TWI615370B - Semiconductor component coated glass - Google Patents

Abstract

The present invention provides a glass that has a small load on the environment, excellent chemical durability, and low surface charge density, and is particularly suitable for coating semiconductor elements with low withstand voltage. It is characterized in that as a glass composition, it contains 52 to 65% of ZnO, 5 to 20% of B ₂ O ₃ , 15 to 35% of SiO ₂ and 3 to 6% of Al ₂ O ₃ in terms of mass, and It is substantially free of lead. Preferably, it further contains 0 to 5% of Ta ₂ O ₅ , 0 to 5% of MnO ₂ , 0 to 5% of Nb ₂ O ₅ , 0 to 3% of CeO ₂ and Sb ₂ O ₃ as a composition.

Description

Glass for semiconductor device coating

The present invention relates to a glass for coating a semiconductor element including a P-N junction.

In general, a semiconductor device such as a silicon diode or a transistor is covered with a surface including a P-N junction portion of the semiconductor device by glass from the viewpoint of preventing contamination due to external air. This makes it possible to stabilize the surface of the semiconductor element and suppress deterioration of characteristics over time.

As the characteristics required for the semiconductor element coating glass, (1) the thermal expansion coefficient is suitable for the thermal expansion coefficient of the semiconductor element to avoid cracks due to the difference in thermal expansion coefficient with the semiconductor element, etc .; (2) it can be used at low temperature ( (For example, below 900 ° C) to prevent the characteristics of the semiconductor device from deteriorating; (3) do not include impurities such as alkali components that adversely affect the surface of the semiconductor device.

Conventionally, as a glass for coating a semiconductor element, zinc-based glass such as ZnO-B ₂ O ₃ -SiO ₂ system, PbO-SiO ₂ -Al ₂ O ₃ system, or PbO-SiO ₂ -Al ₂ O _3- Lead-based glass such as B ₂ O ₃ system, but from the viewpoint of operability, lead-based system such as PbO-SiO ₂ -Al ₂ O ₃ system and PbO-SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ system Glass is becoming mainstream (see, for example, Patent Documents 1 to 4).

Prior art literature Patent literature

Patent Document 1: Japanese Patent Publication No. 1-49653

Patent Document 2: Japanese Patent Laid-Open No. 50-129181

Patent Document 3: Japanese Patent Laid-Open No. 48-43275

Patent Document 4: Japanese Patent Laid-Open No. 2008-162881

Since lead components such as PbO are harmful to the environment, in recent years, they have been gradually banned from being used in electrical and electronic equipment, and lead-free materials have been promoted. The above-mentioned zinc-based glass such as ZnO-B ₂ O ₃ -SiO ₂ series also contains a small amount of a lead component, and is not environmentally friendly to users. In addition, zinc-based glass is inferior in chemical durability compared to lead-based glass, and has relatively weak resistance to acids in subsequent steps after the glass is fired. Therefore, it is necessary to cover the surface of the glass and form a protective film to perform the subsequent steps.

Furthermore, if the glass composition is enriched with SiO _{2 in} order to improve chemical durability, the surface charge density of the semiconductor element-coated glass layer increases, and the reverse breakdown voltage of the semiconductor element increases. On the other hand, reverse leakage of the semiconductor element occurs Bad current increase. Therefore, regarding a semiconductor element-coated glass used for a semiconductor element for a low withstand voltage that does not require a reverse withstand voltage, in order to suppress the reverse leakage current, it is necessary to reduce the surface charge density.

Therefore, an object of the present invention is to provide a glass having a small load on the environment, excellent chemical durability, and low surface charge density, and is particularly suitable for coating a semiconductor element for low withstand voltage.

As a result of earnest research, the inventors have found that the above-mentioned problems can be solved by a ZnO-B ₂ O ₃ -SiO ₂ -based glass having a specific composition, and have been proposed as the present invention.

That is, the present invention relates to a glass for coating a semiconductor element, which is characterized in that as a glass composition, it contains 52 to 65% of ZnO, 5 to 20% of B ₂ O ₃ , and 15 to 35% of SiO. ₂ and 3 to 6% of Al ₂ O ₃ and substantially no lead component.

The glass for coating a semiconductor element of the present invention is a ZnO-B ₂ O ₃ -SiO ₂ -based glass with a strict limitation on the content of each component, thereby suppressing the surface charge density, and is particularly suitable for coating a semiconductor element for low withstand voltage. It has the characteristics of high chemical durability. In addition, since it does not substantially contain a lead component, the load on the environment is small.

Furthermore, in the present invention, the term "substantially free" means that the relevant component is not intentionally added as a glass component, and does not mean that even impurities that are inevitably mixed in are completely excluded. Objectively speaking, it means that the content of related components including impurities is less than 0.1% by mass.

Secondly, the glass for coating a semiconductor element of the present invention preferably further contains 0 to 5% of Ta ₂ O ₅ , 0 to 5% of MnO ₂ , 0 to 5% of Nb ₂ O ₅ , and 0 to 3% of CeO. ₂ and 0 ~ 3% of Sb ₂ O ₃ as a composition.

Third, the present invention relates to a material for coating a semiconductor element, which is characterized by containing a glass powder including the glass for coating a semiconductor element.

By using this semiconductor element coating material, the surface of the semiconductor element can be easily covered.

Fourth, the semiconductor element coating material of the present invention preferably contains at least one inorganic powder selected from TiO ₂ , ZrO ₂ , ZnO, ZnO‧B ₂ O ₃ and 2ZnO‧SiO ₂ with respect to 100 parts by mass of the glass powder. 0.01 to 5 parts by mass.

Especially when the contact area between a semiconductor element including Si and glass is large, it is desirable that the thermal expansion coefficients of glass and Si are similar. This can suppress the occurrence of cracks on the surface of the coated glass caused by the difference in thermal expansion coefficient between the semiconductor element and the glass. The thermal expansion coefficient of glass can be adjusted by the crystal components contained in the glass, but it is difficult to properly control the amount of crystals precipitated from the glass. Therefore, if the above-mentioned inorganic powder is appropriately added to the glass for coating a semiconductor element, these inorganic powders function as a nucleating agent, and therefore it is possible to control the amount of crystals precipitated relatively easily. As a result, the desired thermal expansion coefficient can be easily adjusted.

The glass for coating a semiconductor element of the present invention has a low surface charge density, and is therefore particularly suitable for coating a semiconductor element for low withstand voltage. Further, since the chemical durability is high, deterioration over time can be reduced. In addition, since it does not substantially contain a lead component, the load on the environment is small.

Hereinafter, the reason why each component is prescribed | regulated as mentioned above in the glass for coating a semiconductor element of this invention is demonstrated. In addition, in the following description of the content of each component, "%" means "mass%" unless otherwise specified.

ZnO is a component that stabilizes glass. The content of ZnO is preferably 52 to 65%, particularly preferably 55 to 60%. If the content of ZnO is too small, the devitrification property at the time of melting becomes strong, and it is difficult to obtain a homogeneous glass. On the other hand, if the content of ZnO is too large, the acid resistance tends to weaken.

B ₂ O ₃ is a component that forms a network of glass and is a component that improves fluidity. The content of B ₂ O ₃ is preferably 5 to 20%, particularly preferably 7 to 15%. When the content of B ₂ O ₃ is too small, the crystallinity tends to increase, and the fluidity is impaired during coating, and it is difficult to uniformly coat the surface of the semiconductor element. On the other hand, when the content of B ₂ O ₃ is too large, the thermal expansion coefficient tends to increase or the chemical durability tends to decrease.

The SiO ₂ based glass is a component for forming a network and is a component for improving acid resistance. The content of SiO ₂ is preferably 15 to 35%, particularly preferably 20 to 33%. When the content of SiO ₂ is too small, the chemical durability tends to be poor. On the other hand, if the content of SiO ₂ is too large, the devitrification property at the time of melting becomes strong, making it difficult to obtain a homogeneous glass.

Al ₂ O ₃ is a component that stabilizes glass and adjusts the surface charge density. The content of Al ₂ O ₃ is preferably 3 to 6%, particularly preferably 4 to 5.5%. If the content of Al ₂ O ₃ is too small, devitrification tends to occur. On the other hand, if the content of Al ₂ O ₃ is too large, the surface charge density tends to increase too much.

The glass for coating a semiconductor element of the present invention may further contain Ta ₂ O ₅ , MnO ₂ , Nb ₂ O ₅ , CeO ₂ or Sb ₂ O ₃ as a component that reduces the surface charge density of the glass and suppresses the generation of a leakage current.

Ta ₂ O ₅ is a component having a particularly large effect as described above. The content of Ta ₂ O ₅ is preferably 0 to 5%, particularly preferably 0.1 to 3%. If the content of Ta ₂ O ₅ is too large, the meltability tends to decrease.

The content of MnO ₂ is preferably 0 to 5%, particularly preferably 0.1 to 3%. If the content of MnO ₂ is too large, the meltability tends to decrease.

The content of Nb ₂ O ₅ is preferably 0 to 5%, particularly preferably 0.1 to 3%. When the content of Nb ₂ O ₅ is too large, the meltability tends to decrease.

The content of CeO ₂ is preferably 0 to 3%, particularly preferably 0.1 to 2%. If the content of CeO ₂ is too large, the crystallinity tends to be too strong and the fluidity tends to decrease during coating.

The content of Sb ₂ O ₃ is preferably 0 to 3%, particularly preferably 0.1 to 2%. When the content of Sb ₂ O ₃ is too large, the meltability tends to decrease.

From the environmental point of view, the glass for coating a semiconductor element of the present invention does not substantially contain a lead component (PbO, etc.). In addition, it is preferable that it does not substantially contain an alkali component (Li ₂ O, Na ₂ O, and K ₂ O) that adversely affects the surface of the semiconductor element.

The glass for coating a semiconductor element of the present invention is preferably powdery. This makes it possible to easily coat the surface of the semiconductor element using, for example, a slurry method or an electrophoretic coating method. In this case, the average particle diameter D _{50 of the} glass powder is preferably 25 μm or less, and particularly preferably 15 μm or less. When the average particle diameter D _{50 of} the glass powder is too large, it tends to be difficult to make a slurry. Moreover, electrophoretic coating becomes difficult. The lower limit of the average particle diameter D ₅₀ of the glass powder is not particularly limited, but is practically 0.1 μm or more.

The semiconductor element coating material of the present invention is a material containing a glass powder (hereinafter also referred to as a "semiconductor element coating glass powder") containing the above-mentioned glass for coating a semiconductor element. The semiconductor element coating material of the present invention may be such that the glass powder for semiconductor element coating contains at least one inorganic powder selected from the group consisting of TiO ₂ , ZrO ₂ , ZnO, ZnO‧B ₂ O ₃ and 2ZnO‧SiO ₂ as a nucleating agent. Become. By adding these inorganic powders, the amount of precipitated crystals can be controlled relatively easily. As a result, the desired thermal expansion coefficient can be easily adjusted.

Content of these inorganic powders with respect to glass powder for semiconductor element coating 100 parts by mass, preferably 0.01 to 5 parts by mass, and particularly preferably 0.1 to 3 parts by mass. When the content of the inorganic powder is too small, the amount of precipitated crystals tends to be small, and it is difficult to achieve a desired thermal expansion coefficient. When the content of the inorganic powder is too large, the amount of precipitated crystals is excessively increased, and fluidity is impaired during coating, and the coating of the surface of the semiconductor element tends to be difficult.

Furthermore, the smaller the particle size of the inorganic powder, the smaller the particle size of the precipitated crystals and the higher the mechanical strength. Therefore, the average particle diameter D _{50 of the} inorganic powder is preferably 5 μm or less, and _more preferably 3 μm or less. The lower limit of the average particle diameter D ₅₀ of the inorganic powder is not particularly limited, but is practically 0.1 μm or more.

The thermal expansion coefficient (30 to 300 ° C) of the glass for coating a semiconductor element of the present invention is in the range of, for example, 20 to 60 × 10 ^-7 / ° C, and further to 30 to 50 × 10 ^-7 / ° C, based on the thermal expansion coefficient of the semiconductor element. Adjust appropriately.

For example, when the semiconductor element is used at a voltage of 1000 V or less, the surface charge density of the semiconductor element coating material is preferably 6 × 10 ¹¹ / cm ² or less, and particularly preferably 5 × 10 ¹¹ / cm ² or less. The surface charge density is a value measured by a method described in the following examples.

The glass for coating a semiconductor element of the present invention can be obtained, for example, by mixing raw material powders of each oxide component and batch-melting it at about 1500 ° C. for about 1 hour and forming it after vitrification (they are crushed and classified as necessary) .

Examples

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

Table 1 shows Examples 1 to 6 and Comparative Examples 1 to 3 of the present invention.

Each sample was produced as follows. First, the raw material powder was prepared so as to have a glass composition in the table, and was batchwise melted at 1500 ° C. for 1 hour to vitrify. Next, the molten glass was formed into a film shape, and then pulverized with a ball mill and classified using a 350-mesh sieve to obtain a glass powder (material for semiconductor element coating) having an average particle diameter D ₅₀ of 12 μm. In addition, regarding Example 4, a ZnO powder was added to the obtained glass powder to prepare a material for coating a semiconductor element.

The thermal expansion coefficient, surface charge density, and acid resistance of the semiconductor element coating material were measured or evaluated by the following methods. The results are shown in Table 1.

The coefficient of thermal expansion is a value measured using a dilatometer in a temperature range of 30 to 300 ° C.

The surface charge density was measured as follows. First, the semiconductor element coating material is dispersed in an organic solvent, and becomes a fixed film by electrophoresis. It is attached to the surface of the silicon substrate in a thick manner, and is fired to form a sintered layer. After forming an aluminum electrode on the surface of the sintered layer, the change in capacitance in the sintered layer was measured using a C-V meter to calculate the surface charge density.

The acid resistance was evaluated as follows. First, the semiconductor element coating material was pressure-molded to a size of 20 mm in diameter and about 4 mm in thickness, and then calcined to prepare a granular sample. The sample was immersed in 30% nitric acid at 25 ° C for 1 minute As the mass decreases, the mass change per unit area is calculated and used as an index of acid resistance. Furthermore, the smaller the amount of mass change, the more excellent the acid resistance.

According to Table 1, it can be known that the surface charge density of the semiconductor element coating materials of Examples 1 to 6 is as low as 6 × 10 ¹¹ / cm ² or less, and the mass reduction caused by the acid resistance test is 1.0 mg / cm ² or less, and acid resistance Excellent. Therefore, it can be seen that the materials for coating semiconductor devices of Examples 1 to 6 are suitable for coating semiconductor devices for low withstand voltage, and have excellent chemical durability.

On the other hand, although the samples of Comparative Examples 1 and 2 had a low surface charge density of 6 × 10 ¹¹ / cm ² or less, the mass reduction caused by the acid resistance test was 3.5 mg / cm ² or more, and the acid resistance was poor. The sample of Comparative Example 3 had a small decrease in mass due to the acid resistance test of 0.4 mg / cm ² , but had a large surface charge density of 15 × 10 ¹¹ / cm ² .

Although the present invention has been described in detail and with reference to specific embodiments, those skilled in the art should know that various changes or modifications can be made without departing from the spirit and scope of the present invention.

This application is based on a Japanese patent application filed on August 25, 2011 (Japanese Patent Application No. 2011-183703) and a filed on June 12, 2012 The contents of Japanese Patent Application (Japanese Patent Application No. 2012-132531) are hereby incorporated by reference.

Industrial availability

The glass of the present invention has a small load on the environment, excellent chemical durability, and low surface charge density, and is particularly preferably used for coating semiconductor devices with low withstand voltage.

Claims (4)

A glass for covering a semiconductor element, which is characterized in that as a glass composition, it contains 52 to 65% of ZnO, 5 to 20% of B ₂ O ₃ , 15 to 35% of SiO ₂ and 4 to 6%. Al ₂ O ₃ , which further contains Ta ₂ O ₅ , MnO ₂ , Nb ₂ O ₅ , CeO ₂ or Sb ₂ O ₃ , and substantially contains no lead component. For example, the glass for covering a semiconductor element of claim 1 further contains: 0 to 5% of Ta ₂ O ₅ , 0 to 5% of MnO ₂ , 0 to 5% of Nb ₂ O ₅ , and 0 to 3% of CeO ₂ And 0 ~ 3% of Sb ₂ O ₃ as a composition. A semiconductor element coating material comprising a glass powder containing the glass for coating a semiconductor element as claimed in claim 1 or 2. For example, the semiconductor element coating material of claim 3 contains at least one inorganic powder selected from TiO ₂ , ZrO ₂ , ZnO, ZnO‧B ₂ O _3, and 2ZnO‧SiO ₂ with respect to 100 parts by mass of glass powder. 5 parts by mass.