JPS6238301B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to glass for semiconductor coating, and particularly to a glass composition suitable for manufacturing a so-called molded semiconductor device, in which the entire semiconductor device having a PN junction including electrodes is coated with a thick layer of glass. . As an example of such a molded semiconductor device, the structure of a silicon diode is shown in the attached drawings. In the drawing, a silicon device 10 with a PN junction is shown.
is sandwiched between a pair of molybdenum or tungsten electrodes 12 to which an aluminum vapor-deposited film 11 is attached, a copper lead wire 13 is welded to the electrodes 12, and the surfaces of the silicon element 10 and the electrodes 12 are It is covered with a covering glass 14. Generally, when coating a semiconductor element with glass as described above, glass powder is applied to the surface of the semiconductor element, and then the glass is heated to a sealing temperature to melt and fluidize the glass to form an airtight coating on the surface of the semiconductor element. Form a glass layer. Conventionally, ZnO was used as such glass for semiconductor coating.
−B ₂ O ₃ −SiO ₂ glass is used, but the sealing temperature of the glass that is put into practical use is 700 to 800.
It is ℃. When the sealing temperature is high in this way, in the case of the molded silicon diode mentioned above, the eutectic point of the silicon and aluminum that make up the semiconductor element is approximately 575°C, so the silicon element and electrode Deterioration occurs at the junction with the semiconductor element, resulting in a disadvantage that the characteristics of the semiconductor element are impaired. Therefore,
Firstly, the glass for semiconductor coating is required to have a sealing temperature as low as possible. In addition to the above-mentioned characteristics, the glass for semiconductor coatings must have a thermal expansion coefficient that matches that of silicon and the electrode material molybdenum or tungsten, and that the electrical properties of the semiconductor must be It has excellent characteristics, especially high reverse breakdown voltage, low reverse leakage current, and can withstand thermal shock during soldering of lead wires. The object of the present invention is to satisfy the various properties required for the above-mentioned glass for semiconductor coating, and in particular, to have a sealing temperature of 650°C.
It is an object of the present invention to provide a glass for semiconductor coating having a temperature of ℃ or less. The above object of the invention is achieved by using a glass having the composition expressed in weight percent as follows:

[Table] The reason for limiting the range of each component as described above in the present invention is as follows. If ZnO is more than 55%, the fluidity and wettability of the glass will be poor, and if it is less than 35%, the coefficient of thermal expansion will be too large. When B ₂ O ₃ is 30% or more, the glass sealing temperature increases, and when it is 10% or less, it becomes difficult to vitrify. If SiO ₂ is 10% or more, the viscosity of the glass becomes too high and sealing is impossible at temperatures below 650° C., and if it is 5% or less, devitrification tends to occur, making it impossible to obtain a stable glass. When PbO is 40% or more, the thermal expansion coefficient becomes too large, and when it is 15% or less, sealing cannot be performed at a temperature of 650° C. or less. At least one of SnO ₂ and Bi ₂ O ₃ is used to improve the electrical properties of semiconductors.
Contains 0.05% or more, including 5% each of SnO ₂ and Bi ₂ O ₃
When the total amount exceeds 8%, it is difficult to obtain a homogeneous glass, and the coefficient of thermal expansion becomes too large. The inclusion of MnO ₂ and CeO ₂ improves the electrical properties of the semiconductor, but when the MnO ₂ content is 5% or more and the CeO ₂ content is 3% or more, it is difficult to form a homogeneous glass. Sb ₂ O ₃ is the above-mentioned MnO ₂ , CeO ₂ , SnO ₂ , Bi ₂ O ₃
It enhances the action and effect of glass and improves the solubility of glass, but the effect is small below 0.1%, and 3%
Above this, it becomes difficult to obtain homogeneous glass. Al ₂ O ₃ stabilizes the glass and improves its chemical durability, but if it exceeds 3.0%, the viscosity of the glass increases and it becomes difficult to obtain a good coating. Table 1 shows the composition of Examples of the coating glass of the present invention. In the lower row of the same table, 30~ for each example glass.
The thermal expansion coefficient and coating sealing temperature at 300°C are shown.

[Table] In the present invention, fillers such as willemite powder (2ZnO.SiO ₂ ) powder, quartz glass (SiO ₂ ) powder, zircon (ZnO _{2.SiO 2} ) powder, By mixing at least one of cordierite (2MgO.2Al ₂ O ₃ .5SiO ₂ ) powder in a predetermined proportion, it is possible to improve electrical properties, lower the coefficient of thermal expansion, and improve solder thermal shock resistance. The mixing ratio is 0 to 15% of willemite powder, 0 to 10% of quartz glass powder, 0 to 15% of zircon powder, 0 to 10% of cordierite powder, and their contents by weight relative to the coating glass.
It is appropriate to mix 0.01 to 20%. If the content of filler powder is less than 0.01%, it is not very effective.
On the other hand, when the content of each filler exceeds each of the above-mentioned upper limits, or when the total amount exceeds 20%, not only the fluidity deteriorates, but also the electrical properties of the semiconductor may deteriorate. Table 2 shows an example in which glass B in Table 1 was used and a filler was mixed therein, and the coefficient of thermal expansion is shown in the lower row.
Indicates sealing temperature.

【table】

[Table] The coating glass of the present invention can be sealed at a low temperature of 650°C or less and has other excellent properties, so it is suitable for coating molded semiconductor devices, but it is not limited to this. Needless to say, it is widely used for coating semiconductor devices.

[Brief explanation of the drawing]

The drawing is a partial sectional view showing a structural example of a molded semiconductor device to which the covering glass of the present invention is applied. 10; Silicon element; 14; Covering glass.

Claims (1)

[Claims] A semiconductor coating glass having the composition shown in [Table] at 1% by weight. 2% by weight of glass powder having the composition shown in Table 1, mixed with at least one of willemite powder, quartz glass powder, zircon powder, and cordierite powder as a filler. 3. The glass for semiconductor coating according to claim 2, which is obtained by mixing glass powder with the following in a weight ratio.