Glass for coating semiconductor element, and sintered body for coating semiconductor element

Abstract

Provided is a glass for coating a semiconductor element, the glass having a low environmental impact and being resistant to devitrification during a melting step.　The glass is characterized by: having a glass composition which contains, in mol%, 60-80% of SiO2 + ZnO, 0-1% of B2O3, 2-12% of Al2O3, and 12-30% of MgO + CaO, wherein (SiO2 + Zno) / Al2O3 is 5.5 or more and SiO2 / ZnO is 1.8 or more in terms of the molar ratio; and being substantially free of a lead component.

Description

Glass for coating semiconductor elements and sintered body for coating semiconductor elements

[0001] The present invention relates to glass for coating semiconductor elements and a sintered body for coating semiconductor elements.

[0002] For semiconductor elements such as silicon diodes and transistors, the surface including the PN junction of the semiconductor element is generally coated with glass. This stabilizes the surface of the semiconductor element and can suppress characteristic deterioration over time.

[0003] Characteristics required for glass for coating semiconductor elements include: (1) the coefficient of thermal expansion matches that of the semiconductor element, so that cracks or the like do not occur due to the difference in coefficient of thermal expansion with the semiconductor element; (2) coating can be performed at low temperature (for example, 900° C. or lower) to prevent characteristic deterioration of the semiconductor element; (3) the glass does not contain impurities such as alkali components that adversely affect the surface of the semiconductor element.

[0004] Conventionally, as glass for coating semiconductor elements, ZnO-B ２ O ３ -SiO ２ based zinc-based glass, PbO-SiO ２ -Al ２ O ３ based glass, PbO-SiO ２ -Al ２ O ３ -B ２ O ３ based lead-based glasses are known, but at present, from the viewpoint of workability, PbO-SiO ２ -Al ２ O ３ based glass, PbO-SiO ２ -Al ２ O ３ -B ２ O ３ based lead-based glasses are the mainstream (see, for example, Patent Documents 1 to 4).

[0005] JP-A-48-43275, JP-A-50-129181, JP-B-1-49653, JP-A-2008-162881

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

[0007] Furthermore, zinc-based glass had the problem of being more prone to devitrification during the melting process compared to lead-based glass.

[0008] Therefore, the present invention has been made in view of the above circumstances, and its technical objective is to provide a glass for semiconductor device coating that has a low environmental impact and is less prone to devitrification during the melting process.

[0009] The semiconductor device coating glass of the present invention has a glass composition of SiO in mol%. ２ +ZnO 60-80%, B ２ O ３ 0-1%, Al ２ O ３ It contains 2-12% MgO + CaO and 12-30% molar ratio of (SiO ２ +ZnO) / Al ２ O ３ If 5.5 or higher, SiO ２ It is characterized by having a ZnO content of 1.8 or more and being substantially free of lead components. Here, "SiO ２ "+ZnO" means SiO ２ This is the total amount of MgO and ZnO. "MgO + CaO" is the total amount of MgO and CaO. "(SiO ２ +ZnO) / Al ２ O ３ " is SiO ２ and the total amount of ZnO content Al ２ O ３ This is the value obtained by dividing by the content of [the substance]. In this invention, "substantially does not contain [the substance]" means that the substance in question is not intentionally added as a glass component, and does not mean that impurities that are inevitably mixed in are completely eliminated. Specifically, it means that the content of the substance in question, including impurities, is less than 0.1% by mass.

[0010] The semiconductor element coating glass of the present invention has a thermal expansion coefficient of 20 to 55 × 10 in the temperature range of 30 to 300°C. －７It is preferable that the value is / °C. Here, "thermal expansion coefficient in the temperature range of 30 to 300°C" refers to the value measured by a push-rod type thermal expansion coefficient measuring device.

[0011] The sintered body for semiconductor device coating of the present invention has a composition of SiO in mol%. ２ +ZnO 60-80%, B ２ O ３ 0-1%, Al ２ O ３ It contains 2-12% MgO + CaO and 12-30% molar ratio of (SiO ２ +ZnO) / Al ２ O ３ If 5.5 or higher, SiO ２ It is characterized by having a ZnO content of 1.8 or higher and being substantially free of lead components.

[0012] According to the present invention, it is possible to provide a glass for semiconductor device coatings that has a low environmental impact and is less prone to devitrification during the melting process.

[0013] The semiconductor device coating glass of the present invention has a glass composition of SiO in mol%. ２ +ZnO 60-80%, B ２ O ３ 0-1%, Al ２ O ３ It contains 2-12% MgO + CaO and 12-30% molar ratio of (SiO ２ +ZnO) / Al ２ O ３ If 5.5 or higher, SiO ２ It is characterized by having a ZnO content of 1.8 or higher and being substantially free of lead components. The reasons for limiting the content of each component are explained below. In the following explanation of the content of each component, percentages refer to mole percentages unless otherwise specified.

[0014] SiO ２ ZnO is a component that stabilizes glass. ２ The amount of +ZnO is 60-80%, preferably 62-78%, 64-76%, and particularly preferably 66-74%. SiO ２ If there is too little +ZnO, devitrification is likely to occur during the melting process. On the other hand, SiO ２If there is too much +ZnO, the softening point of the glass tends to rise significantly, resulting in a higher firing temperature.

[0015] SiO ２ The content is preferably 30-60%, 35-58%, 40-56%, and particularly 42-54%.

[0016] The ZnO content is preferably 10-40%, 15-35%, 17-30%, and particularly 18-25%.

[0017] In molar ratio, SiO ２ The ZnO content is 1.8 or higher, preferably 1.9 or higher, and particularly preferably 2 or higher. ２ If the amount of ZnO is too small, it is prone to devitrification during the melting process. SiO ２ There is no particular upper limit to the ZnO ratio, but in reality it is 6 or less.

[0018] B ２ O ３ This is a component that forms the network of glass and enhances its softening and fluidity. ２ O ３ The content is 0-1%, preferably 0-0.5%, and especially preferably substantially absent. ２ O ３ If the content is too high, it becomes prone to devitrification during the melting process.

[0019] Al ２ O ３ Al is a component that stabilizes glass. ２ O ３ The content is 2-12%, preferably 3-11%, and particularly preferably 4-10%. ２ O ３ If the content of is too low, it becomes difficult to vitrify. On the other hand, Al ２ O ３ If the content is too high, it becomes prone to devitrification during the melting process.

[0020] In molar ratio, (SiO ２ +ZnO) / Al ２ O ３ It is 5.5 or higher, and preferably 5.7 or higher, 6.0 or higher, 6.2 or higher, 6.5 or higher, 6.8 or higher, and especially preferably 7 or higher. (SiO２ +ZnO) / Al ２ ₂O₃ ３ If it is too small, devitrification is prone to occur in the melting step. (SiO₂ ２ +ZnO) / Al ２ ₂O₃ ３ The upper limit is not particularly limited, but is realistically 40 or less.

[0021] MgO and CaO are components that lower the viscosity of glass. The content of MgO+CaO is 12 to 30%, preferably 15 to 28%, and particularly preferably 20 to 26%. If MgO+CaO is too low, the softening temperature of glass tends to increase, and as a result, the firing temperature tends to be high. On the other hand, if the content of MgO+CaO is too high, there are risks that the coefficient of thermal expansion becomes excessively high, acid resistance decreases, and insulation performance decreases.

[0022] The content of MgO is preferably 2 to 20%, more preferably 3 to 15%, and particularly preferably 4 to 13%.

[0023] The content of CaO is preferably 2 to 20%, more preferably 3 to 15%, and particularly preferably 4 to 13%.

[0024] In addition to the above components, other components (for example, SrO, BaO, MnO₂ ２ , Ta ２ ₂O₅ ５ , Nb ２ ₂O₅ ５ , CeO₂ ２ , Sb ２ ₂O₃ ３ etc.) may be contained up to 7% (preferably up to 3%).

[0025] From the viewpoint of environmental protection, it is preferable that the glass substantially does not contain lead components (e.g., PbO, etc.), and also substantially does not contain Bi₂O₃ ２ , F, and Cl ３ . In addition, it is preferable that the glass substantially does not contain alkali components (Li₂O ２ , Na₂O ２ and K₂O ２ ) that adversely affect the surface of semiconductor elements.

[0026] The glass for coating a semiconductor element of the present invention has a coefficient of thermal expansion of 20 to 55×10 －７ ⁻⁷ / °C in the temperature range of 30 to 300°C, particularly 30 to 50×10－７ It is preferable that the thermal expansion coefficient is within the above range. If the thermal expansion coefficient falls outside the above range, cracks, warping, etc. are more likely to occur due to the difference in thermal expansion coefficients with the semiconductor element.

[0027] The glass for coating semiconductor devices of the present invention preferably has a firing temperature of 900°C or lower, and more preferably 880°C or lower. If the firing temperature is too high, there is a risk that the properties of the semiconductor device will be impaired during the coating process.

[0028] The semiconductor device coating glass of the present invention is preferably in powder form. Processing it into a powder allows for easy coating of the semiconductor device surface using methods such as paste coating or electrophoretic coating.

[0029] Average particle size D of glass powder ５０ The average particle size D of the glass powder is preferably 25 μm or less, and particularly preferably 15 μm or less. ５０ If the particle size is too large, it becomes difficult to form a paste. Furthermore, paste application by electrophoresis also becomes difficult. Note that the average particle size D of the glass powder is... ５０ The lower limit is not particularly limited, but in reality it is 0.1 μm or larger. Note that "Average particle diameter D ５０ This refers to a value measured on a volume basis, and specifically to a value measured by laser diffraction.

[0030] The semiconductor device coating glass of the present invention may be mixed with ceramic powder as needed to form a composite powder. Adding ceramic powder makes it easier to adjust the coefficient of thermal expansion.

[0031] The amount of ceramic powder is preferably less than 25 parts by mass, and more preferably less than 20 parts by mass, per 100 parts by mass of glass powder. If the ceramic powder content is too high, the softening and fluidity of the glass will be impaired, making it difficult to coat the surface of the semiconductor device.

[0032] Average particle size D of ceramic powder ５０ The average particle size D of the ceramic powder is preferably 30 μm or less, and particularly preferably 20 μm or less. ５０ If the average particle size D of the ceramic powder is too large, the surface smoothness of the coating layer tends to decrease. ５０ The lower limit is not particularly limited, but in practice it is 0.1 μm or larger.

[0033] Next, an example of a method for manufacturing a semiconductor device coating glass and a semiconductor device coating sintered body according to the present invention will be described.

[0034] First, raw material powders, blended to achieve the desired glass composition, are melted at 1300-1550°C for 1-2 hours until a homogeneous glass is obtained. Next, the resulting molten glass is formed into a film or the like, then crushed and classified to produce powdered glass for semiconductor device coatings.

[0035] Next, the powdered semiconductor device coating glass is coated onto the surface of the semiconductor device using, for example, a paste method or electrophoretic coating method. After that, by heat treatment, the semiconductor device coating glass that has coated the surface of the semiconductor device becomes a sintered body for semiconductor device coating that does not have crystal deposition. It is preferable that the sintered body for semiconductor device coating has the same composition range as the glass composition of the semiconductor device coating glass.

[0036] The present invention will be described in detail below based on the following examples. Note that the following examples are merely illustrative. The present invention is not limited in any way to the following examples.

[0037] Table 1 shows examples of the present invention (samples No. 1 to 6) and comparative examples (samples No. 7 to 9).

[0038]

[0039] Each sample was prepared as follows: First, the raw material powders were mixed to achieve the glass composition shown in the table and formed into batches, which were then melted at 1500°C for 1 hour to vitrify. Next, the molten glass was formed into a film, then crushed in a ball mill, and classified using a 350-mesh sieve to determine the average particle size D. ５０ A glass powder with a particle size of 12 μm was obtained.

[0040] For each sample, the coefficient of thermal expansion and resistance to devitrification were evaluated. The results are shown in Table 1.

[0041] The thermal expansion coefficient was measured using a push-rod type thermal expansion coefficient measuring device in a temperature range of 30 to 300°C.

[0042] Devitrification resistance was evaluated as follows: 100g of the glass film of each sample was placed in a platinum crucible and held at 1100°C for 8 hours. After that, the presence of devitrified material was visually confirmed. Subsequently, it was held at 1300°C for 10 minutes. If no devitrified material was visually confirmed, it was marked as "○"; if devitrified material was confirmed, it was marked as "×".

[0043] As is clear from Table 1, samples No. 1 to 6 showed high resistance to devitrification. Furthermore, when samples No. 1 to 6 were fired at the temperatures listed in the table for 10 minutes, no crystals precipitated. On the other hand, samples No. 7 to 9 showed low resistance to devitrification.

Claims

1. A glass for coating a semiconductor element, characterized in that it comprises, as a glass composition, in mol%, SiO ２ +ZnO 60 to 80%, B ２ O ３ 0 to 1%, Al ２ O ３ 2 to 12%, MgO+CaO 12 to 30%, and in terms of molar ratio, (SiO ２ +ZnO) / Al ２ O ３ is 5.5 or more, SiO ２ / ZnO is 1.8 or more, and does not substantially contain a lead component.

2. The coefficient of thermal expansion in the temperature range of 30 to 300°C is 20 to 55 × 10⁻⁶. －７ The semiconductor device coating glass according to claim 1, characterized in that it is / ℃.

3. In terms of composition, SiO in mol% ２ +ZnO 60-80%, B ２ O ３ 0-1%, Al ２ O ３ It contains 2-12% MgO + CaO and 12-30% molar ratio of (SiO ２ +ZnO) / Al ２ O ３ If 5.5 or higher, SiO ２ A sintered body for semiconductor device coating, characterized by having a ZnO content of 1.8 or more and substantially free of lead components.

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