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_235～65％、ZnO 25～50％、SiO_2+ZnO 65％以上且低于90％、Al_2O_32～14％、B_2O_30～10％、MgO+CaO 3～15％,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 35～65％、ZnO 25～50％、SiO 2 + ZnO 65% or more and less than 90%, Al 2 O 3 2～14％、B 2 O 3 0 to 10%, MgO + CaO 3 to 15%, and substantially no lead component.)

1. A glass for coating a semiconductor element, characterized by comprising SiO in mol% as a glass composition₂ 35％～65％、ZnO 25％～50％、SiO₂+ ZnO 65% or more and less than 90%, Al₂O₃ 2％～14％、B₂O₃0 to 10% and MgO + CaO 3 to 15%, and substantially no lead component.

2. A semiconductor element-coating material comprising a glass powder, wherein the glass powder comprises the semiconductor element-coating glass according to claim 1.

3. The material for coating a semiconductor element according to claim 2, wherein the material has a property of precipitating crystals by heat treatment.

4. The material for coating a semiconductor element according to claim 3, wherein the coefficient of thermal expansion in the temperature range of 30 to 300 ℃ is 20 x 10 by the heat treatment^-7over/DEG C and 48X 10^-7Below/° c.

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. Further, the zinc-based glass contains a small amount of lead component and bismuth component, and therefore cannot be said to be completely harmless to the environment.

Further, zinc-based glass tends to have a high thermal expansion coefficient, and when the surface of a semiconductor element such as Si is coated, cracks may occur in the semiconductor element or warpage may occur.

On the other hand, if SiO is contained in the glass composition₂When the content of (B) is increased, the thermal expansion is promotedThe coefficient is lowered and the reverse voltage in the semiconductor element is increased, but there is a problem that the reverse leakage current of the semiconductor element becomes large. 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, a low thermal expansion coefficient, 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-ZnO-Al₂O₃The present invention is proposed as a glass capable of solving the above technical problems. That is, the glass for coating a semiconductor element of the present invention is characterized by containing SiO in mol% as a glass composition₂ 35～65％、ZnO 25～50％、SiO₂+ ZnO 65% or more and less than 90%, Al₂O₃ 2～14％、B₂O₃0 to 10%, MgO + CaO 3 to 15%, and substantially no lead component. Here, "Si₂+ ZnO "means SiO₂And the total amount of ZnO. "MgO + CaO" refers to 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 glass for coating a semiconductor element of the present invention limits the content ranges of the respective components as described above. Thus, the environmental load is small, the thermal expansion coefficient is low, and the surface charge density is reduced. 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 a glass powder containing the above-mentioned semiconductor element-coating glass.

The semiconductor element coating material of the present invention preferably has a property of precipitating by heat treatment crystallization. This can reduce the thermal expansion coefficient, and can easily avoid the occurrence of cracks or warpage in the semiconductor element.

In addition, the material for covering a semiconductor element of the present invention is preferably heat-treated so that the coefficient of thermal expansion in a temperature range of 30 to 300 ℃ is 20X 10^-7over/DEG C and 48X 10^-7Below/° c. This makes it easy to avoid the occurrence of cracks and warpage in the semiconductor element. 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 35～65％、ZnO 25～50％、SiO₂+ ZnO 65% or more and less than 90%, Al₂O₃ 2～14％、B₂O₃0 to 10%, MgO + CaO 3 to 15%, and substantially no lead component. The reason for limiting the content of each component 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 preferably 35 to 65%, 37 to 60%, particularly 40 to 55%. If SiO₂When the content of (b) is too small, the thermal expansion coefficient tends to increase, and the acid resistance tends to decrease. On the other hand, if SiO₂When the content of (b) is too large, the firing temperature becomes too high, and the coating layer cannot be formed at an appropriate temperature.

ZnO is a component for stabilizing the glass. The content of ZnO is 25 to 50%, preferably 30 to 45%. 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.

SiO₂The total amount of ZnO and ZnO is 65% or more and less than 90%, preferably 75 to 88%. If SiO₂When the total amount of ZnO and ZnO is outside the above range, devitrification is strong and melting and molding become difficult.

Al₂O₃A component for stabilizing the glass and adjusting the surface charge density. Al (Al)₂O₃The content of (b) is 2 to 14%, preferably 4 to 12%, particularly 5 to 10%. If Al is present₂O₃When the content of (b) is too small, the glass tends to devitrify during molding. On the other hand, if Al₂O₃If the content of (b) is too large, the surface charge density may become too large.

B₂O₃Is a network-forming component of glass and is a component for improving softening fluidity. B is₂O₃The content of (b) is 0 to 10%, preferably 0 to 7%, 0 to 3%, particularly 0% or more and less than 1%. If B is₂O₃Too much content of (b) makes crystallization of the glass difficult, and also tends to lower acid resistance.

MgO and CaO are components that reduce the viscosity of the glass. The total amount of MgO and CaO is 3 to 15%, preferably 5 to 10%. 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 becomes too high, and the semiconductor element may be warped, have reduced chemical resistance, or have reduced insulation properties. The content of MgO is preferably 0 to 15%, particularly 1 to 10%. The preferable content of CaO is 0 to 10%, particularly 0 to 5%.

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)。

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

The semiconductor element-coating material of the present invention preferably contains a powder obtained by processing the above-mentioned semiconductor element-coating glass into a powder, that is, preferably contains a glass powder. 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 powder₅₀If it is too large, pasting 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 powder can be obtained, for example, by preparing a batch by mixing 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 preferably has a property of precipitating crystals by heat treatment, that is, the glass powder is preferably crystalline. When the coating layer is formed by crystallizing the glass powder, the thermal expansion coefficient of the coating layer is likely to be lowered.

Examples of the method for crystallizing the glass powder include a method of heat-treating the glass powder at a temperature not lower than the crystallization temperature of the glass powder, a method of crystallizing the glass powder and a crystallization aid (TiO)₂、ZrO₂Etc.) are mixed and heat-treated.

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 48X 10^-7Less than/° C, particularly 30X 10^-745X 10 ℃ C or higher^-7Below/° c. If the thermal expansion coefficient is outside the above rangeCracks, warpage, and the like due to a difference in thermal expansion coefficient with the semiconductor element are likely to occur.

In the case where the material for covering a semiconductor element of the present invention is used to cover a semiconductor element surface of 1500V or less, for example, the surface charge density is preferably 10 × 10¹¹/cm²The following, in particular 8X 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.

For each sample, the thermal expansion coefficient, the amount of warpage, and the surface charge density were evaluated. The results are shown in table 1. In samples nos. 1 to 4, the coefficient of thermal expansion, the amount of warpage, and the surface charge density were evaluated for a material obtained by crystallizing a glass powder.

The coefficient of thermal expansion is: the value obtained by using a material crystallized by heat treatment at 800 to 900 ℃ for 10 minutes as a measurement sample and measuring the temperature in the range 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 at a temperature at which crystallization proceeds 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 amount of warpage was measured in the following manner. First, the silicon substrate is placed on a stage so as to project downward, and any point on the circumference of the silicon substrate is fixed to the stage by a double-sided tape. Next, the height displacement of the silicon substrate on a straight line passing through the fixed point and the circle center is measured using a laser displacement meter. The height difference between the highest point and the lowest point of the obtained displacement was calculated, and the difference was evaluated as the amount of warpage. If the warpage amount is 300 μm or less, the warpage amount can be said to be small.

As is clear from Table 1, the surface charge densities of samples Nos. 1 to 4 were 8X 10¹¹/cm²The warpage amount was evaluated as follows. From this fact, it is considered that sample Nos. 1 to 4 are suitable as semiconductor element-coating materials for coating low-voltage semiconductor elements.

On the other hand, sample No.5 was poor in the evaluation of the amount of warpage. Sample No.6 was too devitrified to be molded into glass.