Oxide-containing copper particles, paste composition, semiconductor device, electrical component and electronic component

Abstract

The present invention provides: oxide-containing copper particles which enable the achievement of a paste composition that is capable of forming a bonding layer having high denseness, high bonding strength and high bonding reliability; a paste composition which uses the oxide-containing copper particles; and a semiconductor device, an electrical component and an electronic component. With respect to oxide-containing copper particles according to the present disclosure, the absorption spectrum as measured with a spectrophotometer by dispersing the oxide-containing copper particles in ethanol that has a mass of 1 × 106 times the mass of the oxide-containing copper particles has an absorption peak within the wavelength range of 600 nm to 1,000 nm.

Description

Technical Field

[0001] The present disclosure relates to copper particles containing an oxide, a paste composition using the same, and semiconductor devices, electrical components, and electronic components.

Background Art

[0002] In semiconductor devices, various electrical components, and electronic components, a highly thermally conductive paste is used as an adhesive for joining each member. In semiconductor devices, heat generation associated with high integration and high-speed operation is increasing. In order to obtain stable operability, for example, a heat-generating member such as a semiconductor element and a heat dissipation member are joined with a highly thermally conductive adhesive (paste) to take measures such as dissipating heat. Also, in die bonding of bare chips, adhesion of LED chips, or adhesion of electrodes and lead wires, a highly thermally conductive conductive paste is used.

[0003] As one of the highly thermally conductive conductive pastes, a paste composition containing copper particles has been proposed. Application of such a paste composition to printed electronics has also been studied. For example, Patent Documents 1 and 2 disclose using copper particles containing an oxide obtained by sintering a copper raw material at a low temperature as a constituent material of a conductive paste. [[ID=-- --]]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] The present disclosure relates to the following. [1] The oxide-containing copper particles have a thickness of 5-50 nm, a major axis of 30-300 nm, and an aspect ratio of 1.5-10.0. The absorption spectrum measured with a spectrophotometer by dispersing copper particles containing an oxide in ethanol having a mass 1×10 6 times is at a wavelength of 62 Oxide-containing copper particles having an absorption peak in the range of 0 to 1000 nm. [Brief explanation of the drawing]

[0006] [Figure 1] This is the absorption spectrum of the oxide-containing copper particles of Example 4. [Figure 2] This is the absorption spectrum of the oxide-containing copper particles of Comparative Example 2. [Figure 3] This is a scanning electron microscope image of the oxide-containing copper particles of Example 4. [Figure 4] This is a scanning electron microscope image of the oxide-containing copper particles of Comparative Example 2. [Modes for carrying out the invention]

[0007] Conductive pastes using oxide-containing copper particles, as described in Patent Documents 1 and 2, have substantially spherical particles. Therefore, when sintered and joined, voids may form in the bonded layer, resulting in low density, difficulty in obtaining sufficient bonding strength, and a risk of low bonding reliability.

[0008] This disclosure provides oxide-containing copper particles that can be used to obtain a paste composition capable of forming a bonding layer with high density, high bonding strength, and high bonding reliability, as well as a paste composition using the same, and semiconductor devices, electrical components, and electronic components.

[0009] The present disclosure will be described in detail below with reference to one embodiment. In this disclosure, oxide-containing copper particles mean particles containing metallic copper and at least one copper oxide. Hereinafter, they are also simply referred to as copper particles.

[0010] In this specification, the notation "XX~YY" means "XX or more and YY or less." Also, in this specification, the lower and upper limits of numerical ranges (for example, ranges of content, etc.) described in stages can be combined independently. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples.

[0011] [Oxide-containing copper particles] The oxide-containing copper particles of this disclosure are composed of 1 × 10⁻¹⁶ oxide-containing copper particles. 6 The absorption spectrum measured by a spectrophotometer after dispersing the substance in twice its mass of ethanol shows an absorption peak in the wavelength range of 600 to 1000 nm. Because the copper particles possess such light absorption properties, a paste composition can be obtained that can form a bonding layer with high density, high bonding strength, and high bonding reliability. The reason why the paste composition of this disclosure can form a bonding layer with high density, high bonding strength, and high bonding reliability, and the correlation between this and the above-mentioned light absorption characteristics are not clear. It is presumed that the main factor for this is the shape of the copper particles, and that the degree of reduction of the copper oxide is also involved.

[0012] The absorption peak may be in the wavelength range of 610 to 900 nm, or in the wavelength range of 620 to 850 nm. Furthermore, copper particles having an absorption peak within that wavelength range tend to exhibit a greenish color, which is the complementary color of the absorption wavelength.

[0013] The absorption spectrum of the copper particles in question may have at least one absorption peak within the wavelength range of 600 to 1000 nm, and may also have two or more absorption peaks. Furthermore, absorption peaks may also be present outside the wavelength range of 600 to 1000 nm.

[0014] In the absorption spectrum of the copper particles, the maximum average absorbance (A2) in a continuous 50-nm interval within the wavelength range of 600 to 1000 nm may be 1.25 times or more the average value (A1) of the absorbance in the wavelength range of 400 to 450 nm. The absorbance ratio (A2 / A1) may be 1.30 to 3.50, or may be 1.50 to 3.00.

[0015] From the viewpoint of sufficiently dispersing the copper particles in the dispersion medium, the absorption spectrum is obtained by dispersing the copper particles in ethanol having a mass 1×10 6 times that of the copper particles to prepare a sample solution, and measuring the absorbance of the sample solution with a spectrophotometer. Specifically, the absorption spectrum can be measured by the method described in the examples.

[0016] The copper particles may be plate-like particles. The thickness of the copper particles may be 5 to 50 nm, may be 8 to 40 nm, or may be 10 to 30 nm. The major axis of the copper particles may be 30 to 300 nm, may be 50 to 200 nm, may be 75 to 150 nm, and the major axis may be larger than the thickness.

[0017] The aspect ratio (major axis / thickness) of the copper particles may be 1.5 to 10.0, may be 2.0 to 9.0, or may be 3.0 to 8.0.

[0018] Since the copper particles are plate-like particles as described above, the contact area between the particles is larger than that of spherical particles. It is presumed that the bonding layer formed from the paste composition using the plate-like particles as described above has a high density, high bonding strength, and high bonding reliability.

[0019] The thickness and major axis of the copper particles are the median values ​​of the measured lengths of at least 200 particles extracted from images taken using a scanning electron microscope (SEM), respectively. The thickness and major axis of the copper particles can be measured by the method described in the examples. The plate-shaped particles have a shape with a pair of substantially parallel planes, the distance between the pair of planes is defined as the "thickness," and the longest diameter on the plane is defined as the "major axis."

[0020] The copper particles are typically sintered by heating them to 100-250°C under an inert gas atmosphere. Examples of inert gases include nitrogen, argon, and helium. Nitrogen may also be used due to its availability and cost. The heating temperature may be 120-230°C or 150-200°C, from the viewpoint of sinterability. Sintering may be carried out under normal pressure or under pressure. The heating time is set appropriately depending on the heating temperature and the form of the sintered body. From the viewpoint of sufficient sintering, it may be, for example, 5 to 180 minutes, 10 to 120 minutes, or 30 to 90 minutes.

[0021] [Method for producing oxide-containing copper particles] The method for producing oxide-containing copper particles described herein is not particularly limited. For example, a method may be used in which a copper compound is reduced using a reducing compound in the presence of a shape stabilizer. The copper compound, the shape stabilizer, and the reducing compound may be mixed in an organic solvent.

[0022] (copper compound) Examples of copper compounds include copper oxide, copper hydroxide, copper nitride, and copper carboxylate. From the viewpoint of obtaining copper particles of this disclosure in high yield, copper oxide may also be used as the copper compound. The copper compound may be used alone or in combination of two or more.

[0023] Examples of copper oxide include copper(I) oxide (cuprous oxide: Cu2O) and copper(II) oxide (CuO). From a productivity standpoint, copper(I) oxide may also be used. Examples of copper hydroxide include copper(II) hydroxide and copper(I) hydroxide. Examples of copper nitride include copper(II) nitride and copper(I) nitride. Examples of copper carboxylates include copper(I) formate, copper(I) acetate, copper(I) propionate, copper(I) butyrate, copper(I) valerate, copper(I) hexanoate, copper(I) octanoate, copper(I) decanoate, etc., as well as copper anhydrides or hydrates such as copper(II) formate, copper(II) acetate, copper(II) propionate, copper(II) butyrate, copper(II) valerate, copper(II) hexanoate, copper(II) octanoate, copper(II) decanoate, and copper(II) citrate. Commercially available copper carboxylates may be used. Copper carboxylates synthesized by known methods may also be used. From the viewpoint of availability and the efficiency of manufacturing the copper particles of this disclosure, copper(II) acetate monohydrate may also be used as the copper carboxylate.

[0024] (Shape stabilizer) The shape stabilizer may be, for example, at least one selected from the group consisting of amine compounds, carboxylic acids, and phosphate esters, or a combination of an amine compound and a carboxylic acid. The shape stabilizer makes it easier to obtain the predetermined light absorption characteristics of this disclosure by coating at least a portion of the oxide-containing copper, which is the copper particle of this disclosure. In addition, the fluidity of the paste composition using the copper particle is improved.

[0025] Examples of amine compounds include monoamines such as dipropylamine, butylamine, dibutylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, 3-aminopropyltriethoxysilane, dodecylamine, oleylamine, monoethanolamine, 2-aminoethoxy-2-ethanol, 3-amino-1-propanol, 3-amino-2-propanol, 4-amino-1-butanol, 3-amino-1-hexanol, 2-(2-aminoethoxy)ethanol; ethylenediamine, N,N-dimethylethylenediamine Examples of diamines include N,N'-dimethylethylenediamine, N,N-diethylethylenediamine, N,N'-diethylethylenediamine, 1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, N,N-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, 1,4-diaminobutane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, N,N'-dimethyl-1,6-diaminohexane, 1,7-diaminoheptane, and 1,8-diaminooctane. The amine compound may be used alone or in combination of two or more. The amine compound may also be an amino alcohol, and the molecular weight of the amino alcohol may be 80 or more, or 150 or less.

[0026] Examples of carboxylic acids include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, octicic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid, and isostearic acid; and dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and diglycolic acid. The carboxylic acid may also be an aromatic carboxylic acid such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, and gallic acid, or a hydroxy acid such as glycolic acid, lactic acid, tartaric acid, malic acid, glyceric acid, hydroxybutyric acid, tartaric acid, citric acid, and isocitric acid. The carboxylic acid may be used alone or in combination of two or more. The carboxylic acid may also be a monocarboxylic acid. The molecular weight of the monocarboxylic acid may be 80 or more, or 150 or less.

[0027] Phosphate esters can remove the oxide film formed on the surface of copper particles by heating in air, thereby improving the sinterability of the copper particles. Furthermore, phosphate esters can improve the lubricity of the copper particles in the paste composition. Phosphate esters may also be added after the reduction reaction. Examples of phosphate esters include alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkylphenyl ether phosphates. The acid value and amine value of the phosphate ester may both be 130 mg KOH / g or less, 120 mg KOH / g or less, or 110 mg KOH / g or less. The ratio of the acid value to the amine value (acid value / amine value) may be 0 to 1.5 or 0 to 1.2. The acid value is determined according to JIS K 0070:1992, and the amine value is determined according to JIS K 7237:1995.

[0028] The total amount of shape stabilizer used may be 0.1 to 10 moles, 0.5 to 8 moles, or 1 to 5 moles per mole of copper compound. When using, for example, an amine compound and a carboxylic acid as shape stabilizers, the molar ratio of the amine compound to the carboxylic acid may be 1 / 5 to 5 / 1, 1 / 3 to 3 / 1, or 1 / 2 to 2 / 1.

[0029] (Reducing compounds) The reducing compound is not particularly limited as long as it has the reducing power to reduce copper compounds and liberate metallic copper. Examples of reducing compounds include hydrazine derivatives. The reducing compound may be used alone or in combination of two or more. Examples of hydrazine derivatives include hydrazine monohydrate, methylhydrazine, ethylhydrazine, n-propylhydrazine, isopropylhydrazine, n-butylhydrazine, isobutylhydrazine, sec-butylhydrazine, tert-butylhydrazine, n-pentylhydrazine, isopentylhydrazine, neopentylhydrazine, tert-pentylhydrazine, n-hexylhydrazine, isohexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n-undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine, phenylhydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol, and acetohydrazine.

[0030] The amount of reducing compound used may be 0.1 to 10 moles, 0.5 to 5 moles, or 0.8 to 3 moles per mole of copper compound.

[0031] (Organic solvents) The organic solvent is not particularly limited, as long as it can carry out a uniform reaction without inhibiting the properties of the complex formed by the mixing of the copper compound, shape stabilizer, and reducing compound. The organic solvent may also be compatible with the reducing compound. Examples of organic solvents include alcohols such as 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, butyl cellosolve, ethyl carbitol, and butyl carbitol; and butyl carbitol acetate, ethyl carbitol acetate, and diethylene glycol diethyl ether. The organic solvent may be used alone or in combination of two or more.

[0032] When using an organic solvent, the amount used should be such that the copper compound, shape stabilizer, and reducing compound are uniformly mixed. The amount of organic solvent used may be, for example, 0.1 to 500 times the volume of the shape stabilizer.

[0033] The reduction reaction of copper compounds may be heated to ensure sufficient reaction progress. The reaction temperature may be -20 to 140°C, 25 to 120°C, or 40 to 100°C. The reaction time may be 20 to 360 minutes, 30 to 300 minutes, or 40 to 240 minutes, from the viewpoint of sufficient reaction progress.

[0034] If the contents of the container in which the reduction reaction was carried out are a liquid (mixture), the solids may be separated by means of centrifugation, for example. The obtained solids may be washed with an organic solvent, or further obtained as a copper particle cake by means of centrifugation. The cleaning process only needs to remove shape stabilizers and reducing compounds, and the cleaning method is not particularly limited. The organic solvent used for cleaning may be an alcohol. Examples of alcohols include ethanol, 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, diethylene glycol, butyl cellosolve, ethyl carbitol, and butyl carbitol. The organic solvent used for cleaning may be used alone or in combination of two or more types.

[0035] [Paste composition] The paste composition of this disclosure comprises the oxide-containing copper particles of this disclosure as described above. The copper particle content in the paste composition may be 10 to 95% by mass, 20 to 90% by mass, or 30 to 85% by mass. In this disclosure, the non-volatile content, which is the component of the paste composition excluding the organic solvent, is considered to be the content of copper particles.

[0036] The paste composition may be diluted with an organic solvent, from the viewpoint of handling and viscosity during use. Examples of suitable organic solvents, from the viewpoint of dispersibility of copper particles and volatility during sintering of the paste composition, include 1-propanol, 2-propanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 3-methyl-1,5-pentanediol, glycerin, polyethylene glycol, etc. The organic solvent may be used alone or in combination of two or more. The organic solvent used for dilution may be the same as the organic solvent used for washing the copper particles.

[0037] The paste composition of this disclosure may, in addition to copper particles, an organic solvent, and components derived from the production of copper particles, optionally contain known additives that are commonly used in conductive pastes. Examples of additives include thermosetting resins, curing accelerators, stress reducers such as rubber and silicone, coupling agents, defoamers, surfactants, colorants such as pigments and dyes, polymerization inhibitors, and antioxidants. Additives may be used individually or in combination of two or more types.

[0038] The paste composition of this disclosure can be prepared by kneading a mixture of copper particles, an organic solvent, and additives used as needed, in a kneading machine such as a disperser, kneader, three-roll mill, or planetary mixer, and then degassing it.

[0039] The cured product of the paste composition of this disclosure contains a sintered body of copper particles of this disclosure, has high thermal conductivity, and high heat dissipation. Therefore, when the paste composition of this disclosure is used as a bonding material for a substrate of an element or heat dissipation member, the thermal conductivity of the device is improved, and the ability of heat to dissipate from inside the device to the outside is improved. Accordingly, by using the paste composition of this disclosure, the operation of various products such as semiconductor devices, electrical components, and electronic components can be stabilized.

[0040] [Semiconductor device] The semiconductor device of this disclosure is joined, at least in part, using the paste composition of this disclosure described above. An example of the semiconductor device is one in which a semiconductor element and a substrate that serves as an element support member are joined using the paste composition. The paste composition may also be used as a die bond.

[0041] By using the paste composition of this disclosure for bonding, a bonding layer with high density and high bonding strength is formed. The bonding layer exhibits a low rate of change in thermal resistance even when subjected to repeated temperature changes, resulting in high bonding reliability and thus providing a semiconductor device with stable operation.

[0042] The semiconductor device may be any known semiconductor device, such as a transistor or diode, as well as a wide-bandgap semiconductor device using SiC, GaN, etc., and a light-emitting element such as an LED. Examples of element support members include copper plates, silver-plated copper plates, pre-plated leadframes (PPF) with Ni / Pd, Ti / Pd / Au, Ni / Pd / Au, etc., glass epoxy plates, and ceramic members.

[0043] The bonding strength of the bonded layer formed using the paste composition may be 20 MPa or more, 30 MPa or more, or 40 MPa or more, depending on the purpose and object of bonding, but from the viewpoint of sufficient bonding strength. The aforementioned bonding strength is die shear strength, which can be measured specifically by the method described in the examples.

[0044] The density of the bonding layer may be 78% or higher, 80% or higher, or 82% or higher, from the viewpoint of bonding strength and bonding reliability. The aforementioned density is the proportion of the sintered body portion in the bonding layer, and can be specifically measured by the method described in the examples.

[0045] [Electrical and electronic components] The electrical or electronic components of this disclosure are joined, at least in part, using the paste composition of this disclosure described above. Examples of electrical or electronic components include those in which a heat-generating member and a heat-dissipating member are joined using the paste composition. The paste composition may also be used as an adhesive for the heat-dissipating member.

[0046] By using the paste composition of this disclosure for bonding, a bonding layer with high density and high bonding strength is formed. The bonding layer exhibits a low rate of change in thermal resistance and high bonding reliability even when subjected to repeated thermal cycle loads, resulting in high heat dissipation and a reduction in the temperature rise of heat-generating members, thus providing an electrical or electronic component with stable operation.

[0047] Examples of heat-generating components include optical pickups and power transistors. The heat-generating component may also be the semiconductor element or a component having the semiconductor element. Examples of heat dissipation components include heat sinks and heat spreaders. The heat-generating component and the heat-dissipating component may be directly bonded together via a paste composition, or they may be indirectly bonded together with another component with high thermal conductivity sandwiched in between. [Examples]

[0048] The present disclosure will now be described in detail by examples, but the present disclosure is not limited in any way by these examples.

[0049] [Manufacturing of oxide-containing copper particles] The compounds used to produce the oxide-containing copper particles in each example and comparative example are as follows. <Copper compounds> • FRC-D70: Cuprous oxide; manufactured by Furukawa Chemicals Co., Ltd.; specific surface area 0.2 m² 2 / g • FRC-D30: Cuprous oxide; manufactured by Furukawa Chemicals Co., Ltd.; specific surface area 0.5 m² 2 / g • FRC-05B: Cuprous oxide; manufactured by Furukawa Chemicals Co., Ltd.; specific surface area 2.3 m² 2 / g <Amine compounds> 4-Amino-1-Butanol; manufactured by Tokyo Chemical Industry Co., Ltd. 2-(2-aminoethoxy)ethanol; manufactured by Tokyo Chemical Industry Co., Ltd. • 6-amino-1-hexanol; manufactured by Tokyo Chemical Industry Co., Ltd. 3-amino-1-propanol; manufactured by Tokyo Chemical Industry Co., Ltd. n-octylamine; manufactured by Tokyo Chemical Industry Co., Ltd. <Carboxylic acid> Hexanoic acid; manufactured by Tokyo Chemical Industry Co., Ltd. • Octanoic acid; manufactured by Tokyo Chemical Industry Co., Ltd. Acetic acid; manufactured by Tokyo Chemical Industry Co., Ltd. Decanoic acid; manufactured by Tokyo Chemical Industry Co., Ltd. <Reducible Compounds> • Hydrazine monohydrate; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. <Organic solvents> • 1-Propanol; manufactured by Tokyo Chemical Industry Co., Ltd. • Ethanol; manufactured by Tokyo Chemical Industry Co., Ltd. • Diethylene glycol; manufactured by Tokyo Chemical Industry Co., Ltd.

[0050] (Example 1) In a 2000 mL round-bottom flask, 10 mmol of cuprous oxide (FRC-D70), 20 mmol of 4-amino-1-butanol, 20 mmol of hexanoic acid, 10 mmol of hydrazine monohydrate, and 400 mL of 1-propanol were placed and heated in an 80°C oil bath while stirring at 250 rpm for 180 minutes. The mixture was then centrifuged (25°C, 10000 rpm, 15 minutes; the same conditions were followed for subsequent steps) and the supernatant was removed. Ethanol was added to the residue and washed by stirring for 10 minutes in a vacuum rotary mixer (25°C, 1000 rpm), then centrifuged and the supernatant was removed. This procedure was repeated four times. Furthermore, ethanol was replaced with diethylene glycol, and the same procedure as above—washing, centrifugation, and removal of supernatant—was repeated twice to obtain a cake of oxide-containing copper particles.

[0051] (Examples 2-4, Comparative Examples 1 and 2) Using the raw material components shown in Table 1, and performing the same procedure as in Example 1, cakes containing each oxide-containing copper particle were obtained.

[0052] [Measurement and evaluation of oxide-containing copper particles] The oxide-containing copper particles (cakes) produced in the examples and comparative examples were subjected to the following measurement evaluations. The evaluation results are shown in Table 1.

[0053] (Absorbance measurement) A cake containing oxide-containing copper particles was taken into a sample bottle, and 1 × 10⁻⁶ of the oxide-containing copper particles were compared to the sample. 6 Twice the mass of ethanol was added. This sample bottle was immersed in an ultrasonic cleaner for 10 minutes to disperse the particles and prepare an ethanol dispersion of oxide-containing copper particles (sample solution). The absorbance of this sample solution at wavelengths of 300 to 1000 nm was measured using a spectrophotometer (UV-Vis-Near Infrared Spectrophotometer "V-570", manufactured by JASCO). For Examples 1-4, there was one absorption peak within the wavelength range of 600-1000 nm. For Comparative Examples 1 and 2, there were no peaks within the wavelength range of 600-1000 nm. Furthermore, the average value of the average absorbance in the wavelength range of 400-450 nm (A1) and the maximum average absorbance in a continuous 50 nm interval within the wavelength range of 600-1000 nm (A2) were determined, and their absorbance ratio (A2 / A1) was calculated. The absorption spectra for Example 4 and Comparative Example 2 are shown in Figures 1 and 2, respectively, as representative examples.

[0054] (Scanning electron microscope (SEM) observation) A sample was prepared by applying a cake of oxide-containing copper particles to a brass sample holder to which carbon tape had been attached, and then drying it at 90°C for 3 hours under a nitrogen atmosphere. This sample was observed using a Schottky field emission scanning electron microscope (SEM "JSM-F100", manufactured by JEOL Ltd.; acceleration voltage 15kV, magnification 100,000x; the same applies hereafter). The length of 200 particles in the SEM image was measured, and the thickness and major axis of each particle were determined. Table 1 shows the median values ​​for thickness and major axis. Furthermore, representative SEM images of Example 4 and Comparative Example 2 are shown in Figures 3 and 4, respectively.

[0055] [Characterization of sintered bodies] The following measurements and evaluations were performed on the sintered bodies of oxide-containing copper particles produced in the examples and comparative examples. These evaluation results are also shown in Table 1.

[0056] (Joining strength) The oxide-containing copper particles (cake) produced in the examples and comparative examples were diluted with diethylene glycol to prepare a paste composition with a non-volatile content of 80% by mass. Using the prepared paste composition, a bonded test specimen (without sealing resin) was prepared by bonding a Ti / Pd / Au plated aluminum nitride piece (3 mm x 3 mm, 200 μm thick) to a Ni / Pd plated copper substrate, and then heating it at 200°C for 60 minutes under a nitrogen atmosphere (containing 3 volume% hydrogen) to sinter the copper particles. The die shear strength (bonding strength) of the bonded test specimens was measured using a bond strength tester ("4000Plus Bond Tester," manufactured by Nordon DAGE; room temperature (25°C), distance from substrate to load fixture 0.15 mm, load speed 30 mm / min).

[0057] (density) After embedding the unsealed specimen in epoxy resin, the sample was cut in the thickness direction and observed using SEM. The area percentage occupied by the sintered body in the binarized image of the cross-section of the bonded layer was determined and defined as the density.

[0058] (Cold cycle test) Using the aforementioned paste composition, a Ti / Au plated silicon chip (3mm x 3mm, 200μm thick) was bonded to a Ni / Pd / Au plated die pad (4mm x 4mm) of a QFP (Quad Flat Package) frame. The mixture was then heated at 200°C for 60 minutes under a nitrogen atmosphere (containing 3% by volume of hydrogen) to sinter the copper particles. This was then mold-sealed with an epoxy resin ("KE-G3000D," manufactured by Kyocera Corporation) to produce a bonded test specimen (test specimen with sealing resin). Cold and hot cycling tests (1 cycle: -40°C to 120°C / 30 minutes, 2000 cycles) were performed on test specimens with and without sealing resin. The rate of change in thermal resistance of the joint before and after the test was measured using a transient thermal resistance measuring device ("Simcenter T3Ster", Siemens). Table 1 shows this rate of change in thermal resistance. A lower rate of change indicates higher joint reliability, while a rate exceeding 10% indicates low joint reliability and is considered a failure.

[0059] [Table 1]

[0060] In the case of oxide-containing copper particles (Examples 1-4) whose absorption spectrum had an absorption peak in the wavelength range of 600-1000 nm, the particle shape was plate-like (see Figure 3), whereas in the case of copper particles that did not have an absorption peak in the aforementioned wavelength range (Comparative Examples 1 and 2), the particle shape was approximately spherical (see Figure 4). The paste compositions of Examples 1 to 4 were found to be able to form a bonding layer with high density, high bonding strength, and high bonding reliability.

Claims

1. The thickness of the oxide-containing copper particles is 5 to 50 nm, The major axis of the oxide-containing copper particles is 30 to 300 nm. The aspect ratio of the oxide-containing copper particles is 1.5 to 10.

0. The oxide-containing copper particles are 1 × 10 ６ Oxide-containing copper particles, dispersed in twice the mass of ethanol and measured with a spectrophotometer, exhibiting an absorption peak in the wavelength range of 620 to 1000 nm.

2. The oxide-containing copper particles according to Claim 1, wherein the aspect ratio is 2.0 to 9.

0.

3. The major axis is 30 to 200 nm, The oxide-containing copper particles according to claim 1, wherein the aspect ratio is 2.0 to 9.

0.

4. The oxide-containing copper particles according to claim 1, wherein the absorption spectrum has a maximum average absorbance in a continuous 50 nm interval within the wavelength range of 600 to 1000 nm that is 1.25 times or more the average value of the average absorbance in the wavelength range of 400 to 450 nm.

5. A paste composition comprising oxide-containing copper particles according to any one of claims 1 to 4.

6. A semiconductor device in which at least a portion is bonded using the paste composition described in claim 5.

7. An electrical component in which at least a portion is joined using the paste composition described in claim 5.

8. An electronic component in which at least a portion is joined using the paste composition described in claim 5.

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