JP5267251B2 - Thin film capacitor and method of manufacturing thin film capacitor - Google Patents

Description

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

  Conventionally, a discrete capacitor connects the power supply and the power supply terminal of the integrated circuit to suppress electromagnetic interference (EMI) caused by fluctuations in the power supply voltage of the integrated circuit (LSI: Large Scale Integration). Placed on the wiring to be. The capacitor for such use is required to be thinned and devised in arrangement with recent miniaturization of electronic devices. For example, a thin film capacitor as shown in Patent Document 1 or Non-Patent Document 1 below is required. It is generally performed that an array is formed in a thin film sheet, and the sheet is directly attached to the surface of the interposer or the printed board, or a thin film capacitor is embedded in the interposer or the printed board. In addition to the use for suppressing EMI, a thin film capacitor for other uses may be directly attached to the surface of the interposer or the printed board, or may be embedded in the interposer or the printed board.

JP 2001-217142 A

CARTS Europe 2006 proceedings pp273-280

  The above thin film capacitor requires a large capacitance as well as a thin dielectric layer. Conventionally, a dielectric material having a high relative dielectric constant is used for the dielectric layer, and the capacitance of the dielectric layer is conventionally Increase the density. Currently, for example, a dielectric material having a dielectric constant of 200 to 1000 is used for the dielectric layer. When forming a dielectric layer from such a dielectric material, it is necessary to anneal (fire) the layered dielectric material at a high temperature of 800 ° C. or higher to crystallize the dielectric. . Therefore, as shown in Non-Patent Document 1, Si having high heat resistance is used as the substrate of the thin film capacitor, and Pt having low reactivity is used as the base electrode, the internal electrode, and the upper electrode. In order to further increase the capacity of such a thin film capacitor, it is effective to stack a plurality of dielectric layers via internal electrodes. For example, the maximum capacity of a 1005 size thin film capacitor is 15.5 nF when the number of dielectric layers is one, 28 nF when the number of dielectric layers is two, and the number of dielectric layers is three. 40 nF.

  However, a conventional thin film capacitor including a substrate made of Si, a base electrode made of Pt, an internal electrode, and an upper electrode cannot always obtain a sufficient capacitance. For example, in a 1005 size thin film capacitor having three dielectric layers, a capacitance exceeding 40 nF or 50 nF has not been obtained. Therefore, it has been required to increase the capacitance of the thin film capacitor.

  Further, in a conventional thin film capacitor including a substrate made of Si, a base electrode made of Pt, an internal electrode, and an upper electrode, the leakage current tends to increase as the thickness is reduced. Therefore, it has also been demanded to suppress the leakage current of the thin film capacitor.

  Furthermore, conventional thin film capacitors are manufactured using expensive materials such as Si and Pt. In addition, since the base electrode, the internal electrode, and the upper electrode are made of Pt, it is necessary to pattern a large number of stacked internal electrodes and upper electrodes by dry etching, which requires special manufacturing equipment for a dry process. Furthermore, it takes time to dry-etch the internal electrodes. For these reasons, the raw material costs and manufacturing costs of conventional thin film capacitors are high. Therefore, there has been a demand for reducing raw material costs and manufacturing costs of thin film capacitors.

  Accordingly, the present invention has been made in view of the above problems, and provides an inexpensive thin film capacitor and a thin film capacitor manufacturing method that can increase capacitance, reduce leakage current, and the like. The purpose is to do.

  As a result of diligent research, the inventor has been able to increase electrostatic capacity and increase leakage current by the synergistic effect of the composition of each electrode material included in the base electrode, internal electrode, and upper electrode included in the thin film capacitor. It was found that the cost of the thin film capacitor can be reduced and the present invention described below has been achieved.

  In order to achieve the above object, a thin film capacitor of the present invention includes a base electrode composed mainly of Ni, two or more dielectric layers stacked on the base electrode, and a stack between the dielectric layers. An internal electrode containing Ni as a main component and further containing at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag, a dielectric layer, and an internal And an upper electrode made of Cu or a Cu alloy, which is laminated on the opposite side of the base electrode with the electrode interposed therebetween.

  According to the thin film capacitor of the present invention, the capacitance can be increased as compared with a conventional thin film capacitor having a substrate made of Si, a base electrode made of Pt, an internal electrode and an upper electrode, and leakage The current can be reduced. The thin film capacitor of the present invention includes an internal electrode made of a Ni-based metal that is cheaper than Pt and an upper electrode made of Cu or Cu alloy that is cheaper than Pt, and is therefore less expensive than a conventional thin film capacitor. . In the thin film capacitor of the present invention, the base electrode made of Ni can also serve as the substrate. In this case, it is cheaper than a configuration in which the substrate and the base electrode are provided separately.

  A thin film capacitor manufacturing method according to a first aspect of the present invention is a manufacturing method for manufacturing the above thin film capacitor of the present invention, comprising a base electrode, two or more dielectric films laminated on the base electrode, and a dielectric Ni is contained as a main component laminated between body films, and further contains at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag. After forming the internal electrode layer, the base electrode, the two or more dielectric films, and the internal electrode layer are fired at the same time to form a stacked body, and located on the opposite side of the base electrode in the stacked body Forming the upper electrode layer made of Cu or Cu alloy on the surface and patterning the dielectric film, the internal electrode layer and the upper electrode layer, respectively, thereby forming the dielectric layer, the internal electrode and the upper electrode, respectively. Includes a degree, the.

  A method for manufacturing a thin film capacitor according to a second invention is a method for manufacturing the thin film capacitor according to the present invention, wherein a base electrode, two or more dielectric films laminated on the base electrode, and a dielectric Ni is contained as a main component laminated between body films, and further contains at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag. Forming a laminate comprising an internal electrode layer and an upper electrode layer made of Cu or Cu alloy, which is laminated on the opposite side of the base electrode across the dielectric film and the internal electrode layer, and after the formation of the laminate Forming the dielectric layer, the internal electrode, and the upper electrode by wet-etching the dielectric film, the internal electrode layer, and the upper electrode layer, respectively.

  According to the first and second inventions, the thin film capacitor of the present invention can be manufactured easily and at low cost.

  Furthermore, the method for manufacturing a thin film capacitor according to the present invention includes a base electrode, two or more dielectric films stacked on the base electrode, and Ni as a main component stacked between the dielectric films. Furthermore, an internal electrode layer containing at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag, and a base layer with the dielectric film and the internal electrode layer interposed therebetween A step of forming a laminate comprising an upper electrode layer laminated on the opposite side of the electrode, and after forming the laminate, the dielectric film, the internal electrode layer, and the upper electrode layer are each wet-etched to form a dielectric Forming a layer, an internal electrode, and an upper electrode, respectively.

  According to the manufacturing method described above, each of the dielectric layer, the internal electrode, and the upper electrode can be formed by wet etching the dielectric film, the internal electrode layer, and the upper electrode layer after forming the stacked body. Therefore, the process can be simplified as compared with the case of forming each layer while patterning, and a thin film capacitor can be manufactured at a lower cost.

  Here, it is preferable that the step of forming the laminate includes a step of simultaneously firing two or more dielectric films.

  According to the above manufacturing method, since two or more dielectric films are fired at the same time, the number of firings can be reduced as compared with the case of firing each layer. Damage can be reduced and a thin film capacitor having higher characteristics can be obtained. In addition, since the number of firings can be reduced, a thin film capacitor can be manufactured at a lower cost.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to increase an electrostatic capacitance and reducing a leakage current, it becomes possible to provide an inexpensive thin film capacitor and a thin film capacitor manufacturing method.

It is a schematic sectional drawing of the thin film capacitor which concerns on one Embodiment of this invention. 2A, 2B, and 2C are schematic cross-sectional views showing a process of forming the upper electrode 10 by wet etching in the method of manufacturing the thin film capacitor 100 shown in FIG. FIGS. 3A and 3B are schematic cross-sectional views showing a process of forming the dielectric layer 6 by wet etching in the method for manufacturing the thin film capacitor 100 shown in FIG. 4A and 4B are schematic cross-sectional views showing a process of forming the internal electrode 8 by wet etching in the method of manufacturing the thin film capacitor 100 shown in FIG. FIG. 5A and FIG. 5B are schematic cross-sectional views showing a process of forming the dielectric layer 4 by wet etching in the method for manufacturing the thin film capacitor 100 shown in FIG. It is a schematic sectional drawing of the thin film capacitor which concerns on other embodiment of this invention.

  Hereinafter, a preferred embodiment 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, and the description is abbreviate | omitted when description overlaps. In addition, the present invention is not limited to the following embodiment, and is merely an embodiment.

(Thin film capacitor)
As shown in FIG. 1, the thin film capacitor 100 of this embodiment includes a base electrode 2 that also serves as a substrate, a dielectric layer 4 stacked on the base electrode 2, and an internal electrode stacked on the dielectric layer 4. 8, a dielectric layer 6 laminated on the internal electrode 8, and an upper electrode 10 laminated on the dielectric layer 6. That is, the thin film capacitor 100 includes a base electrode 2, two dielectric layers 4 and 6 stacked on the base electrode 2, and an internal electrode 8 stacked between the dielectric layer 4 and the dielectric layer 6. And an upper electrode 10 stacked on the opposite side of the base electrode 2 with the dielectric layers 4 and 6 and the internal electrode 8 interposed therebetween. The dielectric layer 4 is interrupted in the cross section of the thin film capacitor 100 shown in FIG. 1, but is continuous in a plane perpendicular to the stacking direction. Similarly, the dielectric layer 6, the internal electrode 8, and the upper electrode 10 are also continuous in a plane perpendicular to the stacking direction. Hereinafter, the direction in which the base electrode 2, the dielectric layer 4, the internal electrode 8, the dielectric layer 6, and the upper electrode 10 are sequentially overlapped is referred to as “stacking direction”.

  The thin film capacitor 100 includes a pair of terminal electrodes 12 a and 12 b on the opposite side of the base electrode 2 across the dielectric layer 4, the internal electrode 8, the dielectric layer 6 and the upper electrode 10. One terminal electrode 12 a of the pair of terminal electrodes 12 a and 12 b is electrically connected to the base electrode 2 and the upper electrode 10. The other terminal electrode 12 b is electrically connected to the internal electrode 8. Further, the pair of terminal electrodes 12a and 12b are electrically insulated from each other.

  In addition, the thin film capacitor 100 is an insulating material that fills a gap between the base electrode 2, the dielectric layer 4, the internal electrode 8, the dielectric layer 6 and the upper electrode 10 and the pair of terminal electrodes 12a and 12b. The cover layer 14 is provided.

  The internal electrode 8 contains Ni as a main component. The content of Ni contained in the internal electrode 8 is preferably 50 mol% or more with respect to the entire internal electrode 8. The internal electrode 8 is at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag (hereinafter referred to as “additive element”), preferably. , Pd and Ir are further contained. When the internal electrode 8 contains an additive element, the internal electrode 8 is prevented from being interrupted, and oxidation at the interface between the internal electrode 8 and the dielectric layers 4 and 6 is suppressed. As a result, the effects of the present invention can be obtained and the internal electrode 8 can be easily multilayered. If the internal electrode 8 is composed only of Ni, the internal electrode 8 is easily interrupted, and it is difficult to make the internal electrode 8 multilayer. The internal electrode 8 may contain a plurality of types of additive elements. The content of the additive element contained in the internal electrode 8 is preferably greater than 0 mol% and 30 mol% or less, more preferably 5 to 20 mol%, and more preferably 10 to 15 mol% with respect to the entire internal electrode 8. More preferably. This makes it easier to obtain the effects of the present invention. Here, when Pd and Ir are used as additive elements, the above-described effect becomes the highest, so these elements are preferably used as additive elements.

The thickness of the internal electrode 8 is, for example, about 10 to 1000 nm. Further, the area of the internal electrode 8 is, for example, about 0.9 × 0.4 mm ² .

  The base electrode 2 contains Ni as a main component. The purity of Ni constituting the base electrode 2 is preferably as high as possible, and is preferably 99.99% by weight or more. Note that the base electrode 2 may contain a small amount of impurities as long as the effects of the present invention are not impaired. Examples of impurities that can be contained in the base electrode 2 include iron (Fe), titanium (Ti), copper (Cu), aluminum (Al), magnesium (Mg), manganese (Mn), silicon (Si), or chromium ( Cr), vanadium (V), zinc (Zn), niobium (Nb), tantalum (Ta), yttrium (Y), lanthanum (La), cesium (Ce) and other transition metal elements or rare earth elements, chlorine (Cl ), Sulfur (S), phosphorus (P) and the like. When these impurities diffuse from the base electrode 2 to the dielectric film in the firing step of the thin film capacitor manufacturing method to be described later, the composition of the dielectric layers 4 and 6 to be obtained may be shifted, or the crystal of the dielectric film There is a tendency to reduce the insulation resistance of the obtained dielectric layers 4 and 6 by inhibiting the formation and crystal grain growth and changing the fine structure. Deviations in the composition of the dielectric layers 4 and 6 or changes in the microstructure tend to weaken the effect of the present invention that increases the capacitance of the thin film capacitor 100 and weaken the effect of the present invention that reduces leakage current. There is.

The thickness of the base electrode 2 is preferably 5 to 100 μm, more preferably 20 to 70 μm, and still more preferably about 50 μm. If the thickness of the base electrode 2 is too thin, it tends to be difficult to hand-link the base electrode 2 when the thin film capacitor 100 is manufactured. If the thickness of the base electrode 2 is too thick, the effect of suppressing the leakage current becomes small. Tend. The area of the base electrode 2 is, for example, about 1 × 0.5 mm ² .

The dielectric layers 4 and 6 are made of BaTiO ₃ (barium titanate), (Ba _1-x Ca _X ) TiO ₃ , (Ba _1-X Sr _X ) TiO ₃ (barium strontium titanate), PbTiO ₃ , Pb (Zr). _X Ti _1-X ) ₃ or the like (ferroelectric) dielectric material having a perovskite structure, a composite perovskite relaxor type ferroelectric material typified by Pb (Mg _1/3 Nb _2/3 ) O ₃ , Bismuth layered compounds typified by Bi ₄ Ti ₃ O ₁₂ , SrBi ₂ Ta ₂ O _9, etc., tungsten bronze ferroelectrics typified by (Sr _1-X Ba _X ) Nb ₂ O ₆ , PbNb ₂ O _6, etc. Consists of materials etc. Here, in these perovskite structures, perovskite relaxor type ferroelectric materials, bismuth layered compounds and tungsten bronze type ferroelectric materials, the ratio of A site to B site is usually an integer ratio. Alternatively, the integer ratio may be shifted. In order to control the characteristics of the dielectric layers 4 and 6, the dielectric layers 4 and 6 may appropriately contain additive substances as subcomponents.

Each thickness of the dielectric layers 4 and 6 is, for example, 10 to 1000 nm. Each area of the dielectric layers 4 and 6 is, for example, about 0.9 × 0.5 mm ² .

  The upper electrode 10 is made of Cu or a Cu alloy. That is, the upper electrode 10 is made of high-purity Cu or 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 10 may contain a small amount of impurities as long as the effect of the present invention is not impaired. Examples of impurities that can be contained in the upper electrode 10 include iron (Fe), titanium (Ti), aluminum (Al), magnesium (Mg), manganese (Mn), silicon (Si), chromium (Cr), and vanadium. (V), transition metal elements such as zinc (Zn), niobium (Nb), tantalum (Ta), yttrium (Y), lanthanum (La), cesium (Ce), or rare earth elements, chlorine (Cl), sulfur ( S), phosphorus (P) and the like.

  The terminal electrodes 12a and 12b are made of a conductive material such as Cu, for example. The cover layer 14 is made of an insulating material such as polyimide.

  In the present embodiment, as described above, the base electrode 2 contains Ni, the internal electrode 8 contains Ni as a main component and an additive element, and the upper electrode 10 is made of Cu or a Cu alloy. In this case, the difference between the work function of Cu constituting the upper electrode 10 and the interface between the electrode and the dielectric layers 4 and 6 with respect to Ni constituting the base electrode 2 and the main component of the internal electrode 8. The stress in the dielectric layers 4 and 6 is reduced by the synergistic effect of the combination of electrodes having different compositions, such as the difference in the oxygen behavior associated with the oxidation-reduction due to the materials constituting the electrodes. Since the redox state at the interface with the layers 4 and 6 is stabilized, the capacitance of the thin film capacitor 100 is increased and the leakage current is decreased as compared with the conventional thin film capacitor.

  That is, as will be described later, in the manufacture of the thin film capacitor 100, the base electrode 2 containing Ni as a main component, the dielectric films 4a and 6a, the main component Ni, and the internal electrode layer 8a containing the additive element. It is preferable that the two dielectric films 4a and 6a are baked together in a laminated state. Thereby, the effect of this invention mentioned later can be acquired more effectively. Of course, instead of firing in a laminated state all together, firing may be performed sequentially after the formation of each dielectric film as in the prior art, but in this case, the cost increases. On the other hand, in the present embodiment, the internal electrode layer 8a and the dielectric films 4a and 6a are simultaneously fired, so that the internal electrode layer 8a and the dielectric films 4a and 6a are optimally oxidized, burned, and grain-grown. can do. As a result, in the completed thin film capacitor 100, due to the stress balance of the base electrode 2, the internal electrode 8, and the dielectric layers 4 and 6, the stress in the dielectric layers 4 and 6 becomes low, and a large dielectric constant is realized. The capacitance increases.

  Moreover, since the stress in the dielectric layers 4 and 6 is low, the dielectric layers 4 and 6 are hardly damaged by the stress. Further, since the base electrode 2 contains Ni as a main component, the internal electrode 8 contains Ni as a main component and an additive element, and the upper electrode 10 is made of Cu or a Cu alloy, the base electrode 2 and the dielectric layer 4, the interface between the internal electrode 8 and the dielectric layers 4 and 6, and the interface between the upper electrode 10 and the dielectric layer 6 can be stabilized. As described above, the dielectric layers 4 and 6 are hardly damaged and the oxidation state at the interface is stabilized. As a result, the leakage current in the thin film capacitor 100 can be reduced.

  The thin film capacitor 100 of this embodiment is suitably used as a capacitor for suppressing EMI generated in accordance with fluctuations in the power supply voltage of an LSI or a capacitor that can be mounted on a printed board by embedding and pasting in the printed board. .

(Manufacturing method of thin film capacitor 100)
Next, an example of a method for manufacturing the thin film capacitor 100 of the present embodiment will be described.

  The manufacturing method of the thin film capacitor 100 of the present embodiment includes a base electrode containing Ni as a main component, two or more dielectric films stacked on the base electrode, and a laminate between the dielectric films. And an internal electrode layer containing at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag. , Referred to as a “first laminated body”), a step of firing the first laminated body (between the base electrode, two or more dielectric films stacked on the base electrode, and the dielectric film) And forming the laminated body by simultaneously firing the base electrode, the two or more dielectric films and the internal electrode layer, and the first laminated layer after firing. On the surface of the body opposite to the base electrode, Cu or forming an upper electrode layer made of a u alloy to form a laminated body (hereinafter referred to as a “second laminated body”) including a base electrode, a dielectric film, an internal electrode layer, and an upper electrode layer; Forming the dielectric layer, the internal electrode, and the upper electrode by wet etching the dielectric film, the internal electrode layer, and the upper electrode layer, respectively, after forming the two-layered body. Hereinafter, each step will be described in detail.

  First, as shown in FIG. 2A, a dielectric film 4a is formed on the entire surface of the base electrode 2. The composition of the dielectric film 4a may be the same as that of the dielectric layer 4 included in the completed thin film capacitor 100. Examples of the method for forming the dielectric film 4a include solution coating and baking methods such as a sol-gel method and a MOD method (organometallic compound deposition method), and film forming techniques such as a PVD method such as a sputtering method or a CVD method. Of these film forming techniques, the sputtering method is particularly preferably used. The dielectric film 4a formed by the above method is generally in an amorphous state.

  Next, the internal electrode layer 8a is formed on the entire surface of the dielectric film 4a. The composition of the internal electrode layer 8a may be the same as that of the internal electrode 8 included in the completed thin film capacitor 100. Moreover, DC sputtering etc. are mentioned as a formation method of the internal electrode layer 8a.

  Further, the dielectric film 6a is formed on the entire surface of the internal electrode layer 8a. As a result, a first stacked body is obtained in which the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a are sequentially stacked. The composition of the dielectric film 6a may be the same as that of the dielectric layer 6 included in the completed thin film capacitor 100. The formation method of the dielectric film 6a is the same as that of the dielectric film 4a.

Next, the first laminate is fired. Although it is the timing of firing the first stacked body, the stacks are sequentially fired, or preferably two or more dielectric films 4a and 6a are fired simultaneously. More preferably, the first laminate is fired all at once. That is, in this embodiment, after forming the first stacked body including the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a without firing, the first stacked body is fired. The firing temperature is preferably set to a temperature at which the dielectric films 4a and 6a are sintered (crystallized), specifically 500 to 1000 ° C. The firing time may be about 5 minutes to 2 hours. The atmosphere during firing is not particularly limited, and may be any of an oxidizing atmosphere, a reducing atmosphere, and a neutral atmosphere. At least, firing is performed under an oxygen partial pressure that does not oxidize the base electrode 2 and the internal electrode layer 8a. It is preferable to do. More preferably, in at least a part of the firing step, the first laminate is heated to 550 to 1000 ° C. in a reduced pressure atmosphere whose pressure measured by an ionization vacuum gauge is 1 × 10 ⁻⁹ to 1 × 10 ³ Pa. It is preferable to heat.

Here, in the step of firing the first stacked body, the first stacked body is heat-treated in a reduced pressure atmosphere of 1 × 10 ⁻⁹ to 1 × 10 ³ Pa to obtain a dielectric film having a high dielectric constant. . By performing the heat treatment under such a specific range of pressure, the oxidation of the internal electrode layer 8a made of Ni foil or the like is suppressed, and the oxygen vacancy concentration of the obtained dielectric film is suppressed low. Therefore, a dielectric film capable of expressing a high dielectric constant can be obtained without re-oxygenation of the dielectric film after firing. In addition, when the pressure of 8a at the time of baking exceeds 1 * 10 < ³ > Pa, malfunctions, such as the oxidation of the internal electrode layer consisting of a metal, may generate | occur | produce. When the internal electrode layer 8a is oxidized, a high dielectric constant of the dielectric film tends to be difficult to express. Also, the internal electrode layer 8a tends to evaporate under a pressure of less than 1 × 10 ⁻⁹ Pa. When the internal electrode layer 8a evaporates, the leakage current tends to increase. The heat treatment during firing may partially include a process of heating under a pressure outside the above pressure range, but preferably includes a process of heating for at least 1 to 60 minutes within the above pressure range. .

Generally, the pressure during the firing is preferably 1 × 10 ⁻⁵ to 1 × 10 ² Pa, and more preferably 1 × 10 ⁻³ to 10 Pa. In particular, when the internal electrode layer 8a is made of Cu, the pressure is preferably 4 × 10 ⁻¹ to 8 × 10 ⁻¹ Pa. However, the internal electrode layer 8a has the same structure as the laminated body according to the present embodiment. When the main component is Ni, the pressure is preferably 2 × 10 ⁻³ to 8 × 10 ⁻¹ Pa. Moreover, when firing the first laminate, the first laminate is preferably heated to 400 to 1000 ° C, more preferably 550 to 1000 ° C, and even more preferably 600 to 900 ° C. . If the heating temperature during firing is less than 550 ° C., it tends to be difficult to obtain a dielectric film having a density exceeding 72% of the theoretical density. Moreover, when this heating temperature becomes high, the leakage current tends to increase.

  After firing the first laminate, as shown in FIG. 2A, the upper electrode layer 10a made of Cu or Cu alloy is formed on the entire surface of the dielectric film 6a. As a result, a second stacked body 200 is obtained in which the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, the dielectric film 6a, and the upper electrode layer 10a are sequentially stacked. In addition, as a formation method of the upper electrode layer 8a, DC sputtering etc. are mentioned.

  Next, heat treatment is performed on the second stacked body 200. The heat treatment may be performed in a reduced pressure atmosphere of 150 ° C. or higher. Here, the reduced pressure atmosphere means an atmosphere having a pressure lower than 1 atm (= 101325 Pa). By performing the heat treatment, the electrical characteristics can be stabilized.

  Next, as shown below, the upper electrode layer 10a, the dielectric layer 6a, the internal electrode layer 8a, and the dielectric layer 4a are sequentially patterned by wet etching, whereby the upper electrode 10, the dielectric layer 6, and the internal electrode 8 are patterned. And the dielectric layer 4 are formed.

  First, after heat treatment, a photoresist is applied to the surface of the upper electrode layer 10a, and then a mask 20a having a pattern corresponding to the upper electrode 10 included in the completed thin film capacitor 100 is formed by photolithography (FIG. 2B). )reference). After the mask 20a is formed, the upper electrode layer 10a is etched with an etching solution to form the upper electrode 10 (see FIG. 2C). After the upper electrode 10 is formed, the mask 20a that covers the surface of the upper electrode 10 is peeled off. For example, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. may be used as the photoresist for forming the upper electrode 10. Further, as an etching solution for forming the upper electrode 10, an etching solution that erodes the upper electrode layer 10a and does not erode the dielectric film 6a and the mask 20a adjacent to the upper electrode layer 10a may be used. An aqueous ammonium sulfate solution may be used.

  Next, as shown in FIG. 3A, a photoresist is applied to the surfaces of the upper electrode 10 and the dielectric film 6a included in the multilayer body 200a, and then the dielectric included in the completed thin film capacitor 100 by photolithography. A mask 20b having a pattern corresponding to the layer 6 is formed. After the formation of the mask 20b, the dielectric film 6a is etched with an etchant to form the dielectric layer 6 (see FIG. 3B). After the dielectric layer 6 is formed, the upper electrode 10 and the mask 20b that covers the surface of the dielectric layer 6 are peeled off. For example, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. may be used as the photoresist for forming the dielectric layer 6. Further, as an etching solution for forming the dielectric layer 6, an etchant that erodes the dielectric film 6a and does not erode the internal electrode layer 8a and the mask 20b adjacent to the dielectric film 6a may be used. Hydrochloric acid + ammonium fluoride aqueous solution may be used.

Next, as shown in FIG. 4A, after the photoresist is applied to the surfaces of the upper electrode 10, the dielectric layer 6 and the internal electrode layer 8a included in the multilayer body 200b, the completed thin film capacitor is formed by photolithography. A mask 20c having a pattern corresponding to the internal electrode 8 included in 100 is formed. After the formation of the mask 20c, the internal electrode layer 8a is etched with an etching solution to form the internal electrode 8 (see FIG. 4B). After the internal electrode 8 is formed, the upper electrode 10, the dielectric layer 6, and the mask 20c that covers the surface of the internal electrode 8 are peeled off. For example, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. may be used as the photoresist for forming the internal electrode 8. Further, as an etching solution for forming the internal electrode 8, a solution that erodes the internal electrode layer 8a and does not erode the dielectric film 4a and the mask 20c adjacent to the internal electrode layer 8a may be used. An aqueous iron (FeCl ₃ ) solution may be used.

  Next, as shown in FIG. 5A, a photoresist is applied to the surfaces of the upper electrode 10, the dielectric layer 6, the internal electrode 8, and the dielectric film 4a included in the multilayer body 200c, and then completed by photolithography. A mask 20d having a pattern corresponding to the dielectric layer 4 included in the subsequent thin film capacitor 100 is formed. After forming the mask 20d, the dielectric film 4a is etched with an etching solution to form the dielectric layer 4 (see FIG. 5B). After forming the dielectric layer 4, the upper electrode 10, the dielectric layer 6, the internal electrode 8, and the mask 20 d covering the surface of the dielectric layer 4 are cleaned. For example, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. may be used as the photoresist for forming the dielectric layer 4. Further, as the etching solution for forming the dielectric layer 4, an etching solution that erodes the dielectric film 4a and does not erode the base electrode 2 and the mask 20d adjacent to the dielectric film 4a may be used. A + ammonium fluoride aqueous solution may be used.

  After the formation of the dielectric 4, a cover layer 14 is formed so as to cover the surfaces of the base electrode 2, the dielectric layer 4, the internal electrode 8, the dielectric layer 6, and the upper electrode 10 included in the multilayer body 200 d, and the cover layer 14 A pair of terminal electrodes 12a and 12b are formed on the upper surface of the substrate. One terminal electrode 12 a is electrically connected to the base electrode 2 and the upper electrode 10, and the other terminal electrode 12 b is electrically connected to the internal electrode 8. Thereby, the thin film capacitor 100 shown in FIG. 1 is completed.

  In the present embodiment, the internal electrode layer 8a contains Ni as a main component, and at least selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta, and Ag as additive elements. Since one kind (additive element) is contained, the cost of the thin film capacitor 100 can be reduced as compared with the case where a conventional internal electrode mainly composed of Pt is used. Further, the internal electrode layer 8a having the above composition hardly undergoes oxidation or breakage during firing with the dielectric films 4a and 6a, and hardly reacts with the dielectric films 4a and 6a. If the internal electrode layer 8a is made of a base metal alone, the internal electrode layer 8a tends to oxidize or break during firing with the dielectric films 4a and 6a, and tends to react with the dielectric films 4a and 6a.

  Among the above-described additive elements contained in the internal electrode layer 8a, at least one of Pt, Pd, Ir, W, Cr, Ta, and Ag is easy in obtaining an effect of preventing the internal electrode layer 8a from being interrupted during firing. preferable. Among the above-described additive elements, Pt, Pd, Ir, Rh, and Pt, Pd, Ir, Rh, and the like are easy to obtain an effect of suppressing the oxidation of the internal electrode layer 8a and the reaction between the internal electrode layer 8a and the dielectric films 4a and 6a during firing. At least one of Ru, Os, and Re is preferable. Moreover, at least one of Pd, Re, W, Cr, Ta, and Ag is preferable in that wet etching is easily performed when an aqueous iron chloride solution is used as an etching solution. If the internal electrode layer 8a is made of only Pt, it is difficult to etch the internal electrode layer 8a by a wet process, and the internal electrode layer 8a must be etched by a dry process, resulting in an increase in manufacturing cost.

  The content of the additive element contained in the internal electrode layer 8a is preferably greater than 0 mol% and 30 mol% or less, more preferably 5 to 20 mol%, and more preferably 10 to 15 mol% with respect to the entire internal electrode layer 8a. More preferably. Thereby, the internal electrode layer 8a is less likely to be interrupted during firing, and the internal electrode layer 8a can be multilayered. If the internal electrode layer 8a is made of only Ni, the internal electrode layer is likely to break during firing, making it difficult to make the internal electrode layer multi-layered.

  In the present embodiment, the thermal expansion coefficient of the base electrode 2 containing Ni as a main component is close to the thermal expansion coefficient of the dielectric films 4a and 6a. For this reason, when the first laminated body formed by sequentially laminating the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a is fired, stress is generated in the fired dielectric films 4a and 6a. This makes it difficult to increase the dielectric constant of the dielectric films 4a and 6a, and makes it difficult for cracks to occur in the dielectric films 4a and 6a. Further, since the base electrode 2 contains Ni as a main component, the internal electrode 8 is hardly peeled off. That is, peeling of the internal electrode 8 is prevented by a combination of the base electrode 2 containing Ni as a main component and the internal electrode 8 containing Ni as a main component.

  If a conventional Si substrate and a base electrode made of Pt formed thereon are used as the base electrode 2, the thermal expansion coefficient of the Si substrate and the thermal expansion coefficients of the dielectric films 4a and 6a are too different. Stress is likely to occur in the subsequent dielectric films 4a and 6a. As a result, the dielectric constants of the dielectric films 4a and 6a are reduced, and cracks are likely to occur in the dielectric films 4a and 6a. And peeling of the internal electrode 8 becomes easy to occur. Furthermore, if a base electrode made of a conventional Si substrate and Pt formed thereon is used as the base electrode 2, the cost increases.

  In this embodiment, the thermal expansion coefficient of the internal electrode layer 8a containing Ni as a main component is close to the thermal expansion coefficient of the dielectric films 4a and 6a. For this reason, when the first laminated body formed by sequentially laminating the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a is fired, stress is generated in the fired dielectric films 4a and 6a. This makes it difficult to increase the dielectric constant of the dielectric films 4a and 6a, and makes it difficult for cracks to occur in the dielectric films 4a and 6a. In addition, since the internal electrode layer 8a containing Ni as a main component is difficult to melt when fired at a high temperature at which the dielectric films 4a and 4b are sintered, the internal electrode layer 8a after firing is less likely to be interrupted.

  Further, in the present embodiment, after firing the first laminated body in which the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a are sequentially laminated, the laminated body is positioned on the opposite side of the base electrode 2. An upper electrode layer 10a made of Cu or Cu alloy is formed on the surface to be processed. By heat-treating the upper electrode layer 10a at a temperature lower than the firing temperature of the dielectric films 4a and 4b, the thin film capacitor 100 capable of reducing the leakage current can be obtained.

  If the upper electrode 10 made of a platinum group such as Pt is used, the thin film capacitor 100 becomes more expensive and the leakage current becomes larger than when the upper electrode 10 made of Cu or Cu alloy is used. Tend. In the case of the Pt electrode, in order to reduce the leakage current, it is necessary to perform a heat treatment in a high-temperature oxidizing atmosphere to the extent that the dielectric films 4a and 6a are sintered. Unlike the case, the electrode is oxidized and does not function as an electrode, so that high-temperature heat treatment is impossible. In the laminated structure of the present invention, the present inventor has found that leakage current is reduced by low-temperature heat treatment by using Cu or a Cu alloy for the upper electrode layer 10a of the second laminated body 200.

  Further, in the conventional manufacturing method, the patterning formation of the internal electrodes and the crystallization of the dielectric layer are repeated, so that the high-temperature heat treatment is repeatedly performed. For this reason, the oxidation in the vicinity of patterning is intense, and particularly the portion where the internal electrode is exposed by patterning is greatly damaged. On the other hand, as in the manufacturing method described above, the first laminated body formed by sequentially laminating the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film 6a is fired at once (that is, two or more dielectrics). In the case where the film is fired at once, the internal electrode layer 8a is in a protected state and is fired by a single high-temperature heat treatment, so that the damage to the internal electrode layer 8a is compared with the conventional manufacturing method. Can be reduced.

(Another embodiment of thin film capacitor manufacturing method)
In the manufacturing method of the thin film capacitor 100 described above, after firing the first multilayer body, the upper electrode layer 10a made of Cu or Cu alloy is formed on the surface of the first multilayer body after firing on the opposite side of the base electrode 2. The second laminated body 200 including the base electrode 2, the dielectric films 4a and 6a, the internal electrode layer 8a, and the upper electrode layer 10a is formed, and the dielectric films 4a and 6a of the second laminated body 200 and the internal electrodes are formed. The method of forming the dielectric layers 4 and 6, the internal electrode 8 and the upper electrode 10 by wet etching the layer 8a and the upper electrode layer 10a, respectively, has been described. However, the above-described thin film capacitor manufacturing method is used when the upper electrode 10 is made of a material different from Cu or Cu alloy, that is, a wiring material such as Al, Cr, W, Mn, Ni used in semiconductors and displays. Is also applicable.

  That is, even when a thin film capacitor is manufactured using a material different from Cu or Cu alloy as the upper electrode 10, the internal electrode layer 8 a can be etched by a wet process. Compared to the case, cost reduction can be realized. This is because the internal electrode layer 8a is made of a material suitable for wet etching. Specifically, it contains Ni as a main component and further contains Pt, Pd, Ir, Rh, Ru, Os, Re as additive elements. This is because it contains at least one selected from the group consisting of W, Cr, Ta and Ag. For example, Ni is preferably used as the material of the upper electrode 10 instead of Cu or Cu alloy. Further, the upper electrode layer 10a made of Ni can be formed on the surface of the first laminated body after firing by sputtering using Ni as a target. Further, even when Ni is used as the upper electrode 10, the dielectric films 4 a and 6 a that are formed before the upper electrode layer 10 a is formed are collectively fired in the state of the first stacked body. Naturally, the effect of reducing damage to the electrode layer 8a is the same.

  Further, in the manufacturing method of the thin film capacitor 100 described above, the base electrode 2 containing Ni as a main component is described. However, a material different from the material containing Ni as a main component may be used as the base electrode 2. it can. As the material of the base electrode 2 replacing the material containing Ni as a main component, for example, a material containing Cu as a main component or a material obtained by forming Pt as a base electrode on a Si substrate is preferably used. Even when the material used for the base electrode 2 is changed, the effect of reducing the damage to the internal electrode layer 8a by performing the firing of the dielectric films 4a and 6a in the state of the first stacked body is as follows. It is the same.

  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, the dielectric films 4a and 6a do not have to be fired at once in the state of the first stacked body. For example, the dielectric films 6a are fired once immediately after forming the dielectric film 4a, and the dielectric films 6a are formed. Baking may be performed again immediately after film formation.

  In addition, as shown in FIG. 6, the thin film capacitor 100 a may include a plurality of (for example, four layers) internal electrodes 8 laminated via a dielectric layer 60. Thereby, the electrostatic capacitance of the thin film capacitor 100a can be further increased. Further, although the configuration in which the base electrode 2 also serves as the substrate has been described, the base electrode and the substrate may be made of different materials.

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

(Sample 2d)
First, the surface of a 30 μm thick Ni foil (base electrode 2 in FIG. 1) was polished into a mirror surface. Then, by sputtering using a BaTiO ₃ as a target, thereby forming a BaTiO ₃ film (dielectric film 4a) on the surface of the polished Ni foil. In sputtering, the temperature of the Ni foil was maintained at 250 ° C. The thickness of the BaTiO ₃ film was 200 nm.

Next, a layer made of a Ni-based metal (internal electrode layer 8a) is formed as a BaTiO ₃ film (dielectric) by sputtering using a Ni-based metal containing Ni as a main component and further containing 15 mol% of Pd as an additional element. A film 4a) was formed on the surface. The thickness of the internal electrode layer 8a was 200 nm.

Next, a BaTiO ₃ film (dielectric film 6a) is formed on the surface of the internal electrode layer 8a by sputtering using BaTiO ₃ as a target, and the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, and the dielectric film are formed. A plurality of first laminated bodies composed of four layers 6a were formed. In sputtering, the temperature of the Ni foil was maintained at 250 ° C. The thickness of the BaTiO ₃ film (dielectric film 6a) was 200 nm.

Next, the first laminated body was fired at 800 ° C. in a vacuum atmosphere to sinter the two BaTiO ₃ films (dielectric films 4a and 6a). The surface of the 1st laminated body obtained after baking was observed with the optical microscope, and the presence or absence of the interruption of the internal electrode layer 8a was investigated. Since the dielectric films 4a and 6a are transparent, the discontinuity of the internal electrode layer 8a can be observed. The results are shown in Table 1. By this observation, when the internal electrode layer 8a is not interrupted, it is evaluated as “no”, and when several discontinuous points are observed in the region of the microscope field of view of 100 μm ^2, it is evaluated as “small”. When a hole (discontinuity) in the electrode layer 8a is exposed and a short circuit occurs in the thin film capacitor 100 after completion, or when 20 or more discontinuities are observed in the region of the microscope field of view of 100 μm ² , “ "Large".

  After firing the first laminate, an upper electrode layer 10a made of Cu is formed on the surface of the first laminate that is opposite to the Ni foil, and the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, A second stacked body 200 including five layers of the dielectric film 6a and the upper electrode layer 10a was formed (see FIG. 2A). The upper electrode layer 10a was formed by sputtering using Cu as a target. Next, the 2nd laminated body 200 was heat-processed at 310 degreeC in the vacuum atmosphere.

After the heat treatment, the upper electrode layer 10a, the dielectric film 6a, the internal electrode layer 8a, and the dielectric film 4a included in the second stacked body are illustrated in FIG. 2 (b), FIG. 2 (c), FIG. 3 (a), FIG. (B), FIG. 4 (a), FIG. 4 (b), FIG. 5 (a), and FIG. 5 (b) are subjected to wet etching, whereby the upper electrode 10, the dielectric layer 6, the internal electrode 8 and Dielectric layers 4 were sequentially formed to obtain a stacked body 200d shown in FIG. In wet etching of the upper electrode layer 10a, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used as a photoresist, and an aqueous ammonium persulfate solution was used as an etching solution. In the wet etching of the dielectric film 6a, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used as a photoresist, and hydrochloric acid + ammonium fluoride aqueous solution was used as an etching solution. In the wet etching of the internal electrode layer 8a, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used as a photoresist, and an iron chloride (FeCl ₃ ) aqueous solution was used as an etching solution. In the wet etching of the dielectric film 4a, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used as a photoresist, and hydrochloric acid + ammonium fluoride aqueous solution was used as an etching solution.

  After wet etching of the internal electrode layer 8a (before performing wet etching of the dielectric film 4a), the shape of the obtained internal electrode 8 was evaluated. The results are shown in Table 2. In Table 2, when a desired internal electrode 8 having a shape corresponding to the mask 20c of FIG. 4 is formed, it is evaluated as “◯”, and a part of the internal electrode layer 8a not covered with the mask 20c is When it remains on the surface of the dielectric film 4a as a residue, it is evaluated as “Δ”, the internal electrode 8 having a shape corresponding to the mask 20c cannot be formed, and the thin film capacitor 100 cannot be completed. And “×”.

  Next, a cover layer 14 made of polyimide was formed so as to cover the surfaces of the base electrode 2, the dielectric layer 4, the internal electrode 8, the dielectric layer 6, and the upper electrode 10 included in the multilayer body 200 d. Next, after forming holes respectively communicating with the upper electrode 10, the internal electrode 8, and the base electrode 2 on the upper surface of the cover layer 14, a pair of terminal electrodes 12a and 12b made of Cu are formed by sputtering. A plurality of sized thin film capacitors 100 were obtained (see FIG. 1). One terminal electrode 12a is electrically connected to the base electrode 2 and the upper electrode 10 through a hole formed in the cover layer 14, and the other terminal electrode 12b is connected through a hole formed in the cover layer 14. The internal electrode 8 was electrically connected.

  One of the obtained thin film capacitors 100 is cut in a cross section perpendicular to the stacking direction, and the surface of the internal electrode 8 (interface with the dielectric layers 4 and 6) is observed with an optical microscope. The presence or absence was examined. The results are shown in Table 3. In Table 3, when the oxide of the internal electrode 8 was not found, it was evaluated as “◯”, and even when the oxide of the internal electrode 8 was found or could not be determined as an oxide, the thin film capacitor after completion When the electrostatic capacity could not be obtained at 100, and when the electrostatic capacity of the thin film capacitor 100 after completion was significantly reduced to be less than 20 nF, and when tan δ was 20% or more, “x” was evaluated. .

(Samples 1a to 2c, 2e to 13f)
Samples 1a, 1b, 1c, 1d, 1e, 1f are the same as in the case of Sample 2d, except that the additive elements contained in the internal electrode layer 8a and the addition amounts of the additive elements are set to the values shown in Tables 1-3. 2a, 2b, 2c, 2e, 2f, 3a, 3b, 3c, 3d, 3e, 3f, 4a, 4b, 4c, 4d, 4e, 4f, 5a, 5b, 5c, 5d, 5e, 5f, 6a, 6b 6c, 6d, 6e, 6f, 7a, 7b, 7c, 7d, 7e, 7f, 8a, 8b, 8c, 8d, 8e, 8f, 9a, 9b, 9c, 9d, 9e, 9f, 10a, 10b, 10c 10d, 10e, 10f, 11a, 11b, 11c, 11d, 11e, 11f, 12a, 12b, 12c, 12d, 12e, 12f, 13a, 13b, 13c, 13d, 13e, and 13f are manufactured. . Similarly to the case of the sample 2d, the presence or absence of the discontinuity of the internal electrode layer 8a of these samples, the shape of the internal electrode 8 obtained after the wet etching, and the presence or absence of oxidation of the internal electrode 8 in the thin film capacitor 100 are evaluated. did. The results are shown in Tables 1-3.

(Sample 2dd)
A thin film capacitor 100 of sample 2dd was produced in the same manner as in sample 2d, except that the upper electrode was changed from a Cu electrode to a Ni electrode. Specifically, after firing the first laminate by a method similar to the method for producing the sample 2d shown in FIG. 2 (a), Ni on the surface of the first laminate located on the opposite side of the Ni foil. The upper electrode layer 10a made of the first electrode layer 10a was formed, and the second stacked body 200 including the base electrode 2, the dielectric film 4a, the internal electrode layer 8a, the dielectric film 6a, and the upper electrode layer 10a was formed. However, Ni is used as the upper electrode layer 10a instead of Cu. The upper electrode layer 10a was formed by sputtering using Ni as a target. Next, the 2nd laminated body 200 was heat-processed at 310 degreeC in the vacuum atmosphere.

After the heat treatment, the upper electrode layer 10a, the dielectric film 6a, the internal electrode layer 8a, and the dielectric film 4a included in the second stacked body are illustrated in FIG. 2 (b), FIG. 2 (c), FIG. 3 (a), FIG. (B), FIG. 4 (a), FIG. 4 (b), FIG. 5 (a), and FIG. 5 (b) are subjected to wet etching, whereby the upper electrode 10, the dielectric layer 6, the internal electrode 8 and Dielectric layers 4 were sequentially formed to obtain a stacked body 200d shown in FIG. In wet etching of the upper electrode layer 10a made of Ni, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used as a photoresist, and an aqueous iron chloride (FeCl ₃ ) solution was used as an etching solution. In the subsequent steps, the thin film capacitor 100 of the sample 2dd was manufactured by the same method as that of the sample 2d.

(Sample 14)
As a sample 14, as shown in FIG. 6, a 1005-size thin film capacitor 100a having four layers of internal electrodes 8 was produced. As shown below, the thin film capacitor 100a of the sample 14 was produced in the same manner as the sample 2d except for the method of forming the dielectric film, the timing of firing, and the thickness of the dielectric layer 60.

  In manufacturing the thin film capacitor 100a, each dielectric film (dielectric layer 60 before etching) was formed by a CSD (Chemical Solution Deposition) method. Each time the dielectric films were formed, the dielectric films were sequentially fired by heating to 800 ° C. in a vacuum. That is, when the thin film capacitor 100a of the sample 14 was manufactured, firing was performed five times in order to sinter the five layers of dielectric films. The thickness of each dielectric layer 60 was 300 nm.

(Sample 15)
The surface of a silicon single crystal substrate (hereinafter referred to as “substrate”) was thermally oxidized to form a SiO ₂ layer. Then, by sputtering using a TiO ₂ target, a TiO ₂ layer was formed on the surface of the SiO ₂ layer as an adhesion layer. The substrate was kept at room temperature during sputtering. Sputtering was performed in an oxygen atmosphere. The film thickness of the TiO ₂ layer was 20 nm.

Next, a base electrode made of Pt was formed on the surface of the TiO ₂ layer by sputtering. The thickness of the lower electrode was 200 nm.

After the formation of the base electrode, a dielectric film was formed on the surface of the base electrode by sputtering using BaTiO ₃ as a target. In sputtering for forming a dielectric film, the substrate was kept at 250 ° C. The film thickness of the dielectric film was 200 nm.

After forming the dielectric film, a laminate composed of the silicon single crystal substrate, the SiO ₂ layer, the TiO ₂ layer, the base electrode, and the dielectric film was fired. Firing was performed in vacuum, and the firing temperature was 800 ° C. The dielectric film was sintered by this firing.

  Next, an internal electrode layer made of Pt was formed on the surface of the dielectric film by sputtering. The thickness of the internal electrode was 200 nm.

A dielectric film is formed on the surface of the internal electrode by sputtering using BaTiO ₃ as a target, and a silicon single crystal substrate, a SiO ₂ layer, a TiO ₂ layer, a base electrode, a dielectric film, an internal electrode layer, and a dielectric film The 1st laminated body of the sample 15 by which these are laminated | stacked sequentially was formed. In the sputtering for forming a dielectric film on the internal electrode layer, the substrate was kept at 250 ° C. The thickness of the dielectric film formed on the internal electrode layer was 200 nm.

Next, the first laminate of Sample 15 was fired at 800 ° C. in a vacuum atmosphere, and the dielectric film formed on the internal electrode layer was sintered. After firing the laminated body, an upper electrode layer made of Pt was formed on the surface of the laminated body located on the opposite side of the silicon single crystal substrate. The upper electrode layer was formed by sputtering using Pt as a target. As a result, a second laminated body of the sample 15 composed of eight layers of the silicon single crystal substrate, the SiO ₂ layer, the TiO ₂ layer, the base electrode, the dielectric film, the internal electrode layer, the dielectric film, and the upper electrode layer was formed. Next, the second laminated body of the sample 15 was heat-treated at 310 ° C. in a vacuum atmosphere.

  The upper electrode layer, the dielectric film, the internal electrode layer, and the dielectric film included in the second stacked body of the heat-treated sample 15 were sequentially patterned using photolithography. Thus, an upper electrode layer, a dielectric film, an internal electrode layer, and a dielectric film were sequentially formed. The dielectric layer was formed by wet etching, and the internal electrode and the upper electrode made of Pt were each formed by dry etching.

  Next, a cover layer made of polyimide was formed so as to cover the surfaces of the base electrode, dielectric layer, internal electrode, dielectric layer, and upper electrode included in the second laminate of sample 15. Next, after forming holes respectively communicating with the upper electrode, the internal electrode, and the base electrode on the upper surface of the cover layer, a pair of terminal electrodes made of Cu are formed by sputtering to obtain a 1005-size thin film capacitor 100. It was. One terminal electrode is electrically connected to the base electrode and the upper electrode through a hole formed in the cover layer, and the other terminal electrode is electrically connected to the internal electrode through a hole formed in the cover layer. Connected.

Above manner, the thin film capacitor of the sample 15 thus fabricated, a Si substrate having an SiO ₂ layer, and a TiO ₂ layer which is laminated on the SiO ₂ layer, and the underlying electrode made of Pt laminated on TiO ₂ layer on the A first dielectric layer laminated on the base electrode, an internal electrode made of Pt laminated on the first dielectric layer, a second dielectric layer laminated on the internal electrode, And an upper electrode made of Pt laminated on two dielectric layers, which is a conventional thin film capacitor.

(Measurement of capacitance and leakage current)
The capacitance and leakage current of the thin film capacitor 100 of sample 2d, the thin film capacitor 100 of sample 2dd, the thin film capacitor 100a of sample 14, and the thin film capacitor of sample 15 were measured. The voltage applied to each capacitor when measuring the leakage current was 2V.

The capacitance of the thin film capacitor 100 of Sample 2d was 35.6 nF, and the capacitance of the thin film capacitor of Sample 15 was 17.6 nF. In addition, the leakage current of the thin film capacitor 100 of Sample 2d was 3.3 × 10 ⁻⁹ A, and the leakage current of the thin film capacitor of Sample 15 was 2.8 × 10 ⁻⁷ A.

From the above results, the base electrode 2 made of Ni, the dielectric layer 4 laminated on the base electrode 2,
Laminated on the dielectric layer 4, containing Ni as a main component and containing 15 mol% of Pd as an additive element, the dielectric layer 6 laminated on the internal electrode 8, and the dielectric layer 8 The thin film capacitor 100 of the sample 2d provided with the upper electrode 10 made of Cu and having a capacitance more than twice as large as that of the conventional thin film capacitor of the sample 15 and a leakage current of about 2 It was confirmed that it was an order of magnitude smaller.

Further, the capacitance of the thin film capacitor 100 of the sample 2dd was 36.0 nF, and the leakage current was 2.8 × 10 ⁻⁸ A. Thus, the sample 2dd thin film capacitor 100 in which the upper electrode is changed to Ni also has a capacitance more than twice as large as that of the conventional sample 15 thin film capacitor, and the leakage current is almost one digit smaller. It was confirmed.

The thin film capacitor 100a of Sample 14 had a capacitance of 90.6 nF and a leakage current of 4.3 × 10 ⁻⁹ A. Thus, according to the present invention, it was confirmed that a high capacity of 40 nF or more can be realized with the 1005 size thin film capacitor 100a.

  2 ... Base electrode, 4, 6, 60 ... Dielectric layer, 4a, 6a ... Dielectric film, 8 ... Internal electrode, 8a ... Internal electrode layer, 10 ... Upper electrode DESCRIPTION OF SYMBOLS 10a ... Upper electrode layer, 12a, 12b ... Terminal electrode, 14 ... Cover layer, 100, 100a ... Thin film capacitor, 20a, 20b, 20c, 20d ... Mask, 200, 200a, 200b, 200c, 200d ... laminated body.

Claims (3)

A base electrode containing 99.99% by weight or more of Ni;
Two or more dielectric layers stacked on the base electrode;
At least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Os, Re, W, Cr, Ta and Ag, which is laminated between the dielectric layers and contains Ni as a main component. Containing internal electrodes;
A thin film capacitor comprising: an upper electrode made of Cu or a Cu alloy, which is laminated on the opposite side of the base electrode with the dielectric layer and the internal electrode interposed therebetween. It is a manufacturing method of the thin film capacitor according to claim 1,
The base electrode, two or more dielectric films stacked on the base electrode, and Ni as a main component stacked between the dielectric films, and further Pt, Pd, Ir, Rh, An internal electrode layer containing at least one selected from the group consisting of Ru, Os, Re, W, Cr, Ta, and Ag, and then forming the base electrode, the two or more dielectric films, and the internal electrode A step of simultaneously firing the layers to form a laminate;
Forming an upper electrode layer made of Cu or Cu alloy on the surface of the laminate that is located on the opposite side of the base electrode;
Forming the dielectric layer, the internal electrode, and the upper electrode by patterning the dielectric film, the internal electrode layer, and the upper electrode layer, respectively. It is a manufacturing method of the thin film capacitor according to claim 1,
The base electrode, two or more dielectric films stacked on the base electrode, and Ni as a main component stacked between the dielectric films, and further Pt, Pd, Ir, Rh, An internal electrode layer containing at least one selected from the group consisting of Ru, Os, Re, W, Cr, Ta and Ag, and laminated on the opposite side of the base electrode with the dielectric film and the internal electrode layer in between. Forming a laminate comprising: an upper electrode layer made of Cu or Cu alloy;
Forming the dielectric layer, the internal electrode, and the upper electrode by wet-etching the dielectric film, the internal electrode layer, and the upper electrode layer, respectively, after forming the stacked body. Manufacturing method of thin film capacitor.

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