Components of adhesives, film adhesives, and methods for manufacturing film adhesives, and semiconductor packaging using film adhesives and semiconductor packaging manufacturing methods.

Abstract

DEPCT65 The adhesive components consist of epoxy resin (A), an epoxy resin curing agent (B). Polymer component (C) and inorganic filler (D), where the inorganic filler (D) conforms to Condition (1) of (average diameter (d50) is 0.1 to 3.5 micrometers) and condition (2) of (The ratio of the particle diameter at a cumulative dispersion frequency of 90% (d90) to the diameter of the particle at a cumulative dispersion frequency of 10%. The center average (d50) is 5.0 or less) and the proportion of inorganic filler (D) in quantity. The package contains a mixture of epoxy resin (A), epoxy resin curing agent (B), polymer component (C), and Inorganic filler (D) is 20 to 70% by volume. Film-forming adhesives and methods for manufacturing film-forming adhesives. Semiconductor packaging and methods for manufacturing semiconductor packaging. -----------------------------------------------------------

Description

Adhesive composition, film-like adhesive and its manufacturing method, and semiconductor package using film-like adhesive and its manufacturing method

[0001] The present invention relates to an adhesive composition, a film-like adhesive and a method for producing the same, and a semiconductor package using the film-like adhesive and a method for producing the same.

[0002] In recent years, as electronic devices have become smaller and more sophisticated and multifunctional, the semiconductor packages mounted therein have also become more sophisticated and multifunctional, and semiconductor wafer wiring rules have become finer. Along with this trend toward higher functionality and multifunctionality, stacked MCPs (Multi-Chip Packages), in which semiconductor chips are stacked in multiple layers, have become widespread and are mounted in memory packages for mobile phones, mobile audio devices, and the like. Furthermore, as mobile phones and other devices become more multifunctional, the density and integration of packages have also increased. Accordingly, the trend toward multi-layer stacking of semiconductor chips has further progressed.

[0003] In the manufacturing process of such memory packages, a film-like adhesive (die attach film) is used to bond the wiring substrate and the semiconductor chip, and also to bond semiconductor chips together (so-called die attach), and this die attach film is required to have sufficient adhesiveness. As chips are increasingly stacked in multiple layers, thinner die attach films are also required. Furthermore, in recent years, wafer wiring rules have become increasingly finer, making it easier for heat to be generated on the surface of semiconductor elements. Therefore, these die attach films are increasingly required to have high thermal conductivity in order to facilitate heat dissipation to the outside of the package.

[0004] Thin thermally conductive die attach films are generally designed using thermally conductive fillers with small particle sizes. However, small particle sizes increase the specific surface area, which strengthens the interactions between fillers and tends to cause filler aggregation when mixed with resin. Furthermore, small particle sizes generally decrease the fluidity of the film adhesive, i.e., increase the melt viscosity. As a result, thin thermally conductive die attach films are prone to trap voids on the backside of the semiconductor chip or the wiring substrate that serves as the adherend. Furthermore, they are unable to fully fill the unevenness of the wiring substrate, resulting in a lack of the so-called anchoring effect and problems such as reduced adhesive strength and reduced heat dissipation.

[0005] As a material that can be used as a thermally conductive die attach film, for example, Patent Document 1 describes a material having an average particle size of 2 to 9 μm and a specific surface area of ​​0.8 to 8.0 m ２

[0003] Patent Document 2 describes an adhesive sheet containing spherical alumina filler having a molecular weight of 0.1 to 5 μm, a polymer, an epoxy resin or oxetane resin, and a curing agent, and having a surface arithmetic mean roughness Ra of 0.1 to 3 μm, wherein the filler content in the insulating sheet is a specific amount. It also describes that this insulating sheet increases the adhesive strength between the conductor layer and the cured insulating sheet.

[0006] Japanese Patent No. 6366228 Japanese Patent Application Laid-Open No. 2010-218975

[0007] Recently, there has been a demand for thinner thermally conductive die attach films. However, when the film thickness is reduced to less than 10 μm, voids are more likely to occur between the film and the backside of the semiconductor chip or the wiring substrate that serves as the adherend. With the sheets described in Patent Documents 1 and 2, when thinner films of less than 10 μm are produced, the presence of filler aggregates and coarse particles in the film due to the small particle size of the filler becomes significant. As a result, the adhesive sheet described in Patent Document 1 fails to sufficiently suppress the occurrence of voids, and the insulating sheet described in Patent Document 2 fails to achieve the arithmetic mean surface roughness Ra of 0.1 to 3 μm specified in Patent Document 2, resulting in insufficient adhesive strength. It has also been found that even if voids can be suppressed with thin films of less than 10 μm, the anchoring effect is not effectively exerted, and sufficient adhesive strength may not be obtained between the film and the adherend.

[0008] The present invention has been made in consideration of the problems of the prior art described above, and an object of the present invention is to provide an adhesive composition that can highly suppress the generation of voids after a die attach process, even in the form of a thin film, and that can provide a film adhesive that exhibits high adhesive strength with an adherend and excellent thermal conductivity. Another object of the present invention is to provide a film adhesive having the above-mentioned excellent properties, a method for producing the same, and a semiconductor package using this film adhesive, and a method for producing the same.

[0009] The present inventors have conducted extensive research to solve the above problems and have found that the problem can be solved by the following configuration. (1) An adhesive composition containing an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), and an inorganic filler (D), wherein the inorganic filler (D) satisfies the following conditions (1) and (2), and the proportion of the inorganic filler (D) in the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D) is 20 to 70 volume %. (1) The average particle size (d50) is 0.1 to 3.5 μm. (2) The ratio of the particle size (d90) at a cumulative distribution frequency of 90% to the average particle size (d50) is 5.0 or less. (2) The adhesive composition according to (1), characterized in that, when a film-like adhesive obtained from the adhesive composition is heated from 25°C at a heating rate of 5°C / min, the melt viscosity at 70°C reaches a range of 6,000 to 50,000 Pa s and the melt viscosity at 120°C reaches a range of 500 to 10,000 Pa s, and the film-like adhesive gives, after thermal curing, a cured product having a thermal conductivity of 1.0 W / m K or more. (3) The adhesive composition according to (1) or (2), characterized in that the polymer component (C) contains a phenoxy resin. (4) The adhesive composition according to any one of (1) to (3), characterized in that the inorganic filler (D) is particles made of a thermally conductive material or particles surface-coated with the thermally conductive material, and the thermal conductivity of the thermally conductive material is 12 W / m K or more. (5) A film-like adhesive obtained from the adhesive composition according to any one of (1) to (4), wherein the arithmetic mean roughness Ra of at least one surface of the film-like adhesive is 3.0 μm or less, and the thickness of the film-like adhesive is in the range of 1 μm or more and less than 10 μm. (6) A method for producing a film-like adhesive, characterized by applying the adhesive composition according to any one of (1) to (4) onto a release-treated substrate film and drying the adhesive composition.(7) A method for manufacturing a semiconductor package, comprising: a first step of thermocompression bonding the film-like adhesive described in (5) to the backside of a semiconductor wafer having at least one semiconductor circuit formed on its front side to provide an adhesive layer, and providing a dicing tape 3 via this adhesive layer, a second step of simultaneously dicing the semiconductor wafer and the adhesive layer to obtain a semiconductor chip with an adhesive layer, the semiconductor wafer and the adhesive layer, on the dicing tape, a third step of removing the dicing tape from the adhesive layer and thermocompression bonding the semiconductor chip with the adhesive layer to a wiring substrate via the adhesive layer, and a fourth step of thermally curing the adhesive layer. (8) A semiconductor package, characterized in that a semiconductor chip and a wiring substrate, or semiconductor chips, are bonded together with a thermoset product of the film-like adhesive described in (5).

[0010] In the present invention, a numerical range expressed using "to" means a range including the numerical values ​​written before and after "to" as the lower and upper limits. In the present invention, (meth)acrylic means one or both of acrylic and methacrylic. The same applies to (meth)acrylate.

[0011] The adhesive composition of the present invention is a suitable composition for obtaining a film-like adhesive that suppresses the generation of voids after a die-attach process, even in the form of a thin film, and exhibits high adhesive strength with an adherend, thereby exhibiting excellent thermal conductivity. The film-like adhesive of the present invention also has the above-mentioned excellent properties. Furthermore, the semiconductor package of the present invention has a film-like adhesive having the above-mentioned excellent properties. The manufacturing method of the present invention can produce a film-like adhesive and a semiconductor package having the above-mentioned excellent properties.

[0012] FIG. 1 is a schematic vertical cross-sectional view showing a preferred embodiment of the first step of the method for manufacturing a semiconductor package of the present invention. FIG. 2 is a schematic vertical cross-sectional view showing a preferred embodiment of the second step of the method for manufacturing a semiconductor package of the present invention. FIG. 3 is a schematic vertical cross-sectional view showing a preferred embodiment of the third step of the method for manufacturing a semiconductor package of the present invention. FIG. 4 is a schematic vertical cross-sectional view showing a preferred embodiment of the step of connecting bonding wires in the method for manufacturing a semiconductor package of the present invention. FIG. 5 is a schematic vertical cross-sectional view showing an example of a multi-layer stacking embodiment of the method for manufacturing a semiconductor package of the present invention. FIG. 6 is a schematic vertical cross-sectional view showing another example of a multi-layer stacking embodiment of the method for manufacturing a semiconductor package of the present invention. FIG. 7 is a schematic vertical cross-sectional view showing a preferred embodiment of a semiconductor package manufactured by the method for manufacturing a semiconductor package of the present invention.

[0013] <<Adhesive Composition>> The adhesive composition of the present invention (hereinafter also referred to as a thermally conductive adhesive composition) contains an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), and an inorganic filler (D), and the inorganic filler (D) satisfies the following conditions (1) and (2): The proportion of the inorganic filler (D) in the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D) is 20 to 70 volume %. (1) The average particle size (d50) is 0.1 to 3.5 μm. (2) The ratio d90 / d50, which is the ratio of the particle size (d90) at a cumulative distribution frequency of 90% to the average particle size (d50), is 5.0 or less.

[0014] In the present invention, the average particle size (d50) is the so-called median diameter, and refers to the particle size at which the particle size distribution is measured by a laser diffraction / scattering method, and the cumulative distribution is 50% when the total volume of the particles is taken as 100%. Similarly to the average particle size (d50), the particle size at a cumulative distribution frequency of 90% (d90) refers to the particle size at which the cumulative distribution is 90% when the total volume of the particles is taken as 100%. Specifically, it is a value measured by the method described in the Examples. When measuring the average particle size of the inorganic filler (D) contained in the thermally conductive adhesive composition, the inorganic filler (D) is separated from other components in the composition by, for example, a method of heat-treating the adhesive composition at 300°C or higher to carbonize the organic components and then washing and removing them, and then the measurement is performed by the method described in the Examples. The average particle size of the inorganic filler (D) contained in an adhesive (e.g., the film-like adhesive described below) obtained from the thermally conductive adhesive composition of the present invention can also be measured in the same manner as the average particle size of the inorganic filler (D) contained in the thermally conductive adhesive composition. Here, the thermally conductive adhesive composition of the present invention can suppress aggregation of the inorganic filler (D) by dispersing the inorganic filler (D) in the composition during preparation of the composition. Therefore, even if the composition is stored for a certain period of time after preparation, it can be redispersed. The thermally conductive adhesive composition of the present invention can be stored stably for one month or more under conditions of 25°C. However, considering the reactivity of the epoxy resin (A) and the epoxy resin curing agent (B), it is preferable to store it in a refrigerator at 10°C or below. The film-like adhesive of the present invention described below can also be stored under similar conditions.

[0015] The thermally conductive adhesive composition of the present invention contains an inorganic filler (D) having a small average particle size (d50) of 0.1 to 3.5 μm as defined in (1) above, and a particle size distribution with a d90 / d50 of 5.0 or less as defined in (2) above. This allows for the suppression of inorganic filler aggregation and the inclusion of coarse particles when mixed with a resin component containing an epoxy resin (A) and a polymer component (C), even when the inorganic filler has a small average particle size. Furthermore, even when the composition is made into a film-like adhesive, the suppression of inorganic filler aggregation and the inclusion of coarse particles is similarly achieved. While the reason for this is unclear, it is presumed that the aggregates inherent in the inorganic filler (D), which act as nuclei for aggregation growth when mixed with the resin component, in addition to the coarse particles, are removed during the particle size distribution adjustment process. As a result, adhesives such as film-like adhesives obtained from the thermally conductive adhesive composition of the present invention can suppress an increase in melt viscosity and suppress the occurrence of voids after the die-attach process. Furthermore, when molded into a film, the adhesive surface becomes smooth, eliminating even small gaps between the adhesive layer (film-like adhesive) and the adherend that would not be detected as voids, and it is believed that this results in excellent adhesive strength between the adhesive and the adherend. The d50 value is preferably 0.2 to 3.3. The d90 / d50 value is preferably 4.5 or less, more preferably 4.2 or less, and even more preferably 4.0 or less. Hereinafter, in this specification, the epoxy resin (A) may be referred to as component (A), the epoxy resin curing agent (B) as component (B), the polymer component (C) as component (C), and the inorganic filler (D) as component (D).

[0016] <Characteristics of Film-Like Adhesive> (Melt Viscosity) When a film-like adhesive obtained using the thermally conductive adhesive composition of the present invention (hereinafter also referred to as a thermally conductive film-like adhesive) is heated from 25°C at a heating rate of 5°C / min, it is preferable that the melt viscosity at 70°C reach a range of 6,000 to 50,000 Pa·s. This melt viscosity at 70°C is more preferably in the range of 6,000 to 45,000 Pa·s, and even more preferably in the range of 6,000 to 40,000 Pa·s. By having the melt viscosity at 70°C within the above preferred range, it is possible to reduce the occurrence of voids between the semiconductor wafer and the film-like adhesive and the occurrence of poor extrusion of the film-like adhesive when bonding the film-like adhesive to a semiconductor wafer. Furthermore, when the thermally conductive film-like adhesive of the present invention is heated from 25°C at a heating rate of 5°C / min, it is preferable that the melt viscosity at 120°C reach a range of 500 to 10,000 Pa·s. The melt viscosity at 120°C is more preferably in the range of 800 to 9000 Pa·s, and even more preferably in the range of 1000 to 8000 Pa·s. Having a melt viscosity at 120°C within the above-mentioned preferred range can reduce the occurrence of voids between the uneven portions of the wiring substrate and the occurrence of poor extrusion of the film adhesive when a semiconductor chip provided with the film adhesive is thermocompression bonded to the wiring substrate. In the present invention, the above melt viscosity is measured using a rheometer (product name: RS6000, manufactured by Haake Corporation) for the thermally conductive film adhesive before heat curing, measuring the change in viscous resistance at a temperature rise rate of 5°C / min from 25°C in the temperature range of 25 to 200°C, and calculating the melt viscosity at 70°C and 120°C from the obtained temperature-viscous resistance curve. Specifically, the measurement method described in the Examples can be referenced. Here, the thermally conductive film adhesive before heat curing in the melt viscosity measurement refers to a thermally conductive film adhesive that has not been exposed to temperatures of 25°C or higher for one month or more. The melt viscosity can be adjusted to fall within the above range by adjusting the content of the inorganic filler (D) and further the type of the inorganic filler (D), as well as the types and contents of coexisting compounds or resins such as the epoxy resin (A), the epoxy resin curing agent (B) and the polymer component (C).

[0017] (Thermal Conductivity) The thermally conductive film-like adhesive of the present invention preferably has a thermal conductivity of 1.0 W / m·K or more after thermal curing. The thermal conductivity is more preferably 1.5 W / m·K or more. If the thermal conductivity is below the above-mentioned preferred lower limit, it tends to be difficult for generated heat to escape to the outside of the package. The thermally conductive film-like adhesive of the present invention exhibits such excellent thermal conductivity after thermal curing. By adhering the thermally conductive film-like adhesive of the present invention to an adherend such as a semiconductor wafer or wiring board and thermally curing it, a semiconductor package with improved heat dissipation efficiency to the outside of the semiconductor package can be obtained. The upper limit of the thermal conductivity is not particularly limited, but in reality it is 7.0 W / m·K or less, more preferably 6.5 W / m·K or less, and also preferably 5.0 W / m·K or less. Here, "after thermal curing" in measuring thermal conductivity means a state in which the thermosetting resin has completely cured. Specifically, this refers to a state in which no reaction heat peak is observed when DSC (differential scanning calorimetry) measurement is performed at a temperature rise rate of 10°C / min. In the present invention, the thermal conductivity of the film-like adhesive after heat curing refers to the value measured by the heat flow meter method (in accordance with JIS-A1412) using a thermal conductivity measuring device (product name: HC-110, manufactured by Eiko Seiki Co., Ltd.). Specifically, the measurement method described in the examples can be referenced. To achieve the above range of thermal conductivity, the content of the inorganic filler (D) and the type of inorganic filler (D) can be adjusted by adjusting the type and content of coexisting compounds or resins such as the epoxy resin (A), epoxy resin curing agent (B), and polymer component (C). The thermally conductive film-like adhesive of the present invention also possesses insulating properties.

[0018] <Epoxy Resin (A)> The epoxy resin (A) can be used without particular limitation as long as it is a thermosetting resin having epoxy groups, and may be liquid, solid, or semi-solid. In the present invention, "liquid" refers to a resin having a softening point below 25°C, "solid" refers to a resin having a softening point of 60°C or higher, and "semi-solid" refers to a resin having a softening point between the softening points of the liquid and solid (25°C or higher and lower than 60°C). The epoxy resin (A) used in the present invention preferably has a softening point of 100°C or lower, from the viewpoint of obtaining a film-like adhesive that can achieve a low melt viscosity in a suitable temperature range (e.g., 60 to 120°C). In the present invention, the softening point is a value measured by a softening point test (ring and ball method) (measurement conditions: in accordance with JIS-2817).

[0019] In the epoxy resin (A) used in the present invention, the crosslink density of the cured product is increased, resulting in a higher contact probability and a wider contact area between the blended inorganic fillers (D), thereby achieving higher thermal conductivity. From this perspective, the epoxy equivalent is preferably 500 g / eq or less, and more preferably 150 to 450 g / eq. In the present invention, the epoxy equivalent refers to the number of grams (g / eq) of resin containing 1 gram equivalent of epoxy groups. The mass average molecular weight of the epoxy resin (A) is usually preferably less than 10,000, more preferably 5,000 or less. There is no particular lower limit, but a value of 300 or more is practical. The mass average molecular weight is a value determined by GPC (Gel Permeation Chromatography) analysis.

[0020] Examples of the skeleton of the epoxy resin (A) include phenol novolac type, orthocresol novolac type, cresol novolac type, dicyclopentadiene type, biphenyl type, fluorene bisphenol type, triazine type, naphthol type, naphthalenediol type, triphenylmethane type, tetraphenyl type, bisphenol A type, bisphenol F type, bisphenol AD ​​type, bisphenol S type, trimethylolmethane type, etc. Of these, the triphenylmethane type, bisphenol A type, cresol novolac type, and orthocresol novolac type are preferred from the viewpoint of obtaining a film-like adhesive having low resin crystallinity and good appearance.

[0021] The content of the epoxy resin (A) in the thermally conductive adhesive composition of the present invention is preferably 3 to 30 parts by mass, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the total content of the components constituting the film-like adhesive (specifically, components other than the solvent). By ensuring that the content is equal to or greater than the above-mentioned preferred lower limit, the thermal conductivity of the film-like adhesive can be improved. On the other hand, by ensuring that the content is equal to or less than the above-mentioned preferred upper limit, the generation of oligomer components can be suppressed, making it less likely that changes in the film state (film tackiness, etc.) will occur due to slight temperature changes.

[0022] <Epoxy Resin Curing Agent (B)> The epoxy resin curing agent (B) can be any curing agent, such as amines, acid anhydrides, or polyhydric phenols. In the present invention, a latent curing agent is preferably used, from the viewpoint of providing a thermally conductive adhesive composition that has a low melt viscosity, exhibits curing properties at high temperatures exceeding a certain temperature, exhibits rapid curing properties, and has high storage stability, allowing for long-term storage at room temperature. Examples of latent curing agents include dicyandiamides, imidazoles, curing catalyst composite polyhydric phenols, hydrazides, boron trifluoride-amine complexes, amine imides, polyamine salts, and modified or microencapsulated versions of these. In the present invention, imidazoles are more preferably used, from the viewpoint of adjusting the melt viscosities at 70°C and 120°C of the thermally conductive film-like adhesive to satisfy the above-mentioned preferred ranges. These agents may be used alone or in combination of two or more.

[0023] The content of the epoxy resin curing agent (B) per 100 parts by mass of the epoxy resin (A) is preferably 0.5 to 100 parts by mass, and more preferably 1 to 80 parts by mass. By setting the content to be equal to or greater than the above-mentioned preferable lower limit, the curing time can be shortened, while by setting the content to be equal to or less than the above-mentioned preferable upper limit, the excess curing agent remaining in the film-like adhesive and the residual curing agent absorbing moisture can be reduced, thereby reducing defects in reliability tests after the film-like adhesive is incorporated into a semiconductor.

[0024] <Polymer Component (C)> The polymer component (C) may be any component that, when a film-like adhesive is formed, suppresses film tackiness (the tendency for the film state to change even with slight temperature changes) at room temperature (25°C) and provides sufficient adhesion and film-forming properties (film-forming properties). Examples include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resins such as 6-nylon and 6,6-nylon, phenoxy resin, (meth)acrylic resin, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamideimide resin, and fluororesin. These polymer components (C) may be used alone or in combination of two or more. The weight average molecular weight of the polymer component (C) is 10,000 or more. There is no particular upper limit, but a practical upper limit is 5,000,000 or less. The mass average molecular weight of the polymer component (C) is a value determined by GPC (gel permeation chromatography) in terms of polystyrene. Hereinafter, the mass average molecular weight of a specific polymer component (C) has the same meaning. The glass transition temperature (Tg) of the polymer component (C) is preferably less than 100°C, more preferably less than 90°C. The lower limit is preferably 0°C or higher, more preferably 10°C or higher. The glass transition temperature of the polymer component (C) is a glass transition temperature measured by DSC at a heating rate of 0.1°C / min. Hereinafter, the glass transition temperature of a specific polymer component (C) has the same meaning. In the present invention, among the epoxy resins (A) and polymer components (C), resins that may have epoxy groups, such as phenoxy resins, are classified as epoxy resins (A) if they have an epoxy equivalent of 500 g / eq or less, and as component (C) if they do not fall into this category.

[0025] In the present invention, it is preferable to use at least one phenoxy resin among these polymer components (C). Phenoxy resins have a similar structure to the epoxy resin (A), and therefore have good compatibility, low resin melt viscosity, and excellent adhesive properties. Furthermore, phenoxy resins have high heat resistance and low saturated water absorption, making them preferable from the viewpoint of ensuring the reliability of semiconductor packages. Furthermore, they are also preferable from the viewpoint of eliminating tackiness, brittleness, etc. at room temperature.

[0026] Phenoxy resins can be obtained by the reaction of a bisphenol or biphenol compound with an epihalohydrin such as epichlorohydrin, or by the reaction of a liquid epoxy resin with a bisphenol or biphenol compound. In either reaction, the bisphenol or biphenol compound is preferably a compound represented by the following general formula (A):

[0027]

[0028] In general formula (A), L ａ represents a single bond or a divalent linking group, R ａ１ and R ａ２ each independently represents a substituent; ma and na each independently represents an integer of 0 to 4.

[0029] L ａ In the formula, the divalent linking group is an alkylene group, a phenylene group, —O—, —S—, —SO—, —SO ２ - or a group in which an alkylene group and a phenylene group are combined is preferred. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1. The alkylene group is -C(R α ) (R β )- is preferred, where R α and R β R each independently represents a hydrogen atom, an alkyl group, or an aryl group. α and R β may be bonded to each other to form a ring. α and R βis preferably a hydrogen atom or an alkyl group (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, hexyl, octyl, 2-ethylhexyl). ２ -, -CH(CH ３ ) -, -C(CH ３ ) ２ - is preferred, and -CH ２ -, -CH(CH ３ )- is more preferred, and -CH ２ - is even more preferred.

[0030] The phenylene group preferably has 6 to 12 carbon atoms, more preferably 6 to 8 carbon atoms, and even more preferably 6 carbon atoms. Examples of the phenylene group include p-phenylene, m-phenylene, and o-phenylene, and p-phenylene and m-phenylene are preferred. As a group in which an alkylene group and a phenylene group are combined, an alkylene-phenylene-alkylene group is preferred, and -C(R α ) (R β )-phenylene-C(R α ) (R β )- is more preferred. α and R β The ring formed by bonding is preferably a 5- or 6-membered ring, more preferably a cyclopentane ring or a cyclohexane ring, and even more preferably a cyclohexane ring.

[0031] L ａ represents a single bond or an alkylene group, —O—, —SO ２ - is preferred, and an alkylene group is more preferred.

[0032] R ａ１ and R ａ２ In the above, the substituent is preferably an alkyl group, an aryl group, an alkoxy group, an alkylthio group, or a halogen atom, more preferably an alkyl group, an aryl group, or a halogen atom, and still more preferably an alkyl group.

[0033] ma and na are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0034] Examples of bisphenol or biphenol compounds include bisphenol A, bisphenol AD, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol Z, 4,4'-biphenol, 2,2'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethyl-4,4'-biphenol, and cardo skeleton bisphenols. Bisphenol A, bisphenol AD, bisphenol C, bisphenol E, bisphenol F, and 4,4'-biphenol are preferred, bisphenol A, bisphenol E, and bisphenol F are more preferred, and bisphenol A is particularly preferred.

[0035] On the other hand, as the liquid epoxy resin, a diglycidyl ether of an aliphatic diol compound is preferred, and a compound represented by the following general formula (B) is more preferred.

[0036]

[0037] In formula (B), X represents an alkylene group, and nb represents an integer of 1 to 10.

[0038] The alkylene group preferably has 2 to 10 carbon atoms, more preferably 2 to 8, still more preferably 3 to 8, particularly preferably 4 to 6, and most preferably 6. Examples thereof include ethylene, propylene, butylene, pentylene, hexylene, and octylene, with ethylene, trimethylene, tetramethylene, pentamethylene, heptamethylene, hexamethylene, and octamethylene being preferred.

[0039] nb is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1.

[0040] When nb is 2 to 10, X is preferably ethylene or propylene, more preferably ethylene.

[0041] Examples of the aliphatic diol compound in the diglycidyl ether include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,7-pentanediol, and 1,8-octanediol.

[0042] In the above reaction, the phenoxy resin may be obtained by reacting each of the bisphenol or biphenol compound and the aliphatic diol compound alone, or may be obtained by reacting two or more of them together, for example, by reacting a diglycidyl ether of 1,6-hexanediol with a mixture of bisphenol A and bisphenol F.

[0043] In the present invention, the phenoxy resin is preferably a phenoxy resin obtained by reacting a liquid epoxy resin with a bisphenol or biphenol compound, and more preferably a phenoxy resin having a repeating unit represented by the following general formula (I).

[0044]

[0045] In general formula (I), L ａ , R ａ１ , R ａ２ , ma and na are L in general formula (A). ａ , R ａ１ , R ａ２ X and nb have the same meanings as X and nb in formula (B), and the preferred ranges are also the same.

[0046] Among these, a polymer of bisphenol A and diglycidyl ether of 1,6-hexanediol is preferred in the present invention.

[0047] The mass average molecular weight of the phenoxy resin is preferably 10,000 or more, more preferably 10,000 to 100,000. The amount of epoxy groups remaining in the phenoxy resin in small amounts is preferably 5,000 g / eq or more in terms of epoxy equivalent.

[0048] The glass transition temperature (Tg) of the phenoxy resin is preferably less than 100° C., more preferably less than 90° C. The lower limit is preferably 0° C. or higher, more preferably 10° C. or higher.

[0049] The phenoxy resin may be synthesized by the method described above, or a commercially available product may be used. Examples of commercially available products include YX7180 (trade name: bisphenol F + 1,6-hexanediol diglycidyl ether type phenoxy resin, manufactured by Mitsubishi Chemical Corporation), 1256 (trade name: bisphenol A type phenoxy resin, manufactured by Mitsubishi Chemical Corporation), YP-50 (trade name: bisphenol A type phenoxy resin, manufactured by Shin-Nipponka Epoxy Manufacturing Co., Ltd.), YP-70 (trade name: bisphenol A / F type phenoxy resin, manufactured by Shin-Nipponka Epoxy Manufacturing Co., Ltd.), FX-316 (trade name: bisphenol F type phenoxy resin, manufactured by Shin-Nipponka Epoxy Manufacturing Co., Ltd.), FX-280S (trade name: cardo skeleton type phenoxy resin, manufactured by Shin-Nipponka Epoxy Manufacturing Co., Ltd.), and 4250 (trade name: bisphenol A type / F type phenoxy resin, manufactured by Mitsubishi Chemical Corporation).

[0050] As the (meth)acrylic resin, a resin made of a conventionally known (meth)acrylic copolymer is used. The mass average molecular weight of the (meth)acrylic copolymer is preferably 10,000 to 2,000,000, and more preferably 100,000 to 1,500,000. By setting the mass average molecular weight within the above preferred range, tackiness can be reduced and an increase in melt viscosity can be suppressed. The glass transition temperature of the (meth)acrylic copolymer is preferably in the range of -10°C to 50°C, more preferably 0°C to 40°C, and even more preferably 0°C to 30°C. By setting the glass transition temperature within the above preferred range, tackiness can be reduced and the occurrence of voids between the semiconductor wafer and the film-like adhesive can be suppressed.

[0051] Examples of the (meth)acrylic resin include poly(meth)acrylic esters and their derivatives. Examples include copolymers containing monomer components such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, glycidyl methacrylate, and glycidyl acrylate. Also useful as monomer components are (meth)acrylic esters having a cyclic skeleton, such as cycloalkyl (meth)acrylates, benzyl (meth)acrylates, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate, and imide (meth)acrylates, as well as alkyl (meth)esters having 1 to 18 carbon atoms in the alkyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. It may also be copolymerized with vinyl acetate, (meth)acrylonitrile, styrene, etc. Also, it is preferable that it has a hydroxyl group, since this improves compatibility with epoxy resins.

[0052] The content of the polymer component (C) per 100 parts by mass of the epoxy resin (A) is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass, and even more preferably 10 to 30 parts by mass. By setting the content within this range, it is possible to adjust the rigidity and flexibility of the thermally conductive film-like adhesive before curing. This improves the film condition (reduced film tackiness) and also reduces film brittleness.

[0053] <Inorganic Filler (D)> The inorganic filler (D) is not particularly limited as long as it is a thermally conductive inorganic filler that satisfies the above-mentioned (1) average particle size (d50) and (2) d90 / d50 requirements, but in the present invention, it contributes to imparting thermal conductivity to the film-like adhesive. An inorganic filler (D) that satisfies the above-mentioned (1) average particle size (d50) and (2) d90 / d50 requirements can be prepared, for example, by filtering any inorganic filler using a mesh filter of an appropriate diameter. The thermally conductive inorganic filler is preferably particles made of a thermally conductive material or particles surface-coated with the thermally conductive material, and the thermal conductivity of these thermally conductive materials is preferably 12 W / m K or more, more preferably 30 W / m K or more. When the thermal conductivity of the thermally conductive material is equal to or greater than the above-mentioned preferred lower limit, the amount of inorganic filler (D) to be blended can be reduced to achieve the desired thermal conductivity, thereby suppressing an increase in the melt viscosity of the adhesive film, improving the embedding ability into uneven portions of the substrate when pressure-bonded to the substrate, and suppressing the occurrence of voids. In the present invention, the thermal conductivity of the thermally conductive material means the thermal conductivity at 25°C, and literature values ​​for each material can be used. Even if there is no description in the literature, for example, values ​​measured according to JIS R 1611 for ceramics and values ​​measured according to JIS H 7801 for metals can be used instead.

[0054] Examples of the inorganic filler (D) include thermally conductive ceramics, such as alumina particles (thermal conductivity: 36 W / m K), aluminum nitride particles (thermal conductivity: 150 to 290 W / m K), boron nitride particles (thermal conductivity: 60 W / m K), zinc oxide particles (thermal conductivity: 54 W / m K), silicon nitride filler (thermal conductivity: 27 W / m K), silicon carbide particles (thermal conductivity: 200 W / m K), and magnesium oxide particles (thermal conductivity: 59 W / m K). Alumina particles are particularly preferred in terms of their high thermal conductivity, dispersibility, and availability. Aluminum nitride particles and boron nitride particles are also preferred because they have even higher thermal conductivities than alumina particles. In the present invention, alumina particles and aluminum nitride particles are particularly preferred. Particles coated with a thermally conductive metal are also preferred. Preferred examples include silicone resin particles and acrylic resin particles whose surfaces are coated with metals such as silver (thermal conductivity: 429 W / m K), nickel (thermal conductivity: 91 W / m K), and gold (thermal conductivity: 329 W / m K). In particular, silicone resin particles whose surfaces are coated with silver are preferred from the viewpoints of stress relaxation properties and high heat resistance.

[0055] The inorganic filler (D) may be surface-treated or surface-modified. Examples of such surface treatments or surface modifications include silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants. In addition to the matters described in this specification, for example, the descriptions of silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants in the section on thermally conductive fillers in WO 2018 / 203527 or the section on aluminum nitride fillers in WO 2017 / 158994 can be applied.

[0056] The method of blending inorganic filler (D) with resin components such as epoxy resin (A), epoxy resin curing agent (B) and polymer component (C) can be a method of directly blending powder inorganic filler with, if necessary, a silane coupling agent, phosphoric acid or a phosphoric acid compound or a surfactant (integral blend method), or a method of blending a slurry inorganic filler in which an inorganic filler treated with a surface treatment agent such as a silane coupling agent, phosphoric acid or a phosphoric acid compound or a surfactant is dispersed in an organic solvent.In addition, the method of treating inorganic filler (D) with a silane coupling agent is not particularly limited, and can include a wet method of mixing inorganic filler (D) and a silane coupling agent in a solvent, a dry method of treating inorganic filler (D) and a silane coupling agent in a gas phase, the above-mentioned integral blend method, etc.

[0057] In particular, aluminum nitride particles contribute to high thermal conductivity, but are prone to generating ammonium ions through hydrolysis, so it is preferable to use them in combination with a phenolic resin with low moisture absorption, or to suppress hydrolysis through surface modification.A particularly preferable method for modifying the surface of aluminum nitride is to provide an aluminum oxide layer on the surface to improve water resistance, and then perform surface treatment with phosphoric acid or a phosphoric acid compound to improve affinity with resin.

[0058] It is also preferable to treat the surface of the inorganic filler (D) with a silane coupling agent, and it is also preferable to use an ion trapping agent in combination.

[0059] The silane coupling agent is a silicon atom to which at least one hydrolyzable group such as an alkoxy group or an aryloxy group is bonded, and in addition, an alkyl group, an alkenyl group, or an aryl group may be bonded. The alkyl group is preferably substituted with an amino group, an alkoxy group, an epoxy group, or a (meth)acryloyloxy group, and more preferably substituted with an amino group (preferably a phenylamino group), an alkoxy group (preferably a glycidyloxy group), or a (meth)acryloyloxy group. Examples of the silane coupling agent include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

[0060] The silane coupling agent or surfactant is preferably contained in an amount of 0.1 to 2.0 parts by mass per 100 parts by mass of the inorganic filler (D). By setting the content of the silane coupling agent or surfactant within the above preferred range, it is possible to suppress separation at the adhesive interface due to volatilization of excess silane coupling agent or surfactant during the semiconductor assembly heating process (e.g., the reflow process), while suppressing aggregation of the inorganic filler (D), thereby suppressing the generation of voids and improving adhesion.

[0061] The shape of the inorganic filler (D) is not limited as long as it satisfies the average particle size (d50) specified in (1) above and the particle size distribution specified in (2). Examples of the shape include flakes, needles, filaments, spheres, and scales. From the viewpoints of high packing density and flowability, spherical particles are preferred.

[0062] In the present invention, the inorganic filler (D) accounts for 20 to 70 volume % of the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D). When the content of the inorganic filler (D) is at or above the lower limit, the desired thermal conductivity and melt viscosity can be imparted to the film adhesive, thereby achieving heat dissipation from the semiconductor package and suppressing extrusion defects of the film adhesive. When the content is at or below the upper limit, the desired melt viscosity can be imparted to the film adhesive, suppressing the occurrence of voids. Furthermore, it is possible to alleviate internal stresses that occur in the semiconductor package during thermal changes and improve adhesive strength. The inorganic filler (D) accounts for preferably 25 to 70 volume %, more preferably 30 to 70 volume %, even more preferably 30 to 60 volume %, and even more preferably 30 to 50 volume % of the total content of the components (A) to (D). The content (vol %) of the inorganic filler (D) can be calculated from the mass content and specific gravity of each of the components (A) to (D).

[0063] <Other Additives> In addition to the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D), the adhesive composition of the present invention may further contain additives such as an organic solvent (MEK, etc.), an ion trapping agent (ion scavenger), a curing catalyst, a viscosity modifier, an antioxidant, a flame retardant, a colorant, and a stress relaxation agent such as butadiene rubber or silicone rubber, provided that the effects of the present invention are not impaired. For example, the description of other additives in WO 2017 / 158994 can be applied.

[0064] The total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D) in the adhesive composition of the present invention is not particularly limited as long as the film-like adhesive of the present invention can be obtained, but it can be, for example, 60 to 95 mass %, and preferably 70 to 90 mass %. The adhesive composition of the present invention can be suitably used to obtain the film-like adhesive of the present invention. However, it is not limited to film-like adhesives, and can also be suitably used for liquid adhesives.

[0065] <<Film-like adhesive and its manufacturing method>> The film-like adhesive of the present invention is a film-like adhesive obtained from the adhesive composition of the present invention, and contains the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D). In addition, among the additives described as other additives in the thermally conductive adhesive composition of the present invention, additives other than organic solvents may also be contained. Here, the term "film" refers to a thin film having a thickness of 200 μm or less. The shape, size, etc. are not particularly limited and can be appropriately adjusted according to the usage mode. The film-like adhesive of the present invention may be composed solely of the film-like adhesive of the present invention, or may be in a form in which a release-treated substrate film described below is laminated to at least one surface. Furthermore, the film-like adhesive of the present invention may be in a form in which the film is cut to an appropriate size, or in a form in which the film is wound into a roll. A preferred embodiment of the method for manufacturing the film-like adhesive of the present invention includes a method in which the thermally conductive adhesive composition of the present invention is coated on one surface of a release-treated substrate film and then heated and dried, but the method is not particularly limited to this method. The heat drying is carried out for the purpose of removing the solvent to form a film-like adhesive. The release-treated substrate film may be any film that functions as a cover film for the resulting film-like adhesive, and known films may be appropriately used. Examples include release-treated polypropylene (PP), release-treated polyethylene (PE), and release-treated polyethylene terephthalate (PET). Known coating methods may be appropriately used, and examples include methods using a roll knife coater, gravure coater, die coater, reverse coater, etc.

[0066] The thickness of the film-like adhesive of the present invention obtained in this manner is not particularly limited, but is preferably 1 to 200 μm, and more preferably 1 to 40 μm from the viewpoint of being able to more fully embed the unevenness of the wiring board and semiconductor chip surface. If the thickness is less than the above-mentioned preferable lower limit, the unevenness of the wiring board and semiconductor chip surface tends to be insufficient to ensure sufficient adhesion. On the other hand, if the thickness exceeds the above-mentioned preferable upper limit, it becomes difficult to remove the organic solvent during production, resulting in a large amount of residual solvent and a tendency for the film to become more tacky. In order to better demonstrate the effects of the present invention, such as excellent thermal conductivity, void suppression, and excellent adhesive strength as a thin thermally conductive film-like adhesive, the thickness of the film-like adhesive is more preferably 1 μm or more and less than 10 μm. The thickness of the film-like adhesive is a value measured using a contact / linear gauge method (desktop contact thickness measurement device).

[0067] The thermally conductive film-like adhesive of the present invention preferably has an arithmetic mean roughness Ra of 3.0 μm or less on at least one surface (i.e., at least one surface that will be bonded to the adherend), and more preferably, the arithmetic mean roughness Ra of both surfaces that will be bonded to the adherend is 3.0 μm or less. The arithmetic mean roughness Ra is more preferably 2.0 μm or less, and even more preferably 1.5 μm or less. There is no particular lower limit, but a practical value is 0.1 μm or more. The above-mentioned method for producing a film-like adhesive can produce a film-like adhesive whose surface arithmetic mean roughness Ra satisfies the above-mentioned preferred range. For example, when the thermally conductive adhesive composition of the present invention is applied to one surface of a release-treated substrate film and then heated and dried, the arithmetic mean roughness Ra of the surface of the resulting film-like adhesive that comes into contact with the release-treated substrate film is usually smaller than the arithmetic mean roughness Ra of the exposed film-like adhesive surface. It is believed that the film adhesive of the present invention can satisfy the arithmetic mean roughness Ra by using the inorganic filler (D), especially in the case of a thin film having a thickness of less than 10 μm. As a result, an adhesive state can be achieved in which the generation of voids between the wiring board and the uneven parts of the semiconductor chip surface is suppressed, and excellent adhesive properties can be exhibited. The arithmetic mean roughness Ra is measured by the method described in the Examples below.

[0068] <<Semiconductor Package and Manufacturing Method Thereof>> Next, preferred embodiments of a semiconductor package and a manufacturing method thereof of the present invention will be described in detail with reference to the drawings. Note that in the following description and drawings, identical or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted. Figures 1 to 7 are schematic vertical cross-sectional views showing each step of a preferred embodiment of a semiconductor package manufacturing method of the present invention.

[0069] In the semiconductor package manufacturing method of the present invention, as shown in FIG. 1 , in the first step, the film-like adhesive of the present invention is thermocompression bonded to the backside (i.e., the side of the semiconductor wafer 1 on which at least one semiconductor circuit is formed) of a semiconductor wafer 1 having at least one semiconductor circuit formed on its surface to form an adhesive layer 2. Next, the semiconductor wafer 1 and dicing tape 3 are provided with the adhesive layer 2 interposed therebetween. At this time, the integrated product of the adhesive layer 2 and dicing tape 3 may be thermocompression bonded at once. The conditions for thermocompression bonding are not particularly limited as long as the epoxy resin (A) is not thermally cured and the effects of the present invention are not impaired. Examples of suitable conditions include a temperature of 70°C and a pressure of 0.3 MPa. The semiconductor wafer 1 may be any semiconductor wafer having at least one semiconductor circuit formed on its surface, such as a silicon wafer, a SiC wafer, or a GaS wafer. The thermally conductive film-like adhesive of the present invention may be used as the adhesive layer 2, either singly or in a laminate of two or more layers. As a method for providing such an adhesive layer 2 on the back surface of the wafer 1, any method capable of laminating the film-like adhesive on the back surface of the semiconductor wafer 1 can be appropriately adopted, and examples thereof include a method in which the film-like adhesive is bonded to the back surface of the semiconductor wafer 1, and then, when two or more layers are laminated, film-like adhesives are sequentially laminated until the desired thickness is achieved, or a method in which film-like adhesives are first laminated to the desired thickness and then laminated to the back surface of the semiconductor wafer 1. Furthermore, there are no particular limitations on the device used when providing such adhesive layer 2 on the back surface of the semiconductor wafer 1, and for example, known devices such as a roll laminator or a manual laminator can be appropriately used.

[0070] 2, the semiconductor wafer 1 and the adhesive layer 2 are simultaneously diced to obtain a semiconductor chip 5 with an adhesive layer, which comprises the semiconductor wafer 1 and the adhesive layer 2, on the dicing tape 3. The dicing tape 3 is not particularly limited, and any known dicing tape can be used as appropriate. Furthermore, the device used for dicing is not particularly limited, and any known dicing device can be used as appropriate.

[0071] 3, the dicing tape 3 is removed from the adhesive layer 2, and the semiconductor chip 5 with the adhesive layer and the wiring board 6 are thermocompression bonded via the adhesive layer 2, thereby mounting the semiconductor chip 5 with the adhesive layer on the wiring board 6. As the wiring board 6, any substrate having a semiconductor circuit formed on its surface can be used as appropriate, and examples thereof include printed circuit boards (PCBs), various lead frames, and substrates having electronic components such as resistors and capacitors mounted on their surfaces.

[0072] There are no particular limitations on the method for mounting the semiconductor chip 5 with an adhesive layer on such a wiring board 6, and any conventional method can be appropriately employed that is capable of using the adhesive layer 2 to bond the semiconductor chip 5 with an adhesive layer to the wiring board 6 or to an electronic component mounted on the surface of the wiring board 6. Examples of such a mounting method include conventionally known heating and pressure methods, such as a method using a mounting technique that uses a flip-chip bonder that has a heating function from above, a method that uses a die bonder that has a heating function only from below, and a method that uses a laminator.

[0073] In this way, by mounting a semiconductor chip 5 with an adhesive layer on a wiring board 6 via an adhesive layer 2 made of the film-like adhesive of the present invention, the film-like adhesive can be made to conform to the unevenness on the wiring board 5 caused by electronic components, making it possible to fix the semiconductor chip 4 and wiring board 6 in close contact with each other.

[0074] Next, in the fourth step, the film-like adhesive of the present invention is thermally cured. The thermal curing temperature is not particularly limited as long as it is equal to or higher than the thermal curing initiation temperature of the film-like adhesive of the present invention. This temperature varies depending on the types of epoxy resin (A), polymer component (C), and epoxy curing agent (B) used, and no generalizations can be made. However, for example, 100 to 180°C is preferred, and 140 to 180°C is more preferred from the viewpoint that curing at higher temperatures allows for shorter curing times. If the temperature is below the thermal curing initiation temperature, the thermal curing does not proceed sufficiently, and the strength of the adhesive layer 2 tends to decrease. On the other hand, if the temperature exceeds the upper limit, the epoxy resin, curing agent, additives, etc. in the film-like adhesive tend to volatilize during the curing process, causing foaming. Furthermore, the curing time is preferably 10 to 120 minutes. In the present invention, by thermally curing the film-like adhesive at a high temperature, a semiconductor package can be obtained in which the wiring substrate 6 and the semiconductor chip 4 are firmly bonded without generating voids even when cured at a high temperature.

[0075] 4, it is preferable to connect the wiring substrate 6 and the semiconductor chip 5 with the adhesive layer via a bonding wire 7. There are no particular restrictions on the method for such connection, and any conventionally known method, such as a wire bonding method or a TAB (Tape Automated Bonding) method, can be used as appropriate.

[0076] Alternatively, multiple semiconductor chips can be stacked by thermocompressing and thermosetting another semiconductor chip 4 on the surface of the mounted semiconductor chip 4 and then connecting it again to the wiring board 6 by wire bonding. For example, there is a method of stacking semiconductor chips by shifting them as shown in Fig. 5, or a method of stacking them while embedding bonding wires 7 by thickening the adhesive layer 2 from the second layer onwards as shown in Fig. 6.

[0077] In the method for manufacturing a semiconductor package of the present invention, as shown in Figure 7, it is preferable to seal the wiring substrate 6 and the semiconductor chip 5 with an encapsulating resin 8, thereby obtaining a semiconductor package 9. There are no particular restrictions on the encapsulating resin 8, and any known encapsulating resin that can be used in the manufacture of semiconductor packages can be used. There are also no particular restrictions on the method for sealing using the encapsulating resin 8, and any known method can be used.

[0078] The semiconductor package manufacturing method of the present invention can provide an adhesive layer 2 that suppresses the generation of voids after the die-attach process, even in the form of a thin film, and that exhibits high adhesive strength with the adherend. Furthermore, by exhibiting excellent thermal conductivity after thermal curing, it becomes possible to efficiently dissipate heat generated on the surface of the semiconductor chip 4 to the outside of the semiconductor package 9.

[0079] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples. In each example and comparative example, the arithmetic mean roughness Ra, melt viscosity, thermal conductivity, wafer lamination property evaluation, die attach property evaluation, and adhesive strength evaluation were performed by the methods shown below. Room temperature means 25°C, MEK is methyl ethyl ketone, and PET is polyethylene terephthalate.

[0080] <Measurement of Average Particle Size (d50) and the Ratio of Particle Size (d90) at 90% Cumulative Distribution Frequency / Average Particle Size (d50)> 0.1 g of each inorganic filler used in each Example and Comparative Example and 9.9 g of MEK were weighed, and the mixture was subjected to ultrasonic dispersion treatment for 5 minutes to prepare a measurement sample. For this measurement sample, the average particle size (d50) and the particle size (d90) at 90% cumulative distribution frequency were determined from the cumulative curve of particle size volume fraction of the particle size distribution measured using a laser diffraction / scattering method (model: LMS-2000e, manufactured by Seishin Enterprise Co., Ltd.). From these values, the ratio of the particle size (d90) at 90% cumulative distribution frequency to the average particle size (d50), i.e., d90 / d50, was calculated.

[0081] <Arithmetic mean roughness Ra> The arithmetic mean roughness Ra of the film adhesive was measured using a surface roughness measuring instrument (model: SV3000-CNC, manufactured by Mitutoyo Corporation). The measurement conditions were as follows. For all film adhesives, the surface of the film adhesive that was not in contact with the release film exhibited a larger arithmetic mean roughness Ra than the surface that was in contact with the release film. The arithmetic mean roughness Ra of the surface that was not in contact with the release film is listed in the table below. Cutoff value: 0.8 mm Evaluation length: 4 mm Measurement speed: 0.3 mm / s Stylus tip radius (R): 2 μm

[0082] <Melt Viscosity Measurement> A square measuring 5.0 cm long x 5.0 cm wide was cut from the film-like adhesive with release film obtained in each Example and Comparative Example, and the cut samples were stacked with the release film peeled off and bonded together with a hand roller on a hot plate with a stage set at 70°C to obtain a test piece with a thickness of approximately 1.0 mm. For this test piece, the change in viscous resistance was measured using a rheometer (RS6000, manufactured by Haake Co., Ltd.) over a temperature range of 20 to 250°C at a heating rate of 5°C / min. The melt viscosities (Pa s) at 70°C and 120°C were calculated from the obtained temperature-viscosity resistance curves.

[0083] <Thermal Conductivity> A square piece with a side length of 50 mm or more was cut from the film-like adhesive with release film obtained in each Example and Comparative Example, and the cut samples were stacked with the release film removed to a thickness of 5 mm or more. This sample was placed on a disk-shaped mold with a diameter of 50 mm and a thickness of 5 mm, heated at 150 ° C and a pressure of 2 MPa using a compression press molding machine for 10 minutes, removed, and then further heated at 180 ° C in a dryer for 1 hour to thermally cure the film-like adhesive, obtaining a disk-shaped test piece with a diameter of 50 mm and a thickness of 5 mm. The thermal conductivity (W / (m K)) of this test piece was measured using a thermal conductivity measuring device (product name: HC-110, manufactured by Eiko Seiki Co., Ltd.) using the heat flow meter method (compliant with JIS-A1412).

[0084] <Wafer Lamination Evaluation> The film-like adhesive with release film obtained in each Example and Comparative Example was first bonded to one side of a dummy silicon wafer (8 inch size, 100 μm thick) using a manual laminator (product name: FM-114, manufactured by Technovision) at a temperature of 70°C and a pressure of 0.3 MPa so that the film-like adhesive came into contact with the wafer. After bonding, the presence or absence of voids at the interface between the film-like adhesive and the wafer was visually observed from the film-like adhesive side, and the wafer lamination properties were evaluated based on the following evaluation criteria. In this test, an evaluation rank of "A" is the level required for practical use. - Evaluation criteria - A: No voids observed. B: Voids observed.

[0085] <Evaluation of die attachment properties> The film-like adhesive with release film obtained in each example and comparative example was first adhered to one side of a dummy silicon wafer (8 inch size, 100 μm thick) using a manual laminator (trade name: FM-114, manufactured by Technovision Co., Ltd.) at a temperature of 70°C and a pressure of 0.3 MPa. Thereafter, the release film was peeled from the film-like adhesive, and then a dicing tape (trade name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (trade name: DTF2-8-1H001, manufactured by DISCO Corporation) were adhered to the side of the film-like adhesive opposite the dummy silicon wafer using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, a dicing machine (trade name: DFD-6340, manufactured by DISCO) equipped with a two-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO) was used to dic the dummy silicon wafer to a size of 10 mm x 10 mm, and a dummy chip was obtained. Next, using a die bonder (trade name: DB-800, manufactured by Hitachi High-Technologies Corporation), the dummy chip with the film-like adhesive was picked up from the dicing tape and subjected to thermal compression bonding under conditions of 120 ° C., a pressure of 0.1 MPa (load 400 gf), and a time of 1.0 second, so that the film-like adhesive side of the dummy chip with the film-like adhesive and the mounting surface side of the lead frame substrate (42 Alloy system, manufactured by Toppan Printing Co., Ltd.) were bonded together. Here, the mounting surface of the lead frame substrate is a metal surface with slight surface roughness. The dummy chips with film-like adhesive thermocompression bonded to the substrate were observed for the presence or absence of voids at the interface between the film-like adhesive and the mounting surface of the lead frame substrate using an ultrasonic flaw detector (SAT) (FS300III manufactured by Hitachi Power Solutions), and the die attachment properties were evaluated based on the following evaluation criteria. In this test, an evaluation rank of "A" is the pass level. - Evaluation criteria - A: No voids were observed in any of the 24 mounted semiconductor chips. B: Voids were observed in at least one of the 24 mounted semiconductor chips.

[0086] <Adhesion Strength Evaluation> The film-like adhesive with release film obtained in each Example and Comparative Example was first adhered to one side of a dummy silicon wafer (8 inch size, thickness 350 μm) using a manual laminator (trade name: FM-114, manufactured by Technovision Co., Ltd.) at a temperature of 70°C and a pressure of 0.3 MPa. Thereafter, the release film was peeled from the film-like adhesive, and then a dicing tape (trade name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (trade name: DTF2-8-1H001, manufactured by DISCO Corporation) were adhered to the side of the film-like adhesive opposite the dummy silicon wafer using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, dicing was performed from the dummy silicon wafer side to a size of 2 mm x 2 mm using a dicing machine (trade name: DFD-6340, manufactured by DISCO Corporation) equipped with a two-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO Corporation / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO Corporation), to obtain dummy chips. Next, the dummy chip with the film adhesive was picked up from the dicing tape using a die bonder (trade name: DB-800, manufactured by Hitachi High-Technologies Corporation), and the film adhesive side of the dummy chip with the film adhesive was bonded to the mounting side of a lead frame substrate (42 Alloy series, manufactured by Toppan Printing Co., Ltd.) under conditions of 120°C, a pressure of 0.1 MPa (load 400 gf), and a time of 1.0 second, by thermocompression bonding. The film adhesive was then thermally cured by heating at a temperature of 125°C for 1 hour in a dryer. The shear peel strength (adhesion strength) of the bonded chip to the lead frame substrate was measured using a universal bond tester (trade name: Series 4000PXY, manufactured by Nordson Advanced Technologies Co., Ltd.) for the dummy chip with the film adhesive bonded to the substrate, and evaluated according to the following criteria. In this test, an evaluation rank of "A" is a passing level. - Evaluation criteria - A: Adhesion strength of 40 MPa or more B: Adhesion strength of 10 MPa or more but less than 40 MPa C: Adhesion strength less than 10 MPa

[0087] [Preparation of Particle Size Distribution of Inorganic Filler] The particle size distribution of each inorganic filler was prepared by Preparation Method A or B, and used in the following Examples. (Inorganic Fillers) AO-502: Trade name, manufactured by Admatechs Co., Ltd., alumina filler, thermal conductivity of alumina: 36 W / m·K ASFP-20: Trade name, manufactured by Denka Co., Ltd., alumina filler, thermal conductivity of alumina: 36 W / m·K DAW-03: Trade name, manufactured by Denka Co., Ltd., alumina filler, thermal conductivity of alumina: 36 W / m·K SC0280-SF: Trade name, manufactured by Mitsubishi Materials Corporation, silver-coated silicone resin filler, thermal conductivity of silver: 429 W / m·K (Preparation Methods) Preparation Method A: The particle size distribution of the inorganic filler was prepared using a 1.3 μm mesh filter. Preparation method B: The particle size distribution of the inorganic filler was adjusted using a capsule filter cartridge (trade name: CCPD-10, model number C1, 10 μm mesh filter).

[0088] The average particle size (d50), particle size at 90% cumulative distribution frequency (d90), and the ratio (d90 / d50) of the particle size at 90% cumulative distribution frequency (d90) to the average particle size (d50) before and after particle size distribution preparation are summarized in the table below.

[0089]

[0090] [Preparation of Adhesive Composition and Film-Like Adhesive] (Example 1) 56 parts by mass of triphenylmethane type epoxy resin (trade name: EPPN-501H, mass average molecular weight: 1000, softening point: 55°C, semi-solid, epoxy equivalent: 167 g / eq, manufactured by Nippon Kayaku Co., Ltd.), 49 parts by mass of bisphenol A type epoxy resin (trade name: YD-128, mass average molecular weight: 400, softening point: 25°C or less, liquid, epoxy equivalent: 190 g / eq, manufactured by Shinnikka Epoxy Manufacturing Co., Ltd.), 30 parts by mass of bisphenol A type phenoxy resin (trade name: YP-50, mass average molecular weight: 70000, Tg: 84°C, manufactured by Shinnikka Epoxy Manufacturing Co., Ltd.), and 67 parts by mass of MEK were heated and stirred in a 1000 ml separable flask at a temperature of 110°C for 2 hours to obtain a resin varnish. Next, this resin varnish was transferred to an 800 ml planetary mixer, and 205 parts by weight of No. 1B inorganic filler with a particle size distribution adjusted was added. 8.5 parts by weight of an imidazole-type curing agent (trade name: 2PHZ-PW, manufactured by Shikoku Kasei Co., Ltd.), and 3.0 parts by weight of a silane coupling agent (trade name: Sila-Ace S-510, manufactured by JNC Corporation) were added. The mixture was stirred and mixed at room temperature for 1 hour, and then vacuum degassed to obtain a mixed varnish. The resulting mixed varnish was then applied to a 38 μm thick release-treated PET film (release film) and dried by heating at 130 ° C. for 10 minutes to obtain a film-like adhesive with a release film measuring 300 mm in length, 200 mm in width, and 8 μm in thickness.

[0091] (Example 2) An adhesive composition and a film-like adhesive with a release film of Example 2 were obtained in the same manner as in Example 1, except that 313 parts by mass of No. 1B inorganic filler whose particle size distribution had been adjusted and 103 parts by mass of MEK were used in Example 1. (Example 3) An adhesive composition and a film-like adhesive with a release film of Example 3 were obtained in the same manner as in Example 1, except that 475 parts by mass of No. 1B inorganic filler whose particle size distribution had been adjusted and 158 parts by mass of MEK were used in Example 1. (Example 4) An adhesive composition and a film-like adhesive with a release film of Example 4 were obtained in the same manner as in Example 1, except that 205 parts by mass of No. 2B inorganic filler whose particle size distribution had been adjusted in Example 1 was used in Example 1. (Example 5) An adhesive composition and a film-like adhesive with a release film of Example 5 were obtained in the same manner as in Example 1, except that 313 parts by mass of No. 2B inorganic filler whose particle size distribution had been adjusted and 103 parts by mass of MEK were used in Example 1. Example 6 An adhesive composition and a film-like adhesive with a release film of Example 6 were obtained in the same manner as in Example 1, except that 475 parts by mass of No. 2B inorganic filler, whose particle size distribution had been adjusted, and 158 parts by mass of MEK were used. Example 7 An adhesive composition and a film-like adhesive with a release film of Example 7 were obtained in the same manner as in Example 1, except that 205 parts by mass of No. 3B inorganic filler, whose particle size distribution had been adjusted, and a capsule filter cartridge (product name: CCPD-10, model number C1, 10 μm mesh filter) were used. Example 8 An adhesive composition and a film-like adhesive with a release film of Example 8 were obtained in the same manner as in Example 1, except that 313 parts by mass of No. 3B inorganic filler, whose particle size distribution had been adjusted, and 103 parts by mass of MEK were used. Example 9 An adhesive composition and a film-like adhesive with a release film of Example 8 were obtained in the same manner as in Example 1, except that 313 parts by mass of No. 3B inorganic filler, whose particle size distribution had been adjusted, and 103 parts by mass of MEK were used. An adhesive composition and a film-like adhesive with a release film of Example 9 were obtained in the same manner as in Example 1, except that 475 parts by mass of No. 3B inorganic filler and 158 parts by mass of MEK were used. (Example 10) An adhesive composition and a film-like adhesive with a release film of Example 10 were obtained in the same manner as in Example 1, except that 350 parts by mass of No. 4B inorganic filler whose particle size distribution had been adjusted in Example 1 and 88 parts by mass of MEK were used.(Example 11) An adhesive composition and a film-like adhesive with a release film of Example 11 were obtained in the same manner as in Example 1, except that 220 parts by mass of No. 4B inorganic filler whose particle size distribution had been adjusted and 88 parts by mass of MEK were used in Example 1. (Example 12) An adhesive composition and a film-like adhesive with a release film of Example 12 were obtained in the same manner as in Example 1, except that 170 parts by mass of No. 4B inorganic filler whose particle size distribution had been adjusted and 88 parts by mass of MEK were used in Example 1. (Example 13) An adhesive composition and a film-like adhesive with a release film of Example 13 were obtained in the same manner as in Example 1, except that 127 parts by mass of No. 4B inorganic filler whose particle size distribution had been adjusted and 88 parts by mass of MEK were used in Example 1.

[0092] (Comparative Example 1) An adhesive composition and a film-like adhesive with a release film of Comparative Example 1 were obtained in the same manner as in Example 1, except that 313 parts by mass of No. 1A inorganic filler whose particle size distribution had not been adjusted and 103 parts by mass of MEK were used. (Comparative Example 2) An adhesive composition and a film-like adhesive with a release film of Comparative Example 2 were obtained in the same manner as in Comparative Example 1, except that 313 parts by mass of No. 2A inorganic filler whose particle size distribution had not been adjusted was used. (Comparative Example 3) An adhesive composition and a film-like adhesive with a release film of Comparative Example 3 were obtained in the same manner as in Comparative Example 1, except that 313 parts by mass of No. 3A inorganic filler whose particle size distribution had not been adjusted was used. (Comparative Example 4) An adhesive composition and a film-like adhesive with a release film of Comparative Example 4 were obtained in the same manner as in Comparative Example 1, except that 350 parts by mass of No. 4A inorganic filler whose particle size distribution had not been adjusted was used. Comparative Example 5 The film-like adhesive composition and film-like adhesive with a release film of Comparative Example 5 were the same as the film-like adhesive composition and film-like adhesive with a release film of Comparative Example 1. In the wafer lamination evaluation, die attachability evaluation, and adhesive strength evaluation, the temperature for adhesion to the wafer was changed from 70°C to 100°C, and the temperature for thermocompression bonding to the lead frame substrate was changed from 120°C to 150°C, and the evaluations were performed.

[0093] The obtained film-like adhesive with release film was evaluated for surface roughness, melt viscosity, thermal conductivity, wafer lamination, die attachability, and adhesive strength, as described above. The results are shown in Table 2 below, along with the compositions of the adhesive composition and film-like adhesive.

[0094]

[0095]

[0096]

[0097]

[0098] <Notes for the table> "-" in the inorganic filler column means that the component is not contained. ＊ " indicates that the evaluation was performed by changing the temperature for bonding to the wafer from 70°C to 100°C and the temperature for thermocompression bonding to the lead frame substrate from 120°C to 150°C. "Inorganic filler material [vol%]" is the proportion (vol%) of the inorganic filler (D) in the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C), and the inorganic filler (D).

[0099] The following can be seen from Table 2 above. The film-like adhesives of Examples 1 to 13 contain an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), and an inorganic filler (D), with the inorganic filler (D) accounting for 30 to 70 volume % of the total content of these components (A) to (D), and the inorganic filler (D) has an average particle size (d50) of 0.1 to 3.5 μm, and the ratio of the particle size (d90) at 90% cumulative distribution frequency to the average particle size (d50) is 5.0 or less. These film-like adhesives of Examples 1 to 10 have thermal conductivity and are thin films with a thickness of 8 μm. However, in a die-attach evaluation, no voids were observed in any of the semiconductor chips observed, and they also exhibited high adhesive strength and excellent adhesion.

[0100] In contrast, Comparative Examples 1 to 4 have average particle diameters (d50) in the range of 0.1 to 3.5 μm, but the ratio of the particle diameter (d90) at 90% cumulative distribution frequency to the average particle diameter (d50) exceeds 5.0, and therefore are not film-like adhesives obtained from the adhesive composition defined in the present invention. In Comparative Example 1, voids were observed in four semiconductor chips during the die attachability evaluation, and in Comparative Example 2, voids were observed in eight semiconductor chips during the die attachability evaluation. Furthermore, in Comparative Examples 1 and 2, the adhesive strength was low, less than 10 MPa, indicating poor adhesion. In Comparative Example 3, voids were observed in ten semiconductor chips during the die attachability evaluation, and the adhesive strength was low, less than 40 MPa, indicating poor adhesion. In Comparative Example 4, voids were observed in three semiconductor chips during the die attachability evaluation, indicating poor void suppression. On the other hand, Comparative Example 5 is an example in which the same film adhesive as Comparative Example 1 was used, but the bonding temperature to the wafer was changed from 70°C to 100°C, and the thermocompression bonding temperature to the lead frame substrate was changed from 120°C to 150°C. In Comparative Example 5, by adjusting the bonding temperature to the wafer and the thermocompression bonding temperature to the lead frame substrate, no voids were observed in the die attach property evaluation, but the adhesive strength was low at less than 10 MPa, resulting in poor adhesiveness. In other words, in the form of a thin film adhesive with a thickness of less than 10 μm, there is not necessarily a correlation between the presence or absence of voids and adhesive strength. It was found that by using a film adhesive obtained from the adhesive composition of the present invention, it is possible to achieve both suppression of void generation and excellent adhesiveness.

[0101] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0102] This application claims priority based on Japanese Patent Application No. 2019-152371, filed in Japan on August 22, 2019, the contents of which are incorporated herein by reference.

[0103] REFERENCE SIGNS LIST 1 semiconductor wafer 2 film-like adhesive layer 3 dicing tape 4 semiconductor chip 5 semiconductor chip with film-like adhesive 6 wiring substrate 7 bonding wire 8 sealing resin 9 semiconductor package

Claims

DEPCT651. The composition of an adhesive consisting of epoxy resin (A), epoxy resin curing agent (B), polymer component (C), and inorganic filler (D), where the inorganic filler (D) satisfies condition (1) of (average diameter (d50) is 0.1 to 3.5 μm) and condition (2) of (ratio of particle diameter at cumulative dispersion frequency 90% (d90) to average diameter (d50) is 5.0 or less), and where the proportion of inorganic filler (D) in the total packed volume of epoxy resin (A), epoxy resin curing agent (B), polymer component (C), and inorganic filler (D) is 5.0 or less, 1. The composition of the adhesive according to claim 1, whereby when the film-forming adhesive derived from the adhesive composition is heated at a temperature increase rate of 5 °C / min from 25 °C, the melt viscosity at 70 °C to a range of 6,000 to 50,000 Pascal•s and the melt viscosity at 120 °C to a range of 500 to 10,000 Pascal•s, and whereby a cured product is obtained which has a thermal conductivity of 1.0 W / m•Kalvin or more after heat curing of the film adhesive.

3. The composition of the adhesive following claim 1 or 2 in which the polymer component (C) is incorporated with phenoxy resin.

4. The composition of the adhesive following any one of claims 1 through 3 in which the inorganic filler (D) is a particle made of a thermally conductive material or a particle whose surface is coated with a thermally conductive material and where the thermal conductivity of the thermally conductive material is 12 W / m•Kalvin or more.

5. The film adhesive obtained from 6. The method of manufacturing the film adhesive, which includes the production of coating any of the adhesive components under Patents 1 through 4 onto a substrate film subject to release and drying of the adhesive components. 7.The method of manufacturing semiconductor packaging consists of four steps: the first step involves the application of a film-type adhesive layer, as per claim 5, to the back surface of a semiconductor wafer where at least one semiconductor circuit is formed, and the provision of a cube tape through the adhesive layer; the second step involves the simultaneous cube formation of the semiconductor wafer and the adhesive layer to obtain a semiconductor chip with an adhesive layer, in which the semiconductor chip with an adhesive layer includes the semiconductor wafer and the adhesive layer on a cube tape; the third step involves the removal of the cube tape from the adhesive layer and the thermal application of the semiconductor chip with an adhesive layer and the wiring panel through the adhesive layer; and the fourth step involves the thermal curing of the adhesive layer.Semiconductor packaging in which semiconductor chips and wiring boards or semiconductor chips are bonded to heat-curing film-type components as per claim 5-----------------------------------------------------------;.