JP2020007593A - Joint material, joint material paste containing the same, and joint method and semiconductor device using the same - Google Patents

Abstract

To provide a joint material capable of jointing metal members such as a semiconductor element or a substrate with high joint strength even when they are jointed while applying lower pressure.SOLUTION: There is provided a joint material containing surface coated Cu nanoparticles having Cu nanoparticles with an average particle diameter of 10 to 1000 nm, and an organic coated film arranged on a surface of the Cu nanoparticles, containing at least one kind of group of a carboxyl group and an amino group, and capable of detaching from the surface by heating, and Zn particles consisting of one kind selected from a group consisting of zinc, zinc alloy, and zinc oxide, and having an average particle diameter of 0.01 to 100 μm, in which content of the Zn particles based on the total amount of the surface coated Cu nanoparticles and the Zn-based particles is 2 to 55 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a bonding material containing at least copper nanoparticles, a bonding material paste containing the same, a bonding method using the same, and a semiconductor device.

  Conventionally, Sn-Pb based solders have been used for electrode bonding of semiconductor elements, but in recent years, from the viewpoint of environmental protection, new bonding materials such as lead-free solders have been required. In addition, in the technology of joining semiconductor elements, a material that can be joined at a low temperature is required in order to reduce the load on the semiconductor element. Further, when the particle size of metal particles such as Ag, Cu, and Ni is reduced to a nanometer size, it can be sintered at a temperature much lower than its melting point. Is expected.

  However, such metal fine particles have a high surface activity and are easily aggregated, so that they are usually coated with a surfactant or a polymer to ensure dispersion stability. Therefore, if a heat treatment is performed when a semiconductor element is joined using such metal fine particles, the metal fine particles are sintered and a film of a surfactant or a polymer is decomposed, and gas is generated. Voids are generated between the fine particles. As a result, the sintered structure did not become dense under no pressure or low temperature, and a sufficiently high joining strength could not be obtained.

  On the other hand, Japanese Patent Application Laid-Open No. 2012-46779 (Patent Document 1) discloses a surface-coated Cu nanoparticle in which the surface of the Cu nanoparticle is coated with an organic film containing a fatty acid having 8 or more carbon atoms and an aliphatic amine. Has been described. In order to bond metal members with high bonding strength using the surface-coated Cu nanoparticles alone as a bonding material, it was necessary to bond while applying a large pressure.

  Japanese Patent Application Laid-Open No. 2017-147151 (Patent Document 2) discloses a conductive paste containing Cu-based nanoparticles whose surfaces are coated with organic molecules, Ni-based coarse particles, an organic solvent, and a surface. Describes a conductive paste containing Ni-based nanoparticles coated with organic molecules, coarse Cu particles, and an organic solvent, and those composed of an alloy of Cu and Zn or the like as the coarse Cu particles. ing. This conductive paste is effective for bonding a metal member having an adhesion layer containing a specific metal element such as Ni on the surface, but for bonding other metal members with high bonding strength. It was necessary to join while applying a large pressure.

  Further, JP-A-2017-101313 (Patent Document 3) contains Bi-Sn alloy particles and surface-coated Cu fine particles in which the surfaces of Cu fine particles are coated with an organic film detachable by heating. A bonding material is described, and a bonding layer excellent in heat resistance is formed by including third metal particles made of Ag, Ni, Zn, etc. in addition to the surface-coated Cu fine particles and the Bi-Sn alloy particles. Is described. By using this joining material, it was possible to join metal members even when joining while applying a relatively low pressure, but the joining strength is not always sufficient, and the applied pressure , The bonding strength was sometimes reduced.

JP 2012-46779 A JP-A-2017-147151 JP 2017-101313 A

  The present invention has been made in view of the above-mentioned problems of the related art, and enables metal members such as semiconductor elements and substrates to be bonded with high bonding strength even when bonding is performed while applying lower pressure. An object of the present invention is to provide a bonding material that can be used, a bonding material paste containing the same, a bonding method using the same, and a semiconductor device.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a bonding material containing Cu nanoparticles having an organic coating on the surface (surface-coated Cu nanoparticles) and Zn-based particles at a specific ratio. Using a bonding material layer formed by this bonding material is heated at a temperature equal to or higher than the desorption start temperature of the organic coating to release the organic coating from the surface-coated Cu nanoparticles, and to reduce the Cu nanoparticles. The constituent Cu and the constituent Zn are reacted with each other to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound, and the Cu constituting the Cu nanoparticles is bonded by firing. The present inventors have found that by forming a layer, it is possible to join metal members with high joining strength even when joining while applying a lower pressure, and have completed the present invention.

  That is, the bonding material of the present invention contains Cu nanoparticles having an average particle diameter of 10 to 1000 nm, and is disposed on the surface of the Cu nanoparticles, and contains at least one group of a carboxyl group and an amino group. And a surface-coated Cu nanoparticle provided with an organic film capable of desorbing from the surface, and one selected from the group consisting of zinc, a zinc alloy and a zinc oxide, and having an average particle diameter of 0.1. It contains Zn-based particles of 01 to 100 µm, and the content of the Zn-based particles is 2 to 55% by mass based on the total amount of the surface-coated Cu nanoparticles and the Zn-based particles. is there. In such a bonding material of the present invention, it is preferable that the organic coating has a desorption start temperature lower than the melting point of the Zn-based particles. Further, the bonding material paste of the present invention contains the bonding material of the present invention.

  The bonding method according to the present invention includes the first member and the second member whose surfaces are made of metal, and the bonding material according to the present invention or the bonding according to the present invention, which are in contact with the surfaces of the first member and the second member. A step of forming a laminate including a bonding material layer formed using a material paste, and heating the bonding material layer at a temperature equal to or higher than the desorption start temperature of the organic film, and from the surface-coated Cu nanoparticles The organic coating is removed, and Cu constituting the Cu nanoparticles is reacted with Zn constituting the Zn-based particles to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound. And baking Cu constituting the Cu nanoparticles to form a bonding layer.

  A semiconductor device of the present invention includes a semiconductor element, a semiconductor substrate, and a bonding layer disposed between the semiconductor element and the semiconductor substrate, and formed using the bonding material or the bonding material paste of the present invention. Are provided.

The “desorption start temperature of the organic film” in the present invention is based on the desorption of the organic film by performing thermogravimetric analysis on the surface-coated Cu nanoparticles in an atmosphere of an inert gas such as Ar or N _2. It is defined as the lowest temperature in the temperature range in which mass loss is recognized, that is, the temperature at which mass loss starts in the heating process.

  In addition, the reason why it is possible to join metal members with high joining strength even when joining by applying a lower pressure by the joining material of the present invention is not necessarily clear, but the present inventors have Infer as follows. That is, when the bonding material layer formed by the bonding material of the present invention is heated at a temperature equal to or higher than the desorption start temperature of the organic coating, the organic coating is released from the surface-coated Cu nanoparticles, and the Cu constituting the Cu nanoparticles is removed. Reacts with Zn constituting the Zn-based particles to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound, and sinter Cu constituting the Cu nanoparticles. When the bonding material layer contains a Cu—Zn solid solution or a Cu—Zn intermetallic compound, the melting point of the bonding material is reduced, so that sintering of Cu is promoted and even if the pressure applied during bonding is reduced, high bonding is achieved. It is presumed that a bonding layer having strength is formed.

  ADVANTAGE OF THE INVENTION According to this invention, even if it joins, applying a lower pressure, it becomes possible to join metal members, such as a semiconductor element and a board | substrate, with high joining strength.

FIG. 2 is a schematic diagram showing a preferred embodiment of the semiconductor device of the present invention. It is a schematic diagram which shows the joined body manufactured by the Example and this invention.

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

<Joining materials>
First, the bonding material of the present invention will be described. The bonding material of the present invention has Cu nanoparticles having an average particle diameter of 10 to 1000 nm, and is disposed on the surface of the Cu nanoparticles, and contains at least one group of a carboxyl group and an amino group. A surface-coated Cu nanoparticle comprising an organic film capable of desorbing from the surface, and one selected from the group consisting of zinc, zinc alloy and zinc oxide, having an average particle diameter of 0.01 to A bonding material containing 100 μm Zn-based particles, wherein the content of the Zn-based particles is 2 to 55% by mass based on the total amount of the surface-coated Cu nanoparticles and the Zn-based particles.

  The surface-coated Cu nanoparticles used in the present invention include Cu nanoparticles and at least one group of a carboxyl group and an amino group, which are arranged on the surface of the Cu nanoparticles and are removed from the surface by heating. An organic film that can be separated. By providing such organic coating on the surface of the Cu nanoparticles, oxidation and aggregation of the Cu nanoparticles can be prevented, and sintering of Cu during firing can be promoted.

  The average particle size of such Cu nanoparticles is 10 to 1000 nm. When the average particle diameter of the Cu nanoparticles is less than the lower limit, the surface of the Cu nanoparticles is oxidized, so that sintering of the Cu nanoparticles is inhibited, and the bonding strength, conductivity, and thermal conductivity of the bonding layer are improved. On the other hand, if the upper limit is exceeded, the surface energy of the Cu nanoparticles becomes small, so that the sintering of the Cu nanoparticles does not proceed, and the bonding strength, electrical conductivity, and thermal conductivity of the bonding layer are not improved. Furthermore, from the viewpoint that sintering of the Cu nanoparticles is hardly inhibited and the bonding strength, electrical conductivity, and thermal conductivity of the bonding layer are improved, the average particle size of the Cu nanoparticles is preferably 50 to 300 nm, and 80 to 200 nm. Is more preferred. The average particle diameter is an arithmetic average value obtained by measuring diameters of 200 randomly extracted Cu nanoparticles in transmission electron microscope (TEM) observation.

  The organic coating according to the present invention is not particularly limited as long as it contains at least one group of a carboxyl group and an amino group and can be released from the surface of the Cu nanoparticles by heating. In addition, an organic film having a desorption initiation temperature of Cu nanoparticles lower than the melting point of Zn-based particles described below is preferable. When the desorption start temperature of the organic film is higher than the melting point of the Zn-based particles, it is necessary to heat at an extremely high temperature (for example, 420 ° C. or higher) in order to desorb the organic film from the surface-coated Cu nanoparticles. Energy costs at times tend to be higher.

  Further, the desorption start temperature of the organic film is preferably from 200 to 300C. When the desorption start temperature of the organic film is lower than the lower limit, the organic film tends to be unstable, and it tends to be difficult to maintain the shape of Cu nanoparticles. The temperature tends to increase, and the reliability of the semiconductor device tends to decrease. The organic film having the desorption initiation temperature satisfying the above range includes fatty acids (preferably having 8 to 18 carbon atoms, more preferably having 8 to 16 carbon atoms, particularly preferably having 8 to 14 carbon atoms) and aliphatic amines ( An organic coating containing at least one (preferably both) of preferably 8 to 18 carbon atoms, more preferably 8 to 16 carbon atoms, and particularly preferably 8 to 14 carbon atoms.

  Further, the molar ratio between the aliphatic amine and the fatty acid (aliphatic amine / fatty acid) in such an organic coating is preferably from 0.001 / 1-1 / 1, more preferably from 0.001 / 1-1 / 15/1. Is more preferable, and 0.001 / 1 to 0.1 / 1 is particularly preferable. When the proportion of the aliphatic amine is less than the lower limit, the organic coating does not stably exist on the surface of the Cu nanoparticles, and the Cu nanoparticles tend to aggregate. The separation start temperature tends to exceed the upper limit.

  Such surface-coated Cu nanoparticles used in the present invention can be prepared, for example, by the method described in JP-A-2012-46779, that is, a Cu salt which is insoluble in an alcohol-based solvent in an alcohol-based solvent. Producing Cu nanoparticles by reduction in the presence of at least one of a fatty acid and an aliphatic amine, and containing at least one of the fatty acid and the aliphatic amine on the surface of the Cu nanoparticle. It can be manufactured by a method of forming an organic film.

  The Zn-based particles used in the present invention are made of one selected from the group consisting of zinc, zinc alloy and zinc oxide. By using such Zn-based particles, Zn constituting the Zn-based particles reacts with Cu constituting Cu nanoparticles to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound. Is done. Such a bonding material containing a Cu-Zn solid solution or a Cu-Zn intermetallic compound has a lower melting point than a bonding material containing only Cu, so that sintering of Cu is promoted at a lower temperature, and a Even if the applied pressure is reduced, a bonding layer having high bonding strength is formed.

  Further, as the Zn-based particles used in the present invention, particles made of metal zinc (metal Zn particles) are particularly preferable from the viewpoint that sintering is promoted by active Zn atoms, but the particles react with Cu by firing. Since it is easily reduced to a metallic Zn state, there is no particular problem even with Zn particles whose surface is partially or entirely oxidized (that is, surface partially oxidized Zn particles or surface oxidized Zn particles). Further, as the Zn-based particles, particles made of a zinc alloy (Zn alloy particles) can also be used. Examples of alloying elements constituting the Zn alloy particles include iron, titanium, nickel, and aluminum. In addition, the Zn content in the Zn alloy particles is preferably 80 atomic% or more, and more preferably 90 atomic% or more, from the viewpoint of effectively utilizing the activity of Zn. As the Zn-based particles, those having an organic coating on the surface may be used, but those having no organic coating are preferable from the viewpoint that a bonding layer having a small amount of impurities and high bonding strength is formed.

  The average particle diameter of such Zn-based particles is 0.01 to 100 μm. It is difficult to prepare Zn-based particles having an average particle size less than the lower limit, while if the average particle size exceeds the upper limit, printability and coatability of the bonding material and its paste are reduced. Further, from the viewpoint of the handling properties of the Zn-based particles and the printability and coatability of the bonding material and the paste thereof, the average particle diameter of the Zn-based particles is preferably 1 to 50 μm, more preferably 3 to 20 μm. The average particle diameter is an arithmetic average value obtained by measuring the diameters of 200 randomly extracted Zn-based particles in a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

  The bonding material of the present invention contains the surface-coated Cu nanoparticles and Zn-based particles. In such a bonding material, the content of the Zn-based particles is 2 to 55% by mass based on the total amount of the surface-coated Cu nanoparticles and the Zn-based particles. When the content of the Zn-based particles is less than the lower limit, the effect of adding the Zn-based particles (improvement of bonding strength) cannot be obtained. On the other hand, when the content exceeds the upper limit, sintering of Cu in the bonding layer does not proceed, Bonding strength decreases. In addition, from the viewpoint that the joining strength of the joining layer is further increased, the content of the Zn-based particles is preferably 3 to 50% by mass, more preferably 20 to 50% by mass, and still more preferably 25 to 40% by mass. -35% by mass is particularly preferred.

  Further, in the bonding material of the present invention, other metal particles made of copper, nickel, or the like and having an average particle diameter of 1 to 100 μm may be included as long as the effects of the present invention are not impaired. . By including such other metal particles, it is possible to reduce cracks and the like due to sintering shrinkage. As such other metal particles, those having an organic coating on the surface may be used, but those having no organic coating are preferable from the viewpoint of forming a bonding layer having a small amount of impurities and a high bonding strength.

  The content of such other metal particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on all the metal particles (the total amount of surface-coated Cu nanoparticles, Zn-based particles, and other metal particles). More preferred. If the content of the other metal particles exceeds the upper limit, the joining strength tends to decrease.

  In addition, the bonding material of the present invention may be used as a paste (the bonding material paste of the present invention) by adding an organic solvent, fat or the like from the viewpoint of printability and coatability, or may be pressed and sheeted. It may be formed into a shape. Examples of the organic solvent used for the paste include monoterpene alcohols such as α-terpineol, aliphatic alcohols such as 1-octanol and 1-decanol, and high-boiling organic solvents such as glycerin. Further, an organic compound such as polyethylene glycol may be added to such a bonding material paste for viscosity adjustment.

<Joining method>
Next, the joining method of the present invention will be described. The bonding method of the present invention uses the first member and the second member whose surfaces are made of metal, and the bonding material or the bonding material paste of the present invention, which is in contact with the surfaces of the first member and the second member. Forming a laminate including a bonding material layer formed by heating, the bonding material layer is heated at a temperature equal to or higher than the desorption start temperature of the organic coating, and the organic coating is formed from the surface-coated Cu nanoparticles. While being desorbed, Cu constituting the Cu nanoparticles is reacted with Zn constituting the Zn-based particles to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound, and Baking Cu constituting Cu nanoparticles to form a bonding layer.

  In the joining method of the present invention, first, a first member and a second member are formed using the joining material or the joining material paste of the present invention, which is in contact with the surfaces of the first member and the second member. And a bonding material layer formed. The method for forming such a laminate is not particularly limited. For example, the bonding material paste of the present invention is printed or applied on the surface of the first member, and the second member is formed on the surface of the formed bonding material paste layer. A sheet (hereinafter, referred to as a “joining material sheet”) obtained by compacting the joining material of the present invention on the surface of the first member and laminating the second member on the surface of the joining material sheet. A method of laminating; a method of sandwiching the bonding material sheet between the first member and the second member, and the like.

  The first member is not particularly limited as long as the surface is made of metal. For example, a Cu plate (for example, a substrate for semiconductor), a ceramic plate having a metal adhered to the surface, or an alloy such as a Cu alloy or a Ni alloy Plate. The second member is not particularly limited as long as it has a metal surface. For example, a semiconductor element (Si chip, SiC chip, GaN chip) or a metal plate (Cu plate, Ni plate, Al plate) may be used. No.

  Next, the thus-formed laminate composed of the first member / the bonding material layer / the second member is heated at a temperature equal to or higher than the desorption start temperature of the organic film. As a result, the organic film is detached from the surface of the surface-coated Cu nanoparticles, and Cu constituting the Cu nanoparticles reacts with Zn constituting the Zn-based particles to form a Cu-Zn solid solution and a Cu-Zn intermetallic compound. At least one of which is formed. This lowers the melting point of the bonding material layer, so that sintering of Cu is promoted and a bonding layer having high bonding strength is formed even when the pressure applied during bonding is reduced. Even if a part or the whole of the surface of the Zn particles is oxidized, the Zn oxide is reduced during the reaction between Cu and Zn, and the reaction product is released out of the system. Almost no Zn oxide remains in the bonding layer, which hinders embrittlement and promotes embrittlement.

  Further, in the bonding method of the present invention, before heating the laminate including the first member / the bonding material layer / the second member at a temperature equal to or higher than the desorption start temperature of the organic coating, the laminate is subjected to the organic coating. It may be heated at a temperature lower than the desorption start temperature. This makes it possible to remove organic components other than the organic film, such as an organic solvent, remaining in the bonding material layer, and to obtain a bonding layer having high bonding strength.

  A semiconductor device as shown in FIG. 1 is manufactured by such a bonding method of the present invention. Specifically, by using the semiconductor substrate 1 as the first member and the semiconductor element 2 as the second member, and applying the bonding method of the present invention, the semiconductor substrate 1, the semiconductor element 2, and the semiconductor element The bonding strength between the semiconductor substrate 1 and the semiconductor element 2, which is provided between the substrate 1 and the semiconductor element 2 and includes the bonding layer 3 formed using the bonding material of the present invention. An excellent semiconductor device can be manufactured. In particular, as at least one (preferably both) of the semiconductor substrate 1 and the semiconductor element 2, a metal capable of reacting with Zn to form an intermetallic compound in a contact region of the surface with the bonding layer 3. In the case of using a semiconductor device including a semiconductor device, a semiconductor device in which the bonding strength between the semiconductor substrate 1 and the semiconductor element 2 is further improved can be manufactured.

  Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. The method for measuring the desorption start temperature and bonding strength of the organic film and the method for preparing Cu nanoparticles having the organic film are described below.

(1) elimination using starting temperature thermogravimetric analyzer (manufactured by Rigaku Corporation), Ar or an inert gas atmosphere of N _2, heating while surface-coated Cu nano at 20 ° C. / min up to 500 ° C. from room temperature The particles were subjected to thermogravimetric analysis (TG analysis). On the basis of the obtained TG curve, a temperature range in which the mass loss due to desorption (decomposition) of the organic film was recognized was determined, and the lower limit temperature was defined as the desorption start temperature of the organic film.

(2) Bonding strength Tool height: 50 μm from the surface of the Cu plate, shear rate: 50 μm / second, a shearing test was performed by applying a shearing tool to the Si chip, and the shear strength per bonded area of the Si chip was determined. This was defined as the bonding strength.

(Preparation Example 1)
The surface-coated Cu nanoparticles were prepared according to the method described in JP-A-2012-46779. That is, 600 ml of ethylene glycol (HO (CH ₂ ) ₂ OH) was placed in the flask, and 120 mmol of copper carbonate (CuCO ₃ .Cu (OH) ₂ .H ₂ O) was added thereto. In addition, copper carbonate precipitated almost without dissolving in ethylene glycol. After adding 180 mmol of dodecanoic acid (C ₁₁ H ₂₃ COOH) and 60 mmol of 1-dodecylamine (C ₁₂ H ₂₅ NH ₂ ), the mixture was heated and refluxed at 198 ° C. for 1 hour while flowing nitrogen gas at 1 L / min. Then, surface-coated Cu nanoparticles having an organic coating composed of dodecanoic acid and 1-dodecylamine on the surfaces of the Cu nanoparticles were obtained. The surface-coated Cu nanoparticles were recovered by dispersing in hexane, washed with acetone and ethanol sequentially added, recovered by centrifugation (3000 rpm, 20 min), and vacuum dried (35 ° C., 30 min). .

  The obtained surface-coated Cu nanoparticles are dispersed in toluene, and this dispersion is applied to a Cu microgrid with an elastic carbon support film (polymer material film (15 to 20 nm thick) + carbon film (20 to 25 nm thick)) (Oken Shoji) (Manufactured by K.K.) and dried naturally to prepare an observation sample. This observation sample was observed at an acceleration voltage of 200 kV using a transmission electron microscope (TEM, “JEM-2000EX” manufactured by JEOL Ltd.). In this TEM observation, 200 surface-coated Cu nanoparticles were randomly extracted, and their diameters were measured and arithmetically averaged. As a result, the average particle diameter of the Cu nanoparticles was 140 nm. Further, the desorption start temperature of the organic film in the surface-coated Cu nanoparticles was measured by the above method, and was 250 ° C.

(Example 1)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Zn particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. (Zinc purity: 99% by mass, average particle size: 7 μm, melting point: 419.5 ° C.) so that the mass ratio becomes 70% by mass: 30% by mass, and 1-decanol (1-decanol) is used as a solvent in the obtained mixture. 70 μl of 1 g of the mixture was dropped into 1 g of the mixture to disperse the mixture to prepare a bonding material paste.

  Next, a joined body shown in FIG. 2 was produced using this joining material paste. That is, Cu (thickness: 0.15 mm) / SiN () has a multilayer film 11 in which Ag (thickness: 100 nm) / Ni (thickness: 200 nm) / Ti (thickness: 100 nm) is laminated from the front side. The bonding material paste is formed to a thickness of 100 μm in a 5 mm × 5 mm region on the Ag surface of a laminate (made by Denka Corporation) 12 made of thickness: 0.32 mm) / Cu (thickness: 0.15 mm). SiC wafer having a multilayer film 11 in which Ag (thickness: 100 nm) / Ni (thickness: 200 nm) / Ti (thickness: 100 nm) is laminated from the surface side on the applied and obtained bonding material layer (5 mm × 5 mm × 0.35 mm thick) 13 cut out from (4H structure SiC single crystal (0001) plane, manufactured by Tanque Blue Co., Ltd.) was used to form the bonding material layer and the silver surface of the SiC chip 13. It was stacked so that.

The heat treatment at 200 ° C. for 10 minutes and the heat treatment at 350 ° C. for 5 minutes in the H ₂ atmosphere were performed while applying a uniaxial load to the laminate surface of the obtained laminate so that the surface pressure became 20 kPa. This was applied to the body and Cu was sintered to produce a semiconductor device (joined body) composed of the laminated plate 12 / the multilayer film 11 / the bonding layer 14 / the multilayer film 11 / the SiC chip 13. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. The results are shown in Tables 1 and 2.

(Example 2)
A bonding material paste was prepared in the same manner as in Example 1 except that the mass ratio between the surface-coated Cu nanoparticles and the Zn particles obtained in Preparation Example 1 was changed to 97% by mass: 3% by mass. A semiconductor device (joined body) composed of / the multilayer film 11 / the bonding layer 14 / the multilayer film 11 / the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. The results are shown in Tables 1 and 3.

(Example 3)
A bonding material paste was prepared in the same manner as in Example 1 except that the mass ratio between the surface-coated Cu nanoparticles and Zn particles obtained in Preparation Example 1 was changed to 80% by mass: 20% by mass. A semiconductor device (joined body) composed of / the multilayer film 11 / the bonding layer 14 / the multilayer film 11 / the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. The results are shown in Tables 1 and 4.

(Example 4)
A bonding material paste was prepared in the same manner as in Example 1 except that the mass ratio between the surface-coated Cu nanoparticles and Zn particles obtained in Preparation Example 1 was changed to 50% by mass: 50% by mass. A semiconductor device (joined body) composed of / the multilayer film 11 / the bonding layer 14 / the multilayer film 11 / the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. The results are shown in Tables 1 and 5.

(Comparative Example 1)
A bonding material paste (surface-coated Cu nanoparticles: Zn particles = 100% by mass: 0% by mass) was prepared in the same manner as in Example 1 except that Zn particles were not mixed, and the laminate 12 / the multilayer film 11 was prepared. A semiconductor device (joined body) composed of / the bonding layer 14 / the multilayer film 11 / the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 1 shows the results.

(Comparative Example 2)
A bonding material paste was prepared in the same manner as in Example 1 except that the mass ratio between the surface-coated Cu nanoparticles and Zn particles obtained in Preparation Example 1 was changed to 40% by mass: 60% by mass. A semiconductor device (joined body) composed of / the multilayer film 11 / the bonding layer 14 / the multilayer film 11 / the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 1 shows the results.

(Comparative Example 3)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ni particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. Nickel purity: 99.9% by mass, particle diameter: 2 to 3 μm, melting point: 1455 ° C.) in the same manner as in Example 1 except that the mass ratio was 70% by mass: 30% by mass. A paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 2 shows the results.

(Comparative Example 4)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ag particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. (Silver purity: 99.9% by mass, particle size: about 1 μm, melting point: 961.8 ° C.) except that the mass ratio was 70% by mass: 30% by mass. A material paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 2 shows the results.

(Comparative Example 5)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ni particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. Nickel purity: 99.9% by mass, particle diameter: 2-3 μm, melting point: 1455 ° C.) in the same manner as in Example 1 except that the mass ratio was 97% by mass: 3% by mass. A paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 3 shows the results.

(Comparative Example 6)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ag particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. (Silver purity: 99.9% by mass, particle size: about 1 μm, melting point: 961.8 ° C.) except that the mass ratio was 97% by mass: 3% by mass. A material paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 3 shows the results.

(Comparative Example 7)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ni particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. Nickel purity: 99.9% by mass, particle diameter: 2-3 μm, melting point: 1455 ° C.) in the same manner as in Example 1 except that the mass ratio was 80% by mass: 20% by mass. A paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 4 shows the results.

(Comparative Example 8)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ag particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. (Silver purity: 99.9% by mass, particle diameter: about 1 μm, melting point: 961.8 ° C.) except that the mass ratio was 80% by mass: 20% by mass. A material paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 4 shows the results.

(Comparative Example 9)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ni particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. Nickel purity: 99.9% by mass, particle diameter: 2-3 μm, melting point: 1455 ° C.) in the same manner as in Example 1 except that the mass ratio was 50% by mass: 50% by mass. A paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 5 shows the results.

(Comparative Example 10)
Surface-coated Cu nanoparticles obtained in Preparation Example 1 (average particle diameter: 140 nm, desorption start temperature of the organic film: 250 ° C.) and Ag particles whose surface is not coated (manufactured by Kojundo Chemical Laboratory Co., Ltd. (Silver purity: 99.9% by mass, particle size: about 1 μm, melting point: 961.8 ° C.) except that the mass ratio was 50% by mass: 50% by mass. A material paste was prepared, and a semiconductor device (joined body) including the laminated plate 12, the multilayer film 11, the bonding layer 14, the multilayer film 11, and the SiC chip 13 was manufactured. The bonding strength between the laminate and the Si chip in the obtained semiconductor device was measured by the above method. Table 5 shows the results.

  As shown in Table 1, when the bonding material (Examples 1 to 4) of the present invention containing the surface-coated Cu nanoparticles and the Zn-based particles at a predetermined ratio was used, the Zn-based particles were included. It was found that the bonding strength was higher than when a bonding material that did not contain (Comparative Example 1) or a bonding material that did not contain Zn-based particles at a predetermined ratio (Comparative Example 2) was used. Also, it was found that when the content of the Zn-based particles was 20 to 50% by mass, the bonding strength was further increased.

  In addition, as shown in Tables 2 to 5, the content of the surface-coated Cu nanoparticles is the same, and Example 1 and Comparative Examples 3 to 4, Example 2 and Comparative Examples 5 to 6, and Example 3 As is clear from comparison of Comparative Examples 7 to 8 and Example 4 with Comparative Examples 9 to 10, when the bonding material of the present invention containing surface-coated Cu nanoparticles and Zn-based particles was used, It was found that the bonding strength was higher than that of a bonding material containing surface-coated Cu nanoparticles and Ni particles or Ag particles.

  As described above, according to the present invention, it is possible to join metal members such as semiconductor elements and substrates with high joining strength even when joining while applying lower pressure.

  Therefore, the bonding method of the present invention uses a bonding material capable of bonding metal members with high bonding strength even when bonding is performed while applying a lower pressure, so that a lower pressure is applied. This makes it possible to manufacture a semiconductor device while the semiconductor element is firmly joined to the substrate and is useful as a method for manufacturing a semiconductor device in which cracks in the semiconductor element and the substrate are suppressed.

1: semiconductor substrate 2: semiconductor element 3: bonding layer 4: lead frame 5: bonding wire 11: multilayer film 12: laminated plate 13: SiC chip 14: bonding layer

Claims (5)

Cu nanoparticles having an average particle diameter of 10 to 1000 nm, and are arranged on the surface of the Cu nanoparticles and contain at least one group of a carboxyl group and an amino group, and can be desorbed from the surface by heating. A surface-coated Cu nanoparticle provided with a possible organic coating, and one or more selected from the group consisting of zinc, zinc alloy and zinc oxide, and containing Zn-based particles having an average particle diameter of 0.01 to 100 μm. ,
A bonding material, wherein the content of the Zn-based particles is 2 to 55% by mass based on the total amount of the surface-coated Cu nanoparticles and the Zn-based particles.   The bonding material according to claim 1, wherein the organic coating has a desorption starting temperature lower than a melting point of the Zn-based particles.   A bonding material paste comprising the bonding material according to claim 1. The joining material according to claim 1 or 2, wherein the joining material according to claim 1 or 2 is in contact with the first member and the second member whose surfaces are made of metal, and is in contact with the surfaces of the first member and the second member. A step of forming a laminate including a bonding material layer formed using a paste,
The bonding material layer is heated at a temperature equal to or higher than the desorption start temperature of the organic coating, and the organic coating is released from the surface-coated Cu nanoparticles, and the Cu and Zn-based particles constituting the Cu nanoparticles are removed. Reacting Zn to form at least one of a Cu-Zn solid solution and a Cu-Zn intermetallic compound, and baking Cu forming the Cu nanoparticles to form a bonding layer. When,
A joining method comprising:   A semiconductor element, a substrate for a semiconductor, and a semiconductor element, the semiconductor element being disposed between the semiconductor element and the semiconductor substrate, formed using the bonding material according to claim 1 or the bonding material paste according to claim 3. A semiconductor device, comprising: a bonding layer.