 36)
In Example 36, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination step. By alternately performing the firing process five times, five dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 500 nm.

  A thin film capacitor of Example 36 was produced in the same manner as in Example 3 except for the above items.

(Example 37)
In Example 37, a coating layer is formed and pre-baked twice each in a single laminating step, whereby two precursor layers having a thickness of 50 nm are laminated on the Ni foil. By alternately performing the firing process six times, six dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 600 nm.

  A thin film capacitor of Example 37 was produced in the same manner as in Example 3 except for the above items.

(Example 38)
In Example 38, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination step. By alternately performing the firing process seven times, seven dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 700 nm.

  A thin film capacitor of Example 38 was produced in the same manner as in Example 3 except for the above items.

(Example 39)
In Example 39, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary baking twice each in a single lamination step. By alternately performing the firing process eight times, eight dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 800 nm.

  A thin film capacitor of Example 39 was produced in the same manner as in Example 3 except for the above items.

(Example 40)
In Example 40, a coating layer was formed and pre-baked twice each in a single laminating step, whereby two precursor layers having a thickness of 50 nm were laminated on the Ni foil. Nine dielectric layers having a thickness of 100 nm were stacked by alternately performing the firing process nine times to form a dielectric thin film having a thickness of 900 nm.

  A thin film capacitor of Example 40 was produced in the same manner as in Example 3 except for the above items.

(Example 41)
In Example 41, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination process. By alternately performing the firing process 10 times, 10 dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 1000 nm.

  A thin film capacitor of Example 41 was produced in the same manner as in Example 3 except for the above items.

(Comparative Example 11)
In Comparative Example 11, two precursor layers each having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination process. By alternately performing the firing process once, a dielectric thin film having a thickness of 100 nm and having a single dielectric layer was formed.

  Except for the above, a thin film capacitor of Comparative Example 11 was produced in the same manner as in Example 3.

(Comparative Example 12)
In Comparative Example 12, two layers of a precursor layer having a thickness of 50 nm are laminated on the Ni foil by performing coating film formation and temporary firing twice each in a single lamination step. By alternately performing the firing process 11 times, 11 dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 1100 nm.

  Except for the above, a thin film capacitor of Comparative Example 12 was produced in the same manner as in Example 3.

(Comparative Example 13)
In Comparative Example 13, two layers of a precursor layer having a thickness of 50 nm are stacked on the Ni foil by performing coating film formation and temporary firing twice each in a single stacking process. By alternately performing the firing process 20 times, 20 dielectric layers having a thickness of 100 nm were stacked to form a dielectric thin film having a thickness of 2000 nm.

  A thin film capacitor of Comparative Example 13 was produced in the same manner as in Example 3 except for the above items.

Ε _r , leakage current, and τ _c of each thin film capacitor of Examples 33 to 41 and Comparative Examples 12 and 13 were obtained in the same manner as in Example 1. The results are shown in Table 5.

  As shown in Table 5, it was confirmed that the leakage currents of Examples 33 to 41 in which the thickness of the dielectric thin film was 200 to 1000 nm were smaller than those of Comparative Examples 12 and 13.

  In Comparative Example 11 where the thickness of the dielectric thin film was less than 200 nm, a short circuit defect occurred. When a cross section in the stacking direction of the thin film capacitor of Comparative Example 11 was observed with an SEM, it was confirmed that dielectric particles having a diameter of 100 nm were formed in the dielectric thin film. Thus, in Comparative Example 11, since the diameter of the dielectric particles and the thickness of the dielectric thin film are the same, the plurality of dielectric particles do not overlap in the film thickness direction of the dielectric thin film, and each particle is independent. It was confirmed that it was arranged in. In Comparative Example 11, there was a gap between the dielectric particles because the diameter of the dielectric particles was large. The present inventors consider that a short defect has occurred due to this gap.

  When a cross section in the stacking direction of each thin film capacitor of Comparative Examples 12 and 13 was observed with an SEM, a large number of cracks were formed in the dielectric thin film, and the leakage currents of Comparative Examples 12 and 13 were caused by the cracks. The present inventors think that it became large compared with the Example.

(Example 42)
The thin film capacitor of Example 42 in the same manner as in Example 3 except that the content of the sintering aid (impurities) contained in the metal solution was adjusted to 1100 ppm with respect to the metal element content in the metal solution. Was made.

(Example 43)
In Example 43, the formation of the coating film and the pre-baking were each performed 6 times in one laminating process, thereby stacking 6 precursor layers having a thickness of 50 nm on the Ni foil. Each of the firing steps was performed once. Thus, in Example 43, a dielectric thin film having a thickness of 300 nm was formed on the Ni foil. That is, the dielectric thin film of Example 43 corresponds to one dielectric layer.

  A thin film capacitor of Example 43 was produced in the same manner as in Example 3 except for the above items.

(Example 44)
A thin film capacitor of Example 44 was produced in the same manner as in Example 3.

(Comparative Example 14)
The thin film capacitor of Comparative Example 14 in the same manner as in Example 43, except that the content of the sintering aid (impurities) contained in the metal solution was adjusted to 1100 ppm with respect to the metal element content in the metal solution. Was made.

Ε _r , leakage current, and τ _c of each thin film capacitor of Examples 42 to 44 and Comparative Example 14 were determined in the same manner as in Example 1. The results are shown in Table 6.

  As shown in Table 6, the leakage current of Comparative Example 14 in which a dielectric thin film was formed by including 1100 ppm of a sintering aid in the metal solution and performing the lamination step and the main firing step once was It was confirmed that it was larger than Examples 42-44.

  2, 2c: Thin film capacitor, 4, 4c, 4d: Dielectric thin film, 6, 6d: Base electrode, 8: Upper electrode, 10, 10c, 10d, 12, 12c, 12d, 16d ... Dielectric layer, 14, 14c ... Interface, 10a, 12a, 20a, 22a, 30a, 32a ... Coating film, 10b, 12b, 20b, 22b, 30b, 32b ... Precursor layer.

Claims (7)

A dielectric thin film comprising a dielectric composition represented by the following chemical formula (1) and having a thickness of 200 to 1000 nm;
A pair of electrodes sandwiching the dielectric thin film therebetween;
A thin film capacitor comprising:
_{Ca m Zr 1-x Ti x} O 3 (1)
[In the chemical formula (1), 0.9 ≦ m ≦ 1.1 and 0 ≦ x <1. ] The dielectric thin film comprises at least two dielectric layers substantially parallel to the electrode;
A planar interface is formed between the two dielectric layers;
The thin film capacitor according to claim 1. A laminating step of laminating one or more precursor layers on the electrode by performing calcining of the coating film formed from a solution of Ca and Zr once or more on the electrode;
A main firing step in which one or more of the precursor layers laminated on the electrode are fired at 850 to 1000 ° C. to form a dielectric layer on the electrode;
By alternately performing the laminating step and the main firing step twice or more, a dielectric thin film having two or more laminated dielectric layers and having a thickness of 200 to 1000 nm is formed on the electrode. A thin film forming step to be formed,
The Ti content in the solution is 0 mol or more,
The ratio M _Ca / (M _Zr + M _Ti ) of the mole number M _Ca of the Ca to the sum of the mole number M _{Zr of the Zr} and the mole number M _Ti of the _{Ti is set} to 0.9 to 1.1.
Manufacturing method of thin film capacitor. The content of the sintering aid in the solution is 1000 ppm or less with respect to the metal element content in the solution.
A method for manufacturing the thin film capacitor according to claim 3. A laminating step of laminating one or more precursor layers on the electrode by performing calcining of the coating film formed from a solution of Ca and Zr once or more on the electrode;
A main firing step of firing one or more of the precursor layers stacked on the electrode to form a dielectric layer on the electrode, and
The Ti content in the solution is 0 mol or more,
The ratio M _Ca / (M _Zr + M _Ti ) of the number of moles of _Ca M _Ca to the sum of the number of moles of _Zr M _Zr and the number of moles of _Ti M _Ti is 0.9 to 1.1,
The content of the sintering aid in the solution is 1000 ppm or less with respect to the metal element content in the solution.
Manufacturing method of thin film capacitor.   The method for manufacturing a thin film capacitor according to claim 5, wherein in the main firing step, the precursor layer is subjected to main firing at 850 to 1000 ° C. 6. By alternately performing the laminating step and the main firing step twice or more, a dielectric thin film having two or more laminated dielectric layers and having a thickness of 200 to 1000 nm is formed on the electrode. The manufacturing method of the thin film capacitor of Claim 5 or 6 provided with the thin film formation process to form.