JP2002016364A - Capacitor-containing ceramic multilayer board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress characteristics from deteriorating due to the mutual reaction of a ceramic multilayer wiring board with a sintering atmosphere and process it to contain fine capacitors at a high positional accuracy. SOLUTION: Fine capacitors each composed of an electrode foil held on a film and a dielectric on the electrode and a counter electrode are formed. The capacitor has a structure sealed at the side faces with an atmosphere sealing material. The capacitors are positioned and transferred to green sheets, and they are sintered after laminating and compression bonding them. Thus a multilayer board containing the capacitors is manufactured at a high positional accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circuit board suitable for forming a functional module having a built-in capacitor for preventing malfunction of a semiconductor due to external noise and unnecessary radiation, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor device housing package, a semiconductor integrated circuit is liable to malfunction due to external noise or unnecessary radiation. For example, a large-sized computer has a ceramic capacitor having a capacitance of about 10 nF between a power supply side and a ground side. By inserting between them, noise was absorbed and malfunction was prevented. Conventionally, this capacitor was connected externally separately from the package. However, conventionally, as described above, a ceramic capacitor for preventing malfunction due to extraneous noise or unnecessary radiation is externally attached, so that the mounting density of a substrate or a package cannot be improved.

Therefore, as a method for improving the mounting density of a substrate or a package, there is a method of forming a capacitor in a substrate and incorporating the capacitor therein. Hitherto, as a ceramic multilayer substrate which has been provided with this kind of noise countermeasure, a ceramic multilayer substrate in which a capacitor portion is formed below a ceramic multilayer substrate has been proposed (Japanese Patent Application Laid-Open No. 59-145536).

A method of manufacturing a ceramic multilayer circuit board having such a built-in capacitor is disclosed in Japanese Patent Application Laid-Open No. 9-9298.
No. 3 and JP-A-9-139578. The former prints conductor paste and dielectric paste on green sheets,
The latter is a method in which a conductor paste is printed on a green sheet to form an electrode, a dielectric green sheet is sandwiched, laminated and pressed, and simultaneously sintered to form a ceramic multilayer circuit board with a built-in capacitor.

However, since the ceramic material as the substrate material and the dielectric material forming the capacitor have different compositions and different firing shrinkage characteristics, when both are laminated and fired simultaneously, the substrate shrinks due to the difference in firing shrinkage characteristics. Warpage, cracks and distortion are likely to occur. Further, when the sintering end temperature of the ceramic material does not match the sintering end temperature of the dielectric material, the density of the sintered layer of either material is reduced. In this case, when the denseness of the sintered layer of the ceramic material is reduced, the insulation characteristics between the wiring conductors in the substrate are reduced, and the mechanical strength of the ceramic insulating portion is significantly reduced.
Conversely, when the denseness of the sintered layer of the dielectric material decreases, the insulating properties and the dielectric constant of the dielectric of the capacitor decrease. Furthermore, a dielectric material having a sintering temperature equal to or higher than the melting point of the conductor metal cannot be used. For example, the melting point is 108
In the case of a copper / glass ceramic substrate using copper at 3 ° C. as a conductor, it is impossible to use PZT, which requires a high temperature of about 1200 ° C. for sintering, as a dielectric.

The capacitance C of the capacitor is determined by the capacitor area S (m2), the dielectric constant εs of the dielectric, and the dielectric constant ε0 of the vacuum.
(F / m) From the dielectric thickness t (m), it is given by C = εsε0S / t. Therefore, in order to miniaturize the capacitor, it is necessary to use a dielectric having a high dielectric constant or to reduce the thickness of the dielectric. For example, a 1 mm square capacitor, C = 10n
In order to obtain F, the dielectric thickness t must be 1.13 μm even if a dielectric having a relative permittivity ε = 1000 is used. However, in the above-mentioned conventional green sheet method, the thickness of the green sheet is required to be several tens μm or more in order to obtain a strength that does not cause a problem such as breakage during handling. It is difficult to do. In addition, the dielectric paste method can reduce the dielectric thickness compared to the green sheet method, but the thinner the printed film thickness, the more blurred the print or pinholes, and the more likely it is that short circuits will occur after sintering. There is.

However, a defect such as a short circuit of the formed capacitor cannot be evaluated until the sintering is completed, which causes an increase in manufacturing cost.

Therefore, the capacitor is fired in advance,
As a method of sandwiching the fired capacitor between green sheets and sintering under pressure, there is a method disclosed in JP-A-5-163072.

[0009]

However, in order to increase the number of terminals of the semiconductor element and increase the mounting density of the semiconductor element on the substrate with the increase in the density of circuits on the semiconductor element, it is necessary to reduce the size of the capacitor. In addition to this, it is necessary to incorporate a fine capacitor into the substrate with high positional accuracy. Furthermore, in the above-mentioned conventional technology, it is necessary to prevent the conductive metal from being oxidized during sintering. However, in such an atmosphere, the characteristics of the dielectric may be deteriorated. For example, the dielectric properties of a lead-based dielectric material such as PZT generally deteriorate significantly when fired in a non-oxidizing atmosphere.

In order to solve the above-mentioned problems of the prior art, the present invention makes it possible to miniaturize a capacitor, remove defects beforehand, and manufacture a ceramic multilayer wiring board with a built-in capacitor that suppresses the influence of the atmosphere during firing. The method was developed. In this method, an electrode foil previously held on a film, a dielectric and a counter electrode on the electrode, and a capacitor having a structure in which the side surfaces are sealed with an atmosphere sealing material are collectively created, and the capacitors are aligned. This is a method of producing a multilayer substrate with a built-in capacitor by transferring the image to a green sheet, sintering after laminating and pressing.

[0011]

Means for Solving the Problems As a result of studying these problems, the present inventors formed a dielectric layer on a metal foil held on a film, and formed an electrode on the dielectric layer. Then, the side surface of the dielectric layer is made of, for example, alumina (Al2O3)
By evaluating the characteristics of the capacitor manufactured by sealing with a sealing material such as a high melting point oxide such as magnesia (MgO) silica (SiO2), aligning, transferring to a green sheet, and performing lamination sintering, By arranging a large number of fine capacitors having desired characteristics in a substrate with high positional accuracy, it has been found that malfunction of a semiconductor element due to external noise and unnecessary radiation can be prevented, and the present invention has been accomplished.

The dielectric layer, electrode and seal layer are formed by electron beam evaporation, activated reactive evaporation (ARE), sputtering, cluster ion beam (ICB), ion beam sputtering (IBS), and chemical vapor deposition. Growth (CVD), atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source (MBE or CB)
It can be formed in a vacuum or under various control atmospheres by using a known crystal growth technique such as E), electron cyclotron resonance (ECR) or the like, and an amorphous thin film forming technique.

The pattern formation of the capacitor may be performed at any timing according to the material of the capacitor and the forming conditions. For example, a metal foil held on a film is patterned by a photoetch method, and then a dielectric layer,
A counter electrode, a dielectric layer, an atmosphere sealing layer on the side surface is formed, a dielectric layer is formed, and then a pattern is formed by etching using the dielectric layer as a mask, and a counter electrode, a dielectric layer, and a side surface are formed. After forming the entire atmosphere sealing layer, it is possible to form a pattern by a photoetching method.

In addition to forming a dielectric crystal directly on the electrode, the dielectric layer also forms an amorphous film having the same composition, and the heat history and sintering profile at the time of sintering cause the crystallization of the amorphous film. It is possible to obtain a dielectric layer having a high dielectric constant by crystallizing by incorporating steps.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 As shown in FIG. 1, a method for manufacturing a glass ceramic multilayer wiring board is as follows. First, a lead β-diketone complex Pb (C11H19O2) 2 and Zr (Ot-C4H) are formed on a copper foil 1 having a thickness of 9 μm.
9) Using 4Ti (OiC3H7) and O2 as raw materials,
A PZT dielectric layer 2 having a desired pattern with a total pressure of 660 Pa and a thickness of 1 μm at 620 ° C. is formed by MOCVD.

Next, a Cu counter electrode 3 is formed.
A side atmosphere sealing layer 4 of gO is formed by using a plasma sputtering method.

Next, using a thermoplastic film 6 having a softening temperature of 200 ° C. on a polyester film 5 having a thickness of 200 μm, the copper foil is held at 200 ° C. at 10 kg / cm 2 for 30 minutes and thermocompression-bonded.

Next, an excess copper foil portion is removed by photoetching to form an electrode pattern. When this electrode pattern was formed into a shape having a capacitor electrode portion and an extraction electrode for evaluating the characteristics at the end thereof, the formed capacitor was easily evaluated.

Next, the electric capacity of the formed capacitor was measured, and the short-circuit failure and the capacitor whose electric capacity was 10 nF or less were mechanically removed.

Next, a slurry for forming a green sheet is prepared.

The slurry is prepared by adding 37 parts by weight of mullite particles having an average particle diameter of 3 μm and 17 parts by weight of an acrylic binder to 63 parts by weight of borosilicate glass powder having an average particle diameter of 3 μm and a softening temperature of 820 ° C., and wet-mixing with a ball mill for 24 hours. To make.

Next, the viscosity is adjusted appropriately by vacuum degassing.
Next, this slurry was applied on a polyester film to a thickness of 0.5 μm using a doctor blade and then dried to produce a green sheet.

Next, the green sheet is punched with a diameter of 1 mm.
Holes of 60 μm were drilled at 450 μm intervals, copper paste was printed and filled, and a surface layer, a power supply layer, and a wiring layer were formed by printing the copper paste.

The copper paste is a reduced copper powder 1 having an average particle size of 3 μm.
10 parts by weight of ethyl cellulose as a binder and 90 parts by weight of a solvent were added to 00 parts by weight, and 10 parts by weight of a vehicle prepared was added thereto.
The roll was kneaded several times, kneaded and adjusted to an appropriate viscosity, and then filled and printed.

Of the green sheets thus prepared, the green sheet on which the capacitor is mounted and the polyester film on which the capacitor has been evaluated after the evaluation of the electrical characteristics have been completed are aligned at 200.degree.
After holding at 0 kg / cm 2 for 30 minutes and thermocompression bonding, the polyester film is peeled off and the capacitor is transferred to a green sheet. If there is a defective capacitor that has been removed, the capacitor manufactured in the same manner is further transferred to the defective portion.

After aligning 50 sheets of the green sheets thus prepared, they were pressed by a hot press. The pressure bonding was performed at a temperature of 130 ° C. and a pressure of 150 kgf / cm 2.

The pressed green sheet is degreased to obtain 1
The temperature was raised at a temperature rising rate of 00 ° C./h or less and maintained at 850 ° C. for 10 hours. The atmosphere was an N2 + H2O + H2 atmosphere in which binder carbon could be removed and copper was not oxidized. After that, the atmosphere was switched to N2 at 1000 ° C for 2 hours.
Hold and sinter densify. During sintering, 2k is used to control the warpage of the substrate and to control the shrinkage of the substrate in the X and Y directions.
Pressure was applied at gf / cm2.

After replacing the conductive pads on the back surface of the ceramic multilayer circuit board thus prepared with AuSn solder, the CuZr electrical signal input / output pins are brazed to the 1.6 mm diameter conductive pads, and then the LSI is mounted. When the chip was mounted with the solder 8, good operating characteristics could be obtained. FIG. 2 shows a schematic diagram of the module manufactured in this manner.

Example 2 Polyester film having a thickness of 200 μm and softening temperature 2
A thermoplastic film at 00 ° C. and a copper foil with a thickness of 18 μm are overlaid, held at 200 ° C. at 10 kg / cm 2 for 30 minutes, and thermocompression bonded.

Next, a photo-etching process is performed to form a capacitor electrode pattern. Next, an amorphous thin film layer having a PZT composition having a thickness of 1 μm is formed on the electrode by sputtering. Next, similarly, a counter electrode of Cu is formed on the amorphous thin film layer by sputtering. Next, an MgO side atmosphere sealing layer is similarly formed on the side surface of the formed capacitor by sputtering.

Next, after the capacitor was evaluated for short-circuit failure, it was transferred to a green sheet under the conditions shown in Example 1.
Lamination, pressure bonding, and sintering were performed. PZ with low dielectric constant at the beginning
The amorphous thin film layer having the T composition crystallized during the sintering process, and became a PZT crystal layer having a high dielectric constant. Thus, capacitor characteristics equivalent to those of Example 1 were obtained.

[0033]

According to the present invention, a large amount of fine capacitors can be built in the substrate with high positional accuracy, and the side surfaces of the dielectric are protected by an atmosphere sealing layer, and the upper and lower surfaces are protected by dense electrode metals, thereby achieving a sintering atmosphere. The degradation of the dielectric characteristics due to the interaction with the substrate can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a capacitor forming process.

FIG. 2 is a schematic cross-sectional view of a glass ceramic multilayer circuit board showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Copper foil, 2 ... dielectric layer, 3 ... counter electrode, 4 ... side atmosphere sealing layer, 5 ... polyester film, 6 ... thermoplastic adhesive film, 7 ... green sheet, 8 ... through hole, 9 ... solder, 10: power supply layer, 11: glass ceramic, 12: connection pad.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01G 4/30 301 H01G 4/30 311F 311 C23C 14/08 J // C23C 14/08 14/34 A14 / 34 16/18 16/18 H01G 1/035 E (72) Inventor Nobuhito Katsumura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref.Hitachi, Ltd.Production Technology Research Laboratory, Hitachi, Ltd. (72) Inventor Bunichi Tagami Hatano, Kanagawa Prefecture No. 1 Ichihori Yamashita F-term (reference) 4K029 AA02 AA04 AA25 BA43 BA46 BC05 CA05 DC05 4K030 AA11 BA42 BB12 CA02 HA03 LA02 5E001 AB03 AC09 AE00 AE03 AG00 AH03 AH05 AH01 AJ01 AB02 BC40 EE03 EE23 EE41 FG26 FG27 FG42 FG54 HH43 JJ15 JJ23 LL02 MM22 MM24 5E346 CC16 CC32 DD04 DD15 DD44 EE13 EE23 EE29 FF45 GG09 GG18 GG19 GG28 HH01

Claims (5)

[Claims] 1. A dielectric layer is formed on a metal foil held on a film, a counter electrode is formed on the dielectric layer, and a side surface of the dielectric layer is formed of a high melting point oxide such as alumina (Al2O3) magnesia (MgO) silica (SiO2). A ceramic multilayer substrate with a built-in capacitor, which is manufactured by sealing with a sealing material, transferring to a green sheet, laminating and pressing, and sintering. 2. The method of manufacturing a ceramic multilayer substrate with a built-in capacitor according to claim 1. 3. A dielectric layer is formed on a metal foil held on a film, a counter electrode is formed on the dielectric layer, and a side surface of the dielectric layer is formed of a high melting point oxide such as alumina (Al2O3) magnesia (MgO) silica (SiO2). A capacitor characterized by being manufactured by sealing with a sealing material. 4. A method for manufacturing a capacitor according to claim 3. 5. A green sheet on which the capacitor according to claim 3 is transferred.