Paste-like composition, highly thermally conductive material, and semiconductor device

Abstract

To provide a pasty composition capable of forming a semiconductor device excellent in thermal conductivity by use in bonding a semiconductor element to a substrate.SOLUTION: The pasty composition contains silver-containing particles and a thermoacid generator represented by general formula (1), [A].[B], where [A] refers to a cationic species and [B] refers to an anionic species.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a paste composition, a highly thermally conductive material, and a semiconductor device. [Background technology]

[0002] A technique for manufacturing a semiconductor device using a composition containing metal particles is known, with the aim of improving the heat dissipation of the semiconductor device. By using metal particles with high thermal conductivity, the thermal conductivity of the cured product can be increased. As a specific example of application to semiconductor devices, techniques are known in which a composition containing metal particles is used to bond / join a semiconductor element to a substrate (support member), as described in the following Patent Documents 1 to 4.

[0003] Patent Document 1 discloses a thermosetting resin composition for semiconductor bonding, which contains a (meth)acrylic acid ester compound of a predetermined structure, a radical initiator, silver fine particles, silver powder, and a solvent, and a semiconductor device in which a semiconductor element and a substrate are bonded with the composition. The document also describes (paragraph 0011) that the composition can improve connection reliability against temperature cycles after mounting.

[0004] Patent Document 2 discloses a resin paste composition containing an imide acrylate compound, a radical initiator, and a filler such as silver powder, and a semiconductor device in which a semiconductor element and a substrate are bonded with the composition. The document states (paragraph 0003) that chip cracks and chip warpage can be suppressed by reducing the stress of the resin paste composition.

[0005] Patent Document 3 discloses a silver paste composition comprising silver particles, a solvent, and an additive, each of which satisfies predetermined physical properties, and a semiconductor device having a structure in which a semiconductor element and a support member for mounting the semiconductor element are bonded via the composition. This document describes an example in which dipropylene glycol methyl ether acetate and isobornylcyclohexanol are used as solvents.

[0006] Patent Document 4 discloses a conductive material containing a curable compound having an unsaturated double bond, a curable compound having an epoxy group, a thermal cationic curing initiator, a thermal anionic curing agent, a compound capable of capturing cations generated from the thermal cationic curing initiator, and conductive particles, and a connection structure in which an electronic component and a circuit board are joined via the conductive material. The document also discloses that the use of the conductive material can suppress the occurrence of voids in the connection structure. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-74132 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-239616 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-225350 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-229314 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the semiconductor devices in which a semiconductor element and a substrate are bonded using the compositions described in Patent Documents 1 to 4 have room for improvement in thermal conductivity. [Means for solving the problem]

[0009] The present inventors have found that good thermal conductivity can be obtained by using a thermal acid generator, and have completed the present invention. That is, the present invention can be shown as follows.

[0010] According to the present invention, (a) silver-containing particles; (b) a thermal acid generator represented by the following general formula (1); A paste-like composition is provided, comprising: [A]·[B]···(1) (In the general formula (1), [A] represents a cation species, and [B] represents an anion species.)

[0011] According to the present invention, A highly thermally conductive material is provided by sintering the paste composition.

[0012] According to the present invention, A substrate; a semiconductor element mounted on the base material via an adhesive layer, The adhesive layer is formed by sintering the paste composition, thereby providing a semiconductor device. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a paste composition that can be used to bond a semiconductor element to a substrate, thereby obtaining a semiconductor device with excellent thermal conductivity. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a semiconductor device. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and their description will be omitted where appropriate. Furthermore, unless otherwise specified, "~" indicates "above" to "below."

[0016] The paste composition of the present embodiment comprises: (a) silver-containing particles; (b) a thermal acid generator.

[0017] [Silver-containing particles (a)] The silver-containing particles (a) can be sintered by an appropriate heat treatment to form a particle-connected structure (sintered structure).

[0018] In particular, when the paste composition contains silver-containing particles, particularly silver particles having a relatively small particle size and a relatively large specific surface area, a sintered structure can be easily formed even with heat treatment at a relatively low temperature (about 180° C.). The preferred particle size will be described later.

[0019] The shape of the silver-containing particles (a) is not particularly limited. A preferred shape is spherical, but non-spherical shapes such as ellipsoidal, flat, plate-like, needle-like, scale-like, aggregated, and polyhedral shapes are also acceptable. The silver-containing particles (a) may contain at least one type of silver-containing particle having any of these shapes.

[0020] In this embodiment, the paste composition preferably contains two or more types of silver-containing particles selected from spherical, scaly, aggregated, and polyhedral particles, more preferably spherical silver-containing particles (a1) and one or more types of silver-containing particles (a2) selected from scaly, aggregated, and polyhedral particles, and particularly preferably spherical silver-containing particles (a1) and scaly silver-containing particles (a2-1). This further improves the contact rate between the silver-containing particles, facilitating the formation of a network after sintering the paste composition, thereby further improving the thermal conductivity and electrical conductivity.

[0021] When the silver-containing particles (a) contain the silver-containing particles (a2), resin cracking in a molded product obtained from the paste composition can be suppressed, and the linear expansion coefficient can be suppressed. In this embodiment, the term "spherical" does not necessarily mean a perfect sphere, but also includes shapes with slight irregularities on the surface. The circularity is, for example, 0.90 or more, preferably 0.92 or more, and more preferably 0.94 or more.

[0022] The surface of the silver-containing particles (a) may be treated with an organic compound such as a carboxylic acid, a saturated fatty acid having 4 to 30 carbon atoms, a monovalent unsaturated fatty acid having 4 to 30 carbon atoms, or a long-chain alkylnitrile.

[0023] Silver-containing particles (a) are usually surface-treated to suppress aggregation, but the present inventors discovered that the surface treatment agent affects the sintering of silver-containing particles. Further investigation revealed that adding a thermal acid generator (b) to surface-treated silver-containing particles (a) results in a highly thermally conductive material with excellent thermal conductivity. Although the mechanism of this effect is unclear, it is believed that the thermal acid generator (b) dissociates into anions and cations upon heating, such as sintering, and the cations react with the surface treatment agent, removing it from the surface of the silver-containing particles, thereby promoting sintering of the silver-containing particles (a).

[0024] The silver-containing particles (a) may be (i) particles consisting essentially of silver alone, or (ii) particles consisting of silver and a component other than silver. In addition, (i) and (ii) may be used in combination as metal-containing particles.

[0025] In this embodiment, it is particularly preferred that the silver-containing particles (a) comprise silver-coated resin particles in which the surfaces of resin particles are coated with silver, thereby enabling the preparation of a paste-like composition that can give a cured product having excellent thermal conductivity and a low storage modulus.

[0026] Silver-coated resin particles have a silver surface and a resin interior, which is thought to give them good thermal conductivity and softness compared to particles made of silver alone. For this reason, it is thought that using silver-coated resin particles makes it easier to design appropriate values ​​for thermal conductivity and storage modulus.

[0027] Generally, increasing the amount of silver-containing particles is considered to increase thermal conductivity. However, since metals are generally "hard," if the amount of silver-containing particles is too large, the elastic modulus after sintering may become too large. When some or all of the silver-containing particles are silver-coated resin particles, it is easy to design a paste-like composition that can produce a cured product with the desired thermal conductivity and storage modulus. In the case of silver-coated resin particles, it is sufficient that at least a portion of the surface of the resin particle is covered with a silver layer, although the entire surface of the resin particle may be covered with silver.

[0028] Specifically, in the silver-coated resin particles, the silver layer covers preferably 50% or more, more preferably 75% or more, and even more preferably 90% or more of the surface of the resin particle, and particularly preferably, in the silver-coated resin particles, the silver layer covers substantially the entire surface of the resin particle. From another viewpoint, when the silver-coated resin particle is cut at a cross section, it is preferable that a silver layer be observed all around the periphery of the cross section.

[0029] From yet another perspective, the mass ratio of resin / silver in the silver-coated resin particles is, for example, 90 / 10 to 10 / 90, preferably 80 / 20 to 20 / 80, and more preferably 70 / 30 to 30 / 70.

[0030] Examples of the "resin" in the silver-coated resin particles include silicone resin, (meth)acrylic resin, phenolic resin, polystyrene resin, melamine resin, polyamide resin, and polytetrafluoroethylene resin. Of course, other resins may also be used. Furthermore, only one type of resin may be used, or two or more types of resins may be used in combination.

[0031] From the viewpoint of elasticity and heat resistance, the resin is preferably a silicone resin or a (meth)acrylic resin. The silicone resin may be particles composed of organopolysiloxane obtained by polymerizing organochlorosilane such as methylchlorosilane, trimethyltrichlorosilane, dimethyldichlorosilane, etc. Alternatively, the silicone resin may have a basic skeleton in which organopolysiloxane is further three-dimensionally crosslinked.

[0032] The (meth)acrylic resin can be a resin obtained by polymerizing a monomer containing a (meth)acrylic acid ester as the main component (50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more). Examples of the (meth)acrylic acid ester include at least one compound selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-propyl (meth)acrylate, chloro-2-hydroxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and isoboronol (meth)acrylate. The monomer components of the acrylic resin may contain a small amount of other monomers. Examples of such other monomer components include styrene-based monomers. For details of silver-coated (meth)acrylic resins, see, for example, JP 2017-126463 A.

[0033] Various functional groups may be introduced into the silicone resin or (meth)acrylic resin. The functional groups that can be introduced are not particularly limited. Examples include epoxy groups, amino groups, methoxy groups, phenyl groups, carboxyl groups, hydroxyl groups, alkyl groups, vinyl groups, and mercapto groups.

[0034] The resin particle portion of the silver-coated resin particles may contain various additive components, such as a low-stress modifier. Examples of the low-stress modifier include liquid synthetic rubbers such as butadiene styrene rubber, butadiene acrylonitrile rubber, polyurethane rubber, polyisoprene rubber, acrylic rubber, fluororubber, liquid organopolysiloxane, and liquid polybutadiene. In particular, when the resin particle portion contains a silicone resin, the inclusion of a low-stress modifier can make the elastic properties of the silver-coated resin particles favorable.

[0035] The shape of the resin particle portion of the silver-coated resin particles is not particularly limited, but is preferably a combination of a spherical shape and an irregular shape other than a spherical shape, such as a flat, plate-like, or needle-like shape.

[0036] The specific gravity of the silver-coated resin particles is not particularly limited, but the lower limit is, for example, 2 or more, preferably 2.5 or more, and more preferably 3 or more. The upper limit of the specific gravity is, for example, 10 or less, preferably 9 or less, and more preferably 8 or less. An appropriate specific gravity is preferable in terms of the dispersibility of the silver-coated resin particles themselves and the uniformity when the silver-coated resin particles are used in combination with other silver-containing particles.

[0037] When silver-coated resin particles are used, the proportion of the silver-coated resin particles in the entire silver-containing particles (a) is preferably 1 to 50 mass%, more preferably 3 to 45 mass%, and even more preferably 5 to 40 mass%. By appropriately adjusting this proportion, it is possible to further improve heat dissipation while suppressing a decrease in adhesive strength due to heat cycles.

[0038] Incidentally, when the proportion of silver-coated resin particles in the entire silver-containing particles (a) is not 100% by mass, the silver-containing particles other than the silver-coated resin particles are, for example, particles consisting essentially of silver only.

[0039] Median diameter D of silver-containing particles (a) 50 is, for example, 0.01 to 50 μm, preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm. 50By setting the appropriate value, it is easy to balance thermal conductivity, sinterability, resistance to heat cycles, etc. Also, by setting the D50 to an appropriate value, it may be possible to improve the workability of application / adhesion. The particle size distribution of the silver-containing particles (horizontal axis: particle diameter, vertical axis: frequency) may be unimodal or multimodal.

[0040] From the viewpoint of the effects of the present invention, it is preferred that the silver-containing particles (a) contain spherical silver-containing particles (a1) and scaly silver-containing particles (a2-1). It is more preferred that these silver-containing particles are silver particles consisting essentially of silver.

[0041] Median diameter D of spherical silver-containing particles (a1) 50 is, for example, 0.1 to 20 μm, preferably 0.5 to 10 μm, and more preferably 0.5 to 5.0 μm. The specific surface area of ​​the spherical silver-containing particles (a1) is, for example, 0.1 to 2.5 m 2 / g, preferably 0.5 to 2.3 m 2 / g, more preferably 0.8 to 2.0 m 2 / g. The tap density of the spherical silver-containing particles (a1) is, for example, 1.5 to 6.0 g / cm 3 , preferably 2.5 to 5.8 g / cm 3 , more preferably 4.5 to 5.5 g / cm 3 is. The circularity of the spherical silver-containing particles (a1) is, for example, 0.90 or more, preferably 0.92 or more, and more preferably 0.94 or more. By satisfying these properties, an excellent balance of thermal conductivity, sinterability, resistance to heat cycles, and the like is achieved.

[0042] Median diameter D of scaly silver-containing particles (a2-1) 50 is, for example, 0.1 to 20 μm, preferably 1.0 to 15 μm, and more preferably 2.0 to 10 μm. The specific surface area of ​​the scaly silver-containing particles (a2-1) is, for example, 0.1 to 2.5 m 2 / g, preferably 0.2 to 2.0 m 2 / g, more preferably 0.25 to 1.2 m 2 / g. The tap density of the scaly silver-containing particles (a2-1) is, for example, 1.5 to 6.0 g / cm 3 , preferably 2.5 to 5.9 g / cm 3 , more preferably 4.0 to 5.8 g / cm 3 is. By satisfying these properties, an excellent balance of thermal conductivity, sinterability, resistance to heat cycles, and the like is achieved.

[0043] In this embodiment, by combining spherical silver-containing particles (a1) that satisfy at least one of the above properties with scale-like silver-containing particles (a2-1) that satisfy at least one of the above properties, thermal conductivity and electrical conductivity are particularly improved.

[0044] The ratio (a1 / a2-1) of the content of the spherical silver-containing particles (a1) to the content of the scaly silver-containing particles (a2-1) can be set to preferably 0.1 or more and 10 or less, more preferably 0.3 or more and 5 or less, and particularly preferably 0.5 or more and 3 or less. This particularly improves the contact rate between the silver-containing particles, and therefore a network is easily formed after sintering of the paste-like polymerizable composition, resulting in particularly improved thermal conductivity and electrical conductivity.

[0045] Median diameter D of scaly silver-containing particles (a2-1) 50 The median diameter D of the spherical silver-containing particles (a1) 50 The ratio (a1 / a2-1) is preferably 0.01 or more and 0.8 or less, and more preferably 0.05 or more and 0.6 or less. This allows the spherical silver-containing particles to efficiently fill the gaps between the scaly silver-containing particles, particularly improving the contact rate between the silver-containing particles, and therefore, after sintering the paste-like polymerizable composition, a network is easily formed, resulting in particularly improved thermal conductivity and electrical conductivity.

[0046] The ratio (a1 / a2-1) of the tap density of the spherical silver-containing particles b1 to the tap density of the scaly silver-containing particles (a2-1) is preferably 0.5 or more and 2.0 or less, more preferably 0.7 or more and 1.2 or less. This improves the packing rate of the silver-containing particles and particularly improves the contact rate between the silver-containing particles, so that a network is easily formed after sintering of the paste-like polymerizable composition, resulting in particularly improved thermal conductivity and electrical conductivity.

[0047] Median diameter D of silver-coated resin particles 50 The thickness is, for example, 5.0 to 25 μm, preferably 7.0 to 20 μm, and more preferably 8.0 to 15 μm, which can further improve the thermal conductivity.

[0048] Median diameter D of silver-containing particles (a) 50 can be determined by particle image measurement using, for example, a flow particle image analyzer FPIA (registered trademark)-3000 manufactured by Sysmex Corporation. More specifically, the particle size of the silver-containing particles (a) can be determined by measuring the volume-based median diameter in a wet state using this device.

[0049] The proportion of the silver-containing particles (a) in the entire paste-like composition is, for example, 1 to 98 mass%, preferably 30 to 95 mass%, and more preferably 50 to 90 mass%. By setting the proportion of the metal-containing particles to 1 mass% or more, thermal conductivity is easily increased. By setting the proportion of the silver-containing particles (a) to 98 mass% or less, workability in application / adhesion can be improved.

[0050] Among the silver-containing particles (a), particles consisting essentially of silver are available from, for example, DOWA Hitec Co., Ltd. and Fukuda Metal Foil & Powder Co., Ltd. Silver-coated resin particles are available from, for example, Mitsubishi Materials Corporation, Sekisui Chemical Co., Ltd. and Sanno Co., Ltd.

[0051] [Thermal acid generator (b)] The thermal acid generator (b) is represented by the following general formula (1): [A]·[B]···(1) In the general formula (1), [A] represents a cationic species and [B] represents an anionic species.

[0052] The cation species may be any known cation species as long as it can exert the effects of the present invention, but is preferably a sulfonium cation or an ammonium cation. In view of the effects of the present invention, the cationic species is more preferably selected from the cationic species represented by the following formulas (a1) to (a6).

[0053] [ka]

[0054] The anion species can be any known anion species as long as it can exert the effects of the present invention. From the viewpoint of the effects of the present invention, however, it is preferably selected from anions (b1) to (b4) represented by the following formulas.

[0055] [ka]

[0056] (b2) PF6 - , (b3) CF3SO3 - , (b4) SbF6 - In this embodiment, it is more preferable to use the anion (b1).

[0057] The thermal acid generator (b) preferably has an exothermic peak in a temperature range of 250° C. or less, preferably 230° C. or less, and more preferably 210° C. or less, in a DSC curve obtained under the following conditions. (Test conditions) A composition obtained by mixing 68.0 parts by mass of an epoxy resin, 27.0 parts by mass of a phenolic resin, and 5.0 parts by mass of a thermal acid generator (b) is heated from 30°C to 300°C at a heating rate of 10°C / min using a differential scanning calorimeter to obtain a DSC curve.

[0058] Since the thermal acid generator (b) has an exothermic peak in the above temperature range, it acts on the surfaces of the silver-containing particles (a) during the heating step in sintering, and if the silver-containing particles (a) have been surface-treated, it acts on the surface treatment agent as described above, thereby making it possible to obtain a highly thermally conductive material with even better thermal conductivity.

[0059] From the viewpoint of the effects of the present invention, the thermal acid generator (b) can be contained in an amount of 0.01 parts by mass or more and 1.0 parts by mass or less, preferably 0.05 parts by mass or more and 0.9 parts by mass or less, and more preferably 0.07 parts by mass or more and 0.8 parts by mass or less, per 100 parts by mass of the paste-like composition.

[0060] <Paste-like composition> The paste composition of the present embodiment can be used as a sintering type paste composition, a binder type paste composition, or a half-sintering type paste composition.

[0061] A sintering-type paste composition is a composition in the form of silver-containing particles (a) dispersed in a volatile organic solvent (dispersion medium), and the dispersion medium volatilizes upon heat treatment, causing the silver-containing particles (a) to sinter, thereby ensuring conductivity and enabling the composition to exhibit electrical conductivity and thermal conductivity. That is, the sintering type paste composition contains silver-containing particles (a), a thermal acid generator (b), and an organic solvent (c).

[0062] The binder-type paste composition is a composition in the form of silver-containing particles (a) dispersed in a liquid thermosetting resin, and when the resin is cured by heating, the silver-containing particles (a) are compressed and bonded together, thereby exhibiting electrical conductivity and thermal conductivity. That is, the binder-type paste composition contains silver-containing particles (a), a thermal acid generator (b), and a thermosetting resin (d), and may further contain a curing agent (e), a curing accelerator (f), a radical initiator (g), etc.

[0063] The half-sintering type paste composition is used to sinter and compress the silver-containing particles (a) described above. That is, the half-sintering type paste composition contains the silver-containing particles (a), a thermal acid generator (b), an organic solvent (c), and a thermosetting resin (d), and may further contain a curing agent (e), a curing accelerator (f), a radical initiator (g), and the like. Any type of paste composition may contain other components such as a silane coupling agent and a plasticizer.

[0064] [Organic solvent (c)] Examples of the organic solvent (c) include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl methoxybutanol, α-terpineol, β-terpineol, hexylene glycol, benzyl alcohol, 2-phenylethyl alcohol, isopalmityl alcohol, isostearyl alcohol, lauryl alcohol, ethylene glycol, propylene glycol, butylpropylene triglyceride, and glycerin; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2-octanone, isophorone (3,5,5-trimethyl-2-cyclohexen-1-one), and diisobutyl ketone (2,6-dimethyl-4-heptanone); Esters such as ethyl acetate, butyl acetate, diethyl phthalate, dibutyl phthalate, acetoxyethane, methyl butyrate, methyl hexanoate, methyl octanoate, methyl decanoate, methyl cellosolve acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 1,2-diacetoxyethane, tributyl phosphate, tricresyl phosphate, and tripentyl phosphate; ethers such as tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, ethoxyethyl ether, 1,2-bis(2-diethoxy)ethane, and 1,2-bis(2-methoxyethoxy)ethane; Ester ethers such as 2-(2-butoxyethoxy)ethane acetic acid; Ether alcohols such as 2-(2-methoxyethoxy)ethanol; Hydrocarbons such as toluene, xylene, n-paraffin, isoparaffin, dodecylbenzene, turpentine, kerosene, and diesel; nitriles such as acetonitrile or propionitrile; Amides such as acetamide and N,N-dimethylformamide; Silicone oils such as low molecular weight volatile silicone oils and volatile organic modified silicone oils; Monofunctional (meth)acrylic compounds and the like can be given. When the organic solvent (c) is used, only one type of solvent may be used, or two or more types of solvents may be used in combination.

[0065] When organic solvent (c) is used, its amount is not particularly limited. The amount used may be adjusted appropriately based on the desired fluidity, etc. As an example, organic solvent (c) is used in an amount such that the non-volatile component concentration of the paste-like composition becomes 50 to 95% by mass.

[0066] [Thermosetting resin (d)] The thermosetting resin (d) usually contains a group that polymerizes / crosslinks when acted upon by an active chemical species such as a radical, and / or a chemical structure that reacts with the curing agent (e) described below. The thermosetting resin (d) contains, for example, one or more of an epoxy group, an oxetanyl group, a group containing an ethylenic carbon-carbon double bond, a hydroxy group, an isocyanate group, a maleimide structure, etc. A preferred example of the thermosetting resin (d) is an epoxy resin. The epoxy resin may be a compound having only one epoxy group in one molecule, or may be a compound having two or more epoxy groups in one molecule.

[0067] Examples of epoxy resins include bifunctional or crystalline epoxy resins such as biphenyl-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, stilbene-type epoxy resins, and hydroquinone-type epoxy resins; novolac-type epoxy resins such as cresol novolac-type epoxy resins, phenol novolac-type epoxy resins, and naphthol novolac-type epoxy resins; phenol aralkyl-type epoxy resins such as phenylene-skeleton-containing phenol aralkyl-type epoxy resins, biphenylene-skeleton-containing phenol aralkyl-type epoxy resins, and phenylene-skeleton-containing naphthol aralkyl-type epoxy resins; trifunctional epoxy resins such as triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins and terpene-modified phenol-type epoxy resins; and heterocycle-containing epoxy resins such as triazine-nucleus-containing epoxy resins.

[0068] Furthermore, the epoxy group-containing compound may also include monofunctional epoxy group-containing compounds such as 4-tert-butylphenyl glycidyl ether, m,p-cresyl glycidyl ether, phenyl glycidyl ether, and cresyl glycidyl ether. The paste-like composition of the present embodiment may contain only one type of thermosetting component, or may contain two or more types.

[0069] The thermosetting resin (d) is preferably an epoxy resin, such as bisphenol A epoxy resin or bisphenol F epoxy resin. The amount of the thermosetting resin (d) in the paste composition of this embodiment is, for example, 20 to 80 mass %, and preferably 40 to 60 mass %, of the total nonvolatile components.

[0070] [Hardening agent (e)] The curing agent (e) may be one having a reactive group that reacts with the thermosetting resin (d). For example, the curing agent (e) contains a reactive group that reacts with a functional group, such as an epoxy group, a maleimide group, or a hydroxy group, contained in the thermosetting resin (d).

[0071] The curing agent (e) preferably comprises a phenolic curing agent and / or an imidazole curing agent, which are particularly preferred when the thermosetting component contains epoxy groups. The phenolic curing agent may be a low molecular weight compound or a high molecular weight compound (ie, a phenolic resin).

[0072] Examples of phenolic curing agents that are low molecular weight compounds include bisphenol compounds (phenolic resins having a bisphenol F skeleton) such as bisphenol A and bisphenol F (dihydroxydiphenylmethane); and compounds having a biphenylene skeleton such as 4,4'-biphenol.

[0073] Specific examples of the phenolic resin include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, bisphenol novolac resin, and phenol-biphenyl novolac resin; polyvinylphenol; multifunctional phenolic resins such as triphenylmethane-type phenolic resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; and phenol aralkyl-type phenolic resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene and / or biphenylene skeleton. When the curing agent (e) is used, only one type may be used, or two or more types may be used in combination.

[0074] When the paste composition of this embodiment contains the curing agent (e), the amount thereof is, for example, 10 to 120 parts by mass, preferably 30 to 80 parts by mass, relative to 100 parts by mass of the thermosetting resin (d).

[0075] (Curing accelerator (f)) The curing accelerator (f) typically accelerates the reaction between the thermosetting resin (d) and the curing agent (e).

[0076] Specific examples of the curing accelerator (f) include phosphorus atom-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds; amidines and tertiary amines such as dicyandiamide, 1,8-diazabicyclo[5.4.0]undecene-7, and benzyldimethylamine; and nitrogen atom-containing compounds such as quaternary ammonium salts of the above amidines or the above tertiary amines. When the curing accelerator (f) is used, one type may be used alone, or two or more types may be used in combination.

[0077] When the paste-like composition of this embodiment contains the curing accelerator (f), the amount thereof is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the thermosetting resin (d).

[0078] [Radical initiator (g)] The radical initiator (g) may, for example, prevent insufficient curing, allow the curing reaction to proceed sufficiently at a relatively low temperature (e.g., 180°C), or further improve adhesive strength. Examples of the radical initiator (g) include peroxides and azo compounds.

[0079] Examples of peroxides include organic peroxides such as diacyl peroxides, dialkyl peroxides, and peroxyketals. More specifically, examples thereof include ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane and 2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane; Hydroperoxides such as p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide;

[0080] Dialkyl peroxides such as di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and di-t-butyl peroxide; Diacyl peroxides such as dibenzoyl peroxide and di(4-methylbenzoyl) peroxide; Peroxydicarbonates such as di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate; Examples include peroxyesters such as 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexyl peroxybenzoate, t-butyl peroxybenzoate, and t-butylperoxy 2-ethylhexanoate.

[0081] Examples of the azo compound include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile). When the radical initiator (g) is used, one type may be used alone, or two or more types may be used in combination.

[0082] When the paste composition of this embodiment contains the radical initiator (g), the amount thereof is, for example, 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the thermosetting resin (d).

[0083] (Silane coupling agent) The paste composition of the present embodiment may further contain a silane coupling agent, which can further improve the adhesive strength.

[0084] Examples of the silane coupling agent include known silane coupling agents, specifically vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Epoxy silanes such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; styrylsilanes such as p-styryltrimethoxysilane; Methacrylsilanes such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; Acrylic silanes such as 3-(trimethoxysilyl)propyl methacrylate and 3-acryloxypropyltrimethoxysilane; aminosilanes such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; Isocyanurate silane; Alkylsilanes; ureidosilanes such as 3-ureidopropyltrialkoxysilane; mercaptosilanes such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; Examples include isocyanate silanes such as 3-isocyanatepropyltriethoxysilane. When a silane coupling agent is used, only one type may be used, or two or more types may be used in combination.

[0085] When the paste composition of this embodiment contains a silane coupling agent, the amount thereof is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the thermosetting resin (d).

[0086] (plasticizer) The paste composition of the present embodiment may contain a plasticizer. The plasticizer makes it easier to design a low storage modulus, and further makes it easier to prevent a decrease in adhesive strength due to heat cycles.

[0087] Specific examples of the plasticizer include polyester compounds, silicone compounds such as silicone oil and silicone rubber, polybutadiene compounds such as polybutadiene maleic anhydride adducts, and acrylonitrile butadiene copolymer compounds. When a plasticizer is used, only one type may be used, or two or more types may be used in combination.

[0088] When the paste composition of this embodiment contains a plasticizer, the amount thereof is, for example, 5 to 50 parts by mass, and preferably 10 to 30 parts by mass, relative to 100 parts by mass of the thermosetting resin (d).

[0089] (Properties of the composition) The paste composition of the present embodiment is preferably in a paste form at 20° C. That is, the paste composition of the present embodiment can be applied to a substrate or the like in the form of a paste, preferably at 20° C. This allows the paste composition of the present embodiment to be preferably used as an adhesive for semiconductor elements, or the like. Of course, depending on the process to be applied, the paste composition of the present embodiment may be in the form of a varnish having a relatively low viscosity. The paste composition of the present embodiment can be obtained by mixing the above components by a conventionally known method.

[0090] <High thermal conductivity material> A highly thermally conductive material can be obtained by sintering the paste composition of this embodiment. By changing the shape of the highly thermally conductive material, it can be applied to a variety of parts in the automotive and electrical fields that require heat dissipation.

[0091] <Semiconductor device> A semiconductor device can be manufactured using the paste composition of this embodiment. For example, a semiconductor device can be manufactured by using the paste composition of this embodiment as an "adhesive" between a substrate and a semiconductor element.

[0092] In other words, the semiconductor device of this embodiment includes, for example, a substrate and a semiconductor element mounted on the substrate via an adhesive layer obtained by sintering the above-mentioned paste composition by heat treatment. In the semiconductor device of this embodiment, the adhesiveness of the adhesive layer is not easily reduced even by heat cycles, which means that the reliability of the semiconductor device of this embodiment is high.

[0093] Examples of semiconductor elements include ICs, LSIs, power semiconductor elements (power semiconductors), and various other elements. Examples of substrates include various semiconductor wafers, lead frames, BGA substrates, mounting substrates, heat spreaders, and heat sinks.

[0094] An example of a semiconductor device will now be described with reference to the drawings: Fig. 1 is a cross-sectional view showing an example of a semiconductor device.

[0095] The semiconductor device 100 includes a substrate 30 and a semiconductor element 20 mounted on the substrate 30 via an adhesive layer 10 (die attach material) that is a heat-treated paste composition.

[0096] The semiconductor element 20 and the substrate 30 are electrically connected via, for example, bonding wires 40. The semiconductor element 20 is sealed with, for example, sealing resin 50.

[0097] The thickness of the adhesive layer 10 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, which improves the stress absorption ability of the paste composition and improves the heat cycle resistance. The thickness of the adhesive layer 10 is, for example, 100 μm or less, preferably 50 μm or less.

[0098] 1, the substrate 30 is, for example, a lead frame. In this case, the semiconductor element 20 is mounted on a die pad 32 or the substrate 30 via an adhesive layer 10. The semiconductor element 20 is electrically connected to outer leads 34 (substrate 30) via bonding wires 40, for example. The substrate 30, which is a lead frame, is made of, for example, a 42 alloy, a Cu frame, or the like.

[0099] The substrate 30 may be an organic substrate or a ceramic substrate. Examples of organic substrates include those made of epoxy resin, cyanate resin, maleimide resin, and the like. The surface of the substrate 30 may be coated with a metal such as silver or gold, which improves the adhesion between the adhesive layer 10 and the substrate 30.

[0100] FIG. 2 is a cross-sectional view showing an example of a semiconductor device 100 different from that shown in FIG. 2, the substrate 30 is, for example, an interposer. A plurality of solder balls 52, for example, are formed on the surface of the substrate 30, which is an interposer, opposite to the surface on which the semiconductor element 20 is mounted. In this case, the semiconductor device 100 is connected to another wiring board via the solder balls 52. An example of a method for manufacturing a semiconductor device will be described.

[0101] First, the paste composition is applied onto the substrate 30, and then the semiconductor element 20 is placed thereon. That is, the substrate 30, the paste composition, and the semiconductor element 20 are layered in this order. The method for applying the paste composition is not particularly limited, and specific examples include dispensing, printing, and ink-jet methods.

[0102] Next, the paste-like composition is thermally cured. The thermal curing is preferably performed by pre-curing and post-curing. By thermal curing, the paste-like composition becomes a heat-treated body (cured product). By thermal curing (heat treatment), the metal-containing particles in the paste-like composition aggregate, and a structure in which the interfaces between multiple metal-containing particles disappear is formed in the adhesive layer 10. This bonds the substrate 30 and the semiconductor element 20 via the adhesive layer 10. Next, the semiconductor element 20 and the substrate 30 are electrically connected using bonding wires 40. Next, the semiconductor element 20 is encapsulated with an encapsulating resin 50. In this manner, a semiconductor device can be manufactured.

[0103] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0104] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The components used in the examples are listed below.

[0105] (thermosetting component) Epoxy resin 1: Bisphenol F type epoxy resin (Nippon Kayaku Co., Ltd., RE-303S) Acrylic monomer 1: Ethylene glycol dimethacrylate (Kyoeisha Chemical Co., Ltd., Light Ester EG)

[0106] (hardening agent) Curing agent 1: Phenolic resin with a bisphenol F skeleton (solid at room temperature of 25°C, manufactured by DIC Corporation, DIC-BPF)

[0107] (curing accelerator) Imidazole catalyst 1: 2-phenyl-1H-imidazole-4,5-dimethanol (Shikoku Chemicals Corporation, 2PHZ-PW)

[0108] (Radical polymerization initiator) Radical polymerization initiator 1: Dicumyl peroxide (Perkadox BC, manufactured by Kayaku Akzo Co., Ltd.)

[0109] (thermal acid generator) Thermal acid generator 1: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0110] Thermal acid generator 2: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0111] Thermal acid generator 3: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0112] Thermal acid generator 4: A thermal acid generator represented by the following formula (manufactured by Asahi Glass Co., Ltd.) [ka]

[0113] Thermal acid generator 5: a thermal acid generator represented by the following formula (manufactured by Kusumoto Chemicals Co., Ltd.) [ka]

[0114] Thermal acid generator 6: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0115] Thermal acid generator 7: a thermal acid generator represented by the following formula (manufactured by Kusumoto Chemicals Co., Ltd.) Quaternary ammonium salt CF3SO3 -

[0116] Thermal acid generator 8: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0117] Thermal acid generator 9: a thermal acid generator represented by the following formula (manufactured by Sanshin Chemical Industry Co., Ltd.) [ka]

[0118] (Silver-containing particles) Silver filler 1: DOWA Electronics, AG-DSB-114, spherical, D 50 :0.7μm, specific surface area: 1.05m 2 / g, tap density 5.25g / cm 3 Circularity: 0.953 Silver filler 2: Fukuda Metal Foil and Powder Co., Ltd., HKD-12, flake-shaped, median diameter D 50 :7.6μm, specific surface area: 0.315m 2 / g, tap density: 5.5g / cm 3

[0119] (solvent) Solvent 1: Tripropylene glycol mono-n-butyl ether (BFTG, manufactured by Nippon Nyukazai Co., Ltd., boiling point 274°C)

[0120] [Examples 1 to 14, Comparative Example 1] The raw material components were uniformly dispersed and kneaded using a three-roll mill according to the blending amounts shown in Table 1. After kneading, the mixture was degassed under reduced pressure at room temperature for 15 minutes to obtain a paste-like polymerizable composition.

[0121] (volume resistivity) The paste-like composition was applied to a glass plate, heated from 30°C to 200°C over 60 minutes in a nitrogen atmosphere, and then heat-treated at 200°C for 120 minutes. This resulted in a heat-treated paste-like polymerizable composition (cured product) with a thickness of 0.05 mm. The surface resistance of the heat-treated product was measured using a milliohmmeter (manufactured by HIOKI Corporation) using a DC four-electrode method with electrodes spaced 40 mm apart.

[0122] [Table 1]

[0123] From the results shown in Table 1, it was confirmed that the cured products obtained from the paste compositions containing the specified thermal acid generators had low volume resistivity and excellent thermal conductivity. [Explanation of symbols]

[0124] 100 Semiconductor device 10 Adhesive layer 20 Semiconductor elements 30 Base material 32 die pad 34 outer lead 40 Bonding Wire 50 Sealing resin 52 solder balls

Claims

1. A paste-like composition for use in sintering to form a particle-connected structure, comprising: (a) silver-containing particles; (b) a thermal acid generator represented by the following general formula (1); Including, the silver-containing particles (a) comprise one or more types selected from the group consisting of (i) particles consisting essentially of silver and (ii) particles consisting of silver and a component other than silver, The (ii) particles composed of silver and a component other than silver include silver-coated resin particles in which the surfaces of resin particles are coated with silver. [A]・[B] ...(1) (In general formula (1), [A] represents a cation species, and [B] represents an anion species, and the anion species is selected from the following anions (b1) to (b4).) 【Chemistry 1】 (b2) PF ６ － 、 (A3) CF ３ SO ３ － 、 (b4) SbF ６ －

2. The paste-like composition according to claim 1 , wherein the cationic species is a sulfonium cation or an ammonium cation.

3. 3. The paste-like composition according to claim 1, wherein in the thermal acid generator (b) represented by the general formula (1), [B] is an anion (b1).

4. 4. The paste-like composition according to claim 1, wherein the thermal acid generator (b) has an exothermic peak in a temperature range of 250° C. or less in a DSC curve obtained under the following conditions: (Test conditions) A composition obtained by mixing 68.0 parts by mass of an epoxy resin, 27.0 parts by mass of a phenolic resin, and 5.0 parts by mass of a thermal acid generator (b) was heated from 30°C to 300°C at a heating rate of 10°C / min using a differential scanning calorimeter to obtain a DSC curve.

5. 5. The paste-like composition according to claim 1, wherein the amount of the thermal acid generator (b) relative to 100 parts by mass of the paste-like composition is 0.01 parts by mass or more and 1.0 parts by mass or less.

6. The paste-like composition according to any one of claims 1 to 5, further comprising an organic solvent (c).

7. The paste-like composition according to any one of claims 1 to 5, further comprising an organic solvent (c) and a thermosetting resin (d).

8. The paste-like composition according to claim 7 , wherein the thermosetting resin (d) includes an epoxy resin.

9. The paste-like composition according to claim 8, further comprising a hardening agent (e).

10. The paste-like composition according to any one of claims 1 to 5, further comprising a thermosetting resin (d).

11. The paste-like composition according to claim 10 , wherein the thermosetting resin (d) comprises an epoxy resin.

12. The paste-like composition according to claim 10 or 11, further comprising a hardening agent (e).

13. A highly thermally conductive material obtained by sintering the paste composition according to any one of claims 1 to 12.

14. A substrate; a semiconductor element mounted on the base material via an adhesive layer, A semiconductor device, wherein the adhesive layer is formed by sintering the paste composition according to any one of claims 1 to 12.

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