Paste composition, semiconductor device and method for manufacturing the same, and electronic component and method for manufacturing the same

Abstract

To provide a paste composition and the like having high coatability, capable of achieving, through heating and pressurizing at a low temperature, a bonding that has high adhesive strength and is less likely to cause peeling due to thermal cycling.SOLUTION: A paste composition comprises silver particles A and a binder B, wherein: a content of silver particles A1 having a particle diameter of more than 20 μm in 100 mass% of the silver particles A is 5 mass% or less; a content of the silver particles A in 100 mass% of a total amount of the silver particles A and the binder B is 95 mass% or more; and a rate of change represented by the following formula (1) is 250% or more. (1) Rate of change=(S1-S0) / S0×100(%). [S0 is a crystallite size at Miller index (111) of the silver particles in a dried product of the paste composition. S1 is a crystallite size at Miller index (111) of the silver particles in a processed product obtained by subjecting the dried product of the paste composition to a heat and pressure treatment under a nitrogen atmosphere at 15 MPa and 200°C for 2 minutes.]SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a paste composition, a semiconductor device and a method for manufacturing the same, and an electronic component and a method for manufacturing the same. [Background technology]

[0002] In recent years, there has been active development of power semiconductor devices that use wide bandgap semiconductor elements such as silicon carbide (SiC) and gallium nitride (GaN), which have low power loss. In these power semiconductor devices, the wide bandgap semiconductor elements are bonded to other members, such as a semiconductor support member, by bonding members made of bonding materials. The wide bandgap semiconductor device itself has high heat resistance, allowing it to operate at high temperatures of 250°C or higher with a large current. This characteristic is achieved by adequately dissipating the heat generated by the device during operation. Therefore, there is a demand for bonding materials that have excellent long-term high-temperature resistance in addition to electrical conductivity and heat transfer.

[0003] Sintered materials are increasingly being used as joining materials. Sintered materials are paste compositions containing fine metal particles. These fine metal particles are sintered at temperatures significantly lower than the melting point of the metal itself, and after sintering, they can acquire thermal conductivity and heat resistance equivalent to that of bulk metal.

[0004] Sintered materials are classified into pressureless and pressureless types depending on the joining process. Pressureless types use heat but no pressure during joining, while pressure types use heat and pressure simultaneously during joining. Among these, pressure-type solder joints are used in fields requiring high connection reliability, such as in automobiles (vehicle inverters, etc.) because high connection reliability can be achieved by forming a dense sintered body through pressure during joining. Conventional pressure-type sintering processes generally require heating to high temperatures of 250°C or higher during bonding, but there are concerns that high temperatures can damage surrounding components and that residual stress resulting from thermal expansion can reduce connection reliability. Therefore, there is a demand for pressure-type sintering materials that can be bonded at low temperatures. For example, Patent Document 1 describes a technique in which pressure bonding is performed at a low bonding temperature of 200°C, focusing on the change in crystallite diameter before and after heat treatment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-136580 Summary of the Invention [Means for solving the problem]

[0006] The present disclosure relates to the following [1] to

[11] .

[0007] [1] A composition comprising silver particles (A) and a binder (B), the content of silver particles (A1) having a particle diameter of more than 20 μm is 5% by mass or less in 100% by mass of the silver particles (A), the content of the silver particles (A) is 95% by mass or more in 100% by mass of the total amount of the silver particles (A) and the binder (B), A paste composition having a rate of change represented by the following formula (1) of 250% or more. Rate of change = (S1 - S0) / S0 × 100 (%) (1) [S0 is the crystallite size of the silver particles in the dried paste composition in terms of Miller index (111). S1 is the crystallite size, in Miller index (111), of silver particles in a treated product obtained by subjecting the dried paste composition to a heating and pressurizing treatment at 15 MPa and 200°C for 2 minutes in a nitrogen atmosphere.] [2] The paste composition according to the above [1], wherein the content of silver particles (A2) having a particle diameter of 1.0 to 20 μm in 100% by mass of the silver particles (A) is 50% by mass or less. [3] The paste composition according to the above [1] or [2], wherein the content of silver particles (A3) having a particle diameter of less than 1.0 μm in 100% by mass of the silver particles (A) is 50% by mass or more. [4] The specific surface area of ​​the silver particles (A) is 1.4 m 2 The paste composition according to any one of the above [1] to [3], wherein the viscosity is 1 / g or more. [5] The paste composition according to any one of the above [1] to [4], wherein the binder (B) contains at least one resin selected from the group consisting of thermosetting resins and thermoplastic resins. [6] The paste composition according to any one of the above [1] to [5], wherein the binder (B) has a 5% by mass weight loss temperature of 250°C or higher. [7] A solvent (C) is contained, [6] The paste composition according to any one of the above-mentioned items [1] to [6], wherein the content of the solvent (C) is 10 to 30% by mass relative to 100% by mass of the total amount of the silver particles (A), the binder (B), and the solvent (C). [8] A semiconductor device having a bonding portion formed using the paste composition according to any one of [1] to [7] above. [9] A method for manufacturing a semiconductor device including a semiconductor element and a semiconductor support member, a step of applying the paste composition according to any one of the above [1] to [7] to the semiconductor support member; Mounting the semiconductor element on the paste composition; and a step of bonding the semiconductor element and the semiconductor support member together under heat and pressure, A method for manufacturing a semiconductor device, wherein the heat and pressure bonding is performed under conditions of 180 to 300° C., 1 to 30 MPa, and 0.5 to 10 minutes.

[10] An electronic component having a joint formed from the paste composition according to any one of [1] to [7] above.

[11] A method for producing an electronic component, comprising the step of forming a joint using the paste composition according to any one of [1] to [7] above. DETAILED DESCRIPTION OF THE INVENTION

[0008] The bonding method described in Patent Document 1 has a threshold value of adhesive strength, which is an evaluation standard for sinterability, of 20 MPa, and it is difficult to say that the bonding method has sufficient bonding properties. The present disclosure aims to provide a paste composition that has high coatability and that can achieve high adhesive strength through heating and pressure bonding at low temperatures, with bonding that is less likely to peel due to thermal cycling, as well as a semiconductor device and a method for manufacturing the same that uses the paste composition, and an electronic component and a method for manufacturing the same. The present inventors have focused on the change in crystallite size of silver particles when heated and pressurized, and have found that by selecting silver particles that have good sinterability in the pressurizing step, it is possible to provide a paste composition that has high coatability and is capable of achieving bonding by heating and pressurizing at low temperatures, with high adhesive strength and resistance to peeling due to thermal cycling, as well as a semiconductor device and a method for manufacturing the same that use the paste composition, and an electronic component and a method for manufacturing the same that use the paste composition. According to the present disclosure, it is possible to provide a paste composition that has high coatability and that can achieve high adhesive strength through heating and pressure bonding at low temperatures, and that is less likely to peel due to thermal cycling; as well as a semiconductor device and a method for manufacturing the same that uses the paste composition, and an electronic component and a method for manufacturing the same that uses the paste composition.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. In the following description, the expression "A to B" indicating a numerical range means "A or more and B or less," including the endpoints, and when it is stated that "may be A to B, may be C to D, or may be E to F," the upper and lower limits can be combined arbitrarily. 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.

[0010] [Paste composition] The paste composition of the present disclosure comprises silver particles (A) and a binder (B), wherein the content of silver particles (A1) having a particle size of more than 20 μm is 5% by mass or less relative to 100% by mass of the silver particles (A), the content of the silver particles (A) is 95% by mass or more relative to 100% by mass of the total amount of the silver particles (A) and the binder (B), and the rate of change, as expressed by the following formula (1), is 250% or more. Rate of change = (S1 - S0) / S0 × 100 (%) (1) Here, S0 is the crystallite size of the silver particles in the dried paste composition in terms of Miller index (111). S1 is the crystallite size, in Miller indices (111), of silver particles in a treated product obtained by subjecting the dried paste composition to a heating and pressurizing treatment at 15 MPa and 200° C. for 2 minutes in a nitrogen atmosphere.

[0011] The paste composition of the present disclosure has good coatability, is capable of pressure bonding at low temperatures, and has high adhesive strength. The details of the reason for this are unknown, but it is speculated to be as follows. That is, crystal growth proceeds both within the particles and through sintering between particles. It is believed that the greater the degree of crystal growth, the greater the degree of sintering. Generally, the smaller the crystallite diameter, the easier the crystals grow, but the degree of crystal growth is thought to vary depending on the particle shape, size, and treatment conditions. Silver particles with a large rate of change in crystallite diameter due to treatment simulating a bonding process (heating and pressurizing at 15 MPa and 200°C for 2 minutes in a nitrogen atmosphere) tend to be densely packed under these conditions, resulting in frequent contact, and therefore sintering. That is, if the rate of change {((S1-S0) / S0) × 100} of silver particles (A) is 250% or more, they can exhibit good sinterability during heat and pressure treatment at low temperatures. Furthermore, as described above, silver particles (A) exhibit good sinterability during heat and pressure treatment at low temperatures, resulting in high bonding performance. This allows the content of binder (B) added for bonding to be reduced. That is, the paste composition of the present disclosure contains silver particles (A) in an amount of 95 mass% or more relative to 100 mass% of the total amount of silver particles (A) and binder (B). Because the paste composition of the present disclosure contains a large amount of silver particles (A), it is possible to form a bonded joint that not only has high bonding strength but also has high thermal conductivity and electrical conductivity.

[0012] <Silver particles (A)> The silver particles (A) have a rate of change represented by the following formula (1) of 250% or more. Rate of change = (S1 - S0) / S0 × 100 (%) (1) Here, S0 is the crystallite size, in Miller index (111), of silver particles in the dried paste composition, and S1 is the crystallite size, in Miller index (111), of silver particles in a treated product obtained by subjecting the dried paste composition to a heating and pressurizing treatment at 15 MPa and 200°C for 2 minutes in a nitrogen atmosphere.

[0013] When the rate of change {((S1-S0) / S0) x 100} is 250% or more, a paste composition can be obtained that can achieve high adhesive strength through low-temperature heat and pressure bonding and is less likely to peel due to thermal cycling. There is no particular upper limit to the rate of change {((S1-S0) / S0) x 100}, but it may be 500% or less from the viewpoint of reducing structural changes in the sintered layer due to thermal history after bonding. From this viewpoint, the rate of change {((S1-S0) / S0)×100} may be 255 to 475%, 270 to 450%, 285 to 425%, or 300 to 400%.

[0014] The silver particles (A) may have a crystallite size S0 of 30 to 70 nm. When the crystal size S0 is in this range, crystals tend to grow easily during heating and pressure application, and sintering proceeds easily. From this viewpoint, the crystallite size S0 may be 40 to 60 nm. The crystallite size S0 can be measured as follows. The silver particles (A) in the dried paste composition are compressed into a cake. The cake is applied to a glass plate, and the crystallite size S0 can be calculated from the Miller index (111) plane peak using the Scherrer equation by a focusing method using an X-ray diffractometer with CuKα radiation as the radiation source. Specifically, it can be obtained by the method described in the Examples.

[0015] The silver particles (A) may have a crystallite size S1 of 105 to 420 nm. When the crystallite size S1 is 105 nm or more, structural changes in the sintered layer after bonding can be reduced. When the crystallite size S1 is 420 nm or less, stress generated inside the sintered layer can be reduced. From this viewpoint, the crystallite size S1 may be 120 to 400 nm, 130 to 350 nm, or 140 to 300 nm. The crystallite diameter S1 can be measured as follows. The silver particles (A) in the dried paste composition are compressed to form a cake. A sintered body is obtained by heating the cake to 200°C at a heating rate of 60°C / min under a nitrogen atmosphere while applying a pressure of 15 MPa, heating and pressurizing the cake at 15 MPa and 200°C for 2 minutes, and then cooling it to room temperature (25°C) at a heating rate of 110°C / min. A powder is obtained by pulverizing the sintered body in a mortar. The crystallite diameter S1 can be calculated by applying the powder to a glass plate and using an X-ray diffractometer with a CuKα radiation source by a focusing method using the Scherrer equation for the Miller index (111) plane peak. Specifically, it can be obtained by the method described in the Examples.

[0016] The rate of change {((S1-S0) / S0) × 100} tends to be improved by, for example, setting the particle size of silver particles (A) within the range described below and setting the crystallite size S0 of silver particles (A) within the range described below. The change rate {((S1-S0) / S0) x 100} of silver particles can be easily measured by the above-mentioned method for measuring S0 and S1.

[0017] The silver particles (A) may have an average particle size of 0.62 to 5.0 μm. When the average particle size is 0.62 μm or more, the silver particles come into contact with each other more frequently when pressure is applied, improving sinterability. When the average particle size is 5.0 μm or less, damage to semiconductor elements or substrates when pressure is applied can be reduced. Furthermore, when the average particle size of the silver particles (A) is 0.62 to 5.0 μm, the aforementioned rate of change {((S1-S0) / S0)×100} tends to be high. From this viewpoint, the average particle size of the silver particles (A) may be 0.65 to 3.0 μm, or may be 2.0 μm or less, or may be 1.75 μm or less.

[0018] The shape of the silver particles (A) is not particularly limited and may be, for example, spherical or flaky. The silver particles (A) may be spherical. The silver particles (A) may be primary particles or secondary particles formed by aggregation of primary particles. The silver particles (A) may be hollow or solid, but from the viewpoint of low-temperature sintering, hollow particles are preferred. Here, hollow particles refer to particles having voids inside. When the silver particles (A) are hollow, voids may exist in the center of the silver particles. Furthermore, solid particles refer to particles having substantially no voids inside.

[0019] The specific surface area of ​​silver particles (A) determined by the BET method is 1.4 m 2 / g or more. 2 When the specific surface area is 2.0 m / g or more, the contact between silver particles can be increased, and the proportion of highly active silver atoms on the particle surface can be increased. 2 / g or less. 2 When the content is 1 / g or less, the viscosity of the paste composition can be reduced, and aggregation of silver particles can be reduced. From this viewpoint, the specific surface area is 1.5 to 1.95 m 2 / g. The specific surface area of ​​the silver particles (A) can be measured by the BET single-point method using nitrogen adsorption using a specific surface area measuring device, and specifically, can be measured by the method described in the Examples.

[0020] The content of the silver particles (A) is 95% by mass or more relative to the total mass of the silver particles (A) and the binder (B), which is 100% by mass. When the content is 95% by mass or more, a paste composition can be obtained that can achieve bonding by heat and pressure bonding at low temperatures with high adhesive strength and resistance to peeling due to thermal cycling. The content of the silver particles (A) may be 99% by mass or less relative to 100% by mass of the total amount of the silver particles (A) and the binder (B). When the content is 99% by mass or less, the function of the binder (B) is fully exhibited, thereby making it possible to obtain a paste composition that has high coatability and can reduce structural changes in the sintered layer due to thermal history after bonding. From this viewpoint, the content may be 95 to 99% by mass, 95.5 to 98.7% by mass, or 96 to 98.5% by mass.

[0021] From the viewpoint of sinterability, the silver content of the paste composition relative to the total amount of metals present in the paste composition (100% by mass) may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, and the paste composition may not contain any metals other than silver.

[0022] <<Silver particles (A1)>> In the present disclosure, the content of silver particles (A1) having a particle size of more than 20 μm is 5% by mass or less relative to 100% by mass of silver particles (A). The content of silver particles (A1) may be 0% by mass. When the content is 5% by mass or less, a pressure load can be uniformly applied to the bonding layer without leaving squeegee marks during printing application, and therefore, when the content is 5% by mass or less, a paste composition can be obtained that has high coatability, and that can achieve bonding with high adhesive strength by heat and pressure bonding at low temperatures and is less likely to peel due to thermal cycling. From this viewpoint, the content may be 2.5% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0023] <<Silver particles (A2)>> The content of silver particles (A2) having a particle diameter of 1.0 to 20 μm in 100% by mass of silver particles (A) of the present disclosure may be 50% by mass or less. When the content is 50% by mass or less, a uniform silver sintered layer can be formed. Alternatively, the content may be 5% by mass or more. When the content is 5% by mass or more, the frequency of contact between silver particles can be improved. From this viewpoint, the content may be 8 to 45% by mass, 10 to 40% by mass, or 15 to 36% by mass.

[0024] <<Silver particles (A3)>> The content of silver particles (A3) having a particle size of less than 1.0 μm may be 50% by mass or more relative to 100% by mass of silver particles (A) of the present disclosure. When the content is 50% by mass or more, a uniform silver sintered layer can be formed. The content may be 95% by mass or less. When the content is 95% by mass or less, the frequency of contact between silver particles can be improved. From this viewpoint, the content may be 55 to 92 mass %, 60 to 90 mass %, or 64 to 85 mass %.

[0025] (Method for producing silver particles (A)) The method for producing silver particles (A) includes the steps of adding aqueous ammonia to an aqueous solution containing a silver compound to obtain a silver ammine complex solution, and reducing the silver ammine complex in the silver ammine complex solution obtained in the above step with a reducing compound to obtain a silver particle-containing slurry.

[0026] (Step of obtaining a silver ammine complex solution) In this step, aqueous ammonia is added to an aqueous solution containing a silver compound to obtain a silver ammine complex solution. Examples of the silver compound include silver nitrate, silver chloride, silver acetate, silver oxalate, silver oxide, etc. From the viewpoint of solubility in water, the silver compound may be silver nitrate or silver acetate.

[0027] The amount of ammonia added may be 2 to 50 mol, 5 mol or more, or 10 mol or more per mol of silver in the aqueous solution containing the silver compound. When the amount of ammonia added is within the above range, the average particle size of the primary particles can be set within the above range.

[0028] (Step of obtaining silver particle-containing slurry) In this step, the silver ammine complex in the silver ammine complex solution obtained in the previous step is reduced with a reducing compound to obtain a silver particle-containing slurry. By reducing the silver ammine complex with a reducing compound, the primary particles of the silver particles in the silver ammine complex aggregate to form secondary particles (hollow particles) having a void in the center.

[0029] By appropriately adjusting the amount of silver in the silver ammine complex and the content of the reducing compound, it is possible to control the aggregation of the primary particles and to set the average particle size of the resulting secondary particles within the above-mentioned range.

[0030] The reducing compound is not particularly limited as long as it has the reducing power to reduce the silver ammine complex and precipitate silver. Examples of the reducing compound include hydrazine derivatives. Examples of hydrazine derivatives include hydrazine monohydrate, methylhydrazine, ethylhydrazine, n-propylhydrazine, i-propylhydrazine, n-butylhydrazine, i-butylhydrazine, sec-butylhydrazine, t-butylhydrazine, n-pentylhydrazine, i-pentylhydrazine, neo-pentylhydrazine, t-pentylhydrazine, n-hexylhydrazine, i-hexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n-undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine, phenylhydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol, acetohydrazine, etc. These may be used alone or in combination of two or more.

[0031] The content of the reducing compound may be 0.25 to 20.0 mol per mol of silver in the silver ammine complex, or may be 10.0 mol or less, or may be 5.0 mol or less. When the content of the reducing compound is within the above range, the average particle size of the obtained secondary particles can be within the above range.

[0032] Furthermore, the temperature of the silver ammine complex solution during reduction of the silver ammine complex may be less than 30° C. or may be 0 to 20° C. If the temperature of the silver ammine complex solution is within this range, aggregation of the primary particles can be controlled, and the average particle size of the resulting secondary particles can be within the above-mentioned range.

[0033] <Binder (B)> The binder (B) may contain one or more resins selected from thermosetting resins and thermoplastic resins.

[0034] <<Thermosetting resin>> The thermosetting resin can be any thermosetting resin that is generally used for adhesive applications, without any particular limitations. The thermosetting resin may be a resin that is liquid at room temperature (25°C), or a resin that becomes a paste when diluted with a solvent or the like. The thermosetting resin may include at least one selected from cyanate resins, epoxy resins, acrylic resins, and maleimide resins. These may be used alone, or two or more may be used in combination.

[0035] Cyanate resins are compounds having an -NCO group in the molecule, and the -NCO group reacts when heated. Specific examples include 1,3-dicyanatobenzene, 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-dicyanatonaphthalene, 1,4-dicyanatonaphthalene, 1,6-dicyanatonaphthalene, 1,8-dicyanatonaphthalene, 2,6-dicyanatonaphthalene, 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4'-dicyanatobiphenyl, bis(4-cyanatophenyl)methane, bis(3,5-dimethyl- ... Examples of suitable cyanates include 2,2-bis(4-cyanatophenyl)methane, 2,2-bis(4-cyanatophenyl)propane, 2,2-bis(3,5-dibromo-4-cyanatophenyl)propane, bis(4-cyanatophenyl)ether, bis(4-cyanatophenyl)thioether, bis(4-cyanatophenyl)sulfone, tris(4-cyanatophenyl)phosphite, tris(4-cyanatophenyl)phosphate, and cyanates obtained by reacting novolak resins with cyanogen halides. Prepolymers having triazine rings formed by trimerizing the cyanate groups of these polyfunctional cyanate resins can also be used. These prepolymers can be obtained by polymerizing the polyfunctional cyanate resin monomers listed above using, for example, an acid such as a mineral acid or Lewis acid, a base such as a sodium alcoholate or tertiary amine, or a salt such as sodium carbonate as a catalyst.

[0036] As the curing accelerator for the cyanate resin, generally known ones can be used. Examples include, but are not limited to, organometallic complexes such as zinc octoate, tin octoate, cobalt naphthenate, zinc naphthenate, and iron acetylacetonate; metal salts such as aluminum chloride, tin chloride, and zinc chloride; and amines such as triethylamine and dimethylbenzylamine. These curing accelerators can be used alone or in combination.

[0037] Epoxy resins are compounds containing one or more glycidyl groups in the molecule, and the glycidyl groups react upon heating. The epoxy resins may also be compounds containing two or more glycidyl groups per molecule. Examples include, but are not limited to, bifunctional epoxy compounds such as bisphenol A, bisphenol F, and biphenol, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexanedimethanol, and other alicyclic diols and derivatives thereof, and aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, and decanediol, and derivatives thereof; trifunctional epoxy compounds such as compounds having a trihydroxyphenylmethane skeleton or an aminophenol skeleton; and polyfunctional epoxy compounds such as phenol novolac resins, cresol novolac resins, phenol aralkyl resins, biphenyl aralkyl resins, naphthol aralkyl resins, and polybutadiene. The epoxy resins may be liquid at room temperature (25°C) either alone or as a mixture. A compound containing one glycidyl group per molecule can also be used as a commonly used reactive diluent. Examples of reactive diluents include monofunctional aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, and aliphatic glycidyl ethers.

[0038] Examples of the curing agent for the epoxy resin include aliphatic amines, aromatic amines, dicyandiamide, dihydrazide compounds, acid anhydrides, phenolic resins, and organic peroxides. Examples of the dihydrazide compound include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, and p-oxybenzoic acid dihydrazide. Examples of the acid anhydride include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, dodecenylsuccinic anhydride, a reaction product of maleic anhydride and polybutadiene, and a copolymer of maleic anhydride and styrene. Examples of organic peroxides include hydroperoxides, dialkyl peroxides, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, acetyl peroxide, acyl peroxides, and peroxyketals such as cumene peroxide, 1,1-di-t-butylperoxycyclohexane, and peroxyesters such as t-butyl peroxybenzoate, as well as so-called room temperature curing organic peroxides such as methyl ethyl ketone peroxide.

[0039] Furthermore, a curing accelerator can be blended to accelerate curing. Examples of curing accelerators for epoxy resins include imidazoles, triphenylphosphine or tetraphenylphosphine and their salts, and amine compounds such as diazabicycloundecene and their salts. Examples of curing accelerators include 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-C 11 H 23 The imidazole compound may be an imidazole compound such as an adduct of 2-methylimidazole and 2,4-diamino-6-vinyltriazine, or an imidazole compound having a melting point of 180° C. or higher.

[0040] Examples of acrylic resins include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,2-cyclohexanediol mono(meth)acrylate, 1,3-cyclohexanediol mono(meth)acrylate, 1,4-cyclohexanediol mono(meth)acrylate, 1,2-cyclohexanedimethanol mono(meth)acrylate, 1,3-cyclohexanedimethanol mono(meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 1,2-cyclohexanediethanol mono(meth)acrylate, Examples of the hydroxyl group-containing (meth)acrylate include (meth)acrylates having a hydroxyl group such as methylpropane mono(meth)acrylate, 1,3-cyclohexanediethanol mono(meth)acrylate, 1,4-cyclohexanediethanol mono(meth)acrylate, glycerin mono(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and neopentyl glycol mono(meth)acrylate, as well as (meth)acrylates having a carboxyl group obtained by reacting these hydroxyl group-containing (meth)acrylates with dicarboxylic acid or a derivative thereof. Examples of dicarboxylic acids that can be used herein include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and derivatives thereof.

[0041] Examples of acrylic resins include polyethers, polyesters, polycarbonates, and poly(meth)acrylates having a molecular weight of 100 to 10,000, which have a (meth)acrylic group; (meth)acrylates having a hydroxy group; and (meth)acrylamides having a hydroxy group.

[0042] A maleimide resin is a compound containing one or more maleimide groups per molecule, and the maleimide groups react upon heating. Examples of maleimide resins include bismaleimide resins such as N,N'-(4,4'-diphenylmethane)bismaleimide, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane. The maleimide resin may be a compound obtained by reacting a dimer acid diamine with maleic anhydride; or a compound obtained by reacting a maleimidized amino acid, such as maleimidoacetic acid or maleimidocaproic acid, with a polyol. The maleimidized amino acid may be obtained by reacting maleic anhydride with aminoacetic acid or aminocaproic acid. The polyol may be a polyether polyol, polyester polyol, polycarbonate polyol, or poly(meth)acrylate polyol, and may not contain an aromatic ring.

[0043] <<Thermoplastic resin>> The thermoplastic resin can be any thermoplastic resin commonly used for adhesive applications, without any particular limitations. Examples include acrylic resins, methacrylic resins, vinyl resins, carbonate resins, cellulose, polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. At least one selected from the thermoplastic resins listed above may be used. These may be used alone, or two or more may be used in combination.

[0044] The content of the binder (B) is 5.0% by mass or less relative to the total amount (100% by mass) of the silver particles (A) and the binder (B). When the content is 5.0% by mass or less, the voids in the structure formed by silver sintering can be filled without inhibiting the sintering of the silver particles. The content of the binder (B) may be 0.1% by mass or more relative to 100% by mass of the total amount of the silver particles (A) and the binder (B). When the content is 0.1% by mass or more, the resin fills the voids in the structure formed by silver sintering, thereby reducing stress applied to the sintered layer. From this viewpoint, the content may be 0.1 to 5.0 mass %, 0.5 to 4.8 mass %, 1.0 to 4.5 mass %, or 1.5 to 4.0 mass %.

[0045] <<Physical properties etc.>> The 5% weight loss temperature of the binder (B) may be 250°C or higher. If the temperature is 250°C or higher, thermal decomposition of the resin during bonding can be reduced. There is no particular upper limit to the 5% weight loss temperature of the binder (B), but it may be 450°C or lower from the viewpoints of binder availability, compatibility with solvents, etc. From this viewpoint, the 5% by mass weight loss temperature of the binder (B) may be 250 to 450°C, 300 to 425°C, or 350 to 400°C. The 5% weight loss temperature of the binder (B) can be measured by a thermogravimetric and differential thermal analyzer, specifically by the method described in the examples.

[0046] <Solvent (C)> The paste composition of the present disclosure may further contain a solvent (C) from the viewpoint of workability. Examples of the solvent (C) include butyl carbitol, cellosolve acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, diethylene glycol dimethyl ether, diacetone alcohol, N-methyl-2-pyrrolidone (NMP), dimethylformamide, N,N-dimethylacetamide (DMAc), γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, 3,5-dimethyl-1-adamantanamine (DMA), and terpene ethers such as dihydroterpinyloxyethanol. These may be used alone or in combination of two or more.

[0047] When the paste composition of the present disclosure contains a solvent (C), the content of the solvent (C) in 100% by mass of the paste composition may be 5 to 50% by mass. When the content is 5% by mass or more, good coatability can be achieved. When the content is 50% by mass or less, it is possible to reduce settling of silver particles when the paste composition is left standing, thereby improving the usable time. From this viewpoint, the content may be 10 to 40% by mass, 12 to 30% by mass, or 15 to 25% by mass.

[0048] When the paste composition according to the present disclosure contains a solvent (C), the content of the solvent (C) may be 10 to 30% by mass relative to 100% by mass of the total amount of the silver particles (A), the binder (B), and the solvent (C). When the content is 10% by mass or more, good coatability can be achieved, and when the content is 30% by mass or less, sedimentation of silver particles when the paste composition is left to stand can be reduced, thereby improving the usable time. From this point of view, the content may be 12 to 25% by mass.

[0049] <Other ingredients> In addition to the above components, the paste composition of the present disclosure may contain, as necessary, various additives that are commonly compounded in compositions of this type, such as stress-reducing agents such as rubber and silicone, coupling agents, antifoaming agents, surfactants, colorants such as pigments and dyes, various polymerization inhibitors, antioxidants, solvents, fluxing agents, and other additives. Each of these additives may be used alone or in combination of two or more. The paste composition of the present disclosure may or may not contain a resin containing an aromatic amine skeleton.

[0050] The total content of the silver particles (A), binder (B), and solvent (C) in 100% by mass of the paste composition of the present disclosure may be 80 to 100% by mass, 90 to 99.95% by mass, or 95 to 99.9% by mass. The total content of the silver particles (A) and the binder (B) in the paste composition of the present disclosure, relative to 100% by mass of the solids content, may be 80 to 100% by mass, 90 to 100% by mass, or 95 to 99.9% by mass. Here, the solid content refers to the components remaining after excluding the solvent (C) from the paste composition.

[0051] The paste composition of the present disclosure can be prepared by thoroughly mixing the above-described silver particles (A), binder (B), optional solvent (C), and various additives, followed by further kneading using a disperse mill, kneader, triple-roll mill, or the like, and then degassing.

[0052] <Physical properties of paste composition> (viscosity) From the viewpoint of coatability, the viscosity of the paste composition of the present disclosure may be 1 to 200 Pa·s, 10 to 100 Pa·s, 12 to 50 Pa·s, or 15 to 25 Pa·s. The viscosity is a value measured using an E-type viscometer (3° cone) at 25° C. and a rotation speed of 2.0 rpm. Specifically, it can be measured by the method described in the examples.

[0053] (thixotropy index) The thixotropy index of the paste composition of the present disclosure may be 1 to 20, 2 to 10, or 3.5 to 7, from the viewpoint of coatability. The thixotropy index was measured using an E-type viscometer (3°C) at a temperature of 25°C and a rotation speed of 2.0 rpm (V 2.0 ) and viscosity at 20 rpm (V 20 ) and measure the viscosity ratio (V 2.0 / V 20 Specifically, it can be measured by the method described in the Examples.

[0054] (shear strength) The shear strength of the cured paste composition of the present disclosure may be 80 MPa or more. When the shear strength is 80 MPa or more, bonding can be performed by heating and pressurizing at low temperatures, with high adhesive strength and resistance to peeling due to thermal cycling. From this viewpoint, the shear strength of the cured product of the paste composition may be 85 MPa or more, 90 MPa or more, or 92 MPa or more. The shear strength of the cured paste composition can be measured by applying the paste composition to a copper frame, mounting a backside gold chip with a gold vapor deposition layer on a 2 mm × 2 mm bonding surface, and curing under heat and pressure at 200°C and 15 MPa for 2 minutes, followed by measuring the hot die shear strength at 260°C using a mount strength measuring device. Specifically, the measurement can be performed by the method described in the Examples.

[0055] (volume resistivity) The volume resistivity of the cured paste composition of the present disclosure may be 4.0 μΩ·cm or less, which can reduce resistance heat generation at the joint. From this viewpoint, the volume resistivity of the cured product of the paste composition may be 3.5 μΩ·cm or less, 3.4 μΩ·cm or less, or 3.0 μΩ·cm or less. The volume resistivity of the cured paste composition can be measured by applying the paste composition to a glass substrate to a thickness of 30 μm, drying, and curing at 200° C. and 15 MPa for 2 minutes to obtain a wiring, and measuring the electrical resistivity using a resistivity meter by the four-terminal method. Specifically, the measurement can be performed by the method described in the Examples.

[0056] [Semiconductor device and manufacturing method thereof] The semiconductor device of the present disclosure has a joint formed from the paste composition described above. Because the semiconductor device of the present disclosure has a joint formed from the paste composition described above, it has good heat dissipation properties and connection reliability, and can provide a semiconductor device for an in-vehicle component. The semiconductor device may have a semiconductor element, a substrate, and a joint that joins the semiconductor element and the substrate, The joint is formed from the paste composition described above.

[0057] The method for manufacturing a semiconductor device according to the present disclosure is a method for manufacturing a semiconductor device including a semiconductor element and a semiconductor support member, and includes the steps of applying the paste composition to the semiconductor support member, mounting the semiconductor element on the paste composition, and bonding the semiconductor element and the semiconductor support member together under heat and pressure, wherein the heat and pressure bonding is performed under conditions of 180 to 300°C and 1 to 30 MPa for 0.5 to 10 minutes.

[0058] When the heating temperature in the heat and pressure bonding is 180°C or higher, sintering proceeds sufficiently and the bonding strength of the bonded portion is improved.When the heating temperature is 300°C or lower, thermal degradation of members such as the semiconductor element and the semiconductor support member is reduced. From this viewpoint, the heating temperature may be 180 to 300°C, 185 to 250°C, or 190 to 210°C.

[0059] When the pressure during the heat and pressure bonding is 1 MPa or more, sintering proceeds sufficiently and the bonding strength of the bonded portion is improved.When the pressure is 30 MPa or less, damage to members such as semiconductor elements and semiconductor support members due to pressure is reduced. From this viewpoint, the pressure may be 1 to 30 MPa, 5 to 25 MPa, or 10 to 20 MPa.

[0060] The semiconductor element may be any known semiconductor element, such as a transistor or a diode. Further examples of the semiconductor element include light-emitting elements such as LEDs. The type of light-emitting element is not particularly limited, and examples include light-emitting layers formed on a substrate by MOCVD (metal-organic chemical vapor deposition) or the like using nitride semiconductors such as InN, AlN, GaN, InGaN, AlGaN, and InGaAlN. Examples of semiconductor support members include support members made of materials such as copper, copper-plated copper, PPF (pre-plating lead frame), glass epoxy, and ceramics.

[0061] By using the die attach material of this embodiment, semiconductor elements can be bonded to substrates that are not metal-plated. The semiconductor device thus obtained has improved connection reliability against temperature cycles after mounting compared to conventional devices. Furthermore, because the electrical resistance is sufficiently low and changes little over time, there is little decrease in output power over time even when driven for long periods of time, resulting in a long life.

[0062] [Electronic components and their manufacturing methods] The electronic component of the present disclosure has a joint formed from the paste composition described above. Because the electronic component of the present disclosure has a joint formed from the paste composition described above, it has good heat dissipation properties and connection reliability, and can be used as an electronic component for an in-vehicle component. The electronic component may have an electronic element, a substrate, and a joint that joins the electronic element and the substrate, The joint is formed from the paste composition described above. The method for producing an electronic component according to the present disclosure is a method for producing an electronic component that includes a step of forming a joint using the paste composition described above. [Example]

[0063] Next, the present disclosure will be described in detail by showing examples, but the present disclosure is not limited to these examples.

[0064] The raw materials used were those shown in Table 1 and below.

[0065] (1) Silver particles

[0066] [Table 1]

[0067] (2) Binder (resin) jER1009 (bisphenol A solid epoxy resin, manufactured by Mitsubishi Chemical Corporation, molecular weight: 3800, 5% weight loss temperature: 359°C) JP-100 (epoxidized solid epoxy resin, manufactured by Nippon Soda Co., Ltd., molecular weight: 1300, 5% weight loss temperature: 377°C) (3) Solvent TOE-100 (dihydroterpinyloxyethanol, manufactured by Nippon Terpene Chemical Co., Ltd., molecular weight 198.31) (4) Other ingredients Hardener: Percumyl D (dicumyl peroxide, NOF Corporation, molecular weight 270.37) Fluxing agent: KE-604 (product name "Pine Crystal KE-604", acrylic acid modified rosin hydrogenated, manufactured by Arakawa Chemical Industries, Ltd.)

[0068] [Examples 1 to 7 and Comparative Examples 1 to 10] The components were mixed according to the formulation shown in Table 2 and kneaded with a roll to obtain a paste composition. The paste compositions thus obtained were evaluated as described below, and the results are shown in Table 2.

[0069] [evaluation] (1) Crystallite diameters S0 and S1 and their rate of change {((S1-S0) / S0) × 100} The obtained paste composition was dried at 80°C for 30 minutes to obtain a cake. The obtained cake was applied to a glass plate to a thickness of 200 μm, and the crystallite size S (nm) was calculated using the Scherrer equation for the Miller index (111) plane peak by the focusing method using an X-ray diffractometer (product name: SmartLab SE, manufactured by Rigaku Corporation) with CuKα radiation as the radiation source. The fitting function used was a divided pseudo-Voigt function, the width was FWHD, and the Scherrer constant was 0.94.

[0070] The cake was heated to 200°C at a heating rate of 60°C / min under a nitrogen atmosphere while applying a pressure of 15 MPa. After heating and pressurizing at 15 MPa and 200°C for 2 minutes, the temperature was lowered to room temperature (25°C) at a cooling rate of 110°C / min to obtain a sintered body. The sintered body was pulverized in a mortar to obtain a powder. The powder was applied to a glass plate, and the crystallite size S1 (nm) was calculated using the Scherrer equation for the Miller index (111) plane peak by the focusing method using an X-ray diffractometer (product name: SmartLab SE, manufactured by Rigaku Corporation) with CuKα radiation as the radiation source. The fitting function used was a divided pseudo-Voigt function, the width was FWHD, and the Scherrer constant was 0.94. Furthermore, the rate of change {((S1-S0) / S0) x 100} (%) was calculated from the above S0 and S1.

[0071] (2) Viscosity The viscosity of the obtained paste composition was measured at a temperature of 25°C and a rotation speed of 2.0 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone-plate type rotor: 3°×R14) (3° cone).

[0072] (3) Thixotropy index The viscosity (V) of the obtained paste composition was measured at a temperature of 25°C and a rotation speed of 2.0 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applied cone-plate rotor: 3° × R14). 2.0 ) and viscosity at 20 rpm (V 20 ) were measured. 20 Viscosity V 2.0 Viscosity ratio (V 2.0 / V 20 ) was used as the thixotropy index.

[0073] (4) Volume resistivity The obtained paste composition was applied to a glass substrate (thickness 1 mm) by screen printing to a thickness of 30 μm, dried at 120°C for 10 minutes, then heated to 200°C at a heating rate of 60°C / min, and cured at 200°C and 15 MPa for 2 minutes to obtain wiring. The electrical resistivity of the obtained wiring was measured by the four-terminal method using a resistivity meter (product name "MCP-T600", manufactured by Mitsubishi Chemical Corporation).

[0074] (5) Shear strength The resulting paste composition was applied by stencil printing to a copper frame and dried at 120°C for 10 minutes. After that, a backside gold chip with a gold vapor deposition layer on a 2 mm x 2 mm bonding surface was mounted. The temperature was increased to 200°C at a rate of 60°C / min, and heat-pressure curing was performed at 200°C and 15 MPa for 2 minutes. The hot die shear strength at 260°C was measured using a mount strength measuring device.

[0075] (6) Heat and cold cycle (Manufacturing of Joints) The obtained paste composition was applied to a copper frame by stencil printing and dried at 120°C for 10 minutes. After that, a gold-backed silicon chip with a gold vapor deposition layer on the bonding surface of 5 mm x 5 mm was mounted on it. The temperature was increased to 200°C at a rate of 60°C / min, and the mixture was cured under heat and pressure at 200°C and 15 MPa for 2 minutes to obtain a bonded body.

[0076] (Cold-heat cycle treatment) The resulting 10 bonded bodies were subjected to a thermal cycle treatment, which consisted of holding the body at −55° C. for 30 minutes, then increasing the temperature from −55° C. to 150° C. at a heating rate of 30° C. / min, holding the body at 150° C. for 30 minutes, and then decreasing the temperature at a rate of 30° C. / min. This cycle was repeated 2000 times. The bonded bodies that had undergone the thermal cycle treatment were observed using an ultrasonic microscope (product name "FineSAT II", manufactured by Hitachi Power Solutions Co., Ltd.) to check for peeling of the silicon chip, and evaluated according to the following criteria.

[0077] OK: 0 out of 10 silicone chips peeled off NG: One or more silicon chips peeled off out of 10

[0078] (7) Particle size distribution For each paste composition shown in Table 2, only silver particles, among the constituent components of the paste composition, were blended in the proportions shown in Table 2 to obtain a sample for measuring the particle size distribution of the silver particles. For example, for the paste composition of Example 2, 90 parts by mass of TC-728 and 10 parts by mass of TC-905 were mixed to obtain a measurement sample. The particle size distribution of each measurement sample was measured using a laser diffraction particle size distribution analyzer (product name "SALAD-7500nano", manufactured by Shimadzu Corporation). From the particle size distribution, the average particle diameter (D50) was calculated from the particle size at which the cumulative volume was 50% (50% particle size D50). Furthermore, based on the particle size distribution, the proportions of particles in three ranges of 1.0 μm or less, 1.0 to 20 μm, and over 20 μm were calculated from the frequency of the particle size distribution.

[0079] (8) Specific surface area Samples for measuring the specific surface area of ​​silver particles were prepared by the following procedure: For each paste composition shown in Table 2, only silver particles were blended among the components of the paste composition in the proportions shown in Table 2 to obtain samples for measuring the specific surface area of ​​silver particles. For example, for the paste composition of Example 2, 90 parts by mass of TC-728 and 10 parts by mass of TC-905 were mixed to obtain a measurement sample. Each of the obtained measurement samples was degassed at 60°C for 10 minutes, and then the specific surface area was measured by the BET single-point method using nitrogen adsorption using a specific surface area measuring device (Monosorb, manufactured by Quanta Chrome).

[0080] (9)5% weight loss temperature Each resin (jER-1009 and JP-100) was placed in a thermogravimetric and differential thermal analyzer (product name "TG / DTA6200", manufactured by Hitachi High-Tech Science Corp.) The resin was heated from room temperature (25°C) at a heating rate of 10°C / min, and the temperature at which the weight of the resin had decreased by 5% by mass was defined as the 5% weight loss temperature of the resin.

[0081] [Table 2]

[0082] The paste compositions of the examples have a (111) crystallite size change rate ({((S1-S0) / S0) × 100}) of 250% or more, and the content of silver particles with a particle size of more than 20 μm in 100% by mass of silver particles is 5% by mass or less. Therefore, the paste compositions have good coatability, can be pressure-bonded at low temperatures, and have high adhesive strength. On the other hand, the paste compositions of Comparative Examples 1 to 3 and 5 to 8 had a rate of change {((S1-S0) / S0)×100} of less than 250%, and therefore had poor at least one of the properties of coatability, pressure bonding at low temperatures, and adhesive strength. The paste composition of Comparative Example 4 had a content of silver particles with a particle diameter of more than 20 μm in 100% by mass of silver particles of more than 5% by mass, and therefore had poor properties in at least one of coatability, dispersibility, pressure bonding property at low temperatures, and adhesive strength. The paste compositions of Comparative Examples 9 and 10 had a content of silver particles (A) of less than 95% by mass relative to 100% by mass of the total amount of silver particles (A) and binder (B), and therefore exhibited poor properties in at least one of coatability, dispersibility, pressure bonding property at low temperatures, and adhesive strength.

Claims

1. silver particles (A) and a binder (B), the content of silver particles (A1) having a particle diameter of more than 20 μm is 5% by mass or less based on 100% by mass of the silver particles (A), the content of the silver particles (A) is 95% by mass or more based on 100% by mass of the total amount of the silver particles (A) and the binder (B), A paste composition having a rate of change represented by the following formula (1) of 250% or more. Rate of change = (S1 - S0) / S0 × 100 (%) (1) [S0 is the crystallite size of the silver particles in the dried paste composition in Miller index (111)] S1 is the crystallite size, in Miller indices (111), of silver particles in a treated product obtained by subjecting a dried paste composition to a heating and pressurizing treatment at 15 MPa and 200°C for 2 minutes in a nitrogen atmosphere.]

2. 2. The paste composition according to claim 1, wherein the content of silver particles (A2) having a particle diameter of 1.0 to 20 μm is 50% by mass or less, relative to 100% by mass of the silver particles (A).

3. 3. The paste composition according to claim 1, wherein the content of silver particles (A3) having a particle diameter of less than 1.0 μm in 100% by mass of the silver particles (A) is 50% by mass or more.

4. The specific surface area of ​​the silver particles (A) is 1.4 m ２ The paste composition according to any one of claims 1 to 3, wherein the solubility is 1 / g or more.

5. The paste composition according to any one of claims 1 to 4, wherein the binder (B) comprises at least one resin selected from the group consisting of thermosetting resins and thermoplastic resins.

6. The paste composition according to any one of claims 1 to 5, wherein the binder (B) has a 5% by mass weight loss temperature of 250°C or higher.

7. Contains a solvent (C), 7. The paste composition according to claim 1, wherein a content of the solvent (C) is 10 to 30% by mass, relative to 100% by mass of the total amount of the silver particles (A), the binder (B), and the solvent (C).

8. A semiconductor device having a joint formed from the paste composition according to any one of claims 1 to 7.

9. A method for manufacturing a semiconductor device including a semiconductor element and a semiconductor support member, comprising: A step of applying the paste composition according to any one of claims 1 to 7 to the semiconductor support member; Mounting the semiconductor element on the paste composition; and a step of bonding the semiconductor element and the semiconductor support member together under heat and pressure, The method for manufacturing a semiconductor device, wherein the heat and pressure bonding is performed under conditions of 180 to 300° C. and 1 to 30 MPa for 0.5 to 10 minutes.

10. An electronic component having a joint formed using the paste composition according to any one of claims 1 to 7.

11. A method for producing an electronic component, comprising a step of forming a joint using the paste composition according to any one of claims 1 to 7.

Images