JP6153076B2 - Metal nanoparticle paste, bonding material containing the same, and semiconductor device using the same - Google Patents

Description

  The present invention relates to a metal nanoparticle paste containing Cu nanoparticles, a bonding material containing the same, and a semiconductor device using the bonding material.

  Conventionally, Sn—Pb-based solder has been used for electrode bonding of semiconductor elements, but recently, a new bonding material such as lead-free solder has been demanded from the viewpoint of environmental protection. Also, in semiconductor element bonding technology, materials that can be bonded at a low temperature or without pressure are required to reduce the load on the semiconductor element.

  Metal nanoparticles such as Ag and Cu can be sintered at a temperature much lower than their melting point (sintering temperature 200 ° C. or less) when the particle size is reduced to a nanometer size such as 1000 nm or less. Therefore, application to low-temperature bonding of semiconductor elements is expected.

  However, such metal nanoparticles have a highly active surface and are likely to aggregate, so that they are usually coated with a surfactant or a polymer to ensure dispersion stability. For this reason, when heat treatment is performed when joining semiconductor elements using such metal nanoparticles, the metal nanoparticles are sintered and the coating of surfactant, polymer, etc. is decomposed and gas is generated. , Voids are generated between the metal nanoparticles. As a result, the sintered structure did not become dense at no pressure or low temperature, and a sufficiently high bonding strength could not be obtained.

  11th Symposium on “Microjoining and Assembly Technology in Electronics”, February 3-4, 2005, pp. 229-232 (Non-Patent Document 1) includes 10-50 mass% Cu powder with an average particle size of 10 μm or 30 μm. The composite paste containing Sn powder 90-50 mass% whose average particle diameter is 10 micrometers or 25 micrometers is disclosed. However, when a low temperature bonding of a semiconductor device is performed using a composite paste containing a micrometer-sized powder having an average particle diameter of 10 μm or more, a sufficiently high bonding strength cannot be obtained.

  Japanese Patent Laid-Open No. 2012-46779 (Patent Document 1) discloses metal nanoparticles having an organic coating containing a fatty acid having 8 or more carbon atoms and an aliphatic amine on the surface. It is also described that it is pyrolyzed at low temperatures.

  On the other hand, in the semiconductor device mounting technology using metal nanoparticles, conventionally, the bonding between the semiconductor device and the substrate has been performed under pressure, but the yield is reduced due to chip destruction and the cost is increased due to the addition of production processes. There was a problem, and there was a strong demand for the development of mounting technology by pressureless bonding.

JP 2012-46779 A

Ikeda, et al., “Examination of connection using Cu powder / Sn powder composite paste”, 11th Symposium on “Microjoining and Assembly Technology in Electronics”, February 3-4, 2005, pages 229-232

  However, when the surface-coated Cu nanoparticles described in Patent Document 1 are used, sintering at a low temperature is possible, but voids in the bonding layer are not necessarily sufficiently suppressed, and the bonding strength is not always sufficient. It was not expensive.

  The present invention has been made in view of the above-described problems of the prior art, and a metal nanoparticle paste capable of forming a bonding layer having sufficiently high bonding strength at a low temperature (specifically, 400 ° C. or lower), It is an object of the present invention to provide a bonding material containing the same and a semiconductor device using the same.

The present inventors have made intensive studies to achieve the above object, the use of a metal nanoparticle paste containing a Cu nanoparticle, a intermetallic compound nanoparticles of Sn and a transition metal in a specific ratio Thus, it has been found that a bonding layer having a sufficiently high bonding strength can be formed at a low temperature (specifically, 400 ° C. or lower), and the present invention has been completed.

That is, the metal nanoparticle paste of the present invention comprises 99.9 to 70% by mass of Cu nanoparticles and 0.1 to 30% by mass of intermetallic compound nanoparticles of Sn and transition metal with respect to all metal nanoparticles. It is characterized by containing.

  In such a metal nanoparticle paste, the metal nanoparticles having a diameter in the range of 1 to 1000 nm are preferably 99% or more of the total metal particles on a number basis.

In such a metal nanoparticle paste, the transition metal of the intermetallic compound nanoparticles of Sn and transition metal has a melting point of 960 ° C. or higher and an ion standard electrode potential of −0.45 V or higher. A metal is preferred.

Furthermore, in such a metal nanoparticle paste, the transition metal of the intermetallic compound nanoparticles of Sn and transition metal is selected from the group consisting of Au, Pt, Pd, Ag, Cu, Ni, Co and Fe. Preferably, the at least one metal.

  The bonding material of the present invention contains such a metal nanoparticle paste of the present invention.

  The semiconductor device of the present invention includes a semiconductor element, a substrate, and a bonding layer that bonds the semiconductor element and the substrate, and the bonding layer is formed of Cu, Sn, and a transition metal formed of the bonding material of the present invention. And a mixture layer.

In such a semiconductor device of the present invention, the mixture layer is preferably formed of metal nanoparticles having an average particle diameter of 1 to 1000 nm. The mixture layer preferably contains an intermetallic compound of Cu and CuSn and an Sn and transition metal, and the CuSn intermetallic compound is preferably Cu ₃ Sn.

Furthermore, in the semiconductor device of the present invention, an adhesive layer made of at least one metal selected from the group consisting of Ni, Co, and Ag is further provided on both surfaces of the bonding layer, and one adhesive layer is the semiconductor layer. It is preferable that it is disposed so as to be in contact with the joint portion of the element, and the other adhesion layer is disposed so as to be in contact with the joint portion of the substrate.

  The reason why the metal nanoparticle paste of the present invention makes it possible to form a bonding layer having high bonding strength at a low temperature is not necessarily clear, but the present inventors speculate as follows.

That is, since the metal nanoparticle paste of the present invention contains nanoparticles of an intermetallic compound of Sn and a transition metal (hereinafter referred to as “ Sn- transition intermetallic compound”) having a sintering temperature of 150 to 400 ° C., It is presumed that the Sn-transition intermetallic compound sintered at a temperature of 400 ° C. or lower penetrates between Cu nanoparticles, thereby filling voids, improving the sintered density, and increasing the bonding strength of the bonding layer.

Moreover, Cu nanoparticle and Sn-transition intermetallic compound nanoparticle easily react with active surface atoms at a low temperature in a short time, and contains nanoparticles of an intermetallic compound of Sn and a transition metal that is a refractory metal. By doing so, the diffusion of Sn is suppressed, and a stable and high heat-resistant Cu ₃ Sn that is a compound having a high Cu-rich strength as a CuSn intermetallic compound is likely to be preferentially formed. For this reason, Sn-transition intermetallic compound nanoparticles that have penetrated between Cu nanoparticles easily form a strong, stable, and high heat-resistant Cu ₃ Sn intermetallic compound in the vicinity of the interface. It is assumed that a bonding layer is formed. Furthermore, since the oxide layer on the surface of the Cu nanoparticles is easily reduced by the reduction effect of the Sn-transition intermetallic compound nanoparticles, the Cu nanoparticles are easily sintered, the sintered density is improved, and the bonding layer has a high bonding strength. Is presumed to be formed. Moreover, since the nanoparticles of Sn and a high melting point transition metal have a function of strengthening the sintered layer, it is assumed that the bonding strength is sufficiently improved.

  On the other hand, when Sn particles having a micrometer size are used, the Sn particles do not permeate between the Cu particles, and the voids between the Cu particles are not sufficiently filled. Therefore, it is assumed that sufficient bonding strength cannot be obtained. In addition, Cu particles and Sn particles of micrometer size are not highly active on the surface, so it is difficult to sinter at low temperatures, CuSn intermetallic compounds are not easily formed, and it is assumed that the bonding strength is not sufficiently high. Is done.

  In addition, when the bonding layer is formed by heat treatment at a relatively low temperature or heat treatment without pressure using only Cu nanoparticles having an organic coating on the surface, gas generated during decomposition of the organic coating or points between Cu nanoparticles It is presumed that voids are easy to be formed due to the bonding state (linking state) in, and a structure having a low sintered density is formed. For this reason, it is speculated that the bonding strength decreases when only Cu nanoparticles having an organic coating on the surface are used.

  According to the present invention, a metal nanoparticle paste capable of forming a bonding layer having a sufficiently high bonding strength at a low temperature (specifically, 400 ° C. or lower), a bonding material containing the same, and a semiconductor using the same An apparatus can be provided.

It is a schematic diagram which shows one embodiment of the semiconductor device of this invention. It is a schematic diagram which shows another embodiment of the semiconductor device of this invention. It is a schematic diagram which shows another embodiment of the semiconductor device of this invention. It is a schematic diagram which shows another embodiment of the semiconductor device of this invention. 2 is a scanning electron microscope (SEM) photograph (scale bar: 40 μm) of Sn particles used in Preparation Example 1. FIG. 6 is a graph showing an XRD spectrum of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 3. FIG. 4 is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 3. FIG. 6 is a graph showing an XRD spectrum of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 4. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the Sn-transition intermetallic compound nanoparticles produced in Preparation Example 4. 6 is a graph showing an XRD spectrum of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 5. FIG. 6 is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 5. FIG. 14 is a graph showing an XRD spectrum of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 6. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the Sn-transition intermetallic compound nanoparticles produced in Preparation Example 6. 10 is a graph showing an XRD spectrum of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 7. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the Sn-transition intermetallic compound nanoparticles produced in Preparation Example 7. It is a schematic diagram which shows the joined body for shear strength measurement produced in the Example. It is a graph which shows the XRD spectrum of the adhesion layer upper part vicinity of the joining layer produced in Example 1-2. It is a graph which shows the XRD spectrum of the adhesion layer vicinity of the upper side of the joining layer produced in Example 1-4. It is a graph which shows the XRD spectrum of the adhesion layer upper part vicinity of the joining layer produced in Example 1-6. It is a graph which shows the XRD spectrum of the adhesion layer vicinity of the upper side of the joining layer produced in Example 1-8. It is a scanning electron micrograph of the adhesion layer vicinity of the upper side of the joining layer produced in Example 1-9. It is a scanning electron micrograph of the adhesion layer vicinity of the lower side of the joining layer produced in Example 1-9. It is a scanning electron micrograph of the adhesion layer vicinity of the upper side of the joining layer produced in Example 1-10. It is a scanning electron micrograph of the adhesion layer vicinity of the lower side of the joining layer produced in Example 1-10. It is a graph which shows the XRD spectrum of the NiSn micron particle used in Comparative Examples 3-2 and 3-3. 6 is a scanning electron microscope (SEM) photograph of a micron-sized aggregate of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 8. FIG. 10 is a graph of an EDS spectrum of a micron-sized aggregate of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 8. 10 is a transmission electron microscope (TEM) photograph of Sn-transition intermetallic compound nanoparticles prepared in Preparation Example 8.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, the metal nanoparticle paste of the present invention and the bonding material of the present invention containing the metal nanoparticle paste will be described. The metal nanoparticle paste of the present invention contains Cu nanoparticles and Sn-transition intermetallic compound nanoparticles at a predetermined ratio. The metal nanoparticle paste of the present invention can be sintered by heat treatment at a low temperature (specifically, 400 ° C. or lower) to form a bonding layer having a sufficiently high bonding strength. In addition, when the metal nanoparticle paste of the present invention is used, a bonding layer having a sufficiently high bonding strength can be formed even without pressure during heat treatment.

(Cu nanoparticles)
In the present invention, Cu particles having a diameter in the range of 1 to 1000 nm are referred to as “Cu nanoparticles”. The diameter of Cu particles can be measured by transmission electron microscope (TEM) observation. In the present invention, the ratio of Cu nanoparticles to the total Cu particles shown below and the average of Cu particles (including Cu nanoparticles) are as follows. The particle diameter is a value obtained by randomly extracting 200 Cu particles and measuring their diameters in the TEM observation.

  In the metal nanoparticle paste of the present invention, such Cu nanoparticles (those having a diameter in the range of 1 to 1000 nm) are preferably 99% or more of all Cu particles on a number basis, and all Cu particles are The Cu nanoparticles are particularly preferable. When the ratio of Cu nanoparticles is less than the lower limit, the sintering temperature of Cu particles becomes high, so that bonding of Cu particles due to heating at a low temperature (specifically, 400 ° C. or less) hardly occurs. The strength tends to decrease.

  Moreover, as an average particle diameter of Cu particle | grains (a Cu nanoparticle is included) contained in the metal nanoparticle paste of this invention, 10-1000 nm is preferable, 30-500 nm is more preferable, 50-400 nm is especially preferable. When the average particle diameter of the Cu particles is less than the lower limit, the surface ratio to the bulk is increased, so that the surface of the Cu nanoparticles is easily oxidized in the atmosphere. As a result, the Cu nanoparticles are aggregated in the metal nanoparticle paste. Or the oxidation component cannot be sufficiently removed by heat treatment at the time of bonding, and the characteristics of the bonding material such as bonding strength, conductivity, and thermal conductivity tend to be deteriorated. However, if Cu nanoparticles are handled in an inert gas or a reducing gas atmosphere, the surface of the Cu nanoparticles is less likely to be oxidized, and the above problems are less likely to occur. Therefore, Cu nanoparticles having an average particle diameter of less than the lower limit are also included. It can be used for the metal nanoparticle paste of the present invention. In addition, when using Cu nanoparticles with an organic coating, the organic coating remains higher than the Cu nanoparticles in proportion to the organic coating. There is a tendency that characteristics of the bonding material such as conductivity, thermal conductivity and the like are deteriorated. On the other hand, if the average particle diameter of the Cu particles exceeds the upper limit, the particle size effect is small, so the sintering temperature of the Cu particles increases, and the Cu particles are heated by heating at a low temperature (specifically, 400 ° C. or less). Bonding is difficult to occur, and as a result, the bonding strength tends to decrease.

  Examples of such Cu nanoparticles include surface-coated Cu nanoparticles including Cu nanoparticles and an organic coating containing a fatty acid and an aliphatic amine disposed on the surface of the Cu nanoparticles. The organic coating can be thermally decomposed at a low temperature (specifically, 400 ° C. or lower). The surface-coated Cu nanoparticles can be produced according to the method described in JP 2012-46779 A. That is, Cu nanoparticles are formed by reducing a Cu salt insoluble in the alcohol solvent in the coexistence of a fatty acid and an aliphatic amine in an alcohol solvent, and the fatty acid and the surface of the Cu nanoparticles are formed. The surface-coated Cu nanoparticles can be produced by forming an organic coating containing an aliphatic amine. Here, examples of the Cu salt include copper carbonate and copper hydroxide. Examples of fatty acids include saturated fatty acids such as octanoic acid, decanoic acid, dodecanoic acid, myristic acid, palmitic acid and stearic acid, and unsaturated fatty acids such as oleic acid. Aliphatic amines include octylamine, decylamine and dodecylamine. , Saturated aliphatic amines such as myristylamine, palmitylamine, stearylamine, and unsaturated aliphatic amines such as oleylamine, and by changing the carbon number of the hydrocarbon chain of fatty acids and aliphatic amines, The particle size can be adjusted.

  In the present invention, commercially available Cu nanoparticles such as Cu nanoparticles “Cu60-BtTP” manufactured by IOX Co., Ltd. and copper nanoparticle powders manufactured by Tech Science Co., Ltd. can also be used. Furthermore, Cu nanoparticles dispersed in a solvent can also be used. As such Cu nanoparticle dispersion liquid, copper nanoparticle dispersion liquid manufactured by Tateyama Scientific Industry Co., Ltd., “NCU-09” manufactured by Daiken Chemical Industry Co., Ltd., copper nanoparticle manufactured by Harima Chemical Group Co., Ltd. Commercial products such as dispersions can be mentioned.

(Sn-transition intermetallic compound nanoparticles)
In the present invention, Sn-transition intermetallic compound nanoparticles having a diameter in the range of 1 to 1000 nm are referred to as “Sn-transition intermetallic compound nanoparticles”. The diameter of the Sn-transition intermetallic compound nanoparticles can be measured by observation with a transmission electron microscope (TEM). In the present invention, the Sn-transition metal interparticles with respect to all the Sn-transition intermetallic compounds shown below are used. The ratio of compound nanoparticles and the average particle diameter of Sn-transition intermetallic compound particles (including Sn-transition intermetallic compound nanoparticles) were determined by randomly selecting 200 Sn-transition intermetallic compound particles in the TEM observation. It is set as the value calculated | required by extracting and measuring these diameters.

  In the metal nanoparticle paste of the present invention, such Sn-transition intermetallic compound nanoparticles (having a diameter in the range of 1 to 1000 nm) account for 99% or more of all Sn-transition intermetallic compound particles on a number basis. It is preferable that all of the Sn-transition intermetallic compound particles are the Sn-transition intermetallic compound nanoparticles. When the ratio of Sn-transition intermetallic compound nanoparticles is less than the lower limit, the amount of Sn-transition intermetallic compound nanoparticles entering between the Cu nanoparticles decreases, and the voids between the Cu nanoparticles are not sufficiently filled. Voids are generated and the bonding strength tends not to be sufficiently improved.

  Moreover, as an average particle diameter of Sn-transition intermetallic compound particle | grains (including Sn-transition intermetallic compound nanoparticle) contained in the metal nanoparticle paste of this invention, 5-1000 nm is preferable and 10-500 nm is more preferable. 20 to 250 nm is particularly preferable. When the average particle diameter of the Sn-transition intermetallic compound particles is less than the lower limit, the surface ratio to the bulk increases, so that the surface of the Sn nanoparticles is easily oxidized in the atmosphere. As a result, Sn in the metal nanoparticle paste -Aggregation between transition metal intermetallic nanoparticles occurs, or the oxidation component cannot be sufficiently removed by heat treatment at the time of bonding, and the characteristics of the bonding material such as bonding strength, conductivity, and thermal conductivity tend to be deteriorated. However, if the Sn-transition intermetallic compound nanoparticles are handled in an inert gas or reducing gas atmosphere, the surface of the Sn-transition intermetallic compound nanoparticles is unlikely to oxidize and the above-mentioned problems are unlikely to occur. Sn-transition intermetallic compound nanoparticles having a diameter less than the lower limit can also be used in the metal nanoparticle paste of the present invention. In addition, when using Sn-transition intermetallic compound nanoparticles provided with an organic coating, the organic coating is more than the Sn-transition intermetallic compound nanoparticles. It remains without being decomposed, and the properties of the bonding material such as bonding strength, conductivity, and thermal conductivity tend to deteriorate. On the other hand, when the average particle diameter of the Sn-transition intermetallic compound particles exceeds the upper limit, the Sn-transition intermetallic compound nanoparticles cannot enter between the Cu nanoparticles, and the voids between the Cu nanoparticles are not sufficiently filled. , Voids are formed, and the bonding strength tends not to be sufficiently improved.

In the metal nanoparticle paste of the present invention, the transition metal of such Sn-transition intermetallic compound nanoparticles has a melting point of 960 ° C. or higher and an ion standard electrode potential of −0.45 V or higher. A metal is preferred. By using a metal having a melting point of 960 ° C. or higher as the transition metal, the diffusion of Sn is suppressed, and a stable and high heat-resistant Cu ₃ Sn that is a compound having a high Cu-rich strength is easily formed. -The transition intermetallic compound itself tends to have the effect of high strength. A metal having a melting point of 1000 ° C. or higher is more preferable. In addition, by using a metal having an ion standard electrode potential of −0.45 V or more as the transition metal, the oxidation resistance of the Sn-transition intermetallic compound is improved, and high strength can be achieved by suppressing oxidation. It tends to be effective. It is more preferable to use a metal having an ion standard electrode potential of −0.3 V or higher.

In the metal nanoparticle paste of the present invention, the transition metal of such Sn-transition intermetallic compound nanoparticles is selected from the group consisting of Au, Pt, Pd, Ag, Cu, Ni, Co and Fe. It is preferably at least one metal, and more preferably Pt, Ag, Cu, or Ni. By using at least one metal selected from the group consisting of Au, Pt, Pd, Ag, Cu, Ni, Co and Fe as the transition metal, Sn diffusion is suppressed, and a compound having high Cu-rich strength The stable and highly heat-resistant Cu ₃ Sn is easily formed, and the Sn-transition intermetallic compound itself tends to have a sufficient effect of high strength.

  In addition, the Sn-transition intermetallic compound nanoparticles are not particularly limited, and known Sn-transition intermetallic compound nanoparticles can be appropriately used. For example, Sn particles and transition metal element ions are reacted in a solution, and transition metal element ions are reduced to synthesize Sn-transition intermetallic compound nanoparticles. If the transition metal element ion is a noble metal than Sn (for example, Pb, Bi, Cu, Ag, Pd, Pt, Au, etc.), the ionization of Sn and the reduction of metal ions without using a reducing agent However, since the reduction takes time, it is preferable to react in a reducing solvent in order to promote the reduction.

  Such reducing solvents include primary monoalcohols such as methanol, ethanol, propyl alcohol, butanol, hexanol, octanol, decanol, oleyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, Diols such as butanediol, pentanediol and hexanediol, triols such as glycerin, primary amines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, and oleylamine can be used. . A secondary alcohol may be used in place of the primary alcohol, and a secondary or tertiary amine may be used in place of the primary amine. A solvent miscible with these reducing solvents may be appropriately mixed. Examples of miscible solvents include hexane, benzene, toluene, dimethyl ether, diethyl ether, diphenyl ether, chloroform, ethyl acetate, dichloromethane, THF, acetone, acetonitrile, DMF, water, and the like. In addition to these reducing solvents and miscible solvents, a modifier may be added for shape control of the nanoparticles. Such modifiers include phosphines such as tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, propionic acid, butyric acid, hexanoic acid, octanoic acid, decanoic acid, dodecane. Fatty acids such as acid, myristic acid, palmitic acid, stearic acid and oleic acid can be used. In addition, amines added as reducing agents can also be used as modifiers.

  As the Sn particles used as a raw material for such Sn-transition intermetallic compound nanoparticles, it is preferable to use Sn nanoparticles having a particle size of 1000 nm or less. In addition, when obtaining a Sn-transition intermetallic compound with a metal nobler than Sn, submicron particles having a particle size of 1 to 100 μm may be used. This is because, due to the presence of noble metal ions, Sn elution is accelerated by the standard electrode potential difference, so that Sn-transition intermetallic compound nanoparticles can be obtained without using nano-sized particles. Moreover, when using Sn nanoparticle as a raw material of Sn-transition intermetallic compound nanoparticle, as an average particle diameter, 5-500 nm is preferable and 10-300 nm is more preferable. When the average particle diameter of the Sn particles is less than the lower limit, the active action of the Sn nanoparticles is too strong, and there is a tendency that the oxidation of the particles and the aggregation of the particles easily occur. On the other hand, if the average particle diameter of the Sn particles exceeds the upper limit, the reaction between the transition metal element and Sn does not proceed sufficiently to the inside, and an intermetallic compound tends to be hardly formed.

  Examples of such Sn particles include surface-coated Sn nanoparticles including Sn nanoparticles and an organic coating containing an aliphatic amine disposed on the surface of the Sn nanoparticles. The organic coating can be thermally decomposed at a low temperature (specifically, 400 ° C. or lower). The surface-coated Sn nanoparticles can be produced according to the method described in the specification of Japanese Patent Application No. 2012-130888. That is, Sn nanoparticles are formed by reducing Sn ions in the presence of an aliphatic amine and a quaternary ammonium borohydride in an organic solvent, and the aliphatic amine is formed on the surface of the Sn nanoparticles. The surface-coated Sn nanoparticles can be produced by forming an organic film to be contained. Here, the Sn ion source is not particularly limited as long as it is an Sn compound that is soluble in an organic solvent and generates Sn ions. For example, tin chloride, tin fluoride, tin bromide, tin iodide, acetic acid Examples thereof include tin, tin sulfate, tin nitrate, and acetylacetonatotin. Examples of aliphatic amines include saturated aliphatic amines such as octylamine, decylamine, dodecylamine, myristylamine, palmitylamine, stearylamine, and unsaturated aliphatic amines such as oleylamine. The particle diameter of Sn nanoparticles can be adjusted by changing the number of carbon atoms.

  In addition, in the present invention, commercially available Sn nanoparticles such as Sn nano powder manufactured by Nippon Ion Co., Ltd., Sn powder manufactured by Wako Pure Chemical Industries, Ltd., Sn powder manufactured by Kojundo Chemical Laboratory Co., Ltd., etc. Sn submicron particles can also be used. Furthermore, Sn nanoparticles dispersed in a solvent can also be used. Examples of such Sn nanoparticle dispersion include commercially available products such as Sn nanoparticle dispersion manufactured by Tateyama Kagaku Kogyo Co., Ltd.

  The shape of the Sn-transition intermetallic compound nanoparticles of the present invention is not particularly limited, and examples thereof include a spherical shape, a rectangular shape, a cubic shape, and a polyhedral shape. In addition, it is preferable that it is a rectangular shape, a cube shape, and a polyhedron shape from a viewpoint that particles are closely packed and a sintered density can be improved.

In the Sn-transition intermetallic compound nanoparticles of the present invention, the Sn-transition intermetallic compound is a compound composed of Sn and a transition metal, and as such an Sn-transition intermetallic compound, Pt ₃ Sn _{, Ag 3 Sn, Cu 6 Sn} 5, Ni 3 Sn 2, Ni 3 Sn, Ni 3 Sn 4, Cu 3 Sn, PtSn, Pt 2 Sn 3, PtSn 2, PtSn 4, AuSn, AuSn 2, AuSn 4, Pd ₃ Sn, Pd ₂ Sn, PdSn, PdSn ₂ , PdSn ₃ , PdSn ₄ , Co ₃ Sn ₂ , CoSn, CoSn ₂ , FeSn, FeSn ₂ , (Ni, Cu) ₆ Sn ₅ , (Ni, Cu) ₃ Sn, _{(Ni, Cu)} Sn 6, or _{(Pt, Ni) 3 Sn,} (Ag, Ni) 3 Sn, (Pt, Cu) 3 Sn, (Ag, Cu) 3 Sn At least one more preferred intermetallic compound selected from the group consisting _{of, Pt 3 Sn, Ag 3 Sn} , Cu 6 Sn 5, Ni 3 Sn 2, (Ni, Cu) 6 Sn 5, (Ni, Cu) 3 Particularly preferred is Sn, (Ni, Cu) Sn ₆ . By using at least one intermetallic compound selected from the above as Sn-transition intermetallic compound nanoparticles, the diffusion of Sn is suppressed, and a stable and high heat-resistant Cu ₃ Sn that is a compound with high Cu-rich strength. Tends to be formed, and the Sn-transition intermetallic compound itself tends to be sufficiently effective.

(Metal nanoparticle paste)
The metal nanoparticle paste of the present invention contains such Cu nanoparticles and Sn-transition intermetallic compound nanoparticles at a predetermined ratio. The ratio of Cu nanoparticles and Sn-transition intermetallic compound nanoparticles in the metal nanoparticle paste of the present invention is 99.9 to 70% by mass of Cu nanoparticles with respect to all metal nanoparticles, and Sn-transition metal Intermetallic nanoparticles are 0.1-30 mass%. When the content of the Sn-transition intermetallic compound nanoparticles is less than the lower limit (that is, the content of the Cu nanoparticles exceeds the upper limit), the amount of Sn nanoparticles that enter between the Cu nanoparticles decreases, and Cu Since voids between the nanoparticles are not sufficiently filled, voids are generated and the bonding strength is reduced. Moreover, since the CuSn intermetallic compound is not generated, the bonding strength is reduced. On the other hand, when the content of the Sn-transition intermetallic compound nanoparticles exceeds the upper limit (that is, the content of the Cu nanoparticles is less than the lower limit), the bonding material such as bonding strength, conductivity, thermal conductivity, etc. Characteristics are degraded. Further, from the viewpoint of higher bonding strength, it is preferable that the content of Cu nanoparticles is 98 to 80% by mass and the content of Sn-transition intermetallic compound nanoparticles is 2 to 20% by mass, It is more preferable that the content of Cu nanoparticles is 97 to 85% by mass and the content of Sn-transition intermetallic compound nanoparticles is 3 to 15% by mass. In addition, in the ratio of Cu nanoparticle and Sn-transition intermetallic compound nanoparticle, these total amount is 100 mass% with respect to all the metal nanoparticles.

  In the metal nanoparticle paste of the present invention, metal nanoparticles (thickness in the range of 1 to 1000 nm, Cu nanoparticles + Sn—transition intermetallic compound nanoparticles) are all metal particles (Cu particles + Sn) on a number basis. -99% or more of the transition intermetallic compound particles), and it is particularly preferable that all the metal particles are the metal nanoparticles. When the ratio of the metal nanoparticles is less than the lower limit, the sintering temperature of the metal particles becomes high, so that the metal particles are hardly bonded by heating at a low temperature (specifically, 400 ° C. or less). The strength tends to decrease.

  In such a metal nanoparticle paste of the present invention, for example, both of the Cu nanoparticles and Sn-transition intermetallic compound nanoparticles are mixed so that a predetermined ratio is obtained, and the obtained mixed nanoparticles are pasty. After mixing with a solvent such as an organic solvent or preparing a Cu nanoparticle paste and Sn-transition intermetallic compound nanoparticle paste, Cu nanoparticles and Sn-transition intermetallic compound nanoparticles are in a predetermined ratio. After mixing both or preparing a Cu nanoparticle dispersion and a Sn-transition intermetallic compound nanoparticle dispersion, the Cu nanoparticles and the Sn-transition intermetallic compound nanoparticles are in a predetermined ratio. Thus, both can be mixed, and the resulting dispersion of mixed nanoparticles can be concentrated by using an evaporator or the like until a paste is formed.

  These nanoparticle pastes and dispersions may be prepared by mixing Cu nanoparticles and Sn-transition intermetallic compound nanoparticles with a solvent such as an organic solvent, respectively. A paste or dispersion may be used.

  Although there is no restriction | limiting in particular as an organic solvent used for the metal nanoparticle paste of this invention, For example, C5-C18 alkanes, such as tetradecane; C1-C20, such as 1-butanol, decanol, and isopropyl alcohol Monoalcohols; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol; triols such as glycerin; cyclic alcohols such as α-terpineol; ketones such as acetone, methyl ethyl ketone, and diethyl ketone; tetrahydrofuran, diethyl Examples include ethers such as ether and butyl carbitol; esters such as ethyl acetate and butyl carbitol acetate; and aromatic compounds such as benzene, toluene and xylene. Moreover, you may add additives, such as viscosity modifiers, such as a cellulose derivative (for example, ethyl cellulose, hydroxyethyl cellulose) and a glyceride (for example, castor oil) to the metal nanoparticle paste of this invention. .

  The mixing method of the nanoparticles and the solvent is not particularly limited, and examples thereof include a method using a known stirring device such as a rotation / revolution mixer, a ball mill, or a stirrer.

<Semiconductor device>
Next, the semiconductor device of the present invention will be described. The semiconductor device of the present invention includes a semiconductor element, a substrate, and a bonding layer for bonding the semiconductor element and the substrate, and the bonding layer includes a bonding material containing the metal nanoparticle paste of the present invention (hereinafter, “ It is a mixture layer of Cu, Sn, and a transition metal formed by the “joining material of the present invention”. Moreover, the semiconductor device of this invention WHEREIN: It is preferable that the said mixture layer is formed with the metal nanoparticle with an average particle diameter of 1-1000 nm. Furthermore, it is preferable that the mixture layer contains Cu, a CuSn intermetallic compound, and a Sn-transition intermetallic compound from the viewpoint of sufficiently increasing the bonding strength. An example of such a CuSn intermetallic compound is Cu ₃ Sn. Examples of the transition metal of such an Sn-transition intermetallic compound include at least one metal selected from the group consisting of Au, Pt, Pd, Ag, Cu, Ni, Co, and Fe. Furthermore, in the semiconductor device of the present invention, it is preferable that an adhesive layer made of at least one of Ni, Co, and Ag is further provided on both surfaces of the mixture layer. In this case, one adhesion layer is disposed so as to contact the bonding portion of the semiconductor element, and the other adhesion layer is disposed so as to contact the bonding portion of the substrate.

  There is no restriction | limiting in particular as a semiconductor element which comprises the semiconductor device of this invention, For example, a power element, LSI, resistance, a capacitor | condenser etc. are mentioned. Moreover, there is no restriction | limiting in particular as a board | substrate, For example, a lead frame, the ceramic substrate in which the electrode was formed, a mounting substrate, etc. are mentioned. An example of the lead frame is a copper alloy lead frame. Examples of the ceramic substrate on which the electrode is formed include a DBC (Direct Bond Copper: registered trademark) substrate and an active metal bonded (AMC: Active Metal Copper) substrate. Examples of the mounting substrate include an alumina substrate on which electrodes are formed, a low temperature co-fired ceramics (LTCC) substrate, a glass epoxy substrate, and the like.

  Hereinafter, preferred embodiments of the semiconductor device of the present invention will be described in detail with reference to the drawings. However, the semiconductor device of the present invention is not limited to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

  FIG. 1 is a schematic view showing an embodiment of a semiconductor device of the present invention. This semiconductor device includes a semiconductor element 1, an upper substrate 2a, a lower substrate 2b, bonding layers 3a and 3b, a signal terminal 5, a bonding wire 6, and a molding resin 7. An upper substrate 2a is bonded to the upper surface of the semiconductor element 1 via a bonding layer 3a. A lower substrate 2b is bonded to the lower surface of the semiconductor element 1 through a bonding layer 3b. A part of the upper surface of the semiconductor element 1 and the signal element 5 are electrically connected by a bonding wire 6. The semiconductor element 1, a part of the upper substrate 2 a, a part of the lower substrate 2 b, the bonding layers 3 a and 3 b, a part of the signal terminal 5, and the bonding wire 6 are covered with a mold resin 7. Further, the protruding portion 2 c of the upper substrate 2 a, the protruding portion 2 d of the lower substrate 2 b, and a part of the signal terminal 5 protrude outside the mold resin 7.

  Such a semiconductor device can be manufactured as follows. That is, first, the bonding material of the present invention is applied to one of the upper surface of the semiconductor element 1 and the lower surface of the upper substrate 2a to form a bonding material layer. Also, the bonding material of the present invention is applied to either the lower surface of the semiconductor element 1 or the upper surface of the lower substrate 2b to form a bonding material layer. Although there is no restriction | limiting in particular as thickness of these joining material layers, When productivity and joining resistance are considered, 1-500 micrometers is preferable, 50-400 micrometers is more preferable, 100-300 micrometers is especially preferable. Examples of the method for applying the bonding material include a screen printing method, an ink jet method, a dip method, and a flexographic printing method. Moreover, such application | coating can be performed in air | atmosphere or inert gas atmosphere.

  Next, the semiconductor element 1 and the upper substrate 2a are bonded together so that the bonding material layer is disposed between the upper surface of the semiconductor element 1 and the lower surface of the upper substrate 2a. The semiconductor element 1 and the lower substrate 2b are bonded together so that the bonding material layer is disposed between the upper surface of the lower substrate 2b. At this time, pressure may be applied so that bubbles do not enter the bonding material layer. The bonding may be performed in a vacuum, but the bonding material of the present invention can be bonded in the air because the oxidation of Cu nanoparticles in the air is suppressed.

  In this way, the bonded body in which the semiconductor element 1 and the upper substrate 2a and the semiconductor element 1 and the lower substrate 2b are bonded together is subjected to heat treatment to sinter the bonding material, thereby forming the bonding layers 3a and 3b. Thereby, the semiconductor element 1 and the upper substrate 2a are bonded via the bonding layer 3a, and the semiconductor element 1 and the lower substrate 2b are bonded via the bonding layer 3b. Since the bonding layers 3a and 3b formed of the bonding material of the present invention are a mixture layer of Cu, Sn, and a transition metal, the bonding strength is sufficiently excellent. Since the bonding layers 3a and 3b contain Sn, they tend to act as stress relaxation layers. On the other hand, since the bonding layer made of only Cu has high hardness, the stress is not relieved, and, for example, there is a problem that the semiconductor element is destroyed during the cooling and heating cycle.

Furthermore, the bonding layer according to the present invention preferably contains a CuSn intermetallic compound, and the CuSn intermetallic compound is preferably Cu ₃ Sn. By including such a CuSn intermetallic compound, the bonding strength of the bonding layer tends to be sufficiently improved. In the bonding layer according to the present invention, CuSn intermetallic compounds are formed during sintering, so that the Cu nanoparticles are not completely sintered, and the particle diameter in the bonding material of the present invention is maintained. However, it tends to be sintered. As a result, the obtained bonding layer (mixture layer) tends to be formed of metal nanoparticles having an average particle diameter of 1 to 1000 nm (more preferably 10 to 1000 nm). The bonding layer formed of such metal nanoparticles can be confirmed by observation with a scanning electron microscope or the like.

  Although there is no restriction | limiting in particular as temperature of heat processing, 150-450 degreeC is preferable and 250-400 degreeC is more preferable. When the heat treatment temperature is less than the lower limit, the solvent contained in the bonding material tends to remain in the bonding layers 3a and 3b, and sufficient bonding strength tends not to be obtained. In some cases, the temperature exceeds the heat-resistant temperature of the semiconductor element, the thermal stress increases, the warp or peeling tends to occur, and the bonding layer may be oxidized.

  Such heat treatment is preferably performed in an inert gas or reducing gas atmosphere. Furthermore, when the bonding material of the present invention is used, bonding can be performed without applying pressure, but bonding strength tends to be improved by bonding while applying pressure.

  In the semiconductor device of the present invention, as shown in FIG. 2, between the semiconductor element 1 and the bonding layer 3a, between the upper substrate 2a and the bonding layer 3a, between the semiconductor element 1 and the bonding layer 3b, It is preferable that adhesion layers 4a and 4b made of at least one of Ni, Co, and Ag are disposed between the lower substrate 2b and the bonding layer 3a. By forming such an adhesion layer, the bonding strength tends to be further improved.

  The thickness of such an adhesion layer is not particularly limited because high bonding strength can be obtained if it is 1 nm or more, but it is preferably 10 μm or less in consideration of the production cost of the semiconductor device, the electric resistance of the adhesion layer, and the like. Moreover, 200 nm or less is more preferable from a viewpoint of reducing production cost more.

  Such a semiconductor device can be manufactured as follows. That is, first, the adhesion layer is formed on both surfaces of the semiconductor element 1, the lower surface of the upper substrate 2a, and the upper surface of the lower substrate 2b. Examples of the method for forming the adhesion layer include a sputtering method, a plating method, and a coating method.

  In the case of forming an adhesion layer by sputtering, first, an object to be coated such as a semiconductor element or a substrate is inserted into a vacuum chamber, and the inside of the chamber is decompressed. After the inside of the chamber is in a vacuum state, argon gas is introduced, and RF plasma is generated on the object to be coated to remove impurities on the surface of the object to be coated. Thereafter, RF sputtering is performed using a target of the material of the adhesion layer to be formed (for example, Ni, Co, or Ag). Thereby, an adhesion layer can be formed on the surface of an object to be coated. Although there is no restriction | limiting in particular as a temperature of the to-be-coated object at the time of forming a contact | glue layer, For example, room temperature (about 25 degreeC)-450 degreeC are preferable. If the temperature of the object to be coated exceeds the upper limit, the heat resistance temperature of the semiconductor element may be exceeded, the thermal stress increases, and warping or peeling tends to occur.

  In the case of forming an adhesion layer by a coating method, first, a metal mask method, an ink jet method, a spin coating method, a dip method, an object to be coated such as a semiconductor element or a substrate in the air or an inert gas atmosphere, A paste or ink containing a material (for example, Ni, Co, or Ag) of the adhesion layer to be formed is applied by a method such as a screen printing method. As the paste or ink, a paste prepared by mixing metal particles and a solvent may be used, or a commercially available paste containing metal particles may be used. Examples of commercially available pastes containing nickel particles include nickel nanoparticle dispersions manufactured by Tateyama Kagaku Kogyo Co., Ltd., “MM12-800TO” manufactured by Daiken Chemical Industries, Ltd., and the like. Examples of commercially available pastes containing cobalt particles include cobalt nanoparticle dispersions manufactured by Tateyama Science Co., Ltd. Examples of commercially available pastes containing silver particles include “AGIN-W4A” manufactured by Sumitomo Electric Industries, Ltd. and “NPS-J-HTB” manufactured by Harima Chemical Co., Ltd. Thus, the said adhesion layer is formed by heat-processing the to-be-coated object which apply | coated the paste in inert gas or reducing gas atmosphere. Note that heat treatment may be performed in an oxidizing atmosphere before heat treatment in an inert gas or reducing gas atmosphere. Although there is no restriction | limiting in particular as atmospheric temperature in heat processing, 150-450 degreeC is preferable. When the atmospheric temperature is lower than the lower limit, the organic components (for example, organic solvent and organic modifier) in the paste are not sufficiently volatilized and removed, and the content of the organic components in the adhesion layer tends to increase. On the other hand, when the upper limit is exceeded, the heat resistance temperature of the semiconductor element may be exceeded, the thermal stress increases, and warping and peeling tend to occur.

  Next, as in the case of the semiconductor device shown in FIG. 1, a bonding material layer is formed on the surface of the adhesion layer thus formed using the bonding material of the present invention, and the semiconductor element 1 and the upper substrate 2a. The semiconductor element 1 and the lower substrate 2b are bonded together, and the obtained bonded body is subjected to heat treatment to sinter the bonding material, thereby forming the bonding layers 3a and 3b. Thus, the semiconductor element 1 and the upper substrate 2a are bonded via the bonding layer 3a and the adhesion layers 4a and 4b, and the semiconductor element 1 and the lower substrate 2b are bonded via the bonding layer 3b and the adhesion layers 4a and 4b. The Thus, by forming the adhesion layer made of at least one metal of Ni, Co, and Ag, the bonding strength tends to be further improved.

  The reason why the bonding strength is further improved by forming the adhesion layer is not necessarily clear, but the present inventors infer as follows. That is, the passive oxide layer formed on the metal surface such as Ni is thin and easily reduced, and the metal layer such as Ni also has an action of reducing the oxide layer on the surface of the Cu nanoparticles. In addition, since a metal layer such as Ni has very high wettability with Cu nanoparticles during sintering, it is presumed that an adhesion layer having high bonding strength can be formed even without pressure.

  As described above, the semiconductor device of the present invention has been described by taking the case where the semiconductor element is sandwiched between the upper electrode and the lower electrode (FIGS. 1 and 2) as an example, but the semiconductor device of the present invention is not limited to these, For example, as shown in FIGS. 3 and 4, a semiconductor device in which only one surface of a semiconductor element is bonded to a substrate through a bonding layer can be given.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Various metal nanoparticles used in the examples and comparative examples were prepared by the following method.

(Preparation Example 1)
<Preparation of Cu nanoparticles>
Cu nanoparticles were prepared according to the method described in JP 2012-46779 A. That is, when 300 ml of ethylene glycol (HO (CH ₂ ) ₂ OH) was put into a flask and 60 mmol of copper carbonate (CuCO ₃ · Cu (OH) ₂ · H ₂ O) was added thereto, the copper carbonate was hardly added to ethylene glycol. It precipitated without dissolving. To this was added 90 mmol of decanoic acid (C ₉ H ₁₉ COOH) and 30 mmol of decylamine (C ₁₀ H ₂₁ NH ₂ ), and then the mixture was heated to reflux for 1 hour at the boiling point of ethylene glycol while flowing nitrogen gas at 1 L / min. However, fine particles were generated. The obtained fine particles were dispersed in hexane and collected, and acetone and ethanol were sequentially added and washed, and then collected by centrifugation (3000 rpm, 20 min), followed by vacuum drying (35 ° C., 30 min).

  About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Cu was the main component.

  In addition, the obtained Cu fine particles are dispersed in toluene, and this dispersion is dispersed in a Cu microgrid (Aken Shoji Co., Ltd.) with an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)). The sample for observation was produced by dripping on the product) and air-drying. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 Cu fine particles were randomly extracted and the diameter thereof was measured. As a result, the Cu nanoparticles having a diameter in the range of 1 to 1000 nm were 100% (number basis) of the total Cu fine particles. Moreover, these average particle diameters were 200 nm.

(Preparation Example 2)
<Preparation of Sn nanoparticles>
After adding 10 ml of tetrahydrofuran (THF) to the flask, 1.7 mmol of tin chloride (SnCl ₂ ), 32 mmol of oleylamine (C ₁₈ H ₃₅ NH ₂ ) and 3.6 mmol of tetrabutylammonium borohydride (TBABH) were added, and then nitrogen was added. While flowing gas at 0.1 L / min, the mixture was stirred at 60 ° C. for 1 hour to carry out a synthesis reaction to obtain a THF dispersion containing fine particles.

  The THF dispersion is subjected to centrifugation (3000 rpm, 10 min), and the resulting precipitate is dispersed in ethanol, and then centrifuged again (3000 rpm, 20 min) to collect fine particles, followed by vacuum drying (35 ° C. , 30 min) to obtain Sn fine particles.

  About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Sn was the main component.

  In addition, the obtained Sn fine particles were dispersed in toluene, and this dispersion was dispersed into a Cu microgrid (Aken Shoji Co., Ltd.) with an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)). The sample for observation was produced by dripping on the product) and air-drying. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 Sn fine particles were randomly extracted and the diameter thereof was measured. As a result, the Sn nanoparticles having a diameter in the range of 1 to 1000 nm accounted for 100% of all Sn fine particles (number basis). Moreover, these average particle diameters were 25 nm.

(Preparation Example 3)
<Preparation of Sn-transition intermetallic compound nanoparticles (Pt ₃ Sn nanoparticles)>
12.6 mL of ethanol was put in a flask, and Sn particles (“Suzu, powder” manufactured by Wako Pure Chemical Industries, Ltd., particle size 10 to 50 μm) 0.10 g (0.86 mmol), H ₂ PtCl ₆ 0.44 g (0. 86 mmol) was added, and a synthesis reaction was performed by stirring at 70 ° C. for 5 hours while flowing nitrogen gas at 0.1 L / min to obtain an ethanol dispersion containing fine particles. In addition, the scanning electron microscope (SEM) photograph of Sn particle | grains used above is shown in FIG.

  The ethanol dispersion is subjected to centrifugation (3000 rpm, 10 min) and washed. The resulting precipitate is dispersed in ethanol, and then centrifuged (3000 rpm, 20 min) again to collect fine particles and vacuum dried. (35 ° C., 30 min).

About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. A metal component was identified from the obtained XRD spectrum, and it was confirmed that Pt ₃ Sn was a main component. The obtained XRD spectrum is shown in FIG. 6A.

Further, the obtained Pt ₃ Sn fine particles were dispersed in toluene, and this dispersion was dispersed into a Cu microgrid with an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)) (Oken). After being dropped on a trading company), it was naturally dried to prepare an observation sample. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, where randomly extracting 200 _Pt 3 Sn particles, to measure the diameter, the _Pt 3 Sn nanoparticles ranging in diameter 1 to 1,000 nm 100% of the total _Pt 3 Sn particles (number Standard). Moreover, these average particle diameters were 2.6 nm and were spherical particles. In addition, the obtained transmission electron microscope (TEM) photograph is shown in FIG. 6B.

(Preparation Example 4)
<Preparation of Sn-transition intermetallic compound nanoparticles (Ag ₃ Sn nanoparticles)>
25 mL of ethanol was put into a flask, 0.17 g (1.4 mmol) of Sn nanoparticles prepared in Preparation Example 2 was added thereto, 0.58 g (3.4 mmol) of AgNO ₃ was added, and then sonication (output) : 100W) to disperse Sn nanoparticles. Next, a synthesis reaction was performed by stirring at 70 ° C. for 3 hours while flowing nitrogen gas at 0.1 L / min to obtain an ethanol dispersion liquid containing fine particles.

  The ethanol dispersion is subjected to centrifugation (3000 rpm, 10 min) and washed. The resulting precipitate is dispersed in ethanol, and then centrifuged (3000 rpm, 20 min) again to collect fine particles and vacuum dried. (35 ° C., 30 min).

About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Ag ₃ Sn was the main component. The obtained XRD spectrum is shown in FIG. 7A.

In addition, the obtained Ag ₃ Sn fine particles are dispersed in toluene, and this dispersion is dispersed into an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)) Cu microgrid (Oken). After being dropped on a trading company), it was naturally dried to prepare an observation sample. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, where randomly extracting 200 _Ag 3 Sn particles, to measure the diameter, the _Ag 3 Sn nanoparticles ranging in diameter 1 to 1,000 nm 100% of the total _Ag 3 Sn particles (number Standard). Moreover, these average particle diameters were 8 nm and were spherical particles. In addition, the obtained transmission electron microscope (TEM) photograph is shown in FIG. 7B.

(Preparation Example 5)
<Preparation of Sn-transition intermetallic compound nanoparticles (Cu ₆ Sn ₅ nanoparticles)>
18 mL of ethylene glycol was added to the flask, and 0.17 g (1.4 mmol) of Sn nanoparticles prepared in Preparation Example 2 was added thereto, and 2 (acetylacetone) · copper (II) (Cu (C ₅ H ₈ O ₂ ) was added. ₂ ) 0.32 g (1.2 mmol) was added, followed by sonication (output: 100 W) to disperse Sn nanoparticles. Next, a synthesis reaction was carried out by stirring at 100 ° C. for 1 hour while flowing nitrogen gas at 0.1 L / min to obtain an ethylene glycol dispersion containing fine particles.

  This ethylene glycol dispersion is subjected to centrifugation (3000 rpm, 10 min) and washed, and the resulting precipitate is dispersed in ethanol, and then centrifuged again (3000 rpm, 20 min) to collect fine particles, and vacuum Drying (35 ° C., 30 min) was performed.

About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Cu ₆ Sn ₅ was the main component. The obtained XRD spectrum is shown in FIG. 8A.

Further, the obtained Cu ₆ Sn ₅ fine particles were dispersed in toluene, and this dispersion was used as a Cu microgrid with an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)). After being dropped onto Oken Shoji Co., Ltd.), it was naturally dried to prepare an observation sample. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 Cu ₆ Sn ₅ fine particles were randomly extracted and the diameter thereof was measured. As a result, the Cu ₆ Sn ₅ nanoparticles in the range of 1 to 1000 nm in diameter were 100 of all the Cu ₆ Sn ₅ fine particles. % (Number basis). Moreover, these average particle diameters were 8 nm and were spherical particles. In addition, the obtained transmission electron microscope (TEM) photograph is shown in FIG. 8B.

(Preparation Example 6)
<Preparation of Sn-transition intermetallic compound nanoparticles (Ni ₃ Sn ₂ nanoparticles 1)>
After adding 8.03 g (30 mmol) of oleylamine to the flask, 0.17 g (1.4 mmol) of Sn nanoparticles prepared in Preparation Example 2 was added, and 0.156 g (1.2 mmol) of NiCl ₂ was added. Ultrasonic treatment (output: 100 W) was applied to disperse Sn nanoparticles. Next, a synthesis reaction was carried out by stirring at 200 ° C. for 1 hour while flowing nitrogen gas at 0.1 L / min to obtain an oleylamine dispersion containing fine particles.

  This oleylamine dispersion is subjected to centrifugation (3000 rpm, 10 min) and washed, and the resulting precipitate is dispersed in hexane, and then centrifuged (3000 rpm, 20 min) again to collect fine particles and vacuum dried. (35 ° C., 30 min).

About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Ni ₃ Sn ₂ was the main component. The obtained XRD spectrum is shown in FIG. 9A.

Further, the obtained Ni ₃ Sn ₂ fine particles were dispersed in toluene, and this dispersion was dispersed into an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)) Cu microgrid ( After being dropped onto Oken Shoji Co., Ltd.), it was naturally dried to prepare an observation sample. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 Ni ₃ Sn ₂ fine particles were randomly extracted and the diameter thereof was measured. As a result, Ni ₃ Sn ₂ nanoparticles having a diameter in the range of 1 to 1000 nm were 100% of all Ni ₃ Sn ₂ fine particles. % (Number basis). Moreover, these average particle diameters were 18 nm and were polyhedral shape particle | grains. In addition, the obtained transmission electron microscope (TEM) photograph is shown in FIG. 9B.

(Preparation Example 7)
<Preparation of Sn-transition intermetallic compound nanoparticles (Ni ₃ Sn ₂ nanoparticles 2)>
The flask was charged with 8.03 g (30 mmol) of oleylamine and 0.89 g (2.4 mmol) of trioctylphosphine, to which 0.17 g (1.4 mmol) of Sn nanoparticles prepared in Preparation Example 2 was added, and NiCl ₂ was added. After adding 0.156 g (1.2 mmol), ultrasonic treatment (output: 100 W) was applied to disperse Sn nanoparticles. Next, a synthesis reaction was carried out by stirring at 200 ° C. for 1 hour while flowing nitrogen gas at 0.1 L / min to obtain an oleylamine dispersion containing fine particles.

  This oleylamine dispersion is subjected to centrifugation (3000 rpm, 10 min) and washed, and the resulting precipitate is dispersed in hexane, and then centrifuged (3000 rpm, 20 min) again to collect fine particles and vacuum dried. (35 ° C., 30 min).

About the obtained fine particles, an X-ray diffractometer (“Rigaku Co., Ltd.“ sample horizontal strong X-ray diffractometer RINT-TTR ”) was used, X-ray source: CuKα ray (λ = 0.15418 nm), tube voltage: Powder X-ray diffraction (XRD) measurement was performed under the conditions of 50 kV and tube current: 300 mA. The metal component was identified from the obtained XRD spectrum, and it was confirmed that Ni ₃ Sn ₂ was the main component. The obtained XRD spectrum is shown in FIG. 10A.

Further, the obtained Ni ₃ Sn ₂ fine particles were dispersed in toluene, and this dispersion was dispersed into an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)) Cu microgrid ( After being dropped onto Oken Shoji Co., Ltd.), it was naturally dried to prepare an observation sample. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 Ni ₃ Sn ₂ fine particles were randomly extracted and the diameter thereof was measured. As a result, Ni ₃ Sn ₂ nanoparticles having a diameter in the range of 1 to 1000 nm were 100% of all Ni ₃ Sn ₂ fine particles. % (Number basis). Moreover, these average particle diameters were 15 nm and were rectangular parallelepiped shaped particles. In addition, the obtained transmission electron microscope (TEM) photograph is shown to FIG. 10B.

(Preparation Example 8)
<Preparation of Sn-transition intermetallic compound nanoparticles (NiSnCu nanoparticles)>
The flask was charged with 8.03 g (30 mmol) of oleylamine and 0.89 g (2.4 mmol) of trioctylphosphine, to which 0.17 g (1.4 mmol) of Sn nanoparticles prepared in Preparation Example 2 was added, and NiCl ₂ was added. After adding 0.156 g (1.2 mmol), ultrasonic treatment (output: 100 W) was applied to disperse Sn nanoparticles. Next, a synthesis reaction was carried out by stirring at 200 ° C. for 1 hour while flowing nitrogen gas at 0.1 L / min to obtain an oleylamine dispersion containing fine particles.

The obtained oleylamine dispersion was cooled with water, 0.272 g (1.5 mmol) of copper acetate (Cu (OAc) ₂ ) was added, and the mixture was stirred at 200 ° C. for 1 hour to carry out a synthesis reaction to obtain a product. . The obtained product was washed with hexane, and then centrifuged (3000 rpm, 20 min) to collect fine particles, followed by vacuum drying (35 ° C., 30 min).

  The micron-sized aggregates of the obtained fine particles were subjected to SEM-EDS analysis using a scanning electron microscope SEM-EDS (“S-3600N” manufactured by Hitachi, Ltd.) under the conditions of an acceleration voltage of 15 kV and a working distance of 15 mm. As a result, it was confirmed that the particles contained Ni, Sn, and Cu, and NiSnCu was confirmed to be the main component. In addition, the obtained scanning electron microscope (SEM) photograph is shown to FIG. 19A. Further, FIG. 19B shows a graph of an EDS spectrum obtained by EDS analysis of the SEM image of the fine particle aggregate.

  Further, the obtained NiSnCu fine particles are dispersed in toluene, and this dispersion is dispersed into an elastic carbon support film (polymer material film (15 to 20 nm thickness) + carbon film (20 to 25 nm thickness)) Cu microgrid (Oken Corporation ( The sample for observation was produced by dripping on the product) and air-drying. This observation sample was observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 NiSnCu fine particles were randomly extracted and the diameter thereof was measured. As a result, the NiSnCu nanoparticles in the range of 1 to 1000 nm in diameter were 100% (based on the number) of all NiSnCu fine particles. Moreover, these average particle diameters were 16 nm and were polyhedral shape particle | grains. In addition, the obtained transmission electron microscope (TEM) photograph is shown in FIG. 19C.

(Preparation Example 9)
<Preparation of Cu nanoparticles>
30 mmol of copper carbonate (CuCO ₃ · Cu (OH) ₂ · H ₂ O), 30 mmol of dodecanoic acid (C ₁₁ H ₂₃ COOH) and 30 mmol of dodecylamine (C ₁₂ H ₂₅ NH ₂ ) instead of decanoic acid and decylamine Cu fine particles were prepared in the same manner as in Preparation Example 1 except for the above. The obtained Cu fine particles were observed in the same manner as in Preparation Example 1. In TEM observation, 200 Cu fine particles were randomly extracted and the diameters thereof were measured. As a result, Cu nanoparticles in the range of 1 to 1000 nm in diameter were 100% of all Cu fine particles (number basis). Moreover, these average particle diameters were 60 nm.

(Preparation Example 10)
<Preparation of Cu nanoparticles>
30 mmol of copper carbonate (CuCO ₃ · Cu (OH) ₂ · H ₂ O), 30 mmol of octanoic acid (C ₇ H ₁₅ COOH) and 30 mmol of octylamine (C ₈ H ₁₇ NH ₂ ) instead of decanoic acid and decylamine Cu fine particles were prepared in the same manner as in Preparation Example 1 except for the above. The obtained Cu fine particles were observed in the same manner as in Preparation Example 1. In TEM observation, 200 Cu fine particles were randomly extracted and the diameters thereof were measured. As a result, Cu nanoparticles in the range of 1 to 1000 nm in diameter were 100% of all Cu fine particles (number basis). Moreover, these average particle diameters were 300 nm.

(Example 1-1)
The Cu nanoparticles prepared in Preparation Example 1 and the Pt ₃ Sn nanoparticles prepared in Preparation Example 3 were ground and mixed in a mortar, and 95% by mass of Cu nanoparticles and 5% by mass of Pt with respect to all metal nanoparticles. A mixed powder containing ₃ Sn nanoparticles was prepared. To 1 g of this mixed powder, 50 μl of decanol and 50 μl of α-terpineol were added and stirred by a rotating / revolving mixer to prepare a bonding material paste.

<Bonding strength measurement>
In a semiconductor device composed of a lead frame, a semiconductor element, etc., it is difficult to directly measure the bonding strength of the bonding layer. Therefore, the bonding strength of the bonding layer formed from the obtained bonding material was measured by the following method using the bonded body for shear strength measurement shown in FIG.

  First, on one surface of a test piece 8a (diameter 5 mmφ × height 2 mm) made of oxygen-free copper (C1020) and on one surface of a test piece 8b (10 mm × 22 mm × 3 mm) made of oxygen-free copper (C1020), respectively. Ni adhesion layers 10a and 10b having a thickness of 40 nm were formed by RF sputtering.

  Next, a bonding material paste is applied to the surface of the Ni adhesion layer 10b on the test piece 8b by a screen printing method using a metal mask (diameter 5 mmφ × thickness 0.15 mm), and the bonding material layer (diameter 5 mmφ × thickness). 150 μm) was formed. The test piece 8a and the test piece 8b were bonded so that the bonding material layer and the Ni adhesion layer 10a on the test piece 8a were in contact with each other, and preheated at 200 ° C. for 10 minutes in a hydrogen atmosphere under no pressure. Then, the heat processing for 5 minutes were performed at the joining temperature of 400 degreeC, and the joined body for shear strength measurement (FIG. 11) with which the test piece 8a and the test piece 8b were joined by the joining layer 9 was produced.

  In this way, three joined bodies for measuring shear strength were prepared, and these shear strengths were measured at room temperature (20 ° C.) and shear rate of 1 mm / min using an Instron universal testing machine (Instron). The average value of these values was taken as the bonding strength of the bonding layer formed of the bonding material. The results are shown in Table 1.

(Examples 1-2 to 1-11)
As Sn-transition intermetallic compound nanoparticles, Pt ₃ Sn nanoparticles prepared in Preparation Example 3 (Example 1-2), Ag ₃ Sn nanoparticles prepared in Preparation Example 4 (Examples 1-3 and 1-4) ), Cu ₆ Sn ₅ nanoparticles prepared in Preparation Example 5 (Examples 1-5 and 1-6), Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 6 (Examples 1-7 and 1-8), Using the Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 7 (Examples 1-9 and 1-10) and the NiSnCu nanoparticles prepared in Preparation Example 8 (Example 1-11), Cu nanoparticles and Sn-transitions A bonding material paste was prepared in the same manner as in Example 1-1 except that the content of the intermetallic compound nanoparticles was changed to Table 1. Further, a bonded body for measuring shear strength was prepared to increase the bonding strength of the bonding layer. Asked. The results are shown in Table 1.

In addition, the bonding layer formed in Example 1-2 (Pt ₃ Sn: 10% by mass), the bonding layer formed in Example 1-4 (Ag ₃ Sn: 10% by mass), and formed in Example 1-6. Bonding layer (Cu ₆ Sn ₅ : 10% by mass), bonding layer formed in Example 1-8 (Ni ₃ Sn ₂ : 10% by mass), and bonding layer formed in Example 1-10 (Ni ₃ Sn ₂₎ : 10 mass%) when the XRD spectrum in the vicinity of the upper adhesive layer 10a was measured, as shown in FIGS. 12 to 15, in addition to the diffraction peak derived from Cu, the diffraction peak derived from Cu ₃ Sn was observed. It was observed and it was confirmed that a CuSn intermetallic compound (Cu ₃ Sn) was generated.

Furthermore, the cross section near the upper adhesion layer 10a and the lower adhesion layer 10b of the bonding layer (Ni ₃ Sn ₂ : 5% by mass) formed in Example 1-9 was observed with a scanning electron microscope (SEM). However, as shown in FIG. 16A and FIG. 16B, it was confirmed that the average particle diameter was 1000 nm or less in any part. In addition, the cross section of the bonding layer (Ni ₃ Sn ₂ : 10% by mass) formed in Example 1-10 near the upper adhesion layer 10a and the lower adhesion layer 10b was observed with a scanning electron microscope (SEM). However, as shown in FIGS. 17A and 17B, it was confirmed that the average particle diameter was 1000 nm or less in any part. In the bonding layer formed using the bonding material paste, the Cu nanoparticles are not completely sintered (sintering is suppressed) due to the formation of the CuSn intermetallic compound (Cu ₃ Sn), This is probably because the Cu nanoparticles were sintered while maintaining the particle diameter in the bonding material paste.

(Comparative Example 1-1)
A bonding material paste was prepared in the same manner as in Example 1-1 except that Pt ₃ Sn nanoparticles were not mixed, and a bonded body for measuring shear strength was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 1.

(Comparative Examples 1-2 to 1-4)
Example except that Sn nanoparticles (Comparative Examples 1-2 to 1-3) or Ni ₃ Sn ₂ nanoparticles (Comparative Example 1-4) were used instead of Pt ₃ Sn nanoparticles and the ratios shown in Table 1 were used. A bonding material paste was prepared in the same manner as in 1-1, and a bonded body for measuring shear strength was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 1.

As is apparent from the results shown in Table 1, formed by a bonding material containing 95 or 90% by mass of Cu nanoparticles and 5 or 10% by mass of Sn-transition intermetallic compound nanoparticles with respect to the total metal nanoparticles. The bonding strength of the formed bonding layers (Examples 1-1 to 1-11) includes a bonding layer (Comparative Example 1-1) formed of a bonding material only of Cu nanoparticles, Cu nanoparticles, and Sn nanoparticles. Bonding layer formed by bonding material (Comparative Examples 1-2 to 1-3), and bonding layer formed by bonding material including Cu nanoparticles and 50 mass% Sn-transition intermetallic compound nanoparticles (Comparative example) It was confirmed that it was higher than the bonding strength of 1-4). In _Ni 3 Sn ₂ polyhedral nanoparticles 50% by mass added was mixed paste (Comparative Example 1-4) with respect to Cu nanoparticles, can not be joined, strength did not appear at all.

(Examples 2-1 to 2-11)
As Sn-transition intermetallic compound nanoparticles, Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 7 (Examples 2-1 to 2-10), NiSnCu nanoparticles prepared in Preparation Example 8 (Example 2-11) And a bonding material paste was prepared in the same manner as in Example 1-1 except that the content of Sn-transition intermetallic compound nanoparticles was changed to Table 2 (Examples 2-1 to 2-11). A bonded body for shear strength measurement was prepared in the same manner as in Example 1-1 except that the bonding temperature was changed to 350 ° C., and the bonding strength of the bonding layer was determined. The results are shown in Table 2.

(Comparative Examples 2-1 to 2-2)
A bonding material paste was prepared in the same manner as in Comparative Examples 1-1 and 1-3 (Comparative Examples 2-1 and 2-2), and Comparative Examples 1-1 and 1 except that the bonding temperature was changed to 350 ° C. The joint for shear strength measurement was produced in the same manner as in -3 to determine the joint strength of the joint layer. The results are shown in Table 2.

(Comparative Example 2-3)
A joining material paste was prepared in the same manner as in Example 1-1 except that Ni ₃ Sn ₂ nanoparticles (Comparative Example 2-3) were used instead of Pt ₃ Sn nanoparticles, and the ratios shown in Table 2 were used. A bonded body for shear strength measurement was prepared in the same manner as in Example 1-1 except that the bonding temperature was changed to 350 ° C., and the bonding strength of the bonding layer was determined. The results are shown in Table 2.

As is apparent from the results shown in Table 2, a bonding material containing 70 to 99.5% by mass of Cu nanoparticles and 30 to 0.5% by mass of Ni ₃ Sn ₂ nanoparticles with respect to all metal nanoparticles. The bonding strength of the bonding layers (Examples 2-1 to 2-10) formed by the bonding layers was a bonding layer (Comparative Example 2-1) formed of a bonding material composed only of Cu nanoparticles, Cu nanoparticles, and Sn nanoparticles. Of a bonding layer (Comparative Example 2-2) formed of a bonding material containing Ni, and a bonding layer (Comparative Example 2-3) formed of a bonding material in which the content of Ni ₃ Sn ₂ nanoparticles exceeds 30% by mass It was confirmed that it was higher than the bonding strength. Even when the bonding temperature is changed to 350 ° C., the bonding layers (Examples 2-1 to 2-10) formed of the bonding material of the present example are formed of the bonding material of the comparative example. It was confirmed that it was higher than the bonding strength of the bonding layers (Comparative Examples 2-1 to 2-3). Further, a bonding layer formed of a bonding material containing 95 mass% Cu nanoparticles and 5 mass% ternary Sn-transition intermetallic compound nanoparticles (NiSnCu nanoparticles) with respect to all metal nanoparticles ( It was confirmed that the bonding strength of Example 2-11) was higher than the bonding strength of the bonding layers (Comparative Examples 2-1 to 2-3) formed of the bonding material of the comparative example.

(Example 3-1)
5 mass% of Pt ₃ Sn nanoparticles prepared in Preparation Example 3 are added to the Cu nanoparticles prepared in Preparation Example 1 (mixed nanoparticles), and Cu micron particles having an average particle diameter of 1.2 μm (total Cu The ratio of Cu nanoparticles in the range of 1 to 1000 nm in diameter (number basis): 20%) is mixed, and a composite material containing 99% of mixed nanoparticles and 1% of Cu micron particles on the basis of number A powder was prepared. A bonding material paste was prepared in the same manner as in Example 1-1 except that 1 g of this mixed powder was used. Further, a bonded body for measuring shear strength was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 3.

(Example 3-2)
A bonding material paste was prepared in the same manner as in Example 3-1, except that the Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 7 were used as Sn-transition intermetallic compound nanoparticles. The body was prepared and the bonding strength of the bonding layer was determined. The results are shown in Table 3.

  As is apparent from the results shown in Table 3, bonding layers formed of a bonding material containing composite powder containing 1% of Cu micron particles on the basis of the number of mixed nanoparticles (Examples 3-1 to 3- It was confirmed that the bonding strength of 2) was higher than the bonding strengths of Comparative Examples 2-1 to 2-3.

(Comparative Example 3-1)
A bonding material paste was prepared in the same manner as in Example 1-9 except that Cu micron particles (average particle size 24 μm) manufactured by Fukuda Metal Foil Powder Co., Ltd. were used instead of Cu nanoparticles (Comparative Example 3- 1) A bonded body for measuring shear strength was prepared in the same manner as in Example 1-9, and the bonding strength of the bonding layer was determined. The results are shown in Table 4.

(Comparative Example 3-2)
A bonding material paste was prepared in the same manner as in Example 1-10 except that NiSn micron particles (average particle diameter of 5 μm) were used instead of Ni ₃ Sn ₂ nanoparticles (Comparative Example 3-2). In the same manner as in Example 10, a bonded body for measuring shear strength was prepared, and the bonding strength of the bonding layer was determined. The results are shown in Table 4.

(Comparative Example 3-3)
A bonding material paste was prepared in the same manner as in Example 2-7 except that NiSn micron particles (average particle size of 5 μm) were used instead of Ni ₃ Sn ₂ nanoparticles (Comparative Example 3-3). In the same manner as in Example 7, a bonded body for measuring shear strength was prepared, and the bonding strength of the bonding layer was determined. The results are shown in Table 4.

In addition, the XRD spectrum figure of the NiSn micron particle used in Comparative Examples 3-1 to 3-2 is shown in FIG. From FIG. 18, Ni ₃ Sn ₂ and Ni ₃ Sn ₄ were confirmed as components.

As is clear from the results shown in Table 4, the bonding layer (Comparative Example 3-1) formed of a bonding material using Cu micron particles instead of Cu nanoparticles has an extremely low bonding strength of 0.1 MPa. It was confirmed that In addition, the bonding layer (Comparative Examples 3-2 to 3-3) formed of a bonding material using NiSn micron particles instead of Ni ₃ Sn ₂ nanoparticles is lower than those in Examples 1 and 2 above. It was confirmed that

(Example 4-1)
Except that the Cu nanoparticles were changed to the Cu nanoparticles prepared in Preparation Example 9 and the Sn-transition intermetallic compound nanoparticles were changed to the Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 6, the same as in Example 1-1. A bonding material paste was prepared, and a bonded body for shear strength measurement was prepared in the same manner as in Example 1-1 to determine the bonding strength of the bonding layer. The results are shown in Table 5.

(Comparative Example 4-1)
A bonding material paste was prepared in the same manner as in Example 4-1, except that the Sn-transition intermetallic compound nanoparticles were not mixed, and a bonded body for shear strength measurement was prepared to determine the bonding strength of the bonding layer. It was. The results are shown in Table 5.

  As is clear from the results shown in Table 5, the bonding layer formed of the bonding material of Example 4-1 (Example 4-1) even when the Cu nanoparticles were changed to an average particle diameter of 60 nm. Is higher than the bonding strength of the bonding layer (Comparative Example 4-1) formed of the bonding material of the bonding layer (Comparative Example 4-1) formed of the bonding material not containing Sn nanoparticles. confirmed.

(Example 5-1)
Except that the Cu nanoparticles were changed to the Cu nanoparticles prepared in Preparation Example 10 and the Sn-transition intermetallic compound nanoparticles were changed to the Ni ₃ Sn ₂ nanoparticles prepared in Preparation Example 6, the same as in Example 1-1. A bonding material paste was prepared, and a bonded body for shear strength measurement was prepared in the same manner as in Example 1-1 to determine the bonding strength of the bonding layer. The results are shown in Table 6.

(Comparative Example 5-1)
A bonding material paste was prepared in the same manner as in Example 5-1, except that the Sn-transition intermetallic compound nanoparticles were not mixed, and a bonded body for measuring shear strength was prepared to determine the bonding strength of the bonding layer. It was. The results are shown in Table 6.

  As is clear from the results shown in Table 6, the bonding layer formed of the bonding material of Example 5-1 (Example 5-1) even when the Cu nanoparticles were changed to an average particle diameter of 300 nm. Is higher than the bonding strength of the bonding layer (Comparative Example 5-1) formed of the bonding material of the bonding layer (Comparative Example 5-1) formed of the bonding material not containing Sn nanoparticles. confirmed.

  As described above, according to the present invention, a bonding material capable of forming a bonding layer having a sufficiently high bonding strength at no pressure and at a low temperature (specifically, 400 ° C. or less) can be obtained. Therefore, the metal nanoparticle paste of the present invention is useful as a bonding material in a bonding technique for semiconductor elements at a low temperature or no pressure.

  1: semiconductor element, 2: substrate, 2a: upper substrate, 2b: lower substrate, 2c, 2d: protruding portion of each substrate, 3, 3a, 3b: bonding layer, 4a, 4b: adhesion layer, 5: signal terminal, 6: bonding wire, 7: mold resin, 8a, 8b: test piece, 9: bonding layer, 10a, 10b: adhesion layer.

Claims (10)

A metal nanoparticle paste comprising 99.9 to 70% by mass of Cu nanoparticles and 0.1 to 30% by mass of intermetallic compound nanoparticles of Sn and a transition metal with respect to all metal nanoparticles .   2. The metal nanoparticle paste according to claim 1, wherein the metal nanoparticles having a diameter in the range of 1 to 1000 nm are 99% or more of the total metal particles based on the number. The transition metal of the intermetallic compound nanoparticles of Sn and transition metal is a metal having a melting point of 960 ° C or higher and an ion standard electrode potential of -0.45V or higher. Or the metal nanoparticle paste of 2. The transition metal of the intermetallic compound nanoparticles of Sn and transition metal is at least one metal selected from the group consisting of Au, Pt, Pd, Ag, Cu, Ni, Co and Fe, The metal nanoparticle paste according to any one of claims 1 to 3.   A bonding material comprising the metal nanoparticle paste according to any one of claims 1 to 4. Comprising a semiconductor element, a substrate, and a bonding layer disposed between the semiconductor element and the substrate;
A semiconductor device, wherein the bonding layer is a mixture layer of Cu, Sn, and a transition metal formed of the bonding material according to claim 5 .   The semiconductor device according to claim 6, wherein the mixture layer is formed of metal nanoparticles having an average particle diameter of 1 to 1000 nm. The semiconductor device according to claim 6, wherein the mixture layer contains an intermetallic compound of Cu and CuSn and an intermetallic compound of Sn and a transition metal . The semiconductor device according to claim 8, wherein the CuSn intermetallic compound is Cu ₃ Sn. The adhesive layer further includes an adhesion layer made of at least one metal selected from the group consisting of Ni, Co, and Ag on both surfaces of the bonding layer,
Is one of the adhesion layer is disposed in contact with the junction of the semiconductor device, any other adhesion layer of the claims 6-9, characterized in that it is arranged in contact with the joint portion of the substrate The semiconductor device according to claim 1.