JPH04283946A - Forming method of minute wiring pattern on ceramic green sheet - Google Patents

Abstract

PURPOSE:To form a minute wiring pattern on a ceramic green sheet. CONSTITUTION:A photoresist 2 constituted of photosensitive resin is applied by coating on a green sheet 1 constituted of ceramic powder for a multilayer wiring board and then exposure and development are conducted, so as to form a desired photoresist pattern. A conductor paste 3 is filled up in a recession formed thereby and the photoresist 2 is removed thereafter. Thereby a very minute wiring pattern is formed on the ceramic green sheet 1 for the multilayer wiring board.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramic multilayer wiring board for mounting high-speed LSI devices.

0002

[Prior Art] Conventionally, semiconductor devices such as ICs and LSIs are
They were mounted on printed circuit boards such as glass epoxy or alumina ceramic substrates, but as semiconductor devices become more highly integrated, finer, and faster, mounting substrates are also becoming more densely wired and have faster transmission speeds. , demands for higher frequencies and higher heat dissipation have increased.

Conventional printed circuit boards have problems such as through-hole plating, workability, multilayer adhesion, and thermal deformation at high temperatures, and there is a limit to their ability to increase density. Therefore, as a high-density mounting board, it has not yet been put into practical use, and ceramic boards have more potential.

[0004] However, since the alumina substrate must also be sintered at a high temperature of 1500°C or higher, the wiring conductor materials to be co-fired are limited to high melting point metals such as W and Mo, which have relatively high resistivity. . Therefore, if the transmission loss of the pulse signal is taken into account, there is a limit to the miniaturization of the wiring pattern.

On the other hand, for high-speed transmission, it is essential to lower the dielectric constant of the substrate material because the propagation delay time of the pulse signal is proportional to the square root of the dielectric constant of the substrate material. However, the alumina substrate has a relatively high dielectric constant of about 10.

[0006] Therefore, a low temperature sinterable multilayer ceramic substrate was developed. Insulating materials include ceramic-glass composite materials and crystallized glass, but since all of them are sintered at temperatures below 1000°C, materials such as Au, Ag-Pd, and Cu, which have low specific resistance, are used as wiring conductor materials. Low melting point metals can be used. Furthermore, by selecting a low dielectric constant ceramic or glass, it is possible to lower the dielectric constant of the insulating material to 5 or less. Furthermore, since a green sheet multilayering method can be used, three-dimensional wiring is possible, which is very advantageous for increasing density.

[0007]

[Problems to be Solved by the Invention] However, the formation of wiring patterns in the green sheet multilayer method is generally performed by thick film screen printing, and at a mass production level, the line and space width is limited to 75 μm. , new methods and structures are required for finer wiring.

[0008] Therefore, an object of the present invention is to solve such conventional problems by creating a fine wiring pattern on a green sheet made of ceramic powder, which can realize high-density and fine wiring even on a ceramic multilayer wiring board. The object of the present invention is to provide a method for forming the same.

[0009]

[Means for Solving the Problems] In order to achieve the above object, a method for forming a fine wiring pattern on a ceramic green sheet according to the present invention includes a pattern forming step, an embedding step, and a removing step. A method for forming a fine wiring pattern, the pattern forming step is a step of coating a green sheet containing ceramic powder with a photoresist made of a photosensitive resin, and then exposing and developing it to form a desired photoresist pattern. The embedding step is a step of embedding a conductor into the recess formed by the photoresist pattern, and the removal step is a step of removing the photoresist pattern.

0010

[Operation] In recent years, multilayer ceramic wiring boards are formed by the following green sheet lamination method. That is, a vehicle is added to ceramic powder and mixed, thoroughly kneaded using a high-speed mixer or ball mill, etc., and uniformly dispersed to prepare a slurry, which is then used to form a green film with a thickness suitable for forming an insulating layer by slip casting. Make it a sheet. It should be noted that organic vehicles such as binders and solvents that are commonly used are sufficient, and there is no need to limit the components in any way.

Next, through holes connecting the upper and lower conductors are formed in the sheet, and the conductor is printed or printed so that the through holes are filled with conductive paste. Furthermore, these are laminated and thermocompressed to form a desired multilayer structure. After removing the organic vehicle added during molding, it is fired to obtain a multilayer ceramic wiring board.

[0012] In the present invention, when forming a conductor wiring, a photoresist made of a photosensitive resin is first coated on a green sheet (see FIG. 1(a)), and then exposed and developed to form a desired photoresist pattern. form (Figure 1(b)
)reference).

Photosensitive resins mainly include photopolymerizable, photocrosslinkable, and photodegradable types. Photopolymerizable oligomers and monomers include acryloyl groups (CH2=CH-CO-
), methacryloyl group (CH2=C(CH3)-CO-
), vinyl ether group (CH2=CH=O-), vinyl group (CH2=CH-), allyl group (CH2=CH-CH
It is made of a polyfunctional group containing two or more of 2-), and specific compounds include pentaerythritol triacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, and ethylene glycol acrylate. Furthermore, pendant linear polymers having a functional group of an unsaturated monomer in a side chain are also included.

As the photopolymerization initiator, benzoin and benzoin derivatives such as benzoin alkyl ethers, benzyl, benzophenone and derivatives thereof, alkylanthraquinone, acetophenone derivative, chlorinated acetonephenone derivative, etc. are used. In order to obtain a predetermined resolution as a photosensitive resin, in addition to the above components, polymerization inhibitors such as hydroquinone and methylhydroquinone, adhesives such as oil blue, methylene blue, crystal violet, and oil yellow are also added.

On the other hand, the photo-crosslinkable type includes systems in which cyclized polyisoprene rubber or butadiene rubber is mixed with hisazide or azidopyrene, and systems in which an acrylic acid polymer and a water-soluble bisamide such as stilbendiazide sulfonate are mixed. .

Furthermore, photodegradable materials include quinone azide-based materials such as orthonaphthoquinodiazide and nitro compound-based materials. It can be blended with acrylic soluble resins such as polymers, combined with polymers such as phenol novolak, or mixtures thereof.

Furthermore, dry development type resins are particularly effective in forming fine patterns.

The developer contains, depending on the type of photosensitive resin,
There are organic solvents such as ketone, xylene, ester, and chlorine, and alkaline aqueous solutions or water such as sodium carbonate, sodium hydroxide, and potassium hydroxide, but if they destroy the organic binder of the ceramic green sheet. Therefore, sufficient care must be taken in its selection.

In the manufacturing method of the present invention, a conductor is then embedded in the recesses formed by the photoresist pattern (see FIG. 1(c)).

As a conductor, tungsten, molybdenum, etc. are used for ceramics such as alumina and mullite whose sintering temperature exceeds 1000°C, and gold is used for low-temperature sinterable ceramics such as glass ceramics and crystallized glass whose sintering temperature is 1000°C or less. , silver or silver-palladium, copper, nickel, etc. are used.

[0021] These pastes are applied onto a ceramic green sheet, and filled in the recesses formed by the photoresist pattern using an ordinary printing machine.

Furthermore, in the present invention, the photoresist pattern is removed (see FIG. 1(d)). The photoresist is removed using the same developer as before, but since it is hardened by exposure, it is necessary to change the conditions, such as the development time, slightly.

In this way, a fine wiring pattern corresponding to the recesses of the photoresist pattern is formed on the ceramic green sheet.

[0024]

EXAMPLES Next, the present invention will be explained in detail using examples.

(Example 1) As Example 1 of the present invention, a two-component ceramic composition containing 55% by weight of alumina and 45% by weight of borosilicate lead glass was used as a ceramic raw material, and a photocrosslinkable photosensitive resin was used as a ceramic raw material. The case where this is used as a photoresist will be described.

[0026] The above ceramic composition has an average particle size of 1.0
Mix alumina powder of μm and borosilicate lead glass of 2.0 μm to the target composition, and use a ball mill etc. to
Mix for an hour to obtain a homogeneous mixed powder. Note that this composition can be sintered at a low temperature of about 900° C., so a low resistance material such as gold, silver, or silver-palladium, which has a low melting point, can be used as the conductor.

The above ceramic mixed powder is sufficiently mixed and dispersed with an organic vehicle (binder, plasticizer, solvent, etc.) using a high-speed mixer, a ball mill, etc., to form a slurry. Furthermore, from the slurry that has been sufficiently defoamed, a green sheet having a desired thickness is produced on a carrier film made of polyester or the like by slip casting.

On the other hand, a mixture of photocrosslinkable modified polyvinyl alcohol and diazonium salt was used as the photosensitive resin. The photosensitive resin, ie, the photoresist 2, was uniformly coated onto the ceramic green sheet 1 to a predetermined thickness (FIG. 1(a)). A photomask having a predetermined pattern formed thereon is brought into close contact with the photoresist 2 and exposed to light. In addition, the exposure was 3kW.
This was carried out for 1 minute using an ultra-high pressure mercury lamp. Furthermore, spray development with water (pressure 3 kg/cm2) was performed for 1 minute to form the desired photoresist pattern (Figure 1
(b)). Note that the pattern width can be up to 10 μm and the pitch width can be up to 20 μm, but this time we prototyped 85 μm & 30 μm.

A conductive paste 3 consisting of 95% by weight of silver and 5% by weight of palladium was applied onto the green sheet on which the photoresist pattern was formed by the above method, and was embedded in the recesses of the photoresist pattern using a printing machine (see Fig. 1
(c)). The organic component ratio in the paste is 15% by weight, and the remainder contains additives such as glass frit and metal oxides in addition to silver and palladium, and the viscosity is 4.
It is adjusted to about 00 to 500 cp. In addition, the embedding conditions are a printing pressure of 3 kg/cm2 and a speed of approximately 1.
0s/100mm, and other factors such as the rubber hardness of the squeegee and the contact angle were also taken into consideration.

Next, spray development with water (pressure 3k)
g/cm〓2〓) for 4 minutes, the photoresist pattern was removed and dried at 80°C for 10 minutes (Figure 1
(d)).

[0031] As a result, the line width is 30 μm and the line spacing is 8
A very fine wiring pattern of 5 μm and 15 μm in thickness was formed on the green sheet.

[0032] When the green sheets are laminated and thermocompressed to obtain the desired structure, and then the binder is removed and fired, the line width is approximately 25 μm, the line spacing is approximately 75 μm, and the thickness is approximately 10 μm.
Since it shrinks up to m, high-density and fine wiring becomes possible.

(Example 2) As Example 2 of the present invention, 15% by weight of quartz glass and 20% by weight of cordierite were used.
A case will be described in which a three-component ceramic composition containing 65% by weight of borosilicate glass is used as a ceramic raw material, and a photopolymerizable photosensitive resin is used as a photoresist.

[0034] The above ceramic composition has an average particle size of 3.7.
Quartz glass powder of .mu.m, cordierite powder of 2.6 .mu.m, and borosilicate glass of 2.0 .mu.m are blended to a target composition and mixed for 1 to 3 hours using a ball mill or the like to obtain a homogeneous mixed powder. This composition can also be sintered at a low temperature of about 900°C, so gold, which has a low melting point, can be used as a conductor.
Low resistance materials such as silver or silver-palladium, copper or nickel can be used. Further, a green sheet having a desired thickness is produced from the above ceramic mixed powder in the same manner as in Example 1 of the present invention.

On the other hand, as the photosensitive resin, triethylene glycol acrylate, benzoin propyl ether,
A photopolymerizable type consisting of ethyl anthraquinone as a polymerization inhibitor and Orlu Blue as a coloring agent was used. In addition,
Exposure was carried out for 1 minute using a 3 kW ultra-high pressure mercury lamp, and development was carried out using methyl ethyl ketone spray development (pressure 1 k).
g/cm2) for 1 minute. Furthermore, gold paste was used as the conductor.

The hardened photoresist pattern filled with the conductor was removed by spray development with methyl ethyl ketone (pressure 1 kg/cm 2 ) for 4 minutes.

[0037] As a result, the line width is 20 μm and the line spacing is 2
A very fine wiring pattern with a thickness of 0 μm and a thickness of 20 μm was formed on the green sheet.

[0038] When the green sheets are laminated and thermocompressed to form the desired structure, and then the binder is removed and baked, the line width shrinks to approximately 17 μm, the line spacing to 17 μm, and the thickness to approximately 15 μm, resulting in a very high This enables high-density and fine wiring.

[0039]

[Effects of the Invention] As explained above, by using the method of forming fine wiring patterns on ceramic green sheets for multilayer wiring boards of the present invention, fine wiring with line width, line spacing, and thickness of 20 μm can be formed on green sheets. This makes it possible to provide a mounting board compatible with higher density and higher speed LSI elements.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a process flow diagram of a method for forming a fine wiring pattern on a ceramic green sheet for a multilayer wiring board according to the present invention.

[Explanation of symbols]

1 Ceramic green sheet 2 Photoresist 3 Conductor paste

Claims (1)

[Claims] 1. A method for forming a fine wiring pattern comprising a pattern forming step, a embedding step, and a removing step, the pattern forming step is to form a photoresist made of a photosensitive resin on a green sheet containing ceramic powder. After coating, a desired photoresist pattern is formed by exposure and development.The embedding process is a process of embedding a conductor in the recesses formed by the photoresist pattern, and the removal process is a process of embedding the conductor in the recesses formed by the photoresist pattern. 1. A method for forming a fine wiring pattern on a ceramic green sheet, the method being a step of removing.