JPH0666532B2 - Method for manufacturing glass-ceramic composite substrate - Google Patents

Description

Description: (a) Technical Field of the Invention The present invention relates to a method for manufacturing a wiring board in which ceramic particles and glass are uniformly dispersed.

(B) Background of technology In order to achieve high-speed and large-capacity information processing, ICs, LSIs and other semiconductor elements used in computers are becoming more integrated, and the unit elements that make them up are becoming smaller and smaller. Is being done.

For example, VLSI has been put to practical use as a method for increasing the degree of integration, and due to improvements in the passivation method for semiconductor elements, multiple semiconductor chips have been mounted on the heat-resistant substrate instead of the conventional hermetic exterior and replaced. As a unit, a mounting method of mounting on a printed wiring board is about to be adopted.

In addition, the unit elements that make up LSI and the like are becoming smaller and smaller, and the wiring pattern connecting the unit elements is being reduced to a width of about 100 μm.

As the degree of integration of semiconductor elements increases and miniaturization progresses in this way, it is necessary to improve the performance of the heat resistant substrate on which these semiconductor elements are mounted.

(C) Conventional technology and problems A multilayer wiring board is used for a wiring board on which a plurality of ICs, LSIs, and other semiconductor elements are mounted because the number of terminals of the semiconductor element is large. It is increasing in proportion to the degree of integration and the number of elements.

On the other hand, in a multilayer wiring board, the thickness of each layer provided with a wiring pattern tends to decrease in inverse proportion to the number of layers included.

Conventionally, a multilayer wiring board having alumina as a constituent material has been used as a board on which a semiconductor chip is mounted.

The reason is that the insulation resistance is high and the heat resistance is excellent.

However, such an alumina substrate has various problems when it is used as a multilayer, unlike a single layer.

In other words, the sintering temperature of alumina is extremely high at a few thousand hundreds of degrees,
Therefore, gold (Au, melting point 1064 ℃) and copper (Cu, melting point 1083), which have high electrical conductivity, are used as metal materials for forming the multilayer wiring pattern.
Can not be used.

Therefore, high melting point metals such as molybdenum (Mo) and tungsten (W) are used as metal materials having a high melting point and being difficult to oxidize.

However, as described above, when the wiring pattern width is reduced to about 100 μm, the conductor resistance becomes a problem, and it is necessary to use a conductor material having a lower value.

Next, the number of layers of the multi-layer wiring board increases, so that the distance between the wiring patterns becomes narrower, and when the upper and lower patterns intersect or run in parallel, crosstalk due to an increase in capacitance becomes a problem.

That is, the capacitance value is proportional to the size of the opposing electrode area and the dielectric constant of the dielectric material, and is inversely proportional to the distance between the electrodes.

Therefore, the capacitance increases as the thickness of the unit layer constituting the multilayer substrate decreases, and the amount of crosstalk increases due to the high frequency of the signal, which makes high-speed signal propagation difficult.

To solve such a problem, the substrate may be formed of a material having a low dielectric constant, a low baking temperature, and a high insulation resistance.

Therefore, research has been conducted on crystallized glass substrates, glass substrates in which ceramics are dispersed, etc. to meet this purpose.

For example, the dielectric constant of borosilicate glass is 4.1 to 6 which is lower than that of alumina 7, while the softening temperature is 600 to 800 ° C. which is much lower than that of ceramics such as alumina and magnesia.

Therefore, crystallized glass is used to improve the mechanical strength, the glass composition is selected and the firing temperature is set to about 1000 ° C, and ceramics such as alumina is mixed into the glass substrate to improve the mechanical strength. Is being studied.

However, a substrate suitable for a multilayer wiring substrate, such as a low dielectric constant, an appropriate firing temperature, excellent mechanical strength, and a small surface roughness, has not yet been put into practical use.

(D) Object of the Invention An object of the present invention is to provide a method for manufacturing a glass ceramic substrate in which ceramics are uniformly dispersed and which can be fired at a low temperature as a substrate suitable for high-density mounting of semiconductor elements. There is.

(E) Structure of the Invention The object of the present invention is to add ceramic powder to a mixed solution of boron alkoxide and silicon alkoxide, and in a suspended state, hydrolyze using the alkoxide method so that the surface of the ceramic powder is borosilicate. A step of forming a sludge-like precipitate covered with an oxide gel having a composition ratio corresponding to glass, and molding the sludge-like precipitate into a plate shape to remove water and a solvent to form a green sheet. A step of printing a wiring pattern on the green sheet to form a unit layer, a step of printing a glass paste on the unit layer and then laminating and integrating the layers, and firing the laminated body to form a glass ceramic multilayer substrate. This can be solved by configuring the method for manufacturing a glass-ceramic composite substrate, which is characterized by comprising the following steps:

(F) Example of the Invention The present invention uses a substrate having excellent mechanical strength and a low dielectric constant in which fine powder such as alumina is uniformly dispersed in glass having a low dielectric constant. As the oxide gel, an oxide gel produced by a hydrolysis reaction and a condensation reaction of a metal alkoxide is used.

Conventional glass refers to silicate glass, which is a silicate group that forms a network structure and is stabilized by copolymerization with groups of oxides such as boron and phosphorus, and has an amorphous structure with a glass transition point. Refers to something.

There is also a structure in which alkali-ion ions such as sodium and potassium and alkaline-earth ions such as calcium and magnesium enter in a stable manner in the polymerized silicic acid group having a network structure and are stabilized.

However, substrate materials that fulfill this purpose are limited to materials that have a low dielectric constant, high insulation resistance, and do not cause ionic conduction, and borosilicate glass is a material that meets the purpose at a softening temperature of 1000 ° C or less.

In the conventional method for producing glass, the above oxides are mixed and melted, and the melt is rapidly cooled to form glass.

However, apart from this method, a method has been developed in which a gel having an amorphous structure is formed by a solution reaction near room temperature, and this is heated to produce glass, which is a method in which a metal alkoxide having a metal-oxygen bond is in solution. It is a method of producing a gel having an oxide network structure by hydrolyzing and polymerizing with.

That is, in the chemical formula, M (OR) n, where M is a metal, R is an alkyl group, n is dependent on the valence of M, and a metal alkoxide solution represented by is hydrolyzed to form a compound having an MOM bond. As the reaction proceeds further, it polymerizes into a gel.

The gel is then turned into glass by heating at the corresponding glass transition temperature.

Speaking of a specific example of making a borosilicate glass, a boron alkoxide B (OC ₂ H ₅ ) ₃ solution and a silicon alkoxide S
It may be hydrolyzed by mixing with i (OC ₂ H ₅ ) ₄ solution, but usually hydrochloric acid (HCl) or ammonia (NH ₄ ) is used as a catalyst.
OH) is added, and alcohol (C ₂ H ₅ OH) is added as a reaction modifier and a viscosity modifier.

Here, the hydrolysis rate is not always constant when the type of metal alkoxide is different, but in the case of approximating as in the case of this example, a gel having a B--O--Si--O bond is formed, which has a glass transition point. It is known that glass can be made by heating at a temperature in the vicinity. It is known that the glass thus produced has the same physical properties as those produced by the melting method, such as thermal expansion coefficient and density. There is.

According to the present invention, the particle size of the gel oxide thus produced is extremely small, 1 μm or less, and is uniformly mixed in the glass composition ratio. Therefore, in comparison with the conventional oxide powder mixed. Attention was paid to the fact that glass with a uniform composition can be produced by firing at a much lower temperature. Then, by mixing ceramic powder such as alumina together when hydrolyzing a condensation reaction by mixing multiple types of alkoxide mixed solutions, a ceramic slurry covered with oxides with a glass composition ratio is obtained. Is.

The ceramic sludge treated in this way is molded into a substrate, pressure-molded at 100 to 200 ° C to evaporate water and solvent, and then the wiring pattern is formed using Au or Cu conductor paste. The formation of layers is complete.

Next, the plurality of unit layers made in this way use glass paste as a binder, apply thinly by screen printing method, align accurately, pressurize and integrate and then fire to make the ceramic powder uniform. A dispersed glass multilayer substrate can be obtained.

Examples will be described below.

Alumina crushed to a particle size of several μm is used as ceramics, while borosilicate glass is used as glass, which is an alkoxide of boron and silicon, that is, B (OC ₂ H ₅ )
₃ Si (OC ₂ H ₅ ) ₄ was mixed at a weight ratio of 2: 5 and hydrolyzed using hydrochloric acid as a catalyst to produce alumina coated with BO and SiO.

Here, the weight ratio of alumina to oxide was about 1: 1.

The sludge-like alumina thus obtained is allowed to undergo a reaction until it becomes easy to mold, then it is heated to evaporate the solvent, then put in a mold and molded at 150 ° C. under a pressure of 20 MPa. Make a sheet, make a wiring pattern using Au paste, print the glass paste on the surface of the sheet, press it with the same pressure as before to integrate it, and then at 900 ℃ 2
A multilayer substrate can be obtained by firing for a time.

The composite permittivity of the substrate is 5.5 and the surface roughness is 4
was μm.

(G) Effects of the Invention The present invention has been made for the purpose of putting into practical use a multilayer substrate having a low dielectric constant, a low firing temperature, and an excellent mechanical strength. By carrying out the present invention, a ceramic powder such as alumina is uniformly dispersed. In addition, since the oxide fine powder having the glass component ratio is uniformly dispersed, the same glass as that melted at a high temperature can be obtained despite the low firing temperature.

As described above, by carrying out the present invention, it is possible to form a wiring pattern using a material having a good dielectric constant such as gold or copper, and to form a substrate having excellent electrical and mechanical properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location C03C 8/02 14/00 H01B 3/02 A 9059-5G (72) Inventor Koichi Niwa Kawasaki, Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, Ichi, Fujitsu Limited (56) References JP-A-49-37910 (JP, A) JP-A-59-26966 (JP, A) JP-A-57-175724 (JP, A)

Claims (1)

[Claims] 1. A composition in which ceramic powder is added to a mixed solution of boron alkoxide and silicon alkoxide, and the resulting suspension is hydrolyzed by the alkoxide method, and the surface of the ceramic powder corresponds to borosilicate glass. A step of forming a sludge-like precipitate covered with an oxide gel having a specific ratio, forming a green sheet by molding the sludge-like precipitate into a plate shape and removing water and a solvent, and wiring the green sheet. A step of printing a pattern to form a unit layer, a step of printing a glass paste on the unit layer, then laminating and pressurizing to integrate the laminated body, and a melting point of metal powder forming the wiring pattern. A step of firing at a lower temperature to form a glass-ceramic multilayer circuit board made of a composite of glass and ceramics. Build method.