JPS62124799A - Glass ceramic multilayer substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [4 Already Required] By forming the upper and lower layers of the glass ceramic multilayer substrate from glass ceramic in which heat-resistant ceramic powder with a low coefficient of thermal expansion is dispersed, destruction of the glass phase is eliminated and strength is achieved. multilayer board.

[Industrial application field]

The present invention relates to the structure of a glass-ceramic multilayer substrate with improved mechanical strength.

IC, L to achieve faster information processing and larger capacity
In semiconductor devices such as SI, the unit elements constituting these devices have become smaller, and with advances in passivation technology, large-capacity elements have come to be mounted on substrates without changing the semiconductor chip.

That is, the trend is to create an LSI module by mounting a plurality of LSI chips on a printed wiring board made of ceramics, and to mount this LSI module on a conventional printed wiring board as a replacement unit.

The present invention relates to improvements in such ceramic circuit boards.

[Conventional technology]

Ceramic circuit board requirements are: ■Multilayer structure with good heat conduction.

■It is possible to form fine conductor patterns.

■Excellent signal transmission characteristics.

etc.

In other words, LSI chips are equipped with a large number of terminals, but since multiple such LSI chips are mounted on a ceramic substrate, the number of terminals, that is, the number of wires, becomes enormous, resulting in a multilayer wiring structure, and the conductor pattern width is extremely narrow. It is necessary to form.

Here, the multilayer wiring is composed of signal lines, power supply lines, ground lines, etc., and since the signal frequency is high, it is necessary that crosstalk between layers or wirings and signal delay be small.

Further, in order to suppress heat generation in the wiring, the wiring board needs to be made of a material with good thermal conductivity.

Here, alumina (α-8 to 20 C1) ceramics has traditionally been used as a single-layer substrate due to its excellent heat resistance, thermal conductivity, and dielectric properties. Forming multilayer substrates is difficult.

In other words, the sintering temperature of alumina ceramics is approximately 1600℃.
℃, and therefore only special high-melting point metals such as molybdenum (Mo) and tungsten (W) can be used as wiring pattern forming materials, resulting in high resistance of wiring patterns and difficulty in forming fine wiring patterns.

For these reasons, glass ceramics, in which alumina powder is dispersed in low-loss borosilicate glass, have come to be used as constituent materials for multilayer substrates.

The advantages of this product are: ■ Good workability due to the low sintering temperature of approximately 1000°C (
, metals with low resistivity such as gold (Au) and copper (Cu) can be used as wiring pattern materials, and fine patterns can be formed; ■ substrates with a lower dielectric constant than alumina ceramics can be made; Therefore, it can be mentioned that it has good electrical characteristics.

However, the coefficient of thermal expansion of borosilicate glass is approximately 3XIO-'/℃
Although it is small, the coefficient of thermal expansion of alumina is 8 × 10-6/°
Because of the large C, there is a problem in that tension acts inside the glass substrate when the substrate temperature returns to room temperature after the heat treatment, and the glass phase is likely to be destroyed, which requires improvement.

[Problem that the invention seeks to solve]

As mentioned above, glass-ceramics with alumina powder dispersed in them are used as constituent materials for multilayer wiring boards used to mount semiconductor chips. Due to the difference in thermal expansion coefficients, the glass phase breaks down after the heat treatment process, causing fine cracks and impairing reliability, and improvements have been desired.

[Means for solving problems]

The above problem can be solved by using glass with alumina powder dispersed in it, then creating vias and printing a wiring pattern.
A second green sheet is prepared using glass in which a heat-resistant ceramic powder having a coefficient of thermal expansion smaller than that of the alumina powder is dispersed, and a second green sheet is prepared in which vias are formed and a wiring pattern is printed. This problem can be solved by using a glass-ceramic multilayer substrate, which is characterized in that two first green sheets are positioned so as to be sandwiched between second green sheets, stacked, and then baked and integrated.

[Function] The present invention provides a method for eliminating destruction of the glass phase caused by differences in thermal expansion coefficients. By using glass ceramic dispersed with ceramic powder, which has higher bending strength than glass ceramic dispersed with alumina, as the upper and lower layers of a multilayer substrate,
This problem is solved.

In other words, semiconductor chips are densely mounted on the upper and lower layers of a multilayer board, and in most cases the wiring pattern from the bonding pad is immediately led inside through vias, so the internal layers of the multilayer board are This method uses alumina-dispersed glass ceramic.

The following table shows a comparison of the thermal expansion coefficient of ceramic materials suitable for such purposes and the bending strength of glass-ceramink with conventional materials.

Next, the manufacturing method for the multilayer board is to create a glass-ceramic layer with alumina powder dispersed in it, create a green sheet in which these ceramics are evenly dispersed, punch via holes in predetermined positions, and print a conductor pattern. It is then dried, accurately positioned with a separately formed alumina-dispersed green sheet, and integrated under pressure, followed by high-temperature firing and fusion.

Examples will be described below.

Example 1: 350 g of alumina powder with a particle size of 3 to 6 μm, 350 g of borosilicate glass, 80 g of polyvinyl butylade (hereinafter abbreviated as PVB) as a binder, 30 g of cyphytyl phthalate as a plasticizer, and 350 g of borosilicate glass as a binder. alcohol 100
Mix 700g of acetone and 700g of acetone, and use a ball mill to
A slurry was prepared by kneading each other for 0 hours, and a doctor blade method was applied to the slurry to form a green sheet with a thickness of about 300 μm, which was punched into 150 mm square pieces.

In addition, a 150 mm square green sheet was made in the same manner using silicon carbide (Si C) with a particle size of approximately 1 μm instead of alumina powder.

Next, holes are drilled at predetermined positions in the green sheet to form via holes, a conductor pattern is printed, and ten layers are aligned using green sheets with SiC dispersed in the upper and lower layers, and the mold is assembled. was used to apply pressure and laminate.

This was fired in a nitrogen (N2) stream at 1000° C. for 4 hours to obtain a glass-ceramink substrate, but no fine cracks due to destruction of the glass phase were observed as in the prior art.

Example 2: A green sheet was made using alumina powder in the same manner as in Example 1, and silicon nitride (Si) was used instead of alumina powder.
A green sheet was made using the same method using 3N B ) powder.

Then, vias were formed in each grid-1 and a conductive pattern was printed.

Using such a green sheet, each of the upper and lower layers contains S.
A glass-ceramic layer with i3N4 dispersed is used, and a glass-ceramic layer with alumina dispersed in the center is used.
) Laminated and pressurized, integrated and heated to 1000℃ in a N2 stream
, and fired for 4 hours to produce a multilayer ceramic.

No microcracks due to destruction of the glass phase were observed in such multilayer ceramics.

Example 3: A green sheet with alumina powder dispersed therein was prepared in the same manner as in Example 1, and mullite (3
Al 203 ・2 SiO2) powder was used instead of alumina powder, and 1
I made a green sheet of 50 Tsurukaku.

Then, a wiring pattern was printed to match the circuit, and vias were formed. Seven layers of glass ceramic were used in which mullite was dispersed in each of the upper and lower layers, and the 30-layer structure was baked under the same conditions as in Example 1. Although a multilayer ceramic was formed, no fine racks due to destruction of the glass phase were observed.

Example 4: A green sheet with alumina powder dispersed therein was prepared in the same manner as in Example 1, and zircon (Zr
A 1501) square green sheet was prepared in the same manner as in Example 1 using SiO4) powder instead of alumina powder.

Then, a wiring pattern was printed in accordance with the circuit, and vias were formed. Glass-ceramic layers with mullite dispersed therein were used in each of the upper and lower layers, and were fired under the same conditions as in Example 1 to form a 10-layer multilayer ceramic. Although some cracks were formed, no fine racks due to destruction of the glass phase were observed.

Example 5: A green sheet with alumina powder dispersed therein was made in the same manner as in Example 1, and cordierite (2MgO.2Al103.5SiOz) powder with a unilateral diameter of 3 to 6 μm was used instead of the alumina powder. In the same manner as in Example 1, green sheets each having a size of 150 n squares were made.

Then, a wiring pattern was printed to match the circuit, and vias were formed. Glass ceramic layers with mullite dispersed therein were used in each of the upper and lower layers, and were fired under the same conditions as in Example 1 to form a 20-layer multilayer ceramic. However, no fine racks due to destruction of the glass phase were observed.

Example 6: A green sheet with alumina powder dispersed therein was prepared in the same manner as in Example 1, and aluminum nitride (^IN) powder with a one-sided diameter of 3 to 6 μm was used instead of the alumina powder. Green sheets each measuring 150 mm square were made in the same manner as above.

Then, we printed a wiring pattern to match the circuit, formed vias, used glass ceramic layers in which mullite was dispersed in each of the upper and lower layers, and fired them under the same conditions as in Example 1 to create a 10-layer multilayer ceramic. However, no fine racks due to destruction of the glass phase were observed.

〔Effect of the invention〕

As described above, according to the present invention, the thermal expansion coefficient of Hirami-nox and the thermal expansion coefficient of borosilicate glass are close to each other, so less stress is generated, and therefore, the destruction of the stress glass phase does not occur. Furthermore, it is possible to produce a reinforced multilayer board with a higher track number than the conventional one.

Claims (7)

[Claims] (1) A first green sheet formed using glass in which alumina powder is dispersed, then vias are formed and a wiring pattern is printed, and glass in which heat-resistant ceramic powder having a coefficient of thermal expansion smaller than that of the alumina powder is dispersed. After forming vias using A glass-ceramic multilayer substrate characterized by being integrated by firing. (2) The glass-ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder has a lower coefficient of thermal expansion than alumina powder and is made of silicon carbide. (3) The glass-ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder having a coefficient of thermal expansion smaller than that of alumina powder is made of silicon nitride. (4) The glass-ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder has a coefficient of thermal expansion smaller than that of alumina powder and is made of mullite. (5) The glass-ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder has a coefficient of thermal expansion smaller than that of alumina powder and is made of zircon. (6) The glass-ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder has a coefficient of thermal expansion smaller than that of alumina powder and is made of cordierite. (7) The glass ceramic multilayer substrate according to claim 1, wherein the heat-resistant ceramic powder having a coefficient of thermal expansion smaller than that of alumina powder is made of aluminum nitride.