JP3152098B2 - Manufacturing method of ceramic laminated electronic component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic laminated electronic component having an internal electrode formed by a thin film forming method, and more particularly, to a ceramic laminated electronic component in which steps from formation of an internal electrode to firing are improved. The present invention relates to a method for manufacturing an electronic component. INDUSTRIAL APPLICATION This invention can be utilized for the manufacturing method of various ceramic laminated electronic components, such as a laminated capacitor, a laminated piezoelectric component, and a ceramic multilayer substrate.

[0002]

2. Description of the Related Art For example, when manufacturing a ceramic multilayer electronic component having internal electrodes such as a multilayer capacitor, a metal-ceramic integrated firing technique is used. That is, a conductive paste is pattern-printed on a ceramic green sheet to form internal electrodes. Next, a plurality of ceramic green sheets on which internal electrodes are formed are laminated, and an appropriate number of ceramic green sheets on which no internal electrodes are printed are laminated on the upper and lower sides to obtain a ceramic laminate. Alternatively, the ceramic paste and the conductive paste are sequentially printed in a predetermined shape to obtain a ceramic laminate. Thereafter, the ceramic laminate obtained as described above is pressed in the thickness direction to bring the ceramic layers into close contact with each other. Thereafter, the ceramic laminate is fired to obtain a sintered body. Appropriate external electrodes are formed on the outer surface of the obtained sintered body to obtain a ceramic laminated electronic component.

In recent years, electronic components have been required to be further reduced in size, and ceramic laminated electronic components have also been strongly required to be reduced in size and thickness. In order to reduce the size and thickness of ceramic multilayer electronic components, it is necessary to reduce the thickness of the ceramic layer sandwiched between the internal electrodes. Therefore, a ceramic laminate is manufactured using thinner ceramic green sheets. There must be.

[0004] However, there is a limit in reducing the thickness of the ceramic green sheet. If the thickness is too small, the ceramic green sheet cannot be handled alone. In addition, at the stage of obtaining the ceramic laminate, the portion where the internal electrodes overlap is thicker than the portion where the internal electrodes are not present, and a step tends to occur between the two. In particular, at the stage where the ceramic laminate is pressed in the thickness direction prior to sintering, since the steps are generated, the upper and lower layers are pressed only in the overlapping portions of the internal electrodes, and in other regions, Was not pressurized. As a result, a delamination phenomenon called delamination tends to occur in the sintered body.
Furthermore, the internal electrode swells due to the solvent in the ceramic green sheet, and an internal electrode having a desired shape may not be accurately formed.

Therefore, it has been very difficult to reduce the thickness of the ceramic green sheet to about 6 μm or less. The above-mentioned problem is the same in a method of printing a ceramic paste and a conductive paste alternately to obtain a ceramic laminate.

In order to solve the above-mentioned problems, a method has been proposed in which a metal film formed by a thin film forming method is used as an internal electrode, for example, the following first and second methods.

In the first method, for example, as shown in FIG. 1, a metal film is formed on the entire surface of a support 1 by a thin film forming method such as sputtering. Next, a resist layer having an opening corresponding to the shape of the electrode is formed on the metal film, and the metal film is patterned by photolithography. Thus, the metal film 2 shown in FIG. 1 is formed. Thereafter, a ceramic green sheet 3 is formed on the metal film 2. The laminate 4 is obtained by repeating the steps of forming the metal film 2 and the ceramic green sheet 3.

The second method is disclosed in Japanese Patent Application Laid-Open No. Sho 64-42809.
As disclosed in Japanese Unexamined Patent Publication No.
And a metal film is formed on the second support film by a thin film forming method. Thereafter, the metal film supported by the second support film is transferred onto the ceramic green sheet on the first support film to obtain a metal film integrated green sheet.
By laminating a plurality of green sheets integrated with a metal film obtained as described above, a ceramic laminate is obtained.

In the first and second methods using the metal film formed by the above-mentioned thin film forming method as the internal electrode, the thickness of the internal electrode can be reduced as compared with the internal electrode forming method using the conductive paste. it can.

[0010]

However, in both of the first and second methods described above, although the thickness of the internal electrode can be reduced to some extent, when the thickness of the ceramic multilayer electronic component is further reduced. However, the number of layers increases, and the thickness of the internal electrodes becomes larger than the thickness of the ceramic layer sandwiched between the internal electrodes. Therefore, in the first method, as shown in FIG. 2, in the obtained laminate 5, a portion 6 where only the ceramic green sheets are laminated and a portion 7 where the internal electrode 8 overlaps,
Again, a difference in thickness occurs. Therefore, when the obtained laminate is pressed in the thickness direction, pressure tends to be applied only to the portion where the internal electrodes 8 overlap, and the adhesion between the ceramic layers in a region where the internal electrodes do not overlap is impaired. Therefore, there is a problem that delamination easily occurs in the finally obtained sintered body.

In the first method, after a metal film is formed on a support, complicated processes such as pattern formation and etching with a resist layer, removal of the resist layer, and the like are required, and thus the process becomes complicated. There was also a problem.

Also, in the second method using the transfer method, the thickness of the portion where the internal electrodes overlap also becomes thicker than the thickness of the non-overlapping region of the internal electrodes as the thickness of the device decreases. Become. Accordingly, similarly, there is a problem that delamination tends to occur in the obtained laminate. In addition, when the thickness of the ceramic green sheet is reduced, the thickness of the metal film-integrated green sheet is also reduced, which makes handling difficult.
Furthermore, since a metal film is transferred onto a ceramic green sheet to form a metal film-integrated green sheet, the pattern accuracy of the metal film may not be sufficient.

In addition, when the metal film and the ceramic green sheet are integrated, the ceramic green sheet is brought into contact with the second support film in a portion where the metal film does not exist. Therefore, it is necessary to peel off the second support film from the metal film-integrated green sheet after the integration, so that the peelability of the second support film from both the metal film and the ceramic green sheet is good. Required. However, it is difficult to satisfy such requirements, and the ceramic green sheet tends to be broken when the second support film is peeled off.

An object of the present invention is to reduce the difference in thickness between the region where the internal electrodes are formed and the region where the internal electrodes are not formed at the stage of the ceramic laminate, and thus effectively suppress the occurrence of delamination and the like. It is an object of the present invention to provide a method of manufacturing a ceramic laminated electronic component which can be performed.

[0015]

SUMMARY OF THE INVENTION The present invention is a method of manufacturing a ceramic laminated electronic component including a step of forming an internal electrode by a thin film forming method, and comprises the following steps.

That is, according to the present invention, there is provided a step of forming a first metal film on a support by a thin film forming method, and a step of partially forming a thickness on the first metal film which is larger than that of the first metal film. Forming a second metal film having a large thickness by a thin film forming method to form a multilayer metal film, forming a ceramic laminate including the multilayer metal film therein, and forming a second metal film in the ceramic laminate. A first metal film portion that is not located below the metal film is converted into an insulator so that constituent metal components diffuse into the ceramic, and the ceramic is fired. This is a method for manufacturing a laminated electronic component.

In a specific aspect of the present invention, the first
The thickness of the metal film is 100 nm or less, and the thickness of the second metal film is 300 nm or more and 1000 nm or less. This is because the first metal film needs to be configured such that the first metal film portion not located below the second metal film is converted into an insulator when the ceramic is fired as described above. is there. That is, by setting the thickness of the first metal film to 100 nm or less, the metal component constituting the first metal film can be easily diffused into the ceramics in the form of oxide ions by heating. The reason why the thickness of the second metal film is set to 300 nm or more is to prevent oxidation of the second metal film when the first metal film portion is made into an insulator. That is, since the second metal film is a portion that functions as an internal electrode to the last, it must not be oxidized, and therefore is preferably formed to a thickness of 300 nm or more as described above. Although the upper limit of the thickness of the second metal film is not particularly limited, it is usually 1000 nm or less for use as an internal electrode of the ceramic laminated electronic component and for reducing the step which is the object of the present invention. It is said.

In another specific aspect of the present invention, the first metal film portion is made into an insulator and the ceramic is fired by oxidizing the first metal film and oxidizing the second metal film without oxidizing the second metal film. This is performed by firing the ceramic laminate under a partial pressure. That is, by controlling the oxygen partial pressure as described above, the first metal film is oxidized during firing of the ceramics, and the first metal film portion that is not located below the second metal film is insulated. And oxidation of the second metal film can be prevented. Since the value of the oxygen partial pressure in this case differs depending on the material for forming the first and second metal films, the thickness of the first and second metal films, the temperature and time for firing, and the like, it is univocally. Cannot be determined.

In the present invention, the step of forming the above-mentioned multilayer metal film can be carried out by using an appropriate photolithography technique. For example, a resist layer provided with pattern holes on the first metal film may be used. The step of forming, the step of forming a second metal film in the pattern hole of the resist layer by a thin film forming method, and the step of removing the resist layer can be performed.

The step of obtaining a ceramic laminate having the above-mentioned multilayer metal film inside can also be carried out by using a conventionally known transfer method or the like. According to a specific aspect of the present invention, the step of forming the ceramic laminate includes forming a ceramic green sheet on a multilayer metal film by an appropriate method to obtain a metal film-integrated green sheet; And laminating a film-integrated green sheet. According to another specific aspect of the present invention, the step of forming the ceramic laminate includes forming a ceramic green sheet on a second support and supporting the ceramic green sheet on the ceramic green sheet. Transferring a multilayer metal film that has been obtained, a step of obtaining a metal film integrated green sheet, and a step of sequentially transferring and stacking a plurality of metal film integrated green sheets to obtain a ceramic laminated body by a transfer method including Done. In the case of this transfer method, preferably, the multilayer metal film can be transferred onto the ceramic green sheet using a roll press.

[0021]

According to the method for manufacturing a ceramic laminated electronic component of the present invention, the first metal film is formed on the entire surface, and the first metal film is provided, so that the region where the internal electrodes overlap (the second electrode) is formed. (The region where the metal films overlap) and the region where the internal electrodes do not overlap can be reduced. Therefore, the occurrence of delamination in the obtained sintered body can be effectively reduced.

In addition, the first metal film is converted into an insulating material in the firing step of the ceramic. Therefore, the first metal film formed to reduce the step does not eventually function as a conductor. Therefore, even if the first metal film is formed, a short circuit failure does not occur. In addition, since it is not necessary to partially remove the first metal film by etching or the like in a later step, an extra step is not required to obtain a multilayer metal film.

Further, the first metal film is diffused in the form of oxide ions in the ceramics. By controlling the composition of the first metal film, it is possible to control the composition of the ceramics. Become. Therefore, it is possible to provide a ceramic laminated electronic component capable of exhibiting desired characteristics.

Further, the multilayer metal film is supported by the support, but in this state, only the first metal film is in contact with the support. Therefore, when considering the releasability of the multilayer metal film with respect to the support, the support may be selected in consideration of only the releasability with respect to the first metal film. Can be done. Therefore, for example, when the multilayer metal film is transferred onto the ceramic green sheet formed on the second support, the multilayer metal film can be smoothly separated from the support. In addition, since the second support is in contact only with the ceramic green sheet, the second support may have only the releasability with respect to the ceramic green sheet. Design of the releasability of the support is also facilitated.

The present invention can be applied to a method for manufacturing various kinds of ceramic laminated electronic parts containing internal electrodes, such as multilayer capacitors, laminated ceramic piezoelectric parts, and ceramic multilayer substrates.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing non-limiting embodiments of the present invention.

The following embodiment is an example in which the present invention is applied to the manufacture of a multilayer capacitor. However, the steps up to the step of obtaining an unfired ceramic laminate are performed using a mother multilayer metal film and a mother ceramic green sheet. Have been done.

Example 1 As shown in FIG. 3A, a polyethylene terephthalate (PET) film 11 was prepared as a first support. The upper surface of the PET film 11 is coated with a silicone resin (not shown). On the PET film 11, a first metal film 12 is formed. here,
The first metal film 12 is made of Ag having a thickness of 70 nm by an evaporation method.
It is configured by forming a film on the entire surface.

Next, a resist layer having a thickness of 1 μm is applied on the first metal film 12, and is subjected to exposure and development treatments, thereby forming the patterned resist layer 13 as shown in FIG. To form

Next, the pattern holes 13a of the resist layer 13 are formed.
Inside, a second metal film 14 is formed by a thin film forming method.
In this embodiment, the second metal film 14 is formed by electroplating Pd so as to have a thickness of 0.5 μm.

Next, the resist layer 13 is removed with a resist stripper or the like. Thus, the multilayer metal film 15 shown in FIG. 4 is obtained. In the multilayer metal film 15, the second metal film 14 is partially formed on the first metal film 12. Therefore, the multilayer metal film 15 is in contact with the PET film 11 only on the lower surface of the first metal film 12. Therefore, since the releasability of the PET film 11 may be set in consideration of only the first metal film 12, it is understood that the releasability on the upper surface of the PET film 11 can be easily designed.

The second metal film 14 corresponds to a portion finally used as an internal electrode, and the first metal film 12 is made into an insulator by a process described later. Next, the above P
On the ET film 11, a ceramic green sheet is formed on the multilayer metal film 15. In the present embodiment, the ceramic slurry was applied to a thickness of 8 μm by a microgravure method.
The ceramic green sheet 16 is formed by forming the sheet so as to obtain m (see FIG. 5).

As shown in FIG. 5, by forming the ceramic green sheet 16, the metal film-integrated green sheet 17 is prepared while being supported by the PET film 11.

Next, the metal sheet integrated green sheet 1
By laminating layers 7 sequentially, a laminated body 18 shown in FIG. 6 is obtained. Although FIG. 6 shows only some layers below the laminate 18, actually, a plurality of metal film integrated green sheets are further laminated on the upper side. Reference numeral 19 denotes a support film for lamination.

The mother ceramic laminate 18 obtained as described above is cut in the thickness direction so as to form an unfired ceramic laminate for each individual multilayer capacitor, thereby obtaining individual ceramic laminates for a multilayer capacitor. .

Next, the obtained ceramic laminate is fired in the atmosphere by maintaining it at a temperature of 1200 ° C. for 4 hours. In this firing, not only the unfired ceramic is fired, but also the first metal film 12 is turned into an insulator. That is, the metal component constituting the first metal film 12 becomes oxide ions and diffuses into the surrounding ceramics to become an insulator. Therefore, as shown in FIG. 7, a cross section of the obtained sintered body is obtained.
Only the internal electrode made of the second metal film 14 remains in the sintered body 20. Note that FIG. 7 also shows only some of the second metal films 14, but actually, a large number of second metal films overlap with each other via ceramic layers as internal electrodes.

The multilayer capacitor 21 shown in FIG. 8 is obtained by forming a pair of external electrodes on both end surfaces of the sintered body 20 obtained as described above. In the multilayer capacitor 21, a plurality of internal electrodes made of the second metal film 14 are overlapped via the ceramic layer in the sintered body 20. Note that reference numerals 22a and 22b denote external electrodes, and the external electrodes 22a and 22b can be formed by an appropriate method such as application and baking of conductive paste or plating.

In the multilayer capacitor obtained as described above, the step between the portion where the internal electrode overlaps and the portion where the internal electrode does not overlap was examined. The thickness of the first metal film × the thickness of the first metal film. It was confirmed that the step could be reduced by the number of layers.

Further, 20 laminated capacitors were prepared, and cut so that the cross section shown in FIG. 8 was exposed, and the presence or absence of delamination was observed. As a result, no delamination was observed. Similarly, when 20 multilayer capacitors were cut so that a cross section orthogonal to the cross section shown in FIG. 8 was exposed, and the cross sections were observed, no delamination was observed.

For comparison, the presence or absence of delamination of a conventional multilayer capacitor, which was obtained according to the first method described in the description of the prior art, was observed. When the cross section in the direction was observed, delamination was observed in 5 of the 20 multilayer capacitors.

The melting point of the first metal film is about 960 ° C., which is sufficiently lower than the above-mentioned firing temperature of 1200 ° C.
The first metal film was surely made into an insulator, and therefore, no short-circuit failure occurred in the multilayer capacitor of the example.

Example 2 A multilayer capacitor was manufactured in the same manner as in Example 1. However, the first metal film was made of Cu, and the second metal film was made of Ni. For ceramic slurries,
A BaTiO ₃ ceramic containing no Cu was used. At the beginning of the baking process, that is, a half of the period during which the baking was performed at the highest baking temperature, the baking was performed by setting the oxygen partial pressure to a value such that the Ni plating film was not oxidized and the Cu vapor deposition film was oxidized. Specifically, the oxygen partial pressure was set to 10 ⁻⁴ Pa at the beginning of the firing step. In addition, the above 10 ^-4 Pa
After the initial stage of the firing step was performed at an oxygen partial pressure of 2, the firing was performed in a reducing atmosphere. For the others, Example 1
In the same manner as in the above, a multilayer capacitor was produced.

As a result of analyzing the sintered body of the multilayer capacitor obtained in Example 2, it was confirmed that Cu was uniformly present in the ceramics. That is, it was confirmed that Cu constituting the first metal film was diffused into the ceramic.

Further, the electrical characteristics of the obtained multilayer capacitor
When the characteristics were measured, BaTiO _ThreeSystem ceramics
The same result as in the case where Cu powder was added was obtained. Ma
Also, as in Example 1, the cross section of the multilayer capacitor was observed.
As a result, no delamination was observed.

In the second embodiment, the oxygen partial pressure at the initial stage of firing is controlled as described above to diffuse Cu constituting the first metal film. By containing an agent or a diffusion promoter, the metal component constituting the first metal film may be diffused into the ceramic.

Embodiment 3 As shown in FIG. 9, a PET film 31 as a second support is prepared. The upper surface of the PET film 31 is coated with a silicone resin (not shown).

A ceramic green sheet 32 having a thickness of 8 μm is formed on a PET film 31 by forming a ceramic slurry by a doctor blade method and drying the slurry.

On the other hand, a PET film 33 shown in FIG. 10 is prepared as a first support. The upper surface of the PET film 33 is coated with a silicon resin (not shown).

A first metal film 34 and a second metal film 35 are formed on the PET film 33 in the same manner as in the first embodiment. In the present embodiment, the first metal film 34 is made of Ag, and the second metal film 35 is made of Pd. Thus, the multilayer metal film 36 is formed.

Next, as shown in FIG. 11, the multilayer metal film 36 is transferred onto the ceramic green sheet 32 by using a calender roll 37. Next, the PET film 31 is peeled to obtain the metal film integrated green sheet 38 shown in FIG.

Further, a laminate is obtained by laminating the metal film integrated green sheets 38 obtained as described above. That is, the metal sheet integrated green sheet 3
By peeling and laminating the PET film 33 while transferring 8 by the transfer method, a ceramic laminate similar to that obtained in Example 1 can be obtained.

Using the ceramic laminate obtained as described above, a multilayer capacitor was produced in the same manner as in Example 1. When the presence or absence of delamination of the obtained multilayer capacitor of Example 3 was observed in the same manner as in Example 1, no occurrence of delamination was observed.

In the conventional method of manufacturing a multilayer capacitor using the transfer method, two types of ceramics and a metal film are in contact with the support film. Both mold release and metal release had to be considered. On the other hand, in Example 3, the PET film 3
3 is in contact only with the first metal film 34,
The releasability of the T film 33 can be designed by considering only the releasability of the first metal film 34.

In the first to third embodiments, the first metal film 1
2, 34 are partially diffused in the firing step and are converted into an insulating material. Therefore, it is understood that there is no need to perform a complicated process of removing the first metal film portion not located below the second metal film by etching or the like.

In the first to third embodiments, the first metal film is made of Ag or Cu, and the second metal film is made of Pd or Ni. It is also possible to use a metal material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a conventional method for manufacturing a multilayer capacitor.

FIG. 2 is a cross-sectional view of a sintered body for describing a problem in a conventional method for manufacturing a multilayer capacitor.

FIGS. 3A and 3B are cross-sectional views respectively showing a state in which a first metal film is formed and a state in which a second metal film is formed in a pattern hole of a resist in Examples.

FIG. 4 is a cross-sectional view showing a state in which a multilayer metal film is formed on a support in Examples.

FIG. 5 is a cross-sectional view showing a state where a ceramic green sheet is formed on a multilayer metal film to form a metal film integrated green sheet.

FIG. 6 is a cross-sectional view illustrating a ceramic laminate.

FIG. 7 is a sectional view of a sintered body.

FIG. 8 is a sectional view showing a multilayer capacitor.

FIG. 9 is a cross-sectional view showing a state where a ceramic green sheet is formed on a second support in Example 3.

FIG. 10 is a sectional view showing a state where a multilayer metal film is formed.

FIG. 11 is a cross-sectional view illustrating a step of transferring a multilayer metal film to a ceramic green sheet in Example 3.

FIG. 12 is a cross-sectional view for explaining a metal sheet-integrated green sheet obtained in Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... PET film (1st support) 12 ... 1st metal film 13 ... Resist layer 13a ... Pattern hole 14 ... 2nd metal film 15 ... Multilayer metal film 16 ... Ceramic green sheet 17 ... Metal film integrated green Sheet 18 Ceramic laminated body 20 Sintered body 21 Multilayer capacitor 31 PET film (second support) 32 Ceramic green sheet 33 PET film (first support) 34 First metal film 35 ... second metal film 36 ... multilayer metal film 38 ... metal film integrated green sheet

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H05K 3/46 H01L 23/14 C (56) References JP-A-6-302469 (JP, A) JP-A-7-57961 ( JP, A) JP-A-3-116810 (JP, A) JP-A-6-232000 (JP, A) JP-A-1-226139 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) H01G 4/00-4/40 H01G 13/00-13/06

Claims (7)

(57) [Claims] A step of forming a first metal film on a support by a thin film forming method; and a step of forming a second metal film having a thickness larger than the first metal film partially on the first metal film. Forming a multi-layered metal film by forming a metal film according to a thin-film forming method, forming a ceramic laminate including the multi-layered metal film therein, and below a second metal film in the ceramic laminate. A first metal film portion that is not located in the ceramic laminated electronic component, wherein the component metal component is diffused into the ceramic to be an insulator, and the ceramic is fired. Production method. 2. The first metal film has a thickness of 100 nm or less, and the second metal film has a thickness of 300 nm or more and 1000 n or more.
The method for producing a ceramic multilayer electronic component according to claim 1, wherein the number is not more than m. 3. The step of converting the first metal film portion into an insulator and firing the ceramic is performed under an oxygen partial pressure at which the first metal film is oxidized and the second metal film is not oxidized. The method for producing a ceramic laminated electronic component according to claim 1, wherein the method is performed by firing. 4. The step of forming the multilayer metal film includes forming a resist layer having a pattern hole on the first metal film, and forming a first metal layer in the pattern hole of the resist layer. The method for manufacturing a ceramic multilayer electronic component according to claim 1, further comprising: forming a second metal film having a thickness greater than the thickness of the film by a thin film forming method; and removing the resist layer. . 5. The step of forming the ceramic laminate includes forming a ceramic green sheet on the multilayer metal film to obtain a metal film integrated green sheet, and laminating the metal film integrated green sheet. The method for manufacturing a ceramic laminated electronic component according to claim 1, comprising: 6. The step of forming the ceramic laminate includes forming a ceramic green sheet on a second support, and transferring a multilayer metal film supported by the support on the ceramic green sheet. The method according to any one of claims 1 to 4, further comprising: forming a metal film integrated green sheet; and sequentially stacking the plurality of the metal film integrated green sheets to obtain a ceramic laminate. 3. The method for producing a ceramic laminated electronic component according to 1.). 7. When transferring the multilayer metal film onto a ceramic green sheet, a roll press is used.
A method for manufacturing a ceramic multilayer electronic component according to claim 6.