Copper particles, paste-like composition, semiconductor device manufacturing method, and semiconductor device

Abstract

The copper particles of the present disclosure have a rate of change (A) of crystallite diameter found via calculation expression (1) of 100% or greater, and a ratio (B / A) of the rate of change (A) and a rate of change (B) of crystallite diameter found via calculation expression (2) of 0.7 to 2.0.　(1) Rate of change (A) = [(Sinit, 200°C (111) – Sinit, 30°C (111)) / Sinit, 30°C (111)] × 100 (2) Rate of change (B) = [((S6h, 200°C (111) – S6h, 30°C (111)) / S6h, 30°C (111)] × 100

Description

Copper particles, paste composition, method for manufacturing semiconductor device, and semiconductor device

[0001] The present disclosure relates to copper particles, a paste composition, a method for manufacturing a semiconductor device, and a semiconductor device.

[0002] When manufacturing a semiconductor device, various bonding materials are used to bond a semiconductor element to a supporting member such as a lead frame. Known bonding materials include Au-Si eutectic, solder, and paste-like compositions. Among these, paste-like compositions are widely used from the viewpoints of workability and cost.

[0003] In recent years, with the trend toward higher integration and miniaturization of semiconductor devices, there has been a demand for paste compositions as bonding materials that are excellent in electrical conductivity, thermal conductivity, adhesive strength, etc. In response to this demand, for example, a paste composition containing copper particles has been proposed (Patent Document 1, etc.).

[0004] JP 2024-24322 A

[0005] The present disclosure relates to the following. <Copper particles> [1] Copper particles having a rate of change (A) in crystallite diameter calculated by the following calculation formula (1) of 100% or more, and a ratio (B / A) of the rate of change (A) to a rate of change (B) in crystallite diameter calculated by the following calculation formula (2) of 0.7 to 2.0. Rate of change (A) = [(S ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ] × 100... (1) Rate of change (B) = [((S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ]×100...(2) [In calculation formula (1), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. ｉｎｉｔ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. 6ｈ，３０℃（１１１）is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and copper particles. 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C 6 hours after drying the solvent from a copper particle dispersion containing the solvent and copper particles. The crystallite diameter (nm) of Cu(111) is a value calculated from the half-width of a diffraction peak obtained by X-ray diffraction and the Scherrer equation.] [2] The copper particles according to [1] above, which are plate-shaped with a major axis of 250 to 650 nm. [3] The copper particles according to [1] or [2] above, which have an aspect ratio (major axis / thickness) of 5 to 15. [4] The copper particles according to [1] above, which have a BET specific surface area of ​​1.0 to 15.0 m ２ [5] The copper particles according to any one of the above [1] to [4], wherein the rate of change (C) of crystallite diameter calculated by the following calculation formula (3) is 100% or more. Rate of change (C) = [(S 6ｈ，２００℃（２００） -S 6ｈ，３０℃（２００） ) / S 6ｈ，３０℃（２００） ]×100...(3) [In calculation formula (3), S 6ｈ，３０℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and copper particles. 6ｈ，２００℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 200°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. The crystallite diameter (nm) of Cu(200) is a value calculated from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation.

[0006] <Paste-like composition> [6] A paste-like composition containing the copper particles according to any one of [1] to [5] above and a solvent, wherein the content of the copper particles in 100% by mass of the paste-like composition is 50% by mass or more.

[0007] <Semiconductor device> [7] A semiconductor device having a bonding layer formed using the paste composition according to [6] above.

[0008] <Method of manufacturing a semiconductor device> [8] A coating step (A) of coating a substrate with a paste composition containing plate-like copper particles (Cu) and a solvent, and a coating step (B) of drying at least a portion of the coating film coated on the substrate and oxidizing at least a portion of the plate-like copper particles (Cu) to form cuprous oxide (Cu). ２ A drying step (B) to obtain the cuprous oxide (CuO); ２ a mounting step (C) of mounting a semiconductor element on the cuprous oxide-containing coating film containing the cuprous oxide (CuO); ２ a sintering step (D) of heating the cuprous oxide-containing coating film to fix the semiconductor element to the substrate, the sintering step (D) comprising heating the cuprous oxide-containing coating film and sintering the semiconductor element to the substrate, the sintering step (D) comprising heating the cuprous oxide-containing coating film and sintering the semiconductor element to the substrate, the sintered semiconductor element having a cuprous oxide-containing coating film ... ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ] × 100... (1) Rate of change (B) = [((S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ]×100...(2) [In calculation formula (1), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). ｉｎｉｔ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). 6ｈ，３０℃（１１１）is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 200°C 6 hours after drying the solvent from a copper particle dispersion containing a solvent and plate-like copper particles (Cu). The crystallite diameters (nm) are values ​​calculated from the half-width of a diffraction peak obtained by X-ray diffraction and the Scherrer equation.] [9] The method for manufacturing a semiconductor device according to [8], wherein the paste-like composition contains 50% by mass or more of the plate-like copper particles (Cu) in 100% by mass of the paste-like composition.

[10] The Cu in the cuprous oxide-containing coating film ２

[11] The method for manufacturing a semiconductor device according to any one of [8] to

[10] above, wherein the coating film has a thickness of 5 to 1000 μm.

[12] The method for manufacturing a semiconductor device according to any one of [8] to

[11] above, wherein the drying step (B) comprises holding the substrate, onto which the paste composition has been applied, at 50 to 150°C for 1 to 60 minutes.

[13] The method for manufacturing a semiconductor device according to any one of [8] to

[12] above, wherein the sintering step (D) comprises heating and pressurizing the cuprous oxide-containing coating film, on which the semiconductor element has been mounted, at 180 to 350°C and 1 to 40 MPa to fix the semiconductor element to the substrate.

[0009] Copper particles are easily oxidized, and paste-like compositions containing oxidized copper particles exhibit reduced sinterability. Therefore, in semiconductor device manufacturing processes, when the bonding material is exposed to an atmospheric environment, the copper particles oxidize, resulting in reduced sinterability and reduced bonding strength. Specifically, for example, a mounting process for bonding a semiconductor element to a support member generally comprises a coating process in which a paste-like composition is applied or printed onto the support member, a drying process in which the solvent is removed from the paste-like composition, a mounting process in which the semiconductor element is mounted on the support member, and a bonding process in which the paste-like composition is sintered by heating or other methods to bond the semiconductor element to the support member. Waiting times are generated between each process. During the waiting time between the drying and mounting processes, the dried surface of the paste-like composition is open, which makes oxidation of the copper particles more likely to progress. This leads to a problem of reduced sinterability due to the oxidation of the copper particles. Furthermore, even when the waiting times between the processes are short, oxidation of the copper particles is likely to progress if the drying process is performed in an atmospheric environment.

[0010] The present inventors have found that with certain copper particles, oxidation of the copper particles is unlikely to proceed (i.e., oxidation resistance is good) and deterioration of sinterability is unlikely to occur even in an environment exposed to the atmosphere, such as when a waiting time occurs or when a drying process is performed in the atmosphere. They have also found that a paste-like composition using copper particles with good oxidation resistance can form a bonding layer with high bonding strength even in an environment exposed to the atmosphere, such as when a waiting time occurs or when a drying process is performed in the atmosphere.

[0011] The present disclosure will be described in detail below with reference to one embodiment. In this specification, the expression "XX to YY" means "XX or more and YY or less." In addition, in this specification, for a numerical range (for example, a range of content, etc.), lower and upper limits described in stages can be independently combined. In addition, in a numerical range described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example. In this specification, "solid content" means components excluding solvent.

[0012] [Copper Particles] The copper particles of the present disclosure have a crystallite diameter change rate (A) calculated by the following calculation formula (1) of 100% or more, and the ratio (B / A) of the change rate (A) to the crystallite diameter change rate (B) calculated by the following calculation formula (2) is 0.7 to 2.0. Change rate (A) = [(S ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ] × 100... (1) Rate of change (B) = [((S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ] × 100 (2) In the calculation formula (1), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. ｉｎｉｔ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. 6ｈ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and copper particles. 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles.

[0013] The copper particles of the present disclosure may exist alone or together with other components. For example, the copper particles of the present disclosure may be stored in an inert gas or in a solvent. In a copper particle dispersion in which the copper particles of the present disclosure are dispersed in a solvent, the copper particles present in the dispersion are the copper particles of the present disclosure. Furthermore, when the copper particles of the present disclosure are present in a wet cake-like composition, the copper particles present in the composition are the copper particles of the present disclosure. That is, even when copper particles are present together with a solvent, as in the copper particle dispersion and the wet cake-like composition, the copper particles can be considered to be the copper particles of the present disclosure by focusing only on the copper particles. That is, all copper particles used in a copper particle dispersion containing a solvent and copper particles, in which the rate of change (A) of crystallite diameter calculated by the calculation formula (A) is 100% or more, and the ratio (B / A) of the rate of change (A) to the rate of change (B) of crystallite diameter calculated by the calculation formula (B) is 0.7 to 2.0, can be considered to be copper particles of the present disclosure.

[0014] The copper particle dispersion may be a wet cake-like composition obtained during the copper particle production process, or may be a paste-like composition obtained by diluting the wet cake-like composition with a solvent.

[0015] Here, the copper particle dispersion liquid is a copper particle dispersion liquid containing copper particles and a solvent, in which the rate of change (A') of crystallite diameter calculated by the following calculation formula (1') is 100% or more, and the ratio (B' / A') of the rate of change (A') to the rate of change (B') of crystallite diameter calculated by the following calculation formula (2') is 0.7 to 2.0. Rate of change (A') = (S ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ...(1') Rate of change (B') = (S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ... (2') In the calculation formula (1'), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. ｉｎｉｔ，２００℃（１１１）is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. 6ｈ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and copper particles. 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200° C. 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. The crystallite diameter (nm) of Cu(111) is a value calculated from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation.

[0016] In the copper particles of the present disclosure, the rate of change (C) of crystallite diameter calculated by the following calculation formula (3) may be 100% or more. Rate of change (C) = [(S 6ｈ，２００℃（２００） -S 6ｈ，３０℃（２００） ) / S 6ｈ，３０℃（２００） ] × 100 (3) In the calculation formula (3), S 6ｈ，３０℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and copper particles. 6ｈ，２００℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 200°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles.

[0017] The S ｉｎｉｔ，X℃（１１１） (X = 30, 200) can be measured as follows. That is, copper particles immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles are heated from 25°C to X°C at a heating rate of 10°C / min under a nitrogen gas atmosphere at atmospheric pressure, and XRD measurement is performed at X°C. The crystallite diameter S of Cu(111) is calculated using a split pseudo-Voigt function as the fitting function, FWHM as the width, and a Scherrer constant of 0.94. Ｘ Specifically, it can be calculated by the method described in the Examples.

[0018] The S 6ｈ，X℃（１１１） (X=30, 200) is the same as the above S except that the copper particles to be measured are obtained 6 hours after drying the solvent from a copper particle dispersion containing the solvent and copper particles. ｉｎｉｔ，X℃（１１１） It can be measured in the same way as

[0019] The S 6ｈ，X℃（２００） (X=30, 200) is the same as the above except that the half width of the Cu(200) peak is used. 6ｈ，X℃（１１１） It can be measured in the same way as

[0020] In order to improve oxidation resistance, the copper particles of the present disclosure may be in a state where a solvent is present around the copper particles during the process up to sintering. Even when the copper particles are exposed to the atmosphere, copper particles having the rate of change (A) of 100% or more and the ratio (B / A) of 0.7 to 2.0 are less likely to undergo oxidation and less likely to experience a decrease in sinterability. Thus, when a paste composition containing the copper particles is used as a bonding material, even in environments exposed to the atmosphere, such as when a waiting period occurs during the bonding process of components or when the drying process is performed in the atmosphere, a bonded body with high bonding strength can be obtained that is less susceptible to such effects. Furthermore, copper particles having the rate of change (A) of 100% or more and the ratio (B / A) of 0.7 to 2.0 are less likely to undergo oxidation and are less likely to experience a decrease in sinterability, so that when a bonded body using a paste composition containing the copper particles as a bonding material is subjected to a thermal cycle test in which cooling and heating are repeated, the bonded body is less likely to peel or crack, and the rate of change in thermal resistance is small. The ratio (B / A) may be 0.75 to 1.5, or 0.8 to 1.0.

[0021] The copper particles of the present disclosure may be plate-shaped. The copper particles have a larger contact area between particles than spherical particles because they are plate-shaped particles. It is presumed that a bonding layer formed from a paste composition using such plate-shaped particles will have a high density and tend to have a high bonding strength.

[0022] The copper particles may have a major axis of 250 to 650 nm, 300 to 600 nm, 350 to 550 nm, or 400 to 500 nm. The copper particles may have a thickness of 30 to 60 nm, 40 to 50 nm, or 40 to 50 nm, and the major axis may be greater than the thickness.

[0023] The aspect ratio (major axis / thickness) of the copper particles may be 5.0 to 15.0, 7.5 to 14.0, 8.0 to 14.0, 9.0 to 14.0, or 10.0 to 14.0. When the major axis of the copper particles is 250 to 650 nm, the aspect ratio (major axis / thickness) may be 1.5 to 15.0, 5.0 to 15.0, 7.5 to 14.0, 8.0 to 14.0, 9.0 to 14.0, or 10.0 to 14.0. Copper particles having major axes and aspect ratios within the above ranges tend to have better oxidation resistance. The reason for this is presumed to be as follows. Copper particles having major axes and aspect ratios within the above ranges have a large aspect ratio and therefore have a smaller amount of oxide on their surfaces than copper particles having a small aspect ratio. Furthermore, since copper particles having a major axis and aspect ratio within the above ranges have a larger number of contact points per unit weight than copper particles having a shorter major axis, it is believed that this balance reduces oxides on the particle surfaces, and the reduced metal surfaces sinter rapidly and sufficiently at low temperatures in many locations, resulting in improved oxidation resistance.

[0024] The thickness and major axis of the copper particles are each the median of the measured length values ​​of at least 200 particles extracted from images taken by scanning electron microscope (SEM) observation. Specifically, the thickness and major axis of the copper particles can be measured by the method described in the Examples. The plate-like particles have a shape having a pair of approximately parallel flat surfaces, and the distance between the pair of flat surfaces is defined as the "thickness" and the longest diameter on the flat surfaces is defined as the "major axis."

[0025] The copper particles of the present disclosure have a BET specific surface area of ​​3.0 to 13.0 m２ The copper particles may have a specific surface area of ​​3.0 m / g. ２ / g or more, the sinterability of the copper particles can be ensured, and the specific surface area is 13.0 m ２ When the specific surface area of ​​the copper particles is 5.0 to 13.0 m / g or less, oxidation of the particle surface is unlikely to proceed. ２ / g, and 6.0 to 13.0 m ２ / g, and 7.0 to 13.0 m ２ / g, and 8.0 to 13.0 m ２ / g, and 9.0 to 13.0 m ２ The BET specific surface area may be determined by the nitrogen (N ２ ) onto solid particles, and the surface area is measured from the amount of adsorption. Specifically, the specific surface area is determined by measuring the monomolecular adsorption amount V M using the Brunauer, Emmet and Teller's equation (BET equation) from the relationship between pressure P and adsorption amount V. Measurements can be performed using a fully automatic specific surface area measurement device (for example, a fully automatic specific surface area measurement device, Macsorb, manufactured by Mountec Co., Ltd.).

[0026] [Method for Producing Copper Particles] The method for producing copper particles of the present disclosure is not particularly limited. For example, a method of reducing a copper compound using a reducing compound may be used. The reduction may be carried out in the presence of a shape stabilizer. The reduction may be carried out by dropping a diluted reducing compound into a mixed solution of a copper compound, a shape stabilizer, and an organic solvent.

[0027] The method for producing copper particles of the present disclosure is directed to the production of copper oxide (copper oxide (II): CuO) and cuprous oxide (copper oxide (I): Cu ２The method for producing copper particles may also be a method for producing copper particles in which copper oxide (copper oxide: CuO) and cuprous oxide (copper oxide: CuO) are reduced using a reducing compound. According to the method for producing copper particles, copper atoms derived from copper oxide serve as crystal nuclei, and copper atoms derived from cuprous oxide are added to the nuclei to grow crystals, which tends to easily produce copper particles with a large diameter and a large aspect ratio, and the ratio of the aforementioned rate of change (B / A) is 0.7 to 2.0. Furthermore, the method for producing copper particles of the present disclosure is also advantageous in that copper oxide (copper oxide (II): CuO) and cuprous oxide (copper oxide (I): Cu ２ O) may be reduced using a reducing compound in the presence of an organic solvent.

[0028] (Copper Compound) Examples of copper compounds include copper oxides, copper hydroxides, copper nitrides, and copper carboxylates. From the viewpoint of obtaining the copper particles of the present disclosure in high yield, the copper compound may be copper oxides. The copper compound may be used alone or in combination of two or more.

[0029] Copper oxides include copper oxide (I) (cuprous oxide: Cu ２ 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, and copper(I) decanoate, as well as copper carboxylate 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, and copper(II) citrate. Commercially available copper carboxylates may be used. Copper carboxylates synthesized by known methods may also be used. The copper carboxylate may be copper (II) acetate monohydrate from the viewpoints of availability and production efficiency of the copper particles of the present disclosure.

[0030] (Reducing Compound) The reducing compound is not particularly limited as long as it has the reducing power to reduce the copper compound and liberate metallic copper. The reducing compound may be used alone or in combination of two or more. Examples of the reducing compound include hydrazine and hydrazine derivatives. Examples of the hydrazine derivatives include hydrazine derivatives modified with an organic chain, such as methyl hydrazine, ethyl hydrazine, n-propyl hydrazine, isopropyl hydrazine, n-butyl hydrazine, isobutyl hydrazine, sec-butyl hydrazine, tert-butyl hydrazine, n-pentyl hydrazine, isopentyl hydrazine, neopentyl hydrazine, tert-pentyl hydrazine, n-hexyl hydrazine, isohexyl hydrazine, n-heptyl hydrazine, n-octyl hydrazine, n-nonyl hydrazine, n-decyl hydrazine, n-undecyl hydrazine, n-dodecyl hydrazine, cyclohexyl hydrazine, phenyl hydrazine, 4-methylphenyl hydrazine, benzyl hydrazine, 2-phenylethyl hydrazine, 2-hydrazinoethanol, and acetohydrazine. The hydrazine derivative may be modified with an organic chain such as an amine, acid, or alcohol, or may be 2-hydrazinoethanol. By using a hydrazine derivative modified with an organic chain, excessive reduction can be prevented, and oriented growth into a plate shape is promoted.

[0031] The amount of the reducing compound used may be 0.1 to 10 mol, 0.5 to 5 mol, or 0.8 to 3 mol per mol of the copper compound.

[0032] The reduction may be carried out by dropping the reducing compound in the amount used as a diluted solution diluted with an organic solvent into a mixed solution of a copper compound, a shape stabilizer, and an organic solvent. The diluted solution may be a diluted solution with an organic solvent as described below, and the dilution concentration may be 1 to 50% by mass, 5 to 20% by mass, or 8 to 12% by mass. By dropping the reducing compound as the diluted solution into the mixed solution to carry out the reduction, excessive reduction is less likely to occur and oriented growth into a plate shape is promoted. The drop time of the diluted solution may be 30 to 180 minutes, 30 to 150 minutes, 40 to 120 minutes, or 50 to 90 minutes.

[0033] In order to promote oriented growth into a plate shape, the hydrazine derivative modified with an organic chain may be added dropwise as the diluted solution to the mixed solution to carry out reduction.

[0034] (Organic Solvent) The organic solvent is not particularly limited as long as it is capable of carrying out a uniform reaction without inhibiting the properties of the complex formed by mixing the copper compound, shape stabilizer, and reducing compound. The organic solvent may be compatible with the reducing compound. Examples of the organic solvent 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; butyl carbitol acetate, ethyl carbitol acetate, and diethylene glycol diethyl ether. One type of organic solvent may be used alone, or two or more types may be used in combination.

[0035] When an organic solvent is used, the amount used may be such that the copper compound, the shape stabilizer, and the reducing compound can be uniformly mixed. The amount of the organic solvent used may be, for example, 0.1 to 500 times by volume the volume of the shape stabilizer.

[0036] (Shape Stabilizer) The shape stabilizer may be, for example, at least one selected from the group consisting of an amine compound such as 3-amino-1-propanol, a carboxylic acid such as heptanoic acid, and a phosphate ester, or a combination of an amine compound and a carboxylic acid. By coating at least a portion of the copper particles of the present disclosure with a shape stabilizer, oxidation of the particle surface is less likely to proceed and aggregation between particles is less likely to occur. In addition, the fluidity of a paste composition using the copper particles is improved.

[0037] The reduction reaction of the copper compound may be heated from the viewpoint of 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.

[0038] When the content of the vessel in which the reduction reaction was carried out is a liquid (liquid mixture), the solid matter may be separated, for example, by centrifugation or the like. The obtained solid matter may be washed with an organic solvent, and further, by centrifugation or the like, the solid matter may be obtained as a cake of copper particles. The washing method is not particularly limited as long as the shape stabilizer, reducing compound, etc. are sufficiently removed. The organic solvent for washing may be alcohol. Examples of alcohol 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, butyl carbitol, etc. The organic solvent for washing may be used alone, or two or more types may be used in combination.

[0039] [Paste-like composition] The paste-like composition of the present disclosure is a paste-like composition containing the copper particles of the present disclosure and an organic solvent.

[0040] (Copper Particles) The copper particles are as described above. From the viewpoint of obtaining a paste composition with good bonding properties, the content of the copper particles in 100% by mass of the paste composition may be 50 to 90% by mass or 60 to 80% by mass.

[0041] (Organic Solvent) The paste-like composition may be diluted with an organic solvent from the viewpoints of handleability during use, viscosity, and the like. Examples of organic solvents 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, and polyethylene glycol from the viewpoints of dispersibility of copper particles and volatility during sintering of the paste-like composition. The organic solvent may be used alone, or two or more types may be used in combination. The organic solvent for dilution may be the same as the organic solvent for washing the copper particles.

[0042] (Additives) In addition to the copper particles, organic solvent, and components derived from the production of the copper particles, the paste composition of the present disclosure may also contain, as necessary, known additives that are commonly used in conductive pastes. Examples of additives include thermoplastic resins, thermosetting resins, curing accelerators, stress-reducing agents such as rubber and silicone, coupling agents, antifoaming agents, surfactants, colorants such as pigments and dyes, polymerization inhibitors, antioxidants, etc. The additives may be used alone or in combination of two or more.

[0043] (Reducing Compound) The paste-like composition of the present disclosure may contain the above-described reducing compound as appropriate.

[0044] (Preparation of Paste Composition) The paste composition of the present disclosure can be prepared by kneading a mixture of copper particles, an organic solvent, and additives used as needed using a kneading machine such as a disperse, kneader, three-roll mill, or planetary mixer, followed by degassing.

[0045] A bonded body using the paste-like composition of the present disclosure as a bonding material includes a sintered body of copper particles of the present disclosure and has high thermal conductivity and excellent heat dissipation. Therefore, when the paste-like composition of the present disclosure is used as a bonding material for substrates of elements or heat dissipation components, the thermal conductivity of the device is improved and the ability to dissipate heat from within the device to the outside is improved. Therefore, the use of the paste-like composition of the present disclosure can stabilize the operation of various products such as semiconductor devices, electrical components, and electronic components.

[0046] The paste-like composition is usually sintered by heating to 100 to 250°C in an inert gas atmosphere. Examples of inert gases include nitrogen, argon, and helium. Nitrogen is preferred from the viewpoints of availability and cost. The heating temperature may be 120 to 230°C or 150 to 200°C from the viewpoint of good sinterability. Sintering may be performed under normal pressure or under pressure. The heating time is set appropriately depending on the heating temperature, the shape of the sintered body, and the like. From the viewpoint of sufficient sintering progress, the heating time may be, for example, 5 to 180 minutes, 10 to 120 minutes, or 30 to 90 minutes.

[0047] [Semiconductor Device] The semiconductor device of the present disclosure has a bonding layer formed using the paste composition of the present disclosure. Examples of semiconductor devices include those in which a semiconductor element and a substrate serving as an element support member are bonded using the paste composition. The paste composition may be used as a die bond. By using the paste composition of the present disclosure for bonding, a bonding layer with high density and high bonding strength is formed. The bonding layer has a low rate of change in thermal resistance and high bonding reliability even when subjected to repeated temperature changes, resulting in a semiconductor device with stable operation.

[0048] The semiconductor element may be a known semiconductor element, for example, a transistor, a diode, etc., or a wide band gap semiconductor element using SiC, GaN, etc., or a light emitting element such as an LED. Examples of the element support member include a copper plate, a silver-plated copper plate, a lead frame (PPF; Pre Plated Leadframe) plated with Ni / Pd, Ti / Pd / Au, Ni / Pd / Au, etc., a glass epoxy plate, a ceramic member, etc.

[0049] The bonding strength of the bonding layer formed using the paste composition for bonding varies depending on the purpose and object of bonding, but from the viewpoint of sufficient bonding strength, it may be 100 MPa or more, 105 MPa or more, or 110 MPa or more. The bonding strength is a die shear strength, and specifically, it can be measured by the method described in the examples.

[0050] [Method for manufacturing semiconductor device] In one embodiment, a method for manufacturing a semiconductor device may include the steps of applying the paste composition of the present disclosure to a substrate to form a coating film, drying the solvent in the coating film, and, after drying the solvent, mounting a member to be bonded to the substrate on the coating film that has been left to stand in an air atmosphere at room temperature (15 to 35°C) for 10 minutes or more to form a laminate, and heating the laminate to bond the substrate and the member to be bonded via a bonding layer formed by sintering the coating film.

[0051] As described above, the copper particles of the present disclosure have good oxidation resistance and are less likely to decrease in sinterability. Therefore, by using a resin paste composition containing the copper particles as a bonding material, even if the coating film is left in an air atmosphere at room temperature (15 to 35°C) for 10 minutes or more after drying, the bonding strength is less likely to decrease, and a semiconductor device having a bonding layer with high bonding strength can be obtained.

[0052] [Method for manufacturing a semiconductor device] In another embodiment, a method for manufacturing a semiconductor device includes a coating step (A) of coating a substrate with a paste composition containing plate-like copper particles (Cu) and a solvent, and a coating step (B) of drying at least a portion of the coating film coated on the substrate and oxidizing at least a portion of the plate-like copper particles (Cu) to form cuprous oxide (Cu).２ A drying step (B) to obtain the cuprous oxide (Cu ２ a mounting step (C) of mounting the semiconductor element on the cuprous oxide-containing coating film containing the cuprous oxide (CuO); ２ and a sintering step (D) of heating the cuprous oxide-containing coating film, the cuprous oxide-containing coating film having a copper oxide content of 20 mass % or less relative to 100 mass % of the plate-like copper particles (Cu) in the cuprous oxide-containing coating film, to fix the semiconductor element to the substrate.

[0053] (Step A) The paste composition applied to a substrate in the application step (A) may be the paste composition of the present disclosure. The thickness of the coating film applied to the substrate may be 5 to 1000 μm, 40 to 750 μm, or 80 to 500 μm.

[0054] (Step B) The drying step (B) may include holding the substrate coated with the paste composition at 50 to 150°C for 1 to 60 minutes to dry at least a portion of the coating film. The holding temperature may be 60 to 130°C, or 70 to 110°C. The holding time may be 5 to 45 minutes, or 10 to 30 minutes. The drying step (B) may be performed while gradually increasing the temperature, and the temperature may be gradually increased from room temperature to any desired temperature.

[0055] The atmosphere during drying can be appropriately selected depending on the application from among oxygen-containing atmospheres such as air atmospheres, inert gas atmospheres such as nitrogen and argon, and reduced pressure atmospheres.

[0056] (Step C) The Cu in the cuprous oxide-containing coating film on which the semiconductor element is mounted is ２ The crystallite size of O(111) may be 10 nm or less, 5 nm or less, or 1 nm or less.

[0057] The cuprous oxide-containing coating film is formed by oxidizing the surface layer of the coating film formed on the substrate in the coating step (A), and contains cuprous oxide (Cu ２ O) is unevenly distributed near the surface layer of the cuprous oxide-containing coating film.

[0058] (Step D) The sintering step (D) may include heating and pressurizing the cuprous oxide-containing coating film on which the semiconductor element is mounted at 180 to 350°C and 1 to 40 MPa to fix the semiconductor element to the substrate. The heating conditions may be 200 to 300°C or 225 to 275°C. The pressure conditions may be 10 to 35 MPa or 15 to 30 MPa. The sintering step (D) may be performed while increasing the temperature in a stepwise manner, or while increasing the pressure in a stepwise manner. The temperature and pressure may be increased simultaneously, or the pressure may be increased after the temperature increase is complete, or the temperature may be increased after the pressure increase is complete.

[0059] The atmosphere during sintering can be appropriately selected depending on the application from among oxygen-containing atmospheres such as air atmospheres, inert gas atmospheres such as nitrogen and argon, and reduced pressure atmospheres.

[0060] The cuprous oxide (Cu) in the cuprous oxide-containing coating film ２ The O) content may be 0.01 to 40% by mass, 0.05 to 35% by mass, or 0.1 to 30% by mass.

[0061] The cuprous oxide (Cu) ２ When the content of copper oxide (Cu) in the coating film is more than 20% by mass relative to 100% by mass of the plate-like copper particles (Cu) in the coating film containing cuprous oxide, for example, reductive sintering is performed under conditions in which 3% hydrogen is introduced before the sintering to reduce the cuprous oxide, thereby obtaining the cuprous oxide (Cu ２ The copper oxide content may be 20% by mass or less relative to 100% by mass of the plate-like copper particles (Cu) in the cuprous oxide-containing coating film. By the reductive sintering, the cuprous oxide is reduced to metallic copper, and the copper particles are bonded to each other by necking, thereby obtaining good electrical conductivity.

[0062] The cuprous oxide (Cu) ２ The copper oxide content is 20% by mass or less relative to 100% by mass of the plate-like copper particles (Cu) in the cuprous oxide-containing coating film, and ２ When the crystallite diameter of O(111) is 10 nm or less, good bonding strength can be obtained, and a highly reliable semiconductor device can be obtained.

[0063] Next, the present disclosure will be specifically described using examples, but the present disclosure is not limited to these examples in any way.

[0064] [Production of Copper Particles] The compounds used in the production of copper particles in each of the Examples and Comparative Examples are as follows: <Copper Compound> FCO-M6B: Copper oxide; manufactured by Furukawa Chemicals Corporation; specific surface area: 26 m ２ / g, D50: 0.9 μm FRC-10A: Cuprous oxide; manufactured by Furukawa Chemicals Corporation; specific surface area: 0.9 m ２ / g, D50: 2.0 μm <Amine compound> 3-amino-1-propanol; manufactured by Tokyo Chemical Industry Co., Ltd. <Carboxylic acid> Heptanoic acid; manufactured by Tokyo Chemical Industry Co., Ltd. <Reducing compound> 2-hydrazinoethanol; manufactured by Tokyo Chemical Industry Co., Ltd. <Organic solvent> 1-propanol; manufactured by Tokyo Chemical Industry Co., Ltd. Diethylene glycol; manufactured by Tokyo Chemical Industry Co., Ltd.

[0065] Example 1: A 2000 mL round-bottom flask was charged with 1 mmol of copper oxide (FCO-M6B), 9 mmol of cuprous oxide (FRC-10A), 20 mmol of 3-amino-1-propanol, 20 mmol of heptanoic acid, and 30 mmol of 1-propanol, and heated in an 80°C oil bath while stirring at 250 rpm. 10 mmol of 2-hydrazinoethanol was diluted in 1-propanol to prepare a 10% by mass diluted solution. This diluted solution was added dropwise to the flask over 30 minutes, and mixed for 120 minutes after the completion of the addition. The resulting mixture was centrifuged (25°C, 10,000 rpm, 15 minutes; the same conditions apply hereinafter), and the supernatant was removed. Ethanol was added to the residue, and the mixture was washed by stirring for 10 minutes in a vacuum planetary centrifugal mixer (25°C, 1,000 rpm). The supernatant was then removed, and this procedure was repeated four times. Furthermore, the ethanol was changed to diethylene glycol, and the same procedures of washing, centrifugation and removal of the supernatant were repeated twice to obtain a cake of copper particles.

[0066] Examples 2 and 3 and Comparative Examples 1 to 3 Using the raw material components shown in Table 1, the same operation as in Example 1 was carried out to obtain each copper particle cake.

[0067] [Measurement and Evaluation of Copper Particles] The copper particles (cakes) obtained in each Example and Comparative Example were subjected to the following measurement and evaluation. The evaluation results are shown in Table 1.

[0068] (X-ray Diffraction (XRD) Measurement) The copper cake obtained in each Example and Comparative Example was applied to a glass plate to a thickness of 200 μm, and an X-ray diffractometer (product name: SmartLab SE, manufactured by Rigaku Corporation) was used. Using a CuKα ray source, the crystallite size was calculated from the Miller index (111) and (220) plane peaks using the Scherrer equation by a focusing method. The fitting function used was a split pseudo-Voigt function, the width was FWHM, and the Scherrer constant was 0.94. A corrosion-resistant infrared heating sample high-temperature device for the X-ray diffractometer, Reactor X (manufactured by Rigaku Corporation), was used.

[0069] S ｉｎｉｔ，X℃（１１１） (X = 30, 200) was measured as follows. Copper particles (cakes) produced in the Examples and Comparative Examples were heated from 25°C to X°C at a heating rate of 10°C / min under a nitrogen gas atmosphere at atmospheric pressure immediately after the solvent was dried at 90°C for 20 minutes (within 10 minutes of drying the solvent), and XRD measurement was performed at X°C. At each measurement temperature X, the time required for one XRD measurement was 15 seconds, and the temperature of the measurement atmosphere was maintained without heating during the XRD measurement.

[0070] S 6ｈ，X℃（１１１） (X=30, 200) and S 6ｈ，X℃（２００） (X = 30, 200) was measured as follows. Copper particles (cakes) produced in the Examples and Comparative Examples were dried to remove the solvent, and six hours later, the copper particles were heated from 25°C to X°C at a heating rate of 10°C / min under a nitrogen gas atmosphere at atmospheric pressure, and XRD measurement was performed at X°C. At each measurement temperature X, the time required for one XRD measurement was 15 seconds, and the temperature of the measurement atmosphere was maintained without heating during the XRD measurement.

[0071] (Scanning Electron Microscope (SEM) Observation) A cake of copper particles was applied to a brass sample stage with carbon tape attached, and dried at 90°C for 3 hours in a nitrogen atmosphere to prepare a sample. This sample was observed with an SEM (Schottky field emission scanning electron microscope "JSM-F100", manufactured by JEOL Ltd.; acceleration voltage 15 kV, magnification 100,000 times; the same applies hereinafter). The lengths of 200 particles in the SEM image were measured to determine the thickness and major axis of the particles. In Table 1, the thickness and major axis indicate the respective median values. The aspect ratio was calculated using the above median values.

[0072] (BET Specific Surface Area) The BET specific surface area was measured by the BET method using nitrogen gas as the adsorption gas and an automatic specific surface area measuring device (Macsorb Hmmodel-1220 automatic specific surface area measuring device, manufactured by Mountec Co., Ltd.).

[0073]

[0074] (Examples 4 to 6 and Comparative Examples 4 to 6) The copper particles (cakes) produced in Examples 1 to 3 and Comparative Examples 1 to 3 were diluted with diethylene glycol in the proportions shown in Table 2 to prepare paste compositions with a solid content of 78 mass%.

[0075] The following measurements and evaluations were carried out on each of the paste compositions prepared in Examples 4 to 6 and Comparative Examples 4 to 6. The evaluation results are shown in Table 2.

[0076] (Bonding strength) Using the prepared paste composition, a Ti / Pd / Au-plated aluminum nitride piece (3 mm x 3 mm, thickness 200 μm) was bonded to a Ni / Pd-plated copper substrate, and heated at 200 ° C. for 60 minutes in a nitrogen atmosphere (containing 3% by volume of hydrogen) to sinter the copper particles. A bonded test piece (a test piece without a sealing resin, for measuring "initial bonding strength" in Table 2) was prepared. In addition, a bonded test piece (a test piece without a sealing resin, for measuring "bonding strength after 6 h" in Table 2) was prepared in the same manner as above, except that an aluminum nitride piece (3 mm x 3 mm, thickness 200 μm) was bonded to a Ni / Pd-plated copper substrate 6 hours after application of the prepared paste composition. The die shear strength (bond strength) of the bonded test pieces was measured using a bond strength tester ("4000Plus Bond Tester", manufactured by Nordon DAGE; room temperature (25°C), distance from substrate to loading jig: 0.15 mm, loading speed: 30 mm / min).

[0077] (Cold-Heat Cycle Test) Using the paste composition, a Ti / Au-plated silicon chip (3 mm x 3 mm, 200 μm thick) was bonded to a Ni / Pd / Au-plated die pad (4 mm x 4 mm) of a QFP (Quad Flat Package) frame. The resulting mixture was heated at 200°C for 60 minutes in a nitrogen atmosphere (containing 3% by volume of hydrogen) to sinter the copper particles. This was then mold-sealed with an encapsulating epoxy resin ("KE-G3000D" manufactured by Kyocera Corporation) to prepare a bonded test specimen (a test specimen with encapsulating resin). A cold-heat cycle test (1 cycle: -40°C to 120°C / 30 minutes, 2000 cycles) was performed on the test specimens without encapsulating resin and with encapsulating resin. The rate of change in the thermal resistance of the bonding layer before and after the test was measured using a transient thermal resistance measurement device ("Simcenter T3Ster" manufactured by Siemens). The rate of change of this thermal resistance is shown in Table 1. The lower the rate of change, the higher the bonding reliability.

[0078]

[0079] The bonding layers formed using the paste compositions of Examples 4 to 6 containing the copper particles of Examples 1 to 3 were found to have high initial bonding strength and excellent sinterability. Furthermore, the bonding layers maintained high bonding strength even after 6 hours had elapsed, and even when standby time occurred, the sinterability was unlikely to decrease, i.e., they had good oxidation resistance. Furthermore, the bonding layers exhibited a small rate of change in thermal resistance during thermal cycle testing, demonstrating high bonding reliability. On the other hand, the bonding layers formed using the paste compositions of Comparative Examples 4 to 6, which did not contain the copper particles of Examples 1 to 3, were found to have low bonding strength and poor sinterability. Furthermore, the bonding layers exhibited a large rate of change in thermal resistance during thermal cycle testing, demonstrating low bonding reliability.

[0080] Example 7 The paste composition prepared in Example 4 was applied to a Ni / Pd-plated copper substrate and then dried at 90°C for 20 minutes to obtain a copper substrate having a cuprous oxide-containing coating film (application step (A) and drying step (B)). A Ti / Pd / Au-plated aluminum nitride piece (3 mm x 3 mm, 200 μm thick) was adhered to the copper substrate having the cuprous oxide-containing coating film, and the resulting mixture was heated and pressurized at 250°C and 20 MPa for 3 minutes in a nitrogen atmosphere to produce a bonded body in which the copper particles were sintered (mounting step (C) and sintering step (D)).

[0081] (Examples 8 to 9, Comparative Examples 7 to 9) Each bonded body was produced in the same manner as in Example 7, except that the paste-like compositions prepared in Examples 5 to 6 and Comparative Examples 4 to 6 were used instead of the paste-like composition prepared in Example 4.

[0082] Example 10 A joined body was produced in the same manner as in Example 7, except that the copper particles (cake) produced in Example 1 were diluted with diethylene glycol in the proportions shown in Table 3, and 2-hydrazinoethanol was added to prepare a paste composition with a solid content of 80 mass %.

[0083] (Examples 11 and 12, Comparative Examples 10 and 12) Each bonded body was produced in the same manner as in Example 10, except that the copper particles (cakes) produced in Examples 2 and 3 and Comparative Examples 1 to 3 were used instead of the copper particles (cake) produced in Example 1.

[0084] [Measurement and Evaluation of Cuprous Oxide-Containing Coating Film] In Examples 7 to 12 and Comparative Examples 7 to 12, the cuprous oxide-containing coating film on the copper substrate was subjected to the following measurement and evaluation before heating in the sintering step (D). The evaluation results are shown in Table 3.

[0085] (X-ray Diffraction (XRD) Measurement) Before heating in the sintering step (D), the cuprous oxide-containing coating film on the copper substrate was analyzed using an X-ray diffractometer (product name: SmartLab SE, manufactured by Rigaku Corporation) with CuKα radiation as the radiation source, and the crystallite size was calculated from the Miller index (111) plane peak using the Scherrer equation by a focusing method. A split pseudo-Voigt function was used as the fitting function, the width was FWHM, and the Scherrer constant was 0.94. A Reactor X (manufactured by Rigaku Corporation) was used as the corrosion-resistant infrared heating sample high-temperature device for the X-ray diffractometer. The abundance ratio of cuprous oxide to copper was determined from the peak intensity ratio. The measurement results are shown in Table 3.

[0086] [Evaluation of Bonded Structure Characteristics] (Bonding Strength) The die shear strength (bonding strength) of each bonded structure was measured using a bond strength tester ("4000Plus Bond Tester", manufactured by Nordon DAGE; room temperature (25°C), distance from substrate to loading jig: 0.15 mm, loading speed: 30 mm / min). The evaluation results are shown in Table 3.

[0087]

[0088] The bonded bodies of Examples 10 to 12, in which a reducing compound was added during preparation of the paste composition, were found to have even higher bonding strengths than the bonded bodies of Examples 7 to 9. Comparing Examples 7 and 4, Examples 8 and 5, and Examples 9 and 6, in which the same paste composition was used, it was found that the bonded bodies of Examples 7 to 9, in which pressure was applied during production, had even higher bonding strengths.

Claims

The rate of change (A) of crystallite diameter calculated by the following calculation formula (1) is 100% or more, Copper particles, wherein the ratio (B / A) of the rate of change (A) to the rate of change (B) of crystallite diameter calculated by the following calculation formula (2) is 0.7 to 2.0: Rate of change (A) = [(S ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ] × 100 ... (1) Rate of change (B) = [((S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ] × 100 ... (2) [In calculation formula (1), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. In calculation formula (1), S ｉｎｉｔ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and copper particles. In calculation formula (2), S 6ｈ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 30°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. In calculation formula (2), S 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the copper particles are heated to 200°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. 　 The crystallite diameters (nm) of Cu(111) are values ​​calculated from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation.

2. The copper particles according to claim 1, which are plate-shaped with a major axis of 250 to 650 nm.

3. The copper particles according to claim 1, having an aspect ratio (major axis / thickness) of 5 to 15. 　 BET specific surface area is 1.0 to 15.0 m ２ The copper particles according to any one of claims 1 to 3, wherein the copper content is 1 / g. 　 The copper particles according to any one of claims 1 to 4, wherein the rate of change (C) of crystallite diameter calculated by the following calculation formula (3) is 100% or more. Rate of change (C) = [(S 6ｈ，２００℃（２００） -S 6ｈ，３０℃（２００） ) / S 6ｈ，３０℃（２００） ] × 100 ... (3) [In calculation formula (3), S 6ｈ，３０℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 30°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. In calculation formula (3), S 6ｈ，２００℃（２００） is the crystallite diameter (nm) of Cu(200) when the copper particles are heated to 200°C 6 hours after the solvent is dried from a copper particle dispersion containing the solvent and copper particles. 　 The crystallite diameters (nm) of Cu(200) are values ​​calculated from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation. 　 A method for producing a copper powder comprising the copper particles according to any one of claims 1 to 5 and a solvent, A paste-like composition, wherein the content of the copper particles is 50% by mass or more in 100% by mass of the paste-like composition. 　 A semiconductor device having a bonding layer formed using the paste composition according to claim 6. 　 A coating step (A) of coating a paste composition containing plate-like copper particles (Cu) and a solvent onto a substrate; At least a part of the coating film applied to the substrate is dried, and at least a part of the plate-like copper particles (Cu) is oxidized to cuprous oxide (Cu). ２ A drying step (B) of The cuprous oxide (Cu ２ a mounting step (C) of mounting a semiconductor element on the cuprous oxide-containing coating film containing The cuprous oxide-containing coating film on which the semiconductor element is mounted, ２ a sintering step (D) of heating the cuprous oxide-containing coating film to fix the semiconductor element to the substrate, wherein the cuprous oxide-containing coating film has a copper content of 20 mass% or less relative to 100 mass% of the plate-like copper particles (Cu) in the cuprous oxide-containing coating film, The plate-like copper particles (Cu) have a crystallite diameter change rate (A) calculated by the following calculation formula (1) of 100% or more, and a ratio (B / A) of the change rate (A) to the crystallite diameter change rate (B) calculated by the following calculation formula (2) of 0.7 to 2.

0. Rate of change (A) = [(S ｉｎｉｔ，２００℃（１１１） -S ｉｎｉｔ，３０℃（１１１） ) / S ｉｎｉｔ，３０℃（１１１） ] × 100 ... (1) Rate of change (B) = [((S 6ｈ，２００℃（１１１） -S 6ｈ，３０℃（１１１） ) / S 6ｈ，３０℃（１１１） ] × 100 ... (2) [In calculation formula (1), S ｉｎｉｔ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 30°C immediately after drying the solvent from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). In calculation formula (1), S ｉｎｉｔ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 200°C immediately after drying the solvent from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). In calculation formula (2), S 6ｈ，３０℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 30°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). In calculation formula (2), S 6ｈ，２００℃（１１１） is the crystallite diameter (nm) of Cu(111) when the plate-like copper particles (Cu) are heated to 200°C after 6 hours have passed since the solvent was dried from a copper particle dispersion containing the solvent and the plate-like copper particles (Cu). The crystallite diameters (nm) are values ​​calculated from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation.

9. The method for manufacturing a semiconductor device according to claim 8, wherein the paste-like composition contains 50% by mass or more of the plate-like copper particles (Cu) relative to 100% by mass of the paste-like composition. 　 The Cu in the cuprous oxide-containing coating film ２ 10. The method for manufacturing a semiconductor device according to claim 8, wherein the crystallite diameter of O(111) is 10 nm or less.

11. The method for manufacturing a semiconductor device according to claim 8, wherein the coating film has a thickness of 5 to 1000 μm.

12. The method for manufacturing a semiconductor device according to claim 8, wherein the drying step (B) comprises holding the substrate coated with the paste composition at 50 to 150°C for 1 to 60 minutes.

13. The method for manufacturing a semiconductor device according to claim 8, wherein the sintering step (D) comprises heating and pressurizing the cuprous oxide-containing coating film on which the semiconductor element is mounted at 180 to 350°C and 1 to 40 MPa to fix the semiconductor element to the substrate.

Images