KR101766426B1 - Method for forming copper layer - Google Patents

Abstract

Disclosed is a method of manufacturing a copper layer on a substrate. According to a specific example of the present invention, a copper formate paste is manufactured by mixing copper formate powder with a solvent; and the manufactured copper formate paste is printed on one substrate of a glass substrate, a ceramic substrate, and a silicon substrate using screen printing process. By performing heat treatment in a nitrogen environment, a pure copper layer having an adhesive force on a substrate is formed such that a manufacturing process is able to be simplified. Accordingly, manufacturing costs are able to be reduced, and the copper layer with much higher conductivity is able to be obtained by increasing a density and thickness of the manufactured copper layer by a following copper plating process.

Description

[0001] METHOD FOR FORMING COPPER LAYER [0002]

More particularly, the present invention relates to a method of manufacturing a copper layer, and more particularly, to a method of manufacturing a copper layer by mixing a copper foamate powder with a solvent and then paste. The copper foamate paste is then screen printed on one of glass, A pure copper layer is formed on the substrate by printing and heat treatment to form a copper layer having a high electrical conductivity by a dense texture and thickness of the pure copper layer through a subsequent copper plating process to form a pure copper wiring or pad The present invention relates to a technique for manufacturing a substrate having a low cost.

Generally, a method of forming a conductive metal layer in a low-cost printing process when manufacturing electronic parts, for example, a process of printing a metal paste and then performing a heat treatment (firing or sintering) is used. In this case, a conductive paste mainly composed of silver (Ag) is mainly used because the low resistivity characteristic of silver and excellent oxidation resistance enable stable low electric resistance characteristic after heat treatment.

In this case, silver (Ag) is added to the paste in the form of powder, and the paste can be produced with or without a resin component such as an epoxy. In the former case, But it is inevitable to reduce the electrical conductivity due to the resin component. In any case, silver (Ag) is used as a material for forming conductive wirings in electronic parts because of its high price, and it is gradually losing its competitiveness and utilizing low-cost metal such as copper (Cu) or nickel Research is continuing.

However, since copper and nickel are oxidized not only in the atmosphere but also in an inert atmosphere such as nitrogen or argon, the electric resistance value of the wiring can be greatly increased after the heat treatment.

On the other hand, the formation of the copper wiring on the glass, ceramic and silicon substrate can be accomplished by vacuum deposition of an adhesive layer such as titanium (Ti) or chromium (Cr) after a photo lithography process and then continuously depositing a copper layer a lift off method in which a resist is removed, a method in which an adhesive layer such as titanium or chrome and a copper layer are successively vacuum-deposited, and a photolithography process is performed thereon and patterning is performed through etching, there is a method of producing a paste in which a paste of glass frit powder is mixed, pattern printing is performed on the paste, and sintering heat treatment is performed to form a copper layer on the substrate.

However, when the photolithography method is used, there is a disadvantage that the manufacturing process is very complicated and the price competitiveness is poor. In the case of using the glass frit, the composition of the final product layer is not pure copper.

The applicant of the present invention synthesized a copper formate powder to prepare a paste, printed on one of glass, ceramics and silicon by a screen printing method, and heat treated in a nitrogen atmosphere to form a pure copper layer having an adhesive force on a substrate The formation process of the pure copper layer bonded to one of the substrates of glass, ceramics and silicon can be extremely simplified and the fine structure and thickness of the copper layer produced through the additional copper plating process can be increased, We propose a method to maximize the conductivity.

SUMMARY OF THE INVENTION The present invention has been made to solve all the problems of the prior art, and an object of the present invention is to provide a copper foaming paste, which comprises a copper foamate powder mixed with a solvent to prepare a copper foamate paste, Ceramics, and silicon, and a pure copper film is adhered on the substrate by heat treatment in a nitrogen atmosphere to form a copper layer, and a substrate of one of glass, ceramics and silicon A pure copper film is bonded to a copper layer to simplify the manufacturing process and to increase the density and thickness of the copper layer through an additional copper plating process to maximize electrical conductivity. .

Technical Solution In order to achieve the above object,

A copper formate powder producing process for producing a copper formate powder;

A paste manufacturing process for producing a copper formate-based paste by mixing a copper formate powder with a solvent;

A copper layer forming step of printing the copper formate paste on the surface of one of the cleaned glass, ceramics and silicon and then performing heat treatment in a nitrogen atmosphere to bond the pure copper film to the substrate to form a copper layer .

Preferably, the copper foamate powder is produced by mixing copper oxide, formic acid, and a grinding ball, followed by milling to form a copper formate; Charging the synthesized copper formate with a washing solvent, and then filtering with a filter paper; And drying the filtered copper formate in a vacuum to form a copper formate powder.

Preferably, the milling step in the copper foamate powder manufacturing process may be performed in a jar rotating at 200 to 300 rpm. In the copper formate powder manufacturing process, the washing solvent may be isopropyl alcohol (isopropanol) Ethanol, methanol, distilled water, or a mixed solution thereof. The ultrasonic bath may be used for washing. In the copper foamate powder manufacturing process, the drying step may be performed at a temperature of 40 to 70 ° C Temperature range.

Preferably, the paste manufacturing process may include mixing and mixing the dried copper formate powder with a solvent to produce a copper formate-based paste. Preferably, the solvent of the paste manufacturing process is selected from the group consisting of terpineol, isopropyl alcohol, ethanol, methanol, butanol, glycerol, diethylene glycol, ethyl acetate, butyl acetate, propyl acetate, methyl ethyl ketone, benzene, tetradecane, toluene and distilled water One or a mixed solution thereof may be used.

Preferably, the copper layer forming process may be performed by printing the copper foil-based paste on the cleaned substrate, then heat-treating the pure copper layer to form a copper layer on the substrate. The printing method in the copper layer forming step is most preferably a screen printing method when patterning is used, but may be performed by one of doctor blade coating method, spin coating method and spray coating method when patterning is unnecessary. In the screen printing method, the thickness of the screen is preferably in the range of 1 μm to 100 μm, and the thickness of the copper layer after printing may range from 0.1 μm to 0.9 μm.

Preferably, the heat treatment in the copper layer forming step may be carried out in a nitrogen atmosphere at a sintering temperature ranging from 230 ° C to 300 ° C for a time ranging from 10 minutes to 2 hours, have.

Preferably further comprising a post-treatment step in which the substrate on which the copper layer has been formed can be secondly cleaned and then further plated with pure copper by immersion in a copper plating solution to increase the density of the resulting copper layer and increase the thickness of the copper layer can do. The plating process may be performed by electroless plating or electrolytic plating.

According to the present invention, after a copper foaming paste is prepared by mixing a copper foamate powder with a solvent, the copper foams paste is printed on glass, ceramics and silicon by a screen printing method and heat-treated in a nitrogen atmosphere By forming a pure copper layer adhered in the form of a film on the substrate, the manufacturing process can be simplified in forming a pure copper layer bonded on one of glass, ceramics and silicon, The effect can be obtained.

In addition, according to the present invention, the density and thickness of the copper layer are increased by the subsequent copper plating process, so that excellent electric conductivity can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further understand the technical idea of the invention. And should not be construed as limiting.
FIG. 1 is a flowchart showing a copper layer manufacturing method according to an embodiment of the present invention.
2 is a flowchart showing a detailed configuration of a process for producing copper formate powder in a copper layer manufacturing method according to an embodiment of the present invention.
3 is a flowchart showing a detailed configuration of a pure copper layer forming process in a copper layer manufacturing method according to an embodiment of the present invention.
FIG. 4 is a SEM image showing the appearance and appearance of the copper formate powder produced in the copper layer manufacturing method according to the embodiment of the present invention.
FIG. 5 is a view showing an XRD pattern of a copper formate powder produced in a copper layer manufacturing method according to an embodiment of the present invention.
FIG. 6 is a graph showing the adhesive strength of the copper layer formed according to the blending ratio of copper formate and terpineol solvent in the copper layer manufacturing method according to the embodiment of the present invention.
7 is a SEM image of a surface and a cross-sectional view of the copper layer produced in the copper layer manufacturing method according to the embodiment of the present invention.
8 is a view showing an XRD pattern of a generated metal layer according to a heat treatment time in a copper layer manufacturing method according to an embodiment of the present invention.
9 is a graph showing a change in the thickness of the copper layer produced in the copper layer manufacturing method according to the embodiment of the present invention.
FIG. 10 is a graph showing the adhesion of the copper layer formed according to the heat treatment temperature in the copper layer manufacturing method according to the embodiment of the present invention.
11 and 12 are SEM images of the surface and side cross-section of the copper layer formed on each substrate in the copper layer manufacturing method according to the embodiment of the present invention.
13 is a SEM image of a copper layer after electroless copper plating in the copper layer manufacturing method according to an embodiment of the present invention.
14 is a view showing an XRD pattern of a copper layer after an electroless copper plating process in a copper layer manufacturing method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, a method of forming a metal thin film using copper formate according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flow chart showing a copper layer manufacturing method according to an embodiment of the present invention, FIG. 2 is a diagram showing a detailed configuration of the copper foamate powder manufacturing process 100 shown in FIG. 1, 1 to 3, a method of manufacturing a copper layer according to an embodiment of the present invention includes mixing a copper foamate powder with a solvent The copper formate paste thus prepared is printed on one of glass, ceramics and silicon substrates by a screen printing method and heat-treated in a nitrogen atmosphere to obtain pure copper Layer, and the method of manufacturing the pure copper layer on one of the glass, the ceramic and the silicon may include a copper formate powder manufacturing process 100, a paste manufacturing process 200, And a copper layer forming process 300.

The copper formate powder manufacturing process 100 is a process for producing copper formate powder by mixing 23 g of copper oxide having a purity of 95% and 103.52 ml of formic acid having a purity of 85% and a grinding ball having a tap volume of 86.27 ml through steps 101 and 103 at 300 rpm At 25 DEG C for 5 hours to prepare a copper formate.

Then, the copper formate synthesized in the steps (105) and (107) was repeatedly washed with a washing solvent (preferably isopropyl alcohol), filtered through filter paper, and dried in a vacuum state at 50 ° C for 7 hours to obtain a copper formate powder Can be produced.

Here, the washing solvent may be used as one of isopropyl alcohol, ethanol, methanol, and distilled water, or a mixture thereof.

Then, the paste manufacturing process 200 may mix and dry the dried copper formate powder with a solvent to produce a copper formate-based paste. The solvent may be one of terpineol, isopropyl alcohol, ethanol, methanol, butanol, glycerol, diethylene glycol, ethyl acetate, butyl acetate, propyl acetate, methyl ethyl ketone, benzene, tetradecane, toluene, Can be used.

After the copper foil paste is printed on the cleaned substrate by a screen printing method, the heating temperature may be elevated to 10 ° C per minute in a nitrogen atmosphere, and then heat-treated at a sintering temperature of 250 ° C for 30 minutes or more 301, 303). A pure copper film is then bonded on one of the substrates of glass, ceramic, and silicon to form a copper layer.

Examples of the material of the substrate include glass, ceramics, silicon, and the like. Particularly, ceramics can be used as an oxide such as alumina (Al ₂ O ₃ ) or silica (SiO ₂ ), a nitride such as aluminum nitride (AlN) SiC), or the like may be used.

The printing method describes a screen printing method capable of patterning. However, when patterning is unnecessary, the printing method can be used in accordance with a usual method, for example, a doctor blade coating method, a spin coating method, a spray coating method, have. The screen thickness may range from 1 [mu] m to 100 [mu] m.

On the other hand, the heat treatment can be performed in a nitrogen atmosphere, but is not limited thereto. For example, the heat treatment may be performed in an inert gas such as nitrogen and argon, a reducing gas such as hydrogen, and a mixed atmosphere thereof.

Next, the method for manufacturing a copper layer of the present invention is characterized in that the substrate having the copper layer formed in the copper layer forming step 300 is washed and then charged into a copper plating solution to further coat pure copper by electroless plating or electrolytic plating And a post-treatment process (400) in which the electrical conductivity is increased by increasing the density and thickness of the copper layer.

≪ Example 1 >

First, 23 g of copper oxide having a purity of 95%, 103.52 ml of formic acid having a purity of 85%, and a grinding ball having a tap volume of 86.27 ml were mixed and milled at 25 DEG C for 5 hours at 300 rpm to prepare a copper formate powder. The formate was synthesized, and the synthesized copper formate was repeatedly washed with isopropyl alcohol, filtered with a filter paper, and then dried in a vacuum state at 50 ° C for 7 hours.

The obtained SEM (Scanning Electron Microscope) image and X-ray diffraction (XRD) pattern for the copper formate powder are shown in FIGS. 4 and 5. That is, it can be confirmed from the SEM analysis that the size of the copper formate powder has a size of 284 nm to 826 nm.

Then, copper formate paste was prepared by mixing 50 wt% of copper formate powder and 50 wt% of terpinol solvent, and then printed on a soda lime glass substrate by a screen printing method. Then, in a nitrogen atmosphere The heating temperature was raised to 10 ° C per minute and the film was annealed at a sintering temperature of 250 ° C for 60 minutes to form a pure copper film layer adhered on a soda lime glass substrate. The analysis is shown in FIG. From the cross cut test analysis according to the mixing ratio of the copper formate copper powder and the terpineol solvent, it was confirmed that the adhesion strength of the copper layer prepared by the above method was maximum in the mixing condition of the copper formate powder of 60 wt% and the terpineol solvent of 40 wt% . Referring to FIG. 6, it can be seen that when the copper formate powder accounts for 60 to 70 parts by weight, the adhesive strength is good.

But the present invention is not limited to this, for example, by analyzing the adhesive force through a conventional cross cut test analysis.

Then, the state of the surface of the produced copper layer and the state of the cutting surface are analyzed by SEM image and shown in FIG. 7, and XRD pattern analysis is shown in FIG. SEM image analysis shows that the copper layer is bonded to the glass substrate and a distinctive necking structure is formed between the fine copper particles and that the CO ₂ and H ₂ O gases generated during the phase change of the copper formate during the heat treatment It can be confirmed that the density of the copper layer is low, but the structure is comparatively uniform and the reproducibility is high. From the XRD analysis, it can be confirmed that the copper formate disappears from the retention time of 5 minutes at the sintering temperature of 250 ° C, and only pure copper is produced.

The change in the thickness of the resulting copper layer is shown in Fig. That is, from the copper layer thickness change analysis, the thickness of the copper layer was in the range of 260.8 to 592.3 nm.

The paste was prepared by mixing the 60 wt% copper formate powder and the 40 wt% terpineol solvent prepared in the above-described example, and then printed on a soda lime glass substrate by a screen printing method. Then, 250 As shown in FIG. 10, from the analysis of the resistivity characteristics of the copper layer obtained by the heat treatment for 30 minutes at the sintering temperature of 0.degree. C., the sheet resistance was 0.30? / Sq. As measured by a four point probe. , And the specific resistance is 14.77 [micro] [Omega] .cm.

On the other hand, SEM images of the surface and cross-section of the copper layer obtained by printing the copper formate paste prepared in the above-mentioned embodiment on the aluminum nitride and silicon wafer by screen printing method and then heat-treating them are shown in FIGS. 11 and 12, respectively. SEM image analysis showed that both the aluminum nitride and silicon wafers were bonded to the copper layer and the necking structure was formed between the fine copper particles.

≪ Example 2 >

0.75 g of kappa sulfate pentahydrate having a purity of 99%, 1.46 g of tetrasodium dithiophosphate having a purity of 98.5%, 0.1 g of 2,2-bipyridyl, 0.03 g of polyethylene glycol, and 0.3 g of propaldehyde having a purity of 99.5% (PH = 12.5) mixed with 500 ml of distilled water was heated to 60 ° C, and the sodalime glass substrate on which the copper layer prepared in Example 1 was formed was charged for 3 minutes to further coat pure copper The resistivity was measured.

As shown in the following table, it was confirmed that the surface resistance was greatly reduced after electroless copper plating.

Before electroless plating process After electroless plating process Sheet Resistance 0.295463? / Sq 0.08441 Ω / sq

The SEM image of the surface of the copper layer obtained through the addition of the electroless copper plating process is as shown in FIG. 13, and the XRD analysis result is shown in FIG. From the SEM image and XRD analysis, the copper layer produced by the above-mentioned method shows that the microstructure becomes dense and the thickness thereof is increased, and copper formate still does not exist and only pure copper exists.

Accordingly, the copper layer manufacturing method according to an embodiment of the present invention is a method of manufacturing a copper foil paste by mixing a copper foamate powder with a solvent to prepare a copper foamate paste, then coating the copper foamate paste by glass printing, By printing on one of the silicon substrates and forming a film-like pure copper layer having an adhesive force on the substrate by heat treatment in a nitrogen atmosphere, the manufacturing process can be simplified, the manufacturing cost can be reduced, By increasing the density and thickness of the copper layer to the subsequent copper plating process, it is possible to obtain excellent electrical conductivity.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. will be. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by all changes or modifications derived from the scope of the appended claims and equivalents of the following claims.

A copper formate-based paste is prepared by mixing a copper foamate powder with a solvent, and then the produced copper formate-based paste is printed on one of glass, ceramic and silicon substrates by a screen printing method and heat-treated in a nitrogen atmosphere By forming a film-like pure copper layer having an adhesive force on the substrate, the manufacturing process can be simplified, thereby lowering the manufacturing cost, and by increasing the density and thickness of the resulting copper layer to a subsequent copper plating process, The copper layer manufacturing method which can obtain the electric conductivity is a completely new process which has not been reported before, and copper layers such as pure copper wires and pads can be formed on glass, ceramics and silicon substrates and the conventional photolithographic process, By eliminating the vacuum deposition process and the use of the adhesive layer, By eliminating the use of resin, it is possible to secure the film structure of the excellent electrical conductivity of only the metal (copper) layer and the shape bonded on the substrate, In the field of semiconductors, automobile modules, ICT devices, medical devices, intelligent robots and the like, it is a technology that can be practically and clearly practiced in manufacturing parts using glass, ceramics or silicon substrates, .

Claims (10)

A milling step of mixing copper oxide, formic acid, and a grinding ball followed by milling to produce a copper formate;
A paste manufacturing process for producing a copper formate based paste by mixing the copper formate powder with a solvent so that the copper formate powder accounts for 60 to 70 parts by weight of the total paste;
The copper formate paste is printed on the surface of one of the cleaned glass, ceramic, and silicon and then heat-treated in a nitrogen atmosphere to change the copper formate to copper in its entirety and form a necking structure between the copper particles, A copper layer forming step of forming a film layer of a copper layer bonded onto the substrate; And
And a post-treatment step of charging the copper-layer-formed substrate into the copper plating solution to further coat the copper layer with copper to increase the density of the copper layer formed and increase the thickness of the copper layer Lt; / RTI >
The process for producing a copper foil powder according to claim 1,
Washing the copper formate synthesized in the milling step for preparing the copper formate, washing the copper formate, and filtering the copper formate with the filter paper; And
And drying the filtered copper formate in a vacuum to form a copper formate powder.
The method according to claim 1, wherein in the copper foamate powder manufacturing process, In the step,
Is carried out in a jar rotating at 200 to 300 rpm.
[3] The method of claim 2, wherein the cleaning solvent in the copper foamate powder manufacturing process is one of isopropyl alcohol (isopropanol), ethanol, methanol, distilled water, or a mixture thereof.
The method according to claim 2, wherein the drying step in the copper foamate powder production step is performed in a vacuum state at a temperature ranging from 40 ° C to 70 ° C.
The method according to claim 1,
And mixing and mixing the dried copper formate powder with a solvent to produce a copper formate-based paste.

7. The process of claim 6, wherein the solvent in the paste manufacturing process comprises
And is a mixture of one or more of terpineol, isopropyl alcohol, ethanol, methanol, butanol, glycerol, diethylene glycol, ethyl acetate, butyl acetate, propyl acetate, methyl ethyl ketone, benzene, tetradecane, toluene and distilled water By weight.
The method according to claim 1,
The copper foil paste is printed on a cleaned substrate and then heat treated to form a film-like pure copper layer on the substrate,
Wherein the printing method is performed by a screen printing method when patterning is required and is performed by one of a doctor blade coating method, a spin coating method and a spray coating method when patterning is unnecessary.
9. The method according to claim 8,
The thickness of the screen ranges from 1 m to 100 m,
Wherein the thickness of the copper layer after printing is in the range of 0.1 mu m to 0.9 mu m.
The method according to claim 1,
Wherein the plating process is performed by electroless plating or electrolytic plating.

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