Semiconductor element coating glass, and semiconductor element coating material comprising same

Abstract

Provided is a semiconductor element coating glass having little environmental impact, excellent acid resistance and a low firing temperature.　A semiconductor element coating glass characterized by comprising, as a glass composition, 35-65% of SiO2, 0-8% of ZnO, 5-30% of B2O3, 5-15% of Al2O3 and 8-35% of MgO+CaO+SrO+BaO in % by mole, having ZnO / SiO2 of 0-0.2 in a molar ratio, and not substantially containing a lead component.

Description

Glass for covering semiconductor elements and semiconductor element covering material using the same

[0001] The present invention relates to a glass for covering a semiconductor element and a material for covering a semiconductor element using the same.

[0002] In general, the surfaces of semiconductor elements such as silicon diodes and transistors, including the PN junctions, are covered with glass, which stabilizes the surface of the semiconductor element and prevents its characteristics from deteriorating over time.

[0003] The properties required for a glass for covering semiconductor elements include: (1) a thermal expansion coefficient that matches that of the semiconductor element so as to prevent cracks and the like due to differences in the thermal expansion coefficient between the semiconductor element and the glass; (2) the glass must be capable of covering the semiconductor element at low temperatures (for example, 900°C or lower) so as to prevent deterioration of the characteristics of the semiconductor element; and (3) the glass must be free of impurities such as alkaline components that have adverse effects on the surface of the semiconductor element.

[0004] Conventionally, ZnO-B has been used as a glass for covering semiconductor elements. ２ O ３ -SiO ２ zinc-based glass such as PbO—SiO ２ -Al ２ O ３ PbO-SiO ２ -Al ２ O ３ -B ２ O ３ Although lead-based glasses such as PbO-SiO are known, currently, from the viewpoint of workability, ２ -Al ２ O ３ PbO-SiO ２ -Al ２ O ３ -B ２ O ３ Lead-based glasses such as lead-based glasses have become mainstream (see, for example, Patent Documents 1 to 4).

[0005] Japanese Patent Laid-Open No. 48-43275 Japanese Patent Laid-Open No. 50-129181 Japanese Patent Publication No. 1-49653 Japanese Patent Laid-Open No. 2008-162881

[0006] However, the lead component of lead-based glass is harmful to the environment, and the zinc-based glass described above contains small amounts of lead and bismuth components, so it cannot be said to be completely harmless to the environment.

[0007] Furthermore, compared with lead-based glass, zinc-based glass has a problem in that it is inferior in chemical durability and is easily corroded in the acid treatment step after the formation of the coating layer, so it has been necessary to form an additional protective film on the surface of the coating layer before the acid treatment.

[0008] On the other hand, SiO in the glass composition ２ Increasing the content of improves the acid resistance and reverse breakdown voltage of the semiconductor element, but increases the baking temperature of the glass, which may degrade the characteristics of the semiconductor element in the coating process.

[0009] The present invention has been made in view of the above circumstances, and its technical object is to provide a lead-free glass for covering semiconductor elements which has a small environmental impact, excellent acid resistance, and can be fired at a low temperature.

[0010] As a result of extensive research, the present inventors have discovered a SiO ２ -B ２ O ３ -Al ２ O ３ The inventors have found that the above technical problems can be solved by using a glass containing SiO. ２ 35-65%, ZnO 0-8%, B ２ O ３ 5-30%, Al ２ O ３ 5-15% of MgO + CaO + SrO + BaO 8-35%, and in molar ratio, ZnO / SiO ２is 0 to 0.2 and is substantially free of lead components. Here, "substantially free of lead components" means that the relevant components are not intentionally added as glass components, and does not mean that even unavoidable impurities are completely excluded. Specifically, it means that the content of the relevant components, including impurities, is less than 0.1 mass%. Furthermore, "MgO + CaO + SrO + BaO" refers to the total content of MgO, CaO, SrO, and BaO. "ZnO / SiO ２ " means that the content of ZnO is SiO ２ The value is divided by the content of

[0011] As described above, the glass for covering semiconductor elements of the present invention has the content ranges of each component regulated, which reduces the environmental load, improves acid resistance, and makes it easier to lower the firing temperature, making it suitable for covering semiconductor elements.

[0012] The semiconductor element coating material of the present invention preferably contains 75 to 100 mass % of glass powder made of the above-mentioned semiconductor element coating glass and 0 to 25 mass % of ceramic powder.

[0013] The semiconductor element coating material of the present invention has a thermal expansion coefficient of 20×10 in the temperature range of 30 to 300°C. －７ / ℃~55×10 －７ / ° C. or less. Here, the "coefficient of thermal expansion in the temperature range of 30 to 300° C." refers to a value measured using a push rod type thermal expansion coefficient measuring device.

[0014] According to the present invention, it is possible to provide a lead-free glass for covering semiconductor elements which has a small environmental impact, excellent acid resistance, and can be fired at a low temperature.

[0015] The glass for covering semiconductor elements of the present invention has a glass composition containing, in mol %, SiO ２ 35-65%, ZnO 0-8%, B ２ O ３ 5-30%, Al ２ O ３ 5-15% of MgO + CaO + SrO + BaO 8-35%, and in molar ratio, ZnO / SiO ２is 0 to 0.2, and is substantially free of lead components. The reasons for limiting the content of each component as described above are explained below. In the following explanation of the content of each component, % means mol% unless otherwise specified. In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0016] SiO ２ is a glass network-forming component and a component that enhances acid resistance. Its content is 35 to 65%, preferably 36 to 62%, 37 to 60%, 38 to 58%, 39 to 56%, and particularly preferably 40 to 55%. SiO ２ If the content of SiO is too small, the acid resistance is likely to decrease and vitrification becomes difficult. ２ If the content is too high, the firing temperature of the glass becomes high, which tends to deteriorate the characteristics of the semiconductor element in the coating process.

[0017] ZnO is a component that stabilizes glass. The ZnO content is preferably 0 to 8%, 0 to 6%, and particularly preferably 0.1 to 5%. If the ZnO content is too low, the glass will be more prone to devitrification during melting, making it difficult to obtain a homogeneous glass. On the other hand, if the ZnO content is too high, the glass will be more prone to phase separation during melting, crystals will be more likely to precipitate during firing, and acid resistance will be more likely to decrease.

[0018] ZnO / SiO ２ If the ratio is too large, the glass is likely to undergo phase separation during melting, crystals are likely to precipitate during firing, and acid resistance is likely to decrease. ２ is 0 to 0.2, preferably 0 to 0.18, 0 to 0.16, and particularly preferably 0 to 0.14.

[0019] B ２ O ３ is a component that forms a glass network and enhances the softening and fluidity of the glass. ２ O ３ The content of is 5 to 30%, preferably 8 to 27%, and particularly preferably 10 to 25%. ２ O ３If the content of B is too small, the crystallinity becomes strong, which impairs the softening and fluidity during coating, making it difficult to uniformly coat the surface of the semiconductor element. ２ O ３ If the content is too high, the acid resistance tends to decrease.

[0020] Al ２ O ３ is a component that stabilizes the glass. ２ O ３ The content of Al is 5 to 15%, preferably 7 to 13%, and particularly preferably 9 to 12%. ２ O ３ If the content of Al is too low, vitrification becomes difficult. ２ O ３ If the content is too high, the firing temperature may become too high.

[0021] MgO, CaO, SrO, and BaO are components that reduce the viscosity of the glass. The content of MgO + CaO + SrO + BaO is 8 to 35%, preferably 9 to 33%, and particularly preferably 11 to 31%. If the content of MgO + CaO + SrO + BaO is too low, the softening temperature of the glass tends to increase. On the other hand, if the content of MgO + CaO + SrO + BaO is too high, the thermal expansion coefficient tends to become too high, and acid resistance and insulating properties tend to decrease.

[0022] The preferred ranges of the contents of MgO, CaO, SrO, and BaO are as follows:

[0023] The MgO content is preferably 0 to 22%, 4 to 22%, 8 to 22%, 9 to 21%, and particularly preferably 10 to 20%.

[0024] The CaO content is preferably 0 to 15%, 1 to 14%, 2 to 13%, or 3 to 12%, and particularly preferably 4 to 11%.

[0025] The SrO content is preferably 0 to 10%, 0 to 8%, 0 to 6%, or 0 to 4%, and particularly preferably 0.1 to 2%.

[0026] The content of BaO is preferably 0 to 10%, 0 to 8%, 0 to 6%, or 0 to 4%, and particularly preferably 0.1 to 2%.

[0027] In addition to the above components, other components (e.g., MnO ２ , Bi ２ O ３ , Ta ２ O ５ , Nb ２ O ５ , CeO ２ , Sb ２ O ３ etc.) may be contained in an amount of up to 7% (preferably up to 3%).

[0028] From an environmental viewpoint, it is preferable that the material does not substantially contain lead components (for example, PbO, etc.) and does not substantially contain F or Cl. In addition, it is preferable that the material does not substantially contain alkaline components (Li, ２ O, Na ２ O and K ２ It is also preferable that the compound is substantially free of fluorine-containing compounds.

[0029] The glass for covering a semiconductor element of the present invention is preferably in a powder form, i.e., a glass powder. If processed into a glass powder, it can be easily used to cover the surface of a semiconductor element by, for example, a paste method or an electrophoretic coating method.

[0030] Average particle diameter D of glass powder ５０ is preferably 25 μm or less, particularly 15 μm or less. ５０ If the average particle diameter D of the glass powder is too large, it becomes difficult to form a paste. In addition, it becomes difficult to apply the paste by electrophoresis. ５０ The lower limit of the average particle diameter D is not particularly limited, but in reality it is 0.1 μm or more. ５０ " is a value measured on a volume basis and refers to a value measured by a laser diffraction method.

[0031] The glass for covering semiconductor elements of the present invention can be obtained, for example, by blending raw material powders of the respective oxide components to form a batch, melting the batch at about 1500°C for about 1 hour to vitrify the mixture, and then molding the mixture (and then pulverizing and classifying the mixture as necessary).

[0032] The semiconductor element coating material of the present invention contains glass powder made of the semiconductor element coating glass, which may be mixed with ceramic powder to form a composite powder, if necessary. The addition of ceramic powder makes it easier to adjust the thermal expansion coefficient. The ceramic powder is preferably cordierite powder.

[0033] The ceramic powder content is preferably 25% or less, less than 25%, and particularly less than 20%, relative to 100% by mass of the composite powder. That is, the composition is preferably 75 to 100% by mass of glass powder and 0 to 25% by mass of ceramic powder, or more than 75% by mass to 100% by mass of glass powder and 0 to less than 25% by mass of ceramic powder, and particularly more than 80% by mass to 100% by mass of glass powder and 0 to less than 20% by mass of ceramic powder. If the content of the ceramic powder is too high, the softening and fluidity of the glass is impaired, making it difficult to coat the surface of the semiconductor element.

[0034] Average particle diameter D of ceramic powder ５０ The average particle diameter D of the ceramic powder is preferably 30 μm or less, and particularly preferably 20 μm or less. ５０ If the average particle diameter D of the ceramic powder is too large, the surface smoothness of the coating layer is likely to decrease. ５０ The lower limit is not particularly limited, but in reality it is 0.1 μm or more.

[0035] In the semiconductor element coating material of the present invention, the thermal expansion coefficient in the temperature range of 30 to 300°C is 20 x 10 －７ / ℃~55×10 －７ / °C, especially 30 x 10 －７ / ℃~50×10 －７ If the thermal expansion coefficient is outside the above range, cracks, warping, etc. are likely to occur due to the difference in thermal expansion coefficient with the semiconductor element.

[0036] The material for covering a semiconductor element of the present invention is preferably fired at a temperature of not more than 900° C., particularly not more than 880° C. If the firing temperature is too high, there is a risk that the characteristics of the semiconductor element may be impaired in the coating step.

[0037] The present invention will be described in detail below based on examples. Note that the following examples are merely illustrative and the present invention is not limited to the following examples in any way.

[0038] Table 1 shows examples of the present invention (samples Nos. 1 to 4) and comparative examples (samples Nos. 5 to 9).

[0039] Each sample was prepared as follows: First, raw material powders were mixed to form a batch having the glass composition shown in the table, and the batch was melted at 1500°C for 1 hour to form a glass. The molten glass was then formed into a film, pulverized in a ball mill, and classified using a 350-mesh sieve to determine the average particle diameter D ５０ In Sample No. 3, the amount of cordierite powder (average particle diameter D ５０ : 12 μm) was added to form a composite powder.

[0040] The softening point, thermal expansion coefficient, and acid resistance of each sample were evaluated, and the results are shown in Table 1.

[0041] The softening point was measured using a macro-type differential thermal analyzer. Specifically, the value of the fourth inflection point in the chart obtained by measuring each glass powder sample using the macro-type differential thermal analyzer was taken as the softening point. The firing temperature was set to a temperature 20°C higher than the softening point.

[0042] The thermal expansion coefficient is a value measured in the temperature range of 30 to 300°C using a push rod type thermal expansion coefficient measuring device.

[0043] The acid resistance was evaluated as follows. Each sample was press-molded to a size of about 20 mm in diameter and 4 mm in thickness, and then fired at a temperature 20°C above the softening point to produce a sintered body. The sintered body was immersed in 30% nitric acid at 25°C for 1 minute, and the mass change per unit area was calculated from the mass loss. Note that a mass change per unit area of ​​1.0 mg / cm ２ Those less than 1.0 mg / cm are marked as "○" ２ The above were marked as "X".

[0044] As is clear from Table 1, Samples No. 1 to 4 have a thermal expansion coefficient of 44×10 －７ / ℃~48×10 －７ / °C, the firing temperature was 900°C or less, and the evaluation of acid resistance was also good. Therefore, Samples No. 1 to 4 are considered to be suitable as materials for covering semiconductor elements. On the other hand, Sample No. 5 was fired at a high temperature. Sample No. 6 experienced phase separation during melting. Sample No. 7 had low acid resistance. Sample No. 8 had low acid resistance. Sample No. 9 was fired at a high temperature.

Claims

1. The glass composition is, in mole percent, SiO ２ 35-65%, ZnO 0-8%, B ２ O ３ 5-30%, Al ２ O ３ 5-15%, MgO+CaO+SrO+BaO 8-35%, and ZnO / SiO ２ A glass for covering semiconductor elements, characterized in that the glass has a viscosity of 0 to 0.2 and is substantially free of lead components.

2. A material for covering semiconductor elements, comprising 75 to 100% by mass of glass powder made of the glass for covering semiconductor elements according to claim 1, and 0 to 25% by mass of ceramic powder.

3. The thermal expansion coefficient in the temperature range of 30 to 300°C is 20 x 10 －７ / ℃~55×10 －７ 3. The semiconductor element coating material according to claim 2, wherein the temperature is 100° C. / ° C.

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