JPH07106198A - Manufacture of laminated thin-film capacitor - Google Patents

Abstract

PURPOSE:To provide the method of manufacturing a laminated thin-film capacitor, which can miniaturize a chip capacitor and which can make the capacity of the chip capacitor large. CONSTITUTION:A dielectric thin-film layer 4 in a film thickness of 3mum or lower is formed, by a plasma CVD method, on a substratum substrate 1 on which a metal-electrode thin-film layer 2 has been formed by a vacuum deposition method or a sputtering method. The two layers are laminated alternately, a laminated body is cut in such a way that metal-electrode thin-film layers 2, 4, 6 faced alternately sidewalls every other layer, external electrodes 8, 9 are formed on cut faces, the electrodes are brought into continuity with the metal-electrodes thin-film layers 2, 4, 6 at the inside, and a small and large- capacity laminated thin-film capacitor is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer thin film capacitor used as a small-sized, large-capacity chip capacitor.

[0002]

2. Description of the Related Art Strontium titanate (SrTiO ₃ ) having a perovskite crystal structure is a cubic crystal and a paraelectric material at a temperature of about 110 K or higher. Ceramics containing strontium titanate as a main component have a lower dielectric constant than barium titanate (BaTiO ₃ ) based on the same crystal structure, but have characteristics of good temperature characteristics and small dielectric loss. Further, by adding a shifter such as barium or lead to shift the Curie point, a paraelectric ceramic having a high dielectric constant can be obtained at room temperature, which is widely used as a capacitor for high frequency and high voltage.
In addition, Pb (Mg) which is one of typical relaxation type ferroelectrics
Pb (Mg _1/3 , Nb _2/3 ) O ₃ -PbTiO ₃ which is a composite material of _1/3 , Nb _2/3 ) O ₃ and lead titanate (PbTiO ₃ ).
The complex perovskite compound of (1) has a large relative permittivity and good DC bias characteristics as compared with barium titanate-based ferroelectrics, and is therefore applied to small and large capacity multilayer capacitors.

On the other hand, in order to cope with miniaturization of electronic equipment and high-density mounting, miniaturization and large capacity of chip capacitors are being advanced. In order to achieve high capacity, there is a method of using a dielectric material having a large relative dielectric constant or a method of increasing the number of layers by thinning the dielectric layer. For example, electronic
Ceramics Magazine No. 103 (1990), pages 57 to 6
A manufacturing method of a monolithic ceramic capacitor is announced on page 1. The method of laminating the dielectric layer and the metal electrode layer in the production of the laminated ceramic capacitor in this document is as follows. Mixing powder of dielectric material such as BaTiO ₃ ,
The mixed and dried product is slurried and formed into a thin film sheet. An internal electrode paste such as palladium is printed on this sheet, and the sheets are stacked. This operation is repeated several times, and then cut to a desired size, and the ceramic and metal are co-fired.

[0004]

However, in the above-mentioned lamination method, the starting material BaTiO ₃ is a powder having a particle size of about 1 μm, and this is compounded into a slurry, molded into a sheet and fired, so that the dielectric layer is formed. Is less than 3 μm, there is a problem in film thickness uniformity and insulation between electrodes.
It was technically difficult. Further, since the firing temperature is as high as about 1200 ° C. and the electrode materials are limited, it has been required to find a manufacturing method for obtaining an inexpensive and excellent laminated capacitor at low temperature.

In view of the above-mentioned conventional problems, the present invention has an object to provide a method for manufacturing a laminated thin film capacitor which enables miniaturization and large capacity of a chip capacitor.

[0006]

In order to solve the above-mentioned problems, the present invention is to form a metal electrode thin film layer on a substrate by a vacuum deposition method or a sputtering method, and form a dielectric thin film layer on the substrate by using titanic acid. perovskite oxide and Pb (Mg _1/3 composed mainly of strontium, Nb
_2/3 ) A composite perovskite type compound containing O ₃ and lead titanate as main components is formed by a plasma CVD method utilizing plasma activation and a CVD reaction, and this operation is repeated to form a metal electrode thin film layer on the substrate. A laminated thin film capacitor is manufactured by cutting a laminate of a dielectric thin film layer and a dielectric thin film into a predetermined size, and forming external electrodes on the cut surface by a vacuum deposition method, a sputtering method, a plating method, or a coating baking method. is there.

[0007]

According to the present invention, by using the plasma CVD method for forming the dielectric thin film layer, strontium titanate or Pb (Mg _{1 /} Mg _{1 /
3,} Nb _2/3) dense perovskite dielectric thin film with O ₃ -PbTiO ₃ as the main component is relatively obtained at low temperatures. Also, by using the vacuum deposition method or the sputtering method for forming the metal electrode thin film layer, a dense and thin metal electrode thin film layer can be obtained. Therefore, the electrostatic capacitance per unit volume becomes large, and the multilayer thin film capacitor corresponding to miniaturization and large capacity can be manufactured at a temperature lower than the firing temperature of the bulk.

[0008]

【Example】

(Embodiment 1) FIG. 1 is a schematic view showing a cross-sectional structure of a multilayer thin film capacitor in one embodiment of the present invention.

In FIG. 1, 1 is a base substrate made of alumina, 2, 4, 6 are metal electrode thin film layers made of metallic platinum,
3, 5, 7 are dielectric thin film layers made of SrTiO ₃ , 8,
Reference numeral 9 is an external electrode made of silver.

A method of manufacturing a laminated thin film capacitor composed of the above constituent elements is as follows. A metal electrode thin film layer 2 is patterned on a base substrate 1 by a vacuum deposition method as shown in FIG. The dielectric thin film layer 3 is formed thereon by the plasma CVD method. Further, a metal electrode thin film layer 4 is patterned thereon by a vacuum vapor deposition method, offset from the metal electrode thin film layer 2 as shown in FIG. Further thereon, the dielectric thin film layer 5 is formed by the plasma CVD method. Further, a metal electrode thin film layer 6 is formed thereon by a vacuum deposition method in the same pattern as the metal electrode thin film layer 2 as shown in FIG. Further thereon, the dielectric thin film layer 7 is formed by the plasma CVD method. After repeating this operation to stack a predetermined number of layers, as shown in FIG. 1B, the metal electrode thin film layers are cut into a predetermined size such that every other metal electrode thin film layer faces alternating side walls. External electrodes 8 and 9 made of silver are applied to the cut surface and baked to establish electrical connection between the internal metal electrode thin film layers 2 and 46 and the external electrodes 8 and 9.

Among the above manufacturing methods, a method for forming a dielectric thin film layer will be described below. FIG. 2 is a schematic diagram of a plasma CVD apparatus used for forming a dielectric thin film layer in the multilayer thin film capacitor in one embodiment of the present invention.

In FIG. 2, as components, 10 is a reaction chamber, 11 is an electrode, 12 is a substrate rotation motor, 13
Is a substrate heater, 14 is a base substrate made of alumina, 15 is an exhaust system, 16 is a high frequency power source (13.56 MH)
z).

On the other hand, vaporization vessels 17, 18 and 1 containing raw materials
9 and 20 are connected to the pipes opened between the electrodes 11 in the reaction chamber 10 through valves 25, 26, 27 and 28, and the pipes introduced into the vaporization vessels 17, 18, 19 and 20 are , Valves 21, 22, 2
It is connected to an argon cylinder 29 for carrier gas through 3, 24, and the introduction of the source gas and the carrier gas into the reaction chamber 10 is controlled by opening and closing the valves 25, 26, 27, 28. Further, the oxygen cylinder 30 is connected to a pipe opened between the electrodes 11 in the reaction chamber 10. Strontium dipivaloyl methane [Sr (C ₁₁ H ₁₉ O ₂ ) ₂ ] and isopropoxy titanium [Ti (C ₃ H ₇ O) ₄ ] were used as starting materials.

The method for forming the dielectric thin film layer is as follows. The base substrate 14 on which the metal electrode thin film layer of metal platinum is patterned in advance by the vacuum deposition method is used as the substrate heater 1.
Attached to No. 3, heated to 700 ° C. and held. Vaporization container 1
Vaporization vessel 1 with strontium dipivaloyl methane in 7
Put isopropoxytitanium in 8 and 235 ℃,
It was heated to and held at 50 ° C. The inside of the reaction chamber 10 is evacuated by the exhaust system 15, and the substrate heating motor 12 and the underlying substrate 14 together with the substrate heating heater 13 are evacuated to 12 per minute.
It rotated at a speed of 0 revolutions. Valves 17, 18, 25, 2
6 is opened, and strontium dipivaloylmethane and isopropoxytitanium vapors are introduced into the reaction chamber 10 by the carrier gas (vaporizers 17 and 18 with flow rates of 25 SCCM and 5 SCCM, respectively) together with oxygen as a reaction gas (flow rate of 10 SCCM). Introduced and reacted in plasma (power 1.4 W / cm ² ) under reduced pressure (0.02 Torr) for 50 minutes to form a dielectric thin film layer of SrTiO ₃ on which a metal electrode thin film layer was patterned. A film was formed on the substrate 14. After cooling this, it was taken out, the metal electrode thin film layer was pattern-formed again on the dielectric thin film layer by the vacuum evaporation method, and the dielectric thin film layer was formed thereon by the same method as described above. Thereafter, this operation was repeated to stack 10 metal electrode thin film layers and 10 dielectric thin film layers. As shown in FIG. 1, this is cut into a predetermined size together with the substrate so that every other metal electrode thin film layer faces the alternate side walls, and silver is applied to the cut surface and baked to form an external electrode. Formed.

For the analysis of the dielectric thin film layer, a sample was prepared in which metallic platinum was deposited on an alumina substrate and a thin film of SrTiO ₃ was deposited thereon by the same method as above.

The thickness of the dielectric thin film layer of the obtained laminated thin film capacitor was 2.2 μm per layer, and the thickness of the metal electrode thin film layer was 0.06 μm per layer. The electrical characteristics were measured between the electrodes 8 and 9 of this laminated thin film capacitor. The dielectric characteristics were 190 kHz and a dielectric loss of 0.06 when measured by an LCR meter at 1 kHz and 1 V at room temperature. The insulation resistance was 10 ⁹ Ω · cm or more, and the DC breakdown voltage was 0.7 kV / cm. A sample in which a platinum metal film was formed on an alumina substrate and a single thin film of SrTiO _{3 was formed on} the film was analyzed by X-ray diffraction and found to have a perovskite crystal structure.

In the above embodiment, the raw materials of Sr and Ti are used.
As strontium dipivaloyl methane, isopropo
Although xyltitanium was used, this raw material was used in the manufacturing method of this embodiment.
The perovskite type crystal structure is not limited to
SrTiO₃It is possible to obtain a thin film of
It was confirmed that In addition, N as a reaction gas ₂
O or H₂Even when O is used, when oxygen is used
It was confirmed that equivalent dielectric properties were obtained.

Similar results were obtained when barium, lead, bismuth, calcium and magnesium were added as additives. (Embodiment 2) FIG. 3 is a schematic view of the cross-sectional structure of a multilayer thin film capacitor according to Embodiment 2 of the present invention.

In FIG. 3, 31 is an underlying substrate made of alumina, 32, 34 and 36 are metal electrode thin film layers made of metallic platinum, and 33, 35 and 37 are Pb (Mg).
_1/3, Nb _2/3) O ₃ consisting -PbTiO ₃ dielectric thin film layers, 38 and 39 are external electrodes made of silver.

The manufacturing method of this multilayer thin film capacitor is as follows. The metal electrode thin film layer 32 is patterned on the base substrate 31 by a vacuum deposition method as shown in FIG. Plasma CVD of a dielectric thin film layer 33 thereon
It is formed by the method. On top of that, the metal electrode thin film layer 34
Is formed by a vacuum evaporation method so as to be displaced from the metal electrode thin film layer 32 as shown in FIG. 3 (a). Further, a dielectric thin film layer 35 is formed thereon by the plasma CVD method. Further, a metal electrode thin film layer 36 is formed thereon by a vacuum deposition method as shown in FIG.
It is formed in the same pattern as. Further, a dielectric thin film layer 37 is formed thereon by the plasma CVD method. After repeating this operation to stack a predetermined number of layers, as shown in FIG. 3 (b), the metal electrode thin film layers 32, 34, and 36 are made to have a predetermined size so as to face alternating side walls. Disconnect. External electrodes 38 and 39 made of silver are applied to the cut surface and baked to establish electrical continuity between the internal metal electrode thin film layers 32, 34 and 36 and the external electrodes 38 and 39.

Of the above manufacturing methods, the dielectric thin film layer 3
The film forming methods of 3, 35, and 37 will be described below. Lead dipivaloyl methane [Pb (C ₁₁ H
₁₉ O ₂ ) ₂ ], isopropoxy titanium [Ti (C ₃ H ₇ O)
₄ ], magnesium acetylacetonate [Mg (C ₅ H
₇ O ₂ ) ₂ · H ₂ O], pentaethoxyniobium [Nb (OC
₂ H ₅ ) ₅ ].

As shown in FIG. 2, the base substrate 14 on which a metal electrode thin film layer of platinum metal is patterned in advance by the vacuum deposition method is attached to the substrate heater 13 as shown in FIG.
It was heated to and held at 00 ° C. Lead dipivaloyl methane was added to the vaporization container 17, and isopropoxy titanium was added to the vaporization container 18.
Magnesium acetylacetonate is added to the vaporization container 19,
Pentaethoxyniobium was put in the vaporization container 20 and heated and held at 145 ° C., 50 ° C., 195 ° C. and 60 ° C., respectively. The inside of the reaction chamber 10 was exhausted by the exhaust system 15, and the substrate heating motor 12 rotated the substrate heating heater at a speed of 120 rotations per minute. Valves 21, 2
2, 23, 24, 25, 26, 27, 28 are opened, and lead dipivaloyl methane, isopropoxy is supplied by a carrier gas (flow rate 35 SCCM, 15 SCCM, 10 SCCM, 8 SCCM for vaporizers 17, 18, 19, 20 respectively). Titanium, magnesium acetylacetonate, and pentaethoxyniobium vapor were introduced into the reaction chamber 10 together with oxygen as a reaction gas (flow rate 30 SCCM), and plasma (power 1.4
The reaction is performed under reduced pressure (0.03 Torr) for 50 minutes at W / cm ₂ ) to obtain a dielectric thin film layer of Pb (Mg _1/3 , Nb _2/3 ) O.
Of ₃ -PbTiO ₃ thin film was formed on a base substrate 14 having patterned metal electrode thin film layer. After cooling this, it was taken out, the metal electrode thin film layer was pattern-formed again on the dielectric thin film layer by the vacuum evaporation method, and the dielectric thin film layer was formed thereon by the same method as described above. Thereafter, this operation was repeated to stack 10 metal electrode thin film layers and 10 dielectric thin film layers. As shown in FIG. 3, this is cut into a predetermined size together with the substrate so that every other metal electrode thin film layer faces alternating side walls, and silver is applied to the cut surface and baked to form an external electrode. Formed.

Further, for the analysis of the dielectric thin film layer, a sample was prepared in which a platinum metal film was formed on an alumina substrate, and a thin film of SrTiO ₃ was formed thereon by the same method as above.

The thickness of the dielectric thin film layer of the obtained laminated thin film capacitor was 2.2 μm per layer, and the thickness of the metal electrode thin film layer was 0.06 μm per layer. The electrical characteristics were measured between the electrodes 8 and 9 of this laminated thin film capacitor. The dielectric characteristics were 190 kHz and a dielectric loss of 0.06 when measured by an LCR meter at 1 kHz and 1 V at room temperature. The insulation resistance was 10 ⁹ Ω · cm or more, and the DC breakdown voltage was 0.7 kV / cm. Also, a metal platinum film is formed on an alumina substrate, and Pb (Mg _1/3 , N
A sample in which only one thin film of b _2/3 ) O ₃ -PbTiO ₃ was formed was analyzed by X-ray diffraction and found to have a perovskite crystal structure. The film composition analyzed by an X-ray microanalyzer is Pb {(Mg _1/3 Nb _2/3 ) _0.7 T
i _0.3 } O ₃ .

In the above embodiment, Pb, Ti, M
Although lead dipivaloyl methane, isopropoxy titanium, magnesium acetylacetonate, and pentaethoxyniobium were used as the raw materials for g and Nb, the perovskite crystal structure is not limited to these raw materials in the manufacturing method of the present embodiment. It was confirmed that the Pb (Mg _1/3 , Nb _2/3 ) O ₃ -PbTiO ₃ thin film could be obtained, and that equivalent dielectric characteristics could be obtained. Further, it was confirmed that even when N ₂ O or H ₂ O was used as the reaction gas, the same dielectric characteristics as when oxygen was used were obtained.

As additives, barium, strontium,
Bismuth, calcium, nickel, zinc, cobalt,
Similar results were obtained when iron, tantalum and tungsten were added.

In Examples 1 and 2, when a metal other than platinum, such as palladium, palladium / silver alloy, nickel, copper, etc., was used for the metal electrode thin film layer by a vacuum deposition method, or a sputtering method was used as a film forming method. Even when used, it was possible to manufacture a multilayer thin film capacitor having equivalent characteristics. Similarly, even when a metal other than silver is used for forming the external electrodes, or when a vacuum deposition method, a sputtering method, or a plating method is used in addition to the coating and baking method, it is possible to manufacture a multilayer thin film capacitor having the same characteristics. It was possible.

Further, in Examples 1 and 2, the plasma CVD apparatus for forming the dielectric thin film layer and the vacuum vapor deposition apparatus and the sputtering apparatus for forming the metal electrode thin film layer were separate, but they were connected. It was possible to more easily manufacture the substrate by transporting the substrate without breaking the vacuum and continuously forming a film by using.

[0029]

As is apparent from the above description of the embodiments, the present invention uses the plasma CVD method to form a dielectric thin film layer, so that SrTiO _{3 having} good dielectric properties can be formed on the metal electrode thin film layer. Or Pb (Mg _1/3 , Nb _2/3 ) O ₃
Dense thin film of -PbTiO ₃ is obtained at a relatively low temperature. Further, by using the vacuum deposition method or the sputtering method for forming the metal electrode thin film layer, a dense and thin metal electrode thin film layer can be obtained. Therefore, since it can be made thinner than the method of stacking and firing slurry-like ones in the conventional monolithic ceramic capacitor, the number of laminated layers is increased even if the chip thickness is the same, the electrostatic capacity is increased, and it is possible to cope with downsizing and large capacity .

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a multilayer thin film capacitor according to an embodiment of the present invention.

FIG. 2 is a plasma MOCVD used for forming a dielectric thin film layer of a multilayer thin film capacitor according to an embodiment of the present invention.
Device schematic

FIG. 3 is a schematic cross-sectional view of a multilayer thin film capacitor according to another embodiment of the present invention.

[Explanation of symbols]

 1 Base substrate 2, 4, 6 Metal electrode thin film layer 3, 5, 7 SrTiO3 dielectric thin film layer 8, 9 External electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01G 4/30 311 Z 9174-5E (72) Inventor Ryoichi Takayama 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Denki Sangyo Co., Ltd.

Claims (5)

[Claims] 1. A metal electrode thin film layer patterned on a substrate by a vacuum deposition method or a sputtering method, and a dielectric thin film layer formed by a plasma CVD method using a mixed gas of a vapor of a metal compound and a reaction gas. The metal thin film layer and the dielectric thin film layer are laminated by alternately repeating the production,
The above-mentioned patterned metal electrode thin film layer is cut so that every other layer faces alternating side walls, and external electrodes are formed on the cut surface by a vacuum deposition method, a sputtering method, a plating method, or a coating baking method. And a method for manufacturing a multilayer thin film capacitor. 2. The method for producing a multilayer thin film capacitor according to claim 1, wherein the material of the dielectric thin film layer is a perovskite type oxide containing strontium titanate as a main component. 3. The material of the dielectric thin film layer is Pb (Mg _1/3 ,
The method for producing a multilayer thin film capacitor according to claim 1, wherein the compound is a complex perovskite type compound containing Nb _2/3 ) O ₃ and lead titanate as main components. 4. The method for producing a multilayer thin film capacitor according to claim 1, wherein a β-diketone metal complex or a metal alkoxide is used as the metal compound. 5. The method for producing a multilayer thin film capacitor according to claim 1, wherein oxygen, N ₂ O or H ₂ O is used as a reaction gas.