Method for forming fine copper particle sintered product type of electric conductor having fine shape, method for forming fine copper wiring and thin copper film using said method

• US 20060210705A1
• Filed: 05/13/2004
• Published: 09/21/2006
• Est. Priority Date: 05/16/2003
• Status: Active Grant

• Current Assignee: Harima Chemicals Incorporated
• Original Assignee: Harima Chemicals Incorporated
• Inventors: Itoh, Daisuke, Hata, Noriaki, Matsuba, Yorishige, Izumitani, Akihito
• Granted Patent: US 7,820,232 B2
• Time in Patent Office: Days
• US Class Current: 427/96.100
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H05K 2201/0257 Nanoparticles inks comprising nanoparticles H05K1/097
• CPC Class Codes: H05K 2203/0315 Oxidising metal
• CPC Class Codes: H05K 2203/1131 Sintering, i.e. fusing of metal particles to achieve or improve electrical conductivity
• CPC Class Codes: H05K 2203/1157 Using means for chemical reduction
• CPC Class Codes: H05K 2203/122 Organic non-polymeric compounds, e.g. oil, wax, thiol using solvent H05K2203/0783
• CPC Class Codes: H05K 3/102 by bonding of conductive powder, i.e. metallic powder H05K3/12 takes precedence
• CPC Class Codes: H05K 3/105 by conversion of non-conductive material on or in the support into conductive material, e.g. by using an energy beam
• CPC Class Codes: H05K 3/1283 After-treatment of the printed patterns, e.g. sintering or curing methods

Abstract

The present invention provides a process for forming a copper fine particle sintered product type of a fine-shaped electric conductor showing superior electroconductivity, which comprises steps of drawing a fine pattern with the use of a dispersion containing the copper fine particles having a surface oxide film layer, conducting a treatment for reducing the copper fine particles with the surface oxide film layer or copper oxide fine particles included in the pattern at a comparatively low temperature, and baking the resultant copper fine particles. Specifically, the process carries out the processes of; applying a dispersion containing the copper fine particles having the surface oxide film layer thereon or the copper oxide fine particles with an average particle diameter of 10 μm or smaller onto a substrate; and then performing a series of the heat treatment steps of heating the particles in the coated layer at temperature of 350° C. or lower under an atmosphere containing a vapor and a gas of a compound having reducibility to reduce the oxide film by a reduction reaction which used the compound having reducibility as a reducing agent, subsequently repeating a heat treatment combining an oxidizing treatment of a short time with a re-reducing treatment, and sintering the resultant copper fine particles with each other to form a layer of the sintered product.

Claims

1. A process for forming a copper-based fine pattern made of a sintered product layer of copper nano-particles sintered with each other, which process comprises the steps of:

drawing a layer coated on a substrate, which has a fine pattern, by using a dispersion containing copper nano-particles provided with a surface oxide film layer or copper oxide nano-particles, which have an average particle diameter of 1 to 100 nm, and

subjecting the copper nano-particles with the surface oxide film layer or the copper oxide nano-particles contained in the coated layer to a reducing treatment wherein the surface oxide film layer or copper oxides are reduced, and further a baking treatment wherein the nano-particles resulting from the reducing treatment are baked to form a sintered product layer of the nano-particles in the fine pattern,

wherein said reducing treatment and the baking treatment are carried out in a single step which is conducted by heating the copper nano-particles provided with the surface oxide film layer or the copper oxide nano-particles contained in the coated layer in the presence of an organic compound having reducibility at a heating temperature of 300°

C. or lower, thereby giving rise to the action of said organic compound having reducibility on said nano-particles.

2. The process according to claim 1, wherein in the copper nano-particles with the surface oxide film layer contained in the dispersion, said surface oxide film layer comprises at least cuprous oxide, cupric oxide or a mixture thereof, and the nano-particles are particles each containing two or more selected from the group consisting of cuprous oxide, cupric oxide, a mixture of the foregoin, and metallic copper.

3. The process according to claim 1, wherein said organic compound having reducibility is an organic compound having a hydroxyl group that is transformable to an oxo group (═

O) or a formyl group (—

CHO) by oxidation, or a mixture containing two or more types thereof.

4. The process according to claim 1, wherein said organic compound having reducibility is selected from an organic compound having an alcoholic hydroxyl group, or a mixture containing two or more types thereof.

5. The process according to claim 1, wherein said organic compound having reducibility is selected from an organic compound having two or more hydroxyl groups, or a mixture containing two or more types thereof.

6. The process according to claim 1, wherein said organic compound having reducibility is glycerin (1,2,3-propanetriol).

7. The process according to claim 1, wherein at least one of said organic compound having reducibility is blended in the dispersion containing the copper nano-particles with the surface oxide film layer or the copper oxide nano-particles.

8. The process according to claim 1, wherein in the reducing step, at least one of said organic compound having reducibility is vaporized to act on the coated layer having the fine pattern in vapor phase of the at least one organic compound.

9. The process according to claim 1, wherein in the coated layer having the fine pattern drawn on the substrate,

a minimum width of a line of the pattern is selected from a range of 0.5 to 200 μ

m, and a minimum distance between adjacent lines of the pattern is selected from a range of 0.5 to 200 μ

m, and

the average particle diameter of the copper nano-particles with the surface oxide film layer or the copper oxide nano-particles contained in the dispersion is selected from values of 1/10 or less of the minimum width of wiring and the minimum distance between the adjacent lines of the pattern.

10. The process according to claim 1, wherein the drawing step is conducted by a screen-printing method, an ink-jet method or a transferring method.

30. The process according to claim 1, wherein the copper-based fine pattern is a copper-based fine pattern for wiring of a plated circuit.

11-18. -18. (canceled)

20. (canceled)

22. (canceled)

23. A process for forming a copper thin-film layer made of a product layer composed of copper fine particles sintered with each other, wherein the process comprises the steps of:

drawing a layer coated on a substrate by using a dispersion containing copper fine particles provided with a surface oxide film layer or copper oxide fine particles, which have an average particle diameter of 10 μ

m or less, and

subjecting the copper fine particles with the surface oxide film layer or the copper oxide fine particles contained in the coated layer to a reducing treatment wherein the surface oxide film layer or copper oxides are reduced, and further a baking treatment wherein the fine particles resulting from the reducing treatment are baked to form a sintered product layer of the copper fine particles,

wherein said reducing treatment and the baking treatment comprise the following two steps that are executed sequentially in a single process at a heating temperature of 350°

C. or lower;

a first treatment step of heating the copper fine particles with the surface oxide film layer or the copper oxide fine particles contained in the coated layer for duration of 1 min. to 15 min. in the presence of an organic compound having reducibility to give rise to the action of said organic compound having reducibility thereon, and thereby reducing the copper fine particles with the surface oxide film layer or the copper oxides composing the copper oxide fine particles to provide copper fine particles; and

a second treatment step of subjecting said copper fine particles obtained in the first treatment step, to a combined treatment of oxidation/re-reduction at least one time, which includes an stage of subjecting the copper fine particles to a surface oxidization treatment by heating the particles for 30 seconds or shorter under an atmosphere containing oxygen to give rise to the action of oxygen thereon, and then an stage of subjecting said copper fine particles which have undergone the surface oxidization treatment, to a re-reduction treatment by heating the particles for 30 seconds or longer but 300 seconds or shorter under an atmosphere containing gas or vapor of said compound having reducibility to give rise to the action of said compound having reducibility thereon.

21. The process according to claim 23, wherein the copper thin-film layer is a sintered product layer of the copper fine particles being shaped into a predetermined plane-view pattern, wherein in said sintered product layer of the copper fine particles, a minimum film thickness is selected from a range of 0.1 to 20 μ

m, a maximum film thickness is selected from a range of 100 μ

m or smaller, and a minimum width of a line of the plane-view pattern is selected from a range of 0.5 to 200 μ

m.

24. The process according to claim 21, wherein in the copper fine particles with the surface oxide film layer contained in the dispersion, said surface oxide film layer comprises at least cuprous oxide, cupric oxide or a mixture thereof, and the fine particles are particles each containing two or more selected from the group consisting of cuprous oxide, cupric oxide, a mixture of the foregoing, and metallic copper.

25. The process according to claim 21, wherein said organic compound having reducibility used in said first treatment step and said second treatment step is an organic compound having a hydroxyl group that is transformable to an oxo group (═

O) or a formyl group (—

CHO) by oxidation, or a mixture containing two or more types thereof.

26. The process according to claim 21, wherein said organic compound having reducibility used in said first treatment step and said second treatment step in the is a polyvalent alcohol compound having two or more hydroxyl groups in a molecule, or a mixture containing two or more types thereof.

27. The process according to claim 21, wherein said organic compound having reducibility used in said first treatment step and said second treatment step is a hydrogen molecule.

28. The process according to claim 21, wherein said organic compound having reducibility used in said first treatment step and said second treatment step is any one of glycerin (1,2,3-propanetriol), ethylene glycol (1,2-ethanediol), propylene glycol (1,2-propanediol) and 1,3-propanediol.

29. The process according to claim 21, wherein a dispersing solvent contained in the dispersion containing the copper fine particles with the surface oxide film layer or the copper oxide fine particles is an alcoholic compound having a melting point of 10°

C. or lower, and a hydroxyl group which is transformable to an oxo group (═

O) or a formyl group (—

CHO) by oxidation.

31. The process according to claim 23, wherein the copper thin-film layer is a fine copper-based wiring pattern.