Manufacturing method of copper complex ink

Abstract

Provided is a method for producing a copper complex ink that has excellent storage stability, low volume resistivity, and high smoothness, and that can produce copper wiring. [Solution] A method for producing a copper complex ink containing a copper complex represented by the general formula (HCOO)2Cu((CH3)2C(NH2)CH2OH)2, comprising a stirring step of stirring a mixture of powdered Cu(HCOO)2·4H2O and solid or liquid (CH3)2C(NH2)CH2OH by a thin film swirling 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

[Technical Field]

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

[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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2022 / 130892A1 [Patent Document 2] WO2010 / 018771A1 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a method for producing a copper complex ink containing a copper complex represented by the general formula (HCOO)2Cu((CH3)2C(NH2)CH2OH)2, and includes a stirring step of stirring a mixture of Cu(HCOO)2·4H2O powder and solid or liquid (CH3)2C(NH2)CH2OH by a thin film swirling 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.

[0009] The stirring step may use a stirrer including 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 has been made to exist in the form of a film between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member. 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 inward and outward directions. The stirring step may be a step of stirring the mixture that has been made to exist in the form of a film between the rotating member and the inner wall surface by centrifugal force generated by the rotation of the rotating member. In the stirring step, the conditions for coordinating (CH)C(NH)CHOH as a ligand to Cu in Cu(HCOO)4H0 to form the copper complex may be a peripheral speed of the rotating member of 0.5 m / s to 40.0 m / s, a temperature of the mixture of 10°C to 50°C, and a stirring time of the mixture of 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] A grinding step of grinding powder of Cu(HCOO)2·4H2O may be included before the stirring step.

[0012] Before the stirring step, a mixing step of mixing powder of Cu(HCOO)2·4H2O with solid (CH3)2C(NH2)CH2OH to obtain a mixture may be included. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view of an example of a stirrer that can be used in a method for producing a copper complex ink. [Figure 2] 1 is an example of an image observed using a laser microscope. [Figure 3] 1 is an example of an image observed using a laser microscope. [Figure 4] 1 is an example of an image observed using a laser microscope. [Figure 5] 1 is an enlarged SEM image of a cross section of a copper film in Example 2. [Figure 6] 10 is an enlarged SEM image of a cross section of a copper film in Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[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 for producing a copper complex ink of the present invention is a method for producing a copper complex ink containing a copper complex represented by the general formula (HCOO)2Cu((CH3)2C(NH2)CH2OH)2. This copper complex can be said to be in a state in which two molecules of (CH3)2C(NH2)CH2OH (2-aminomethylpropanol, hereinafter sometimes referred to as "AMP") are coordinated to copper formate (Cu(HCOO)2) as a ligand. Hereinafter, the copper complex represented by (HCOO)2Cu((CH3)2C(NH2)CH2OH)2 will sometimes be referred to as "Cu-AMP."

[0017] In addition to the copper complexes mentioned above, copper complex ink may contain water derived from the crystallization water of the raw material Cu(HCOO)2·4H2O (copper formate tetrahydrate).

[0018] (Raw material for copper complex ink) The raw materials for copper complex ink are Cu(HCOO)2·4H2O powder and (CH3)2C(NH2)CH2OH solid. Since two molecules of (CH3)2C(NH2)CH2OH coordinate to Cu(HCOO)2, the molar ratio when mixing these is preferably Cu(HCOO)2·4H2O to (CH3)2C(NH2)CH2OH = 1:2, with an allowable range of this molar ratio being between 1:1.8 and 2.2. The mixture of Cu(HCOO)2·4H2O powder and (CH3)2C(NH2)CH2OH solid is mixed in the following mixing process.

[0019] (CH3)2C(NH2)CH2OH is in a solid state at room temperature (5°C to 35°C), and considering that it will be coordinated to Cu(HCOO)2, it is considered preferable to heat (CH3)2C(NH2)CH2OH to make it liquid. However, 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)2·4H2O may increase in weight by absorbing moisture from the air and may also aggregate to form lumps. Therefore, to crush these lumps and facilitate mixing of the raw materials, a crushing step of crushing Cu(HCOO)2·4H2O powder may be included before the stirring step described below.

[0021] <Mixing process> The raw materials for copper complex ink can be prepared by mixing powdered Cu(HCOO)2·4H2O and solid (CH3)2C(NH2)CH2OH to form a mixture, then adding the mixture to the container of the mixer described below and carrying out the stirring process. Alternatively, these raw materials can be separately placed in their own containers and then stirred without mixing them.

[0022] <Stirring process> This process involves stirring a mixture of Cu(HCOO)2·4H2O powder and (CH3)2C(NH2)CH2OH solid matter using the thin film swirling method. The thin film swirling method involves pressing the material to be dispersed against the inner wall of a processing vessel using centrifugal force, forming a thin cylindrical film that is then rotated at high speed. The shear stress generated by the centrifugal force and the speed difference with the inner wall of the processing vessel acts on the material, dispersing it within the thin cylindrical material.

[0023] (mixer) The agitator that can be used in the agitation step is equipped with a container having an inner wall surface and a rotating member that rotates slightly inside the inner wall surface, and 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 from 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. The top of the container 310 is provided with an outlet 315 connected to the upper space 312a, 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] Rotating member 330 is in the form of a cylindrical member 332 having an outer circumferential surface 331 that faces inner wall surface 311 via a small gap S of about 1 to 3 mm in lower space 312b, and is supported by rotating shaft 350 via support member 352. This cylindrical member 332 also has a plurality of holes 333 formed therethrough that penetrate inward and outward.

[0029] It is desirable that at least cylindrical member 332 of rotating member 330 is formed of a material having excellent abrasion resistance, such as fine ceramics, or that outer peripheral surface 331 of cylindrical member 332 is coated with a material having excellent abrasion resistance, such as fine ceramics. Similarly, at least the region of inner wall surface 311 of container 310 that faces rotating member 330 across 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] Rotating member 330 can be rotated at high speeds, for example, so that the peripheral speed of rotating member 330 (relative speed with respect to inner wall surface 311) is 0.1 m / s to 50 m / s. To rotate rotating member 330 at such a peripheral speed while still providing a stirring effect, a high-torque, high-output motor is required, and the dimensions of container 310 and rotating member 330 are selected in accordance with the available motor. When the peripheral speed of rotating member 330 is constant, the processing capacity of this high-speed mixer 300 is approximately proportional to the area of ​​outer peripheral surface 331 of rotating member 330. Therefore, increasing the radial dimensions of container 310 and rotating member 330 is sufficient to increase 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 spread throughout 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 while present in the gap S between them.

[0034] (Mixing conditions) The stirring process using a stirrer allows the centrifugal force generated by the rotation of the rotating element to stir the mixture that exists in the form of a film between the rotating element and the inner wall surface, and in the stirring process, (CH3)2C(NH2)CH2OH is coordinated as a ligand to Cu in Cu(HCOO)2·4H2O to form a copper complex ((HCOO)2Cu((CH3)2C(NH2)CH2OH)2).

[0035] The specific conditions for forming a copper complex by coordinating (CH3)2C(NH2)CH2OH as a ligand to Cu in Cu(HCOO)2·4H2O are as follows: the peripheral speed of the rotating member is 0.5 m / s to 21.0 m / s, the temperature of the mixture is 10°C to 30°C, and the stirring time of the mixture is 5 to 500 minutes.

[0036] <Circumferential speed of rotating member> When the peripheral speed of the rotating element is set to 0.5 m / s to 40.0 m / s, the mixture, which exists in a film-like form between the outer surface of the cylindrical element and the inner wall 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. This velocity gradient causes the mixture to be continuously subjected to powerful shear forces, and this powerful energy achieves a remarkably 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 are no particular limitations on the upper limit of 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 constant 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 mixture temperature during stirring between 10°C and 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 between 10°C and 30°C. Furthermore, if the mixture temperature rises rapidly above 50°C, coordination bond formation will also progress rapidly, so it is important to carefully monitor the mixture while stirring. While a temperature below 10°C does not affect the reaction, the effort and energy required for cooling to below 10°C is required, which is costly and 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 stirring the mixture for 5 to 500 minutes, (CH3)2C(NH2)CH2OH can be sufficiently coordinated to Cu(HCOO)2.

[0040] Conventional copper complex inks tend to have precipitated particles immediately after production, or precipitated particles that occur over time after production, with the number of particles increasing. Copper wiring produced using copper complex ink with a large amount of precipitated particles has a high volume resistivity and poor smoothness. However, according to the production 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 produced copper complex ink, it is possible to form copper wiring with a low volume resistivity and high smoothness.

[0041] The stirring conditions may be such that 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. 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 by the present invention contains a copper complex represented by the general formula (HCOO)2Cu((CH3)2C(NH2)CH2OH)2. It may also contain solvents and additives 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. I would like to add.

[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% 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 allows 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 within 7 days after 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 in the copper complex ink, the lower the volume resistivity and the more smooth the copper wiring that can be produced.

[0048] In the copper complex ink produced according to the present invention, even if precipitated particles are present, the maximum particle size of the precipitated particles is 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 low.

[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 smoother 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 -1 In this case, the viscosity may be 1 to 10 Pa·s. A viscosity of 1 to 10 Pa·s allows the copper complex ink to pass through the screen with ease, resulting in excellent screen printing properties. If the viscosity is less than 1 Pa·s, the viscosity may be too low and printing may not be possible in the shape of a wiring or the like. If the viscosity is greater than 10 Pa·s, the viscosity may be too high and the copper complex ink may not pass through the screen, resulting in printing not being possible at all.

[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 compared 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 of 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 -1The 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 a copper complex ink is used for screen printing, i.e., at high shear rates, it exhibits excellent liquid-like fluidity behavior, thereby improving screen elimination. 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 retain its printed shape. From this perspective, a value of less than 10 results in excellent printing properties, such as screen printing. Furthermore, while a value of 10 or more does not pose a problem with printing properties, if the presence ratio of precipitated particles, described below, exceeds 50 area %, this value may be greater than 10. This value can serve as a guideline for predicting the presence of precipitated particles.

[0053] [Method of manufacturing 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 materials, sintering materials, etc., and the shape, thickness, etc. can be set as desired.

[0054] <Heat Treatment Process> 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 or AMP, from the copper complex ink, and the water, if unavoidably contained in the ink, and precipitate copper particles. For example, the 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 air, and then heating at 250°C for 10 minutes.

[0056] (Other processes) The method for producing a copper film may include other steps in addition to the heat treatment step. 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] Copper films obtained by heating copper complex ink produced by conventional manufacturing methods have many fine pores, which act as electrical resistance, resulting in 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, copper films obtained by the copper complex ink produced by the manufacturing method of the present invention can have the properties of low volume resistivity and high smoothness. High smoothness leads to excellent conductivity and durability. For example, copper films with volume resistivity of less than 100 μΩ·cm and average film roughness Sa of less than 6 μm can be obtained. [Example]

[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] [Manufacturing copper complex ink] Example 1 (Mixing process) A 10 g mixture was prepared by mixing powdered Cu(HCOO)2·4H2O (copper formate tetrahydrate) and solid (CH3)2C(NH2)CH2OH (2-aminomethylpropanol) in a molar ratio of 1:2. No grinding step was performed to crush the Cu(HCOO)2·4H2O powder, and no pre-heating step was performed to liquidify the (CH3)2C(NH2)CH2OH.

[0060] (Mixing process) The stirring process employed the thin film swirling method, using a thin film swirling high-speed mixer (Filmix (registered trademark) FM-30-L, manufactured by Primix Corporation) as the stirrer. 10 g of the mixture was placed in the stirrer's container and stirred, and (CH3)2C(NH2)CH2OH was coordinated as a ligand to Cu in Cu(HCOO)2·4H2O to produce a copper complex ink.

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

[0062] Table 1 shows the molar ratio of Cu(HCOO)2·4H2O (copper formate tetrahydrate) and (CH3)2C(NH2)CH2OH (2-aminomethylpropanol), the amount of the mixture charged, the presence or absence of a grinding step and a liquefaction treatment of (CH3)2C(NH2)CH2OH, and the stirring speed, peripheral speed, temperature of the mixture, and treatment time in the stirring step. Similarly, the conditions for Examples 2 to 5 and Comparative Examples 1 to 12 are also shown in Table 1.

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

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

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

[0066] Example 5 (Crushing process) Prior to the mixing step, a grinding step was carried out to grind the Cu(HCOO)2·4H2O powder. Specifically, the Cu(HCOO)2·4H2O lumps were ground using a mortar until they were completely powdered and free of lumps. Then, the mixing and stirring steps were carried out under the same conditions as in Example 4 to produce the copper complex ink.

[0067] Comparative Example 1 (Crushing process) Before the mixing process, a grinding process was carried out to grind the Cu(HCOO)2·4H2O powder. Specifically, the Cu(HCOO)2·4H2O lumps were ground using a mortar until they were completely powdered and free of lumps.

[0068] (Mixing process) A 30 ml screw cap tube containing a stirrer was charged with solid (CH3)2C(NH2)CH2OH, which was then heated to 45 °C to liquefy the solid. Then, while stirring, Cu(HCOO)2·4H2O (copper formate tetrahydrate) powder was added to the screw cap tube and mixed to prepare a 10 g mixture of Cu(HCOO)2·4H2O (copper formate tetrahydrate) and (CH3)2C(NH2)CH2OH (2-aminomethylpropanol) in a molar ratio of 1:2.

[0069] (Mixing process) For the stirring process, 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 (CH3)2C(NH2)CH2OH was coordinated as a ligand to Cu in Cu(HCOO)2·4H2O to produce a copper complex ink.

[0070] The stirring conditions were as follows: the stirrer rotation speed was 500 rpm, the temperature of the mixture was maintained at 45°C, and stirring was continued for 1440 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 mixture was not heated but the temperature was changed from 45°C to room temperature, and the stirring treatment time was set to 1,440 minutes.

[0074] Comparative Example 5 The conditions were the same as those of Comparative Example 3, except that the (CH3)2C(NH2)CH2OH was not previously heated to form a liquid. Because the liquidization process was not performed, the temperature of the mixture was room temperature (5°C to 35°C), and the (CH3)2C(NH2)CH2OH was in a solid state. Therefore, even when stirring with a REXIM RSH-4DN hot stirrer, a copper complex ink could not be produced.

[0075] Comparative Example 6 (Crushing process) Before the mixing process, a grinding process was carried out to grind the Cu(HCOO)2·4H2O powder. Specifically, the Cu(HCOO)2·4H2O lumps were ground using a mortar until they were completely powdered and free of lumps.

[0076] (Mixing process) A 300 ml beaker was charged with solid (CH3)2C(NH2)CH2OH, which was then heated to 45°C to liquefy the solid. Then, Cu(HCOO)2·4H2O (copper formate tetrahydrate) powder was added to the beaker and mixed to prepare 100 g of a 1:2 molar mixture of Cu(HCOO)2·4H2O (copper formate tetrahydrate) and (CH3)2C(NH2)CH2OH (2-aminomethylpropanol).

[0077] (Mixing process) In the stirring process, motor stirring was adopted instead of the thin film swirling 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 (CH3)2C(NH2)CH2OH was coordinated as a ligand to Cu in Cu(HCOO)2·4H2O to produce a copper complex ink.

[0078] The stirring conditions were as follows: the rotation speed of the propeller blade was 100 rpm, and the temperature of the mixture was maintained at room temperature while stirring for 1,440 minutes.

[0079] Comparative Example 7 A copper complex ink was produced under the same conditions as in Comparative Example 6, except that the (CH)C(NH)CHOH was not preliminarily heated to make it 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 A copper complex ink was produced under the same conditions as in Comparative Example 6, except that the grinding step was not performed, the (CH)C(NH)CHOH was not preliminarily heated to liquefy it, and the temperature of the mixture was maintained at 45°C.

[0082] Comparative Example 10 The conditions were the same as those of Comparative Example 6, except that a pulverization step was not performed and that the (CH3)2C(NH2)CH2OH was not previously heated to liquefy. Because the liquefaction step was not performed, the temperature of the mixture was room temperature (5°C to 35°C), and the (CH3)2C(NH2)CH2OH was in a solid state. Therefore, even when stirring with a propeller blade three-one motor, a copper complex ink could not be produced.

[0083] Comparative Example 11 (Crushing process) Before the mixing process, a grinding process was carried out to grind the Cu(HCOO)2·4H2O powder. Specifically, the Cu(HCOO)2·4H2O lumps were ground using a mortar until they were completely powdered and free of lumps.

[0084] (Mixing process) A 100 ml container was charged with solid (CH3)2C(NH2)CH2OH, which was then heated to 45°C to liquefy the solid. Then, Cu(HCOO)2·4H2O (copper formate tetrahydrate) powder was added to the container, resulting in a 10 g mixture of Cu(HCOO)2·4H2O (copper formate tetrahydrate) and (CH3)2C(NH2)CH2OH (2-aminomethylpropanol) in a molar ratio of 1:2.

[0085] (Mixing process) For the mixing process, instead of the thin film swirling method, a planetary mixer was used, and the mixer was an ARE-310 (Thinky Corporation). The container containing the mixture was placed in the ARE-310 and the mixture was stirred, and (CH3)2C(NH2)CH2OH was coordinated as a ligand to Cu in Cu(HCOO)2·4H2O to produce a copper complex ink.

[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 A copper complex ink was produced under the same conditions as in Comparative Example 11, except that the treatment of liquefying the solid (CH3)2C(NH2)CH2OH was not carried out.

[0088] [Evaluation of physical properties using copper complex ink] The produced copper complex ink was used to evaluate the following physical properties.

[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 left to stand and stored for 7 days at room temperature (5°C to 35°C). 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 specimens were sandwiched between cover glasses to ensure a uniform field of view. The presence or absence of precipitated particles was observed using a laser microscope.

[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] Examples of images observed with a laser microscope are shown in Figures 2 to 4. Figure 2 is an image of a sample with no precipitated particles, rated ◯, Figure 3 is an image of a sample with a precipitated particle presence rate of 49 area % and rated △, and Figure 4 is an image of a sample with a precipitated particle presence rate of 84 area % and rated ×.

[0092] [Table 1]

[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, although the generation of precipitated particles was observed after 7 days of storage, it 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, a good copper complex ink was produced by heating (CH3)2C(NH2)CH2OH to 45°C and liquefying the solid (Comparative Example 11). However, without this liquefaction process, the copper complex ink produced contained a large amount of precipitated particles immediately after production (Comparative Example 12). Examples 1 to 5 are easier to produce than Comparative Example 11 because they do not require the liquefaction 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 ink 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 change in viscosity and thixotropy.

[0097] Viscosity measurements were performed using an Anton Paar rheometer MCR302e with a φ25 mm disposable parallel plate. 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 -1 The viscosity was measured while increasing the shear rate to 0.01 sec. -1 Viscosity and shear rate at 100sec -1 The viscosity was measured at a shear rate of 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] [Table 2]

[0100] [Table 3]

[0101] (result) The copper complex ink of Example 2 maintained a stable viscosity from production until 180 days after storage, but the copper complex ink of Comparative Example 3 tended to show a gradual decrease in viscosity. 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] <Manufacturing of copper film> Two pieces of masking tape (Nichiban Clear Line Tape 536) approximately 100 μm thick were attached to an alumina substrate (Kyocera A476) with a 5 mm gap between them. An appropriate amount of ink was applied to the side of the alumina substrate not covered by the masking tape and smoothed with a squeegee. The masking tape was then removed, leaving a coating film approximately 100 μm thick, 5 mm wide, and 1.52 mm long 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, 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] <Volume Resistivity Measurement> Measurements were performed using a four-terminal method using a Hioki RM3548 resistance meter and pin-type leads as electrode terminals. The resistance 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 multiplying the obtained resistance value by width by thickness and dividing the length.

[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] [Table 4]

[0107] (result) 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 thus formed 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] [Table 5]

[0111] (result) 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 approximately half the value of the average film roughness Sa of Comparative Example 3 immediately after production.

[0112] <Cross-section observation of copper film using SEM> Of the copper films produced, 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). Figure 5 shows an SEM image of the cross section of the copper film in Example 2, enlarged 30,000 times, and Figure 6 shows an SEM image of the cross section of the copper film in Comparative Example 3, enlarged 30,000 times.

[0113] (result) 5 and 6, the copper particles in the copper film in Example 2 were more densely packed than those in the copper film in 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. [Industrial Applicability]

[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. [Explanation of symbols]

[0115] 300 high-speed agitator, 310 vessel, 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 peripheral 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 following formula: Cu(HCOO) ２ ・4H ２ O powder and (CH ３ ) ２ C(NH ２ ) CH ２ a stirring step of stirring the mixture of OH and a solid or liquid substance by a thin film swirling method, Cu(HCOO) in the mixture 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 includes using 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 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 penetrating in an inward-outward direction; the stirring step is a step of stirring the mixture present in a film form between the rotating member and the inner wall surface by centrifugal force generated by rotation of the rotating member, 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 are as follows: 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; The stirring time of the mixture is 5 minutes to 500 minutes. A method for producing the copper complex ink according to claim 1 .

3. 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 mixture is stirred for 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 a copper complex with a solid of OH to obtain a mixture.

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