Copper paste for bonding, method for manufacturing a bonded body, and bonded body

Abstract

A copper paste for joining, containing: copper particles; a polycarboxylic acid having a melting point of no more than 120°C; and a carrier fluid. A method for manufacturing a joined body, comprising: a first step in which a laminate is prepared that has a first member, the copper paste for joining and a second member, laminated in said order; and a second step in which the laminate is heated and the copper paste for joining is sintered, in a gas atmosphere having a hydrogen concentration of no more than 45%. The joined body comprises the first member, the second member, and the sintered body of the copper paste for joining which joins the first member and the second member.

Description

Technical Field

[0001] The present invention relates to a copper paste for bonding, a method for manufacturing a bonded body, and a bonded body.

Background Art

[0002] In electrical bonding in electronic devices, generally, solder bonding is used. For example, in flip chip bonding of microdevices, solder balls, solder paste, or the like is used for bonding between the microdevice and the electrode pads on the substrate.

[0003] In recent years, in flip chip bonding, with the narrowing of the pitch of terminals, a method has been used in which metal pillars are formed on a microdevice and the metal pillars and the electrode pads on the substrate are solder-bonded. However, in solder bonding, there are problems such as (1) the generation of Kirkendall voids between the solder and the electrode pads and between the solder and the metal pillars, (2) when the reflow process is performed again after bonding, the solder melts and bonding failure occurs, and (3) signal reflection due to impedance mismatch at the interface of dissimilar metals.

[0004] On the other hand, methods of performing bonding using metals other than solder have been studied. For example, Patent Document 1 below proposes a method of bonding between copper pillars provided on a microdevice and copper pads on a substrate using a bonding agent (copper paste) in which copper microparticles and copper nanoparticles are mixed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the joining using copper paste, in order to obtain sufficient joining strength, it was necessary to thermocompression bond the members to be joined under high pressure, or to heat the copper paste in a reducing gas atmosphere containing hydrogen gas or the like. Thermocompression bonding under high pressure applies a load to the members to be joined, so problems such as a decrease in mass production yield and a decrease in long-term reliability may occur. On the other hand, regarding heating in a reducing gas atmosphere, it is desirable to reduce the hydrogen concentration so that it is not necessary to make the equipment used explosion-proof, and it is more desirable to change to an inert gas atmosphere such as nitrogen gas. However, under such conditions, conventional copper paste is not sufficient to obtain sufficient joining strength without applying a load to the members to be joined, and further improvement is required.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a copper paste for joining that can obtain sufficient joining strength even when heated in a gas atmosphere containing no hydrogen or having a low hydrogen concentration, a method for manufacturing a joined body using the same, and a joined body.

Means for Solving the Problems

[0008] One aspect of the present invention relates to a copper paste for joining containing copper particles, a polycarboxylic acid having a melting point of 120° C. or lower, and a dispersion medium.

[0009] According to the above copper paste for joining, sufficient joining strength can be obtained even when heated in a gas atmosphere containing no hydrogen or having a low hydrogen concentration. Thereby, the above copper paste for joining can be applied also to a joining device that is not explosion-proof.

[0010] Although the reason why such an effect is obtained is unclear, one of the factors is considered to be that the protective material on the surface of the copper particles is effectively removed when the copper paste is heated. In other words, the inventors speculate that the polycarboxylic acid having a melting point of 120°C or less flows when the copper paste is heated and can sufficiently contact the copper particles, and brings about a strong interaction between the carboxyl group and the protective material on the surface of the copper particles, so that the sintering of the copper particles proceeds sufficiently even in nitrogen or a gas atmosphere with a low hydrogen concentration.

[0011] The content of the polycarboxylic acid in the copper paste for bonding may be 0.01 to 1.5 mass % based on the total amount of copper particles, which can achieve both storage stability and bonding strength of the copper paste for bonding.

[0012] The copper paste for bonding may contain, as the polycarboxylic acid, a dicarboxylic acid represented by the following general formula (1). [ka] [In formula (1), R represents a divalent, linear or branched, saturated or unsaturated hydrocarbon group having 2 to 10 carbon atoms.]

[0013] The bonding copper paste may contain dimethyl glutaric acid as the polycarboxylic acid.

[0014] The bonding copper paste may contain, as the polycarboxylic acid, a polycarboxylic acid having a melting point of 100° C. or less.

[0015] The bonding copper paste may contain dihydroterpineol as a dispersion medium, which can achieve both high levels of printing properties and bonding strength of the paste.

[0016] The copper paste for bonding may contain, as copper particles, sub-micro copper particles having a volume average particle size of 0.12 to 0.8 μm and flake-shaped micro copper particles having a maximum diameter of 2 to 50 μm and an aspect ratio of 3.0 or more, which is suitable for bonding without pressure.

[0017] In this specification, "non-pressurized" means that the copper paste for bonding is under a micro-pressure of 0.01 MPa or less only due to the weight of the members to be bonded, or in addition to the weight, i.e., the pressure during bonding is 0.01 MPa or less.

[0018] The content of the above sub-micro copper particles in the copper paste for bonding is 30 to 90% by mass based on the total mass of the copper particles, and the content of the above micro copper particles may be 10 to 70% by mass based on the total mass of the copper particles.

[0019] The copper paste for bonding may be for non-pressurized bonding.

[0020] Another aspect of the present invention relates to a method for manufacturing a bonded body including a first step of preparing a laminate in which a first member, the above copper paste for bonding, and a second member are laminated in this order, and a second step of heating in a gas atmosphere having a hydrogen concentration of 45% or less to sinter the copper paste for bonding of the laminate. According to this manufacturing method, by using the above copper paste for bonding, a bonded body having sufficient bonding strength can be obtained by heating in the above gas atmosphere. Further, the above manufacturing method can be implemented even in a bonding device that is not explosion-proof.

[0021] In this specification, the hydrogen concentration in the gas atmosphere means the volume ratio (%) of hydrogen contained in the total gas inside the manufacturing apparatus.

[0022] The above gas atmosphere may be a nitrogen gas atmosphere. Even when the above bonding precursor is heated in such an atmosphere, a bonded body having sufficient bonding strength can be obtained.

[0023] In the above second step, the copper paste for bonding can be heated and sintered in a state of receiving the weight of the first member, or in a state of receiving the weight of the first member and a micro-pressure of 0.01 MPa or less. In this case, damage to the members bonded by non-pressurized bonding can be reduced.

[0024] At least one of the above-described first member and second member may be a semiconductor element. In this case, a semiconductor device can be obtained as the joined body.

[0025] In the above laminate, the first member may have a first electrode, the second member may have a second electrode facing the first electrode, and the copper paste for joining may be provided between the first electrode and the second electrode. In this case, a joined body in which the first electrode and the second electrode are joined with sufficient joining strength can be obtained.

[0026] At least one of the first electrode and the second electrode may be a metal pillar. In this case, a pillar-joined body can be obtained.

[0027] The first member and the second member are a wafer or chip containing one or more semiconductors selected from the group consisting of silicon, gallium nitride, and silicon carbide, and the first electrode and the second electrode may be through electrodes. According to this method, a semiconductor device in which a plurality of semiconductor wafers and / or semiconductor chips provided with through electrodes are laminated and the layers are microbump-joined can be obtained as the joined body.

[0028] Another aspect of the present invention relates to a joined body including a first member, a second member, and a sintered body of the copper paste for joining the first member and the second member.

[0029] At least one of the above-described first member and second member may be a semiconductor element. That is, the joined body may be a semiconductor device.

[0030] The joined body may be such that the first member has a first electrode, the second member has a second electrode facing the first electrode, and the sintered body of the copper paste for joining joins the first electrode and the second electrode.

[0031] At least one of the first electrode and the second electrode may be a metal pillar.

[0032] The first member and the second member are a wafer or a chip containing one or more semiconductors selected from the group consisting of silicon, gallium nitride, and silicon carbide, and the first electrode and the second electrode may be through electrodes.

Effects of the Invention

[0033] According to the present invention, it is possible to provide a copper paste for bonding that can obtain sufficient bonding strength even when heated in a gas atmosphere containing no hydrogen or having a low hydrogen concentration, and a method for manufacturing a bonded body using the same and the bonded body.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0035] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[0036] First, details of the copper paste for joining in this embodiment will be described.

[0037] [Copper Paste for Joining] The copper paste for joining in this embodiment contains at least copper particles, a polycarboxylic acid having a melting point of 120° C. or lower, and a dispersion medium. In this specification, for convenience, an aggregate of a plurality of copper particles is also referred to as "copper particles". The same applies to metal particles other than copper particles.

[0038] (Copper Particles) Examples of the copper particles include sub-micro copper particles, micro copper particles, and other copper particles.

[0039] [Sub-Micro Copper Particles] Sub-micro copper particles are copper particles having a particle size of 0.01 μm or more and less than 1.00 μm. The sub-micro copper particles preferably have sinterability in a temperature range of 150°C or more and 300°C or less. The sub-micro copper particles preferably contain copper particles having a particle size of 0.01 to 0.80 μm. The sub-micro copper particles may contain 10 mass% or more, may contain 20 mass% or more, may contain 30 mass% or more, or may contain 100 mass% of copper particles having a particle size of 0.01 to 0.80 μm. The particle size of the copper particles can be calculated from, for example, an SEM image. The powder of the copper particles is placed on a carbon tape for SEM with a spatula to form an SEM sample. This SEM sample is observed at 5000 times magnification with an SEM device. A rectangle circumscribing the copper particles in this SEM image is drawn with image processing software, and one side thereof is taken as the particle size of the particles.

[0040] The volume average particle size of the sub-micro copper particles is preferably 0.01 to 0.80 μm. If the volume average particle size of the sub-micro copper particles is 0.01 μm or more, effects such as suppression of the synthesis cost of the sub-micro copper particles, good dispersibility, and suppression of the amount of the surface treatment agent used are easily obtained. If the volume average particle size of the sub-micro copper particles is 0.80 μm or less, an effect that the sinterability of the sub-micro copper particles is excellent is easily obtained. From the viewpoint of further achieving the above effects, the volume average particle size of the sub-micro copper particles may be 0.02 μm or more, 0.05 μm or more, 0.10 μm or more, 0.11 μm or more, 0.12 μm or more, 0.15 μm or more, 0.2 μm or more, or 0.3 μm or more. Also, from the viewpoint of further achieving the above effects, the volume average particle size of the sub-micro copper particles may be 0.60 μm or less, 0.50 μm or less, 0.45 μm or less, or 0.40 μm or less. The volume average particle size of the sub-micro copper particles may be, for example, 0.01 to 0.60 μm, 0.01 to 0.50 μm, 0.02 to 0.80 μm, 0.05 to 0.80 μm, 0.10 to 0.80 μm, 0.11 to 0.80 μm, 0.12 to 0.80 μm, 0.15 to 0.80 μm, 0.15 to 0.60 μm, 0.20 to 0.50 μm, 0.30 to 0.45 μm, or 0.30 to 0.40 μm.

[0041] In this specification, the volume average particle diameter means the 50% volume average particle diameter. The volume average particle diameter of metal particles (for example, copper particles) can be measured, for example, by the following method. First, the raw material metal particles or the dried metal particles obtained by removing the volatile components from the metal paste are dispersed in a dispersion medium using a dispersant. Next, the volume average particle diameter of the obtained dispersion is measured with a light scattering method particle size distribution measuring device (for example, Shimadzu nanoparticle size distribution measuring device (SALD-7500nano, manufactured by Shimadzu Corporation)). When using a light scattering method particle size distribution measuring device, as the dispersion medium, hexane, toluene, α-terpineol, 4-methyl-1,3-dioxolan-2-one, etc. can be used.

[0042] The shape of the sub-micro copper particles is not particularly limited. Examples of the shape of the sub-micro copper particles include spherical, massive, needle-like, columnar, flake-like, substantially spherical, and aggregates thereof. From the viewpoints of dispersibility and filling property, the shape of the sub-micro copper particles may be spherical, substantially spherical or flake-like, and from the viewpoints of flammability, dispersibility, and miscibility with flake-like microparticles (for example, flake-like micro copper particles), it may be spherical or substantially spherical. In this specification, "flake-like" includes flat plate-like shapes such as plate-like and scaly.

[0043] The aspect ratio of the sub-micro copper particles may be 5.0 or less, 3.0 or less, 2.5 or less, or 2.0 or less from the viewpoints of dispersibility, filling property, and miscibility with flake-like microparticles (for example, flake-like micro copper particles). In this specification, "aspect ratio" means "long side of the particle / thickness of the particle". The long side and the thickness of the particle can be obtained, for example, from the SEM image of the particle.

[0044] The sub-micro copper particles may be treated with a surface treatment agent from the viewpoint of the dispersibility of the sub-micro copper particles. The surface treatment agent may be adsorbed, for example, on the surface of the sub-micro copper particles by hydrogen bonding or the like, or may react with the sub-micro copper particles and bond to the surface of the sub-micro copper particles. That is, the sub-micro copper particles may have a compound derived from a specific surface treatment agent. The surface treatment agent is included in the organic compounds contained in the copper paste for bonding.

[0045] Examples of the surface treatment agent include organic acids having 2 to 18 carbon atoms. Examples of the organic acids having 2 to 18 carbon atoms include saturated fatty acids such as acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, caprylic acid, methylheptanoic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, capric acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethylnonanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyl octanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pentyl decanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyl decanoic acid, heptylnonanoic acid, heptadecanoic acid, octadecanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid; unsaturated fatty acids such as octenoic acid, nonenoic acid, methylnonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, sapienic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, linolenic acid; and aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, nonylbenzoic acid.The organic acid may be used alone or in combination of two or more. By combining such an organic acid with the sub-micro copper particles, it tends to be possible to achieve both the dispersibility of the sub-micro copper particles and the desorbability of the organic acid during sintering.

[0046] From the viewpoint of the dispersibility of the sub-micro copper particles, the treatment amount of the surface treatment agent may be 0.07 to 2.10% by mass, 0.10 to 1.60% by mass, or 0.20 to 1.10% by mass based on the total mass of the sub-micro copper particles after surface treatment. The treatment amount of the surface treatment agent may be 0.07% by mass or more, 0.10% by mass or more, or 0.20% by mass or more based on the total mass of the sub-micro copper particles after surface treatment. The treatment amount of the surface treatment agent may be 2.10% by mass or less, 1.60% by mass or less, or 1.10% by mass or less based on the total mass of the sub-micro copper particles after surface treatment.

[0047] The treatment amount of the surface treatment agent may be an amount that adheres to one to three molecular layers on the surface of the sub-micro copper particles. This treatment amount is measured by the following method. Weigh W1 (g) of the surface-treated sub-micro copper particles into an alumina crucible (for example, manufactured by AS ONE, model number: 1-7745-07) treated at 700 °C for 2 hours in the air, and bake at 700 °C for 1 hour in the air. Then, treat at 300 °C for 1 hour in hydrogen, and measure the mass W2 (g) of the copper particles in the crucible. Next, based on the following formula, calculate the treatment amount of the surface treatment agent. Treatment amount of surface treatment agent (% by mass) = (W1 - W2) / W1 × 100

[0048] As the sub-micro copper particles, commercially available ones can be used. Examples of materials containing commercially available sub-micro copper particles include CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.36 μm), HT-14 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.41 μm), CT-500 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.72 μm), Tn-Cu100 (manufactured by Taiyo Nippon Sanso Corporation, volume average particle size 0.12 μm), and Cu-C-40 (manufactured by Fukuda Metal Foil & Powder Co., Ltd., volume average particle size 0.2 μm).

[0049] The content of the sub-micro copper particles may be 30% by mass or more, 35% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less or 85% by mass or less, based on the total mass of the metal particles contained in the copper paste for bonding. Further, the content of the sub-micro copper particles may be 30 to 90% by mass, 35 to 90% by mass, 40 to 85% by mass, or 50 to 85% by mass, based on the total mass of the metal particles contained in the copper paste for bonding. If the content of the sub-micro copper particles is within the above range, it becomes easy to ensure the bonding strength of the bonded body manufactured by sintering the copper paste for bonding. When the copper paste for bonding is used for bonding micro-devices, the micro-devices tend to exhibit good die shear strength and connection reliability.

[0050] [Micro copper particles] The micro copper particles are copper particles having a particle size of 1 μm or more and less than 50 μm. The micro copper particles preferably contain copper particles having a particle size of 2.0 to 50 μm. The micro copper particles may contain 50% by mass or more, 70% by mass or more, 80% by mass or more, or 100% by mass of copper particles having a particle size of 2.0 to 50 μm.

[0051] The volume average particle size of the micro copper particles is preferably 2.0 to 50 μm. If the volume average particle size of the micro copper particles is within the above range, volume shrinkage, void generation, etc. during sintering of the copper paste for bonding can be reduced, and it becomes easy to ensure the bonding strength of the bonded body manufactured by sintering the copper paste for bonding. When the copper paste for bonding is used for bonding micro-devices, the micro-devices tend to exhibit good die shear strength and connection reliability. From the viewpoint of further achieving the above effects, the volume average particle size of the micro copper particles may be 2.0 to 20 μm, 2.0 to 10 μm, 3.0 to 20 μm, or 3.0 to 10 μm. The volume average particle size of the micro copper particles may be 2.0 μm or more or 3.0 μm or more. The volume average particle size of the micro copper particles may be 50 μm or less, 20 μm or less, or 10 μm or less.

[0052] The shape of the micro copper particles is not particularly limited. Examples of the shape of the micro copper particles include spherical, massive, needle-like, flake-like, substantially spherical, and aggregates thereof. Among these, the preferred shape of the micro copper particles is flake-like. The micro copper particles may contain 50% by mass or more of the flake-like micro copper particles, may contain 70% by mass or more, may contain 80% by mass or more, or may contain 100% by mass.

[0053] By using the flake-like micro copper particles, the micro copper particles in the copper paste for bonding are oriented substantially parallel to the bonding surface, the volume shrinkage in the bonding surface direction when the copper paste for bonding is sintered can be suppressed, and it becomes easy to ensure the bonding strength of the bonded body manufactured by sintering the copper paste for bonding. When the copper paste for bonding is used for bonding microdevices, the microdevices tend to exhibit good die shear strength and connection reliability. From the viewpoint of further achieving the above effects, the aspect ratio of the flake-like micro copper particles is preferably 3.0 or more, more preferably 4.0 or more, and still more preferably 6.0 or more.

[0054] The maximum diameter and the average maximum diameter of the flake-like micro copper particles may be 2.0 to 50 μm, 3.0 to 50 μm, or 3.0 to 20 μm. The maximum diameter and the average maximum diameter of the flake-like micro copper particles can be determined, for example, from the SEM image of the particles. The maximum diameter and the average maximum diameter of the flake-like micro copper particles are determined, for example, as the major axis X and the average value Xav of the major axis of the flake-like micro copper particles. The major axis X is the distance between two parallel planes that circumscribe the flake-like micro copper particles in the three-dimensional shape of the flake-like micro copper particles and are selected such that the distance between the two parallel planes is maximized.

[0055] In the case of micro copper particles, the presence or absence of treatment with a surface treatment agent is not particularly limited. From the viewpoints of dispersion stability and oxidation resistance, the micro copper particles may be treated with a surface treatment agent. That is, the micro copper particles may have a compound derived from the surface treatment agent. The surface treatment agent may be adsorbed on the surface of the micro copper particles by hydrogen bonding or the like, or may react with the micro copper particles and bind to the surface of the micro copper particles.

[0056] The surface treatment agent may be removed by heating during bonding. Examples of such surface treatment agents include aliphatic carboxylic acids such as dodecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; aliphatic alcohols such as cetyl alcohol, stearyl alcohol, isobornyl cyclohexanol, and tetraethylene glycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, and stearylamine; aliphatic nitriles such as stearonitrile and decanenitrile; silane coupling agents such as alkylalkoxysilane; and polymer treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomer. The surface treatment agent may be used alone or in combination of two or more.

[0057] As the micro copper particles, commercially available ones can be used. Examples of materials containing commercially available micro copper particles include 1050YF (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 1.7 μm), MA-C025KFD (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 7.5 μm), 3L3 (manufactured by Fukuda Metal Foil & Powder Co., Ltd., volume average particle diameter 8.0 μm), 2L3N (manufactured by Fukuda Metal Foil & Powder Co., Ltd., volume average particle diameter 7.2 μm), and 1110F (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 3.8 μm).

[0058] The content of the micro copper particles may be 10% by mass or more, 15% by mass or more, or 20% by mass or more, and may be 70% by mass or less, 50% by mass or less, 45% by mass or less, or 40% by mass or less, based on the total mass of the metal particles contained in the copper paste for bonding. Also, the content of the micro copper particles may be 10 - 70% by mass, 10 - 65% by mass, 10 - 50% by mass, 15 - 60% by mass, 15 - 50% by mass, or 15 - 45% by mass, based on the total mass of the metal particles contained in the copper paste for bonding. If the content of the micro copper particles is within the above range, the occurrence of peeling, voids, and cracks in the joint (for example, the sintered body) can be suppressed, and the bonding strength can be ensured. When the copper paste for bonding is used for bonding microdevices, the microdevices tend to exhibit good die shear strength and connection reliability. The content of the flaky micro copper particles may be the same as the range of the content of the above micro copper particles. When the content of the flaky micro copper particles is within such a range, the above effects tend to be further enhanced.

[0059] [Other copper particles] Examples of the sub - micro copper particles and copper particles other than the micro copper particles include copper nanoparticles. Copper nanoparticles refer to copper particles having a particle size of less than 0.01 μm. Copper nanoparticles are generally coated on the surface with carboxylic acid or amine (referred to as the surface coating material). Copper nanoparticles have a larger specific surface area than copper micro - particles, and the proportion of the surface coating material per unit mass tends to increase. Therefore, since more surface coating material desorbs during sintering (heating), the volume shrinkage during sintering tends to increase compared to copper micro - particles. From the viewpoint of reducing volume shrinkage, the content of copper nanoparticles is preferably 30% by mass or less, more preferably 15% by mass or less, and even more preferably not contained, based on the total mass of the copper particles.

[0060] The copper paste for bonding of the present embodiment preferably contains sub-micro copper particles and micro copper particles. When the sub-micro copper particles and the micro copper particles are used in combination, volume shrinkage and sintering shrinkage associated with drying are likely to be suppressed, and the copper paste for bonding is less likely to peel from the bonding surface during sintering. That is, by using the sub-micro copper particles and the micro copper particles in combination, volume shrinkage when the copper paste for bonding is sintered is suppressed, and the bonded body can have a more sufficient bonding strength. When the copper paste for bonding in which the sub-micro copper particles and the micro copper particles are used in combination is used for bonding of a microdevice, the microdevice tends to exhibit better die shear strength and connection reliability. Further, the bonding portion of such a microdevice can have improved thermal conductivity and electrical conductivity.

[0061] The total content of the sub-micro copper particles and the content of the micro copper particles may be 80 to 100% by mass based on the total mass of the metal particles contained in the copper paste for bonding. If the total content of the sub-micro copper particles and the content of the micro copper particles are within the above range, volume shrinkage when the copper paste for bonding is sintered can be sufficiently reduced, and it becomes easy to ensure the bonding strength of the bonded body manufactured by sintering the copper paste for bonding. When the copper paste for bonding is used for bonding of a microdevice, the microdevice tends to exhibit good die shear strength and connection reliability. From the viewpoint of further achieving the above effects, the total content of the sub-micro copper particles and the content of the micro copper particles may be 90% by mass or more, 95% by mass or more, or 100% by mass based on the total mass of the metal particles.

[0062] The copper paste for bonding of the present embodiment may contain sub-micro copper particles having a volume average particle diameter of 0.12 to 0.8 μm and flaky micro copper particles having a maximum diameter of 2 to 50 μm and an aspect ratio of 3.0 or more. In this case, it is suitable for bonding without pressure. In the copper paste for bonding in this case, the content of the sub-micro copper particles is 30 to 90% by mass based on the total mass of the copper particles, and the content of the micro copper particles may be 10 to 70% by mass based on the total mass of the copper particles.

[0063] [Other metal particles] The copper paste for bonding of this embodiment can contain metal particles other than copper particles (also referred to as "other metal particles").

[0064] Examples of the other metal particles include particles such as nickel, silver, gold, palladium, and platinum. The volume average particle diameter of the other metal particles may be 0.01 to 10 μm, 0.01 to 5 μm, or 0.05 to 3 μm. The shape of the other metal particles is not particularly limited. From the viewpoint of obtaining sufficient bondability, the content of the other metal particles may be less than 20% by mass, may be 10% by mass or less, or may be 0% by mass based on the total mass of the metal particles contained in the copper paste for bonding.

[0065] [Polycarboxylic acid having a melting point of 120°C or lower] As the polycarboxylic acid having a melting point of 120°C or lower (hereinafter, may also be referred to as "low melting point polycarboxylic acid"), a dicarboxylic acid represented by the following general formula (1) can be used. [Chemical formula] [In formula (1), R represents a divalent linear or branched saturated or unsaturated hydrocarbon group having 2 to 10 carbon atoms.]

[0066] Examples of the above dicarboxylic acid include dimethylglutaric acid (melting point 83°C), isopropylmalonic acid (melting point 90°C), allylmalonic acid (melting point 103°C), and ethylmalonic acid (112°C). It is preferable that the above R is a linear or branched alkylene group having 4 to 5 carbon atoms.

[0067] From the viewpoint of improving the bonding strength at a low bonding temperature of 200°C or lower, the copper paste for bonding may contain a polycarboxylic acid having a melting point of 120°C or lower, a polycarboxylic acid having a melting point of 115°C or lower, or a polycarboxylic acid having a melting point of 100°C or lower as the low-melting polycarboxylic acid. From the viewpoint of storage stability, the melting point of the low-melting polycarboxylic acid may be 30°C or higher or 50°C or higher.

[0068] From the viewpoint of achieving both storage stability and bonding strength of the copper paste for bonding, the content of the low-melting polycarboxylic acid in the copper paste for bonding may be 0.01 to 1.5% by mass, 0.05 to 1.5% by mass, 0.1 to 1.5% by mass, 0.1 to 1% by mass, or 0.1 to 0.5% by mass based on the total amount of the copper particles.

[0069] (Dispersion medium) The dispersion medium is not particularly limited as long as it has the function of dispersing metal particles, and it may be volatile. Examples of the volatile dispersion medium include alcohols such as monohydric alcohols and polyhydric alcohols, ethers, esters, acid amides, aliphatic hydrocarbons, aromatic hydrocarbons, etc. Specifically, alcohols such as cyclohexanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, α-terpineol (α-terpinol), dihydroterpineol (dihydroterpinol); ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, propylene glycol dipropyl ether, tripropylene glycol dimethyl ether; esters such as ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexane, octane, nonane, decane, undecane; aromatic hydrocarbons such as benzene, toluene, xylene, etc.

[0070] The content of the dispersion medium may be 2% by mass or more, or 5% by mass or more, based on the total mass of the copper paste for bonding, and may be 50% by mass or less, 30% by mass or less, or 20% by mass or less. For example, the content of the dispersion medium may be 2 to 50% by mass, 5 to 30% by mass, or 5 to 20% by mass based on the total mass of the copper paste for bonding. Further, the content of the dispersion medium may be 5 to 50 parts by mass, 5 to 40 parts by mass, or 7 to 35 parts by mass, with the total mass of the metal particles contained in the copper paste for bonding being 100 parts by mass. If the content of the dispersion medium is within the above range, the copper paste for bonding can be adjusted to a more appropriate viscosity, and it is difficult to inhibit the sintering of copper particles.

[0071] From the viewpoint of achieving both high-level printing characteristics and bonding strength of the paste, the copper paste for bonding in this embodiment preferably contains dihydroterpineol. The content of dihydroterpineol may be 30% by mass or more, 60% by mass or more, or 100% by mass based on the total mass of the dispersion medium.

[0072] The copper paste for bonding preferably contains a dispersion medium having a boiling point of 300°C or higher. By containing a dispersion medium having a boiling point of 300°C or higher, plasticity and adhesiveness are imparted to the copper paste for bonding until immediately before the start of sintering, and bonding without pressure becomes easy. The boiling point of the dispersion medium having a boiling point of 300°C or higher may be 300 to 450°C, 305 to 400°C, or 310 to 380°C from the viewpoint of not hindering sintering and densification during sintering of the copper paste for bonding and being rapidly evaporated and removed when the bonding temperature is reached.

[0073] As the dispersion medium having a boiling point of 300 °C or higher, isobornyl cyclohexanol (MTPH, manufactured by Nippon Terpene Chemical Co., Ltd.), butyl stearate, Exceparl BS (manufactured by Kao Corporation), stearyl stearate, Exceparl SS (manufactured by Kao Corporation), 2-ethylhexyl stearate, Exceparl EH-S (manufactured by Kao Corporation), isotridecyl stearate, Exceparl TD-S (manufactured by Kao Corporation), heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, methyl heptadecane, tridecyl cyclohexane, tetradecyl cyclohexane, pentadecyl cyclohexane, hexadecyl cyclohexane, undecyl benzene, dodecyl benzene, tetradecyl benzene, tridecyl benzene, pentadecyl benzene, hexadecyl benzene, heptadecyl benzene, nonyl naphthalene, diphenyl propane, octyl octanoate, methyl myristate, ethyl myristate, methyl linoleate, methyl stearate, triethylene glycol bis(2-ethylhexanoic acid), tributyl citrate, dibutyl sebacate, methoxyphenethyl alcohol, benzyl phenol (C 13 H 12 O), hexadecanenitrile, heptadecanenitrile, benzyl benzoate, sym-collidine, bis(2-ethylhexyl) adipate, etc. can be mentioned. From the viewpoint of making bonding without pressure easier, it is preferable that the solvent component having a boiling point of 300 °C or higher contains at least one selected from the group consisting of isobornyl cyclohexanol, tributyrin, butyl stearate, and octyl octanoate.

[0074] The content of the dispersion medium having a boiling point of 300 °C or higher may be 2% by mass or more, 2.2% by mass or more, or 2.4% by mass or more, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less based on the total mass of the copper paste for bonding. For example, the content of the dispersion medium having a boiling point of 300 °C or higher may be 2 to 50% by mass based on the total mass of the copper paste for bonding.

[0075] (Other components) The copper paste for bonding can contain, as additives, wetting improvers such as nonionic surfactants and fluorosurfactants; surface tension adjusters; dispersants such as alkylamines and alkylcarboxylic acids; antifoaming agents such as silicone oil; ion trappers such as inorganic ion exchangers, etc. The content of the additives can be appropriately adjusted within a range that does not inhibit the effects of the present invention. Further, the total content of the non-metallic inorganic particles (for example, glass particles, etc.) in the copper paste for bonding may be 1% by mass or less, or may be 0.1% by mass or less, based on the total amount of the copper particles. Furthermore, the copper paste for bonding may not contain non-metallic inorganic particles.

[0076] The viscosity of the above-described copper paste for bonding is not particularly limited, and when applying by a method such as printing, it may be adjusted to a viscosity suitable for the application method. The Casson viscosity of the copper paste for bonding at 25°C may be 0.05 Pa·s or more, or 0.06 Pa·s or more, and may be 2.0 Pa·s or less, or 1.0 Pa·s or less. For example, the Casson viscosity of the copper paste for bonding at 25°C may be 0.05 to 2.0 Pa·s, or may be 0.06 to 1.0 Pa·s.

[0077] According to the copper paste for bonding of the present embodiment, sufficient bonding strength can be obtained even when heated in a gas atmosphere containing no hydrogen or having a low hydrogen concentration. Therefore, the copper paste for bonding of the present embodiment can also be applied to bonding devices that are not explosion-proof compliant. Further, the copper paste for bonding of the present embodiment may be for non-pressure bonding.

[0078] <Preparation of Copper Paste for Bonding> The copper paste for bonding can be prepared by mixing the above-described copper particles, low melting point polycarboxylic acid, dispersion medium, and optionally other metal particles and additives contained. After mixing each component, a stirring treatment may be performed. The copper paste for bonding may adjust the maximum particle size of the dispersion by a classification operation. At this time, the maximum particle size of the dispersion can be 20 μm or less, and can also be 10 μm or less. The metal particles such as the sub-micro copper particles may be those treated with a surface treatment agent.

[0079] When using sub-micro copper particles and micro copper particles as the copper particles, the copper paste for bonding may be prepared, for example, by the following method. First, a dispersant is added to the dispersion medium and the low-melting polycarboxylic acid as necessary, and then the sub-micro copper particles are mixed and subjected to a dispersion treatment. Next, the micro copper particles and other metal particles as necessary are added and a dispersion treatment is performed. The dispersion methods and dispersion conditions suitable for dispersion may be different between the sub-micro copper particles and the micro copper particles. Generally, the sub-micro copper particles are more difficult to disperse than the micro copper particles, and in order to disperse the sub-micro copper particles, a higher intensity than that added when dispersing the micro copper particles is required. On the other hand, the micro copper particles are not only easy to disperse, but may be deformed when a high intensity is applied for dispersion. Therefore, by adopting the above procedure, good dispersibility can be easily obtained and the performance of the copper paste for bonding can be further improved.

[0080] The dispersion treatment can be carried out using a disperser or a stirrer. Examples of the disperser and the stirrer include Ishikawa stirrer, Silverson stirrer, cavitation stirrer, rotation-revolution type stirring device, ultra-thin film high-speed rotary disperser, ultrasonic disperser, Lycra machine, twin-screw kneader, bead mill, ball mill, three-roll mill, homomixer, planetary mixer, ultra-high pressure type disperser, and thin-layer shear disperser.

[0081] The classification operation can be carried out, for example, by filtration, natural sedimentation, and centrifugal separation. Examples of the filter for filtration include water comb, metal mesh, metal filter, and nylon mesh.

[0082] The stirring treatment can be carried out using a stirrer. Examples of the stirrer include Ishikawa stirrer, rotation-revolution type stirring device, Lycra machine, twin-screw kneader, three-roll mill, and planetary mixer.

[0083] <Method for manufacturing a bonded body> The method for manufacturing the joined body of the present embodiment includes a first step of preparing a laminate in which a first member, the copper paste for joining, and a second member are laminated in this order, and a second step of heating in a gas atmosphere with a hydrogen concentration of 45% or less to sinter the copper paste for joining of the laminate.

[0084] Hereinafter, the method for manufacturing the joined body of the present embodiment will be described with reference to the drawings.

[0085] The method for manufacturing the joined body according to one embodiment prepares, as the laminate, a laminate including a first member having a first electrode, a second member having a second electrode and arranged such that the first electrode and the second electrode face each other, and the copper paste for joining provided between the first electrode and the second electrode.

[0086] FIG. 1 is a schematic cross-sectional view showing the method for manufacturing the joined body of one embodiment. FIGS. 2 and 3 are schematic cross-sectional views showing an example of the first step. Here, a case where the first electrode is a metal pillar and the second electrode is an electrode pad is shown.

[0087] (First step) In the first step, a laminate 50 including a first member 10, a second member 20, and a copper paste for joining (joint portion) 30 is prepared (see FIG. 1(a)).

[0088] The first member 10 includes a metal pillar 11 and a substrate (first substrate) 12 on which the metal pillar 11 is provided on one surface. The first member 10 is, for example, a microdevice such as a logic, analog IC, and power IC.

[0089] A plurality of metal pillars 11 are provided, for example, on one surface of the first substrate 12, and when the first member 10 and the second member 20 are arranged to face each other, each of the plurality of metal pillars 11 is arranged on the first substrate 12 so as to face the electrode pad 21 in the second member 20.

[0090] The material of the metal pillar 11 is not particularly limited. When an oxide film is formed on the bonding surface of the metal pillar 11 (the surface on which the copper paste 30 for bonding is disposed, the surface on the opposite side of the first substrate 12), from the viewpoint that the oxide film is easily removed in the second step, at least the bonding surface of the metal pillar 11 is preferably composed of at least one metal selected from the group consisting of gold, platinum, silver, palladium, copper, nickel, and zinc. Further, from the viewpoints of suppressing kirkendall voids after bonding and suppressing impedance mismatch, at least the bonding surface of the metal pillar 11 is preferably composed of a material containing copper, and more preferably composed of a material containing copper at a certain ratio or more (for example, 90% by mass or more).

[0091] The shape of the metal pillar 11 is not particularly limited. The shape of the cross section perpendicular to the direction in which the metal pillar 11 extends may be, for example, circular, elliptical, rectangular, or the like. The height of the metal pillar 11 may be, for example, 10 μm or more and may be 100 μm or less. The pillar diameter of the metal pillar 11 (the maximum diameter when the above cross section is not circular) may be, for example, 10 μm or more and may be 300 μm or less.

[0092] The second member 20 includes an electrode pad 21 and a substrate (second substrate) 22 on which the electrode pad 21 is provided on one surface. The second member 20 is, for example, a substrate such as a mounting substrate, a lead frame, a high heat dissipation mounting substrate, a silicon interposer, or an epoxy wiring board.

[0093] The shape and material of the electrode pad 21 are not particularly limited. When an oxide film is formed on the bonding surface of the electrode pad 21 (the surface on which the copper paste for bonding 30 is disposed, the surface opposite to the second substrate 22), from the viewpoint that the oxide film is easily removed in the second step, at least the bonding surface of the electrode pad 21 is preferably composed of at least one metal selected from the group consisting of gold, platinum, silver, palladium, copper, nickel, and zinc. Further, from the viewpoints of suppressing kirkendall voids after bonding and suppressing impedance mismatch, at least the bonding surface of the electrode pad 21 is preferably composed of a material containing copper, and more preferably composed of a material containing copper at a certain ratio or more (for example, 90% by mass or more). The materials (metals) constituting the metal pillar 11 and the electrode pad 21 may be the same or different.

[0094] The copper paste for bonding 30 forms a joint between the metal pillar 11 and the electrode pad 21. In FIG. 1, the copper paste for bonding 30 exists only between the metal pillar 11 and the electrode pad 21, but the location where the copper paste for bonding 30 is disposed is not limited thereto. That is, the copper paste for bonding 30 only needs to exist at least between the metal pillar 11 and the electrode pad 21, and may also exist in a region other than between the metal pillar 11 and the electrode pad 21.

[0095] The thickness of the copper paste for bonding in the laminate 50 (the distance from the bonding surface of the metal pillar 11 to the bonding surface of the electrode pad 21) may be 1 to 1000 μm, 5 to 500 μm, 10 to 500 μm, 15 to 500 μm, 20 to 300 μm, 50 to 200 μm, 10 to 3000 μm, 10 to 250 μm, or 15 to 150 μm. The thickness of the copper paste for bonding may be 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or 50 μm or more. The thickness of the copper paste for bonding may be 3000 μm or less, 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, or 150 μm or less.

[0096] The laminate 50 can be obtained, for example, by arranging the copper bonding paste 30 on at least one bonding surface of the metal pillar 11 in the first member 10 and the electrode pad 21 in the second member 20, and then connecting the metal pillar 11 of the first member 10 and the electrode pad 21 of the second member 20 through the copper bonding paste 30. For example, as shown in FIG. 2, after arranging the copper bonding paste 30 on the bonding surface of the electrode pad 21 in the second member 20 (see FIG. 2(a)), the first member 10 is arranged on the second member 20 such that the metal pillar 11 and the electrode pad 21 face each other through the copper bonding paste 30 (see FIG. 2(b)), and the laminate 50 may be obtained by connecting the metal pillar 11 and the electrode pad 21 through the copper bonding paste 30 (see FIG. 2(c)). As shown in FIG. 3, after arranging the copper bonding paste 30 on the bonding surface of the metal pillar 11 in the first member 10 (see FIG. 3(a)), the second member 20 is arranged on the first member 10 such that the metal pillar 11 and the electrode pad 21 face each other through the copper bonding paste 30 (see FIG. 3(b)), and the laminate 50 may also be obtained by connecting the metal pillar 11 and the electrode pad 21 (see FIG. 3(c)). The copper bonding paste 30 may be arranged on at least a part of the bonding surfaces of the metal pillar 11 and the electrode pad 21, or may be arranged on the entire bonding surface.

[0097] The method of arranging the copper bonding paste 30 on the bonding surfaces of the metal pillar 11 and the electrode pad 21 may be any method that can attach the copper bonding paste to the bonding surface (end face) of the metal pillar 11 and the bonding surface of the electrode pad 21, and known methods can be adopted.

[0098] Specific examples of the method of attaching the copper bonding paste to the bonding surface of the metal pillar 11 include a method of dipping the bonding surface of the metal pillar 11 into the copper bonding paste thinly and uniformly extended with a squeegee or the like, a method of transferring the copper bonding paste to the bonding surface of the metal pillar 11 with a roller thinly and uniformly coated with the copper bonding paste, a method of printing the copper bonding paste on the bonding surface of the metal pillar 11 with a needle dispenser, and the like.

[0099] Specific examples of the method for attaching the copper paste for bonding to the bonding surface of the electrode pad 21 include methods by printing such as screen printing, transfer printing, offset printing, letterpress printing, intaglio printing, gravure printing, stencil printing, jet printing, etc., methods using a dispenser (for example, a jet dispenser, a needle dispenser), a comma coater, a slit coater, a die coater, a gravure coater, a slit coater, a bar coater, an applicator, a spray coater, a spin coater, a dip coater, etc., a method by soft lithography, a particle deposition method, a method by electrodeposition coating, and the like.

[0100] Examples of the method for laminating the first member (for example, a microdevice) and the second member (for example, a substrate) include methods using, for example, a chip mounter, a flip chip bonder, a positioning jig made of carbon or ceramics, and the like.

[0101] The copper paste 30 for bonding disposed between the first member and the second member (between the metal pillar 11 and the electrode pad 21) may be dried from the viewpoint of suppressing the flow during sintering and the generation of voids. That is, the manufacturing method of the present embodiment may further include a drying step of drying the copper paste 30 for bonding after the first step and before the second step.

[0102] Drying can be carried out in the atmosphere, in an oxygen-free atmosphere such as nitrogen or noble gas, or in a reducing atmosphere such as hydrogen or formic acid. The drying method may be drying by leaving it at room temperature (for example, 25°C), heating drying, or vacuum drying. For heating drying or vacuum drying, for example, a hot plate, a warm air dryer, a warm air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, a hot plate press device, etc. can be used. The drying conditions (drying temperature and time) may be appropriately set according to the type and amount of the volatile components (components other than metal particles such as a dispersion medium) used in the copper paste for bonding. As the drying conditions (drying temperature and time), for example, conditions of drying at 50°C or higher and less than 150°C for 1 to 120 minutes may be used.

[0103] (Second step) In the second step, the laminate 50 is heated in a gas atmosphere with a hydrogen concentration of 45% or less, and the copper paste 30 for bonding is sintered at a predetermined sintering temperature to obtain a sintered body 31. Thereby, a joined body 100 including the first member 10, the second member 20, and the sintered body (joint portion) 31 provided between the metal pillars 11 and the electrode pads 21 is obtained (see Fig. 1(b)). In the joined body 100, the metal pillars 11 and the electrode pads 21 are electrically connected by the sintered body 31.

[0104] For the heat treatment, for example, a hot plate, a warm air dryer, a warm air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, etc. can be used.

[0105] The sintering temperature (the maximum temperature reached during the heat treatment) may be 150 - 300°C, 170 - 250°C, or 200 - 250°C from the viewpoints of promoting sufficient sintering, reducing thermal damage to the first member (e.g., a microdevice) and the second member (e.g., a substrate), and improving the yield. The sintering temperature may be 150°C or higher, 170°C or higher, or 200°C or higher. The sintering temperature may be 300°C or lower or 250°C or lower. If the sintering temperature is 300°C or lower, sintering can proceed sufficiently with less thermal damage to the first member and the second member, and sufficient bonding strength tends to be obtained. If the sintering temperature is 150°C or higher, sintering tends to proceed sufficiently even if the sintering time is 60 minutes or less. Even if the sintering temperature is less than 150°C, it is possible to sufficiently proceed with sintering by setting the sintering time to more than 60 minutes. For the purpose of improving reliability in reliability tests such as temperature cycle tests and power cycle tests, heat treatment can also be performed under conditions of 300°C or higher.

[0106] The sintering time (the holding time at the maximum temperature reached) may be 1 minute or longer, 1.5 minutes or longer, or 2 minutes or longer from the viewpoint of sufficiently removing volatile components (components other than metal particles such as a dispersion medium) and promoting sufficient sintering. The sintering time may be 60 minutes or less, less than 40 minutes, or less than 30 minutes from the viewpoint of improving the yield. From these viewpoints, the sintering time may be 1 - 60 minutes, 1 minute or longer and less than 40 minutes, or 1 minute or longer and less than 30 minutes. In particular, when the sintering temperature is 150 - 300°C, it is preferable that the sintering time be within the above range.

[0107] The atmosphere for heating the laminate 50 in the second step can be a gas atmosphere with a hydrogen concentration of 45% or less, and considering the explosiveness of hydrogen gas, it may be a gas atmosphere with a hydrogen concentration of 10% or less, a gas atmosphere with a hydrogen concentration of 4.5% or less, or a gas atmosphere without hydrogen.

[0108] Examples of the gas atmosphere include a mixed gas atmosphere containing hydrogen and a noble gas and / or nitrogen, a gas atmosphere containing formic acid gas, a mixed gas atmosphere containing formic acid gas and a noble gas and / or nitrogen, and a gas atmosphere containing a noble gas and / or nitrogen. From the perspective of an inert gas, a nitrogen gas atmosphere, an argon gas atmosphere, or a mixed gas atmosphere of nitrogen gas and argon gas is preferable as the gas atmosphere not containing hydrogen.

[0109] The second step may be carried out under pressure or under no pressure (only the weight of the members to be joined or, in addition to the weight, a micro pressure of 0.01 MPa or less that the copper paste for joining receives, in other words, the pressure is 0.01 MPa or less). Examples of the method by which the copper paste for joining receives a pressure of 0.01 MPa or less include a method of placing a weight on a member (for example, the first member) arranged on the upper side in the vertical direction, a method of applying pressure with a spring jig, and the like.

[0110] As described above, in the method for manufacturing a joined body according to the present embodiment, by using the copper paste for joining of the present embodiment, sufficient joining strength can be obtained even when heated in a gas atmosphere not containing hydrogen or having a low hydrogen concentration. Further, sufficient joining strength can be obtained even under no pressure. The method for manufacturing a joined body according to the present embodiment can be carried out even in a joining device not corresponding to explosion prevention, and further, since sufficient joining strength can be obtained even under no pressure, effects such as simplification of the process, simplification of the joining device, and improvement of the manufacturing yield can be obtained.

[0111] From the perspective of sufficiently joining the first member and the second member, the shear strength of the joined body 100 may be 5 MPa or more, 7 MPa or more, 10 MPa or more, or 15 MPa or more. The die shear strength can be measured using a universal bond tester (Royce 650, manufactured by Royce Instruments) or a universal type bond tester (4000 series, manufactured by DAGE), etc.

[0112] The manufacturing method of the bonded body of the present embodiment can be applied to flip-chip bonding of microdevices.

[0113] The manufacturing method of the bonded body of the present embodiment is not limited to the above-described embodiment, and various modifications are possible.

[0114] For example, the first member and the second member may be a wafer or a chip including one or more semiconductors selected from the group consisting of silicon, gallium nitride, and silicon carbide, and the first electrode and the second electrode may be through electrodes. According to this method, a semiconductor device which is a laminate of a plurality of semiconductor wafers and / or semiconductor chips provided with through electrodes and in which the layers are microbump-bonded can be obtained as the bonded body.

[0115] Examples of the wafer or chip include a silicon wafer, a gallium nitride wafer, a silicon carbide wafer, a silicon chip, a gallium nitride chip, and a silicon carbide chip. Examples of the wafer or chip including two or more semiconductors include those in which gallium nitride is laminated on a silicon wafer or chip.

[0116] Furthermore, the manufacturing method of the bonded body of the present embodiment will be described in detail with reference to the drawings.

[0117] FIG. 4 is a schematic cross-sectional view showing an example of a bonded body manufactured by the manufacturing method of the bonded body of the present embodiment.

[0118] The bonded body 125 shown in FIG. 4 includes a first member 102, a second member 103, and a sintered body 101 of the copper bonding paste of the present embodiment that bonds the first member 102 and the second member 103.

[0119] The first member and the second member are, for example, semiconductor elements such as semiconductor wafers, semiconductor chips, IGBTs, diodes, Schottky barrier diodes, MOS-FETs, thyristors, logic, sensors, analog integrated circuits (analog ICs), power ICs, LEDs, semiconductor lasers, transmitters, etc.; lead frames; ceramic substrates with metal plates attached (e.g., DBC); substrates for mounting semiconductor elements such as LED packages; metal wirings such as copper ribbons and metal frames; block bodies such as metal blocks; power supply members such as terminals; heat sinks; water-cooled plates, etc.

[0120] The surfaces 102a and 103a in contact with the sintered body of the copper paste for joining the first member 102 and the second member 103 may contain metal. Examples of the metal include copper, nickel, silver, gold, palladium, platinum, lead, tin, cobalt, etc. The metal may be used alone or in combination of two or more. Also, the surface in contact with the sintered body may be an alloy containing the above metal. Examples of the metal used in the alloy include, in addition to the above metals, zinc, manganese, aluminum, beryllium, titanium, chromium, iron, molybdenum, etc. Examples of the member containing metal on the surface in contact with the sintered body include members having various metal platings (chips having metal platings, lead frames having various metal platings, etc.), wires, heat spreaders, ceramic substrates with metal plates attached, lead frames made of various metals, copper plates, copper foils, etc.

[0121] The shear strength of the joined body 125 may be 5 MPa or more, 7 MPa or more, 10 MPa or more, or 15 MPa or more from the viewpoint of sufficiently joining the first member 102 and the second member 103. The die shear strength can be measured using a universal bond tester (Royce 650, manufactured by Royce Instruments) or a universal type bond tester (4000 series, manufactured by DAGE), etc.

[0122] In the above joined body 125, when the first member is a semiconductor element, the above joined body 125 becomes a semiconductor device.

[0123] FIG. 5 is a schematic cross-sectional view showing an example of a semiconductor device manufactured by the method for manufacturing a bonded body of the present embodiment. The semiconductor device 130 shown in FIG. 5 includes a sintered body 111 of the copper paste for bonding according to the present embodiment, a lead frame 115a, a lead frame 115b, a wire 116, a semiconductor element 118 connected onto the lead frame 115a via the sintered body 111, and a mold resin 117 that molds these components. The semiconductor element 118 is connected to the lead frame 115b via the wire 116.

[0124] Examples of the semiconductor device include power modules such as diodes, rectifiers, thyristors, MOS gate drivers, power switches, power MOSFETs, IGBTs, Schottky diodes, and fast recovery diodes; transmitters; amplifiers; high-brightness LED modules; sensors; and the like.

[0125] FIG. 6 (FIG. 6(a) and FIG. 6(b)) is a schematic cross-sectional view for explaining the method for manufacturing the bonded body 125. The method for manufacturing the bonded body 125 according to the present embodiment includes preparing a laminate 60 in which the copper paste 110 for bonding and a second member 103 are laminated in this order on the side of the first member 102 in the direction in which the weight of the first member 102 acts (FIG. 6(a)), and heating the laminate 60 in a gas atmosphere having a hydrogen concentration of 45% or less to sinter the copper paste 110 for bonding. Thereby, the bonded body 125 is obtained (FIG. 6(b)). Note that the direction in which the weight of the first member 102 acts can also be said to be the direction in which gravity acts.

[0126] In the above step, the copper paste 110 for bonding may be sintered in a state of receiving the weight of the first member 102, or in a state of receiving the weight of the first member 102 and a micro pressure of 0.01 MPa or less (in other words, under the condition that the pressure is 0.01 MPa or less).

[0127] The laminate 60 can be prepared by the same method and conditions as the laminate 50 described above. The drying and sintering of the copper paste 110 for bonding can also be carried out by the same method and conditions as the copper paste 30 for bonding described above.

[0128] The thickness of the copper paste 110 for bonding may be 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or 50 μm or more, and may be 3000 μm or less, 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, or 150 μm or less. For example, the thickness of the copper paste 10 for bonding may be 1 to 1000 μm, may be 10 to 500 μm, may be 50 to 200 μm, may be 10 to 3000 μm, may be 15 to 500 μm, may be 20 to 300 μm, may be 5 to 500 μm, may be 10 to 250 μm, or may be 15 to 150 μm.

[0129] As a method of disposing one member on the other member (for example, a method of disposing the first member 102 on the second member 103 provided with the copper paste 110 for bonding), for example, a method using a chip mounter, a flip chip bonder, a positioning jig made of carbon or ceramics, etc. can be mentioned.

[0130] By using the copper paste 110 for bonding of the present embodiment, even when heated in a gas atmosphere with a hydrogen concentration of 45% or less, the bonded body can have sufficient bonding strength. Also, even when bonding is performed without pressure, the bonded body can have sufficient bonding strength.

[0131] The semiconductor device 130 according to this embodiment can be manufactured in the same manner as the manufacturing method of the above-described joined body 125. That is, the manufacturing method of the semiconductor device uses a semiconductor element for at least one of the first member and the second member, and prepares a laminate in which the joining copper paste and the second member are laminated in this order on the first member and on the side in the direction in which the weight of the first member acts. The method includes a step of heating the laminate in a gas atmosphere having a hydrogen concentration of 45% or less to sinter the joining copper paste. For example, as shown in FIG. 7 (FIGS. 7(a) to 7(c)), after providing the joining copper paste 120 on the lead frame 115a and disposing the semiconductor element 118 to obtain a laminate 70 (FIG. 7(a)), the laminate 70 is heated to sinter the joining copper paste 120 to obtain a joined body 80 (FIG. 7(b)). Next, the lead frame 115b and the semiconductor element 118 in the obtained joined body 80 are connected by a wire 116 and sealed with a sealing resin. The semiconductor device 130 is obtained by the above steps (FIG. 7(c)). The obtained semiconductor device 120 can have sufficient die shear strength and connection reliability even when joining is performed in a gas atmosphere having a hydrogen concentration of 45% or less, preferably without pressure. The semiconductor device of this embodiment has sufficient joining force, and by including a sintered body of a joining copper paste containing copper having a high thermal conductivity and melting point, it can have sufficient die shear strength, excellent connection reliability, and excellent power cycle resistance.

[0132] The joined body 140 shown in FIG. 8 includes a first member 102, a second member 103, a third member 104, a fourth member 105, a sintered body 101a of the joining copper paste that joins the first member 102 and the second member 103, a sintered body 101b of the joining copper paste that joins the first member 102 and the third member 104, and a sintered body 101c of the joining copper paste that joins the third member 104 and the fourth member 105.

[0133] Such a bonded body 140 is, for example, as shown in FIG. 9 (FIGS. 9(a) and 9(b)), on the side in the direction in which the weight of the third member 104 acts, a laminated portion in which the second copper bonding paste 110b, the first member 102, the first copper bonding paste 110a, and the second member 103 are laminated in this order, and on the side in the direction in which the weight of the third member 104 acts, a laminated body 90 having a laminated portion in which the third copper bonding paste 110c and the fourth member 105 are laminated in this order is prepared (FIG. 9(a)). In the same manner as the manufacturing method of the bonded body 125, it can be obtained by a method including a step of sintering the first copper bonding paste 110a, the second copper bonding paste 110b, and the third copper bonding paste 110c (FIG. 9(b)). In the above method, the first copper bonding paste 110a, the second copper bonding paste 110b, and the third copper bonding paste 110c are copper bonding pastes according to this embodiment. By sintering the first copper bonding paste 110a, a sintered body 101a is obtained. By sintering the second copper bonding paste 110b, a sintered body 101b is obtained. By sintering the third copper bonding paste 110c, a sintered body 101c is obtained.

[0134] Further, the bonded body 140 can also be obtained, for example, after obtaining the above bonded body 125, by forming a laminated portion in which the second copper bonding paste 110b and the first member 102 are laminated in this order on the side in the direction in which the weight of the third member 104 acts, and a laminated portion in which the third copper bonding paste 110c and the fourth member 105 are laminated in this order on the side in the direction in which the weight of the third member 104 acts, and in the same manner as the manufacturing method of the bonded body 125, by a method including a step of sintering the second copper bonding paste 110b and the third copper bonding paste 110c.

[0135] The joined body 150 shown in FIG. 10 includes a first member 102, a second member 103, a third member 104, a fourth member 105, a fifth member 106, a sintered body 101a of the copper paste for joining that joins the first member 102 and the second member 103, a sintered body 101c of the copper paste for joining that joins the third member 104 and the fourth member 105, a sintered body 101d of the copper paste for joining that joins the first member 102 and the fifth member 106, and a sintered body 101e of the copper paste for joining that joins the third member 104 and the fifth member 106.

[0136] Such a joined body 150, for example, as shown in FIG. 11 (FIGS. 11(a) and 11(b)), on the side in the direction in which the weight of the third member 104 acts, a laminated portion in which a fifth copper paste for joining 110e, a fifth member 106, a fourth copper paste for joining 110d, a first member 102, a first copper paste for joining 110a, and a second member 103 are laminated in this order, and a laminated body 95 having a laminated portion in which a third copper paste for joining 110c and a fourth member 105 are laminated in this order on the side in the direction in which the weight of the third member 104 acts are prepared (FIG. 11(a)). In the same manner as the manufacturing method of the joined body 125, it can be obtained by a method including a step of sintering the first copper paste for joining 110a, the third copper paste for joining 110c, the fourth copper paste for joining 110d, and the fifth copper paste for joining 110e (FIG. 11(b)). In the above method, the first copper paste for joining 110a, the third copper paste for joining 110c, the fourth copper paste for joining 110d, and the fifth copper paste for joining 110e are copper pastes for joining according to this embodiment. By sintering the first copper paste for joining 110a, a sintered body 101a is obtained. By sintering the third copper paste for joining 110c, a sintered body 101c is obtained. By sintering the fourth copper paste for joining 110d, a sintered body 101d is obtained. By sintering the fifth copper paste for joining 110e, a sintered body 101e is obtained.

[0137] Further, for the bonded body 150, a laminate in which a third member 104, a fifth copper paste for bonding 110e, a fifth member 106, a fourth copper paste for bonding 110d, a first member 102, a first copper paste for bonding 110a, and a second member 103 are laminated in this order is prepared on the side in the direction in which the weight of the third member 104 acts. In the same manner as the method for manufacturing the bonded body 125, after sintering the first copper paste for bonding 110a, the fourth copper paste for bonding 110d, and the fifth copper paste for bonding 110e, a laminated portion in which a third copper paste for bonding 110c and a fourth member 105 are laminated in this order is formed on the third member 104 and the side in the direction in which the weight of the third member 104 acts. It can also be obtained by a method including a step of sintering the third copper paste for bonding 110c in the same manner as the method for manufacturing the bonded body 125.

[0138] Further, after obtaining the bonded body 125, for the bonded body 150, a laminated portion in which a third member 104, a fifth copper paste for bonding 110e, a fifth member 106, a fourth copper paste for bonding 110d, and a first member 102 are laminated in this order is formed on the third member 104 and the side in the direction in which the weight of the third member 104 acts, and a laminated portion in which a third copper paste for bonding 110c and a fourth member 105 are laminated in this order is formed on the third member 104 and the side in the direction in which the weight of the third member 104 acts. It can also be obtained by a method including a step of sintering the third copper paste for bonding 110c, the fourth copper paste for bonding 110d, and the fifth copper paste for bonding 110e in the same manner as the method for manufacturing the bonded body 125.

[0139] In the above modification, examples of the third member 104, the fourth member 105, and the fifth member 106 are the same as those of the second member 103. For example, the third member 104 may be a metal wiring such as a copper ribbon and a metal frame, the fourth member 105 may be a terminal or a lead frame, and the fifth member 106 may be a block body such as a metal block. Further, the surface of the sintered body of the copper paste for joining the third member 104, the fourth member 105, and the fifth member 106 may contain a metal. Examples of the metal that may be included are the same as those of the metal that may be included in the surface of the first member 102 and the second member 103 that are in contact with the sintered body of the copper paste for joining. Further, the first copper paste for joining 110a, the second copper paste for joining 110b, the third copper paste for joining 110c, the fourth copper paste for joining 110d, and the fifth copper paste for joining 110e used in the above modification may be the same or different from each other.

[0140] <Joined body> The joined body of the present embodiment includes a first member, a second member, and a sintered body of the copper paste for joining of the present embodiment that joins the first member and the second member. The joined body of the present embodiment can be obtained by the method for manufacturing the joined body of the present embodiment described above.

[0141] At least one of the above first member and second member may be a semiconductor element. That is, the joined body may be a semiconductor device.

[0142] In the joined body of the present embodiment, the first member has a first electrode, the second member has a second electrode facing the first electrode, and the sintered body may join the first electrode and the second electrode.

[0143] At least one of the first electrode and the second electrode may be a metal pillar.

[0144] The first member and the second member are a wafer or a chip containing one or more semiconductors selected from the group consisting of silicon, gallium nitride, and silicon carbide, and the first electrode and the second electrode may be through electrodes provided on the semiconductor wafer and / or the semiconductor chip. This joined body can be applied to an LSI having a structure connected by TSV (Through Silicon Via).

[0145] FIG. 12 is a schematic cross-sectional view for explaining a joined body in which chip layers of TSVs are microbump-joined and a manufacturing method thereof. The joined body 52 shown in FIG. 12(a) has a structure in which a plurality of semiconductor chips 13 provided with through electrodes 14 are joined via microbumps 15 and a sintered body 16. The sintered body 16 is a sintered body of the copper paste for joining of the present embodiment.

[0146] The joined body 52 can be manufactured in the same manner as the manufacturing method of the joined body described above. For example, as shown in FIG. 12(b), after arranging the copper paste 17 for joining on the microbump 15 in one semiconductor chip 13, the other semiconductor chip 13' is arranged on one semiconductor chip 13 so that the microbump 15 and the microbump 15' in the other semiconductor chip 13' face each other via the copper paste 17 for joining, and the joined body can be obtained by connecting the microbump 15 and the microbump 15' via the sintered copper paste 17 for joining. By repeating or performing this step simultaneously, the joined body 52 is obtained.

Examples

[0147] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0148] <Preparation of Copper Paste for Joining> (Example 1) As materials containing sub-micro copper particles, 6.16 g of CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, 50% volume average particle size: 0.36 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.), 1.1956 g of dihydroterpineol (manufactured by Nippon Terpene Chemical Co., Ltd.), and 0.0044 g of 2,2-dimethylglutaric acid (melting point: 83 °C, manufactured by Fujifilm Wako Pure Chemical Corporation) were mixed with a stirrer manufactured by Shinki Co., Ltd. (product name: "Avatori Rentaro ARE-310", the same applies hereinafter) under the conditions of 2000 rpm for 1 minute. Then, dispersion treatment was performed 10 times with a three-roll mill to obtain a mixture.

[0149] After transferring the mixture obtained by the dispersion treatment to a polyethylene container, 2.64 g of 1050YF (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, 50% volume average particle size: 1.7 μm, aspect ratio 7), as a material containing flaky micro copper particles, was weighed and added to the container, and then mixed with a stirrer manufactured by Shinki Co., Ltd. under the conditions of 2000 rpm for 1 minute. Then, dispersion treatment was performed 5 times with a three-roll mill to obtain a copper paste for bonding.

[0150] (Examples 2 to 11 and Comparative Example 1) A copper paste for bonding was prepared in the same manner as in Example 1, except that the composition of the copper paste for bonding was changed to the composition shown in Table 1 or Table 2 (the unit of the numerical value is g).

[0151] (Evaluation of the copper paste for bonding) Regarding the copper paste for bonding obtained above, the bonding strength and storage stability were evaluated according to the following methods. The results are shown in Table 1 and Table 2.

[0152] (Bonding strength) The bonding strength was evaluated by shear strength. First, a bonding copper paste was stencil-printed on an oxygen-free copper plate (19 mm × 25 mm × thickness 3 mm) using a stencil mask with a thickness of 100 μm, and heating was performed under the following respective conditions to prepare measurement samples each having 10 bumps with a bump diameter of 200 μm formed on the copper plate. Heating condition 1: Gas atmosphere with a hydrogen concentration of 4.5% and a nitrogen concentration of 95.5%, heating temperature 30 °C, heating time 60 minutes Heating condition 2: Gas atmosphere with hydrogen concentration of 10% and nitrogen concentration of 90%, heating temperature of 30°C, heating time of 60 minutes Heating condition 3: Gas atmosphere with nitrogen concentration of 100%, heating temperature of 30°C, heating time of 60 minutes

[0153] The bumps of the measurement samples obtained above were horizontally pushed under the conditions of temperature 25°C, shear speed 100 μm / second, and shear height 10 μm using a universal bond tester Dage4000 (product name, manufactured by Nordson Advanced Technology Co., Ltd.) equipped with a load cell (BS-5KG, manufactured by Nordson Advanced Technology Co., Ltd.) to conduct a shear test. Subsequently, the fracture part of the bump after the test was observed with a digital microscope VHX-5000 (product name, manufactured by Keyence Corporation) to calculate the total area of the fracture surface. The bonding strength was evaluated according to the following criteria from the shear strength per unit area obtained by dividing the obtained shear strength by the total area. [Judgment criteria] A: Shear strength is 15 MPa or more B: Shear strength is 10 MPa or more and less than 15 MPa C: Shear strength is 5 MPa or more and less than 10 MPa D: Shear strength is less than 5 MPa

[0154] (Storage stability) The copper paste for bonding was stored for 168 hours in an environment of -30°C. The stored copper paste for bonding was stencil-printed onto a copper plate using a stencil mask with a thickness of 100 μm and a cylindrical opening with an opening diameter of 200 μm. The storage stability was evaluated according to the following criteria based on the printability at this time. [Judgment criteria] A: The paste can be printed without chipping. B: The paste chips. C: It cannot be printed.

[0155] [Table 1]

[0156] [Table 2]

[0157] Details of sub-micro copper particles A, micro copper particles B, and micro copper particles C in the table are as follows. Sub-micro copper particles A: CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, 50% volume average particle size: 0.36 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.) Micro copper particles B: 1050YF (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, 50% volume average particle size: 1.7 μm, aspect ratio 7) Micro copper particles C: 2L3N (manufactured by Fukuda Metal Foil & Powder Co., Ltd., product name, 50% volume average particle size: 7.2 μm, aspect ratio 5.2)

Explanation of symbols

[0158] 10…First member, 11…Metal pillar, 12…First substrate, 20…Second member, 21…Electrode pad, 22…Second substrate, 30…Copper paste for bonding, 31…Sintered body, 50, 60, 70, 90, 95…Laminate, 80, 100…Bonded body, 101, 1a, 1b, 1c, 1d, 1e, 11…Sintered body of copper paste for bonding, 102…First member, 103…Second member, 110, 110a, 110b, 110c, 110d, 110e, 120…Copper paste for bonding, 115a, 115b…Lead frame, 116…Wire, 117…Mold resin, 118…Semiconductor element, 125, 140, 150…Bonded body, 130…Semiconductor device.

Claims

1. A copper paste for bonding, comprising copper particles, dimethylglutaric acid, and a dispersion medium, wherein the copper particles include submicron copper particles and micron copper particles in amounts of 30 to 90% by mass and 10 to 70% by mass, respectively, based on the total mass of the copper particles, and the content of the dimethylglutaric acid is 0.01 to 1.5% by mass based on the total amount of the copper particles.

2. The copper paste for bonding according to claim 1, wherein the dispersion medium includes dihydroterpineol.

3. The copper paste for bonding according to claim 1 or 2, wherein the submicron copper particles are spherical or substantially spherical, and the micron copper particles are flaky.

4. The copper paste for bonding according to any one of claims 1 to 3, which is for non-pressure bonding.

5. A first step of preparing a laminate in which a first member, the copper paste for bonding according to any one of claims 1 to 3, and a second member are laminated in this order; and a second step of heating the laminate in a gas atmosphere having a hydrogen concentration of 45% or less to sinter the copper paste for bonding. A method for manufacturing a bonded body, comprising:

6. The method for manufacturing a bonded body according to claim 5, wherein the gas atmosphere is a nitrogen gas atmosphere.

7. The method for manufacturing a bonded body according to claim 5 or 6, wherein in the second step, the copper paste for bonding is heated and sintered in a state of receiving the weight of the first member or in a state of receiving the weight of the first member and a micro pressure of 0.01 MPa or less.

8. The method for manufacturing a bonded body according to any one of claims 5 to 7, wherein at least one of the first member and the second member is a semiconductor element.

9. The method for manufacturing a bonded body according to any one of claims 5 to 8, wherein in the laminate, the first member has a first electrode, the second member has a second electrode facing the first electrode, and the copper paste for bonding is provided between the first electrode and the second electrode.

10. The method for manufacturing a bonded body according to claim 9, wherein at least one of the first electrode and the second electrode is a metal pillar.

11. The method for manufacturing a bonded body according to claim 9, wherein the first member and the second member are wafers or chips including one or more semiconductors selected from the group consisting of silicon, gallium nitride, and silicon carbide, and the first electrode and the second electrode are through electrodes.

Images