阅读说明：本技术 半导体元件被覆用玻璃以及使用其的半导体被覆用材料 (Glass for coating semiconductor element and material for coating semiconductor using same ) 是由 广濑将行 于 2019-09-13 设计创作，主要内容包括：本发明的半导体元件被覆用玻璃的特征在于,作为玻璃组成,以摩尔％计含有SiO_218～43％、B_2O_35～21％、Al_2O_38～21％、ZnO 10～25％、MgO+CaO 10～25％,且实质上不含铅成分。(The glass for coating a semiconductor element of the present invention is characterized by containing SiO in mol% as a glass composition 2 18～43％、B 2 O 3 5～21％、Al 2 O 3 8 to 21%, ZnO 10 to 25%, MgO + CaO 10 to 25%, and substantially no lead component.)

1. A glass for coating a semiconductor element, characterized by comprising SiO in mol% as a glass composition₂ 18％～43％、B₂O₃ 5％～21％、Al₂O₃8 to 21 percent, ZnO 10 to 25 percent and MgO + CaO 10 to 25 percent, and does not substantially contain lead.

2. A semiconductor element-coating material characterized by containing 75 to 100% by mass of a glass powder containing the glass for coating a semiconductor element according to claim 1 and 0 to 25% by mass of a ceramic powder.

3. The material for coating a semiconductor element as claimed in claim 2, wherein the coefficient of thermal expansion in the temperature range of 30 ℃ to 300 ℃ is 20 x 10^-7over/DEG C and 55X 10^-7/℃The following.

Technical Field

The present invention relates to a glass for coating a semiconductor element and a semiconductor coating material using the same.

Background

In a semiconductor device such as a silicon diode or a transistor, a surface of the semiconductor device including a P — N junction portion is usually covered with glass. This stabilizes the surface of the semiconductor element and suppresses deterioration of the characteristics with time.

Examples of the characteristics required for the glass for coating a semiconductor element include: (1) a thermal expansion coefficient suitable for the thermal expansion coefficient of the semiconductor element so that cracks and the like due to a difference in thermal expansion coefficient from the semiconductor element do not occur; (2) coating at a low temperature (for example, 900 ℃ or lower) to prevent deterioration of the characteristics of the semiconductor element; (3) impurities such as alkali components which adversely affect the surface of the semiconductor element are not contained; and so on.

Conventionally, ZnO-B has been known as a glass for coating semiconductor elements₂O₃-SiO₂Isozinc-based glass, PbO-SiO₂-Al₂O₃Based glass, PbO-SiO₂-Al₂O₃-B₂O₃At present, lead-based glasses such as glass-based glasses are made of PbO-SiO from the viewpoint of workability₂-Al₂O₃Based glass, PbO-SiO₂-Al₂O₃-B₂O₃Lead-based glasses such as a glass-based glass have been mainly used (for example, see patent documents 1 to 4).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. Sho-48-43275

Patent document 2: japanese laid-open patent publication No. 50-129181

Patent document 3: japanese examined patent publication (Kokoku) No. 1-49653

Patent document 4: japanese patent laid-open No. 2008-162881

Disclosure of Invention

Problems to be solved by the invention

However, the lead component of lead-based glass is a component harmful to the environment. Since the zinc-based glass contains a small amount of lead component and bismuth component, it cannot be said that the glass is completely harmless to the environment.

In addition, zinc-based glasses have the following problems compared to lead-based glasses: the chemical durability is deteriorated and the coating layer is easily corroded in the acid treatment process after the formation. Therefore, it is necessary to further form a protective film on the surface of the coating layer and then perform an acid treatment.

On the other hand, if SiO is contained in the glass composition₂When the content (b) is increased, the acid resistance is improved and the reverse voltage of the semiconductor element is increased, but the reverse leakage current of the semiconductor element is increased. In particular, in the low-voltage semiconductor element, it is preferable to suppress reverse leakage current and reduce the surface electrochemical density, as compared with the increase in reverse voltage, and therefore the above-described problem becomes more problematic.

Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass for covering a semiconductor element, which has a small environmental load, excellent acid resistance, and a low surface charge density.

Means for solving the problems

As a result of intensive studies, the inventors of the present application have found that by using SiO having a specific glass composition₂-B₂O₃-Al₂O₃The present invention is based on the idea that the above technical problem can be solved by a ZnO glass. That is, the glass for coating a semiconductor element of the present invention is characterized by containing SiO in mol% as a glass composition₂ 18～43％、B₂O₃ 5～21％、Al₂O₃8 to 21%, ZnO 10 to 25%, MgO + CaO 10 to 25%, and substantially no lead component. Here, "MgO + CaO" means the total amount of MgO and CaO. In addition, "substantially free" means that the component is not intentionally added as a glass component, and does not mean that impurities that are inevitably mixed are completely excluded. Specifically, the content of the component including impurities is less than 0.1% by mass.

The semiconductor element-coating glass of the present invention has a small environmental load, improved acid resistance, and a reduced surface charge density by limiting the content range of each component as described above. As a result, the present invention can be suitably used for coating a low-voltage semiconductor element.

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

In addition, the material for covering a semiconductor element of the present invention preferably has a thermal expansion coefficient of 20X 10 in a temperature range of 30 to 300 DEG C^-7over/DEG C and 55X 10^-7Below/° c. The "coefficient of thermal expansion in the temperature range of 30 to 300 ℃ is a value measured by a pusher-type coefficient of thermal expansion measuring apparatus.

Detailed Description

The glass for coating a semiconductor element of the present invention is characterized by containing SiO in mol% as a glass composition₂ 18～43％、B₂O₃ 5～21％、Al₂O₃8 to 21%, ZnO 10 to 25%, MgO + CaO 10 to 25%, and substantially no lead component. The reason why the content of each component is limited will be described below. In the following description of the content of each component,% represents mol% unless otherwise specified.

SiO₂Is a network-forming component of glass and is a component for improving acid resistance. SiO 2₂The content of (b) is 18 to 43%, preferably 20 to 40%, particularly 22 to 36%. If SiO₂If the content of (b) is too small, the acid resistance tends to be lowered. On the other hand, if SiO₂When the content of (b) is too large, the devitrification at the time of melting becomes strong, and it becomes difficult to obtain a homogeneous glass.

B₂O₃Is a network-forming component of glass and is a component for improving softening fluidity. B is₂O₃The content of (b) is 5 to 21%, preferably 5 to 18%, particularly 7 to 15%. If B is₂O₃If the content of (b) is too small, crystallinity becomes strong, and therefore softening fluidity is impaired at the time of coating, and uniform coating on the surface of the semiconductor element becomes difficult. On the other hand, if B₂O₃When the content of (b) is too large, the thermal expansion coefficient tends to be undesirably high, and the acid resistance tends to be lowered.

Al₂O₃A component for stabilizing the glass and adjusting the surface charge density. Al (Al)₂O₃In an amount of 8 to 21% is preferably 5 to 20%, particularly 8 to 18%. If Al is present₂O₃When the content of (b) is too small, the glass is easily devitrified. On the other hand, if Al₂O₃If the content of (b) is too large, the surface charge density may become too large.

ZnO is a component for stabilizing the glass. The content of ZnO is 10 to 25%, preferably 12 to 22%. If the content of ZnO is too small, the devitrification at the time of melting becomes strong, and it becomes difficult to obtain a homogeneous glass. On the other hand, if the content of ZnO is too large, the acid resistance is liable to decrease.

MgO and CaO are components that reduce the viscosity of the glass. The total amount of MgO and CaO is 10 to 25%, preferably 12 to 20%. When the total amount of MgO and CaO is too small, the firing temperature of the glass tends to increase. On the other hand, if the total amount of MgO and CaO is too large, the thermal expansion coefficient may become too high, the acid resistance may be lowered, and the insulation may be lowered. The content of MgO is preferably 0 to 20%, particularly 0 to 5%. The preferable content of CaO is 1 to 25%, particularly 10 to 20%.

In addition to the above components, other components (e.g., SrO, BaO, MnO) may be contained₂、Ta₂O₅、Nb₂O₅、CeO₂、Sb₂O₃Etc.) to 7% (preferably to 3%).

From the viewpoint of environment, it is preferable that the alloy contains substantially no lead component (e.g., PbO) and substantially no Bi₂O₃F, Cl. Further, it is preferable that the composition does not substantially contain an alkali component (Li) which exerts an adverse effect on the surface of the semiconductor element₂O、Na₂O and K₂O)。

The glass for coating a semiconductor element of the present invention is preferably in a powder form, that is, preferably in a glass powder form. When processed into a glass powder, the surface of the semiconductor element can be easily coated by, for example, a paste method, an electrophoretic coating method, or the like.

Average particle diameter D of glass powder₅₀Preferably 25 μm or less, particularly 15 μm or less. If the average particle diameter D of the glass powder₅₀When too large, the paste will formIt becomes difficult. In addition, powder adhesion by the electrophoresis method also becomes difficult. The average particle diameter D of the glass powder₅₀The lower limit of (B) is not particularly limited, but is actually 0.1 μm or more. The "average particle diameter D" is₅₀"is a value measured on a volume basis and means a value measured by a laser diffraction method.

The glass for coating a semiconductor element of the present invention is obtained, for example, by preparing a batch by blending raw material powders of the respective oxide components, melting the batch at about 1500 ℃ for about 1 hour, vitrifying the molten batch, and then molding the vitrified batch (thereafter, optionally, pulverizing and classifying the vitrified batch).

The semiconductor element-coating material of the present invention contains a glass powder made of the above-mentioned semiconductor element-coating glass, but may be mixed with a ceramic powder as needed to prepare a composite powder. If ceramic powder is added, it becomes easy to adjust the thermal expansion coefficient.

The ceramic powder is preferably less than 25% by mass, particularly preferably less than 20% by mass, relative to 100 parts by mass of the glass powder. If the content of the ceramic powder is too large, the softening fluidity of the glass is impaired, and the surface of the semiconductor element is hardly coated.

Average particle diameter D of ceramic powder₅₀Preferably 30 μm or less, particularly 20 μm or less. If the average particle diameter D of the ceramic powder₅₀If the amount is too large, the surface smoothness of the coating layer tends to be reduced. Average particle diameter D of ceramic powder₅₀The lower limit of (B) is not particularly limited, but is actually 0.1 μm or more.

The material for coating a semiconductor element of the present invention preferably has a thermal expansion coefficient of 20X 10 in a temperature range of 30 to 300 DEG C^-7over/DEG C and 55X 10^-7Below/° c, in particular 30 × 10^-7over/DEG C and 50X 10^-7Below/° c. If the thermal expansion coefficient is outside the above range, cracks, warpage, and the like due to the difference in thermal expansion coefficient from the semiconductor element are likely to occur.

The material for coating a semiconductor element of the present invention is, for example, a material for coating a surface of a semiconductor element of 1000V or lessIn this case, the surface charge density is preferably 6X 10¹¹/cm²In particular, 5X 10¹¹/cm²The following. If the surface charge density is too high, the withstand voltage is high, but the leakage current tends to increase. The "surface charge density" refers to a value measured by the method described in the column of the example described later.

Examples

The present invention will be described in detail below based on examples. The following examples are merely illustrative. The present invention is not limited to the following examples.

Table 1 shows examples of the present invention (sample Nos. 1 to 4) and comparative examples (sample Nos. 5 and 6).

[ Table 1]

Each sample was prepared as follows. First, raw material powders were blended so as to have glass compositions shown in the table to prepare a batch, and the batch was melted at 1500 ℃ for 1 hour to be vitrified. Next, the molten glass was formed into a film shape, and then pulverized by a ball mill, and classified by a 350-mesh sieve to obtain an average particle diameter D₅₀12 μm glass powder. In sample No.4, 15 mass% of cordierite powder (average particle diameter D) was added to the obtained glass powder₅₀: 12 μm) to prepare a composite powder.

The thermal expansion coefficient, surface charge density and acid resistance were evaluated for each sample. The results are shown in table 1.

The thermal expansion coefficient is measured at a temperature of 30 to 300 ℃ by using a pusher-type thermal expansion coefficient measuring apparatus.

The surface charge density was measured in the following manner. First, each sample was dispersed in an organic solvent, adhered to the surface of a silicon substrate by electrophoresis so as to have a constant film thickness, and then fired to form a coating layer. Next, an aluminum electrode was formed on the surface of the coating layer, and then the change in capacitance in the coating layer was measured using a C — V meter to calculate the surface charge density.

The acid resistance was evaluated in the following manner. Each sample was press-molded into a size of about 20mm in diameter and 4mm in thickness, and then fired to prepare a granular sample, and the change in mass per unit area was calculated from the mass decrease after the sample was immersed in 30% nitric acid at 25 ℃ for 1 minute, and used as an index of acid resistance. The change in mass per unit area is less than 1.0mg/cm²The case of (2) was set to ". smallcircle", and the change in mass per unit area was 1.0mg/cm²The above case is set to "x".

As is clear from Table 1, the surface charge densities of samples Nos. 1 to 4 were 6X 10¹¹/cm²The acid resistance was also evaluated as follows. From this it can be considered that: sample Nos. 1 to 4 are suitable as semiconductor element-coating materials for coating low-voltage semiconductor elements.

On the other hand, the samples No.5 and 6 were poor in the evaluation of the acid resistance test. Further, sample No.6 has a high thermal expansion coefficient and a high surface charge density.