JPH04238858A - Low temperature fired glass ceramic body - Google Patents

Abstract

PURPOSE:To provide a low-temperature burnt glass ceramic material suitable as an insulating substrate for multilayer circuit board, having high mechanical strength of insulating substrate, low coefficient of thermal expansion and dielectric constant, using copper as a conductive material, simultaneously burnable at low temperature close to 1,000 deg.C. CONSTITUTION:Borosilicate glass is blended with a ceramic insulating material and burnt at 900-1,050 deg.C to give a sintered material of glass ceramics consisting of a crystal layer comprising 18-24wt.% alumina, 8-17wt.% quartz and 13-25wt.% cordierite and the rest of borosilicate glass having 770-850 deg.C softening point.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature fired glass-ceramic body which can be used as an insulating substrate for multilayer wiring boards and the like on which semiconductor integrated circuit elements are mounted.

0002

[Prior Art] Conventionally, insulating substrates such as multilayer wiring boards on which semiconductor elements, particularly semiconductor integrated circuit elements made of silicon, are mounted are generally made of alumina ceramics, which have excellent electrical insulation properties, heat resistance, and high strength. An electric wiring circuit is formed by printing a thick film of a metallized metal layer made of a high melting point metal such as molybdenum (Mo) or tungsten (W) on a substrate made of such alumina ceramics. A multilayer ceramic wiring board was obtained by forming multiple layers and firing them together.

However, in recent years, the size of semiconductor elements and the speed of signal propagation have rapidly increased, and when the semiconductor elements are mounted on the above-mentioned conventional multilayer ceramic wiring board,
The coefficient of thermal expansion of alumina ceramics constituting semiconductor integrated circuit elements is 6.0 to 7.5×10 −6 /°C, whereas the coefficient of thermal expansion of silicon is 3.5×10 −6
/℃, which causes large thermal stress when mounting semiconductor integrated circuit elements, which can cause problems such as damage to semiconductor integrated circuit elements and peeling from insulating substrates. there were.

[0004] Furthermore, the alumina ceramics constituting the insulating substrate has a dielectric constant of 9 to 10 (at room temperature, 1 MHz).
Since the delay time of high-frequency propagation is proportional to the square root of the dielectric constant, the propagation speed of the signal through the metallized metal layer provided on the insulating substrate is slow, and for high-speed signal propagation, insulation with a lower dielectric constant is required. A base was required.

Furthermore, since the insulating substrate made of alumina ceramics has a high firing temperature of around 1600°C,
The metallized metal layer that forms the electrical wiring circuit is also limited to high-melting point metals such as molybdenum and tungsten, and due to the high electrical resistivity and high density wiring, the wiring resistance of the electrical wiring circuit becomes large, and the voltage drop increases accordingly. Therefore, it has been required that metals with low resistivity, such as gold and copper, can be used as materials for electrical wiring circuits.

In order to solve the above-mentioned problems, Japanese Patent Application Laid-Open No. 63-248199 proposes that the insulating substrate of the multilayer wiring board be replaced with alumina ceramics and have a coefficient of thermal expansion that approximates that of silicon constituting the semiconductor integrated circuit element. Alumina powder is added to borosilicate glass, which is a low softening point glass that has a high coefficient of thermal expansion and a low dielectric constant of 4.6 or less, making it possible to achieve a firing temperature of around 1000℃ compared to high silica glass. A glass ceramic multilayer wiring board has been proposed.

[0007]

However, a glass ceramic multilayer wiring board made by adding alumina powder to the high silica glass and borosilicate glass, which is a low softening point glass, has a low dielectric constant but a bending strength of 15 kg. /mm
2 or less, and even if practical mechanical strength as a board can be obtained by increasing the thickness of the board, pins for input/output of electrical signals to electrically connect the board to an external circuit, etc. When locally heated during the brazing process, thermal stress caused by the difference in thermal expansion between the brazing material and the substrate material can cause cracks in the substrate and peeling of the metallized metal layer on the substrate surface. There was a problem that a high-quality multilayer wiring board with excellent reliability could not be obtained.

Furthermore, if a trace amount of carbon remains on the substrate, the substrate becomes porous, the color tone becomes uneven, and the mechanical and electrical properties of the substrate deteriorate. As is clear from the diagram of the relationship between temperature and free energy change in the reaction between carbon and water vapor, desorption occurs at a temperature of 680°C or higher, preferably 750°C or higher, which is the temperature at which carbon reacts with water vapor and scatters as carbon dioxide gas. Need a binder.

However, since glass with a softening point of 1000° C. or lower is used in the glass ceramic multilayer wiring board, closed pores are formed due to the softening flow of the glass, and the binder cannot be completely removed if the glass has a low softening point. Therefore, carbon of 100 ppm or more remains.

On the other hand, if you try to use glass that does not soften and flow at temperatures above 750°C, the softening point of the glass will generally be above 850°C within the above temperature range, and if you try to obtain a dense sintered body, the firing temperature will increase. The temperature exceeds 1050° C., which is close to the melting point of copper, and there is a problem in that it cannot be fired at the same time as forming the copper conductor layer.

[0011]

OBJECTS OF THE INVENTION The present invention was developed in order to eliminate the above-mentioned drawbacks, and its purpose is to provide an insulating base with high mechanical strength, and to attach external lead terminals such as pins to the metallized metal layer provided on the insulating base. In addition to being able to be firmly brazed, the insulating substrate has a low coefficient of thermal expansion and dielectric constant, copper is used as the conductor material, and binder removal can be achieved with extremely low residual carbon, and low-temperature firing at around 1000°C is possible. An object of the present invention is to provide a low-temperature fired glass-ceramic body that can be used as an extremely reliable insulating substrate for a multilayer wiring board.

0012

[Means for Solving the Problems] The low-temperature fired glass-ceramic body of the present invention is obtained by adding a ceramic insulating material to borosilicate glass, and the crystal phase of the glass-ceramic sintered body is 18 ~24 wt% alumina (Al2O3), 8-17 wt% quartz (SiO
2) and 13-25% by weight of cordierite (2Mg
O.2Al2O3.5SiO2), and the remainder is made of borosilicate glass having a softening point in the range of 770 to 850°C.

That is, the softening point of the borosilicate glass is 770
If the temperature is below ℃, the glass softens and flows violently during binder removal, resulting in large shrinkage of the glass-ceramic sintered body, and 100 ppm or more of carbon remains in the glass-ceramic sintered body, resulting in deterioration of the strength of the sintered body. or cause deterioration of withstand voltage. Further, the softening point of the borosilicate glass is 850.
If the temperature exceeds 1050°C, a dense sintered body cannot be obtained unless the firing temperature is 1050°C or higher.

If the content of alumina (Al2O3) in the crystal layer of the glass ceramic sintered body is less than 18% by weight, the flexural strength of the sintered body will be as low as 15 kg/mm2 or less, and the acid resistance will deteriorate. During the plating process, the glass at the interface between the conductor layer and the sintered body is corroded, and when a small amount of moisture remaining in the corroded area is heated in a later process, it may cause blisters in the metallized metal layer or damage the metallized metal layer. The metal layer will peel off. Moreover, if it exceeds 24% by weight, the dielectric constant of the sintered body becomes 5 or more, which is beyond the practical range.

Furthermore, if the content of quartz (SiO2) is less than 8% by weight, the firing temperature will be 1050° C. or higher, and the dielectric constant will be as high as 5 or higher. On the other hand, if it exceeds 17%, the acid resistance of the sintered body will deteriorate or the thermal expansion coefficient will be 4.5×1.
It becomes larger than 0-6/℃.

Next, cordierite (2MgO.2Al
If the content of 2O3 ・5SiO2) is less than 13% by weight, the coefficient of thermal expansion of the sintered body will be greater than 4.5×10 -6 /℃, and if it exceeds 25% by weight, the coefficient of thermal expansion of the sintered body will decrease. is smaller than 3.5×10 −6 /° C., which is too small than the coefficient of thermal expansion of silicon constituting the semiconductor integrated circuit element, making both of them impractical.

[0017] Furthermore, if the firing temperature is less than 900°C,
Gold (Au), silver (Ag), copper (Cu) with low resistivity
If the temperature exceeds 1050° C., the low-resistance metal will melt, making it impossible to form an electric wiring circuit. Therefore, the softening point of the borosilicate glass, the content of the crystal layer of the glass ceramic sintered body, and the firing temperature are specified within the above ranges.

From the viewpoint of firing temperature, coefficient of thermal expansion, dielectric constant, and acid resistance, it is recommended to use alumina (Al2O3) of 19 to 21% by weight as a low-temperature fired glass-ceramic body.
11-15% by weight of quartz (SiO2), 18-23% by weight of cordierite (2MgO.2Al2O3.
It is more desirable that the crystal layer of 5SiO2) and the remainder be made of borosilicate glass having a softening point in the range of 780 to 820C.

[0019]

[Function] A low-temperature fired glass-ceramic body made by adding a ceramic insulating material to borosilicate glass contains borosilicate glass, which has low strength but a small dielectric constant, as the main component, and the borosilicate glass has a dielectric constant and a coefficient of thermal expansion. The dielectric constant of the glass-ceramic sintered body is increased by including an alumina crystal layer with high strength, a quartz crystal layer with a low dielectric constant, and a cordierite crystal layer with a low coefficient of thermal expansion and dielectric constant. The coefficient of thermal expansion is low, and the strength can be adjusted to be high.

[0020] Furthermore, by using borosilicate glass with a softening point of 770 to 850°C, residual carbon can be reduced to 100 ppm or less by debinding in a non-oxidizing atmosphere, and copper with low electrical resistance can be used as a conductor material. becomes.

[0021]

EXAMPLES Next, the low-temperature fired glass-ceramic body of the present invention will be explained in detail based on examples. The composition of the raw material powder is 72-76% SiO2 and 15-17% B2 by weight.
O3, 2-4% Al2O3, 1.5% or less MgO, 1.1-1.4% ZrO2, Na2O, K
Alumina (Al2O3),
Quartz (SiO2) and cordierite (2MgO・2
Each powder of Al2O3 ・5SiO2) was mixed so that the composition of the glass ceramic sintered body had the value shown in Table 1, and the mixed powder was wet-mixed using a ball mill using methanol as a solvent, and then the mixed powder was dried. Paraffin wax was added to the mixture to granulate it, and press molding was performed at a molding pressure of about 1000 kg/cm2 into disc-shaped and two types of prismatic molded bodies. Next, after removing the binder from the molded body at a temperature of 350°C, it was fired at a temperature of 880 to 1080°C to obtain glass ceramic sintered bodies having a disk shape and two types of prismatic shapes, respectively.

First, X-ray diffraction was performed using one of the above glass ceramic sintered bodies, and compared with a calibration curve diagram of each crystal layer created from the peak ratios of the diffraction patterns of standard samples of alumina, quartz, and cordierite. The content of each crystal layer was confirmed. Next, an evaluation sample with a diameter of 60 mm and a thickness of 2 mm was prepared by polishing the disk-shaped glass ceramic sintered body, and with this evaluation sample, a frequency of 1 MHz and an input signal level of 1. The dielectric constant was measured under the measurement condition of 0 Vrms. Similarly, from a prismatic glass ceramic sintered body, the length is 6 mm, the width is 6 mm, and the length is 50 mm.
The average coefficient of thermal expansion in the temperature range of 40 to 400° C. was measured using the evaluation sample polished to 400° C.

[0023] Also, using an evaluation sample polished to 3 mm in length, 4 mm in width, and 40 mm in length, JIS-R
A three-point bending test was conducted in accordance with the regulations of -1601 to determine the bending strength. Furthermore, the above evaluation sample was immersed in a 10% hydrochloric acid solution at room temperature for 15 minutes, and the weight change before and after immersion was measured to evaluate acid resistance. On the other hand, a binder mainly composed of acrylic resin, a dispersant, a plasticizer, and an organic solvent were added to a mixed powder prepared and pulverized so that the composition of the glass ceramic sintered body became the values shown in Table 1 in the same manner as above. The slurry is made into a slurry by a doctor blade method to a thickness of about 0.0mm.
A 2 mm green sheet molded body was obtained. Next, a wiring pattern for evaluation is thickly printed on the surface of the green sheet by a screen printing method using a conductive paste containing copper as a main component, and after drying, a plurality of green sheets having the wiring pattern for evaluation are heated at 55°C. 100kg/cm2 at temperature
Heat compression bonding was carried out by applying a pressure of .

The binder was removed from this laminate at a temperature of 750 to 800°C in a nitrogen atmosphere containing water vapor, and then it was fired at a temperature of 880 to 1100°C in a nitrogen atmosphere. The thus obtained sintered body was pulverized in an alumina mortar and then heat treated in the atmosphere at a temperature of 1200°C, and the amount of residual carbon in the sintered body was determined from the amount of carbon dioxide gas generated at this time. The above results are shown in Tables 1 and 2.

Table 1

Table 2

[0027]

Effects of the Invention As described above, the low-temperature fired glass-ceramic body of the present invention is obtained by adding a ceramic insulating material to borosilicate glass having a softening point of 770 to 850°C, and increasing the firing temperature to 900 to 850°C.
The crystal layer of the glass-ceramic sintered body, which is fired at a low temperature of 1050°C, contains 18 to 24% by weight of alumina (Al2).
), 8-17% by weight of quartz (SiO2) and 13-25% by weight of cordierite (2MgO.2Al
2O3 .5SiO2) and the remainder is the borosilicate glass, the residual carbon in the sintered body can be kept extremely low, the mechanical strength of the insulating base is high, and the coefficient of thermal expansion is comparable to that of semiconductor integrated circuit elements. A high-quality insulating material for multilayer wiring boards that has a coefficient of thermal expansion comparable to that of the constituent silicon, has an extremely low dielectric constant, and can be deposited with low-resistivity copper as a conductor layer. It is possible to provide a low-temperature fired glass-ceramic body suitable as

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between temperature and free energy change in the reaction between carbon and water vapor to explain the softening point of the borosilicate glass of the present invention.

[Table 1]

[Table 2]

Claims (1)

[Claims] Claim 1: A glass-ceramic sintered body made of borosilicate glass added with a ceramic insulating material, wherein the glass-ceramic sintered body is fired at a temperature of 900 to 1050°C and contains 18 to 24% by weight of alumina as a crystal phase. (Al
2O3), 8-17% by weight of quartz (SiO2) and 13-25% by weight of cordierite (2MgO.2A
12 O3 ・5SiO2 ), with the remainder being 770
A low-temperature-fired glass-ceramic body, characterized in that it consists of a borosilicate glass having a softening point in the range of ~850°C.