Method for manufacturing multilayer ceramic capacitors and method for manufacturing high-dielectric ceramic films used therein

Abstract

To provide a method for manufacturing a multilayer ceramic capacitor in which a high-dielectric ceramic film and an electrode film can be formed by ALD, and a method for manufacturing a high-dielectric ceramic film used therein. [Solution] A method for manufacturing a multilayer ceramic capacitor by alternately stacking a high-dielectric ceramic film and an electrode film in a reaction vessel using ALD, comprising: a first ALD cycle for forming the high-dielectric ceramic film; and a second ALD cycle for forming the electrode film. The first ALD cycle comprises a first metal oxide film formation step and a second metal oxide film formation step, which are performed alternately in forward or reverse order. The second ALD cycle is performed M (M is an integer) times before and / or after the first ALD cycle has been performed N (N is an integer) times. The first metal compound, second metal compound, and third metal compound, which are precursors to the electrode film which is a first metal oxide film, a second metal oxide film, and a third metal, are produced by etching each target with plasma excited by each plasma generation means using each source gas.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a multi-layer ceramic capacitor (MLCC) and a method for manufacturing a high-dielectric ceramic film used therein. [Background technology]

[0002] Multilayer ceramic capacitors are widely used as electronic components in small mobile devices such as smartphones. Multilayer ceramic capacitors are formed by alternately stacking ceramic high-dielectric ceramic films, such as barium titanate or strontium titanate films, which are different from conventional Si3N4 films or SiO2 layers, with electrode films, such as nickel films.

[0003] Multilayer ceramic capacitors are generally manufactured by applying a metal paste, which serves as the internal electrode, to a roll of dielectric sheets, stacking these sheets, pressing them, sintering them, and then cutting them to chip size.

[0004] The applicant has proposed a technology for manufacturing barium titanate films by ALD (Atomic Layer Deposition) (Patent Document 1) and a technology for manufacturing metal films by ALD (Patent Document 2). A technology for manufacturing high-dielectric ceramic films by ALD is also disclosed in Patent Document 3. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6980324 [Patent Document 2] Patent No. 7112768 [Patent Document 3] US2003 / 113480A [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Patent Document 1 describes how to form a titanium oxide film by ALD (Advanced Laser Development) by reacting TDMAT (TiH[N(CH3)4]) with OH radicals, and then forming a barium oxide film by reacting the sublimated and vaporized barium complex with OH radicals. On the other hand, Patent Document 3 describes how to form a strontium oxide film by reacting Sr(TMHD)2 with NH3, and then forming a titanium oxide film by reacting Ti(OiPr)4 with NH3, thereby forming a strontium titanate film. According to Patent Document 3, it is possible to manufacture high dielectric capacitors without generating unwanted byproducts caused by H2O vapor, which was conventionally used as a reaction gas.

[0007] However, Patent Document 1 requires heating the solid barium complex under vacuum to sublimate it and vaporize it. Furthermore, Patent Documents 1 and 3 require storing gases such as TDMAT(TiH[N(CH3)4]), Sr(TMHD)2, and Ti(OiPr)4 as raw material gas sources. For example, raw materials such as TDMAT can react violently with moisture in the atmosphere and pose an explosion risk.

[0008] The present invention aims to provide a method for manufacturing a multilayer ceramic capacitor and a high-dielectric ceramic film used therein, which allows for the formation of a ceramic high-dielectric film and an electrode film by ALD without using barium complexes that require heating and sublimation under vacuum, or raw material gases that pose a risk of explosion. [Means for solving the problem]

[0009] (1) One aspect of the present invention is: A method for manufacturing a multilayer ceramic capacitor by alternately stacking a high-dielectric ceramic film and an electrode film in a reaction vessel using ALD, The process includes a first ALD cycle for forming the high-dielectric ceramic film and a second ALD cycle for forming the electrode film. The first ALD cycle comprises a first metal oxide film formation step and a second metal oxide film formation step, which are performed alternately in forward or reverse order, and the second ALD cycle is performed M (M is an integer) times before and / or after the first ALD cycle has been performed N (N is an integer) times. The first metal oxide film formation step in the first ALD cycle is: A first step involves filling the reaction vessel with a first metal compound gas, A second step involves exhausting the first metal compound gas from the reaction vessel, A third step involves filling the reaction vessel with OH radicals, A fourth step involves exhausting the OH radicals from the reaction vessel, Includes, The first step includes a step of generating the first metal compound gas by etching a first target containing a first metal in the first metal compound gas with a first plasma obtained by exciting a first raw material gas with a first plasma generating means outside the reaction vessel, The second metal oxide film formation step in the first ALD cycle is: A fifth step involves filling the reaction vessel with a second metal compound gas, A sixth step involves exhausting the second metal compound gas from the reaction vessel, A seventh step involves filling the reaction vessel with OH radicals, An eighth step of exhausting the OH radicals from the reaction vessel, Includes, The fifth step includes a step of generating a second metal compound gas by etching a second target containing a second metal in the second metal compound gas with a second plasma obtained by exciting a second raw material gas with a second plasma generating means outside the reaction vessel, The second ALD cycle is, A ninth step involves filling the reaction vessel with a third metal compound gas, A tenth step involves exhausting the third metal compound gas from the reaction vessel, The 11th step involves filling the reaction vessel with radicals of the reducing gas component, a twelfth step of evacuating radicals of the reducing gas component from the reaction vessel, including, the ninth step includes a step of exciting a third source gas outside the reaction vessel by a third plasma generation unit to obtain a third plasma, and etching a third target containing a third metal in the third metal compound gas with the third plasma to generate the metal compound gas, the eleventh step relates to a method for manufacturing a multilayer ceramic capacitor, comprising a step of exciting a reducing gas outside the reaction vessel by a fourth plasma generation unit to generate radicals of the reducing gas component.

[0010] According to one aspect of the present invention, a first target containing a first metal can be etched with a first plasma obtained by exciting a first source gas by a first plasma generation unit, so that a first metal compound gas that is a precursor can be generated. In addition, without sublimating the barium complex, a second target containing a second metal is etched with a second plasma obtained by exciting a second source gas by a second plasma generation unit, so that a second metal compound gas that is a precursor can be generated. Further, a third target containing a third metal is etched with a third plasma obtained by exciting a third source gas by a third plasma generation unit, so that a third metal compound gas that is a precursor can be generated. In this way, three types of film formation can be realized by ALD using the components obtained by etching the respective targets. The laminate of the first metal oxide film and the second metal oxide film interdiffuses under heating, for example, to form a thermodynamically stable high-dielectric ceramic film. Therefore, a capacitor structure in which high-dielectric ceramic films and electrode films are alternately laminated is formed.

[0011] (2) Another aspect of the present invention is a method for producing a high-dielectric ceramic film by alternately laminating first metal oxide films and second metal oxide films in normal order or reverse order by ALD in a reaction vessel, the method comprising: the first metal oxide film forming step includes: a first step of filling the reaction vessel with a first metal compound gas, A second step involves exhausting the first metal compound gas from the reaction vessel, A third step involves filling the reaction vessel with OH radicals, A fourth step involves exhausting the OH radicals from the reaction vessel, Includes, The first step includes a step of generating the first metal compound gas by etching a first target containing the first metal with a first plasma obtained by exciting the first raw material gas with a first plasma generating means outside the reaction vessel, The second metal oxide film formation step is as follows: A fifth step involves filling the reaction vessel with a second metal compound gas, A sixth step involves exhausting the second metal compound gas from the reaction vessel, A seventh step involves filling the reaction vessel with OH radicals, An eighth step of exhausting the OH radicals from the reaction vessel, Includes, The fifth step relates to a method for producing a high-dielectric ceramic film, which includes a step of generating a second metal compound gas by etching a second target containing a second metal in the second metal compound gas with a second plasma obtained by exciting a second raw material gas with a second plasma generating means outside the reaction vessel.

[0012] Another aspect of the present invention allows for the formation of a high-dielectric ceramic film in the same manner as the first to eighth steps in one aspect of the present invention, and can be used for applications other than the manufacturing method of multilayer ceramic capacitors.

[0013] (3) In the third and / or seventh steps of one and / or other aspects of the present invention, OH radicals can be generated by passing an inert gas containing water vapor through a foamed metal heated to 150-300°C. Hydrogen is readily adsorbed onto the heated foamed metal, and H is separated from H2O in the water vapor to generate OH radicals. At room temperature, OH radicals are readily adsorbed on the metal portion of the foamed metal, and H radicals are readily adsorbed on the native oxide film portion. However, heating the foamed metal to the above range disrupts this balance, making it more difficult for OH radicals to be adsorbed. Furthermore, the inert gas physically prevents OH radicals from recombining with H radicals. Therefore, when an inert gas containing water vapor is passed through a heated foamed metal, the foamed metal can adsorb H radicals while allowing OH radicals to pass through.

[0014] (4) In one aspect of the present invention, the first raw material gas, the second raw material gas, the third raw material gas, and the reducing gas may be halogen gases. In this case, the first metal compound gas becomes a halogen compound containing the first metal and reacts with OH radicals to form a first metal oxide film. The second metal compound gas becomes a halogen compound containing the second metal and reacts with OH radicals to form a second metal oxide film. The third metal compound gas becomes a halogen compound containing the third metal and reacts with halogen radicals of the reducing gas component to reduce it and form a third metal film. In other aspects of the present invention, the first raw material gas and the second raw material gas may be halogen gases in the same manner as in one aspect of the present invention. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an ALD apparatus in which one embodiment of the method of the present invention is implemented. [Figure 2] This is a timing chart showing the first ALD cycle performed by the ALD device shown in Figure 1. [Figure 3] This is a timing chart showing the second ALD cycle performed by the ALD device shown in Figure 1. [Figure 4]This diagram illustrates the foamed metal placed inside the conduit in place of the induction coil in Figure 1 to generate OH radicals. [Figure 5] Figure 4 shows the mechanism of OH radical generation by foamed metal. [Modes for carrying out the invention]

[0016] The following disclosure provides numerous different embodiments and examples for carrying out different features of the presented subject matter. Of course, these are merely examples and are not intended to be limiting. Furthermore, the disclosure may repeat reference numbers and / or letters in various examples. Such repetition is for the sake of brevity and clarity and does not require itself to be related to the various embodiments and / or configurations described. Furthermore, where it is stated that the first element is “connected” or “linked” to the second element, such a statement includes embodiments in which the first and second elements are integral, or in which the first and second elements are directly connected or linked to each other, as well as embodiments in which the first and second elements are indirectly connected or linked to each other by having one or more other elements interposed between them. Also, where it is stated that the first element “moves” relative to the second element, such a statement includes embodiments of relative movement in which at least one of the first and second elements moves relative to the other.

[0017] 1.ALD equipment Figure 1 shows an example of an ALD apparatus 10. The ALD apparatus 10 includes a reaction vessel 20, first to third raw material gas sources 31 to 33, a reducing gas source 34, and an inert gas source 35. The reaction vessel 20 is a vessel for forming a film on a workpiece 1. The reaction vessel 20 has a mounting section 21 on which the workpiece 1, such as a substrate, is placed. The mounting section 21 has a heating section 22. The heating section 22 heats the workpiece 1 to a predetermined temperature. Gas piping 23 is connected to the reaction vessel 20, and various gases are introduced into the reaction vessel 20. An exhaust pipe 24 is connected to the reaction vessel 20, and the inside of the reaction vessel 20 can be exhausted by an exhaust pump 25. In this embodiment, the gas piping 23 and the exhaust pipe 24 form a concentric double pipe, and intake and exhaust are possible from one location in the reaction vessel 20. Connecting the gas piping 23 and exhaust pipe 24 to the reaction vessel 20 via their respective connection ports would be costly. By using a coaxial structure as in this embodiment, the gas temporarily remaining in the gas piping 23 can be instantly exhausted through the coaxial exhaust pipe 24 without passing through the inside of the reaction vessel 20. Note that, unlike in Figure 1, the exhaust pipe 24 may be installed inside the gas piping 23.

[0018] The inert gas source 35 can supply inert gas as a carrier gas for the raw material gas and reaction gas, or as a purge gas to purge the reaction vessel 20. Alternatively, instead of introducing purge gas, the reaction vessel 20 may be evacuated using the vacuum pump 25. The gases from these various gas sources 31 to 35 are supplied to the reaction vessel 20 with their supply timing and flow rate controlled via a flow control unit (MFC) and valves.

[0019] The first to third raw material gas sources 31 to 33 can be supplied with, for example, halogen gases as the first to third raw material gases. In this case, one raw material gas source may be shared by the first to third raw material gases. In this embodiment, chlorine (Cl2 gas), which is a halogen gas, is used as the first to third raw material gas, but fluorine (F), bromine (Br), iodine (I), or astatine (At) may also be used.

[0020] The first raw material gas source 31 is connected to a non-metallic conduit 41. A first plasma generation means, such as a first induction coil 42, is provided around the conduit 41. A high-frequency power supply (not shown) is connected to the first induction coil 42. For example, the electromagnetic energy applied by the first induction coil 42 is 20 W, and the frequency is 13.56 MHz. The first induction coil 42 generates an inductively coupled halogen gas plasma (e.g., Cl2 plasma) P1 inside the conduit 41.

[0021] Similarly, the second raw material gas source 32 is connected to a pipeline 51 around which a second plasma generation means, such as a second induction coil 52, is provided. The third raw material gas source 33 is connected to a pipeline 61 around which a third plasma generation means, such as a third induction coil 62, is provided. The reducing gas source 34 is connected to a pipeline 71 around which a fourth plasma generation means, such as a fourth induction coil 72, is provided.

[0022] The first to third targets 43, 53, and 63 are positioned within the pipelines 41, 51, and 61, respectively. The first to third targets 43, 53, and 63 can be rod-shaped targets positioned along the longitudinal direction of the pipelines 41, 51, and 61, inside the non-metallic portions of the pipelines. This reduces the obstruction of gas flow by the first to third targets 43, 53, and 63 within the pipelines 41, 51, and 61.

[0023] The first target 43 contains a first metal, such as titanium (Ti). The second target 53 contains a second metal, such as barium (Ba). The third target 63 contains a third metal, such as nickel (Ni), which forms the electrode film. Halogen gas introduced into conduits 41, 51, and 61 is excited by the first to third induction coils 42, 52, and 62, generating first to third plasmas P1, P2, and P3 near the first to third targets 43, 53, and 63. Ions in the first to third plasmas P1, P2, and P3 etch the first to third targets 43, 53, and 63. Ti ions, which are the first metal, generated when the first target 43 is etched, react with halogens, such as Cl radicals, in the first plasma P1 to produce a halogen compound of titanium, such as CuCl. Ba ions, which are the second metal, generated when the second target 53 is etched, react with halogens, such as Cl radicals, in the second plasma P2 to produce a halogen compound of barium, such as BaCl. The third target 63 is etched, and the resulting Ni ions, which are a third metal, react with halogens in the third plasma P3, such as Cl radicals, to produce nickel halogen compounds, such as NiCl.

[0024] The inert gas source 35 is capable of supplying water to a bubbling tank 70 containing water. From the bubbling tank 70, water bubbling with an inert gas, such as argon (Ar), is discharged as water vapor. The bubbling tank 70 is connected to a conduit 71 around which a fourth plasma generation means, such as a fourth induction coil 72, is provided. In the conduit 71, humidified argon gas is excited by the fourth induction coil 72 to generate a fourth plasma P4, which activates the water vapor. This results in Ar + H2O → Ar * +OH * +H * This results in the OH radical (OH * ) can be generated.

[0025] The reducing gas source 34 supplies a reducing gas to reduce the third metal compound NiCl generated in the pipeline 61 and deposit the third metal Ni. In this embodiment, a halogen gas such as chlorine halogen is used to reduce NiCl and deposit Ni. In this case, a single gas source containing chlorine may be shared as the first to third raw material gas sources 31 to 33 and the reducing gas source 34.

[0026] The reducing gas source 34 is connected to a conduit 81 around which a fifth plasma generation means, such as a fifth induction coil 82, is provided. In the conduit 81, chlorine gas is excited by the fifth induction coil 82 to generate a fifth plasma P5, which activates the chlorine gas. This generates Cl radicals (Cl * ) can be generated. Note that since pipelines 71 and 81 have the same structure, they can be used as a single pipeline for both the bubbling tank 70 and the reducing gas source 34.

[0027] 2.ALD process The object 1 is placed in the reaction vessel 20, and the ALD cycle is carried out. Generally, an ALD cycle consists of a minimum of four steps: introduction of raw material gas → exhaust (purge or vacuum) → introduction of reaction gas → exhaust. In this embodiment, the film formed on the object 1 in the ALD apparatus 10 is a laminate of a high-dielectric ceramic film, such as a barium titanate film, and an electrode film, such as a nickel film.

[0028] 2.1 First ALD cycle for depositing a high-dielectric ceramic film (barium titanate film) The barium titanate film is formed by alternately forming titanium oxide films and barium oxide films in normal order or reverse order. The stacked titanium oxide film and barium oxide film are heated by the heating unit 22 to, for example, 200 to 300°C, preferably 230 to 270°C, so that they interdiffuse to form a barium titanate film. As shown in Figure 2, the first ALD cycle in the present embodiment is defined as one cycle consisting of: introducing the first precursor gas → exhausting → introducing the second precursor gas → exhausting → introducing the third precursor gas → exhausting → introducing the fourth precursor gas → exhausting. The thickness of the film deposited on the target object 1 is proportional to the number N (N is an integer) of ALD cycles. Therefore, it is determined whether the number of cycles counted up each time an ALD cycle ends has reached a set value, and as shown in Figure 2, the ALD cycle is repeatedly performed the required number of times N.

[0029] 2.1.1. First Metal Oxide Film (Titanium Oxide Film) As two types of precursors, TiCl which is a titanium halogen compound generated in line 41, and hydroxyl group OH radicals (OH * ) are used. In performing the ALD cycle, first, the inside of the reaction vessel 20 is evacuated by the exhaust pump 25, for example, to 10 -4 Pa. Next, as the first step of the first ALD cycle, TiCl (first precursor gas), which is a titanium halogen compound generated in line 41, is filled into the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the first step of the ALD cycle, TiCl penetrates the surface of the target object 1. After a predetermined time has elapsed, in the second step of the first ALD cycle, a purge gas is introduced into the reaction vessel 20, and TiCl in the reaction vessel 20 is exhausted and replaced with the purge gas.

[0030] Next, in the third step of the first ALD cycle, hydroxyl group OH radicals (OH, which is the second precursor gas) * ) are filled into the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the third step of the ALD cycle, OH radicals (OH * ) penetrate. As a result, on the surface of the target object 1, TiCl reacts with OH radicals (OH *) reacts with TiCl + OH * →TiO + HCl↑, and a titanium oxide film TiO is formed on the object 1. After a predetermined time has elapsed, in the fourth step of the first ALD cycle, the inside of the reaction vessel 20 is evacuated, for example 10 -4 Set to Pa.

[0031] 2.1.2. Second metal oxide film (barium oxide film) Two types of precursors are used: BaCl, a barium halogen compound produced in pipeline 51, and hydroxyl group OH radicals (OH*), produced in pipeline 71. In the fifth step of the first ALD cycle, BaCl (third precursor gas), a barium halogen compound produced in pipeline 51, fills the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the fifth step of the first ALD cycle, BaCl penetrates the surface of the object 1. After a predetermined time has elapsed, in the sixth step of the first ALD cycle, a purge gas is introduced into the reaction vessel 20, and the vaporized barium complex in the reaction vessel 20 is exhausted and replaced by the purge gas.

[0032] Next, in the seventh step of the first ALD cycle, the fourth precursor gas, a hydroxyl group OH radical (OH), is generated in pipeline 71. * ) fills the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the seventh step of the first ALD cycle, OH radicals (OH) are formed on the surface of the object 1. * ) penetrates. As a result, on the surface of object 1, BaCl is converted into OH radicals (OH * ) reacts with BaCl + OH * →BaO + HCl↑, and a barium oxide film BaO is formed. After a predetermined time has elapsed, in the 8th step of the first ALD cycle, the inside of the reaction vessel 20 is evacuated, for example, 10 -4 The pressure is set to Pa, or the OH radicals (OH*) in the reaction vessel 20 are replaced with purge gas.

[0033] The titanium oxide (TIO) film and the barium oxide (BaO) film are arranged in a regular manner to form a barium titanate film (BaTiO3). The first ALD cycle is repeated a required number of times N (where N is an integer), and a barium titanate film of a predetermined thickness is formed at time T1 in Figure 2. In addition, even if a barium oxide film is formed by steps 5 to 8 of the first ALD cycle, and then a titanium oxide film is formed by steps 1 to 4 of the first ALD cycle, a barium titanate film will be formed in the same manner.

[0034] 2.2. Second ALD cycle for depositing the electrode film, which is the third metal. At time T1 in Figure 3, the second ALD cycle begins. As shown in Figure 3, the second ALD cycle consists of a minimum of four steps: introduction of the fifth precursor gas → exhaust (including purging) → introduction of the sixth precursor gas → exhaust (including purging). The thickness of the electrode film deposited on the workpiece 1 is proportional to the number of second ALD cycles M (where M is an integer). Therefore, the ALD cycle is repeated as many times as necessary M.

[0035] At time T1, the Nth execution of the 8th step of the first ALD cycle results in, for example, 10 -4 The pressure is set to Pa. In the first step (also called the ninth step) of the second ALD cycle, NiCl, the fifth precursor gas produced in the pipeline 61, fills the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the first step of the second ALD cycle, CuCl penetrates the exposed surface of the workpiece 1. After a predetermined time has elapsed, in the second step (also called the tenth step) of the second ALD cycle, a purge gas is introduced into the reaction vessel 20, and the inside of the reaction vessel 20 is replaced with the purge gas.

[0036] Next, in the third step (also called the eleventh step) of the second ALD cycle, Cl radicals, which are the sixth precursor gas from the pipeline 81, fill the reaction vessel 20 at a predetermined pressure, for example, 1 to 10 Pa. In the third step of the ALD cycle, the Cl radicals penetrate the exposed surface of the workpiece 1. As a result, CuCl reacts with the Cl radicals on the exposed surface of the workpiece 1, and copper Cu is deposited on the exposed surface of the workpiece 1 by the subsequent reduction reaction. NiCl + Cl * →Ni+Cl2↑

[0037] After a predetermined time has elapsed, in the fourth step (also called the twelfth step) of the second ALD cycle, the inside of the reaction vessel 20 is evacuated, for example, 10 -4 The temperature is set to Pa, or the OCl radicals in the reaction vessel 20 are replaced with a purge gas. The Ni film is formed by repeating the second ALD cycle M (where M is an integer) times. When the Mth second ALD cycle is completed, the workpiece 1 is removed from the reaction vessel 20, as shown in Figure 3.

[0038] The electrode film Ni, which is deposited on the entire surface of the barium titanate film, is patterned outside the reaction vessel 20 by etching away areas that are not masked, for example. Then, the workpiece 1 is brought back into the reaction vessel 20, and N first ALD cycles and M second ALD cycles are performed, and thereafter the film deposition process is repeated for the number of layers of barium titanate film / electrode film. Alternatively, the patterning of the electrode film Ni may be performed by removing the workpiece 1 from the reaction vessel 20 before the deposition of the electrode film Ni, placing a mask body with holes in the area where Ni will be formed on the workpiece 1, and then depositing the Ni on the workpiece 1 via the mask body inside the reaction vessel 20.

[0039] 3. Variant Although one embodiment of the present invention has been described, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, the high-dielectric ceramic film is not limited to barium titanate, but may also be strontium titanate, calcium titanate, magnesium titanate, lanthanum titanate, etc. In this case, the first metal is titanium Ti, and the second metal is strontium Sr, calcium Ca, magnesium Mg, or lanthanum La. The third metal that forms the metal film can be nickel Ni, as well as copper Cu, silver Au, platinum Pt, etc. However, the first to third metals are not limited to the above examples, and any metal that can be produced by etching a metal target is acceptable.

[0040] Next, a method for generating OH radicals without using the fourth plasma generation means 72 shown in Figure 1 will be described with reference to Figure 4. In Figure 4, the foamed metal 90 is arranged in the conduit 81 shown in Figure 1 so as to close the flow path, and the fourth plasma generation means 72 shown in Figure 1 is not provided. The foamed metal 90 is, for example, Al foam.

[0041] Using the structure shown in Figure 4, in the third and / or seventh steps of the first ALD cycle, an inert gas containing water vapor from the bubbling tank 70 is passed through the foamed metal 90, which is heated to 150-300°C, preferably 180-220°C, to generate OH radicals. As shown in Figure 5, hydrogen is readily adsorbed onto the heated foamed metal 90, and H is separated from H2O in the water vapor to generate OH radicals. For example, in foamed metal 90 such as Al foam, OH radicals are readily adsorbed on the metal portion and H radicals on the native oxide film portion at room temperature. However, heating the foamed metal 90 to the above range disrupts this balance, making it more difficult for OH radicals to be adsorbed. Furthermore, the inert gas physically prevents OH radicals from recombining with H radicals. Therefore, when an inert gas containing water vapor is passed through the heated foamed metal 90, the foamed metal 90 can adsorb H radicals while allowing OH radicals to pass through. In addition to Al foam, foamed metal 90 can also include Al alloys, Ni, Ni alloys, Cu, Cu alloys, Au, etc. [Explanation of Symbols]

[0042] 1…Workpiece, 10…ALD apparatus, 20…Reaction vessel, 21…Placement section, 22…Heating section, 31…First raw material gas source, 32…Second raw material gas source, 33…Third raw material gas source, 34…Reducing gas source, 35…Inert gas source, 41, 51, 61, 71, 81…Pipelines, 42, 52, 62, 72, 82…First to fifth plasma generation means, 43, 53, 63…First to third targets, 70…Bubbling tank, 90…Foamed metal, P1 to P5…First to fifth plasma

Claims

1. A method for manufacturing a multilayer ceramic capacitor by alternately stacking a high-dielectric ceramic film and an electrode film in a reaction vessel using ALD, The process includes a first ALD cycle for forming the high-dielectric ceramic film and a second ALD cycle for forming the electrode film. The first ALD cycle includes a first metal oxide film formation step and a second metal oxide film formation step, which are performed alternately in forward or reverse order, and the second ALD cycle is performed M times (M is an integer) before and / or after the first ALD cycle has been performed N times (N is an integer). The first metal oxide film formation step in the first ALD cycle is A first step involves filling the reaction vessel with a first metal compound gas, A second step involves exhausting the first metal compound gas from the reaction vessel, A third step involves filling the reaction vessel with OH radicals, A fourth step involves exhausting the OH radicals from the reaction vessel, Includes, The first step includes a step of generating a first metal compound gas by etching a first target containing a first metal with a first plasma obtained by exciting a first raw material gas with a first plasma generating means outside the reaction vessel, The second metal oxide film formation step in the first ALD cycle is A fifth step involves filling the reaction vessel with a second metal compound gas, A sixth step involves exhausting the second metal compound gas from the reaction vessel, A seventh step involves filling the reaction vessel with OH radicals, An eighth step involves evacuating the OH radicals from the reaction vessel, Includes, The fifth step includes a step of generating a second metal compound gas by etching a second target containing a second metal with a second plasma obtained by exciting a second raw material gas with a second plasma generating means outside the reaction vessel, The second ALD cycle is, A ninth step involves filling the reaction vessel with a third metal compound gas, A tenth step involves exhausting the third metal compound gas from the reaction vessel, A 11th step involves filling the reaction vessel with radicals of the reducing gas component, A 12th step involves exhausting the radicals of the reducing gas component from the reaction vessel, Includes, The ninth step includes a step of generating a third metal compound gas by etching a third target containing a third metal in the third metal compound gas with a third plasma obtained by exciting a third raw material gas with a third plasma generating means outside the reaction vessel, The 11th step is a step of generating radicals of the reducing gas components by exciting a reducing gas outside the reaction vessel using a fourth plasma generation means, the method for manufacturing a multilayer ceramic capacitor.

2. In claim 1, A method for manufacturing a multilayer ceramic capacitor, wherein the third or seventh step includes passing an inert gas containing water vapor through a foamed metal heated to 150 to 300°C to generate the OH radicals.

3. In claim 1 or 2, A method for manufacturing a multilayer ceramic capacitor, wherein the first raw material gas, the second raw material gas, the third raw material gas, and the reducing gas are halogen gases.

4. A method for producing a high-dielectric ceramic film by alternately stacking a first metal oxide film and a second metal oxide film in forward or reverse order using ALD in a reaction vessel, The first metal oxide film formation step is as follows: A first step involves filling the reaction vessel with a first metal compound gas, A second step involves exhausting the first metal compound gas from the reaction vessel, A third step involves filling the reaction vessel with OH radicals, A fourth step involves exhausting the OH radicals from the reaction vessel, Includes, The first step includes a step of generating a first metal compound gas by etching a first target containing a first metal with a first plasma obtained by exciting a first raw material gas with a first plasma generating means outside the reaction vessel, The process for forming the second metal oxide film is as follows: A fifth step involves filling the reaction vessel with a second metal compound gas, A sixth step involves exhausting the second metal compound gas from the reaction vessel, A seventh step involves filling the reaction vessel with OH radicals, An eighth step involves evacuating the OH radicals from the reaction vessel, Includes, The fifth step is a step of generating a second metal compound gas by etching a second target containing a second metal with a second plasma obtained by exciting a second raw material gas with a second plasma generating means outside the reaction vessel.

5. In claim 4, A method for producing a high-dielectric ceramic film, wherein the third or seventh step includes passing an inert gas containing water vapor through a foamed metal heated to 150 to 300°C to generate the OH radicals.

6. In claim 4 or 5, A method for manufacturing a high-dielectric ceramic film, wherein the first raw material gas and the second raw material gas are halogen gases.

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