JP5754090B2 - Glass frit, conductive paste using the same, and electronic device - Google Patents

Description

  The present invention relates to a glass frit, a conductive paste using the glass frit, and an electronic device.

  Conventionally, an electronic device in which a conductive layer serving as an electrode is formed on a semiconductor substrate such as silicon (Si) has been used for various applications.

  The conductive layer to be the electrode is formed by applying a conductive paste in which a conductive metal powder such as aluminum (Al), silver (Ag), copper (Cu) and the like and glass frit are dispersed in an organic vehicle on a semiconductor substrate. It is formed by firing at a temperature equal to or higher than the melting point of the conductive metal powder.

  Conventionally, as glass frit to be blended in a conductive paste, one containing lead oxide has been used, but for reasons of environmental protection and the like, a composition containing no lead is required. In addition, the conductive layer serving as an electrode is required to have good durability against corrosive gas and the like. However, the conventional conductive paste using glass frit cannot satisfy such a requirement sufficiently.

  By the way, as a thick film electrode wiring material, a material containing a glass composition mainly composed of vanadium oxide and silver powder has been proposed (for example, see Patent Document 1).

However, since the electrode wiring material shown in Patent Document 1 contains 5% by weight or more of MnO ₂ in the glass composition, the flowability of the glass is easily hindered, and the silver electrode formed from this electrode material is Durability against corrosive gas was not sufficient.

JP 2009-209032 A

  The present invention has been made to solve the above problems, and provides a glass frit for a conductive particle binder capable of forming a conductive layer (electrode) having excellent durability against corrosive gases and the like. With the goal.

The glass frit of the present invention substantially does not contain Pb and Mn, and in terms of oxide, V ₂ O ₅ is 20 mol% or more and 80 mol% or less, ZnO is 5 mol% or more and 22.2 mol% or less, and BaO is 2 mol% or more. 40 mol% or less, _Sb 2 _{O 3} of 0 mol% or more 15 mol% or _less, P 2 _{O 5} and containing less 0 mol% or more 22.3 mol%, average particle diameter (50% particle diameter _{D 50)} is 0.1μm or more 5 0.0 μm or less.

  The conductive paste of the present invention is a conductive paste containing a conductive metal powder, a glass frit, and an organic vehicle. The glass frit of the present invention described above as the glass frit is replaced by 100 parts by mass of the conductive metal powder. It contains in the ratio of 0.1 to 10 mass parts with respect to this.

  The electronic device of the present invention is an electronic device comprising a semiconductor substrate and a conductive layer provided on the semiconductor substrate, wherein the conductive layer is a layer formed by firing the conductive paste of the present invention. It is characterized by being.

  In the electronic device of the present invention, the conductive layer is preferably a layer formed by heating and baking the conductive paste in an infrared heating furnace at a temperature rising rate of 10 ° C./second or more. Moreover, it is preferable that the said conductive layer has a glass deposit on the surface of the said electroconductive metal particle by baking of the said glass frit contained in the said electroconductive paste.

  According to the present invention, a conductive layer excellent in durability against corrosive gas or the like can be obtained by setting the composition of the glass frit for forming a conductive layer to be an electrode on a semiconductor substrate to a predetermined value. .

  In addition, according to the present invention, by preparing a conductive paste using such a glass frit, a conductive layer excellent in durability against corrosive gas or the like can be formed.

  Furthermore, according to the present invention, an electronic device excellent in reliability such as durability against corrosive gas can be obtained by forming a conductive layer on a semiconductor substrate by baking such a conductive paste.

It is sectional drawing which shows an example of the semiconductor device of this invention. The image by SEM of the cross section of the silver electrode formed using the glass frit of Example 2 is shown. The image by SEM of the cross section of the silver electrode formed using the glass frit of the comparative example 2 is shown. The image by SEM of the cross section of the aluminum electrode formed using the glass frit of Example 4 is shown. The image by SEM of the cross section of the aluminum electrode formed using the glass frit of the reference example 7 is shown. The image by the SEM of the cross section of the aluminum electrode formed using the glass frit of the reference example 8 is shown. The image by the SEM of the cross section of the aluminum electrode formed using the glass frit of the comparative example 2 is shown.

  Hereinafter, the present invention will be described in detail.

The glass frit of the present invention is substantially free of Pb and P, and in terms of oxide, V ₂ O ₅ is 20 mol% to 80 mol%, ZnO is 5 mol% to 45 mol%, and BaO is 0 mol% to 40 mol%. Hereinafter, Sb ₂ O ₃ is contained in an amount of 0 mol% to 15 mol% and P ₂ O ₅ is contained in an amount of 0 mol% to 40 mol%. The glass frit has an average particle size (50% particle size D ₅₀ ) of 0.1 μm or more and 5.0 μm or less.

In the glass frit of the present invention, V ₂ O ₅ is a component that lowers the softening temperature of the glass and improves fluidity. Also, V ₂ O ₅ is, by coloring the glass, so improving the infrared absorption rate of the time of firing, the glass deposit is formed on the outer periphery of the conductive metal particles. In other words, glass containing V ₂ O ₅ has a high infrared absorption rate and is likely to reach a high temperature. Therefore, a conductive paste obtained by mixing this glass frit with a conductive metal powder such as silver powder is heated with infrared rays. When firing, the glass volatilizes and condenses on the surface of the conductive metal particles, covering the outer periphery of the particles. By forming the glass precipitate around the conductive metal particles in this way, durability against corrosive gas and the like is improved.

This V ₂ O ₅ is contained in the glass frit at a ratio of 20 mol% to 80 mol%. If the content of V ₂ O ₅ is less than 20 mol%, the absorption of infrared rays during firing is insufficient and the glass is not sufficiently volatilized, so that a glass layer may not be formed around the conductive metal particles. . If the content of V ₂ O ₅ exceeds 80 mol%, there is a possibility that glass cannot be obtained due to crystallization. The more preferable content of V ₂ O ₅ is 22 mol% or more and 75 mol% or less, and the more preferable content is 24 mol% or more and 72 mol% or less.

  ZnO is a component that stabilizes the glass. This ZnO is contained in the glass frit at a ratio of 5 mol% to 45 mol%. When the content of ZnO is less than 5 mol% or exceeds 45 mol%, glass may not be obtained due to crystallization. From the viewpoint of stabilization of the glass, the more preferable content of ZnO is 7 mol% or more and 40 mol% or less, and the more preferable content is 8 mol% or more and 35 mol% or less.

  BaO is a component that stabilizes the glass. This BaO is contained in the glass frit at a ratio of 40 mol% or less. When the content of BaO exceeds 40 mol%, glass may not be obtained due to crystallization. From the viewpoint of stabilizing the glass, a more preferable content of BaO is 2 mol% or more and 38 mol% or less, and a more preferable content is 4 mol% or more and 36 mol% or less.

Sb ₂ O ₃ is a component that improves the water resistance of the glass. This Sb ₂ O ₃ can be contained in the glass frit at a ratio of 15 mol% or less. If the content of Sb ₂ O ₃ exceeds 15 mol%, the softening temperature of the glass increases, so that the glass does not flow sufficiently during firing, and no glass precipitate is formed around the conductive metal particles. Therefore, the durability against corrosive gas or the like may be deteriorated. The more preferable content of Sb ₂ O ₃ is 13 mol% or less, and the more preferable content is 12 mol% or less.

P ₂ O ₅ is a component that improves the stability of the glass. This P ₂ O ₅ can be contained in the glass frit at a ratio of 40 mol% or less. When the content of P ₂ O ₅ exceeds 40 mol%, the softening temperature of the glass increases, so that the glass does not flow sufficiently during firing, and no glass precipitate is formed around the conductive metal particles. Therefore, the durability against corrosive gas or the like may be deteriorated. The more preferable content of P ₂ O ₅ is 35 mol% or less, and the more preferable content is 33 mol% or less.

  The glass frit of the present invention contains substantially no Mn. If Mn is contained, the fluidity of the glass tends to be hindered, so that glass precipitates are not formed around the conductive particles, and the durability against corrosive gas and the like may be deteriorated.

  The glass frit of the present invention does not substantially contain Pb in consideration of the environment.

In the glass frit of the present invention, V ₂ O ₅ and ZnO, which are the above-described essential components, and further, BaO, Sb ₂ O ₃ , P ₂ O _{5 and the} like are blended at a predetermined ratio as necessary, and mixed thoroughly. Then, for example, heat treatment can be performed at a temperature of 1100 ° C. to 1300 ° C. and a time of 10 minutes to 120 minutes, followed by cooling and pulverization.

The glass frit thus obtained has an average particle size of 0.1 μm or more and 5.0 μm or less. Here, the average particle diameter is the cumulative median diameter (50% particle diameter (D ₅₀ )). When the 50% particle size (D ₅₀ ) is less than 0.1 μm, the frit cohesiveness becomes strong, and the frit exists as an aggregate. Therefore, in the preparation of the conductive paste described later, it is sufficient in the conductive metal powder. May not be dispersed. As a result, the glass does not flow sufficiently during firing. In addition, when the 50% particle size (D ₅₀ ) exceeds 5.0 μm, the specific surface area of the frit becomes small, so that the amount of infrared rays absorbed by the glass frit substantially decreases. May not volatilize. As a result, the periphery of the conductive metal particles cannot be covered with glass precipitates, and there is a possibility that sufficient durability against corrosive gas or the like cannot be obtained. In the present specification, the particle diameter is a value obtained by a particle diameter measuring apparatus using a laser diffraction / scattering method.

  The conductive paste of the present invention contains such a glass frit of the present invention. Specifically, it contains a conductive metal powder, a glass frit, and an organic vehicle, and at least a part, preferably all of the glass frit is made of the glass frit of the present invention.

  The content (ratio) of the glass frit in the conductive paste is preferably 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the conductive metal powder. When the content of the glass frit is less than 0.1 parts by mass with respect to 100 parts by mass of the conductive metal powder, the periphery of the conductive metal particles may not be covered with the glass precipitate. In addition, the adhesion between the conductive layer (electrode) formed by baking the conductive paste and the semiconductor substrate such as silicon may be insufficient. If the glass frit content exceeds 10 parts by mass, the conductivity of the conductive layer formed by this conductive paste may be insufficient. Further, the adhesion strength between the conductivity and the semiconductor substrate becomes too large, and there is a possibility that the warp of the semiconductor substrate becomes large.

Examples of the conductive metal powder contained in the conductive paste of the present invention include conductive aluminum powder, silver powder, and copper powder. The shape and manufacturing method of those conductive metal powders are not particularly limited. In addition, the particle size of the conductive metal powder is not particularly limited, and those having a wide average particle size (50% particle size D ₅₀ ) of 0.1 to 20 μm can be used. In particular, it is preferable to use one having a 50% particle size (D ₅₀ ) of 0.1 to 10 μm. If the 50% particle size (D ₅₀ ) is less than 0.1 μm or more than 10 μm, a paste having an appropriate viscosity cannot be obtained, which is not preferable.

  As the organic vehicle, an organic resin binder usually used for this type of conductive paste can be used. For example, ethyl cellulose, nitrocellulose, or the like can be used. The content of the organic vehicle is preferably 5% by mass or more and 40% by mass or less of the entire conductive paste. When the content of the organic vehicle is less than 5% by mass, the paste viscosity increases, so that the coating property such as printing of the conductive paste is lowered, and a good conductive layer (electrode) cannot be formed. On the other hand, if the content of the organic vehicle exceeds 40% by mass, the solid content of the paste becomes low, and there is a problem that a sufficient coating film thickness cannot be obtained.

  In the conductive paste of the present invention, in addition to the above-described conductive metal powder, glass frit, and organic vehicle, various kinds such as a dispersant, a plasticizer, an anti-settling agent, and a thixotropic agent that adjust the properties of the paste as necessary. Additives can be included. The composition of the additive is not particularly limited, but the content is preferably 10% by mass or less.

  The conductive paste of the present invention is sufficiently kneaded by adding a conductive metal powder, glass frit, and, if necessary, the above additives to an organic vehicle solution obtained by dissolving an organic resin binder as an organic vehicle in a solvent. Can be prepared.

  An electronic device 1 of the present invention shown in FIG. 1 includes a semiconductor substrate 2 and a conductive layer (electrode) 3 provided thereon, and the conductive layer (electrode) 3 is obtained by baking the conductive paste described above. Is formed. Such an electronic device 1 can be manufactured by the following method. That is, the conductive metal paste of the present invention is applied to a predetermined region of the main surface of the semiconductor substrate 1 by a method such as screen printing and dried. Thereafter, the semiconductor substrate 1 is heated to, for example, a temperature of 600 ° C. or higher and 900 ° C. or lower, and the conductive metal paste is baked to form the conductive layer 3.

  In the formation of the conductive layer 3 by firing the conductive metal paste, it is preferable to heat at an increase rate of 10 ° C./second or more using an infrared firing furnace in an air atmosphere. Furthermore, baking is preferably performed under conditions of a maximum temperature of 600 to 900 ° C. and a maximum temperature holding time of 1 to 10 seconds.

By heating and baking under the above conditions, the glass frit in the conductive metal paste of the present invention exhibits sufficient fluidity, and the surface of the conductive metal particles is covered with the glass precipitate. Glass containing V ₂ O ₅ has a high infrared absorption rate and is likely to become high temperature. Therefore, when the conductive paste mixed with conductive metal powder or the like is heated and fired with infrared rays, the glass volatilizes. Then, it condenses on the surface of the conductive metal particles and covers the outer periphery of the conductive metal particles. In this way, a glass precipitate is formed around the conductive metal particles, whereby the characteristics are improved. That is, when the conductive metal particles are silver particles, the glass precipitate is formed on the outer periphery of the silver particles, so that the conductive layer 3 formed by heating and baking the conductive paste has durability against corrosive gas and the like. Is greatly improved. Further, when the conductive metal particles are aluminum particles, the durability against moisture and the like is greatly improved by forming the glass precipitate on the outer periphery of the aluminum particles. Furthermore, when the conductive metal particles are copper particles, the glass precipitate is formed on the outer periphery of the particles before the copper is oxidized, thereby preventing the copper from being oxidized. Furthermore, this effect of preventing oxidation is more prominently obtained in copper particles whose oxidation resistance is enhanced by surface treatment or alloying.

  When the temperature rising rate during firing is less than 10 ° C./second, the glass frit in the conductive metal paste is not sufficiently volatilized, so the conductive metal particles cannot be covered with glass precipitates. The effect of improving the characteristics may not be sufficiently obtained.

  Examples of the present invention will be described below.

( Reference Example 1, Examples 2 to 6, Reference Examples 7 and 8 , Comparative Examples 1 to 5)
First, glass frit having the composition shown in Table 1 was produced. That is, raw material powders were blended and mixed so as to have the composition shown in Table 1, and melted in a 1100 to 1300 ° C. electric furnace using a platinum crucible for 1 hour to form a thin glass sheet. Then, the thin-plate glass was ground with a ball mill, the average particle diameter D ₅₀ to a value shown in Table 1 in the range of 0.9～2.0Myuemu, and classified by air classifier device. Thus, the glass frit for electrode formation of Reference Example 1, Examples 2 to 6, Reference Examples 7 and 8, and Comparative Examples 2 and 3, and Comparative Example 5 was manufactured. For Comparative Example 4, the average particle diameter D ₅₀ was prepared by grinding in a ball mill so that the 6.5 [mu] m.

The glass frit of Comparative Example 4 has the same composition as the glass frit of Example 6. Further, the glass frit of Comparative Examples 2 and 3 does not contain V ₂ O ₅ , and the glass frit of Comparative Example 5 contains Mn.

Next, using the glass frit of Reference Example 1, Examples 2 to 6, Reference Examples 7 and 8, and Comparative Examples 2 to 5, a conductive paste (silver paste) was prepared as follows. First, 90 parts by mass of terpineol was mixed with 10 parts by mass of ethyl cellulose and stirred at 85 ° C. for 2 hours to prepare an organic vehicle. Next, 10 parts by mass of the organic vehicle thus obtained was mixed with 90 parts by mass of conductive silver powder (silver powder manufactured by DOWA Electronics: AG4-8F), and then kneaded by a rotation and revolution mixer. Thereafter, the glass frit of Reference Example 1, Examples 2 to 6, Reference Examples 7 and 8, and Comparative Examples 2 to 5 was blended at a ratio of 1.1 parts by mass with respect to 100 parts by mass of the silver powder, and further rotation and revolution A silver paste was obtained by kneading with a mixer. As shown in Table 1, in Comparative Example 1, a silver paste was prepared in the same manner as described above except that no glass frit was added.

Next, using the glass frit of Example 4, Reference Examples 7 and 8, and Comparative Example 2, a conductive paste (aluminum paste) was prepared as follows. First, 90 parts by mass of terpineol was mixed with 10 parts by mass of ethyl cellulose and stirred at 85 ° C. for 2 hours to prepare an organic vehicle. Next, 20 parts by mass of the organic vehicle thus obtained was mixed with 80 parts by mass of aluminum powder (aluminum powder manufactured by Toyo Aluminum Co., Ltd .: D ₅₀ = 5 μm), and then kneaded by a rotation and revolution mixer. Thereafter, the glass frits of Example 4, Reference Examples 7 and 8 and Comparative Example 2 were blended at a ratio of 1.4 parts by mass with respect to 100 parts by mass of the aluminum powder, and further kneaded by a rotation and revolution mixer to obtain an aluminum paste. .

  Next, the silver paste and the aluminum paste obtained as described above were printed on a 6-inch square polycrystalline silicon substrate using a # 325 screen printing plate and dried for 10 minutes with a dryer at 150 ° C. Thereafter, firing was performed in an air atmosphere in an infrared firing furnace under conditions of a temperature rising rate of 35 ° C./second, a maximum temperature of 720 ° C., and a maximum temperature holding time of 2 seconds. Thus, a silicon substrate (electrode fired substrate) on which silver electrodes and aluminum electrodes were formed was obtained.

  The cross section of the silver electrode of the electrode fired substrate thus obtained was observed with an SEM (scanning electron microscope), and the covering state of the silver particles with the glass precipitate was examined. Here, the cross-sectional SEM image of the silver electrode formed using the glass frit of Example 2 is shown in FIG. 2, and the cross-sectional SEM image of the silver electrode formed using the glass frit of Comparative Example 2 is shown in FIG. From the cross-sectional SEM image of FIG. 2, it can be seen that in the silver electrode formed using the glass frit of Example 2, glass precipitates are formed on the surface of the silver particles. On the other hand, as can be seen from the cross-sectional SEM image of FIG. 3, in the silver electrode formed using the glass frit of Comparative Example 2, no glass precipitates are seen around the silver particles.

  Next, 25 g of ion-exchanged water and 0.5 g of ammonium sulfide are put in a plastic container, and a small plastic container with a lid on which an electrode firing substrate is placed is placed, and the outer plastic container is tightly covered. Closed. After leaving it to stand at room temperature for 2 hours, the electrode fired substrate was taken out, and whether or not there was spot-like corrosion on the electrode was visually observed with a microscope. The case where no spot-like corrosion was observed was rated as ◯, and the case where it was observed was marked as x. The hydrogen sulfide concentration in a small plastic container in which the electrode firing substrate was placed was measured with a detector tube and found to be 23 ppm.

As is clear from Table 1, the silver paste obtained in Comparative Example 1 does not contain glass frit, so in the silver electrode formed by this silver paste, there is no glass deposit around the silver particles, Since hydrogen sulfide reacts with the surface of silver particles, spot-like corrosion occurs. In addition, since the silver paste prepared using the glass frit of Comparative Examples 2 and 3 uses a glass frit that does not contain V ₂ O ₅ , in the silver electrode formed by this silver paste, There are no glass deposits around and hydrogen sulfide reacts with the surface of the silver particles, so that spot-like corrosion occurs. Since the silver paste obtained in Comparative Example 4 has a predetermined composition but a glass frit having a size exceeding a predetermined average particle size (5 μm) is used, the silver paste formed by this silver paste is also used. The glass deposits are not sufficiently present around the silver particles, and spot-like corrosion occurs. Since the silver paste obtained using the glass frit of Comparative Example 5 uses a glass frit containing MnO ₂ , in the silver electrode formed by this silver paste, glass precipitates are formed around the silver particles. Since hydrogen sulfide reacts with the surface of silver particles, spot-like corrosion occurs.

On the other hand, the silver paste obtained using the glass frit of Reference Example 1, Examples 2 to 6, and Reference Examples 7 and 8 contains a glass frit having a predetermined composition and a predetermined average particle diameter. Therefore, it can be seen that the silver electrodes formed by printing and baking these silver pastes have glass precipitates around the silver particles and have excellent resistance to hydrogen sulfide.

Next, the cross section of the aluminum electrode of the electrode fired substrate was observed with an SEM, and the covering state of the aluminum particles with the glass precipitate was examined. Here, the cross-sectional SEM image of the aluminum electrode obtained using the glass frit of Example 4 is shown in FIG. 4, and the cross-sectional SEM image of the aluminum electrode obtained using the glass frit of Reference Example 7 is shown in FIG. A cross-sectional SEM image of the aluminum electrode obtained using the glass frit of Reference Example 8 is shown in FIG. 6, and a cross-sectional SEM image of the aluminum electrode obtained using the glass frit of Comparative Example 2 is shown in FIG. 4, 5 and 6, it can be seen that glass precipitates are formed on the surfaces of the aluminum particles in the aluminum electrodes obtained using the glass frit of Example 4 and Reference Examples 7 and 8. . On the other hand, as can be seen from the cross-sectional SEM image of FIG. 7, in the aluminum electrode obtained using the glass frit of Comparative Example 2, no glass deposits are seen around the aluminum particles. The aluminum electrodes of Example 4 and Reference Examples 7 and 8 are considered to have improved durability against moisture and the like because glass precipitates are present on the surfaces of the aluminum particles.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Semiconductor substrate, 3 ... Conductive layer (electrode)

Claims (6)

Substantially free of Pb and Mn, in terms of oxide, V ₂ O ₅ is 20 mol% or more and 80 mol% or less, ZnO is 5 mol% or more and 22.2 mol% or less, BaO is 2 mol% or more and 40 mol% or less, Sb ₂ O ₃ is 0 mol% or more and 15 mol% or less, P ₂ O ₅ is contained 0 mol% or more and 22.3 mol% or less, and the average particle size (50% particle size D ₅₀ ) is 0.1 μm or more and 5.0 μm or less. Characteristic glass frit for conductive particle binder. V ₂ O ₅ The glass frit according to claim 1, wherein the content of ZnO is 24 mol% or more and 72 mol% or less, the content of ZnO is 5 mol% or more and 22.2 mol% or less, and the content of BaO is 17.8 mol% or more and 36 mol% or less. A conductive paste containing a conductive metal powder, a glass frit, and an organic vehicle, wherein the glass frit according to claim 1 or 2 is 0.1% with respect to 100 parts by mass of the conductive metal powder. It contains in the ratio of 10 mass parts or less of a mass part, The electrically conductive paste characterized by the above-mentioned. An electronic device comprising a semiconductor substrate and a conductive layer provided on the semiconductor substrate,
An electronic device, wherein the conductive layer is a layer formed by firing the conductive paste according to claim 3 . 5. The electronic device according to claim 4 , wherein the conductive layer is a layer formed by heating and baking the conductive paste in an infrared heating furnace at a temperature rising rate of 10 ° C./second or more. 6. The electronic device according to claim 4 , wherein the conductive layer has glass precipitates on the surface of the conductive metal particles by firing the glass frit contained in the conductive paste.