JP5094183B2 - Metallic silicon powder and method for producing the same, spherical silica powder and resin composition - Google Patents

Description

  The present invention relates to a metal silicon powder suitable for a semiconductor encapsulant and a method for producing the same, a spherical silica powder produced using the metal silicon powder, and a resin composition using the spherical silica powder.

  A semiconductor package is generally sealed with a resin composition containing spherical silica powder in order to improve thermal properties (Patent Document 1). The resin composition containing spherical silica powder is solidified by advancing a polymerization reaction after filling and sealing a semiconductor using a dispersion of spherical silica powder in a liquid (solution) organic resin material. is there. If the spherical silica powder contains a predetermined amount or more of uranium, the α-rays emitted from the uranium may cause malfunction in the semiconductor to be sealed. Therefore, uranium contained is removed as much as possible. Particularly when the spherical silica powder is produced without controlling the concentration of uranium element (uranium concentration), the uranium concentration is around 30 ppb.

For the purpose of reducing the uranium content in the spherical silica powder, the uranium content in the raw metal silicon is reduced. For example, uranium content is reduced by dissolving and removing uranium aggregated by segregation with hydrofluoric acid or the like.
JP 2000-63630 A

  By the way, it has been found that even if a semiconductor encapsulant is manufactured using metal silicon powder whose uranium content is controlled within an appropriate range, sufficient performance may not be exhibited. According to the study of the present inventors, there are elements that cannot be removed even if purification is performed to remove uranium from metallic silicon, and if the content of phosphorus (P) among these elements is not controlled within a predetermined range, The electrical conductivity of the manufactured semiconductor encapsulant has increased, and there has been a problem associated with exceeding the upper limit of the electrical conductivity required for the semiconductor encapsulant depending on the type of semiconductor to be applied.

  The present invention has been made in view of the above circumstances, and also controls the phosphorus content as well as the uranium content, and when applied to a semiconductor encapsulant, a metal silicon powder capable of realizing higher performance and a method for producing the same Providing is a problem to be solved. Another object to be solved is to provide a high-purity spherical silica powder produced from the metal silicon powder. Furthermore, it is also a problem to be solved to provide a resin composition produced from the spherical silica powder.

  The metal silicon powder of the present invention is a metal silicon powder used for producing spherical silica powder by reacting with oxygen in a flame.

  As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found the appropriate content range for the phosphorus content in addition to the uranium content, and have completed the following invention. That is, the metal silicon powder of the present invention is characterized by containing uranium element at 10 ppb or less on a mass basis and phosphorus element at 100 ppm or less, 1 ppm or more on a mass basis. In particular, the concentration of the uranium element is preferably 5 ppb or less.

The method for producing a metal silicon powder of the present invention is a silicon content of more than 99 wt%, 100 ppm or less of phosphorus element based on the weight, grinding process of the crushed product was pulverized metal silicon feedstock containing more than 1ppm And a removing and cleaning step of immersing the pulverized product in an inorganic acid containing at least hydrofluoric acid and then cleaning with a cleaning liquid. The produced metal silicon powder contains uranium element in a mass basis of 10 ppb or less and phosphorus element in a mass basis of 100 ppm or less and 1 ppm or more.

  The spherical silica powder of the present invention that solves the above problems is manufactured by introducing the above-described metal silicon powder or the metal silicon powder manufactured by the above-described manufacturing method into an oxygen-excessive oxygen flame together with a carrier gas. Features.

  The resin composition of the present invention that solves the above problems is characterized by having the aforementioned spherical silica powder and an organic resin material in which the spherical silica powder is dispersed.

  The metal silicon powder of the present invention has the above-described composition, so that when a spherical silica powder is produced and applied to a semiconductor encapsulant, it is used for applications that require high performance such as reducing the uranium content. Even if it exists, it becomes possible to demonstrate high performance. Specifically, when spherical silica powder is produced by controlling phosphorus within a predetermined range, a resin composition with improved fluidity is produced by improving the wettability with respect to the organic resin material constituting the resin composition. In addition, the electrical conductivity of the resin composition can be reduced.

  Hereinafter, the metal silicon powder, the manufacturing method thereof, the spherical silica powder and the resin composition of the present invention will be described in detail based on the embodiments. The metal silicon powder, spherical silica powder, production method thereof, spherical silica powder and resin composition of the present invention are not limited to the following embodiments, and those skilled in the art within the scope not departing from the gist of the present invention. The present invention can be implemented in various forms that can be changed and improved.

<Metal silicon powder and production method thereof>
The uranium content of the metal silicon powder of the present embodiment is controlled to 10 ppb or less, particularly preferably 5 ppb or less, and more preferably 1 ppb or less and 0.5 ppb or less. The method for reducing the uranium content is not particularly limited, but employs a purification step in which uranium contained in the surface is segregated on the surface by melting and solidifying the metal silicon raw material and then pulverized and the surface is washed with an inorganic acid. Thus, impurities containing uranium segregated on the surface can be removed. This purification step can be repeated as necessary.

  The concentration of phosphorus is 1 ppm or more and 100 ppm or less. The phosphorus concentration can be 50 ppm or less, and is preferably 40 ppm or less. Furthermore, it is desirable to make it 20 ppm or less. As a lower limit, 2 ppm or more can be adopted, and 5 ppm or more and 10 ppm or more can also be adopted.

  The method for controlling the concentration of phosphorus is not particularly limited, but the concentration of phosphorus is controlled independently of the uranium content because it cannot be controlled by the aforementioned method of reducing the uranium content. As a specific method for controlling the concentration of phosphorus, a method of adding a necessary amount when the phosphorus content is low, and evaporating and removing phosphorus when the phosphorus content is high can be exemplified. A case where the phosphorus content is low may be a case of purification by a monosilane method or a trichlorosilane method for the purpose of producing a raw material for producing a semiconductor itself such as a wafer. Examples of the case where the phosphorus content is high include general unpurified metal silicon.

<Spherical silica powder and production method thereof>
The spherical silica powder of the present embodiment is a spherical silica powder produced by the so-called VMC method using the above-described metal silicon powder. In the VMC (Vaperized Metal Combustion) method, a chemical flame is formed by a burner in an oxygen-containing atmosphere, and metal silicon powder is introduced into the chemical flame in such an amount that a dust cloud is formed. This is a method for obtaining physical particles. Specifically, it is a spherical silica powder obtained by putting the above-described metal silicon powder together with a carrier gas into an oxygen-excess oxide flame.

The operation of the VMC method will be described as follows. First, the container is filled with a gas containing oxygen as a reaction gas, and a chemical flame is formed in the reaction gas. Next, metal powder is introduced into the chemical flame to form a dust cloud with a high concentration (500 g / m ³ or more). Then, thermal energy is given to the metal powder surface by the chemical flame, the surface temperature of the metal powder rises, and metal vapor spreads from the metal powder surface to the surroundings. This metal vapor reacts with oxygen gas to ignite and produce a flame. The heat generated by the flame further promotes the vaporization of the metal powder, and the generated metal vapor and the reaction gas are mixed and propagated in a chain. At this time, the metal powder itself is destroyed and scattered, which promotes flame propagation. The product gas is naturally cooled after combustion, thereby forming a cloud of oxide particles. The obtained oxide particles are collected by a bag filter, an electric dust collector or the like.

  The VMC method uses the principle of dust explosion. According to the VMC method, a large amount of oxide particles can be obtained instantaneously. The resulting oxide particles have a substantially spherical shape. It is possible to adjust the particle diameter of the resulting spherical silica powder by adjusting the particle diameter of the metal silicon powder to be input, the input amount, the flame temperature, and the like. In addition to the metal silicon powder, silica powder can be added as a raw material. The silica powder can maintain the purity of the spherical silica powder obtained by adopting the spherical silica powder obtained by this method.

  When the obtained spherical silica powder is mixed with the resin composition, it can be subjected to a surface treatment for the purpose of improving the adhesion with the resin. For example, various silane, titanate, aluminate and zirconate coupling agents, cations, anions, amphoteric and neutral surfactants can be mixed.

<Resin composition>
The resin composition of the present embodiment is obtained by mixing the spherical silica powder and the organic resin material, and dispersing the spherical silica powder in the organic resin material. The resin composition can be used as a semiconductor liquid sealing material for sealing semiconductor elements, and can also be used for substrate materials, inorganic pastes, adhesives, coating agents, precision molding resins, and the like.

  Since the spherical silica powder is as described above, further explanation is omitted. The spherical silica powder is preferably contained in an amount of 40% by mass or more, more preferably 50% by mass or more based on the total mass.

  Examples of organic resin materials include epoxy resins, oxirane resins, oxetane compounds, cyclic ether compounds, cyclic lactone compounds, thiirane compounds, cyclic acetal compounds, cyclic thioether compounds, spiro orthoester compounds, vinyl compounds, and the like. It can be used alone or in combination.

  In particular, an epoxy resin is preferable from the viewpoints of availability, handleability, and the like. Although an epoxy resin is not specifically limited, The monomer, oligomer, and polymer which have two or more epoxy groups in 1 molecule are mentioned. For example, biphenyl type epoxy resin, stilbene type epoxy resin, bisphenol type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, naphthol type epoxy resin, triazine core containing An epoxy resin is mentioned.

  Specific examples other than the epoxy resin include oxirane compounds such as phenylglycidyl ether, ethylene oxide and epichlorohydrin; oxetane compounds such as trimethylene oxide, 3,3-dimethyloxetane and 3,3-dichloromethyloxetane; tetrahydrofuran, 2 Cyclic ether compounds such as 1,3-dimethyltetrahydrofuran, trioxane, 1,3-dioxofuran, 1,3,6-trioxacyclooctane; cyclic lactone compounds such as β-propiolactone and ε-caprolactone; ethylene sulfide, 3, Thiane compounds such as 3-dimethylthiirane; Thiane compounds such as 1,3-propyne sulfide and 3,3-dimethyl thietane; Cyclic thioether compounds such as tetrahydrothiophene derivatives; Spiro ortho ester compounds obtained by reaction with kuton; spiro ortho carbonate compounds; cyclic carbonate compounds; vinyl compounds such as ethylene glycol divinyl ether, alkyl vinyl ether, triethylene glycol divinyl ether; styrene, vinyl cyclohexene, isobutylene, polybutadiene, etc. An ethylenically unsaturated compound can be illustrated. As a cationically polymerizable compound, an epoxy resin and these compounds can be used alone or in combination.

  As a curing agent to be added when an epoxy resin is employed, a primary amine, a secondary amine, a phenol resin, or an acid anhydride may be used. As a curing catalyst, Bronsted acid, Lewis acid, basic catalyst, or the like may be used. Used. As the basic catalyst, imidazole, dicyandiamide, amine adduct, phosphine, and hydrazide are used.

  The spherical silica powder and resin composition of the present invention will be described in more detail based on examples.

<Example 1>
The phosphorus content of the metal silicon raw material having a purity of 99.7% by mass was controlled to 5 ppm. The metal silicon raw material was pulverized to a particle size of 2 mm or less, and then immersed in a 3% hydrofluoric acid aqueous solution for 24 hours with stirring. Thereafter, the metal silicon was filtered off and washed with pure water as a washing liquid. The washing was performed until the electric conductivity of the washing liquid did not change before and after washing. Then, it was made to dry and it was set as the metal silicon powder of a present Example. Table 1 shows the uranium content and phosphorus content of the obtained metal silicon powders of Examples. Table 1 also shows the uranium content and phosphorus content for the metal silicon powders of the following examples and comparative examples.

<Example 2>
The phosphorus content of the metal silicon raw material having a purity of 99.5% by mass was controlled to 30 ppm. The metal silicon raw material was pulverized to a particle size of 2 mm or less, and then immersed in a 3% hydrofluoric acid aqueous solution for 24 hours with stirring. Thereafter, the metal silicon was filtered off and washed with pure water as a washing liquid. The washing was performed until the electric conductivity of the washing liquid did not change before and after washing. Then, it was made to dry and it was set as the metal silicon powder of a present Example.

<Example 3>
The phosphorus content of the metal silicon raw material having a purity of 99% by mass was controlled to 70 ppm. The metal silicon raw material was pulverized to a particle size of 2 mm or less, and then immersed in a 3% hydrofluoric acid aqueous solution for 24 hours with stirring. Thereafter, the metal silicon was filtered off and washed with pure water as a washing liquid. The washing was performed until the electric conductivity of the washing liquid did not change before and after washing. Then, it was made to dry and it was set as the metal silicon powder of a present Example.

<Comparative example 1>
The phosphorus content of the metal silicon raw material having a purity of 99% by mass was controlled to 110 ppm. The metal silicon raw material was pulverized to a particle size of 2 mm or less, and then immersed in a 3% hydrofluoric acid aqueous solution for 24 hours with stirring. Thereafter, the metal silicon was filtered off and washed with pure water as a washing liquid. The washing was performed until the electric conductivity of the washing liquid did not change before and after washing. Then, it was made to dry and it was set as the metal silicon powder of this comparative example.

<Comparative example 2>
The high-purity metal silicon pulling ingot for silicon wafers was pulverized to obtain the metal silicon powder of this comparative example.

(Production of spherical silica powder)
Spherical silica powder having a volume average particle size of 0.5 μm was produced by the VMC method using the metal silicon powders of the examples and comparative examples.

  The spherical silica powder and resin composition of the present invention will be described in more detail based on examples. The raw material powder was put into the spherical silica particle explosion combustion apparatus of each example and comparative example.

Specifically, oxygen as a carrier gas and propane gas as a combustible gas were respectively introduced into a reaction vessel, and then ignited with a burner to form a flame, thereby sufficiently drying the inside of the reaction vessel. Carrier gas was introduced into the reaction vessel at a flow rate of 20 Nm ³ / hour and combustible gas at a flow rate of 1.0 Nm ³ / hour.

  Next, the metal silicon powder was oxidized by introducing it into the reaction vessel through a burner at a supply rate of 10 kg / hour with a carrier gas and ejecting it into the flame. The raw material metal silicon powder formed spherical silica powder by oxidation. The uranium content and phosphorus content of the obtained spherical silica powder and the electrical conductivity of the extract were measured. The results are shown in Table 2. For electrical conductivity, each spherical silica powder was suspended in ion-exchanged water and made into a 10% slurry, placed in a pressure vessel, and shaken at room temperature for 30 minutes. Thereafter, the supernatant liquid centrifuged down was measured with a conductivity meter ES-51 manufactured by Horiba, Ltd. The conductivity of ion-exchanged water as a control was 1.4 μS / cm.

(Manufacture of resin composition)
The spherical silica powder of each Example and Comparative Example was dispersed in a liquid resin (manufactured by Toto Kasei Co., Ltd., ZX-1059) to prepare a resin composition. The mixing ratio was 1: 1 by mass ratio. The thixo ratio, which is a viscosity ratio between a shear rate of 0.1 sec- ¹ and 10 sec- ¹ , was measured for the obtained resin composition. The thixo ratio is a value indicating that the higher the value, the lower the fluidity. The results are shown in Table 3.

  As is clear from Tables 1 to 3, it was found that the resin compositions of Examples 1 to 3 had low electrical conductivity and a thixo ratio and could be suitably used for liquid sealing applications such as underfill. On the other hand, although the resin composition of Comparative Example 1 had a low thixo ratio, the electrical conductivity was high. And although the resin composition of the comparative example 2 had low electrical conductivity, it turned out that thixo ratio is very high and the filling property to a narrow clearance gap is not enough.

  That is, by controlling the phosphorus content to be low (100 ppm or less) from the results of Examples 1 to 3, the electrical conductivity can be lowered as compared with the case of containing 110 ppm of phosphorus as in Comparative Example 1. Although it was possible, it was revealed that the thixo ratio was increased when the content was reduced to less than 1 ppm as in Comparative Example 2. Therefore, it became clear that it is desirable to contain phosphorus within a predetermined range.

Claims (5)

The metal silicon powder used for producing spherical silica powder by reacting metal silicon powder with oxygen in a flame,
A metallic silicon powder comprising 10 ppb or less of uranium element and 100 ppm or less and 1 ppm or more of phosphorus element on a mass basis.   The metal silicon powder according to claim 1, wherein the concentration of the uranium element is 5 ppb or less. And a silicon content of more than 99 wt%, 100 ppm or less of phosphorus element based on the weight, the pulverization step to pulverized by pulverizing metal silicon feedstock containing more than 1 ppm,
A removal cleaning step of immersing the pulverized material in an inorganic acid containing at least hydrofluoric acid and then cleaning with a cleaning liquid;
The manufacturing method of the metal silicon powder which contains 10 ppm or less of uranium elements on a mass basis, and 100 ppm or less and 1 ppm or more of a phosphorus element on a mass basis.   The metal silicon powder according to claim 1 or 2 or the metal silicon powder produced by the production method according to claim 3 is produced by introducing it into an oxygen-excessive oxide flame together with a carrier gas. Spherical silica powder.   A resin composition comprising the spherical silica powder according to claim 4 and an organic resin material in which the spherical silica powder is dispersed.