GB2387392A

GB2387392A - Metal film for use in a laminated ceramic electronic component and manufacturing method thereof

Info

Publication number: GB2387392A
Application number: GB0316072A
Authority: GB
Inventors: Teppe Akiyoshi
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2001-06-08
Filing date: 2002-06-07
Publication date: 2003-10-15
Anticipated expiration: 2022-06-07
Also published as: GB2387392B; GB0316072D0

Abstract

A manufacturing method for a metal film is provided. The metal film is intended to form an internal conductor film of a laminated ceramic electronic component and has excellent mold-release properties from a supporting member, on which it is formed, and, furthermore, defects, such as peeling from the supporting meter and crack, are unlikely to occur. A first metal film is formed made of an electroless plating catalyst material on a supporting member by a vacuum thin-film forming apparatus. A second metal film made of an electroless plating catalyst is then formed by immersion plating. A third metal film is subsequently formed by electroless plating using the second metal film as a catalyst. The first metal film forming step is completed before the first metal film grows to a uniform continuous film.

Description

- 1 METAL FILM AND MANUFACTURING METHOD THEREFOR, AND

LAMINATED CERAMIC ELECTRONIC COMPONENT AND MANUFACTURING

METHOD THEREFOR

5 The present invention relates to a metal film and a manufacturing method therefor, and to a laminated ceramic electronic component and a manufacturing method therefor.

In particular, the present invention relates to a manufacturing method for a metal film which is formed 10 basically by electroless plating and which is suitable for the use as an internal conductor film provided in a laminated ceramic electronic component.

A laminated ceramic electronic component, for example, a multilayer ceramic capacitor, is provided with 15 an internal conductor film such as an internal electrode.

The internal conductor film can be formed by various methods. Typical examples include: forming the internal conductor film by the use of a thick-film forming technique, such as printing and baking of a conductive 20 paste; or forming the internal conductor film by the use of a thinfilm forming technique, such as a vacuum thin film forming method, for example, vacuum evaporation or sputtering, or a wet plating method, for example, an electroless plating method or electroplating method.

25 The method of forming the internal conductor film using the latter thin-film forming technique, that is, a manufacturing method for a metal film, is particularly relevant to the present invention.

A manufacturing method for metal film using a thin 30 film forming technique is known, for example, from Japanese Unexamined Patent Application Publication No. 6 302469, which discloses a method in which a first metal film having a th |

organic film (supporting member) by a vacuum thin-film forming method through a mask. A second metal film is formed on the first metal film by electroless plating and, therefore, a metal film having a predetermined thickness 5 is manufactured.

The metal film thus formed on the organic film must be in a condition that the organic film can be peeled from the metal film by some step of, for example, transferal from the organic film to a ceramic green sheet, in order 10 to be used as the internal conductor film of the laminated ceramic electronic component.

However, the technique described in Japanese Unexamined Patent Application Publication No. 6-302469, suffers from problems as described below.

IS In the case where the metal film is formed under the condition that no defect occurs, there are problems in that the peeling between the metal film and the supporting member and, furthermore, the transfer of the metal film to the ceramic green sheet are impossible. The time for this 20 transfer is increased, part of the metal film is not transferred and remains on the supporting member and, therefore, breakage or cracking occurs in the metal film, and the like.

To tackle these problems, a method in which adhesion 25 between the supporting member and the metal film is reduced, is effective. Consequently, measures have been taken, in which, for example, some contrivances have been made in the combination of the material for the supporting member and the material for the first metal film. Some 30 contrivances have also been made in the film making condition regarding the thin-film forming method for forming the first metal film.

- 3 - However, when adhesion between the supporting member and the metal film is reduced as described above, peeling is likely to occur in the metal film due to an internal stress which occurs in the metal film during formation of 5 the first metal film by the vacuum thin-film forming apparatus, or during electroless plating or water washing after the electroless plating for formation of the second metal film. Consequently, a problem is encountered in that defects, such as partial peeling and cracking, are 10 likely to occur in the metal film.

To overcome this problem, a method is conceived, in which to avoid occurrence of the defect due to peeling during the formation of the metal film, adhesion to hold the metal film on the supporting member is ensured while 15 the adhesion is reduced as low as possible to improve the moldrelease property within the range of the adhesion.

In order to realize this method, a method of precisely controlling the adhesion between the supporting member and the metal film has been suggested. For example, Japanese 20 Unexamined Patent Application Publication No. 7-66072 discloses specifying the pin hole open area ratio of the first metal film to be between 1% to 70%. The metal film can be reliably held on a supporting member, which is a supporting member, while the the force which is needed to 25 peel the metal film from the supporting member is controlled. However, inhibition of peeling, which occurs during formation of the metal film, by such a conventional technique degrade a mold-release property between the 30 supporting member and the metal film. Consequently, the problem with the aforementioned Japanese Unexamined Patent Application P

- 4 - between the supporting member and the metal film and, furthermore, transfer to the ceramic green sheet have been impossible, the time for the transfer has been increased, a part of the metal film has not been transferred and has 5 remained on the supporting member and, therefore, breakage or crack has occurred in the metal film, and the like have not yet been adequately overcome.

Japanese Unexamined Patent Application Publication No. 7-66072, describes a technique in which the first 10 metal film is evaporated until the thickness is in the order of 0.1 um. When evaporation is performed until such a thickness is achieved, the first metal film grows to a uniform continuous film in the thin film growth process described below. As is described in the aforementioned 15 publication, even when a pin hole is formed, the size thereof is 1 um in the example, and in general, 0.5 Am or more. As a result, although a uniform continuous films may be achieved over some regions of 1 x 1Os nm2, only one or 20 two boundary lines of pinholes may be observed in some regions of 1 x 105 nm2, and other regions of 1 x 105 nm2 may become a part of the pin hole, and may become in a condition that no metal film exists within the range thereof. 25 Accordingly, in the conventional technique, the condition shown in Fig. 5, in which the metal film is in the island structure or in the network structure over any region of 1 x 105, iS not achieved. That is, the control of peeling based on the technique described in Japanese 30 Unexamined Patent Application Publication No. 7-66072 is so-called macro control of peeling. Therefore, a problem regarding the combination of the metal used for the first

- 5 - metal film and the supporting member, and the film making condition in the thin-film forming method, when the condition that strong moldrelease property can be exhibited is adopted. As cracking may occur in the metal 5 film and the metal film may peel off due to internal stresses which occur in the portion other than the pin hole in the metal film during film making, or during plating or water washing after the plating, it is difficult to form the metal film including no defects, 10 such as partial peeling and cracking.

As described above, there is a trade off between forming the metal film without defects, such as peeling, and achieving excellent mold-release property between the supporting member and the metal film. Consequently, it has 15 been difficult to produce stably a metal film satisfying both of these conditions.

SUMMARY OF THE INVENTION

Accordingly, the present invention aims to provide a 20 manufacturing method for a metal film which can overcome or reduce the aforementioned problems. Thus the invention aims to satisfy both the requirement for excellent the mold-release property from the supporting member and the requirements that defects, for example, peeling and 25 cracking, are unlikely to occur during film making by the vacuum thin-film forming apparatus, or during metal film formation by plating or water washing after plating.

The present invention also aims to provide a laminated ceramic electronic component including the metal 30 film manufactured by application of the aforementioned manufacturing method for the metal film, and to provide a manufactu

- 6 - component. According to an aspect of the invention, there is provided a manufacturing method for a metal film comprising a first step of forming a first metal film made 5 of an electroless plating catalyst material on a supporting member using a vacuum thin-film forming apparatus, said first step being completed before the first metal film grows to a uniform continuous film; a second step of forming a second metal film made of an 10 electroless plating catalyse material by adhesion during application of immersion plating due to an ionic displacement reaction for at least the surface of the first metal film; and a third step of forming a third metal film by making a film from a metal while electroless plating is 15 applied using the second metal film as a catalyst.

The first metal film may be in the island structure (island stage), in the network structure (channel stage or hole stage), in the shape of a cluster, or in the shape of an atom or molecule. The metal film is preferably in the 20 island structure or in the network structure, and the metal regions of these structures are less than 1 x 1Os nm2, and more preferably, is in the island structure.

Preferably, the first metal film contains at least one metal selected from the group consisting of silver, 25 aluminum, cadmium, cobalt, copper, chromium, iron, gallium, iridium, manganese, nickel, lead, tin and zinc and the second metal film contains at least one metal which is selected from the group consisting of palladium, platinum, gold, silver, rhodium and iridium and which is a 30 metal capable of being substituted for the metal contained in the first metal film.

More preferably, the first metal film is a metal film selected from the group consisting of a copper film

- 7 - less than 30 nm in thickness, a silver film less than 20 nm in thickness, and an iron film less than lO nm in thickness. Preferably, the third metal film contains at least 5 one metal selected from the group consisting of nickel, copper, silver, palladium, platinum, cobalt, and rhodium.

In the first aspect, preferably, the time for performing the first step is controlled in order to complete the first step before the first metal film grows 10 to a uniform continuous film.

In the aforementioned case, preferably, a preparation step is undertaken to find out a critical time for growth of the first metal film to a uniform continuous film by forming the first metal film under the same film 15 making conditions as those in the first step except the condition with respect to time is further included, wherein a time shorter than this critical time is chosen as the time for performing the first step.

Preferably, in the first step, the first metal film 20 is patterned by being formed through a mask.

Preferably, the surface of the supporting member, on which the first metal film is to be formed, has been subjected to a mold-release treatment.

Preferably, as a film-shaped the supporting member 25 is used.

Any material is used for the supporting member and, for example, an organic material, carbon, metal, or metal oxide, is used.

The present invention also provides a metal film 30 produced by any one of the aforementioned manufacturing methods. Preferably, this metal film is used to form an

- 8 - internal conductor film to be provided in a laminated ceramic electronic component.

The present invention also relates to a laminated ceramic electronic component provided with a plurality of 5 laminated ceramic layers and an internal conductor film extending along a specified interface between the ceramic layers. In such a laminated ceramic electronic component embodying the present invention, the internal conductor film is brought about by the aforementioned metal film.

10 Typical examples of the aforementioned laminated ceramic electronic components include a multilayer ceramic capacitor. The present invention also provides a metal film produced by the aforementioned manufacturing method and 15 being formed on the supporting member. The manufacturing method for a laminated ceramic electronic component embodying the present invention is performed as described below by applying the metal film onto the supporting member. 20 The invention further provides a manufacturing method for a laminated ceramic electronic component comprising forming a first metal film made of an electroless plating catalyst material on a supporting member using a vacuum thin-film forming apparatus, said forming being completed 25 before the first metal film grows to a uniform continuous film; forming a second metal film made of an electroless plating catalyst material by adhesion during application of immersion pating due to an ionic displacement reaction for at least the first of the first metal film; forming a 30 third metal film by making a film from a metal while electroless plating is applied using the second metal film as a catalyst; producing a complex comprising the first and second metal films and a ceramic green sheet by

- 9 forming the ceramic green sheet on the supporting member to cover the metal films; producing a green laminate by laminating a plurality of the complexes; peeling away the supporting member from each of the complexes; and baking 5 the green laminate.

The invention still further provides a manufacturing method for a laminated ceramic electronic component comprising forming a first metal film made of an electroless plating seed material on a supporting member 10 using a vacuum thin-film forming apparatus, said first step being completed before the first metal film grows to a uniform continuous film; forming a second metal film made of an electroless plating catalyst material by adhesion during application of immersion plating due to an 15 ionic displacement reaction for at least the surface of the first metal film; forming a third metal film by making a film from a metal while electroless plating is applied using the second metal film as a catalyst; preparing a ceramic green sheet; producing a complex comprising the 20 second and third metal films and the ceramic green sheet by transferring the second metal films from supporting member to the ceramic green sheet; producing a green laminate by laminating a plurality of the complexes; and baking the green laminate.

25 The present invention further provides a laminated ceramic electronic component produced by the aforementioned manufacturing method.

As described above, in embodiments of the manufacturing method for the metal film according to the 30 present invention, the first metal film of electroless plating catalyst or seed material is formed so that it does not become a uniform continuous film, and subsequently, th

- 10 electroless plating using:he first metal film as a catalyst. Alternatively, the second metal film to become a catalyst for electroless plating is formed by an ionic displacement reaction for at least the surface of the 5 first metal film and, thereafter, the third metal film is formed by electroless plating using the second metal film as a catalyst.

Because of this approach, even when the combination of a supporting member and metal film or film making 10 conditions, which give excellent mold-release properties for the supporting member from the metal film excellent, are adopted, defects, for example, peeling and cracking in the metal film, can be made unlikely to occur during formation of the first metal film, or during electroless 15 plating for forming the second or third metal film and during water washing thereafter.

In the manufacturing method for the metal film embodying the present invention, as described above, the first metal film electroless plating catalyst or seed 20 material is formed so that it does not become a uniform continuous film. It was determined that when film making was performed until the first metal film grew to a uniform continuous film, sometimes, the first metal film peeled off during subsequent electroless plating or water 25 washing. However, when film making was completed before the first metal film grew to a uniform continuous film, the first metal film was unlikely to peel off during subsequent electroless plating or water washing. The present invention has been made based on this finding.

30 The reason for the occurrence of the phenomenon, from which the aforementioned finding was brought about, is assumed to be that when the first metal film is

- discontinuous, the internal stress of the coating of plating, that is, the second or third metal film, during electroless plating is relaxed for some reason.

Consequently, when a laminated ceramic electronic 5 component is produced using the metal film according to the present invention, excellent transfer of the metal film to the ceramic green sheet can be achieved reliably.

The time required for the transfer can be reduced and, furthermore, the yield of the laminated ceramic electronic 10 component can be improved.

In the manufacturing method for the metal film embodying the present invention, when the first metal film is made in the island structure or in a mesh network structure where the metal regions have an area of less 15 than l x lOs nm2, even if the metal film is formed under the aforementioned condition that excellent mold-release property can be achieved, the effect of preventing occurrence of defects can be achieved with further reliability. 20 When a mask is used in formation of the first metal film, even if the step of, for example, photolithography and etching, is not performed, a patterned metal film can be produced and, therefore, the step for producing a patterned metal film can be simplified.

25 The time for performing the step of forming the first metal film is controlled to complete before the first metal film grows to a uniform continuous film. In order to determine this time, a critical time for growth of the first metal film to a uniform continuous film is 30 found out. When a time shorter than this critical time is chosen as the time for performing the step of forming the first metal

r - 12 forming the first metal film can be determined with ease.

Once this time has been determined, in subsequent manufacture of the metal film, the first metal film can be formed stably without becoming a uniform continuous film.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will mow be described, by way of example, and with reference to the accompanying drawings, in which: 10 Figs. 1A and 1B are sectional views for explaining an embodiment of a manufacturing method for a metal film embodying the present invention, showing typical steps included in this manufacturing method; Fig. 2 is a sectional view illustrating the 15 condition of formation of the first metal film 2 shown in Fig. 1A under further magnification.

Figs. 3A to 3C are sectional views explaining a first embodiment of a manufacturing method for a laminated ceramic electronic component according to the present 20 invention, and showing typical steps included in this manufacturing method; Figs. 4A to 4C are sectional views explaining a second embodiment of the manufacturing method for a laminated ceramic electronic component according to the 25 present invention, and showing typical steps included in this manufacturing method.

Fig. 5 is an electron micrograph of the first metal film according to Example 1 produced in Experiment 1.

30 DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figs. 1A and 1B and Fig. 2 explain a first embodiment of a manufacturing method for a metal film according to the present invention.

In.

- 13 Regarding manufacture of a targeted metal film, as shown in Fig. 1A, a first step is performed of forming a first metal film 2 made of a material to become a catalyst for electroless plating on a supporting member 1 by the S use of a vacuum thin-film forming apparatus. Herein, preferably, a mask 3 is used, and the first metal film 2 is patterned by forming the first metal film 2 through this mask 3.

Examples of the aforementioned vacuum thin-film 10 forming apparatus, include a vacuum evaporation apparatus, sputtering apparatus, laser ablation apparatus, ion plating apparatus, cluster ion beam apparatus, and MBE apparatus. An organic material, carbon, metal, or metal oxide 15 can be used as the material for the supporting member 1.

Preferably, the supporting member 1 has a surface, on which the first metal film 2 is to be formed, which has been subjected to a mold-release treatment. When a material having low adhesion with respect to the first 20 metal film 2 is used as the material for the supporting member 1, the mold-release treatment for the surface of the supporting member 1 can be omitted.

For example, where an organic material such a fluororesin or silicone resin is used as the material for 25 the supporting member 1, excellent mold-release property can be imparted even if the mold-release treatment is omitted. The supporting member 1 may have the shape of a plate having relatively high rigidity, or the shape of a 30 film having pliability.

When the supporting member 1 is film-shaped, as this can be wound

- 14 -

of the manufacturing apparatus can be simplified where the metal film is continuously produced and, in addition, high productivity can be expected. Furthermore, since storage space can be reduced if the metal film is mass-produced, 5 and weight and volume can be reduced where the produced metal films are transported, storage cost and transportation cost can be reduced.

Where a film-shaped supporting member 1 is used, usually, the one made of polyethylene terephthalate, which 10 is equivalent to the carrier film used in molding of a ceramic green sheet, and can the carrier film used in molding of a ceramic green sheet be diverted. In this case, desirably, the surface of the carrier film has been subjected to a mold-release treatment with a fluororesin IS or silicone resin in order to perform peeling with ease.

As the material for the film-shaped supporting member 1, polypropylene, etc., in addition to polyethylene terephthalate can be used, and a film made of stainless steel, etc., other than the organic film can also be used.

20 At least one metal selected from the group consisting of palladium, silver, gold, platinum, nickel, cobalt, rhodium, and iridium may be used as the material constituting the first metal film 2 to become a catalyst for electroless plating. These metals may be used alone, 25 or in an alloy containing these metals.

In order to achieve excellent catalysis, it is necessary to prevent passivation due to formation of an oxide layer. Consequently, after the first metal film 2 is formed, it is necessary to perform promptly a step of 30 electroless plating described below, or to control to prevent formation of the oxide layer. It is preferable to use noble metals from the viewpoint of performing control

- 15 with ease. Most of all, palladium is desirable because of high catalysis with respect to various plating solutions.

It is also effective to perform electroless plating as described below after a treatment to remove the passive 5 layer.

In embodiments of the present invention, it is important to complete the first step of forming the first metal film before the first metal film 2 grows to a uniform continuous film.

10 The first metal film 2 formed by the first step may be in any form as long as it is not a uniform continuous film, as shown in Fig. 2. For example, the first metal film may be the island structure (island stage), the network structure (channel stage or hole stage), the shape 15 of an atom, the shape of a molecule, the shape of a cluster, or the like. In particular, the first metal film 2 is preferably not a uniform continuous film, and the metal regions have an area of less than l x lOs nm2. The form of the first metal film 2 is preferably the island 20 structure or the network structure, more preferably, is the island structure or the network structure in channel stage, and most preferably, is the island structure.

In general, in the growth process of thin film, the arrival of an atom at the supporting member, migration, 25 formation of a seed, growth of the seed, and coalescence occur in that order. Growth to a uniform continuous film occurs through the stages of the island structure and the network structure. The time required for growth to the uniform continuous film varies, depending on the film 30 making conditions, for example, the sorts and conditions of material to be adhered and the supporting member, and also the conditions set in a vacuum thin-film forming

- 16 apparatus. However, in genera;, when the thickness reaches in the order of several tens of nanometers at the maximum, growth to the uniform continuous film occurs. The present inventor's experiences show that when thicknesses become 5 lo nm or more, 20 nm or more, 30 nm or more, 20 nm or more, and lO nm or more with respect to palladium, silver, copper, gold, and iron, respectively, evaporated films grow to uniform continuous films regarding almost every supporting members and evaporation conditions.

10 Therefore, when the manufacturing method for the metal film embodying the present invention is performed, preferably, a preparation step is performed in advance, in which the film making condition, is determined. This may include for example, the type of the material constituting 15 the first metal film 2 and the supporting member l, and the conditions set in the vacuum thin-film forming apparatus, except the condition with respect to time.

Under this determined film making condition, the first metal film 2 is formed and, therefore, the critical time 20 for growth of the first metal film 2 to the uniform continuous film is found out.

In a practical mass-production stage, the first step for forming the first metal film 2 is performed with a time shorter than the critical time found out in the 25 aforementioned preparation step. Where the film is continuously made on long lengths of film to become the supporting member, the aforementioned time is controlled by the transport speed of the film. However, as a matter of course, the first metal film 2 must be formed in 30 adequate adhesion quantity to function as catalyst seeds for electroless plating in the later step of electroless plating.

- 17 As shown in Fig. lB, the second step of forming the second metal film 4 is performed by making a film from a specified metal while electroless plating is applied using the first metal film 2 as a catalyst.

5 In the electroless plating for forming the second metal film 4, an electroless plating bath is used. This may comprise of, for example, at least one metal selected from the group consisting of nickel, copper, silver, palladium, platinum, cobalt, and rhodium.

10 This second metal film 4 constitutes the key portion of the resulting metal film. The second metal film 4 is desirably composed of copper or nickel from the viewpoint of electrical conductivity, cost, etc. where this metal film is used as an internal conductor film of a laminated 15 ceramic electronic component and where it is possible to apply a reducing atmosphere when baking to produce the laminated ceramic electronic component. In this case, for example, an electroless copper plating bath, an electroless nickel-phosphorus alloy plating bath, and an 20 electroless nickel-boron alloy plating bath, can be used as the electroless plating bath.

On the other hand, if it is not possible to apply a reducing atmosphere at baking stage to produce the laminated ceramic electronic component, the second metal 25 film 4 is composed of silver, palladium, platinum, or an alloy thereof.

Alloys made by mixing the aforementioned various metals with other metal elements as eutectoid may be used. In addition to these, electroless plating baths of 30 cobalt-phosphorus,

cobalt-boron, rhodium, etc., can be used. As shown in Fig. lA, in the first step, a mask 3 is

- 18 used to form the first metal film 2, and the first metal film 2 is thereby patterned. Consequently, when electroless plating is performed in the second step, the second metal film 4 is formed only on the portion on which 5 the first metal film 2 has been formed and, therefore, the metal film can be patterned as a whole. As such a mask 3, for example, metal masks and various mask films can be used. The method for patterning is not limited to the to aforementioned method using the mask 3. Methods using various resists, for example, a photoresist, are possible.

A method, in which etching is performed after the first metal film 2 is formed, and a method, in which etching is performed after the second metal film 4 is formed, are 15 also possible.

However, from the viewpoint of simplification of the process, the method using the mask 3, such as a metal mask, is advantageous as the mask 3 can be attached or detached with ease, can be used repeatedly, and a 20 patterning condition has been achieved at the stage in which the first metal film 2 has been formed.

The manufacturing method for the metal film embodying the present invention can also be performed as described below.

25 In this second embodiment, the first step of forming the first metal film on the supporting member uses a vacuum thin-film forming apparatus. A material is used as the material for forming the first metal film which becomes a seed for the electroless plating, but which may 30 not have catalysis with respect to the electroless plating. This first step is completed before the first metal _ _

- 19 film grows to a uniform continuous film. This is similar to the first embodiment. The first metal film is preferably in the island structure or in a meshnetwork structure where the metal regions have an area of less 5 than 1 x 1Os nm2. This is also similar to the first embodiment. Subsequently, a material which will act as an electroless plating catalyst is substituted for the surface or whole of the first metal film to become a seed 10 for electroless plating by immersion plating and, thereby, the second step of forming a second metal film is performed. This second metal film is formed due to an ionic displacement reaction for at least the surface of the first metal film as described above and. Therefore, in 15 a manner similar to that of the first metal film, a uniform continuous film is not configured.

More specifically, in this second step, the supporting member, on which the first metal film has been formed, is immersed in a solution of a metal having 20 catalysis with respect to the electroless plating solution. Substitution reaction proceeds due to the difference in oxidation-reduction equilibrium potential in this immersed condition and, the second metal film is formed. Consequently, it is necessary that the oxidation 25 reduction equilibrium potential of the metal constituting the first metal film is more base than that of the metal constituting the second metal film. Conversely, it is necessary that the oxidationreduction equilibrium potential of the metal constituting the second metal film 30 is more noble than that of the metal constituting the first metal film.

As described above, the first metal film does not

- 20 necessarily have catalysis with respect to the electroless plating solution. It can be composed of, for example, at least one metal selected from the group consisting of silver, aluminum, cadmium, cobalt, copper, chromium, iron, 5 gallium, indium, manganese, nickel, lead, tin, and zinc.

Of these metals, cadmium, lead, tin, and zinc function as catalyst poisons and, therefore, when a glossy film is required, it is better to use a different metal.

On the other hand, palladium chloride hydrochloric 10 acid aqueous solution and the like can be used as a solution of a metal having catalysis used for forming the second metal film. This solution is generally used as an activation solution for pretreatment of electroless plating. As a matter of course, among other metals having 15 catalysis, those having an oxidation-reduction equilibrium potential nobler than that of the material constituting the first metal film can be used. That is, those capable of substituting for the metal contained in the first metal film. For example, platinum, gold, silver, rhodium, and 20 iridium, as well as palladium can be used.

The metals exemplified as contained in the first or second metal films may be used alone or as an alloy containing any one of these metals.

The third step of forming a third metal film is 25 performed by making a film from a metal while electroless plating is applied using the aforementioned second metal film as a catalyst. Since this third step corresponds to the second step of forming second metal film 4 in the aforementioned first embodiment, and is substantially 30 similar to this, the aforementioned explanation is also applied thereto.

As described above, the metal film Produced in the _.

- 21 first or second embodiment can be used advantageously in forming an internal conductor film of a laminated ceramic electronic component, for example, an internal electrode for forming capacitance of a multilayer ceramic capacitor.

5 Figs. 3A to 3C show a first embodiment of a manufacturing method for a laminated ceramic electronic component according to the present invention.

In Fig. 3A, the metal films 11 produced by the first or second embodiments of the manufacturing method 10 for the metal film according to the present invention are shown being formed on the supporting member 12. The metal films 11 are handled in the condition of being formed on the supporting member 12 as shown in Fig. 3A.

As shown in Fig, 3B, a complex 14 composed of the 15 metal films 11 and a ceramic green sheet 13 is produced by molding the ceramic green sheet 13 on the supporting member 12 in order to cover the metal films 11, As shown in Fig, 3C, a green laminate 15 is produced by laminating a plurality of complexes 14, As Fig, 3C, 20 shows an intermediate stage during lamination of the complexes 14 only a part of the green laminate is shown in the drawing, Fig, 3A shows that precedence in lamination is given to a complex 14 located at an upper position, 25 As shown in Fig, 3C, the complex 14 is backed by the supporting member 12 until it is laminated on the complex 14 which has been laminated precedingly, Consequently, every time a complex 14 is laminated, a plurality of complexes 14 are repeatedly pressure-bonded by application 30 of pressure from the supporting member 12 side as indicated by arrow 16, Thereafter, the supporting member 12 is peeled off as indicated by arrow 17,

- 22 The step of peeling the supporting member 12 may be performed before the step of laminating each complex 14.

When the green laminate 15 for production of a multilayer ceramic capacitor, alignment among the metal 5 films 11 is performed in order that an internal electrode for forming capacitance is configured by the metal films 11 facing each other with the ceramic green sheet 13 therebetween in the step of lamination.

The green laminate 15 is cut in order to produce a 10 laminate chip for an individual laminated ceramic electronic component. If necessary, and thereafter, it is subjected to a step of degreasing, and to a step of baking. Subsequently, terminal electrodes, etc., are formed 15 on the outer surface of the baked laminate and, therefore, a targeted laminated ceramic electronic component, such as a multilayer ceramic capacitor, is completed.

Figs. 4A to 4C are diagrams for explaining a second embodiment of the manufacturing method for the laminated 20 ceramic electronic component according to the present invention. In Fig. 4A, the metal films 21 are shown being formed on the supporting member 22 in a manner similar to that shown in Fig. 3A.

25 In Fig. 4A, a ceramic green sheet 24 molded on a carrier film 23 is shown.

As described above, the metal films 21 formed on the supporting member 22 and the ceramic green sheet 24 molded on the carrier film 23 are prepared, respectively, and, 30 thereafter, the following steps are performed sequentially. As shown in Fig. 4B, a step of forming a complex 25

-l - 23 of the metal films 21 and the ceramic green sheet 24 is performed by transferring the metal films 21 from the supporting member 22 to the ceramic green sheet 24.

Specifically, the metal films 21 formed on the 5 supporting member 22 and the ceramic green sheet 24 backed by the carrier film 23 are overlapped onto each other, and in that condition, the supporting member 22 and the carrier film 23 are pressed in the direction of overlapping. Subsequently, the supporting member 22 is 10 peeled off as indicated by arrow 26 and, thereby, the metal films 21 are transferred from the supporting member 22 to the ceramic green sheet 24.

As shown in Fig. 4C, a step of forming a green laminate 27 is performed by laminating a plurality of 15 complexes 25. In Fig. 4C, similarly to Fig. 3C, only a part of the green laminate 27 is shown in the drawing, and the drawing shows that precedence in lamination is given to a complex 25 located at an upper position.

The complex 25 is backed by the carrier film 23 20 until it is laminated on the preceedingly laminated complex 25. Consequently, after the complex 25 is laminated, pressure is applied from the carrier film 23 side as indicated by an arrow 28, the complexes 25 are repeatedly pressure-bonded with each other and, 25 thereafter, the carrier film 23 is peeled off as indicated by arrow 29, so that the green laminate 27 is produced.

The step of peeling the carrier film 23 may be performed before the step of laminating each complex 25.

In a manner similar to that in the aforementioned 30 first embodiment, the green laminate 27 thus produced is cut, and if necessary, subjected to a step of degreasing and baking. Subsequently, terminal electrodes, etc., are

formed and, therefore, a targeted laminated ceramic electronic component, such as a multilayer ceramic capacitor, is produced.

Embodiments of the present invention can be applied 5 to laminated ceramic electronic components, for example, multilayer ceramic supporting members, laminated ceramic inductors, and laminated filters, as well as multilayer ceramic capacitors.

Next, Experiments, which were performed in order to 10 verify the effects according to embodiments of the present invention, will be described.

Experiment l In Experiment l, examples and comparative examples 15 regarding the manufacturing method for the metal film were performed, respectively, and evaluations thereof were made. 1. Example l

(l) A film made of polyethylene terephthalate, on 20 which a siliconebased mold-release layer had been formed, was prepared as a supporting member. A metal mask made of stainless steel 0.2 mm in thickness was prepared, on which openings had been placed at the portions that would become a plurality of internal electrodes for a multilayer 25 ceramic capacitor.

(2) The aforementioned metal mask was closely adhered to the surface of the supporting member, on which the mold-release layer had been formed. A first metal film was formed by evaporating palladium on the openings of the 30 metal mask at a film making rate of l A/sec on a quartz resonator thickness gauge basis for lO seconds by a vacuum evaporation apparatus through this metal mask.

- 25 The first metal film formed from palladium was observed with an electron microscope (TEM), and it was verified that palladium existed in the island structure where the metal regions have an area of less than l x lO5 5 nm2.

Fig. 5 is an electron micrograph of the aforementioned first metal film. In Fig. 5, reference numeral l denotes the supporting member, and reference numeral 2 denotes the first metal film.

10 (3) The supporting member, on which the first metal film had been formed, was immersed in an electroless nickel-phosphorous alloy plating bath using phosphinic acid as a reducing agent to form a second metal film. In this electroless plating, the bath temperature was 80_C, 15 and the immersion time was 50 seconds.

The film thickness of thus formed metal film was 0.7 um. This metal film had no defects and had excellent mold-release properties.

20 2. Example 2 (l) A supporting member and a metal mask similar to those in (l) of Example l were prepared.

(2) The aforementioned metal mask was closely adhered to the surface on the mold-release layer side of 25 the aforementioned supporting member. A first metal film was formed by evaporating iron on the openings of the metal mask at a film making rate of 2 A/sec on a quartz resonator thickness gauge basis for lO seconds by a vacuum evaporation apparatus through this metal mask.

30 The first metal film formed from iron was observed with an electron microscope (TEM), and it was verified that iron existed in the island structure where the metal

- 26 regions have an area of less than 1 x 1Os nm2.

(3) Palladium was substituted for the surface of the I first metal film made of iron by immersing the supporting member, on which the first metal film had been formed, in 5 a palladium chloride hydrochloric acid aqueous solution for one minute, and thereby, the second metal film made of palladium was formed.

(4) The supporting member, on which the second metal film had been formed, was immersed in an electroless 10 nickel-phosphorous alloy plating bath similar to that in the step (3) of Example 1 for a similar immersion time and, therefore, a third metal film was formed by electroless plating.

The film thickness of thus formed metal film was 0.7 15 um.

This metal film had no defects and had excellent mold-release properties.

3. Example 3

(1) A supporting member and a metal mask similar to 20 those in (1) of Example 1 were prepared.

(2) The aforementioned metal mask was closely adhered to the surface on the mold-release layer side of the aforementioned supporting member. A first film was formed by evaporating silver on the openings of the metal 25 mask at a film making rate of 6 A/sec on a quartz resonator thickness gauge basis for 16 seconds by a vacuum evaporation apparatus through this metal mask.

The first metal film formed from silver was observed with an electron microscope (TEM), and it was verified 30 that the first metal film existed in the island structure where the metal regions have an area of less than 1 x 105 nm

- 27 (3) The supporting member, on which the first metal film had been formed, was immersed in an electroless nickel-phosphorous alloy plating bath similar to that in the step (3) of Example 1 for a similar immersion time 5 and, therefore, a second metal film was formed by electroless plating.

The film thickness of thus formed metal film was 0.6 m. This metal film had no defects and had excellent 10 mold-release properties.

4. Example 4

(1) A supporting member and a metal mask similar to those in (1) of Example 1 were prepared.

(2) The aforementioned metal mask was closely 15 adhered to the surface on the mold-release layer side of the aforementioned supporting member. A first metal film was formed by evaporating silver on the openings of the metal mask at a film making rate of 5 A/sec on a quartz resonator thickness gauge basis for 10 seconds by a vacuum 20 evaporation apparatus through this metal mask.

The first metal film formed from silver was observed with an electron microscope (TEM), and it was verified that the first metal film existed in the island structure where the metal regions have an area of less then 1 x 105 25 nm2.

(3) Palladium was substituted for the surface of the first metal film made of silver by immersing the supporting member, on which the first metal film had been formed, in a palladium chloride hydrochloric acid aqueous 30 solution for one minute, and thereby, the second metal film made of palladium was formed.

(4) The supporting member, on which the second metal

- 28 film had been formed, was immersed in an electroless nickelphosphorous alloy plating bath similar to that in i the step (3) of Example 1 for a similar immersion time -

and, therefore, a third metal film was formed by S electroless plating.

10 5. Example 5 (1) A supporting member and a metal mask similar to those in (1) of Example 1 were prepared.

(2) The aforementioned metal mask was closely adhered to the surface on the mold-release layer side of IS the aforementioned supporting member. A first metal film was formed by evaporating copper on the openings of the metal mask at a film making rate of 4 A/sec on a quartz resonator thickness gauge basis for 30 seconds by a vacuum evaporation apparatus through this metal mask. c 20 The first metal film formed from copper was observed with an electron microscope (TEM), and it was verified that the first metal film existed in the island structure where the metal regions have an area of less than 1 x 105 nm2 25 (3) Palladium was substituted for the surface of the first metal film made of copper by immersing the supporting member, on which the first metal film had been formed, in a palladium chloride hydrochloric acid aqueous solution for one minute, and thereby, the second metal 30 film made of palladium was formed.

(4) The supporting member, on which the second metal film had been formed, was immersed in an electroless

l - 29 nickel-phosphorous alloy plating bath similar to that in the step (3) of Example l for a similar immersion time and, therefore, a third metal film was formed by electroless plating.

5 The film thickness of thus formed metal film was 0.7 um. This metal film had no defects and had excellent mold-release properties.

6. Comparative example l 10 (l) A supporting member and a metal mask similar to those in (l) of Example l were prepared.

(2) The aforementioned metal mask was closely adhered to the surface on the mold-release layer side of the aforementioned supporting member. A first metal film 15 was formed by evaporating palladium on the openings of the metal mask at a film making rate of l A/sec on a quartz resonator thickness gauge basis for lOO seconds by a vacuum evaporation apparatus through this metal mask.

The first metal film formed from palladium was 20 observed with an electron microscope (TEM), and it was verified that the first metal film was a uniform continuous film over an area of greater than l x 105 nm2.

(3) Immersion in an electroless nickel-phosphorous alloy plating bath similar to that in the step (3) of 25 Example l for a similar immersion time was performed and, therefore, an operation for forming a second metal film by electroless plating was performed.

However, the second metal film peeled off together the first metal film during this electroless plating and 30 during water washing after the plating and, therefore, a metal film could not be formed excellently.

7. Comparative example 2

- 30 (l) A supporting member and a metal mask similar to those in (l) of Example l were prepared.

(2) The aforementioned metal mask was closely adhered to the surface on the mold-release layer side of 5 the aforementioned supporting member. A first metal film was formed by evaporating nickel on the openings of the metal mask at a film making rate of lO A/sec on a quartz resonator thickness gauge basis for lOO seconds by a vacuum evaporation apparatus through this metal mask.

10 The first metal film formed from nickel was observed with a scanning electron microscope (SEM), and it was verified that the first metal film was a uniform continuous film over an area of greater than l x lOs nm2.

(3) The supporting member, on which the first metal 15 film had been formed, was immersed in an electroless nickel-phosphorous alloy plating bath similar to that in the step (3) of Example l for a similar immersion time and, therefore, a second metal film was formed by electroless plating.

20 The film thickness of thus formed metal film was 0.8 um. This metal film had poor mold-release property, and was not transferred when transfer to a ceramic green sheet was attempted.

25 [Experiment 2] In this Experiment, a multilayer ceramic capacitor was produced using the metal film according to Example l in Experiment l as an internal electrode.

A ceramic green sheet 7 Am in thickness containing 30 barium titanate as a primary material was formed on a supporting member, on which a metal film had been formed, by a doctor blade method.

- 31 A green laminate provided with a plurality of metal films and a plurality of ceramic green sheets was produced by repeatedly press bonding a plurality of complexes each composed of the ceramic green sheet and the metal film 5 laminated together. Press-bonded of the complexes with each other was performed by pressuring from the supporting member side.

The peeling property of the metal film from the supporting member was excellent during this step.

10 The green laminate was cut into a predetermined size and, thereafter, was baked at a temperature of 1200 C.

Subsequently, a terminal electrode was formed and, therefore, a multilayer ceramic capacitor was produced.

Various modifications to the embodiment described 15 are possible and will occur to the those skilled in the art without departing from the scope of the invention which is defined by the following claims.

Claims

l i - 32 CLAIMS

A manufacturing method for a metal film comprising: 5 a first step of forming a first metal film made of an electroless plating catalyst material on a supporting member using a vacuum thin-film forming apparatus, said first step being completed before the first metal film grows to a uniform continuous film; 10 a second step of forming a second metal film made of an electroless plating catalyse material by adhesion during application of immersion plating due to an ionic displacement reaction for at least the surface of the first metal film; and 15 a third step of forming a third metal film by making a film from a metal while electroless plating is applied using the second metal film as a catalyst.
2. The manufacturing method for a metal film according 20 to Claim 1, wherein the first step, the first metal film is

in the island structure or in the network structure, and wherein the metal regions of the island structure or the network structure are less than 1 x 105nm2 25
3. The manufacturing method a the metal film according to claim 1, wherein the first metal film comprises at least one metal selected from the group consisting of palladium, silver, gold, platinum, nickel, cobalt, rhodium and iridium.
4. The manufacturing method for a metal film according to Claim 1, wherein the first metal film comprises at least one metal selected from the group consisting of

- 33 silver, aluminum, cadmium, cobalt, copper, chromium, iron, gallium, indium, manganese, nickel, lead, tin and zinc and the second metal film comprises at least one metal which is selected from the group consisting of palladium, platinum, 5 gold, silver, rhodium and iridium and which is a metal capable of being substituted for the metal contained in the first metal film.
5. The manufacturing method for a metal film 10 according to Claim 1, wherein the first metal film comprises a metal film selected from the group consisting of a copper film less than 30 nm in thickness, a silver film less than 20 nm in thickness, and an iron film less than 10 nm in thickness.
6. The manufacturing method for a metal film according to Claim 1, wherein in the first step, the first metal film is patterned by being formed through a mask.

20
7. The manufacturing method for a metal film according to Claim 1, wherein the supporting member, having a surface on which the first metal film is formed, is subjected to a mold-release treatment.

25
8. A metal film produced by a manufacturing method according to Claim 1.
9. A manufacturing method for a laminated ceramic electronic component comprising: 30 forming a first metal film made of an electroless plating catalyst material on a supporting member using a vacuum thin-film forming apparatus, said forming being completed before the first metal film grows to a uniform

- 34 continuous film; forming a second metal film made of an electroless plating catalyst material by adhesion during application of immersion pating due to an ionic displacement reaction 5 for at least the first of the first metal film; forming a third metal film by making a film from a metal while electroless plating is applied using the second metal film as a catalyst; producing a complex comprising the first, second and 10 third metal films and a ceramic green sheet by forming the ceramic green sheet on the supporting member to cover the metal films; producing a green laminate by laminating a plurality of the complexes and peeling away the supporting member 15 after each complex has been laminated onto each preceding complex; and baking the green laminate.
10. A manufacturing method for a laminated ceramic 20 electronic component comprising: forming a first metal film made of an electroless plating seed material on a supporting member using a vacuum thin-film forming apparatus, said first step being completed before the first metal film grows to a uniform 25 continuous film; forming a second metal film made of an electroless plating catalyst material by adhesion during application of immersion plating due to an ionic displacement reaction for at least the surface of the first metal film; 30 forming a third metal film by making a film from a metal while electroless plating is applied using the second metal film as a catalyst; preparing a ceramic green sheet;

- 35 producing a complex comprising the second and third metal films and the ceramic green sheet by transferring the second and third metal films from supporting member to the ceramic green sheet; 5 producing a green laminate by laminating a plurality of the complexes; and baking the green laminate.
11. A laminated ceramic electronic component 10 produced by the manufacturing method according to Claim 9 or Claim 10.