TW201618242A - Semiconductor element-coating glass - Google Patents

Abstract

Provided is a semiconductor element-coating glass which is environmentally friendly and has a large surface charge density. This semiconductor element coating glass comprises, in mass%, 50-62% (excluding 62%) of ZnO, 19-28% of B2O3, 8-15% (excluding 8%) of SiO2, and 3-12% of Al2O3, and substantially not comprising an alkali metal component, lead component, Bi2O3, Sb2O3, and As2O3.

Description

Semiconductor component coated glass

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

In general, in a semiconductor element such as a germanium diode or a transistor, the surface of the semiconductor element including the P-N junction surface is covered by glass from the viewpoint of preventing contamination by external air. Thereby, stabilization of the surface of the semiconductor element can be achieved, and deterioration of temporal characteristics can be suppressed.

The characteristics required for the semiconductor element-coated glass include the following characteristics: (1) the coefficient of thermal expansion corresponds to the coefficient of thermal expansion of the semiconductor element, so that cracking does not occur due to a difference in thermal expansion coefficient of the semiconductor element during coating; (2) coating at a relatively low temperature (for example, 900 ° C or lower) to prevent deterioration of characteristics of the semiconductor element; (3) not containing impurities such as alkali metal components which adversely affect the characteristics of the semiconductor element; (4) The electrical characteristics after the surface of the semiconductor element is covered have high reliability such as high reverse voltage and low leakage current.

Conventionally, as a glass for covering a semiconductor element, a zinc-based glass such as ZnO-B ₂ O ₃ -SiO ₂ or PbO-SiO ₂ -Al ₂ O ₃ or PbO-SiO ₂ -Al ₂ O ₃ -B _{2 is known.} O ₃ based lead glass and the like, in terms of the viewpoint of _{workability, PbO-SiO 2 -Al 2 O} 3 based and _{PbO-SiO 2 -Al 2 O 3} -B 2 O 3 based glass and other lead-based mainstream (e.g. Refer to Patent Documents 1 to 4).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Special Fair No. 1-496653

[Patent Document 2] Japanese Patent Laid-Open No. 50-129181

[Patent Document 3] Japanese Patent Laid-Open No. SHO 48-43275

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2008-162881

Since lead components such as PbO are components having a large environmental load, in recent years, their use in electrical and electronic equipment has been restricted, and lead-free materials have been continuously promoted. The zinc-based glass such as the ZnO-B ₂ O ₃ -SiO ₂ system described above also contains a small amount of lead component, and is also environmentally limited.

On the other hand, in the glass containing no lead component, the surface charge density is low, and it is difficult to cope with the semiconductor element for medium to high withstand voltage. As a semiconductor element coating material having a high surface charge density, a material containing a glass containing Bi ₂ O ₃ has also been proposed. However, Bi ₂ O ₃ has a concern about environmental load similarly to lead.

In view of the above circumstances, an object of the present invention is to provide a semiconductor element coating glass which has a small burden on the environment and a large surface charge density.

The inventors of the present invention conducted intensive studies and found that the above problems can be solved by a ZnO-B ₂ O ₃ -SiO ₂ -based glass having a specific composition, which is proposed in the form of the present invention.

That is, the glass for coating a semiconductor element of the present invention is characterized by containing 50 to 62% by mass (excluding 62%) of ZnO, 19 to 28% of B ₂ O ₃ , and 8 to 15% (excluding 8 of them). %) SiO ₂ , 3 to 12% Al ₂ O ₃ , and substantially no alkali metal component, lead component, Bi ₂ O ₃ , Sb ₂ O ₃ and As ₂ O ₃ .

Further, in the present invention, "substantially free" means that it is not intentionally added as a glass component, and does not mean that impurities which are inevitably mixed are completely excluded. Objectively, it means that the content of the relevant component containing impurities is less than 0.1% by mass%.

The semiconductor device of the present invention is preferably further coated glass comprising in mass% _{0 ~ 5% MnO 2, 0} ~ 5% Nb 2 O 5, and 0 ~ 3% CeO _2.

The glass powder for coating a semiconductor element of the present invention is characterized by comprising the above-described glass for covering a semiconductor element.

The semiconductor element coating material of the present invention is characterized by comprising 100 parts by mass of the glass element for coating a semiconductor element, and 0.01 to 5 parts by mass selected from the group consisting of TiO ₂ , ZrO ₂ , ZnO, αZnO ̇B ₂ O ₃ , 2ZnO. ˙SiO _2, cordierite and quartz is at least one kind of inorganic powder.

In particular, when the contact area between the semiconductor element such as Si and the coated glass is extremely large, in order to suppress the occurrence of cracks or the like, it is preferable that the semiconductor element and the coated glass have similar thermal expansion coefficients. The coefficient of thermal expansion of the glass for coating can be adjusted by the crystal component contained in the glass, but it is very difficult to appropriately control the amount of precipitated crystals. Therefore, when the inorganic powder is appropriately added to the glass powder for coating a semiconductor element, the inorganic powder acts as a nucleating agent, so that the amount of precipitated crystals can be relatively easily controlled. As a result, the desired coefficient of thermal expansion can be easily achieved.

The semiconductor element coating glass of the present invention is characterized by containing 50 to 62% by mass (excluding 62%) of ZnO, 19 to 28% of B ₂ O ₃ , and 8 to 15% (excluding 8%). SiO ₂ and 3 to 12% of Al ₂ O ₃ do not substantially contain an alkali metal component, a lead component, Bi ₂ O ₃ , Sb ₂ O ₃ and As ₂ O ₃ . Hereinafter, the reason why the content of each component is specified as described above in the glass for covering a semiconductor element of the present invention will be described. In the following description of the content of each component, "%" means "% by mass" unless otherwise specified.

ZnO is a component that stabilizes glass. The content of ZnO is 50 to 62% (excluding 62%) of ZnO, preferably 55 to 61%. If the content of ZnO is too small, it is difficult to obtain the above effects. Further, the coefficient of thermal expansion tends to be large, and as a result, the difference in thermal expansion between the glass and the semiconductor element is large. There is a crack in the glass. On the other hand, when the content of ZnO is too large, crystallization proceeds rapidly due to heat treatment at the time of coating, and thus it is difficult to coat the surface of the semiconductor element due to insufficient fluidity.

The B ₂ O ₃ network forms a component and has an effect of improving fluidity. The content of B ₂ O ₃ is 19 to 28%, preferably 20 to 25%. When the content of B ₂ O ₃ is too small, crystallinity is increased and fluidity is impaired, and it tends to be difficult to coat the surface of the semiconductor element. On the other hand, when the content of B ₂ O ₃ is too large, the coefficient of thermal expansion tends to be large. As a result, the difference in thermal expansion between the glass and the semiconductor element is increased, and there is a possibility that the glass is cracked.

The SiO ₂ network forms a component and has an effect of improving acid resistance. The content of SiO ₂ is 8 to 15% (excluding 8%), preferably 9 to 14%. When the content of SiO ₂ is too small, chemical durability is liable to lower. Further, the coefficient of thermal expansion tends to be large, and as a result, the difference in thermal expansion between the glass and the semiconductor element is large, and cracking of the glass occurs. When the content of SiO ₂ is too large, the homogeneity is liable to lower.

The Al ₂ O ₃ system increases the composition of the surface charge density. The content of Al ₂ O ₃ is 3 to 12%, preferably 5 to 10%, more preferably 5.5 to 9.5%. If the content of Al ₂ O ₃ is too small, it is difficult to obtain the above effects. On the other hand, if the content of Al ₂ O ₃ is too large, devitrification is likely to occur.

The alkali metal component (Li ₂ O, Na ₂ O, K ₂ O, etc.) tends to adversely affect the characteristics of the semiconductor element. Therefore, the glass for covering a semiconductor element of the present invention does not substantially contain an alkali metal component. Moreover, the semiconductor element coating glass of the present invention contains substantially no lead component, Sb ₂ O ₃ and As ₂ O _{3 from} the viewpoint of reducing the load on the environment. Further, as described above, Bi ₂ O ₃ also have concerns about the impact on the environment of the component, the semiconductor device of the present invention the glass coating is substantially free of Bi ₂ O _3. In addition, when Bi ₂ O _{3 is} contained, the surface charge density can be easily increased, so that it is easy to increase the withstand voltage, but at the same time, the leakage current tends to increase. Therefore, from the viewpoint of reducing leakage current, it is also effective to substantially exclude Bi ₂ O ₃ .

The semiconductor element coating glass of the present invention may contain MnO ₂ , Nb ₂ O ₅ or CeO _{2 in} addition to the above components. These components have the effect of reducing leakage current of the semiconductor element.

The content of MnO ₂ is preferably from 0 to 5%, more preferably from 0.1 to 3%. When the content of MnO ₂ is too large, the melting property tends to decrease.

The content of Nb ₂ O ₅ is preferably from 0 to 5%, more preferably from 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 from 0 to 3%, more preferably from 0.1 to 2%. When the amount of CeO _{2 is} too large, the crystallinity tends to be too strong and the fluidity tends to decrease.

The semiconductor element coating glass of the present invention is preferably in a powder form (glass powder for semiconductor element coating) from the viewpoint of easily covering the surface of the semiconductor element. In this case, the average particle diameter D _{50 of the} glass powder is preferably 25 μm or less, more 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 be slurried or it is difficult to perform electrophoretic coating. In addition, the lower limit of the average particle diameter D ₅₀ of the glass powder is not particularly limited, and is actually 0.1 μm or more.

The glass for coating a semiconductor element of the present invention can be obtained by blending raw material powders such as oxides to prepare a batch, and melting at about 1400 ° C for about 1 hour, followed by molding. Further, the glass after the molding is further pulverized and classified to obtain a glass powder for coating a semiconductor element.

The semiconductor element coating material of the present invention contains at least one selected from the group consisting of TiO ₂ , ZrO ₂ , ZnO, αZnO ̇B ₂ O ₃ , 2ZnO ̇ SiO ₂ , cordierite, and quartz in the glass powder for semiconductor element coating. Inorganic powders are used as nucleating agents. The content of the inorganic powder is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the glass powder for coating a semiconductor element. When the content of the inorganic powder is too small, the amount of precipitated crystals is 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 too large and the fluidity is impaired, and it tends to be difficult to coat the surface of the semiconductor element.

In addition, the smaller the particle diameter of the inorganic powder, the smaller the particle size of the precipitated crystal and the denser the structure of the coating material, so that the mechanical strength tends to increase. Therefore, the average particle diameter D _{50 of the} inorganic powder is preferably 5 μm or less, more preferably 3 μm or less. In addition, the lower limit of the average particle diameter D ₅₀ of the inorganic powder is not particularly limited, and is actually 0.1 μm or more.

The surface charge density of the semiconductor element-coated glass and the semiconductor element-coated material of the present invention is preferably 4 × 10 ¹¹ /cm ² or more for a semiconductor device having a voltage of 1000 V, and is preferable for a semiconductor device of 1500 V or more. of 9 × 10 ¹¹ / cm ² or more. In addition, when the surface charge density is increased, the withstand voltage becomes high, but at the same time, the leakage current tends to increase. Therefore, when applied to a semiconductor device of about 1000 to 1500 V, in order to suppress leakage current and obtain a balance with withstand voltage, the surface charge density is preferably adjusted to, for example, 12 × 10 ¹¹ /cm ² or less, and further 10 × 10 ¹¹ / cm ² or less.

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

[Examples]

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

Table 1 shows examples and comparative examples of the present invention.

Each sample was produced in the following manner. First, the raw material powders were blended in such a manner as to have the composition of the glass in Table 1, and a batch was prepared and melted at 1400 ° C for 1 hour. After the molten glass was formed into a film shape, it was pulverized by a ball mill, and classified using a 350-mesh sieve to obtain a glass powder for semiconductor element coating (average particle diameter D ₅₀ : 12 μm).

The thermal expansion coefficient and the surface charge density of the obtained glass powder for coating a semiconductor element were measured. In addition, in Example 6, the measurement was carried out by adding 0.1 mass part of ZnO powder to 100 parts by mass of the glass powder for semiconductor element coating. The results are shown in Table 1.

The coefficient of thermal expansion is measured using a thermal expansion meter at a temperature ranging from 30 to 300 °C.

The surface charge density was measured in the following manner. First, the glass powder is dispersed in an organic solvent, and adhered to the surface of the raft by a certain thickness by electrophoresis, and then fired to form a glass layer. After an aluminum electrode was formed on the glass layer, the change in capacitance in the glass was measured using a capacitance-voltage (C-V) meter to calculate the surface charge density.

As is clear from Table 1, the samples of Examples 1 to 5 had a surface charge density of 5 × 10 ¹¹ /cm ² or more and were high. This is a surface charge density equivalent to that of a lead glass such as PbO-SiO ₂ -Al ₂ O ₃ or PbO-SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ . Therefore, the semiconductor element coating glass (semiconductor element coating material) of the first to sixth embodiments is suitable for the coating of the semiconductor element for medium to high withstand voltage.

On the other hand, the sample of Comparative Example 1 had a surface charge density of 1 × 10 ¹¹ /cm ² and was low, and was not suitable for coating of a semiconductor element for medium to high withstand voltage.

Claims (4)

A semiconductor element coating glass characterized by containing 50 to 62% by mass (excluding 62%) of ZnO, 19 to 28% of B ₂ O ₃ , and 8 to 15% (excluding 8% of SiO) by mass. ₂ , 3~12% Al ₂ O ₃ , and substantially no alkali metal component, lead component, Bi ₂ O ₃ , Sb ₂ O ₃ and As ₂ O ₃ . The semiconductor element coating glass according to claim 1, further comprising 0 to 5% by mass of MnO ₂ , 0 to 5% of Nb ₂ O ₅ , and 0 to 3% of CeO ₂ by mass%. A glass powder for coating a semiconductor element, comprising the glass for coating a semiconductor element according to claim 1 or 2. A material for coating a semiconductor element, comprising: 100 parts by mass of the glass element for coating a semiconductor element according to claim 3, and 0.01 to 5 parts by mass selected from the group consisting of TiO ₂ , ZrO ₂ , ZnO, αZnO ̇B ₂ O ₃ , at least one inorganic powder of 2ZnO ̇SiO ₂ , cordierite and quartz.