Spherical silica composition, resin composition, slurry composition, filler for sealing material for semiconductor package, and method for analyzing voids in spherical silica composition

Abstract

The present invention provides a spherical silica composition that is suitable for a filler for a sealing material for a semiconductor package, and the like by improving the quality of particles of the spherical silica composition by accurately understanding the properties of voids which are present in the particles of the spherical silica composition. There is provided a spherical silica composition that contains silica as a main component. If the spherical silica composition is filled into a resin material so that the solid content concentration of the spherical silica composition is 70 mass%, particles of the spherical silica composition containing voids of 150 μm3 or more are 14 particles / mm3 or less as detected by tomographic cross-sectional analysis of the resin composition, and particles of the spherical silica composition containing voids of 35 μm3 or more are 60 particles / mm3 or less as detected by the tomographic cross-sectional analysis.

Description

Spherical silica composition, resin composition, slurry composition, filler for sealing material for semiconductor package, and method for analyzing voids in spherical silica composition

[0001] The present invention relates to a spherical silica composition, a resin composition, a slurry composition, a filler for a sealing material for semiconductor packages, and a method for analyzing voids in a spherical silica composition, and in particular to a spherical silica composition having voids therein and a composition containing the same.

[0002] Encapsulant is used to protect semiconductor IC chips from dust, dirt, and moisture in the air, and the IC chips are encapsulated to create semiconductor packages. The encapsulant is primarily a resin composition made up of a resin with high heat and chemical resistance and silica with a low thermal expansion coefficient. There are several methods for manufacturing semiconductor packages depending on the application and required performance. Fan-Out Wafer Level Package (FOWLP) and Fan-Out Panel Level Package (FOPLP) are used for packages that require high functionality and small size and are installed in mobile devices.

[0003] Various FOWLP processes include a polishing process to smooth the surface of the semiconductor package containing the encapsulant after encapsulating the IC chip. If hollow particles are present in the encapsulant, or if cavities are formed in the encapsulant due to the inclusion of air bubbles or other contaminants, depressions will form on the polished package surface, reducing surface smoothness and appearance, resulting in lower yields. Particularly in processes that involve polishing the surface of a semiconductor package and then forming a rewiring layer on that surface, the presence of hollow particles in the encapsulant can result in copper wiring being formed on the depressions on the package surface. In this state, if the package expands or contracts due to changes in the temperature environment, the hollow spaces in the depressions can cause the copper wiring to break and become disconnected. Without the hollow spaces, the copper wiring is surrounded by the encapsulant, preventing it from breaking even when it expands or contracts. Furthermore, while conventional copper wiring has a large line width of over 10 μm, making it highly rigid and resistant to breakage, as package functionality becomes more sophisticated and the line width becomes smaller, the rigidity of the copper wiring also decreases. For this reason, attention has been focused on reducing the amount of hollow particles contained in the encapsulating material (see, for example, Patent Documents 1 and 2).

[0004] Packages for servers have a different structure and manufacturing process than those described above. The package is mounted on an interposer or similar device using a flip-chip structure, and then the entire package is sealed. There are also manufacturing methods that involve two steps: underfilling the narrow gap under the chip and overmolding to protect the entire chip. There are also manufacturing methods that seal both the chip and the top of the chip at the same time. High fluidity is particularly required for bulk sealing. These types of packages also require a surface polishing process to smooth the package surface, and, as with the above, a low hollow particle content in the encapsulant filler is strongly required.

[0005] JP 2022-117398 A JP 2021-161008 A

[0006] As semiconductor packages become smaller and wiring becomes finer to meet the above-mentioned required characteristics, it is necessary to precisely remove the solid coarse particles used in fillers, and the size of the coarse particles that need to be removed is also becoming smaller.In addition, it is required to reduce the voids present inside the filler particles as much as possible, and therefore measuring the voids present inside filler particles is important from the perspective of quality control.

[0007] However, in conventional particle void measurement, the cross section of the particle is exposed by embedding it in resin or the like and grinding it. Therefore, the solid part of the particle and the void within it are measured. However, depending on the grinding position, the center of the void varies, and it is not necessarily the center of the filler, resulting in misalignment between the two. Even if the filler particle is cut to expose its cross section, the exact diameter of the void sphere is not exposed. The size and volume of the void are calculated from the cross-sectional diameter at a position away from the center, resulting in large errors. Furthermore, factors such as deformation or clogging of the void due to loads during grinding can cause errors. In particular, the larger the volume of the void, the more likely it is that a defect will occur due to a recess during the formation of the redistribution layer. This is because the resin components of the redistribution layer flow into the recess, causing localized loss of flatness.

[0008] The present invention has been made in consideration of the above points, and aims to accurately grasp the properties of the voids present in the particles of a spherical silica composition, thereby improving the quality of the particles of the spherical silica composition, and to provide a spherical silica composition suitable for use in resin compositions, slurry compositions, and fillers for sealing materials for semiconductor packages, and also to provide a method for analyzing the voids in a spherical silica composition.

[0009] That is, the spherical silica composition of the embodiment is a spherical silica composition containing silica as a main component, and when filled into a resin material in which the solid content concentration of the spherical silica composition is 70 mass %, the spherical silica composition has a diameter of 150 μm detected by cross-sectional analysis of the resin composition. ３ The particles of the spherical silica composition containing the above voids are 14 particles / mm ３ 35 μm or less detected by tomographic cross-section analysis ３ The particles of the spherical silica composition containing the above voids are 60 particles / mm ３ The present invention is characterized in that:

[0010] Furthermore, in the spherical silica composition, the cross-sectional analysis may be performed by X-ray CT or FIB-SEM.

[0011] Furthermore, the spherical silica composition may have an average particle size of 1.5 to 15 μm as measured by laser diffraction particle size distribution, and a mode diameter of 1.9 μm or more as measured by laser diffraction particle size distribution.

[0012] Furthermore, in the spherical silica composition, the particles of the spherical silica composition containing voids with a diameter of 5 μm or more are 50 particles / mm ３ The particles of the spherical silica composition containing voids of 10 μm or more in diameter are 5 particles / mm ３ It may be the following.

[0013] Furthermore, the spherical silica composition may contain 100 ppm or more of crystalline silica.

[0014] Furthermore, the spherical silica composition may have a uranium content of 5 ppb or less and a sodium content of 100 ppb or less.

[0015] Furthermore, the spherical silica composition may be surface-treated with a silane compound.

[0016] It may also be a resin composition having a spherical silica composition and a resin material that disperses the spherical silica composition, or a composition having a spherical silica composition and a dispersion medium that disperses the spherical silica composition, or a filler for a sealing material for semiconductor packages that contains the spherical silica composition.

[0017] In addition, the method for analyzing voids in a spherical silica composition according to the embodiment is characterized by comprising a dispersion step of dispersing the spherical silica composition in a resin composition, a cross-sectional analysis step of performing cross-sectional analysis of the spherical silica composition together with the resin composition using X-ray CT or FIB-SEM, and a void calculation step of preparing a three-dimensional image from the cross-sectional analysis and calculating the diameter and volume of voids present in the spherical silica composition. Furthermore, a curing step of curing the resin composition may be provided after the dispersion step.

[0018] According to the spherical silica composition of the present invention, the spherical silica composition is a spherical silica composition containing silica as a main component, and when filled into a resin material in which the solid content concentration of the spherical silica composition is 70 mass %, the spherical silica composition has a particle size of 150 μm detected by cross-sectional analysis of the resin composition. ３ The particles of the spherical silica composition containing the above voids are 14 particles / mm ３ 35 μm or less detected by tomographic cross-section analysis ３ The particles of the spherical silica composition containing voids of 60 particles / mm ３ Therefore, the properties of the voids present in the spherical silica particles can be accurately grasped, thereby improving the quality of the spherical silica particles. Furthermore, by applying the method for analyzing the voids in the spherical silica composition, the accuracy of measuring the voids present in the spherical silica composition can be improved.

[0019] The spherical silica composition, resin composition, slurry composition, filler for semiconductor package encapsulant, and method for analyzing voids in the spherical silica composition according to the embodiment are described below. The spherical silica particles according to the embodiment can be dispersed in a resin material to form a resin composition, or dispersed in a liquid dispersion medium to form a slurry composition. They are particularly suitable for use as fillers for semiconductor package encapsulants.

[0020] (Spherical silica composition and filler for semiconductor package encapsulant) The spherical silica composition of the embodiment is in particulate form and is suitable for use as a filler for semiconductor package encapsulant. It is preferably applied to semiconductors produced using FOWLP or FOPLP technology.

[0021] The spherical silica composition of the embodiment is silicon oxide (SiO ２ ) as the main component, and silicon oxide accounts for 50% or more, preferably 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, based on the mass of the spherical silica composition. The spherical silica composition is a mixture of amorphous and crystalline silica, and the crystalline silica contains 100 ppm or more of crystalline silica. This is because the spherical silica composition is derived from natural quartz.

[0022] The size of the spherical silica composition was measured by laser diffraction particle size distribution measurement. ５０ (median diameter) is 1.5 μm or more and 15 μm or less. ５０ Examples of lower limit values ​​are 1.6 μm, 1.8 μm, 2.0 μm, and 2.2 μm, and examples of upper limit values ​​are 14.0 μm, 11.0 μm, 9.0 μm, 8.0 μm, 7.0 μm, and 6.0 μm. These upper and lower limit values ​​can be combined arbitrarily. Furthermore, the mode diameter (most frequent diameter) is 1.9 μm or more, preferably 2.3 μm or more.

[0023] D ５０ is a value measured by laser diffraction particle size distribution measurement, and is the particle size that accounts for 50% of the smallest particle size on a volume basis. １００ is the particle size of 100% from the smallest particle size. ５０ , D １００The value of D is calculated as a numerical value within the range of the measurement limit of laser diffraction particle size distribution measurement, and in reality, there are coarse particles and fine particles that cannot be detected by laser diffraction particle size distribution measurement. １００ There is no contradiction in the existence of particles with a particle size larger than the value of .

[0024] D ５０ The value of is controlled by the manufacturing conditions of the spherical silica composition. In addition, it is adjusted by a classification operation and the addition of particulate materials with other particle size distributions. For the classification operation, a centrifugal separator such as a cyclone is preferably used. The added particulate materials are also classified.

[0025] The viscosity of the resin composition when filled into a resin material at a solid content of 75% by mass is 1500 Pa·s or less (at a shear rate of 1 s －１ ), preferably 500 Pa s or less, more preferably 400 Pa s or less. As the resin material, an epoxy resin obtained by mixing bisphenol A type epoxy resin and bisphenol F type epoxy resin in a 1:1 ratio is used (for example, ZX-1059 manufactured by Nippon Steel Chemical Materials Co., Ltd.).

[0026] The specific surface area of ​​the spherical silica composition is 1.0 m ２ / g or more 10m ２ The lower limit of the specific surface area is 0.2 m ２ / g, 0.5m ２ / g, 0.8m ２ / g, and the upper limit is 6m ２ / g, 5m ２ / g, 4m ２ / g is an example of the specific surface area. The specific surface area is a value measured by the BET method using nitrogen. A smaller specific surface area is preferable because it reduces the viscosity when used in a slurry composition or the like. The method for controlling the specific surface area is not particularly limited, and the specific surface area can be adjusted by performing the synthesis of a spherical silica composition under conditions that reduce the amount of fine powder, or by controlling the residence time in a classifier to be longer during classification, thereby reducing the amount of fine powder.

[0027] The voids contained in the spherical silica composition refer to hollow particles, which are bubbles that occur during the manufacturing process of the spherical silica composition. Obviously, the fewer voids (hollow particles) there are, the better. However, they inevitably occur during the manufacturing process of the spherical silica composition.

[0028] Voids (hollow particles) The hollow particles are based on the spherical silica composition when filled into a resin material so that the solid content concentration after addition is 70 mass %. ３ The particles of the spherical silica composition having the above voids are 14 particles / mm ３ Below, 10 pieces / mm ３ Below, 5 pieces / mm ３ or less, and most preferably 0 pieces / mm ３ In total, it is 35 μm or less. ３ The particles of the spherical silica composition having the above voids are 60 particles / mm ３ Below, 30 pieces / mm ３ Below, 15 pieces / mm ３ and most preferably 10 pieces / mm ３ The following is the result.

[0029] Furthermore, based on the case where the spherical silica composition is filled into a resin material so that the solid content concentration after addition is 70 mass %, the number of particles of the spherical silica composition having voids with a diameter of 5 μm or more is 50 / mm ３ Below, 30 pieces / mm ３ Below, 10 pieces / mm ３ and most preferably 10 pieces / mm ３ In addition, the number of particles of the spherical silica composition having voids of 10 μm or more in diameter is 10 particles / mm ３ Below, 5 pieces / mm ３ and most preferably 3 particles / mm ３ The following is the result.

[0030] The size of the voids (hollow particles) contained in each spherical silica composition has been evaluated by their diameter. To measure the diameter of the voids (hollow particles), the spherical silica composition is embedded in a resin or the like, and then the resin block is cut to measure the diameter of the voids (hollow particles) from the cut surface of the spherical silica composition exposed on the cross section. However, when cutting the resin block, the spherical silica composition is dispersed in the resin, so the position of the spherical silica composition that becomes the cut surface is completely random. For example, if the cut surface is located away from the center of the spherical silica composition, the voids exposed on the cut surface of the spherical silica composition are measured as having an apparently small diameter. It is impossible for the entire spherical silica composition to be cut exactly at the center of the sphere. Therefore, measuring the size of the voids (hollow particles) based on the cutting position lacks precision.

[0031] Therefore, if one wishes to precisely measure the size of the voids (hollow particles), it is necessary to grasp the void diameters in multiple cross-sectional portions of the spherical silica composition. Taking this into consideration, in an embodiment, a cross-sectional analysis is performed. Specifically, X-ray CT or FIB-SEM is used for the analysis. When using X-ray CT, a cross-sectional image of the resin mass in which the spherical silica composition is dispersed is taken. It is desirable that the imaging interval (pitch) between the tomograms be a fine range, such as 1 μm or less. From each tomogram, the diameter of the voids (hollow particles) present within each spherical silica composition can be measured more precisely. The volume of the voids (hollow particles) is then calculated. Even if the shape of the voids is not spherical but distorted, the volume of the distorted voids can also be calculated from image analysis of the combined tomograms.

[0032] When using FIB-SEM, a focused ion beam is irradiated and scanned onto a resin mass in which a spherical silica composition is dispersed, gradually grinding the surface in a fine range of 1 μm or less. As a result, the voids (hollow particles) present within each spherical silica composition are gradually exposed. The diameter of each void present within each spherical silica composition is then measured according to the amount (depth) of grinding caused by ion beam irradiation. Using FIB-SEM, the volume of the voids (hollow particles) can also be calculated, and it is also possible to measure voids with irregular shapes.

[0033] The aforementioned number of measurements is a number calculated from analysis using X-ray CT or FIB-SEM. The measurement conditions for X-ray CT or FIB-SEM are to cut in at a pitch of 1 μm or less and observe the void diameter at which the diameter is greatest, or to construct three-dimensional data, and calculate the void diameter and void volume within the particle from the difference in contrast (brightness and darkness) between the surrounding resin, the spherical silica composition, and the voids. Alternatively, X-ray CT data is acquired under conditions of a voxel size of 2 μm or less, and the void diameter and void volume within the particle are calculated from the contrast difference. When analyzing using X-ray CT or FIB-SEM, the analysis range is 0.5 mm ３ That's all.

[0034] An essential point of view is to accurately measure the number of hollow particles with large void volumes. In fact, the void volume (volume) measured using X-ray CT or the like as in the embodiment deviates from the theoretical sphere volume calculated from the void diameter. This is because the void shape within the particle is often not a perfect sphere. By performing the cross-sectional analysis of the embodiment, the diameter and volume of the voids (hollow particles) for each spherical silica composition can be accurately detected and calculated. This improves the accuracy of quality control of the finished spherical silica composition. In particular, this contributes greatly to improving the yield when processing wiring with narrower line widths.

[0035] (Method for analyzing voids in spherical silica composition) The method for analyzing voids in a spherical silica composition can be summarized as follows: First, the spherical silica composition is dispersed in a resin composition. The resin is of the composition described above. The solids concentration of the spherical silica composition in the resin composition is adjusted to 60 to 80% by mass, preferably 70% by mass (dispersion step). The purpose of the dispersion step in the resin is to fix the position of the individual spherical silica composition particles for subsequent measurement analysis. Furthermore, after the dispersion step, a curing step is added to harden the resin composition. In this curing step, the resin composition is heated and irradiated with ultraviolet light, and the resin composition is prepared into a cured resin. Obviously, a thermosetting resin or an ultraviolet-curable resin is selected for the resin composition.

[0036] The spherical silica composition together with the resin composition is subjected to cross-sectional analysis using X-ray CT or FIB-SEM (cross-sectional analysis step). The method of cross-sectional analysis is as described above. A three-dimensional image is prepared from the cross-sectional analysis, and the diameter and volume of voids present within the spherical silica composition are calculated (void calculation step). The cross-sectional analysis step and void calculation step can be performed in a consistent manner, and the analysis range, voxel size, etc. are appropriately adjusted to calculate the maximum diameter and volume of voids (hollow particles) present within each spherical silica composition.

[0037] The total amount of alkali metals and alkaline earth metals in the spherical silica composition of the embodiment is preferably 100 ppm, 80 ppm or less, 50 ppm or less, or 30 ppm or less. The reduction of alkali metals and alkaline earth metals can be achieved by purifying the materials used in producing the spherical silica composition. In particular, the sodium content in the spherical silica composition is 100 ppb or less, preferably 50 ppb or less, and more preferably 30 ppb or less.

[0038] Since alkali metals and alkaline earth metals are oxidized and eluted as ions, their application to encapsulants for semiconductor devices and the like is expected to have unexpected effects on the semiconductor devices. For example, assuming the electrical conductivity (EC) of the aqueous extract, it is desirable for it to be 10 μS / cm or less. Since a low content of alkali metals and alkaline earth metals is desirable to achieve a low value, the above-mentioned content ranges have been set. Electrical conductivity (EC) is measured as follows: The spherical silica composition is suspended in ion-exchanged water (electrical conductivity 1 μS / cm or less) to form a 10% slurry, which is then placed in a pressure-resistant container and shaken at room temperature for 30 minutes. The supernatant liquid, which has been centrifuged, is measured for its electrical conductivity using a Horiba, Ltd. ES-51 electrical conductivity meter (EC meter).

[0039] The spherical silica composition of the embodiment is preferably surface-treated with a surface treatment agent such as a silane compound or a silazane compound. The silane compound or silazane compound is not particularly limited, and a silane compound or silazane compound having an appropriate functional group can be selected as needed for the surface treatment. Surface treatment can also be performed using a combination of two or more silane compounds and silazane compounds.

[0040] For the spherical silica composition of the embodiment, the amount of alpha rays produced is 0.001 c / cm ２ In particular, it is desirable that the uranium and thorium as alpha ray sources are each 5 ppb or less, preferably 3 ppb or less, and more preferably 1 ppb or less.

[0041] (Method for Producing Metal Oxide Particle Material) The method for producing a spherical silica composition according to the embodiment includes a production step, a classification step, and other steps that may be adopted as necessary.

[0042] - Manufacturing process The manufacturing process is a process in which raw particle materials are combusted to produce a spherical silica composition. The raw particle materials produced have a volume average particle size of 1 μm or more and 15 μm or less. This volume average particle size range is the same as the volume average particle size range of the spherical silica composition to be produced. Although a classification process to remove coarse particles is performed later, it is preferable to remove as few coarse particles as possible, and the volume average particle size will be the same as that of the spherical silica composition to be produced.

[0043] The manufacturing process is known as the VMC (Vaporized Metal Combustion) Method, which utilizes the deflagration phenomenon of metal powder to produce spherical oxide microparticles. The spherical silica composition produced by the VMC method has high sphericity, is dense, and has excellent electrical properties. Metallic silicon is used as the raw particle material. The VMC method involves burning a combustible (such as hydrocarbon gas) with a burner in an oxygen-containing atmosphere to form a chemical flame as a high-temperature atmosphere, and then introducing an amount of raw particle material into this chemical flame that is sufficient to form a dust cloud, causing deflagration to occur, thereby obtaining a spherical silica composition. The high-temperature atmosphere is preferably an atmosphere of 2000°C or higher.

[0044] The VMC method works as follows: First, a container is filled with a gas containing oxygen, which is a reactive gas, and a chemical flame is formed in this reactive gas. Next, raw material particles are introduced into this chemical flame to form a dust cloud. The chemical flame then imparts thermal energy to the surface of the raw material particles, raising the surface temperature of the metals that make up the raw material particles, causing the vapor of the contained metals to spread from the surface of the raw material particles to the surrounding area. This vapor reacts with oxygen gas, igniting and generating a flame. The heat generated by this flame further promotes the vaporization of the raw material particles, and the resulting vapor and oxygen gas mix, causing a chain reaction of ignition and propagation. Therefore, the smaller the particle size of the raw material particles, the larger the specific surface area and the improved reactivity, allowing for less energy input.

[0045] In addition to the preparation of spherical silica compositions by the VMC method described above, spherical silica compositions can also be prepared by a flame fusion method or the like. In the preparation of spherical silica compositions by the flame fusion method, the raw material crystalline silica is pulverized to, for example, 5 μm or less, and then granulated according to the desired particle size. Alternatively, the crystalline silica is heated to, for example, above 1000° C., which gasifies the moisture in the voids contained in the crystalline silica, thereby reducing the voids.

[0046] As this chain reaction of ignition progresses, the raw material particles themselves are destroyed and scattered, promoting flame propagation. After combustion, the generated gas is naturally cooled, forming a cloud of metal contained in the raw material particles. The resulting spherical silica composition is collected using a bag filter, an electrostatic precipitator, or the like.

[0047] The VMC method utilizes the principle of dust explosion, and can instantly produce a large amount of spherical silica composition. The resulting spherical silica composition has a nearly perfect spherical shape. The particle size distribution of the resulting spherical silica composition can be adjusted by adjusting the particle size, amount, flame temperature, etc. of the raw particle material added. The raw particle material can be metal silicon alone, or silica (quartz) can be added. The raw particle material can also be surface-treated with a silane compound, a silazane compound, or the like. There are no particular restrictions on the type of silane compound that can be used, and those used in the surface treatment process described below can be used.

[0048] The raw material particles are dispersed in a carrier and then fed into the flame to be combusted. The speed at which the raw material particles are fed into the flame is not particularly limited. The carrier may be a gas such as nitrogen, argon, or air, or a liquid such as water or alcohol. There are no particular limitations on how the particles are dispersed, and when dispersed in a liquid, it is preferable to spray the particles into the flame in a mist form. For example, it is preferable that the raw material particles are contained in an amount of about 10% to 80% by volume of the total.

[0049] The flame used is a flame in an oxidizing atmosphere. For example, a flame obtained by burning a flammable gas such as LPG, ammonia, or hydrogen in an atmosphere containing excess oxygen can be used. Thermal plasma is also included in the flame. The raw material particles introduced into the flame are vaporized by combustion and rapidly cooled to form raw silica particles made of silica. The obtained raw silica particles are collected using a bag filter or the like.

[0050] Classification step: The classification step is a step of classifying the raw metal oxide particle material until the content of coarse particles is below the upper limit mentioned above and the content of hollow particles with a particle size of 5 μm or more is below the upper limit mentioned above. The coarse particles consist of solid particles and hollow particles. The classification operation can be performed by centrifugation in a gas or solvent, separation by specific gravity in a liquid, or a dry or wet sieving method. The classification operation is repeated until the desired particle size distribution is achieved in a single classification operation.

[0051] Centrifugation is a method suitable for removing solid particles from among coarse particles. It is desirable that the solvent used for centrifugation has a low viscosity. Examples include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and toluene. Solid coarse particles can be separated with high precision by performing centrifugation while the particles are dispersed in MEK at a concentration of approximately 10% by mass to 30% by mass (particularly 15% by mass to 25% by mass). Wet centrifugation can separate coarse particles by applying centrifugal force to the slurry to cause the coarse particles to settle and be removed.

[0052] To separate coarse particles consisting of hollow particles, it is preferable to separate hollow particles with a low specific gravity after dispersion in a liquid. Separation in a liquid is preferably performed by removing the hollow particles present in the supernatant after leaving the dispersion to stand or applying centrifugal force (hollow particle separation process). The liquid used can be the same as that used in centrifugation. Furthermore, since solid particles among the coarse particles settle quickly, while hollow particles settle slowly or not at all, removing the supernatant in conjunction with the above-described operation for removing the coarse particles can simultaneously remove coarse particles consisting of solid particles and coarse particles consisting of hollow particles. Furthermore, when using a filter, classification is performed in the form of a dispersion slurry dispersed in a solvent. It is desirable to perform the filter classification operation multiple times. If performed multiple times, it is preferable to perform the filter classification operation while switching from a filter with a large pore size to a filter with a small pore size.

[0053] Other Processes The surface treatment process can be carried out on the spherical silica composition produced in the production process, either before, after, or during the classification process. The surface treatment process is a process in which the spherical silica composition is surface-treated with a surface treatment agent such as a silane compound or a silazane compound. Functional groups derived from the surface treatment agent are introduced onto the surface of the spherical silica composition finally produced, or the surface treatment agent is attached to the surface.

[0054] The surface treatment is carried out by contacting the surface of the particles with a surface treatment agent directly (either in liquid or gaseous form) or by contacting the surface of the particles in a dissolved state in a solvent. The surface treatment is carried out by heating the particles after contacting the surface treatment agent with the particles. When a classification operation in liquid is employed in the classification step, the surface treatment step is also carried out in the liquid.

[0055] The amount of the surface treatment agent used for surface treatment is not particularly limited. For example, when a substance that reacts with the surface of particles, such as a silane compound or a silazane compound, is used as the surface treatment agent, an amount that reacts with 100%, 75%, 50%, 25%, etc., based on the amount of OH groups present on the surface of the particles to be treated is selected. Furthermore, an excess amount exceeding 100% (120%, 150%, etc.) can also be selected. In this case, unreacted surface treatment agent remains on the surface of the particles. The silane compound is not particularly limited, and examples thereof include compounds having a phenyl group, an alkyl group, a vinyl group, a methacryl group, an epoxy group, a phenylamino group, an amino group, a styryl group, etc.

[0056] (Resin Composition) The slurry composition of the embodiment is a composition prepared by dispersing the above-described spherical silica composition in a resin material (including a resin material precursor). The mixing ratio of the spherical silica composition and the resin material is not particularly limited. The resin material may be any appropriate material, such as an epoxy resin, an acrylic resin, or a silicone resin. It may also be a resin material precursor before curing.

[0057] (Slurry Composition) The slurry composition of the embodiment is a composition prepared by mixing the above-mentioned spherical silica composition with a liquid dispersion medium (solvent, resin material precursor, etc.). The mixing ratio of the spherical silica composition to the dispersion medium is not particularly limited. In addition to the above-mentioned resin material precursor, examples of the dispersion medium include MEK, MIBK, alcohols such as hexane and isopropanol.

[0058] The spherical silica composition of the embodiment, its production method, and analytical method were prepared and carried out as follows.

[0059] (Test Example 1) Raw material crystalline silica (manufactured by Admatechs Co., Ltd., silicon oxide: average particle size: 10 μm, the same applies hereinafter) was pulverized to an average particle size of 4 μm or less, and 3% by weight of silicone binder KR-500 (manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed in methyl ethyl ketone as an organic solvent. After drying, the particle size was adjusted using a ball mill to form 10 μm granules. The granules were placed in a melting furnace and spheroidized. Furthermore, silica synthesized by the VMC method with an average particle size of 0.3 to 2.0 μm was mixed in to achieve a closest-packed design. In addition, the surface was treated with an epoxy silane coupling agent.

[0060] Test Example 2: Raw material crystalline silica was pulverized to an average particle size of 8 μm and then charged into a melting furnace to be spheroidized. The obtained spherical silica was classified (sieved) using a 20 μm mesh. The subsequent treatment was the same as in Test Example 1.

[0061] Test Example 3 Raw material crystalline silica was pulverized to an average particle size of 4 μm and then charged into a melting furnace to be spheroidized. The obtained spherical silica was classified using a 10 μm mesh. The subsequent treatment was the same as in Test Example 1.

[0062] Test Example 4: Raw material crystalline silica was pulverized to an average particle size of 4 μm and then charged into a melting furnace to form spherical particles. The resulting spherical silica was air-classified (using a cyclone) to a particle size of 20 μm. The subsequent treatments were the same as in Test Example 1.

[0063] Test Example 5 Raw material crystalline silica was pulverized to an average particle size of 4 μm and then charged into a melting furnace to be spheroidized. The obtained spherical silica was classified using a 20 μm mesh. The subsequent treatment was the same as in Test Example 1.

[0064] Test Example 6 Raw material crystalline silica was pulverized to an average particle size of 3 μm and then charged into a melting furnace to be spheroidized. The obtained spherical silica was air-classified to a particle size of 10 μm. The subsequent treatment was the same as in Test Example 1.

[0065] Test Example 7: Spherical silica particles of 2 μm obtained by the VMC method were classified to 5 μm by air classification. Then, silica particles of 0.2 μm average particle size synthesized by the VMC method were blended to achieve a closest-packed design. Additionally, the particles were surface-treated with an aminophenylsilane coupling agent.

[0066] (Test Example 8) 2 μm spherical silica obtained by the VMC method was classified into 5 μm particles by wet classification in an aqueous solvent and dried. Then, silica synthesized by the VMC method with an average particle size of 0.2 μm was blended to achieve a closest-packed design. Additionally, the surface was treated with an aminophenylsilane coupling agent.

[0067] (Test Example 9) 2 μm spherical silica obtained by the VMC method was classified into 5 μm particles by wet classification in an aqueous solvent and dried. Then, wet-synthesized nanosilica with an average particle size of 50 nm was blended to achieve a close-packed design. Additionally, the surface was treated with an aminophenylsilane coupling agent.

[0068] Test Example 10: Raw material crystalline silica was pulverized to an average particle size of 10 μm and then charged into a melting furnace to be spheroidized. The resulting spherical silica was classified using a 24 μm mesh. The subsequent treatments were the same as in Test Example 1.

[0069] (Test Example 11) 2 μm spherical silica obtained by the VMC method was classified into 5 μm particles by wet classification in an aqueous solvent and dried. Then, VMC-synthesized silica with an average particle size of 0.3 μm was blended to achieve a closest-packed design. Additionally, the surface was treated with an aminophenylsilane coupling agent.

[0070] Test Example 12: Spherical silica particles of 1.5 μm obtained by the VMC method were classified to 5 μm by air classification. Then, synthetic silica particles of 0.3 μm average particle size obtained by the VMC method were blended to achieve a closest-packed design. Additionally, the particles were surface-treated with an aminophenylsilane coupling agent.

[0071] (Test Example 13) Spherical silica particles of 1.5 μm obtained by the VMC method were classified to 3 μm by wet classification in an aqueous solvent and dried. Then, synthetic silica particles of 0.2 μm average particle size by the VMC method were blended to achieve a closest-packed design. Furthermore, the surface was treated with an aminophenylsilane coupling agent.

[0072] (Particle size distribution measurement) For each test example, the particle diameter after pulverization, after melting, and after mixing was measured in an aqueous solvent using a laser diffraction particle size distribution measuring device SALD-7500 nano manufactured by Shimadzu Corporation. １０ , D ５０ (Median diameter), D ９０ The particle size distribution was calculated.

[0073] (Specific surface area measurement / BET method) 1.0 g of each test example was weighed and placed in a measurement cell. After pretreatment, the BET specific surface area value was measured by nitrogen adsorption. For the measurement, an automatic specific surface area and pore distribution measuring device TriStar (registered trademark)-II 3020 manufactured by Shimadzu Corporation was used. The pretreatment conditions were as follows: Degassing temperature: 200°C Degassing time: 30 minutes Cooling time: 4 minutes

[0074] (Component Analysis) The atomic composition of each test example was analyzed using an ICP (inductively coupled plasma optical emission spectroscopy) analyzer ICP-MS (measurement of U) and ICP-OES (measurement of silica and other impurities) manufactured by Shimadzu Corporation. For the measurement, each test example was completely dissolved in a mixed solution of nitric acid and hydrofluoric acid to form a solution, which was then subjected to the analyzer.

[0075] (Crystalline Silica Content) Using an X-ray diffractometer manufactured by Rigaku Corporation, the peak intensity (cps) of the sample of each test example at 2θ=26.6° was divided by the intensity of 100% crystalline silica to calculate the crystalline content.

[0076] (Content of hollow particles of 5 μm or more by cross-sectional observation) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) and the spherical silica composition (filler) prepared in the test example were mixed, and then curing agent Ethacure 100 (manufactured by Mitsui Fine Chemicals, Inc.) was added and mixed. At this time, the spherical silica composition (filler) was adjusted to 70 mass %. The mixture of resin and spherical silica composition was heated to 170°C to cure the resin. After curing, the cured resin was cut and the cross section was polished.

[0077] An ArBlade (registered trademark) 5000 (manufactured by Hitachi High-Tech Corporation) was used for ion milling, and the cross section was osmium coated with osmium tetroxide gas and observed by SEM. Observation range: 9 mm ２ The number of particles containing voids in the spherical silica composition having an inner diameter (major axis) of 5 μm or more was counted.

[0078] (Content of hollow particles of 5 μm or more by X-ray CT observation) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) and the spherical silica composition (filler) prepared in the test example were mixed, and then curing agent Ethacure 100 (manufactured by Mitsui Fine Chemicals, Inc.) was added and mixed. At this time, the spherical silica composition (filler) was adjusted to 70 mass %. The mixture of resin and spherical silica composition was heated to 170°C to cure the resin. After curing, the cured resin was cut and the cross section was polished.

[0079] The cured resin was scanned using a microfocus X-ray CT (Rigaku Corporation, nano-3DX). The setting conditions were 0.64 μm / voxel and the measurement range was 0.58 mm. ３ After scanning, the analysis software VG Studio MAX was used for image processing to calculate the void volume inside the spherical silica composition. ３ , 150 μm ３ The number of voids was counted.

[0080] (Filling property) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) was mixed with the spherical silica composition (filler) prepared in the test example. At this time, the spherical silica composition (filler) was adjusted to 75% by weight (mass %). The viscosity at 25°C was measured using a rheometer ARES-G2 (manufactured by TA Instruments) (at a shear rate of 1 s －１ ) Then, it was evaluated whether it was 1500 Pa·s or less. A viscosity of 1500 Pa·s or less was evaluated as "Good", and a viscosity of 1500 Pa·s or more was evaluated as "Poor".

[0081] (Results) The results are as shown in Tables 1, 2 and 3 below. From the top to bottom, the average particle size (μm), mode diameter (μm), specific surface area (m ２ / g), 75% by mass filling viscosity (Pa・s), filling property (〇 or ×), crystalline silica content (with or without), hollow volume of 5 μm or more (pcs / cm ２ ), hollow volume of 10 μm or more (pieces / cm ２ ), hollow volume with maximum diameter of 5 μm or more (pieces / mm ３ ), the amount of hollow holes with a maximum diameter of 10 μm or more (pieces / mm ３ ), void volume 35μm ３ or more particles (pieces / mm ３ ), void volume 150μm ３ or more particles (pieces / mm ３ ), U (uranium) content (ppb), and Na (sodium) content (ppb).

[0082]

[0083]

[0084]

[0085] (Discussion) The smaller the average particle diameter of a spherical silica composition (the finer the particle size), the lower the content of hollow particles with large internal void volumes. However, fine particles have poor filling properties in resin. Therefore, they are not suitable for filler applications. Furthermore, in applications such as semiconductor encapsulation materials (fillers for encapsulation materials for semiconductor packages), filling properties are important for controlling the thermal expansion coefficient. To achieve both of these, the spherical silica composition can have sufficient filling properties by setting the average particle diameter to 1.5 μm or more and the mode diameter to 1.9 μm or more.

[0086] In wafer level packaging (WLP), when an encapsulant is polished and a rewiring layer is formed on it, the polishing exposes the internal voids of the particles filled in the encapsulant, and the resin of the rewiring layer flows into the voids, reducing the flatness of the rewiring layer and making electrical conduction defects more likely to occur. Therefore, understanding the content of particles with large internal void volumes is particularly important for encapsulants for wafer level packaging (WLP). It has been difficult to accurately understand the internal voids of particles using conventional cross-sectional observation techniques. In contrast, as disclosed in the examples, cross-sectional tomographic analysis allows the voids inside the spherical silica composition to be measured, improving the accuracy of evaluation.

Claims

1. A spherical silica composition containing silica as a main component, wherein the spherical silica composition is filled into a resin material having a solid content concentration of 70% by mass, and the spherical silica composition has a particle size of 150 μm detected by cross-sectional analysis of the resin composition. ３ The particles of the spherical silica composition containing the above voids are 14 particles / mm ３ 35 μm or less detected by the tomographic cross-section analysis ３ The particles of the spherical silica composition containing voids of 60 particles / mm ３ A spherical silica composition, characterized in that:

2. The spherical silica composition according to claim 1, wherein the cross-sectional analysis is performed by X-ray CT or FIB-SEM.

3. The spherical silica composition according to claim 1, wherein the average particle size of the spherical silica composition as measured by laser diffraction particle size distribution is 1.5 to 15 μm.

4. The spherical silica composition according to claim 1, wherein the mode diameter of said spherical silica composition measured by laser diffraction particle size distribution measurement is 1.9 μm or more.

5. The spherical silica composition particles containing voids of 5 μm or more in diameter are 50 particles / mm ３ and the particles of the spherical silica composition containing voids of 10 μm or more in diameter are 5 particles / mm ３ The spherical silica composition according to claim 1, wherein:

6. The spherical silica composition according to claim 1, wherein the spherical silica composition contains 100 ppm or more of crystalline silica.

7. A spherical silica composition according to claim 1, wherein the content of uranium in said spherical silica composition is 5 ppb or less, and the content of sodium in said spherical silica composition is 100 ppb or less.

8. The spherical silica composition according to claim 1, wherein the spherical silica composition is surface-treated with a silane compound.

9. A resin composition comprising the spherical silica composition according to claim 1 and a resin material for dispersing said spherical silica composition.

10. A slurry composition comprising the spherical silica composition according to claim 1 and a dispersion medium for dispersing said spherical silica composition.

11. A filler for a sealing material for semiconductor packages, comprising the spherical silica composition according to claim 1.

12. A method for analyzing voids in a spherical silica composition, comprising: a dispersion step of dispersing a spherical silica composition in a resin composition; a cross-sectional analysis step of performing cross-sectional analysis of the spherical silica composition together with the resin composition using X-ray CT or FIB-SEM; and a void calculation step of preparing a three-dimensional image from the cross-sectional analysis and calculating the diameter and volume of voids present in the spherical silica composition.

13. The method for analyzing voids in a spherical silica composition according to claim 12, wherein a curing step of curing the resin composition is provided after the dispersing step.

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