JPH04130052A - Starting material composition for ceramic substrate and production of substrate using the same - Google Patents

Abstract

PURPOSE:To obtain a ceramic substrate having a low dielectric constant and a coefft. of thermal expansion close to that of a semiconductor device by calcin ing at a low temp. by mixing borosilicate glass powder with aluminum borosilicate powder in a specified ratio. CONSTITUTION:A starting material compsn. for a ceramic substrate is obtd. by mixing 40-80wt.% borosilicate glass powder of <=3mum average particle size consisting of, by weight, 65-85% SiO2, 5-25% B2O2, 0.1-7% one or more among Li2O, Na2O and K2O, 0.1-5% MgO and/or CaO and 0.1-5% AlO3 with 20-60wt.% aluminum borosilicate powder of <=3mum average particle size. The compsn. is mixed with water and/or an org. vehicle and molded into green sheets of a prescribed thickness and these sheets are laminated and calcined 90-1,000 deg.C to obtain a substrate.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to semiconductor devices, particularly large-scale integrated circuit devices arranged in
Regarding a raw material composition for a ceramic substrate that is useful as a substrate for multilayer wiring to be mounted, the firing temperature is lower than the firing temperature during manufacturing of a substrate made of alumina, specifically, 1,000°. The present invention relates to a raw material composition for a ceramic substrate that can be fired at a low temperature of C or less, has a small dielectric constant, and has a coefficient of thermal expansion close to that of silicon.

[Prior Art] Generally, increasing the speed of LSI requires increasing the signal transmission speed, and for this purpose, it is necessary to reduce the dielectric constant as a property of the substrate itself. Furthermore, in order to reduce the incidence of poor connection between substrate wiring and semiconductor elements, it is required to provide a substrate having a coefficient of thermal expansion close to that of the semiconductor element. Furthermore, a method is known in which a ceramic substrate having three-dimensional wiring built therein is manufactured by laminating thin plate-like substrates to which metal for wiring is attached by printing or the like, and integrating the laminated substrates by firing them.

Initially, alumina was used as a raw material for manufacturing substrates for such purposes, but since the firing temperature of alumina is as high as 1,500°C, silver-palladium (AgPd) was used as a wiring metal. ), silver (Ag), gold (A
u), conductors with low melting point and low resistance such as copper (Cu) cannot be used, and high melting point conductors such as molybdenum (Mo) and tungsten (W) cannot be used.
Conductors such as are used. However, these high-melting-point conductors have a high conductor resistance, and the dielectric constant of alumina itself is as high as 9 to 10, so that they are no longer compatible with high-speed LSIs. Also, the thermal expansion coefficient of alumina is 75×1
0-6/°C, which is large compared to the thermal expansion coefficient of the semiconductor element (e.g., 3.5 x 10" 67°C for silicon), so there may be problems such as a high rate of connection failure with the semiconductor element. In order to solve these problems, the use of low-resistance conductors such as Ag-Pd, Ag, Au, and Cu, and the supply of raw material compositions for substrates that can be laminated and co-fired at low temperatures have been developed. In order to meet these demands, a composition comprising zinc oxide borate glass, silicon oxide, and alumina, which has a low dielectric constant and can be fired at a low temperature (Japanese Patent Application Laid-Open No. 138357/1982); Glass powder and cordierite (2Mg0・2A1203・5Si○2),
Compositions of crystal or quartz glass (Japanese Patent Application Laid-open No. 63-649
57, JP-A-63-74957), a glass composition that crystallizes during firing, and a composition of alumina and cordierite (
Japanese Unexamined Patent Publication No. 1-95402) is known.

However, although the above-mentioned conventional compositions satisfy the requirements that the product has a low dielectric constant and can be fired at low temperatures, they do not meet the requirements of lowering the dielectric constant and matching the coefficient of thermal expansion to that of the semiconductor element. At the same time, it is not satisfying.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned problems, and allows the use of low-resistance conductors such as Ag-Pd, Ag, Au, Cu, etc., and enables substrate manufacturing by low-temperature firing. The present invention provides a raw material composition for a ceramic substrate, the product of which has a low dielectric constant and a coefficient of thermal expansion close to that of a semiconductor device.

[Means for Solving the Problems] As a result of preparing and repeatedly studying various compositions for raw material compositions for ceramic substrates, the present inventors found that borosilicate glass powder and aluminum borate powder were combined into specific materials. A composition in which a borosilicate glass powder, an aluminum borate powder, and a specific oxide are mixed in a specific ratio is a low-resistance conductor such as Ag-Pd, Ag
, Au, Cu, etc., can be fired at low temperatures, and can produce a ceramic substrate having a low dielectric constant and a coefficient of thermal expansion close to that of a semiconductor element, and has completed the present invention.

That is, the present invention uses borosilicate glass powder in a range of 40 to 80% by weight and aluminum borate powder in a range of 20 to 80% by weight.
A raw material composition for a ceramic substrate, characterized in that it is a mixture containing within a range of 60% by weight, and this raw material composition is mixed with water and/or an organic vehicle, and formed into a green sheet of a predetermined thickness. This method of manufacturing a ceramic substrate is characterized in that a circuit is then formed in accordance with the desired product shape and properties, and the laminated product is fired at a temperature of 900 to 1,000°C.

In the present invention, the borosilicate glass powder preferably has the following composition.

That is, on a weight basis, (1) silicon dioxide (S 1
02) 65-85%, (2) boric anhydride (B20.
) 5-25%, (3) Lithium oxide Li20), sodium oxide (Na20) and potassium oxide (K2 o)
One or more ingredients selected from the group consisting of 0.1-7%
, (4) 0.1 to 5% of at least one component selected from the group consisting of magnesium oxide (MgO) and calcium oxide (Cab), and (5) alumina (Al□03).
It has a composition of 0.01 to 5%.

Although these glass components naturally do not act as individual components, the reason why the ratio of each component is limited as described above is as follows.

If S i 02 is less than 65% by weight, the dielectric constant and coefficient of thermal expansion will become too large, and if it exceeds 85% by weight, the softening temperature of the glass will become high and the firing temperature of the substrate will become high, so both are not preferred.

B203 is a fluxing agent, and if it is less than 5% by weight, the softening temperature of the glass will become too high, and if it is more than 25% by weight, the softening point of the glass will become too low and the moisture resistance will decrease, so either case is not preferable.

Alkali metal oxides such as Li2O and Naz 01K20 are added to improve the melting properties during glass production, but if it exceeds 7% by weight, the dielectric constant and coefficient of thermal expansion will increase, and the insulation properties will decrease. Electrical and thermal characteristics deteriorate, which is undesirable.

Like alkali metal oxides, MgO1Ca◯ is also added to improve the melting properties during glass production, but if it exceeds 5%, the dielectric constant becomes too large, which is not preferable.

A1203 is added to improve the moisture resistance of the substrate, but if it exceeds 5% by weight, there is a risk of devitrification occurring during glass production, which is not preferable.

Aluminum borate powder is added to increase the strength of the substrate. In the present invention, aluminum borate fine powder pulverized to an average particle diameter of 3 μm or less, or whiskers prepared to have a diameter of 05 to 30 μm and a length of about 10 to 200 μm can be used in the present invention.

In addition, the general chemical composition of aluminum borate is A1□8B4033, A1eBa○2□, and A1
4 B20. However, in the present invention, these compounds may be used individually or in the form of a mixture in terms of composition or form. In order to develop the strength of the substrate, whiskers are particularly preferably used.

The ratio of aluminum borate in the total amount of the mixture of aluminum borate powder and borosilicate glass powder is 20 to 6
0% by weight, preferably 30-60% by weight.

If the content of aluminum borate powder exceeds 60% by weight, the content of borosilicate glass powder will decrease.1.
When firing at a temperature of 000° C. or lower, the aluminum borate cannot be sufficiently wetted, and the fired body has pores, making it impossible to obtain a dense body. Further, since the dielectric constant of aluminum borate is approximately 6, the dielectric constant of the substrate increases, which is not preferable. If the content of aluminum borate is less than 20% by weight, the strength of the fired product decreases, which is not preferable. In addition, in the raw material composition of the present invention, a part of aluminum borate is alumina (A1203), spinel (MgO-Al□03), cordierite (2Mg0
・2A1203 ・5SiO2), Mullite (3A1
□03 ・2Si○2), forsterite (2Mgo
・5102), anorthite (Ca O-A 1203)
・2SiOz), Celsian (BaO-A1203
・2SiO2) (hereinafter referred to as an oxide compound) may be substituted.

However, if the amount of aluminum borate powder becomes too small, the balance between the permittivity and thermal expansion coefficient of the resulting substrate will be poor, so the ratio of aluminum borate in the raw material composition needs to be 15% by weight or more. . Like aluminum borate powder, the oxide compound has the effect of developing the strength of the ceramic substrate, and each can be used alone or in combination.
More than one type can be mixed and used.

Typical methods for producing the raw material composition for ceramic substrates of the present invention include borosilicate glass powder pulverized to an average particle size of 3 μm or less, aluminum borate fine powder pulverized to an average particle size of 3 μm or less, or Diameter is 0.5-3.0
JIII+, aluminum borate whiskers prepared to have a length of about 10 to 200 μm, and an oxide compound pulverized to an average particle size of 3 μm or less, respectively, within the above blending ratio so that the total is 100% by weight. Mix and prepare.

Since this raw material composition can be fired at low temperatures, it can be fired simultaneously and multilayered using low resistance conductors such as Ag-Pd, Ag, Au, Cu, etc.

In order to sinter this raw material composition into a substrate, water or an organic vehicle is added to the raw material composition and a uniformly mixed paste is formed into a green sheet of a predetermined thickness using a doctor blade method, etc. Depending on the shape and properties of the product, a ceramic substrate with a low dielectric constant and low coefficient of thermal expansion can be obtained by forming circuits and other layers and firing them at a temperature of 900~]OOOO℃. can. Mixing of the raw material composition or mixing of the raw material composition with water or an organic vehicle is carried out using a normal mixing method that does not cause the risk of mixing impurities, such as placing the raw material composition in a polyethylene pot filled with alumina balls and rotating the pot. can be done. Alternatively, at least one powder selected from borosilicate glass powder, aluminum borate powder, or oxide compound group may be mixed with water or an organic vehicle in advance, without being mixed in advance as a raw material composition. may be added and mixed.

The organic vehicles used here include alcohols,
Solvents such as toluene and methyl ethyl ketone, PVA (
Molding aids such as polyvinyl alcohol), PVB (polyvinyl butyral), ethyl cellulose, acrylic resins, phthalic acid-based or other plasticizers such as dibutyl phthalate, dibutyl phthalate, benzyl butyl phthalate, diethylamine, hydroxyl Examples include peptizers such as Beimen methylammonium. Additionally, an inorganic vehicle such as sodium phosphate may be used within a range that does not affect the performance of the product. Since the raw material composition of the present invention can be fired at a temperature of 1000°C or lower, Ag-Pd and
A circuit or the like can be formed using a low-resistance conductor such as Ag, Au, or Cu, and if necessary, it can be fired in a laminated form.

Furthermore, a ceramic substrate obtained using this raw material composition has a low dielectric constant and a coefficient of thermal expansion close to that of a semiconductor element.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

In this example, each raw material prepared as follows was used.

As borosilicate glass powder, on a weight basis, 8102
78.5%, B2O3 13.4%, Al 20. ．． 0
．． 11%, MgO0.39%, Ca00.03%, T
A sample having a composition of 20,007% iO and the balance 20% was prepared to have an average particle size of 3. As aluminum borate powder, fine powder aluminum borate is Al
2O3 and B2O3 were blended to have a composition of A I +aB4033 or A14B209, respectively, and heat treated to have an average particle size of 2 μm, and the whisker-shaped aluminum borate had a chemical composition of A I +aB4033 or A14B209.
4033 with a diameter of 0.5 to 1.0 μm and a length of 1
The thickness was adjusted to 0 to 30 μm. The oxide compound has an average particle size of 2
It was prepared in μm.

(Examples 1 to 15, Comparative Examples 1 to 8) In Examples 1 to 10 and Comparative Examples 1 to 4, borosilicate glass powder and polycrystalline aluminum borate fine powder were used in predetermined amounts at the ratios shown in Table 1. The mixture was weighed, mixed in a groove for 3 hours using an alumina hole mill, and then molded.The resulting product was fired at a temperature of 950° C. for 5 hours in an air atmosphere.

In addition, in Examples 11 to 15 and Comparative Example 5.6, predetermined amounts of borosilicate glass powder and whisker-like aluminum borate were weighed at the ratios shown in Table 1, and the borosilicate glass powder and whisker-like boric acid 14 parts by weight of acrylic resin per 100 parts by weight of aluminum mixed powder
Weighed 3 parts by weight of dibutyl phthalate, 32 parts by weight of toluene, 68 parts by weight of ethanol, and 1 part by weight of sorbitan monolaurate, and heated them in a polyethylene pot equipped with an alumina hole for 24 hours to homogenize them. Adjusted the slurry. Next, using the slurry, green sheets with a thickness of 02 mm were produced by a doctor blade method, and 20 of the obtained green sheets (thickness, approximately 4 mm) were prepared using the slurry.
mm) After stacking and crimping, it was made into a sample piece with dimensions of 50 x 50 mm.

The sample piece was fired at a temperature of 950° C. for 3 hours in an air atmosphere. Table 1 shows the results of measuring the characteristics of the fired body thus obtained using the method described below. The dielectric constant and dielectric loss tangent were measured at 20° C. and IMHz using a Q meter, and the signal propagation delay time (Tpd) was calculated using the following formula. Note that the shorter the signal propagation delay time, the lower the dielectric constant (ε
) indicates that the signal transmission speed is faster.

Tpd=rτnC(ns/m) Here, C: speed of light ns/m Represents nanoseconds/meter.

The coefficient of thermal expansion was measured using a quartz differential thermal dilatometer from room temperature to 4.
Measurements were made between 00°C. The bending strength is based on the Japanese Industrial Standards (JIS).
) Measured according to R1601.

As is clear from the results in Table 1, the fired body obtained from the raw material composition of the present invention has a dielectric constant of 30-30 compared to the conventional alumina substrate or alumina-glass composite substrate shown in Comparative Examples 7 and 8. The signal delay time has been reduced by 40%, and accordingly, the signal delay time has been shortened to 68 to 7.5 ns/m, and at the same time, the thermal expansion coefficient has characteristics similar to that of a semiconductor element. Note that the dielectric loss tangent at this time is (11 to 17
)XIO-'.

In Comparative Examples 1.3 and 5, since the blended amount of borosilicate glass powder was large, the properties of the fired bodies were affected by the properties of the borosilicate glass powder, and the strength development was also poor. Also, Comparative Example 2.
Samples No. 4 and No. 6 are not preferred because pores are observed on the surface of the obtained fired product.

(Examples 16 to 30, Comparative Examples 9 to 14) Borosilicate glass powder, aluminum borate powder (fine powder or whiskers), and oxide compounds were each weighed in predetermined amounts at the ratios shown in Table 2. It was operated and treated in the same manner as in 15. From Table 2, it can be seen that each characteristic value of the obtained fired body is almost equivalent to that of the example in which no oxide compound was used. In addition, as can be seen from Comparative Examples 9 to 14, if the proportion of aluminum borate is less than 15%, the coefficient of thermal expansion is small;
The bending strength also decreases, which defeats the purpose of the present invention. Furthermore, if the proportion of borosilicate glass is less than 40% by weight, the bending strength will be high due to the action of aluminum borate and oxide compounds, but the relative density will decrease.

[Effect of the invention] As mentioned above, the raw material composition of the present invention can be heated at 1000°C.
Ag-
Pd, Ag, Au, Cu, etc. can be used. In addition, the ceramic substrate obtained from this raw material composition has a low dielectric constant and a coefficient of thermal expansion close to that of semiconductor elements, resulting in faster LSIs, higher density packaging, and higher reliability. It can contribute to improving sexual performance.

Claims (3)

[Claims] 1. Borosilicate glass powder in the range of 40 to 80% by weight and aluminum borate powder in the range of 20 to 60% by weight
A raw material composition for a ceramic substrate, characterized in that it is a mixture containing within the range of: 2. In the raw material composition according to claim 1, a part of the aluminum borate powder is mixed with alumina, spinel, cordierite, mullite, forsterite, anorthite, and celsian within a range where the aluminum borate content is 15% by weight or more. A raw material composition for a ceramic substrate substituted with one or more selected from the group consisting of: 3. The raw material composition according to claim 1 or 2 is mixed with water and/or an organic vehicle, formed into a green sheet of a predetermined thickness, and then a circuit is formed according to the desired product shape and properties. The laminated one is 900 to 1,0
A method for producing a ceramic substrate, characterized by firing at a temperature of 0.000C.