JP6270241B2 - Bonding material and semiconductor device using the same - Google Patents

Description

  The present invention relates to a bonding material 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. Furthermore, in semiconductor element bonding technology and fine wiring formation technology, materials that can be bonded at low temperatures or non-pressure bonding and wiring formation at low temperatures are possible to reduce the load on the semiconductor elements. There is a need for materials.

  Metal nanoparticles such as Ag, Cu, Ni, etc. should 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, for example 50 nm or less. Therefore, it is expected to be applied to low-temperature bonding of semiconductor elements and low-temperature formation of fine wiring using ink jet or screen printing.

  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 or forming fine wiring using such metal nanoparticles, the metal nanoparticles are sintered and the coating of surfactant, polymer, etc. is decomposed, Gas is generated and voids are formed 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 and a sufficiently low resistivity could not be obtained.

  In addition, Cu nanoparticles are metal nanoparticles that are low in cost, excellent in heat resistance and anti-mication properties, and low in resistivity. In general, however, the problem is that oxidation is easy and sintering is hindered by the oxide film on the surface. was there.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2008-24969 (Patent Document 1) discloses monodispersed copper fine particles coated with a nickel coating that adsorbs an organic compound component on the surface. The coating amount of nickel is Ni: Cu = 1: 100 to 50: 100 in terms of mass ratio, the average particle size of the copper fine particles is 10 to 100 nm, and the standard deviation in the particle size of the copper fine particles Nickel-coated copper fine particles in which (σ / d) × 100 representing the ratio of (σ) to the average particle diameter (d) is 10 to 30% are disclosed. However, in the nickel-coated copper fine particles disclosed in Patent Document 1, the coating layer of the nanoparticle having a coating structure itself becomes a sintering inhibiting factor, so that high bonding strength cannot be obtained at low temperature and no pressure. Therefore, the strength is not sufficient even when bonding is performed under no pressure at a low temperature (for example, 300 ° C. or less).

JP-A-2011-63828 (Patent Document 2) discloses a reaction solvent in which one or more linear alcohols having 6 to 10 carbon atoms and one or more organic compounds having 200 to 400 molecules are dissolved. After the copper and nickel compounds are dissolved, the copper-nickel nanostructures in which the composition ratio of copper in the central portion is high and the surroundings are formed of a nickel-copper alloy by a manufacturing method in which an organic-ammonium hydroxide salt solution is added in particles coated with an organic compound having a molecular number 200 to 400, transmission electron a mean particle diameter D _TEM is 1~30nm measured by a microscope, a high surface portion nickel copper composition ratio of the central portion and copper There is disclosed a nickel-copper alloy which is made of a copper-nickel nanoparticle formed of the above alloy and which is fine and has a nickel-rich surface layer. However, even in the nickel-copper alloy disclosed in Patent Document 2, since the coating layer of nanoparticles having a coating structure itself becomes a sintering inhibiting factor, high bonding strength can be obtained at low temperature and no pressure. Therefore, the strength is not sufficient even when joining without pressure at a low temperature (for example, 300 ° C. or less).

  Further, JP 2011-175871 A (Patent Document 3) discloses a bonding material containing two or more kinds of silver-based powders having different average particle diameters, and includes an organic component and silver as the first powder. Disclosed is a bonding material including a silver-based powder having a mean particle size of less than 10 nm and a silver-based powder having a mean particle size of 40 nm or more, which is composed of silver-based particles containing silver as the second powder. . However, even the bonding material disclosed in Patent Document 3 does not have sufficient migration resistance, and a high bonding strength cannot be obtained at low temperature and no pressure. Therefore, no application at low temperature (for example, 300 ° C. or lower). Even if it was joined by pressure, the strength was not sufficient.

  In addition, Masayoshi Shimoda et al., “Development of die-bonding technology using high-temperature bonding materials”, MES2013 (23rd Microelectronics Symposium), Japan Institute of Electronics Packaging, September 2013, P147-150 (Non-patent Document 1). Discloses a bonding material using a paste in which three kinds of Cu nanoparticles having different average sizes of 70 nm, 0.8 μm, and 5 μm are mixed. However, even in the Cu nanoparticle mixed paste disclosed in Non-Patent Document 1, it is difficult to lower the sintering temperature because the particles are not sufficiently fine, and when the Cu nanoparticles are further miniaturized, the surface tends to be oxidized. High bonding strength cannot be obtained at low temperature and no pressure, for example, the bonding strength cannot be improved. Therefore, even if bonding is performed at a low temperature (for example, 300 ° C. or less) without pressure, the strength is not always sufficient.

JP 2008-24969 A JP 2011-63828 A JP 2011-175871 A

Masayoshi Shimoda et al., “Development of die-bonding technology using high-temperature-resistant bonding materials”, MES2013 (23rd Microelectronics Symposium), Japan Institute of Electronics Packaging, September 2013, P147-150

  The present invention has been made in view of the above-described problems of the prior art, and a bonding material capable of forming a bonding layer having sufficiently high bonding strength at a low temperature (specifically, 300 ° C. or lower), and the same An object of the present invention is to provide a semiconductor device using this.

  As a result of intensive studies to achieve the above object, the present inventors have identified Cu nanoparticles having a specific range of particle size and average particle size and fine CuNi alloy nanoparticles having a specific range of average particle size. It is possible to form a bonding layer having a sufficiently high bonding strength at a low temperature (specifically, 300 ° C. or lower) by using a bonding material containing a specific proportion of the metal nanoparticle mixture including As a result, the present invention has been completed.

That is, the bonding material of the present invention is composed of Cu nanoparticles having a particle diameter of 1000 nm or less and an average particle diameter of 60 nm to 300 nm, and fine CuNi alloy nanoparticles having an average particle diameter of 1 nm to 50 nm. The metal nanoparticle mixture is contained, the content of the fine CuNi alloy nanoparticles in the metal nanoparticle mixture is 0.1 to 29% by mass, and the content of the metal nanoparticle mixture is 15% by mass. % Or more.

  In the bonding material of the present invention, the ratio of the average particle diameter of the Cu nanoparticles to the average particle diameter of the fine CuNi alloy nanoparticles is preferably 2 to 60.

  In the bonding material of the present invention, the Ni content in the fine CuNi alloy nanoparticles is preferably 2 to 90% by mass.

In addition, other bonding materials of the present invention, a Cu nanoparticle and the average particle size becomes a particle diameter from the Cu particles 1000nm is 50 nm to 1000 nm, the fine CuNi alloy nanoparticles having an average particle diameter of 1nm~50nm A metal nanoparticle mixture comprising particles, and Cu micron particles comprising Cu particles having a particle diameter of more than 1 μm and an average particle diameter of more than 1 μm and not more than 200 μm, and the fine CuNi in the metal nanoparticle mixture The alloy nanoparticle content is 0.1 to 29% by mass, the metal nanoparticle mixture content is 15% by mass or more, and the Cu micron particle content is 85% by mass or less. It is characterized by .

  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 made of Cu and CuNi alloy formed of the bonding material of the present invention. It is a mixture layer.

  In the semiconductor device of the present invention, the Ni content in the mixture layer is preferably 0.0003 to 26.1% by mass.

  The semiconductor device of the present invention 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 mixture layer, and one adhesion layer is the above-mentioned It is preferable that the semiconductor element is disposed so as to be in contact with the joint portion of the semiconductor 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 bonding layer having high bonding strength can be formed at a low temperature by the bonding material of the present invention is not necessarily clear, but the present inventors speculate as follows.

  That is, conventionally, metal nanoparticles are known to sinter at a temperature much lower than the melting point due to the active action of surface atoms. Recently, development of high heat-resistant bonding technology for semiconductor elements has been actively conducted by utilizing such low-temperature sintering of metal nanoparticles. In the prior art, Ag nanoparticles have been used, but recently, development of Cu nanoparticles having lower migration cost and better migration resistance than Ag is strongly expected. Further, when bonding semiconductor elements under pressure, there are problems such as a decrease in yield due to chip destruction and an increase in cost due to the addition of production processes, and therefore bonding without pressure is strongly expected. Furthermore, if bonding can be performed at the same bonding temperature (250 ° C., etc.) as conventional Sn—Cu solder, the thermal load on the element can be reduced and bonding can be performed with existing equipment. Has been. However, in the conventional technique, it is difficult to suppress oxidation when the particle size of the Cu nanoparticles is 50 nm or less, and therefore bonding is performed using Cu nanoparticles of 50 nm or more. This makes it difficult to lower the sintering temperature because of the large particle size, and even if sintering is performed without pressure, many particles remain bonded only at points (linking state), so that sufficient sintering is achieved. There was a problem that the knot strength could not be obtained.

  First, the present inventors achieve a low temperature and high strength by packing fine particles between Cu particles with a particle size of 50 nm or less to Cu nanoparticles with a particle size of 50 nm or more, thereby more densely filling the space between the particles. Although an attempt was made to oxidize fine Cu nanoparticles, the oxide layer hindered sintering and could not be strengthened.

  Therefore, the present inventors paid attention to Ni as an additive component capable of suppressing oxidation of Cu nanoparticles with respect to fine Cu nanoparticles. Then, a metal nanoparticle mixture containing a specific proportion of fine CuNi alloy nanoparticles having a specific particle diameter and a specific range together with Cu nanoparticles having a specific particle size and average particle size is included in a specific ratio. It is possible to suppress the oxidation of Cu nanoparticles due to the presence of Ni contained in the material. When a bonding layer is formed using such a bonding material, the sintering temperature can be sufficiently lowered. It can be realized that it is possible to obtain a high bonding strength even at a temperature at which the bonding temperature is sufficiently low (specifically, 300 ° C. or lower) even without pressure. Furthermore, Ni added as an additive has an effect of improving the bonding property between Cu nanoparticles, for example, high bonding strength even at the same bonding temperature (250 ° C.) as that of Sn—Cu solder or no pressure. It is assumed that it will be possible to obtain.

  According to the present invention, it is possible to provide a bonding material capable of forming a bonding layer having sufficiently high bonding strength at a low temperature (specifically, 300 ° C. or lower), and a semiconductor device using the same. .

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. It is a graph which shows the XRD spectrum of the nanoparticle produced by the preparation examples 2-1 to 2-6. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles produced in Preparation Example 2-1. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles produced in Preparation Example 2-2. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles produced in Preparation Example 2-3. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles produced in Preparation Example 2-4. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles produced in Preparation Example 2-5. It is a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the comparative fine Cu nanoparticles produced in Preparation Example 2-6. It is a schematic diagram which shows the joined body for shear strength measurement produced in the Example.

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

  First, the bonding material of the present invention will be described. The bonding material of the present invention contains a metal nanoparticle mixture including Cu nanoparticles having a predetermined particle diameter and average particle diameter and fine CuNi alloy nanoparticles having a predetermined average particle diameter in a predetermined ratio. To do. The bonding material of the present invention can be sintered by heat treatment at a low temperature (specifically, 300 ° C. or lower) to form a bonding layer having a sufficiently high bonding strength. In addition, when the bonding material of the present invention is used, a bonding layer having a sufficiently high bonding strength can be formed even when no pressure is applied during heat treatment.

(Cu nanoparticles)
The Cu nanoparticles in the metal nanoparticle mixture according to the present invention are required to be composed of Cu particles having a particle size of 1000 nm or less and an average particle size of 50 nm to 1000 nm. The average particle diameter of such Cu nanoparticles, that is, Cu nanoparticles in the bonding material of the present invention is preferably 50 nm to 800 nm, more preferably 60 nm to 500 nm, and particularly preferably 60 nm to 400 nm. When the average particle diameter of the Cu nanoparticles is less than the lower limit, the surface ratio with respect to the bulk increases, so that the surface of the Cu nanoparticles is easily oxidized in the air, and as a result, aggregation of Cu nanoparticles occurs in the bonding material. Occurs or the oxidizing component cannot be removed sufficiently by heat treatment during bonding, and the characteristics of the bonding material such as bonding strength, conductivity, and thermal conductivity tend to be reduced. 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 bonding material 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 nanoparticles 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, 300 ° C. or less). As a result, the bonding strength tends to decrease.

  The diameter of the Cu nanoparticles can be measured by transmission electron microscope (TEM) observation. In the present invention, the diameter of the Cu nanoparticles and the fine CuNi alloy nanoparticles in the metal nanoparticle mixture can be measured. The ratio and content of Cu nanoparticles and the average particle diameter of Cu nanoparticles are values determined by randomly extracting 200 Cu particles and measuring these diameters in the TEM observation.

  In addition, 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, 300 ° 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 presence 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, and 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.

(Fine CuNi alloy nanoparticles)
The fine CuNi alloy nanoparticles in the metal nanoparticle mixture according to the present invention are required to have an average particle diameter of 1 nm to 50 nm. The average particle diameter of such fine CuNi alloy nanoparticles, that is, CuNi alloy particles (including CuNi alloy nanoparticles) in the bonding material of the present invention is preferably 5 nm to 50 nm, more preferably 8 nm to 40 nm, and more preferably 10 nm to 30 nm. Is particularly preferred. When the average particle diameter of the fine CuNi alloy nanoparticles is less than the lower limit, the component ratio of the organic coating in the particles increases, the organic coating component remains and inhibits sintering, and the bonding strength, conductivity, and thermal conductivity. There is a tendency for the properties of the bonding material to deteriorate. On the other hand, if the average particle diameter of the fine CuNi alloy nanoparticles exceeds the above upper limit, the particle size effect is small, so the sintering temperature of the Cu particles becomes high, and the Cu by heating at a low temperature (specifically, 300 ° C. or less). -Bonding between CuNi alloy nanoparticles is difficult to occur, and as a result, the strength is not easily improved by the addition of CuNi alloy nanoparticles, and the bonding strength tends to decrease.

  The diameter of the CuNi alloy nanoparticles can be measured by transmission electron microscope (TEM) observation. In the present invention, the total amount of the Cu nanoparticles and the fine CuNi alloy nanoparticles in the metal nanoparticle mixture. In the TEM observation, the ratio of fine CuNi alloy nanoparticles with respect to the average particle diameter and the average particle diameter of CuNi alloy particles (including CuNi alloy nanoparticles) are extracted by randomly extracting 200 Cu particles and measuring these diameters. The value obtained by.

  In the present invention, the content of Ni contained in such fine CuNi alloy nanoparticles is not particularly limited, but is preferably 2 to 90% by mass, more preferably 10 to 85% by mass. It is especially preferable that it is 20-82 mass%. If the content of Ni contained in the fine CuNi alloy nanoparticles is less than the lower limit, the oxidation of the Cu nanoparticles by the fine CuNi alloy nanoparticles is insufficiently suppressed, adversely affecting the sintering characteristics, and joining of the joining layer formed On the other hand, when the upper limit is exceeded, the melting point of the particles is excessively increased, the sintering temperature is increased, sintering at a low temperature is difficult to occur, and a bonding layer having high bonding strength is formed at a low temperature. It tends to be impossible to form with.

  Moreover, it does not restrict | limit especially as such a fine CuNi alloy nanoparticle, A well-known CuNi alloy nanoparticle can be used suitably. For example, Cu particles or Cu ions and Ni ions are reacted in a solution, and Ni ions are reduced to synthesize CuNi alloy nanoparticles. In order to accelerate the reduction, the reaction is preferably carried out in a reducing solvent.

  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.

  For the synthesis of CuNi alloy nanoparticles, surfactants with different alkyl chain lengths are used instead of modifiers for shape control such as aliphatic amines such as oleylamine and trioctylphosphine, and the addition ratio is changed. By doing so, it is possible to synthesize particles having various particle sizes and organic component contents.

  The shape of the fine CuNi alloy 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.

(Joining material)
The bonding material of the present invention contains a metal nanoparticle mixture containing such Cu nanoparticles and fine CuNi alloy nanoparticles in a predetermined ratio. In the bonding material of the present invention, the content of the fine CuNi alloy nanoparticles in the metal nanoparticle mixture is 0.1 to 29% by mass (that is, the content of Cu nanoparticles is 99.9 to 71% by mass). is there. If the content of the fine CuNi alloy nanoparticles is less than the lower limit (that is, the content of the Cu nanoparticles exceeds the upper limit), the effect of improving the bonding between particles by the fine CuNi alloy nanoparticles is not sufficiently exhibited. , The bonding strength decreases. On the other hand, if the content of fine CuNi alloy nanoparticles exceeds the upper limit (that is, the content of Cu nanoparticles is less than the lower limit), the amount of organic coating becomes too large and sintering is inhibited by the remaining organic coating. In addition, since the CuNi alloy has a higher melting point than Cu, the CuNi component is increased and sintering at low temperature is difficult to occur, and the properties of the bonding material such as bonding strength, conductivity, and thermal conductivity are deteriorated. Moreover, from a viewpoint that joint strength becomes higher, it is preferable that content of a fine CuNi alloy nanoparticle is 1-27 mass%, and it is more preferable that it is 1-20 mass%.

  In such a bonding material of the present invention, the content of the metal nanoparticle mixture in the bonding material is 15% by mass or more. By setting the content of the metal nanoparticle mixture to 15% by mass or more, a bonding material capable of forming a bonding layer having sufficiently high bonding strength at a low temperature (specifically, 300 ° C. or less) can be obtained. It becomes.

  In such a bonding material of the present invention, the ratio of the average particle diameter of the Cu nanoparticles to the average particle diameter of the fine CuNi alloy nanoparticles is preferably 2 to 60, and preferably 3 to 40. Is more preferable. When the ratio of the average particle diameter of the Cu nanoparticles to the average particle diameter of the fine CuNi alloy nanoparticles is less than the lower limit, the difference in the particle diameter between the Cu nanoparticles and the fine CuNi alloy nanoparticles is small. The filling effect between the nanoparticles tends to be small, and the bonding strength of the formed bonding layer tends to be insufficient. On the other hand, when the upper limit is exceeded, a fine CuNi alloy is added between the Cu nanoparticles with a predetermined addition amount. It becomes difficult to fill with nano, and the bonding strength of the formed bonding layer tends to be insufficient.

  In addition, the bonding material of the present invention is a bonding material further comprising Cu micron particles made of Cu particles having a particle diameter of more than 1 μm and having an average particle diameter of more than 1 μm and not more than 200 μm. The content of is more preferably 85% by mass or less. When the content of Cu micron particles exceeds the above upper limit, the proportion of particles having a large particle diameter increases so much that the sintering temperature does not decrease due to the nano-size effect of the bonding material, and the bonding strength of the bonding layer to be formed is reduced. It tends to be insufficient. Moreover, as an average particle diameter of such Cu micron particle, 1.2 micrometers-180 micrometers or less are preferable, and 3 micrometers-150 micrometers are more preferable. When the average particle diameter of Cu micron particles is less than the lower limit, aggregation between particles tends to occur and the bonding strength tends to decrease. On the other hand, when the upper limit is exceeded, the sintering temperature is lowered due to finer particles. Tends to occur and the bonding strength tends to decrease.

  Such a bonding material of the present invention is, for example, mixed so that Cu nanoparticles and fine CuNi alloy nanoparticles are in a predetermined ratio, and the resulting mixed nanoparticles are mixed with a solvent such as an organic solvent. Or by mixing the Cu nanoparticle dispersion and the fine CuNi alloy nanoparticle dispersion so that the Cu nanoparticles and the fine CuNi alloy nanoparticles have a predetermined ratio. Alternatively, Cu nanoparticles, fine CuNi alloy nanoparticles, and Cu micron particles may be dispersed in a solvent such as an organic solvent, and then the dispersion solution may be mixed and concentrated by an evaporator so that a desired amount is obtained. Alternatively, stirring may be performed with a ball mill. Furthermore, when preparing a paste-like or ink-like bonding material, the mixed nanoparticles and the solvent may be mixed so as to become a paste-like or ink-like, or a paste-like or ink-like Cu nano-particle may be mixed. Particles and fine CuNi alloy nanoparticles may be prepared and mixed, or after preparing a dispersion of the mixed nanoparticles, it may be concentrated using an evaporator or the like until a paste or ink is obtained. .

  The Cu nanoparticle dispersion and the fine CuNi alloy nanoparticle dispersion may be prepared by mixing Cu nanoparticles and fine CuNi alloy nanoparticles with a solvent such as an organic solvent, or a commercially available nanoparticle paste or dispersion. A liquid may be used.

  Although there is no restriction | limiting in particular as an organic solvent used for the joining material of this invention, For example, C1-C20 monoalcohols, such as C1-C18 alkanes, such as tetradecane; 1-butanol, decanol, isopropyl alcohol, etc. 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 ether, Examples thereof include ethers such as butyl carbitol; esters such as ethyl acetate and butyl carbitol acetate; 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 joining material paste of this invention as needed.

  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 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. It is a mixture layer. In the semiconductor device of the present invention, the semiconductor device of the present invention 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 mixture layer. Is preferred. 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.

  In such a semiconductor device of the present invention, the Ni content in the mixture layer is preferably 0.0003 to 26.1% by mass, and more preferably 0.003 to 20% by mass. . If the Ni content is less than the lower limit, sintering between particles tends to be insufficient and the bonding strength tends to be insufficient. On the other hand, if the upper limit is exceeded, the amount of Ni is large, resulting in heat and electrical conduction characteristics. It tends to be insufficient.

  The Ni ratio of the joint composed of a mixture layer of Cu and CuNi alloy can be determined from the minimum content ratio of Ni and the maximum content ratio of Ni in the joining material of the present invention forming the joint. .

  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 micrometer-500 micrometers are preferable, 50 micrometers-400 micrometers are more preferable, and 100 micrometers-300 micrometers are 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 and Ni, the bonding strength is excellent. In the bonding layer according to the present invention, a Cu—Ni alloy may be formed as long as the bonding strength does not decrease.

  Although there is no restriction | limiting in particular as temperature of heat processing, 150-450 degreeC is preferable and 200-400 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 resistance temperature of the semiconductor element, the thermal stress increases, and warping or peeling tends to occur.

  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.

  When the adhesion layer is formed by a coating method, first, an inkjet method, a spin coating method, a dip method, a screen printing method, or the like is applied to an object to be coated such as a semiconductor element or a substrate in the air or in an inert gas atmosphere. The paste or ink containing the material (for example, Ni, Co, or Ag) of the adhesion layer to be formed is applied by the above 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 speculate 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. In addition, the joining material used by the Example and the comparative example was prepared with the following method.

(Preparation Example 1-1)
<Preparation of Cu nanoparticles 1-1>
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 placed in a flask and 30 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 30 mmol of octanoic acid (C ₇ H ₁₅ COOH) and 30 mmol of octylamine (C ₈ H ₁₇ 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. As a result, fine particles were formed. 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.

  Further, the obtained Cu fine particles are dispersed in hexane, 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 Cu fine particles were randomly extracted and the diameter thereof was measured. As a result, the average particle diameter was 300 nm. The obtained results are shown in Table 1. In addition, all the particle diameters of Cu fine particles were 1000 nm or less.

(Preparation Examples 1-2 to 1-4)
<Preparation of Cu nanoparticles 1-2 to 1-4>
Cu fine particles were prepared in the same manner as in Preparation Example 1-1 except that the fatty acids shown in Table 1 were used instead of octanoic acid, the aliphatic amines shown in Table 1 were used instead of octylamine, and the ratios shown in Table 1 were used. . About the obtained microparticles | fine-particles, the powder X-ray-diffraction (XRD) measurement was performed like preparation example 1-1, and all confirmed that Cu was a main component. Next, using the obtained Cu fine particles, an observation sample was prepared in the same manner as in Preparation Example 1-1, and TEM observation was performed in the same manner as in Preparation Example 1-1 to obtain an average particle size. The obtained results are shown in Table 1. In addition, all the particle diameters of Cu fine particles were 1000 nm or less in any of Preparation Examples 1-2 to 1-4.

(Preparation Examples 2-1 to 2-5)
<Preparation of Fine CuNi Alloy Nanoparticles 2-1 to 2-5>
The flask was charged with 30 mmol of oleylamine (OA, C ₁₈ H ₃₅ NH ₂ ) and 1.7 mmol of Cu acetylacetonate (Cu (acac) ₂ , Cu (C ₅ H ₇ O ₂ ) ₂ ), and 0.4 L / nitrogen gas was added. The synthesis reaction was performed by stirring at 200 ° C. for 1 hour while flowing at min to obtain an oleylamine dispersion containing Cu fine particles.

The obtained oleylamine dispersion was cooled with water, 2.4 mmol of trioctylphosphine (TOP, P (C ₈ H ₁₇ ) ₃ ) and nickel chloride (NiCl ₂ ) were added in the amounts shown in Table 2, and nitrogen gas was reduced to 0. The mixture was stirred at 200 ° C. for 1 hour while flowing at 4 L / min 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).

(Preparation Example 2-6)
<Preparation 2-6 of fine Cu nanoparticles for comparison>
Comparative fine Cu nanoparticles were prepared in the same manner as Preparation Examples 2-1 to 2-5 except that nickel chloride (NiCl ₂ ) was not added.

(Preparation Example 2-7)
<Preparation 2-7 of Cu ₆ Sn ₅ nanoparticles for comparison>
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 was subjected to centrifugation (3000 rpm, 20 min), and the resulting precipitate was 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.

Next, 18 mL of ethylene glycol was placed in the flask, 0.17 g (1.4 mmol) of the obtained Sn fine particles were added thereto, and 1.2 mmol of Cu acetylacetonate was added, followed by sonication (output: 100 W). To disperse Sn nanoparticles. Next, while flowing nitrogen gas at 0.1 L / min, the mixture was stirred at 100 ° C. for 3 hours to carry out a synthesis reaction to obtain an ethylene glycol dispersion containing Cu ₆ Sn ₅ nanoparticles.

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

(Evaluation test of Preparation Examples 2-1 to 2-7)
An evaluation test was performed on the fine particles obtained in Preparation Examples 2-1 to 2-7.

  First, with respect to the fine particles obtained in Preparation Examples 2-1 to 2-6, the components of each fine particle were identified by powder X-ray diffraction (XRD) measurement in the same manner as in Preparation Example 1-1. The obtained XRD spectrum is shown in FIG.

As is apparent from the results shown in FIG. 5, Cu ₂ O other than Cu was found in the Cu nanoparticles to which Ni was not added (Preparation Example 2-6), but the addition amount of nickel chloride was 0.00. At 05 mmol (Preparation Example 2-1), the peak of Cu ₂ O becomes weak, and when the addition amount of nickel chloride is 0.3 mmol or more (Preparation Examples 2-2 to 2-5), the peak of Cu ₂ O is It was confirmed that the oxidation resistance was improved with almost no observation. It was also confirmed that the peak of each particle gradually shifted from Cu to the peak position of Ni as the amount of Ni added was increased.

  Next, with respect to the fine particles obtained in Preparation Examples 2-1 to 2-6, the average particle size of each fine particle was observed by TEM in the same manner as in Preparation Example 1-1 to obtain the average particle size. The obtained results are shown in Table 2. Further, a transmission electron microscope (TEM) photograph (scale bar: 50 nm) of the fine CuNi alloy nanoparticles prepared in Preparation Examples 2-1 to 2-6, Preparation Example 2-1 in FIG. 2 is shown in FIG. 7, Preparation Example 2-3 is shown in FIG. 8, Preparation Example 2-4 is shown in FIG. 9, Preparation Example 2-5 is shown in FIG. 10, and Preparation Example 2-6 is shown in FIG.

In addition, the comparative Cu ₆ Sn ₅ nanoparticles obtained in Preparation Example 2-7 were subjected to a measurement test in the same manner as described above, and the result of TEM observation that Cu ₆ Sn ₅ was the main component from the XRD spectrum. From the results, it was confirmed that the average particle size was 10 nm.

  Next, for the fine particles obtained in Preparation Examples 2-1 to 2-6, composition analysis of the Ni ratio in the nanoparticles was performed using a high frequency inductively coupled plasma emission (ICP) analyzer (manufactured by Rigaku Corporation, model: CIROS-120EOP). Was performed by inductively coupled plasma optical emission spectrometry (ICP-OES). The obtained results are shown in Table 2.

(Example 1-1)
Cu nanoparticles prepared in Preparation Example 1-2 and fine CuNi alloy nanoparticles prepared in Preparation Example 2-3 were ground and mixed in a mortar, and 95% by mass of Cu nanoparticles and 5% with respect to all metal nanoparticles. A mixed powder containing mass% fine CuNi alloy nanoparticles was prepared. To 0.4 g of this mixed powder, 20 μL of decanol and 20 μL of 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 measuring shear strength 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 using a metal mask (diameter 5 mmφ × thickness 0.15 mm), and a bonding material layer (diameter 5 mmφ × thickness 150 μm) is applied. 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 250 degreeC, and the joined body for shear strength measurement (FIG. 12) 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 3. Table 3 shows the Ni content in the bonding layer (mixture layer).

(Examples 1-2 to 1-5)
As Cu nanoparticles, those shown in “Cu nanoparticles (A)” in Table 3 and as fine CuNi alloy nanoparticles, fine CuNi alloys shown in “fine CuNi alloy nanoparticles or fine Cu nanoparticles (B)” in Table 3 A bonding material paste was prepared in the same manner as in Example 1-1 except that the nanoparticles were used. About the obtained joining material paste, it carried out similarly to Example 1-1, and performed joint strength measurement. The obtained results are shown in Table 3.

(Examples 1-6 to 1-10)
As Cu nanoparticles, those shown in “Cu nanoparticles (A)” in Table 3 and as fine CuNi alloy nanoparticles, fine CuNi alloys shown in “fine CuNi alloy nanoparticles or fine Cu nanoparticles (B)” in Table 3 A bonding material paste was prepared in the same manner as in Example 1-1 except that the nanoparticles were used. About the obtained joining material paste, joining strength measurement was performed like Example 1-1 except joining temperature having been 300 degreeC. The obtained results are shown in Table 3.

(Comparative Example 1-1)
A bonding material paste was prepared in the same manner as in Example 1-1 except that fine CuNi alloy 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 3.

(Comparative Example 1-2)
A bonding material paste was prepared in the same manner as in Example 1-1 except that the fine Cu nanoparticles of Preparation Example 2-6 were used in place of the fine CuNi alloy nanoparticles, and a bonded body for measuring shear strength was prepared. Thus, the bonding strength of the bonding layer was obtained. The results are shown in Table 3.

(Comparative Example 1-3)
A bonding material paste was prepared in the same manner as in Example 1-1, except that the Cu ₆ Sn ₅ nanoparticles of Preparation Example 2-7 were used instead of the fine CuNi alloy nanoparticles, and a bonded body for measuring shear strength was further prepared. The bonding strength of the bonding layer was determined by manufacturing. The results are shown in Table 3.

(Comparative Example 1-4)
Joining in the same manner as in Example 1-1 except that the Cu nanoparticles of Preparation Example 1-4 were used instead of the Cu nanoparticles of Preparation Example 1-2, and the fine CuNi alloy nanoparticles of Preparation Example 2-4 were used. A material paste was prepared, and a bonded body for shear strength measurement was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 3.

(Comparative Example 1-5)
A bonding material paste was prepared in the same manner as in Example 1-1 except that the fine CuNi alloy nanoparticles were not mixed. About the obtained joining material paste, joining strength measurement was performed like Example 1-1 except joining temperature having been 300 degreeC. The obtained results are shown in Table 3.

(Comparative Example 1-6)
A joining material paste was prepared in the same manner as in Example 1-1 except that the fine Cu nanoparticles of Preparation Example 2-6 were used instead of the fine CuNi alloy nanoparticles. About the obtained joining material paste, joining strength measurement was performed like Example 1-1 except joining temperature having been 300 degreeC. The obtained results are shown in Table 3.

<Results of bond strength measurement test>
As is clear from the comparison between the results of Examples 1-1 to 1-10 and the results of Comparative Examples 1-1 to 1-6 shown in Table 3, the bonding material pastes of Examples 1-1 to 1-10 It was confirmed that a bonding layer having a high bonding strength with respect to the comparative bonding material paste having the same bonding temperature was obtained. From this result, it was confirmed in this example that a bonding material capable of forming a bonding layer having high bonding strength at a low temperature (specifically, 300 ° C. or lower) was obtained.

On the other hand, in the comparative example, the bonding layer formed of the bonding material composed only of Cu nanoparticles (average particle diameter 150 nm) has a bonding temperature of 250 ° C., a bonding strength of 11.7 MPa (Comparative Example 1-1), and a bonding temperature of 300 ° C. The bonding strength was 18.6 MPa (Comparative Example 1-5), and it was confirmed that both had low bonding strength. Moreover, the joining layer formed with the joining material which added the fine Cu nanoparticle of the preparation example 2-6 which did not add Ni with respect to Cu nanoparticle of the preparation example 1-2 is joining strength at the joining temperature of 250 degreeC. Was 3.6 MPa (Comparative Example 1-2), the bonding strength was 14.8 MPa (Comparative Example 1-6) at a bonding temperature of 300 ° C., and it was confirmed that both had low bonding strength. Furthermore, the bonding layer (Comparative Example 1-3) formed of the bonding material obtained by adding the Cu ₆ Sn ₅ nanoparticles of Preparation Example 2-7 to the Cu nanoparticles of Preparation Example 1-2 has a bonding temperature of 250. It was confirmed that the bonding strength was low at 7.4 MPa at ℃. On the other hand, the bonding layer formed of the bonding material obtained by adding fine CuNi alloy nanoparticles to the Cu nanoparticles of Preparation Example 1-2 has a bonding temperature of 250 ° C. (Examples 1-1 to 1-3). ) And a bonding temperature of 300 ° C. (Examples 1-6 to 1-10) in both cases, the bonding layer (Comparative Example 1-1) formed of the bonding material only of Cu nanoparticles of Preparation Example 1-2. It was confirmed that the bonding strength was improved as compared with the case.

  From the above results, the bonding material containing a mixture of metal nanoparticles composed of Cu nanoparticles having a specific range of particle diameter and average particle size and fine CuNi alloy nanoparticles having a specific range of average particle diameter depends on the material. It was confirmed that the bonding strength of the formed bonding layer was improved. This is presumably because the addition of Ni improves the oxidation resistance of the fine Cu nanoparticles. On the other hand, it was confirmed that in the case of fine Cu nanoparticles to which Ni was not added or fine Cu nanoparticles to which Sn other than Ni was added, the particles were likely to oxidize, so that improvement in bonding strength could not be expected.

  Next, focusing on the particle diameter of Cu nanoparticles in the metal nanoparticle mixture in the bonding material, the case where the particle diameter is changed from the Cu nanoparticles of Preparation Example 1-2 (average particle diameter 150 nm) will be considered. A bonding layer formed by a bonding material in which the fine CuNi alloy nanoparticles of Preparation Example 2-4 (average particle diameter of 15.1 nm) are added to the Cu nanoparticles of Preparation Example 1-4 (average particle diameter of 20 nm) (Comparison) In Example 1-4), the bonding strength was 0.93 MPa at a bonding temperature of 250 ° C., whereas the Cu nanoparticles of Preparation Example 1-1 (average particle size 300 nm) and the Cu nanoparticles of Preparation Example 1-3 The bonding layer formed of the bonding material obtained by adding the fine CuNi alloy nanoparticles (average particle diameter 15.1 nm) of Preparation Example 2-4 to (average particle diameter 60 nm) has a bonding temperature of 250 ° C. and a bonding strength of 13. .1 MPa (Example 1-4) and a bonding temperature of 250 ° C. and a bonding strength of 11.8 MPa (Example 1-5), both of which were formed by the bonding material of only Cu nanoparticles of Preparation Example 1-2 Layer (Comparative Example 1-1 The bonding strength is higher than has been confirmed. It was also confirmed that the bonding strength was improved when the ratio of the average particle diameter of the Cu nanoparticles to the average particle diameter of the fine CuNi alloy nanoparticles was 4-20.

  From the above results, in the case of a bonding material in which the average particle diameter of Cu nanoparticles is in the range of 50 nm to 1000 nm and the average particle diameter of fine CuNi alloy nanoparticles is in the range of 1 nm to 50 nm, the bonding layer formed of the material It was confirmed that the joint strength was improved. In addition, when the particle diameter of Cu nanoparticle is less than 50 nm, since the oxidation resistance of Cu nanoparticle is inadequate, sintering of a joining layer becomes inadequate and it is thought that intensity | strength fell. Moreover, it was confirmed that in the bonding material in which the ratio of the average particle diameter of the Cu nanoparticles and the fine CuNi alloy nanoparticles is 4 to 20, the bonding strength of the bonding layer formed of the material is improved.

(Examples 2-1 to 2-9)
The Cu nanoparticles prepared in Preparation Example 1-2 and the fine CuNi alloy nanoparticles prepared in Preparation Example 2-4 are ground and mixed in a mortar, and 99.9 to 71.0% by mass based on the total metal nanoparticles. Mixed powders containing 0.1 to 29.0 mass% fine CuNi alloy nanoparticles were prepared (Examples 2-1 to 2-9). To 0.4 g of this mixed powder, 20 μL of decanol and 20 μL of terpineol were added and stirred by a rotating / revolving mixer to prepare a bonding material paste. About the obtained joining material paste, the joined body for shear strength measurement was produced like Example 1-1, and the joining strength measurement of the joining layer was performed. Table 4 shows the obtained results.

(Comparative Example 2-1)
A bonding material paste was prepared in the same manner as in Example 2-1, except that the fine CuNi alloy nanoparticles were not mixed, and a bonded body for shear strength measurement was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 4.

(Comparative Example 2-2)
A mixed powder comprising 70.0% by mass of Cu nanoparticles prepared in Preparation Example 1-2 and 30.0% by mass of fine CuNi alloy nanoparticles prepared in Preparation Example 2-4 was prepared. Except for the above, a bonding material paste was prepared in the same manner as in Example 2-1, and a bonded body for shear strength measurement was prepared to determine the bonding strength of the bonding layer. The results are shown in Table 4.

(Comparative Example 2-3)
A bonding material paste was prepared in the same manner as in Example 2-1 except that Cu 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 4.

<Results of bond strength measurement test>
As is clear from the comparison between the results of Examples 2-1 to 2-9 and the results of Comparative Examples 2-1 to 2-3 shown in Table 4, the bonding material pastes of Examples 2-1 to 2-9 Has a content of fine CuNi alloy nanoparticles in the range of 0.1 to 29% by mass, that is, the content of Cu nanoparticles is 99% of the total amount of Cu nanoparticles and fine CuNi alloy nanoparticles. It was confirmed that a bonding layer having a high bonding strength at low temperatures can be obtained by setting the content in the range of .9 to 71% by mass. From this result, it was confirmed in this example that a bonding material capable of forming a bonding layer having high bonding strength at a low temperature (specifically, 300 ° C. or lower) can be obtained.

  On the other hand, the amount of addition of the bonding layer (Comparative Example 2-1) formed of the bonding material to which the fine CuNi alloy nanoparticles of Preparation Example 2-4 were not added and the fine CuNi alloy nanoparticles was 30% by mass. It was confirmed that all of the bonding layers (Comparative Example 2-2) formed of the bonding material have low bonding strength. In addition, it was confirmed that the bonding layer (Comparative Example 2-3) formed of the bonding material composed only of the fine CuNi alloy nanoparticles of Preparation Example 2-4 did not exhibit any strength and was easily broken.

  From the above results, it was confirmed that a bonding layer having a high bonding strength at a low temperature can be obtained by setting the content of fine CuNi alloy nanoparticles to 0.1 to 29% by mass. Moreover, it was confirmed that the content of the fine CuNi alloy nanoparticles is preferably 0.1 to 29% by mass, and more preferably 1 to 27% by mass.

(Examples 3-1 to 3-3)
The Cu nanoparticles prepared in Preparation Example 1-2 and the fine CuNi alloy nanoparticles prepared in Preparation Example 2-4 were ground and mixed in a mortar, and 95.0 mass% Cu nanoparticles with respect to all metal nanoparticles. And a mixed powder containing 5.0% by mass of fine CuNi alloy nanoparticles were prepared.

  Next, this Cu nanoparticle-fine CuNi alloy nanoparticle mixed powder was mixed with 0.3 g of a powder comprising Cu particles having a particle diameter of more than 1 μm and an average particle diameter of 5 μm in the amount shown in Table 5. On the other hand, 15 μL of decanol and 15 μL of terpineol were added and stirred by a rotation / revolution mixer to prepare a bonding material paste (metal nanoparticle mixture). About the obtained joining material paste, the joined body for shear strength measurement was produced like Example 1-1, and the joining strength measurement of the joining layer was performed. The results obtained are shown in Table 5.

(Comparative Example 3-1)
A bonding material paste was prepared in the same manner as in Example 3-1, except that the amount of Cu micron particles mixed with the Cu nanoparticle-fine CuNi alloy nanoparticle mixed powder was 90.0% by mass. A bonded body for measurement was prepared, and the bonding strength of the bonding layer was determined. The results are shown in Table 5.

<Results of bond strength measurement test>
As is clear from the results shown in Table 5, the content of Cu micron particles in the bonding material (metal nanoparticle mixture consisting of Cu nanoparticle-fine CuNi alloy nanoparticle mixed powder + Cu micron particle) is 25 to 85% by mass. The bonding strength of the bonding layers (Examples 3-1 to 3-3) formed by the bonding material formed was determined by the bonding layer (comparative example) formed by the bonding material in which the content of Cu micron particles was 90.0% by mass. It was confirmed that the bonding strength of the bonding layer (Comparative Example 2-1) formed of the bonding material of only Cu nanoparticles prepared in 3-1) and Preparation Example 1-2 was increased.

  From the above results, even in the case of the bonding material in which the content of Cu micron particles in the bonding material is 85% by mass or less of the total metal powder, the bonding material of only Cu nanoparticles prepared in Preparation Example 1-2 (Comparative Example) It was confirmed that a bonding layer having higher bonding strength than that of (2-1) can be formed at a low temperature (specifically, 300 ° C. or lower).

  From the above, the results of Examples 1-1 to 1-10 and Examples 2-1 to 2-9 shown in Table 3 and Table 4, and Comparative Examples 1-1 to 1-6 and Comparative Examples 2-1 to 2-1 As is clear from the comparison with the results of 2-9, the bonding material pastes of Examples 1-1 to 1-10 and Examples 2-1 to 2-9 are composed of Cu particles having a particle diameter of 1000 nm or less and A metal nanoparticle mixture comprising Cu nanoparticles having an average particle diameter of 50 nm to 1000 nm and fine CuNi alloy nanoparticles having an average particle diameter of 1 nm to 50 nm is contained, and the fine CuNi alloy nanoparticle in the metal nanoparticle mixture By using a bonding material having a particle content of 0.1 to 29% by mass and a metal nanoparticle mixture content of 15% by mass or more, a bonding layer having high bonding strength can be obtained at a low temperature ( Specifically, below 300 ° C) It was confirmed that can be joined material capable of forming.

  As described above, according to the present invention, it is possible to obtain a bonding material capable of forming a bonding layer having a sufficiently high bonding strength at no pressure and at a low temperature (specifically, 300 ° C. or lower). Therefore, the bonding material 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 (7)

Containing a metal nanoparticle mixture comprising Cu nanoparticles having a particle diameter of 1000 nm or less and an average particle diameter of 60 nm to 300 nm and fine CuNi alloy nanoparticles having an average particle diameter of 1 nm to 50 nm. The content of the fine CuNi alloy nanoparticles in the metal nanoparticle mixture is 0.1 to 29% by mass, and the content of the metal nanoparticle mixture is 15% by mass or more. Bonding material.   The bonding material according to claim 1, wherein a ratio of an average particle diameter of the Cu nanoparticles to an average particle diameter of the fine CuNi alloy nanoparticles is 2 to 60.   The joining material according to claim 1 or 2, wherein the content of Ni contained in the fine CuNi alloy nanoparticles is 2 to 90 mass%. Metal nanoparticle mixture comprising Cu nanoparticles having a particle diameter of 1000 nm or less and an average particle diameter of 50 nm to 1000 nm, and fine CuNi alloy nanoparticles having an average particle diameter of 1 nm to 50 nm, and particles Cu microparticles comprising Cu particles having a diameter of more than 1 μm and an average particle diameter of more than 1 μm and not more than 200 μm are contained, and the content of the fine CuNi alloy nanoparticles in the metal nanoparticle mixture is 0.1 to 29 is the mass%, the metal content of the nanoparticle mixture is at least 15 wt%, and junction material you wherein the content of the Cu-micron particles is more than 85 wt%. A semiconductor element, a substrate, and a bonding layer for bonding the semiconductor element and the substrate;
A semiconductor device, wherein the bonding layer is a mixture layer of Cu and a CuNi alloy formed of the bonding material according to claim 1.   The semiconductor device according to claim 5, wherein a content of Ni contained in the mixture layer is 0.0003 to 26.1 mass%. Further comprising an adhesion layer made of at least one metal selected from the group consisting of Ni, Co and Ag on both surfaces of the mixture layer,
7. The semiconductor according to claim 5, wherein one adhesion layer is disposed so as to be in contact with a bonding portion of the semiconductor element, and the other adhesion layer is disposed so as to be in contact with a bonding portion of the substrate. apparatus.