JP2008133157A - METHOD FOR PRODUCING SiO SINTERED COMPACT - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate evaporation residue in a powder sintered type SiO sintered compact used for the formation of a vapor-deposited film of silicon monoxide, to secure material strength withstanding use, and to suppress the generation of splashes. <P>SOLUTION: As sintering raw material powder, a powdery mixture of powder with small grain sizes and powder with large grain sizes produced from precipitated SiO is used. The mixing ratio of the powder with small grain sizes in the raw material powder is controlled to 10 to 30 wt.%. The sintering temperature is reduced to 700 to 1,000°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a SiO sintered body suitable for use as a deposition material for forming a deposited film of silicon monoxide.

  Packaging materials for foods and pharmaceuticals, and resin substrates for flat panel displays such as liquid crystals and organic ELs are required to have a high gas barrier property. From this point of view, a gas barrier film in which a metal such as aluminum or a metal oxide such as silicon oxide, aluminum oxide, or magnesium oxide is vapor-deposited on a polymer film substrate is known, and in particular, silicon monoxide is vapor-deposited. Is attracting attention because it has both high transparency and high gas barrier properties.

As a vapor deposition material used for forming the silicon monoxide film, silicon monoxide manufactured using a vacuum agglomeration method is usually used. The vacuum agglomeration method is a method for producing SiO by mixing and heating Si and SiO ₂ in a raw material chamber, and vapor-depositing SiO on the inner surface of a tubular agglomeration chamber connected to the raw material chamber. It is. The produced SiO is a dense precipitate, which may be cut into a predetermined tablet shape and used directly as a vapor deposition material. In other cases, the precipitate is once crushed into a powder and then sintered into a predetermined tablet shape. In some cases, it may be used. Since characteristic values such as bulk density can be controlled over a wide range, a sintered body is relatively often used as a vapor deposition material.

One of the quality factors required for such a vapor deposition material is that there is little evaporation residue. The evaporation residue is the residue remaining in the crucible after vapor deposition, which consists of silicon dioxide (SiO ₂ ) and silicide with the metal (usually W) that constitutes the crucible. It becomes a problem. This is because in the powder-sintered vapor deposition material, the oxidized amount (SiO ₂ ) on the grain surface of the raw material SiO powder becomes a residue, so the amount of residue is inevitably increased, and at the same time, the oxide film on the grain surface Since it becomes an obstacle of vapor deposition, the vapor deposition rate is lowered as a result. Regardless of the type of vapor deposition material, if there are many vapor deposition residues, the continuous operation for a long period of time will be hindered. And as a measure to reduce the evaporation residue in the powder-sintered evaporation material, it is patented that the effectiveness of increasing the particle size of the powder raw material used for the manufacture of the evaporation material, specifically 250 μm or more It is described in Document 1.

Japanese Patent No. 3828434

  When the particle size of the raw material powder is increased in the powder-sintered deposition material, the grain surface area per unit weight of the powder is reduced, and the amount of oxidation on the grain surface is reduced. However, when a large particle size powder is used as a sintering raw material, the mechanical strength of the sintered body is reduced. When the mechanical strength of the vapor deposition material decreases, the material (tablet) breaks during vapor deposition, and this problem also becomes an obstacle to continuous vapor deposition. For example, in the EB vapor deposition method, the surface of the tablet is heated and evaporated by an electron beam (EB), but only the surface is heated to a high temperature, so that a large thermal stress is generated inside the tablet, and this causes the tablet to be deposited during the vapor deposition. It is thought to cause destruction. This problem becomes prominent when the electron beam output is increased to increase the deposition rate. And in order to solve this problem, in patent document 1, sintering temperature is set very high as 1200 to 1350 degreeC (1300 degreeC in an Example). That is, the large particle size powder is hardened and hardened at a high temperature.

  In addition to these problems, the formation process of the silicon monoxide vapor deposition film is a technical problem that must also be solved with splash. Splash is a fine jumping phenomenon of the molten material. If this occurs during film formation, defects such as pinholes are generated in the formed deposited film, and the film quality is significantly reduced. This phenomenon becomes more prominent as the film formation rate is increased, and it is a factor that hinders the film formation rate. For this reason, in the formation work of a silicon monoxide vapor deposition film, suppression of the occurrence of splash has become an important technical problem, and approaches have been attempted from various directions to solve the problem.

  And regarding this splash, the physical properties of the vapor deposition material are deeply involved, and it is thought that the more dense and hard the vapor deposition material is, the less likely it is to splash. From this point of view, the hard material sintered at high temperature This means that the vapor deposition material hardly generates splash. However, in actuality, a vapor deposition material sintered at a high temperature is likely to generate splash. Therefore, the vapor deposition material presented in Patent Document 1 has a problem of occurrence of splash in the formation process of a silicon monoxide vapor deposition film. Turned out to be.

  It is an object of the present invention to produce a high-quality SiO sintered body that can be used in a process for forming a silicon monoxide vapor deposition film and can effectively suppress the occurrence of splash and cracking, and can also reduce the amount of evaporation residue. It is to provide a method.

  In order to reduce the evaporation residue when using the powder sintering type vapor deposition material, the use of a large particle size powder is indispensable. From this point of view, the present inventor has studied from various aspects about a method for simultaneously suppressing the decrease in mechanical strength and the occurrence of splash, which are problems in a vapor deposition material using a large particle size powder. As a result, the following facts were found.

  As described above, the cause of the splash in the vapor deposition operation of silicon monoxide has hitherto been thought to be due to the low physical properties of the vapor deposition material, particularly the denseness. That is, it was considered that the splash was caused by the low density of the material and the remarkable brittleness. However, from the results of various investigations by the present inventors, another new cause has emerged. That is, the present inventor paid attention to the influence of the sintering temperature on the splash in the powder sintering type vapor deposition material, and investigated this in detail. The result was that the splash was effectively suppressed when a vapor deposition material sintered at a temperature slightly lower than the conventional ideal value was used. The inventor considers the reason as follows.

  Conventionally, the powder sintering temperature has been set to a high temperature of 1200 ° C. or higher in order to increase the density. This high temperature sintering was particularly required when using large particle size powders. In the case of such high-temperature sintering, SiO is thermally decomposed and Si is precipitated in the sintering process. In the vapor deposition operation, the deposited Si is evaporated and splashed. Although the possibility that the brittleness of the vapor deposition material may contribute to the splash cannot be denied, the evaporation phenomenon in the vapor deposition process of Si deposited in the high temperature sintering is more dominant than the splash. Actually, when XRD (X-Ray Diffraction spectroscopy) was performed on the vapor deposition material having variously changed sintering temperatures, it was confirmed that the Si peak disappeared and the splash was drastically reduced as the sintering temperature decreased.

  However, when the sintering temperature is lowered in the sintering of the large particle size powder, the mechanical strength of the sintered body is extremely lowered, and the damage during use of the vapor deposition material (tablet) becomes more remarkable.

  Under these circumstances, the present inventor considers that the use of a large particle size powder is indispensable for suppressing evaporation residue, and that the reduction of the sintering temperature is also indispensable for preventing splash. A method for compensating for the decrease in mechanical strength of a sintered body, which becomes a problem when a large particle size powder is sintered at a low temperature without adverse effects, was studied. As a result, the effectiveness of mixing and using a small particle size powder in a large particle size powder was found. The reason is that when a small particle size powder is mixed with a large particle size powder and sintered, the small particle size powder particles enter between the large particle size powder particles, and this acts as a binder, It is conceivable that the particles are firmly bonded to each other.

  The manufacturing method of the SiO sintered body of the present invention has been completed on the basis of such knowledge, and a large particle size SiO powder and a small particle size SiO powder are used as raw materials, and these are mixed and then molded and sintered. To do.

  In the method for producing a SiO sintered body of the present invention, a mixed powder of large particle size SiO powder and small particle size SiO powder is used as a sintering raw material powder. An image of the particle size distribution of the raw material powder used in the method for producing a SiO sintered body of the present invention is shown by a solid line in FIG. In the method for producing a SiO sintered body of the present invention, two types of fine powder and coarse powder are mixed and used after classifying the SiO powder, so that two particle size distribution peaks occur. Since coarse grains are the main component, the peak of coarse grains is high and the peak of fine grains is low. For reference, the particle size distribution of a general powder is shown by a broken line in FIG. In the case of a broad powder with no lumps, both coarse and fine particles are included, but the particle size distribution has one peak, which is different from the above mixed powder.

  In the method for producing a SiO sintered body according to the present invention, since the large particle size SiO powder is used as the main component of the sintered powder, the surface area is reduced, the evaporation residue is reduced in the evaporation process, and the evaporation rate is improved. Since the small particle size SiO powder is mixed and used, even when the occurrence of splash in the vapor deposition process is suppressed by low-temperature sintering, the decrease in mechanical strength of the vapor deposition material is suppressed, and the occurrence of splash in the vapor deposition process is suppressed. Is done.

  In the method for producing a SiO sintered body of the present invention, the mixing ratio of the small particle size SiO powder in the raw material, the particle size of both powders, and the sintering temperature in the sintering process are important.

  The mixing ratio of the small particle size SiO powder in the raw material is preferably 10 to 30 wt%. If the mixing ratio of the small particle size SiO powder is too small, the decrease in the mechanical strength of the sintered body cannot be sufficiently compensated. On the other hand, if the mixing ratio of the small particle size SiO powder is too large, the surface area per unit weight of the powder increases, which may cause a problem of evaporation residue and a decrease in deposition rate.

FIG. 2 shows the cumulative distribution of the powder. In the case of powder that is an aggregate of particles having different diameters, the relationship between the particle diameter and the accumulation is as shown in the figure. The particle径径the cumulative weight becomes 50% is referred to as a median diameter, expressed in D _50. In other words, when the powder is divided into two parts by a certain particle diameter, it is also a diameter in which the large side and the small side are of equal weight. Expressed by this D ₅₀ , the particle size of the small particle size SiO powder is preferably from 0.1 to 45 μm, more preferably from 0.3 to 20 μm. The particle size of the large particle size SiO powder is preferably 100 to 300 μm. If the particle size of the small particle size SiO powder is too small, the surface area of the raw material powder becomes excessive, which may cause a problem of evaporation residue due to oxidation of the particle surface and a problem of a decrease in deposition rate. On the contrary, if it is too large, the mechanical strength of the sintered body may be insufficient. If the particle size of the large particle size SiO powder is too small, the surface area of the raw material powder becomes excessive, which solves the original purpose of using the large particle size powder, that is, the problem of evaporation residue due to oxidation of the particle surface, and the problem of reduced deposition rate Effect is insufficient. On the other hand, if it is too large, the mechanical strength of the sintered body may be lowered.

  The sintering temperature is preferably 700 to 1000 ° C. 700-1000 degreeC is low temperature compared with the past. As described above, the necessary mechanical strength is ensured by using a small particle size powder even in such low temperature sintering. Even in the case of low temperature sintering, the necessary mechanical strength is not ensured at an extremely low temperature of less than 700 ° C. When the sintering temperature exceeds 1000 ° C., Si precipitates during the sintering process, which causes splash.

  The SiO sintered body produced by the production method of the present invention is suitable as a vapor deposition material, particularly an EB vapor deposition material in which tablet cracking due to a temperature difference in the vapor deposition process is remarkable.

  The method for producing a SiO sintered body according to the present invention has a problem when a large particle size SiO powder is sintered at a low temperature by using a large particle size SiO powder mixed with a small particle size SiO powder as a sintering raw material powder. Decrease in mechanical strength of the sintered body can be avoided, and damage to the vapor deposition material in the vapor deposition process can be prevented. And by using large particle size SiO powder, the evaporation residue in a vapor deposition process can be decreased, and the fall of a vapor deposition rate can be prevented. Moreover, the occurrence of splash in the vapor deposition process can be remarkably suppressed by low temperature sintering.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is an explanatory view of the production process of the silicon monoxide-based vapor deposition material of the present invention.

In this embodiment, a vapor deposition material is manufactured through the following steps. The first step is the production of the raw material (deposited SiO). In this step, deposited SiO is produced with a vacuum aggregating apparatus. The vacuum agglomeration apparatus includes a raw material chamber and a circular agglomeration chamber connected thereto. In operation, the raw material chamber is charged with a mixture of Si powder and SiO ₂ powder. The chamber is depressurized to a predetermined degree of vacuum and heated to a predetermined temperature (1200 to 1400 ° C.). As a result, SiO vapor is generated in the raw material chamber and introduced into the upper coagulation chamber. In the coagulation chamber, the coagulation tube temperature is controlled to several hundred degrees at the outer surface temperature, and SiO is deposited on the inner surface.

When the deposited SiO is produced by the vacuum aggregating apparatus, the deposited SiO is pulverized to a predetermined particle size by a pulverizer. The SiO powder produced by grinding is classified. Various particle sizes of well D ₅₀ D ₅₀ is the particle径粉of 1~45μm among powder selects the large径粉of 100 to 300 [mu] m, as the ratio of small径粉is 10 to 30 wt% To mix. When mixing is completed, the mixed powder is formed into a vapor deposition material (tablet) shape (usually a cylindrical shape) with a predetermined binder and sintered. The sintering temperature is 700 to 1000 ° C.

A powder having a D _{50 of 100} to 300 μm is an aggregate of coarse particles. Moreover, 700-1000 degreeC is low temperature compared with the past. Even in such low-temperature sintering of coarse grains, as described above, a predetermined mechanical strength is ensured by mixing small-diameter powders.

  Sintering may be performed by hot pressing, but it is more economical to perform sintering using a binder for molding. When the binder is used, the denseness is lowered, and its use has been regarded as a problem in the past. However, as described above, the denseness does not greatly affect the occurrence of splash. There are many economic benefits of using binders. As the binder, commercially available ones are not a problem, but those that can be removed at a low temperature of 500 ° C. or lower are particularly preferable. The addition amount of the binder is preferably 15 to 30% by weight. If the amount of the binder is too small, the moldability deteriorates. If the amount is too large, it becomes a slurry and the molding becomes difficult.

  The atmosphere and pressure during sintering may be an inert atmosphere and atmospheric pressure, and no fine control is required.

  Next, the result of investigating the characteristics of the SiO sintered body produced by such a method as a vapor deposition material will be described.

Precipitated SiO was produced with a vacuum aggregator. A small particle size powder having a D ₅₀ of 0.5 μm and a large particle size powder having a D ₅₀ of 125 μm obtained by pulverization and classification from the deposited SiO were mixed at a weight ratio of 20:80, and the diameter was 30 mm and the height was high. The binder was molded into a 40 mm tablet shape and sintered. The sintering temperature was 850 ° C. The sintering atmosphere and pressure were inert atmosphere and atmospheric pressure. A commercially available binder was used, and the amount added was 20% by weight.

  The produced tablet (deposition material) was measured and evaluated for evaporation residue, compressive fracture strength, and splash characteristics. The evaporation residue was measured by measuring the weight change when the sample was evaporated by a thermogravimetric instrument. When the weight change disappeared, the weight was expressed as a ratio with respect to the weight before the measurement, and 5% or less was good. The heating conditions were a vacuum atmosphere at a temperature of 1300 ° C. and a pressure of 10 Pa or less. The compressive fracture strength was 10 MPa or more. About the splash characteristic, the manufactured vapor deposition material was actually used for the vacuum vapor deposition test (ion plating), the number of pinholes in a base film was counted, and 10 or less was made favorable.

Table 1 shows the particle size distribution of the small particle size powder and the large particle size powder used in the production of the sintered body, and Table 2 shows the test conditions of the vacuum deposition test for evaluating the splash characteristics. And the evaluation result of each characteristic is shown in Table 3. For comparison, in the above-described example of the present invention, when the sintering raw material powder was only a large particle size powder having D ₅₀ of 125 μm (Comparative Example 1), the sintering temperature was increased to 1200 ° C. in Comparative Example 1. In the case (Comparative Example 2), in the case of the above invention example, the sintering raw material powder is only a small particle size powder having a D ₅₀ of 0.5 μm (Comparative Example 3) as the vapor deposition material for the sintered body. Was evaluated. The results are also shown in Table 3.

  In the example of the present invention in which a mixed powder of a small particle size powder and a large particle size powder is used as the sintering raw material powder, the evaporation residue characteristics, the compression fracture strength characteristics, and the splash characteristics are good. In Comparative Example 1 in which a single powder having a large particle size was used as the sintering raw material powder, the large particle size powder was sintered at a low temperature, and thus the compression fracture strength characteristics were poor. In Comparative Example 2 in which the sintering temperature is increased in Comparative Example 1, the compressive fracture strength characteristics turn well, but the splash characteristics are poor. In Comparative Examples 1 and 2, since a large particle size powder is used, the evaporation residue characteristics are good. On the other hand, in Comparative Example 3, since the single powder having a small particle size is sintered at low temperature, the compression fracture strength characteristic and the splash characteristic are good, but the evaporation residue characteristic is poor.

It is explanatory drawing of the particle size distribution of mixed powder. It is a cumulative distribution diagram for explaining the median D _50. It is explanatory drawing of the manufacturing process of SiO sintered compact.

Claims (4)

  A method for producing a SiO sintered body, characterized in that a large particle size SiO powder and a small particle size SiO powder are used as raw materials, and these are mixed and then molded and sintered.   The method for producing a SiO sintered body according to claim 1, wherein a mixing ratio of the small particle size SiO powder in the raw material is 10 to 30 wt%. The particle size of the small particle size SiO powder is 0.1~45μm at D _50, the manufacturing method of the SiO sintered body according to claim 1 the particle size of the large particle size SiO powder is 100~300μm at D ₅₀ .   The method for producing a SiO sintered body according to claim 1, wherein the sintering temperature is 700 to 1000 ° C.

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