Processing device for metal materials
|発明の名称 （英語）||Processing device for metal materials|
|発明の概要（英語）||A processing device for a metal material, containing: an airtight container for housing a specimen thereinside; an oxygen pump for extracting oxygen molecules from a gas discharged from the airtight container; a circulation means for returning the gas into the airtight container; and a plasma generation means present inside the airtight container for converting the gas returned from the circulation means into plasma and exposing the specimen thereto.|
In a common method of industrially forming an electronic circuit, films of electronic materials, such as metal, semiconductor and insulator formed on one surface of a substrate are processed by photolithography.That is, processing is repeated in which a photoresist is applied onto the film, exposure and development are performed to leave the photoresist at portions required by the circuit, unnecessary electronic material is removed by etching, and the remaining photoresist is also removed.In such processing, a large amount of electronic material is wasted, and treatment of electronic and resist waste materials is also necessary, so that process entails high environmental load.
Consequently, from the viewpoint of resource and energy conservation, electronic circuit fabrication methods that utilize printing as a technology for depositing required amounts of materials at required places have recently attracted attention.
In such a technology, ink or paste containing metal fine particles is used to form the electronic circuit wiring, and a wiring pattern is formed on the substrate by one of various printing techniques, such as inkjet or screen printing.As this ink or paste is liquid, it therefore contains a solvent in addition to the metal fine particles, and generally further contains a dispersing agent for preventing aggregation of the metal fine particles, a binder for ensuring adhesion onto the substrate, and organic matter, such as the solvent for adjusting viscosity of the liquid.Accordingly, after the wiring pattern is formed, it is necessary to decompose these organic matters by heat treatment to form a conducting path among the metal fine particles.As the substrate on which printing is applied, plastics having flexibility are preferred, so that the heat treatment temperature must be lowered below the heat-resistance temperature limit of the plastic (for example, 200° C. or so below).
Examples of resins having high heat resistance include polyimide (which can be used at 260° C. or higher).However, polyimide is expensive in comparison with other plastics.Therefore, it is desirable to reduce the heat treatment temperature to about 180° C. or lower, preferably 120° C. or lower, so that use can be made of comparatively low cost plastics, for example, polyethylene naphthalate (PEN, maximum service temperature, about 180° C.) or polyethylene terephthalate (PET, maximum service temperature, about 120° C.).
With regard to an ink or paste containing fine particles of silver as metal, various products have been developed that can exhibit satisfactory electrical conductivity by applying low temperature heat treatment in the air (Patent Literature 1).Meanwhile, in the case of copper, if the heat treatment is applied in the air, copper oxide, which is an insulator, is formed, so that wiring having good electrical conductivity cannot be obtained.In order to avoid this problem, the ambience of the copper particles is required to be somehow made, at least locally, a reducing atmosphere during calcinating treatment.
As a means therefor, the following methods are known:
(1) heat treatment in a reducing gas of some kind, such as hydrogen (Non-Patent Literature 1), formic acid vapor (Patent Literature 2) or an ultralow oxygen atmosphere (Patent Literature 3, Patent Literature 4, Non-Patent Literature 2); and
(2) heat treatment upon using ink from which a reducing gas is generated from an ink component, such as copper formate, by thermal decomposition in an oxygen-blocked environment (Non-Patent Literature 3, Patent Literature 5).
15. A processing device for a metal material, comprising:
an airtight container for housing a specimen thereinside;
an oxygen pump for extracting oxygen molecules from a gas discharged from the airtight container;
a circulation means for returning the gas into the airtight container; and
a plasma generation means present inside the airtight container for converting the gas returned from the circulation means into plasma and exposing the specimen thereto.
16. The device according to claim 15, further comprising a heater for heating the gas returned from the circulation means.
17. The device according to claim 15, comprising a specimen stage for holding the specimen inside the airtight container.
18. The device according to claim 17, wherein the specimen stage includes a heater for heating the specimen.
19. The device according to claim 15, wherein the circulation means pressurizes the gas discharged from the airtight container and returns the gas into the airtight container.
20. The device according to claim 15, wherein the metal material is fine particles of metal or metal compound.
21. The device according to claim 15, wherein both sintering and reducing of the metal material, or either sintering or reducing thereof, can be performed.
22. The device according to claim 15, wherein total pressure of the gas returned from the circulation means and converted into plasma is 0.1 atm or more and less than 10 atm in terms of absolute pressure.
23. The device according to claim 15, wherein metal constituting the metal material is copper.
24. The device according to claim 15, wherein the gas contains nitrogen.
25. The device according to claim 15, wherein oxygen partial pressure in the gas returned into the airtight container is 10－25 atm or less.
26. The device according to claim 15, wherein the oxygen pump comprises a solid electrolyte body having oxygen ion conductivity and electrodes arranged inside the body and outside the body.
27. The device according to claim 26, wherein the solid electrolyte body is made of stabilized zirconia.
28. The device according to claim 26, wherein the electrode is a porous electrode along the surfaces of the solid electrolyte body.
|参考情報 （研究プロジェクト等）||Flexible Electronics Research Center, AIST|
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