Adhesive film for semiconductor, method for producing the same, and semiconductor package

Abstract

To provide an adhesive film for semiconductors capable of suppressing generation of hot spots inside a semiconductor package.SOLUTION: An adhesive film for semiconductors comprises a plate-shaped thermally conductive filler and a mesogenic compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an adhesive film for a semiconductor, a method for manufacturing the same, and a semiconductor package. [Background technology]

[0002] Conventionally, semiconductor packages (hereinafter simply referred to as "packages") have been manufactured using a wire bonding method in which a semiconductor chip and a substrate are connected using thin metal wires such as gold wires. However, in order to meet the demands for higher functionality, higher integration, and higher speeds for packages, a flip-chip connection method (FC connection method) is becoming more widespread, in which conductive protrusions called bumps are formed on the semiconductor chip or substrate to directly connect the semiconductor chip and the substrate.

[0003] For example, the COB (Chip On Board) type connection method used for BGA (Ball Grid Array), CSP (Chip Size Package), etc., in connection between semiconductor chips and substrates also falls under the FC connection method. The FC connection method is also used in the COC (Chip On Chip) type connection method, in which connection parts (e.g., bumps and wiring) are formed on semiconductor chips to connect between semiconductor chips.

[0004] Furthermore, in the case of packages that require even smaller size, thinner design, and higher functionality, chip-stacked packages, POP (Package On Package), TSV (Through-Silicon Via), and other technologies that stack and multi-layer chips using the above-mentioned connection methods are beginning to become popular. These stacking and multi-layering technologies arrange connecting components such as semiconductor chips three-dimensionally, allowing for smaller packages compared to methods that arrange these connecting components two-dimensionally. Furthermore, because they are effective in improving semiconductor performance, reducing noise, reducing mounting area, and saving power, they are attracting attention as a next-generation semiconductor wiring technology.

[0005] Also, from the perspective of improving productivity, COW (Chip On Wafer) is attracting attention, in which semiconductor chips are pressure-bonded (connected) onto a semiconductor wafer and then separated into individual pieces to create packages. From a similar perspective, gang bonding is also attracting attention, in which multiple semiconductor chips are aligned and temporarily pressure-bonded onto a semiconductor wafer or map substrate, and then these multiple semiconductor chips are finally pressure-bonded together to ensure connection.

[0006] To connect the above-mentioned connecting members such as semiconductor chips, a film-like adhesive (hereinafter referred to as "adhesive film") is sometimes used (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-294382 [Non-patent literature]

[0008] [Non-Patent Document 1] ACS Nano 2019, 13, 337-345. [Non-patent document 2] J. APPL. POLYM. SCI. 2014, 131, 39768. Summary of the Invention [Problem to be solved by the invention]

[0009] In recent years, packages manufactured using the above method have become more highly functional and integrated, resulting in narrower gaps between layers and narrower pitches between wiring. This has also increased the amount of heat generated by the package, making it more likely that localized high-temperature areas known as hot spots will occur inside the package (especially between connecting members). Since hot spots can cause connecting members to malfunction, it is desirable to prevent them from occurring.

[0010] Therefore, one aspect of the present disclosure aims to provide an adhesive film for semiconductors that helps to suppress the occurrence of hot spots inside a semiconductor package. [Means for solving the problem]

[0011] Some aspects of the present disclosure provide the following [1] to

[10] .

[0012] [1] An adhesive film for semiconductors, comprising a plate-like thermally conductive filler and a mesogenic compound.

[0013] [2] The adhesive film for semiconductors according to [1], wherein the planar aspect ratio of the plate-like thermally conductive filler is 1.2 or more.

[0014] [3] The adhesive film for semiconductors according to [1] or [2], wherein the tabular thermally conductive filler contains hexagonal boron nitride.

[0015] [4] The adhesive film for a semiconductor according to any one of [1] to [3], which has thermosetting properties.

[0016] [5] An adhesive film for a semiconductor according to any one of [1] to [4], which has a multilayer structure, and at least one layer constituting the multilayer structure contains the tabular thermally conductive filler and the mesogenic compound.

[0017] [6] a first layer containing a first filler and a first mesogenic compound; a second layer containing a second filler and a second mesogenic compound; the first filler and the second filler are flat thermally conductive fillers having a planar aspect ratio of 1.2 or more; [5] An adhesive film for semiconductors as described in [5], wherein the angle between the direction in which the thermal conductivity of the first layer is highest and the direction in which the thermal conductivity of the second layer is highest among directions parallel to the main surface of the adhesive film is 80 to 100°.

[0018] [7] A method for producing an adhesive film for semiconductors, comprising applying a composition containing a flat thermally conductive filler and a mesogenic compound onto a substrate to form a layer containing the flat thermally conductive filler and the mesogenic compound.

[0019] [8] applying a first composition containing a first filler and a first mesogenic compound onto a substrate to form a first layer containing the first filler and the first mesogenic compound; applying a second composition containing a second filler and a second mesogenic compound onto a substrate to form a second layer containing the second filler and the second mesogenic compound; laminating the first layer and the second layer; the first filler and the second filler are flat thermally conductive fillers having a planar aspect ratio of 1.2 or more; A method for producing an adhesive film for semiconductors as described in claim 7, wherein the first layer and the second layer are laminated so that the angle between the application direction of the first composition and the application direction of the second composition is 80 to 100 degrees.

[0020] [9] a semiconductor chip having a first connection portion, a base having a second connection portion electrically connected to the first connection portion, and a sealing portion that bonds the semiconductor chip and the base and fills a gap between the semiconductor chip and the base, A semiconductor package, wherein the sealing part is formed from the adhesive film for a semiconductor according to any one of [1] to [6].

[0021]

[10] The semiconductor package according to [9], wherein the sealing portion includes a layered nanovoid aggregation region. [Effects of the Invention]

[0022] According to one aspect of the present disclosure, it is possible to provide an adhesive film for a semiconductor that contributes to suppressing the occurrence of hot spots inside a semiconductor package. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of the semiconductor adhesive film of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another embodiment of the semiconductor adhesive film of the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view showing another embodiment of the semiconductor adhesive film of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view showing another embodiment of the semiconductor adhesive film of the present disclosure. [Figure 5] FIG. 5 is a schematic cross-sectional view showing one embodiment of a semiconductor package according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, unless specifically stated otherwise, the units of the numerical values ​​before and after "to" are the same. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limits individually described can be arbitrarily combined. Furthermore, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more types. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0025] <Adhesive film for semiconductors> One embodiment of the present disclosure is an adhesive film for semiconductors (hereinafter, sometimes simply referred to as "adhesive film") that contains a mesogenic compound and a flat thermally conductive filler.

[0026] The adhesive film described above can prevent hot spots from occurring inside the semiconductor package. The reason for this effect is presumed to be as follows.

[0027] It is known that flat thermally conductive fillers interact with mesogenic compounds, and that flat thermally conductive fillers dispersed in mesogenic compounds are oriented by coating (see, for example, Non-Patent Document 1). Therefore, it is presumed that in the adhesive film, the flat thermally conductive fillers are oriented so that their plate surfaces are approximately parallel to the main surface of the adhesive film, forming regions with anisotropically high thermal conductivity. It is presumed that such regions allow heat to be diffused within the surface even if localized heat generation occurs within the package, and therefore that the adhesive film can suppress the occurrence of hot spots.

[0028] In addition to the problem of hot spots, stacked semiconductor packages also have the problem of heat generated in one semiconductor being conducted in the stacking direction, spreading to other semiconductors and causing thermal malfunctions (the so-called thermal crosstalk problem). Thermal crosstalk can also lead to the problem of hot spots being more likely to occur when heat generated in one semiconductor is added to heat generated in other semiconductors. Meanwhile, in the adhesive film, the tabular thermally conductive filler is oriented in the main surface direction, allowing heat to be selectively conducted in the main surface direction, thereby suppressing the occurrence of thermal crosstalk.

[0029] The adhesive film may be a film having a single layer structure or a film having a multilayer structure. When the adhesive film has a multilayer structure, at least one layer constituting the multilayer structure may contain a mesogenic compound and a flat thermally conductive filler.

[0030] The adhesive film may have the property of being cured by an external stimulus such as heat or light (external stimulus curing property). The adhesive film may be thermosetting or photocurable, but from the viewpoint of workability, it is preferably thermosetting.

[0031] The adhesive film may contain voids (hereinafter referred to as "macrovoids") with a size of about 1.0 to 2.0 μm. When the adhesive film contains macrovoids, nanovoid-collected regions can be formed in the sealed portion by adjusting the temperature and pressure during thermocompression bonding during mounting. Nanovoid-collected regions are regions formed when macrovoids become voids (hereinafter referred to as "nanovoids") with a size of about 5 to 800 nm and diffuse into the film. The size of the voids refers to the longest diameter of the voids observed in a cross section of the film in the thickness direction.

[0032] The thickness (total thickness) of the adhesive film is, for example, 3 to 50 μm.

[0033] Hereinafter, several embodiments of adhesive films for semiconductors will be described, with reference to the drawings as needed. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0034] (First embodiment) Fig. 1 is a schematic cross-sectional view showing an adhesive film for a semiconductor according to a first embodiment. The adhesive film 10 in Fig. 1 is a single-layer adhesive film made of an adhesive composition containing a flat, thermally conductive filler 1 and an adhesive component 2. In Fig. 1, the components contained in the adhesive film 10 other than the flat, thermally conductive filler are shown as adhesive component 2.

[0035] (Flat thermally conductive filler) A flat thermally conductive filler is a filler that has a flat shape and thermal conductivity. Here, "flat" refers to a filler that has length, width, and thickness, with the length (long side) and width (short side) each being at least five times the thickness. The length (long side) is measured at the largest point, and the width (short side) is determined by measuring the dimension perpendicular to the length in the same plane as the length measurement. Furthermore, "having thermal conductivity" refers to a thermal conductivity of at least 1 W / (m·K) as measured by the heat flow meter method, laser flash method, cyclic heating method, or hot wire method.

[0036] The plate-like thermally conductive filler is preferably an insulating filler, where insulating means that the resistance value measured by a powder resistance measuring device is greater than 1.0E+09 Ω.

[0037] The ratio of the length (long side) to the thickness of the plate-like thermally conductive filler may be 5 to 10,000, 10 or more, or 100 or more, or 1,000 or less, or 100 or less.

[0038] The ratio of the width (short side) to the thickness of the plate-like thermally conductive filler may be 5 to 1000, 10 or more, 100 or more, or 100 or less, or 10 or less.

[0039] The ratio of the length (long side) to the width (short side) of the plate-like thermally conductive filler, i.e., the planar aspect ratio of the plate-like thermally conductive filler, may be 1.2 or more, or may be 2 or more, 3 or more, or 10 or more. Because the plate-like thermally conductive filler tends to be oriented in the long side direction, when the planar aspect ratio is 1.2 or more, the thermal conductivity in the length direction (long side direction) of the filler in the direction parallel to the main surface of the adhesive film tends to be higher than the thermal conductivity in the width direction (short side direction) of the filler. The planar aspect ratio of the plate-like thermally conductive filler may be 80 or less (e.g., 1.2 to 80, 10 to 80, etc.), or may be 10 or less (e.g., 3 to 10).

[0040] The average particle size of the plate-like thermally conductive filler may be, for example, 0.05 to 20 μm. Here, the average particle size of the plate-like thermally conductive filler is the volume average particle size (median size, d50) at which the cumulative value of the cumulative particle size distribution is 50%, and is measured by a laser diffraction scattering method.

[0041] The plate-shaped thermally conductive filler contains at least a thermally conductive material, such as alumina, alumina nitride, silicon nitride, boron nitride, boron carbide, zinc oxide, and magnesium oxide. Among these, hexagonal boron nitride has high thermal conductivity and good flatness, and the use of hexagonal boron nitride can more significantly suppress the occurrence of hot spots.

[0042] The proportion of hexagonal boron nitride in the thermally conductive material may be 60 mass % or more, 80 mass % or more, or 90 mass % or more. The thermally conductive material may be composed solely of hexagonal boron nitride.

[0043] The plate-shaped thermally conductive filler may contain a material that does not have thermal conductivity as long as the thermal conductivity is not impaired. The content of the thermally conductive material may be, for example, 98% by mass or more, 99% by mass or more, or 99.5% by mass or more. The plate-shaped thermally conductive filler may be composed solely of the thermally conductive material.

[0044] The content of the flat thermally conductive filler in the adhesive composition may be, for example, 20 to 60 mass % based on the total amount of the adhesive composition, or may be 30 mass %, or may be 50 mass % or less, or 40 mass % or less.

[0045] As described above, the flat thermally conductive filler particles may be oriented so that their plate surfaces are approximately parallel to the main surface of the adhesive film. In this specification, "two surfaces are approximately parallel" is defined as the angle between two lines drawn on each of the two surfaces, the lines passing through the intersection of the two surfaces and perpendicular to the intersection, being 0 to 10°. The degree of orientation is not particularly limited, but from the viewpoint of easily achieving higher thermal conductivity anisotropy, it is preferred that, when a 0.1 mm × 0.1 mm area is observed in a cross section of the adhesive film in the thickness direction, at least 40% of the flat thermally conductive fillers contained in this area are oriented so that their plate surfaces are approximately parallel to the main surface of the adhesive film.

[0046] (adhesive component) The adhesive component contains at least a mesogenic compound and, if necessary, further contains components other than the mesogenic compound, such as a thermosetting resin (excluding the mesogenic compound), a curing agent, a thermoplastic resin, and a filler other than the flat thermally conductive filler (hereinafter referred to as "other filler").

[0047] [Mesogenic compounds] The mesogenic compound is a compound having a mesogenic skeleton. From the viewpoint of enhancing the interaction with the filler and the thermal conductivity between the filler and the resin, and between fillers, the mesogenic skeleton is preferably a skeleton having a condensed aromatic ring. Specific examples include a naphthalene skeleton, an anthracene skeleton, a tetracene skeleton, a pyrene skeleton, a phenanthrene skeleton, a perylene skeleton, a quinoline skeleton, and an acridine skeleton. Among the above, the mesogenic compound more preferably has at least one skeleton selected from the group consisting of a naphthalene skeleton, a biphenyl skeleton, and an anthracene skeleton.

[0048] From the viewpoint of enhancing the interaction with the filler and the thermal conductivity between the filler and the resin and between the fillers, the mesogenic compound preferably has a skeleton capable of forming van der Waals bonds or hydrogen bonds between fillers. From the viewpoints above, the mesogenic compound more preferably has at least one skeleton selected from the group consisting of an imide skeleton and an aramid skeleton.

[0049] The mesogenic compound may be polymerizable. That is, the mesogenic compound may have a polymerizable group in addition to the mesogenic skeleton. Examples of the polymerizable group include an epoxy group, an amino group, and a hydroxyl group. The mesogenic compound may be a compound having a carbonyl group (carbonyl compound), such as a carboxylic acid, an ester, an amide, an acyl halide, or an acid anhydride.

[0050] Specific examples of mesogenic compounds include 2,2′-[9,10-Anthracenediylbis(oxymethylene)]bis[oxirane], 9,10-Anthracenedirboxylic acid, 2,2′-[1,6-Naphthalenediylbis(oxymethylene)]bis[oxirane], 2,7-Naphthalenediol, 2,2′-[[1,1′-Biphenyl]-4,4′-diylbis(oxymethylene)]bis[oxirane], 4-(2-Oxiranylmethoxy)phenyl 4-(2-oxiranylmethoxy)benzoate, 4-(2-Oxiranylmethoxy)-N-[4-(2-oxiranylmethoxy)phenyl]benzamid, 4-[(4-Carboxybenzoyl)amino]benzoic aci, 4-hydroxy-, 4-hydroxyphenyl ester, 4,4′-Dihydroxybiphenyl, [1,1′-Biphenyl]-4,4′-dicarboxylic acid, 2,3,6,7,10,11-hexahydroxytriphenylene, 2,3,6,7,10,11-triphenylenehexacarboxylic acid, 2,3,6,7,10,11-triphenylenehexamin, 2,3,6,7,10,11-hexaglycidoxytriphenylene, oligobiphenyls, phthalocyanine derivatives, phenyl ester derivatives, and phenylamide derivatives.

[0051] The content of the mesogenic compound in the adhesive composition may be, for example, 5 to 80% by mass, or may be 10% by mass or more, or 20% by mass or more, or may be 60% by mass or less, or 30% by mass or less, based on the total amount of the adhesive composition.

[0052] The ratio of the content of the flat thermally conductive filler to the content of the mesogenic compound in the adhesive composition may be 0.2 to 20, or may be 0.5 or more, or 2 or more, or may be 3 or less, or 1 or less, in mass ratio.

[0053] [Thermosetting resin] Examples of thermosetting resins include epoxy resins, phenolic resins (except when contained as a curing agent), and acrylic resins. Among these, epoxy resins are preferably used. The content of the epoxy resin in the thermosetting resin is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total amount of the thermosetting resin. The content of the epoxy resin may be 100% by mass based on the total amount of the thermosetting resin.

[0054] Epoxy resins are compounds having two or more epoxy groups in the molecule. Examples of epoxy resins that can be used include bisphenol A epoxy resins, bisphenol F epoxy resins, naphthalene epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, phenol aralkyl epoxy resins, biphenyl epoxy resins, triphenylmethane epoxy resins, triphenolmethane epoxy resins, dicyclopentadiene epoxy resins, and various polyfunctional epoxy resins. These can be used alone or as a mixture of two or more. Among these, triphenolmethane epoxy resins (epoxy resins containing a triphenolmethane skeleton) tend to further reduce the amount of fillet formation.

[0055] As the epoxy resin, an epoxy resin that is liquid at 25°C (hereinafter simply referred to as "liquid epoxy resin") may be used, from the viewpoint of easily suppressing the occurrence of cracks and fissures on the film surface. Here, "liquid at 25°C" means that the viscosity at 25°C measured with an E-type viscometer is 400 Pa·s or less. Examples of liquid epoxy resins include glycidyl ethers of bisphenol A, glycidyl ethers of bisphenol AD, glycidyl ethers of bisphenol S, glycidyl ethers of bisphenol F, glycidyl ethers of hydrated bisphenol A, glycidyl ethers of ethylene oxide adducts of bisphenol A, glycidyl ethers of propylene oxide adducts of bisphenol A, glycidyl ethers of naphthalene resins, and trifunctional or tetrafunctional glycidyl amines.

[0056] The content of the liquid epoxy resin in the thermosetting resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total amount of the thermosetting resin, from the viewpoint of easily suppressing the occurrence of cracks and fissures on the film surface. The content of the liquid epoxy resin is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, based on the total amount of the thermosetting resin, from the viewpoint of easily suppressing an excessive increase in tackiness of the film and easily suppressing edge fusion.

[0057] The reactive functional group equivalent of the thermosetting resin (for example, the epoxy equivalent of the epoxy resin) may be 100 to 3000 g / eq, 100 to 2000 g / eq, or 100 to 1500 g / eq. When the reactive functional group equivalent is within the above range, a good balance between reactivity and fluidity during heating tends to be achieved.

[0058] The content of the thermosetting resin in the adhesive composition is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, based on the total amount of the adhesive composition, from the viewpoint of easily suppressing the occurrence of fillets. The content of the thermosetting resin is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the total amount of the adhesive composition, from the viewpoint of easily obtaining good sealing properties and easily suppressing the occurrence of voids.

[0059] [Hardening agent] As the curing agent, a known curing agent known as a curing agent for thermosetting resins can be used. Curing agents also include materials generally known as curing accelerators. When an epoxy resin is used as the thermosetting resin, examples of the curing agent that can be used include phenolic resin-based curing agents, acid anhydride-based curing agents, amine-based curing agents, imidazole-based curing agents, and phosphine-based curing agents. Among these, phenolic resin-based curing agents, acid anhydride-based curing agents, amine-based curing agents, and imidazole-based curing agents exhibit flux activity that suppresses the formation of an oxide film at the connection, and therefore, the use of these curing agents can improve connection reliability. From the viewpoint of being able to rapidly proceed with curing when heating is performed at low temperatures, it is preferable to use an imidazole-based curing agent.

[0060] The content of the thermosetting agent in the adhesive composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the thermosetting resin, from the viewpoint of improving curing properties upon heating. The content of the thermosetting agent is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the thermosetting resin, from the viewpoint of making it more difficult for the adhesive composition to intervene between the connected parts.

[0061] [Thermoplastic resin] Thermoplastic resins contribute to improving heat resistance and film formability. Examples of thermoplastic resins include phenoxy resins, polyimide resins, polyamide resins, polycarbodiimide resins, cyanate ester resins, acrylic resins, polyester resins, polyethylene resins, polyethersulfone resins, polyetherimide resins, polyvinyl acetal resins, urethane resins, and acrylic rubber. Among these, from the viewpoint of easily obtaining excellent heat resistance and film formability, phenoxy resins, polyimide resins, acrylic rubbers, cyanate ester resins, and polycarbodiimide resins are preferred, and phenoxy resins, polyimide resins, and acrylic rubbers are more preferred. These thermoplastic resins can be used alone or as a mixture or copolymer of two or more types.

[0062] The weight average molecular weight of the thermoplastic resin is, for example, 10,000 or more, and may be 20,000 or more, or 30,000 or more. Such a thermoplastic resin can further improve the heat resistance and film formability of the adhesive composition. From the viewpoint of more easily achieving an improved heat resistance effect, the weight average molecular weight of the thermoplastic resin may be 1,000,000 or less, or may be 500,000 or less. In this specification, the weight average molecular weight refers to the weight average molecular weight measured in polystyrene equivalent terms using high performance liquid chromatography (Shimadzu Corporation, product name: C-R4A).

[0063] The content of the thermoplastic resin in the adhesive composition is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the adhesive composition, from the viewpoint of easily improving the heat resistance and film formability of the adhesive composition. The content of the thermoplastic resin is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on the total amount of the adhesive composition, from the viewpoint of easily suppressing the occurrence of fillets.

[0064] [Other fillers] The other filler is effective in controlling the viscosity of the adhesive composition, the physical properties of the cured product of the adhesive composition, etc. Specifically, by using the other filler, it is possible to suppress the generation of voids during connection, reduce the moisture absorption rate of the cured product of the adhesive composition, etc. The other filler may be an inorganic filler (inorganic particles) or an organic filler (organic particles).

[0065] From the viewpoint of achieving even better insulation reliability, the other filler is preferably insulating. The adhesive composition preferably does not contain a filler containing a conductive material such as silver, solder, or carbon black (conductive filler).

[0066] The physical properties of the other fillers may be adjusted as appropriate by surface treatment. The other fillers may be surface-treated to improve dispersibility or adhesive strength. Examples of surface treatment agents include glycidyl (epoxy), amine, phenyl, phenylamino, (meth)acrylic, and vinyl compounds. Note that "(meth)acrylic" refers to at least one of acrylic and its corresponding methacrylic.

[0067] The average particle size of the other filler is, for example, 0.5 to 1.5 μm. From the viewpoint of preventing jamming during flip-chip connection, the average particle size of the other filler is preferably 1.5 μm or less, and from the viewpoint of excellent visibility (transparency), 1.0 μm or less is more preferable. The average particle size of the other filler is the particle size at the point corresponding to 50% volume when a cumulative frequency distribution curve of particle sizes is calculated assuming the total volume of the particles to be 100%, and can be measured using a particle size distribution measuring device using a laser diffraction scattering method.

[0068] The content of other fillers in the adhesive composition may be, for example, 10 to 90 mass % based on the total amount of the adhesive composition, or may be 40 mass % or more or 60 mass % or more, or may be 90 mass % or less or 60 mass % or less.

[0069] The adhesive composition may further contain various additives such as antioxidants, silane coupling agents, titanium coupling agents, leveling agents, ion trapping agents, and fluxing agents. These may be used alone or in combination of two or more. The content of these additives may be appropriately adjusted so that the effects of each additive are exerted.

[0070] The adhesive film 10 described above can be produced by a method including applying a composition containing each component constituting the adhesive film 10 (flat thermally conductive filler 1 and adhesive component 2) onto a substrate and forming a layer containing these components.

[0071] Specifically, first, of the components constituting the adhesive film, the flat thermally conductive filler 1 and the mesogenic compound are mixed and subjected to ultrasonic treatment, and then other components, if necessary, are mixed and stirred or kneaded to prepare a composition (coating liquid). The composition is then applied to a substrate (film or tape) that has been subjected to a release treatment on at least one side using a knife coater, roll coater, applicator, or the like to form a coating film. Next, if an organic solvent is used, the organic solvent is reduced from the coating film by heating. This allows the adhesive film 10 to be formed on the substrate.

[0072] The mixing conditions for the flat thermally conductive filler 1 and the mesogenic compound may be known conditions such as those described in Non-Patent Document 1. For example, ultrasonic treatment may be carried out using an ultrasonic cleaner or ultrasonic homogenizer at a frequency of 30 KHz or less (e.g., 15 to 30 KHz) for an irradiation time of 30 minutes or more (e.g., 30 to 120 minutes). Alternatively, dispersion and mixing may be carried out using a high-shear mixer or the like as another mixing condition.

[0073] Second Embodiment Fig. 2 is a schematic cross-sectional view showing an adhesive film for a semiconductor of a second embodiment. The adhesive film 20 of Fig. 2 has a layer (first layer) 13 containing a first filler 11 and a first adhesive component 12, and a layer (second layer) 16 containing a second filler 14 and a second adhesive component 15. The second layer 16 is provided on the first layer 13. The thickness of the first layer 13 is, for example, 2 to 12 µm, and the thickness of the second layer 16 is, for example, 3 to 20 µm.

[0074] The first filler 11 and the second filler 14 are flat thermally conductive fillers. Details of these fillers are the same as those of the flat thermally conductive filler 1 of the first embodiment, except that they have a planar aspect ratio of 1.2 or more. The first filler 11 and the second filler 14 may be the same as or different from each other.

[0075] Since the first filler 11 and the second filler 14 have the above-mentioned specific planar aspect ratio, they are oriented in the length direction (long side direction) of the fillers. Furthermore, the first filler 11 is oriented from the left to the right side of the paper in Fig. 2, and the second filler 14 is oriented from the back side to the front side of the paper in Fig. 2. The angle formed by the orientation directions of the first filler 11 and the second filler 14 in a direction parallel to the main surface of the adhesive film is preferably approximately a right angle (80 to 100°).

[0076] The degree of orientation of the first filler 11 and the second filler 14 is not particularly limited, but from the viewpoint of easily obtaining better thermal diffusivity, when observing a 0.2 mm × 0.2 mm region in a cross section parallel to the main surface of the adhesive film, it is preferable that 50% or more of the flat thermally conductive fillers contained in this region are oriented in approximately the same direction. Note that in this embodiment, if the angle between the orientation directions of the fillers is 0 to 30°, those fillers are considered to be oriented in approximately the same direction.

[0077] The first adhesive component 12 contains a first mesogenic compound, and the second adhesive component 15 contains a second mesogenic compound. The details of the first adhesive component 12 and the second adhesive component 15 are the same as those of the adhesive component 2 in the first embodiment. The first adhesive component 12 and the second adhesive component 15 may be the same as or different from each other.

[0078] The first layer 13 and the second layer 16 may have the same composition, but preferably have different compositions. By providing a difference in fluidity during thermocompression bonding, defects such as filler entrapment at the joint can be easily suppressed. From this perspective, it is preferable that the melt viscosities of the first layer 13 and the second layer 16 at the temperature during thermocompression bonding (e.g., 100 to 350°C) are different from each other.

[0079] In this embodiment, the first filler 11 and the second filler 14 are oriented in different directions, and therefore, among directions parallel to the main surface of the adhesive film 20, the direction in which the thermal conductivity of the first layer 13 is highest is different from the direction in which the thermal conductivity of the second layer 16 is highest. Therefore, the adhesive film 20 tends to exhibit better thermal diffusivity than the adhesive film 10 of the first embodiment. From the viewpoint of easily obtaining better thermal diffusivity, the angle formed between the direction in which the thermal conductivity of the first layer 13 is highest and the direction in which the thermal conductivity of the second layer 16 is highest is preferably approximately a right angle (80 to 100°).

[0080] The adhesive film 20 can be manufactured by a method including applying a first composition containing the components constituting the first layer 13 (first filler 11 and first adhesive component 12) onto a substrate to form the first layer 13, applying a second composition containing the components constituting the second layer 16 (second filler 14 and second adhesive component 15) onto the substrate to form the second layer 16, and laminating the first layer 13 and the second layer 16 together.

[0081] The details of the method for forming the first layer 13 and the second layer 16 are the same as the details of the method for manufacturing the adhesive film 10 in the first embodiment. In this embodiment, the second layer 16 may be formed on the first layer 13, thereby simultaneously forming the second layer 16 and laminating the first layer 13 and the second layer 16, or the second layer 16 may be formed on the substrate and then bonded to the first layer 13 and the second layer 16. The first layer 13 may be formed on the second layer 16, thereby simultaneously forming the first layer 13 and laminating the first layer 13 and the second layer 16.

[0082] The method for bonding the first layer 13 and the second layer 16 together (lamination) is not particularly limited, and may be, for example, hot pressing, roll lamination, vacuum lamination, etc. The lamination may be performed under a temperature condition of, for example, 0 to 80°C.

[0083] In this embodiment, by laminating the first layer 13 and the second layer 16 so that the angle between the application direction of the first composition and the application direction of the second composition is approximately right angles (80 to 100°), the angle between the orientation directions of the first filler 11 and the second filler 14 in a direction parallel to the main surface of the adhesive film can be made approximately right angles, and the angle between the direction in which the thermal conductivity of the first layer 13 is highest and the direction in which the thermal conductivity of the second layer 16 is highest can be made approximately right angles.

[0084] (Third embodiment) Fig. 3 is a schematic cross-sectional view showing an adhesive film for a semiconductor according to a third embodiment. The adhesive film 30 of Fig. 3 has a layer (first layer) 23 containing a flat thermally conductive filler 21 and a first adhesive component 22, and a layer (second layer) 25 containing a second adhesive component 24. The second layer 25 is provided on the first layer 23. The thickness of the first layer 23 is, for example, 2 to 12 µm, and the thickness of the second layer 25 is, for example, 3 to 20 µm.

[0085] The details of the first layer 23 are the same as those of the adhesive film 10 of the first embodiment.

[0086] The second layer 25 is a layer that does not contain a flat thermally conductive filler. The details of the second layer 25 are the same as those of the first layer 23, except that the second layer 25 does not contain a flat thermally conductive filler and does not necessarily contain a mesogenic compound.

[0087] The first layer 23 and the second layer 25 may have the same composition, but preferably have different compositions. By providing a difference in fluidity during thermocompression bonding, defects such as filler entrapment at the connection can be easily suppressed. From this perspective, it is preferable that the melt viscosities of the first layer 23 and the second layer 25 at the temperature during thermocompression bonding (e.g., 100 to 350°C) are different from each other.

[0088] In a layer containing a flat thermally conductive filler and a mesogenic compound, the flat thermally conductive filler is likely to be oriented, and therefore the layer may tear along the orientation direction of the flat thermally conductive filler during thermocompression bonding, and if a crack occurs at the joint, the filler may become trapped at the joint. On the other hand, because the adhesive film 30 includes the second layer 25 that does not contain a flat thermally conductive filler, even if a crack occurs in the first layer 23, the cracked portion is filled by the second layer 25, and therefore the above-mentioned filler trapping is unlikely to occur.

[0089] The adhesive film 30 can be produced in the same manner as the adhesive film 20 of the second embodiment. That is, the adhesive film 30 can be produced by a method including applying a first composition containing the components constituting the first layer 23 (flat thermally conductive filler 21 and first adhesive component 22) onto a substrate to form the first layer 23, applying a second composition containing the components constituting the second layer 25 (second adhesive component 24) onto the substrate to form the second layer 25, and laminating the first layer 23 and the second layer 25 together.

[0090] (Fourth embodiment) Fig. 4 is a schematic cross-sectional view showing an adhesive film for a semiconductor according to a fourth embodiment. The adhesive film 40 of Fig. 4 has a layer (first layer) 33 containing a first filler 31 and a first adhesive component 32, a layer (second layer) 35 containing a second adhesive component 34, and a layer (third layer) 38 containing a second filler 36 and a third adhesive component 37. The first layer 33, the second layer 35, and the third layer 38 are laminated in this order. The thickness of the first layer 33 is, for example, 1 to 12 µm, the thickness of the second layer 35 is, for example, 5 to 20 µm, and the thickness of the third layer 38 is, for example, 1 to 12 µm.

[0091] The details of the first layer 33 and the third layer 38 are the same as the details of the first layer 13 and the second layer 16 in the adhesive film 20 of the second embodiment. The details of the second layer 35 are the same as the details of the second layer 25 in the third embodiment.

[0092] The first layer 33 and the third layer 38 may have the same composition, but preferably have different compositions. By providing a difference in fluidity during thermocompression bonding, defects such as filler entrapment at the joint can be more easily prevented. From this perspective, it is preferable that the melt viscosities of the first layer 33 and the third layer 38 at the thermocompression bonding temperature (e.g., 100 to 350°C) be different from each other. From a similar perspective, it is also preferable that the melt viscosities of the first layer 33 and the second layer 35, and the melt viscosities of the second layer 35 and the third layer 38 at the thermocompression bonding temperature (e.g., 100 to 350°C) be different from each other.

[0093] The adhesive film 40 can be obtained, for example, by forming a third layer on the surface of the adhesive film 30 of the third embodiment on the side of the second layer 25. The method for forming the third layer is the same as the method for forming the second layer 16 of the adhesive film 20 of the second embodiment. The order in which the first layer 33, second layer 35, and third layer 38 are formed is not particularly limited.

[0094] Although the adhesive films for a semiconductor of the first to fourth embodiments have been described above, the adhesive film for a semiconductor of the present disclosure is not limited to the above embodiments. For example, the first filler 11 and the second filler 14 in the adhesive film 20 of the second embodiment may be oriented in the same direction. Similarly, the first filler 31 and the second filler 36 in the fourth embodiment may be oriented in the same direction. Furthermore, for example, the adhesive film for a semiconductor may have a multilayer structure of four or more layers.

[0095] <Semiconductor package> Another embodiment of the present disclosure is a semiconductor package comprising: a semiconductor chip having a first connection portion; a base having a second connection portion electrically connected to the first connection portion; and a sealing portion that bonds the semiconductor chip and the base and fills the gap between the semiconductor chip and the base, wherein the sealing portion is formed from the above-mentioned semiconductor adhesive film.

[0096] Fig. 5 is a schematic cross-sectional view showing one embodiment of a semiconductor package according to the present disclosure. The semiconductor package 100 in Fig. 5 includes a semiconductor chip 50 having wiring 51 as a first connection portion, a base 60 having wiring 61 as a second connection portion, connection bumps 70 connecting the wiring 51, 61 of the semiconductor chip 50 and the base 60 to each other, and a sealing portion 80 filling the gap between the semiconductor chip 50 and the base 60. The semiconductor chip 50 and the base 60 are flip-chip connected by the wiring 51, 61 and the connection bumps 70. The wiring 51, 61 and the connection bumps 70 are sealed by the sealing portion 80 and are isolated from the external environment.

[0097] The semiconductor chip 50 is not particularly limited, and may be a semiconductor chip made of an elemental semiconductor made of the same type of element such as silicon or germanium, or a semiconductor chip made of a compound semiconductor such as gallium arsenide or indium phosphide.

[0098] The substrate 60 is not particularly limited as long as it can be used to mount a semiconductor chip, and examples thereof include a semiconductor chip, a semiconductor wafer, and a wiring circuit board.

[0099] Examples of semiconductor chips that can be used as the substrate 60 are the same as the examples of semiconductor chips described above.

[0100] The semiconductor wafer that can be used as the base 60 is not particularly limited, and may be one having a configuration in which a plurality of the semiconductor chips exemplified above are connected together.

[0101] There are no particular restrictions on the wired circuit board that can be used as the base 60, and examples that can be used include a circuit board having wiring (wiring pattern) formed by etching away unnecessary parts of a metal film on the surface of an insulating substrate whose main component is glass epoxy, polyimide, polyester, ceramic, epoxy, bismaleimide triazine, etc.; a circuit board in which wiring is formed on the surface of the insulating substrate by metal plating, etc.; and a circuit board in which wiring is formed by printing a conductive material on the surface of the insulating substrate.

[0102] The wiring 51, 61 and the connection bump 70 may contain gold, silver, copper, solder (the main component may be, for example, tin-silver, tin-lead, tin-bismuth, tin-copper, tin-silver-copper, etc.), nickel, tin, lead, etc. as a main component, or may contain a plurality of metals. Among the above metals, from the viewpoint of obtaining a package with excellent electrical conductivity and thermal conductivity at the connection portion, gold, silver, and copper are preferred, and silver and copper are more preferred. From the viewpoint of obtaining a cost-reduced package, silver, copper, and solder, which are inexpensive materials, are preferred, copper and solder are more preferred, and solder is even more preferred.

[0103] A metal layer containing gold, silver, copper, solder (main components of which may be, for example, tin-silver, tin-lead, tin-bismuth, tin-copper, etc.), tin, nickel, etc. as a main component may be formed, for example, by plating, on the surfaces of the wirings 51, 61 and the connection bumps 70. This metal layer may be composed of only a single component, or may be composed of multiple components. Furthermore, the metal layer may have a structure in which a single layer or multiple metal layers are laminated.

[0104] The sealing portion 80 may be a cured product of the adhesive film (e.g., the adhesive films of the first to fourth embodiments). The sealing portion may include a layer of nanovoid aggregation regions. The nanovoid aggregation regions may be formed near the layer interface of the adhesive film, along the interface. When the sealing portion includes nanovoid aggregation regions, the occurrence of thermal crosstalk is more likely to be suppressed.

[0105] The semiconductor package 100 can be manufactured, for example, by a method including a heat bonding process in which the semiconductor chip 50 and the base 60 are heated and bonded together while being arranged so that their connection portions face each other via an adhesive film.

[0106] Specifically, an adhesive film is first prepared and attached by lamination to the surface of semiconductor chip 50 on which wiring 51 (first connection portion) is formed, to obtain a semiconductor chip with an adhesive film. Next, the obtained semiconductor chip with adhesive film is heated and pressed from the adhesive film side onto the surface of base 60, which is the adherend, on which wiring 61 is formed, via connection bumps, to obtain semiconductor package 100.

[0107] The conditions for lamination and thermocompression bonding are not particularly limited, but nanovoid-collected regions are likely to be formed, for example, by laminating at a temperature of about 80 to 120°C for about 1 to 5 minutes under a pressure of about 0.5 to 2 MPa, and then thermocompressing the semiconductor chip with the adhesive film at 100 to 350°C for about 15 seconds to 1 minute under a pressure of about 50 to 60 MPa. Nanovoid-collected regions are particularly likely to be formed in adhesive films with multilayer structures. This is presumably because, in adhesive films with multilayer structures, macrovoids are likely to be formed near the layer interfaces during lamination, and these macrovoids are diffused into the film as nanovoids by laminating and thermocompressing under the specific conditions described above, forming nanovoid-collected regions.

[0108] Although one embodiment of the semiconductor package of the present disclosure has been described above, the semiconductor package of the present disclosure is not limited to the above embodiment. For example, the semiconductor package may be a stack of multiple semiconductor packages 100 (packages configured with a laminate of semiconductor chips 50 and base bodies 60) described above. In such multi-layer packages, problems such as hot spots and crosstalk are particularly likely to occur, and therefore the adhesive film of the present disclosure is preferably used. [Explanation of symbols]

[0109] 1,11,14,21,31,36...Flat thermally conductive filler, 2,12,15,22,24,32,34,37...Adhesive component, 10,20,30,40...Semiconductor adhesive film, 50...Semiconductor chip, 51...Wiring (first connection portion), 60...Base, 61...Wiring (second connection portion), 80...Sealing portion, 100...Semiconductor package.

Claims

1. An adhesive film for semiconductors, comprising a plate-like thermally conductive filler and a mesogenic compound.

2. 2. The adhesive film for a semiconductor according to claim 1, wherein the planar aspect ratio of the plate-like thermally conductive filler is 1.2 or more.

3. 2. The adhesive film for semiconductor use according to claim 1, wherein the plate-like thermally conductive filler comprises hexagonal boron nitride.

4. The adhesive film for semiconductor use according to claim 1 , which has thermosetting properties.

5. 2. The adhesive film for a semiconductor according to claim 1, which has a multilayer structure, and at least one layer constituting said multilayer structure contains said tabular thermally conductive filler and said mesogenic compound.

6. a first layer containing a first filler and a first mesogenic compound; a second layer containing a second filler and a second mesogenic compound; the first filler and the second filler are flat thermally conductive fillers having a planar aspect ratio of 1.2 or more; 6. An adhesive film for semiconductors according to claim 5, wherein the angle between the direction in which the thermal conductivity of the first layer is highest and the direction in which the thermal conductivity of the second layer is highest among directions parallel to the main surface of the adhesive film is 80 to 100°.

7. A method for producing an adhesive film for semiconductors, comprising applying a composition containing a flat thermally conductive filler and a mesogenic compound onto a substrate to form a layer containing the flat thermally conductive filler and the mesogenic compound.

8. applying a first composition containing a first filler and a first mesogenic compound onto a substrate to form a first layer containing the first filler and the first mesogenic compound; applying a second composition containing a second filler and a second mesogenic compound onto a substrate to form a second layer containing the second filler and the second mesogenic compound; laminating the first layer and the second layer; the first filler and the second filler are flat thermally conductive fillers having a planar aspect ratio of 1.2 or more; The method for producing an adhesive film for semiconductors according to claim 7, wherein the first layer and the second layer are laminated so that the angle between the application direction of the first composition and the application direction of the second composition is 80 to 100°.

9. a semiconductor chip having a first connection portion, a base having a second connection portion electrically connected to the first connection portion, and a sealing portion that bonds the semiconductor chip and the base and fills a gap between the semiconductor chip and the base, A semiconductor package, wherein the sealing portion is formed from the adhesive film for a semiconductor according to any one of claims 1 to 6.

10. The semiconductor package of claim 9 , wherein the encapsulant comprises layered nanovoid aggregate regions.

Images