Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Utilizing magnet or magnetic field during coating
Reexamination Certificate
1999-08-31
2001-08-14
Gorgos, Kathryn (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Utilizing magnet or magnetic field during coating
C205S148000, C427S304000, C427S443100, C427S598000
Reexamination Certificate
active
06274022
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of producing electro- or electroless-deposited film with a controlled crystal orientation and, in particular, to a method for controlling the crystal orientation in order to provide improved product properties.
2. Description of Related Art
A thin film is conventionally deposited and developed on a substrate by various deposition method, including a wet method such as electro- or electroless-deposition method, and a dry method such as sputtering method, PVD method, CVD method and the like. Among other things, in the wet method, a material (e.g., metal) in electrolytic solution assumes an ionic state and is deposed on a substrate to form a thin film by electro-deposition method or electroless-deposition method. In this instance, it is desirable to control the crystal orientation of the deposited film to improve the product property of the film. The crystal orientation of the deposited film is generally controlled by:
(1) orienting crystals of the deposited film into conformity with the crystal orientation of the substrate, or
(2) subjecting the deposited film to stresses through the substrate,
(3) controlling an overvoltage applied to the electro-deposition environment.
The method (1) above is generally known as epitaxial method, and requires no particular explanations. The method (2) above is usually seen when stresses are added to the substrate during the deposition process due to a difference in terms of the coefficient of thermal expansion between the substrate and the deposited film. Furthermore, the method (3) above utilizes a phenomenon wherein an easy axis of the crystals in the deposited material, in which electro-deposition tends to readily occur, changes depending upon the applied overvoltage. For example, in the case of an electro-deposited Zn film, the crystals of the deposited Zn film are oriented into the c-axis when the overvoltage is low, and into the a-axis or b-axis under an increased overvoltage.
Beside the above-mentioned methods (1), (2) and (3), there may be instances wherein the crystal orientation of the deposited film is controlled by controlling temperature of the substrate or the temperature or flow of the electrolytic solution, etc.
However, these methods suffer from a serious problem that they can be applied only to specific substances. Moreover, while the known method for developing the deposited film allows the development of a deposited film comprising crystals oriented in a thermodynamically stable direction, it is still difficult, if not impossible, to develop a deposited film comprising crystals which are oriented in other direction.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method of producing electro- or electroless-deposited film with a controlled crystal orientation, which can be widely applied without being limited to specific materials or to specific crystal orientation of the deposited film.
In general, a substance has magnetism and is classified into magnetic material and non-magnetic material. The magnetic material refers to ferromagnetic body, while the non-magnetic material refers to paramagnetic body or diamagnetic body. Moreover, a crystal of the substance has different magnetic susceptibility according to the crystal orientation. Therefore, when the material having different magnetic susceptibility according to the crystal orientation is electro- or electroless-deposited on a substrate while applying a magnetic field, the deposited crystals of the material on the substrate are oriented so that the direction of the crystal orientation having a higher magnetic susceptibility is in parallel with the direction in which the magnetic field is applied. Such a phenomenon is utilized in the present invention.
According to the invention, a material to be electro- or electroless-deposited is made to have an ionic state in a conventional manner and is then aggregated, electro-deposited or electroless-deposited on a substrate. A magnetic field is applied to the electro-deposition or electroless-deposition environment, i.e., an environment which surrounds the substrate and the material in electrolytic state.
Since the crystals of the substance have magnetic anisotropy, when the substance is electro- or electroless-deposited while being applied with a magnetic field, the crystals of the deposited substance are oriented on the substrate, with the crystal orientation having a higher magnetic susceptibility being in parallel with the direction in which the magnetic field is applied. Therefore, by applying the magnetic field so that the crystals of the deposited substance on the substrate are oriented to have the desired crystal orientation according to the invention, it is possible to obtain a deposition film having a desired crystal orientation.
In the method according to the present invention, it is preferred that a porous plate is arranged adjacent to the substrate so as to suppress a flow of an electrolytic solution which occurs during the application of the magnetic field. Such a porous plate serves to improve the property of the crystal orientation, since the flow of the electrolytic solution is suppressed by the porous plate during the electro- or electroless-deposition.
The material to be subjected to the electro- or electroless-deposition may be a paramagnetic material or diamagnetic material. Even such materials can be formed into a thin film having a desired crystal orientation, by adequately controlling the direction of the magnetic field. This is because a magnetic anisotropy is inherent not only to a ferromagnetic body, but also to a paramagnetic body or a diamagnetic body. In this instance, it is preferred that the magnetic field has an intensity which is at least on the order of 7 T, preferably on the order of 10 T.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1
a
and
FIG. 1
b
are schematic views showing a typical arrangement of an electro-deposition apparatus which can be suitably used for carrying out the method according to the invention;
FIG. 2
a
and
FIG. 2
b
are explanatory views showing the principle of controlling the orientation of metallic crystal by applying a magnetic field;
FIG. 3
a
is a chart showing the crystal orientation property of an electro-deposited Zn film obtained while applying a magnetic field in accordance with the invention; and
FIG. 3
b
is a similar chart showing the crystal orientation property of another electro-deposited Zn film obtained without applying a magnetic field;
FIG. 4
is a graph showing a difference in the crystal orientation property of electro-deposited Zn films depending upon whether or not a magnetic field is applied, and whether or not a flow-suppression porous plate is arranged.
REFERENCES:
patent: 4244788 (1981-01-01), Faulkner
patent: 5372698 (1994-12-01), Liao
patent: 59-104495 (1984-06-01), None
patent: 7-41996 (1995-02-01), None
Asai Shigeo
Sassa Kensuke
Taniguchi Takahisa
Burr & Brown
Gorgos Kathryn
Leader William
Nagoya University
LandOfFree
Method for producing electro- or electroless-deposited film... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing electro- or electroless-deposited film..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing electro- or electroless-deposited film... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457054