JP2015126155A - Thin film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film capacitor in which degradation of breakdown voltage performance is prevented.SOLUTION: A thin film capacitor 1 includes a lower electrode 2, a dielectric layer 3 provided on the lower electrode, and an upper electrode 4 formed on the dielectric layer, and has an insulator structure 5 enclosing a defect 6 included in a part of the dielectric layer. The outermost part of the insulator structure has a tapered cross-sectional shape. The tapered cross-sectional shape of the insulator structure has (1) a tangent in contact with the position of 50% of the maximum height of the insulator structure at the outermost part thereof, and (2) a tapered cross-sectional angle where the angle formed by the dielectric layer and a line, i.e., the interface with the upper electrode, is smaller than 25 degrees. The outermost part of the insulator structure is not in contact with the end of a defect, and the distance from the end of a defect to the outermost part of the insulator structure is 20-150 times of the thickness of a dielectric film.

Description

The present invention relates to a thin film capacitor.

In recent electronic devices, the space for mounting electronic components tends to be reduced. For this reason, a capacitor (referred to as a “capacitor”) is required to have a low-profile element.
Thinning the dielectric layer is effective for reducing the height of the capacitor. As a capacitor having a thin dielectric layer, a capacitor having a dielectric layer formed by using a thin film forming technique such as sputtering (hereinafter referred to as “thin film capacitor”) is known (see Patent Document 1). The thin film capacitor described in Patent Document 1 is formed by laminating a first electrode layer, a dielectric layer, and a second electrode layer in this order on a base substrate.

In the conventional thin film capacitor, when the dielectric layer thickness is reduced, defects occur in the dielectric layer, causing a short circuit failure, increasing a leakage current, and decreasing a withstand voltage. It was. Here, the “defect” means a portion different from the normal state of the dielectric, such as a foreign matter, a dielectric crack, or a pinhole, existing on the dielectric layer or inside the dielectric layer.

Japanese Patent Application Laid-Open No. 2004-228561 suggests that the problems of occurrence of short-circuit failure, increase in leakage current, and decrease in withstand voltage are caused by pinhole portions and crystal grain boundaries existing in the dielectric layer. In Patent Document 1, as a means for solving this problem, an insulating layer is formed by oxidizing the material constituting the first electrode layer between the pinhole portion of the dielectric layer or the grain boundary and the first electrode layer. The technology to do is disclosed.

In Patent Document 2, an insulating layer or a low dielectric layer is laminated on a lower conductor pattern, and a defective portion such as an insulating layer in a multilayer wiring board in which an upper conductor pattern is laminated on the insulating layer or the like is disclosed. The technology to repair is disclosed. In this technique, after formation of an insulating layer or the like, an insulating material such as an epoxy resin is attached to a deficient portion of the insulating layer or the like by using an electrodeposition method in which a lower conductive pattern is one electrode.

Patent Document 3 discloses a manufacturing method for forming a resin insulator using an electrophoresis method on a pinhole portion or the like of a dielectric layer.

JP 2002-26266 A JP 2002-185148 A JP 2008-160040 A

As disclosed by the inventors of Patent Documents 1 to 3, a technique for improving the breakdown voltage performance by coating a defect in a dielectric layer with some insulator structure is known. However, the present inventors have found that even with such coating, the thin film capacitor may not have sufficient withstand voltage performance.

For example, when the outermost part of the insulator structure has a steep taper section angle, or when the distance from the end of the insulator structure to the end of the defect must be close, the insulator structure The electric charge stored in is transmitted to the interface between the insulator structure and the dielectric layer and reaches a defect, so that the breakdown voltage of the thin film capacitor is lowered.

The present invention has been made in view of the above knowledge, and an object thereof is to provide a thin film capacitor having improved withstand voltage performance.

A thin film capacitor that solves the above problem includes a lower electrode, a dielectric layer provided on the lower electrode, and an upper electrode formed on the dielectric layer. The dielectric layer of the thin film capacitor contains defects. An insulator structure is formed at the interface between the dielectric layer and the upper electrode layer of the thin film capacitor. This insulator structure includes a defect so as not to be exposed to the upper electrode. The cross-sectional structure of the insulator structure is as follows: (1) a tangent line that is at the end of the insulator structure and touches 50% of the maximum height of the insulator structure; and (2) a dielectric layer; An angle formed by a line that is an interface with the upper electrode (hereinafter referred to as a “taper section angle”) has a gentle taper section angle that is smaller than 25 degrees. By adopting this structure for the thin film capacitor, an effect of suppressing the movement of charges at the interface between the insulator structure and the dielectric layer can be obtained. Although the cause of this effect is not necessarily clear, the inventors first move the interface between the insulator structure and the dielectric layer because the outermost part of the insulator structure is separated from the defect. The charge is consumed before it reaches the defect, and secondly, the outermost part of the insulator structure has a gentle shape, so electric field concentration is less likely to occur. Yes. As a result of this effect, short circuit failure of the thin film capacitor can be prevented by implementing the present invention, and characteristics such as sufficient capacity can be secured. Such an insulator structure is realized by forming an electrodeposition resin using an electrophoresis method. Moreover, according to the electrophoresis method, an insulator structure can be selectively formed with respect to a defect that causes current leakage.

The shortest distance from the edge of the defect to the outermost part of the insulator structure is not less than 20 times and not more than 150 times the thickness of the dielectric layer. The charge accumulated in the outermost part of the insulator structure has a thickness direction of the dielectric layer (having an electric resistance value R1) and an interface direction (electric resistance value R2) between the insulator structure and the dielectric layer. ) And may move on. The inventors examined these electric resistances through simulations and experiments. Although the relationship between the resistance values R1 and R2 varies depending on the material types of the dielectric layer and the insulator structure, the resistance value R1 is generally about 150 times that of R2. When the shortest distance from the edge of the defect to the outermost part of the insulator structure (hereinafter, this distance is expressed as “L _min ”) exceeds 150 times the thickness of the dielectric layer, it is short-circuited to the thin film capacitor. And the probability of leakage current increases. This is presumably because the charge accumulated on the outermost part of the insulator structure tends to flow in the thickness direction of the dielectric layer having a relatively low electrical resistance. From the viewpoint of thin film capacitor products, it is preferable that the size of the insulator resistor is small. This is because if the area is large, the capacity of the thin film capacitor tends to be impaired. Further, the resin may become an obstacle when fine patterning is performed on the thin film capacitor. However, even when L _min is less than 20 times the thickness of the dielectric layer, the probability of a short circuit or leakage current occurring in the thin film capacitor increases. This is presumably because the charge consumption in the planar direction is not sufficient and the charge reaches the defect.

The taper cross-sectional angle is preferably 1 degree or more and 10 degrees or less. In the case of an angle exceeding 10 degrees, charge accumulation at the outermost part is increased, which may cause a short circuit or a leakage current. When the angle is less than 1 degree, film adhesion failure may occur, and charge accumulation is wide-ranging, which may cause a short circuit or a leakage current.

According to the thin film capacitor of the present invention, it is possible to provide a thin film capacitor in which short circuit failure is prevented.

1 is a schematic cross-sectional view showing a thin film capacitor according to an embodiment of the present invention. It is an observation image by the optical microscope of the electrodeposition part which concerns on embodiment of this invention. It is a cross-sectional observation image by SEM (scanning electron microscope) of the electrodeposition part which concerns on embodiment of this invention. It is the schematic of the electrodeposition apparatus which concerns on embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

FIG. 1 is a cross-sectional view of a thin film capacitor according to an embodiment of the present invention. The thin film capacitor 1 includes a lower electrode 2, a dielectric layer 3 formed on the lower electrode 2, and an upper electrode 4 formed thereon.

As a material of the lower electrode 2 in the present embodiment, a known conductive material can be appropriately selected. A well-known conductive material means a metal, a metal oxide, a conductive organic material etc., for example. In particular, since the lower electrode 2 desirably has a low electrical resistance and desirably has a high mechanical strength, it is preferable to use a metal material. Among these, Ni and Cu are preferable because they are relatively tough metal materials having low electrical resistance. In particular, from the viewpoint of high temperature load reliability and moisture resistance load reliability, a conductor containing at least Ni is desirable. Here, the Ni-containing conductor means pure Ni (Ni 99.9% or more) or a Ni-based alloy. In the case of a Ni-based alloy, it is desirable to include a noble metal element such as Pt, Pd, Ir, Ru, Rh, for example, and the content is desirably 50 wt% or less. If it is in the range of such a content rate, the high temperature load reliability and moisture-proof load reliability of the thin film capacitor 1 equivalent to the case where pure Ni is used will be obtained.

The form of the lower electrode 2 in this embodiment can select various forms, such as the electroconductive foil containing a metal, the sintered compact containing a metal, or the electroconductive thin film formed on arbitrary board | substrates. The lower electrode 2 is particularly preferably a Ni metal foil made of a metal polycrystal. By using the metal foil, it becomes possible to reduce the difference in thermal expansion coefficient from the dielectric layer, and to suppress the decrease in the capacity of the thin film capacitor 1. As the conductive thin film, for example, a Ni electrode layer may be formed as the lower electrode 2 by sputtering or vapor deposition on a Si substrate or a ceramic substrate (not shown). In such a form, it is desirable to select a material having a small difference in thermal expansion coefficient from the dielectric layer 3 for the substrate. As the substrate, for example, a Si substrate with a Ni film, a ceramic substrate with a Ni film, or the like can be used. Thereby, the capacity | capacitance fall of the thin film capacitor 1 resulting from a thermal expansion coefficient difference can be suppressed.

The form of the lower electrode 2 in the present embodiment may further include a different conductive material interposed between the lower electrode 2 and the dielectric layer 3. Alternatively, a multilayer electrode structure may be used. The multilayer electrode structure may be a multilayer electrode film in which a Ni electrode layer is disposed on the side in contact with the dielectric layer 3. Such a multilayer electrode layer may have a structure in which, for example, a Ni electrode layer is formed on a Cu metal foil by sputtering or vapor deposition and stacked. However, when the Ni electrode layer and the dielectric layer 3 are in contact with each other, the high temperature load reliability and moisture resistance load reliability of the thin film capacitor 1 are further improved.

The material of the dielectric layer 3 in this embodiment is preferably a perovskite oxide dielectric having a large dielectric constant. Among the perovskite-type dielectrics, a lead-free barium titanate-based dielectric is preferable from the viewpoint of environmental protection. In the case of a barium titanate-based dielectric material, a Ba site partially substituted with an alkaline earth such as Ca or Sr may be used. Moreover, you may use what substituted a part of Ti site by elements, such as Zr, Sn, and Hf. Further, rare earth elements, Mn, V, Nb, Ta, or the like may be added to the dielectric.

The formation of the dielectric layer 3 in the present embodiment can be appropriately performed by a method usually used in thin film formation, such as solution coating, sputtering, vapor deposition, PLD (Pulse Laser Deposition), and CVD.

The structure of the dielectric layer 3 in the present embodiment is preferably a thin film having a thickness of 1000 nm or less. If it exceeds 1000 nm, the capacitance value per unit area may decrease. There is no particular lower limit to the film thickness, but the insulation resistance value decreases as the thickness decreases. Therefore, 50 nm or more is considered necessary. Considering the above relationship between the insulation resistance value and the capacitance, it is considered that the preferable thickness range of the dielectric layer 3 of the thin film capacitor 1 is 250 nm to 1000 nm. Note that the dielectric layer 3 in the present embodiment contains defects that are difficult to avoid stochastically.

In the present embodiment, the insulator structure 5 is formed after the dielectric layer 3 is formed. The surface of the dielectric layer 3 is preferably subjected to surface treatment or physical cleaning before the insulator structure 5 is formed. As the surface treatment, etching with acid or alkali, etching with plasma, or the like may be performed. As the physical cleaning, ultrasonic cleaning or polishing may be performed. By these treatments, the interface state between the dielectric layer 3 and the insulator structure 5 becomes good, so that the electrical characteristics become stable in the long term. In addition, in the step of forming the insulator structure 5 to be described later, selectivity can be exhibited so that the formation of the insulator structure 5 is concentrated on the defects of the dielectric layer 3.

The material of the insulator structure 5 in the present embodiment is preferably a resin material with high electrical resistance. This is because the insulator structure 5 itself has a flexible structure with high electrical resistance, so that the electrical state at the interface with the dielectric layer 3 is hardly changed through the use of the thin film capacitor 1 after completion. Such a resin material can be appropriately selected from known high electrical resistance resin materials. Specifically, it can be selected from resin materials such as acrylic resin, epoxy resin, fluorine resin, urethane resin, amide resin, phenol resin, PEEK resin, polycarbonate resin, polybutadiene resin, and polyimide resin. These resin materials may be used alone or in combination of two or more.

The structure of the insulator structure 5 in the present embodiment is an insulator patch-like structure with the defect of the dielectric layer 3 approximately at the center. The shape of a typical insulator structure 5 according to this embodiment is shown in FIGS. FIG. 2 is an image observed by an optical microscope when the insulator structure 5 of the present embodiment is viewed from above. The dielectric layer 3 has a defect 6 formed by peeling off after the impurity particles are adhered, and the insulator structure 5 is formed in a substantially circular patch shape with the defect 6 positioned substantially at the center. Is formed on top. L _min formed by the end of the defect 6 and the outermost part of the insulator structure 5 can be read from a planar observation photograph as shown in FIG. The insulator structure 5 of this embodiment is 40 μm as shown by the arrow in FIG. When the defect 6 has an irregular shape, for example, a scratch extending over a relatively long distance, it may be formed as an elliptical or curved patch shape according to the shape of the defect. In this case, L _min can be defined by reading the shortest distance between the end of the defect 6 and the outermost part of the insulator structure 5. The position to be read can be determined empirically as the position where the electric charge flows most easily from the insulator structure 5 toward the defect 6. FIG. 3 is a cross-sectional observation image of the insulator structure 5 of the present embodiment using an SEM (scanning electron microscope). The cross-section observation is performed on a cross section obtained by cutting the lower electrode 2, the dielectric layer 3, and the insulator structure 5 around the defect 6. In the example of the insulator structure 5 of this embodiment illustrated in FIG. 2 and FIG. 3, L _min is 40 μm and the film thickness of the dielectric layer 3 is 1 μm as described above. The ratio of thickness to L _min is 40 times. This is a range in which the reduction in dielectric strength of the thin film capacitor according to the implementation of the present invention can be more effectively suppressed. In particular, the insulator structure 5 is (1) a thin thin film having a uniform film thickness so as to completely cover the defect 6, and (2) a gentle taper at the patch-shaped end. It can be seen that it has a cross-sectional angle. In particular, (2) has a taper cross-sectional angle of about 5 degrees with respect to the surface of the dielectric layer.

The unique shapes such as (1) and (2) seen in the insulator structure 5 in the present embodiment are obtained by electrophoresis using pure water as a solvent and dispersing the monomer of the resin material. The resin material can be formed by electrodeposition on the surface of the dielectric layer 3. However, the electrophoresis method of the present embodiment is a structure of an apparatus different from the conventional electrodeposition formation of a resin material, and is a forming condition. FIG. 4 shows a schematic diagram of an electrodeposition apparatus according to an embodiment of the present invention. Specifically, (A) the anode electrode 8 used in the electrophoresis method has a structure in which an immobile film made of oxide such as alumina, silica, or iron oxide is formed on the surface of a SUS material that is an electrode body. And (B) using a production condition for setting the resin material content in the electrodeposition solution to a low concentration of 0.1 wt% or more and 1.0 wt% or less.

The reason why the shape of the insulator structure 5 in the present embodiment is obtained by the electrodeposition electrophoresis method combining the above requirements (A) and (B) is not necessarily clear. The present inventors presume the mechanism as follows through research.

By the requirement (A), the electron extraction reaction from the resin material monomer in the electrodeposition solution is suppressed, and the ratio of the polar monomer is reduced. The polar monomer tends to collect in the defect 6 where the electric field of the dielectric layer 3 is maximum. Other non-polar monomers move to the surface of the dielectric layer 3 to be dragged by the polar monomers, but do not have an electrical potential to be attracted to the defect 6, so that before reaching the defect 6 Adsorbed on the dielectric layer 3. The kinetic energy of the nonpolar monomer has a certain distribution as a group in the electrodeposition solution. Therefore, the shape of the insulator structure 5 has a spread in the plane direction and the thickness direction according to the kinetic energy distribution of the nonpolar monomer. As a result, the insulator structure 5 of the present embodiment has a substantially circular patch-like shape in which the defect 6 is arranged at the approximate center and the end is tapered in the dielectric layer 3.

Note that the taper cross-sectional angle of the insulator structure 5 also changes depending on the strength of the current. The taper cross-sectional angle tends to increase at high currents, and the taper cross-sectional angle tends to decrease at low currents. This result is considered to be because the area of the dielectric layer 3 that the nonpolar monomer can reach changes as the potential at which the polar monomer is attracted to the defect 6 increases or decreases. In this embodiment, electrodeposition is performed with a low current (1 to 50 mA) as an electrophoretic method of the resin material.

The requirement (B) suppresses excessive monomer association in the electrodeposition solution. The electrophoresis method in the present embodiment is performed by dispersing a monomer of a resin material in a solvent of pure water. In this case, if the concentration of the monomer is high, association between the monomers occurs in the solvent, and the monomer may be carried to the surface of the dielectric layer 3 as an aggregate. Since the monomer as an aggregate may include a polar monomer, a large amount of monomer may be deposited in the vicinity of the defect 6. By reducing the resin material content in the electrodeposition solution to a low concentration of 0.1 wt% or more and 1.0 wt% or less, the association probability of the monomer in the solvent is lowered, so that the monomer is not an aggregate but a single substance. The probability of moving to the surface of the dielectric layer 3 is increased. As a result, the shape of the insulator structure 5 has a spread in the surface direction and the thickness direction according to only the kinetic energy distribution of the monomer, and the outermost portion has a tapered shape with the defect 6 disposed substantially at the center. Presents a substantially circular patch shape.

In addition to adjusting the resin material content in the electrodeposition solution as described above, an appropriate amount of a dispersant may be added to the electrodeposition solution. As such a dispersant, a known surfactant can be appropriately used. In particular, surfactants such as alkyl glucoside, polyethylene glycol, and fatty acid sodium can be used. Alternatively, the monomer of the resin material may be dispersed by ultrasonic stirring.

In the thin film capacitor 1 of the present embodiment, the upper electrode 4 is formed after the insulator structure 5 is formed. As a material of the upper electrode 4 of the present embodiment, a known conductive material can be appropriately selected. A well-known electroconductive material means a metal, a metal oxide, a conductive organic material etc., for example, These can be selected suitably. In particular, it is preferable that the upper electrode 4 has a low electrical resistance and a high mechanical strength. Therefore, it is preferable to use a metal. Among these, Ni and Cu are preferable because they are relatively tough metal materials having low electric resistance. The upper electrode 4 may be a single layer of a Ni electrode layer or a Cu electrode layer, but may have a two-layer structure of a Ni electrode layer and a Cu electrode layer. Different conductive materials may be interposed between the upper electrode 4 and the dielectric layer 3 or the insulator structure 5. When the upper electrode 4 includes an Ni electrode layer, it is desirable that the Ni electrode layer side is in contact with the dielectric layer 3 from the viewpoint of reliability. When a Ni electrode layer is used for all or part of the upper electrode 4, pure Ni or a Ni-based alloy can be used as in the lower electrode layer 1. In the case of a Ni-based alloy, it is desirable to contain a noble metal element such as Pt, Pd, Ir, Ru, Rh, and the content is desirably 50 wt% or less. Further, the thickness is preferably in the range of 0.1 μm to 2.0 μm.

A Cu electrode layer may be formed on the Ni electrode layer of the present embodiment. The Cu electrode layer here is preferably pure Cu (Cu 99.9% or more) or a Cu-based alloy. In the case of an alloy, it is desirable to include a noble metal element such as Pt, Pd, Ir, Ru, and Rh, and the content is desirably 50 wt% or less. Cu has the same resistivity as Au and Ag, and is characterized by being easy to use industrially. Therefore, it is often used for wiring of electronic equipment. Further, since the resistivity is relatively small, when used as an electrode layer of a thin film capacitor, there is an effect of reducing the equivalent series resistance (ESR).

In forming the upper electrode 4, a method usually used in thin film formation, for example, application of a solution, sputtering, vapor deposition, PLD (Pulse Laser Deposition), CVD, or the like can be used as appropriate.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

Example 1
A dielectric layer (BaTiO ₃ dielectric) was formed to a thickness of 800 nm on a Ni metal foil having a size of 100 mm × 100 mm by a sputtering method. Thereafter, annealing was performed to crystallize the dielectric layer on the Ni metal foil. As a pretreatment for forming the insulator structure, foreign matters and the like were removed by scrub cleaning.

A Ni metal foil having a crystallized dielectric layer is provided as an anode electrode, an electrode in which an alumina non-moving body coating is formed on a SUS material, and an electrolytic solution containing 1 wt% of an imide resin in pure water is provided as an electrolytic solution. It was immersed in an electrodeposition bath. With the Ni foil immersed in the electrodeposition solution, electrodeposition is performed while the voltage is appropriately controlled at a current of 35 mA while visually observing the electrodeposition, and cured in an oven at 200 ° C. to form an insulator structure. did. A portion of a plurality of insulator structures was separated from the sample so far, and the appearance was observed with an optical microscope and the cross section was observed with an electron microscope. The shape of the insulator structure had a maximum film thickness of 1.2 μm, The taper section angle was 18 degrees, and the shortest distance from the outermost part of the insulator structure to the edge of the defect was 36 μm (about 30 times the dielectric thickness). Thereafter, Ni and Cu were formed as an upper electrode layer in this order by sputtering.

After the formation of the upper electrode layer, the upper electrode layer was patterned and annealed in a vacuum at 340 ° C. This annealing was performed for grain growth of the Cu electrode layer. With respect to 100 capacitor elements of 5 mm × 5 mm subjected to patterning, the following capacitance values and insulation resistance values were measured.

The capacitance value was measured using an Agilent LCR meter 4284A at 1 kHz, 1 Vrms, and room temperature (25 ° C.). The insulation resistance value was measured at 4 V DC and room temperature (25 ° C.) using an Agilent 4339B high resistance meter.

As a result, a non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained at 90% (90/100 pcs) of the measurement points.

(Example 2)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.8% and a current of 30 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 42 μm (35 times the dielectric thickness), the taper cross-sectional angle is 15 degrees, and the measurement point is 93% (93/100 pcs). A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 3)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.6% and a current of 25 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 48 μm (40 times the dielectric thickness), the taper section angle is 10 degrees, and 98% (98/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

Example 4
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.5% and a current of 20 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 60 μm (50 times the dielectric thickness), the taper section angle is 8 degrees, and 100% of the measurement point (100/100 pcs). A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 5)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.4% and a current of 15 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 84 μm (70 times the dielectric thickness), the taper cross-sectional angle is 5 degrees, and 99% (99/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 6)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.3% and a current of 10 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 108 μm (90 times the dielectric thickness), the taper section angle is 3 degrees, and 97% (97/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 7)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.2% and a current of 5 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 120 μm (100 times the dielectric thickness), the taper cross section angle is 1 degree, and 94% (94/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 8)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.1% and a current of 2 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect was 144 μm (120 times the dielectric thickness), the taper cross-sectional angle was 0.5 degrees, and 91% of measurement points (91/100 pcs) ), A non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

Example 9
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 3% and a current of 50 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 24 μm (20 times the dielectric thickness), the taper cross-sectional angle is 23 degrees, and 75% (75/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 10)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 2% and a current of 40 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 30 μm (25 times the dielectric thickness), the taper cross-sectional angle is 21 degrees, and 85% (85/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 11)
Fabrication and measurement were performed in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.08% and a current of 1 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect was 276 μm (130 times the dielectric thickness), the taper cross-sectional angle was 0.4 degrees, and 83% (83/100 pcs) of the measurement point ), A non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Example 12)
It was produced and carried out in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.06% and a current of 0.5 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 180 μm (150 times the dielectric thickness), the taper cross-sectional angle is 0.3 degree, and 77% (77/100 pcs) of the measurement point. ), A non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained.

(Comparative Example 1)
It was produced and carried out in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 10% and a current of 80 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 12 μm (10 times the dielectric thickness), the taper section angle is 28 degrees, and 3% (3/100 pcs) of the measurement point. A good product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained. This is considered to be caused by charges flowing from the planar direction to defects in the dielectric layer.

(Comparative Example 2)
It was produced and carried out in the same manner as in Example 1 except that electrodeposition was performed at a polyimide concentration of 0.8% and a current of 0.3 mA. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 240 μm (200 times the dielectric thickness), the taper cross-sectional angle is 0.3 degrees, and 5% of the measurement point (5/100 pcs) ), A non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained. This is probably because the insulator structure was too large, and the charge flowed to defects in the dielectric layer having a relatively low resistance.

(Comparative Example 3)
It was produced and carried out in the same manner as in Example 1 except that an anode electrode that did not form a nonconductive film on the surface (the surface facing the direction of the dielectric layer) was used. As a result, the shortest distance from the outermost part of the insulator structure to the edge of the defect is 6 μm (about 5 times the dielectric thickness), the taper cross-sectional angle is 43 degrees, and 1% of measurement points (1/100 pcs) Thus, a non-defective product having a capacitance value of 2.5 × 10 ⁻⁷ F or more and an insulation resistance value of 5 × 10 ⁺⁸ Ω or more was obtained. This is probably because the taper cross-sectional angle was steep and the charge flowed into the dielectric layer defect starting from the outermost part of the insulator structure.

Table 1 summarizes the series of examples and comparative examples described above.

The inventors of the present invention have confirmed through the examples and comparative examples that the thin film capacitor obtained by the implementation of the present invention has a good withstand voltage performance.

DESCRIPTION OF SYMBOLS 1 Thin film capacitor 2 Lower electrode 3 Dielectric layer 4 Upper electrode 5 Insulator structure 6 Defect of dielectric layer 7 Electrodeposition apparatus 8 Anode electrode 9 Cathode electrode 10 Electrodeposition sample (lower electrode 2 and dielectric layer 3 were provided (Deposition body)
11 Electrodeposition tank

Claims (2)

A lower electrode, a dielectric layer provided on the lower electrode, and an upper electrode formed on the dielectric layer,
The dielectric layer includes defects;
An insulator structure is formed at the interface between the dielectric layer and the upper electrode layer,
The insulator structure includes the defect so as not to be exposed to the upper electrode,
The cross-sectional structure of the insulator structure is as follows: (1) a tangent line at the end of the insulator structure and in contact with 50% of the maximum height of the insulator structure; and (2) a dielectric layer and an upper portion. The angle formed by the line that is the interface with the electrode has a taper cross-sectional angle that is 1 degree or more and less than 25 degrees;
The distance from the defect end to the outermost part of the insulator structure is 20 to 150 times the thickness of the dielectric film. 2. The thin film capacitor according to claim 1, wherein the taper cross-sectional angle is not less than 1 degree and not more than 10 degrees.