Method for producing copper complex ink

Abstract

Provided is a method for producing a copper complex ink which has excellent storage stability and with which copper wiring having low volume resistivity and high smoothness can be produced.　The method for producing a copper complex ink containing a copper complex represented by general formula (HCOO)2Cu((CH3)2C(NH2)CH2OH)2 includes an agitation step for agitating a mixture of powder of Cu(HCOO)2·4H2O and a solid or liquid of (CH3)2C(NH2)CH2OH by a thin-film spin method, wherein the molar ratio of Cu(HCOO)2·4H2O to (CH3)2C(NH2)CH2OH in the mixture is 1:1.8 to 2.2.

Description

Manufacturing method of copper complex ink

[0001] The present invention relates to a method for producing a copper complex ink.

[0002] In recent years, printed electronics has been developed as a wiring technology for semiconductor elements, electronic circuits, etc. Printed electronics has attracted attention because it can reduce manufacturing costs compared to existing semiconductor manufacturing technologies such as photolithography.

[0003] Inks using complexes have been developed as inks for such printed electronics (for example, Patent Document 1, etc.). Patent Document 1 discloses that it is possible to provide a conductive ink for copper-nickel alloy electrodes, a substrate with copper-nickel alloy electrodes, which is low-cost, has excellent atmospheric stability, and enables metal wiring with a smooth surface, and a method for manufacturing the same.

[0004] WO2022 / 130892A1 WO2010 / 018771A1

[0005] Metal wiring can be obtained, for example, by applying a metal complex ink to form a thin film, followed by a heat treatment. However, when metal wiring is produced using conventional metal complex inks, particularly copper complex inks, the volume resistivity of the resulting copper wiring is high to begin with, and the copper complex ink has a problem with storage stability, which causes the volume resistivity of the copper wiring obtained using the copper complex ink to become even higher after storage.

[0006] Furthermore, it is preferable that the surface of metal wiring has high smoothness, but the smoothness of copper wiring obtained using conventional copper complex inks is low, and the smoothness of copper wiring obtained using copper complex inks after storage is even lower.

[0007] Therefore, an object of the present invention is to provide a method for producing a copper complex ink that has excellent storage stability, low volume resistivity, and is capable of producing copper wiring with high smoothness.

[0008] In order to solve the above problems, the method for producing a copper complex ink of the present invention comprises the steps of: ２ Cu((CH ３ ) ２ C(NH ２ ) CH２ OH) ２ A method for producing a copper complex ink containing a copper complex represented by the formula: Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ The method includes a stirring step of stirring a mixture of Cu(HCOO) and a solid or liquid material of Cu(HCOO) in the mixture by a thin film swirling method. ２ ・4H ２ O and (CH ３ ) ２ C(NH ２ ) CH ２ The molar ratio of OH is 1:1.8-2.2.

[0009] The stirring step may use a stirrer that includes a container having an inner wall surface and a rotating member that rotates slightly inside the inner wall surface, and that stirs the mixture that exists in a film-like form between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member, and the rotating member may be cylindrical and positioned with a small gap between it and the inner wall surface, and may have a plurality of holes that penetrate in an inward and outward direction, and the stirring step may be a step of stirring the mixture that exists in a film-like form between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member, and in the stirring step, Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ The conditions for forming the copper complex by coordinating OH as a ligand may be such that the peripheral speed of the rotating member is 0.5 m / s to 40.0 m / s, the temperature of the mixture is 10°C to 50°C, and the stirring time of the mixture is 5 minutes to 500 minutes.

[0010] The peripheral speed of the rotating member may be 5.0 m / s to 21.0 m / s, and the mixture may be stirred for 5 minutes to 40 minutes.

[0011] Before the stirring step, Cu(HCOO) ２ ・4H ２The method may include a pulverization step of pulverizing the O powder.

[0012] Before the stirring step, Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ The method may include a mixing step of mixing the OH with the solid to obtain the mixture.

[0013] The present invention can provide a method for producing a copper complex ink that has excellent storage stability, low volume resistivity, and excellent smoothness, and is capable of producing copper wiring.

[0014] FIG. 1 is a cross-sectional view of an example of an agitator that can be used in a method for producing a copper complex ink. FIG. 2 is an example of an image observed by a laser microscope. FIG. 3 is an example of an image observed by a laser microscope. FIG. 4 is an example of an image observed by a laser microscope. FIG. 5 is an enlarged SEM image of a cross section of the copper film in Example 2. FIG. 6 is an enlarged SEM image of a cross section of the copper film in Comparative Example 3.

[0015] Hereinafter, one embodiment of the method for producing a copper complex ink of the present invention will be described.

[0016] [Method of Manufacturing Copper Complex Ink] The method of manufacturing the copper complex ink of the present invention is a method of manufacturing a copper complex ink comprising a copper complex represented by the general formula (HCOO) ２ Cu((CH ３ ) ２ C(NH ２ ) CH ２ OH) ２ The present invention relates to a method for producing a copper complex ink containing a copper complex represented by the formula (CH ３ ) ２ C(NH ２ ) CH ２ OH (2-amino-methyl-propanol, hereinafter sometimes referred to as "AMP") is used as a ligand, copper formate (Cu(HCOO) ２ ) is in a state where two molecules are coordinated to (HCOO). ２ Cu((CH ３ ) ２ C(NH ２ ) CH ２ OH) ２The copper complex represented by the formula (I) is sometimes referred to as "Cu-AMP".

[0017] Copper complex ink contains the above copper complex as well as the raw material Cu(HCOO) ２ ・4H ２ It may contain water derived from the water of crystallization of copper formate tetrahydrate.

[0018] (Raw materials for copper complex ink) The raw materials for copper complex ink are Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ It is a solid of OH. (CH ３ ) ２ C(NH ２ ) CH ２ OH is Cu (HCOO) ２ Since two molecules are coordinated to Cu(HCOO), the molar ratio when mixing these is Cu(HCOO) ２ ・4H ２ O: (CH ３ ) ２ C(NH ２ ) CH ２ It is preferable that the molar ratio of Cu(HCOO) is 1:2, and the allowable range is 1:1.8 to 2.2. ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ The OH solid mixture is stirred in the following stirring step.

[0019] In addition, (CH ３ ) ２ C(NH ２ ) CH ２ OH is in a solid state at room temperature (5°C to 35°C), and Cu(HCOO) ２ Considering the coordination to (CH ３ ) ２ C(NH ２ ) CH ２ It is considered preferable to heat OH to make it liquid, but in the manufacturing method of this embodiment, copper complex ink can be manufactured without any problems even if it is used in a solid state.

[0020] <Crushing process> Cu (HCOO) ２ ・4H ２ O absorbs moisture from the atmosphere, increases in weight, and may aggregate to form lumps. Therefore, in order to pulverize these lumps and facilitate the mixing of the raw materials, Cu(HCOO) ２ ・4H ２ The method may include a pulverization step of pulverizing the O powder.

[0021] <Mixing process> The raw material for copper complex ink is Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ After mixing the raw materials with the solid OH to form a mixture, the mixture may be placed in a container of a stirrer described below and then the stirring step may be performed. Alternatively, these raw materials may be placed in their own containers without being mixed, and then the stirring step may be performed.

[0022] <Stirring process> In this process, Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ This is a process of stirring a mixture of OH and solid matter by thin film swirling. The thin film swirling method is a dispersion method in which the material to be dispersed is pressed against the inner wall surface of a treatment vessel by centrifugal force, and rotated at high speed in a thin cylindrical state, and shear stress generated by the centrifugal force and the speed difference with the inner wall surface of the treatment vessel is applied to the material to be dispersed within the thin cylindrical material to be dispersed.

[0023] (Agitator) An example of an agitator that can be used in the agitation step is an agitator that includes a container having an inner wall surface and a rotating member that rotates slightly inside the inner wall surface, and that agitates the mixture that exists in a film-like form between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member. The rotating member is cylindrical and positioned with a small gap between it and the inner wall surface, and has multiple holes that penetrate inward and outward.

[0024] An example of an agitator that can be used in the agitation step is the high-speed agitator 300 disclosed in Patent Document 2. More specifically, a thin film swirling high-speed mixer (Filmix (registered trademark), manufactured by Primix Corporation) can be used.

[0025] As shown in FIG. 1, the high-speed mixer 300 disclosed in Patent Document 2 has a container 310 and a rotating member 330 that rotates at high speed around a rotation axis 350 that extends vertically through the center of the container 310.

[0026] The container 310 has a substantially cylindrical inner wall surface 311 and defines a cylindrical space 312 having a predetermined length in the vertical direction. The rotating shaft 350 can be rotated at high speed by a high-torque motor (not shown) mounted on the top of the container 310. The cylindrical space 312 is separated into an upper space 312a and a lower space 312b by an inward flange 313. The mixture may be supplied into the container 310 from above. An outlet 315 connected to the upper space 312a is provided at the top of the container 310, and the produced copper complex ink may be discharged from this outlet 315 to the outside of the container 310. Alternatively, the material supply port 314 and the outlet 315 may be closed, and the mixture may be stirred in a batchwise manner to produce the copper complex ink.

[0027] In addition, the high-speed mixer 300 is provided with a jacket 320 through which cooling water circulates, surrounding the lower space 312b of the container 310, and a cooling water circulation path 321 is also formed in the upper space 312a, surrounding it.

[0028] The rotating member 330 is in the form of a cylindrical member 332 having an outer circumferential surface 331 that faces the inner wall surface 311 in the lower space 312b with a small gap S of about 1 to 3 mm between it and the inner wall surface 311, and is supported by a rotating shaft 350 via a support member 352. The cylindrical member 332 is also formed with a plurality of holes 333 that penetrate inward and outward.

[0029] It is desirable that at least the cylindrical member 332 of the rotating member 330 is formed of a material having excellent abrasion resistance, such as fine ceramics, or that the outer peripheral surface 331 of the cylindrical member 332 is coated with a material having excellent abrasion resistance, such as fine ceramics. Similarly, at least the region of the inner wall surface 311 of the container 310 that faces the rotating member 330 across the gap S may be coated with a material having excellent abrasion resistance, such as fine ceramics. An example of such fine ceramics is alumina ceramics.

[0030] The rotating member 330 can be rotated at high speeds, for example, so that the peripheral speed of the rotating member 330 (relative speed with respect to the inner wall surface 311) is 0.1 m / s to 50 m / s. A high-torque, high-output motor is required to rotate the rotating member 330 at such a peripheral speed while still providing a stirring effect. The dimensions of the container 310 and the rotating member 330 are selected to accommodate the available motor. The processing capacity of this high-speed mixer 300 is approximately proportional to the area of ​​the outer peripheral surface 331 of the rotating member 330, assuming that the peripheral speed of the rotating member 330 is constant. Therefore, increasing the radial dimensions of the container 310 and the rotating member 330 is sufficient to increase the processing capacity.

[0031] When a mixture is supplied to the high-speed mixer 300, the mixture is pressed against the inner wall surface 311 of the container 310 by the centrifugal force of the rotating member 330 rotating at high speed, and is introduced so as to fill the gap S between the outer circumferential surface 331 of the cylindrical member 332 of the rotating member 330 and the inner wall surface 311 of the container 310. In this embodiment, since a plurality of holes 333 are formed in the cylindrical member 332, the mixture adhering to the inner surface of the cylindrical member 332 is also smoothly introduced into the gap S.

[0032] During stirring by the high-speed mixer 300, the mixture is subjected to a stirring action due to the powerful shear energy between the rotating member 330 and the inner wall surface 311, and may become heated due to heat caused by friction. However, the mixture is cooled appropriately by the cooling water flowing through the cooling water circulation jacket 320 and the cooling water circulation path 321, thereby preventing the mixture from becoming excessively hot.

[0033] Furthermore, if the outer surface 331 of the rotating member 330 and the inner wall surface 311 of the container 310 are coated with a material with excellent abrasion resistance, such as fine ceramics, it is possible to effectively prevent the mixture from being contaminated with minute foreign matter such as metal wear powder due to the mixture being subjected to a strong shear force when present in the gap S between them.

[0034] (Stirring Conditions) In the stirring step using a stirrer, the mixture present in a film form between the rotating member and the inner wall surface can be stirred by the centrifugal force generated by the rotation of the rotating member, and in the stirring step, Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ Copper complex ((HCOO) ２ Cu((CH ３ ) ２ C(NH ２ ) CH ２ OH) ２ ) can be formed.

[0035] Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ An example of specific conditions for forming a copper complex by coordinating OH as a ligand is a peripheral speed of the rotating member of 0.5 m / s to 21.0 m / s, a temperature of the mixture of 10°C to 30°C, and a stirring time of the mixture of 5 minutes to 500 minutes.

[0036] <Peripheral speed of rotating element> When the peripheral speed of the rotating element is set to 0.5 m / s to 40.0 m / s, the mixture that exists in the form of a film between the outer surface of the cylindrical element and the inner wall surface of the container can have a steep velocity gradient with a thickness of just 1 to 3 mm. For example, when the peripheral speed is 21.0 m / s, the velocity gradient is 0 to 20 m / s. Due to this velocity gradient, the mixture is continuously subjected to a powerful shear force, and this powerful energy achieves a significantly high level of dispersion. This is thought to be because such powerful shear energy acts on the mixture that a phenomenon similar to a sudden turbulent transition continuously occurs in the mixture.

[0037] If the peripheral speed of the rotating member is less than 0.5 m / s, the slow peripheral speed may result in insufficient shear force, resulting in insufficient dispersion. Although there is no particular upper limit to the peripheral speed of the rotating member, the upper limit of the peripheral speed is approximately 40.0 m / s, which is the performance limit value for the current high-speed mixer 300.

[0038] <Mixture Temperature> The mixture generates heat during stirring due to the continuous application of strong shear forces. A sudden rise in the mixture temperature can make it difficult to control the coordination bond formation. Therefore, by controlling the temperature of the mixture during stirring to 10°C to 50°C, the progress of coordination bond formation can be controlled while preventing the mixture from becoming excessively hot. It is more preferable to control the mixture temperature within the range of 10°C to 30°C. Since coordination bond formation also progresses rapidly if the mixture temperature rises rapidly above 50°C, it is important to carefully monitor the mixture while stirring. Although a mixture temperature below 10°C does not affect the reaction, the effort and extra energy required for cooling to below 10°C is required, which is costly and therefore uneconomical.

[0039] <Mixture Stirring Time> Although it depends on the temperature conditions of the mixture and the peripheral speed conditions of the rotating member, by setting the mixture stirring time to 5 to 500 minutes, (CH3) ２ C(NH ２ ) CH ２ Cu OH (HCOO) ２ can be sufficiently coordinated to

[0040] Conventional copper complex inks may have precipitated particles immediately after production, or may have precipitated particles that increase in number over time after production. Copper wiring manufactured using copper complex ink with a large amount of precipitated particles has a high volume resistivity and poor smoothness. However, according to the manufacturing method of the present embodiment, there are no precipitated particles at the beginning of production, and the generation of precipitated particles over time can be suppressed. Therefore, by using the manufactured copper complex ink, it is possible to form copper wiring with a low volume resistivity and high smoothness.

[0041] The stirring conditions may include a peripheral speed of the rotating member of 5.0 m / s to 21.0 m / s and a stirring time of the mixture of 5 to 40 minutes. By adopting such stirring conditions, the generation of precipitated particles due to storage of the produced copper complex ink can be further suppressed.

[0042] [Copper Complex Ink] The copper complex ink produced according to the present invention is a copper complex having a general formula (HCOO) ２ Cu((CH3) ２ C(NH ２ ) CH ２ OH) ２ The copper complex may contain a solvent or an additive as appropriate.

[0043] Examples of solvents that can be contained in the copper complex ink include hydrocarbon-based solvents, alcohol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, glycol-based solvents, glyme-based solvents, halogen-based solvents, aromatic solvents, and heterocycle-containing solvents.

[0044] The copper complex ink may also contain additives such as adhesion promoters, surface conditioners, antifoaming agents, and rheology control agents.

[0045] The copper complex ink produced according to the present invention has a 0% by area ratio of precipitated particles on the day of production. Copper complex ink produced according to conventional production methods (e.g., Patent Document 1) contains a large amount of precipitated particles immediately after production, including large particles with diameters of 10 μm or more. The presence of a large amount of precipitated particles results in copper wiring produced using this copper complex having a high volume resistivity and low smoothness.

[0046] As in the present invention, the absence of precipitated particles immediately after production enables the formation of copper wiring with low volume resistivity and high smoothness. Furthermore, the copper complex ink produced by the production method of the present invention has a precipitated particle presence rate of less than 50 area % within 7 days of production. As described above, the presence of a large amount of precipitated particles resulted in copper wiring produced using this copper complex having high volume resistivity and low smoothness. A characteristic of copper complex ink is that precipitated particles gradually appear and increase over time after production. However, if the precipitated particle presence rate is less than 50 area %, copper wiring with low volume resistivity and high smoothness can be formed.

[0047] The proportion of precipitated particles present within 7 days from production is preferably less than 40 area %, more preferably less than 2 area %, even more preferably less than 0.5 area %, and most preferably 0 area %. The fewer precipitated particles there are in the copper complex ink, the lower the volume resistivity and the more smooth the copper wiring can be produced.

[0048] In the copper complex ink produced according to the present invention, even if precipitated particles are present, it is preferable that the maximum particle size of the precipitated particles be less than 10 μm. If the particle size is 10 μm or more, the smoothness of the copper wiring produced using this copper complex ink will be extremely reduced.

[0049] The maximum particle size refers to the particle size of the largest particle among the precipitated particles. The smaller the maximum particle size of the precipitated particles, the higher the smoothness of the copper wiring produced using this copper complex ink. The maximum particle size of the precipitated particles is preferably less than 5 μm, more preferably less than 3 μm, and even more preferably less than 1 μm.

[0050] The copper complex ink produced by the present invention exhibits a shear rate of 5.34 S －１In this case, the viscosity may be 1 to 10 Pa·s. When the viscosity is 1 to 10 Pa·s, the copper complex ink has good removability when passing through the screen, resulting in excellent screen printability. If the viscosity is less than 1 Pa·s, the viscosity is too low and there is a risk that the ink will not be able to be printed in a shape such as a wiring. If the viscosity is greater than 10 Pa·s, the viscosity is too high and the copper complex ink will not pass through the screen, which may result in printing being impossible.

[0051] The copper complex ink produced according to the present invention may have a viscosity change rate of 20% or less after 7 days from production relative to the viscosity on the day of production. Copper complex inks produced according to conventional production methods (e.g., Patent Document 1) have poor storage stability and tend to have a significant decrease in viscosity over time after production. Therefore, when producing copper wiring, it may be necessary to change the production conditions for the copper wiring depending on the change in viscosity. However, since the copper complex ink produced according to the present invention has a small viscosity change rate due to storage, copper wiring can be produced using copper complex ink even after 7 days from production under the same conditions as when using copper complex ink immediately after production.

[0052] The copper complex ink produced by the present invention has a shear rate of 0.01 S for 7 days after production. －１ The viscosity when the shear rate is 100S －１ The value obtained by dividing the viscosity by the viscosity in the case of (1) may be less than 10. This value serves as a guideline for indicating the thixotropy of a copper complex ink intended for screen printing. When the copper complex ink is screen printed, i.e., at high shear rates, it exhibits excellent liquid-like fluidity behavior, thereby improving screen removability. It is important that the copper complex ink, which has a slow shear rate after passing through the screen and being printed, behaves like a solid so that it can maintain the printed shape. From this perspective, when this value is less than 10, excellent printing properties, such as screen printing, are achieved. Furthermore, if this value is 10 or more, there is no problem with printing properties, but if the presence ratio of precipitated particles, described below, exceeds 50 area %, this value may be 10 or more, and this value can serve as a guideline for predicting the presence of precipitated particles.

[0053] [Method for Producing Copper Film] Next, one embodiment of a method for producing a copper film using the copper complex ink produced by the present invention will be described. The obtained copper film can be used as a raw material for copper wiring, die attach material, sinter material, etc., and the shape, thickness, etc. can be set as desired.

[0054] <Heat Treatment Step> The method for producing a copper film includes a heat treatment step, in which the copper complex ink produced according to the present invention is heat-treated to form a copper film.

[0055] The heat treatment conditions may be any conditions that volatilize the ligands, such as formic acid and AMP, from the copper complex ink, and, if water is unavoidably contained in the ink, also volatilize the water, thereby precipitating copper particles. For example, the heat treatment conditions include raising the temperature from room temperature to 250°C at a rate of 20°C / min in an inert atmosphere, such as nitrogen gas or argon gas, so as not to be in an air atmosphere, and then heating at 250°C for 10 minutes.

[0056] (Other Steps) The method for producing a copper film may include other steps in addition to the heat treatment step described above. For example, before the heat treatment, a film formation step may be performed in which a copper complex ink is applied to an object to be coated, such as an electronic substrate including an alumina substrate, a polyimide film, a PET film, or glass, by screen printing, inkjet printing, gravure printing, gravure offset printing, a dispenser, or the like to form a copper complex film for wiring or the like. Furthermore, an anti-oxidation treatment may be performed to prevent oxidation of the surface of the copper film after the heat treatment.

[0057] [Copper Film] A copper film obtained by heating a copper complex ink produced by a conventional manufacturing method has many fine holes, which act as electrical resistance, resulting in a high volume resistivity. Furthermore, if the copper film does not have high smoothness, it cannot be used for high-frequency applications. On the other hand, a copper film obtained by a copper film manufacturing method using the copper complex ink produced by the manufacturing method of the present invention can have the characteristics of low volume resistivity and high smoothness. High smoothness leads to excellent conductivity and durability. For example, a copper film having a volume resistivity of less than 100 μΩ cm and an average film roughness Sa of less than 6 μm can be obtained.

[0058] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In these examples and comparative examples, a copper complex ink was first prepared, and the storage stability of the prepared copper complex ink and the physical properties of a copper film formed using the copper complex ink were evaluated.

[0059] [Production of copper complex ink] Example 1 (Mixing step) Cu(HCOO) ２ ・4H ２ Powder of copper formate tetrahydrate (CH ３ ) ２ C(NH ２ ) CH ２ 10 g of a mixture was prepared by mixing solids of Cu(HCOO) and Cu(HCOO). ２ ・4H ２ No grinding step for grinding the powder of O was carried out, and ３ ) ２ C(NH ２ ) CH ２ The OH was not preliminarily heated to a liquid state.

[0060] (Stirring step) In the stirring step, a thin film swirling method was adopted, and a thin film swirling high-speed mixer (Filmix (registered trademark) FM-30-L manufactured by Primix Corporation) was used as the stirrer. 10 g of the mixture was placed in the container of the stirrer and stirred to obtain Cu(HCOO). ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ Copper complex ink was prepared by coordinating OH as a ligand.

[0061] The conditions for the stirring step were that the rotation speed of the rotating member was 15,000 rpm, the peripheral speed was 20.42 m / s, the temperature of the mixture was maintained at 10° C., and stirring was carried out for 10 minutes.

[0062] Table 1 shows Cu(HCOO) ２ ・4H ２ O (copper formate tetrahydrate) and (CH ３ ) ２ C(NH ２ ) CH ２The molar ratio of the mixture with OH (2-amino-methyl-propanol), the amount of the mixture charged, the grinding process and (CH ３ ) ２ C(NH ２ ) CH ２ The conditions for Examples 2 to 5 and Comparative Examples 1 to 12 below are shown in Table 1, including whether or not OH liquefaction treatment was performed, and the stirring speed, peripheral speed, temperature of the mixture, and treatment time in the stirring step.

[0063] Example 2 The stirring time in the stirring step was changed from 10 minutes in Example 1 to 15 minutes, while the other conditions were the same as in Example 1, to produce a copper complex ink.

[0064] Example 3 A copper complex ink was produced under the same conditions as in Example 1, except that the rotation speed of the rotating member in the stirring step was changed to 5000 rpm, the peripheral speed was changed to 6.81 m / s, and the stirring treatment time was changed to 30 minutes.

[0065] Example 4 A copper complex ink was produced under the same conditions as in Example 1, except that the rotation speed of the rotating member in the stirring step was changed to 500 rpm, the peripheral speed was changed to 0.68 m / s, and the stirring treatment time was changed to 480 minutes.

[0066] Example 5 (Crushing step) Before the mixing step, Cu(HCOO) ２ ・4H ２ A grinding step was carried out to grind the Cu(HCOO) powder. Specifically, the Cu(HCOO) powder was ground in a mortar until it was completely powdered and free of lumps. ２ ・4H ２ The lumps of O were crushed. Thereafter, the mixing step and the stirring step were carried out under the same conditions as in Example 4 to produce a copper complex ink.

[0067] Comparative Example 1 (Crushing Step) Before the mixing step, Cu(HCOO) ２ ・4H ２ A grinding step was carried out to grind the Cu(HCOO) powder. Specifically, the Cu(HCOO) powder was ground in a mortar until it was completely powdered and free of lumps. ２ ・4H ２ The O chunks were crushed.

[0068] (Mixing step) Put the contents of the mixture into a 30 ml screw tube equipped with a stirrer (CH ３) ２ C(NH ２ ) CH ２ After adding the OH solid, (CH ３ ) ２ C(NH ２ ) CH ２ The temperature of OH was raised to 45°C, and the solid was liquefied. Then, Cu(HCOO) ２ ・4H ２ Powder of copper formate tetrahydrate was added to the screw tube and mixed to obtain Cu(HCOO). ２ ・4H ２ O (copper formate tetrahydrate) and (CH ３ ) ２ C(NH ２ ) CH ２ 10 g of a mixture of 1:2 molar ratio of OH (2-amino-methyl-propanol) was prepared.

[0069] (Stirring step) In the stirring step, a magnetic stirrer was used instead of the thin film rotation method, and a hot stirrer REXIM RSH-4DN (manufactured by AS ONE Corporation) was used as the stirrer. The screw tube containing the mixture was placed in the hot stirrer and the mixture was stirred, and Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ Copper complex ink was prepared by coordinating OH as a ligand.

[0070] The stirring conditions were that the stirrer rotation speed was 500 rpm, and the mixture temperature was maintained at 45°C, and stirring was continued for 1,440 minutes.

[0071] Comparative Example 2 A copper complex ink was produced under the same conditions as in Comparative Example 1, except that the pulverization step was not carried out.

[0072] Comparative Example 3 A copper complex ink was produced under the same conditions as in Comparative Example 1, except that the stirrer rotation speed was 100 rpm and the stirring time was 4,320 minutes.

[0073] Comparative Example 4 A copper complex ink was produced under the same conditions as in Comparative Example 1, except that the stirrer rotation speed was set to 100 rpm, the temperature of the mixture was changed from 45°C to room temperature without heating, and the stirring treatment time was set to 1,440 minutes.

[0074] <Comparative Example 5> (CH ３ ) ２ C(NH ２ ) CH ２ The conditions were the same as those in Comparative Example 3, except that the OH was not previously heated to make it liquid. Since the liquefaction treatment was not performed, the temperature of the mixture was room temperature (5°C to 35°C), and the (CH ３ ) ２ C(NH ２ ) CH ２ Since OH was in a solid state, it was not possible to produce a copper complex ink even when stirring with a hot stirrer REXIM RSH-4DN.

[0075] Comparative Example 6 (Crushing Step) Before the mixing step, Cu(HCOO) ２ ・4H ２ A grinding step was carried out to grind the Cu(HCOO) powder. Specifically, the Cu(HCOO) powder was ground in a mortar until it was completely powdered and free of lumps. ２ ・4H ２ The O chunks were crushed.

[0076] (Mixing step) Add the contents to a 300 ml beaker (CH ３ ) ２ C(NH ２ ) CH ２ After adding the OH solid, (CH ３ ) ２ C(NH ２ ) CH ２ The OH was heated to a temperature of 45°C to convert the solid into a liquid. ２ ・4H ２ Powder of copper formate tetrahydrate was added to a beaker and mixed to obtain Cu(HCOO). ２ ・4H ２ O (copper formate tetrahydrate) and (CH ３ ) ２ C(NH ２ ) CH ２100 g of a mixture of 1:2 molar ratio of OH (2-amino-methyl-propanol) was prepared.

[0077] (Stirring step) In the stirring step, motor stirring was adopted instead of the thin film rotation method, and a propeller blade three-one motor (manufactured by Shinto Scientific Co., Ltd.) was used as the stirrer. The beaker containing the mixture was placed on the three-one motor and the mixture was stirred, and Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ Copper complex ink was prepared by coordinating OH as a ligand.

[0078] The stirring conditions were that the propeller blade rotation speed was 100 rpm, and the mixture was stirred for 1,440 minutes while maintaining the temperature at room temperature.

[0079] <Comparative Example 7> (CH ３ ) ２ C(NH ２ ) CH ２ A copper complex ink was produced under the same conditions as in Comparative Example 6, except that the OH was not previously heated to form a liquid and the temperature of the mixture was maintained at 45°C.

[0080] Comparative Example 8 A copper complex ink was produced under the same conditions as in Comparative Example 6, except that the pulverization step was not carried out.

[0081] Comparative Example 9: The grinding step was not performed. ３ ) ２ C(NH ２ ) CH ２ A copper complex ink was produced under the same conditions as in Comparative Example 6, except that the OH was not previously heated to form a liquid and the temperature of the mixture was maintained at 45°C.

[0082] Comparative Example 10: The grinding step was not performed, and (CH ３ ) ２ C(NH ２ ) CH ２The conditions were the same as those in Comparative Example 6, except that the treatment of liquefying OH by heating in advance was not carried out. Since the treatment of liquefying was not carried out, the temperature of the mixture was room temperature (5°C to 35°C), and ３ ) ２ C(NH ２ ) CH ２ Since OH was in a solid state, it was not possible to produce a copper complex ink even when it was stirred with a propeller blade three-one motor.

[0083] Comparative Example 11 (Crushing Step) Before the mixing step, Cu(HCOO) ２ ・4H ２ A grinding step was carried out to grind the Cu(HCOO) powder. Specifically, the Cu(HCOO) powder was ground in a mortar until it was completely powdered and free of lumps. ２ ・4H ２ The O chunks were crushed.

[0084] (Mixing step) Put into a container with a capacity of 100 ml (CH ３ ) ２ C(NH ２ ) CH ２ After adding the OH solid, (CH ３ ) ２ C(NH ２ ) CH ２ The OH was heated to a temperature of 45°C to convert the solid into a liquid. ２ ・4H ２ Powder of Cu(HCOO) was added to the container. ２ ・4H ２ O (copper formate tetrahydrate) and (CH ３ ) ２ C(NH ２ ) CH ２ 10 g of a mixture of 1:2 molar ratio of OH (2-amino-methyl-propanol) was prepared.

[0085] (Stirring step) In the stirring step, a planetary mixer was used instead of the thin film rotation method, and an ARE-310 (manufactured by Thinky Corporation) was used as the stirrer. The container containing the mixture was placed in the ARE-310, and the mixture was stirred to obtain Cu(HCOO). ２ ・4H ２ O to Cu (CH３ ) ２ C(NH ２ ) CH ２ Copper complex ink was prepared by coordinating OH as a ligand.

[0086] The conditions for the stirring step were that the rotation speed of the ARE-310 was 2000 rpm, and the mixture was stirred for 30 minutes while being kept at room temperature.

[0087] <Comparative Example 12> (CH ３ ) ２ C(NH ２ ) CH ２ A copper complex ink was produced under the same conditions as in Comparative Example 11, except that the treatment for liquefying the OH solid was not carried out.

[0088] [Evaluation of Physical Properties Using Copper Complex Ink] The following physical properties were evaluated using the produced copper complex ink.

[0089] <Observation of Precipitated Particles> The copper complex inks of Examples 1 to 5 and Comparative Examples 1 to 4, 6 to 9, 11, and 12 were allowed to stand and stored for 7 days at room temperature (5°C to 35°C), and a drop of each of the copper complex inks immediately after production and after 7 days of storage was placed on a glass slide, and the test specimens were sandwiched between cover glasses to ensure a uniform field of view, and observed with a laser microscope to observe the presence or absence of precipitated particles.

[0090] The results of observing the presence or absence of precipitated particles are shown in Table 1. In Table 1, the case where no precipitated particles were observed was evaluated as ○, the case where precipitated particles were observed but the proportion of precipitated particles was less than 50 area % within the area observed with the laser microscope, and it was determined that the copper complex ink was usable without affecting the physical properties of the copper wiring, was evaluated as △, and the case where the proportion of precipitated particles was 50 area % or more within the area observed with the laser microscope, and it was determined that the copper complex ink was unusable because it affected the physical properties of the copper wiring, was evaluated as ×.

[0091] Figures 2 to 4 show examples of images observed with a laser microscope. Figure 2 is an image showing no precipitated particles and rated as ◯, Figure 3 is an image showing a precipitated particle presence rate of 49 area % and rated as △, and Figure 4 is an image showing a precipitated particle presence rate of 84 area % and rated as ×. The scale bars shown in Figures 2 to 4 are 100 μm.

[0092]

[0093] (Observation results of precipitated particles) As can be seen from Table 1, copper complex inks with the best storage stability were produced in Examples 1 to 3. Furthermore, under the conditions of Examples 4 and 5, the generation of precipitated particles was observed after 7 days of storage, but this was within the acceptable range.

[0094] In the results of Comparative Examples 1 to 10, although there were cases in which no precipitated particles were observed in the copper complex ink immediately after production, after 7 days of storage, a large amount of precipitated particles were generated, making the ink unusable as a material for copper wiring.

[0095] In the results of Comparative Examples 11 and 12, (CH ３ ) ２ C(NH ２ ) CH ２ By heating the OH to a temperature of 45°C and carrying out a process to liquefy the solids, a good copper complex ink could be produced (Comparative Example 11). However, without this liquefying process, the copper complex ink resulted in a large amount of precipitated particles immediately after production (Comparative Example 12). Note that Examples 1 to 5 are easier to produce than Comparative Example 11 in that they do not require the liquefying process. Furthermore, while the planetary mixer used in Comparative Example 11 is not suitable for mass production, the thin film swirling method used in Examples 1 to 5 allows for the agitator to be scaled up, and copper complex inks can be produced not only by a batch method but also by circulating the mixture. Therefore, the production examples of Examples 1 to 5 are superior to the production example of Comparative Example 11 in that they are easier to mass-produce.

[0096] <Viscosity Measurement of Copper Complex Ink> The copper complex inks of Example 2 and Comparative Example 3 were stored at room temperature (5° C. to 35° C.), and the viscosity was measured over time to evaluate the viscosity change and thixotropy.

[0097] The viscosity was measured using a rheometer MCR302e manufactured by Anton Paar, with a disposable parallel plate of φ25 mm. The gap between the upper and lower plates was fixed at 0.2 mm, and the shear rate was 0.01 sec. －１ From 100 seconds －１The viscosity was measured while increasing the shear rate to 0.01 sec. －１ Viscosity and shear rate at 100 sec －１ The viscosity was read when the shear rate was 0.01 sec. －１ The viscosity when the shear rate is 100 sec －１ The thixotropy index was calculated by dividing the viscosity by the viscosity at the time of measurement.

[0098] The results of the viscosity change are shown in Table 2, and the evaluation results of the thixotropy are shown in Table 3.

[0099]

[0100]

[0101] (Results) The copper complex ink of Example 2 maintained a stable viscosity from production until 180 days after storage, but the viscosity of the copper complex ink of Comparative Example 3 tended to gradually decrease. Furthermore, with regard to thixotropy, the copper complex ink of Example 2 remained stable from production until 30 days after storage, but the copper complex ink of Comparative Example 3 tended to show a gradual decrease in value.

[0102] [Physical Properties of Copper Film] The copper complex inks of Example 2 and Comparative Example 3 were left to stand and stored at room temperature (5°C to 35°C), and a copper film was formed using the stored copper complex ink, and its physical properties were evaluated.

[0103] <Production of Copper Film> Two pieces of masking tape (Clear Line Tape 536, manufactured by Nichiban) with a thickness of approximately 100 μm were attached to an alumina substrate (A476, manufactured by Kyocera) with a 5 mm gap between them. An appropriate amount of ink was applied to the side of the alumina substrate where the masking tape was not attached, and the ink was smoothed with a squeegee. The masking tape was then peeled off, and a coating film with a thickness of approximately 100 μm, a width of approximately 5 mm, and a length of 1.52 mm was produced on the alumina substrate. This coating film was placed in a reflow furnace and heated from room temperature to 250°C at a rate of 20°C / min under a nitrogen atmosphere, and then held at 250°C for 10 minutes to obtain a heat-treated copper film. The width and length of the resulting copper film were measured with vernier calipers, and the thickness was measured with a laser microscope.

[0104] <Measurement of Volume Resistivity> Measurement was performed by the four-terminal method using a Hioki EE RM3548 resistance meter and pin-type leads as electrode terminals. The resistance value of the copper film was measured by contacting the electrode terminals with both ends of the obtained copper film. The volume resistivity was calculated by using the obtained resistance value and calculating "resistance value × width of copper film × thickness of copper film ÷ length of copper film."

[0105] The volume resistivity was measured, and the changes in the value due to storage of the copper complex ink are shown in Table 4.

[0106]

[0107] (Results) The results of Example 2 and Comparative Example 3 both show that the volume resistivity tends to increase depending on the storage period of the copper complex ink, but the original value was lower in Example 2. Specifically, the volume resistivity of Example 2 after 180 days of storage was lower than the volume resistivity of Comparative Example 3 immediately after production.

[0108] <Measurement of Average Film Roughness Sa> The average film roughness Sa of the copper film was measured using a laser microscope VK-X3000 manufactured by Keyence Corporation.

[0109] The average film roughness Sa was measured, and the changes in the value due to storage of the copper complex ink are shown in Table 5.

[0110]

[0111] (Results) The results of Example 2 and Comparative Example 3 both show that the average film roughness Sa tends to increase depending on the storage period of the copper complex ink, but the original numerical value was lower in Example 2. Specifically, in the case of Example 2, the value of the average film roughness Sa remained stable up to 120 days after storage, and the average film roughness Sa of Example 2 after 120 days of storage was about half the value of the average film roughness Sa of Comparative Example 3 immediately after production.

[0112] <SEM observation of cross section of copper film> Of the produced copper films, the cross section of the copper film produced using the copper complex ink after 30 days of storage was observed using a scanning electron microscope (SEM). Fig. 5 shows an SEM image of the cross section of the copper film in Example 2 enlarged 30,000 times, and Fig. 6 shows an SEM image of the cross section of the copper film in Comparative Example 3 enlarged 30,000 times. The scales shown in Figs. 5 and 6 are 1.00 µm.

[0113] 5 and 6 show that the copper particles in the copper film of Example 2 were more densely packed than those in the copper film of Comparative Example 3. This difference in state is thought to cause changes in the volume resistivity and average film roughness Sa of the copper film.

[0114] The present invention can provide a method for producing a copper complex ink that has excellent storage stability and is capable of producing copper wiring with low volume resistivity and high smoothness, and is therefore industrially useful.

[0115] 300 High-speed agitator, 310 Container, 311 Inner wall surface, 312 Cylindrical space, 312a Upper space, 312b Lower space, 313 Inward flange, 314 Material supply port, 315 Discharge port, 320 Jacket, 321 Cooling water circulation path, 330 Rotating member, 331 Outer circulating surface, 332 Cylindrical member, 333 Hole, 350 Rotating shaft, 352 Support member, S Gap

Claims

1. General formula (HCOO) ２ Cu((CH ３ ) ２ C(NH ２ ) CH ２ OH) ２ A method for producing a copper complex ink containing a copper complex represented by the formula Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ a stirring step of stirring a mixture of Cu(HCOO) and a solid or liquid material by a thin film swirling method, ２ ・4H ２ O and (CH ３ ) ２ C(NH ２ ) CH ２ The method for producing a copper complex ink, wherein the molar ratio of OH is 1:1.8 to 2.

2.

2. The stirring step uses a stirrer that includes a container having an inner wall surface and a rotating member that rotates slightly inside the inner wall surface, and stirs the mixture that exists in a film-like state between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member, the rotating member is cylindrical and positioned with a small gap between it and the inner wall surface, and has a plurality of holes that penetrate in an inward and outward direction, the stirring step is a step of stirring the mixture that exists in a film-like state between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member, and in the stirring step, Cu(HCOO) ２ ・4H ２ O to Cu (CH ３ ) ２ C(NH ２ ) CH ２ 2. The method for producing a copper complex ink according to claim 1, wherein the conditions for forming the copper complex by coordinating OH as a ligand are: a peripheral speed of the rotating member is 0.5 m / s to 40.0 m / s; a temperature of the mixture is 10°C to 50°C; and a stirring time of the mixture is 5 minutes to 500 minutes.

3. The method for producing a copper complex ink according to claim 2, wherein the peripheral speed of the rotating member is 5.0 m / s to 21.0 m / s, and the stirring time of the mixture is 5 minutes to 40 minutes.

4. Before the stirring step, Cu(HCOO) ２ ・4H ２ The method for producing the copper complex ink according to claim 1 , further comprising a pulverizing step of pulverizing a powder of O.

5. Before the stirring step, Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ The method for producing a copper complex ink according to claim 1 , further comprising a mixing step of mixing the copper complex ink with the solid of OH to obtain the mixture.

Images